Host-Toxoplasma gondii Coadaptation Leads to Fine Tuning of the Immune Response.

PubMed

Brasil, Thaís Rigueti; Freire-de-Lima, Celio Geraldo; Morrot, Alexandre; Vetö Arnholdt, Andrea Cristina

2017-01-01

Toxoplasma gondii has successfully developed strategies to evade host's immune response and reach immune privileged sites, which remains in a controlled environment inside quiescent tissue cysts. In this review, we will approach several known mechanisms used by the parasite to modulate mainly the murine immune system at its favor. In what follows, we review recent findings revealing interference of host's cell autonomous immunity and cell signaling, gene expression, apoptosis, and production of microbicide molecules such as nitric oxide and oxygen reactive species during parasite infection. Modulation of host's metalloproteinases of extracellular matrix is also discussed. These immune evasion strategies are determinant to parasite dissemination throughout the host taking advantage of cells from the immune system to reach brain and retina, crossing crucial hosts' barriers.

Yersinia versus host immunity: how a pathogen evades or triggers a protective response.

PubMed

Chung, Lawton K; Bliska, James B

2016-02-01

The human pathogenic Yersinia species cause diseases that represent a significant source of morbidity and mortality. Despite this, specific mechanisms underlying Yersinia pathogenesis and protective host responses remain poorly understood. Recent studies have shown that Yersinia disrupt cell death pathways, perturb inflammatory processes and exploit immune cells to promote disease. The ensuing host responses following Yersinia infection include coordination of innate and adaptive immune responses in an attempt to control bacterial replication. Here, we highlight current advances in our understanding of the interactions between the pathogenic yersiniae and host cells, as well as the protective host responses mobilized to counteract these pathogens. Together, these studies enhance our understanding of Yersinia pathogenesis and highlight the ongoing battle between host and microbe. Copyright © 2015 Elsevier Ltd. All rights reserved.

Calcineurin Orchestrates Lateral Transfer of Aspergillus fumigatus during Macrophage Cell Death.

PubMed

Shah, Anand; Kannambath, Shichina; Herbst, Susanne; Rogers, Andrew; Soresi, Simona; Carby, Martin; Reed, Anna; Mostowy, Serge; Fisher, Matthew C; Shaunak, Sunil; Armstrong-James, Darius P

2016-11-01

Pulmonary aspergillosis is a lethal mold infection in the immunocompromised host. Understanding initial control of infection and how this is altered in the immunocompromised host are key goals for comprehension of the pathogenesis of pulmonary aspergillosis. To characterize the outcome of human macrophage infection with Aspergillus fumigatus and how this is altered in transplant recipients on calcineurin inhibitor immunosuppressants. We defined the outcome of human macrophage infection with A. fumigatus, as well as the impact of calcineurin inhibitors, through a combination of single-cell fluorescence imaging, transcriptomics, proteomics, and in vivo studies. Macrophage phagocytosis of A. fumigatus enabled control of 90% of fungal germination. However, fungal germination in the late phagosome led to macrophage necrosis. During programmed necroptosis, we observed frequent cell-cell transfer of A. fumigatus between macrophages, which assists subsequent control of germination in recipient macrophages. Lateral transfer occurred through actin-dependent exocytosis of the late endosome in a vasodilator-stimulated phosphoprotein envelope. Its relevance to the control of fungal germination was also shown by direct visualization in our zebrafish aspergillosis model in vivo. The calcineurin inhibitor FK506 (tacrolimus) reduced cell death and lateral transfer in vitro by 50%. This resulted in uncontrolled fungal germination in macrophages and also resulted in hyphal escape. These observations identify programmed, necrosis-dependent lateral transfer of A. fumigatus between macrophages as an important host strategy for controlling fungal germination. This process is critically dependent on calcineurin. Our studies provide fundamental insights into the pathogenesis of pulmonary aspergillosis in the immunocompromised host.

Struggle for space: viral extinction through competition for cells.

PubMed

Cuesta, José A; Aguirre, Jacobo; Capitán, José A; Manrubia, Susanna C

2011-01-14

The design of protocols to suppress the propagation of viral infections is an enduring enterprise, especially hindered by limited knowledge of the mechanisms leading to viral extinction. Here we report on infection extinction due to intraspecific competition to infect susceptible hosts. Beneficial mutations increase the production of viral progeny, while the host cell may develop defenses against infection. For an unlimited number of host cells, a feedback runaway coevolution between host resistance and progeny production occurs. However, physical space limits the advantage that the virus obtains from increasing offspring numbers; thus, infection clearance may result from an increase in host defenses beyond a finite threshold. Our results might be relevant to devise improved control strategies in environments with mobility constraints or different geometrical properties.

A strain-cue hypothesis for biological network formation

PubMed Central

Cox, Brian N.

2011-01-01

The direction of migration of a cell invading a host population is assumed to be controlled by the magnitude of the strains in the host medium (cells plus extracellular matrix) that arise as the host medium deforms to accommodate the invader. The single assumption that invaders are cued by strains external to themselves is sufficient to generate network structures. The strain induced by a line of invaders is greatest at the extremity of the line and thus the strain field breaks symmetry, stabilizing branch formation. The strain cue also triggers sprouting from existing branches, with no further model assumption. Network characteristics depend primarily on the ratio of the rate of advance of the invaders to the rate of relaxation of the host cells after their initial deformation. Intra-cell mechanisms that govern these two rates control network morphology. The strain field that cues an individual invader is a collective response of the combined cell populations, involving the nearest 100 cells, to order of magnitude, to any invader. The mechanism does not rely on the pre-existence of the entire host medium prior to invasion; the host cells need only maintain a layer several cells thick around each invader. Consistent with recent experiments, networks result only from a strain cue that is based on strain magnitudes. Spatial strain gradients do not break symmetry and therefore cannot stabilize branch formation. The theory recreates most of the geometrical features of the nervous network in the mouse gut when the most influential adjustable parameter takes a value consistent with one inferred from human and mouse amelogenesis. Because of similarity in the guiding local strain fields, strain cues could also be a participating factor in the formation of vascular networks. PMID:20671068

A Viral Pilot for HCMV Navigation?

PubMed

Adler, Barbara

2015-07-15

gH/gL virion envelope glycoprotein complexes of herpesviruses serve as entry complexes and mediate viral cell tropism. By binding additional viral proteins, gH/gL forms multimeric complexes which bind to specific host cell receptors. Both Epstein-Barr virus (EBV) and human cytomegalovirus (HCMV) express alternative multimeric gH/gL complexes. Relative amounts of these alternative complexes in the viral envelope determine which host cells are preferentially infected. Host cells of EBV can modulate the gH/gL complex complement of progeny viruses by cell type-dependent degradation of one of the associating proteins. Host cells of HCMV modulate the tropism of their virus progenies by releasing or not releasing virus populations with a specific gH/gL complex complement out of a heterogeneous pool of virions. The group of Jeremy Kamil has recently shown that the HCMV ER-resident protein UL148 controls integration of one of the HCMV gH/gL complexes into virions and thus creates a pool of virions which can be routed by different host cells. This first mechanistic insight into regulation of the gH/gL complex complement of HCMV progenies presents UL148 as a pilot candidate for HCMV navigation in its infected host.

Effects of long non-coding RNA HOST2 on cell migration and invasion by regulating MicroRNA let-7b in breast cancer.

PubMed

Lu, Peng-Wei; Li, Lin; Wang, Fang; Gu, Yuan-Ting

2018-06-01

The study intends to investigate the effects of long non-coding RNA HOST2 (lncRNA HOST2) on cell migration and invasion by regulating microRNA let-7b (let-7b) in breast cancer. Breast cancer and adjacent normal tissues were collected from 98 patients with breast cancer. Breast cancer MCF-7 cells were divided into the blank, negative control (NC), pcDNA3-Mock, siHOST2, let-7b inhibitor, pcDNA3-HOST2, let-7b mimic, pcDNA3-HOST2 + let-7b mimic, and siHOST2 + let-7b inhibitor groups. RT-qPCR was used to detect the mRNA expressions of HOST2, let-7b, and c-Myc. Western blotting was conducted to measure the c-Myc expression. Scratch test and Transwell assay were applied to detect the cell motility, migration, and invasion. Xenograft tumor in nude mice was performed to evaluate the effect of different transfection on the tumor growth. Compared with adjacent normal tissues, HOST2 expression was higher but let-7b expression lower in breast cancer tissues. HOST2 expression in breast cancer cells was remarkably increased compared with that in the normal breast epithelial MCF-10A cells. In MCF-7 cells, in comparison with the blank and NC groups, expressions of HOST2 and c-Myc were reduced, but let-7b expression was remarkably elevated in the siHOST2 and let-7b mimic groups; the let-7b inhibitor group exhibited higher expressions of HOST2 and c-Myc but lower let-7b expression. Overexpression of HOST2 could promote cell motility, migration and invasion, thus enhancing the growth of breast cancer tumor. By inhibiting HOST2, opposite trends were found. LncRNA HOST2 promotes cell migration and invasion by inhibiting let-7b in breast cancer patients. © 2017 Wiley Periodicals, Inc.

Regulatory T cells in the control of host-microorganism interactions (*).

PubMed

Belkaid, Yasmine; Tarbell, Kristin

2009-01-01

Each microenvironment requires a specific set of regulatory elements that are finely and constantly tuned to maintain local homeostasis. Various populations of regulatory T cells contribute to the maintenance of this equilibrium and establishment of controlled immune responses. In particular, regulatory T cells limit the magnitude of effector responses, which may result in failure to adequately control infection. However, regulatory T cells also help limit collateral tissue damage caused by vigorous antimicrobial immune responses against pathogenic microbes as well as commensals. In this review, we describe various situations in which the balance between regulatory T cells and effector immune functions influence the outcome of host-microorganism coexistence and discuss current hypotheses and points of polemic associated with the origin, target, and antigen specificity of both endogenous and induced regulatory T cells during these interactions.

Fungal Strategies to Evade the Host Immune Recognition.

PubMed

Hernández-Chávez, Marco J; Pérez-García, Luis A; Niño-Vega, Gustavo A; Mora-Montes, Héctor M

2017-09-23

The recognition of fungal cells by the host immune system is key during the establishment of a protective anti-fungal response. Even though the immune system has evolved a vast number of processes to control these organisms, they have developed strategies to fight back, avoiding the proper recognition by immune components and thus interfering with the host protective mechanisms. Therefore, the strategies to evade the immune system are as important as the virulence factors and attributes that damage the host tissues and cells. Here, we performed a thorough revision of the main fungal tactics to escape from the host immunosurveillance processes. These include the composition and organization of the cell wall, the fungal capsule, the formation of titan cells, biofilms, and asteroid bodies; the ability to undergo dimorphism; and the escape from nutritional immunity, extracellular traps, phagocytosis, and the action of humoral immune effectors.

Chicken macrophages infected with Salmonella (S.) Enteritidis or S. heidelberg produce differential responses in immune and metabolic signaling pathways

USDA-ARS?s Scientific Manuscript database

Protein kinases act in coordination with phosphatases to control protein phosphorylation and regulate signaling pathways and cellular processes involved in nearly every functions of cell life. Salmonella are known to manipulate the host kinase network to gain entrance and survive inside host cells....

F4/80+ Host Macrophages Are a Barrier to Murine Embryonic Stem Cell-Derived Hematopoietic Progenitor Engraftment In Vivo.

PubMed

Thompson, Heather L; van Rooijen, Nico; McLelland, Bryce T; Manilay, Jennifer O

2016-01-01

Understanding how embryonic stem cells and their derivatives interact with the adult host immune system is critical to developing their therapeutic potential. Murine embryonic stem cell-derived hematopoietic progenitors (ESHPs) were generated via coculture with the bone marrow stromal cell line, OP9, and then transplanted into NOD.SCID.Common Gamma Chain (NSG) knockout mice, which lack B, T, and natural killer cells. Compared to control mice transplanted with adult lineage-negative bone marrow (Lin - BM) progenitors, ESHP-transplanted mice attained a low but significant level of donor hematopoietic chimerism. Based on our previous studies, we hypothesized that macrophages might contribute to the low engraftment of ESHPs in vivo . Enlarged spleens were observed in ESHP-transplanted mice and found to contain higher numbers of host F4/80 + macrophages compared to BM-transplanted controls. In vivo depletion of host macrophages using clodronate-loaded liposomes improved the ESHP-derived hematopoietic chimerism in the spleen but not in the BM. F4/80 + macrophages demonstrated a striking propensity to phagocytose ESHP targets in vitro . Taken together, these results suggest that macrophages are a barrier to both syngeneic and allogeneic ESHP engraftment in vivo .

Candida albicans triggers interleukin-6 and interleukin-8 responses by oral fibroblasts in vitro.

PubMed

Dongari-Bagtzoglou, A; Wen, K; Lamster, I B

1999-12-01

Oral candidiasis is the most frequent opportunistic infection associated with an immunocompromised host. Production of proinflammatory cytokines, such as interleukin-6 (IL-6) and IL-8, by host cells in response to Candida albicans can be expected to have a major impact in the activation of immune effector cells against the invading microorganism. Using a human cell--C. albicans coculture model system, we determined that this microorganism can trigger secretion of these potent chemoattractant and proinflammatory cytokines by oral mucosal fibroblasts. This response varied depending on the infecting strain and required fungal viability, germination of yeast into hyphae and mannose-mediated direct contact between the host cell and Candida. The secretion of proinflammatory cytokines by oral mucosal fibroblasts in response to C. albicans suggests that these cells have the potential to enhance the host defense against this organism in vivo. This may have important implications in controlling fungal overgrowth in the oral cavity.

Pre-existing malignancy results in increased prevalence of distinct populations of CD4+ T cells during sepsis.

PubMed

Xie, Jianfeng; Robertson, Jennifer M; Chen, Ching-Wen; Zhang, Wenxiao; Coopersmith, Craig M; Ford, Mandy L

2018-01-01

The presence of pre-existing malignancy in murine hosts results in increased immune dysregulation and risk of mortality following a septic insult. Based on the known systemic immunologic changes that occur in cancer hosts, we hypothesized that the presence of pre-existing malignancy would result in phenotypic and functional changes in CD4+ T cell responses following sepsis. In order to conduct a non-biased, unsupervised analysis of phenotypic differences between CD4+ T cell compartments, cohorts of mice were injected with LLC1 tumor cells and tumors were allowed to grow for 3 weeks. These cancer hosts and age-matched non-cancer controls were then subjected to CLP. Splenocytes were harvested at 24h post CLP and flow cytometry and SPADE (Spanning-tree Progression Analysis of Density-normalized Events) were used to analyze populations of CD4+ cells most different between the two groups. Results indicated that relative to non-cancer controls, cancer mice contained more resting memory CD4+ T cells, more activated CD4+ effectors, and fewer naïve CD4+ T cells during sepsis, suggesting that the CD4+ T cell compartment in cancer septic hosts is one of increased activation and differentiation. Moreover, cancer septic animals exhibited expansion of two distinct subsets of CD4+ T cells relative to previously healthy septic controls. Specifically, we identified increases in both a PD-1hi population and a distinct 2B4hi BTLAhi LAG-3hi population in cancer septic animals. By combining phenotypic analysis of exhaustion markers with functional analysis of cytokine production, we found that PD-1+ CD4+ cells in cancer hosts failed to make any cytokines following CLP, while the 2B4+ PD-1lo cells in cancer mice secreted increased TNF during sepsis. In sum, the immunophenotypic landscape of cancer septic animals is characterized by both increased CD4+ T cell activation and exhaustion, findings that may underlie the observed increased mortality in mice with pre-existing malignancy following sepsis.

Pre-existing malignancy results in increased prevalence of distinct populations of CD4+ T cells during sepsis

PubMed Central

Xie, Jianfeng; Robertson, Jennifer M.; Chen, Ching-wen; Zhang, Wenxiao

2018-01-01

The presence of pre-existing malignancy in murine hosts results in increased immune dysregulation and risk of mortality following a septic insult. Based on the known systemic immunologic changes that occur in cancer hosts, we hypothesized that the presence of pre-existing malignancy would result in phenotypic and functional changes in CD4+ T cell responses following sepsis. In order to conduct a non-biased, unsupervised analysis of phenotypic differences between CD4+ T cell compartments, cohorts of mice were injected with LLC1 tumor cells and tumors were allowed to grow for 3 weeks. These cancer hosts and age-matched non-cancer controls were then subjected to CLP. Splenocytes were harvested at 24h post CLP and flow cytometry and SPADE (Spanning-tree Progression Analysis of Density-normalized Events) were used to analyze populations of CD4+ cells most different between the two groups. Results indicated that relative to non-cancer controls, cancer mice contained more resting memory CD4+ T cells, more activated CD4+ effectors, and fewer naïve CD4+ T cells during sepsis, suggesting that the CD4+ T cell compartment in cancer septic hosts is one of increased activation and differentiation. Moreover, cancer septic animals exhibited expansion of two distinct subsets of CD4+ T cells relative to previously healthy septic controls. Specifically, we identified increases in both a PD-1hi population and a distinct 2B4hi BTLAhi LAG-3hi population in cancer septic animals. By combining phenotypic analysis of exhaustion markers with functional analysis of cytokine production, we found that PD-1+ CD4+ cells in cancer hosts failed to make any cytokines following CLP, while the 2B4+ PD-1lo cells in cancer mice secreted increased TNF during sepsis. In sum, the immunophenotypic landscape of cancer septic animals is characterized by both increased CD4+ T cell activation and exhaustion, findings that may underlie the observed increased mortality in mice with pre-existing malignancy following sepsis. PMID:29338031

A Viral Pilot for HCMV Navigation?

PubMed Central

Adler, Barbara

2015-01-01

gH/gL virion envelope glycoprotein complexes of herpesviruses serve as entry complexes and mediate viral cell tropism. By binding additional viral proteins, gH/gL forms multimeric complexes which bind to specific host cell receptors. Both Epstein–Barr virus (EBV) and human cytomegalovirus (HCMV) express alternative multimeric gH/gL complexes. Relative amounts of these alternative complexes in the viral envelope determine which host cells are preferentially infected. Host cells of EBV can modulate the gH/gL complex complement of progeny viruses by cell type-dependent degradation of one of the associating proteins. Host cells of HCMV modulate the tropism of their virus progenies by releasing or not releasing virus populations with a specific gH/gL complex complement out of a heterogeneous pool of virions. The group of Jeremy Kamil has recently shown that the HCMV ER-resident protein UL148 controls integration of one of the HCMV gH/gL complexes into virions and thus creates a pool of virions which can be routed by different host cells. This first mechanistic insight into regulation of the gH/gL complex complement of HCMV progenies presents UL148 as a pilot candidate for HCMV navigation in its infected host. PMID:26184287

Virus and Host Mechanics Support Membrane Penetration and Cell Entry

PubMed Central

2016-01-01

Viruses are quasi-inert macromolecular assemblies. Their metastable conformation changes during entry into cells, when chemical and mechanical host cues expose viral membrane-interacting proteins. This leads to membrane rupture or fusion and genome uncoating. Importantly, virions tune their physical properties and enhance penetration and uncoating. For example, influenza virus softens at low pH to uncoat. The stiffness and pressure of adenovirus control uncoating and membrane penetration. Virus and host mechanics thus present new opportunities for antiviral therapy. PMID:26842477

Defects in intracellular trafficking of fungal cell wall synthases lead to aberrant host immune recognition.

PubMed

Esher, Shannon K; Ost, Kyla S; Kohlbrenner, Maria A; Pianalto, Kaila M; Telzrow, Calla L; Campuzano, Althea; Nichols, Connie B; Munro, Carol; Wormley, Floyd L; Alspaugh, J Andrew

2018-06-01

The human fungal pathogen, Cryptococcus neoformans, dramatically alters its cell wall, both in size and composition, upon entering the host. This cell wall remodeling is essential for host immune avoidance by this pathogen. In a genetic screen for mutants with changes in their cell wall, we identified a novel protein, Mar1, that controls cell wall organization and immune evasion. Through phenotypic studies of a loss-of-function strain, we have demonstrated that the mar1Δ mutant has an aberrant cell surface and a defect in polysaccharide capsule attachment, resulting in attenuated virulence. Furthermore, the mar1Δ mutant displays increased staining for exposed cell wall chitin and chitosan when the cells are grown in host-like tissue culture conditions. However, HPLC analysis of whole cell walls and RT-PCR analysis of cell wall synthase genes demonstrated that this increased chitin exposure is likely due to decreased levels of glucans and mannans in the outer cell wall layers. We observed that the Mar1 protein differentially localizes to cellular membranes in a condition dependent manner, and we have further shown that the mar1Δ mutant displays defects in intracellular trafficking, resulting in a mislocalization of the β-glucan synthase catalytic subunit, Fks1. These cell surface changes influence the host-pathogen interaction, resulting in increased macrophage activation to microbial challenge in vitro. We established that several host innate immune signaling proteins are required for the observed macrophage activation, including the Card9 and MyD88 adaptor proteins, as well as the Dectin-1 and TLR2 pattern recognition receptors. These studies explore novel mechanisms by which a microbial pathogen regulates its cell surface in response to the host, as well as how dysregulation of this adaptive response leads to defective immune avoidance.

First Evidence for the Disease-Stage, Cell-Type, and Virus Specificity of microRNAs during Human Immunodeficiency Virus Type-1 Infection

PubMed Central

Fowler, Lauren; Conceicao, Viviane; Perera, Suneth S.; Gupta, Priyanka; Chew, Choo Beng; Dyer, Wayne B.; Saksena, Nitin K.

2016-01-01

The potential involvement of host microRNAs (miRNAs) in HIV infection is well documented, and evidence suggests that HIV modulates and also dysregulates host miRNAs involved in maintaining the host innate immune system. Moreover, the dysregulation of host miRNAs by HIV also effectively interferes directly with the host gene expression. In this study, we have simultaneously evaluated the expression of host miRNAs in both CD4+ and CD8+ T-cells derived from HIV-positive (HIV+) individuals (viremic and aviremic individuals while receiving highly active antiretroviral therapy (HAART), therapy-naïve long-term non-progressors (LTNP), and HIV-negative (HIV–) healthy controls. miRNAs were run on Affymetrix V2 chips, and the differential expression between HIV+ and HIV− samples, along with intergroup comparisons, was derived using PARTEK software, using an FDR of 5% and an adjusted p-value < 0.05. The miR-199a-5p was found to be HIV-specific and expressed in all HIV+ groups as opposed to HIV– controls. Moreover, these are the first studies to reveal clearly the highly discriminatory miRNAs at the level of the disease state, cell type, and HIV-specific miRNAs. PMID:29083374

The role of B cells and humoral immunity in Mycobacterium tuberculosis infection.

PubMed

Chan, John; Mehta, Simren; Bharrhan, Sushma; Chen, Yong; Achkar, Jacqueline M; Casadevall, Arturo; Flynn, JoAnne

2014-12-01

Mycobacterium tuberculosis remains a major public health burden. It is generally thought that while B cell- and antibody-mediated immunity plays an important role in host defense against extracellular pathogens, the primary control of intracellular microbes derives from cellular immune mechanisms. Studies on the immune regulatory mechanisms during infection with M. tuberculosis, a facultative intracellular organism, has established the importance of cell-mediated immunity in host defense during tuberculous infection. Emerging evidence suggest a role for B cell and humoral immunity in the control of intracellular pathogens, including obligatory species, through interactions with the cell-mediated immune compartment. Recent studies have shown that B cells and antibodies can significantly impact on the development of immune responses to the tubercle bacillus. In this review, we present experimental evidence supporting the notion that the importance of humoral and cellular immunity in host defense may not be entirely determined by the niche of the pathogen. A comprehensive approach that examines both humoral and cellular immunity could lead to better understanding of the immune response to M. tuberculosis. Copyright © 2014 Elsevier Ltd. All rights reserved.

The role of B cells and humoral immunity in Mycobacterium tuberculosis infection

PubMed Central

Chan, John; Mehta, Simren; Bharrhan, Sushma; Chen, Yong; Achkar, Jacqueline M.; Casadevall, Arturo; Flynn, JoAnne

2014-01-01

Mycobacterium tuberculosis remains a major public health burden. It is generally thought that while B cell- and antibody-mediated immunity plays an important role in host defense against extracellular pathogens, the primary control of intracellular microbes derives from cellular immune mechanisms. Studies on the immune regulatory mechanisms during infection with M. tuberculosis, a facultative intracellular organism, has established the importance of cell-mediated immunity in host defense during tuberculous infection. Emerging evidence suggest a role for B cell and humoral immunity in the control of intracellular pathogens, including obligatory species, through interactions with the cell-mediated immune compartment. Recent studies have shown that B cells and antibodies can significantly impact on the development of immune responses to the tubercle bacillus. In this review, we present experimental evidence supporting the notion that the importance of humoral and cellular immunity in host defense may not be entirely determined by the niche of the pathogen. A comprehensive approach that examines both humoral and cellular immunity could lead to better understanding of the immune response to M. tuberculosis. PMID:25458990

Chromatin reorganisation in Epstein-Barr virus-infected cells and its role in cancer development.

PubMed

West, Michelle J

2017-10-01

The oncogenic Epstein-Barr virus (EBV) growth transforms B cells and drives lymphoma and carcinoma development. The virus encodes four key transcription factors (EBNA2, EBNA3A, EBNA3B and EBNA3C) that hijack host cell factors to bind gene control elements and reprogramme infected B cells. These viral factors predominantly target long-range enhancers to alter the expression of host cell genes that control B cell growth and survival and facilitate virus persistence. Enhancer and super-enhancer binding by these EBNAs results in large-scale reorganisation of three-dimensional enhancer-promoter architecture to drive the overexpression of oncogenes, the silencing of tumour suppressors and the modulation of transcription, cell-cycle progression, migration and adhesion. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Immune subversion by chromatin manipulation: a 'new face' of host-bacterial pathogen interaction.

PubMed

Arbibe, Laurence

2008-08-01

Bacterial pathogens have evolved various strategies to avoid immune surveillance, depending of their in vivo'lifestyle'. The identification of few bacterial effectors capable to enter the nucleus and modifying chromatin structure in host raises the fascinating questions of how pathogens modulate chromatin structure and why. Chromatin is a dynamic structure that maintains the stability and accessibility of the host DNA genome to the transcription machinery. This review describes the various strategies used by pathogens to interface with host chromatin. In some cases, chromatin injury can be a strategy to take control of major cellular functions, such as the cell cycle. In other cases, manipulation of chromatin structure at specific genomic locations by modulating epigenetic information provides a way for the pathogen to impose its own transcriptional signature onto host cells. This emerging field should strongly influence our understanding of chromatin regulation at interphase nucleus and may provide invaluable openings to the control of immune gene expression in inflammatory and infectious diseases.

The effect of immunodeficiency on the evolution of virulence: an experimental test with the rodent malaria Plasmodium chabaudi.

PubMed

Barclay, Victoria C; Kennedy, David A; Weaver, Veronika C; Sim, Derek; Lloyd-Smith, James O; Read, Andrew F

2014-08-01

Host immunity plays an important role in the evolution of pathogen virulence and disease emergence. There is increasing theoretical and empirical evidence that enhanced immunity through vaccination may have the unfortunate side effect of selecting for more virulent parasites, but the effect of host immune suppression on pathogen evolution is less clear. Here, we use serial passage experiments in mice to test how immune-suppressed hosts may alter pathogen virulence evolution. We passaged Plasmodium chabaudi through CD4(+) T cell-depleted or control mice every 7 days for 20 weeks and then measured virulence differences during infection of immunologically normal mice. We found that those parasites that had been selected through CD4(+) T cell-depleted mice were more virulent than parasites selected through control mice. Virulence increases during serial passage are believed to be caused by pathogen adaptation to the passage host. These data suggest that immune-suppressed hosts could provide a within-host environment that lowers the barrier to parasite adaptation and promotes the evolution of virulence.

In vivo inhibition of tryptophan catabolism reorganizes the tuberculoma and augments immune-mediated control of Mycobacterium tuberculosis

PubMed Central

Gautam, Uma S.; Foreman, Taylor W.; Bucsan, Allison N.; Veatch, Ashley V.; Alvarez, Xavier; Adekambi, Toidi; Golden, Nadia A.; Gentry, Kaylee M.; Doyle-Meyers, Lara A.; Didier, Peter J.; Blanchard, James L.; Kousoulas, K. Gus; Lackner, Andrew A.; Kalman, Daniel; Rengarajan, Jyothi; Khader, Shabaana A.; Kaushal, Deepak

2018-01-01

Mycobacterium tuberculosis continues to cause devastating levels of mortality due to tuberculosis (TB). The failure to control TB stems from an incomplete understanding of the highly specialized strategies that M. tuberculosis utilizes to modulate host immunity and thereby persist in host lungs. Here, we show that M. tuberculosis induced the expression of indoleamine 2,3-dioxygenase (IDO), an enzyme involved in tryptophan catabolism, in macrophages and in the lungs of animals (mice and macaque) with active disease. In a macaque model of inhalation TB, suppression of IDO activity reduced bacterial burden, pathology, and clinical signs of TB disease, leading to increased host survival. This increased protection was accompanied by increased lung T cell proliferation, induction of inducible bronchus-associated lymphoid tissue and correlates of bacterial killing, reduced checkpoint signaling, and the relocation of effector T cells to the center of the granulomata. The enhanced killing of M. tuberculosis in macrophages in vivo by CD4+ T cells was also replicated in vitro, in cocultures of macaque macrophages and CD4+ T cells. Collectively, these results suggest that there exists a potential for using IDO inhibition as an effective and clinically relevant host-directed therapy for TB. PMID:29255022

The Influence of Programmed Cell Death in Myeloid Cells on Host Resilience to Infection with Legionella pneumophila or Streptococcus pyogenes

PubMed Central

Gamradt, Pia; Xu, Yun; Gratz, Nina; Duncan, Kellyanne; Kobzik, Lester; Högler, Sandra; Decker, Thomas

2016-01-01

Pathogen clearance and host resilience/tolerance to infection are both important factors in surviving an infection. Cells of the myeloid lineage play important roles in both of these processes. Neutrophils, monocytes, macrophages, and dendritic cells all have important roles in initiation of the immune response and clearance of bacterial pathogens. If these cells are not properly regulated they can result in excessive inflammation and immunopathology leading to decreased host resilience. Programmed cell death (PCD) is one possible mechanism that myeloid cells may use to prevent excessive inflammation. Myeloid cell subsets play roles in tissue repair, immune response resolution, and maintenance of homeostasis, so excessive PCD may also influence host resilience in this way. In addition, myeloid cell death is one mechanism used to control pathogen replication and dissemination. Many of these functions for PCD have been well defined in vitro, but the role in vivo is less well understood. We created a mouse that constitutively expresses the pro-survival B-cell lymphoma (bcl)-2 protein in myeloid cells (CD68(bcl2tg), thus decreasing PCD specifically in myeloid cells. Using this mouse model we explored the impact that decreased cell death of these cells has on infection with two different bacterial pathogens, Legionella pneumophila and Streptococcus pyogenes. Both of these pathogens target multiple cell death pathways in myeloid cells, and the expression of bcl2 resulted in decreased PCD after infection. We examined both pathogen clearance and host resilience and found that myeloid cell death was crucial for host resilience. Surprisingly, the decreased myeloid PCD had minimal impact on pathogen clearance. These data indicate that the most important role of PCD during infection with these bacteria is to minimize inflammation and increase host resilience, not to aid in the clearance or prevent the spread of the pathogen. PMID:27973535

KAPOSI’S SARCOMA–ASSOCIATED HERPESVIRUS IMMUNOEVASION AND TUMORIGENESIS: TWO SIDES OF THE SAME COIN?

PubMed Central

Moore, Patrick S.; Chang, Yuan

2013-01-01

Kaposi’s sarcoma–associated herpesvirus (KSHV) [or human herpesvirus 8 (HHV-8)] is the most frequent cause of malignancy among AIDS patients. KSHV and related herpesviruses have extensively pirated cellular cDNAs from the host genome, providing a unique opportunity to examine the range of viral mechanisms for controlling cell proliferation. Many of the viral regulatory homologs encode proteins that directly inhibit host adaptive and innate immunity. Other viral proteins target retinoblastoma protein and p53 control of tumor suppressor pathways, which also play key effector roles in intracellular immune responses. The immune evasion strategies employed by KSHV, by targeting tumor suppressor pathways activated during immune system signaling, may lead to inadvertent cell proliferation and tumorigenesis in susceptible hosts. PMID:14527293

Recombinant cells that highly express chromosomally-integrated heterologous genes

DOEpatents

Ingram, L.O.; Ohta, Kazuyoshi; Wood, B.E.

1998-10-13

Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol. 13 figs.

Recombinant cells that highly express chromosomally-integrated heterologous genes

DOEpatents

Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

1998-01-01

Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

Recombinant cells that highly express chromosomally-integrated heterologous gene

DOEpatents

Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

2007-03-20

Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

Recombinant cells that highly express chromosomally-integrated heterologous genes

DOEpatents

Ingram, Lonnie O.; Ohta, Kazuyoshi; Wood, Brent E.

2000-08-22

Recombinant host cells are obtained that comprise (A) a heterologous, polypeptide-encoding polynucleotide segment, stably integrated into a chromosome, which is under transcriptional control of an endogenous promoter and (B) a mutation that effects increased expression of the heterologous segment, resulting in enhanced production by the host cells of each polypeptide encoded by that segment, relative to production of each polypeptide by the host cells in the absence of the mutation. The increased expression thus achieved is retained in the absence of conditions that select for cells displaying such increased expression. When the integrated segment comprises, for example, ethanol-production genes from an efficient ethanol producer like Zymomonas mobilis, recombinant Escherichia coli and other enteric bacterial cells within the present invention are capable of converting a wide range of biomass-derived sugars efficiently to ethanol.

Method for fabrication of electrodes

DOEpatents

Jankowski, Alan F.; Morse, Jeffrey D.; Barksdale, Randy

2004-06-22

Described herein is a method to fabricate porous thin-film electrodes for fuel cells and fuel cell stacks. Furthermore, the method can be used for all fuel cell electrolyte materials which utilize a continuous electrolyte layer. An electrode layer is deposited on a porous host structure by flowing gas (for example, Argon) from the bottomside of the host structure while simultaneously depositing a conductive material onto the topside of the host structure. By controlling the gas flow rate through the pores, along with the process conditions and deposition rate of the thin-film electrode material, a film of a pre-determined thickness can be formed. Once the porous electrode is formed, a continuous electrolyte thin-film is deposited, followed by a second porous electrode to complete the fuel cell structure.

Ribosome profiling-guided depletion of an mRNA increases cell growth rate and protein secretion

NASA Astrophysics Data System (ADS)

Kallehauge, Thomas Beuchert; Li, Shangzhong; Pedersen, Lasse Ebdrup; Ha, Tae Kwang; Ley, Daniel; Andersen, Mikael Rørdam; Kildegaard, Helene Faustrup; Lee, Gyun Min; Lewis, Nathan E.

2017-01-01

Recombinant protein production coopts the host cell machinery to provide high protein yields of industrial enzymes or biotherapeutics. However, since protein translation is energetically expensive and tightly controlled, it is unclear if highly expressed recombinant genes are translated as efficiently as host genes. Furthermore, it is unclear how the high expression impacts global translation. Here, we present the first genome-wide view of protein translation in an IgG-producing CHO cell line, measured with ribosome profiling. Through this we found that our recombinant mRNAs were translated as efficiently as the host cell transcriptome, and sequestered up to 15% of the total ribosome occupancy. During cell culture, changes in recombinant mRNA translation were consistent with changes in transcription, demonstrating that transcript levels influence specific productivity. Using this information, we identified the unnecessary resistance marker NeoR to be a highly transcribed and translated gene. Through siRNA knock-down of NeoR, we improved the production- and growth capacity of the host cell. Thus, ribosomal profiling provides valuable insights into translation in CHO cells and can guide efforts to enhance protein production.

Intracellular pH and its response to CO2-driven seawater acidification in symbiotic versus non-symbiotic coral cells.

PubMed

Gibbin, Emma M; Putnam, Hollie M; Davy, Simon K; Gates, Ruth D

2014-06-01

Regulating intracellular pH (pHi) is critical for optimising the metabolic activity of corals, yet the mechanisms involved in pH regulation and the buffering capacity within coral cells are not well understood. Our study investigated how the presence of symbiotic dinoflagellates affects the response of pHi to PCO2-driven seawater acidification in cells isolated from Pocillopora damicornis. Using the fluorescent dye BCECF-AM, in conjunction with confocal microscopy, we simultaneously characterised the pHi response in host coral cells and their dinoflagellate symbionts, in symbiotic and non-symbiotic states under saturating light, with and without the photosynthetic inhibitor DCMU. Each treatment was run under control (pH 7.8) and CO2-acidified seawater conditions (decreasing pH from 7.8 to 6.8). After 105 min of CO2 addition, by which time the external pH (pHe) had declined to 6.8, the dinoflagellate symbionts had increased their pHi by 0.5 pH units above control levels when in the absence of DCMU. In contrast, in both symbiotic and non-symbiotic host coral cells, 15 min of CO2 addition (0.2 pH unit drop in pHe) led to cytoplasmic acidosis equivalent to 0.3-0.4 pH units irrespective of whether DCMU was present. Despite further seawater acidification over the duration of the experiment, the pHi of non-symbiotic coral cells did not change, though in host cells containing a symbiont cell the pHi recovered to control levels when photsynthesis was not inhibited. This recovery was negated when cells were incubated with DCMU. Our results reveal that photosynthetic activity of the endosymbiont is tightly coupled with the ability of the host cell to recover from cellular acidosis after exposure to high CO2/low pH. © 2014. Published by The Company of Biologists Ltd.

Remodeling of the Host Cell Plasma Membrane by HIV-1 Nef and Vpu: A Strategy to Ensure Viral Fitness and Persistence.

PubMed

Sugden, Scott M; Bego, Mariana G; Pham, Tram N Q; Cohen, Éric A

2016-03-03

The plasma membrane protects the cell from its surroundings and regulates cellular communication, homing, and metabolism. Not surprisingly, the composition of this membrane is highly controlled through the vesicular trafficking of proteins to and from the cell surface. As intracellular pathogens, most viruses exploit the host plasma membrane to promote viral replication while avoiding immune detection. This is particularly true for the enveloped human immunodeficiency virus (HIV), which assembles and obtains its lipid shell directly at the plasma membrane. HIV-1 encodes two proteins, negative factor (Nef) and viral protein U (Vpu), which function primarily by altering the quantity and localization of cell surface molecules to increase virus fitness despite host antiviral immune responses. These proteins are expressed at different stages in the HIV-1 life cycle and employ a variety of mechanisms to target both unique and redundant surface proteins, including the viral receptor CD4, host restriction factors, immunoreceptors, homing molecules, tetraspanins and membrane transporters. In this review, we discuss recent progress in the study of the Nef and Vpu targeting of host membrane proteins with an emphasis on how remodeling of the cell membrane allows HIV-1 to avoid host antiviral immune responses leading to the establishment of systemic and persistent infection.

Translational Control of Viral Gene Expression in Eukaryotes

PubMed Central

Gale, Michael; Tan, Seng-Lai; Katze, Michael G.

2000-01-01

As obligate intracellular parasites, viruses rely exclusively on the translational machinery of the host cell for the synthesis of viral proteins. This relationship has imposed numerous challenges on both the infecting virus and the host cell. Importantly, viruses must compete with the endogenous transcripts of the host cell for the translation of viral mRNA. Eukaryotic viruses have thus evolved diverse mechanisms to ensure translational efficiency of viral mRNA above and beyond that of cellular mRNA. Mechanisms that facilitate the efficient and selective translation of viral mRNA may be inherent in the structure of the viral nucleic acid itself and can involve the recruitment and/or modification of specific host factors. These processes serve to redirect the translation apparatus to favor viral transcripts, and they often come at the expense of the host cell. Accordingly, eukaryotic cells have developed antiviral countermeasures to target the translational machinery and disrupt protein synthesis during the course of virus infection. Not to be outdone, many viruses have answered these countermeasures with their own mechanisms to disrupt cellular antiviral pathways, thereby ensuring the uncompromised translation of virion proteins. Here we review the varied and complex translational programs employed by eukaryotic viruses. We discuss how these translational strategies have been incorporated into the virus life cycle and examine how such programming contributes to the pathogenesis of the host cell. PMID:10839817

Productive Lifecycle of Human Papillomaviruses that Depends Upon Squamous Epithelial Differentiation

PubMed Central

Kajitani, Naoko; Satsuka, Ayano; Kawate, Akifumi; Sakai, Hiroyuki

2012-01-01

Human papillomaviruses (HPVs) target the stratified epidermis, and can causes diseases ranging from benign condylomas to malignant tumors. Infections of HPVs in the genital tract are among the most common sexually transmitted diseases, and a major risk factor for cervical cancer. The virus targets epithelial cells in the basal layer of the epithelium, while progeny virions egress from terminally differentiated cells in the cornified layer, the surface layer of the epithelium. In infected basal cells, the virus maintains its genomic DNA at low-copy numbers, at which the viral productive lifecycle cannot proceed. Progression of the productive lifecycle requires differentiation of the host cell, indicating that there is tight crosstalk between viral replication and host differentiation programs. In this review, we discuss the regulation of the HPV lifecycle controlled by the differentiation program of the host cells. PMID:22536200

Immunoregulation of GVHD by triggering the innate immune system with CpG.

PubMed

Morecki, Shoshana; Slavin, Shimon

2009-08-01

Stimulation of Toll-like receptors by oligodeoxynucleotide sequences containing a CpG motif provides signals capable of triggering the innate and adaptive immune systems, thereby leading either to stimulation or suppression of immunoreactivities. Similar immunoregulatory capabilities are necessary for achieving the fine balance between engraftment and graft-versus-host disease required in the setup of allogeneic cell therapy. Ligation of CpG to its Toll-like receptors can be accomplished by treatment of the host or pretransplant treatment of the donor in vivo. These different strategies are presented in this review, which summarizes the attempts to maximize beneficial alloreactivity against malignant or other undesirable host cells, while controlling graft-versus-host disease.

Cellstat--A continuous culture system of a bacteriophage for the study of the mutation rate and the selection process at the DNA level

NASA Astrophysics Data System (ADS)

Husimi, Yuzuru; Nishigaki, Koichi; Kinoshita, Yasunori; Tanaka, Toyosuke

1982-04-01

A bacteriophage is continuously cultured in the flow of the host bacterial cell under the control of a minicomputer. In the culture, the population of the noninfected cell is kept constant by the endogeneous regulation mechanism, so it is called the ''cellstat'' culture. Due to the high dilution rate of the host cell, the mutant cell cannot be selected in the cellstat. Therefore, the cellstat is suitable for the study of the mutation rate and the selection process of a bacteriophage under well-defined environmental conditions (including physiological condition of the host cell) without being interfered by host-cell mutations. Applications to coliphage fd, a secretion type phage, are shown as a measurement example. A chimera between fd and a plasmid pBR322 is cultured more than 100 h. The process of population changeovers by deletion mutants indicates that the deletion hot spots exist in this cloning vector and that this apparatus can be used also for testing instability of a recombinant DNA.

Proteases and phosphatases during Leishmania-macrophage interaction: paving the road for pathogenesis.

PubMed

Gómez, María Adelaida; Olivier, Martin

2010-01-01

The outcome of Leishmania infection depends both on host and pathogen factors. Macrophages, the specialized host cells for uptake and intracellular development of Leishmania, play a central role in the control of infection. Leishmania has evolved strategies to downregulate host cell functions, largely mediated by the parasite-induced activation of macrophage protein tyrosine phosphatases (PTPs). We have recently identified PTP1B and TCPTP as two additional PTPs engaged upon Leishmania infection and have unraveled an intimate interaction between the Leishmania surface protease GP63 and host PTPs, which mediates a mechanism of cleavage-dependent PTP activation. Here we discuss new perspectives for GP63-mediated parasite virulence and propose putative mechanisms of GP63 internalization into host macrophages and access to intracellular substrates.

Structural basis for Epstein–Barr virus host cell tropism mediated by gp42 and gHgL entry glycoproteins

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sathiyamoorthy, Karthik; Hu, Yao Xiong; Möhl, Britta S.

Herpesvirus entry into host cells is mediated by multiple virally encoded receptor binding and membrane fusion glycoproteins. Despite their importance in host cell tropism and associated disease pathology, the underlying and essential interactions between these viral glycoproteins remain poorly understood. For Epstein–Barr virus (EBV), gHgL/gp42 complexes bind HLA class II to activate membrane fusion with B cells, but gp42 inhibits fusion and entry into epithelial cells. To clarify the mechanism by which gp42 controls the cell specificity of EBV infection, in this paper we determined the structure of gHgL/gp42 complex bound to an anti-gHgL antibody (E1D1). The critical regulator ofmore » EBV tropism is the gp42 N-terminal domain, which tethers the HLA-binding domain to gHgL by wrapping around the exterior of three gH domains. Both the gp42 N-terminal domain and E1D1 selectively inhibit epithelial-cell fusion; however, they engage distinct surfaces of gHgL. Finally, these observations clarify key determinants of EBV host cell tropism.« less

Structural basis for Epstein–Barr virus host cell tropism mediated by gp42 and gHgL entry glycoproteins

DOE PAGES

Sathiyamoorthy, Karthik; Hu, Yao Xiong; Möhl, Britta S.; ...

2016-12-08

Herpesvirus entry into host cells is mediated by multiple virally encoded receptor binding and membrane fusion glycoproteins. Despite their importance in host cell tropism and associated disease pathology, the underlying and essential interactions between these viral glycoproteins remain poorly understood. For Epstein–Barr virus (EBV), gHgL/gp42 complexes bind HLA class II to activate membrane fusion with B cells, but gp42 inhibits fusion and entry into epithelial cells. To clarify the mechanism by which gp42 controls the cell specificity of EBV infection, in this paper we determined the structure of gHgL/gp42 complex bound to an anti-gHgL antibody (E1D1). The critical regulator ofmore » EBV tropism is the gp42 N-terminal domain, which tethers the HLA-binding domain to gHgL by wrapping around the exterior of three gH domains. Both the gp42 N-terminal domain and E1D1 selectively inhibit epithelial-cell fusion; however, they engage distinct surfaces of gHgL. Finally, these observations clarify key determinants of EBV host cell tropism.« less

Engineering host-derived resistance against plant parasites through RNA interference: challenges and opportunities.

PubMed

Runo, Steven

2011-01-01

RNA interference (RNAi) has rapidly advanced to become a powerful genetic tool and holds promise to revolutionizing agriculture by providing a strategy for controlling a wide array of crop pests. Numerous studies document RNAi efficacy in achieving silencing in viruses, insects, nematodes and weeds parasitizing crops. In general, host derived pest resistance through RNAi is achieved by genetically transforming host plants with double stranded RNA constructs targeted at essential parasite genes leading to generation of small interfering RNAs (siRNAs). Small interfering RNAs formed in the host are then delivered to the parasite and transported to target cells. Delivery can be oral - worms and insects, viral infections, viruses - or through a vascular connections - parasitic plants, while delivery to target cells is by cell to cell systemic movement of the silencing signal. Despite the overall optimism in generating pest resistant crops through RNAi-mediated silencing, some hurdles have recently begun to emerge. Presently, the main challenge is delivery of sufficient siRNAs, in the right cells, and at the right time to mount; a strong, durable, and broad-spectrum posttranscriptional gene silencing (PTGS) signal. This review highlights the novel strategies available for improving host derived RNAi resistance in downstream applied agriculture.

Pickle Flavors Relish in Drosophila Immunity.

PubMed

Salminen, Tiina Susanna; Rämet, Mika

2016-09-14

Immune responses must be tightly controlled to avoid host damage. In Drosophila, two NF-κB signaling pathways, Toll and Imd, mediate host immune responses. In this issue of Cell Host & Microbe, Morris et al. (2016) introduce Pickle, a nuclear IκB that inhibits Drosophila immune signaling by modulating the NF-κB Relish. Copyright © 2016 Elsevier Inc. All rights reserved.

Quality status display for a vibration welding process

DOEpatents

Spicer, John Patrick; Abell, Jeffrey A.; Wincek, Michael Anthony; Chakraborty, Debejyo; Bracey, Jennifer; Wang, Hui; Tavora, Peter W.; Davis, Jeffrey S.; Hutchinson, Daniel C.; Reardon, Ronald L.; Utz, Shawn

2017-03-28

A system includes a host machine and a status projector. The host machine is in electrical communication with a collection of sensors and with a welding controller that generates control signals for controlling the welding horn. The host machine is configured to execute a method to thereby process the sensory and control signals, as well as predict a quality status of a weld that is formed using the welding horn, including identifying any suspect welds. The host machine then activates the status projector to illuminate the suspect welds. This may occur directly on the welds using a laser projector, or on a surface of the work piece in proximity to the welds. The system and method may be used in the ultrasonic welding of battery tabs of a multi-cell battery pack in a particular embodiment. The welding horn and welding controller may also be part of the system.

Interferon signaling in Peromyscus leucopus confers a potent and specific restriction to vector-borne flaviviruses.

PubMed

Izuogu, Adaeze O; McNally, Kristin L; Harris, Stephen E; Youseff, Brian H; Presloid, John B; Burlak, Christopher; Munshi-South, Jason; Best, Sonja M; Taylor, R Travis

2017-01-01

Tick-borne flaviviruses (TBFVs), including Powassan virus and tick-borne encephalitis virus cause encephalitis or hemorrhagic fevers in humans with case-fatality rates ranging from 1-30%. Despite severe disease in humans, TBFV infection of natural rodent hosts has little noticeable effect. Currently, the basis for resistance to disease is not known. We hypothesize that the coevolution of flaviviruses with their respective hosts has shaped the evolution of potent antiviral factors that suppress virus replication and protect the host from lethal infection. In the current study, we compared virus infection between reservoir host cells and related susceptible species. Infection of primary fibroblasts from the white-footed mouse (Peromyscus leucopus, a representative host) with a panel of vector-borne flaviviruses showed up to a 10,000-fold reduction in virus titer compared to control Mus musculus cells. Replication of vesicular stomatitis virus was equivalent in P. leucopus and M. musculus cells suggesting that restriction was flavivirus-specific. Step-wise comparison of the virus infection cycle revealed a significant block to viral RNA replication, but not virus entry, in P. leucopus cells. To understand the role of the type I interferon (IFN) response in virus restriction, we knocked down signal transducer and activator of transcription 1 (STAT1) or the type I IFN receptor (IFNAR1) by RNA interference. Loss of IFNAR1 or STAT1 significantly relieved the block in virus replication in P. leucopus cells. The major IFN antagonist encoded by TBFV, nonstructural protein 5, was functional in P. leucopus cells, thus ruling out ineffective viral antagonism of the host IFN response. Collectively, this work demonstrates that the IFN response of P. leucopus imparts a strong and virus-specific barrier to flavivirus replication. Future identification of the IFN-stimulated genes responsible for virus restriction specifically in P. leucopus will yield mechanistic insight into efficient control of virus replication and may inform the development of antiviral therapeutics.

Recombinant hosts suitable for simultaneous saccharification and fermentation

DOEpatents

Ingram, Lonnie O'Neal; Zhou, Shengde

2007-06-05

The invention provides recombinant host cells containing at least one heterologous polynucleotide encoding a polysaccharase under the transcriptional control of a surrogate promoter capable of increasing the expression of the polysaccharase. In addition, the invention further provides such hosts with genes encoding secretory protein/s to facilitate the secretion of the expressed polysaccharase. Preferred hosts of the invention are ethanologenic and capable of carrying out simultaneous saccharification fermentation resulting in the production of ethanol from complex cellulose substrates.

Intranasal administration of Lactobacillus rhamnosus GG protects mice from H1N1 influenza virus infection by regulating respiratory immune responses.

PubMed

Harata, G; He, F; Hiruta, N; Kawase, M; Kubota, A; Hiramatsu, M; Yausi, H

2010-06-01

To investigate whether intranasal Lactobacillus administration protects host animals from influenza virus (IFV) infection by enhancing respiratory immune responses in a mouse model. After 3 days of intranasal exposure to Lactobacillus rhamnosus GG (LGG), BALB/c mice were infected with IFV A/PR/8/34 (H1N1). Mice treated with LGG showed a lower frequency of accumulated symptoms and a higher survival rate than control mice (P < 0.05). The YAC-1 cell-killing activity of lung cells isolated from mice treated with LGG was significantly greater than those isolated from control mice (P < 0.01). Intranasal administration of LGG significantly increased mRNA expression of interleukin (IL)-1 beta, tumour necrosis factor (TNF) and monocyte chemotactic protein (MCP)-1 (P < 0.01). These results suggest that intranasal administration of LGG protects the host animal from IFV infection by enhancing respiratory cell-mediated immune responses following up-regulation of lung natural killer (NK) cell activation. We have demonstrated that probiotics might protect host animals from viral infection by stimulating immune responses in the respiratory tract.

MYR1-Dependent Effectors Are the Major Drivers of a Host Cell's Early Response to Toxoplasma, Including Counteracting MYR1-Independent Effects.

PubMed

Naor, Adit; Panas, Michael W; Marino, Nicole; Coffey, Michael J; Tonkin, Christopher J; Boothroyd, John C

2018-04-03

The obligate intracellular parasite Toxoplasma gondii controls its host cell from within the parasitophorous vacuole (PV) by using a number of diverse effector proteins, a subset of which require the aspartyl protease 5 enzyme (ASP5) and/or the recently discovered MYR1 protein to cross the PV membrane. To examine the impact these effectors have in the context of the entirety of the host response to Toxoplasma , we used RNA-Seq to analyze the transcriptome expression profiles of human foreskin fibroblasts infected with wild-type RH (RH-WT), RHΔ myr1 , and RHΔ asp5 tachyzoites. Interestingly, the majority of the differentially regulated genes responding to Toxoplasma infection are MYR1 dependent. A subset of MYR1 responses were ASP5 independent, and MYR1 function did not require ASP5 cleavage, suggesting the export of some effectors requires only MYR1. Gene set enrichment analysis of MYR1-dependent host responses suggests an upregulation of E2F transcription factors and the cell cycle and a downregulation related to interferon signaling, among numerous others. Most surprisingly, "hidden" responses arising in RHΔ myr1 - but not RH-WT-infected host cells indicate counterbalancing actions of MYR1-dependent and -independent activities. The host genes and gene sets revealed here to be MYR1 dependent provide new insight into the parasite's ability to co-opt host cell functions. IMPORTANCE Toxoplasma gondii is unique in its ability to successfully invade and replicate in a broad range of host species and cells within those hosts. The complex interplay of effector proteins exported by Toxoplasma is key to its success in co-opting the host cell to create a favorable replicative niche. Here we show that a majority of the transcriptomic effects in tachyzoite-infected cells depend on the activity of a novel translocation system involving MYR1 and that the effectors delivered by this system are part of an intricate interplay of activators and suppressors. Removal of all MYR1-dependent effectors reveals previously unknown activities that are masked or hidden by the action of these proteins. Copyright © 2018 Naor et al.

Infection dynamics of Nosema ceranae in honey bee midgut and host cell apoptosis.

PubMed

Kurze, Christoph; Le Conte, Yves; Kryger, Per; Lewkowski, Oleg; Müller, Thomas; Moritz, Robin F A

2018-05-01

Nosema ceranae is an intracellular microsporidian parasite that infects epithelial cells of the honey bee (Apis mellifera) midgut. Previous studies have shown that Nosema may alter cell renewal and apoptosis in honey bees. We found that the amount of apoptotic cells progressively declines from the anterior towards posterior regions of the midgut in Nosema-infected sensitive bees. There was no such pattern in the infected Nosema tolerant honey bees and controls. These data provide additional evidence that N. ceranae appears to alter apoptosis in its host cells for its own advantage. Copyright © 2018 Elsevier Inc. All rights reserved.

Novel Approaches for Graft-versus-Host Disease Prevention Compared to Contemporary Controls (BMT CTN 1203)

ClinicalTrials.gov

2018-04-05

Acute Leukemia; Chronic Myelogenous Leukemia; Myelodysplasia; Chronic Lymphocytic Leukemia; Small Lymphocytic Lymphoma; Lymphoma, B-Cell; Lymphoma, Follicular; Lymphoma, Large B-Cell, Diffuse; Hodgkin's Lymphoma

Role of host protein Ebp1 in influenza virus growth: intracellular localization of Ebp1 in virus-infected and uninfected cells.

PubMed

Honda, Ayae

2008-01-20

The cellular protein Ebp1 was identified to interact with PB1 protein of influenza virus RNA polymerase, and inhibit both RNA synthesis in vitro and influenza virus replication in vivo [Honda, A., Okamoto, T., Ishihama, A., 2007. Host factor Ebp1: selective inhibitor of influenza virus transcriptase. Genes Cells 12, 133-142]. The intracellular localization of Ebp1 that is involved in cell proliferation control was analyzed by direct immunostaining of cells before and after influenza virus infection. Ebp1 was found to localize in the nuclear membrane of uninfected cells, and to form nuclear aggregates with viral P proteins in virus-infected cells.

Unique Infectious Strategy of H5N1 Avian Influenza Virus Is Governed by the Acid-Destabilized Property of Hemagglutinin.

PubMed

Daidoji, Tomo; Watanabe, Yohei; Arai, Yasuha; Kajikawa, Junichi; Hirose, Ryohei; Nakaya, Takaaki

Highly pathogenic avian influenza (HPAI) H5N1 virus emerged in 1997 as a zoonotic disease in Hong Kong. It has since spread to Asia and Europe and is a serious threat to both the poultry industry and human health. For effective surveillance and possible prevention/control of HPAI H5N1 viruses, it is necessary to understand the molecular mechanism underlying HPAI H5N1 pathogenesis. The hemagglutinin (HA) protein of influenza A viruses (IAVs) is one of the major determinants of host adaptation, transmissibility, and viral virulence. The main function of the HA protein is to facilitate viral entry and viral genome release within host cells before infection. To achieve viral infection, IAVs belonging to different subtypes or strains induce viral-cell membrane fusion at different endosomal pH levels after internalization through endocytosis. However, host-specific endosomal pH also affects induction of membrane fusion followed by infection. The HA protein of HPAI H5N1 has a higher pH threshold for membrane fusion than the HA protein of classical avian influenza viruses. Although this particular property of HA (which governs viral infection) is prone to deactivation in the avian intestine or in an ambient environment, it facilitates efficient infection of host cells, resulting in a broad host tropism, regardless of the pH in the host endosome. Accumulated knowledge, together with further research, about the HA-governed mechanism underlying HPAI H5N1 virulence (i.e., receptor tropism and pH-dependent viral-cell membrane fusion) will be helpful for developing effective surveillance strategies and for prevention/control of HPAI H5N1 infection.

Relative Contributions of Various Cellular Mechanisms to Loss of Algae during Cnidarian Bleaching.

PubMed

Bieri, Tamaki; Onishi, Masayuki; Xiang, Tingting; Grossman, Arthur R; Pringle, John R

2016-01-01

When exposed to stress such as high seawater temperature, corals and other cnidarians can bleach due to loss of symbiotic algae from the host tissue and/or loss of pigments from the algae. Although the environmental conditions that trigger bleaching are reasonably well known, its cellular and molecular mechanisms are not well understood. Previous studies have reported the occurrence of at least four different cellular mechanisms for the loss of symbiotic algae from the host tissue: in situ degradation of algae, exocytic release of algae from the host, detachment of host cells containing algae, and death of host cells containing algae. The relative contributions of these several mechanisms to bleaching remain unclear, and it is also not known whether these relative contributions change in animals subjected to different types and/or durations of stresses. In this study, we used a clonal population of the small sea anemone Aiptasia, exposed individuals to various precisely controlled stress conditions, and quantitatively assessed the several possible bleaching mechanisms in parallel. Under all stress conditions tested, except for acute cold shock at 4°C, expulsion of intact algae from the host cells appeared to be by far the predominant mechanism of bleaching. During acute cold shock, in situ degradation of algae and host-cell detachment also became quantitatively significant, and the algae released under these conditions appeared to be severely damaged.

Relative Contributions of Various Cellular Mechanisms to Loss of Algae during Cnidarian Bleaching

PubMed Central

Bieri, Tamaki; Onishi, Masayuki; Xiang, Tingting; Grossman, Arthur R.; Pringle, John R

2016-01-01

When exposed to stress such as high seawater temperature, corals and other cnidarians can bleach due to loss of symbiotic algae from the host tissue and/or loss of pigments from the algae. Although the environmental conditions that trigger bleaching are reasonably well known, its cellular and molecular mechanisms are not well understood. Previous studies have reported the occurrence of at least four different cellular mechanisms for the loss of symbiotic algae from the host tissue: in situ degradation of algae, exocytic release of algae from the host, detachment of host cells containing algae, and death of host cells containing algae. The relative contributions of these several mechanisms to bleaching remain unclear, and it is also not known whether these relative contributions change in animals subjected to different types and/or durations of stresses. In this study, we used a clonal population of the small sea anemone Aiptasia, exposed individuals to various precisely controlled stress conditions, and quantitatively assessed the several possible bleaching mechanisms in parallel. Under all stress conditions tested, except for acute cold shock at 4°C, expulsion of intact algae from the host cells appeared to be by far the predominant mechanism of bleaching. During acute cold shock, in situ degradation of algae and host-cell detachment also became quantitatively significant, and the algae released under these conditions appeared to be severely damaged. PMID:27119147

Functional Stem Cell Integration into Neural Networks Assessed by Organotypic Slice Cultures.

PubMed

Forsberg, David; Thonabulsombat, Charoensri; Jäderstad, Johan; Jäderstad, Linda Maria; Olivius, Petri; Herlenius, Eric

2017-08-14

Re-formation or preservation of functional, electrically active neural networks has been proffered as one of the goals of stem cell-mediated neural therapeutics. A primary issue for a cell therapy approach is the formation of functional contacts between the implanted cells and the host tissue. Therefore, it is of fundamental interest to establish protocols that allow us to delineate a detailed time course of grafted stem cell survival, migration, differentiation, integration, and functional interaction with the host. One option for in vitro studies is to examine the integration of exogenous stem cells into an existing active neural network in ex vivo organotypic cultures. Organotypic cultures leave the structural integrity essentially intact while still allowing the microenvironment to be carefully controlled. This allows detailed studies over time of cellular responses and cell-cell interactions, which are not readily performed in vivo. This unit describes procedures for using organotypic slice cultures as ex vivo model systems for studying neural stem cell and embryonic stem cell engraftment and communication with CNS host tissue. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Dectin-1 plays an important role in host defense against systemic Candida glabrata infection.

PubMed

Chen, Si Min; Shen, Hui; Zhang, Teng; Huang, Xin; Liu, Xiao Qi; Guo, Shi Yu; Zhao, Jing Jun; Wang, Chun Fang; Yan, Lan; Xu, Guo Tong; Jiang, Yuan Ying; An, Mao Mao

2017-11-17

Candida glabrata is the second most common pathogen of severe candidiasis in immunocompromised hosts, following C. albicans. Although C. glabrata and C. albicans belong to the same genus, they are phylogenetically distinct. C-type lectin receptors (CLRs), acting as pattern-recognition receptors (PRRs), play critical roles in host defense against C. albicans infections. However, our understanding of the specific roles of CLRs in host defense against C. glabrata is limited. Here, we explored the potential roles of the C-type lectins Dectin-1 and Dectin-2 in host defense against C. glabrata. We found that both Dectin-1-deficient mice (Dectin-1 -/- ) and Dectin-2-deficient mice (Dectin-2 -/- ) are more susceptible to C. glabrata infection. Dectin-1confers host higher sensitivity for sensing C. glabrata infections, while the effect of Dectin-2 in the host defense against C. glabrata is infection dose dependent. Dectin-1 is required for host myeloid cells recognition, killing of C. glabrata, and development of subsequent Th1 and Th17 cell-mediated adaptive immune response. Significantly impaired inflammatory responses such as inflammatory cells recruitment and cytokines release that were induced by C. glabrata were manifested in Dectin-1-deficient mice. Together, our study demonstrates that Dectin-1 plays an important role in host defense against systemic Candida glabrata infections, indicating a previous unknown control mechanism for this particular type of infection in host. Our study, therefore, provides new insights into the host defense against C. glabrata.

Ikaros-Notch axis in host hematopoietic cells regulates experimental graft-versus-host disease

PubMed Central

Toubai, Tomomi; Sun, Yaping; Tawara, Isao; Friedman, Ann; Liu, Chen; Evers, Rebecca; Nieves, Evelyn; Malter, Chelsea; Chockley, Peter; Maillard, Ivan; Winandy, Susan

2011-01-01

Host hematopoietically derived APCs play a vital role in the initiation of GVH responses. However, the APC autonomous molecular mechanisms that are critical for the induction of GVHD are not known. We report here that the Ikaros-Notch axis in host hematopoietically derived APCs regulates the severity of acute GVHD across multiple clinically relevant murine models of experimental bone marrow transplantation. In the present study, Ikaros deficiency (Ik−/−) limited to host hematopoietically derived APCs enhanced donor T-cell expansion and intensified acute GVHD, as determined by survival and other GVHD-specific parameters. The Ik−/− conventional CD8+ and CD8−CD11c+ dendritic cells (DCs), the most potent APCs, showed no increase in the expression of activation markers or in response to TLR stimulation compared with wild-type controls. However, Ik−/− DCs demonstrated an enhanced stimulation of allogeneic T cells. Deficiency of Ikaros in the conventional CD8+ and CD8−CD11c+ DCs was associated with an increase in Notch signaling, the blockade of which mitigated the enhanced in vitro and in vivo allostimulatory capacity. Therefore, the Ikaros-Notch axis is a novel pathway that modulates DC biology in general, and targeting this pathway in host hematopoietically derived APCs may reduce GVHD. PMID:21471527

Cell division and density of symbiotic Chlorella variabilis of the ciliate Paramecium bursaria is controlled by the host's nutritional conditions during early infection process.

PubMed

Kodama, Yuuki; Fujishima, Masahiro

2012-10-01

The association of ciliate Paramecium bursaria with symbiotic Chlorella sp. is a mutualistic symbiosis. However, both the alga-free paramecia and symbiotic algae can still grow independently and can be reinfected experimentally by mixing them. Effects of the host's nutritional conditions against the symbiotic algal cell division and density were examined during early reinfection. Transmission electron microscopy revealed that algal cell division starts 24 h after mixing with alga-free P. bursaria, and that the algal mother cell wall is discarded from the perialgal vacuole membrane, which encloses symbiotic alga. Labelling of the mother cell wall with Calcofluor White Stain, a cell-wall-specific fluorochrome, was used to show whether alga had divided or not. Pulse labelling of alga-free P. bursaria cells with Calcofluor White Stain-stained algae with or without food bacteria for P. bursaria revealed that the fluorescence of Calcofluor White Stain in P. bursaria with bacteria disappeared within 3 days after mixing, significantly faster than without bacteria. Similar results were obtained both under constant light and dark conditions. This report is the first describing that the cell division and density of symbiotic algae of P. bursaria are controlled by the host's nutritional conditions during early infection. © 2012 Society for Applied Microbiology and Blackwell Publishing Ltd.

miRNA engineering of CHO cells facilitates production of difficult-to-express proteins and increases success in cell line development.

PubMed

Fischer, Simon; Marquart, Kim F; Pieper, Lisa A; Fieder, Juergen; Gamer, Martin; Gorr, Ingo; Schulz, Patrick; Bradl, Harald

2017-07-01

In recent years, coherent with growing biologics portfolios also the number of complex and thus difficult-to-express (DTE) therapeutic proteins has increased considerably. DTE proteins challenge bioprocess development and can include various therapeutic protein formats such as monoclonal antibodies (mAbs), multi-specific affinity scaffolds (e.g., bispecific antibodies), cytokines, or fusion proteins. Hence, the availability of robust and versatile Chinese hamster ovary (CHO) host cell factories is fundamental for high-yielding bioprocesses. MicroRNAs (miRNAs) have emerged as potent cell engineering tools to improve process performance of CHO manufacturing cell lines. However, there has not been any report demonstrating the impact of beneficial miRNAs on industrial cell line development (CLD) yet. To address this question, we established novel CHO host cells constitutively expressing a pro-productive miRNA: miR-557. Novel host cells were tested in two independent CLD campaigns using two different mAb candidates including a normal as well as a DTE antibody. Presence of miR-557 significantly enhanced each process step during CLD in a product independent manner. Stable expression of miR-557 increased the probability to identify high-producing cell clones. Furthermore, production cell lines derived from miR-557 expressing host cells exhibited significantly increased final product yields in fed-batch cultivation processes without compromising product quality. Strikingly, cells co-expressing miR-557 and a DTE antibody achieved a twofold increase in product titer compared to clones co-expressing a negative control miRNA. Thus, host cell engineering using miRNAs represents a promising tool to overcome limitations in industrial CLD especially with regard to DTE proteins. Biotechnol. Bioeng. 2017;114: 1495-1510. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Comparative phosphoproteomics reveals components of host cell invasion and post-transcriptional regulation during Francisella infection

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nakayasu, Ernesto S.; Tempel, Rebecca; Cambronne, Xiaolu A.

2013-09-22

Francisella tularensis is a facultative intracellular bacterium that causes the deadly disease tularemia. Most evidence suggests that Francisella is not well recognized by the innate immune system that normally leads to cytokine expression and cell death. In previous work, we identified new bacterial factors that were hyper-cytotoxic to macrophages. Four of the identified hyper-cytotoxic strains (lpcC, manB, manC and kdtA) had an impaired lipopolysaccharide (LPS) synthesis and produced an exposed lipid A lacking the O-antigen. These mutants were not only hyper-cytotoxic but also were phagocytosed at much higher rates compared to the wild type parent strain. To elucidate the cellularmore » signaling underlying this enhanced phagocytosis and cell death, we performed a large-scale comparative phosphoproteomic analysis of cells infected with wild-type and delta-lpcC F. novicida. Our data suggest that not only actin but also intermediate filaments and microtubules are important for F. novicida entry into the host cells. In addition, we observed differential phosphorylation of tristetraprolin (TTP), a key component of the mRNA-degrading machinery that controls the expression of a variety of genes including many cytokines. Infection with the delta-lpcC mutant induced the hyper-phosphorylation and inhibition of TTP, leading to the production of cytokines such as IL-1beta and TNF-alpha which may kill the host cells by triggering apoptosis. Together, our data provide new insights for Francisella invasion and a post-transcriptional mechanism that prevents the expression of host immune response factors that controls infection by this pathogen.« less

Near-infrared remotely triggered drug-release strategies for cancer treatment

NASA Astrophysics Data System (ADS)

Goodman, Amanda M.; Neumann, Oara; Nørregaard, Kamilla; Henderson, Luke; Choi, Mi-Ran; Clare, Susan E.; Halas, Naomi J.

2017-11-01

Remotely controlled, localized drug delivery is highly desirable for potentially minimizing the systemic toxicity induced by the administration of typically hydrophobic chemotherapy drugs by conventional means. Nanoparticle-based drug delivery systems provide a highly promising approach for localized drug delivery, and are an emerging field of interest in cancer treatment. Here, we demonstrate near-IR light-triggered release of two drug molecules from both DNA-based and protein-based hosts that have been conjugated to near-infrared-absorbing Au nanoshells (SiO2 core, Au shell), each forming a light-responsive drug delivery complex. We show that, depending upon the drug molecule, the type of host molecule, and the laser illumination method (continuous wave or pulsed laser), in vitro light-triggered release can be achieved with both types of nanoparticle-based complexes. Two breast cancer drugs, docetaxel and HER2-targeted lapatinib, were delivered to MDA-MB-231 and SKBR3 (overexpressing HER2) breast cancer cells and compared with release in noncancerous RAW 264.7 macrophage cells. Continuous wave laser-induced release of docetaxel from a nanoshell-based DNA host complex showed increased cell death, which also coincided with nonspecific cell death from photothermal heating. Using a femtosecond pulsed laser, lapatinib release from a nanoshell-based human serum albumin protein host complex resulted in increased cancerous cell death while noncancerous control cells were unaffected. Both methods provide spatially and temporally localized drug-release strategies that can facilitate high local concentrations of chemotherapy drugs deliverable at a specific treatment site over a specific time window, with the potential for greatly minimized side effects.

Host-mediated impairment of parasite maturation during blood-stage Plasmodium infection

PubMed Central

Khoury, David S.; Cromer, Deborah; Akter, Jasmin; Sebina, Ismail; Elliott, Trish; Thomas, Bryce S.; Soon, Megan S. F.; James, Kylie R.; Best, Shannon E.; Haque, Ashraful; Davenport, Miles P.

2017-01-01

Severe malaria and associated high parasite burdens occur more frequently in humans lacking robust adaptive immunity to Plasmodium falciparum. Nevertheless, the host may partly control blood-stage parasite numbers while adaptive immunity is gradually established. Parasite control has typically been attributed to enhanced removal of parasites by the host, although in vivo quantification of this phenomenon remains challenging. We used a unique in vivo approach to determine the fate of a single cohort of semisynchronous, Plasmodium berghei ANKA- or Plasmodium yoelii 17XNL-parasitized red blood cells (pRBCs) after transfusion into naive or acutely infected mice. As previously shown, acutely infected mice, with ongoing splenic and systemic inflammatory responses, controlled parasite population growth more effectively than naive controls. Surprisingly, however, this was not associated with accelerated removal of pRBCs from circulation. Instead, transfused pRBCs remained in circulation longer in acutely infected mice. Flow cytometric assessment and mathematical modeling of intraerythrocytic parasite development revealed an unexpected and substantial slowing of parasite maturation in acutely infected mice, extending the life cycle from 24 h to 40 h. Importantly, impaired parasite maturation was the major contributor to control of parasite growth in acutely infected mice. Moreover, by performing the same experiments in rag1−/− mice, which lack T and B cells and mount weak inflammatory responses, we revealed that impaired parasite maturation is largely dependent upon the host response to infection. Thus, impairment of parasite maturation represents a host-mediated, immune system-dependent mechanism for limiting parasite population growth during the early stages of an acute blood-stage Plasmodium infection. PMID:28673996

Aberrant epithelial differentiation by cigarette smoke dysregulates respiratory host defence.

PubMed

Amatngalim, Gimano D; Schrumpf, Jasmijn A; Dishchekenian, Fernanda; Mertens, Tinne C J; Ninaber, Dennis K; van der Linden, Abraham C; Pilette, Charles; Taube, Christian; Hiemstra, Pieter S; van der Does, Anne M

2018-04-01

It is currently unknown how cigarette smoke-induced airway remodelling affects highly expressed respiratory epithelial defence proteins and thereby mucosal host defence.Localisation of a selected set of highly expressed respiratory epithelial host defence proteins was assessed in well-differentiated primary bronchial epithelial cell (PBEC) cultures. Next, PBEC were cultured at the air-liquid interface, and during differentiation for 2-3 weeks exposed daily to whole cigarette smoke. Gene expression, protein levels and epithelial cell markers were subsequently assessed. In addition, functional activities and persistence of the cigarette smoke-induced effects upon cessation were determined.Expression of the polymeric immunoglobulin receptor, secretory leukocyte protease inhibitor and long and short PLUNC (palate, lung and nasal epithelium clone protein) was restricted to luminal cells and exposure of differentiating PBECs to cigarette smoke resulted in a selective reduction of the expression of these luminal cell-restricted respiratory host defence proteins compared to controls. This reduced expression was a consequence of cigarette smoke-impaired end-stage differentiation of epithelial cells, and accompanied by a significant decreased transepithelial transport of IgA and bacterial killing.These findings shed new light on the importance of airway epithelial cell differentiation in respiratory host defence and could provide an additional explanation for the increased susceptibility of smokers and patients with chronic obstructive pulmonary disease to respiratory infections. Copyright ©ERS 2018.

Selfish restriction modification genes: resistance of a resident R/M plasmid to displacement by an incompatible plasmid mediated by host killing.

PubMed

Naito, Y; Naito, T; Kobayashi, I

1998-01-01

Previous work from this laboratory demonstrated that plasmids carrying a type II restriction-modification gene complex are not easily lost from their bacterial host because plasmid-free segregant cells are killed through chromosome cleavage. Here, we have followed the course of events that takes place when an Escherichia coli rec BC sbcA strain carrying a plasmid coding for the PaeR7I restriction-modification (R/M) gene complex is transformed by a plasmid with an identical origin of replication. The number of transformants that appeared was far fewer than with the restriction-minus (r-) control. Most of the transformants were very small. After prolonged incubation, the number and the size of the colonies increased, but this increase never attained the level of the r- control. Most of the transformed colonies retained the drug-resistance of the resident, r+ m+ plasmid. These results indicate that post-segregational host killing occurs when a plasmid bearing an R/M gene complex is displaced by an incompatible plasmid. Such cell killing eliminates the competitor plasmid along with the host and, thus, would allow persistence of the R/M plasmid in the neighboring, clonal host cells in nature. This phenomenon is reminiscent of mammalian apoptosis and other forms of altruistic cell death strategy against infection. This type of resistance to displacement was also studied in a wild type Escherichia coli strain that was normal for homologous recombination (rec+). A number of differences between the recBC sbcA strain and the rec+ strain were observed and these will be discussed.

DOT1L inhibition attenuates graft-versus-host disease by allogeneic T cells in adoptive immunotherapy models.

PubMed

Kagoya, Yuki; Nakatsugawa, Munehide; Saso, Kayoko; Guo, Tingxi; Anczurowski, Mark; Wang, Chung-Hsi; Butler, Marcus O; Arrowsmith, Cheryl H; Hirano, Naoto

2018-05-15

Adoptive T-cell therapy is a promising therapeutic approach for cancer patients. The use of allogeneic T-cell grafts will improve its applicability and versatility provided that inherent allogeneic responses are controlled. T-cell activation is finely regulated by multiple signaling molecules that are transcriptionally controlled by epigenetic mechanisms. Here we report that inhibiting DOT1L, a histone H3-lysine 79 methyltransferase, alleviates allogeneic T-cell responses. DOT1L inhibition reduces miR-181a expression, which in turn increases the ERK phosphatase DUSP6 expression and selectively ameliorates low-avidity T-cell responses through globally suppressing T-cell activation-induced gene expression alterations. The inhibition of DOT1L or DUSP6 overexpression in T cells attenuates the development of graft-versus-host disease, while retaining potent antitumor activity in xenogeneic and allogeneic adoptive immunotherapy models. These results suggest that DOT1L inhibition may enable the safe and effective use of allogeneic antitumor T cells by suppressing unwanted immunological reactions in adoptive immunotherapy.

Know your neighbor: Microbiota and host epithelial cells interact locally to control intestinal function and physiology.

PubMed

Sommer, Felix; Bäckhed, Fredrik

2016-05-01

Interactions between the host and its associated microbiota differ spatially and the local cross talk determines organ function and physiology. Animals and their organs are not uniform but contain several functional and cellular compartments and gradients. In the intestinal tract, different parts of the gut carry out different functions, tissue structure varies accordingly, epithelial cells are differentially distributed and gradients exist for several physicochemical parameters such as nutrients, pH, or oxygen. Consequently, the microbiota composition also differs along the length of the gut, but also between lumen and mucosa of the same intestinal segment, and even along the crypt-villus axis in the epithelium. Thus, host-microbiota interactions are highly site-specific and the local cross talk determines intestinal function and physiology. Here we review recent advances in our understanding of site-specific host-microbiota interactions and discuss their functional relevance for host physiology. © 2016 WILEY Periodicals, Inc.

The cGAS-STING Defense Pathway and Its Counteraction by Viruses.

PubMed

Ma, Zhe; Damania, Blossom

2016-02-10

Upon virus infection, host cells mount a concerted innate immune response involving type I interferon and pro-inflammatory cytokines to enable elimination of the pathogen. Recently, cGAS and STING have been identified as intracellular sensors that activate the interferon pathway in response to virus infection and thus mediate host defense against a range of DNA and RNA viruses. Here we review how viruses are sensed by the cGAS-STING signaling pathway as well as how viruses modulate this pathway. Mechanisms utilized by viral proteins to inhibit cGAS and/or STING are also discussed. On the flip side, host cells have also evolved strategies to thwart viral immune escape. The balance between host immune control and viral immune evasion is pivotal to viral pathogenesis, and we discuss this virus-host stand-off in the context of the cGAS-STING innate immune pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

A correlate of HIV-1 control consisting of both innate and adaptive immune parameters best predicts viral load by multivariable analysis in HIV-1 infected viremic controllers and chronically-infected non-controllers.

PubMed

Tomescu, Costin; Liu, Qin; Ross, Brian N; Yin, Xiangfan; Lynn, Kenneth; Mounzer, Karam C; Kostman, Jay R; Montaner, Luis J

2014-01-01

HIV-1 infected viremic controllers maintain durable viral suppression below 2000 copies viral RNA/ml without anti-retroviral therapy (ART), and the immunological factor(s) associated with host control in presence of low but detectable viral replication are of considerable interest. Here, we utilized a multivariable analysis to identify which innate and adaptive immune parameters best correlated with viral control utilizing a cohort of viremic controllers (median 704 viral RNA/ml) and non-controllers (median 21,932 viral RNA/ml) that were matched for similar CD4+ T cell counts in the absence of ART. We observed that HIV-1 Gag-specific CD8+ T cell responses were preferentially targeted over Pol-specific responses in viremic controllers (p = 0.0137), while Pol-specific responses were positively associated with viral load (rho = 0.7753, p = 0.0001, n = 23). Viremic controllers exhibited significantly higher NK and plasmacytoid dendritic cells (pDC) frequency as well as retained expression of the NK CD16 receptor and strong target cell-induced NK cell IFN-gamma production compared to non-controllers (p<0.05). Despite differences in innate and adaptive immune function however, both viremic controllers (p<0.05) and non-controller subjects (p<0.001) exhibited significantly increased CD8+ T cell activation and spontaneous NK cell degranulation compared to uninfected donors. Overall, we identified that a combination of innate (pDC frequency) and adaptive (Pol-specific CD8+ T cell responses) immune parameters best predicted viral load (R2 = 0.5864, p = 0.0021, n = 17) by a multivariable analysis. Together, this data indicates that preferential Gag-specific over Pol-specific CD8+ T cell responses along with a retention of functional innate subsets best predict host control over viral replication in HIV-1 infected viremic controllers compared to chronically-infected non-controllers.

Non-coding RNAs in virology: an RNA genomics approach.

PubMed

Isaac, Christopher; Patel, Trushar R; Zovoilis, Athanasios

2018-04-01

Advances in sequencing technologies and bioinformatic analysis techniques have greatly improved our understanding of various classes of RNAs and their functions. Despite not coding for proteins, non-coding RNAs (ncRNAs) are emerging as essential biomolecules fundamental for cellular functions and cell survival. Interestingly, ncRNAs produced by viruses not only control the expression of viral genes, but also influence host cell regulation and circumvent host innate immune response. Correspondingly, ncRNAs produced by the host genome can play a key role in host-virus interactions. In this article, we will first discuss a number of types of viral and mammalian ncRNAs associated with viral infections. Subsequently, we also describe the new possibilities and opportunities that RNA genomics and next-generation sequencing technologies provide for studying ncRNAs in virology.

Controlling the burn and fueling the fire: defining the role for the alarmin interleukin-33 in alloimmunity.

PubMed

Liu, Quan; Turnquist, Heth R

2016-02-01

The purpose of this review is to provide a general update on recent developments in the immunobiology of IL-33 and IL-33-targeted immune cells. We also discuss emerging concepts regarding the potential role IL-33 appears to play in altering alloimmune responses mediating host-versus-graft and graft-versus-host alloresponses. Stromal cells and leukocytes display regulated expression of IL-33 and may actively or passively secrete this pleotropic cytokine. Type 2 innate lymphoid cells and a large proportion of tissue resident regulatory T cells (Treg) express membrane-bound suppressor of tumorigenicity 2 (ST2), the IL-33 receptor. Although Treg are appreciated suppressors of the inflammatory function of immune cells, both type 2 innate lymphoid cells and tissue resident Treg could play key roles in tissue repair and homeostasis. The functions of IL-33 in transplantation are poorly understood. However, like other disease models, the functions of IL-33 in alloimmunity appear to be quite pleiotropic. IL-33 is associated with immune regulation and graft protection in cardiac transplant settings. Yet, it is highly proinflammatory and stimulates lethal graft-versus-host disease through its capacity to stimulate type 1 immunity. Intensive studies on IL-33/ST2 signaling pathways and ST2 cell populations in solid organ and cell transplantation are warranted. A better understanding of this important pathway will provide promising therapeutic targets controlling pathogenic alloimmune responses, as well as potentially facilitating the function of regulatory and reparative immune cells posttransplantation.

Two pore channels control Ebolavirus host cell entry and are drug targets for disease treatment

PubMed Central

Sakurai, Yasuteru; Kolokoltsov, Andrey A.; Chen, Cheng-Chang; Tidwell, Michael W.; Bauta, William E.; Klugbauer, Norbert; Grimm, Christian; Wahl-Schott, Christian; Biel, Martin; Davey, Robert A.

2015-01-01

Ebolavirus causes sporadic outbreaks of lethal hemorrhagic fever in humans with no currently approved therapy. Cells take up Ebolavirus by macropinocytosis, followed by trafficking through endosomal vesicles. However, few factors controlling endosomal virus movement are known. Here we find that Ebolavirus entry into host cells requires the endosomal calcium channels called two pore channels (TPCs). Disrupting TPC function by gene knockout, small interfering RNAs or small molecule inhibitors halted virus trafficking and prevented infection. Tetrandrine, the most potent small molecule we tested, inhibited infection of human macrophages, the primary target of Ebolavirus in vivo, and also showed therapeutic efficacy in mice. Therefore, TPC proteins play a key role in Ebolavirus infection and may be effective targets for antiviral therapy. PMID:25722412

Communication between filamentous pathogens and plants at the biotrophic interface.

PubMed

Yi, Mihwa; Valent, Barbara

2013-01-01

Fungi and oomycetes that colonize living plant tissue form extensive interfaces with plant cells in which the cytoplasm of the microorganism is closely aligned with the host cytoplasm for an extended distance. In all cases, specialized biotrophic hyphae function to hijack host cellular processes across an interfacial zone consisting of a hyphal plasma membrane, a specialized interfacial matrix, and a plant-derived membrane. The interface is the site of active secretion by both players. This cross talk at the interface determines the winner in adversarial relationships and establishes the partnership in mutualistic relationships. Fungi and oomycetes secrete many specialized effector proteins for controlling the host, and they can stimulate remarkable cellular reorganization even in distant plant cells. Breakthroughs in live-cell imaging of fungal and oomycete encounter sites, including live-cell imaging of pathogens secreting fluorescently labeled effector proteins, have led to recent progress in understanding communication across the interface.

Long-distance endosome trafficking drives fungal effector production during plant infection

PubMed Central

Bielska, Ewa; Higuchi, Yujiro; Schuster, Martin; Steinberg, Natascha; Kilaru, Sreedhar; Talbot, Nicholas J.; Steinberg, Gero

2014-01-01

To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppress plant immunity and facilitate fungal infection. Most fungal pathogens infect plants using very long strand-like cells, called hyphae, that secrete effectors from their tips into host tissue. How fungi undergo long-distance cell signalling to regulate effector production during infection is not known. Here we show that long-distance retrograde motility of early endosomes (EEs) is necessary to trigger transcription of effector-encoding genes during plant infection by the pathogenic fungus Ustilago maydis. We demonstrate that motor-dependent retrograde EE motility is necessary for regulation of effector production and secretion during host cell invasion. We further show that retrograde signalling involves the mitogen-activated kinase Crk1 that travels on EEs and participates in control of effector production. Fungal pathogens therefore undergo long-range signalling to orchestrate host invasion. PMID:25283249

Long-distance endosome trafficking drives fungal effector production during plant infection.

PubMed

Bielska, Ewa; Higuchi, Yujiro; Schuster, Martin; Steinberg, Natascha; Kilaru, Sreedhar; Talbot, Nicholas J; Steinberg, Gero

2014-10-06

To cause plant disease, pathogenic fungi can secrete effector proteins into plant cells to suppress plant immunity and facilitate fungal infection. Most fungal pathogens infect plants using very long strand-like cells, called hyphae, that secrete effectors from their tips into host tissue. How fungi undergo long-distance cell signalling to regulate effector production during infection is not known. Here we show that long-distance retrograde motility of early endosomes (EEs) is necessary to trigger transcription of effector-encoding genes during plant infection by the pathogenic fungus Ustilago maydis. We demonstrate that motor-dependent retrograde EE motility is necessary for regulation of effector production and secretion during host cell invasion. We further show that retrograde signalling involves the mitogen-activated kinase Crk1 that travels on EEs and participates in control of effector production. Fungal pathogens therefore undergo long-range signalling to orchestrate host invasion.

Spatiotemporal regulation of a Legionella pneumophila T4SS substrate by the metaeffector SidJ.

PubMed

Jeong, Kwang Cheol; Sexton, Jessica A; Vogel, Joseph P

2015-03-01

Modulation of host cell function is vital for intracellular pathogens to survive and replicate within host cells. Most commonly, these pathogens utilize specialized secretion systems to inject substrates (also called effector proteins) that function as toxins within host cells. Since it would be detrimental for an intracellular pathogen to immediately kill its host cell, it is essential that secreted toxins be inactivated or degraded after they have served their purpose. The pathogen Legionella pneumophila represents an ideal system to study interactions between toxins as it survives within host cells for approximately a day and its Dot/Icm type IVB secretion system (T4SS) injects a vast number of toxins. Previously we reported that the Dot/Icm substrates SidE, SdeA, SdeB, and SdeC (known as the SidE family of effectors) are secreted into host cells, where they localize to the cytoplasmic face of the Legionella containing vacuole (LCV) in the early stages of infection. SidJ, another effector that is unrelated to the SidE family, is also encoded in the sdeC-sdeA locus. Interestingly, while over-expression of SidE family proteins in a wild type Legionella strain has no effect, we found that their over-expression in a ∆sidJ mutant completely inhibits intracellular growth of the strain. In addition, we found expression of SidE proteins is toxic in both yeast and mammalian HEK293 cells, but this toxicity can be suppressed by co-expression of SidJ, suggesting that SidJ may modulate the function of SidE family proteins. Finally, we were able to demonstrate both in vivo and in vitro that SidJ acts on SidE proteins to mediate their disappearance from the LCV, thereby preventing lethal intoxication of host cells. Based on these findings, we propose that SidJ acts as a metaeffector to control the activity of other Legionella effectors.

Obtaining control of cell surface functionalizations via Pre-targeting and Supramolecular host guest interactions

NASA Astrophysics Data System (ADS)

Rood, Mark T. M.; Spa, Silvia J.; Welling, Mick M.; Ten Hove, Jan Bart; van Willigen, Danny M.; Buckle, Tessa; Velders, Aldrik H.; van Leeuwen, Fijs W. B.

2017-01-01

The use of mammalian cells for therapeutic applications is finding its way into modern medicine. However, modification or “training” of cells to make them suitable for a specific application remains complex. By envisioning a chemical toolbox that enables specific, but straight-forward and generic cellular functionalization, we investigated how membrane-receptor (pre)targeting could be combined with supramolecular host-guest interactions based on β-cyclodextrin (CD) and adamantane (Ad). The feasibility of this approach was studied in cells with membranous overexpression of the chemokine receptor 4 (CXCR4). By combining specific targeting of CXCR4, using an adamantane (Ad)-functionalized Ac-TZ14011 peptide (guest; KD = 56 nM), with multivalent host molecules that entailed fluorescent β-CD-Poly(isobutylene-alt-maleic-anhydride)-polymers with different fluorescent colors and number of functionalities, host-guest cell-surface modifications could be studied in detail. A second set of Ad-functionalized entities enabled introduction of additional surface functionalities. In addition, the attraction between CD and Ad could be used to drive cell-cell interactions. Combined we have shown that supramolecular interactions, that are based on specific targeting of an overexpressed membrane-receptor, allow specific and stable, yet reversible, surface functionalization of viable cells and how this approach can be used to influence the interaction between cells and their surroundings.

Mitochondrial cyclophilin D regulates T cell metabolic responses and disease tolerance to tuberculosis.

PubMed

Tzelepis, Fanny; Blagih, Julianna; Khan, Nargis; Gillard, Joshua; Mendonca, Laura; Roy, Dominic G; Ma, Eric H; Joubert, Philippe; Jones, Russell G; Divangahi, Maziar

2018-05-11

Mycobacterium tuberculosis ( Mtb ) is one of the most ancient human pathogens, yet the exact mechanism(s) of host defense against Mtb remains unclear. Although one-third of the world's population is chronically infected with Mtb , only 5 to 10% develop active disease. This indicates that, in addition to resistance mechanisms that control bacterial burden, the host has also evolved strategies to tolerate the presence of Mtb to limit disease severity. We identify mitochondrial cyclophilin D (CypD) as a critical checkpoint of T cell metabolism that controls the expansion of activated T cells. Although loss of CypD function in T cells led to enhanced Mtb antigen-specific T cell responses, this increased T cell response had no impact on bacterial burden. Rather, mice containing CypD-deficient T cells exhibited substantially compromised disease tolerance and succumbed to Mtb infection. This study establishes a mechanistic link between T cell-mediated immunity and disease tolerance during Mtb infection. Copyright © 2018 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

A parasitic nematode releases cytokinin that controls cell division and orchestrates feeding site formation in host plants.

PubMed

Siddique, Shahid; Radakovic, Zoran S; De La Torre, Carola M; Chronis, Demosthenis; Novák, Ondřej; Ramireddy, Eswarayya; Holbein, Julia; Matera, Christiane; Hütten, Marion; Gutbrod, Philipp; Anjam, Muhammad Shahzad; Rozanska, Elzbieta; Habash, Samer; Elashry, Abdelnaser; Sobczak, Miroslaw; Kakimoto, Tatsuo; Strnad, Miroslav; Schmülling, Thomas; Mitchum, Melissa G; Grundler, Florian M W

2015-10-13

Sedentary plant-parasitic cyst nematodes are biotrophs that cause significant losses in agriculture. Parasitism is based on modifications of host root cells that lead to the formation of a hypermetabolic feeding site (a syncytium) from which nematodes withdraw nutrients. The host cell cycle is activated in an initial cell selected by the nematode for feeding, followed by activation of neighboring cells and subsequent expansion of feeding site through fusion of hundreds of cells. It is generally assumed that nematodes manipulate production and signaling of the plant hormone cytokinin to activate cell division. In fact, nematodes have been shown to produce cytokinin in vitro; however, whether the hormone is secreted into host plants and plays a role in parasitism remained unknown. Here, we analyzed the spatiotemporal activation of cytokinin signaling during interaction between the cyst nematode, Heterodera schachtii, and Arabidopsis using cytokinin-responsive promoter:reporter lines. Our results showed that cytokinin signaling is activated not only in the syncytium but also in neighboring cells to be incorporated into syncytium. An analysis of nematode infection on mutants that are deficient in cytokinin or cytokinin signaling revealed a significant decrease in susceptibility of these plants to nematodes. Further, we identified a cytokinin-synthesizing isopentenyltransferase gene in H. schachtii and show that silencing of this gene in nematodes leads to a significant decrease in virulence due to a reduced expansion of feeding sites. Our findings demonstrate the ability of a plant-parasitic nematode to synthesize a functional plant hormone to manipulate the host system and establish a long-term parasitic interaction.

Filovirus receptor NPC1 contributes to species-specific patterns of ebolavirus susceptibility in bats

PubMed Central

Ng, Melinda; Ndungo, Esther; Kaczmarek, Maria E; Herbert, Andrew S; Binger, Tabea; Kuehne, Ana I; Jangra, Rohit K; Hawkins, John A; Gifford, Robert J; Biswas, Rohan; Demogines, Ann; James, Rebekah M; Yu, Meng; Brummelkamp, Thijn R; Drosten, Christian; Wang, Lin-Fa; Kuhn, Jens H; Müller, Marcel A; Dye, John M; Sawyer, Sara L; Chandran, Kartik

2015-01-01

Biological factors that influence the host range and spillover of Ebola virus (EBOV) and other filoviruses remain enigmatic. While filoviruses infect diverse mammalian cell lines, we report that cells from African straw-colored fruit bats (Eidolon helvum) are refractory to EBOV infection. This could be explained by a single amino acid change in the filovirus receptor, NPC1, which greatly reduces the affinity of EBOV-NPC1 interaction. We found signatures of positive selection in bat NPC1 concentrated at the virus-receptor interface, with the strongest signal at the same residue that controls EBOV infection in Eidolon helvum cells. Our work identifies NPC1 as a genetic determinant of filovirus susceptibility in bats, and suggests that some NPC1 variations reflect host adaptations to reduce filovirus replication and virulence. A single viral mutation afforded escape from receptor control, revealing a pathway for compensatory viral evolution and a potential avenue for expansion of filovirus host range in nature. DOI: http://dx.doi.org/10.7554/eLife.11785.001 PMID:26698106

Method of forming a package for MEMS-based fuel cell

DOEpatents

Morse, Jeffrey D; Jankowski, Alan F

2013-05-21

A MEMS-based fuel cell package and method thereof is disclosed. The fuel cell package comprises seven layers: (1) a sub-package fuel reservoir interface layer, (2) an anode manifold support layer, (3) a fuel/anode manifold and resistive heater layer, (4) a Thick Film Microporous Flow Host Structure layer containing a fuel cell, (5) an air manifold layer, (6) a cathode manifold support structure layer, and (7) a cap. Fuel cell packages with more than one fuel cell are formed by positioning stacks of these layers in series and/or parallel. The fuel cell package materials such as a molded plastic or a ceramic green tape material can be patterned, aligned and stacked to form three dimensional microfluidic channels that provide electrical feedthroughs from various layers which are bonded together and mechanically support a MEMS-based miniature fuel cell. The package incorporates resistive heating elements to control the temperature of the fuel cell stack. The package is fired to form a bond between the layers and one or more microporous flow host structures containing fuel cells are inserted within the Thick Film Microporous Flow Host Structure layer of the package.

Method of forming a package for mems-based fuel cell

DOEpatents

Morse, Jeffrey D.; Jankowski, Alan F.

2004-11-23

A MEMS-based fuel cell package and method thereof is disclosed. The fuel cell package comprises seven layers: (1) a sub-package fuel reservoir interface layer, (2) an anode manifold support layer, (3) a fuel/anode manifold and resistive heater layer, (4) a Thick Film Microporous Flow Host Structure layer containing a fuel cell, (5) an air manifold layer, (6) a cathode manifold support structure layer, and (7) a cap. Fuel cell packages with more than one fuel cell are formed by positioning stacks of these layers in series and/or parallel. The fuel cell package materials such as a molded plastic or a ceramic green tape material can be patterned, aligned and stacked to form three dimensional microfluidic channels that provide electrical feedthroughs from various layers which are bonded together and mechanically support a MEMOS-based miniature fuel cell. The package incorporates resistive heating elements to control the temperature of the fuel cell stack. The package is fired to form a bond between the layers and one or more microporous flow host structures containing fuel cells are inserted within the Thick Film Microporous Flow Host Structure layer of the package.

The Well-Tempered SIV Infection: Pathogenesis of SIV Infection in Natural Hosts in the Wild, with Emphasis on Virus Transmission and Early Events Post-Infection that May Contribute to Protection from Disease Progression

PubMed Central

Raehtz, Kevin; Pandrea, Ivona; Apetrei, Cristian

2016-01-01

African NHPs are infected by over 40 different simian immunodeficiency viruses. These viruses have coevolved with their hosts for long periods of time and, unlike HIV in humans, infection does not generally lead to disease progression. Chronic viral replication is maintained for the natural lifespan of the host, without loss of overall immune function. Lack of disease progression is not correlated with transmission, as SIV infection is highly prevalent in many African NHP species in the wild. The exact mechanisms by which these natural hosts of SIV avoid disease progression are still unclear, but a number of factors might play a role, including: (i) avoidance of microbial translocation from the gut lumen by preventing or repairing damage to the gut epithelium; (ii) control of immune activation and apoptosis following infection; (iii) establishment of an anti-inflammatory response that resolves chronic inflammation; (iv) maintenance of homeostasis of various immune cell populations, including NK cells, monocytes/macrophages, dendritic cells, Tregs, Th17 T-cells, and γδ T-cells; (v) restriction of CCR5 availability at mucosal sites; (vi) preservation of T-cell function associated with down-regulation of CD4 receptor. Some of these mechanisms might also be involved in protection of natural hosts from mother-to-infant SIV transmission during breastfeeding. The difficulty of performing invasive studies in the wild has prohibited investigation of the exact events surrounding transmission in natural hosts. Increased understanding of the mechanisms of SIV transmission in natural hosts, and of the early events post-transmission which may contribute to avoidance of disease progression, along with better comprehension of the factors involved in protection from SIV breastfeeding transmission in the natural hosts, could prove invaluable for the development of new prevention strategies for HIV. PMID:27394696

Functional engraftment of the medial ganglionic eminence cells in experimental stroke model.

PubMed

Daadi, Marcel M; Lee, Sang Hyung; Arac, Ahmet; Grueter, Brad A; Bhatnagar, Rishi; Maag, Anne-Lise; Schaar, Bruce; Malenka, Robert C; Palmer, Theo D; Steinberg, Gary K

2009-01-01

Currently there are no effective treatments targeting residual anatomical and behavioral deficits resulting from stroke. Evidence suggests that cell transplantation therapy may enhance functional recovery after stroke through multiple mechanisms. We used a syngeneic model of neural transplantation to explore graft-host communications that enhance cellular engraftment.The medial ganglionic eminence (MGE) cells were derived from 15-day-old transgenic rat embryos carrying green fluorescent protein (GFP), a marker, to easily track the transplanted cells. Adult rats were subjected to transient intraluminal occlusion of the medial cerebral artery. Two weeks after stroke, the grafts were deposited into four sites, along the rostro-caudal axis and medially to the stroke in the penumbra zone. Control groups included vehicle and fibroblast transplants. Animals were subjected to motor behavioral tests at 4 week posttransplant survival time. Morphological analysis demonstrated that the grafted MGE cells differentiated into multiple neuronal subtypes, established synaptic contact with host cells, increased the expression of synaptic markers, and enhanced axonal reorganization in the injured area. Initial patch-clamp recording demonstrated that the MGE cells received postsynaptic currents from host cells. Behavioral analysis showed reduced motor deficits in the rotarod and elevated body swing tests. These findings suggest that graft-host interactions influence the fate of grafted neural precursors and that functional recovery could be mediated by neurotrophic support, new synaptic circuit elaboration, and enhancement of the stroke-induced neuroplasticity.

Toxoplasma gondii TgIST co-opts host chromatin repressors dampening STAT1-dependent gene regulation and IFN-γ–mediated host defenses

PubMed Central

Brenier-Pinchart, Marie-Pierre; Bertini, Rose-Laurence; Varesano, Aurélie; De Bock, Pieter-Jan

2016-01-01

An early hallmark of Toxoplasma gondii infection is the rapid control of the parasite population by a potent multifaceted innate immune response that engages resident and homing immune cells along with pro- and counter-inflammatory cytokines. In this context, IFN-γ activates a variety of T. gondii–targeting activities in immune and nonimmune cells but can also contribute to host immune pathology. T. gondii has evolved mechanisms to timely counteract the host IFN-γ defenses by interfering with the transcription of IFN-γ–stimulated genes. We now have identified TgIST (T. gondii inhibitor of STAT1 transcriptional activity) as a critical molecular switch that is secreted by intracellular parasites and traffics to the host cell nucleus where it inhibits STAT1-dependent proinflammatory gene expression. We show that TgIST not only sequesters STAT1 on dedicated loci but also promotes shaping of a nonpermissive chromatin through its capacity to recruit the nucleosome remodeling deacetylase (NuRD) transcriptional repressor. We found that during mice acute infection, TgIST-deficient parasites are rapidly eliminated by the homing Gr1+ inflammatory monocytes, thus highlighting the protective role of TgIST against IFN-γ–mediated killing. By uncovering TgIST functions, this study brings novel evidence on how T. gondii has devised a molecular weapon of choice to take control over a ubiquitous immune gene expression mechanism in metazoans, as a way to promote long-term parasitism. PMID:27503074

Insights into Host Cell Modulation and Induction of New Cells by the Corn Smut Ustilago maydis.

PubMed

Redkar, Amey; Matei, Alexandra; Doehlemann, Gunther

2017-01-01

Many filamentous fungal pathogens induce drastic modulation of host cells causing abnormal infectious structures such as galls, or tumors that arise as a result of re-programming in the original developmental cell fate of a colonized host cell. Developmental consequences occur predominantly with biotrophic phytopathogens. This suggests that these host structures result as an outcome of efficient defense suppression and intimate fungal-host interaction to suit the pathogen's needs for completion of its infection cycle. This mini-review mainly summarizes host cell re-programming that occurs in the Ustilago maydis - maize interaction, in which the pathogen deploys cell-type specific effector proteins with varying activities. The fungus senses the physiological status and identity of colonized host cells and re-directs the endogenous developmental program of its host. The disturbance of host cell physiology and cell fate leads to novel cell shapes, increased cell size, and/or the number of host cells. We particularly highlight the strategies of U. maydis to induce physiologically varied host organs to form the characteristic tumors in both vegetative and floral parts of maize.

Tobacco mosaic virus Movement Protein Enhances the Spread of RNA Silencing

PubMed Central

Vogler, Hannes; Kwon, Myoung-Ok; Dang, Vy; Sambade, Adrian; Fasler, Monika; Ashby, Jamie; Heinlein, Manfred

2008-01-01

Eukaryotic cells restrain the activity of foreign genetic elements, including viruses, through RNA silencing. Although viruses encode suppressors of silencing to support their propagation, viruses may also exploit silencing to regulate host gene expression or to control the level of their accumulation and thus to reduce damage to the host. RNA silencing in plants propagates from cell to cell and systemically via a sequence-specific signal. Since the signal spreads between cells through plasmodesmata like the viruses themselves, virus-encoded plasmodesmata-manipulating movement proteins (MP) may have a central role in compatible virus:host interactions by suppressing or enhancing the spread of the signal. Here, we have addressed the propagation of GFP silencing in the presence and absence of MP and MP mutants. We show that the protein enhances the spread of silencing. Small RNA analysis indicates that MP does not enhance the silencing pathway but rather enhances the transport of the signal through plasmodesmata. The ability to enhance the spread of silencing is maintained by certain MP mutants that can move between cells but which have defects in subcellular localization and do not support the spread of viral RNA. Using MP expressing and non-expressing virus mutants with a disabled silencing suppressing function, we provide evidence indicating that viral MP contributes to anti-viral silencing during infection. Our results suggest a role of MP in controlling virus propagation in the infected host by supporting the spread of silencing signal. This activity of MP involves only a subset of its properties implicated in the spread of viral RNA. PMID:18389061

Molecular mechanisms of cell-cell spread of intracellular bacterial pathogens.

PubMed

Ireton, Keith

2013-07-17

Several bacterial pathogens, including Listeria monocytogenes, Shigella flexneri and Rickettsia spp., have evolved mechanisms to actively spread within human tissues. Spreading is initiated by the pathogen-induced recruitment of host filamentous (F)-actin. F-actin forms a tail behind the microbe, propelling it through the cytoplasm. The motile pathogen then encounters the host plasma membrane, forming a bacterium-containing protrusion that is engulfed by an adjacent cell. Over the past two decades, much progress has been made in elucidating mechanisms of F-actin tail formation. Listeria and Shigella produce tails of branched actin filaments by subverting the host Arp2/3 complex. By contrast, Rickettsia forms tails with linear actin filaments through a bacterial mimic of eukaryotic formins. Compared with F-actin tail formation, mechanisms controlling bacterial protrusions are less well understood. However, recent findings have highlighted the importance of pathogen manipulation of host cell-cell junctions in spread. Listeria produces a soluble protein that enhances bacterial protrusions by perturbing tight junctions. Shigella protrusions are engulfed through a clathrin-mediated pathway at 'tricellular junctions'--specialized membrane regions at the intersection of three epithelial cells. This review summarizes key past findings in pathogen spread, and focuses on recent developments in actin-based motility and the formation and internalization of bacterial protrusions.

The Unexpected Tuners: Are LncRNAs Regulating Host Translation during Infections?

PubMed Central

Knap, Primoz; Tebaldi, Toma; Di Leva, Francesca; Biagioli, Marta; Dalla Serra, Mauro; Viero, Gabriella

2017-01-01

Pathogenic bacteria produce powerful virulent factors, such as pore-forming toxins, that promote their survival and cause serious damage to the host. Host cells reply to membrane stresses and ionic imbalance by modifying gene expression at the epigenetic, transcriptional and translational level, to recover from the toxin attack. The fact that the majority of the human transcriptome encodes for non-coding RNAs (ncRNAs) raises the question: do host cells deploy non-coding transcripts to rapidly control the most energy-consuming process in cells—i.e., host translation—to counteract the infection? Here, we discuss the intriguing possibility that membrane-damaging toxins induce, in the host, the expression of toxin-specific long non-coding RNAs (lncRNAs), which act as sponges for other molecules, encoding small peptides or binding target mRNAs to depress their translation efficiency. Unravelling the function of host-produced lncRNAs upon bacterial infection or membrane damage requires an improved understanding of host lncRNA expression patterns, their association with polysomes and their function during this stress. This field of investigation holds a unique opportunity to reveal unpredicted scenarios and novel approaches to counteract antibiotic-resistant infections. PMID:29469820

Intrinsic properties of limb bud cells can be differentially reset.

PubMed

Saiz-Lopez, Patricia; Chinnaiya, Kavitha; Towers, Matthew; Ros, Maria A

2017-02-01

An intrinsic timing mechanism specifies the positional values of the zeugopod (i.e. radius/ulna) and then autopod (i.e. wrist/digits) segments during limb development. Here, we have addressed whether this timing mechanism ensures that patterning events occur only once by grafting GFP-expressing autopod progenitor cells to the earlier host signalling environment of zeugopod progenitor cells. We show by detecting Hoxa13 expression that early and late autopod progenitors fated for the wrist and phalanges, respectively, both contribute to the entire host autopod, indicating that the autopod positional value is irreversibly determined. We provide evidence that Hoxa13 provides an autopod-specific positional value that correctly allocates cells into the autopod, most likely through the control of cell-surface properties as shown by cell-cell sorting analyses. However, we demonstrate that only the earlier autopod cells can adopt the host proliferation rate to permit normal morphogenesis. Therefore, our findings reveal that the ability of embryonic cells to differentially reset their intrinsic behaviours confers robustness to limb morphogenesis. We speculate that this plasticity could be maintained beyond embryogenesis in limbs with regenerative capacity. © 2017. Published by The Company of Biologists Ltd.

The Cell Wall of the Human Fungal Pathogen Aspergillus fumigatus: Biosynthesis, Organization, Immune Response, and Virulence.

PubMed

Latgé, Jean-Paul; Beauvais, Anne; Chamilos, Georgios

2017-09-08

More than 90% of the cell wall of the filamentous fungus Aspergillus fumigatus comprises polysaccharides. Biosynthesis of the cell wall polysaccharides is under the control of three types of enzymes: transmembrane synthases, which are anchored to the plasma membrane and use nucleotide sugars as substrates, and cell wall-associated transglycosidases and glycosyl hydrolases, which are responsible for remodeling the de novo synthesized polysaccharides and establishing the three-dimensional structure of the cell wall. For years, the cell wall was considered an inert exoskeleton of the fungal cell. The cell wall is now recognized as a living organelle, since the composition and cellular localization of the different constitutive cell wall components (especially of the outer layers) vary when the fungus senses changes in the external environment. The cell wall plays a major role during infection. The recognition of the fungal cell wall by the host is essential in the initiation of the immune response. The interactions between the different pattern-recognition receptors (PRRs) and cell wall pathogen-associated molecular patterns (PAMPs) orientate the host response toward either fungal death or growth, which would then lead to disease development. Understanding the molecular determinants of the interplay between the cell wall and host immunity is fundamental to combatting Aspergillus diseases.

EDRN-WHI Pre-Clinical Colon Ca Specimens — EDRN Public Portal

Cancer.gov

Specifically, it is proposed to assess plasma proteins from postmenopausal women diagnosed with colon cancer within a span of 18 months after year-3 OS blood draw and from appropriate matched controls enrolled in the WHI OS study. The range of case-control differences sought in plasma include: 1 Detection and identification of proteins that may be derived from tumor cells through the classical secreted protein pathway and through non-classical pathways (eg protein cleavage and release) or through cell turnover. 2 Detection and identification of protein changes associated with the host response that occur during tumor development and that may be related to inflammation, angiogenesis, infiltration of tumor with host cells and other processes. 3 Identification of tumor derived proteins that induce a humoral immune response in the form of autoantibodies that are detectable at the preclinical stage.

Evolving ideas of legume evolution and diversity: a taxonomic perspective on the occurrence of nodulation.

PubMed

Sprent, Janet I

2007-01-01

Legumes evolved about 60 million years ago (Ma), and nodulation 58 Ma. Nonnodulation remains common in Caesalpinioideae, with smaller numbers in Mimosoideae and Papilionoideae. The first type of infection by bacteria may have been at junctions where lateral roots emerged, followed by formation of infection threads to confine bacteria and convey them to some cells in the developing nodule, where they were generally released into symbiosomes. Infection threads were a prerequisite for root-hair infection, a process better controlled by the host, leading to a higher degree of specificity between symbionts. An alternative process, dating from the same time and persisting in about 25% of legumes, did not involve infection threads, bacteria entering a few host cells, surrounded by an undefined matrix. These cells divided repeatedly to give uniform infected tissue, with bacteria released into symbiosomes. Such legumes may have less stringent control of nodulation processes, and are found mainly in tropical and warm temperate areas. In each type of nodule, meristems may or may not be retained, leading to indeterminate or determinate forms. Nodule morphology and structure are host-determined, but the effectiveness of nitrogen fixation is largely controlled by the bacterial symbionts, which vary greatly in genotypic and phenotypic characters.

How do viruses control mitochondria-mediated apoptosis?

PubMed

Neumann, Simon; El Maadidi, Souhayla; Faletti, Laura; Haun, Florian; Labib, Shirin; Schejtman, Andrea; Maurer, Ulrich; Borner, Christoph

2015-11-02

There is no doubt that viruses require cells to successfully reproduce and effectively infect the next host. The question is what is the fate of the infected cells? All eukaryotic cells can "sense" viral infections and exhibit defence strategies to oppose viral replication and spread. This often leads to the elimination of the infected cells by programmed cell death or apoptosis. This "sacrifice" of infected cells represents the most primordial response of multicellular organisms to viruses. Subverting host cell apoptosis, at least for some time, is therefore a crucial strategy of viruses to ensure their replication, the production of essential viral proteins, virus assembly and the spreading to new hosts. For that reason many viruses harbor apoptosis inhibitory genes, which once inside infected cells are expressed to circumvent apoptosis induction during the virus reproduction phase. On the other hand, viruses can take advantage of stimulating apoptosis to (i) facilitate shedding and hence dissemination, (ii) to prevent infected cells from presenting viral antigens to the immune system or (iii) to kill non-infected bystander and immune cells which would limit viral propagation. Hence the decision whether an infected host cell undergoes apoptosis or not depends on virus type and pathogenicity, its capacity to oppose antiviral responses of the infected cells and/or to evade any attack from immune cells. Viral genomes have therefore been adapted throughout evolution to satisfy the need of a particular virus to induce or inhibit apoptosis during its life cycle. Here we review the different strategies used by viruses to interfere with the two major apoptosis as well as with the innate immune signaling pathways in mammalian cells. We will focus on the intrinsic mitochondrial pathway and discuss new ideas about how particular viruses could activately engage mitochondria to induce apoptosis of their host. Copyright © 2015 Elsevier B.V. All rights reserved.

Copper-catalyzed azide-alkyne cycloaddition (click chemistry)-based Detection of Global Pathogen-host AMPylation on Self-assembled Human Protein Microarrays*

PubMed Central

Yu, Xiaobo; Woolery, Andrew R.; Luong, Phi; Hao, Yi Heng; Grammel, Markus; Westcott, Nathan; Park, Jin; Wang, Jie; Bian, Xiaofang; Demirkan, Gokhan; Hang, Howard C.; Orth, Kim; LaBaer, Joshua

2014-01-01

AMPylation (adenylylation) is a recently discovered mechanism employed by infectious bacteria to regulate host cell signaling. However, despite significant effort, only a few host targets have been identified, limiting our understanding of how these pathogens exploit this mechanism to control host cells. Accordingly, we developed a novel nonradioactive AMPylation screening platform using high-density cell-free protein microarrays displaying human proteins produced by human translational machinery. We screened 10,000 unique human proteins with Vibrio parahaemolyticus VopS and Histophilus somni IbpAFic2, and identified many new AMPylation substrates. Two of these, Rac2, and Rac3, were confirmed in vivo as bona fide substrates during infection with Vibrio parahaemolyticus. We also mapped the site of AMPylation of a non-GTPase substrate, LyGDI, to threonine 51, in a region regulated by Src kinase, and demonstrated that AMPylation prevented its phosphorylation by Src. Our results greatly expanded the repertoire of potential host substrates for bacterial AMPylators, determined their recognition motif, and revealed the first pathogen-host interaction AMPylation network. This approach can be extended to identify novel substrates of AMPylators with different domains or in different species and readily adapted for other post-translational modifications. PMID:25073739

Long-term live-cell imaging reveals new roles for Salmonella effector proteins SseG and SteA.

PubMed

McQuate, Sarah E; Young, Alexandra M; Silva-Herzog, Eugenia; Bunker, Eric; Hernandez, Mateo; de Chaumont, Fabrice; Liu, Xuedong; Detweiler, Corrella S; Palmer, Amy E

2017-01-01

Salmonella Typhimurium is an intracellular bacterial pathogen that infects both epithelial cells and macrophages. Salmonella effector proteins, which are translocated into the host cell and manipulate host cell components, control the ability to replicate and/or survive in host cells. Due to the complexity and heterogeneity of Salmonella infections, there is growing recognition of the need for single-cell and live-cell imaging approaches to identify and characterize the diversity of cellular phenotypes and how they evolve over time. Here, we establish a pipeline for long-term (17 h) live-cell imaging of infected cells and subsequent image analysis methods. We apply this pipeline to track bacterial replication within the Salmonella-containing vacuole in epithelial cells, quantify vacuolar replication versus survival in macrophages and investigate the role of individual effector proteins in mediating these parameters. This approach revealed that dispersed bacteria can coalesce at later stages of infection, that the effector protein SseG influences the propensity for cytosolic hyper-replication in epithelial cells, and that while SteA only has a subtle effect on vacuolar replication in epithelial cells, it has a profound impact on infection parameters in immunocompetent macrophages, suggesting differential roles for effector proteins in different infection models. © 2016 John Wiley & Sons Ltd.

Long-Term Live Cell Imaging Reveals New Roles For Salmonella Effector Proteins SseG and SteA

PubMed Central

McQuate, Sarah E.; Young, Alexandra M.; Silva-Herzog, Eugenia; Bunker, Eric; Hernandez, Mateo; de Chaumont, Fabrice; Liu, Xuedong; Detweiler, Corrella S.; Palmer, Amy E.

2016-01-01

Summary Salmonella Typhimurium is an intracellular bacterial pathogen that infects both epithelial cells and macrophages. Salmonella effector proteins, which are translocated into the host cell and manipulate host cell components, control the ability to replicate and/or survive in host cells. Due to the complexity and heterogeneity of Salmonella infections, there is growing recognition of the need for single cell and live-cell imaging approaches to identify and characterize the diversity of cellular phenotypes and how they evolve over time. Here we establish a pipeline for long-term (16 hours) live-cell imaging of infected cells and subsequent image analysis methods. We apply this pipeline to track bacterial replication within the Salmonella-containing vacuole in epithelial cells, quantify vacuolar replication versus survival in macrophages, and investigate the role of individual effector proteins in mediating these parameters. This approach revealed that dispersed bacteria can coalesce at later stages of infection, that the effector protein SseG influences the propensity for cytosolic hyperreplication in epithelial cells, and that while SteA only has a subtle effect on vacuolar replication in epithelial cells, it has a profound impact on infection parameters in immunocompetent macrophages, suggesting differential roles for effector proteins in different infection models. PMID:27376507

African swine fever virus controls the host transcription and cellular machinery of protein synthesis.

PubMed

Sánchez, Elena G; Quintas, Ana; Nogal, Marisa; Castelló, Alfredo; Revilla, Yolanda

2013-04-01

Throughout a viral infection, the infected cell reprograms the gene expression pattern in order to establish a satisfactory antiviral response. African swine fever virus (ASFV), like other complex DNA viruses, sets up a number of strategies to evade the host's defense systems, such as apoptosis, inflammation and immune responses. The capability of the virus to persist in its natural hosts and in domestic pigs, which recover from infection with less virulent isolates, suggests that the virus displays effective mechanisms to escape host defense systems. ASFV has been described to regulate the activation of several transcription factors, thus regulating the activation of specific target genes during ASFV infection. Whereas some reports have concerned about anti-apoptotic ASFV genes and the molecular mechanisms by which ASFV interferes with inducible gene transcription and immune evasion, less is yet known regarding how ASFV regulates the translational machinery in infected cells, although a recent report has shown a mechanism for favored expression of viral genes based on compartmentalization of viral mRNA and ribosomes with cellular translation factors within the virus factory. The viral mechanisms involved both in the regulation of host genes transcription and in the control of cellular protein synthesis are summarized in this review. Copyright © 2012 Elsevier B.V. All rights reserved.

Evidence for a Transketolase-Mediated Metabolic Checkpoint Governing Biotrophic Growth in Rice Cells by the Blast Fungus Magnaporthe oryzae

PubMed Central

Fernandez, Jessie; Marroquin-Guzman, Margarita; Wilson, Richard A.

2014-01-01

The blast fungus Magnaporthe oryzae threatens global food security through the widespread destruction of cultivated rice. Foliar infection requires a specialized cell called an appressorium that generates turgor to force a thin penetration hypha through the rice cuticle and into the underlying epidermal cells, where the fungus grows for the first days of infection as a symptomless biotroph. Understanding what controls biotrophic growth could open new avenues for developing sustainable blast intervention programs. Here, using molecular genetics and live-cell imaging, we dismantled M. oryzae glucose-metabolizing pathways to reveal that the transketolase enzyme, encoded by TKL1, plays an essential role in facilitating host colonization during rice blast disease. In the absence of transketolase, Δtkl1 mutant strains formed functional appressoria that penetrated rice cuticles successfully and developed invasive hyphae (IH) in rice cells from primary hyphae. However, Δtkl1 could not undertake sustained biotrophic growth or cell-to-cell movement. Transcript data and observations using fluorescently labeled histone H1:RFP fusion proteins indicated Δtkl1 mutant strains were alive in host cells but were delayed in mitosis. Mitotic delay could be reversed and IH growth restored by the addition of exogenous ATP, a metabolite depleted in Δtkl1 mutant strains. We show that ATP might act via the TOR signaling pathway, and TOR is likely a downstream target of activation for TKL1. TKL1 is also involved in controlling the migration of appressorial nuclei into primary hyphae in host cells. When taken together, our results indicate transketolase has a novel role in mediating - via ATP and TOR signaling - an in planta-specific metabolic checkpoint that controls nuclear migration from appressoria into primary hyphae, prevents mitotic delay in early IH and promotes biotrophic growth. This work thus provides new information about the metabolic strategies employed by M. oryzae to enable rice cell colonization. PMID:25188286

Diversifying selection and host adaptation in two endosymbiont genomes

PubMed Central

Brownlie, Jeremy C; Adamski, Marcin; Slatko, Barton; McGraw, Elizabeth A

2007-01-01

Background The endosymbiont Wolbachia pipientis infects a broad range of arthropod and filarial nematode hosts. These diverse associations form an attractive model for understanding host:symbiont coevolution. Wolbachia's ubiquity and ability to dramatically alter host reproductive biology also form the foundation of research strategies aimed at controlling insect pests and vector-borne disease. The Wolbachia strains that infect nematodes are phylogenetically distinct, strictly vertically transmitted, and required by their hosts for growth and reproduction. Insects in contrast form more fluid associations with Wolbachia. In these taxa, host populations are most often polymorphic for infection, horizontal transmission occurs between distantly related hosts, and direct fitness effects on hosts are mild. Despite extensive interest in the Wolbachia system for many years, relatively little is known about the molecular mechanisms that mediate its varied interactions with different hosts. We have compared the genomes of the Wolbachia that infect Drosophila melanogaster, wMel and the nematode Brugia malayi, wBm to that of an outgroup Anaplasma marginale to identify genes that have experienced diversifying selection in the Wolbachia lineages. The goal of the study was to identify likely molecular mechanisms of the symbiosis and to understand the nature of the diverse association across different hosts. Results The prevalence of selection was far greater in wMel than wBm. Genes contributing to DNA metabolism, cofactor biosynthesis, and secretion were positively selected in both lineages. In wMel there was a greater emphasis on DNA repair, cell division, protein stability, and cell envelope synthesis. Conclusion Secretion pathways and outer surface protein encoding genes are highly affected by selection in keeping with host:parasite theory. If evidence of selection on various cofactor molecules reflects possible provisioning, then both insect as well as nematode Wolbachia may be providing substances to hosts. Selection on cell envelope synthesis, DNA replication and repair machinery, heat shock, and two component switching suggest strategies insect Wolbachia may employ to cope with diverse host and intra-host environments. PMID:17470297

Human MicroRNA miR-532-5p Exhibits Antiviral Activity against West Nile Virus via Suppression of Host Genes SESTD1 and TAB3 Required for Virus Replication

PubMed Central

Slonchak, Andrii; Shannon, Rory P.; Pali, Gabor

2015-01-01

ABSTRACT West Nile virus (WNV) is a mosquito-transmitted flavivirus that naturally circulates between mosquitos and birds but can also infect humans, causing severe neurological disease. The early host response to WNV infection in vertebrates primarily relies on the type I interferon pathway; however, recent studies suggest that microRNAs (miRNAs) may also play a notable role. In this study, we assessed the role of host miRNAs in response to WNV infection in human cells. We employed small RNA sequencing (RNA-seq) analysis to determine changes in the expression of host miRNAs in HEK293 cells infected with an Australian strain of WNV, Kunjin (WNVKUN), and identified a number of host miRNAs differentially expressed in response to infection. Three of these miRNAs were confirmed to be significantly upregulated in infected cells by quantitative reverse transcription (qRT)-PCR and Northern blot analyses, and one of them, miR-532-5p, exhibited a significant antiviral effect against WNVKUN infection. We have demonstrated that miR-532-5p targets and downregulates expression of the host genes SESTD1 and TAB3 in human cells. Small interfering RNA (siRNA) depletion studies showed that both SESTD1 and TAB3 were required for efficient WNVKUN replication. We also demonstrated upregulation of mir-532-5p expression and a corresponding decrease in the expression of its targets, SESTD1 and TAB3, in the brains of WNVKUN -infected mice. Our results show that upregulation of miR-532-5p and subsequent suppression of the SESTD1 and TAB3 genes represent a host antiviral response aimed at limiting WNVKUN infection and highlight the important role of miRNAs in controlling RNA virus infections in mammalian hosts. IMPORTANCE West Nile virus (WNV) is a significant viral pathogen that poses a considerable threat to human health across the globe. There is no specific treatment or licensed vaccine available for WNV, and deeper insight into how the virus interacts with the host is required to facilitate their development. In this study, we addressed the role of host microRNAs (miRNAs) in antiviral response to WNV in human cells. We identified miR-532-5p as a novel antiviral miRNA and showed that it is upregulated in response to WNV infection and suppresses the expression of the host genes TAB3 and SESTD1 required for WNV replication. Our results show that upregulation of miR-532-5p and subsequent suppression of the SESTD1 and TAB3 genes represent an antiviral response aimed at limiting WNV infection and highlight the important role of miRNAs in controlling virus infections in mammalian hosts. PMID:26676784

Corneal Tissue From Dry Eye Donors Leads to Enhanced Graft Rejection.

PubMed

Inomata, Takenori; Hua, Jing; Nakao, Takeshi; Shiang, Tina; Chiang, Homer; Amouzegar, Afsaneh; Dana, Reza

2018-01-01

To assess the effect of dry eye disease (DED) in graft donors on dendritic cell (DC) maturation, host T-cell sensitization, and corneal allograft rejection. Corneas of control (healthy donor) and DED mice (C57BL/6) were transplanted onto fully allogeneic naive BALB/c recipients (n = 10 mice/group). Long-term allograft survival was evaluated for 8 weeks. Corneas and draining lymph nodes (dLNs) were harvested at posttransplantation day 14 (n = 5 mice/group). The frequencies of MHCII CD11c DCs in the donor corneas and host dLNs and the frequencies of interferon (IFN)-γ and IL-17 CD4 T cells and Foxp3 expression by Tregs in host dLNs were investigated using flow cytometry. The enzyme-linked immunospot assay was used to assess host T-cell allosensitization through direct and indirect pathways (n = 3/group). Recipients of DED donor corneas showed significantly reduced graft survival (10%) compared with control mice (50% survival, P = 0.022), and had significantly increased frequencies of mature DCs in the grafted cornea (DED donor 44.0% ± 0.36% vs. healthy donor 35.4 ± 0.5%; P < 0.0001) and host dLNs (DED donor 25.1% ± 0.66% vs. healthy donor 13.7% ± 1.6%; P = 0.005). Frequencies of IFN-γ and IL-17 T cells were increased in the dLNs of recipients of DED corneas, whereas the expression (mean fluorescence intensity) of Foxp3 in Tregs was decreased significantly in these mice (DED donor 6004 ± 193 vs. healthy donor 6806 ± 81; P = 0.0002). Enzyme-linked immunospot analysis showed that the direct pathway of allosensitization was significantly amplified in recipients of grafts with DED (P = 0.0146). Our results indicate that DED in the donor is a significant risk factor for subsequent corneal allograft rejection.

Transcriptome analysis reveals the host response to Schmallenberg virus in bovine cells and antagonistic effects of the NSs protein.

PubMed

Blomström, Anne-Lie; Gu, Quan; Barry, Gerald; Wilkie, Gavin; Skelton, Jessica K; Baird, Margaret; McFarlane, Melanie; Schnettler, Esther; Elliott, Richard M; Palmarini, Massimo; Kohl, Alain

2015-04-19

Schmallenberg virus (SBV) is a member of the Orthobunyavirus genus (Bunyaviridae family) causing malformations and abortions in ruminants. Although, as for other members of this family/genus, the non-structural protein NSs has been shown to be an interferon antagonist, very little is known regarding the overall inhibitory effects and targets of orthobunyavirus NSs proteins on host gene expression during infection. Therefore, using RNA-seq this study describes changes to the transcriptome of primary bovine cells following infection with Schmallenberg virus (SBV) or with a mutant lacking the non-structural protein NSs (SBVdelNSs) providing a detailed comparison of the effect of NSs expression on the host cell. The sequence reads from all samples (uninfected cells, SBV and SBVdelNSs) assembled well to the bovine host reference genome (on average 87.43% of the reads). During infection with SBVdelNSs, 649 genes were differentially expressed compared to uninfected cells (78.7% upregulated) and many of these were known antiviral and IFN-stimulated genes. On the other hand, only nine genes were differentially expressed in SBV infected cells compared to uninfected control cells, demonstrating the strong inhibitory effect of NSs on cellular gene expression. However, the majority of the genes that were expressed during SBV infection are involved in restriction of viral replication and spread indicating that SBV does not completely manage to shutdown the host antiviral response. In this study we show the effects of SBV NSs on the transcriptome of infected cells as well as the cellular response to wild type SBV. Although NSs is very efficient in shutting down genes of the host innate response, a number of possible antiviral factors were identified. Thus the data from this study can serve as a base for more detailed mechanistic studies of SBV and other orthobunyaviruses.

Pyrimidinergic Receptor Activation Controls Toxoplasma gondii Infection in Macrophages

PubMed Central

Moreira-Souza, Aline Cristina Abreu; Marinho, Ygor; Correa, Gladys; Santoro, Giani França; Coutinho, Claudia Mara Lara Melo; Vommaro, Rossiane Claudia; Coutinho-Silva, Robson

2015-01-01

Infection by the protozoan parasite Toxoplasma gondii is highly prevalent worldwide and may have serious clinical manifestations in immunocompromised patients. T. gondii is an obligate intracellular parasite that infects almost any cell type in mammalian hosts, including immune cells. The immune cells express purinergic P2 receptors in their membrane – subdivided into P2Y and P2X subfamilies - whose activation is important for infection control. Here, we examined the effect of treatment with UTP and UDP in mouse peritoneal macrophages infected with T. gondii tachyzoites. Treatment with these nucleotides reduced parasitic load by 90%, but did not increase the levels of the inflammatory mediators NO and ROS, nor did it modulate host cell death by apoptosis or necrosis. On the other hand, UTP and UDP treatments induced early egress of tachyzoites from infected macrophages, in a Ca2+-dependent manner, as shown by scanning electron microscopy analysis, and videomicroscopy. In subsequent infections, prematurely egressed parasites had reduced infectivity, and could neither replicate nor inhibit the fusion of lysosomes to the parasitophorous vacuole. The use of selective agonists and antagonists of the receptor subtypes P2Y2 and P2Y4 and P2Y6 showed that premature parasite egress may be mediated by the activation of these receptor subtypes. Our results suggest that the activity of P2Y host cell receptors controls T. gondii infection in macrophages, highlighting the importance of pyrimidinergic signaling for innate immune system response against infection. Finally the P2Y receptors should be considered as new target for the development of drugs against T. gondii infection. PMID:26192447

Single-cell sequencing provides clues about the host interactions of segmented filamentous bacteria (SFB)

PubMed Central

Pamp, Sünje J.; Harrington, Eoghan D.; Quake, Stephen R.; Relman, David A.; Blainey, Paul C.

2012-01-01

Segmented filamentous bacteria (SFB) are host-specific intestinal symbionts that comprise a distinct clade within the Clostridiaceae, designated Candidatus Arthromitus. SFB display a unique life cycle within the host, involving differentiation into multiple cell types. The latter include filaments that attach intimately to intestinal epithelial cells, and from which “holdfasts” and spores develop. SFB induce a multifaceted immune response, leading to host protection from intestinal pathogens. Cultivation resistance has hindered characterization of these enigmatic bacteria. In the present study, we isolated five SFB filaments from a mouse using a microfluidic device equipped with laser tweezers, generated genome sequences from each, and compared these sequences with each other, as well as to recently published SFB genome sequences. Based on the resulting analyses, SFB appear to be dependent on the host for a variety of essential nutrients. SFB have a relatively high abundance of predicted proteins devoted to cell cycle control and to envelope biogenesis, and have a group of SFB-specific autolysins and a dynamin-like protein. Among the five filament genomes, an average of 8.6% of predicted proteins were novel, including a family of secreted SFB-specific proteins. Four ADP-ribosyltransferase (ADPRT) sequence types, and a myosin-cross-reactive antigen (MCRA) protein were discovered; we hypothesize that they are involved in modulation of host responses. The presence of polymorphisms among mouse SFB genomes suggests the evolution of distinct SFB lineages. Overall, our results reveal several aspects of SFB adaptation to the mammalian intestinal tract. PMID:22434425

Immunobiologic effects of cytokine gene transfer of the B16-BL6 melanoma.

PubMed

Strome, S E; Krauss, J C; Cameron, M J; Forslund, K; Shu, S; Chang, A E

1993-12-01

The genetic modification of tumors offers an approach to modulate the host immune response to relatively weak native tumor antigens. We examined the immunobiologic effects of various cytokine genes transferred into the poorly immunogenic B16-BL6 murine melanoma. Retroviral expression vectors containing cDNAs for interleukin 2, interleukin 4, interferon gamma, or a neomycin-resistant control were electroporated into a B16-BL6 tumor clone. Selected transfected clones were examined for in vitro cytokine secretion and in vivo tumorigenicity. When cells from individual clones were injected intradermally into syngeneic mice, the interleukin 4-secreting clone grew significantly slower than did the neomycin-resistant transfected control, while the growth of the interleukin 2- and interferon gamma-expressing clones was not affected. Despite minimal cytokine secretion by interferon gamma-transfected cells, these cells expressed upregulated major histocompatibility class I antigen and were more susceptible to lysis by allosensitized cytotoxic T lymphocytes compared with parental or neomycin-resistant transfected tumor targets. We observed diverse immunobiologic effects associated with cytokine gene transfer into the B16-BL6 melanoma. Interleukin 4 transfection of tumor resulted in decreased in vivo tumorigenicity that may be related to a host immune response. Further studies to evaluate the host T-cell response to these gene-modified tumors are being investigated.

The interactions of intracellular Protista and their host cells, with special reference to heterotrophic organisms.

PubMed

Bannister, L H

1979-04-11

Intracellular genera are found in all the major groups of Protista, but are particularly common among the dinoflagellates, trypanosomatid zooflagellates and suctorian ciliates; the Sporozoa are nearly all intracellular at some stage of their life, and the Microspora entirely so. Intracellular forms can dwell in the nucleus, within phagosomal or other vacuoles or may lie free in the hyaloplasm of their host cells. Organisms tend to select their hosts from a restricted taxonomic range although there are some notable exceptions. There is also great variation in the types of host cell inhabited. There are various reasons for both host and cell selectivity including recognition phenomena at the cell surfaces. Invasion of host cells is usually preceded by surface interactions with the invader. Some organisms depend upon phagocytosis for entry, but others induce host cells to engulf them by non-phagocytic means or invade by microinjection through the host plasma membrane. Protista avoid lysosomal destruction by their resistance to enzyme attack, by surrounding themselves with lysosome-inhibiting vacuoles, by escaping from the phagosomal system into the hyaloplasm and by choosing host cells which lack lysosomes. Nutrition of intracellular heterotrophic organisms involves some degree of competition with the host cell's metabolism as well as erosion of host cell cytoplasm. In Plasmodium infections, red cells are made more permeable to required nutrients by the action of the parasite on the host cell membrane. The parasite is often dependent upon the host cell for complex nutrients which it cannot synthesize for itself. Intracellular forms often profoundly modify the structure and metabolism of the host cell or interfere with its growth and multiplication. This may result in the final lysis of the host cell at the end of the intracellular phase or before the infection of other cells. Certain types of intracellular organisms may have arisen initially as forms attached to the cell surface of digestive or other organs, but the intracellular habit appears to have arisen independently in several groups of Protista.

Use of an optical trap for study of host-pathogen interactions for dynamic live cell imaging.

PubMed

Tam, Jenny M; Castro, Carlos E; Heath, Robert J W; Mansour, Michael K; Cardenas, Michael L; Xavier, Ramnik J; Lang, Matthew J; Vyas, Jatin M

2011-07-28

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system(1, 2); however, the lack of spatial and temporal control between the phagocytic cell and microbe has rendered focused observations into the initial interactions of host response to pathogens difficult. Historically, intercellular contact events such as phagocytosis(3) have been imaged by mixing two cell types, and then continuously scanning the field-of-view to find serendipitous intercellular contacts at the appropriate stage of interaction. The stochastic nature of these events renders this process tedious, and it is difficult to observe early or fleeting events in cell-cell contact by this approach. This method requires finding cell pairs that are on the verge of contact, and observing them until they consummate their contact, or do not. To address these limitations, we use optical trapping as a non-invasive, non-destructive, but fast and effective method to position cells in culture. Optical traps, or optical tweezers, are increasingly utilized in biological research to capture and physically manipulate cells and other micron-sized particles in three dimensions(4). Radiation pressure was first observed and applied to optical tweezer systems in 1970(5, 6), and was first used to control biological specimens in 1987(7). Since then, optical tweezers have matured into a technology to probe a variety of biological phenomena(8-13). We describe a method(14) that advances live cell imaging by integrating an optical trap with spinning disk confocal microscopy with temperature and humidity control to provide exquisite spatial and temporal control of pathogenic organisms in a physiological environment to facilitate interactions with host cells, as determined by the operator. Live, pathogenic organisms like Candida albicans and Aspergillus fumigatus, which can cause potentially lethal, invasive infections in immunocompromised individuals(15, 16) (e.g. AIDS, chemotherapy, and organ transplantation patients), were optically trapped using non-destructive laser intensities and moved adjacent to macrophages, which can phagocytose the pathogen. High resolution, transmitted light and fluorescence-based movies established the ability to observe early events of phagocytosis in living cells. To demonstrate the broad applicability in immunology, primary T-cells were also trapped and manipulated to form synapses with anti-CD3 coated microspheres in vivo, and time-lapse imaging of synapse formation was also obtained. By providing a method to exert fine spatial control of live pathogens with respect to immune cells, cellular interactions can be captured by fluorescence microscopy with minimal perturbation to cells and can yield powerful insight into early responses of innate and adaptive immunity.

Intestinal Helminths Regulate Lethal Acute Graft Versus Host Disease and Preserve Graft Versus Tumor Effect in Mice

PubMed Central

Li, Yue; Chen, Hung-lin; Bannick, Nadine; Henry, Michael; Holm, Adrian N.; Metwali, Ahmed; Urban, Joseph F.; Rothman, Paul B.; Weiner, George J.; Blazar, Bruce R.; Elliott, David E.; Ince, M. Nedim

2014-01-01

Donor T lymphocyte transfer with hematopoietic stem cells suppresses residual tumor growth (graft-versus-tumor; GVT) in cancer patients undergoing bone marrow transplantation (BMT). However, donor T cell reactivity to host organs causes severe and potentially lethal inflammation, called graft-versus-host disease (GVHD). High dose steroids or other immune suppressives are used to treat GVHD that have limited ability to control the inflammation while incurring long-term toxicity. Novel strategies are needed to modulate GVHD, preserve GVT and improve the outcome of BMT. Regulatory T cells (Tregs) control alloantigen-sensitized inflammation of GVHD, sustain GVT and prevent mortality in bone marrow transplantation. Helminths colonizing the alimentary tract dramatically increase the Treg activity, thereby modulating intestinal or systemic inflammatory responses. These observations led us to hypothesize that helminths can regulate GVHD and maintain GVT in mice. Acute GVHD was induced in helminth (Heligmosomoides polygyrus)-infected or uninfected Balb/C recipients of C57BL/6 donor grafts. Helminth infection suppressed donor T cell inflammatory cytokine generation along with reduction in GVHD lethality and maintenance of GVT. H. polygyrus colonization promoted the survival of TGFβ generating recipient Tregs after a conditioning regimen with total body irradiation and led to a TGFβ-dependent in vivo expansion/maturation of donor Tregs after BMT. Helminths did not control GVHD, when T cells unresponsive to TGFβ-mediated immune regulation were used as donor T lymphocytes. These results suggest that helminths suppress acute GVHD, employing regulatory T cells and TGFβ-dependent pathways in mice. Helminthic regulation of GVHD and GVT through intestinal immune conditioning may improve the outcome of BMT. PMID:25527786

Helminths: Immunoregulation and Inflammatory Diseases—Which Side Are Trichinella spp. and Toxocara spp. on?

PubMed Central

Aranzamendi, Carmen; Sofronic-Milosavljevic, Ljiljana; Pinelli, Elena

2013-01-01

Macropathogens, such as multicellular helminths, are considered masters of immunoregulation due to their ability to escape host defense and establish chronic infections. Molecular crosstalk between the host and the parasite starts immediately after their encounter, which influences the course and development of both the innate and adaptive arms of the immune response. Helminths can modulate dendritic cells (DCs) function and induce immunosuppression which is mediated by a regulatory network that includes regulatory T (Treg) cells, regulatory B (Breg) cells, and alternatively activated macrophages (AAMs). In this way, helminths suppress and control both parasite-specific and unrelated immunopathology in the host such as Th1-mediated autoimmune and Th2-mediated allergic diseases. However, certain helminths favour the development or exacerbation of allergic responses. In this paper, the cell types that play an essential role in helminth-induced immunoregulation, the consequences for inflammatory diseases, and the contrasting effects of Toxocara and Trichinella infection on allergic manifestations are discussed. PMID:23365718

Natural Killer T Cells: An Ecological Evolutionary Developmental Biology Perspective

PubMed Central

Kumar, Amrendra; Suryadevara, Naveenchandra; Hill, Timothy M.; Bezbradica, Jelena S.; Van Kaer, Luc; Joyce, Sebastian

2017-01-01

Type I natural killer T (NKT) cells are innate-like T lymphocytes that recognize glycolipid antigens presented by the MHC class I-like protein CD1d. Agonistic activation of NKT cells leads to rapid pro-inflammatory and immune modulatory cytokine and chemokine responses. This property of NKT cells, in conjunction with their interactions with antigen-presenting cells, controls downstream innate and adaptive immune responses against cancers and infectious diseases, as well as in several inflammatory disorders. NKT cell properties are acquired during development in the thymus and by interactions with the host microbial consortium in the gut, the nature of which can be influenced by NKT cells. This latter property, together with the role of the host microbiota in cancer therapy, necessitates a new perspective. Hence, this review provides an initial approach to understanding NKT cells from an ecological evolutionary developmental biology (eco-evo-devo) perspective. PMID:29312339

Natural Killer T Cells: An Ecological Evolutionary Developmental Biology Perspective.

PubMed

Kumar, Amrendra; Suryadevara, Naveenchandra; Hill, Timothy M; Bezbradica, Jelena S; Van Kaer, Luc; Joyce, Sebastian

2017-01-01

Type I natural killer T (NKT) cells are innate-like T lymphocytes that recognize glycolipid antigens presented by the MHC class I-like protein CD1d. Agonistic activation of NKT cells leads to rapid pro-inflammatory and immune modulatory cytokine and chemokine responses. This property of NKT cells, in conjunction with their interactions with antigen-presenting cells, controls downstream innate and adaptive immune responses against cancers and infectious diseases, as well as in several inflammatory disorders. NKT cell properties are acquired during development in the thymus and by interactions with the host microbial consortium in the gut, the nature of which can be influenced by NKT cells. This latter property, together with the role of the host microbiota in cancer therapy, necessitates a new perspective. Hence, this review provides an initial approach to understanding NKT cells from an ecological evolutionary developmental biology (eco-evo-devo) perspective.

HilD and PhoP independently regulate the expression of grhD1, a novel gene required for Salmonella Typhimurium invasion of host cells.

PubMed

Banda, María M; López, Carolina; Manzo, Rubiceli; Rico-Pérez, Gadea; García, Pablo; Rosales-Reyes, Roberto; De la Cruz, Miguel A; Soncini, Fernando C; García-Del Portillo, Francisco; Bustamante, Víctor H

2018-03-19

When Salmonella is grown in the nutrient-rich lysogeny broth (LB), the AraC-like transcriptional regulator HilD positively controls the expression of genes required for Salmonella invasion of host cells, such as the Salmonella pathogenicity island 1 (SPI-1) genes. However, in minimal media, the two-component system PhoP/Q activates the expression of genes necessary for Salmonella replication inside host cells, such as the SPI-2 genes. Recently, we found that the SL1344_1872 hypothetical gene, located in a S. Typhimurium genomic island, is co-expressed with the SPI-1 genes. In this study we demonstrate that HilD induces indirectly the expression of SL1344_1872 when S. Typhimurium is grown in LB; therefore, we named SL1344_1872 as grhD1 for gene regulated by HilD. Furthermore, we found that PhoP positively controls the expression of grhD1, independently of HilD, when S. Typhimurium is grown in LB or N-minimal medium. Moreover, we demonstrate that the grhD1 gene is required for the invasion of S. Typhimurium into epithelial cells, macrophages and fibroblasts, as well as for the intestinal inflammatory response caused by S. Typhimurium in mice. Thus, our results reveal a novel virulence factor of Salmonella, whose expression is positively and independently controlled by the HilD and PhoP transcriptional regulators.

Specific allogeneic unresponsiveness in the adult host: present-day experimental models

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rapaport, F.T.; Bachvaroff, R.J.; Cronkite, E.

As part of a long-term intensive effort to apply the induction of adult allogensic unresponsiveness to the transplantation problem, two techniques to control the variability in the persistence of immunologically competent postthymic cells iin the treated host and/or the inoculum of autologous marrow returned to the host after irradiation are described. The first consisted of exposing the peripheral blood of prospective recipients to a 5-week course of extra-corporeal irradiation (ECIB), the other of exposing the stored autologous marrow scheduled to repopulate a given recipient to methyl-prednisolone (MPd) and DNase prior to renifusion into the recipient. Serial analysis of bone marrowmore » cell samples at various intervals before and after treatment was undertaken. The significance of the disappearance of a particular population of nonnuclear cells from the samples, and the association of such disappearance with increased success in the induction of allogeneic unresponsiveness is discussed. (ACR)« less

The Production of lnterleukin-1 Receptor Antagonist by Human Bronchogenic Carcinoma

PubMed Central

Smith, Daniel R.; Kunkel, Steven L.; Standiford, Theodore J.; Chensue, Stephen W.; Rolfe, Mark W.; Orringer, Mark B.; Whyte, Richard I.; Burdick, Marie D.; Danforth, Jean M.; Gilbert, Andrew R.; Strieter, Robert M.

1993-01-01

Bronchogenic carcinoma displays an aggressive clinical course that may reflect a capacity to evade host defenses. We postulated that tumors may elaborate interleukin-1 receptor antagonist protein (IRAP) to escape host interleukin-1-dependent responses. Homogenates of human bronchogenic lung tumors demonstrated significant increases of IRAP compared with normal lung tissue controls (n = 48). There was no significant difference in interleukin-1 β levels between tumor and normal lung tissue. Immunohistochemical staining localized IRAP to tumor cells. Semiquantitative pathological analysis demonstrated a modest inflammatory cell infiltrate with qualitative differences between tumors of different histology. Western blot analysis of tumor homogenates demonstrated several molecular weight forms of IRAP. Finally, antigenic IRAP was detected in supernatants of the human bronchogenic carcinoma cell line (A549) maintained in vitro. These findings illustrate the capacity of bronchogenic tumors to produce and secrete IRAP that may be important in tumor evasion of host defenses. ImagesFigure 3Figure 4 PMID:8362978

Cnidarian-microbe interactions and the origin of innate immunity in metazoans.

PubMed

Bosch, Thomas C G

2013-01-01

Most epithelia in animals are colonized by microbial communities. These resident microbes influence fitness and thus ecologically important traits of their hosts, ultimately forming a metaorganism consisting of a multicellular host and a community of associated microorganisms. Recent discoveries in the cnidarian Hydra show that components of the innate immune system as well as transcriptional regulators of stem cells are involved in maintaining homeostasis between animals and their resident microbiota. Here I argue that components of the innate immune system with its host-specific antimicrobial peptides and a rich repertoire of pattern recognition receptors evolved in early-branching metazoans because of the need to control the resident beneficial microbes, not because of invasive pathogens. I also propose a mutual intertwinement between the stem cell regulatory machinery of the host and the resident microbiota composition, such that disturbances in one trigger a restructuring and resetting of the other.

What’s the Damage? The Impact of Pathogens on Pathways that Maintain Host Genome Integrity

PubMed Central

Weitzman, Matthew D.; Weitzman, Jonathan B.

2014-01-01

Maintaining genome integrity and transmission of intact genomes is critical for cellular, organismal, and species survival. Cells can detect damaged DNA, activate checkpoints, and either enable DNA repair or trigger apoptosis to eliminate the damaged cell. Aberrations in these mechanisms lead to somatic mutations and genetic instability, which are hallmarks of cancer. Considering the long history of host-microbe coevolution, an impact of microbial infection on host genome integrity is not unexpected, and emerging links between microbial infections and oncogenesis further reinforce this idea. In this review, we compare strategies employed by viruses, bacteria, and parasites to alter, subvert, or otherwise manipulate host DNA damage and repair pathways. We highlight how microbes contribute to tumorigenesis by directly inducing DNA damage, inactivating checkpoint controls, or manipulating repair processes. We also discuss indirect effects resulting from inflammatory responses, changes in cellular metabolism, nuclear architecture, and epigenome integrity, and the associated evolutionary tradeoffs. PMID:24629335

Pathogen Trojan Horse Delivers Bioactive Host Protein to Alter Maize Anther Cell Behavior in Situ.

PubMed

van der Linde, Karina; Timofejeva, Ljudmilla; Egger, Rachel L; Ilau, Birger; Hammond, Reza; Teng, Chong; Meyers, Blake C; Doehlemann, Gunther; Walbot, Virginia

2018-03-01

Small proteins are crucial signals during development, host defense, and physiology. The highly spatiotemporal restricted functions of signaling proteins remain challenging to study in planta. The several month span required to assess transgene expression, particularly in flowers, combined with the uncertainties from transgene position effects and ubiquitous or overexpression, makes monitoring of spatiotemporally restricted signaling proteins lengthy and difficult. This situation could be rectified with a transient assay in which protein deployment is tightly controlled spatially and temporally in planta to assess protein functions, timing, and cellular targets as well as to facilitate rapid mutagenesis to define functional protein domains. In maize ( Zea mays ), secreted ZmMAC1 (MULTIPLE ARCHESPORIAL CELLS1) was proposed to trigger somatic niche formation during anther development by participating in a ligand-receptor module. Inspired by Homer's Trojan horse myth, we engineered a protein delivery system that exploits the secretory capabilities of the maize smut fungus Ustilago maydis , to allow protein delivery to individual cells in certain cell layers at precise time points. Pathogen-supplied ZmMAC1 cell-autonomously corrected both somatic cell division and differentiation defects in mutant Zm mac1-1 anthers. These results suggest that exploiting host-pathogen interactions may become a generally useful method for targeting host proteins to cell and tissue types to clarify cellular autonomy and to analyze steps in cell responses. © 2018 American Society of Plant Biologists. All rights reserved.

Thermal Stress Promotes Host Mitochondrial Degradation in Symbiotic Cnidarians: Are the Batteries of the Reef Going to Run Out?

PubMed Central

Dunn, Simon R.; Pernice, Mathieu; Green, Kathryn; Hoegh-Guldberg, Ove; Dove, Sophie G.

2012-01-01

The symbiotic relationship between cnidarians and their dinoflagellate symbionts, Symbiodinium spp, which underpins the formation of tropical coral reefs, can be destabilized by rapid changes to environmental conditions. Although some studies have concluded that a breakdown in the symbiosis begins with increased reactive oxygen species (ROS) generation within the symbiont due to a decoupling of photosynthesis, others have reported the release of viable symbionts via a variety of host cell derived mechanisms. We explored an alternative model focused upon changes in host cnidarian mitochondrial integrity in response to thermal stress. Mitochondria are often likened to being batteries of the cell, providing energy in the form of ATP, and controlling cellular pathway activation and ROS generation. The overall morphology of host mitochondria was compared to that of associated symbionts under an experimental thermal stress using confocal and electron microscopy. The results demonstrate that hyperthermic stress induces the degradation of cnidarian host mitochondria that is independent of symbiont cellular deterioration. The potential sites of host mitochondrial disruption were also assessed by measuring changes in the expression of genes associated with electron transport and ATP synthesis using quantitative RT-PCR. The primary site of degradation appeared to be downstream of complex III of the electron transport chain with a significant reduction in host cytochrome c and ATP synthase expression. The consequences of reduced expression could limit the capacity of the host to mitigate ROS generation and maintain both organelle integrity and cellular energy supplies. The disruption of host mitochondria, cellular homeostasis, and subsequent cell death irrespective of symbiont integrity highlights the importance of the host response to thermal stress and in symbiosis dysfunction that has substantial implications for understanding how coral reefs will survive in the face of climate change. PMID:22815696

The Dialogue of the Host-Parasite Relationship: Leishmania spp. and Trypanosoma cruzi Infection.

PubMed

de Morais, Carlos Gustavo Vieira; Castro Lima, Ana Karina; Terra, Rodrigo; dos Santos, Rosiane Freire; Da-Silva, Silvia Amaral Gonçalves; Dutra, Patrícia Maria Lourenço

2015-01-01

The intracellular protozoa Leishmania spp. and Trypanosoma cruzi and the causative agents of Leishmaniasis and Chagas disease, respectively, belong to the Trypanosomatidae family. Together, these two neglected tropical diseases affect approximately 25 million people worldwide. Whether the host can control the infection or develops disease depends on the complex interaction between parasite and host. Parasite surface and secreted molecules are involved in triggering specific signaling pathways essential for parasite entry and intracellular survival. The recognition of the parasite antigens by host immune cells generates a specific immune response. Leishmania spp. and T. cruzi have a multifaceted repertoire of strategies to evade or subvert the immune system by interfering with a range of signal transduction pathways in host cells, which causes the inhibition of the protective response and contributes to their persistence in the host. The current therapeutic strategies in leishmaniasis and trypanosomiasis are very limited. Efficacy is variable, toxicity is high, and the emergence of resistance is increasingly common. In this review, we discuss the molecular basis of the host-parasite interaction of Leishmania and Trypanosoma cruzi infection and their mechanisms of subverting the immune response and how this knowledge can be used as a tool for the development of new drugs.

Golgi-associated Rab14, a new regulator for Chlamydia trachomatis infection outcome.

PubMed

Capmany, Anahí; Leiva, Natalia; Damiani, María Teresa

2011-09-01

Chlamydia trachomatis is the causing agent of the most frequent bacterial sexually-transmitted diseases worldwide and is an underlying cause of chronic pelvic inflammatory diseases and cervical cancer. It is an obligate intracellular bacterium that establishes a close relationship with the Golgi complex and parasites the biosynthetic machinery of host cells. In a recent study, we have demonstrated that Rab14, a newly-described Golgi-associated Rab, is involved in the delivery of sphingolipids to the growing bacteria-containing vacuole. The interference with Rab14-controlled trafficking pathways delays chlamydial inclusion enlargement, decreases bacterial lipid uptake, negatively impact on bacterial differentiation, and reduces bacterial progeny and infectivity. C. trachomatis manipulation of host trafficking pathways for the acquisition of endogenously-biosynthesized nutrients arises as one of the characteristics of this highly evolved pathogen. The development of therapeutic strategies targeted to interfere with bacterium-host cell interaction is a new challenge for pharmacological approaches to control chlamydial infections.

Golgi-associated Rab14, a new regulator for Chlamydia trachomatis infection outcome

PubMed Central

Capmany, Anahí; Leiva, Natalia

2011-01-01

Chlamydia trachomatis is the causing agent of the most frequent bacterial sexually-transmitted diseases worldwide and is an underlying cause of chronic pelvic inflammatory diseases and cervical cancer. It is an obligate intracellular bacterium that establishes a close relationship with the Golgi complex and parasites the biosynthetic machinery of host cells. In a recent study, we have demonstrated that Rab14, a newly-described Golgi-associated Rab, is involved in the delivery of sphingolipids to the growing bacteria-containing vacuole. The interference with Rab14-controlled trafficking pathways delays chlamydial inclusion enlargement, decreases bacterial lipid uptake, negatively impact on bacterial differentiation, and reduces bacterial progeny and infectivity. C. trachomatis manipulation of host trafficking pathways for the acquisition of endogenously-biosynthesized nutrients arises as one of the characteristics of this highly evolved pathogen. The development of therapeutic strategies targeted to interfere with bacterium-host cell interaction is a new challenge for pharmacological approaches to control chlamydial infections. PMID:22046472

Cytotoxic Killing and Immune Evasion by Repair

NASA Astrophysics Data System (ADS)

Chan, Cliburn; George, Andrew J. T.; Stark, Jaroslav

2007-07-01

The interaction between the immune system and pathogens is a complex one, with pathogens constantly developing new ways of evading destruction by the immune system. The immune system's task is made even harder when the pathogen in question is an intra-cellular one (such as a virus or certain bacteria) and it is necessary to kill the infected host cell in order to eliminate the pathogen. This causes damage to the host, and such killing therefore needs to be carefully controlled, particularly in tissues with poor regenerative potential, or those involved in the immune response itself. Host cells therefore possess repair mechanisms which can counteract killing by immune cells. These in turn can be subverted by pathogens which up-regulate the resistance of infected cells to killing. In this paper, we explore the hypothesis that this repair process plays an important role in determining the efficacy of evasion and escape from immune control. We model a situation where cytotoxic T lymphocytes (CTL) and natural killer (NK) cells kill pathogen-infected and tumour cells by directed secretion of preformed granules containing perforin and granzymes. Resistance to such killing can be conferred by the expression of serine protease inhibitors (serpins). These are utilized by several virally infected and tumour cells, as well as playing a role in the protection of host bystander, immune and immuneprivileged cells. We build a simple stochastic model of cytotoxic killing, where serpins can neutralize granzymes stoichiometrically by forming an irreversible complex, and the survival of the cell is determined by the balance between serpin depletion and replenishment, which in its simplest form is equivalent to the well known shot noise process. We use existing analytical results for this process, and additional simulations to analyse the effects of repair on cytotoxic killing. We then extend the model to the case of a replicating target cell population, which gives a branching process coupled to shot noise. We show how the process of repair can have a major impact on the dynamics of pathogen evasion and escape of tumour cells from immune surveillance

Mammalian Synthetic Biology: Time for Big MACs.

PubMed

Martella, Andrea; Pollard, Steven M; Dai, Junbiao; Cai, Yizhi

2016-10-21

The enabling technologies of synthetic biology are opening up new opportunities for engineering and enhancement of mammalian cells. This will stimulate diverse applications in many life science sectors such as regenerative medicine, development of biosensing cell lines, therapeutic protein production, and generation of new synthetic genetic regulatory circuits. Harnessing the full potential of these new engineering-based approaches requires the design and assembly of large DNA constructs-potentially up to chromosome scale-and the effective delivery of these large DNA payloads to the host cell. Random integration of large transgenes, encoding therapeutic proteins or genetic circuits into host chromosomes, has several drawbacks such as risks of insertional mutagenesis, lack of control over transgene copy-number and position-specific effects; these can compromise the intended functioning of genetic circuits. The development of a system orthogonal to the endogenous genome is therefore beneficial. Mammalian artificial chromosomes (MACs) are functional, add-on chromosomal elements, which behave as normal chromosomes-being replicating and portioned to daughter cells at each cell division. They are deployed as useful gene expression vectors as they remain independent from the host genome. MACs are maintained as a single-copy and can accommodate multiple gene expression cassettes of, in theory, unlimited DNA size (MACs up to 10 megabases have been constructed). MACs therefore enabled control over ectopic gene expression and represent an excellent platform to rapidly prototype and characterize novel synthetic gene circuits without recourse to engineering the host genome. This review describes the obstacles synthetic biologists face when working with mammalian systems and how the development of improved MACs can overcome these-particularly given the spectacular advances in DNA synthesis and assembly that are fuelling this research area.

Cell-Specific IRF-3 Responses Protect against West Nile Virus Infection by Interferon-Dependent and -Independent Mechanisms

PubMed Central

Daffis, Stephane; Samuel, Melanie A; Keller, Brian C; Gale, Michael; Diamond, Michael S

2007-01-01

Interferon regulatory factor (IRF)-3 is a master transcription factor that activates host antiviral defense programs. Although cell culture studies suggest that IRF-3 promotes antiviral control by inducing interferon (IFN)-β, near normal levels of IFN-α and IFN-β were observed in IRF-3−/− mice after infection by several RNA and DNA viruses. Thus, the specific mechanisms by which IRF-3 modulates viral infection remain controversial. Some of this disparity could reflect direct IRF-3-dependent antiviral responses in specific cell types to control infection. To address this and determine how IRF-3 coordinates an antiviral response, we infected IRF-3−/− mice and two primary cells relevant for West Nile virus (WNV) pathogenesis, macrophages and cortical neurons. IRF-3−/− mice were uniformly vulnerable to infection and developed elevated WNV burdens in peripheral and central nervous system tissues, though peripheral IFN responses were largely normal. Whereas wild-type macrophages basally expressed key host defense molecules, including RIG-I, MDA5, ISG54, and ISG56, and restricted WNV infection, IRF-3−/− macrophages lacked basal expression of these host defense genes and supported increased WNV infection and IFN-α and IFN-β production. In contrast, wild-type cortical neurons were highly permissive to WNV and did not basally express RIG-I, MDA5, ISG54, and ISG56. IRF-3−/− neurons lacked induction of host defense genes and had blunted IFN-α and IFN-β production, yet exhibited only modestly increased viral titers. Collectively, our data suggest that cell-specific IRF-3 responses protect against WNV infection through both IFN-dependent and -independent programs. PMID:17676997

Innate Immune Responses of Bat and Human Cells to Filoviruses: Commonalities and Distinctions

PubMed Central

Kuzmin, Ivan V.; Schwarz, Toni M.; Ilinykh, Philipp A.; Jordan, Ingo; Ksiazek, Thomas G.; Sachidanandam, Ravi; Basler, Christopher F.

2017-01-01

ABSTRACT Marburg (MARV) and Ebola (EBOV) viruses are zoonotic pathogens that cause severe hemorrhagic fever in humans. The natural reservoir of MARV is the Egyptian rousette bat (Rousettus aegyptiacus); that of EBOV is unknown but believed to be another bat species. The Egyptian rousette develops subclinical productive infection with MARV but is refractory to EBOV. Interaction of filoviruses with hosts is greatly affected by the viral interferon (IFN)-inhibiting domains (IID). Our study was aimed at characterization of innate immune responses to filoviruses and the role of filovirus IID in bat and human cells. The study demonstrated that EBOV and MARV replicate to similar levels in all tested cell lines, indicating that permissiveness for EBOV at cell and organism levels do not necessarily correlate. Filoviruses, particularly MARV, induced a potent innate immune response in rousette cells, which was generally stronger than that in human cells. Both EBOV VP35 and VP24 IID were found to suppress the innate immune response in rousette cells, but only VP35 IID appeared to promote virus replication. Along with IFN-α and IFN-β, IFN-γ was demonstrated to control filovirus infection in bat cells but not in human cells, suggesting host species specificity of the antiviral effect. The antiviral effects of bat IFNs appeared not to correlate with induction of IFN-stimulated genes 54 and 56, which were detected in human cells ectopically expressing bat IFN-α and IFN-β. As bat IFN-γ induced the type I IFN pathway, its antiviral effect is likely to be partially induced via cross talk. IMPORTANCE Bats serve as reservoirs for multiple emerging viruses, including filoviruses, henipaviruses, lyssaviruses, and zoonotic coronaviruses. Although there is no evidence for symptomatic disease caused by either Marburg or Ebola viruses in bats, spillover of these viruses into human populations causes deadly outbreaks. The reason for the lack of symptomatic disease in bats infected with filoviruses remains unknown. The outcome of a virus-host interaction depends on the ability of the host immune system to suppress viral replication and the ability of a virus to counteract the host defenses. Our study is a comparative analysis of the host innate immune response to either MARV or EBOV infection in bat and human cells and the role of viral interferon-inhibiting domains in the host innate immune responses. The data are useful for understanding the interactions of filoviruses with natural and accidental hosts and for identification of factors that influence filovirus evolution. PMID:28122983

Innate Immune Responses of Bat and Human Cells to Filoviruses: Commonalities and Distinctions.

PubMed

Kuzmin, Ivan V; Schwarz, Toni M; Ilinykh, Philipp A; Jordan, Ingo; Ksiazek, Thomas G; Sachidanandam, Ravi; Basler, Christopher F; Bukreyev, Alexander

2017-04-15

Marburg (MARV) and Ebola (EBOV) viruses are zoonotic pathogens that cause severe hemorrhagic fever in humans. The natural reservoir of MARV is the Egyptian rousette bat ( Rousettus aegyptiacus ); that of EBOV is unknown but believed to be another bat species. The Egyptian rousette develops subclinical productive infection with MARV but is refractory to EBOV. Interaction of filoviruses with hosts is greatly affected by the viral interferon (IFN)-inhibiting domains (IID). Our study was aimed at characterization of innate immune responses to filoviruses and the role of filovirus IID in bat and human cells. The study demonstrated that EBOV and MARV replicate to similar levels in all tested cell lines, indicating that permissiveness for EBOV at cell and organism levels do not necessarily correlate. Filoviruses, particularly MARV, induced a potent innate immune response in rousette cells, which was generally stronger than that in human cells. Both EBOV VP35 and VP24 IID were found to suppress the innate immune response in rousette cells, but only VP35 IID appeared to promote virus replication. Along with IFN-α and IFN-β, IFN-γ was demonstrated to control filovirus infection in bat cells but not in human cells, suggesting host species specificity of the antiviral effect. The antiviral effects of bat IFNs appeared not to correlate with induction of IFN-stimulated genes 54 and 56, which were detected in human cells ectopically expressing bat IFN-α and IFN-β. As bat IFN-γ induced the type I IFN pathway, its antiviral effect is likely to be partially induced via cross talk. IMPORTANCE Bats serve as reservoirs for multiple emerging viruses, including filoviruses, henipaviruses, lyssaviruses, and zoonotic coronaviruses. Although there is no evidence for symptomatic disease caused by either Marburg or Ebola viruses in bats, spillover of these viruses into human populations causes deadly outbreaks. The reason for the lack of symptomatic disease in bats infected with filoviruses remains unknown. The outcome of a virus-host interaction depends on the ability of the host immune system to suppress viral replication and the ability of a virus to counteract the host defenses. Our study is a comparative analysis of the host innate immune response to either MARV or EBOV infection in bat and human cells and the role of viral interferon-inhibiting domains in the host innate immune responses. The data are useful for understanding the interactions of filoviruses with natural and accidental hosts and for identification of factors that influence filovirus evolution. Copyright © 2017 American Society for Microbiology.

Ebola virus. Two-pore channels control Ebola virus host cell entry and are drug targets for disease treatment.

PubMed

Sakurai, Yasuteru; Kolokoltsov, Andrey A; Chen, Cheng-Chang; Tidwell, Michael W; Bauta, William E; Klugbauer, Norbert; Grimm, Christian; Wahl-Schott, Christian; Biel, Martin; Davey, Robert A

2015-02-27

Ebola virus causes sporadic outbreaks of lethal hemorrhagic fever in humans, but there is no currently approved therapy. Cells take up Ebola virus by macropinocytosis, followed by trafficking through endosomal vesicles. However, few factors controlling endosomal virus movement are known. Here we find that Ebola virus entry into host cells requires the endosomal calcium channels called two-pore channels (TPCs). Disrupting TPC function by gene knockout, small interfering RNAs, or small-molecule inhibitors halted virus trafficking and prevented infection. Tetrandrine, the most potent small molecule that we tested, inhibited infection of human macrophages, the primary target of Ebola virus in vivo, and also showed therapeutic efficacy in mice. Therefore, TPC proteins play a key role in Ebola virus infection and may be effective targets for antiviral therapy. Copyright © 2015, American Association for the Advancement of Science.

Host control of human papillomavirus infection and disease.

PubMed

Doorbar, John

2018-02-01

Most human papillomaviruses cause inapparent infections, subtly affecting epithelial homeostasis, to ensure genome persistence in the epithelial basal layer. As with conspicuous papillomas, these self-limiting lesions shed viral particles to ensure population level maintenance and depend on a balance between viral gene expression, immune cell stimulation and immune surveillance for persistence. The complex immune evasion strategies, characteristic of high-risk HPV types, also allow the deregulated viral gene expression that underlies neoplasia. Neoplasia occurs at particular epithelial sites where vulnerable cells such as the reserve or cuboidal cells of the cervical transformation zone are found. Beta papillomavirus infection can also predispose an individual with immune deficiencies to the development of cancers. The host control of HPV infections thus involves local interactions between keratinocytes and the adaptive immune response. Effective immune detection and surveillance limits overt disease, leading to HPV persistence as productive microlesions or in a true latent state. Copyright © 2017. Published by Elsevier Ltd.

Prior Population Immunity Reduces the Expected Impact of CTL-Inducing Vaccines for Pandemic Influenza Control

PubMed Central

Bolton, Kirsty J.; McCaw, James M.; Brown, Lorena; Jackson, David; Kedzierska, Katherine; McVernon, Jodie

2015-01-01

Vaccines that trigger an influenza-specific cytotoxic T cell (CTL) response may aid pandemic control by limiting the transmission of novel influenza A viruses (IAV). We consider interventions with hypothetical CTL-inducing vaccines in a range of epidemiologically plausible pandemic scenarios. We estimate the achievable reduction in the attack rate, and, by adopting a model linking epidemic progression to the emergence of IAV variants, the opportunity for antigenic drift. We demonstrate that CTL-inducing vaccines have limited utility for modifying population-level outcomes if influenza-specific T cells found widely in adults already suppress transmission and prove difficult to enhance. Administration of CTL-inducing vaccines that are efficacious in "influenza-experienced" and "influenza-naive" hosts can likely slow transmission sufficiently to mitigate a moderate IAV pandemic. However if neutralising cross-reactive antibody to an emerging IAV are common in influenza-experienced hosts, as for the swine-variant H3N2v, boosting CTL immunity may be ineffective at reducing population spread, indicating that CTL-inducing vaccines are best used against novel subtypes such as H7N9. Unless vaccines cannot readily suppress transmission from infected hosts with naive T cell pools, targeting influenza-naive hosts is preferable. Such strategies are of enhanced benefit if naive hosts are typically intensively mixing children and when a subset of experienced hosts have pre-existing neutralising cross-reactive antibody. We show that CTL-inducing vaccination campaigns may have greater power to suppress antigenic drift than previously suggested, and targeting adults may be the optimal strategy to achieve this when the vaccination campaign does not have the power to curtail the attack rate. Our results highlight the need to design interventions based on pre-existing cellular immunity and knowledge of the host determinants of vaccine efficacy, and provide a framework for assessing the performance requirements of high-impact CTL-inducing vaccines. PMID:25811654

Prior population immunity reduces the expected impact of CTL-inducing vaccines for pandemic influenza control.

PubMed

Bolton, Kirsty J; McCaw, James M; Brown, Lorena; Jackson, David; Kedzierska, Katherine; McVernon, Jodie

2015-01-01

Vaccines that trigger an influenza-specific cytotoxic T cell (CTL) response may aid pandemic control by limiting the transmission of novel influenza A viruses (IAV). We consider interventions with hypothetical CTL-inducing vaccines in a range of epidemiologically plausible pandemic scenarios. We estimate the achievable reduction in the attack rate, and, by adopting a model linking epidemic progression to the emergence of IAV variants, the opportunity for antigenic drift. We demonstrate that CTL-inducing vaccines have limited utility for modifying population-level outcomes if influenza-specific T cells found widely in adults already suppress transmission and prove difficult to enhance. Administration of CTL-inducing vaccines that are efficacious in "influenza-experienced" and "influenza-naive" hosts can likely slow transmission sufficiently to mitigate a moderate IAV pandemic. However if neutralising cross-reactive antibody to an emerging IAV are common in influenza-experienced hosts, as for the swine-variant H3N2v, boosting CTL immunity may be ineffective at reducing population spread, indicating that CTL-inducing vaccines are best used against novel subtypes such as H7N9. Unless vaccines cannot readily suppress transmission from infected hosts with naive T cell pools, targeting influenza-naive hosts is preferable. Such strategies are of enhanced benefit if naive hosts are typically intensively mixing children and when a subset of experienced hosts have pre-existing neutralising cross-reactive antibody. We show that CTL-inducing vaccination campaigns may have greater power to suppress antigenic drift than previously suggested, and targeting adults may be the optimal strategy to achieve this when the vaccination campaign does not have the power to curtail the attack rate. Our results highlight the need to design interventions based on pre-existing cellular immunity and knowledge of the host determinants of vaccine efficacy, and provide a framework for assessing the performance requirements of high-impact CTL-inducing vaccines.

Characterization of the Population of the Sulfur-Oxidizing Symbiont of Codakia orbicularis (Bivalvia, Lucinidae) by Single-Cell Analyses▿ †

PubMed Central

Caro, Audrey; Gros, Olivier; Got, Patrice; De Wit, Rutger; Troussellier, Marc

2007-01-01

We investigated the characteristics of the sulfur-oxidizing symbiont hosted in the gills of Codakia orbicularis, a bivalve living in shallow marine tropical environments. Special attention was paid to describing the heterogeneity of the population by using single-cell approaches including flow cytometry (FCM) and different microscopic techniques and by analyzing a cell size fractionation experiment. Up to seven different subpopulations were distinguished by FCM based on nucleic acid content and light side scattering of the cells. The cell size analysis of symbionts showed that the symbiotic population was very heterogeneous in size, i.e., ranging from 0.5 to 5 μm in length, with variable amounts of intracellular sulfur. The side-scatter signal analyzed by FCM, which is often taken as a proxy of cell size, was greatly influenced by the sulfur content of the symbionts. FCM revealed an important heterogeneity in the relative nucleic acid content among the subclasses. The larger cells contained exceptionally high levels of nucleic acids, suggesting that these cells contained multiple copies of their genome, i.e., ranging from one copy for the smaller cells to more than four copies for the larger cells. The proportion of respiring symbionts (5-cyano-2,3-ditolyl-terazolium chloride positive) in the bacteriocytes of Codakia revealed that around 80% of the symbionts hosted by Codakia maintain respiratory activity throughout the year. These data allowed us to gain insight into the functioning of the symbionts within the host and to propose some hypotheses on how the growth of the symbionts is controlled by the host. PMID:17259363

Lymphoproliferative and Gamma Interferon Responses to Stress-Regulated Mycobacterium avium subsp. paratuberculosis Recombinant Proteins

PubMed Central

Gurung, Ratna B.; Begg, Douglas J.; Purdie, Auriol C.; de Silva, Kumudika; Bannantine, John P.

2014-01-01

Johne's disease in ruminants is a chronic infection of the intestines caused by Mycobacterium avium subsp. paratuberculosis. An important strategy to control disease is early detection, and a potentially efficient method for early detection is measurement of cell-mediated immune responses developed by the host in response to exposure or infection. One method is to measure lymphoproliferation and cytokine release from the host cells when exposed to the organism or parts of the organism. In this study, 10 recombinant M. avium subsp. paratuberculosis proteins known to be upregulated under in vitro stress conditions were evaluated by examining their ability to evoke memory as a result of exposure by vaccination or oral challenge with live Mycobacterium avium subsp. paratuberculosis. Out of 10 proteins, MAP2698c was found to induce higher cell-mediated immune responses in vaccinated and challenged sheep in comparison to healthy controls. The findings suggest that not all stress-regulated proteins have the diagnostic potential to detect cell-mediated immune responses in ovine paratuberculosis. PMID:24695774

Gut Microbiota: From Microorganisms to Metabolic Organ Influencing Obesity.

PubMed

Stephens, Richard W; Arhire, Lidia; Covasa, Mihai

2018-05-01

This review summarizes the current understanding of the relationship between gut microbiota and the host as it pertains to the regulation of energy balance and obesity. The paper begins with a brief description of the gut microbiota environment, distribution, and its unique symbiotic relationship with the host. The way that enviromental factors influence microbiota composition and subsequent impact on the host are then described. Next, the mechanisms linking gut dysbiosis with obesity are discussed, and finally current challenges and limitations in understanding the role of gut microbiota in control of obesity are presented. Gut microbiota has been implicated in regulation of fat storage, as well as gut dysbiosis, thus contributing to the development of obesity, insulin resistance, hyperglycemia and hyperlipidemia. However, the underlying mechanisms of these processes are far from being clear and will require complex preclinical and clinical interdisciplinary studies of bacteria and host cell-to-cell interactions. There is a need for a better understanding of how changes in gut microbiota composition can impact energy balance and thus control weight gain. This may represent a promising avenue in the race to develop nonsurgical treatments for obesity. © 2018 The Obesity Society.

Cell Cycle-Dependent Phosphorylation of Theileria annulata Schizont Surface Proteins

PubMed Central

von Schubert, Conrad; Wastling, Jonathan M.; Heussler, Volker T.; Woods, Kerry L.

2014-01-01

The invasion of Theileria sporozoites into bovine leukocytes is rapidly followed by the destruction of the surrounding host cell membrane, allowing the parasite to establish its niche within the host cell cytoplasm. Theileria infection induces host cell transformation, characterised by increased host cell proliferation and invasiveness, and the activation of anti-apoptotic genes. This process is strictly dependent on the presence of a viable parasite. Several host cell kinases, including PI3-K, JNK, CK2 and Src-family kinases, are constitutively activated in Theileria-infected cells and contribute to the transformed phenotype. Although a number of host cell molecules, including IkB kinase and polo-like kinase 1 (Plk1), are recruited to the schizont surface, very little is known about the schizont molecules involved in host-parasite interactions. In this study we used immunofluorescence to detect phosphorylated threonine (p-Thr), serine (p-Ser) and threonine-proline (p-Thr-Pro) epitopes on the schizont during host cell cycle progression, revealing extensive schizont phosphorylation during host cell interphase. Furthermore, we established a quick protocol to isolate schizonts from infected macrophages following synchronisation in S-phase or mitosis, and used mass spectrometry to detect phosphorylated schizont proteins. In total, 65 phosphorylated Theileria proteins were detected, 15 of which are potentially secreted or expressed on the surface of the schizont and thus may be targets for host cell kinases. In particular, we describe the cell cycle-dependent phosphorylation of two T. annulata surface proteins, TaSP and p104, both of which are highly phosphorylated during host cell S-phase. TaSP and p104 are involved in mediating interactions between the parasite and the host cell cytoskeleton, which is crucial for the persistence of the parasite within the dividing host cell and the maintenance of the transformed state. PMID:25077614

Origins of endothelial and osteogenic cells in the subcutaneous collagen gel implant.

PubMed

Bilic-Curcic, I; Kalajzic, Z; Wang, L; Rowe, D W

2005-11-01

The interdependent relationship between vascular endothelial cells and osteoblasts during bone formation and fracture healing has been long appreciated. This paper reports a heterotopic implant model using FGF-2-expanded bone marrow stromal cells (BMSC) derived from Tie2eGFP (endothelial marker) and pOBCol3.6GFPcyan or topaz (early osteoblast marker) transgenic mice to appreciate the host/donor relationships of cells participating in the process of heterotopic bone formation. The study included various combinations of Tie2eGFP and pOBCol3.6GFPcyan and topaz transgenics as BMSC or whole bone marrow (WBM) donors and also as recipients. Rat tail collagen was used as a carrier of donor cells and implantation was done in lethally irradiated mice rescued with WBM injection. Development of ossicles in the implants was followed weekly during the 4- to 5-week long post-implantation period. By 4-5 weeks after total body irradiation (TBI) and implantation, a well-formed bone spicule had developed that was invested with bone marrow. Experiments showed absolute dominance of donor-derived cells in the formation of endothelial-lined vessels inside the implants as well as the marrow stromal-derived osteogenic cells. Host-derived fibroblasts and osteogenic cells were confined to the fibrous capsule surrounding the implant. In addition, cells lining the endosteal surface of newly formed marrow space carrying a pOBCol3.6GFP marker were observed that were contributed by WBM donor cells and the host. Thus, FGF-2-expanded BMSC appear to be a source of endothelial and osteogenic progenitor cells capable of eliciting heterotopic bone formation independent of cells from the host. This model should be useful for understanding the interactions between these two cell types that control osteogenic differentiation in vivo.

A global RNA-seq-driven analysis of CHO host and production cell lines reveals distinct differential expression patterns of genes contributing to recombinant antibody glycosylation.

PubMed

Könitzer, Jennifer D; Müller, Markus M; Leparc, Germán; Pauers, Martin; Bechmann, Jan; Schulz, Patrick; Schaub, Jochen; Enenkel, Barbara; Hildebrandt, Tobias; Hampel, Martin; Tolstrup, Anne B

2015-09-01

Boehringer Ingelheim uses two CHO-DG44 lines for manufacturing biotherapeutics, BI-HEX-1 and BI-HEX-2, which produce distinct cell type-specific antibody glycosylation patterns. A recently established CHO-K1 descended host, BI-HEX-K1, generates antibodies with glycosylation profiles differing from CHO-DG44. Manufacturing process development is significantly influenced by these unique profiles. To investigate the underlying glycosylation related gene expression, we leveraged our CHO host and production cell RNA-seqtranscriptomics and product quality database together with the CHO-K1 genome. We observed that each BI-HEX host and antibody producing cell line has a unique gene expression fingerprint. CHO-DG44 cells only transcribe Fut10, Gfpt2 and ST8Sia6 when expressing antibodies. BI-HEX-K1 cells express ST8Sia6 at host cell level. We detected a link between BI-HEX-1/BI-HEX-2 antibody galactosylation and mannosylation and the gene expression of the B4galt gene family and genes controlling mannose processing. Furthermore, we found major differences between the CHO-DG44 and CHO-K1 lineages in the expression of sialyl transferases and enzymes synthesizing sialic acid precursors, providing a rationale for the lack of immunogenic NeuGc/NGNA synthesis in CHO. Our study highlights the value of systems biotechnology to understand glycoprotein synthesis and product glycoprofiles. Such data improve future production clone selection and process development strategies for better steering of biotherapeutic product quality. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Differentiation of presumptive primordial germ cell (pPGC)-like cells in explants into PGCs in experimental tadpoles

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ikenishi, K.; Okuda, T.; Nakazato, S.

1984-05-01

A single blastomere containing the ''germ plasm'' of 32-cell stage Xenopus embryos was cultured with (/sup 3/H)thymidine until the control embryos developed to the neurula stage. The explants, showing a spherical mass in which the nuclei of all cells were labeled, were implanted into the prospective place of presumptive primordial germ cells (pPGCs) in the endodermal cell mass of unlabeled host embryos of the neurula stage. Labeled PGCs as well as unlabeled, host PGCs were found in the genital ridges of experimental tadpoles. This indicates that the precursor of germ cells, corresponding to pPGCs in normal embryos of the neurulamore » stage, in the explants migrated to genital ridges just at the right moment to become PGCs, and suggests that the developmental process progressed normally, even in the explants, as far as the differentiation of pPGCs is concerned.« less

Modes of Human T Cell Leukemia Virus Type 1 Transmission, Replication and Persistence

PubMed Central

Carpentier, Alexandre; Barez, Pierre-Yves; Hamaidia, Malik; Gazon, Hélène; de Brogniez, Alix; Perike, Srikanth; Gillet, Nicolas; Willems, Luc

2015-01-01

Human T-cell leukemia virus type 1 (HTLV-1) is a retrovirus that causes cancer (Adult T cell Leukemia, ATL) and a spectrum of inflammatory diseases (mainly HTLV-associated myelopathy—tropical spastic paraparesis, HAM/TSP). Since virions are particularly unstable, HTLV-1 transmission primarily occurs by transfer of a cell carrying an integrated provirus. After transcription, the viral genomic RNA undergoes reverse transcription and integration into the chromosomal DNA of a cell from the newly infected host. The virus then replicates by either one of two modes: (i) an infectious cycle by virus budding and infection of new targets and (ii) mitotic division of cells harboring an integrated provirus. HTLV-1 replication initiates a series of mechanisms in the host including antiviral immunity and checkpoint control of cell proliferation. HTLV-1 has elaborated strategies to counteract these defense mechanisms allowing continuous persistence in humans. PMID:26198240

Capture of cell culture-derived influenza virus by lectins: strain independent, but host cell dependent.

PubMed

Opitz, Lars; Zimmermann, Anke; Lehmann, Sylvia; Genzel, Yvonne; Lübben, Holger; Reichl, Udo; Wolff, Michael W

2008-12-01

Strategies to control influenza outbreaks are focused mainly on prophylactic vaccination. Human influenza vaccines are trivalent blends of different virus subtypes. Therefore and due to frequent antigenic drifts, strain independent manufacturing processes are required for vaccine production. This study verifies the strain independency of a capture method based on Euonymus europaeus lectin-affinity chromatography (EEL-AC) for downstream processing of influenza viruses under various culture conditions propagated in MDCK cells. A comprehensive lectin binding screening was conducted for two influenza virus types from the season 2007/2008 (A/Wisconsin/67/2005, B/Malaysia/2506/2004) including a comparison of virus-lectin interaction by surface plasmon resonance technology. EEL-AC resulted in a reproducible high product recovery rate and a high degree of contaminant removal in the case of both MDCK cell-derived influenza virus types demonstrating clearly the general applicability of EEL-AC. In addition, host cell dependency of EEL-AC was studied with two industrial relevant cell lines: Vero and MDCK cells. However, the choice of the host cell lines is known to lead to different product glycosylation profiles. Hence, altered lectin specificities have been observed between the two cell lines, requiring process adaptations between different influenza vaccine production systems.

CD56-enriched donor cell infusion after post-transplantation cyclophosphamide for haploidentical transplantation of advanced myeloid malignancies is associated with prompt reconstitution of mature natural killer cells and regulatory T cells with reduced incidence of acute graft versus host disease: A pilot study.

PubMed

Jaiswal, Sarita Rani; Zaman, Shamsur; Nedunchezhian, Murugaiyan; Chakrabarti, Aditi; Bhakuni, Prakash; Ahmed, Margoob; Sharma, Kanika; Rawat, Sheh; O'donnell, Paul; Chakrabarti, Suparno

2017-04-01

We conducted a pilot study on the feasibility of CD56-enriched donor cell infusion after post-transplantation cyclophosphamide (PTCy) for 10 patients with advanced myeloid malignancies undergoing haploidentical peripheral blood stem cell transplantation with cyclosporine alone as graft-versus-host disease (GVHD) prophylaxis and compared the outcome and immune reconstitution with a control group of 20 patients undergoing the same without CD56-enriched donor cell infusion. An early and rapid surge of mature NK cells as well as CD4 + T cells and regulatory T cells (Tregs) was noted compared with the control group. KIR of donor phenotype reconstituted as early as day 30 with expression of CD56 dim CD16 + NKG2A - KIR + phenotype. None experienced viral or fungal infections, and non-relapse mortality was 10% only. The incidence of grade 2-4 acute GVHD was 50% in the control group with none in the CD56 group (P = 0.01). Only two had de novo chronic GVHD in each group. Relapse occurred in five patients in CD56 group with a median follow-up of 12 months, similar to the control group. Our preliminary data show that CD56 + donor cell infusion after PTCy and short-course cyclosporine is feasible with prompt engraftment, rapid reconstitution of CD4 + T cells, Tregs and NK cells and reduced incidence of acute GVHD. Copyright © 2017 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

Anaplasma phagocytophilum MSP4 and HSP70 Proteins Are Involved in Interactions with Host Cells during Pathogen Infection

PubMed Central

Contreras, Marinela; Alberdi, Pilar; Mateos-Hernández, Lourdes; Fernández de Mera, Isabel G.; García-Pérez, Ana L.; Vancová, Marie; Villar, Margarita; Ayllón, Nieves; Cabezas-Cruz, Alejandro; Valdés, James J.; Stuen, Snorre; Gortazar, Christian; de la Fuente, José

2017-01-01

Anaplasma phagocytophilum transmembrane and surface proteins play a role during infection and multiplication in host neutrophils and tick vector cells. Recently, A. phagocytophilum Major surface protein 4 (MSP4) and Heat shock protein 70 (HSP70) were shown to be localized on the bacterial membrane, with a possible role during pathogen infection in ticks. In this study, we hypothesized that A. phagocytophilum MSP4 and HSP70 have similar functions in tick-pathogen and host-pathogen interactions. To address this hypothesis, herein we characterized the role of these bacterial proteins in interaction and infection of vertebrate host cells. The results showed that A. phagocytophilum MSP4 and HSP70 are involved in host-pathogen interactions, with a role for HSP70 during pathogen infection. The analysis of the potential protective capacity of MSP4 and MSP4-HSP70 antigens in immunized sheep showed that MSP4-HSP70 was only partially protective against pathogen infection. This limited protection may be associated with several factors, including the recognition of non-protective epitopes by IgG in immunized lambs. Nevertheless, these antigens may be combined with other candidate protective antigens for the development of vaccines for the control of human and animal granulocytic anaplasmosis. Focusing on the characterization of host protective immune mechanisms and protein-protein interactions at the host-pathogen interface may lead to the discovery and design of new effective protective antigens. PMID:28725639

Thalidomide enhances both primary and secondary host resistances to Listeria monocytogenes infection by a neutrophil-related mechanism in female B6C3F1 mice

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Tai L.; Chi, Rui P.; Karrow, Niel A.

2005-12-15

Previously, we have reported that thalidomide can modulate the immune responses in female B6C3F1 mice. Furthermore, thalidomide immunomodulation increased primary host resistance to intravenously infected Listeria monocytogenes. The present study was intended to evaluate the mechanisms underlying the enhanced host resistance to L. monocytogenes by focusing on the neutrophils. Female B6C3F1 mice were treated intraperitoneally with thalidomide (100 mg/kg) for 15 days. Exposure to thalidomide increased the numbers of neutrophils in the spleens and livers of L. monocytogenes-infected mice when compared to the L. monocytogenes-infected control mice. Additionally, the percentage of neutrophils was also significantly increased after Thd treatment inmore » L. monocytogenes-infected mice. Further studies using antibodies to deplete corresponding cells indicated that thalidomide-mediated increase in primary host resistance (both the moribundity and colony counts in the liver and spleen) to L. monocytogenes infection was due to its effect on neutrophils but not CD8{sup +} T cells or NK cells. Finally, Thd exposure also increased host resistance to secondary host resistance to L. monocytogenes infection, and depletion of neutrophils abolished the protective effect. In conclusion, thalidomide enhanced host resistance to both primary and secondary L. monocytogenes infections by a neutrophil-related mechanism in female B6C3F1 mice.« less

Anaplasma phagocytophilum MSP4 and HSP70 Proteins Are Involved in Interactions with Host Cells during Pathogen Infection.

PubMed

Contreras, Marinela; Alberdi, Pilar; Mateos-Hernández, Lourdes; Fernández de Mera, Isabel G; García-Pérez, Ana L; Vancová, Marie; Villar, Margarita; Ayllón, Nieves; Cabezas-Cruz, Alejandro; Valdés, James J; Stuen, Snorre; Gortazar, Christian; de la Fuente, José

2017-01-01

Anaplasma phagocytophilum transmembrane and surface proteins play a role during infection and multiplication in host neutrophils and tick vector cells. Recently, A. phagocytophilum Major surface protein 4 (MSP4) and Heat shock protein 70 (HSP70) were shown to be localized on the bacterial membrane, with a possible role during pathogen infection in ticks. In this study, we hypothesized that A. phagocytophilum MSP4 and HSP70 have similar functions in tick-pathogen and host-pathogen interactions. To address this hypothesis, herein we characterized the role of these bacterial proteins in interaction and infection of vertebrate host cells. The results showed that A. phagocytophilum MSP4 and HSP70 are involved in host-pathogen interactions, with a role for HSP70 during pathogen infection. The analysis of the potential protective capacity of MSP4 and MSP4-HSP70 antigens in immunized sheep showed that MSP4-HSP70 was only partially protective against pathogen infection. This limited protection may be associated with several factors, including the recognition of non-protective epitopes by IgG in immunized lambs. Nevertheless, these antigens may be combined with other candidate protective antigens for the development of vaccines for the control of human and animal granulocytic anaplasmosis. Focusing on the characterization of host protective immune mechanisms and protein-protein interactions at the host-pathogen interface may lead to the discovery and design of new effective protective antigens.

Development of hyper osmotic resistant CHO host cells for enhanced antibody production.

PubMed

Kamachi, Yasuharu; Omasa, Takeshi

2018-04-01

Cell culture platform processes are generally employed to shorten the duration of new product development. A fed-batch process with continuous feeding is a conventional platform process for monoclonal antibody production using Chinese hamster ovary (CHO) cells. To establish a simplified platform process, the feeding method can be changed from continuous feed to bolus feed. However, this change induces a rapid increase of osmolality by the bolus addition of nutrients. The increased osmolality suppresses cell culture growth, and the final product concentration is decreased. In this study, osmotic resistant CHO host cells were developed to attain a high product concentration. To establish hyper osmotic resistant CHO host cells, CHO-S host cells were passaged long-term in a hyper osmotic basal medium. There were marked differences in cell growth of the original and established host cells under iso- (328 mOsm/kg) or hyper-osmolality (over 450 mOsm/kg) conditions. Cell growth of the original CHO host cells was markedly decreased by the induction of osmotic stress, whereas cell growth of the hyper osmotic resistant CHO host cells was not affected. The maximum viable cell concentration of hyper osmotic resistant CHO host cells was 132% of CHO-S host cells after the induction of osmotic stress. Moreover, the hyper osmotic resistant characteristic of established CHO host cells was maintained even after seven passages in iso-osmolality basal medium. The use of hyper osmotic resistance CHO host cells to create a monoclonal antibody production cell line might be a new approach to increase final antibody concentrations with a fed-batch process. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Molecular basis of Trypanosoma cruzi and Leishmania interaction with their host(s): exploitation of immune and defense mechanisms by the parasite leading to persistence and chronicity, features reminiscent of immune system evasion strategies in cancer diseases.

PubMed

Ouaissi, Ali; Ouaissi, Mehdi

2005-01-01

A number of features occurring during host-parasite interactions in Chagas disease caused by the protozoan parasite, Trypanosoma cruzi, and Leishmaniasis, caused by a group of kinetoplastid protozoan parasites are reminiscent of those observed in cancer diseases. In fact,although the cancer is not a single disease, and that T.cruzi and Leishmania are sophisticated eukaryotic parasites presenting a high level of genotypic variability the growth of the parasites in their host and that of cancer cells share at least one common feature, that is their mutual capacity for rapid cell division. Surprisingly, the parasitic diseases and cancers share some immune evasion strategies. Consideration of these immunological alterations must be added to the evaluation of the pathogenic processes. The molecular and functional characterization of virulence factors and the study of their effect on the arms of the immune system have greatly improved understanding of the regulation of immune effectors functions. The purpose of this review is to analyze some of the current data related to the regulatory components or processes originating from the parasite that control or interfere with host cell physiology. Attempts are also made to delineate some similarities between the immune evasion strategies that parasites and tumors employ. The elucidation of the mode of action of parasite virulence factors toward the host cell allow not only provide us with a more comprehensive view of the host-parasite relationships but may also represent a step forward in efforts aimed to identify new target molecules for therapeutic intervention.

Stress and death of cnidarian host cells play a role in cnidarian bleaching.

PubMed

Paxton, Camille W; Davy, Simon K; Weis, Virginia M

2013-08-01

Coral bleaching occurs when there is a breakdown of the symbiosis between cnidarian hosts and resident Symbiodinium spp. Multiple mechanisms for the bleaching process have been identified, including apoptosis and autophagy, and most previous work has focused on the Symbiodinium cell as the initiator of the bleaching cascade. In this work we show that it is possible for host cells to initiate apoptosis that can contribute to death of the Symbiodinium cell. First we found that colchicine, which results in apoptosis in other animals, causes cell death in the model anemone Aiptasia sp. but not in cultured Symbiodinium CCMP-830 cells or in cells freshly isolated from host Aiptasia (at least within the time frame of our study). In contrast, when symbiotic Aiptasia were incubated in colchicine, cell death in the resident Symbiodinium cells was observed, suggesting a host effect on symbiont mortality. Using live-cell confocal imaging of macerated symbiotic host cell isolates, we identified a pattern where the initiation of host cell death was followed by mortality of the resident Symbiodinium cells. This same pattern was observed in symbiotic host cells that were subjected to temperature stress. This research suggests that mortality of symbionts during temperature-induced bleaching can be initiated in part by host cell apoptosis.

The cnidarian origin of the proto-oncogenes NF-κB/STAT and WNT-like oncogenic pathway drives the ctenophores (Review)

PubMed Central

SINKOVICS, JOSEPH G.

2015-01-01

The cell survival pathways of the diploblastic early multicellular eukaryotic hosts contain and operate the molecular machinery resembling those of malignantly transformed individual cells of highly advanced multicellular hosts (including Homo). In the present review, the STAT/NF-κB pathway of the cnidarian Nematostella vectensis is compared with that of human tumors (malignant lymphomas, including Reed-Sternberg cells) pointing out similarities, including possible viral initiation in both cases. In the ctenophore genome and proteome, β-catenin gains intranuclear advantages due to a physiologically weak destructive complex in the cytoplasm, and lack of natural inhibitors (the Dickkopfs). Thus, a scenario similar to what tumor cells initiate and achieve is presented through several constitutive loss-of-function type mutations in the destructive complex and in the elimination of inhibitors. Vice versa, malignantly transformed individual cells of advanced multicellular hosts assume pheno-genotypic resemblance to cells of unicellular or early multicellular hosts, and presumably to their ancient predecessors, by returning to the semblance of immortality and to the resumption of the state of high degree of resistance to physicochemical insults. Human leukemogenic and oncogenic pathways are presented for comparisons. The supreme bioengineers RNA/DNA complex encoded both the malignantly transformed immortal cell and the human cerebral cortex. The former generates molecules for the immortality of cellular life in the Universe. The latter invents the inhibitors of the process in order to gain control over it. PMID:26239915

The cnidarian origin of the proto-oncogenes NF-κB/STAT and WNT-like oncogenic pathway drives the ctenophores (Review).

PubMed

Sinkovics, Joseph G

2015-10-01

The cell survival pathways of the diploblastic early multicellular eukaryotic hosts contain and operate the molecular machinery resembling those of malignantly transformed individual cells of highly advanced multicellular hosts (including Homo). In the present review, the STAT/NF-κB pathway of the cnidarian Nematostella vectensis is compared with that of human tumors (malignant lymphomas, including Reed-Sternberg cells) pointing out similarities, including possible viral initiation in both cases. In the ctenophore genome and proteome, β-catenin gains intranuclear advantages due to a physiologically weak destructive complex in the cytoplasm, and lack of natural inhibitors (the dickkopfs). Thus, a scenario similar to what tumor cells initiate and achieve is presented through several constitutive loss-of-function type mutations in the destructive complex and in the elimination of inhibitors. Vice versa, malignantly transformed individual cells of advanced multicellular hosts assume pheno-genotypic resemblance to cells of unicellular or early multicellular hosts, and presumably to their ancient predecessors, by returning to the semblance of immortality and to the resumption of the state of high degree of resistance to physicochemical insults. Human leukemogenic and oncogenic pathways are presented for comparisons. The supreme bioengineers RNA/DNA complex encoded both the malignantly transformed immortal cell and the human cerebral cortex. The former generates molecules for the immortality of cellular life in the Universe. The latter invents the inhibitors of the process in order to gain control over it.

Nanotechnology as an adjunct tool for transplanting engineered cells and tissues.

PubMed

Borlongan, Cesar V; Masuda, Tadashi; Walker, Tiffany A; Maki, Mina; Hara, Koichi; Yasuhara, Takao; Matsukawa, Noriyuki; Emerich, Dwaine F

2007-11-01

Laboratory and clinical studies have provided evidence of feasibility, safety and efficacy of cell transplantation to treat a wide variety of diseases characterized by tissue and cell dysfunction ranging from diabetes to spinal cord injury. However, major hurdles remain and limit pursuing large clinical trials, including the availability of a universal cell source that can be differentiated into specific cellular phenotypes, methods to protect the transplanted allogeneic or xenogeneic cells from rejection by the host immune system, techniques to enhance cellular integration of the transplant within the host tissue, strategies for in vivo detection and monitoring of the cellular implants, and new techniques to deliver genes to cells without eliciting a host immune response. Finding ways to circumvent these obstacles will benefit considerably from being able to understand, visualize, and control cellular interactions at a sub-micron level. Cutting-edge discoveries in the multidisciplinary field of nanotechnology have provided us a platform to manipulate materials, tissues, cells, and DNA at the level of and within the individual cell. Clearly, the scientific innovations achieved with nanotechnology are a welcome strategy for enhancing the generally encouraging results already achieved in cell transplantation. This review article discusses recent progress in the field of nanotechnology as a tool for tissue engineering, gene therapy, cell immunoisolation, and cell imaging, highlighting its direct applications in cell transplantation therapy.

The Iron-Dependent Regulator Fur Controls Pheromone Signaling Systems and Luminescence in the Squid Symbiont Vibrio fischeri ES114

PubMed Central

Septer, Alecia N.; Lyell, Noreen L.

2013-01-01

Bacteria often use pheromones to coordinate group behaviors in specific environments. While high cell density is required for pheromones to achieve stimulatory levels, environmental cues can also influence pheromone accumulation and signaling. For the squid symbiont Vibrio fischeri ES114, bioluminescence requires pheromone-mediated regulation, and this signaling is induced in the host to a greater extent than in culture, even at an equivalent cell density. Our goal is to better understand this environment-specific control over pheromone signaling and bioluminescence. Previous work with V. fischeri MJ1 showed that iron limitation induces luminescence, and we recently found that ES114 encounters a low-iron environment in its host. Here we show that ES114 induces luminescence at lower cell density and achieves brighter luminescence in low-iron media. This iron-dependent effect on luminescence required ferric uptake regulator (Fur), which we propose influences two pheromone signaling master regulators, LitR and LuxR. Genetic and bioinformatic analyses suggested that under low-iron conditions, Fur-mediated repression of litR is relieved, enabling more LitR to perform its established role as an activator of luxR. Interestingly, Fur may similarly control the LitR homolog SmcR of Vibrio vulnificus. These results reveal an intriguing regulatory link between low-iron conditions, which are often encountered in host tissues, and pheromone-dependent master regulators. PMID:23315731

Dramatic transcriptional changes in an intracellular parasite enable host switching between plant and insect.

PubMed

Oshima, Kenro; Ishii, Yoshiko; Kakizawa, Shigeyuki; Sugawara, Kyoko; Neriya, Yutaro; Himeno, Misako; Minato, Nami; Miura, Chihiro; Shiraishi, Takuya; Yamaji, Yasuyuki; Namba, Shigetou

2011-01-01

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the "host switching" between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to "host switching" between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of "host switching" mechanism may contribute to the development of novel pest controls.

Evaluation of blood T-lymphocyte subpopulations involved in host cellular immunity in dogs with mammary cancer.

PubMed

Karayannopoulou, Maria; Anagnostou, Tilemachos; Margariti, Apostolia; Kostakis, Charalampos; Kritsepi-Konstantinou, Maria; Psalla, Dimitra; Savvas, Ioannis

2017-04-01

Cancer-bearing patients are often immunosuppressed. In dogs with mammary or other cancers, various alterations in blood cell populations involved in host cellular immunity have been reported; among these cell populations some T-lymphocyte subsets play an important role against cancer. The purpose of the present study was to investigate any alterations in circulating T-lymphocyte subpopulations involved in cellular immunity in bitches with mammary cancer, in comparison to age-matched healthy intact bitches. Twenty eight dogs with mammary cancer and 14 control dogs were included in this study. Twelve out of the 28 bitches had mammary cancer of clinical stage II and 16/28 of stage III. Histological examination revealed that 23/28 animals had carcinomas, 3/28 sarcomas and 2/28 carcinosarcomas. White blood cell, neutrophil and lymphocyte absolute numbers were measured by complete blood count. Furthermore, blood T-lymphocyte population (CD3 + ) and the subpopulations CD4 + , CD8 + and CD5 low+ were assessed by flow cytometry. White blood cell and neutrophil but not lymphocyte absolute numbers were higher (P=0.003 and P=0.001, respectively) in cancer patients than controls. Flow cytometric analysis revealed that the relative percentage of T-lymphocytes (CD3 + ) and of CD4 + , CD8 + subpopulations was lower (the CD4 + /CD8 + ratio was higher), whereas the percentage of CD5 low+ T-cells was higher, in dogs with cancer compared to controls; however, a statistically significant difference was found only in the case of CD8 + T-cells (P=0.014), whereas in the case of the CD4 + /CD8 + ratio the difference almost reached statistical significance (P=0.059). Based on these findings, it can be suggested that, although the absolute number of blood lymphocytes is unchanged, the relative percentages of T-lymphocyte subpopulations involved in host cell-mediated immunity are altered, but only cytotoxic CD8 + T-cells are significantly suppressed, in dogs with mammary cancer of clinical stage II or III compared to age-matched healthy controls. Copyright © 2017 Elsevier B.V. All rights reserved.

Reduced-intensity conditioning for the treatment of malignant and life-threatening non-malignant disorders.

PubMed

Slavin, Shimon; Aker, Mehmet; Shapira, Michael Y; Resnick, Igor; Bitan, Menachem; Or, Reuven

2003-01-01

Allogeneic bone marrow or blood stem cell transplantation (BMT) represents an important therapeutic tool for the treatment of an otherwise incurable broad spectrum of malignant and non-malignant diseases. Until recently, BMT was used primarily to replace a malignant, genetically abnormal or deficient immunohematopoietic compartment and therefore, highly toxic myeloablative regimens were considered mandatory for more effective eradication of all undesirable host-derived hematopoietic cells, including stem cells and their progeny. Our preclinical and ongoing clinical studies indicated that much more effective eradication of host immunohematopoietic system cells can be mediated by donor lymphocytes in the process of adoptive allogeneic cell therapy following BMT. Thus, eradication of all malignant cells, especially in patients with CML and, to a lesser extent, in patients with other hematologic malignancies can be accomplished despite complete resistance of puch tumor cells to maximally tolerated doses of chemoradiotherapy. Our cumulative experience suggested that graft-versus-malignancy effects might be used as a tool for eradication of otherwise resistant tumor cells of host origin. We speculated that the therapeutic benefit of BMT may be improved by using safer conditioning for engraftment of donor stem cells induce host-versus-graft unresponsiveness to enable engraftment of donor lymphocytes for subsequent induction of graft-versus-malignancy effects, or even graft-versus-autoimmunity and graft-versus-genetically abnormal cells. In other words, focusing on more selective and smarter rather than stronger modalities. Effective BMT procedures may be accomplished without lethal conditioning of the host, using a new, well-tolerated and user-friendly non-myeloablative regimen, thus eliminating or minimizing immediate and late procedure-related toxicity and mortality. It appears that initial induction of graft tolerance, mediated by engraftment of donor stem cells, leads to durable engraftment of immunocompetent donor lymphocytes, which may be necessary for induction of effective biologic warfare against host-type immunohematopoietic cells. Consequently, stem-cell therapy following induction of transplantation tolerance by selective elimination of alloreactive donor lymphocytes may represent the treatment of choice for a wide range of otherwise incurable diseases, including cancer (hematologic malignancies and certain metastatic solid tumors), genetic disorders (hemoglobinopathies and enzyme deficiency disorders), diseases caused by self-reactive lymphocytes (autoimmune diseases such as multiple sclerosis, rheumatoid arthritis) to mention just a few. Using reduced intensity conditioning, non-myeloablative stem cell transplantation (NST) can be accomplished with no major procedure-related toxicity or mortality. Thus, NST offers the feasibility of safe stem cell transplantation and cell-mediated procedures for a large and constantly growing spectrum of clinical indications for all patients in need without lower or upper age limit. Future strategies currently under investigation include developing new approaches for control of alloreactivity of host-versus-graft and graft-versus host reactivity reactions and developing better approaches for maximizing the capacity of donor lymphocytes to eliminate cancer cells more selectively, while avoiding or minimizing GVHD for safer and more effective treatment of patients in need of BMT.

The Control of Auxin Transport in Parasitic and Symbiotic Root–Microbe Interactions

PubMed Central

Ng, Jason Liang Pin; Perrine-Walker, Francine; Wasson, Anton P.; Mathesius, Ulrike

2015-01-01

Most field-grown plants are surrounded by microbes, especially from the soil. Some of these, including bacteria, fungi and nematodes, specifically manipulate the growth and development of their plant hosts, primarily for the formation of structures housing the microbes in roots. These developmental processes require the correct localization of the phytohormone auxin, which is involved in the control of cell division, cell enlargement, organ development and defense, and is thus a likely target for microbes that infect and invade plants. Some microbes have the ability to directly synthesize auxin. Others produce specific signals that indirectly alter the accumulation of auxin in the plant by altering auxin transport. This review highlights root–microbe interactions in which auxin transport is known to be targeted by symbionts and parasites to manipulate the development of their host root system. We include case studies for parasitic root–nematode interactions, mycorrhizal symbioses as well as nitrogen fixing symbioses in actinorhizal and legume hosts. The mechanisms to achieve auxin transport control that have been studied in model organisms include the induction of plant flavonoids that indirectly alter auxin transport and the direct targeting of auxin transporters by nematode effectors. In most cases, detailed mechanisms of auxin transport control remain unknown. PMID:27135343

Alcohol-associated intestinal dysbiosis impairs pulmonary host defense against Klebsiella pneumoniae.

PubMed

Samuelson, Derrick R; Shellito, Judd E; Maffei, Vincent J; Tague, Eric D; Campagna, Shawn R; Blanchard, Eugene E; Luo, Meng; Taylor, Christopher M; Ronis, Martin J J; Molina, Patricia E; Welsh, David A

2017-06-01

Chronic alcohol consumption perturbs the normal intestinal microbial communities (dysbiosis). To investigate the relationship between alcohol-mediated dysbiosis and pulmonary host defense we developed a fecal adoptive transfer model, which allows us to investigate the impact of alcohol-induced gut dysbiosis on host immune response to an infectious challenge at a distal organ, independent of prevailing alcohol use. Male C57BL/6 mice were treated with a cocktail of antibiotics (ampicillin, gentamicin, neomycin, vancomycin, and metronidazole) via daily gavage for two weeks. A separate group of animals was fed a chronic alcohol (or isocaloric dextrose pair-fed controls) liquid diet for 10 days. Microbiota-depleted mice were recolonized with intestinal microbiota from alcohol-fed or pair-fed (control) animals. Following recolonization groups of mice were sacrificed prior to and 48 hrs. post respiratory infection with Klebsiella pneumoniae. Klebsiella lung burden, lung immunology and inflammation, as well as intestinal immunology, inflammation, and barrier damage were examined. Results showed that alcohol-associated susceptibility to K. pneumoniae is, in part, mediated by gut dysbiosis, as alcohol-naïve animals recolonized with a microbiota isolated from alcohol-fed mice had an increased respiratory burden of K. pneumoniae compared to mice recolonized with a control microbiota. The increased susceptibility in alcohol-dysbiosis recolonized animals was associated with an increase in pulmonary inflammatory cytokines, and a decrease in the number of CD4+ and CD8+ T-cells in the lung following Klebsiella infection but an increase in T-cell counts in the intestinal tract following Klebsiella infection, suggesting intestinal T-cell sequestration as a factor in impaired lung host defense. Mice recolonized with an alcohol-dysbiotic microbiota also had increased intestinal damage as measured by increased levels of serum intestinal fatty acid binding protein. Collectively, these results suggest that alterations in the intestinal immune response as a consequence of alcohol-induced dysbiosis contribute to increased host susceptibility to Klebsiella pneumonia.

Alcohol-associated intestinal dysbiosis impairs pulmonary host defense against Klebsiella pneumoniae

PubMed Central

Campagna, Shawn R.; Blanchard, Eugene E.; Ronis, Martin J. J.

2017-01-01

Chronic alcohol consumption perturbs the normal intestinal microbial communities (dysbiosis). To investigate the relationship between alcohol-mediated dysbiosis and pulmonary host defense we developed a fecal adoptive transfer model, which allows us to investigate the impact of alcohol-induced gut dysbiosis on host immune response to an infectious challenge at a distal organ, independent of prevailing alcohol use. Male C57BL/6 mice were treated with a cocktail of antibiotics (ampicillin, gentamicin, neomycin, vancomycin, and metronidazole) via daily gavage for two weeks. A separate group of animals was fed a chronic alcohol (or isocaloric dextrose pair-fed controls) liquid diet for 10 days. Microbiota-depleted mice were recolonized with intestinal microbiota from alcohol-fed or pair-fed (control) animals. Following recolonization groups of mice were sacrificed prior to and 48 hrs. post respiratory infection with Klebsiella pneumoniae. Klebsiella lung burden, lung immunology and inflammation, as well as intestinal immunology, inflammation, and barrier damage were examined. Results showed that alcohol-associated susceptibility to K. pneumoniae is, in part, mediated by gut dysbiosis, as alcohol-naïve animals recolonized with a microbiota isolated from alcohol-fed mice had an increased respiratory burden of K. pneumoniae compared to mice recolonized with a control microbiota. The increased susceptibility in alcohol-dysbiosis recolonized animals was associated with an increase in pulmonary inflammatory cytokines, and a decrease in the number of CD4+ and CD8+ T-cells in the lung following Klebsiella infection but an increase in T-cell counts in the intestinal tract following Klebsiella infection, suggesting intestinal T-cell sequestration as a factor in impaired lung host defense. Mice recolonized with an alcohol-dysbiotic microbiota also had increased intestinal damage as measured by increased levels of serum intestinal fatty acid binding protein. Collectively, these results suggest that alterations in the intestinal immune response as a consequence of alcohol-induced dysbiosis contribute to increased host susceptibility to Klebsiella pneumonia. PMID:28604843

Radiation-induced equilibrium is a balance between tumor cell proliferation and T cell-mediated killing

PubMed Central

Liang, Hua; Deng, Liufu; Chmura, Steven; Burnette, Byron; Liadis, Nicole; Darga, Thomas; Beckett, Michael A.; Lingen, Mark W.; Witt, MaryEllyn; Weichselbaum, Ralph R.; Fu, Yang-Xin

2013-01-01

Local failures following radiation therapy are multifactorial and the contributions of the tumor and the host are complex. Current models of tumor equilibrium suggest that a balance exists between cell birth and cell death due to insufficient angiogenesis, immune effects, or intrinsic cellular factors. We investigated whether host immune responses contribute to radiation induced tumor equilibrium in animal models. We report an essential role for immune cells and their cytokines in suppressing tumor cell regrowth in two experimental animal model systems. Depletion of T cells or neutralization of interferon-gamma reversed radiation-induced equilibrium leading to tumor regrowth. We also demonstrate that PD-L1 blockade augments T cell responses leading to rejection of tumors in radiation induced equilibrium. We identify an active interplay between tumor cells and immune cells that occurs in radiation-induced tumor equilibrium and suggest a potential role for disruption of the PD-L1/PD-1 axis in increasing local tumor control. PMID:23630355

Plant Virus–Insect Vector Interactions: Current and Potential Future Research Directions

PubMed Central

Dietzgen, Ralf G.; Mann, Krin S.; Johnson, Karyn N.

2016-01-01

Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Plant viruses can interact with their insect host in a variety of ways including both non-persistent and circulative transmission; in some cases, the latter involves virus replication in cells of the insect host. Replicating viruses can also elicit both innate and specific defense responses in the insect host. A consistent feature is that the interaction of the virus with its insect host/vector requires specific molecular interactions between virus and host, commonly via proteins. Understanding the interactions between plant viruses and their insect host can underpin approaches to protect plants from infection by interfering with virus uptake and transmission. Here, we provide a perspective focused on identifying novel approaches and research directions to facilitate control of plant viruses by better understanding and targeting virus–insect molecular interactions. We also draw parallels with molecular interactions in insect vectors of animal viruses, and consider technical advances for their control that may be more broadly applicable to plant virus vectors. PMID:27834855

Plant Virus-Insect Vector Interactions: Current and Potential Future Research Directions.

PubMed

Dietzgen, Ralf G; Mann, Krin S; Johnson, Karyn N

2016-11-09

Acquisition and transmission by an insect vector is central to the infection cycle of the majority of plant pathogenic viruses. Plant viruses can interact with their insect host in a variety of ways including both non-persistent and circulative transmission; in some cases, the latter involves virus replication in cells of the insect host. Replicating viruses can also elicit both innate and specific defense responses in the insect host. A consistent feature is that the interaction of the virus with its insect host/vector requires specific molecular interactions between virus and host, commonly via proteins. Understanding the interactions between plant viruses and their insect host can underpin approaches to protect plants from infection by interfering with virus uptake and transmission. Here, we provide a perspective focused on identifying novel approaches and research directions to facilitate control of plant viruses by better understanding and targeting virus-insect molecular interactions. We also draw parallels with molecular interactions in insect vectors of animal viruses, and consider technical advances for their control that may be more broadly applicable to plant virus vectors.

The Battle of RNA Synthesis: Virus versus Host.

PubMed

Harwig, Alex; Landick, Robert; Berkhout, Ben

2017-10-21

Transcription control is the foundation of gene regulation. Whereas a cell is fully equipped for this task, viruses often depend on the host to supply tools for their transcription program. Over the course of evolution and adaptation, viruses have found diverse ways to optimally exploit cellular host processes such as transcription to their own benefit. Just as cells are increasingly understood to employ nascent RNAs in transcription regulation, recent discoveries are revealing how viruses use nascent RNAs to benefit their own gene expression. In this review, we first outline the two different transcription programs used by viruses, i.e., transcription (DNA-dependent) and RNA-dependent RNA synthesis. Subsequently, we use the distinct stages (initiation, elongation, termination) to describe the latest insights into nascent RNA-mediated regulation in the context of each relevant stage.

Intestinal helminths regulate lethal acute graft-versus-host disease and preserve the graft-versus-tumor effect in mice.

PubMed

Li, Yue; Chen, Hung-Lin; Bannick, Nadine; Henry, Michael; Holm, Adrian N; Metwali, Ahmed; Urban, Joseph F; Rothman, Paul B; Weiner, George J; Blazar, Bruce R; Elliott, David E; Ince, M Nedim

2015-02-01

Donor T lymphocyte transfer with hematopoietic stem cells suppresses residual tumor growth (graft-versus-tumor [GVT]) in cancer patients undergoing bone marrow transplantation (BMT). However, donor T cell reactivity to host organs causes severe and potentially lethal inflammation called graft-versus-host disease (GVHD). High-dose steroids or other immunosuppressive drugs are used to treat GVHD that have limited ability to control the inflammation while incurring long-term toxicity. Novel strategies are needed to modulate GVHD, preserve GVT, and improve the outcome of BMT. Regulatory T cells (Tregs) control alloantigen-sensitized inflammation of GVHD, sustain GVT, and prevent mortality in BMT. Helminths colonizing the alimentary tract dramatically increase the Treg activity, thereby modulating intestinal or systemic inflammatory responses. These observations led us to hypothesize that helminths can regulate GVHD and maintain GVT in mice. Acute GVHD was induced in helminth (Heligmosomoides polygyrus)-infected or uninfected BALB/c recipients of C57BL/6 donor grafts. Helminth infection suppressed donor T cell inflammatory cytokine generation and reduced GVHD-related mortality, but maintained GVT. H. polygyrus colonization promoted the survival of TGF-β-generating recipient Tregs after a conditioning regimen with total body irradiation and led to a TGF-β-dependent in vivo expansion/maturation of donor Tregs after BMT. Helminths did not control GVHD when T cells unresponsive to TGF-β-mediated immune regulation were used as donor T lymphocytes. These results suggest that helminths suppress acute GVHD using Tregs and TGF-β-dependent pathways in mice. Helminthic regulation of GVHD and GVT through intestinal immune conditioning may improve the outcome of BMT. Copyright © 2015 by The American Association of Immunologists, Inc.

Memory T cells: A helpful guard for allogeneic hematopoietic stem cell transplantation without causing graft-versus-host disease.

PubMed

Huang, Wei; Chao, Nelson J

2017-12-01

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (AHSCT) and the major cause of nonrelapse morbidity and mortality of AHSCT. In AHSCT, donor T cells facilitate hematopoietic stem cell (HSC) engraftment, contribute to anti-infection immunity, and mediate graft-versus-leukemia (GVL) responses. However, activated alloreactive T cells also attack recipient cells in vital organs, leading to GVHD. Different T-cell subsets, including naïve T (T N ) cells, memory T (T M ) cells, and regulatory T (T reg ) cells mediate different forms of GVHD and GVL; T N cells mediate severe GVHD, whereas T M cells do not cause GVHD, but preserve T-cell function including GVL. In addition, metabolic reprogramming controls T-cell differentiation and activation in these disease states. This minireview focuses on the role and the related mechanisms of T M cells in AHSCT, and the potential manipulation of T cells in AHSCT. Copyright © 2017 King Faisal Specialist Hospital & Research Centre. Published by Elsevier B.V. All rights reserved.

At the Edge of Translation – Materials to Program Cells for Directed Differentiation

PubMed Central

Arany, Praveen R; Mooney, David J

2010-01-01

The rapid advancement in basic biology knowledge, especially in the stem cell field, has created new opportunities to develop biomaterials capable of orchestrating the behavior of transplanted and host cells. Based on our current understanding of cellular differentiation, a conceptual framework for the use of materials to program cells in situ is presented, namely a domino versus a switchboard model, to highlight the use of single versus multiple cues in a controlled manner to modulate biological processes. Further, specific design principles of material systems to present soluble and insoluble cues that are capable of recruiting, programming and deploying host cells for various applications are presented. The evolution of biomaterials from simple inert substances used to fill defects, to the recent development of sophisticated material systems capable of programming cells in situ is providing a platform to translate our understanding of basic biological mechanisms to clinical care. PMID:20860763

Basics of PD-1 in self-tolerance, infection, and cancer immunity.

PubMed

Chikuma, Shunsuke

2016-06-01

Successful cancer treatment requires understanding host immune response against tumor cells. PD-1 belongs to the CD28 superfamily of receptors that work as "checkpoints" of immune activation. PD-1 maintains immune self-tolerance to prevent autoimmunity and controls T-cell reaction during infection to prevent excessive tissue damage. Tumor cells that arise from normal tissue acquire mutations that can be targeted by lymphocytes. Accumulating lines of evidence suggest that tumor cells evade host immune attack by expressing physiological PD-1 ligands and stimulating PD-1 on the lymphocytes. Based on this idea, researchers have successfully demonstrated that systemic administration of monoclonal antibodies that inhibit the binding of PD-1 to the ligands reactivated T cells and augmented the anti-cancer immune response. In this review, I summarize the basics of T-cell biology and its regulation by PD-1 and discuss the current understanding and questions about this multifaceted molecule.

Organelle targeting during bacterial infection: insights from Listeria.

PubMed

Lebreton, Alice; Stavru, Fabrizia; Cossart, Pascale

2015-06-01

Listeria monocytogenes, a facultative intracellular bacterium responsible for severe foodborne infections, is now recognized as a multifaceted model in infection biology. Comprehensive studies of the molecular and cellular basis of the infection have unraveled how the bacterium crosses the intestinal and feto-placental barriers, invades several cell types in which it multiplies and moves, and spreads from cell to cell. Interestingly, although Listeria does not actively invade host cell organelles, it can interfere with their function. We discuss the effect of Listeria on the endoplasmic reticulum (ER) and the mechanisms leading to the fragmentation of the mitochondrial network and its consequences, and review the strategies used by Listeria to subvert nuclear functions, more precisely to control host gene expression at the chromatin level. Copyright © 2015 Elsevier Ltd. All rights reserved.

In Vivo Imaging of Transgenic Gene Expression in Individual Retinal Progenitors in Chimeric Zebrafish Embryos to Study Cell Nonautonomous Influences.

PubMed

Dudczig, Stefanie; Currie, Peter D; Poggi, Lucia; Jusuf, Patricia R

2017-03-22

The genetic and technical strengths have made the zebrafish vertebrate a key model organism in which the consequences of gene manipulations can be traced in vivo throughout the rapid developmental period. Multiple processes can be studied including cell proliferation, gene expression, cell migration and morphogenesis. Importantly, the generation of chimeras through transplantations can be easily performed, allowing mosaic labeling and tracking of individual cells under the influence of the host environment. For example, by combining functional gene manipulations of the host embryo (e.g., through morpholino microinjection) and live imaging, the effects of extrinsic, cell nonautonomous signals (provided by the genetically modified environment) on individual transplanted donor cells can be assessed. Here we demonstrate how this approach is used to compare the onset of fluorescent transgene expression as a proxy for the timing of cell fate determination in different genetic host environments. In this article, we provide the protocol for microinjecting zebrafish embryos to mark donor cells and to cause gene knockdown in host embryos, a description of the transplantation technique used to generate chimeric embryos, and the protocol for preparing and running in vivo time-lapse confocal imaging of multiple embryos. In particular, performing multiposition imaging is crucial when comparing timing of events such as the onset of gene expression. This requires data collection from multiple control and experimental embryos processed simultaneously. Such an approach can easily be extended for studies of extrinsic influences in any organ or tissue of choice accessible to live imaging, provided that transplantations can be targeted easily according to established embryonic fate maps.

Transplantation of cells from eye-like structures differentiated from embryonic stem cells in vitro and in vivo regeneration of retinal ganglion-like cells.

PubMed

Aoki, Hitomi; Hara, Akira; Niwa, Masayuki; Motohashi, Tsutomu; Suzuki, Takashi; Kunisada, Takahiro

2008-02-01

An embryonic stem (ES) cell-derived eye-like structure, made up of neural retinal lineage cells, retinal pigment epithelial (RPE) cells, and lens cells was constructed in our laboratory. We have shown that cells from these eye-like structures can be integrated into the developing optic vesicle of chicks. The purpose of this study was to determine whether the cells from these eye-like structures can differentiate into retinal ganglion cells (RGCs) when transplanted into the vitreous of an injured adult mouse retina. ES cells were induced to differentiate into eye-like structures in vitro for 6 or 11 days. Recipient mouse eyes were injected with NMDA to injure the RGCs prior to the transplantation. Sham-treated eyes received the same amount of carrier vehicle. Cells were extracted from the eye-like structures and transplanted into the vitreous of damaged and control eyes. The host eyes were analyzed both qualitatively and quantitatively by immunohistochemistry 10 days or 8 weeks after transplantation. Cells from the ES cell-derived eye-like structures were integrated into the RGC layer, and differentiated into neurons when transplanted into control (non-NMDA-treated) adult eyes. However, they rarely expressed RGC markers. When they were transplanted into NMDA-treated eyes, the cells spread on the surface of the retina and covered a relatively large area of the host RGC layer that had been injured by the NMDA. The cells from the ES cell-derived eye cells frequently differentiated into cells expressing RGC-specific markers, and formed a new RGC layer. In addition, a small number of these ES cell-derived cells were observed to extend axon-like processes toward the optic disc of the host. However, visually evoked responses could not be recorded from the visual cortex. These findings suggest that ES cell-derived eye-like structures contain cells that can differentiate into RG-like cells and regenerate a new RGC layer. These cells also appeared to be integrated into the retina and extend axon-like processes toward the optic nerve head.

Bifidobacterium breve UCC2003 surface exopolysaccharide production is a beneficial trait mediating commensal-host interaction through immune modulation and pathogen protection.

PubMed

Fanning, Saranna; Hall, Lindsay J; van Sinderen, Douwe

2012-01-01

Bifidobacteria constitute a substantial proportion of the human gut microbiota. There are currently many bifidobacterial strains with claimed probiotic attributes. The mechanism through which these strains reside within their host and exert benefits to the host is far from fully understood. We have shown in the case of Bifidobacterium breve UCC2003 that a cell surface exopolysaccharide (EPS) plays a role in in vivo persistence. Biosynthesis of two possible EPSs is controlled by a bidirectional gene cluster which guides alternate EPS synthesis by means of a reorienting promoter. The presence of EPS impacts on host immune response: the wild type, EPS-positive B. breve UCC2003 efficiently evades the adaptive B-cell host response, while its isogenic, EPS-deficient equivalent elicits a strong adaptive immune response. Functionally, EPS positive strains were more resilient to presence of acid and bile and were responsible for reduced colonization levels of Citrobacter rodentium, a gut pathogen. In conclusion, we have found that EPS is important in host interactions and pathogen protection, the latter indicative of a probiotic ability for the EPS of B. breve UCC2003.

Perspectives on Regulatory T Cell Therapies

PubMed Central

Probst-Kepper, Michael; Kröger, Andrea; Garritsen, Henk S.P.; Buer, Jan

2009-01-01

Summary Adoptive transfer in animal models clearly indicate an essential role of CD4+ CD25+ FOXP3+ regulatory T (Treg) cells in prevention and treatment of autoimmune and graft-versus-host disease. Thus, Treg cell therapies and development of drugs that specifically enhance Treg cell function and development represent promising tools to establish dominant tolerance. So far, lack of specific markers to differentiate human Treg cells from activated CD4+ CD25+ effector T cells, which also express FOXP3 at different levels, hampered such an approach. Recent identification of the orphan receptor glycoprotein-A repetitions predominant (GARP or LRRC32) as Treg cell-specific key molecule that dominantly controls FOXP3 via a positive feedback loop opens up new perspectives for molecular and cellular therapies. This brief review focuses on the role of GARP as a safeguard of a complex regulatory network of human Treg cells and its implications for regulatory T cell therapies in autoimmunity and graft-versus-host disease. PMID:21076548

Perspectives on Regulatory T Cell Therapies.

PubMed

Probst-Kepper, Michael; Kröger, Andrea; Garritsen, Henk S P; Buer, Jan

2009-01-01

Adoptive transfer in animal models clearly indicate an essential role of CD4+ CD25+ FOXP3+ regulatory T (T(reg)) cells in prevention and treatment of autoimmune and graft-versus-host disease. Thus, T(reg) cell therapies and development of drugs that specifically enhance T(reg) cell function and development represent promising tools to establish dominant tolerance. So far, lack of specific markers to differentiate human T(reg) cells from activated CD4+ CD25+ effector T cells, which also express FOXP3 at different levels, hampered such an approach. Recent identification of the orphan receptor glycoprotein-A repetitions predominant (GARP or LRRC32) as T(reg) cell-specific key molecule that dominantly controls FOXP3 via a positive feedback loop opens up new perspectives for molecular and cellular therapies. This brief review focuses on the role of GARP as a safeguard of a complex regulatory network of human T(reg) cells and its implications for regulatory T cell therapies in autoimmunity and graft-versus-host disease.

Polysaccharides from the Chinese medicinal herb Achyranthes bidentata enhance anti-malarial immunity during Plasmodium yoelii 17XL infection in mice.

PubMed

Zhu, Xiaotong; Pan, Yanyan; Zheng, Li; Cui, Liwang; Cao, Yaming

2012-02-20

Clinical immunity to malaria in human populations is developed after repeated exposure to malaria. Regulation and balance of host immune responses may lead to optimal immunity against malaria parasite infection. Polysaccharides (ABPS) derived from the Chinese herb ox knee Achyranthes bidentata possess immuno-modulatory functions. The aim of this study is to use the rodent malaria model Plasmodium yoelii 17XL (P. y17XL) to examine whether pretreatment with ABPS will modulate host immunity against malaria infection and improve the outcome of the disease. To determine whether ABPS could modulate immunity against malaria, mice were pretreated with ABPS prior to blood-stage infection by P. y17XL. Host survival and parasitaemia were monitored daily. The effect of pretreatment on host immune responses was studied through the quantitation of cytokines, dendritic cell populations, and natural regulatory T cells (Treg). Pretreatment with ABPS prior to infection significantly extended the survival time of mice after P. y17XL infection. At three and five days post-infection, ABPS pretreated mice developed stronger Th1 immune responses against malaria infection with the number of F4/80+CD36+ macrophages and levels of IFN-γ, TNF-α and nitric oxide being significantly higher than in the control group. More importantly, ABPS-treated mice developed more myeloid (CD11c+CD11b+) and plasmacytoid dendritic cells (CD11c+CD45R+/B220+) than control mice. ABPS pretreatment also resulted in modulated expression of MHC-II, CD86, and especially Toll-like receptor 9 by CD11c+ dendritic cells. In comparison, pretreatment with ABPS did not alter the number of natural Treg or the production of the anti-inflammatory cytokine IL-10. Pretreatment with the immuno-modulatory ABPS selectively enhanced Th1 immune responses to control the proliferation of malaria parasites, and prolonged the survival of mice during subsequent malaria infection.

Induction of viral, 7-methyl-guanosine cap-independent translation and oncolysis by mitogen-activated protein kinase-interacting kinase-mediated effects on the serine/arginine-rich protein kinase.

PubMed

Brown, Michael C; Bryant, Jeffrey D; Dobrikova, Elena Y; Shveygert, Mayya; Bradrick, Shelton S; Chandramohan, Vidyalakshmi; Bigner, Darell D; Gromeier, Matthias

2014-11-01

Protein synthesis, the most energy-consuming process in cells, responds to changing physiologic priorities, e.g., upon mitogen- or stress-induced adaptations signaled through the mitogen-activated protein kinases (MAPKs). The prevailing status of protein synthesis machinery is a viral pathogenesis factor, particularly for plus-strand RNA viruses, where immediate translation of incoming viral RNAs shapes host-virus interactions. In this study, we unraveled signaling pathways centered on the ERK1/2 and p38α MAPK-interacting kinases MNK1/2 and their role in controlling 7-methyl-guanosine (m(7)G) "cap"-independent translation at enterovirus type 1 internal ribosomal entry sites (IRESs). Activation of Raf-MEK-ERK1/2 signals induced viral IRES-mediated translation in a manner dependent on MNK1/2. This effect was not due to MNK's known functions as eukaryotic initiation factor (eIF) 4G binding partner or eIF4E(S209) kinase. Rather, MNK catalytic activity enabled viral IRES-mediated translation/host cell cytotoxicity through negative regulation of the Ser/Arg (SR)-rich protein kinase (SRPK). Our investigations suggest that SRPK activity is a major determinant of type 1 IRES competency, host cell cytotoxicity, and viral proliferation in infected cells. We are targeting unfettered enterovirus IRES activity in cancer with PVSRIPO, the type 1 live-attenuated poliovirus (PV) (Sabin) vaccine containing a human rhinovirus type 2 (HRV2) IRES. A phase I clinical trial of PVSRIPO with intratumoral inoculation in patients with recurrent glioblastoma (GBM) is showing early promise. Viral translation proficiency in infected GBM cells is a core requirement for the antineoplastic efficacy of PVSRIPO. Therefore, it is critically important to understand the mechanisms controlling viral cap-independent translation in infected host cells. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Genome-Wide RNAi Screen Identifies Broadly-Acting Host Factors That Inhibit Arbovirus Infection

PubMed Central

Yasunaga, Ari; Hanna, Sheri L.; Li, Jianqing; Cho, Hyelim; Rose, Patrick P.; Spiridigliozzi, Anna; Gold, Beth; Diamond, Michael S.; Cherry, Sara

2014-01-01

Vector-borne viruses are an important class of emerging and re-emerging pathogens; thus, an improved understanding of the cellular factors that modulate infection in their respective vertebrate and insect hosts may aid control efforts. In particular, cell-intrinsic antiviral pathways restrict vector-borne viruses including the type I interferon response in vertebrates and the RNA interference (RNAi) pathway in insects. However, it is likely that additional cell-intrinsic mechanisms exist to limit these viruses. Since insects rely on innate immune mechanisms to inhibit virus infections, we used Drosophila as a model insect to identify cellular factors that restrict West Nile virus (WNV), a flavivirus with a broad and expanding geographical host range. Our genome-wide RNAi screen identified 50 genes that inhibited WNV infection. Further screening revealed that 17 of these genes were antiviral against additional flaviviruses, and seven of these were antiviral against other vector-borne viruses, expanding our knowledge of invertebrate cell-intrinsic immunity. Investigation of two newly identified factors that restrict diverse viruses, dXPO1 and dRUVBL1, in the Tip60 complex, demonstrated they contributed to antiviral defense at the organismal level in adult flies, in mosquito cells, and in mammalian cells. These data suggest the existence of broadly acting and functionally conserved antiviral genes and pathways that restrict virus infections in evolutionarily divergent hosts. PMID:24550726

Different residues in the SARS-CoV spike protein determine cleavage and activation by the host cell protease TMPRSS2

PubMed Central

Reinke, Lennart Michel; Hartleib, Anika; Nehlmeier, Inga; Gierer, Stefanie; Hoffmann, Markus; Hofmann-Winkler, Heike; Winkler, Michael

2017-01-01

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) mediates viral entry into target cells. Cleavage and activation of SARS S by a host cell protease is essential for infectious viral entry and the responsible enzymes are potential targets for antiviral intervention. The type II transmembrane serine protease TMPRSS2 cleaves and activates SARS S in cell culture and potentially also in the infected host. Here, we investigated which determinants in SARS S control cleavage and activation by TMPRSS2. We found that SARS S residue R667, a previously identified trypsin cleavage site, is also required for S protein cleavage by TMPRSS2. The cleavage fragments produced by trypsin and TMPRSS2 differed in their decoration with N-glycans, suggesting that these proteases cleave different SARS S glycoforms. Although R667 was required for SARS S cleavage by TMPRSS2, this residue was dispensable for TMPRSS2-mediated S protein activation. Conversely, residue R797, previously reported to be required for SARS S activation by trypsin, was dispensable for S protein cleavage but required for S protein activation by TMPRSS2. Collectively, these results show that different residues in SARS S control cleavage and activation by TMPRSS2, suggesting that these processes are more complex than initially appreciated. PMID:28636671

Different residues in the SARS-CoV spike protein determine cleavage and activation by the host cell protease TMPRSS2.

PubMed

Reinke, Lennart Michel; Spiegel, Martin; Plegge, Teresa; Hartleib, Anika; Nehlmeier, Inga; Gierer, Stefanie; Hoffmann, Markus; Hofmann-Winkler, Heike; Winkler, Michael; Pöhlmann, Stefan

2017-01-01

The spike (S) protein of severe acute respiratory syndrome coronavirus (SARS-CoV) mediates viral entry into target cells. Cleavage and activation of SARS S by a host cell protease is essential for infectious viral entry and the responsible enzymes are potential targets for antiviral intervention. The type II transmembrane serine protease TMPRSS2 cleaves and activates SARS S in cell culture and potentially also in the infected host. Here, we investigated which determinants in SARS S control cleavage and activation by TMPRSS2. We found that SARS S residue R667, a previously identified trypsin cleavage site, is also required for S protein cleavage by TMPRSS2. The cleavage fragments produced by trypsin and TMPRSS2 differed in their decoration with N-glycans, suggesting that these proteases cleave different SARS S glycoforms. Although R667 was required for SARS S cleavage by TMPRSS2, this residue was dispensable for TMPRSS2-mediated S protein activation. Conversely, residue R797, previously reported to be required for SARS S activation by trypsin, was dispensable for S protein cleavage but required for S protein activation by TMPRSS2. Collectively, these results show that different residues in SARS S control cleavage and activation by TMPRSS2, suggesting that these processes are more complex than initially appreciated.

Heterologous expression of enterocin A, a bacteriocin from Enterococcus faecium, fused to a cellulose-binding domain in Escherichia coli results in a functional protein with inhibitory activity against Listeria.

PubMed

Klocke, Michael; Mundt, Kerstin; Idler, Frank; Jung, Sabrina; Backhausen, Jan E

2005-06-01

The genes for the bacteriocins enterocin A and B were isolated from Enterococcus faecium ATB 197a. Using the pET37b(+) vector, the enterocin genes were fused to an Escherichia coli specific export signal sequence, a cellulose-binding domain (CBD(cenA)) and a S-tag under the control of a T7lac promotor. The constructs were subsequently cloned into E. coli host cells. The expression of the recombinant enterocins had different effects on both the host cells and other Gram-positive bacteria. The expression of entA in Esc. coli led to the synthesis and secretion of functional active enterocin A fusion proteins, which were active against some Gram-positive indicator bacteria, but did not influence the viability of the host cells. In contrast, the expression of enterocin B fusion proteins led to a reduced viability of the host cells, indicating a misfolding of the protein or interference with the cellular metabolism of Esc. coli. Indicator strains of Gram-positive bacteria were not inhibited by purified enterocin B fusion proteins. However, recombinant enterocin B displayed inhibitory activity after the proteolytic cleavage of the fused peptides.

The Dialogue of the Host-Parasite Relationship: Leishmania spp. and Trypanosoma cruzi Infection

PubMed Central

de Morais, Carlos Gustavo Vieira; Castro Lima, Ana Karina; dos Santos, Rosiane Freire; Da-Silva, Silvia Amaral Gonçalves; Dutra, Patrícia Maria Lourenço

2015-01-01

The intracellular protozoa Leishmania spp. and Trypanosoma cruzi and the causative agents of Leishmaniasis and Chagas disease, respectively, belong to the Trypanosomatidae family. Together, these two neglected tropical diseases affect approximately 25 million people worldwide. Whether the host can control the infection or develops disease depends on the complex interaction between parasite and host. Parasite surface and secreted molecules are involved in triggering specific signaling pathways essential for parasite entry and intracellular survival. The recognition of the parasite antigens by host immune cells generates a specific immune response. Leishmania spp. and T. cruzi have a multifaceted repertoire of strategies to evade or subvert the immune system by interfering with a range of signal transduction pathways in host cells, which causes the inhibition of the protective response and contributes to their persistence in the host. The current therapeutic strategies in leishmaniasis and trypanosomiasis are very limited. Efficacy is variable, toxicity is high, and the emergence of resistance is increasingly common. In this review, we discuss the molecular basis of the host-parasite interaction of Leishmania and Trypanosoma cruzi infection and their mechanisms of subverting the immune response and how this knowledge can be used as a tool for the development of new drugs. PMID:26090399

A unified pathogenesis for kidney diseases, including genetic diseases and cancers, by the protein-homeostasis-system hypothesis.

PubMed

Lee, Kyung-Yil

2017-06-01

Every cell of an organism is separated and protected by a cell membrane. It is proposed that harmony between intercellular communication and the health of an organism is controlled by a system, designated the protein-homeostasis-system (PHS). Kidneys consist of a variety of types of renal cells, each with its own characteristic cell-receptor interactions and producing characteristic proteins. A functional union of these renal cells can be determined by various renal function tests, and harmonious intercellular communication is essential for the healthy state of the host. Injury to a kind of renal cells can impair renal function and induce an imbalance in total body health. Every acute or chronic renal disease has unknown etiologic substances that are responsible for renal cell injury at the molecular level. The immune/repair system of the host should control the etiologic substances acting against renal cells; if this system fails, the disease progresses to end stage renal disease. Each renal disease has its characteristic pathologic lesions where immune cells and immune proteins, such as immunoglobulins and complements, are infiltrated. These immune cells and immune proteins may control the etiologic substances involved in renal pathologic lesions. Also, genetic renal diseases and cancers may originate from a protein deficiency or malfunctioning protein under the PHS. A unified pathogenesis for renal diseases, including acute glomerulonephritis, idiopathic nephrotic syndrome, immunoglobulin A nephropathy, genetic renal diseases such as Alport syndrome, and malignancies such as Wilms tumor and renal cell carcinoma, is proposed using the PHS hypothesis.

Immune Cells Are Required for Cutaneous Ulceration in a Swine Model of Chancroid

PubMed Central

San Mateo, Lani R.; Toffer, Kristen L.; Orndorff, Paul E.; Kawula, Thomas H.

1999-01-01

Cutaneous lesions of the human sexually transmitted genital ulcer disease chancroid are characterized by the presence of intraepidermal pustules, keratinocyte cytopathology, and epidermal and dermal erosion. These lesions are replete with neutrophils, macrophages, and CD4+ T cells and contain very low numbers of cells of Haemophilus ducreyi, the bacterial agent of chancroid. We examined lesion formation by H. ducreyi in a pig model by using cyclophosphamide (CPA)-induced immune cell deficiency to distinguish between host and bacterial contributions to chancroid ulcer formation. Histologic presentation of H. ducreyi-induced lesions in CPA-treated pigs differed from ulcers that developed in immune-competent animals in that pustules did not form and surface epithelia remained intact. However, these lesions had significant suprabasal keratinocyte cytotoxicity. These results demonstrate that the host immune response was required for chancroid ulceration, while bacterial products were at least partially responsible for the keratinocyte cytopathology associated with chancroid lesions in the pig. The low numbers of H. ducreyi present in lesions in humans and immune-competent pigs have prevented localization of these organisms within skin. However, H. ducreyi organisms were readily visualized in lesion biopsies from infected CPA-treated pigs by immunoelectron microscopy. These bacteria were extracellular and associated with necrotic host cells in the epidermis and dermis. The relative abundance of H. ducreyi in inoculated CPA-treated pig skin suggests control of bacterial replication by host immune cells during natural human infection. PMID:10456960

Immune cells are required for cutaneous ulceration in a swine model of chancroid.

PubMed

San Mateo, L R; Toffer, K L; Orndorff, P E; Kawula, T H

1999-09-01

Cutaneous lesions of the human sexually transmitted genital ulcer disease chancroid are characterized by the presence of intraepidermal pustules, keratinocyte cytopathology, and epidermal and dermal erosion. These lesions are replete with neutrophils, macrophages, and CD4(+) T cells and contain very low numbers of cells of Haemophilus ducreyi, the bacterial agent of chancroid. We examined lesion formation by H. ducreyi in a pig model by using cyclophosphamide (CPA)-induced immune cell deficiency to distinguish between host and bacterial contributions to chancroid ulcer formation. Histologic presentation of H. ducreyi-induced lesions in CPA-treated pigs differed from ulcers that developed in immune-competent animals in that pustules did not form and surface epithelia remained intact. However, these lesions had significant suprabasal keratinocyte cytotoxicity. These results demonstrate that the host immune response was required for chancroid ulceration, while bacterial products were at least partially responsible for the keratinocyte cytopathology associated with chancroid lesions in the pig. The low numbers of H. ducreyi present in lesions in humans and immune-competent pigs have prevented localization of these organisms within skin. However, H. ducreyi organisms were readily visualized in lesion biopsies from infected CPA-treated pigs by immunoelectron microscopy. These bacteria were extracellular and associated with necrotic host cells in the epidermis and dermis. The relative abundance of H. ducreyi in inoculated CPA-treated pig skin suggests control of bacterial replication by host immune cells during natural human infection.

Keeping Control: The Role of Senescence and Development in Plant Pathogenesis and Defense

PubMed Central

Häffner, Eva; Konietzki, Sandra; Diederichsen, Elke

2015-01-01

Many plant pathogens show interactions with host development. Pathogens may modify plant development according to their nutritional demands. Conversely, plant development influences pathogen growth. Biotrophic pathogens often delay senescence to keep host cells alive, and resistance is achieved by senescence-like processes in the host. Necrotrophic pathogens promote senescence in the host, and preventing early senescence is a resistance strategy of plants. For hemibiotrophic pathogens both patterns may apply. Most signaling pathways are involved in both developmental and defense reactions. Increasing knowledge about the molecular components allows to distinguish signaling branches, cross-talk and regulatory nodes that may influence the outcome of an infection. In this review, recent reports on major molecular players and their role in senescence and in pathogen response are reviewed. Examples of pathosystems with strong developmental implications illustrate the molecular basis of selected control strategies. A study of gene expression in the interaction between the hemibiotrophic vascular pathogen Verticillium longisporum and its cruciferous hosts shows processes that are fine-tuned to counteract early senescence and to achieve resistance. The complexity of the processes involved reflects the complex genetic control of quantitative disease resistance, and understanding the relationship between disease, development and resistance will support resistance breeding. PMID:27135337

Chlamydia trachomatis Cellular Exit Alters Interactions with Host Dendritic Cells

PubMed Central

Sherrid, Ashley M.

2017-01-01

ABSTRACT The strategies utilized by pathogens to exit host cells are an area of pathogenesis which has received surprisingly little attention, considering the necessity of this step for infections to propagate. Even less is known about how exit through these pathways affects downstream host-pathogen interactions and the generation of an immune response. Chlamydia trachomatis exits host epithelial cells through two equally active mechanisms: lysis and extrusion. Studies have characterized the outcome of interactions between host innate immune cells, such as dendritic cells and macrophages, and free, extracellular Chlamydia bacteria, such as those resulting from lysis. Exit via extrusion generates a distinct, host-membrane-bound compartment of Chlamydia separate from the original infected cell. In this study, we assessed the effect of containment within extrusions upon the interaction between Chlamydia and host dendritic cells. Extrusion dramatically affected the outcome of Chlamydia-dendritic cell interactions for both the bacterium and the host cell. Dendritic cells rapidly underwent apoptosis in response to engulfment of an extrusion, while uptake of an equivalent dose of free Chlamydia had no such effect. Containment within an extrusion also prolonged bacterial survival within dendritic cells and altered the initial innate immune signaling by the dendritic cell. PMID:28223346

Genome-wide in vivo screen identifies novel host regulators of metastatic colonization.

PubMed

van der Weyden, Louise; Arends, Mark J; Campbell, Andrew D; Bald, Tobias; Wardle-Jones, Hannah; Griggs, Nicola; Velasco-Herrera, Martin Del Castillo; Tüting, Thomas; Sansom, Owen J; Karp, Natasha A; Clare, Simon; Gleeson, Diane; Ryder, Edward; Galli, Antonella; Tuck, Elizabeth; Cambridge, Emma L; Voet, Thierry; Macaulay, Iain C; Wong, Kim; Spiegel, Sarah; Speak, Anneliese O; Adams, David J

2017-01-12

Metastasis is the leading cause of death for cancer patients. This multi-stage process requires tumour cells to survive in the circulation, extravasate at distant sites, then proliferate; it involves contributions from both the tumour cell and tumour microenvironment ('host', which includes stromal cells and the immune system). Studies suggest the early steps of the metastatic process are relatively efficient, with the post-extravasation regulation of tumour growth ('colonization') being critical in determining metastatic outcome. Here we show the results of screening 810 mutant mouse lines using an in vivo assay to identify microenvironmental regulators of metastatic colonization. We identify 23 genes that, when disrupted in mouse, modify the ability of tumour cells to establish metastatic foci, with 19 of these genes not previously demonstrated to play a role in host control of metastasis. The largest reduction in pulmonary metastasis was observed in sphingosine-1-phosphate (S1P) transporter spinster homologue 2 (Spns2)-deficient mice. We demonstrate a novel outcome of S1P-mediated regulation of lymphocyte trafficking, whereby deletion of Spns2, either globally or in a lymphatic endothelial-specific manner, creates a circulating lymphopenia and a higher percentage of effector T cells and natural killer (NK) cells present in the lung. This allows for potent tumour cell killing, and an overall decreased metastatic burden.

Current-Controlled Electrical Point-Source Stimulation of Embryonic Stem Cells

PubMed Central

Chen, Michael Q.; Xie, Xiaoyan; Wilson, Kitchener D.; Sun, Ning; Wu, Joseph C.; Giovangrandi, Laurent; Kovacs, Gregory T. A.

2010-01-01

Stem cell therapy is emerging as a promising clinical approach for myocardial repair. However, the interactions between the graft and host, resulting in inconsistent levels of integration, remain largely unknown. In particular, the influence of electrical activity of the surrounding host tissue on graft differentiation and integration is poorly understood. In order to study this influence under controlled conditions, an in vitro system was developed. Electrical pacing of differentiating murine embryonic stem (ES) cells was performed at physiologically relevant levels through direct contact with microelectrodes, simulating the local activation resulting from contact with surrounding electroactive tissue. Cells stimulated with a charged balanced voltage-controlled current source for up to 4 days were analyzed for cardiac and ES cell gene expression using real-time PCR, immunofluorescent imaging, and genome microarray analysis. Results varied between ES cells from three progressive differentiation stages and stimulation amplitudes (nine conditions), indicating a high sensitivity to electrical pacing. Conditions that maximally encouraged cardiomyocyte differentiation were found with Day 7 EBs stimulated at 30 µA. The resulting gene expression included a sixfold increase in troponin-T and a twofold increase in β-MHCwithout increasing ES cell proliferation marker Nanog. Subsequent genome microarray analysis revealed broad transcriptome changes after pacing. Concurrent to upregulation of mature gene programs including cardiovascular, neurological, and musculoskeletal systems is the apparent downregulation of important self-renewal and pluripotency genes. Overall, a robust system capable of long-term stimulation of ES cells is demonstrated, and specific conditions are outlined that most encourage cardiomyocyte differentiation. PMID:20652088

Bench-to-bedside review: Quorum sensing and the role of cell-to-cell communication during invasive bacterial infection

PubMed Central

Asad, Shadaba; Opal, Steven M

2008-01-01

Bacteria communicate extensively with each other and employ a communal approach to facilitate survival in hostile environments. A hierarchy of cell-to-cell signaling pathways regulates bacterial growth, metabolism, biofilm formation, virulence expression, and a myriad of other essential functions in bacterial populations. The notion that bacteria can signal each other and coordinate their assault patterns against susceptible hosts is now well established. These signaling networks represent a previously unrecognized survival strategy by which bacterial pathogens evade antimicrobial defenses and overwhelm the host. These quorum sensing communication signals can transgress species barriers and even kingdom barriers. Quorum sensing molecules can regulate human transcriptional programs to the advantage of the pathogen. Human stress hormones and cytokines can be detected by bacterial quorum sensing systems. By this mechanism, the pathogen can detect the physiologically stressed host, providing an opportunity to invade when the patient is most vulnerable. These rather sophisticated, microbial communication systems may prove to be a liability to pathogens as they make convenient targets for therapeutic intervention in our continuing struggle to control microbial pathogens. PMID:19040778

Proteomics analysis of BHK-21 cells infected with a fixed strain of rabies virus.

PubMed

Zandi, Fatemeh; Eslami, Naser; Soheili, Masoomeh; Fayaz, Ahmad; Gholami, Alireza; Vaziri, Behrouz

2009-05-01

Rabies is a neurotropic virus that causes a life threatening acute viral encephalitis. The complex relationship of rabies virus (RV) with the host leads to its replication and spreading toward the neural network, where viral pathogenic effects appeared as neuronal dysfunction. In order to better understand the molecular basis of this relationship, a proteomics study on baby hamster kidney cells infected with challenge virus standard strain of RV was performed. This cell line is an in vitro model for rabies infection and is commonly used for viral seed preparation. The direct effect of the virus on cellular protein machinery was investigated by 2-DE proteome mapping of infected versus control cells followed by LC-MS/MS identification. This analysis revealed significant changes in expression of 14 proteins, seven of these proteins were viral and the remaining were host proteins with different known functions: cytoskeletal (capping protein, vimentin), anti-oxidative stress (superoxide dismutase), regulatory (Stathmin), and protein synthesis (P0). Despite of limited changes appeared upon rabies infection, they present a set of interesting biochemical pathways for further investigation on viral-host interaction.

Filopodia and Viruses: An Analysis of Membrane Processes in Entry Mechanisms

PubMed Central

Chang, Kenneth; Baginski, John; Hassan, Samer F.; Volin, Michael; Shukla, Deepak; Tiwari, Vaibhav

2016-01-01

Filopodia are thin, actin rich bundles protruding from cell plasma membranes, serving physiological purposes, such as probing the environment and facilitating cell-to-cell adhesion. Recent studies have highlighted that actively polymerized filopodial-protrusions are exploited during virus entry, trafficking, spread, and the development of clinical pathology of viral diseases. These observations have caused a surge in investigation of the key determinants of filopodial induction and their influence on cell topography including receptor expression for viral entry. It is now very clear that filopodia can provide unique opportunities for many viruses to invade host cells vertically during primary infection, or horizontally during virus spread from cell-to-cell. These emerging concepts can explain the unprecedented ability of viruses to invade both nearby and long-distant host cells, a feature that may directly contribute to viral tropism. In this review, we summarize the significance of filopodia in viral diseases and discuss future therapeutic possibilities to precisely target filopodial-flyovers to prevent or control infectious diseases. PMID:27014223

Chlamydia muridarum evades growth restriction by the IFN-gamma-inducible host resistance factor Irgb10.

PubMed

Coers, Jörn; Bernstein-Hanley, Isaac; Grotsky, David; Parvanova, Iana; Howard, Jonathan C; Taylor, Gregory A; Dietrich, William F; Starnbach, Michael N

2008-05-01

Chlamydiae are obligate intracellular bacterial pathogens that exhibit a broad range of host tropism. Differences in host tropism between Chlamydia species have been linked to host variations in IFN-gamma-mediated immune responses. In mouse cells, IFN-gamma can effectively restrict growth of the human pathogen Chlamydia trachomatis but fails to control growth of the closely related mouse pathogen Chlamydia muridarum. The ability of mouse cells to resist C. trachomatis replication is largely dependent on the induction of a family of IFN-gamma-inducible GTPases called immunity-related GTPases or IRGs. In this study we demonstrate that C. muridarum can specifically evade IRG-mediated host resistance. It has previously been suggested that C. muridarum inactivates the IRG protein Irga6 (Iigp1) to dampen the murine immune response. However, we show that Irga6 is dispensable for the control of C. trachomatis replication. Instead, an effective IFN-gamma response to C. trachomatis requires the IRG proteins Irgm1 (Lrg47), Irgm3 (Igtp), and Irgb10. Ectopic expression of Irgb10 in the absence of IFN-gamma is sufficient to reduce intracellular growth of C. trachomatis but fails to restrict growth of C. muridarum, indicating that C. muridarum can specifically evade Irgb10-driven host responses. Importantly, we find that Irgb10 protein intimately associates with inclusions harboring C. trachomatis but is absent from inclusions formed by C. muridarum. These data suggest that C. muridarum has evolved a mechanism to escape the murine IFN-gamma response by restricting access of Irgb10 and possibly other IRG proteins to the inclusion.

Donor Satellite Cell Engraftment is Significantly Augmented When the Host Niche is Preserved and Endogenous Satellite Cells are Incapacitated

PubMed Central

Boldrin, Luisa; Neal, Alice; Zammit, Peter S; Muntoni, Francesco; Morgan, Jennifer E

2012-01-01

Stem cell transplantation is already in clinical practice for certain genetic diseases and is a promising therapy for dystrophic muscle. We used the mdx mouse model of Duchenne muscular dystrophy to investigate the effect of the host satellite cell niche on the contribution of donor muscle stem cells (satellite cells) to muscle regeneration. We found that incapacitation of the host satellite cells and preservation of the muscle niche promote donor satellite cell contribution to muscle regeneration and functional reconstitution of the satellite cell compartment. But, if the host niche is not promptly refilled, or is filled by competent host satellite cells, it becomes nonfunctional and donor engraftment is negligible. Application of this regimen to aged host muscles also promotes efficient regeneration from aged donor satellite cells. In contrast, if the niche is destroyed, yet host satellite cells remain proliferation-competent, donor-derived engraftment is trivial. Thus preservation of the satellite cell niche, concomitant with functional impairment of the majority of satellite cells within dystrophic human muscles, may improve the efficiency of stem cell therapy. Stem Cells2012;30:1971–1984 PMID:22730231

The type III secretion system needle tip complex mediates host cell sensing and translocon insertion.

PubMed

Veenendaal, Andreas K J; Hodgkinson, Julie L; Schwarzer, Lynn; Stabat, David; Zenk, Sebastian F; Blocker, Ariel J

2007-03-01

Type III secretion systems (T3SSs) are essential virulence determinants of many Gram-negative bacterial pathogens. The Shigella T3SS consists of a cytoplasmic bulb, a transmembrane region and a hollow 'needle' protruding from the bacterial surface. Physical contact with host cells initiates secretion and leads to assembly of a pore, formed by IpaB and IpaC, in the host cell membrane, through which proteins that facilitate host cell invasion are translocated. As the needle is implicated in host cell sensing and secretion regulation, its tip should contain components that initiate host cell contact. Through biochemical and immunological studies of wild-type and mutant Shigella T3SS needles, we reveal tip complexes of differing compositions and functional states, which appear to represent the molecular events surrounding host cell sensing and pore formation. Our studies indicate that the interaction between IpaB and IpaD at needle tips is key to host cell sensing, orchestration of IpaC secretion and its subsequent assembly at needle tips. This allows insertion into the host cell membrane of a translocation pore that is continuous with the needle.

Mycobacterium tuberculosis Controls MicroRNA-99b (miR-99b) Expression in Infected Murine Dendritic Cells to Modulate Host Immunity*

PubMed Central

Singh, Yogesh; Kaul, Vandana; Mehra, Alka; Chatterjee, Samit; Tousif, Sultan; Dwivedi, Ved Prakash; Suar, Mrutyunjay; Van Kaer, Luc; Bishai, William R.; Das, Gobardhan

2013-01-01

Mycobacterium tuberculosis resides and replicates within host phagocytes by modulating host microbicidal responses. In addition, it suppresses the production of host protective cytokines to prevent activation of and antigen presentation by M. tuberculosis-infected cells, causing dysregulation of host protective adaptive immune responses. Many cytokines are regulated by microRNAs (miRNAs), a newly discovered class of small noncoding RNAs, which have been implicated in modulating host immune responses in many bacterial and viral diseases. Here, we show that miRNA-99b (miR-99b), an orphan miRNA, plays a key role in the pathogenesis of M. tuberculosis infection. We found that miR-99b expression was highly up-regulated in M. tuberculosis strain H37Rv-infected dendritic cells (DCs) and macrophages. Blockade of miR-99b expression by antagomirs resulted in significantly reduced bacterial growth in DCs. Interestingly, knockdown of miR-99b in DCs significantly up-regulated proinflammatory cytokines such as IL-6, IL-12, and IL-1β. Furthermore, mRNA and membrane-bound protein data indicated that inhibition of miR-99b augments TNF-α and TNFRSF-4 production. Thus, miR-99b targets TNF-α and TNFRSF-4 receptor genes. Treatment of anti-miR-99b-transfected DCs with anti-TNF-α antibody resulted in increased bacterial burden. Thus, our findings unveil a novel host evasion mechanism adopted by M. tuberculosis via miR-99b, which may open up new avenues for designing miRNA-based vaccines and therapies. PMID:23233675

Modified host cells with efflux pumps

DOEpatents

Dunlop, Mary J.; Keasling, Jay D.; Mukhopadhyay, Aindrila

2016-08-30

The present invention provides for a modified host cell comprising a heterologous expression of an efflux pump capable of transporting an organic molecule out of the host cell wherein the organic molecule at a sufficiently high concentration reduces the growth rate of or is lethal to the host cell.

Dramatic Transcriptional Changes in an Intracellular Parasite Enable Host Switching between Plant and Insect

PubMed Central

Oshima, Kenro; Ishii, Yoshiko; Kakizawa, Shigeyuki; Sugawara, Kyoko; Neriya, Yutaro; Himeno, Misako; Minato, Nami; Miura, Chihiro; Shiraishi, Takuya; Yamaji, Yasuyuki; Namba, Shigetou

2011-01-01

Phytoplasmas are bacterial plant pathogens that have devastating effects on the yields of crops and plants worldwide. They are intracellular parasites of both plants and insects, and are spread among plants by insects. How phytoplasmas can adapt to two diverse environments is of considerable interest; however, the mechanisms enabling the “host switching” between plant and insect hosts are poorly understood. Here, we report that phytoplasmas dramatically alter their gene expression in response to “host switching” between plant and insect. We performed a detailed characterization of the dramatic change that occurs in the gene expression profile of Candidatus Phytoplasma asteris OY-M strain (approximately 33% of the genes change) upon host switching between plant and insect. The phytoplasma may use transporters, secreted proteins, and metabolic enzymes in a host-specific manner. As phytoplasmas reside within the host cell, the proteins secreted from phytoplasmas are thought to play crucial roles in the interplay between phytoplasmas and host cells. Our microarray analysis revealed that the expression of the gene encoding the secreted protein PAM486 was highly upregulated in the plant host, which is also observed by immunohistochemical analysis, suggesting that this protein functions mainly when the phytoplasma grows in the plant host. Additionally, phytoplasma growth in planta was partially suppressed by an inhibitor of the MscL osmotic channel that is highly expressed in the plant host, suggesting that the osmotic channel might play an important role in survival in the plant host. These results also suggest that the elucidation of “host switching” mechanism may contribute to the development of novel pest controls. PMID:21858041

Mining Host-Pathogen Protein Interactions to Characterize Burkholderia mallei Infectivity Mechanisms

PubMed Central

Memišević, Vesna; Zavaljevski, Nela; Rajagopala, Seesandra V.; Kwon, Keehwan; Pieper, Rembert; DeShazer, David; Reifman, Jaques; Wallqvist, Anders

2015-01-01

Burkholderia pathogenicity relies on protein virulence factors to control and promote bacterial internalization, survival, and replication within eukaryotic host cells. We recently used yeast two-hybrid (Y2H) screening to identify a small set of novel Burkholderia proteins that were shown to attenuate disease progression in an aerosol infection animal model using the virulent Burkholderia mallei ATCC 23344 strain. Here, we performed an extended analysis of primarily nine B. mallei virulence factors and their interactions with human proteins to map out how the bacteria can influence and alter host processes and pathways. Specifically, we employed topological analyses to assess the connectivity patterns of targeted host proteins, identify modules of pathogen-interacting host proteins linked to processes promoting infectivity, and evaluate the effect of crosstalk among the identified host protein modules. Overall, our analysis showed that the targeted host proteins generally had a large number of interacting partners and interacted with other host proteins that were also targeted by B. mallei proteins. We also introduced a novel Host-Pathogen Interaction Alignment (HPIA) algorithm and used it to explore similarities between host-pathogen interactions of B. mallei, Yersinia pestis, and Salmonella enterica. We inferred putative roles of B. mallei proteins based on the roles of their aligned Y. pestis and S. enterica partners and showed that up to 73% of the predicted roles matched existing annotations. A key insight into Burkholderia pathogenicity derived from these analyses of Y2H host-pathogen interactions is the identification of eukaryotic-specific targeted cellular mechanisms, including the ubiquitination degradation system and the use of the focal adhesion pathway as a fulcrum for transmitting mechanical forces and regulatory signals. This provides the mechanisms to modulate and adapt the host-cell environment for the successful establishment of host infections and intracellular spread. PMID:25738731

Mining host-pathogen protein interactions to characterize Burkholderia mallei infectivity mechanisms.

PubMed

Memišević, Vesna; Zavaljevski, Nela; Rajagopala, Seesandra V; Kwon, Keehwan; Pieper, Rembert; DeShazer, David; Reifman, Jaques; Wallqvist, Anders

2015-03-01

Burkholderia pathogenicity relies on protein virulence factors to control and promote bacterial internalization, survival, and replication within eukaryotic host cells. We recently used yeast two-hybrid (Y2H) screening to identify a small set of novel Burkholderia proteins that were shown to attenuate disease progression in an aerosol infection animal model using the virulent Burkholderia mallei ATCC 23344 strain. Here, we performed an extended analysis of primarily nine B. mallei virulence factors and their interactions with human proteins to map out how the bacteria can influence and alter host processes and pathways. Specifically, we employed topological analyses to assess the connectivity patterns of targeted host proteins, identify modules of pathogen-interacting host proteins linked to processes promoting infectivity, and evaluate the effect of crosstalk among the identified host protein modules. Overall, our analysis showed that the targeted host proteins generally had a large number of interacting partners and interacted with other host proteins that were also targeted by B. mallei proteins. We also introduced a novel Host-Pathogen Interaction Alignment (HPIA) algorithm and used it to explore similarities between host-pathogen interactions of B. mallei, Yersinia pestis, and Salmonella enterica. We inferred putative roles of B. mallei proteins based on the roles of their aligned Y. pestis and S. enterica partners and showed that up to 73% of the predicted roles matched existing annotations. A key insight into Burkholderia pathogenicity derived from these analyses of Y2H host-pathogen interactions is the identification of eukaryotic-specific targeted cellular mechanisms, including the ubiquitination degradation system and the use of the focal adhesion pathway as a fulcrum for transmitting mechanical forces and regulatory signals. This provides the mechanisms to modulate and adapt the host-cell environment for the successful establishment of host infections and intracellular spread.

Establishment of Myotis myotis cell lines--model for investigation of host-pathogen interaction in a natural host for emerging viruses.

PubMed

He, Xiaocui; Korytář, Tomáš; Zhu, Yaqing; Pikula, Jiří; Bandouchova, Hana; Zukal, Jan; Köllner, Bernd

2014-01-01

Bats are found to be the natural reservoirs for many emerging viruses. In most cases, severe clinical signs caused by such virus infections are normally not seen in bats. This indicates differences in the virus-host interactions and underlines the necessity to develop natural host related models to study these phenomena. Due to the strict protection of European bat species, immortalized cell lines are the only alternative to investigate the innate anti-virus immune mechanisms. Here, we report about the establishment and functional characterization of Myotis myotis derived cell lines from different tissues: brain (MmBr), tonsil (MmTo), peritoneal cavity (MmPca), nasal epithelium (MmNep) and nervus olfactorius (MmNol) after immortalization by SV 40 large T antigen. The usefulness of these cell lines to study antiviral responses has been confirmed by analysis of their susceptibility to lyssavirus infection and the mRNA patterns of immune-relevant genes after poly I:C stimulation. Performed experiments indicated varying susceptibility to lyssavirus infection with MmBr being considerably less susceptible than the other cell lines. Further investigation demonstrated a strong activation of interferon mediated antiviral response in MmBr contributing to its resistance. The pattern recognition receptors: RIG-I and MDA5 were highly up-regulated during rabies virus infection in MmBr, suggesting their involvement in promotion of antiviral responses. The presence of CD14 and CD68 in MmBr suggested MmBr cells are microglia-like cells which play a key role in host defense against infections in the central nervous system (CNS). Thus the expression pattern of MmBr combined with the observed limitation of lyssavirus replication underpin a protective mechanism of the CNS controlling the lyssavirus infection. Overall, the established cell lines are important tools to analyze antiviral innate immunity in M. myotis against neurotropic virus infections and present a valuable tool for a broad spectrum of future investigations in cellular biology of M. myotis.

Establishment of Myotis myotis Cell Lines - Model for Investigation of Host-Pathogen Interaction in a Natural Host for Emerging Viruses

PubMed Central

He, Xiaocui; Korytář, Tomáš; Zhu, Yaqing; Pikula, Jiří; Bandouchova, Hana; Zukal, Jan; Köllner, Bernd

2014-01-01

Bats are found to be the natural reservoirs for many emerging viruses. In most cases, severe clinical signs caused by such virus infections are normally not seen in bats. This indicates differences in the virus-host interactions and underlines the necessity to develop natural host related models to study these phenomena. Due to the strict protection of European bat species, immortalized cell lines are the only alternative to investigate the innate anti-virus immune mechanisms. Here, we report about the establishment and functional characterization of Myotis myotis derived cell lines from different tissues: brain (MmBr), tonsil (MmTo), peritoneal cavity (MmPca), nasal epithelium (MmNep) and nervus olfactorius (MmNol) after immortalization by SV 40 large T antigen. The usefulness of these cell lines to study antiviral responses has been confirmed by analysis of their susceptibility to lyssavirus infection and the mRNA patterns of immune-relevant genes after poly I:C stimulation. Performed experiments indicated varying susceptibility to lyssavirus infection with MmBr being considerably less susceptible than the other cell lines. Further investigation demonstrated a strong activation of interferon mediated antiviral response in MmBr contributing to its resistance. The pattern recognition receptors: RIG-I and MDA5 were highly up-regulated during rabies virus infection in MmBr, suggesting their involvement in promotion of antiviral responses. The presence of CD14 and CD68 in MmBr suggested MmBr cells are microglia-like cells which play a key role in host defense against infections in the central nervous system (CNS). Thus the expression pattern of MmBr combined with the observed limitation of lyssavirus replication underpin a protective mechanism of the CNS controlling the lyssavirus infection. Overall, the established cell lines are important tools to analyze antiviral innate immunity in M. myotis against neurotropic virus infections and present a valuable tool for a broad spectrum of future investigations in cellular biology of M. myotis. PMID:25295526

Ixodes scapularis Tick Cells Control Anaplasma phagocytophilum Infection by Increasing the Synthesis of Phosphoenolpyruvate from Tyrosine.

PubMed

Cabezas-Cruz, Alejandro; Espinosa, Pedro J; Obregón, Dasiel A; Alberdi, Pilar; de la Fuente, José

2017-01-01

The obligate intracellular pathogen, Anaplasma phagocytophilum , is the causative agent of life-threatening diseases in humans and animals. A. phagocytophilum is an emerging tick-borne pathogen in the United States, Europe, Africa and Asia, with increasing numbers of infected people and animals every year. It is increasingly recognized that intracellular pathogens modify host cell metabolic pathways to increase infection and transmission in both vertebrate and invertebrate hosts. Recent reports have shown that amino acids are central to the host-pathogen metabolic interaction. In this study, a genome-wide search for components of amino acid metabolic pathways was performed in Ixodes scapularis , the main tick vector of A. phagocytophilum in the United States, for which the genome was recently published. The enzymes involved in the synthesis and degradation pathways of the twenty amino acids were identified. Then, the available transcriptomics and proteomics data was used to characterize the mRNA and protein levels of I. scapularis amino acid metabolic pathway components in response to A. phagocytophilum infection of tick tissues and ISE6 tick cells. Our analysis was focused on the interplay between carbohydrate and amino acid metabolism during A. phagocytophilum infection in ISE6 cells. The results showed that tick cells increase the synthesis of phosphoenolpyruvate (PEP) from tyrosine to control A. phagocytophilum infection. Metabolic pathway analysis suggested that this is achieved by (i) increasing the transcript and protein levels of mitochondrial phosphoenolpyruvate carboxykinase (PEPCK-M), (ii) shunting tyrosine into the tricarboxylic acid (TCA) cycle to increase fumarate and oxaloacetate which will be converted into PEP by PEPCK-M, and (iii) blocking all the pathways that use PEP downstream gluconeogenesis (i.e., de novo serine synthesis pathway (SSP), glyceroneogenesis and gluconeogenesis). While sequestering host PEP may be critical for this bacterium because it cannot actively carry out glycolysis to produce PEP, excess of this metabolite may be toxic for A. phagocytophilum . The present work provides a more comprehensive view of the major amino acid metabolic pathways involved in the response to pathogen infection in ticks, and provides the basis for further studies to develop novel strategies for the control of granulocytic anaplasmosis.

Trans-suppression of defense DEFB1 gene in intestinal epithelial cells following Cryptosporidium parvum infection is associated with host delivery of parasite Cdg7_FLc_1000 RNA.

PubMed

Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Dolata, Courtney E; Chen, Xian-Ming

2018-03-01

To counteract host immunity, Cryptosporidium parvum has evolved multiple strategies to suppress host antimicrobial defense. One such strategy is to reduce the production of the antimicrobial peptide beta-defensin 1 (DEFB1) by host epithelial cells but the underlying mechanisms remain unclear. Recent studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of intestinal cryptosporidiosis, in this study, we analyzed the expression profile of host beta-defensin genes in host cells following infection. We found that C. parvum infection caused a significant downregulation of the DEFB1 gene. Interestingly, downregulation of DEFB1 gene was associated with host delivery of Cdg7_FLc_1000 RNA transcript, a C. parvum RNA that has previously demonstrated to be delivered into the nuclei of infected host cells. Knockdown of Cdg7_FLc_1000 in host cells could attenuate the trans-suppression of host DEFB1 gene and decreased the parasite burden. Therefore, our data suggest that trans-suppression of DEFB1 gene in intestinal epithelial cells following C. parvum infection involves host delivery of parasite Cdg7_FLc_1000 RNA, a process that may be relevant to the epithelial defense evasion by C. parvum at the early stage of infection.

50-plus years of fungal viruses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ghabrial, Said A., E-mail: saghab00@email.uky.edu; Castón, José R.; Jiang, Daohong

2015-05-15

Mycoviruses are widespread in all major taxa of fungi. They are transmitted intracellularly during cell division, sporogenesis, and/or cell-to-cell fusion (hyphal anastomosis), and thus their life cycles generally lack an extracellular phase. Their natural host ranges are limited to individuals within the same or closely related vegetative compatibility groups, although recent advances have established expanded experimental host ranges for some mycoviruses. Most known mycoviruses have dsRNA genomes packaged in isometric particles, but an increasing number of positive- or negative-strand ssRNA and ssDNA viruses have been isolated and characterized. Although many mycoviruses do not have marked effects on their hosts, thosemore » that reduce the virulence of their phytopathogenic fungal hosts are of considerable interest for development of novel biocontrol strategies. Mycoviruses that infect endophytic fungi and those that encode killer toxins are also of special interest. Structural analyses of mycoviruses have promoted better understanding of virus assembly, function, and evolution. - Highlights: • Historical perspective of fungal virus research. • Description, classification and diversity of fungal virus families. • Structural features of fungal virus particles. • Hypovirulence and exploitation of mycoviruses in biological control of plant pathogenic fungi.« less

Simulation of the M13 life cycle II: Investigation of the control mechanisms of M13 infection and establishment of the carrier state.

PubMed

Smeal, Steven W; Schmitt, Margaret A; Pereira, Ronnie Rodrigues; Prasad, Ashok; Fisk, John D

2017-01-01

Bacteriophage M13 is a true parasite of bacteria, able to co-opt the infected cell and control the production of progeny across many cellular generations. Here, our genetically-structured simulation of M13 is applied to quantitatively dissect the interplay between the host cellular environment and the controlling interactions governing the phage life cycle during the initial establishment of infection and across multiple cell generations. Multiple simulations suggest that phage-encoded feedback interactions constrain the utilization of host DNA polymerase, RNA polymerase and ribosomes. The simulation reveals the importance of p5 translational attenuation in controlling the production of phage double-stranded DNA and suggests an underappreciated role for p5 translational self-attenuation in resource allocation. The control elements active in a single generation are sufficient to reproduce the experimentally-observed multigenerational curing of the phage infection. Understanding the subtleties of regulation will be important for maximally exploiting M13 particles as scaffolds for nanoscale devices. Copyright © 2016 Elsevier Inc. All rights reserved.

Copper Acquisition and Utilization in Fungi.

PubMed

Smith, Aaron D; Logeman, Brandon L; Thiele, Dennis J

2017-09-08

Fungal cells colonize and proliferate in distinct niches, from soil and plants to diverse tissues in human hosts. Consequently, fungi are challenged with the goal of obtaining nutrients while simultaneously elaborating robust regulatory mechanisms to cope with a range of availability of nutrients, from scarcity to excess. Copper is essential for life but also potentially toxic. In this review we describe the sophisticated homeostatic mechanisms by which fungi acquire, utilize, and control this biochemically versatile trace element. Fungal pathogens, which can occupy distinct host tissues that have their own intrinsic requirements for copper homeostasis, have evolved mechanisms to acquire copper to successfully colonize the host, disseminate to other tissues, and combat host copper bombardment mechanisms that would otherwise mitigate virulence.

Role of Chemokines and Trafficking of Immune Cells in Parasitic Infections

PubMed Central

McGovern, Kathryn E.; Wilson, Emma H.

2014-01-01

Parasites are diverse eukaryotic pathogens that can have complex life cycles. Their clearance, or control within a mammalian host requires the coordinated effort of the immune system. The cell types recruited to areas of infection can combat the disease, promote parasite replication and survival, or contribute to disease pathology. Location and timing of cell recruitment can be crucial. In this review, we explore the role chemokines play in orchestrating and balancing the immune response to achieve optimal control of parasite replication without promoting pathology. PMID:25383073

Lymphoproliferative and gamma interferon responses to stress-regulated Mycobacterium avium subsp. paratuberculosis recombinant proteins.

PubMed

Gurung, Ratna B; Begg, Douglas J; Purdie, Auriol C; de Silva, Kumudika; Bannantine, John P; Whittington, Richard J

2014-06-01

Johne's disease in ruminants is a chronic infection of the intestines caused by Mycobacterium avium subsp. paratuberculosis. An important strategy to control disease is early detection, and a potentially efficient method for early detection is measurement of cell-mediated immune responses developed by the host in response to exposure or infection. One method is to measure lymphoproliferation and cytokine release from the host cells when exposed to the organism or parts of the organism. In this study, 10 recombinant M. avium subsp. paratuberculosis proteins known to be upregulated under in vitro stress conditions were evaluated by examining their ability to evoke memory as a result of exposure by vaccination or oral challenge with live Mycobacterium avium subsp. paratuberculosis. Out of 10 proteins, MAP2698c was found to induce higher cell-mediated immune responses in vaccinated and challenged sheep in comparison to healthy controls. The findings suggest that not all stress-regulated proteins have the diagnostic potential to detect cell-mediated immune responses in ovine paratuberculosis. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

Mycobacterium tuberculosis Infection and Innate Responses in a New Model of Lung Alveolar Macrophages.

PubMed

Woo, Minjeong; Wood, Connor; Kwon, Doyoon; Park, Kyu-Ho Paul; Fejer, György; Delorme, Vincent

2018-01-01

Lung alveolar macrophages (AMs) are in the first line of immune defense against respiratory pathogens and play key roles in the pathogenesis of Mycobacterium tuberculosis ( Mtb ) in humans. Nevertheless, AMs are available only in limited amounts for in vitro studies, which hamper the detailed molecular understanding of host- Mtb interactions in these macrophages. The recent establishment of the self-renewing and primary Max Planck Institute (MPI) cells, functionally very close to lung AMs, opens unique opportunities for in vitro studies of host-pathogen interactions in respiratory diseases. Here, we investigated the suitability of MPI cells as a host cell system for Mtb infection. Bacterial, cellular, and innate immune features of MPI cells infected with Mtb were characterized. Live bacteria were readily internalized and efficiently replicated in MPI cells, similarly to primary murine macrophages and other cell lines. MPI cells were also suitable for the determination of anti-tuberculosis (TB) drug activity. The primary innate immune response of MPI cells to live Mtb showed significantly higher and earlier induction of the pro-inflammatory cytokines TNFα, interleukin 6 (IL-6), IL-1α, and IL-1β, as compared to stimulation with heat-killed (HK) bacteria. MPI cells previously showed a lack of induction of the anti-inflammatory cytokine IL-10 to a wide range of stimuli, including HK Mtb . By contrast, we show here that live Mtb is able to induce significant amounts of IL-10 in MPI cells. Autophagy experiments using light chain 3B immunostaining, as well as LysoTracker labeling of acidic vacuoles, demonstrated that MPI cells efficiently control killed Mtb by elimination through phagolysosomes. MPI cells were also able to accumulate lipid droplets in their cytoplasm following exposure to lipoproteins. Collectively, this study establishes the MPI cells as a relevant, versatile host cell model for TB research, allowing a deeper understanding of AMs functions in this pathology.

The molecular network governing nodule organogenesis and infection in the model legume Lotus japonicus.

PubMed

Madsen, Lene H; Tirichine, Leïla; Jurkiewicz, Anna; Sullivan, John T; Heckmann, Anne B; Bek, Anita S; Ronson, Clive W; James, Euan K; Stougaard, Jens

2010-04-12

Bacterial infection of interior tissues of legume root nodules is controlled at the epidermal cell layer and is closely coordinated with progressing organ development. Using spontaneous nodulating Lotus japonicus plant mutants to uncouple nodule organogenesis from infection, we have determined the role of 16 genes in these two developmental processes. We show that host-encoded mechanisms control three alternative entry processes operating in the epidermis, the root cortex and at the single cell level. Single cell infection did not involve the formation of trans-cellular infection threads and was independent of host Nod-factor receptors and bacterial Nod-factor signals. In contrast, Nod-factor perception was required for epidermal root hair infection threads, whereas primary signal transduction genes preceding the secondary Ca2+ oscillations have an indirect role. We provide support for the origin of rhizobial infection through direct intercellular epidermal invasion and subsequent evolution of crack entry and root hair invasions observed in most extant legumes.

Inhibition of Avian Influenza A Virus Replication in Human Cells by Host Restriction Factor TUFM Is Correlated with Autophagy.

PubMed

Kuo, Shu-Ming; Chen, Chi-Jene; Chang, Shih-Cheng; Liu, Tzu-Jou; Chen, Yi-Hsiang; Huang, Sheng-Yu; Shih, Shin-Ru

2017-06-13

Avian influenza A viruses generally do not replicate efficiently in human cells, but substitution of glutamic acid (Glu, E) for lysine (Lys, K) at residue 627 of avian influenza virus polymerase basic protein 2 (PB2) can serve to overcome host restriction and facilitate human infectivity. Although PB2 residue 627 is regarded as a species-specific signature of influenza A viruses, host restriction factors associated with PB2 627 E have yet to be fully investigated. We conducted immunoprecipitation, followed by differential proteomic analysis, to identify proteins associating with PB2 627 K (human signature) and PB2 627 E (avian signature) of influenza A/WSN/1933(H1N1) virus, and the results indicated that Tu elongation factor, mitochondrial (TUFM), had a higher binding affinity for PB2 627 E than PB2 627 K in transfected human cells. Stronger binding of TUFM to avian-signature PB2 590 G/ 591 Q and PB2 627 E in the 2009 swine-origin pandemic H1N1 and 2013 avian-origin H7N9 influenza A viruses was similarly observed. Viruses carrying avian-signature PB2 627 E demonstrated increased replication in TUFM-deficient cells, but viral replication decreased in cells overexpressing TUFM. Interestingly, the presence of TUFM specifically inhibited the replication of PB2 627 E viruses, but not PB2 627 K viruses. In addition, enhanced levels of interaction between TUFM and PB2 627 E were noted in the mitochondrial fraction of infected cells. Furthermore, TUFM-dependent autophagy was reduced in TUFM-deficient cells infected with PB2 627 E virus; however, autophagy remained consistent in PB2 627 K virus-infected cells. The results suggest that TUFM acts as a host restriction factor that impedes avian-signature influenza A virus replication in human cells in a manner that correlates with autophagy. IMPORTANCE An understanding of the mechanisms that influenza A viruses utilize to shift host tropism and the identification of host restriction factors that can limit infection are both critical to the prevention and control of emerging viruses that cross species barriers to target new hosts. Using a proteomic approach, we revealed a novel role for TUFM as a host restriction factor that exerts an inhibitory effect on avian-signature PB2 627 E influenza virus propagation in human cells. We further found that increased TUFM-dependent autophagy correlates with the inhibitory effect on avian-signature influenza virus replication and may serve as a key intrinsic mechanism to restrict avian influenza virus infection in humans. These findings provide new insight regarding the TUFM mitochondrial protein and may have important implications for the development of novel antiviral strategies. Copyright © 2017 Kuo et al.

Apparatus and method for transforming living cells

DOEpatents

Okandan, Murat; Galambos, Paul C.

2003-11-11

An apparatus and method are disclosed for in vitro transformation of living cells. The apparatus, which is formed as a microelectromechanical device by surface micromachining, can be used to temporarily disrupt the cell walls or membrane of host cells one at a time so that a particular substance (e.g. a molecular tag, nucleic acid, bacteria, virus etc.) can be introduced into the cell. Disruption of the integrity of the host cells (i.e. poration) can be performed mechanically or electrically, or by both while the host cells are contained within a flow channel. Mechanical poration is possible using a moveable member which has a pointed or serrated edge and which is driven by an electrostatic actuator to abrade, impact or penetrate the host cell. Electroporation is produced by generating a relatively high electric field across the host cell when the host cell is located in the flow channel between a pair of electrodes having a voltage applied therebetween.

Specific Midgut Region Controlling the Symbiont Population in an Insect-Microbe Gut Symbiotic Association

PubMed Central

Kim, Jiyeun Kate; Kim, Na Hyang; Jang, Ho Am; Kikuchi, Yoshitomo; Kim, Chan-Hee

2013-01-01

Many insects possess symbiotic bacteria that affect the biology of the host. The level of the symbiont population in the host is a pivotal factor that modulates the biological outcome of the symbiotic association. Hence, the symbiont population should be maintained at a proper level by the host's control mechanisms. Several mechanisms for controlling intracellular symbionts of insects have been reported, while mechanisms for controlling extracellular gut symbionts of insects are poorly understood. The bean bug Riptortus pedestris harbors a betaproteobacterial extracellular symbiont of the genus Burkholderia in the midgut symbiotic organ designated the M4 region. We found that the M4B region, which is directly connected to the M4 region, also harbors Burkholderia symbiont cells, but the symbionts therein are mostly dead. A series of experiments demonstrated that the M4B region exhibits antimicrobial activity, and the antimicrobial activity is specifically potent against the Burkholderia symbiont but not the cultured Burkholderia and other bacteria. The antimicrobial activity of the M4B region was detected in symbiotic host insects, reaching its highest point at the fifth instar, but not in aposymbiotic host insects, which suggests the possibility of symbiont-mediated induction of the antimicrobial activity. This antimicrobial activity was not associated with upregulation of antimicrobial peptides of the host. Based on these results, we propose that the M4B region is a specialized gut region of R. pedestris that plays a critical role in controlling the population of the Burkholderia gut symbiont. The molecular basis of the antimicrobial activity is of great interest and deserves future study. PMID:24038695

More than the “Killer Trait”: Infection with the Bacterial Endosymbiont Caedibacter taeniospiralis Causes Transcriptomic Modulation in Paramecium Host

PubMed Central

Grosser, Katrin; Ramasamy, Pathmanaban; Amirabad, Azim Dehghani; Schulz, Marcel H; Gasparoni, Gilles; Simon, Martin

2018-01-01

Abstract Endosymbiosis is a widespread phenomenon and hosts of bacterial endosymbionts can be found all-over the eukaryotic tree of life. Likely, this evolutionary success is connected to the altered phenotype arising from a symbiotic association. The potential variety of symbiont’s contributions to new characteristics or abilities of host organisms are largely unstudied. Addressing this aspect, we focused on an obligate bacterial endosymbiont that confers an intraspecific killer phenotype to its host. The symbiosis between Paramecium tetraurelia and Caedibacter taeniospiralis, living in the host’s cytoplasm, enables the infected paramecia to release Caedibacter symbionts, which can simultaneously produce a peculiar protein structure and a toxin. The ingestion of bacteria that harbor both components leads to the death of symbiont-free congeners. Thus, the symbiosis provides Caedibacter-infected cells a competitive advantage, the “killer trait.” We characterized the adaptive gene expression patterns in symbiont-harboring Paramecium as a second symbiosis-derived aspect next to the killer phenotype. Comparative transcriptomics of infected P. tetraurelia and genetically identical symbiont-free cells confirmed altered gene expression in the symbiont-bearing line. Our results show up-regulation of specific metabolic and heat shock genes whereas down-regulated genes were involved in signaling pathways and cell cycle regulation. Functional analyses to validate the transcriptomics results demonstrated that the symbiont increases host density hence providing a fitness advantage. Comparative transcriptomics shows gene expression modulation of a ciliate caused by its bacterial endosymbiont thus revealing new adaptive advantages of the symbiosis. Caedibacter taeniospiralis apparently increases its host fitness via manipulation of metabolic pathways and cell cycle control. PMID:29390087

Anti-infective Activity of 2-Cyano-3-Acrylamide Inhibitors with Improved Drug-Like Properties against Two Intracellular Pathogens

PubMed Central

Passalacqua, Karla D.; Charbonneau, Marie-Eve; Donato, Nicholas J.; Showalter, Hollis D.; Sun, Duxin; Wen, Bo; He, Miao; Sun, Hanshi

2016-01-01

Due to the rise of antibiotic resistance and the small number of effective antiviral drugs, new approaches for treating infectious diseases are urgently needed. Identifying targets for host-based therapies represents an emerging strategy for drug discovery. The ubiquitin-proteasome system is a central mode of signaling in the eukaryotic cell and may be a promising target for therapies that bolster the host's ability to control infection. Deubiquitinase (DUB) enzymes are key regulators of the host inflammatory response, and we previously demonstrated that a selective DUB inhibitor and its derivative promote anti-infective activities in host cells. To find compounds with anti-infective efficacy but improved toxicity profiles, we tested a library of predominantly 2-cyano-3-acrylamide small-molecule DUB inhibitors for anti-infective activity in macrophages against two intracellular pathogens: murine norovirus (MNV) and Listeria monocytogenes. We identified compound C6, which inhibited DUB activity in human and murine cells and reduced intracellular replication of both pathogens with minimal toxicity in cell culture. Treatment with C6 did not significantly affect the ability of macrophages to internalize virus, suggesting that the anti-infective activity interferes with postentry stages of the MNV life cycle. Metabolic stability and pharmacokinetic assays showed that C6 has a half-life in mouse liver microsomes of ∼20 min and has a half-life of approximately 4 h in mice when administered intravenously. Our results provide a framework for targeting the host ubiquitin system in the development of host-based therapies for infectious disease. Compound C6 represents a promising tool with which to elucidate the role of DUBs in the macrophage response to infection. PMID:27139470

Chewing the fat: lipid metabolism and homeostasis during M. tuberculosis infection.

PubMed

Lovewell, Rustin R; Sassetti, Christopher M; VanderVen, Brian C

2016-02-01

The interplay between Mycobacterium tuberculosis lipid metabolism, the immune response and lipid homeostasis in the host creates a complex and dynamic pathogen-host interaction. Advances in imaging and metabolic analysis techniques indicate that M. tuberculosis preferentially associates with foamy cells and employs multiple physiological systems to utilize exogenously derived fatty-acids and cholesterol. Moreover, novel insights into specific host pathways that control lipid accumulation during infection, such as the PPARγ and LXR transcriptional regulators, have begun to reveal mechanisms by which host immunity alters the bacterial micro-environment. As bacterial lipid metabolism and host lipid regulatory pathways are both important, yet inherently complex, components of active tuberculosis, delineating the heterogeneity in lipid trafficking within disease states remains a major challenge for therapeutic design. Copyright © 2015. Published by Elsevier Ltd.

Imaging host cell-Leishmania interaction dynamics implicates parasite motility, lysosome recruitment, and host cell wounding in the infection process.

PubMed

Forestier, Claire-Lise; Machu, Christophe; Loussert, Celine; Pescher, Pascale; Späth, Gerald F

2011-04-21

Leishmania donovani causes human visceral leishmaniasis. The parasite infectious cycle comprises extracellular flagellated promastigotes that proliferate inside the insect vector, and intracellular nonmotile amastigotes that multiply within infected host cells. Using primary macrophages infected with virulent metacyclic promastigotes and high spatiotemporal resolution microscopy, we dissect the dynamics of the early infection process. We find that motile promastigotes enter macrophages in a polarized manner through their flagellar tip and are engulfed into host lysosomal compartments. Persistent intracellular flagellar activity leads to reorientation of the parasite flagellum toward the host cell periphery and results in oscillatory parasite movement. The latter is associated with local lysosomal exocytosis and host cell plasma membrane wounding. These findings implicate lysosome recruitment followed by lysosome exocytosis, consistent with parasite-driven host cell injury, as key cellular events in Leishmania host cell infection. This work highlights the role of promastigote polarity and motility during parasite entry. Copyright © 2011 Elsevier Inc. All rights reserved.

Host cell processes that influence the intracellular survival of Legionella pneumophila.

PubMed

Shin, Sunny; Roy, Craig R

2008-06-01

Key to the pathogenesis of intracellular pathogens is their ability to manipulate host cell processes, permitting the establishment of an intracellular replicative niche. In turn, the host cell deploys defence mechanisms that limit intracellular infection. The bacterial pathogen Legionella pneumophila, the aetiological agent of Legionnaire's Disease, has evolved virulence mechanisms that allow it to replicate within protozoa, its natural host. Many of these tactics also enable L. pneumophila's survival and replication inside macrophages within a membrane-bound compartment known as the Legionella-containing vacuole. One of the virulence factors indispensable for L. pneumophila's intracellular survival is a type IV secretion system, which translocates a large repertoire of bacterial effectors into the host cell. These effectors modulate multiple host cell processes and in particular, redirect trafficking of the L. pneumophila phagosome and mediate its conversion into an ER-derived organelle competent for intracellular bacterial replication. In this review, we discuss how L. pneumophila manipulates host cells, as well as host cell processes that either facilitate or impede its intracellular survival.

Control of B-cell responses by Toll-like receptors

NASA Astrophysics Data System (ADS)

Pasare, Chandrashekhar; Medzhitov, Ruslan

2005-11-01

Toll-like receptors (TLRs) detect microbial infection and have an essential role in the induction of immune responses. TLRs can directly induce innate host defence responses, but the mechanisms of TLR-mediated control of adaptive immunity are not fully understood. Although TLR-induced dendritic cell maturation is required for activation of T-helper (TH) cells, the role of TLRs in B-cell activation and antibody production in vivo is not yet known. Here we show that activation and differentiation of TH cells is not sufficient for the induction of T-dependent B-cell responses. We find that, in addition to CD4+ T-cell help, generation of T-dependent antigen-specific antibody responses requires activation of TLRs in B cells.

Type 2 immunity and wound healing: evolutionary refinement of adaptive immunity by helminths

PubMed Central

Gause, William C.; Wynn, Thomas A.; Allen, Judith E.

2013-01-01

Helminth-induced type 2 immune responses, which are characterized by the T helper 2 cell-associated cytokines interleukin-4 (IL-4) and IL-13, mediate host protection through enhanced tissue repair, the control of inflammation and worm expulsion. In this Opinion article, we consider type 2 immunity in the context of helminth-mediated tissue damage. We examine the relationship between the control of helminth infection and the mechanisms of wound repair, and we provide a new understanding of the adaptive type 2 immune response and its contribution to both host tolerance and resistance. PMID:23827958

Unique physiology of host-parasite interactions in microsporidia infections.

PubMed

Williams, Bryony A P

2009-11-01

Microsporidia are intracellular parasites of all major animal lineages and have a described diversity of over 1200 species and an actual diversity that is estimated to be much higher. They are important pathogens of mammals, and are now one of the most common infections among immunocompromised humans. Although related to fungi, microsporidia are atypical in genomic biology, cell structure and infection mechanism. Host cell infection involves the rapid expulsion of a polar tube from a dormant spore to pierce the host cell membrane and allow the direct transfer of the spore contents into the host cell cytoplasm. This intimate relationship between parasite and host is unique. It allows the microsporidia to be highly exploitative of the host cell environment and cause such diverse effects as the induction of hypertrophied cells to harbour prolific spore development, host sex ratio distortion and host cell organelle and microtubule reorganization. Genome sequencing has revealed that microsporidia have achieved this high level of parasite sophistication with radically reduced proteomes and with many typical eukaryotic pathways pared-down to what appear to be minimal functional units. These traits make microsporidia intriguing model systems for understanding the extremes of reductive parasite evolution and host cell manipulation.

Synchronous induction of detachment and reattachment of symbiotic Chlorella spp. from the cell cortex of the host Paramecium bursaria.

PubMed

Kodama, Yuuki; Fujishima, Masahiro

2013-09-01

Paramecium bursaria harbor several hundred symbiotic Chlorella spp. Each alga is enclosed in a perialgal vacuole membrane, which can attach to the host cell cortex. How the perialgal vacuole attaches beneath the host cell cortex remains unknown. High-speed centrifugation (> 1000×g) for 1min induces rapid detachment of the algae from the host cell cortex and concentrates the algae to the posterior half of the host cell. Simultaneously, most of the host acidosomes and lysosomes accumulate in the anterior half of the host cell. Both the detached algae and the dislocated acidic vesicles recover their original positions by host cyclosis within 10min after centrifugation. These recoveries were inhibited if the host cytoplasmic streaming was arrested by nocodazole. Endosymbiotic algae during the early reinfection process also show the capability of desorption after centrifugation. These results demonstrate that adhesion of the perialgal vacuole beneath the host cell cortex is repeatedly inducible, and that host cytoplasmic streaming facilitates recovery of the algal attachment. This study is the first report to illuminate the mechanism of the induction to desorb for symbiotic algae and acidic vesicles, and will contribute to the understanding of the mechanism of algal and organelle arrangements in Paramecium. Copyright © 2013 Elsevier GmbH. All rights reserved.

Intracellular growth of Mycobacterium tuberculosis after macrophage cell death leads to serial killing of host cells

PubMed Central

Mahamed, Deeqa; Boulle, Mikael; Ganga, Yashica; Mc Arthur, Chanelle; Skroch, Steven; Oom, Lance; Catinas, Oana; Pillay, Kelly; Naicker, Myshnee; Rampersad, Sanisha; Mathonsi, Colisile; Hunter, Jessica; Wong, Emily B; Suleman, Moosa; Sreejit, Gopalkrishna; Pym, Alexander S; Lustig, Gila; Sigal, Alex

2017-01-01

A hallmark of pulmonary tuberculosis is the formation of macrophage-rich granulomas. These may restrict Mycobacterium tuberculosis (Mtb) growth, or progress to central necrosis and cavitation, facilitating pathogen growth. To determine factors leading to Mtb proliferation and host cell death, we used live cell imaging to track Mtb infection outcomes in individual primary human macrophages. Internalization of Mtb aggregates caused macrophage death, and phagocytosis of large aggregates was more cytotoxic than multiple small aggregates containing similar numbers of bacilli. Macrophage death did not result in clearance of Mtb. Rather, it led to accelerated intracellular Mtb growth regardless of prior activation or macrophage type. In contrast, bacillary replication was controlled in live phagocytes. Mtb grew as a clump in dead cells, and macrophages which internalized dead infected cells were very likely to die themselves, leading to a cell death cascade. This demonstrates how pathogen virulence can be achieved through numbers and aggregation states. DOI: http://dx.doi.org/10.7554/eLife.22028.001 PMID:28130921

Ebola virus host cell entry.

PubMed

Sakurai, Yasuteru

2015-01-01

Ebola virus is an enveloped virus with filamentous structure and causes a severe hemorrhagic fever in human and nonhuman primates. Host cell entry is the first essential step in the viral life cycle, which has been extensively studied as one of the therapeutic targets. A virus factor of cell entry is a surface glycoprotein (GP), which is an only essential viral protein in the step, as well as the unique particle structure. The virus also interacts with a lot of host factors to successfully enter host cells. Ebola virus at first binds to cell surface proteins and internalizes into cells, followed by trafficking through endosomal vesicles to intracellular acidic compartments. There, host proteases process GPs, which can interact with an intracellular receptor. Then, under an appropriate circumstance, viral and endosomal membranes are fused, which is enhanced by major structural changes of GPs, to complete host cell entry. Recently the basic research of Ebola virus infection mechanism has markedly progressed, largely contributed by identification of host factors and detailed structural analyses of GPs. This article highlights the mechanism of Ebola virus host cell entry, including recent findings.

Gene therapy and its implications in Periodontics

PubMed Central

Mahale, Swapna; Dani, Nitin; Ansari, Shumaila S.; Kale, Triveni

2009-01-01

Gene therapy is a field of Biomedicine. With the advent of gene therapy in dentistry, significant progress has been made in the control of periodontal diseases and reconstruction of dento-alveolar apparatus. Implementation in periodontics include: -As a mode of tissue engineering with three approaches: cell, protein-based and gene delivery approach. -Genetic approach to Biofilm Antibiotic Resistance. Future strategies of gene therapy in preventing periodontal diseases: -Enhances host defense mechanism against infection by transfecting host cells with an antimicrobial peptide protein-encoding gene. -Periodontal vaccination. Gene therapy is one of the recent entrants and its applications in the field of periodontics are reviewed in general here. PMID:20376232

Hydrogel Macroporosity and the Prolongation of Transgene Expression and the Enhancement of Angiogenesis

PubMed Central

Shepard, Jaclyn A.; Virani, Farrukh R.; Goodman, Ashley G.; Gossett, Timothy D.; Shin, Seungjin; Shea, Lonnie D.

2012-01-01

The utility of hydrogels for regenerative medicine can be improved through localized gene delivery to enhance their bioactivity. However, current systems typically lead to low-level transgene expression located in host tissue surrounding the implant. Herein, we investigated the inclusion of macropores into hydrogels to facilitate cell ingrowth and enhance gene delivery within the macropores in vivo. Macropores were created within PEG hydrogels by gelation around gelatin microspheres, with gelatin subsequently dissolved by incubation at 37°C. The macropores were interconnected, as evidenced by homogeneous cell seeding in vitro and complete cell infiltration in vivo. Lentivirus loaded within hydrogels following gelation retained its activity relative to the unencapsulated control virus. In vivo, macroporous PEG demonstrated sustained, elevated levels of transgene expression for 6 weeks, while hydrogels without macropores had transient expression. Transduced cells were located throughout the macroporous structure, while non-macroporous PEG hydrogels had transduction only in the adjacent host tissue. Delivery of lentivirus encoding for VEGF increased vascularization relative to the control, with vessels throughout the macropores of the hydrogel. The inclusion of macropores within the hydrogel to enhance cell infiltration enhances transduction and influences tissue development, which has implications for multiple regenerative medicine applications. PMID:22800542

Expanding the universe of cytokines and pattern recognition receptors: galectins and glycans in innate immunity.

PubMed

Cerliani, Juan P; Stowell, Sean R; Mascanfroni, Iván D; Arthur, Connie M; Cummings, Richard D; Rabinovich, Gabriel A

2011-02-01

Effective immunity relies on the recognition of pathogens and tumors by innate immune cells through diverse pattern recognition receptors (PRRs) that lead to initiation of signaling processes and secretion of pro- and anti-inflammatory cytokines. Galectins, a family of endogenous lectins widely expressed in infected and neoplastic tissues have emerged as part of the portfolio of soluble mediators and pattern recognition receptors responsible for eliciting and controlling innate immunity. These highly conserved glycan-binding proteins can control immune cell processes through binding to specific glycan structures on pathogens and tumors or by acting intracellularly via modulation of selective signaling pathways. Recent findings demonstrate that various galectin family members influence the fate and physiology of different innate immune cells including polymorphonuclear neutrophils, mast cells, macrophages, and dendritic cells. Moreover, several pathogens may actually utilize galectins as a mechanism of host invasion. In this review, we aim to highlight and integrate recent discoveries that have led to our current understanding of the role of galectins in host-pathogen interactions and innate immunity. Challenges for the future will embrace the rational manipulation of galectin-glycan interactions to instruct and shape innate immunity during microbial infections, inflammation, and cancer.

Predicting bacteriophage proteins located in host cell with feature selection technique.

PubMed

Ding, Hui; Liang, Zhi-Yong; Guo, Feng-Biao; Huang, Jian; Chen, Wei; Lin, Hao

2016-04-01

A bacteriophage is a virus that can infect a bacterium. The fate of an infected bacterium is determined by the bacteriophage proteins located in the host cell. Thus, reliably identifying bacteriophage proteins located in the host cell is extremely important to understand their functions and discover potential anti-bacterial drugs. Thus, in this paper, a computational method was developed to recognize bacteriophage proteins located in host cells based only on their amino acid sequences. The analysis of variance (ANOVA) combined with incremental feature selection (IFS) was proposed to optimize the feature set. Using a jackknife cross-validation, our method can discriminate between bacteriophage proteins located in a host cell and the bacteriophage proteins not located in a host cell with a maximum overall accuracy of 84.2%, and can further classify bacteriophage proteins located in host cell cytoplasm and in host cell membranes with a maximum overall accuracy of 92.4%. To enhance the value of the practical applications of the method, we built a web server called PHPred (〈http://lin.uestc.edu.cn/server/PHPred〉). We believe that the PHPred will become a powerful tool to study bacteriophage proteins located in host cells and to guide related drug discovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

Single-Cell Analysis of the Impact of Host Cell Heterogeneity on Infection with Foot-and-Mouth Disease Virus.

PubMed

Xin, Xiu; Wang, Hailong; Han, Lingling; Wang, Mingzhen; Fang, Hui; Hao, Yao; Li, Jiadai; Zhang, Hu; Zheng, Congyi; Shen, Chao

2018-05-01

Viral infection and replication are affected by host cell heterogeneity, but the mechanisms underlying the effects remain unclear. Using single-cell analysis, we investigated the effects of host cell heterogeneity, including cell size, inclusion, and cell cycle, on foot-and-mouth disease virus (FMDV) infection (acute and persistent infections) and replication. We detected various viral genome replication levels in FMDV-infected cells. Large cells and cells with a high number of inclusions generated more viral RNA copies and viral protein and a higher proportion of infectious cells than other cells. Additionally, we found that the viral titer was 10- to 100-fold higher in cells in G 2 /M than those in other cell cycle phases and identified a strong correlation between cell size, inclusion, and cell cycle heterogeneity, which all affected the infection and replication of FMDV. Furthermore, we demonstrated that host cell heterogeneity influenced the adsorption of FMDV due to differences in the levels of FMDV integrin receptors expression. Collectively, these results further our understanding of the evolution of a virus in a single host cell. IMPORTANCE It is important to understand how host cell heterogeneity affects viral infection and replication. Using single-cell analysis, we found that viral genome replication levels exhibited dramatic variability in foot-and-mouth disease virus (FMDV)-infected cells. We also found a strong correlation between heterogeneity in cell size, inclusion number, and cell cycle status and that all of these characteristics affect the infection and replication of FMDV. Moreover, we found that host cell heterogeneity influenced the viral adsorption as differences in the levels of FMDV integrin receptors' expression. This study provided new ideas for the studies of correlation between FMDV infection mechanisms and host cells. Copyright © 2018 American Society for Microbiology.

A Numerically Subdominant CD8 T Cell Response to Matrix Protein of Respiratory Syncytial Virus Controls Infection with Limited Immunopathology

PubMed Central

Liu, Jie; Haddad, Elias K.; Marceau, Joshua; Morabito, Kaitlyn M.; Rao, Srinivas S.; Filali-Mouhim, Ali; Sekaly, Rafick-Pierre; Graham, Barney S.

2016-01-01

CD8 T cells are involved in pathogen clearance and infection-induced pathology in respiratory syncytial virus (RSV) infection. Studying bulk responses masks the contribution of individual CD8 T cell subsets to protective immunity and immunopathology. In particular, the roles of subdominant responses that are potentially beneficial to the host are rarely appreciated when the focus is on magnitude instead of quality of response. Here, by evaluating CD8 T cell responses in CB6F1 hybrid mice, in which multiple epitopes are recognized, we found that a numerically subdominant CD8 T cell response against DbM187 epitope of the virus matrix protein expressed high avidity TCR and enhanced signaling pathways associated with CD8 T cell effector functions. Each DbM187 T effector cell lysed more infected targets on a per cell basis than the numerically dominant KdM282 T cells, and controlled virus replication more efficiently with less pulmonary inflammation and illness than the previously well-characterized KdM282 T cell response. Our data suggest that the clinical outcome of viral infections is determined by the integrated functional properties of a variety of responding CD8 T cells, and that the highest magnitude response may not necessarily be the best in terms of benefit to the host. Understanding how to induce highly efficient and functional T cells would inform strategies for designing vaccines intended to provide T cell-mediated immunity. PMID:26943673

Chinese hamster ovary K1 host cell enables stable cell line development for antibody molecules which are difficult to express in DUXB11-derived dihydrofolate reductase deficient host cell.

PubMed

Hu, Zhilan; Guo, Donglin; Yip, Shirley S M; Zhan, Dejin; Misaghi, Shahram; Joly, John C; Snedecor, Bradley R; Shen, Amy Y

2013-01-01

Therapeutic monoclonal antibodies (mAb) are often produced in Chinese hamster ovary (CHO) cells. Three commonly used CHO host cells for generating stable cell lines to produce therapeutic proteins are dihydrofolate reductase (DHFR) positive CHOK1, DHFR-deficient DG44, and DUXB11-based DHFR deficient CHO. Current Genentech commercial full-length antibody products have all been produced in the DUXB11-derived DHFR-deficient CHO host. However, it has been challenging to develop stable cell lines producing an appreciable amount of antibody proteins in the DUXB11-derived DHFR-deficient CHO host for some antibody molecules and the CHOK1 host has been explored as an alternative approach. In this work, stable cell lines were developed for three antibody molecules in both DUXB11-based and CHOK1 hosts. Results have shown that the best CHOK1 clones produce about 1 g/l for an antibody mAb1 and about 4 g/l for an antibody mAb2 in 14-day fed batch cultures in shake flasks. In contrast, the DUXB11-based host produced ∼0.1 g/l for both antibodies in the same 14-day fed batch shake flask production experiments. For an antibody mAb3, both CHOK1 and DUXB11 host cells can generate stable cell lines with the best clone in each host producing ∼2.5 g/l. Additionally, studies have shown that the CHOK1 host cell has a larger endoplasmic reticulum and higher mitochondrial mass. © 2013 American Institute of Chemical Engineers.

Engineering the Controlled Assembly of Filamentous Injectisomes in E. coli K-12 for Protein Translocation into Mammalian Cells.

PubMed

Ruano-Gallego, David; Álvarez, Beatriz; Fernández, Luis Ángel

2015-09-18

Bacterial pathogens containing type III protein secretion systems (T3SS) assemble large needle-like protein complexes in the bacterial envelope, called injectisomes, for translocation of protein effectors into host cells. The application of these "molecular syringes" for the injection of proteins into mammalian cells is hindered by their structural and genomic complexity, requiring multiple polypeptides encoded along with effectors in various transcriptional units (TUs) with intricate regulation. In this work, we have rationally designed the controlled expression of the filamentous injectisomes found in enteropathogenic Escherichia coli (EPEC) in the nonpathogenic strain E. coli K-12. All structural components of EPEC injectisomes, encoded in a genomic island called the locus of enterocyte effacement (LEE), were engineered in five TUs (eLEEs) excluding effectors, promoters and transcriptional regulators. These eLEEs were placed under the control of the IPTG-inducible promoter Ptac and integrated into specific chromosomal sites of E. coli K-12 using a marker-less strategy. The resulting strain, named synthetic injector E. coli (SIEC), assembles filamentous injectisomes similar to those in EPEC. SIEC injectisomes form pores in the host plasma membrane and are able to translocate T3-substrate proteins (e.g., translocated intimin receptor, Tir) into the cytoplasm of HeLa cells reproducing the phenotypes of intimate attachment and polymerization of actin-pedestals elicited by EPEC bacteria. Hence, SIEC strain allows the controlled expression of functional filamentous injectisomes for efficient translocation of proteins with T3S-signals into mammalian cells.

Glyceraldehyde 3-phosphate dehydrogenase negatively regulates human immunodeficiency virus type 1 infection

PubMed Central

2012-01-01

Background Host proteins are incorporated inside human immunodeficiency virus type 1 (HIV-1) virions during assembly and can either positively or negatively regulate HIV-1 infection. Although the identification efficiency of host proteins is improved by mass spectrometry, how those host proteins affect HIV-1 replication has not yet been fully clarified. Results In this study, we show that virion-associated glyceraldehyde 3-phosphate dehydrogenase (GAPDH) does not allosterically inactivate HIV-1 reverse transcriptase (RT) but decreases the efficiency of reverse transcription reactions by decreasing the packaging efficiency of lysyl-tRNA synthetase (LysRS) and tRNALys3 into HIV-1 virions. Two-dimensional (2D) gel electrophoresis demonstrated that some isozymes of GAPDH with different isoelectric points were expressed in HIV-1-producing CEM/LAV-1 cells, and a proportion of GAPDH was selectively incorporated into the virions. Suppression of GAPDH expression by RNA interference in CEM/LAV-1 cells resulted in decreased GAPDH packaging inside the virions, and the GAPDH-packaging-defective virus maintained at least control levels of viral production but increased the infectivity. Quantitative analysis of reverse transcription products indicated that the levels of early cDNA products of the GAPDH-packaging-defective virus were higher than those of the control virus owing to the higher packaging efficiencies of LysRS and tRNALys3 into the virions rather than the GAPDH-dependent negative allosteric modulation for RT. Furthermore, immunoprecipitation assay using an anti-GAPDH antibody showed that GAPDH directly interacted with Pr55gag and p160gag-pol and the overexpression of LysRS in HIV-1-producing cells resulted in a decrease in the efficiency of GAPDH packaging in HIV particles. In contrast, the viruses produced from cells expressing a high level of GAPDH showed decreased infectivity in TZM-bl cells and reverse transcription efficiency in TZM-bl cells and peripheral blood mononuclear cells (PBMCs). Conclusions These findings indicate that GAPDH negatively regulates HIV-1 infection and provide insights into a novel function of GAPDH in the HIV-1 life cycle and a new host defense mechanism against HIV-1 infection. PMID:23237566

Intracellular zinc flux causes reactive oxygen species mediated mitochondrial dysfunction leading to cell death in Leishmania donovani.

PubMed

Kumari, Anjali; Singh, Krishn Pratap; Mandal, Abhishek; Paswan, Ranjeet Kumar; Sinha, Preeti; Das, Pradeep; Ali, Vahab; Bimal, Sanjiva; Lal, Chandra Shekhar

2017-01-01

Leishmaniasis caused by Leishmania parasite is a global threat to public health and one of the most neglected tropical diseases. Therefore, the discovery of novel drug targets and effective drug is a major challenge and an important goal. Leishmania is an obligate intracellular parasite that alternates between sand fly and human host. To survive and establish infections, Leishmania parasites scavenge and internalize nutrients from the host. Nevertheless, host cells presents mechanism like nutrient restriction to inhibit microbial growth and control infection. Zinc is crucial for cellular growth and disruption in its homeostasis hinders growth and survival in many cells. However, little is known about the role of zinc in Leishmania growth and survival. In this study, the effect of zinc on the growth and survival of L.donovani was analyzed by both Zinc-depletion and Zinc-supplementation using Zinc-specific chelator N, N, N', N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN) and Zinc Sulfate (ZnSO4). Treatment of parasites with TPEN rather than ZnSO4 had significantly affected the growth in a dose- and time-dependent manner. The pre-treatment of promastigotes with TPEN resulted into reduced host-parasite interaction as indicated by decreased association index. Zn depletion resulted into flux in intracellular labile Zn pool and increased in ROS generation correlated with decreased intracellular total thiol and retention of plasma membrane integrity without phosphatidylserine exposure in TPEN treated promastigotes. We also observed that TPEN-induced Zn depletion resulted into collapse of mitochondrial membrane potential which is associated with increase in cytosolic calcium and cytochrome-c. DNA fragmentation analysis showed increased DNA fragments in Zn-depleted cells. In summary, intracellular Zn depletion in the L. donovani promastigotes led to ROS-mediated caspase-independent mitochondrial dysfunction resulting into apoptosis-like cell death. Therefore, cellular zinc homeostasis in Leishmania can be explored for new drug targets and chemotherapeutics to control Leishmanial growth and disease progression.

ARF6, PI3-kinase and host cell actin cytoskeleton in Toxoplasma gondii cell invasion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vieira da Silva, Claudio; Departamento de Microbiologia, Imunologia e Parasitologia, Universidade Federal de Sao Paulo, Rua Botucatu, 862, 6o andar, 04023-062 Sao Paulo, SP; Alves da Silva, Erika

2009-01-16

Toxoplasma gondii infects a variety of different cell types in a range of different hosts. Host cell invasion by T. gondii occurs by active penetration of the host cell, a process previously described as independent of host actin polymerization. Also, the parasitophorous vacuole has been shown to resist fusion with endocytic and exocytic pathways of the host cell. ADP-ribosylation factor-6 (ARF6) belongs to the ARF family of small GTP-binding proteins. ARF6 regulates membrane trafficking and actin cytoskeleton rearrangements at the plasma membrane. Here, we have observed that ARF6 is recruited to the parasitophorous vacuole of tachyzoites of T. gondii RHmore » strain and it also plays an important role in the parasite cell invasion with activation of PI3-kinase and recruitment of PIP{sub 2} and PIP{sub 3} to the parasitophorous vacuole of invading parasites. Moreover, it was verified that maintenance of host cell actin cytoskeleton integrity is important to parasite invasion.« less

Fluorescence-Activated Cell Sorting-Based Analysis Reveals an Asymmetric Induction of Interferon-Stimulated Genes in Response to Seasonal Influenza A Virus

PubMed Central

von Recum-Knepper, Jessica; Sadewasser, Anne; Weinheimer, Viola K.

2015-01-01

ABSTRACT Influenza A virus (IAV) infection provokes an antiviral response involving the expression of type I and III interferons (IFN) and IFN-stimulated genes (ISGs) in infected cell cultures. However, the spatiotemporal dynamics of the IFN reaction are incompletely understood, as previous studies investigated mainly the population responses of virus-infected cultures, although substantial cell-to-cell variability has been documented. We devised a fluorescence-activated cell sorting-based assay to simultaneously quantify expression of viral antigens and ISGs, such as ISG15, MxA, and IFIT1, in IAV-infected cell cultures at the single-cell level. This approach revealed that seasonal IAV triggers an unexpected asymmetric response, as the major cell populations expressed either viral antigen or ISG, but rarely both. Further investigations identified a role of the viral NS1 protein in blocking ISG expression in infected cells, which surprisingly did not reduce paracrine IFN signaling to noninfected cells. Interestingly, viral ISG control was impaired in cultures infected with avian-origin IAV, including the H7N9 virus from eastern China. This phenotype was traced back to polymorphic NS1 amino acids known to be important for stable binding of the polyadenylation factor CPSF30 and concomitant suppression of host cell gene expression. Most significantly, mutation of two amino acids within the CPSF30 attachment site of NS1 from seasonal IAV diminished the strict control of ISG expression in infected cells and substantially attenuated virus replication. In conclusion, our approach revealed an asymmetric, NS1-dependent ISG induction in cultures infected with seasonal IAV, which appears to be essential for efficient virus propagation. IMPORTANCE Interferons are expressed by infected cells in response to IAV infection and play important roles in the antiviral immune response by inducing hundreds of interferon-stimulated genes (ISGs). Unlike many previous studies, we investigated the ISG response at the single-cell level, enabling novel insights into this virus-host interaction. Hence, cell cultures infected with seasonal IAV displayed an asymmetric ISG induction that was confined almost exclusively to noninfected cells. In comparison, ISG expression was observed in larger cell populations infected with avian-origin IAV, suggesting a more resolute antiviral response to these strains. Strict control of ISG expression by seasonal IAV was explained by the binding of the viral NS1 protein to the polyadenylation factor CPSF30, which reduces host cell gene expression. Mutational disruption of CPSF30 binding within NS1 concomitantly attenuated ISG control and replication of seasonal IAV, illustrating the importance of maintaining an asymmetric ISG response for efficient virus propagation. PMID:25903337

A history of studies that examine the interactions of Toxoplasma with its host cell: Emphasis on in vitro models.

PubMed

Boyle, Jon P; Radke, Jay R

2009-07-01

This review is a historical look at work carried out over the past 50 years examining interactions of Toxoplasma with the host cell and attempts to focus on some of the seminal experiments in the field. This early work formed the foundation for more recent studies aimed at identifying the host and parasite factors mediating key Toxoplasma-host cell interactions. We focus especially on those studies that were performed in vitro and provide discussions of the following general areas: (i) establishment of the parasitophorous vacuole, (ii) the requirement of specific host cell molecules for parasite replication, (iii) the scenarios under which the host cell can resist parasite replication and/or persistence, (iv) host species-specific and host strain-specific responses to Toxoplasma infection, and (v) Toxoplasma-induced immune modulation.

Suppressors for Human Epidermal Growth Factor Receptor 2/4 (HER2/4): A New Family of Anti-Toxoplasmic Agents in ARPE-19 Cells

PubMed Central

Kim, Yeong Hoon; Bhatt, Lokraj; Ahn, Hye-Jin; Yang, Zhaoshou; Lee, Won-Kyu; Nam, Ho-Woo

2017-01-01

The effects of tyrosine kinase inhibitors (TKIs) were evaluated on growth inhibition of intracellular Toxoplasma gondii in host ARPE-19 cells. The number of tachyzoites per parasitophorous vacuolar membrane (PVM) was counted after treatment with TKIs. T. gondii protein expression was assessed by western blot. Immunofluorescence assay was performed using Programmed Cell Death 4 (PDCD4) and T. gondii GRA3 antibodies. The TKIs were divided into 3 groups; non-epidermal growth factor receptor (non-EGFR), anti-human EGFR 2 (anti-HER2), and anti-HER2/4 TKIs, respectively. Group I TKIs (nintedanib, AZD9291, and sunitinib) were unable to inhibit proliferation without destroying host cells. Group II TKIs (lapatinib, gefitinib, erlotinib, and AG1478) inhibited proliferation up to 98% equivalent to control pyrimethamine (5 μM) at 20 μM and higher, without affecting host cells. Group III TKIs (neratinib, dacomitinib, afatinib, and pelitinib) inhibited proliferation up to 98% equivalent to pyrimethamine at 1–5 μM, but host cells were destroyed at 10–20 μM. In Group I, TgHSP90 and SAG1 inhibitions were weak, and GRA3 expression was moderately inhibited. In Group II, TgHSP90 and SAG1 expressions seemed to be slightly enhanced, while GRA3 showed none to mild inhibition; however, AG1478 inhibited all proteins moderately. Protein expression was blocked in Group III, comparable to pyrimethamine. PDCD4 and GRA3 were well localized inside the nuclei in Group I, mildly disrupted in Group II, and were completely disrupted in Group III. This study suggests the possibility of a vital T. gondii TK having potential HER2/4 properties, thus anti-HER2/4 TKIs may inhibit intracellular parasite proliferation with minimal adverse effects on host cells. PMID:29103264

Suppressors for Human Epidermal Growth Factor Receptor 2/4 (HER2/4): A New Family of Anti-Toxoplasmic Agents in ARPE-19 Cells.

PubMed

Kim, Yeong Hoon; Bhatt, Lokraj; Ahn, Hye-Jin; Yang, Zhaoshou; Lee, Won-Kyu; Nam, Ho-Woo

2017-10-01

The effects of tyrosine kinase inhibitors (TKIs) were evaluated on growth inhibition of intracellular Toxoplasma gondii in host ARPE-19 cells. The number of tachyzoites per parasitophorous vacuolar membrane (PVM) was counted after treatment with TKIs. T. gondii protein expression was assessed by western blot. Immunofluorescence assay was performed using Programmed Cell Death 4 (PDCD4) and T. gondii GRA3 antibodies. The TKIs were divided into 3 groups; non-epidermal growth factor receptor (non-EGFR), anti-human EGFR 2 (anti-HER2), and anti-HER2/4 TKIs, respectively. Group I TKIs (nintedanib, AZD9291, and sunitinib) were unable to inhibit proliferation without destroying host cells. Group II TKIs (lapatinib, gefitinib, erlotinib, and AG1478) inhibited proliferation up to 98% equivalent to control pyrimethamine (5 μM) at 20 μM and higher, without affecting host cells. Group III TKIs (neratinib, dacomitinib, afatinib, and pelitinib) inhibited proliferation up to 98% equivalent to pyrimethamine at 1-5 μM, but host cells were destroyed at 10-20 μM. In Group I, TgHSP90 and SAG1 inhibitions were weak, and GRA3 expression was moderately inhibited. In Group II, TgHSP90 and SAG1 expressions seemed to be slightly enhanced, while GRA3 showed none to mild inhibition; however, AG1478 inhibited all proteins moderately. Protein expression was blocked in Group III, comparable to pyrimethamine. PDCD4 and GRA3 were well localized inside the nuclei in Group I, mildly disrupted in Group II, and were completely disrupted in Group III. This study suggests the possibility of a vital T. gondii TK having potential HER2/4 properties, thus anti-HER2/4 TKIs may inhibit intracellular parasite proliferation with minimal adverse effects on host cells.

Nuclear translocation of Acinetobacter baumannii transposase induces DNA methylation of CpG regions in the promoters of E-cadherin gene.

PubMed

Moon, Dong Chan; Choi, Chul Hee; Lee, Su Man; Lee, Jung Hwa; Kim, Seung Il; Kim, Dong Sun; Lee, Je Chul

2012-01-01

Nuclear targeting of bacterial proteins has emerged as a pathogenic mechanism whereby bacterial proteins induce host cell pathology. In this study, we examined nuclear targeting of Acinetobacter baumannii transposase (Tnp) and subsequent epigenetic changes in host cells. Tnp of A. baumannii ATCC 17978 possesses nuclear localization signals (NLSs), (225)RKRKRK(230). Transient expression of A. baumannii Tnp fused with green fluorescent protein (GFP) resulted in the nuclear localization of these proteins in COS-7 cells, whereas the truncated Tnp without NLSs fused with GFP were exclusively localized in the cytoplasm. A. baumannii Tnp was found in outer membrane vesicles, which delivered this protein to the nucleus of host cells. Nuclear expression of A. baumannii Tnp fused with GFP in A549 cells induced DNA methylation of CpG regions in the promoters of E-cadherin (CDH1) gene, whereas the cytoplasmic localization of the truncated Tnp without NLSs fused with GFP did not induce DNA methylation. DNA methylation in the promoters of E-cadherin gene induced by nuclear targeting of A. baumannii Tnp resulted in down-regulation of gene expression. In conclusion, our data show that nuclear traffic of A. baumannii Tnp induces DNA methylation of CpG regions in the promoters of E-cadherin gene, which subsequently down-regulates gene expression. This study provides a new insight into the epigenetic control of host genes by bacterial proteins.

Human T-lymphotropic virus type 1-infected cells secrete exosomes that contain Tax protein.

PubMed

Jaworski, Elizabeth; Narayanan, Aarthi; Van Duyne, Rachel; Shabbeer-Meyering, Shabana; Iordanskiy, Sergey; Saifuddin, Mohammed; Das, Ravi; Afonso, Philippe V; Sampey, Gavin C; Chung, Myung; Popratiloff, Anastas; Shrestha, Bindesh; Sehgal, Mohit; Jain, Pooja; Vertes, Akos; Mahieux, Renaud; Kashanchi, Fatah

2014-08-08

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. The HTLV-1 transactivator protein Tax controls many critical cellular pathways, including host cell DNA damage response mechanisms, cell cycle progression, and apoptosis. Extracellular vesicles called exosomes play critical roles during pathogenic viral infections as delivery vehicles for host and viral components, including proteins, mRNA, and microRNA. We hypothesized that exosomes derived from HTLV-1-infected cells contain unique host and viral proteins that may contribute to HTLV-1-induced pathogenesis. We found exosomes derived from infected cells to contain Tax protein and proinflammatory mediators as well as viral mRNA transcripts, including Tax, HBZ, and Env. Furthermore, we observed that exosomes released from HTLV-1-infected Tax-expressing cells contributed to enhanced survival of exosome-recipient cells when treated with Fas antibody. This survival was cFLIP-dependent, with Tax showing induction of NF-κB in exosome-recipient cells. Finally, IL-2-dependent CTLL-2 cells that received Tax-containing exosomes were protected from apoptosis through activation of AKT. Similar experiments with primary cultures showed protection and survival of peripheral blood mononuclear cells even in the absence of phytohemagglutinin/IL-2. Surviving cells contained more phosphorylated Rb, consistent with the role of Tax in regulation of the cell cycle. Collectively, these results suggest that exosomes may play an important role in extracellular delivery of functional HTLV-1 proteins and mRNA to recipient cells. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

Human T-lymphotropic Virus Type 1-infected Cells Secrete Exosomes That Contain Tax Protein*

PubMed Central

Jaworski, Elizabeth; Narayanan, Aarthi; Van Duyne, Rachel; Shabbeer-Meyering, Shabana; Iordanskiy, Sergey; Saifuddin, Mohammed; Das, Ravi; Afonso, Philippe V.; Sampey, Gavin C.; Chung, Myung; Popratiloff, Anastas; Shrestha, Bindesh; Sehgal, Mohit; Jain, Pooja; Vertes, Akos; Mahieux, Renaud; Kashanchi, Fatah

2014-01-01

Human T-lymphotropic virus type 1 (HTLV-1) is the causative agent of adult T-cell leukemia and HTLV-1-associated myelopathy/tropical spastic paraparesis. The HTLV-1 transactivator protein Tax controls many critical cellular pathways, including host cell DNA damage response mechanisms, cell cycle progression, and apoptosis. Extracellular vesicles called exosomes play critical roles during pathogenic viral infections as delivery vehicles for host and viral components, including proteins, mRNA, and microRNA. We hypothesized that exosomes derived from HTLV-1-infected cells contain unique host and viral proteins that may contribute to HTLV-1-induced pathogenesis. We found exosomes derived from infected cells to contain Tax protein and proinflammatory mediators as well as viral mRNA transcripts, including Tax, HBZ, and Env. Furthermore, we observed that exosomes released from HTLV-1-infected Tax-expressing cells contributed to enhanced survival of exosome-recipient cells when treated with Fas antibody. This survival was cFLIP-dependent, with Tax showing induction of NF-κB in exosome-recipient cells. Finally, IL-2-dependent CTLL-2 cells that received Tax-containing exosomes were protected from apoptosis through activation of AKT. Similar experiments with primary cultures showed protection and survival of peripheral blood mononuclear cells even in the absence of phytohemagglutinin/IL-2. Surviving cells contained more phosphorylated Rb, consistent with the role of Tax in regulation of the cell cycle. Collectively, these results suggest that exosomes may play an important role in extracellular delivery of functional HTLV-1 proteins and mRNA to recipient cells. PMID:24939845

Host Serine/Threonine Kinases mTOR and Protein Kinase C-α Promote InlB-Mediated Entry of Listeria monocytogenes

PubMed Central

Bhalla, Manmeet; Law, Daria; Dowd, Georgina C.

2017-01-01

ABSTRACT The bacterial pathogen Listeria monocytogenes causes foodborne illnesses resulting in gastroenteritis, meningitis, or abortion. Listeria induces its internalization into some human cells through interaction of the bacterial surface protein InlB with the host receptor tyrosine kinase Met. InlB-dependent entry requires localized polymerization of the host actin cytoskeleton. The signal transduction pathways that act downstream of Met to regulate actin filament assembly or other processes during Listeria uptake remain incompletely characterized. Here, we demonstrate important roles for the human serine/threonine kinases mTOR and protein kinase C-α (PKC-α) in InlB-dependent entry. Experiments involving RNA interference (RNAi) indicated that two multiprotein complexes containing mTOR, mTORC1 and mTORC2, are each needed for efficient internalization of Listeria into cells of the human cell line HeLa. InlB stimulated Met-dependent phosphorylation of mTORC1 or mTORC2 substrates, demonstrating activation of both mTOR-containing complexes. RNAi studies indicated that the mTORC1 effectors 4E-BP1 and hypoxia-inducible factor 1α (HIF-1α) and the mTORC2 substrate PKC-α each control Listeria uptake. Genetic or pharmacological inhibition of PKC-α reduced the internalization of Listeria and the accumulation of actin filaments that normally accompanies InlB-mediated entry. Collectively, our results identify mTOR and PKC-α to be host factors exploited by Listeria to promote infection. PKC-α controls Listeria entry, at least in part, by regulating the actin cytoskeleton downstream of the Met receptor. PMID:28461391

Characterization of Amoeboaphelidium protococcarum, an Algal Parasite New to the Cryptomycota Isolated from an Outdoor Algal Pond Used for the Production of Biofuel

PubMed Central

Letcher, Peter M.; Lopez, Salvador; Schmieder, Robert; Lee, Philip A.; Behnke, Craig; Powell, Martha J.; McBride, Robert C.

2013-01-01

Mass culture of algae for the production of biofuels is a developing technology designed to offset the depletion of fossil fuel reserves. However, large scale culture of algae in open ponds can be challenging because of incidences of infestation with algal parasites. Without knowledge of the identity of the specific parasite and how to control these pests, algal-based biofuel production will be limited. We have characterized a eukaryotic parasite of Scenedesmus dimorphus growing in outdoor ponds used for biofuel production. We demonstrated that as the genomic DNA of parasite FD01 increases, the concentration of S. dimorphus cells decreases; consequently, this is a highly destructive pathogen. Techniques for culture of the parasite and host were developed, and the endoparasite was identified as the Aphelidea, Amoeboaphelidium protococcarum. Phylogenetic analysis of ribosomal sequences revealed that parasite FD01 placed within the recently described Cryptomycota, a poorly known phylum based on two species of Rozella and environmental samples. Transmission electron microscopy demonstrated that aplanospores of the parasite produced filose pseudopodia, which contained fine fibers the diameter of actin microfilaments. Multiple lipid globules clustered and were associated with microbodies, mitochondria and a membrane cisternae, an arrangement characteristic of the microbody-lipid globule complex of chytrid zoospores. After encystment and attachment to the host cells, the parasite injected its protoplast into the host between the host cell wall and plasma membrane. At maturity the unwalled parasite occupied the entire host cell. After cleavage of the protoplast into aplanospores, a vacuole and lipids remained in the host cell. Amoeboaphelidium protococcarum isolate FD01 is characteristic of the original description of this species and is different from strain X-5 recently characterized. Our results help put a face on the Cryptomycota, revealing that the phylum is more diverse than previously understood and include some of the Aphelidea as well as Rozella species and potentially Microsporidia. PMID:23437098

The microbiota metabolite indole inhibits Salmonella virulence: Involvement of the PhoPQ two-component system.

PubMed

Kohli, Nandita; Crisp, Zeni; Riordan, Rebekah; Li, Michael; Alaniz, Robert C; Jayaraman, Arul

2018-01-01

The microbial community present in the gastrointestinal tract is an important component of the host defense against pathogen infections. We previously demonstrated that indole, a microbial metabolite of tryptophan, reduces enterohemorrhagic Escherichia coli O157:H7 attachment to intestinal epithelial cells and biofilm formation, suggesting that indole may be an effector/attenuator of colonization for a number of enteric pathogens. Here, we report that indole attenuates Salmonella Typhimurium (Salmonella) virulence and invasion as well as increases resistance to colonization in host cells. Indole-exposed Salmonella colonized mice less effectively compared to solvent-treated controls, as evident by competitive index values less than 1 in multiple organs. Indole-exposed Salmonella demonstrated 160-fold less invasion of HeLa epithelial cells and 2-fold less invasion of J774A.1 macrophages compared to solvent-treated controls. However, indole did not affect Salmonella intracellular survival in J774A.1 macrophages suggesting that indole primarily affects Salmonella invasion. The decrease in invasion was corroborated by a decrease in expression of multiple Salmonella Pathogenicity Island-1 (SPI-1) genes. We also identified that the effect of indole was mediated by both PhoPQ-dependent and independent mechanisms. Indole also synergistically enhanced the inhibitory effect of a short chain fatty acid cocktail on SPI-1 gene expression. Lastly, indole-treated HeLa cells were 70% more resistant to Salmonella invasion suggesting that indole also increases resistance of epithelial cells to colonization. Our results demonstrate that indole is an important microbiota metabolite that has direct anti-infective effects on Salmonella and host cells, revealing novel mechanisms of pathogen colonization resistance.

The microbiota metabolite indole inhibits Salmonella virulence: Involvement of the PhoPQ two-component system

PubMed Central

Kohli, Nandita; Crisp, Zeni; Riordan, Rebekah; Li, Michael; Alaniz, Robert C.

2018-01-01

The microbial community present in the gastrointestinal tract is an important component of the host defense against pathogen infections. We previously demonstrated that indole, a microbial metabolite of tryptophan, reduces enterohemorrhagic Escherichia coli O157:H7 attachment to intestinal epithelial cells and biofilm formation, suggesting that indole may be an effector/attenuator of colonization for a number of enteric pathogens. Here, we report that indole attenuates Salmonella Typhimurium (Salmonella) virulence and invasion as well as increases resistance to colonization in host cells. Indole-exposed Salmonella colonized mice less effectively compared to solvent-treated controls, as evident by competitive index values less than 1 in multiple organs. Indole-exposed Salmonella demonstrated 160-fold less invasion of HeLa epithelial cells and 2-fold less invasion of J774A.1 macrophages compared to solvent-treated controls. However, indole did not affect Salmonella intracellular survival in J774A.1 macrophages suggesting that indole primarily affects Salmonella invasion. The decrease in invasion was corroborated by a decrease in expression of multiple Salmonella Pathogenicity Island-1 (SPI-1) genes. We also identified that the effect of indole was mediated by both PhoPQ-dependent and independent mechanisms. Indole also synergistically enhanced the inhibitory effect of a short chain fatty acid cocktail on SPI-1 gene expression. Lastly, indole-treated HeLa cells were 70% more resistant to Salmonella invasion suggesting that indole also increases resistance of epithelial cells to colonization. Our results demonstrate that indole is an important microbiota metabolite that has direct anti-infective effects on Salmonella and host cells, revealing novel mechanisms of pathogen colonization resistance. PMID:29342189

Programming mRNA decay to modulate synthetic circuit resource allocation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Venturelli, Ophelia S.; Tei, Mika; Bauer, Stefan

Synthetic circuits embedded in host cells compete with cellular processes for limited intracellular resources. Here we show how funnelling of cellular resources, after global transcriptome degradation by the sequence-dependent endoribonuclease MazF, to a synthetic circuit can increase production. Target genes are protected from MazF activity by recoding the gene sequence to eliminate recognition sites, while preserving the amino acid sequence. The expression of a protected fluorescent reporter and flux of a high-value metabolite are significantly enhanced using this genome-scale control strategy. Proteomics measurements discover a host factor in need of protection to improve resource redistribution activity. A computational model demonstratesmore » that the MazF mRNA-decay feedback loop enables proportional control of MazF in an optimal operating regime. Transcriptional profiling of MazF-induced cells elucidates the dynamic shifts in transcript abundance and discovers regulatory design elements. Altogether, our results suggest that manipulation of cellular resource allocation is a key control parameter for synthetic circuit design.« less

Programming mRNA decay to modulate synthetic circuit resource allocation

DOE PAGES

Venturelli, Ophelia S.; Tei, Mika; Bauer, Stefan; ...

2017-04-26

Synthetic circuits embedded in host cells compete with cellular processes for limited intracellular resources. Here we show how funnelling of cellular resources, after global transcriptome degradation by the sequence-dependent endoribonuclease MazF, to a synthetic circuit can increase production. Target genes are protected from MazF activity by recoding the gene sequence to eliminate recognition sites, while preserving the amino acid sequence. The expression of a protected fluorescent reporter and flux of a high-value metabolite are significantly enhanced using this genome-scale control strategy. Proteomics measurements discover a host factor in need of protection to improve resource redistribution activity. A computational model demonstratesmore » that the MazF mRNA-decay feedback loop enables proportional control of MazF in an optimal operating regime. Transcriptional profiling of MazF-induced cells elucidates the dynamic shifts in transcript abundance and discovers regulatory design elements. Altogether, our results suggest that manipulation of cellular resource allocation is a key control parameter for synthetic circuit design.« less

Recent Insights into the Control of Human Papillomavirus (HPV) Genome Stability, Loss, and Degradation.

PubMed

Fisher, Chris

2015-01-01

Most human papillomavirus (HPV) antiviral strategies have focused upon inhibiting viral DNA replication, but it is increasingly apparent that viral DNA levels can be chemically controlled by approaches that promote its instability. HPVs and other DNA viruses have a tenuous relationship with their hosts. They must replicate and hide from the DNA damage response (DDR) and innate immune systems, which serve to protect cells from foreign or "non-self" DNA, and yet they draft these same systems to support their life cycles. DNA binding antiviral agents promoting massive viral DNA instability and elimination are reviewed. Mechanistic studies of these agents have identified genetic antiviral enhancers and repressors, antiviral sensitizers, and host cell elements that protect and stabilize HPV genomes. Viral DNA degradation appears to be an important means of controlling HPV DNA levels in some cases, but the underlying mechanisms remain poorly understood. These findings may prove useful not only for understanding viral DNA persistence but also in devising future antiviral strategies.

The cGAS/STING Pathway Is Important for Dendritic Cell Activation but Is Not Essential to Induce Protective Immunity against Mycobacterium tuberculosis Infection.

PubMed

Marinho, Fabio V; Benmerzoug, Sulayman; Rose, Stephanie; Campos, Priscila C; Marques, João T; Báfica, André; Barber, Glen; Ryffel, Bernhard; Oliveira, Sergio C; Quesniaux, Valerie F J

2018-05-23

Mycobacterium tuberculosis (Mtb) infection remains a major public health concern. The STING (stimulator of interferon genes) pathway contributes to the cytosolic surveillance of host cells. Most studies on the role of STING activation in Mtb infection have focused on macrophages. Moreover, a detailed investigation of the role of STING during Mtb infection in vivo is required. Here, we deciphered the involvement of STING in the activation of dendritic cells (DCs) and the host response to Mtb infection in vivo. In DCs, this adaptor molecule was important for Ifn-β expression and IL-12 production as well as for the surface expression of the activation markers CD40 and CD86. We also documented that Mtb DNA induces STING activation in murine fibroblasts. In vivo Mtb aerogenic infection induced the upregulation of the STING and cGAS (cyclic GMP-AMP synthase) genes, and Ifn-β pulmonary expression was dependent on both sensors. However, mice deficient for STING or cGAS presented a similar outcome to wild-type controls, with no major alterations in body weight gain, bacterial burden, or survival. Lung inflammation, proinflammatory cytokine production, and inflammatory cell recruitment were similar in STING- and cGAS-deficient mice compared to wild-type controls. In summary, although the STING pathway seems to be crucial for DC activation during Mtb infection, it is dispensable for host protection in vivo. © 2018 S. Karger AG, Basel.

Implanted Cell-Dense Prevascularized Tissues Develop Functional Vasculature That Supports Reoxygenation After Thrombosis

PubMed Central

White, Sean M.; Pittman, Chelsea R.; Hingorani, Ryan; Arora, Rajan; Esipova, Tatiana V.; Vinogradov, Sergei A.; Hughes, Christopher C.W.; Choi, Bernard

2014-01-01

Achieving adequate vascularization within implanted engineered tissues is a significant obstacle to maintaining viability and functionality. In vitro prevascularization of engineered tissues has been explored as a potential solution to this challenge. The traditional paradigm of in vitro prevascularization is to implant an engineered tissue with a preformed vascular network that is perfused after anastomosis with the host circulation. We investigated the efficacy of this strategy by implanting cell-dense prevascularized tissues created via cell-mediated contraction and composed of collagen and a collagen-fibrin mixture into dorsal window chambers surgically prepared on immunocompromised mice. We found that host-implant anastomosis takes place in 2–6 days and that perfusion of vessels within the implants is subsequently restricted by thrombosis. However, by day 7, a functional vascular network composed of host and implant vessels developed. Prevascularization enhanced intra-implant pO2 significantly as early as 2 days postimplantation, reaching a maximum of 55 mmHg by day 8, which was significantly greater than the maximum within cellularized control tissues (18 mmHg). By day 14, collagen tissues supported ∼0.51×109 implanted and host-derived cells per mL. Our findings elucidate key features of in vitro prevascularization that can be used toward the design of larger and more functionally complex engineered tissues. PMID:24593148

Pathogenesis of human papillomavirus-associated mucosal disease.

PubMed

Groves, Ian J; Coleman, Nicholas

2015-03-01

Human papillomaviruses (HPVs) are a necessary cause of carcinoma of the cervix and other mucosal epithelia. Key events in high-risk HPV (HRHPV)-associated neoplastic progression include persistent infection, deregulated expression of virus early genes in basal epithelial cells and genomic instability causing secondary host genomic imbalances. There are multiple mechanisms by which deregulated virus early gene expression may be achieved. Integration of virus DNA into host chromosomes is observed in the majority of cervical squamous cell carcinomas (SCCs), although in ∼15% of cases the virus remains extrachromosomal (episomal). Interestingly, not all integration events provide a growth advantage to basal cervical epithelial cells or lead to increased levels of the virus oncogenes E6 and E7, when compared with episome-containing basal cells. The factors that provide a competitive advantage to some integrants, but not others, are complex and include virus and host contributions. Gene expression from integrated and episomal HRHPV is regulated through host epigenetic mechanisms affecting the virus long control region (LCR), which appear to be of functional importance. New approaches to treating HRHPV-associated mucosal neoplasia include knockout of integrated HRHPV DNA, depletion of virus transcripts and inhibition of virus early gene transcription through targeting or use of epigenetic modifiers. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. Copyright © 2014 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Dengue Virus Selectively Annexes Endoplasmic Reticulum-Associated Translation Machinery as a Strategy for Co-opting Host Cell Protein Synthesis.

PubMed

Reid, David W; Campos, Rafael K; Child, Jessica R; Zheng, Tianli; Chan, Kitti Wing Ki; Bradrick, Shelton S; Vasudevan, Subhash G; Garcia-Blanco, Mariano A; Nicchitta, Christopher V

2018-04-01

A primary question in dengue virus (DENV) biology is the molecular strategy for recruitment of host cell protein synthesis machinery. Here, we combined cell fractionation, ribosome profiling, and transcriptome sequencing (RNA-seq) to investigate the subcellular organization of viral genome translation and replication as well as host cell translation and its response to DENV infection. We report that throughout the viral life cycle, DENV plus- and minus-strand RNAs were highly partitioned to the endoplasmic reticulum (ER), identifying the ER as the primary site of DENV translation. DENV infection was accompanied by an ER compartment-specific remodeling of translation, where ER translation capacity was subverted from host transcripts to DENV plus-strand RNA, particularly at late stages of infection. Remarkably, translation levels and patterns in the cytosol compartment were only modestly affected throughout the experimental time course of infection. Comparisons of ribosome footprinting densities of the DENV plus-strand RNA and host mRNAs indicated that DENV plus-strand RNA was only sparsely loaded with ribosomes. Combined, these observations suggest a mechanism where ER-localized translation and translational control mechanisms, likely cis encoded, are used to repurpose the ER for DENV virion production. Consistent with this view, we found ER-linked cellular stress response pathways commonly associated with viral infection, namely, the interferon response and unfolded protein response, to be only modestly activated during DENV infection. These data support a model where DENV reprograms the ER protein synthesis and processing environment to promote viral survival and replication while minimizing the activation of antiviral and proteostatic stress response pathways. IMPORTANCE DENV, a prominent human health threat with no broadly effective or specific treatment, depends on host cell translation machinery for viral replication, immune evasion, and virion biogenesis. The molecular mechanism by which DENV commandeers the host cell protein synthesis machinery and the subcellular organization of DENV replication and viral protein synthesis is poorly understood. Here, we report that DENV has an almost exclusively ER-localized life cycle, with viral replication and translation largely restricted to the ER. Surprisingly, DENV infection largely affects only ER-associated translation, with relatively modest effects on host cell translation in the cytosol. DENV RNA translation is very inefficient, likely representing a strategy to minimize disruption of ER proteostasis. Overall these findings demonstrate that DENV has evolved an ER-compartmentalized life cycle; thus, targeting the molecular signatures and regulation of the DENV-ER interaction landscape may reveal strategies for therapeutic intervention. Copyright © 2018 American Society for Microbiology.

Enhanced resistance in Theobroma cacao against oomycete and fungal pathogens by secretion of phosphatidylinositol-3-phosphate-binding proteins

USDA-ARS?s Scientific Manuscript database

The internalization of oomycete and fungal pathogen effectors into host plant cells has been reported to be blocked by proteins that bind to the effectors’ cell entry receptor, phosphatidylinositol-3-phosphate (PI3P). This finding suggested a novel strategy for disease control by engineering plants ...

Periodontal cell implantation contributes to the regeneration of the periodontium in an indirect way.

PubMed

Yu, Na; Bronckers, Antonius L J J; Oortgiesen, Daniel A W; Yan, Xiangzhen; Jansen, John A; Yang, Fang; Walboomers, X Frank

2015-01-01

Periodontitis is the most common human infectious disease. Regeneration of bone and soft tissue defects after periodontitis remains challenging, although the transplantation of periodontal ligament (PDL) cells seems a liable strategy. However, little is known about the function of PDL cells after transplantation. In the current study, a combination of in vitro coculture systems and in vivo immunohistochemistry (IHC) was used to investigate the role of PDL cells in the regenerative process. First, a coculture method was used, in which mesenchymal cells (representing the host tissue) were brought into direct contact with PDL cells (representing the transplanted cell population). It was found that PDL cells significantly increased mineralized matrix formation and osteocalcin expression, whereas control cells did not. Similar results were obtained when a noncontact coculture system was applied separating PDL and mesenchymal cells. In an in vivo rat model, regeneration of alveolar bone and ligament was seen after PDL cell transplantation. Implanted PDL cells were found clustered along the newly formed tissues. IHC showed enhanced osteopontin expression and gap junction staining in areas neighboring implanted PDL cells. In conclusion, PDL cells enhance periodontal regeneration through a trophic factor stimulating the osteogenic activity of the surrounding host cells.

The Role of Secretory Immunoglobulin A in the Natural Sensing of Commensal Bacteria by Mouse Peyer's Patch Dendritic Cells*

PubMed Central

Rol, Nicolas; Favre, Laurent; Benyacoub, Jalil; Corthésy, Blaise

2012-01-01

The mammalian gastrointestinal (GI) tract harbors a diverse population of commensal species collectively known as the microbiota, which interact continuously with the host. From very early in life, secretory IgA (SIgA) is found in association with intestinal bacteria. It is considered that this helps to ensure self-limiting growth of the microbiota and hence participates in symbiosis. However, the importance of this association in contributing to the mechanisms ensuring natural host-microorganism communication is in need of further investigation. In the present work, we examined the possible role of SIgA in the transport of commensal bacteria across the GI epithelium. Using an intestinal loop mouse model and fluorescently labeled bacteria, we found that entry of commensal bacteria in Peyer's patches (PP) via the M cell pathway was mediated by their association with SIgA. Preassociation of bacteria with nonspecific SIgA increased their dynamics of entry and restored the reduced transport observed in germ-free mice known to have a marked reduction in intestinal SIgA production. Selective SIgA-mediated targeting of bacteria is restricted to the tolerogenic CD11c+CD11b+CD8− dendritic cell subset located in the subepithelial dome region of PPs, confirming that the host is not ignorant of its resident commensals. In conclusion, our work supports the concept that SIgA-mediated monitoring of commensal bacteria targeting dendritic cells in the subepithelial dome region of PPs represents a mechanism whereby the host mucosal immune system controls the continuous dialogue between the host and commensal bacteria. PMID:23027876

Cell Biology: Control of Partner Lifetime in a Plant-Fungus Relationship.

PubMed

Gutjahr, Caroline; Parniske, Martin

2017-06-05

Arbuscules are tree-shaped fungal structures inside plant root cells that facilitate the exchange of nutrients delivered by the fungus with carbon sources from the host. To maintain symbiotic efficiency, plant cells can trigger degeneration of underperforming arbuscules. A recent study reveals the first transcription factor, which induces genes encoding hydrolytic enzymes, to mediate arbuscule degeneration. Copyright © 2017 Elsevier Ltd. All rights reserved.

Host cell subversion by Toxoplasma GRA16, an exported dense granule protein that targets the host cell nucleus and alters gene expression.

PubMed

Bougdour, Alexandre; Durandau, Eric; Brenier-Pinchart, Marie-Pierre; Ortet, Philippe; Barakat, Mohamed; Kieffer, Sylvie; Curt-Varesano, Aurélie; Curt-Bertini, Rose-Laurence; Bastien, Olivier; Coute, Yohann; Pelloux, Hervé; Hakimi, Mohamed-Ali

2013-04-17

After invading host cells, Toxoplasma gondii multiplies within a parasitophorous vacuole (PV) that is maintained by parasite proteins secreted from organelles called dense granules. Most dense granule proteins remain within the PV, and few are known to access the host cell cytosol. We identify GRA16 as a dense granule protein that is exported through the PV membrane and reaches the host cell nucleus, where it positively modulates genes involved in cell-cycle progression and the p53 tumor suppressor pathway. GRA16 binds two host enzymes, the deubiquitinase HAUSP and PP2A phosphatase, which exert several functions, including regulation of p53 and the cell cycle. GRA16 alters p53 levels in a HAUSP-dependent manner and induces nuclear translocation of the PP2A holoenzyme. Additionally, certain GRA16-deficient strains exhibit attenuated virulence, indicating the importance of these host alterations in pathogenesis. Therefore, GRA16 represents a potentially emerging subfamily of exported dense granule proteins that modulate host function. Copyright © 2013 Elsevier Inc. All rights reserved.

Evolution of Salmonella-Host Cell Interactions through a Dynamic Bacterial Genome

PubMed Central

Ilyas, Bushra; Tsai, Caressa N.; Coombes, Brian K.

2017-01-01

Salmonella Typhimurium has a broad arsenal of genes that are tightly regulated and coordinated to facilitate adaptation to the various host environments it colonizes. The genome of Salmonella Typhimurium has undergone multiple gene acquisition events and has accrued changes in non-coding DNA that have undergone selection by regulatory evolution. Together, at least 17 horizontally acquired pathogenicity islands (SPIs), prophage-associated genes, and changes in core genome regulation contribute to the virulence program of Salmonella. Here, we review the latest understanding of these elements and their contributions to pathogenesis, emphasizing the regulatory circuitry that controls niche-specific gene expression. In addition to an overview of the importance of SPI-1 and SPI-2 to host invasion and colonization, we describe the recently characterized contributions of other SPIs, including the antibacterial activity of SPI-6 and adhesion and invasion mediated by SPI-4. We further discuss how these fitness traits have been integrated into the regulatory circuitry of the bacterial cell through cis-regulatory evolution and by a careful balance of silencing and counter-silencing by regulatory proteins. Detailed understanding of regulatory evolution within Salmonella is uncovering novel aspects of infection biology that relate to host-pathogen interactions and evasion of host immunity. PMID:29034217

Recombinant glucose uptake system

DOEpatents

Ingrahm, Lonnie O.; Snoep, Jacob L.; Arfman, Nico

1997-01-01

Recombinant organisms are disclosed that contain a pathway for glucose uptake other than the pathway normally utilized by the host cell. In particular, the host cell is one in which glucose transport into the cell normally is coupled to PEP production. This host cell is transformed so that it uses an alternative pathway for glucose transport that is not coupled to PEP production. In a preferred embodiment, the host cell is a bacterium other than Z. mobilis that has been transformed to contain the glf and glk genes of Z. mobilis. By uncoupling glucose transport into the cell from PEP utilization, more PEP is produced for synthesis of products of commercial importance from a given quantity of biomass supplied to the host cells.

Sialoglycoproteins in morphological distinct stages of Mucor polymorphosporus and their influence on phagocytosis by human blood phagocytes.

PubMed

Almeida, Catia Amancio; de Campos-Takaki, Galba Maria; Portela, Maristela Barbosa; Travassos, Luiz R; Alviano, Celuta Sales; Alviano, Daniela Sales

2013-10-01

The possible role of sialic acids in host cells-fungi interaction and their association with glycoproteins were evaluated using a clinical isolate of the dimorphic fungus Mucor polymorphosporus. Lectin-binding assays with spores and yeast cells denoted the presence of surface sialoglycoconjugates containing 2,3- and 2,6-linked sialylglycosyl groups. Western blotting with peroxidase-labeled Limulus polyphemus agglutinin revealed the occurrence of different sialoglycoprotein types in both cell lysates and cell wall protein extracts of mycelia, spores, and yeasts of M. polymorphosporus. Sialic acids contributed to the surface negative charge of spores and yeast forms as evaluated by adherence to a cationic substrate. Sialidase-treated spores were less resistant to phagocytosis by human neutrophils and monocytes from healthy individuals than control (untreated) fungal suspensions. The results suggest that sialic acids are terminal units of various glycoproteins of M. polymorphosporus, contributing to negative charge of yeasts and spore cells and protecting infectious propagules from destruction by host cells.

Host-Toxoplasma gondii Coadaptation Leads to Fine Tuning of the Immune Response

PubMed Central

Brasil, Thaís Rigueti; Freire-de-Lima, Celio Geraldo; Morrot, Alexandre; Vetö Arnholdt, Andrea Cristina

2017-01-01

Toxoplasma gondii has successfully developed strategies to evade host’s immune response and reach immune privileged sites, which remains in a controlled environment inside quiescent tissue cysts. In this review, we will approach several known mechanisms used by the parasite to modulate mainly the murine immune system at its favor. In what follows, we review recent findings revealing interference of host’s cell autonomous immunity and cell signaling, gene expression, apoptosis, and production of microbicide molecules such as nitric oxide and oxygen reactive species during parasite infection. Modulation of host’s metalloproteinases of extracellular matrix is also discussed. These immune evasion strategies are determinant to parasite dissemination throughout the host taking advantage of cells from the immune system to reach brain and retina, crossing crucial hosts’ barriers. PMID:28955329

An electron microscopy study of the diversity of Streptococcus sanguinis cells induced by lysozyme in vitro.

PubMed

Hao, Yuqing; Li, Li; Li, Wei; Zhou, Xuedong; Lu, Junjun

2010-01-01

Bacterial virulence could be altered by the antimicrobial agents of the host. Our aim was to identify the damage and survival of Streptococcus sanguinis induced by lysozymes in vitro and to analyse the potential of oral microorganisms to shirk host defences, which cause infective endocarditis. S. sanguinis ATCC 10556 received lysozyme at concentrations of 12.5, 25, 50 and 100 microg/ml. Cells were examined by electron microscopy. The survival was assessed by colony counting and construction of a growth curve. Challenged by lysozymes, cells mainly exhibited cell wall damage, which seemed to increase with increasing lysozyme concentration and longer incubation period in the presence of ions. Cells with little as well as apparent lesion were observed under the same treatment set, and anomalous stick and huge rotund bodies were occasionally observed. After the removal of the lysozyme, some damaged cells could be reverted to its original form with brain heart infusion (BHI), and their growth curve was similar to the control cells. After further incubation in BHI containing lysozyme, S. sanguinis cell damage stopped progressing, and their growth curve was also similar to the control cells. The results suggested that the S. sanguinis lesions caused by the lysozyme in the oral cavity may be nonhomogeneous and that some damaged cells could self-repair and survive. It also indicated that S. sanguinis with damaged cell walls may survive and be transmitted in the bloodstream.

Host genetic determinants of HIV pathogenesis: an immunologic perspective.

PubMed

Hunt, Peter W; Carrington, Mary

2008-05-01

The purpose of this review is to highlight recent advances in our understanding of host genetic determinants of HIV pathogenesis and to provide a theoretical framework for interpreting these studies in the context of our evolving understanding of HIV immunopathogenesis. The first genome-wide association analysis of host determinants of HIV pathogenesis and other recent studies evaluating the interaction between killer cell immunoglobulin-like receptors and human leukocyte antigen alleles have implicated both adaptive and innate immune responses in the control of HIV replication. Furthermore, genetic variation associated with the expression of CCR5 and its ligand have been strongly associated with both decreased susceptibility to HIV infection and delayed clinical progression, independent of their effects on viral replication, suggesting a potential role for CCR5 inhibitors as immune-based therapies in HIV disease. Host factors associated with the control of HIV replication may help identify important targets for vaccine design, while those associated with delayed clinical progression provide targets for future immune-based therapies against HIV infection.

Metformin: Candidate host-directed therapy for tuberculosis in diabetes and non-diabetes patients.

PubMed

Restrepo, Blanca I

2016-12-01

Despite major advances in tuberculosis (TB) control, TB continues to be a leading cause of death worldwide. The discovery of new anti-TB treatment drugs and regimens that target drug-sensitive and drug-resistant TB are being complemented with a search for adjunct host-directed therapies that synergize for Mycobacterium tuberculosis (Mtb) elimination. The goal of host-directed therapies is to boost immune mechanisms that diminish excess inflammation to reduce lung tissue damage and limit Mtb growth. Metformin is the most commonly-used medication for type 2 diabetes, and a candidate for host-directed therapy for TB. Preliminary data suggests metformin may be beneficial for TB control by reducing the deleterious inflammation associated with immune pathology and enhancing the anti-mycobacterial activity of immune cells. In this review I summarize current findings, knowledge gaps and the potential benefits as well as points of caution for using metformin as adjunct therapy for TB in patients with and without type 2 diabetes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Insect immune system maintains long-term resident bacteria through a local response.

PubMed

Login, Frédéric H; Heddi, Abdelaziz

2013-02-01

Long-term associations between bacteria and animals are widely represented in nature and play an important role in animal adaptation and evolution. In insects thriving on nutritionally unbalanced diets, intracellular symbiotic bacteria (endosymbionts) complement the host nutrients with amino acids and vitamins and interfere with host physiology and reproduction. Endosymbionts permanently infect host cells, called bacteriocytes, which express an adapted local immune response that permits symbiont maintenance and control. Among the immune players in bacteriocytes, the coleoptericin A (ColA) antimicrobial peptide of the cereal weevil, Sitophilus zeamais, was recently found to specifically trigger endosymbionts and to inhibit their cytokinesis, thereby limiting bacterial cell division and dispersion throughout the insect tissues. This review focuses on the biological and evolutionary features of Sitophilus symbiosis, and discusses the possible interactions of ColA with weevil endosymbiont proteins and pathways. Copyright © 2012 Elsevier Ltd. All rights reserved.

Human cytomegalovirus tegument protein pp150 acts as a cyclin A2-CDK-dependent sensor of the host cell cycle and differentiation state.

PubMed

Bogdanow, Boris; Weisbach, Henry; von Einem, Jens; Straschewski, Sarah; Voigt, Sebastian; Winkler, Michael; Hagemeier, Christian; Wiebusch, Lüder

2013-10-22

Upon cell entry, herpesviruses deliver a multitude of premade virion proteins to their hosts. The interplay between these incoming proteins and cell-specific regulatory factors dictates the outcome of infections at the cellular level. Here, we report a unique type of virion-host cell interaction that is essential for the cell cycle and differentiation state-dependent onset of human cytomegalovirus (HCMV) lytic gene expression. The major tegument 150-kDa phosphoprotein (pp150) of HCMV binds to cyclin A2 via a functional RXL/Cy motif resulting in its cyclin A2-dependent phosphorylation. Alanine substitution of the RXL/Cy motif prevents this interaction and allows the virus to fully escape the cyclin-dependent kinase (CDK)-mediated block of immediate early (IE) gene expression in S/G2 phase that normally restricts the onset of the HCMV replication cycle to G0/G1. Furthermore, the cyclin A2-CDK-pp150 axis is also involved in the establishment of HCMV quiescence in NTera2 cells, showing the importance of this molecular switch for differentiation state-dependent regulation of IE gene expression. Consistent with the known nucleocapsid-binding function of pp150, its RXL/Cy-dependent phosphorylation affects gene expression of the parental virion only, suggesting a cis-acting, virus particle-associated mechanism of control. The pp150 homologs of other primate and mammalian CMVs lack an RXL/Cy motif and accordingly even the nearest relative of HCMV, chimpanzee CMV, starts its lytic cycle in a cell cycle-independent manner. Thus, HCMV has evolved a molecular sensor for cyclin A2-CDK activity to restrict its IE gene expression program as a unique level of self-limitation and adaptation to its human host.

Blockade of PD-1 Signaling Enhances Th2 Cell Responses and Aggravates Liver Immunopathology in Mice with Schistosomiasis japonica

PubMed Central

Zhou, Sha; Jin, Xin; Li, Yalin; Li, Wei; Chen, Xiaojun; Xu, Lei; Zhu, Jifeng; Xu, Zhipeng; Zhang, Yang; Liu, Feng; Su, Chuan

2016-01-01

Background More than 220 million people worldwide are chronically infected with schistosomes, causing severe disease or even death. The major pathological damage occurring in schistosomiasis is attributable to the granulomatous inflammatory response and liver fibrosis induced by schistosome eggs. The inflammatory response is tightly controlled and parallels immunosuppressive regulation, constantly maintaining immune homeostasis and limiting excessive immunopathologic damage in important host organs. It is well known that the activation of programmed death 1 (PD-1) signaling causes a significant suppression of T cell function. However, the roles of PD-1 signaling in modulating CD4+ T cell responses and immunopathology during schistosome infection, have yet to be defined. Methodology/Principal Findings Here, we show that PD-1 is upregulated in CD4+ T cells in Schistosoma japonicum (S. japonicum)-infected patients. We also show the upregulation of PD-1 expression in CD4+ T cells in the spleens, mesenteric lymph nodes, and livers of mice with S. japonicum infection. Finally, we found that the blockade of PD-1 signaling enhanced CD4+ T helper 2 (Th2) cell responses and led to more severe liver immunopathology in mice with S. japonicum infection, without a reduction of egg production or deposition in the host liver. Conclusions/Significance Overall, our study suggests that PD-1 signaling is specifically induced to control Th2-associated inflammatory responses during schistosome infection and is beneficial to the development of PD-1-based control of liver immunopathology. PMID:27792733

Dynamic Epstein-Barr Virus Gene Expression on the Path to B-Cell Transformation

PubMed Central

Price, Alexander M.; Luftig, Micah A.

2016-01-01

Epstein-Barr Virus is an oncogenic human herpesvirus in the γ-herpesvirinae sub-family that contains a 170–180 kb double stranded DNA genome. In vivo, EBV commonly infects B and epithelial cells and persists for the life of the host in a latent state in the memory B cell compartment of the peripheral blood. EBV can be reactivated from its latent state leading to increased expression of lytic genes that primarily encode for enzymes necessary to replicate the viral genome as well as structural components of the virion. Lytic cycle proteins also aid in immune evasion, inhibition of apoptosis, and the modulation of other host responses to infection. In vitro, EBV has the potential to infect primary human B cells and induce cellular proliferation to yield effectively immortalized lymphoblastoid cell lines, or LCLs. EBV immortalization of B cells in vitro serves as a model system for studying EBV-mediated lymphomagenesis. While much is known about the steady state viral gene expression within EBV immortalized LCLs and other EBV-positive cell lines, relatively little is known about the early events after primary B-cell infection. It was previously thought that upon latent infection EBV only expressed the well-characterized latency associated transcripts found in LCLs. However, recent work has characterized the early, but transient, expression of lytic genes necessary for efficient transformation as well as delayed responses in the known latency genes. This review summarizes these recent findings that show how dynamic and controlled expression of multiple EBV genes can control the activation of B cells, entry into the cell cycle, inhibition of apoptosis, and control of innate and adaptive immune responses. PMID:24373315

The Mechanisms for Within-Host Influenza Virus Control Affect Model-Based Assessment and Prediction of Antiviral Treatment

PubMed Central

Cao, Pengxing

2017-01-01

Models of within-host influenza viral dynamics have contributed to an improved understanding of viral dynamics and antiviral effects over the past decade. Existing models can be classified into two broad types based on the mechanism of viral control: models utilising target cell depletion to limit the progress of infection and models which rely on timely activation of innate and adaptive immune responses to control the infection. In this paper, we compare how two exemplar models based on these different mechanisms behave and investigate how the mechanistic difference affects the assessment and prediction of antiviral treatment. We find that the assumed mechanism for viral control strongly influences the predicted outcomes of treatment. Furthermore, we observe that for the target cell-limited model the assumed drug efficacy strongly influences the predicted treatment outcomes. The area under the viral load curve is identified as the most reliable predictor of drug efficacy, and is robust to model selection. Moreover, with support from previous clinical studies, we suggest that the target cell-limited model is more suitable for modelling in vitro assays or infection in some immunocompromised/immunosuppressed patients while the immune response model is preferred for predicting the infection/antiviral effect in immunocompetent animals/patients. PMID:28933757

Gene Expression Profiling of Monkeypox Virus-Infected Cells Reveals Novel Interfaces for Host-Virus Interactions

DTIC Science & Technology

2010-07-28

expression is plotted on Y -axis after normalization to mock-treated samples. Results plotted to compare calculated fold change in expression of each gene ...RESEARCH Open Access Gene expression profiling of monkeypox virus-infected cells reveals novel interfaces for host-virus interactions Abdulnaser...suppress antiviral cell defenses, exploit host cell machinery, and delay infection-induced cell death. However, a comprehensive study of all host genes

Obligatory Requirement for Antibody in Recovery from a Primary Poxvirus Infection

PubMed Central

Chaudhri, Geeta; Panchanathan, Vijay; Bluethmann, Horst; Karupiah, Gunasegaran

2006-01-01

To understand the correlates of protective immunity against primary variola virus infection in humans, we have used the well-characterized mousepox model. This is an excellent surrogate small-animal model for smallpox in which the disease is caused by infection with the closely related orthopoxvirus, ectromelia virus. Similarities between the two infections include virus replication and transmission, aspects of pathology, and development of pock lesions. Previous studies using ectromelia virus have established critical roles for cytokines and effector functions of CD8 T cells in the control of acute stages of poxvirus infection. Here, we have used mice deficient in B cells to demonstrate that B-cell function is also obligatory for complete virus clearance and recovery of the host. In the absence of B cells, virus persists and the host succumbs to infection, despite the generation of CD8 T-cell responses. Intriguingly, transfer of naive B cells or ectromelia virus-immune serum to B-cell-deficient mice with established infection allowed these animals to clear virus and fully recover. In contrast, transfer of ectromelia virus-immune CD8 T cells was ineffective. Our data show that mice deficient in CD8 T-cell function die early in infection, whereas those deficient in B cells or antibody production die much later, indicating that B-cell function becomes critical after the effector phase of the CD8 T-cell response to infection subsides. Strikingly, our results show that antibody prevents virus from seeding the skin and forming pock lesions, which are important for virus transmission between hosts. PMID:16775322

Understanding the biology of ex vivo-expanded CD8 T cells for adoptive cell therapy: role of CD62L.

PubMed

Díaz-Montero, C Marcela; Zidan, Abdel-Aziz; Pallin, Maria F; Anagnostopoulos, Vasileios; Salem, Mohamed L; Wieder, Eric; Komanduri, Krishna; Montero, Alberto J; Lichtenheld, Mathias G

2013-12-01

CD62L governs the circulation of CD8(+) T cells between lymph nodes and peripheral tissues, whereby the expression of CD62L by CD8(+) T cells promotes their recirculation through lymph nodes. As such, CD62L participates in the fate of adoptively transferred CD8(+) T cells and may control their effectiveness for cancer immunotherapy, including settings in which host preconditioning results in the acute lymphopenia-induced proliferation of the transferred cells. Indeed, previous studies correlated CD62L expression by donor CD8(+) cells with the success rate of adoptive cell therapy (ACT). Here, we analyzed the functions and fate of ex vivo-activated, tumor-specific CD62L(-/-) CD8(+) T cells in a mouse melanoma model for ACT. Unexpectedly, we observed that CD62L(-/-) CD8(+) T cells were functionally indistinguishable from CD62L(+/+) CD8(+) T cells, i.e., both greatly expanded in cyclophosphamide preconditioned animals, controlled subcutaneously and hematogenously spreading tumors, and generated anti-tumor-specific CD8(+) T cell memory. Moreover, even in hosts with rudimentary secondary lymphoid organs (LT(-/-) animals), CD8(+) T cells with and without CD62L expanded equivalently to those adoptively transferred into wild-type animals. These results put into question the utility of CD62L as a predictive biomarker for the efficacy of ex vivo-expanded T cells after ACT in lymphopenic conditions and also offer new insights into the homing, engraftment, and memory generation of adoptively transferred ex vivo-activated CD8(+) T cells.

Antiviral T-cell therapy

PubMed Central

Leen, Ann M; Heslop, Helen E; Brenner, Malcolm K

2013-01-01

Summary Serious viral infections are a common cause of morbidity and mortality after allogeneic stem cell transplantation. They occur in the majority of allograft recipients and are fatal in 17–20%. These severe infections may be prolonged or recurrent and add substantially to the cost, both human and financial, of the procedure. Many features of allogeneic stem cell transplantation contribute to this high rate of viral disease. The cytotoxic and immunosuppressive drugs administered pre-transplant to eliminate the host hematopoietic/immune system and any associated malignancy, the delay in recapitulating immune ontogeny post-transplant, the immunosuppressive drugs given to prevent graft versus host disease (GvHD), and the effects of GvHD itself, all serve to make stem cell transplant recipients vulnerable to disease from endogenous (latent) and exogenous (community) viruses, and to be incapable of controlling them as quickly and effectively as most normal individuals. PMID:24517423

Host cell capable of producing enzymes useful for degradation of lignocellulosic material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Los, Alrik Pieter; Sagt, Cornelis Maria Jacobus; Schoonneveld-Bergmans, Margot Elisabeth Francoise

The invention relates to a host cell comprising at least four different heterologous polynucleotides chosen from the group of polynucleotides encoding cellulases, hemicellulases and pectinases, wherein the host cell is capable of producing the at least four different enzymes chosen from the group of cellulases, hemicellulases and pectinases, wherein the host cell is a filamentous fungus and is capable of secretion of the at least four different enzymes. This host cell can suitably be used for the production of an enzyme composition that can be used in a process for the saccharification of cellulosic material.

An antimicrobial peptide essential for bacterial survival in the nitrogen-fixing symbiosis.

PubMed

Kim, Minsoo; Chen, Yuhui; Xi, Jiejun; Waters, Christopher; Chen, Rujin; Wang, Dong

2015-12-08

In the nitrogen-fixing symbiosis between legume hosts and rhizobia, the bacteria are engulfed by a plant cell membrane to become intracellular organelles. In the model legume Medicago truncatula, internalization and differentiation of Sinorhizobium (also known as Ensifer) meliloti is a prerequisite for nitrogen fixation. The host mechanisms that ensure the long-term survival of differentiating intracellular bacteria (bacteroids) in this unusual association are unclear. The M. truncatula defective nitrogen fixation4 (dnf4) mutant is unable to form a productive symbiosis, even though late symbiotic marker genes are expressed in mutant nodules. We discovered that in the dnf4 mutant, bacteroids can apparently differentiate, but they fail to persist within host cells in the process. We found that the DNF4 gene encodes NCR211, a member of the family of nodule-specific cysteine-rich (NCR) peptides. The phenotype of dnf4 suggests that NCR211 acts to promote the intracellular survival of differentiating bacteroids. The greatest expression of DNF4 was observed in the nodule interzone II-III, where bacteroids undergo differentiation. A translational fusion of DNF4 with GFP localizes to the peribacteroid space, and synthetic NCR211 prevents free-living S. meliloti from forming colonies, in contrast to mock controls, suggesting that DNF4 may interact with bacteroids directly or indirectly for its function. Our findings indicate that a successful symbiosis requires host effectors that not only induce bacterial differentiation, but also that maintain intracellular bacteroids during the host-symbiont interaction. The discovery of NCR211 peptides that maintain bacterial survival inside host cells has important implications for improving legume crops.

Models of breast cancer growth and investigations of adjuvant surgical oophorectomy.

PubMed

Love, Richard R; Niederhuber, John E

2004-09-01

Clinical observations of the natural history of breast cancer and its response to a variety of therapeutic interventions have contributed to changing concepts about the growth and metastatic spread of this disease. Increased attention has been given to tumor cell dormancy and the occurrence of greatly delayed metastatic disease development, which has been important to rethinking therapy. Although gene profiling of breast tumors recently has highlighted the importance of individual tumor characteristics in patients' prognosis, considerable data also support the concept of breast cancer as a problem of macro- and microenvironmental regulatory imbalance and dynamic chaos. Observations of unexpectedly large survival benefits from adjuvant surgical oophorectomy done in the luteal phase of the menstrual cycle in premenopausal women are consistent with an interpretation that extratumoral interactions in the host environment are important in prognosis. These observations also suggest that a treatment paradigm shift from an exclusive focus on cell kill and specific tumor cell molecular targets to one focused also on broad host regulatory control may be useful. Clinical trials and laboratory mechanistic investigations based on these data and observations can determine the potential impact of therapeutic interventions targeting host system macro and micro tumor cell environments.

Rapid host immune response and viral dynamics in herpes simplex virus-2 infection

PubMed Central

Schiffer, Joshua T; Corey, Lawrence

2014-01-01

Herpes Simplex Virus-2 (HSV-2) is episodically shed throughout the human genital tract. While high viral load correlates with development of genital ulcers, shedding also commonly occurs even when ulcers are not present, allowing for silent transmission during coitus and contributing to high seroprevalence of HSV-2 worldwide. Frequent viral reactivation occurs despite diverse and complementary host and viral mechanisms within ganglionic tissue that predispose towards latency, suggesting that viral replication may be constantly occurring in a small minority of neurons within the ganglia. Within genital mucosa, the in vivo expansion and clearance rates of HSV-2 are extremely rapid. Resident dendritic cells and memory HSV-specific T cells persist at prior sites of genital tract reactivation, and in conjunction with prompt innate recognition of infected cells, lead to rapid containment of infected cells. Shedding episodes vary greatly in duration and severity within a single person over time: this heterogeneity appears best explained by variation in the densities of host immunity across the genital tract. The fact that immune responses usually control viral replication in genital skin prior to development of lesions provides optimism that enhancing such responses could lead to effective vaccines and immunotherapies. PMID:23467247

Systems biology of host-mycobiota interactions: dissecting Dectin-1 and Dectin-2 signalling in immune cells with DC-ATLAS.

PubMed

Rizzetto, Lisa; De Filippo, Carlotta; Rivero, Damariz; Riccadonna, Samantha; Beltrame, Luca; Cavalieri, Duccio

2013-11-01

Modelling the networks sustaining the fruitful coexistence between fungi and their mammalian hosts is becoming increasingly important to control emerging fungal pathogens. The C-type lectins Dectin-1 and Dectin-2 are involved in host defense mechanisms against fungal infection driving inflammatory and adaptive immune responses and complement in containing fungal burdens. Recognizing carbohydrate structures in pathogens, their engagement induces maturation of dendritic cells (DCs) into potent immuno-stimulatory cells endowed with the capacity to efficiently prime T cells. Owing to these properties, Dectin-1 and Dectin-2 agonists are currently under investigation as promising adjuvants in vaccination procedures for the treatment of fungal infection. Thus, a detailed understanding of events' cascade specifically triggered in DCs upon engagement is of great interest in translational research. Here, we summarize the current knowledge on Dectin-1 and Dectin-2 signalling in DCs highlighting similarities and differences. Detailed maps are annotated, using the Biological Connection Markup Language (BCML) data model, and stored in DC-ATLAS, a versatile resource for the interpretation of high-throughput data generated perturbing the signalling network of DCs. Copyright © 2013 Elsevier GmbH. All rights reserved.

Genetic Causes of Human NK Cell Deficiency and Their Effect on NK Cell Subsets

PubMed Central

Mace, Emily M.; Orange, Jordan S.

2016-01-01

Human NK cells play critical roles in human host defense, particularly the control of viral infection and malignancy, and patients with congenital immunodeficiency affecting NK cell function or number can suffer from severe illness. The importance of NK cell function is particularly underscored in patients with primary immunodeficiency in which NK cells are the primary or sole affected population (NK cell deficiency, NKD). While NKD may lead to the absence of NK cells, we are also gaining an increasing appreciation of the effect that NKD may have on the generation of specific NK cell subsets. In turn, this leads to improved insights into the requirements for human NK cell subset generation, as well as their importance in immune homeostasis. The presence of inherently abnormally developed or functionally impaired NK cells, in particular, appears to be problematic in the way of interfering with normal human host defense and may be more impactful than low numbers of NK cells alone. Here, we review the known genetic causes of NKD and the insight that is derived by these into the requirements for human subset generation and, by extension, for NK cell-mediated immunity. PMID:27994588

Differential expression of lncRNAs during the HIV replication cycle: an underestimated layer in the HIV-host interplay.

PubMed

Trypsteen, Wim; Mohammadi, Pejman; Van Hecke, Clarissa; Mestdagh, Pieter; Lefever, Steve; Saeys, Yvan; De Bleser, Pieter; Vandesompele, Jo; Ciuffi, Angela; Vandekerckhove, Linos; De Spiegelaere, Ward

2016-10-26

Studying the effects of HIV infection on the host transcriptome has typically focused on protein-coding genes. However, recent advances in the field of RNA sequencing revealed that long non-coding RNAs (lncRNAs) add an extensive additional layer to the cell's molecular network. Here, we performed transcriptome profiling throughout a primary HIV infection in vitro to investigate lncRNA expression at the different HIV replication cycle processes (reverse transcription, integration and particle production). Subsequently, guilt-by-association, transcription factor and co-expression analysis were performed to infer biological roles for the lncRNAs identified in the HIV-host interplay. Many lncRNAs were suggested to play a role in mechanisms relying on proteasomal and ubiquitination pathways, apoptosis, DNA damage responses and cell cycle regulation. Through transcription factor binding analysis, we found that lncRNAs display a distinct transcriptional regulation profile as compared to protein coding mRNAs, suggesting that mRNAs and lncRNAs are independently modulated. In addition, we identified five differentially expressed lncRNA-mRNA pairs with mRNA involvement in HIV pathogenesis with possible cis regulatory lncRNAs that control nearby mRNA expression and function. Altogether, the present study demonstrates that lncRNAs add a new dimension to the HIV-host interplay and should be further investigated as they may represent targets for controlling HIV replication.

Metabolic reprogramming: a hallmark of viral oncogenesis.

PubMed

Lévy, P; Bartosch, B

2016-08-11

More than 1 in 10 cases of cancer in the world are due to chronic viral infections. Viruses induce oncogenesis by targeting the same pathways known to be responsible for neoplasia in tumor cells, such as control of cell cycle progression, cell migration, proliferation and evasion from cell death and the host's immune defense. In addition, metabolic reprogramming has been identified over a century ago as a requirement for growth of transformed cells. Renewed interest in this topic has emerged recently with the discovery that basically all metabolic changes in tumor cells are finely orchestrated by oncogenes and tumor suppressors. Indeed, cancer cells activate biosynthetic pathways in order to provide them with sufficient levels of energy and building blocks to proliferate. Interestingly, viruses introduce into their host cells similar metabolic adaptations, and importantly, it seems that they depend on these changes for their persistence and amplification. The central carbon metabolism, for example, is not only frequently altered in tumor cells but also modulated by human papillomavirus, hepatitis B and C viruses, Epstein-Barr virus and Kaposi's Sarcoma-associated virus. Moreover, adenoviruses (Ad) and human cytomegalovirus, which are not directly oncogenic but present oncomodulatory properties, also divert cellular metabolism in a tumor cell-like mnner. Thus, metabolic reprogramming appears to be a hallmark of viral infection and provides an interesting therapeutic target, in particular, for oncogenic viruses. Therapeutic targeting of metabolic pathways may not only allow to eliminate or control the viral infection but also to prevent virus-induced carcinogenesis.

T cell-derived IL-10 and its impact on the regulation of host responses during malaria.

PubMed

Freitas do Rosario, Ana Paula; Langhorne, Jean

2012-05-15

Despite intense research, malaria still is the one of the most devastating diseases killing more people than any other parasitic infection. In an attempt to control the infection, the host immune system produces a potent pro-inflammatory response. However, this response is also associated with complications, such as severe anaemia, hypoglycaemia and cerebral malaria. This pronounced production of pro-inflammatory cytokines response is a common feature of malaria caused by parasites infecting humans as well as rodents and primates. A balance between pro- and anti-inflammatory responses may be fundamental to the elimination of the parasite without inducing excessive host pathology. IL-10 is a key cytokine that has been shown to have an important regulatory function in establishing this balance in malaria. Here we discuss which cells can produce IL-10 during infection, and present an overview of the evidence showing that T-cell derived IL-10 plays an important role in regulating malaria pathology. Many different subsets of T cells can produce IL-10, however, evidence is accumulating that it is effector Th1 CD4(+) T cells which provide the crucial source that down-regulates inflammatory pathology during blood-stage malaria infections. Copyright © 2012 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

Engraftment of donor mesenchymal stem cells in chimeric BXSB includes vascular endothelial cells and hepatocytes.

PubMed

Jones, Olcay Y; Gok, Faysal; Rushing, Elisabeth J; Horkayne-Szakaly, Iren; Ahmed, Atif A

2011-01-01

Somatic tissue engraftment was studied in BXSB mice treated with mesenchymal stem cell transplantation. Hosts were conditioned with nonlethal radiation prior to introducing donor cells from major histocompatibility complex-matched green fluorescent protein transgenic mice. Transplant protocols differed for route of injection, ie, intravenous (i.v.) versus intraperitoneal (i.p.), and source of mesenchymal stem cells, ie, unfractionated bone marrow cells, ex vivo expanded mesenchymal stem cells, or bone chips. Tissue chimerism was determined after short (10-12 weeks) or long (62 weeks) posttransplant follow-up by immunohistochemistry for green fluorescent protein. Engraftment of endothelial cells was seen in several organs including liver sinusoidal cells in i.v. treated mice with ex vivo expanded mesenchymal stem cells or with unfractionated bone marrow cells. Periportal engraftment of liver hepatocytes, but not engraftment of endothelial cells, was found in mice injected i.p. with bone chips. Engraftment of adipocytes was a common denominator in both i.v. and i.p. routes and occurred during early phases post-transplant. Disease control was more robust in mice that received both i.v. bone marrow and i.p. bone chips compared to mice that received i.v. bone marrow alone. Thus, the data support potential use of mesenchymal stem cell transplant for treatment of severe lupus. Future studies are needed to optimize transplant conditions and tailor protocols that may in part be guided by fat and endothelial biomarkers. Furthermore, the role of liver chimerism in disease control and the nature of cellular communication among donor hematopoietic and mesenchymal stem cells in a chimeric host merit further investigation.

Lactobacillus johnsonii inhibits indoleamine 2,3-dioxygenase and alters tryptophan metabolite levels in BioBreeding rats.

PubMed

Valladares, Ricardo; Bojilova, Lora; Potts, Anastasia H; Cameron, Evan; Gardner, Christopher; Lorca, Graciela; Gonzalez, Claudio F

2013-04-01

In our previous work, we found that feeding Lactobacillus johnsonii to BioBreeding diabetes-prone (BBDP) rats decreased the incidence of diabetes development. The aim of this study was to investigate host pathways affected by L. johnsonii, with specific focus on the rate-limiting enzyme of tryptophan catabolism, indoleamine 2,3-dioxygenase (IDO). Suspensions of L. johnsonii or an equal volume of vehicle were orally administered to BBDP rats. Tissue IDO was investigated using quantitative RT-PCR and Western blot, whereas tryptophan, kynurenine, and 5-hydroxytryptamine (5-HT) concentrations were quantified by HPLC and ELISA. IDO activity was also investigated using L. johnsonii culture cell-free supernatant (CFS) with affinity-purified IDO and HT-29 intestinal epithelial cells. L. johnsonii feeding resulted in a 17% reduction in serum kynurenine compared with that in vehicle-fed controls, correlating with a 1.4-fold elevation in 5-HT levels. H₂O₂ produced by L. johnsonii abolished IDO activity in vitro, and L. johnsonii feeding resulted in a 3.9-fold increase in ileum lumen H₂O₂. L. johnsonii CFS significantly reduced IDO activity in HT-29 intestinal epithelial cells (47% reduction) compared with that in vehicle-treated controls, an effect abolished by catalase treatment. These data support the role of H₂O₂ in commensal bacteria-host interactions and highlight the influence of commensal bacteria-derived H₂O₂ on host physiology.

Expulsion of Symbiotic Algae during Feeding by the Green Hydra – a Mechanism for Regulating Symbiont Density?

PubMed Central

Fishman, Yelena; Zlotkin, Eliahu; Sher, Daniel

2008-01-01

Background Algal-cnidarian symbiosis is one of the main factors contributing to the success of cnidarians, and is crucial for the maintenance of coral reefs. While loss of the symbionts (such as in coral bleaching) may cause the death of the cnidarian host, over-proliferation of the algae may also harm the host. Thus, there is a need for the host to regulate the population density of its symbionts. In the green hydra, Chlorohydra viridissima, the density of symbiotic algae may be controlled through host modulation of the algal cell cycle. Alternatively, Chlorohydra may actively expel their endosymbionts, although this phenomenon has only been observed under experimentally contrived stress conditions. Principal Findings We show, using light and electron microscopy, that Chlorohydra actively expel endosymbiotic algal cells during predatory feeding on Artemia. This expulsion occurs as part of the apocrine mode of secretion from the endodermal digestive cells, but may also occur via an independent exocytotic mechanism. Significance Our results demonstrate, for the first time, active expulsion of endosymbiotic algae from cnidarians under natural conditions. We suggest this phenomenon may represent a mechanism whereby cnidarians can expel excess symbiotic algae when an alternative form of nutrition is available in the form of prey. PMID:18596972

Time-Course Study of the Transcriptome of Peripheral Blood Mononuclear Cells (PBMCs) from Sheep Infected with Fasciola hepatica

PubMed Central

Scheerlinck, Jean-Pierre; Ansell, Brendan R. E.; Hall, Ross S.; Gasser, Robin B.; Jex, Aaron R.

2016-01-01

Fasciola hepatica is a parasitic trematode that infects a wide range of mammalian hosts, including livestock and humans, in temperate and tropical regions globally. This trematode causes the disease fascioliasis, which consists of an acute phase (≤ 12 weeks) during which juvenile parasites migrate through the host liver tissues, and a chronic phase (> 12 weeks) following the establishment of adult parasites in the liver bile ducts. Few studies have explored the progression of the host response over the course of Fasciola infection in the same animals. In this study, we characterized transcriptomic changes in peripheral blood mononuclear cells (PBMCs) collected from sheep at three time points over the first eight weeks of infection relative to uninfected controls. In total, 183 and 76 genes were found to be differentially transcribed at two and eight weeks post-infection respectively. Functional and pathway analysis of differentially transcribed genes revealed changes related to T-cell activation that may underpin a Th2-biased immune response against this parasite. This first insight into the dynamics of host responses during the early stages of infection improves the understanding of the pathogenesis of acute fascioliasis, informs vaccine development and presents a set of PBMC markers with diagnostic potential. PMID:27438474

Effect of helminth-induced immunity on infections with microbial pathogens

PubMed Central

2016-01-01

Helminth infections are ubiquitous worldwide and can trigger potent immune responses that differ from and potentially antagonize host protective responses to microbial pathogens. In this Review we focus on the three main killers in infectious disease—AIDS, tuberculosis and malaria—and critically assesses whether helminths adversely influence host control of these diseases. We also discuss emerging concepts for how M2 macrophages and helminth-modulated dendritic cells can potentially influence the protective immune response to concurrent infections. Finally, we present evidence advocating for more efforts to determine how and to what extent helminths interfere with the successful control of specific concurrent coinfections. PMID:24145791

Regulation of the Host Antiviral State by Intercellular Communications

PubMed Central

Assil, Sonia; Webster, Brian; Dreux, Marlène

2015-01-01

Viruses usually induce a profound remodeling of host cells, including the usurpation of host machinery to support their replication and production of virions to invade new cells. Nonetheless, recognition of viruses by the host often triggers innate immune signaling, preventing viral spread and modulating the function of immune cells. It conventionally occurs through production of antiviral factors and cytokines by infected cells. Virtually all viruses have evolved mechanisms to blunt such responses. Importantly, it is becoming increasingly recognized that infected cells also transmit signals to regulate innate immunity in uninfected neighboring cells. These alternative pathways are notably mediated by vesicular secretion of various virus- and host-derived products (miRNAs, RNAs, and proteins) and non-infectious viral particles. In this review, we focus on these newly-described modes of cell-to-cell communications and their impact on neighboring cell functions. The reception of these signals can have anti- and pro-viral impacts, as well as more complex effects in the host such as oncogenesis and inflammation. Therefore, these “broadcasting” functions, which might be tuned by an arms race involving selective evolution driven by either the host or the virus, constitute novel and original regulations of viral infection, either highly localized or systemic. PMID:26295405

Shared elements of host-targeting pathways among apicomplexan parasites of differing lifestyles.

PubMed

Pellé, Karell G; Jiang, Rays H Y; Mantel, Pierre-Yves; Xiao, Yu-Ping; Hjelmqvist, Daisy; Gallego-Lopez, Gina M; O T Lau, Audrey; Kang, Byung-Ho; Allred, David R; Marti, Matthias

2015-11-01

Apicomplexans are a diverse group of obligate parasites occupying different intracellular niches that require modification to meet the needs of the parasite. To efficiently manipulate their environment, apicomplexans translocate numerous parasite proteins into the host cell. Whereas some parasites remain contained within a parasitophorous vacuole membrane (PVM) throughout their developmental cycle, others do not, a difference that affects the machinery needed for protein export. A signal-mediated pathway for protein export into the host cell has been characterized in Plasmodium parasites, which maintain the PVM. Here, we functionally demonstrate an analogous host-targeting pathway involving organellar staging prior to secretion in the related bovine parasite, Babesia bovis, a parasite that destroys the PVM shortly after invasion. Taking into account recent identification of a similar signal-mediated pathway in the coccidian parasite Toxoplasma gondii, we suggest a model in which this conserved pathway has evolved in multiple steps from signal-mediated trafficking to specific secretory organelles for controlled secretion to a complex protein translocation process across the PVM. © 2015 John Wiley & Sons Ltd.

The Anatomy and Morphology of the Adult Bacterial Light Organ of Euprymna scolopes Berry (Cephalopoda:Sepiolidae).

PubMed

McFall-Ngai, M; Montgomery, M K

1990-12-01

The sepiolid squid, Euprymna scolopes, has a bilobed luminous organ in the center of the mantle cavity, associated with the ink sac. Luminous bacterial symbionts (Vibrio fischeri) are housed in narrow channels of host epithelial tissue. The channels of each lobe of the light organ empty into a ciliated duct, which is contiguous with the mantle cavity of the squid. Surrounding the symbiotic bacteria and their supportive host cells are host tissues recruited into the light organ system, including a muscle-derived lens and thick reflector that appear to permit the squid to control the quality of bacterial light emission.

Endocrine regulation of the immune response to influenza virus infection with a metabolite of DHEA-androstenediol.

PubMed

Padgett, D A; Loria, R M; Sheridan, J F

1997-09-01

In these studies the influence of androstenediol on the course of an experimental virus infection was examined. Pretreatment with 320 mg/kg AED protected male mice from lethal influenza virus infection. In addition, AED enhanced antigen-induced trafficking of mononuclear cells into the draining lymph node and augmented antigen-specific activation of helper-T cells, which are important for control of viral pathogenesis. Furthermore, AED prevented the characteristic increase in serum corticosterone noted during influenza A virus infection. Although steroid hormones, at least corticosteroids, typically suppress host immune and inflammatory responses in vivo, these data suggest that AED may function to augment host immune and inflammatory responses in contrast to corticosteroids.

Long-term erythropoietin gene expression from transduced cells in bioisolator devices.

PubMed

Yanay, Ofer; Barry, Simon C; Flint, Lisa Y; Brzezinski, Margaret; Barton, Randall W; Osborne, William R A

2003-11-20

Recombinant erythropoietin (EPO) is widely administered for long-term treatment of anemia associated with renal failure and other chronic diseases. The ability to deliver EPO by gene therapy would have clinical and economic benefit. We compared autologous and allogeneic transduced primary vascular smooth muscle cells for their ability to provide sustained EPO gene expression when encapsulated in TheraCyte devices implanted subcutaneously (SQ) or intraperitoneally (IP) in rats. Cells were transduced with retrovirus vector LrEpSN encoding rat EPO cDNA. Rats that received either autologous or allogeneic transduced cells showed elevated hematocrits (HCTs) ranging from 50 to 79% that were sustained for more than 12 months. The HCT of control rats remained at baseline (45.8%). Rats that received second SQ implants of either autologous or allogeneic cells showed elevations in hematocrit that were sustained for up to 12 months, suggesting the absence of immunological responses to transduced cells or implant material. All experimental groups had statistically significant elevated HCT (p < 0.001) when compared with controls. Both SQ and IP implantation were equally effective in delivering EPO long term. There were no significant differences in white blood cell (WBC) or platelet (PLT) values between treated and control animals. Implantation of TheraCyte devices was well tolerated and histological evaluation of the devices up to 12 months after surgery revealed a high degree of vascularization and no evidence of host immune response. TheraCyte devices offer a simple and safe gene delivery system that provides sustained therapeutic gene expression, permit removal and implantation of new devices, and do not require immunosuppression of the host.

Host protective roles of type 2 immunity: Parasite killing and tissue repair, flip sides of the same coin

PubMed Central

Allen, Judith E.; Sutherland, Tara E.

2014-01-01

Metazoan parasites typically induce a type 2 immune response, characterized by T helper 2 (Th2) cells that produce the cytokines IL-4, IL-5 and IL-13 among others. The type 2 response is host protective, reducing the number of parasites either through direct killing in the tissues, or expulsion from the intestine. Type 2 immunity also protects the host against damage mediated by these large extracellular parasites as they migrate through the body. At the center of both the innate and adaptive type 2 immune response, is the IL-4Rα that mediates many of the key effector functions. Here we highlight the striking overlap between the molecules, cells and pathways that mediate both parasite control and tissue repair. We have proposed that adaptive Th2 immunity evolved out of our innate repair pathways to mediate both accelerated repair and parasite control in the face of continual assault from multicellular pathogens. Type 2 cytokines are involved in many aspects of mammalian physiology independent of helminth infection. Therefore understanding the evolutionary relationship between helminth killing and tissue repair should provide new insight into immune mechanisms of tissue protection in the face of physical injury. PMID:25028340

Biomaterials Transforming growth factor-beta 1 delivery from microporous scaffolds decreases inflammation post-implant and enhances function of transplanted islets

PubMed Central

Liu, JMH; Zhang, J; Zhang, X; Hlavaty, KA; Ricci, CF; Leonard, JN; Shea, LD; Gower, RM

2015-01-01

Biomaterial scaffolds are central to many regenerative strategies as they create a space for infiltration of host tissue and provide a platform to deliver growth factors and progenitor cells. However, biomaterial implantation results in an unavoidable inflammatory response, which can impair tissue regeneration and promote loss or dysfunction of transplanted cells. We investigated localized TGF-β1 delivery to modulate this immunological environment around scaffolds and transplanted cells. TGF-β1 was delivered from layered scaffolds, with protein entrapped within an inner layer and outer layers designed for cell seeding and host tissue integration. Scaffolds were implanted into the epididymal fat pad, a site frequently used for cell transplantation. Expression of cytokines TNF-a, IL-12, and MCP-1 were decreased by at least 40% for scaffolds releasing TGF-β1 relative to control scaffolds. This decrease in inflammatory cytokine production corresponded to a 60% decrease in leukocyte infiltration. Transplantation of islets into diabetic mice on TGF-β1 scaffolds significantly improved the ability of syngeneic islets to control blood glucose levels within the first week of transplant and delayed rejection of allogeneic islets. Together, these studies emphasize the ability of localized TGF-β1 delivery to modulate the immune response to biomaterial implants and enhance cell function in cell-based therapies. PMID:26701143

Plasma membrane repair and cellular damage control: the annexin survival kit.

PubMed

Draeger, Annette; Monastyrskaya, Katia; Babiychuk, Eduard B

2011-03-15

Plasmalemmal injury is a frequent event in the life of a cell. Physical disruption of the plasma membrane is common in cells that operate under conditions of mechanical stress. The permeability barrier can also be breached by chemical means: pathogens gain access to host cells by secreting pore-forming toxins and phospholipases, and the host's own immune system employs pore-forming proteins to eliminate both pathogens and the pathogen-invaded cells. In all cases, the influx of extracellular Ca(2+) is being sensed and interpreted as an "immediate danger" signal. Various Ca(2+)-dependent mechanisms are employed to enable plasma membrane repair. Extensively damaged regions of the plasma membrane can be patched with internal membranes delivered to the cell surface by exocytosis. Nucleated cells are capable of resealing their injured plasmalemma by endocytosis of the permeabilized site. Likewise, the shedding of membrane microparticles is thought to be involved in the physical elimination of pores. Membrane blebbing is a further damage-control mechanism, which is triggered after initial attempts at plasmalemmal resealing have failed. The members of the annexin protein family are ubiquitously expressed and function as intracellular Ca(2+) sensors. Most cells contain multiple annexins, which interact with distinct plasma membrane regions promoting membrane segregation, membrane fusion and--in combination with their individual Ca(2+)-sensitivity--allow spatially confined, graded responses to membrane injury. Copyright © 2011 Elsevier Inc. All rights reserved.

Immune Checkpoints in Leprosy: Immunotherapy As a Feasible Approach to Control Disease Progression.

PubMed

Lima, Hayana Ramos; Gasparoto, Thaís Helena; de Souza Malaspina, Tatiana Salles; Marques, Vinícius Rizzo; Vicente, Marina Jurado; Marcos, Elaine Camarinha; Souza, Fabiana Corvolo; Nogueira, Maria Renata Sales; Barreto, Jaison Antônio; Garlet, Gustavo Pompermaier; da Silva, João Santana; Brito-de-Souza, Vânia Nieto; Campanelli, Ana Paula

2017-01-01

Leprosy remains a health problem in several countries. Current management of patients with leprosy is complex and requires multidrug therapy. Nonetheless, antibiotic treatment is insufficient to prevent nerve disabilities and control Mycobacterium leprae . Successful infectious disease treatment demands an understanding of the host immune response against a pathogen. Immune-based therapy is an effective treatment option for malignancies and infectious diseases. A promising therapeutic approach to improve the clinical outcome of malignancies is the blockade of immune checkpoints. Immune checkpoints refer to a wide range of inhibitory or regulatory pathways that are critical for maintaining self-tolerance and modulating the immune response. Programmed cell-death protein-1 (PD-1), programmed cell death ligand-1 (PD-L1), cytotoxic T-lymphocyte-associated protein 4, and lymphocyte-activation gene-3 are the most important immune checkpoint molecules. Several pathogens, including M. leprae , are supposed to utilize these mechanisms to evade the host immune response. Regulatory T cells and expression of co-inhibitory molecules on lymphocytes induce specific T-cell anergy/exhaustion, leading to disseminated and progressive disease. From this perspective, we outline how the co-inhibitory molecules PD-1, PD-L1, and Th1/Th17 versus Th2/Treg cells are balanced, how antigen-presenting cell maturation acts at different levels to inhibit T cells and modulate the development of leprosy, and how new interventions interfere with leprosy development.

Genome-Wide Identification of Molecular Mimicry Candidates in Parasites

PubMed Central

Ludin, Philipp; Nilsson, Daniel; Mäser, Pascal

2011-01-01

Among the many strategies employed by parasites for immune evasion and host manipulation, one of the most fascinating is molecular mimicry. With genome sequences available for host and parasite, mimicry of linear amino acid epitopes can be investigated by comparative genomics. Here we developed an in silico pipeline for genome-wide identification of molecular mimicry candidate proteins or epitopes. The predicted proteome of a given parasite was broken down into overlapping fragments, each of which was screened for close hits in the human proteome. Control searches were carried out against unrelated, free-living eukaryotes to eliminate the generally conserved proteins, and with randomized versions of the parasite proteins to get an estimate of statistical significance. This simple but computation-intensive approach yielded interesting candidates from human-pathogenic parasites. From Plasmodium falciparum, it returned a 14 amino acid motif in several of the PfEMP1 variants identical to part of the heparin-binding domain in the immunosuppressive serum protein vitronectin. And in Brugia malayi, fragments were detected that matched to periphilin-1, a protein of cell-cell junctions involved in barrier formation. All the results are publicly available by means of mimicDB, a searchable online database for molecular mimicry candidates from pathogens. To our knowledge, this is the first genome-wide survey for molecular mimicry proteins in parasites. The strategy can be adopted to any pair of host and pathogen, once appropriate negative control organisms are chosen. MimicDB provides a host of new starting points to gain insights into the molecular nature of host-pathogen interactions. PMID:21408160

Quantitative analyses reveal distinct sensitivities of the capture of HIV-1 primary viruses and pseudoviruses to broadly neutralizing antibodies.

PubMed

Kim, Jiae; Jobe, Ousman; Peachman, Kristina K; Michael, Nelson L; Robb, Merlin L; Rao, Mangala; Rao, Venigalla B

2017-08-01

Development of vaccines capable of eliciting broadly neutralizing antibodies (bNAbs) is a key goal to controlling the global AIDS epidemic. To be effective, bNAbs must block the capture of HIV-1 to prevent viral acquisition and establishment of reservoirs. However, the role of bNAbs, particularly during initial exposure of primary viruses to host cells, has not been fully examined. Using a sensitive, quantitative, and high-throughput qRT-PCR assay, we found that primary viruses were captured by host cells and converted into a trypsin-resistant form in less than five minutes. We discovered, unexpectedly, that bNAbs did not block primary virus capture, although they inhibited the capture of pseudoviruses/IMCs and production of progeny viruses at 48h. Further, viruses escaped bNAb inhibition unless the bNAbs were present in the initial minutes of exposure of virus to host cells. These findings will have important implications for HIV-1 vaccine design and determination of vaccine efficacy. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Innate immune restriction and antagonism of viral RNA lacking 2'-O methylation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hyde, Jennifer L.; Diamond, Michael S., E-mail: diamond@borcim.wustl.edu; Molecular Microbiology, Washington University School of Medicine, St Louis., MO 63110

N-7 and 2′-O methylation of host cell mRNA occurs in the nucleus and results in the generation of cap structures (cap 0, m{sup 7}GpppN; cap 1, m{sup 7}GpppNm) that control gene expression by modulating nuclear export, splicing, turnover, and protein synthesis. Remarkably, RNA cap modification also contributes to mammalian cell host defense as viral RNA lacking 2′-O methylation is sensed and inhibited by IFIT1, an interferon (IFN) stimulated gene (ISG). Accordingly, pathogenic viruses that replicate in the cytoplasm have evolved mechanisms to circumvent IFIT1 restriction and facilitate infection of mammalian cells. These include: (a) generating cap 1 structures on theirmore » RNA through cap-snatching or virally-encoded 2′-O methyltransferases, (b) using cap-independent means of translation, or (c) using RNA secondary structural motifs to antagonize IFIT1 binding. This review will discuss new insights as to how specific modifications at the 5′-end of viral RNA modulate host pathogen recognition responses to promote infection and disease.« less

Friends and foes of tuberculosis: modulation of protective immunity.

PubMed

Brighenti, Susanna; Joosten, Simone A

2018-05-27

Protective immunity in tuberculosis (TB) is subject of debate in the TB research community, as this is key to fully understand TB pathogenesis and to develop new promising tools for TB diagnosis and prognosis as well as a more efficient TB vaccine. IFN-γ producing CD4 + T cells are key in TB control, but may not be sufficient to provide protection. Additional subsets have been identified that contribute to protection such as multifunctional and cytolytic T cell subsets, including classical and non-classical T cells as well as novel innate immune cell subsets resulting from trained immunity. However, to define protective immune responses against TB, the complexity of balancing TB immunity also has to be considered. In this review, insights in effector cell immunity and how this is modulated by regulatory cells, associated comorbidities and the host microbiome is discussed. We systematically map how different suppressive immune cell subsets may affect effector cell responses at the local site of infection. We also dissect how common co-morbidities such as HIV, helminthes and diabetes may bias protective TB immunity towards pathogenic and regulatory responses. Finally, also the composition and diversity of the microbiome in the lung and gut could affect host TB immunity. Understanding these various aspects of the immunological balance in the human host is fundamental to prevent TB infection and disease. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Toxoplasma exports dense granule proteins beyond the vacuole to the host cell nucleus and rewires the host genome expression.

PubMed

Bougdour, Alexandre; Tardieux, Isabelle; Hakimi, Mohamed-Ali

2014-03-01

Toxoplasma gondii is the most widespread apicomplexan parasite and occupies a large spectrum of niches by infecting virtually any warm-blooded animals. As an obligate intracellular parasite, Toxoplasma has evolved a repertoire of strategies to fine-tune the cellular environment in an optimal way to promote growth and persistence in host tissues hence increasing the chance to be transmitted to new hosts. Short and long-term intracellular survival is associated with Toxoplasma ability to both evade the host deleterious immune defences and to stimulate a beneficial immune balance by governing host cell gene expression. It is only recently that parasite proteins responsible for driving these transcriptional changes have been identified. While proteins contained in the apical secretory Rhoptry organelle have already been identified as bona fide secreted effectors that divert host signalling pathways, recent findings revealed that dense granule proteins should be added to the growing list of effectors as they reach the host cell cytoplasm and nucleus and target various host cell pathways in the course of cell infection. Herein, we emphasize on a novel subfamily of dense granule residentproteins, exemplified with the GRA16 and GRA24 members we recently discovered as both are exported beyond the vacuole-containing parasites and reach the host cell nucleus to reshape the host genome expression. © 2013 John Wiley & Sons Ltd.

Intravenous injections of soluble drag-reducing polymers reduce foreign body reaction to implants.

PubMed

Marascalco, Philip J; Blair, Harry C; Nieponice, Alejandro; Robinson, Lisa J; Kameneva, Marina V

2009-01-01

We tested whether soluble viscoelastic drag-reducing polymers (DRPs), which modify blood flow in the macro- and microcirculation, affect host response to implanted biomaterials and control biodegradation and tissue ingrowth processes. Porous poly(L-lactate) (PLLA) implants, which are naturally hydrolyzed by foreign body giant cells, were used to evaluate differences in host response. Intravenous DRPs, high-molecular weight poly(ethylene oxide) (PEO) or poly(mannose) (PMNN), were given biweekly at 0.3-0.4 nM in saline (equivalent volumes of saline in controls) to rats with subcutaneous PLLA implants. After 7 weeks, there was no difference in weight gain or behavior between control and DRP-injected groups. Implanted PLLA scaffolds in controls were almost totally degraded and replaced by giant cell granulomas. On the contrary, PEO- or PMNN-treated animals retained a significant part of the implanted scaffold (p < 0.0001 vs. controls). The foreign body reaction was markedly decreased, and there was an increase in well-oriented collagen deposition within the implanted scaffold area in the animals treated with DRPs. The DRP-mediated effects observed in this study potentially reflect alteration in inflammatory events in response to implanted bioengineered materials, and, thus, warrant further investigation.

Host and non-host pathogens elicit different jasmonate/ethylene responses in Arabidopsis.

PubMed

Zimmerli, Laurent; Stein, Mónica; Lipka, Volker; Schulze-Lefert, Paul; Somerville, Shauna

2004-12-01

Arabidopsis does not support the growth and asexual reproduction of the barley pathogen, Blumeria graminis f. sp. hordei Bgh). A majority of germlings fail to penetrate the epidermal cell wall and papillae. To gain additional insight into this interaction, we determined whether the salicylic acid (SA) or jasmonate (JA)/ethylene (ET) defence pathways played a role in blocking barley powdery mildew infections. Only the eds1 mutant and NahG transgenics supported a modest increase in penetration success by the barley powdery mildew. We also compared the global gene expression patterns of Arabidopsis inoculated with the non-host barley powdery mildew to those inoculated with a virulent, host powdery mildew, Erysiphe cichoracearum. Genes repressed by inoculations with non-host and host powdery mildews relative to non-inoculated control plants accounted for two-thirds of the differentially expressed genes. A majority of these genes encoded components of photosynthesis and general metabolism. Consistent with this observation, Arabidopsis growth was inhibited following inoculation with Bgh, suggesting a shift in resource allocation from growth to defence. A number of defence-associated genes were induced during both interactions. These genes likely are components of basal defence responses, which do not effectively block host powdery mildew infections. In addition, genes encoding defensins, anti-microbial peptides whose expression is under the control of the JA/ET signalling pathway, were induced exclusively by non-host pathogens. Ectopic activation of JA/ET signalling protected Arabidopsis against two biotrophic host pathogens. Taken together, these data suggest that biotrophic host pathogens must either suppress or fail to elicit the JA/ET signal transduction pathway.

Subclinical cytomegalovirus infection associates with altered host immunity, gut microbiota and vaccine responses.

PubMed

Santos Rocha, Clarissa; Hirao, Lauren A; Weber, Mariana G; Méndez-Lagares, Gema; Chang, W L William; Jiang, Guochun; Deere, Jesse D; Sparger, Ellen E; Roberts, Jeffrey; Barry, Peter A; Hartigan-O'Connor, Dennis J; Dandekar, Satya

2018-04-18

Subclinical viral infections (SVI) including cytomegalovirus (CMV) are highly prevalent in humans, resulting in life-long persistence. However, the impact of SVI on the interplay between the host immunity and gut microbiota in the context of environmental exposures is not well defined. We utilized the preclinical nonhuman primate (NHP) model consisting of SVI-free (SPF) rhesus macaques and compared them to the animals with SVI (non-SPF) acquired through natural exposure and investigated the impact of SVI on immune cell distribution and function as well as on gut microbiota. These changes were examined in animals housed in the outdoor environment as compared to the controlled indoor environment. We report that SVI are associated with altered immune cell subsets and gut microbiota composition in animals housed in the outdoor environment. Non-SPF animals harbored a higher proportion of potential butyrate-producing Firmicutes and higher numbers of lymphocytes, effector T cells and cytokine-producing T cells. Surprisingly, these differences diminished following their transfer to the controlled indoor environment, suggesting that non-SPFs had increased responsiveness to environmental exposures. An experimental infection of indoor SPF animals with CMV resulted in an increased abundance of butyrate-producing bacteria, validating that CMV enhanced colonization of butyrate-producing commensals. Finally, non-SPF animals displayed lower antibody responses to influenza vaccination as compared to SPF animals. Our data show that subclinical CMV infection heightens host immunity and gut microbiota changes in response to environmental exposures. This may contribute to the heterogeneity in host immune response to vaccines and environmental stimuli at the population level. IMPORTANCE Humans harbor several latent viruses that modulate host immunity and commensal microbiota, thus introducing heterogeneity in their responses to pathogens, vaccines and environmental exposures. Most of our understanding of the effect of CMV on the immune system is based on studies of children acquiring CMV or of immune-compromised humans with acute or reactivated CMV infection or in ageing individuals. The experimental mouse models are genetically inbred and are completely adapted to the indoor laboratory environment. In contrast, nonhuman primates are genetically outbred and are raised in the outdoor environment. Our study is the first to report the impact of long-term subclinical CMV infection on host immunity and gut microbiota, which is evident only in the outdoor environment but not in the indoor environment. The significance of this study is in highlighting the impact of SVI on enhancing host immune susceptibility to environmental exposures and immune heterogeneity. Copyright © 2018 American Society for Microbiology.

Trans-suppression of host CDH3 and LOXL4 genes during Cryptosporidium parvum infection involves nuclear delivery of parasite Cdg7_FLc_1000 RNA.

PubMed

Ming, Zhenping; Gong, Ai-Yu; Wang, Yang; Zhang, Xin-Tian; Li, Min; Li, Yao; Pang, Jing; Dong, Stephanie; Strauss-Soukup, Juliane K; Chen, Xian-Ming

2018-05-01

Intestinal infection by Cryptosporidium parvum causes significant alterations in the gene expression profile in host epithelial cells. Previous studies demonstrate that a panel of parasite RNA transcripts of low protein-coding potential are delivered into infected host cells and may modulate host gene transcription. Using in vitro models of human intestinal cryptosporidiosis, we report here that trans-suppression of the cadherin 3 (CDH3) and lysyl oxidase like 4 (LOXL4) genes in human intestinal epithelial cells following C. parvum infection involves host delivery of the Cdg7_FLc_1000 RNA, a C. parvum RNA that has been previously demonstrated to be delivered into the nuclei of infected host cells. Downregulation of CDH3 and LOXL4 genes was detected in host epithelial cells following C. parvum infection or in cells expressing the parasite Cdg7_FLc_1000 RNA. Knockdown of Cdg7_FLc_1000 attenuated the trans-suppression of CDH3 and LOXL4 genes in host cells induced by infection. Interestingly, Cdg7_FLc_1000 was detected to be recruited to the promoter regions of both CDH3 and LOXL4 gene loci in host cells following C. parvum infection. Host delivery of Cdg7_FLc_1000 promoted the PH domain zinc finger protein 1 (PRDM1)-mediated H3K9 methylation associated with trans-suppression in the CDH3 gene locus, but not the LOXL4 gene. Therefore, our data suggest that host delivery of Cdg7_FLc_1000 causes CDH3 trans-suppression in human intestinal epithelial cells following C. parvum infection through PRDM1-mediated H3K9 methylation in the CDH3 gene locus, whereas Cdg7_FLc_1000 induces trans-suppression of the host LOXL4 gene through H3K9/H3K27 methylation-independent mechanisms. Copyright © 2018 Australian Society for Parasitology. Published by Elsevier Ltd. All rights reserved.

Alphavirus entry into host cells.

PubMed

Vancini, Ricardo; Hernandez, Raquel; Brown, Dennis

2015-01-01

Viruses have evolved to exploit the vast complexity of cellular processes for their success within the host cell. The entry mechanisms of enveloped viruses (viruses with a surrounding outer lipid bilayer membrane) are usually classified as being either endocytotic or fusogenic. Different mechanisms have been proposed for Alphavirus entry and genome delivery. Indirect observations led to a general belief that enveloped viruses can infect cells either by protein-assisted fusion with the plasma membrane in a pH-independent manner or by endocytosis and fusion with the endocytic vacuole in a low-pH environment. The mechanism of Alphavirus penetration has been recently revisited using direct observation of the processes by electron microscopy under conditions of different temperatures and time progression. Under conditions nonpermissive for endocytosis or any vesicular transport, events occur which allow the entry of the virus genome into the cells. When drug inhibitors of cellular functions are used to prevent entry, only ionophores are found to significantly inhibit RNA delivery. Arboviruses are agents of significant human and animal disease; therefore, strategies to control infections are needed and include development of compounds which will block critical steps in the early infection events. It appears that current evidence points to an entry mechanism, in which alphaviruses infect cells by direct penetration of cell plasma membranes through a pore structure formed by virus and, possibly, host proteins. © 2015 Elsevier Inc. All rights reserved.

A Subset of Host B-Lymphocytes Control Melanoma Metastasis Through a MCAM/MUC18-dependent Interaction: Evidence from Mice and Humans

PubMed Central

Staquicini, Fernanda I.; Tandle, Anita; Libutti, Steven K.; Sun, Jessica; Zigler, Maya; Bar-Eli, Menashe; Aliperti, Fabiana; Pérez, Elizabeth C.; Gershenwald, Jeffrey E.; Mariano, Mario; Pasqualini, Renata; Arap, Wadih; Lopes, José D.

2008-01-01

Host immunity affects tumor metastasis but the corresponding cellular and molecular mechanisms are not entirely clear. Here we show that a subset of B-lymphocytes (termed B-1 population) -- but not other lymphocytes -- have pro-metastatic effects on melanoma cells in vivo through a direct heterotypic cell-cell interaction. In the classic B16 mouse melanoma model, one mechanism underlying this phenomenon is a specific upregulation and subsequent homophilic interaction mediated by the cell surface glycoprotein MUC18 (also known as melanoma cell adhesion molecule; MCAM). Presence of B-1 lymphocytes in a panel of tumor samples from melanoma patients directly correlates with MUC18 expression in melanoma cells, indicating that the same protein interaction exists in humans. These results suggest a new but as yet unrecognized functional role for host B-1 lymphocytes in tumor metastasis and establish a biochemical basis for such observations. Our findings support the counterintuitive central hypothesis in which a primitive layer of the immune system actually contributes to tumor progression and metastasis in a mouse model and in melanoma patients. Given that monoclonal antibodies against MUC18 are in pre-clinical development but the reason for their anti-tumor activity is not well understood, these translational results are relevant in the setting of human melanoma, and perhaps of other cancers. PMID:18922915

Phloem-Conducting Cells in Haustoria of the Root-Parasitic Plant Phelipanche aegyptiaca Retain Nuclei and Are Not Mature Sieve Elements.

PubMed

Ekawa, Minako; Aoki, Koh

2017-12-05

Phelipanche aegyptiaca parasitizes a wide range of plants, including important crops, and causes serious damage to their production. P. aegyptiaca develops a specialized intrusive organ called a haustorium that establishes connections to the host's xylem and phloem. In parallel with the development of xylem vessels, the differentiation of phloem-conducting cells has been demonstrated by the translocation of symplasmic tracers from the host to the parasite. However, it is unclear yet whether haustorial phloem-conducting cells are sieve elements. In this study, we identified phloem-conducting cells in haustoria by the host-to-parasite translocation of green fluorescent protein (GFP) from AtSUC2pro::GFP tomato sieve tubes. Haustorial GFP-conducting cells contained nuclei but not callose-rich sieve plates, indicating that phloem-conducting cells in haustoria differ from conventional sieve elements. To ascertain why the nuclei were not degenerated, expression of the P. aegyptiaca homologs NAC-domain containing transcription factor ( NAC45 ), NAC45/86-dependent exonuclease-domain protein 1 ( NEN1 ), and NEN4 was examined. However, these genes were more highly expressed in the haustorium than in tubercle protrusion, implying that nuclear degradation in haustoria may not be exclusively controlled by the NAC45 / 86 - NEN regulatory pathway. Our results also suggest that the formation of plasmodesmata with large size exclusion limits is independent of nuclear degradation and callose deposition.

Iron-depletion promotes mitophagy to maintain mitochondrial integrity in pathogenic yeast Candida glabrata

PubMed Central

Nagi, Minoru; Tanabe, Koichi; Nakayama, Hironobu; Ueno, Keigo; Yamagoe, Satoshi; Umeyama, Takashi; Ohno, Hideaki; Miyazaki, Yoshitsugu

2016-01-01

ABSTRACT Candida glabrata, a haploid budding yeast, is the cause of severe systemic infections in immune-compromised hosts. The amount of free iron supplied to C. glabrata cells during systemic infections is severely limited by iron-chelating proteins such as transferrin. Thus, the iron-deficiency response in C. glabrata cells is thought to play important roles in their survival inside the host's body. In this study, we found that mitophagy was induced under iron-depleted conditions, and that the disruption of a gene homologous to ATG32, which is responsible for mitophagy in Saccharomyces cerevisiae, blocked mitophagy in C. glabrata. The mitophagic activity in C. glabrata cells was not detected on short-period exposure to nitrogen-starved conditions, which is a mitophagy-inducing condition used in S. cerevisiae. The mitophagy-deficient atg32Δ mutant of C. glabrata also exhibited decreased longevity under iron-deficient conditions. The mitochondrial membrane potential in Cgatg32Δ cells was significantly lower than that in wild-type cells under iron-depleted conditions. In a mouse model of disseminated infection, the Cgatg32Δ strain resulted in significantly decreased kidney and spleen fungal burdens compared with the wild-type strain. These results indicate that mitophagy in C. glabrata occurs in an iron-poor host tissue environment, and it may contribute to the longevity of cells, mitochondrial quality control, and pathogenesis. PMID:27347716

Targeting of RNA Polymerase II by a nuclear Legionella pneumophila Dot/Icm effector SnpL.

PubMed

Schuelein, Ralf; Spencer, Hugh; Dagley, Laura F; Li, Peng Fei; Luo, Lin; Stow, Jennifer L; Abraham, Gilu; Naderer, Thomas; Gomez-Valero, Laura; Buchrieser, Carmen; Sugimoto, Chihiro; Yamagishi, Junya; Webb, Andrew I; Pasricha, Shivani; Hartland, Elizabeth L

2018-04-24

The intracellular pathogen Legionella pneumophila influences numerous eukaryotic cellular processes through the Dot/Icm-dependent translocation of more than 300 effector proteins into the host cell. Although many translocated effectors localize to the Legionella replicative vacuole, other effectors can affect remote intracellular sites. Following infection, a subset of effector proteins localizes to the nucleus where they subvert host cell transcriptional responses to infection. Here we identified Lpg2519 (Lpp2587/Lpw27461), as a new nuclear-localized effector that we have termed SnpL. Upon ectopic expression or during L. pneumophila infection, SnpL showed strong nuclear localization by immunofluorescence microscopy but was excluded from nucleoli. Using immunoprecipitation and mass spectrometry, we determined the host-binding partner of SnpL as the eukaryotic transcription elongation factor, SUPT5H/Spt5. SUPT5H is an evolutionarily conserved component of the DRB sensitivity-inducing factor complex (DSIF complex) that regulates RNA polymerase II (Pol II) dependent mRNA processing and transcription elongation. Protein interaction studies showed that SnpL bound to the central KOW motif region of SUPT5H. Ectopic expression of SnpL led to massive upregulation of host gene expression and macrophage cell death. The activity of SnpL further highlights the ability of L. pneumophila to control fundamental eukaryotic processes such as transcription that, in the case of SnpL, leads to global upregulation of host gene expression. This article is protected by copyright. All rights reserved.

Bacterial effectors target the plant cell nucleus to subvert host transcription.

PubMed

Canonne, Joanne; Rivas, Susana

2012-02-01

In order to promote virulence, Gram-negative bacteria have evolved the ability to inject so-called type III effector proteins into host cells. The plant cell nucleus appears to be a subcellular compartment repeatedly targeted by bacterial effectors. In agreement with this observation, mounting evidence suggests that manipulation of host transcription is a major strategy developed by bacteria to counteract plant defense responses. It has been suggested that bacterial effectors may adopt at least three alternative, although not mutually exclusive, strategies to subvert host transcription. T3Es may (1) act as transcription factors that directly activate transcription in host cells, (2) affect histone packing and chromatin configuration, and/or (3) target host transcription factor activity. Here, we provide an overview on how all these strategies may lead to host transcriptional re-programming and, as a result, to improved bacterial multiplication inside plant cells.

Perturbation of host-cell membrane is a primary mechanism of HIV cytopathology.

PubMed

Cloyd, M W; Lynn, W S

1991-04-01

Cytopathic viruses injure cells by a number of different mechanisms. The mechanism by which HIV-1 injures T cells was studied by temporally examining host-cell macromolecular syntheses, stages of the cell cycle, and membrane permeability following acute infection. T cells cytopathically infected at an m.o.i. of 1-5 grew normally for 24-72 hr, depending on the cell line, followed by the first manifestation of cell injury, slowing of cell division. At that time significant amounts of unintegrated HIV DNA and p24 core protein became detectable, and acridine orange flow cytometric cell cycle studies demonstrated the presence of fewer cells in the G2/M stage of the cell cycle. There was no change in the frequency of cells in the S-stage, and metabolic pulsing with radioactive precursors demonstrated that host-cell DNA, RNA, and protein syntheses were normal at that time and normal up to the time cells started to die (approximately 24 hr later), when all three decreased. Cellular lipid synthesis, however, was perturbed when cell multiplication slowed, with phospholipid synthesis reduced and neutral lipid synthesis enhanced. Permeability of the host-cell membrane to small molecules, such as Ca2+ and sucrose, was slightly enhanced early postinfection, and by the time of slowing of cell division, host membrane permeability was greatly increased to both Ca2+ and sucrose (Stokes radius 5.2 A) but not to inulin (Stokes radium 20 A). These changes in host-cell membrane permeability and phospholipid synthesis were not observed in acutely infected H9 cells, which are not susceptible to HIV cytopathology. Thus, HIV-1 appeared to predominantly injure T cells by perturbing host-cell membrane permeability and lipid synthesis, which is similar to the cytopathic mechanisms of paramyxoviruses.

Cellular Aspects of Shigella Pathogenesis: Focus on the Manipulation of Host Cell Processes.

PubMed

Killackey, Samuel A; Sorbara, Matthew T; Girardin, Stephen E

2016-01-01

Shigella is a Gram-negative bacterium that is responsible for shigellosis. Over the years, the study of Shigella has provided a greater understanding of how the host responds to bacterial infection, and how bacteria have evolved to effectively counter the host defenses. In this review, we provide an update on some of the most recent advances in our understanding of pivotal processes associated with Shigella infection, including the invasion into host cells, the metabolic changes that occur within the bacterium and the infected cell, cell-to-cell spread mechanisms, autophagy and membrane trafficking, inflammatory signaling and cell death. This recent progress sheds a new light into the mechanisms underlying Shigella pathogenesis, and also more generally provides deeper understanding of the complex interplay between host cells and bacterial pathogens in general.

Host-directed strategies using lipid nanoparticles to reduce mycobacteria survival

NASA Astrophysics Data System (ADS)

Pereira, L.; Diogo, J.; Mateus, R.; Pimentel, M.; Videira, M.

2015-02-01

Antibiotic-resistant infections and the stagnations in the development of new drugs have increased the demand for new therapeutic approaches against Mycobacterium tuberculosis. Innovative systems that are able to target and eradicate the bacteria in the infected host cells may represent a therapeutic breakthrough while avoiding latency. The development of nanosystems aiming a controlled and targeted intracellular drug release, have proved to increase cytosolic therapeutic concentration while reducing undesired side effects. This work's main goal was to develop a host-directed strategy against mycobacterial infection through the design of a biocompatible nanocarrier for phage-derived protein delivery, using M. smegmatis as model. Since mycobacterial pathogenicity is strongly supported by the presence of lipids in the cell wall, their degradation induces bacterial destruction through cell wall hydrolysis. Phage-based lipolytic enzymes such as, LysB a mycolylarabinogalactan esterase, represent an appealing therapeutic approach. The herein proposed Ms6 LysB-containing lipid nanocarrier (SLN_LysB) explores the known advantages of nanomedicine-based systems for phagocytic cells selectively targeting thus allowing LysB intracellular accumulation and a more pronounced mycobacterial infection eradication. Adsorption efficiency value indicates the potential of this system as a protein nanocarrier. Moreover, promising outcomes were obtained in host-infected macrophages treated with SLN_LysB. The results show that the herein proposed strategy was more effective in inhibiting the growth of M. smegmatis than free LysB, which might be related to the nanocarrier internalization. Acting as effective protein nanocarriers, the protein-guided delivery in the infected phagocytic cells allows it to exert its hydrolytic action on the lipid layer of the Mycobacterium.

Early divergent host responses in SHIVsf162P3 and SIVmac251 infected macaques correlate with control of viremia.

PubMed

Xu, Huanbin; Wang, Xiaolei; Morici, Lisa A; Pahar, Bapi; Veazey, Ronald S

2011-03-25

We previously showed intravaginal inoculation with SHIVsf162p3 results in transient viremia followed by undetectable viremia in most macaques, and some displayed subsequent immunity to superinfection with pathogenic SIVmac251. Here we compare early T cell activation, proliferation, and plasma cytokine/chemokine responses in macaques intravaginally infected with either SHIVsf162p3 or SIVmac251 to determine whether distinct differences in host responses may be associated with early viral containment. The data show SIVmac251 infection results in significantly higher levels of T cell activation, proliferation, and a mixed cytokine/chemokine "storm" in plasma in primary infection, whereas infection with SHIVsf162p3 resulted in significantly lower levels of T cell activation, proliferation, and better preservation of memory CD4+ T cells in early infection which immediately preceded control of viremia. These results support the hypothesis that early systemic immune activation, T cell proliferation, and a more prominent and broader array of cytokine/chemokine responses facilitate SIV replication, and may play a key role in persistence of infection, and the progression to AIDS. In contrast, immune unresponsiveness may be associated with eventual clearance of virus, a concept that may have key significance for therapy and vaccine design.

Alternative Effector-Function Profiling Identifies Broad HIV-Specific T-Cell Responses in Highly HIV-Exposed Individuals Who Remain Uninfected

PubMed Central

Ruiz-Riol, Marta; Llano, Anuska; Ibarrondo, Javier; Zamarreño, Jennifer; Yusim, Karina; Bach, Vanessa; Mothe, Beatriz; Perez-Alvarez, Susana; Fernandez, Marco A.; Requena, Gerard; Meulbroek, Michael; Pujol, Ferran; Leon, Agathe; Cobarsi, Patricia; Korber, Bette T.; Clotet, Bonaventura; Ganoza, Carmela; Sanchez, Jorge; Coll, Josep; Brander, Christian

2015-01-01

The characterization of host immune responses to human immunodeficiency virus (HIV) in HIV controllers and individuals with high exposure but seronegativity to HIV (HESN) is needed to guide the development of effective preventive and therapeutic vaccine candidates. However, several technical hurdles severely limit the definition of an effective virus-specific T-cell response. By using a toggle-peptide approach, which takes HIV sequence diversity into account, and a novel, boosted cytokine staining/flow cytometry strategy, we here describe new patterns of T-cell responses to HIV that would be missed by standard assays. Importantly, this approach also allows detection of broad and strong virus-specific T-cell responses in HESN individuals that are characterized by a T-helper type 1 cytokine–like effector profile and produce cytokines that have been associated with potential control of HIV infection, including interleukin 10, interleukin 13, and interleukin 22. These results establish a novel approach to improve the current understanding of HIV-specific T-cell immunity and identify cellular immune responses and individual cytokines as potential markers of relative HIV resistance. As such, the findings also help develop similar strategies for more-comprehensive assessments of host immune responses to other human infections and immune-mediated disorders. PMID:25249264

Inhibition of Malaria Infection in Transgenic Anopheline Mosquitoes Lacking Salivary Gland Cells

PubMed Central

Kasashima, Katsumi; Sezutsu, Hideki; Matsuoka, Hiroyuki

2016-01-01

Malaria is an important global public health challenge, and is transmitted by anopheline mosquitoes during blood feeding. Mosquito vector control is one of the most effective methods to control malaria, and population replacement with genetically engineered mosquitoes to block its transmission is expected to become a new vector control strategy. The salivary glands are an effective target tissue for the expression of molecules that kill or inactivate malaria parasites. Moreover, salivary gland cells express a large number of molecules that facilitate blood feeding and parasite transmission to hosts. In the present study, we adapted a functional deficiency system in specific tissues by inducing cell death using the mouse Bcl-2-associated X protein (Bax) to the Asian malaria vector mosquito, Anopheles stephensi. We applied this technique to salivary gland cells, and produced a transgenic strain containing extremely low amounts of saliva. Although probing times for feeding on mice were longer in transgenic mosquitoes than in wild-type mosquitoes, transgenic mosquitoes still successfully ingested blood. Transgenic mosquitoes also exhibited a significant reduction in oocyst formation in the midgut in a rodent malaria model. These results indicate that mosquito saliva plays an important role in malaria infection in the midgut of anopheline mosquitoes. The dysfunction in the salivary glands enabled the inhibition of malaria transmission from hosts to mosquito midguts. Therefore, salivary components have potential in the development of new drugs or genetically engineered mosquitoes for malaria control. PMID:27598328

Three-dimensional polycaprolactone-hydroxyapatite scaffolds combined with bone marrow cells for cartilage tissue engineering.

PubMed

Wei, Bo; Yao, Qingqiang; Guo, Yang; Mao, Fengyong; Liu, Shuai; Xu, Yan; Wang, Liming

2015-08-01

The goal of this study was to investigate the chondrogenic potential of three-dimensional polycaprolactone-hydroxyapatite (PCL-HA) scaffolds loaded with bone marrow cells in vitro and the effect of PCL-HA scaffolds on osteochondral repair in vivo. Here, bone marrow was added to the prepared PCL-HA scaffolds and cultured in chondrogenic medium for 10 weeks. Osteochondral defects were created in the trochlear groove of 29 knees in 17 New Zealand white rabbits, which were then divided into four groups that underwent: implantation of PCL-HA scaffolds (left knee, n = 17; Group 1), microfracture (right knee, n = 6; Group 2), autologous osteochondral transplantation (right knee, n = 6; Group 3), and no treatment (right knee, n = 5; Control). Extracellular matrix produced by bone marrow cells covered the surface and filled the pores of PCL-HA scaffolds after 10 weeks in culture. Moreover, many cell-laden cartilage lacunae were observed, and cartilage matrix was concentrated in the PCL-HA scaffolds. After a 12-week repair period, Group 1 showed excellent vertical and lateral integration with host bone, but incomplete cartilage regeneration and matrix accumulation. An uneven surface of regenerated cartilage and reduced distribution of cartilage matrix were observed in Group 2. In addition, abnormal bone growth and unstable integration between repaired and host tissues were detected. For Group 3, the integration between transplanted and host cartilage was interrupted. Our findings indicate that the PCL-HA scaffolds loaded with bone marrow cells improved chondrogenesis in vitro and implantation of PCL-HA scaffolds for osteochondral repairenhanced integration with host bone. However, cartilage regeneration remained unsatisfactory. The addition of trophic factors or the use of precultured cell-PCL-HA constructs for accelerated osteochondral repair requires further investigation. © The Author(s) 2015.

Tunable Control of an Escherichia coli Expression System for the Overproduction of Membrane Proteins by Titrated Expression of a Mutant lac Repressor.

PubMed

Kim, Seong Keun; Lee, Dae-Hee; Kim, Oh Cheol; Kim, Jihyun F; Yoon, Sung Ho

2017-09-15

Most inducible expression systems suffer from growth defects, leaky basal induction, and inhomogeneous expression levels within a host cell population. These difficulties are most prominent with the overproduction of membrane proteins that are toxic to host cells. Here, we developed an Escherichia coli inducible expression system for membrane protein production based on titrated expression of a mutant lac repressor (mLacI). Performance of the mLacI inducible system was evaluated in conjunction with commonly used lac operator-based expression vectors using a T7 or tac promoter. Remarkably, expression of a target gene can be titrated by the dose-dependent addition of l-rhamnose, and the expression levels were homogeneous in the cell population. The developed system was successfully applied to overexpress three membrane proteins that were otherwise difficult to produce in E. coli. This gene expression control system can be easily applied to a broad range of existing protein expression systems and should be useful in constructing genetic circuits that require precise output signals.

The Encapsidated Genome of Microplitis demolitor Bracovirus Integrates into the Host Pseudoplusia includens ▿ ‡

PubMed Central

Beck, Markus H.; Zhang, Shu; Bitra, Kavita; Burke, Gaelen R.; Strand, Michael R.

2011-01-01

Polydnaviruses (PDVs) are symbionts of parasitoid wasps that function as gene delivery vehicles in the insects (hosts) that the wasps parasitize. PDVs persist in wasps as integrated proviruses but are packaged as circularized and segmented double-stranded DNAs into the virions that wasps inject into hosts. In contrast, little is known about how PDV genomic DNAs persist in host cells. Microplitis demolitor carries Microplitis demolitor bracovirus (MdBV) and parasitizes the host Pseudoplusia includens. MdBV infects primarily host hemocytes and also infects a hemocyte-derived cell line from P. includens called CiE1 cells. Here we report that all 15 genomic segments of the MdBV encapsidated genome exhibited long-term persistence in CiE1 cells. Most MdBV genes expressed in hemocytes were persistently expressed in CiE1 cells, including members of the glc gene family whose products transformed CiE1 cells into a suspension culture. PCR-based integration assays combined with cloning and sequencing of host-virus junctions confirmed that genomic segments J and C persisted in CiE1 cells by integration. These genomic DNAs also rapidly integrated into parasitized P. includens. Sequence analysis of wasp-viral junction clones showed that the integration of proviral segments in M. demolitor was associated with a wasp excision/integration motif (WIM) known from other bracoviruses. However, integration into host cells occurred in association with a previously unknown domain that we named the host integration motif (HIM). The presence of HIMs in most MdBV genomic DNAs suggests that the integration of each genomic segment into host cells occurs through a shared mechanism. PMID:21880747

Exosomes Secreted by Toxoplasma gondii-Infected L6 Cells: Their Effects on Host Cell Proliferation and Cell Cycle Changes

PubMed Central

Kim, Min Jae; Jung, Bong-Kwang; Cho, Jaeeun; Song, Hyemi; Pyo, Kyung-Ho; Lee, Ji Min; Kim, Min-Kyung; Chai, Jong-Yil

2016-01-01

Toxoplasma gondii infection induces alteration of the host cell cycle and cell proliferation. These changes are not only seen in directly invaded host cells but also in neighboring cells. We tried to identify whether this alteration can be mediated by exosomes secreted by T. gondii-infected host cells. L6 cells, a rat myoblast cell line, and RH strain of T. gondii were selected for this study. L6 cells were infected with or without T. gondii to isolate exosomes. The cellular growth patterns were identified by cell counting with trypan blue under confocal microscopy, and cell cycle changes were investigated by flow cytometry. L6 cells infected with T. gondii showed decreased proliferation compared to uninfected L6 cells and revealed a tendency to stay at S or G2/M cell phase. The treatment of exosomes isolated from T. gondii-infected cells showed attenuation of cell proliferation and slight enhancement of S phase in L6 cells. The cell cycle alteration was not as obvious as reduction of the cell proliferation by the exosome treatment. These changes were transient and disappeared at 48 hr after the exosome treatment. Microarray analysis and web-based tools indicated that various exosomal miRNAs were crucial for the regulation of target genes related to cell proliferation. Collectively, our study demonstrated that the exosomes originating from T. gondii could change the host cell proliferation and alter the host cell cycle. PMID:27180572

Cell wall composition profiling of parasitic giant dodder (Cuscuta reflexa) and its hosts: a priori differences and induced changes.

PubMed

Johnsen, Hanne R; Striberny, Bernd; Olsen, Stian; Vidal-Melgosa, Silvia; Fangel, Jonatan U; Willats, William G T; Rose, Jocelyn K C; Krause, Kirsten

2015-08-01

Host plant penetration is the gateway to survival for holoparasitic Cuscuta and requires host cell wall degradation. Compositional differences of cell walls may explain why some hosts are amenable to such degradation while others can resist infection. Antibody-based techniques for comprehensive profiling of cell wall epitopes and cell wall-modifying enzymes were applied to several susceptible hosts and a resistant host of Cuscuta reflexa and to the parasite itself. Infected tissue of Pelargonium zonale contained high concentrations of de-esterified homogalacturonans in the cell walls, particularly adjacent to the parasite's haustoria. High pectinolytic activity in haustorial extracts and high expression levels of pectate lyase genes suggest that the parasite contributes directly to wall remodeling. Mannan and xylan concentrations were low in P. zonale and in five susceptible tomato introgression lines, but high in the resistant Solanum lycopersicum cv M82, and in C. reflexa itself. Knowledge of the composition of resistant host cell walls and the parasite's own cell walls is useful in developing strategies to prevent infection by parasitic plants. © 2015 The Authors. New Phytologist © 2015 New Phytologist Trust.

Dynamic Fungal Cell Wall Architecture in Stress Adaptation and Immune Evasion.

PubMed

Hopke, Alex; Brown, Alistair J P; Hall, Rebecca A; Wheeler, Robert T

2018-04-01

Deadly infections from opportunistic fungi have risen in frequency, largely because of the at-risk immunocompromised population created by advances in modern medicine and the HIV/AIDS pandemic. This review focuses on dynamics of the fungal polysaccharide cell wall, which plays an outsized role in fungal pathogenesis and therapy because it acts as both an environmental barrier and as the major interface with the host immune system. Human fungal pathogens use architectural strategies to mask epitopes from the host and prevent immune surveillance, and recent work elucidates how biotic and abiotic stresses present during infection can either block or enhance masking. The signaling components implicated in regulating fungal immune recognition can teach us how cell wall dynamics are controlled, and represent potential targets for interventions designed to boost or dampen immunity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rational Design of Multifunctional Gold Nanoparticles via Host-Guest Interaction for Cancer-Targeted Therapy.

PubMed

Chen, Wei-Hai; Lei, Qi; Luo, Guo-Feng; Jia, Hui-Zhen; Hong, Sheng; Liu, Yu-Xin; Cheng, Yin-Jia; Zhang, Xian-Zheng

2015-08-12

A versatile gold nanoparticle-based multifunctional nanocomposite AuNP@CD-AD-DOX/RGD was constructed flexibly via host-guest interaction for targeted cancer chemotherapy. The pH-sensitive anticancer prodrug AD-Hyd-DOX and the cancer-targeted peptide AD-PEG8-GRGDS were modified on the surface of AuNP@CD simultaneously, which endowed the resultant nanocomposite with the capability to selectively eliminate cancer cells. In vitro studies indicated that the AuNP@CD-AD-DOX/RGD nanocomposite was preferentially uptaken by cancer cells via receptor-mediated endocytosis. Subsequently, anticancer drug DOX was released rapidly upon the intracellular trigger of the acid microenvirenment of endo/lysosomes, inducing apoptosis in cancer cells. As the ideal drug nanocarrier, the multifunctional gold nanoparticles with the active targeting and controllable intracellular release ability hold the great potential in cancer therapy.

Yersinia virulence factors - a sophisticated arsenal for combating host defences

PubMed Central

Atkinson, Steve; Williams, Paul

2016-01-01

The human pathogens Yersinia pseudotuberculosis and Yersinia enterocolitica cause enterocolitis, while Yersinia pestis is responsible for pneumonic, bubonic, and septicaemic plague. All three share an infection strategy that relies on a virulence factor arsenal to enable them to enter, adhere to, and colonise the host while evading host defences to avoid untimely clearance. Their arsenal includes a number of adhesins that allow the invading pathogens to establish a foothold in the host and to adhere to specific tissues later during infection. When the host innate immune system has been activated, all three pathogens produce a structure analogous to a hypodermic needle. In conjunction with the translocon, which forms a pore in the host membrane, the channel that is formed enables the transfer of six ‘effector’ proteins into the host cell cytoplasm. These proteins mimic host cell proteins but are more efficient than their native counterparts at modifying the host cell cytoskeleton, triggering the host cell suicide response. Such a sophisticated arsenal ensures that yersiniae maintain the upper hand despite the best efforts of the host to counteract the infecting pathogen. PMID:27347390

Alternative Polyadenylation Allows Differential Negative Feedback of Human miRNA miR-579 on Its Host Gene ZFR

PubMed Central

Hinske, Ludwig Christian; Galante, Pedro A. F.; Limbeck, Elisabeth; Möhnle, Patrick; Parmigiani, Raphael B.; Ohno-Machado, Lucila; Camargo, Anamaria A.; Kreth, Simone

2015-01-01

About half of the known miRNA genes are located within protein-coding host genes, and are thus subject to co-transcription. Accumulating data indicate that this coupling may be an intrinsic mechanism to directly regulate the host gene’s expression, constituting a negative feedback loop. Inevitably, the cell requires a yet largely unknown repertoire of methods to regulate this control mechanism. We propose APA as one possible mechanism by which negative feedback of intronic miRNA on their host genes might be regulated. Using in-silico analyses, we found that host genes that contain seed matching sites for their intronic miRNAs yield longer 32UTRs with more polyadenylation sites. Additionally, the distribution of polyadenylation signals differed significantly between these host genes and host genes of miRNAs that do not contain potential miRNA binding sites. We then transferred these in-silico results to a biological example and investigated the relationship between ZFR and its intronic miRNA miR-579 in a U87 cell line model. We found that ZFR is targeted by its intronic miRNA miR-579 and that alternative polyadenylation allows differential targeting. We additionally used bioinformatics analyses and RNA-Seq to evaluate a potential cross-talk between intronic miRNAs and alternative polyadenylation. CPSF2, a gene previously associated with alternative polyadenylation signal recognition, might be linked to intronic miRNA negative feedback by altering polyadenylation signal utilization. PMID:25799583

Microsporidia infection impacts the host cell's cycle and reduces host cell apoptosis.

PubMed

Martín-Hernández, Raquel; Higes, Mariano; Sagastume, Soledad; Juarranz, Ángeles; Dias-Almeida, Joyce; Budge, Giles E; Meana, Aránzazu; Boonham, Neil

2017-01-01

Intracellular parasites can alter the cellular machinery of host cells to create a safe haven for their survival. In this regard, microsporidia are obligate intracellular fungal parasites with extremely reduced genomes and hence, they are strongly dependent on their host for energy and resources. To date, there are few studies into host cell manipulation by microsporidia, most of which have focused on morphological aspects. The microsporidia Nosema apis and Nosema ceranae are worldwide parasites of honey bees, infecting their ventricular epithelial cells. In this work, quantitative gene expression and histology were studied to investigate how these two parasites manipulate their host's cells at the molecular level. Both these microsporidia provoke infection-induced regulation of genes involved in apoptosis and the cell cycle. The up-regulation of buffy (which encodes a pro-survival protein) and BIRC5 (belonging to the Inhibitor Apoptosis protein family) was observed after infection, shedding light on the pathways that these pathogens use to inhibit host cell apoptosis. Curiously, different routes related to cell cycle were modified after infection by each microsporidia. In the case of N. apis, cyclin B1, dacapo and E2F2 were up-regulated, whereas only cyclin E was up-regulated by N. ceranae, in both cases promoting the G1/S phase transition. This is the first report describing molecular pathways related to parasite-host interactions that are probably intended to ensure the parasite's survival within the cell.

A Tale of Two RNAs during Viral Infection: How Viruses Antagonize mRNAs and Small Non-Coding RNAs in The Host Cell

PubMed Central

Herbert, Kristina M.; Nag, Anita

2016-01-01

Viral infection initiates an array of changes in host gene expression. Many viruses dampen host protein expression and attempt to evade the host anti-viral defense machinery. Host gene expression is suppressed at several stages of host messenger RNA (mRNA) formation including selective degradation of translationally competent messenger RNAs. Besides mRNAs, host cells also express a variety of noncoding RNAs, including small RNAs, that may also be subject to inhibition upon viral infection. In this review we focused on different ways viruses antagonize coding and noncoding RNAs in the host cell to its advantage. PMID:27271653

Distribution of O-Acetylated Sialic Acids among Target Host Tissues for Influenza Virus

PubMed Central

Barnard, Karen N.; Ossiboff, Robert J.; Khedri, Zahra; Feng, Kurtis H.; Yu, Hai; Chen, Xi; Varki, Ajit

2017-01-01

ABSTRACT Sialic acids (Sias) are important glycans displayed on the cells and tissues of many different animals and are frequent targets for binding and modification by pathogens, including influenza viruses. Influenza virus hemagglutinins bind Sias during the infection of their normal hosts, while the encoded neuraminidases and/or esterases remove or modify the Sia to allow virion release or to prevent rebinding. Sias naturally occur in a variety of modified forms, and modified Sias can alter influenza virus host tropisms through their altered interactions with the viral glycoproteins. However, the distribution of modified Sia forms and their effects on pathogen-host interactions are still poorly understood. Here we used probes developed from viral Sia-binding proteins to detect O-acetylated (4-O-acetyl, 9-O-acetyl, and 7,9-O-acetyl) Sias displayed on the tissues of some natural or experimental hosts for influenza viruses. These modified Sias showed highly variable displays between the hosts and tissues examined. The 9-O-acetyl (and 7,9-) modified Sia forms were found on cells and tissues of many hosts, including mice, humans, ferrets, guinea pigs, pigs, horses, dogs, as well as in those of ducks and embryonated chicken egg tissues and membranes, although in variable amounts. The 4-O-acetyl Sias were found in the respiratory tissues of fewer animals, being primarily displayed in the horse and guinea pig, but were not detected in humans or pigs. The results suggest that these Sia variants may influence virus tropisms by altering and selecting their cell interactions. IMPORTANCE Sialic acids (Sias) are key glycans that control or modulate many normal cell and tissue functions while also interacting with a variety of pathogens, including many different viruses. Sias are naturally displayed in a variety of different forms, with modifications at several positions that can alter their functional interactions with pathogens. In addition, Sias are often modified or removed by enzymes such as host or pathogen esterases or sialidases (neuraminidases), and Sia modifications can alter those enzymatic activities to impact pathogen infections. Sia chemical diversity in different hosts and tissues likely alters the pathogen-host interactions and influences the outcome of infection. Here we explored the display of 4-O-acetyl, 9-O-acetyl, and 7,9-O-acetyl modified Sia forms in some target tissues for influenza virus infection in mice, humans, birds, guinea pigs, ferrets, swine, horses, and dogs, which encompass many natural and laboratory hosts of those viruses. PMID:28904995

The Plasmodium falciparum pseudoprotease SERA5 regulates the kinetics and efficiency of malaria parasite egress from host erythrocytes

PubMed Central

Hackett, Fiona; Atid, Jonathan; Tan, Michele Ser Ying

2017-01-01

Egress of the malaria parasite Plasmodium falciparum from its host red blood cell is a rapid, highly regulated event that is essential for maintenance and completion of the parasite life cycle. Egress is protease-dependent and is temporally associated with extensive proteolytic modification of parasite proteins, including a family of papain-like proteins called SERA that are expressed in the parasite parasitophorous vacuole. Previous work has shown that the most abundant SERA, SERA5, plays an important but non-enzymatic role in asexual blood stages. SERA5 is extensively proteolytically processed by a parasite serine protease called SUB1 as well as an unidentified cysteine protease just prior to egress. However, neither the function of SERA5 nor the role of its processing is known. Here we show that conditional disruption of the SERA5 gene, or of both the SERA5 and related SERA4 genes simultaneously, results in a dramatic egress and replication defect characterised by premature host cell rupture and the failure of daughter merozoites to efficiently disseminate, instead being transiently retained within residual bounding membranes. SERA5 is not required for poration (permeabilization) or vesiculation of the host cell membrane at egress, but the premature rupture phenotype requires the activity of a parasite or host cell cysteine protease. Complementation of SERA5 null parasites by ectopic expression of wild-type SERA5 reversed the egress defect, whereas expression of a SERA5 mutant refractory to processing failed to rescue the phenotype. Our findings implicate SERA5 as an important regulator of the kinetics and efficiency of egress and suggest that proteolytic modification is required for SERA5 function. In addition, our study reveals that efficient egress requires tight control of the timing of membrane rupture. PMID:28683142

Small bite, large impact-saliva and salivary molecules in the medicinal leech, Hirudo medicinalis

NASA Astrophysics Data System (ADS)

Hildebrandt, Jan-Peter; Lemke, Sarah

2011-12-01

Blood-sucking leeches have been used for medical purposes in humans for hundreds of years. Accordingly, one of the most prominent species has been named Hirudo medicinalis by Carl Linne in 1758. Feeding on vertebrate blood poses some serious problems to blood-sucking ectoparasites, as they have to penetrate the body surface of the host and to suppress the normal reactions of the host to such injuries (swelling, pain, inflammation) to remain undetected during the feeding period. Furthermore, the parasites have to take measures to inhibit the normal reactions in host tissues to blood vessel damage, namely hemostasis and blood coagulation (platelet aggregation and activation, activation of thrombin and formation of fibrin clots). During evolution, leeches have acquired the ability to control these processes in their hosts by transferring various bioactive substances to the host. These substances are supposedly produced in unicellular salivary gland cells and injected into the wound at the feeding site through tiny salivary ductule openings in the jaws that the leech uses to slice open the host body surface and to cut blood vessels in the depth of the wound. This review summarizes current knowledge about the salivary gland cells and the biological effects of individual saliva components as well as hints to the potential usefulness of some of these compounds for medical purposes.

How pathogens use linear motifs to perturb host cell networks.

PubMed

Via, Allegra; Uyar, Bora; Brun, Christine; Zanzoni, Andreas

2015-01-01

Molecular mimicry is one of the powerful stratagems that pathogens employ to colonise their hosts and take advantage of host cell functions to guarantee their replication and dissemination. In particular, several viruses have evolved the ability to interact with host cell components through protein short linear motifs (SLiMs) that mimic host SLiMs, thus facilitating their internalisation and the manipulation of a wide range of cellular networks. Here we present convincing evidence from the literature that motif mimicry also represents an effective, widespread hijacking strategy in prokaryotic and eukaryotic parasites. Further insights into host motif mimicry would be of great help in the elucidation of the molecular mechanisms behind host cell invasion and the development of anti-infective therapeutic strategies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mycobacterium tuberculosis PE13 (Rv1195) manipulates the host cell fate via p38-ERK-NF-κB axis and apoptosis.

PubMed

Li, Hui; Li, Qiming; Yu, Zhaoxiao; Zhou, Mingliang; Xie, Jianping

2016-07-01

PE/PPE family proteins are mycobacteria unique molecules, named after their N-terminal conserved PE (Pro-Glu) and PPE (Pro-Pro-Glu) domains. Mycobacterium tuberculosis (Mtb) PE family gene encoded cell surface proteins are previously reported to be involved in virulence and interaction with host. To explore the role of a novel PE member (PE13, Rv1195), M. smegmatis was used as surrogate host. The study showed that Rv1195 was a cell wall associated protein. Rv1195 can enhance the survival of recombinants under stress conditions such as H2O2, SDS, low pH. This is largely due to the upregulated transcription of Rv1195, since diverse stresses can increase the promoter activity of Rv1195 gene, consistent with enhanced survival within macrophages. Ms_Rv1195 infection also increased the production of interlukin-6 (IL-6) and IL-1β from macrophages, while decreased the secretion of suppressor of cytokine signaling 3 (SOCS3) in comparison with the vector-only control. The cell death was also precipitated by the Ms_Rv1195 infection. Inhibitors treatment showed that the p38-ERK-NF-κB axis was involved in the Rv1195 triggered change of IL-6 and IL-1β expression. In summary, we showed that PE13 (Rv1195) is a new PE family member actively engaged in the interaction between Mycobacterium and host, signaling through p38-ERK-NF-κB axis and apoptosis.

Mechanism of dexamethasone in the context of Toxoplasma gondii infection.

PubMed

Zhang, Jing; Qin, Xin; Zhu, Y U; Zhang, Shuang; Zhang, Xue-Wei; Lu, H E

2017-09-01

Toxoplasmosis is a serious zoonoses disease and opportunistic, and can be life-threatening. Dexamethasone (DEX) is widely used in the clinic for treatment of inflammatory and autoimmune diseases. However, long-term use of DEX is often easy to lead to acute toxoplasmosis in patients, and the potential molecular mechanism is still not very clear. The aims of this study were to investigate the effect of DEX on proliferation of Toxoplasma and its molecular mechanisms, and to establish the corresponding control measures. All the results showed that dexamethasone could enhance the proliferation of Toxoplasma gondii tachyzoites. After 72 h of DEX treatment, 566 (±7) tachyzoites were found in 100 host cells, while only 86 (±8) tachyzoites were counted from the non-treated control cells (P < 0·01). Gas chromatography (GC) analysis showed changes in level and composition of fatty acids in DEX-treated host cells, and T. gondii. Fish oil was added as a modulator of lipid metabolism in experimental mice. It was found that mice fed with fish oil did not develop the disease after infection with T. gondii, and the structure of fatty acids in plasma changed significantly. The metabolism of fatty acid in the parasites was limited, and the desaturase gene expression was downregulated. These results indicate that the molecular mechanism of dexamethasone to promote the proliferation of T. gondii may be that dexamethasone induces the change of fatty acids composition of tachyzoites and host cells. Therefore, we recommend supplementation of fatty acid in immunosuppressive and immunocompromised patients in order to inhibit toxoplasmosis.

Heme-Oxygenase-1 Expression Contributes to the Immunoregulation Induced by Fasciola hepatica and Promotes Infection

PubMed Central

Carasi, Paula; Rodríguez, Ernesto; da Costa, Valeria; Frigerio, Sofía; Brossard, Natalie; Noya, Verónica; Robello, Carlos; Anegón, Ignacio; Freire, Teresa

2017-01-01

Fasciola hepatica, also known as the liver fluke, is a trematode that infects livestock and humans causing fasciolosis, a zoonotic disease of increasing importance due to its worldwide distribution and high economic losses. This parasite immunoregulates the host immune system by inducing a strong Th2 and regulatory T immune response by immunomodulating dendritic cell (DC) maturation and alternative activation of macrophages. In this paper, we show that F. hepatica infection in mice induces the upregulation of heme-oxygenase-1 (HO-1), the rate-limiting enzyme in the catabolism of free heme that regulates the host inflammatory response. We show and characterize two different populations of antigen presenting cells that express HO-1 during infection in the peritoneum of infected animals. Cells that expressed high levels of HO-1 expressed intermediate levels of F4/80 but high expression of CD11c, CD38, TGFβ, and IL-10 suggesting that they correspond to regulatory DCs. On the other hand, cells expressing intermediate levels of HO-1 expressed high levels of F4/80, CD68, Ly6C, and FIZZ-1, indicating that they might correspond to alternatively activated macrophages. Furthermore, the pharmacological induction of HO-1 with the synthetic metalloporphyrin CoPP promoted F. hepatica infection increasing the clinical signs associated with the disease. In contrast, treatment with the HO-1 inhibitor SnPP protected mice from parasite infection, indicating that HO-1 plays an essential role during F. hepatica infection. Finally, HO-1 expression during F. hepatica infection was associated with TGFβ and IL-10 levels in liver and peritoneum, suggesting that HO-1 controls the expression of these immunoregulatory cytokines during infection favoring parasite survival in the host. These results contribute to the elucidation of the immunoregulatory mechanisms induced by F. hepatica in the host and provide alternative checkpoints to control fasciolosis. PMID:28798750

Heme-Oxygenase-1 Expression Contributes to the Immunoregulation Induced by Fasciola hepatica and Promotes Infection.

PubMed

Carasi, Paula; Rodríguez, Ernesto; da Costa, Valeria; Frigerio, Sofía; Brossard, Natalie; Noya, Verónica; Robello, Carlos; Anegón, Ignacio; Freire, Teresa

2017-01-01

Fasciola hepatica , also known as the liver fluke, is a trematode that infects livestock and humans causing fasciolosis, a zoonotic disease of increasing importance due to its worldwide distribution and high economic losses. This parasite immunoregulates the host immune system by inducing a strong Th2 and regulatory T immune response by immunomodulating dendritic cell (DC) maturation and alternative activation of macrophages. In this paper, we show that F. hepatica infection in mice induces the upregulation of heme-oxygenase-1 (HO-1), the rate-limiting enzyme in the catabolism of free heme that regulates the host inflammatory response. We show and characterize two different populations of antigen presenting cells that express HO-1 during infection in the peritoneum of infected animals. Cells that expressed high levels of HO-1 expressed intermediate levels of F4/80 but high expression of CD11c, CD38, TGFβ, and IL-10 suggesting that they correspond to regulatory DCs. On the other hand, cells expressing intermediate levels of HO-1 expressed high levels of F4/80, CD68, Ly6C, and FIZZ-1, indicating that they might correspond to alternatively activated macrophages. Furthermore, the pharmacological induction of HO-1 with the synthetic metalloporphyrin CoPP promoted F. hepatica infection increasing the clinical signs associated with the disease. In contrast, treatment with the HO-1 inhibitor SnPP protected mice from parasite infection, indicating that HO-1 plays an essential role during F. hepatica infection. Finally, HO-1 expression during F. hepatica infection was associated with TGFβ and IL-10 levels in liver and peritoneum, suggesting that HO-1 controls the expression of these immunoregulatory cytokines during infection favoring parasite survival in the host. These results contribute to the elucidation of the immunoregulatory mechanisms induced by F. hepatica in the host and provide alternative checkpoints to control fasciolosis.

Interleukin-10 Gene-Modified Dendritic Cell-Induced Type 1 Regulatory T Cells Induce Transplant-Tolerance and Impede Graft Versus Host Disease After Allogeneic Stem Cell Transplantation.

PubMed

Wan, Jiangbo; Huang, Fang; Hao, Siguo; Hu, Weiwei; Liu, Chuanxu; Zhang, Wenhao; Deng, Xiaohui; Chen, Linjun; Ma, Liyuan; Tao, Rong

2017-01-01

Tr1 cells can induce peripheral tolerance to self- and foreign antigens, and have been developed as a therapeutic tool for the induction of tolerance to transplanted tissue. We explored the feasibility of generating Tr1 cells by using IL-10 gene-modified recipient DCs (DCLV-IL-10) to stimulate donor naive CD4+ T cells. We also investigated some biological properties of Tr1 cells. DCLV-IL-10 were generated through DCs transduced with a lentivirus vector carrying the IL-10 gene, and Tr1 cells were produced by using DCLV-IL-10 to stimulate naive CD4+ T cells. The effects of Tr1 cells on T-cell proliferation and the occurrence of graft versus host disease (GVHD) following allogeneic stem-cell transplantation (allo-HSCT) were investigated. The DCLV-IL-10-induced Tr1 cells co-expressed LAG-3 and CD49b. Moreover, they also expressed CD4, CD25, and IL-10, but not Foxp3, and secreted significantly higher levels of IL-10 (1,729.36 ± 185.79 pg/mL; P < 0.001) and INF-γ (1,524.48 ± 168.65 pg/mL; P < 0.01) than the control T cells upon the stimulation by allogeneic DCs. Tr1 cells markedly suppressed T-lymphocyte proliferation and the mixed lymphocytic response (MLR) in vitro. The mice used in the allo-HSCT model had longer survival times and lower clinical and pathological GVHD scores than the control mice. IL-10 gene-modified DC-induced Tr1 cells may be used as a potent cellular therapy for the prevention of GVHD after allo-HSCT. © 2017 The Author(s). Published by S. Karger AG, Basel.

Chlamydia Infection Across Host Species Boundaries Promotes Distinct Sets of Transcribed Anti-Apoptotic Factors

PubMed Central

Messinger, Joshua E.; Nelton, Emmalin; Feeney, Colleen; Gondek, David C.

2015-01-01

Chlamydiae, obligate intracellular bacteria, cause significant human and veterinary associated diseases. Having emerged an estimated 700-million years ago, these bacteria have twice adapted to humans as a host species, causing sexually transmitted infection (C. trachomatis) and respiratory associated disease (C. pneumoniae). The principle mechanism of host cell defense against these intracellular bacteria is the induction of cell death via apoptosis. However, in the “arms race” of co-evolution, Chlamydiae have developed mechanisms to promote cell viability and inhibit cell death. Herein we examine the impact of Chlamydiae infection across multiple host species on transcription of anti-apoptotic genes. We found mostly distinct patterns of gene expression (Mcl1 and cIAPs) elicited by each pathogen-host pair indicating Chlamydiae infection across host species boundaries does not induce a universally shared host response. Understanding species specific host-pathogen interactions is paramount to deciphering how potential pathogens become emerging diseases. PMID:26779446

Evaluation of nanoparticles as endocytic tracers in cellular microbiology

NASA Astrophysics Data System (ADS)

Zhang, Yuying; Hensel, Michael

2013-09-01

The study of pathogen interactions with eukaryotic host cells requires the introduction of fluorescent probes to visualize processes such as endocytosis, intracellular transport or host cell manipulation by the pathogen. Here, three types of fluorescent nanoparticles (NPs), i.e. Rhodamine-labeled polymethacrylate (PMA) NPs, silica NPs and gold NPs, were employed to label the host cellular endolysosomal system and monitor manipulations by the pathogen Salmonella enterica. Using live cell imaging, we investigated the performance of NPs in cellular uptake, labeling of endocytic vesicles and lysosomes, as well as interaction with the pathogen. We show that fluorescent gold and silica, but not PMA NPs appropriately label host cell structures and efficiently track rearrangements of the host endosomal system by the activities of intracellular Salmonella. Silica NPs slightly aggregated and located in Salmonella-induced compartments as isolated dots, while gold NPs distributed uniformly inside such structures. Both silica and gold NPs exhibited no adverse impact on either host cells or pathogens, and are versatile tools for infection biology.The study of pathogen interactions with eukaryotic host cells requires the introduction of fluorescent probes to visualize processes such as endocytosis, intracellular transport or host cell manipulation by the pathogen. Here, three types of fluorescent nanoparticles (NPs), i.e. Rhodamine-labeled polymethacrylate (PMA) NPs, silica NPs and gold NPs, were employed to label the host cellular endolysosomal system and monitor manipulations by the pathogen Salmonella enterica. Using live cell imaging, we investigated the performance of NPs in cellular uptake, labeling of endocytic vesicles and lysosomes, as well as interaction with the pathogen. We show that fluorescent gold and silica, but not PMA NPs appropriately label host cell structures and efficiently track rearrangements of the host endosomal system by the activities of intracellular Salmonella. Silica NPs slightly aggregated and located in Salmonella-induced compartments as isolated dots, while gold NPs distributed uniformly inside such structures. Both silica and gold NPs exhibited no adverse impact on either host cells or pathogens, and are versatile tools for infection biology. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01550e

Interactions of Cryptococcus with Dendritic Cells

PubMed Central

Wozniak, Karen L.

2018-01-01

The fungal pathogens Cryptococcus neoformans and Cryptococcus gattii can cause life-threatening infections in immune compromised and immune competent hosts. These pathogens enter the host via inhalation, and respiratory tract innate immune cells such as dendritic cells (DCs) are one of the first host cells they encounter. The interactions between Cryptococcus and innate immune cells play a critical role in the progression of disease in the host. This review will focus specifically on the interactions between Cryptococcus and dendritic cells (DCs), including recognition/processing by DCs, effects of immune mediators on DC recruitment and activity, and the potential for DC vaccination against cryptococcosis. PMID:29543719

Interactions of Cryptococcus with Dendritic Cells.

PubMed

Wozniak, Karen L

2018-03-15

The fungal pathogens Cryptococcus neoformans and Cryptococcus gattii can cause life-threatening infections in immune compromised and immune competent hosts. These pathogens enter the host via inhalation, and respiratory tract innate immune cells such as dendritic cells (DCs) are one of the first host cells they encounter. The interactions between Cryptococcus and innate immune cells play a critical role in the progression of disease in the host. This review will focus specifically on the interactions between Cryptococcus and dendritic cells (DCs), including recognition/processing by DCs, effects of immune mediators on DC recruitment and activity, and the potential for DC vaccination against cryptococcosis.

Remodeling of the malaria parasite and host human red cell by vesicle amplification that induces artemisinin resistance

PubMed Central

Coppens, Isabelle; Mbengue, Alassane; Suresh, Niraja; Ghorbal, Mehdi; Slouka, Zdenek; Safeukui, Innocent; Tang, Hsin-Yao; Speicher, David W.; Stahelin, Robert V.; Mohandas, Narla

2018-01-01

Artemisinin resistance threatens worldwide malaria control and elimination. Elevation of phosphatidylinositol-3-phosphate (PI3P) can induce resistance in blood stages of Plasmodium falciparum. The parasite unfolded protein response (UPR) has also been implicated as a proteostatic mechanism that may diminish artemisinin-induced toxic proteopathy. How PI3P acts and its connection to the UPR remain unknown, although both are conferred by mutation in P falciparum Kelch13 (K13), the marker of artemisinin resistance. Here we used cryoimmunoelectron microscopy to show that K13 concentrates at PI3P tubules/vesicles of the parasite’s endoplasmic reticulum (ER) in infected red cells. K13 colocalizes and copurifies with the major virulence adhesin PfEMP1. The PfEMP1-K13 proteome is comprehensively enriched in multiple proteostasis systems of protein export, quality control, and folding in the ER and cytoplasm and UPR. Synthetic elevation of PI3P that induces resistance in absence of K13 mutation also yields signatures of proteostasis and clinical resistance. These findings imply a key role for PI3P-vesicle amplification as a mechanism of resistance of infected red cells. As validation, the major resistance mutation K13C580Y quantitatively increased PI3P tubules/vesicles, exporting them throughout the parasite and the red cell. Chemical inhibitors and fluorescence microscopy showed that alterations in PfEMP1 export to the red cell and cytoadherence of infected cells to a host endothelial receptor are features of multiple K13 mutants. Together these data suggest that amplified PI3P vesicles disseminate widespread proteostatic capacity that may neutralize artemisinins toxic proteopathy and implicate a role for the host red cell in artemisinin resistance. The mechanistic insights generated will have an impact on malaria drug development. PMID:29363540

Nitric Oxide in the Offensive Strategy of Fungal and Oomycete Plant Pathogens

PubMed Central

Arasimowicz-Jelonek, Magdalena; Floryszak-Wieczorek, Jolanta

2016-01-01

In the course of evolutionary changes pathogens have developed many invasion strategies, to which the host organisms responded with a broad range of defense reactions involving endogenous signaling molecules, such as nitric oxide (NO). There is evidence that pathogenic microorganisms, including two most important groups of eukaryotic plant pathogens, also acquired the ability to synthesize NO via non-unequivocally defined oxidative and/or reductive routes. Although the both kingdoms Chromista and Fungi are remarkably diverse, the experimental data clearly indicate that pathogen-derived NO is an important regulatory molecule controlling not only developmental processes, but also pathogen virulence and its survival in the host. An active control of mitigation or aggravation of nitrosative stress within host cells seems to be a key determinant for the successful invasion of plant pathogens representing different lifestyles and an effective mode of dispersion in various environmental niches. PMID:26973690

The Use of High Pressure Freezing and Freeze Substitution to Study Host-Pathogen Interactions in Fungal Diseases of Plants

NASA Astrophysics Data System (ADS)

Mims, C. W.; Celio, Gail J.; Richardson, Elizabeth A.

2003-12-01

This article reports on the use of high pressure freezing followed by freeze substitution (HPF/FS) to study ultrastructural details of host pathogen interactions in fungal diseases of plants. The specific host pathogen systems discussed here include a powdery mildew infection of poinsettia and rust infections of daylily and Indian strawberry. The three pathogens considered here all attack the leaves of their hosts and produce specialized hyphal branches known as haustoria that invade individual host cells without killing them. We found that HPF/FS provided excellent preservation of both haustoria and host cells for all three host pathogen systems. Preservation of fungal and host cell membranes was particularly good and greatly facilitated the detailed study of host pathogen interfaces. In some instances, HPF/FS provided information that was not available in samples prepared for study using conventional chemical fixation. On the other hand, we did encounter various problems associated with the use of HPF/FS. Examples included freeze damage of samples, inconsistency of fixation in different samples, separation of plant cell cytoplasm from cell walls, breakage of cell walls and membranes, and splitting of thin sections. However, we believe that the outstanding preservation of ultrastructural details afforded by HPF/FS significantly outweighs these problems and we highly recommend the use of this fixation protocol for future studies of fungal host-plant interactions.

Role of CD8 Regulatory T Cells versus Tc1 and Tc17 Cells in the Development of Human Graft-versus-Host Disease.

PubMed

Gutiérrez-Hoya, Adriana; López-Santiago, Rubén; Vela-Ojeda, Jorge; Montiel-Cervantes, Laura; Rodríguez-Cortés, Octavio; Rosales-García, Víctor; Paredes-Cervantes, Vladimir; Flores-Mejía, Raúl; Sandoval-Borrego, Daniela; Moreno-Lafont, Martha

2017-01-01

CD8 + T cells that secrete proinflammatory cytokines play a central role in exacerbation of inflammation; however, a new subpopulation of CD8 regulatory T cells has recently been characterized. This study analyzes the prominent role of these different subpopulations in the development of graft-versus-host disease (GVHD). Samples from 8 healthy donors mobilized with Filgrastim® (G-CSF) and 18 patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) were evaluated by flow cytometry. Mobilization induced an increase in Tc1 ( p < 0.01), Th1 ( p < 0.001), Tc17 ( p < 0.05), and CD8 + IL-10 + cells ( p < 0.05), showing that G-CSF induces both pro- and anti-inflammatory profiles. Donor-patient correlation revealed a trend ( p = 0.06) toward the development of GVHD in patients who receive a high percentage of Tc1 cells. Patients with acute GVHD (aGVHD), either active or controlled, and patients without GVHD were evaluated; patients with active aGVHD had a higher percentage of Tc1 ( p < 0.01) and Tc17 ( p < 0.05) cells, as opposed to patients without GVHD in whom a higher percentage of CD8 Treg cells ( p < 0.01) was found. These findings indicate that the increase in Tc1 and Tc17 cells is associated with GVHD development, while regulatory CD8 T cells might have a protective role in this disease. These tests can be used to monitor and control GVHD.

Role of CD8 Regulatory T Cells versus Tc1 and Tc17 Cells in the Development of Human Graft-versus-Host Disease

PubMed Central

Gutiérrez-Hoya, Adriana; López-Santiago, Rubén; Vela-Ojeda, Jorge; Montiel-Cervantes, Laura; Rodríguez-Cortés, Octavio; Rosales-García, Víctor; Flores-Mejía, Raúl; Sandoval-Borrego, Daniela

2017-01-01

CD8+ T cells that secrete proinflammatory cytokines play a central role in exacerbation of inflammation; however, a new subpopulation of CD8 regulatory T cells has recently been characterized. This study analyzes the prominent role of these different subpopulations in the development of graft-versus-host disease (GVHD). Samples from 8 healthy donors mobilized with Filgrastim® (G-CSF) and 18 patients who underwent allogeneic hematopoietic stem cell transplantation (HSCT) were evaluated by flow cytometry. Mobilization induced an increase in Tc1 (p < 0.01), Th1 (p < 0.001), Tc17 (p < 0.05), and CD8+IL-10+ cells (p < 0.05), showing that G-CSF induces both pro- and anti-inflammatory profiles. Donor-patient correlation revealed a trend (p = 0.06) toward the development of GVHD in patients who receive a high percentage of Tc1 cells. Patients with acute GVHD (aGVHD), either active or controlled, and patients without GVHD were evaluated; patients with active aGVHD had a higher percentage of Tc1 (p < 0.01) and Tc17 (p < 0.05) cells, as opposed to patients without GVHD in whom a higher percentage of CD8 Treg cells (p < 0.01) was found. These findings indicate that the increase in Tc1 and Tc17 cells is associated with GVHD development, while regulatory CD8 T cells might have a protective role in this disease. These tests can be used to monitor and control GVHD. PMID:28164135

In vivo Host Environment Alters Pseudomonas aeruginosa Susceptibility to Aminoglycoside Antibiotics

PubMed Central

Pan, Xiaolei; Dong, Yuanyuan; Fan, Zheng; Liu, Chang; Xia, Bin; Shi, Jing; Bai, Fang; Jin, Yongxin; Cheng, Zhihui; Jin, Shouguang; Wu, Weihui

2017-01-01

During host infection, Pseudomonas aeruginosa coordinately regulates the expression of numerous genes to adapt to the host environment while counteracting host clearance mechanisms. As infected patients take antibiotics, the invading bacteria encounter antibiotics in the host milieu. P. aeruginosa is highly resistant to antibiotics due to multiple chromosomally encoded resistant determinants. And numerous in vitro studies have demonstrated the regulatory mechanisms of antibiotic resistance related genes in response to antibiotics. However, it is not well-known how host environment affects bacterial response to antibiotics. In this study, we found that P. aeruginosa cells directly isolated from mice lungs displayed higher susceptibility to tobramycin than in vitro cultured bacteria. In vitro experiments demonstrated that incubation with A549 and differentiated HL60 (dHL60) cells sensitized P. aeruginosa to tobramycin. Further studies revealed that reactive oxygen species produced by the host cells contributed to the increased bacterial susceptibility. At the same concentration of tobramycin, presence of A549 and dHL60 cells resulted in higher expression of heat shock proteins, which are known inducible by tobramycin. Further analyses revealed decreased membrane potential upon incubation with the host cells and modification of lipopolysaccharide, which contributed to the increased susceptibility to tobramycin. Therefore, our results demonstrate that contact with host cells increased bacterial susceptibility to tobramycin. PMID:28352614

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells.

PubMed

Wunsch, Christopher M; Lewis, Janina P

2015-12-17

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth. The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2',7'-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal-spatial visualization of bacteria. Methods used in this study can be applied to any cultivable anaerobe and any eukaryotic cell type.

Porphyromonas gingivalis as a Model Organism for Assessing Interaction of Anaerobic Bacteria with Host Cells

PubMed Central

Wunsch, Christopher M.; Lewis, Janina P.

2015-01-01

Anaerobic bacteria far outnumber aerobes in many human niches such as the gut, mouth, and vagina. Furthermore, anaerobic infections are common and frequently of indigenous origin. The ability of some anaerobic pathogens to invade human cells gives them adaptive measures to escape innate immunity as well as to modulate host cell behavior. However, ensuring that the anaerobic bacteria are live during experimental investigation of the events may pose challenges. Porphyromonas gingivalis, a Gram-negative anaerobe, is capable of invading a variety of eukaryotic non-phagocytic cells. This article outlines how to successfully culture and assess the ability of P. gingivalis to invade human umbilical vein endothelial cells (HUVECs). Two protocols were developed: one to measure bacteria that can successfully invade and survive within the host, and the other to visualize bacteria interacting with host cells. These techniques necessitate the use of an anaerobic chamber to supply P. gingivalis with an anaerobic environment for optimal growth. The first protocol is based on the antibiotic protection assay, which is largely used to study the invasion of host cells by bacteria. However, the antibiotic protection assay is limited; only intracellular bacteria that are culturable following antibiotic treatment and host cell lysis are measured. To assess all bacteria interacting with host cells, both live and dead, we developed a protocol that uses fluorescent microscopy to examine host-pathogen interaction. Bacteria are fluorescently labeled with 2',7'-Bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) and used to infect eukaryotic cells under anaerobic conditions. Following fixing with paraformaldehyde and permeabilization with 0.2% Triton X-100, host cells are labeled with TRITC phalloidin and DAPI to label the cell cytoskeleton and nucleus, respectively. Multiple images taken at different focal points (Z-stack) are obtained for temporal-spatial visualization of bacteria. Methods used in this study can be applied to any cultivable anaerobe and any eukaryotic cell type. PMID:26709454

Host-specific parvovirus evolution in nature is recapitulated by in vitro adaptation to different carnivore species.

PubMed

Allison, Andrew B; Kohler, Dennis J; Ortega, Alicia; Hoover, Elizabeth A; Grove, Daniel M; Holmes, Edward C; Parrish, Colin R

2014-11-01

Canine parvovirus (CPV) emerged as a new pandemic pathogen of dogs in the 1970s and is closely related to feline panleukopenia virus (FPV), a parvovirus of cats and related carnivores. Although both viruses have wide host ranges, analysis of viral sequences recovered from different wild carnivore species, as shown here, demonstrated that>95% were derived from CPV-like viruses, suggesting that CPV is dominant in sylvatic cycles. Many viral sequences showed host-specific mutations in their capsid proteins, which were often close to sites known to control binding to the transferrin receptor (TfR), the host receptor for these carnivore parvoviruses, and which exhibited frequent parallel evolution. To further examine the process of host adaptation, we passaged parvoviruses with alternative backgrounds in cells from different carnivore hosts. Specific mutations were selected in several viruses and these differed depending on both the background of the virus and the host cells in which they were passaged. Strikingly, these in vitro mutations recapitulated many specific changes seen in viruses from natural populations, strongly suggesting they are host adaptive, and which were shown to result in fitness advantages over their parental virus. Comparison of the sequences of the transferrin receptors of the different carnivore species demonstrated that many mutations occurred in and around the apical domain where the virus binds, indicating that viral variants were likely selected through their fit to receptor structures. Some of the viruses accumulated high levels of variation upon passage in alternative hosts, while others could infect multiple different hosts with no or only a few additional mutations. Overall, these studies demonstrate that the evolutionary history of a virus, including how long it has been circulating and in which hosts, as well as its phylogenetic background, has a profound effect on determining viral host range.

Host-Specific Parvovirus Evolution in Nature Is Recapitulated by In Vitro Adaptation to Different Carnivore Species

PubMed Central

Allison, Andrew B.; Kohler, Dennis J.; Ortega, Alicia; Hoover, Elizabeth A.; Grove, Daniel M.; Holmes, Edward C.; Parrish, Colin R.

2014-01-01

Canine parvovirus (CPV) emerged as a new pandemic pathogen of dogs in the 1970s and is closely related to feline panleukopenia virus (FPV), a parvovirus of cats and related carnivores. Although both viruses have wide host ranges, analysis of viral sequences recovered from different wild carnivore species, as shown here, demonstrated that >95% were derived from CPV-like viruses, suggesting that CPV is dominant in sylvatic cycles. Many viral sequences showed host-specific mutations in their capsid proteins, which were often close to sites known to control binding to the transferrin receptor (TfR), the host receptor for these carnivore parvoviruses, and which exhibited frequent parallel evolution. To further examine the process of host adaptation, we passaged parvoviruses with alternative backgrounds in cells from different carnivore hosts. Specific mutations were selected in several viruses and these differed depending on both the background of the virus and the host cells in which they were passaged. Strikingly, these in vitro mutations recapitulated many specific changes seen in viruses from natural populations, strongly suggesting they are host adaptive, and which were shown to result in fitness advantages over their parental virus. Comparison of the sequences of the transferrin receptors of the different carnivore species demonstrated that many mutations occurred in and around the apical domain where the virus binds, indicating that viral variants were likely selected through their fit to receptor structures. Some of the viruses accumulated high levels of variation upon passage in alternative hosts, while others could infect multiple different hosts with no or only a few additional mutations. Overall, these studies demonstrate that the evolutionary history of a virus, including how long it has been circulating and in which hosts, as well as its phylogenetic background, has a profound effect on determining viral host range. PMID:25375184

Viruses and miRNAs: More Friends than Foes.

PubMed

Bruscella, Patrice; Bottini, Silvia; Baudesson, Camille; Pawlotsky, Jean-Michel; Feray, Cyrille; Trabucchi, Michele

2017-01-01

There is evidence that eukaryotic miRNAs (hereafter called host miRNAs) play a role in the replication and propagation of viruses. Expression or targeting of host miRNAs can be involved in cellular antiviral responses. Most times host miRNAs play a role in viral life-cycles and promote infection through complex regulatory pathways. miRNAs can also be encoded by a viral genome and be expressed in the host cell. Viral miRNAs can share common sequences with host miRNAs or have totally different sequences. They can regulate a variety of biological processes involved in viral infection, including apoptosis, evasion of the immune response, or modulation of viral life-cycle phases. Overall, virus/miRNA pathway interaction is defined by a plethora of complex mechanisms, though not yet fully understood. This article review summarizes recent advances and novel biological concepts related to the understanding of miRNA expression, control and function during viral infections. The article also discusses potential therapeutic applications of this particular host-pathogen interaction.

Silencing cytokeratin 18 gene inhibits intracellular replication of Trypanosoma cruzi in HeLa cells but not binding and invasion of trypanosomes.

PubMed

Claser, Carla; Curcio, Marli; de Mello, Samanta M; Silveira, Eduardo V; Monteiro, Hugo P; Rodrigues, Mauricio M

2008-12-17

As an obligatory intracellular parasite, Trypanosoma cruzi, the etiological agent of Chagas' disease, must invade and multiply within mammalian cells. Cytokeratin 18 (CK18) is among the host molecules that have been suggested as a mediator of important events during T. cruzi-host cell interaction. Based on that possibility, we addressed whether RNA interference (RNAi)-mediated down regulation of the CK18 gene could interfere with the parasite life cycle in vitro. HeLa cells transiently transfected with CK18-RNAi had negligible levels of CK18 transcripts, and significantly reduced levels of CK18 protein expression as determined by immunoblotting or immunofluorescence. CK18 negative or positive HeLa cells were invaded equally as well by trypomastigotes of different T. cruzi strains. Also, in CK18 negative or positive cells, parasites recruited host cells lysosomes and escaped from the parasitophorous vacuole equally as well. After that, the growth of amastigotes of the Y or CL-Brener strains, was drastically arrested in CK18 RNAi-treated cells. After 48 hours, the number of amastigotes was several times lower in CK18 RNAi-treated cells when compared to control cells. Simultaneous staining of parasites and CK18 showed that in HeLa cells infected with the Y strain both co-localize. Although the amastigote surface protein-2 contains the domain VTVXNVFLYNR previously described to bind to CK18, in several attempts, we failed to detect binding of a recombinant protein to CK-18. The study demonstrates that silencing CK18 by transient RNAi, inhibits intracellular multiplication of the Y and CL strain of T. cruzi in HeLa cells, but not trypanosome binding and invasion.

Silencing cytokeratin 18 gene inhibits intracellular replication of Trypanosoma cruzi in HeLa cells but not binding and invasion of trypanosomes

PubMed Central

Claser, Carla; Curcio, Marli; de Mello, Samanta M; Silveira, Eduardo V; Monteiro, Hugo P; Rodrigues, Mauricio M

2008-01-01

Background As an obligatory intracellular parasite, Trypanosoma cruzi, the etiological agent of Chagas' disease, must invade and multiply within mammalian cells. Cytokeratin 18 (CK18) is among the host molecules that have been suggested as a mediator of important events during T. cruzi-host cell interaction. Based on that possibility, we addressed whether RNA interference (RNAi)-mediated down regulation of the CK18 gene could interfere with the parasite life cycle in vitro. HeLa cells transiently transfected with CK18-RNAi had negligible levels of CK18 transcripts, and significantly reduced levels of CK18 protein expression as determined by immunoblotting or immunofluorescence. Results CK18 negative or positive HeLa cells were invaded equally as well by trypomastigotes of different T. cruzi strains. Also, in CK18 negative or positive cells, parasites recruited host cells lysosomes and escaped from the parasitophorous vacuole equally as well. After that, the growth of amastigotes of the Y or CL-Brener strains, was drastically arrested in CK18 RNAi-treated cells. After 48 hours, the number of amastigotes was several times lower in CK18 RNAi-treated cells when compared to control cells. Simultaneous staining of parasites and CK18 showed that in HeLa cells infected with the Y strain both co-localize. Although the amastigote surface protein-2 contains the domain VTVXNVFLYNR previously described to bind to CK18, in several attempts, we failed to detect binding of a recombinant protein to CK-18. Conclusion The study demonstrates that silencing CK18 by transient RNAi, inhibits intracellular multiplication of the Y and CL strain of T. cruzi in HeLa cells, but not trypanosome binding and invasion. PMID:19087356

Complex of simian virus 40 large-T antigen and host 53,000-molecular-weight protein in monkey cells.

PubMed Central

Harlow, E; Pim, D C; Crawford, L V

1981-01-01

Mouse cells transformed by simian virus 40 (SV40) have been shown to contain a complex of the virus-coded large-T antigen with a host 53,000-molecular-weight (53K) protein. Initial attempts to detect a similar complex in lytically infected cells were unsuccessful, and it therefore seemed that the complex might be peculiar to transformed or abortively transformed nonpermissive cells. Immunoprecipitation of [32P]phosphate-labeled extracts of SV40-infected CV-1 African green monkey kidney cells with antibodies specific for large-T or the 53K protein revealed that the large-T-53K protein complex was formed during lytic infections. Only a minor fraction of the large-T present was associated with 53K protein, and large-T and the 53K host protein cosedimented during centrifugation through sucrose gradients. We used monospecific sera and monoclonal antibodies to study the rate of synthesis and phosphorylation of the 53K protein during lytic infections. Infection of CV-1 cells with SV40 increased the rate of synthesis of the 53K protein fivefold over that in mock-infected cells. At the same time, the rate of phosphorylation of the 53K protein increased more than 30-fold compared with control cultures. Monkey cells transformed by UV-irradiated SV40 (Gluzman et al., J. Virol. 22:256-266, 1977) also contained the large-T-53K protein complex. The formation of the complex is therefore not a peculiarity of SV40-transformed rodent cells but is a common feature of SV40 infections. Images PMID:6163871

Plasmodesmal regulation during plant-pathogen interactions.

PubMed

Cheval, Cecilia; Faulkner, Christine

2018-01-01

Contents Summary 62 I. Introduction 62 II. Plasmodesmal regulation is an innate defence response 63 III. Reactive oxygen species regulate plasmodesmal function 63 IV. Plasmodesmal regulation by and of defence-associated small molecules 64 V. Plasmodesmata facilitate systemic defence signalling 64 VI. Virulent pathogens exploit plasmodesmata 66 VII. Outlook 66 Acknowledgements 66 References 66 SUMMARY: Plasmodesmata (PD) are plasma membrane-lined pores that connect neighbouring plant cells, bridging the cell wall and establishing cytoplasmic and membrane continuity between cells. PD are dynamic structures regulated by callose deposition in a variety of stress and developmental contexts. This process crudely controls the aperture of the pore and thus the flux of molecules between cells. During pathogen infection, plant cells initiate a range of immune responses and it was recently identified that, following perception of fungal and bacterial pathogens, plant cells initially close their PD. Systemic defence responses depend on the spread of signals between cells, raising questions about whether PD are in different functional states during different immune responses. It is well established that viral pathogens exploit PD to spread between cells, but it has more recently been identified that protein effectors secreted by fungal pathogens can spread between host cells via PD. It is possible that many classes of pathogens specifically target PD to aid infection, which would infer antagonistic regulation of PD by host and pathogen. How PD regulation benefits both host immune responses and pathogen infection is an important question and demands that we examine the multicellular nature of plant-pathogen interactions. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

Cellular Aspects of Shigella Pathogenesis: Focus on the Manipulation of Host Cell Processes

PubMed Central

Killackey, Samuel A.; Sorbara, Matthew T.; Girardin, Stephen E.

2016-01-01

Shigella is a Gram-negative bacterium that is responsible for shigellosis. Over the years, the study of Shigella has provided a greater understanding of how the host responds to bacterial infection, and how bacteria have evolved to effectively counter the host defenses. In this review, we provide an update on some of the most recent advances in our understanding of pivotal processes associated with Shigella infection, including the invasion into host cells, the metabolic changes that occur within the bacterium and the infected cell, cell-to-cell spread mechanisms, autophagy and membrane trafficking, inflammatory signaling and cell death. This recent progress sheds a new light into the mechanisms underlying Shigella pathogenesis, and also more generally provides deeper understanding of the complex interplay between host cells and bacterial pathogens in general. PMID:27066460

Role of Granulocyte-Macrophage Colony-Stimulating Factor Production by T Cells during Mycobacterium tuberculosis Infection.

PubMed

Rothchild, Alissa C; Stowell, Britni; Goyal, Girija; Nunes-Alves, Cláudio; Yang, Qianting; Papavinasasundaram, Kadamba; Sassetti, Christopher M; Dranoff, Glenn; Chen, Xinchun; Lee, Jinhee; Behar, Samuel M

2017-10-24

Mice deficient for granulocyte-macrophage colony-stimulating factor (GM-CSF -/- ) are highly susceptible to infection with Mycobacterium tuberculosis , and clinical data have shown that anti-GM-CSF neutralizing antibodies can lead to increased susceptibility to tuberculosis in otherwise healthy people. GM-CSF activates human and murine macrophages to inhibit intracellular M. tuberculosis growth. We have previously shown that GM-CSF produced by iNKT cells inhibits growth of M. tuberculosis However, the more general role of T cell-derived GM-CSF during infection has not been defined and how GM-CSF activates macrophages to inhibit bacterial growth is unknown. Here we demonstrate that, in addition to nonconventional T cells, conventional T cells also produce GM-CSF during M. tuberculosis infection. Early during infection, nonconventional iNKT cells and γδ T cells are the main source of GM-CSF, a role subsequently assumed by conventional CD4 + T cells as the infection progresses. M. tuberculosis -specific T cells producing GM-CSF are also detected in the peripheral blood of infected people. Under conditions where nonhematopoietic production of GM-CSF is deficient, T cell production of GM-CSF is protective and required for control of M. tuberculosis infection. However, GM-CSF is not required for T cell-mediated protection in settings where GM-CSF is produced by other cell types. Finally, using an in vitro macrophage infection model, we demonstrate that GM-CSF inhibition of M. tuberculosis growth requires the expression of peroxisome proliferator-activated receptor gamma (PPARγ). Thus, we identified GM-CSF production as a novel T cell effector function. These findings suggest that a strategy augmenting T cell production of GM-CSF could enhance host resistance against M. tuberculosis IMPORTANCE Mycobacterium tuberculosis is the bacterium that causes tuberculosis, the leading cause of death by any infection worldwide. T cells are critical components of the immune response to Mycobacterium tuberculosis While gamma interferon (IFN-γ) is a key effector function of T cells during infection, a failed phase IIb clinical trial and other studies have revealed that IFN-γ production alone is not sufficient to control M. tuberculosis In this study, we demonstrate that CD4 + , CD8 + , and nonconventional T cells produce GM-CSF during Mycobacterium tuberculosis infection in mice and in the peripheral blood of infected humans. Under conditions where other sources of GM-CSF are absent, T cell production of GM-CSF is protective and is required for control of infection. GM-CSF activation of macrophages to limit bacterial growth requires host expression of the transcription factor PPARγ. The identification of GM-CSF production as a T cell effector function may inform future host-directed therapy or vaccine designs. Copyright © 2017 Rothchild et al.

Modulation of Memory T Cells to Control Acquired Bone Marrow Failure

DTIC Science & Technology

2016-01-01

Representative images show the tissues from one of 6 recipients in each group at day 7 after transplantation. Images were obtained with an OlympusBX41...alloreactive effector T cells capable of mediating host tissue injury and could be beneficial targets for improving the efficacy of allogeneic HSCT...leukemia (GVL) effect, but showed impaired expansion in local tissues .69-72 This nTEM pool might have less diverse T cell receptor (TCR) repertoire

Resetting the T Cell Repertoire in Prostate Cancer Bearing Host

DTIC Science & Technology

2008-03-04

the last treatment the mice were sacrificed and the total thymocytes and splenocytes were harvested and stained with fluorochrome conjugated...were injected intravenously into recipients and spleen cells were harvested 20 h later and analyzed by flow cytome~ for the relative abundance of...either anti B7 1/B7 2 mAbs or control IgG five times every other day. Thymi and spleens were harvested S days after the last injection. Cells were

Detection of chromosomal abnormalities by fluorescent in-situ hybridization in immotile viable spermatozoa determined by hypo-osmotic sperm swelling test.

PubMed

Zeyneloglu, H B; Baltaci, V; Ege, S; Haberal, A; Batioglu, S

2000-04-01

If randomly selected immotile spermatozoa are used for intracytoplasmic sperm injection (ICSI), pregnancy rates are significantly decreased. The hypo-osmotic swelling test (HOST) is the only method available to detect the viable, but immotile spermatozoa for ICSI. However, evidence is still lacking for the chromosomal abnormalities for the normal-looking, but immotile spermatozoa positive for HOST. Sperm samples from 20 infertile men with normal chromosomal constitution were obtained. After Percoll separation, morphologically normal but immotile spermatozoa were transported individually into HOST solution for 1 min using micropipettes. Cells that showed tail curling with swelling in HOST were then transferred back into human tubal fluid solution to allow reversal of swelling. These sperm cells were fixed and processed for the multi-colour fluorescence in-situ hybridization (FISH) for chromosomes X, Y and 18. The same FISH procedure was applied for the motile spermatozoa from the same cohort, which formed the control group. The average aneuploidy rates were 1.70 and 1.54% in 1000 HOST positive immotile and motile spermatozoa respectively detected by FISH for each patient. Our results indicate that morphologically normal, immotile but viable spermatozoa have an aneuploidy rate similar to that of normal motile spermatozoa.

The Endoplasmic Reticulum-Mitochondrion Tether ERMES Orchestrates Fungal Immune Evasion, Illuminating Inflammasome Responses to Hyphal Signals

PubMed Central

Tucey, Timothy M.; Verma-Gaur, Jiyoti; Nguyen, Julie; Hewitt, Victoria L.; Lo, Tricia L.; Shingu-Vazquez, Miguel; Robertson, Avril A. B.; Hill, James R.; Pettolino, Filomena A.; Beddoe, Travis; Cooper, Matthew A.; Naderer, Thomas

2016-01-01

ABSTRACT The pathogenic yeast Candida albicans escapes macrophages by triggering NLRP3 inflammasome-dependent host cell death (pyroptosis). Pyroptosis is inflammatory and must be tightly regulated by host and microbe, but the mechanism is incompletely defined. We characterized the C. albicans endoplasmic reticulum (ER)-mitochondrion tether ERMES and show that the ERMES mmm1 mutant is severely crippled in killing macrophages despite hyphal formation and normal phagocytosis and survival. To understand dynamic inflammasome responses to Candida with high spatiotemporal resolution, we established live-cell imaging for parallel detection of inflammasome activation and pyroptosis at the single-cell level. This showed that the inflammasome response to mmm1 mutant hyphae is delayed by 10 h, after which an exacerbated activation occurs. The NLRP3 inhibitor MCC950 inhibited inflammasome activation and pyroptosis by C. albicans, including exacerbated inflammasome activation by the mmm1 mutant. At the cell biology level, inactivation of ERMES led to a rapid collapse of mitochondrial tubular morphology, slow growth and hyphal elongation at host temperature, and reduced exposed 1,3-β-glucan in hyphal populations. Our data suggest that inflammasome activation by C. albicans requires a signal threshold dependent on hyphal elongation and cell wall remodeling, which could fine-tune the response relative to the level of danger posed by C. albicans. The phenotypes of the ERMES mutant and the lack of conservation in animals suggest that ERMES is a promising antifungal drug target. Our data further indicate that NLRP3 inhibition by MCC950 could modulate C. albicans-induced inflammation. IMPORTANCE The yeast Candida albicans causes human infections that have mortality rates approaching 50%. The key to developing improved therapeutics is to understand the host-pathogen interface. A critical interaction is that with macrophages: intracellular Candida triggers the NLRP3/caspase-1 inflammasome for escape through lytic host cell death, but this also activates antifungal responses. To better understand how the inflammasome response to Candida is fine-tuned, we established live-cell imaging of inflammasome activation at single-cell resolution, coupled with analysis of the fungal ERMES complex, a mitochondrial regulator that lacks human homologs. We show that ERMES mediates Candida escape via inflammasome-dependent processes, and our data suggest that inflammasome activation is controlled by the level of hyphal growth and exposure of cell wall components as a proxy for severity of danger. Our study provides the most detailed dynamic analysis of inflammasome responses to a fungal pathogen so far and establishes promising pathogen- and host-derived therapeutic strategies. PMID:27303738

The Endoplasmic Reticulum-Mitochondrion Tether ERMES Orchestrates Fungal Immune Evasion, Illuminating Inflammasome Responses to Hyphal Signals.

PubMed

Tucey, Timothy M; Verma-Gaur, Jiyoti; Nguyen, Julie; Hewitt, Victoria L; Lo, Tricia L; Shingu-Vazquez, Miguel; Robertson, Avril A B; Hill, James R; Pettolino, Filomena A; Beddoe, Travis; Cooper, Matthew A; Naderer, Thomas; Traven, Ana

2016-01-01

The pathogenic yeast Candida albicans escapes macrophages by triggering NLRP3 inflammasome-dependent host cell death (pyroptosis). Pyroptosis is inflammatory and must be tightly regulated by host and microbe, but the mechanism is incompletely defined. We characterized the C. albicans endoplasmic reticulum (ER)-mitochondrion tether ERMES and show that the ERMES mmm1 mutant is severely crippled in killing macrophages despite hyphal formation and normal phagocytosis and survival. To understand dynamic inflammasome responses to Candida with high spatiotemporal resolution, we established live-cell imaging for parallel detection of inflammasome activation and pyroptosis at the single-cell level. This showed that the inflammasome response to mmm1 mutant hyphae is delayed by 10 h, after which an exacerbated activation occurs. The NLRP3 inhibitor MCC950 inhibited inflammasome activation and pyroptosis by C. albicans, including exacerbated inflammasome activation by the mmm1 mutant. At the cell biology level, inactivation of ERMES led to a rapid collapse of mitochondrial tubular morphology, slow growth and hyphal elongation at host temperature, and reduced exposed 1,3-β-glucan in hyphal populations. Our data suggest that inflammasome activation by C. albicans requires a signal threshold dependent on hyphal elongation and cell wall remodeling, which could fine-tune the response relative to the level of danger posed by C. albicans. The phenotypes of the ERMES mutant and the lack of conservation in animals suggest that ERMES is a promising antifungal drug target. Our data further indicate that NLRP3 inhibition by MCC950 could modulate C. albicans-induced inflammation. IMPORTANCE The yeast Candida albicans causes human infections that have mortality rates approaching 50%. The key to developing improved therapeutics is to understand the host-pathogen interface. A critical interaction is that with macrophages: intracellular Candida triggers the NLRP3/caspase-1 inflammasome for escape through lytic host cell death, but this also activates antifungal responses. To better understand how the inflammasome response to Candida is fine-tuned, we established live-cell imaging of inflammasome activation at single-cell resolution, coupled with analysis of the fungal ERMES complex, a mitochondrial regulator that lacks human homologs. We show that ERMES mediates Candida escape via inflammasome-dependent processes, and our data suggest that inflammasome activation is controlled by the level of hyphal growth and exposure of cell wall components as a proxy for severity of danger. Our study provides the most detailed dynamic analysis of inflammasome responses to a fungal pathogen so far and establishes promising pathogen- and host-derived therapeutic strategies.

DDX41 Recognizes RNA/DNA Retroviral Reverse Transcripts and Is Critical for In Vivo Control of Murine Leukemia Virus Infection.

PubMed

Stavrou, Spyridon; Aguilera, Alexya N; Blouch, Kristin; Ross, Susan R

2018-06-05

Host recognition of viral nucleic acids generated during infection leads to the activation of innate immune responses essential for early control of virus. Retrovirus reverse transcription creates numerous potential ligands for cytosolic host sensors that recognize foreign nucleic acids, including single-stranded RNA (ssRNA), RNA/DNA hybrids, and double-stranded DNA (dsDNA). We and others recently showed that the sensors cyclic GMP-AMP synthase (cGAS), DEAD-box helicase 41 (DDX41), and members of the Aim2-like receptor (ALR) family participate in the recognition of retroviral reverse transcripts. However, why multiple sensors might be required and their relative importance in in vivo control of retroviral infection are not known. Here, we show that DDX41 primarily senses the DNA/RNA hybrid generated at the first step of reverse transcription, while cGAS recognizes dsDNA generated at the next step. We also show that both DDX41 and cGAS are needed for the antiretroviral innate immune response to murine leukemia virus (MLV) and HIV in primary mouse macrophages and dendritic cells (DCs). Using mice with cell type-specific knockout of the Ddx41 gene, we show that DDX41 sensing in DCs but not macrophages was critical for controlling in vivo MLV infection. This suggests that DCs are essential in vivo targets for infection, as well as for initiating the antiviral response. Our work demonstrates that the innate immune response to retrovirus infection depends on multiple host nucleic acid sensors that recognize different reverse transcription intermediates. IMPORTANCE Viruses are detected by many different host sensors of nucleic acid, which in turn trigger innate immune responses, such as type I interferon (IFN) production, required to control infection. We show here that at least two sensors are needed to initiate a highly effective innate immune response to retroviruses-DDX41, which preferentially senses the RNA/DNA hybrid generated at the first step of retrovirus replication, and cGAS, which recognizes double-stranded DNA generated at the second step. Importantly, we demonstrate using mice lacking DDX41 or cGAS that both sensors are needed for the full antiviral response needed to control in vivo MLV infection. These findings underscore the need for multiple host factors to counteract retroviral infection. Copyright © 2018 Stavrou et al.

Apicomplexans pulling the strings: manipulation of the host cell cytoskeleton dynamics.

PubMed

Cardoso, Rita; Soares, Helena; Hemphill, Andrew; Leitão, Alexandre

2016-07-01

Invasive stages of apicomplexan parasites require a host cell to survive, proliferate and advance to the next life cycle stage. Once invasion is achieved, apicomplexans interact closely with the host cell cytoskeleton, but in many cases the different species have evolved distinct mechanisms and pathways to modulate the structural organization of cytoskeletal filaments. The host cell cytoskeleton is a complex network, largely, but not exclusively, composed of microtubules, actin microfilaments and intermediate filaments, all of which are modulated by associated proteins, and it is involved in diverse functions including maintenance of cell morphology and mechanical support, migration, signal transduction, nutrient uptake, membrane and organelle trafficking and cell division. The ability of apicomplexans to modulate the cytoskeleton to their own advantage is clearly beneficial. We here review different aspects of the interactions of apicomplexans with the three main cytoskeletal filament types, provide information on the currently known parasite effector proteins and respective host cell targets involved, and how these interactions modulate the host cell physiology. Some of these findings could provide novel targets that could be exploited for the development of preventive and/or therapeutic strategies.

Effector T cells require fatty acid metabolism during murine graft-versus-host disease

PubMed Central

Byersdorfer, Craig A.; Tkachev, Victor; Opipari, Anthony W.; Goodell, Stefanie; Swanson, Jacob; Sandquist, Stacy; Glick, Gary D.; Ferrara, James L. M.

2013-01-01

Activated T cells require increased energy to proliferate and mediate effector functions, but the metabolic changes that occur in T cells following stimulation in vivo are poorly understood, particularly in the context of inflammation. We have previously shown that T cells activated during graft-versus-host disease (GVHD) primarily rely on oxidative phosphorylation to synthesize adenosine 5′-triphosphate. Here, we demonstrate that alloreactive effector T cells (Teff) use fatty acids (FAs) as a fuel source to support their in vivo activation. Alloreactive T cells increased FA transport, elevated levels of FA oxidation enzymes, up-regulated transcriptional coactivators to drive oxidative metabolism, and increased their rates of FA oxidation. Importantly, increases in FA transport and up-regulation of FA oxidation machinery occurred specifically in T cells during GVHD and were not seen in Teff following acute activation. Pharmacological blockade of FA oxidation decreased the survival of alloreactive T cells but did not influence the survival of T cells during normal immune reconstitution. These studies suggest that pathways controlling FA metabolism might serve as therapeutic targets to treat GVHD and other T-cell–mediated immune diseases. PMID:24046012

Innate myeloid cell TNFR1 mediates first line defence against primary Mycobacterium tuberculosis infection.

PubMed Central

Segueni, Noria; Benmerzoug, Sulayman; Rose, Stéphanie; Gauthier, Amandine; Bourigault, Marie-Laure; Reverchon, Flora; Philippeau, Amandine; Erard, François; Le Bert, Marc; Bouscayrol, Hélène; Wachter, Thierry; Garcia, Irène; Kollias, George; Jacobs, Muazzam; Ryffel, Bernhard; Quesniaux, Valerie F.J.

2016-01-01

TNF is crucial for controlling Mycobacterium tuberculosis infection and understanding how will help immunomodulating the host response. Here we assessed the contribution of TNFR1 pathway from innate myeloid versus T cells. We first established the prominent role of TNFR1 in haematopoietic cells for controlling M. tuberculosis in TNFR1 KO chimera mice. Further, absence of TNFR1 specifically on myeloid cells (M-TNFR1 KO) recapitulated the uncontrolled M. tuberculosis infection seen in fully TNFR1 deficient mice, with increased bacterial burden, exacerbated lung inflammation, and rapid death. Pulmonary IL-12p40 over-expression was attributed to a prominent CD11b+ Gr1high cell population in infected M-TNFR1 KO mice. By contrast, absence of TNFR1 on T-cells did not compromise the control of M. tuberculosis infection over 6-months. Thus, the protective TNF/TNFR1 pathway essential for controlling primary M. tuberculosis infection depends on innate macrophage and neutrophil myeloid cells, while TNFR1 pathway in T cells is dispensable. PMID:26931771

Fungal-Induced Cell Cycle Impairment, Chromosome Instability and Apoptosis via Differential Activation of NF-κB

PubMed Central

Ben-Abdallah, Mariem; Sturny-Leclère, Aude; Avé, Patrick; Louise, Anne; Moyrand, Frédérique; Weih, Falk; Janbon, Guilhem; Mémet, Sylvie

2012-01-01

Microbial pathogens have developed efficient strategies to compromise host immune responses. Cryptococcus neoformans is a facultative intracellular pathogen, recognised as the most common cause of systemic fungal infections leading to severe meningoencephalitis, mainly in immunocompromised patients. This yeast is characterized by a polysaccharide capsule, which inhibits its phagocytosis. Whereas phagocytosis escape and macrophage intracellular survival have been intensively studied, extracellular survival of this yeast and restraint of host innate immune response are still poorly understood. In this study, we have investigated whether C. neoformans affected macrophage cell viability and whether NF-κB (nuclear factor-κB), a key regulator of cell growth, apoptosis and inflammation, was involved. Using wild-type (WT) as well as mutant strains of C. neoformans for the pathogen side, and WT and mutant cell lines with altered NF-κB activity or signalling as well as primary macrophages for the host side, we show that C. neoformans manipulated NF-κB-mediated signalling in a unique way to regulate macrophage cell fate and viability. On the one hand, serotype A strains reduced macrophage proliferation in a capsule-independent fashion. This growth decrease, which required a critical dosage of NF-κB activity, was caused by cell cycle disruption and aneuploidy, relying on fungal-induced modification of expression of several cell cycle checkpoint regulators in S and G2/M phases. On the other hand, C. neoformans infection induced macrophage apoptosis in a capsule-dependent manner with a differential requirement of the classical and alternative NF-κB signalling pathways, the latter one being essential. Together, these findings shed new light on fungal strategies to subvert host response through uncoupling of NF-κB activity in pathogen-controlled apoptosis and impairment of cell cycle progression. They also provide the first demonstration of induction of aneuploidy by a fungal pathogen, which may have wider implications for human health as aneuploidy is proposed to promote tumourigenesis. PMID:22396644

Fungal-induced cell cycle impairment, chromosome instability and apoptosis via differential activation of NF-κB.

PubMed

Ben-Abdallah, Mariem; Sturny-Leclère, Aude; Avé, Patrick; Louise, Anne; Moyrand, Frédérique; Weih, Falk; Janbon, Guilhem; Mémet, Sylvie

2012-01-01

Microbial pathogens have developed efficient strategies to compromise host immune responses. Cryptococcus neoformans is a facultative intracellular pathogen, recognised as the most common cause of systemic fungal infections leading to severe meningoencephalitis, mainly in immunocompromised patients. This yeast is characterized by a polysaccharide capsule, which inhibits its phagocytosis. Whereas phagocytosis escape and macrophage intracellular survival have been intensively studied, extracellular survival of this yeast and restraint of host innate immune response are still poorly understood. In this study, we have investigated whether C. neoformans affected macrophage cell viability and whether NF-κB (nuclear factor-κB), a key regulator of cell growth, apoptosis and inflammation, was involved. Using wild-type (WT) as well as mutant strains of C. neoformans for the pathogen side, and WT and mutant cell lines with altered NF-κB activity or signalling as well as primary macrophages for the host side, we show that C. neoformans manipulated NF-κB-mediated signalling in a unique way to regulate macrophage cell fate and viability. On the one hand, serotype A strains reduced macrophage proliferation in a capsule-independent fashion. This growth decrease, which required a critical dosage of NF-κB activity, was caused by cell cycle disruption and aneuploidy, relying on fungal-induced modification of expression of several cell cycle checkpoint regulators in S and G2/M phases. On the other hand, C. neoformans infection induced macrophage apoptosis in a capsule-dependent manner with a differential requirement of the classical and alternative NF-κB signalling pathways, the latter one being essential. Together, these findings shed new light on fungal strategies to subvert host response through uncoupling of NF-κB activity in pathogen-controlled apoptosis and impairment of cell cycle progression. They also provide the first demonstration of induction of aneuploidy by a fungal pathogen, which may have wider implications for human health as aneuploidy is proposed to promote tumourigenesis.

At the Frontier; RXLR Effectors Crossing the Phytophthora-Host Interface.

PubMed

Bouwmeester, Klaas; Meijer, Harold J G; Govers, Francine

2011-01-01

Plants are constantly beset by pathogenic organisms. To successfully infect their hosts, plant pathogens secrete effector proteins, many of which are translocated to the inside of the host cell where they manipulate normal physiological processes and undermine host defense. The way by which effectors cross the frontier to reach the inside of the host cell varies among different classes of pathogens. For oomycete plant pathogens - like the potato late blight pathogen Phytophthora infestans - it has been shown that effector translocation to the host cell cytoplasm is dependent on conserved amino acid motifs that are present in the N-terminal part of effector proteins. One of these motifs, known as the RXLR motif, has a strong resemblance with a host translocation motif found in effectors secreted by Plasmodium species. These malaria parasites, that reside inside specialized vacuoles in red blood cells, make use of a specific protein translocation complex to export effectors from the vacuole into the red blood cell. Whether or not also oomycete RXLR effectors require a translocation complex to cross the frontier is still under investigation. For one P. infestans RXLR effector named IPI-O we have found a potential host target that could play a role in establishing the first contact between this effector and the host cell. This membrane spanning lectin receptor kinase, LecRK-I.9, interacts with IPI-O via the tripeptide RGD that overlaps with the RXLR motif. In animals, RGD is a well-known cell adhesion motif; it binds to integrins, which are membrane receptors that regulate many cellular processes and which can be hijacked by pathogens for either effector translocation or pathogen entry into host cells.

Effects of host cell sterol composition upon internalization of Yersinia pseudotuberculosis and clustered β1 integrin.

PubMed

Kim, JiHyun; Fukuto, Hana S; Brown, Deborah A; Bliska, James B; London, Erwin

2018-01-26

Yersinia pseudotuberculosis is a foodborne pathogenic bacterium that causes acute gastrointestinal illness, but its mechanisms of infection are incompletely described. We examined how host cell sterol composition affected Y. pseudotuberculosis uptake. To do this, we depleted or substituted cholesterol in human MDA-MB-231 epithelial cells with various alternative sterols. Decreasing host cell cholesterol significantly reduced pathogen internalization. When host cell cholesterol was substituted with various sterols, only desmosterol and 7-dehydrocholesterol supported internalization. This specificity was not due to sterol dependence of bacterial attachment to host cells, which was similar with all sterols studied. Because a key step in Y. pseudotuberculosis internalization is interaction of the bacterial adhesins invasin and YadA with host cell β1 integrin, we compared the sterol dependence of wildtype Y. pseudotuberculosis internalization with that of Δ inv , Δ yadA , and Δ inv Δ yadA mutant strains. YadA deletion decreased bacterial adherence to host cells, whereas invasin deletion had no effect. Nevertheless, host cell sterol substitution had a similar effect on internalization of these bacterial deletion strains as on the wildtype bacteria. The Δ inv Δ yadA double mutant adhered least to cells and so was not significantly internalized. The sterol structure dependence of Y. pseudotuberculosis internalization differed from that of endocytosis, as monitored using antibody-clustered β1 integrin and previous studies on other proteins, which had a more permissive sterol dependence. This study suggests that agents could be designed to interfere with internalization of Yersinia without disturbing endocytosis. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

IFNAR1-Signalling Obstructs ICOS-mediated Humoral Immunity during Non-lethal Blood-Stage Plasmodium Infection

PubMed Central

Sebina, Ismail; James, Kylie R.; Soon, Megan S. F.; Best, Shannon E.; Montes de Oca, Marcela; Amante, Fiona H.; Thomas, Bryce S.; Beattie, Lynette; Souza-Fonseca-Guimaraes, Fernando; Smyth, Mark J.; Hertzog, Paul J.; Hill, Geoffrey R.; Engwerda, Christian R.

2016-01-01

Parasite-specific antibodies protect against blood-stage Plasmodium infection. However, in malaria-endemic regions, it takes many months for naturally-exposed individuals to develop robust humoral immunity. Explanations for this have focused on antigenic variation by Plasmodium, but have considered less whether host production of parasite-specific antibody is sub-optimal. In particular, it is unclear whether host immune factors might limit antibody responses. Here, we explored the effect of Type I Interferon signalling via IFNAR1 on CD4+ T-cell and B-cell responses in two non-lethal murine models of malaria, P. chabaudi chabaudi AS (PcAS) and P. yoelii 17XNL (Py17XNL) infection. Firstly, we demonstrated that CD4+ T-cells and ICOS-signalling were crucial for generating germinal centre (GC) B-cells, plasmablasts and parasite-specific antibodies, and likewise that T follicular helper (Tfh) cell responses relied on B cells. Next, we found that IFNAR1-signalling impeded the resolution of non-lethal blood-stage infection, which was associated with impaired production of parasite-specific IgM and several IgG sub-classes. Consistent with this, GC B-cell formation, Ig-class switching, plasmablast and Tfh differentiation were all impaired by IFNAR1-signalling. IFNAR1-signalling proceeded via conventional dendritic cells, and acted early by limiting activation, proliferation and ICOS expression by CD4+ T-cells, by restricting the localization of activated CD4+ T-cells adjacent to and within B-cell areas of the spleen, and by simultaneously suppressing Th1 and Tfh responses. Finally, IFNAR1-deficiency accelerated humoral immune responses and parasite control by boosting ICOS-signalling. Thus, we provide evidence of a host innate cytokine response that impedes the onset of humoral immunity during experimental malaria. PMID:27812214

Chronic Lymphocytic Leukemia-Derived IL-10 Suppresses Antitumor Immunity.

PubMed

Alhakeem, Sara S; McKenna, Mary K; Oben, Karine Z; Noothi, Sunil K; Rivas, Jacqueline R; Hildebrandt, Gerhard C; Fleischman, Roger A; Rangnekar, Vivek M; Muthusamy, Natarajan; Bondada, Subbarao

2018-04-30

Chronic lymphocytic leukemia (CLL) patients progressively develop an immunosuppressive state. CLL patients have more plasma IL-10, an anti-inflammatory cytokine, than healthy controls. In vitro human CLL cells produce IL-10 in response to BCR cross-linking. We used the transgenic Eμ-T cell leukemia oncogene-1 ( TCL1 ) mouse CLL model to study the role of IL-10 in CLL associated immunosuppression. Eμ-TCL mice spontaneously develop CLL because of a B cell-specific expression of the oncogene, TCL1. Eμ- TCL1 mouse CLL cells constitutively produce IL-10, which is further enhanced by BCR cross-linking, CLL-derived IL-10 did not directly affect survival of murine or human CLL cells in vitro. We tested the hypothesis that the CLL-derived IL-10 has a critical role in CLL disease in part by suppressing the host immune response to the CLL cells. In IL-10R -/- mice, wherein the host immune cells are unresponsive to IL-10-mediated suppressive effects, there was a significant reduction in CLL cell growth compared with wild type mice. IL-10 reduced the generation of effector CD4 and CD8 T cells. We also found that activation of BCR signaling regulated the production of IL-10 by both murine and human CLL cells. We identified the transcription factor, Sp1, as a novel regulator of IL-10 production by CLL cells and that it is regulated by BCR signaling via the Syk/MAPK pathway. Our results suggest that incorporation of IL-10 blocking agents may enhance current therapeutic regimens for CLL by potentiating host antitumor immune response. Copyright © 2018 by The American Association of Immunologists, Inc.

The effects of Candida albicans cell wall protein fraction on dendritic cell maturation.

PubMed

Roudbary, Maryam; Roudbar Mohammadi, Shahla; Bozorgmehr, Mahmood; Moazzeni, Seyed Mohammad

2009-06-01

Candida albicans is a member of the normal human microflora. C. albicans cell wall is composed of several protein and carbohydrate components which have been shown to play a crucial role in C. albicans interaction with the host immune system. Major components of C. albican cell wall are carbohydrates such as mannans, beta glucans and chitins, and proteins that partially modulate the host immune responses. Dendritic cells (DC), as the most important antigen-presenting cells of the immune system, play a critical role in inducing immune responses against different pathogens. We investigated the effect of the cell wall protein fraction (CPF) of C. albicans on DC maturation. The CPF of C. albicans cells was extracted by a lysis buffer containing sodium dodecyl sulphate, 2-mercaptoethanol and phosphate-buffered saline. The extract was dialyzed and its protein pattern was evaluated by electrophoresis. Dendritic cells were purified from Balb/c mice spleens through a three-step method including mononuclear cell separation, as well as 2-h and overnight cultures. The purified CPF was added at different concentrations to DC. The purity and maturation status of DC were determined by flow cytometry using monoclonal antibodies against CD11c, MHC-II, CD40 and CD86. Treatment of DC with 10 microg/ml of CPF increased the expression of maturation markers including MHC-II, CD86 and CD40 on DC compared to the control group. In this study we used C. albicans CPF with the molecular weight of 40-45 kDa for pulsing and maturation of dendritic cells. Since according to our results CPF significantly increased the expression of maturation markers on DC, we suggest that CPF may act as an efficient immunomodulator, or may be used as a potential adjuvant to boost the host immune system against infections.

Bat lung epithelial cells show greater host species-specific innate resistance than MDCK cells to human and avian influenza viruses.

PubMed

Slater, Tessa; Eckerle, Isabella; Chang, Kin-Chow

2018-04-10

With the recent discovery of novel H17N10 and H18N11 influenza viral RNA in bats and report on high frequency of avian H9 seroconversion in a species of free ranging bats, an important issue to address is the extent bats are susceptible to conventional avian and human influenza A viruses. To this end, three bat species (Eidolon helvum, Carollia perspicillata and Tadarida brasiliensis) of lung epithelial cells were separately infected with two avian and two human influenza viruses to determine their relative host innate immune resistance to infection. All three species of bat cells were more resistant than positive control Madin-Darby canine kidney (MDCK) cells to all four influenza viruses. TB1-Lu cells lacked sialic acid α2,6-Gal receptors and were most resistant among the three bat species. Interestingly, avian viruses were relatively more replication permissive in all three bat species of cells than with the use of human viruses which suggest that bats could potentially play a role in the ecology of avian influenza viruses. Chemical inhibition of the JAK-STAT pathway in bat cells had no effect on virus production suggesting that type I interferon signalling is not a major factor in resisting influenza virus infection. Although all three species of bat cells are relatively more resistant to influenza virus infection than control MDCK cells, they are more permissive to avian than human viruses which suggest that bats could have a contributory role in the ecology of avian influenza viruses.

Blood Vessels in Allotransplantation.

PubMed

Abrahimi, P; Liu, R; Pober, J S

2015-07-01

Human vascularized allografts are perfused through blood vessels composed of cells (endothelium, pericytes, and smooth muscle cells) that remain largely of graft origin and are thus subject to host alloimmune responses. Graft vessels must be healthy to maintain homeostatic functions including control of perfusion, maintenance of permselectivity, prevention of thrombosis, and participation in immune surveillance. Vascular cell injury can cause dysfunction that interferes with these processes. Graft vascular cells can be activated by mediators of innate and adaptive immunity to participate in graft inflammation contributing to both ischemia/reperfusion injury and allograft rejection. Different forms of rejection may affect graft vessels in different ways, ranging from thrombosis and neutrophilic inflammation in hyperacute rejection, to endothelialitis/intimal arteritis and fibrinoid necrosis in acute cell-mediated or antibody-mediated rejection, respectively, and to diffuse luminal stenosis in chronic rejection. While some current therapies targeting the host immune system do affect graft vascular cells, direct targeting of the graft vasculature may create new opportunities for preventing allograft injury and loss. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Donor and host photoreceptors engage in material transfer following transplantation of post-mitotic photoreceptor precursors

PubMed Central

Pearson, R. A.; Gonzalez-Cordero, A.; West, E. L.; Ribeiro, J. R.; Aghaizu, N.; Goh, D.; Sampson, R. D.; Georgiadis, A.; Waldron, P. V.; Duran, Y.; Naeem, A.; Kloc, M.; Cristante, E.; Kruczek, K.; Warre-Cornish, K.; Sowden, J. C.; Smith, A. J.; Ali, R. R.

2016-01-01

Photoreceptor replacement by transplantation is proposed as a treatment for blindness. Transplantation of healthy photoreceptor precursor cells into diseased murine eyes leads to the presence of functional photoreceptors within host retinae that express an array of donor-specific proteins. The resulting improvement in visual function was understood to be due to donor cells integrating within host retinae. Here, however, we show that while integration occurs the majority of donor-reporter-labelled cells in the host arises as a result of material transfer between donor and host photoreceptors. Material transfer does not involve permanent donor–host nuclear or cell–cell fusion, or the uptake of free protein or nucleic acid from the extracellular environment. Instead, RNA and/or protein are exchanged between donor and host cells in vivo. These data require a re-evaluation of the mechanisms underlying rescue by photoreceptor transplantation and raise the possibility of material transfer as a strategy for the treatment of retinal disorders. PMID:27701378

Accommodation of powdery mildew fungi in intact plant cells.

PubMed

Eichmann, Ruth; Hückelhoven, Ralph

2008-01-01

Parasitic powdery mildew fungi have to overcome basic resistance and manipulate host cells to establish a haustorium as a functional feeding organ in a host epidermal cell. Currently, it is of central interest how plant factors negatively regulate basal defense or whether they even support fungal development in compatible interactions. Additionally, creation of a metabolic sink in infected cells may involve host activity. Here, we review the current progress in understanding potential fungal targets for host reprogramming and nutrient acquisition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Los, Alrik Pieter; Sagt, Cornelis Maria Jacobus; Schooneveld-Bergmans, Margot Elisabeth Francoise

The invention relates to a host cell comprising at least four different heterologous polynucleotides chosen from the group of polynucleotides encoding cellulases, hemicellulases and pectinases, wherein the host cell is capable of producing the at least four different enzymes chosen from the group of cellulases, hemicellulases and pectinases, wherein the host cell is a filamentous fungus and is capable of secretion of the at least four different enzymes. This host cell can suitably be used for the production of an enzyme composition that can be used in a process for the saccharification of cellulosic material.

Interactome of E. piscicida and grouper liver proteins reveals strategies of bacterial infection and host immune response.

PubMed

Li, Hui; Zhu, Qing-Feng; Peng, Xuan-Xian; Peng, Bo

2017-01-03

The occurrence of infectious diseases is related to heterogeneous protein interactions between a host and a microbe. Therefore, elucidating the host-pathogen interplay is essential. We previously revealed the protein interactome between Edwardsiella piscicida and fish gill cells, and the present study identified the protein interactome between E. piscicida and E. drummondhayi liver cells. E. drummondhayi liver cells and bacterial pull-down approaches were used to identify E. piscicida outer membrane proteins that bind to liver cells and fish liver cell proteins that interact with bacterial cells, respectively. Eight bacterial proteins and 11 fish proteins were characterized. Heterogeneous protein-protein interactions between these bacterial cells and fish liver cells were investigated through far-Western blotting and co-immunoprecipitation. A network was constructed based on 42 heterogeneous protein-protein interactions between seven bacterial proteins and 10 fish proteins. A comparison of the new interactome with the previously reported interactome showed that four bacterial proteins overlapped, whereas all of the identified fish proteins were new, suggesting a difference between bacterial tricks for evading host immunity and the host strategy for combating bacterial infection. Furthermore, these bacterial proteins were found to regulate the expression of host innate immune-related proteins. These findings indicate that the interactome contributes to bacterial infection and host immunity.

Exosomes and other extracellular vesicles in host–pathogen interactions

PubMed Central

Schorey, Jeffrey S; Cheng, Yong; Singh, Prachi P; Smith, Victoria L

2015-01-01

An effective immune response requires the engagement of host receptors by pathogen-derived molecules and the stimulation of an appropriate cellular response. Therefore, a crucial factor in our ability to control an infection is the accessibility of our immune cells to the foreign material. Exosomes—which are extracellular vesicles that function in intercellular communication—may play a key role in the dissemination of pathogen- as well as host-derived molecules during infection. In this review, we highlight the composition and function of exosomes and other extracellular vesicles produced during viral, parasitic, fungal and bacterial infections and describe how these vesicles could function to either promote or inhibit host immunity. PMID:25488940

The Role of Intestinal Microbiota in Acute Graft-versus-Host Disease.

PubMed

Chen, Yuanyuan; Zhao, Ye; Cheng, Qiao; Wu, Depei; Liu, Haiyan

2015-01-01

The mammalian intestinal microbiota is a complex ecosystem that plays an important role in host immune responses. Recent studies have demonstrated that alterations in intestinal microbiota composition are linked to multiple inflammatory diseases in humans, including acute graft-versus-host disease (aGVHD). aGVHD is one of the major obstacles in allogeneic hematopoietic stem cell transplantation (allo-HSCT), characterized by tissue damage in the gastrointestinal (GI) tract, liver, lung, and skin. Here, we review the current understanding of the role of intestinal microbiota in the control of immune responses during aGVHD. Additionally, the possibility of using probiotic strains for potential treatment or prevention of aGVHD will be discussed.

The Role of Intestinal Microbiota in Acute Graft-versus-Host Disease

PubMed Central

Chen, Yuanyuan; Zhao, Ye; Cheng, Qiao; Wu, Depei; Liu, Haiyan

2015-01-01

The mammalian intestinal microbiota is a complex ecosystem that plays an important role in host immune responses. Recent studies have demonstrated that alterations in intestinal microbiota composition are linked to multiple inflammatory diseases in humans, including acute graft-versus-host disease (aGVHD). aGVHD is one of the major obstacles in allogeneic hematopoietic stem cell transplantation (allo-HSCT), characterized by tissue damage in the gastrointestinal (GI) tract, liver, lung, and skin. Here, we review the current understanding of the role of intestinal microbiota in the control of immune responses during aGVHD. Additionally, the possibility of using probiotic strains for potential treatment or prevention of aGVHD will be discussed. PMID:26090477

The Symbiosome: Legume and Rhizobia Co-evolution toward a Nitrogen-Fixing Organelle?

PubMed Central

Coba de la Peña, Teodoro; Fedorova, Elena; Pueyo, José J.; Lucas, M. Mercedes

2018-01-01

In legume nodules, symbiosomes containing endosymbiotic rhizobial bacteria act as temporary plant organelles that are responsible for nitrogen fixation, these bacteria develop mutual metabolic dependence with the host legume. In most legumes, the rhizobia infect post-mitotic cells that have lost their ability to divide, although in some nodules cells do maintain their mitotic capacity after infection. Here, we review what is currently known about legume symbiosomes from an evolutionary and developmental perspective, and in the context of the different interactions between diazotroph bacteria and eukaryotes. As a result, it can be concluded that the symbiosome possesses organelle-like characteristics due to its metabolic behavior, the composite origin and differentiation of its membrane, the retargeting of host cell proteins, the control of microsymbiont proliferation and differentiation by the host legume, and the cytoskeletal dynamics and symbiosome segregation during the division of rhizobia-infected cells. Different degrees of symbiosome evolution can be defined, specifically in relation to rhizobial infection and to the different types of nodule. Thus, our current understanding of the symbiosome suggests that it might be considered a nitrogen-fixing link in organelle evolution and that the distinct types of legume symbiosomes could represent different evolutionary stages toward the generation of a nitrogen-fixing organelle. PMID:29403508

Cytomegalovirus shapes long-term immune reconstitution after allogeneic stem cell transplantation

PubMed Central

Itzykson, Raphael; Robin, Marie; Moins-Teisserenc, Helene; Delord, Marc; Busson, Marc; Xhaard, Aliénor; de Fontebrune, Flore Sicre; de Latour, Régis Peffault; Toubert, Antoine; Socié, Gérard

2015-01-01

Immune reconstitution after allogeneic stem cell transplantation is a dynamic and complex process depending on the recipient and donor characteristics, on the modalities of transplantation, and on the occurrence of graft-versus-host disease. Multivariate methods widely used for gene expression profiling can simultaneously analyze the patterns of a great number of biological variables on a heterogeneous set of patients. Here we use these methods on flow cytometry assessment of up to 25 lymphocyte populations to analyze the global pattern of long-term immune reconstitution after transplantation. Immune patterns were most distinct from healthy controls at six months, and had not yet fully recovered as long as two years after transplant. The two principal determinants of variability were linked to the balance of B and CD8+ T cells and of natural killer and B cells, respectively. Recipient’s cytomegalovirus serostatus, cytomegalovirus replication, and chronic graft-versus-host disease were the main factors shaping the immune pattern one year after transplant. We identified a complex signature of under- and over-representation of immune populations dictated by recipient’s cytomegalovirus seropositivity. Finally, we identified dimensions of variance in immune patterns as significant predictors of long-term non-relapse mortality, independently of chronic graft-versus-host disease. PMID:25261095

A novel Meloidogyne enterolobii effector MeTCTP promotes parasitism by suppressing programmed cell death in host plants.

PubMed

Zhuo, Kan; Chen, Jiansong; Lin, Borong; Wang, Jing; Sun, Fengxia; Hu, Lili; Liao, Jinling

2017-01-01

Meloidogyne enterolobii is one of the most important plant-parasitic nematodes that can overcome the Mi-1 resistance gene and damage many economically important crops. Translationally controlled tumour protein (TCTP) is a multifunctional protein that exists in various eukaryotes and plays an important role in parasitism. In this study, a novel M. enterolobii TCTP effector, named MeTCTP, was identified and functionally characterized. MeTCTP was specifically expressed within the dorsal gland and was up-regulated during M. enterolobii parasitism. Transient expression of MeTCTP in protoplasts from tomato roots showed that MeTCTP was localized in the cytoplasm of the host cells. Transgenic Arabidopsis thaliana plants overexpressing MeTCTP were more susceptible to M. enterolobii infection than wild-type plants in a dose-dependent manner. By contrast, in planta RNA interference (RNAi) targeting MeTCTP suppressed the expression of MeTCTP in infecting nematodes and attenuated their parasitism. Furthermore, MeTCTP could suppress programmed cell death triggered by the pro-apoptotic protein BAX. These results demonstrate that MeTCTP is a novel plant-parasitic nematode effector that promotes parasitism, probably by suppressing programmed cell death in host plants. © 2016 BSPP and John Wiley & Sons Ltd.

Participation of necroptosis in the host response to acute bacterial pneumonia

PubMed Central

Ahn, Danielle; Prince, Alice

2017-01-01

Common pulmonary pathogens, such as Streptococcus pneumoniae and Staphylococcus aureus as well as the host-adapted pathogens responsible for health care associated pneumonias such as the carbapenem-resistant Klebsiella pneumoniae and Serratia marcesens are able to activate cell death through the RIPK1/RIPK3/MLKL cascade that causes necroptosis. Necroptosis can influence the pathogenesis of pneumonia through several mechanisms. Activation of this pathway can result in the loss of specific types of immune cells, especially macrophages and in doing so contribute to host pathology through loss of their critical immunoregulatory functions. However, in other settings of infection, necroptosis promotes pathogen removal and eradication of infected cells to control excessive proinflammatory signaling. Bacterial production of pore forming toxins provides a common mechanism to activate necroptosis by diverse bacterial species, with variable consequences depending upon the specific pathogen. Included in this brief review are data demonstrating the ability of the carbapenem-resistant ST258 K. pneumoniae to activate necroptosis in the setting of pneumonia, which is counterbalanced by their suppression of CYLD expression. Exactly how necroptosis and other mechanisms of cell death are co-regulated in the response to specific pulmonary pathogens remains a topic of active investigation and may provide potential therapeutic targets in the future. PMID:28125817

Participation of Necroptosis in the Host Response to Acute Bacterial Pneumonia.

PubMed

Ahn, Danielle; Prince, Alice

2017-01-01

Common pulmonary pathogens, such as Streptococcus pneumoniae and Staphylococcus aureus, as well as the host-adapted pathogens responsible for health care-associated pneumonias, such as the carbapenem-resistant Klebsiella pneumoniae and Serratia marcecsens, are able to activate cell death through the RIPK1/RIPK3/MLKL cascade that causes necroptosis. Necroptosis can influence the pathogenesis of pneumonia through several mechanisms. Activation of this pathway can result in the loss of specific types of immune cells, especially macrophages, and, in so doing, contribute to host pathology through the loss of their critical immunoregulatory functions. However, in other settings of infection, necroptosis promotes pathogen removal and the eradication of infected cells to control excessive proinflammatory signaling. Bacterial production of pore-forming toxins provides a common mechanism to activate necroptosis by diverse bacterial species, with variable consequences depending upon the specific pathogen. Included in this brief review are data demonstrating the ability of the carbapenem-resistant ST258 K. pneumoniae to activate necroptosis in the setting of pneumonia, which is counterbalanced by their suppression of CYLD expression. Exactly how necroptosis and other mechanisms of cell death are coregulated in the response to specific pulmonary pathogens remains a topic of active investigation, and it may provide potential therapeutic targets in the future. © 2017 S. Karger AG, Basel.

CD4+ T cells defined by their Vβ T cell receptor expression are associated with immunoregulatory profiles and lesion size in human leishmaniasis

PubMed Central

Keesen, T S L; Antonelli, L R V; Faria, D R; Guimarães, L H; Bacellar, O; Carvalho, E M; Dutra, W O; Gollob, K J

2011-01-01

Leishmaniasis is caused by infection with the protozoan parasite, Leishmania, that parasitizes human cells, and the cellular immune response is essential for controlling infection. In order to measure the host T cell response to Leishmania infection, we have measured the expansion, activation state and functional potential of specific T cells as identified by their T cell receptor Vβ region expression. In a group of cutaneous leishmaniasis (CL) patients, we evaluated these characteristics in nine different T cell subpopulations as identified by their Vβ region expression, before and after specific Leishmania antigen stimulation. Our results show: (1) an increase in CD4+ T cells expressing Vβ 5·2 and Vβ 24 in CL compared to controls; (2) a Leishmania antigen-induced increase in CD4+ T cells expressing Vβ 5·2, 11, 12 and 17; (3) a profile of previous activation of CD4+ Vβ 5·2-, 11- and 24-positive T cells, with higher expression of CD45RO, HLA-DR, interferon-γ, tumour necrosis factor-α and interleukin-10 compared to other Vβ-expressing subpopulations; (4) a positive correlation between higher frequencies of CD4+Vβ5·2+ T cells and larger lesions; and (5) biased homing of CD4+ T cells expressing Vβ 5·2 to the lesion site. Given that CL disease involves a level of pathology (ulcerated lesions) and is often followed by long-lived protection and cure, the identification of specific subpopulations active in this form of disease could allow for the discovery of immunodominant Leishmania antigens important for triggering efficient host responses against the parasite, or identify cell populations most involved in pathology. PMID:21726211

Impact of Active Metabolism on Chlamydia trachomatis Elementary Body Transcript Profile and Infectivity.

PubMed

Grieshaber, Scott; Grieshaber, Nicole; Yang, Hong; Baxter, Briana; Hackstadt, Ted; Omsland, Anders

2018-07-15

Bacteria of the genus Chlamydia include the significant human pathogens Chlamydia trachomatis and C. pneumoniae All chlamydiae are obligate intracellular parasites that depend on infection of a host cell and transition through a biphasic developmental cycle. Following host cell invasion by the infectious elementary body (EB), the pathogen transitions to the replicative but noninfectious reticulate body (RB). Differentiation of the RB back to the EB is essential to generate infectious progeny. While the EB form has historically been regarded as metabolically inert, maintenance of infectivity during incubation with specific nutrients has revealed active maintenance of the infectious phenotype. Using transcriptome sequencing, we show that the transcriptome of extracellular EBs incubated under metabolically stimulating conditions does not cluster with germinating EBs but rather with the transcriptome of EBs isolated directly from infected cells. In addition, the transcriptional profile of the extracellular metabolizing EBs more closely resembled that of EB production than germination. Maintenance of infectivity of extracellular EBs was achieved by metabolizing chemically diverse compounds, including glucose 6-phosphate, ATP, and amino acids, all of which can be found in extracellular environments, including mucosal secretions. We further show that the EB cell type actively maintains infectivity in the inclusion after terminal differentiation. Overall, these findings contribute to the emerging understanding that the EB cell form is actively maintained through metabolic processes after terminal differentiation to facilitate prolonged infectivity within the inclusion and under host cell free conditions, for example, following deposition at mucosal surfaces. IMPORTANCE Chlamydiae are obligate intracellular Gram-negative bacteria that are responsible for a wide range of diseases in both animal and human hosts. According to the Centers for Disease Control and Prevention, C. trachomatis is the most frequently reported sexually transmitted infection in the United States, costing the American health care system nearly $2.4 billion annually. Every year, there are over 4 million new cases of Chlamydia infections in the United States and an estimated 100 million cases worldwide. To cause disease, Chlamydia must successfully complete its complex biphasic developmental cycle, alternating between an infectious cell form (EB) specialized for initiating entry into target cells and a replicative form (RB) specialized for creating and maintaining the intracellular replication niche. The EB cell form has historically been considered metabolically quiescent, a passive entity simply waiting for contact with a host cell to initiate the next round of infection. Recent studies and data presented here demonstrate that the EB maintains its infectious phenotype by actively metabolizing a variety of nutrients. Therefore, the EB appears to have an active role in chlamydial biology, possibly within multiple environments, such as mucosal surfaces, fomites, and inside the host cell after formation. Copyright © 2018 American Society for Microbiology.

miRNA profiling of high, low and non-producing CHO cells during biphasic fed-batch cultivation reveals process relevant targets for host cell engineering.

PubMed

Stiefel, Fabian; Fischer, Simon; Sczyrba, Alexander; Otte, Kerstin; Hesse, Friedemann

2016-05-10

Fed-batch cultivation of recombinant Chinese hamster ovary (CHO) cell lines is one of the most widely used production modes for commercial manufacturing of recombinant protein therapeutics. Furthermore, fed-batch cultivations are often conducted as biphasic processes where the culture temperature is decreased to maximize volumetric product yields. However, it remains to be elucidated which intracellular regulatory elements actually control the observed pro-productive phenotypes. Recently, several studies have revealed microRNAs (miRNAs) to be important molecular switches of cell phenotypes. In this study, we analyzed miRNA profiles of two different recombinant CHO cell lines (high and low producer), and compared them to a non-producing CHO DG44 host cell line during fed-batch cultivation at 37°C versus a temperature shift to 30°C. Taking advantage of next-generation sequencing combined with cluster, correlation and differential expression analyses, we could identify 89 different miRNAs, which were differentially expressed in the different cell lines and cultivation phases. Functional validation experiments using 19 validated target miRNAs confirmed that these miRNAs indeed induced changes in process relevant phenotypes. Furthermore, computational miRNA target prediction combined with functional clustering identified putative target genes and cellular pathways, which might be regulated by these miRNAs. This study systematically identified novel target miRNAs during different phases and conditions of a biphasic fed-batch production process and functionally evaluated their potential for host cell engineering. Copyright © 2016. Published by Elsevier B.V.

Plant parasitic nematode effectors target host defense and nuclear functions to establish feeding cells.

PubMed

Quentin, Michaëel; Abad, Pierre; Favery, Bruno

2013-01-01

Plant parasitic nematodes are microscopic worms, the most damaging species of which have adopted a sedentary lifestyle within their hosts. These obligate endoparasites have a biotrophic relationship with plants, in which they induce the differentiation of root cells into hypertrophied, multinucleate feeding cells (FCs). Effectors synthesized in the esophageal glands of the nematode are injected into the plant cells via the syringe-like stylet and play a key role in manipulating the host machinery. The establishment of specialized FCs requires these effectors to modulate many aspects of plant cell morphogenesis and physiology, including defense responses. This cell reprogramming requires changes to host nuclear processes. Some proteins encoded by parasitism genes target host nuclei. Several of these proteins were immunolocalized within FC nuclei or shown to interact with host nuclear proteins. Comparative genomics and functional analyses are gradually revealing the roles of nematode effectors. We describe here these effectors and their hypothesized roles in the unique feeding behavior of these pests.

Real-Time Sensing of Enteropathogenic E. coli-Induced Effects on Epithelial Host Cell Height, Cell-Substrate Interactions, and Endocytic Processes by Infrared Surface Plasmon Spectroscopy

PubMed Central

Zlotkin-Rivkin, Efrat; Rund, David; Melamed-Book, Naomi; Zahavi, Eitan Erez; Perlson, Eran; Mercone, Silvana; Golosovsky, Michael; Davidov, Dan; Aroeti, Benjamin

2013-01-01

Enteropathogenic Escherichia coli (EPEC) is an important, generally non-invasive, bacterial pathogen that causes diarrhea in humans. The microbe infects mainly the enterocytes of the small intestine. Here we have applied our newly developed infrared surface plasmon resonance (IR-SPR) spectroscopy approach to study how EPEC infection affects epithelial host cells. The IR-SPR experiments showed that EPEC infection results in a robust reduction in the refractive index of the infected cells. Assisted by confocal and total internal reflection microscopy, we discovered that the microbe dilates the intercellular gaps and induces the appearance of fluid-phase-filled pinocytic vesicles in the lower basolateral regions of the host epithelial cells. Partial cell detachment from the underlying substratum was also observed. Finally, the waveguide mode observed by our IR-SPR analyses showed that EPEC infection decreases the host cell's height to some extent. Together, these observations reveal novel impacts of the pathogen on the host cell architecture and endocytic functions. We suggest that these changes may induce the infiltration of a watery environment into the host cell, and potentially lead to failure of the epithelium barrier functions. Our findings also indicate the great potential of the label-free IR-SPR approach to study the dynamics of host-pathogen interactions with high spatiotemporal sensitivity. PMID:24194932

Ultrastructural changes in the ovary cells of engorged Rhipicephalus sanguineus female ticks treated with esters of ricinoleic acid from castor oil (Ricinus communis).

PubMed

Sampieri, Bruno Rodrigues; Arnosti, André; Nunes, Pablo Henrique; Furquim, Karim Christina Scopinho; Chierice, Gilberto Orivaldo; Mathias, Maria Izabel Camargo

2012-05-01

Rhipicephalus sanguineus is a widely distributed tick species that has adapted to the urban environment, and the dog is its main host. This species is also known as a vector and reservoir of diseases caused by bacteria, protozoa, and viruses. Currently, acaricides of synthetic chemical origin have been widely and indiscriminately used, leading to the development of resistance to these products by ticks and causing damage to the environment. Thus, these issues have made it necessary to seek other forms of controlling these ectoparasites. R. sanguineus was artificially infested in host New Zealand White rabbits, which were divided into four treatment groups: control (CG1 and CG2) and treatment (TG1 and TG2) groups. TG1 and TG2 hosts were provided with feed supplemented with esters of ricinoleic acid from castor oil at a concentration of 5 g/kg of feed for 7 and 15 days. Afterward, the ovaries of the female ticks were removed for analysis by transmission electron microscopy. The results showed ultrastructural changes in the somatic and germ cells of ovaries from TG1 and TG2 females, particularly with respect to chorion deposition, a protective membrane of the oocyte, as well as in the transport process of vitellogenic materials via the hemolymph and pedicel cells. Moreover, the mitochondria were less electron-dense and had cristae that were more disorganized than the mitochondria from CG1 and CG2 individuals. Thus, this study demonstrated the action of esters on the ovaries of R. sanguineus, signaling the prospect of a way to control this ectoparasite without affecting nontarget organisms or the environment. Copyright © 2011 Wiley Periodicals, Inc.

Improved Acid Stress Survival of Lactococcus lactis Expressing the Histidine Decarboxylation Pathway of Streptococcus thermophilus CHCC1524*

PubMed Central

Trip, Hein; Mulder, Niels L.; Lolkema, Juke S.

2012-01-01

Degradative amino acid decarboxylation pathways in bacteria generate secondary metabolic energy and provide resistance against acid stress. The histidine decarboxylation pathway of Streptococcus thermophilus CHCC1524 was functionally expressed in the heterologous host Lactococcus lactis NZ9000, and the benefits of the newly acquired pathway for the host were analyzed. During growth in M17 medium in the pH range of 5–6.5, a small positive effect was observed on the biomass yield in batch culture, whereas no growth rate enhancement was evident. In contrast, a strong benefit for the engineered L. lactis strain was observed in acid stress survival. In the presence of histidine, the pathway enabled cells to survive at pH values as low as 3 for at least 2 h, conditions under which the host cells were rapidly dying. The flux through the histidine decarboxylation pathway in cells grown at physiological pH was under strict control of the electrochemical proton gradient (pmf) across the membrane. Ionophores that dissipated the membrane potential (ΔΨ) and/or the pH gradient (ΔpH) strongly increased the flux, whereas the presence of glucose almost completely inhibited the flux. Control of the pmf over the flux was exerted by both ΔΨ and ΔpH and was distributed over the transporter HdcP and the decarboxylase HdcA. The control allowed for a synergistic effect between the histidine decarboxylation and glycolytic pathways in acid stress survival. In a narrow pH range around 2.5 the synergism resulted in a 10-fold higher survival rate. PMID:22351775

Controlling the Biomimetic Implant Interface: Modulating Antimicrobial Activity by Spacer Design

NASA Astrophysics Data System (ADS)

Wisdom, Cate; Vanoosten, Sarah Kay; Boone, Kyle W.; Khvostenko, Dmytro; Arnold, Paul M.; Snead, Malcolm L.; Tamerler, Candan

2016-08-01

Surgical site infection is a common cause of post-operative morbidity, often leading to implant loosening, ultimately requiring revision surgery, increased costs and worse surgical outcomes. Since implant failure starts at the implant surface, creating and controlling the bio-material interface will play a critical role in reducing infection while improving host cell-to-implant interaction. Here, we engineered a biomimetic interface based upon a chimeric peptide that incorporates a titanium binding peptide (TiBP) with an antimicrobial peptide (AMP) into a single molecule to direct binding to the implant surface and deliver an antimicrobial activity against S. mutans and S. epidermidis, two bacteria which are linked with clinical implant infections. To optimize antimicrobial activity, we investigated the design of the spacer domain separating the two functional domains of the chimeric peptide. Lengthening and changing the amino acid composition of the spacer resulted in an improvement of minimum inhibitory concentration by a three-fold against S. mutans. Surfaces coated with the chimeric peptide reduced dramatically the number of bacteria, with up to a nine-fold reduction for S. mutans and a 48-fold reduction for S. epidermidis. Ab initio predictions of antimicrobial activity based on structural features were confirmed. Host cell attachment and viability at the biomimetic interface were also improved compared to the untreated implant surface. Biomimetic interfaces formed with this chimeric peptide offer interminable potential by coupling antimicrobial and improved host cell responses to implantable titanium materials, and this peptide based approach can be extended to various biomaterials surfaces.

The Frustrated Host Response to Legionella pneumophila Is Bypassed by MyD88-Dependent Translation of Pro-inflammatory Cytokines

PubMed Central

Asrat, Seblewongel; Dugan, Aisling S.; Isberg, Ralph R.

2014-01-01

Many pathogens, particularly those that require their host for survival, have devised mechanisms to subvert the host immune response in order to survive and replicate intracellularly. Legionella pneumophila, the causative agent of Legionnaires' disease, promotes intracellular growth by translocating proteins into its host cytosol through its type IV protein secretion machinery. At least 5 of the bacterial translocated effectors interfere with the function of host cell elongation factors, blocking translation and causing the induction of a unique host cell transcriptional profile. In addition, L. pneumophila also interferes with translation initiation, by preventing cap-dependent translation in host cells. We demonstrate here that protein translation inhibition by L. pneumophila leads to a frustrated host MAP kinase response, where genes involved in the pathway are transcribed but fail to be translated due to the bacterium-induced protein synthesis inhibition. Surprisingly, few pro-inflammatory cytokines, such as IL-1α and IL-1β, bypass this inhibition and get synthesized in the presence of Legionella effectors. We show that the selective synthesis of these genes requires MyD88 signaling and takes place in both infected cells that harbor bacteria and neighboring bystander cells. Our findings offer a perspective of how host cells are able to cope with pathogen-encoded activities that disrupt normal cellular process and initiate a successful inflammatory response. PMID:25058342

A translocated effector required for Bartonella dissemination from derma to blood safeguards migratory host cells from damage by co-translocated effectors.

PubMed

Okujava, Rusudan; Guye, Patrick; Lu, Yun-Yueh; Mistl, Claudia; Polus, Florine; Vayssier-Taussat, Muriel; Halin, Cornelia; Rolink, Antonius G; Dehio, Christoph

2014-06-01

Numerous bacterial pathogens secrete multiple effectors to modulate host cellular functions. These effectors may interfere with each other to efficiently control the infection process. Bartonellae are Gram-negative, facultative intracellular bacteria using a VirB type IV secretion system to translocate a cocktail of Bartonella effector proteins (Beps) into host cells. Based on in vitro infection models we demonstrate here that BepE protects infected migratory cells from injurious effects triggered by BepC and is required for in vivo dissemination of bacteria from the dermal site of inoculation to blood. Human endothelial cells (HUVECs) infected with a ΔbepE mutant of B. henselae (Bhe) displayed a cell fragmentation phenotype resulting from Bep-dependent disturbance of rear edge detachment during migration. A ΔbepCE mutant did not show cell fragmentation, indicating that BepC is critical for triggering this deleterious phenotype. Complementation of ΔbepE with BepEBhe or its homologues from other Bartonella species abolished cell fragmentation. This cyto-protective activity is confined to the C-terminal Bartonella intracellular delivery (BID) domain of BepEBhe (BID2.EBhe). Ectopic expression of BID2.EBhe impeded the disruption of actin stress fibers by Rho Inhibitor 1, indicating that BepE restores normal cell migration via the RhoA signaling pathway, a major regulator of rear edge retraction. An intradermal (i.d.) model for B. tribocorum (Btr) infection in the rat reservoir host mimicking the natural route of infection by blood sucking arthropods allowed demonstrating a vital role for BepE in bacterial dissemination from derma to blood. While the Btr mutant ΔbepDE was abacteremic following i.d. inoculation, complementation with BepEBtr, BepEBhe or BIDs.EBhe restored bacteremia. Given that we observed a similar protective effect of BepEBhe on infected bone marrow-derived dendritic cells migrating through a monolayer of lymphatic endothelial cells we propose that infected dermal dendritic cells may be involved in disseminating Bartonella towards the blood stream in a BepE-dependent manner.

A Translocated Effector Required for Bartonella Dissemination from Derma to Blood Safeguards Migratory Host Cells from Damage by Co-translocated Effectors

PubMed Central

Okujava, Rusudan; Guye, Patrick; Lu, Yun-Yueh; Mistl, Claudia; Polus, Florine; Vayssier-Taussat, Muriel; Halin, Cornelia; Rolink, Antonius G.; Dehio, Christoph

2014-01-01

Numerous bacterial pathogens secrete multiple effectors to modulate host cellular functions. These effectors may interfere with each other to efficiently control the infection process. Bartonellae are Gram-negative, facultative intracellular bacteria using a VirB type IV secretion system to translocate a cocktail of Bartonella effector proteins (Beps) into host cells. Based on in vitro infection models we demonstrate here that BepE protects infected migratory cells from injurious effects triggered by BepC and is required for in vivo dissemination of bacteria from the dermal site of inoculation to blood. Human endothelial cells (HUVECs) infected with a ΔbepE mutant of B. henselae (Bhe) displayed a cell fragmentation phenotype resulting from Bep-dependent disturbance of rear edge detachment during migration. A ΔbepCE mutant did not show cell fragmentation, indicating that BepC is critical for triggering this deleterious phenotype. Complementation of ΔbepE with BepEBhe or its homologues from other Bartonella species abolished cell fragmentation. This cyto-protective activity is confined to the C-terminal Bartonella intracellular delivery (BID) domain of BepEBhe (BID2.EBhe). Ectopic expression of BID2.EBhe impeded the disruption of actin stress fibers by Rho Inhibitor 1, indicating that BepE restores normal cell migration via the RhoA signaling pathway, a major regulator of rear edge retraction. An intradermal (i.d.) model for B. tribocorum (Btr) infection in the rat reservoir host mimicking the natural route of infection by blood sucking arthropods allowed demonstrating a vital role for BepE in bacterial dissemination from derma to blood. While the Btr mutant ΔbepDE was abacteremic following i.d. inoculation, complementation with BepEBtr, BepEBhe or BIDs.EBhe restored bacteremia. Given that we observed a similar protective effect of BepEBhe on infected bone marrow-derived dendritic cells migrating through a monolayer of lymphatic endothelial cells we propose that infected dermal dendritic cells may be involved in disseminating Bartonella towards the blood stream in a BepE-dependent manner. PMID:24945914

The Proteome of the Isolated Chlamydia trachomatis Containing Vacuole Reveals a Complex Trafficking Platform Enriched for Retromer Components

PubMed Central

Fischer, Martina; Jehmlich, Nico; Rose, Laura; Koch, Sophia; Laue, Michael; Renard, Bernhard Y.; Schmidt, Frank; Heuer, Dagmar

2015-01-01

Chlamydia trachomatis is an important human pathogen that replicates inside the infected host cell in a unique vacuole, the inclusion. The formation of this intracellular bacterial niche is essential for productive Chlamydia infections. Despite its importance for Chlamydia biology, a holistic view on the protein composition of the inclusion, including its membrane, is currently missing. Here we describe the host cell-derived proteome of isolated C. trachomatis inclusions by quantitative proteomics. Computational analysis indicated that the inclusion is a complex intracellular trafficking platform that interacts with host cells’ antero- and retrograde trafficking pathways. Furthermore, the inclusion is highly enriched for sorting nexins of the SNX-BAR retromer, a complex essential for retrograde trafficking. Functional studies showed that in particular, SNX5 controls the C. trachomatis infection and that retrograde trafficking is essential for infectious progeny formation. In summary, these findings suggest that C. trachomatis hijacks retrograde pathways for effective infection. PMID:26042774

Interspecific Germline Transmission of Cultured Primordial Germ Cells

PubMed Central

van de Lavoir, Marie-Cecile; Collarini, Ellen J.; Leighton, Philip A.; Fesler, Jeffrey; Lu, Daniel R.; Harriman, William D.; Thiyagasundaram, T. S.; Etches, Robert J.

2012-01-01

In birds, the primordial germ cell (PGC) lineage separates from the soma within 24 h following fertilization. Here we show that the endogenous population of about 200 PGCs from a single chicken embryo can be expanded one million fold in culture. When cultured PGCs are injected into a xenogeneic embryo at an equivalent stage of development, they colonize the testis. At sexual maturity, these donor PGCs undergo spermatogenesis in the xenogeneic host and become functional sperm. Insemination of semen from the xenogeneic host into females from the donor species produces normal offspring from the donor species. In our model system, the donor species is chicken (Gallus domesticus) and the recipient species is guinea fowl (Numida meleagris), a member of a different avian family, suggesting that the mechanisms controlling proliferation of the germline are highly conserved within birds. From a pragmatic perspective, these data are the basis of a novel strategy to produce endangered species of birds using domesticated hosts that are both tractable and fecund. PMID:22629301

Leishmania Hijacks Myeloid Cells for Immune Escape

PubMed Central

Martínez-López, María; Soto, Manuel; Iborra, Salvador; Sancho, David

2018-01-01

Protozoan parasites of the Leishmania genus are the causative agents of leishmaniasis, a group of neglected tropical diseases whose clinical manifestations vary depending on the infectious Leishmania species but also on host factors. Recognition of the parasite by host myeloid immune cells is a key to trigger an effective Leishmania-specific immunity. However, the parasite is able to persist in host myeloid cells by evading, delaying and manipulating host immunity in order to escape host resistance and ensure its transmission. Neutrophils are first in infiltrating infection sites and could act either favoring or protecting against infection, depending on factors such as the genetic background of the host or the parasite species. Macrophages are the main host cells where the parasites grow and divide. However, macrophages are also the main effector population involved in parasite clearance. Parasite elimination by macrophages requires the priming and development of an effector Th1 adaptive immunity driven by specific subtypes of dendritic cells. Herein, we will provide a comprehensive outline of how myeloid cells regulate innate and adaptive immunity against Leishmania, and the mechanisms used by the parasites to promote their evasion and sabotage. Understanding the interactions between Leishmania and the host myeloid cells may lead to the development of new therapeutic approaches and improved vaccination to leishmaniases, an important worldwide health problem in which current therapeutic or preventive approaches are limited. PMID:29867798

Other Types Of LCDs

NASA Astrophysics Data System (ADS)

Kobayashi, Shunsuke; Mochizuki, Akihiro

The following sections are included: * INTRODUCTION * TUNABLE BIREFRINGENCE LCDs * Nematic Device with Homogeneous Alignment * Nematic Device with Homeotropic Alignment * ELECTRICALLY CONTROLLED BIREFRINGENCE EFFECT LCDs WITH A COMPENSATING CELL OR POLYMER LAYERS * Super Homeotropic LCDs * Black and White STN LCDs * Optical mode interference * Guest-host mode * Double-layered STN * Retardation film compensated STN * DUAL FREQUENCY ADDRESSING LCDs * Application for DSM LCDs * Application for TN LCDs * PI-CELL * CHOLESTERIC-NEMATIC PHASE CHANGE LCDs * Storage Mode LCDs * Stabilized Hysteresis Mode LCDs * THERMALLY ADDRESSED LCDs (CHOLESTERIC) * BISTABLE LCD * WIDE VIEWING ANGLE TN LCDs USING RETARDATION SHEETS * Type 1 Cells * Type 2 Cells * REFERENCES

A virus or more in (nearly) every cell: ubiquitous networks of virus-host interactions in extreme environments.

PubMed

Munson-McGee, Jacob H; Peng, Shengyun; Dewerff, Samantha; Stepanauskas, Ramunas; Whitaker, Rachel J; Weitz, Joshua S; Young, Mark J

2018-06-01

The application of viral and cellular metagenomics to natural environments has expanded our understanding of the structure, functioning, and diversity of microbial and viral communities. The high diversity of many communities, e.g., soils, surface ocean waters, and animal-associated microbiomes, make it difficult to establish virus-host associations at the single cell (rather than population) level, assign cellular hosts, or determine the extent of viral host range from metagenomics studies alone. Here, we combine single-cell sequencing with environmental metagenomics to characterize the structure of virus-host associations in a Yellowstone National Park (YNP) hot spring microbial community. Leveraging the relatively low diversity of the YNP environment, we are able to overlay evidence at the single-cell level with contextualized viral and cellular community structure. Combining evidence from hexanucelotide analysis, single cell read mapping, network-based analytics, and CRISPR-based inference, we conservatively estimate that >60% of cells contain at least one virus type and a majority of these cells contain two or more virus types. Of the detected virus types, nearly 50% were found in more than 2 cellular clades, indicative of a broad host range. The new lens provided by the combination of metaviromics and single-cell genomics reveals a network of virus-host interactions in extreme environments, provides evidence that extensive virus-host associations are common, and further expands the unseen impact of viruses on cellular life.

Recruitment of EB1, a Master Regulator of Microtubule Dynamics, to the Surface of the Theileria annulata Schizont

PubMed Central

Woods, Kerry L.; Theiler, Romina; Mühlemann, Marcus; Segiser, Adrian; Huber, Sandra; Ansari, Hifzur R.; Pain, Arnab; Dobbelaere, Dirk A. E.

2013-01-01

The apicomplexan parasite Theileria annulata transforms infected host cells, inducing uncontrolled proliferation and clonal expansion of the parasitized cell population. Shortly after sporozoite entry into the target cell, the surrounding host cell membrane is dissolved and an array of host cell microtubules (MTs) surrounds the parasite, which develops into the transforming schizont. The latter does not egress to invade and transform other cells. Instead, it remains tethered to host cell MTs and, during mitosis and cytokinesis, engages the cell's astral and central spindle MTs to secure its distribution between the two daughter cells. The molecular mechanism by which the schizont recruits and stabilizes host cell MTs is not known. MT minus ends are mostly anchored in the MT organizing center, while the plus ends explore the cellular space, switching constantly between phases of growth and shrinkage (called dynamic instability). Assuming the plus ends of growing MTs provide the first point of contact with the parasite, we focused on the complex protein machinery associated with these structures. We now report how the schizont recruits end-binding protein 1 (EB1), a central component of the MT plus end protein interaction network and key regulator of host cell MT dynamics. Using a range of in vitro experiments, we demonstrate that T. annulata p104, a polymorphic antigen expressed on the schizont surface, functions as a genuine EB1-binding protein and can recruit EB1 in the absence of any other parasite proteins. Binding strictly depends on a consensus SxIP motif located in a highly disordered C-terminal region of p104. We further show that parasite interaction with host cell EB1 is cell cycle regulated. This is the first description of a pathogen-encoded protein to interact with EB1 via a bona-fide SxIP motif. Our findings provide important new insight into the mode of interaction between Theileria and the host cell cytoskeleton. PMID:23675298

Toll-Like Receptors 2 and 4 Cooperate in the Control of the Emerging Pathogen Brucella microti.

PubMed

Arias, Maykel A; Santiago, Llipsy; Costas-Ramon, Santiago; Jaime-Sánchez, Paula; Freudenberg, Marina; Jiménez De Bagüés, Maria P; Pardo, Julián

2016-01-01

Toll-like receptors (TLRs) recognize pathogen-derived molecules and play a critical role during the host innate and adaptive immune response. Brucella spp. are intracellular gram-negative bacteria including several virulent species, which cause a chronic zoonotic infection in a wide range of mammalian hosts known as brucellosis. A new Brucella species, Brucella microti , was recently isolated from wild rodents and found to be highly pathogenic in mice. Using this species-specific model, it was previously found that CD8 + T cells are required to control this infection. In order to find out the role of TLR-mediated responses in the control of this pathogen, the course of infection of B. microti was analyzed over 3 weeks in wild-type (WT) and TLR knock out (KO) mice including TLR2 -/- , TLR4 -/- , TLR9 -/- , TLR2×4 -/- and TLR2×4×9 -/- . WT and single TLR2, TLR4 and TLR9 KO mice similarly control infection in liver and spleen. In contrast, bacterial clearance was delayed in TLR2×4 -/- and TLR2×4×9 -/- mice at 7 and 14 days post-infection. This defect correlated with impaired maturation and pro-inflammatory cytokine production in B. microti -infected dendritic cells from TLR2×4 -/- and TLR2×4×9 -/- mice. Finally, it was found that Tc cells from TLR2×4 -/- and TLR2×4×9 -/- mice showed reduced ability to inhibit growth of B. microti in macrophages, suggesting the involvement of TLR2 and 4 in the generation of specific Tc cells. Our findings indicate that TLR2 and TLR4 are required to control B. microti infection in mice and that this effect could be related to its participation in the maturation of dendritic cells and the generation of specific CD8 + Tc cells.

Host-microbiota interactions: Epigenomic regulation

PubMed Central

Woo, Vivienne; Alenghat, Theresa

2016-01-01

The coevolution of mammalian hosts and their commensal microbiota has led to the development of complex symbiotic relationships between resident microbes and mammalian cells. Epigenomic modifications enable host cells to alter gene expression without modifying the genetic code, and therefore represent potent mechanisms by which mammalian cells can transcriptionally respond, transiently or stably, to environmental cues. Advances in genome-wide approaches are accelerating our appreciation of microbial influences on host physiology, and increasing evidence highlights that epigenomics represent a level of regulation by which the host integrates and responds to microbial signals. In particular, bacterial-derived short chain fatty acids have emerged as one clear link between how the microbiota intersects with host epigenomic pathways. Here we review recent findings describing crosstalk between the microbiota and epigenomic pathways in multiple mammalian cell populations. Further, we discuss interesting links that suggest that the scope of our understanding of epigenomic regulation in the host-microbiota relationship is still in its infancy. PMID:28103497

Cytolysin-dependent evasion of lysosomal killing.

PubMed

Håkansson, Anders; Bentley, Colette Cywes; Shakhnovic, Elizabeth A; Wessels, Michael R

2005-04-05

Local host defenses limit proliferation and systemic spread of pathogenic bacteria from sites of mucosal colonization. For pathogens such as streptococci that fail to grow intracellularly, internalization and killing by epithelial cells contribute to the control of bacterial growth and dissemination. Here, we show that group A Streptococcus (GAS), the agent of streptococcal sore throat and invasive soft tissue infections, evades internalization and intracellular killing by pharyngeal epithelial cells. Production of the cholesterol-binding cytotoxin streptolysin O (SLO) prevented internalization of GAS into lysosomes. In striking contrast, GAS rendered defective in production of SLO were internalized directly or rapidly transported into lysosomes, where they were killed by a pH-dependent mechanism. Because SLO is the prototype of cholesterol-dependent cytolysins produced by many Gram-positive bacteria, cytolysin-mediated evasion of lysosomal killing may be a general mechanism to protect such pathogens from clearance by host epithelial cells.

ATM facilitates mouse gammaherpesvirus reactivation from myeloid cells during chronic infection

PubMed Central

Kulinski, Joseph M.; Darrah, Eric J.; Broniowska, Katarzyna A.; Mboko, Wadzanai P.; Mounce, Bryan C.; Malherbe, Laurent P.; Corbett, John A; Gauld, Stephen B.; Tarakanova, Vera L.

2015-01-01

Gammaherpesviruses are cancer-associated pathogens that establish life-long infection in most adults. Insufficiency of Ataxia-Telangiectasia mutated (ATM) kinase leads to a poor control of chronic gammaherpesvirus infection via an unknown mechanism that likely involves a suboptimal antiviral response. In contrast to the phenotype in the intact host, ATM facilitates gammaherpesvirus reactivation and replication in vitro. We hypothesized that ATM mediates both pro- and antiviral activities to regulate chronic gammaherpesvirus infection in an immunocompetent host. To test the proposed proviral activity of ATM in vivo, we generated mice with ATM deficiency limited to myeloid cells. Myeloid-specific ATM deficiency attenuated gammaherpesvirus infection during the establishment of viral latency. The results of our study uncover a proviral role of ATM in the context of gammaherpesvirus infection in vivo and support a model where ATM combines pro- and antiviral functions to facilitate both gammaherpesvirus-specific T cell immune response and viral reactivation in vivo. PMID:26001649

Two interferon-independent double-stranded RNA-induced host defense strategies suppress the common cold virus at warm temperature.

PubMed

Foxman, Ellen F; Storer, James A; Vanaja, Kiran; Levchenko, Andre; Iwasaki, Akiko

2016-07-26

Most strains of rhinovirus (RV), the common cold virus, replicate better at cool temperatures found in the nasal cavity (33-35 °C) than at lung temperature (37 °C). Recent studies found that although 37 °C temperature suppressed RV growth largely by engaging the type 1 IFN response in infected epithelial cells, a significant temperature dependence to viral replication remained in cells devoid of IFN induction or signaling. To gain insight into IFN-independent mechanisms limiting RV replication at 37 °C, we studied RV infection in human bronchial epithelial cells and H1-HeLa cells. During the single replication cycle, RV exhibited temperature-dependent replication in both cell types in the absence of IFN induction. At 37 °C, earlier signs of apoptosis in RV-infected cells were accompanied by reduced virus production. Furthermore, apoptosis of epithelial cells was enhanced at 37 °C in response to diverse stimuli. Dynamic mathematical modeling and B cell lymphoma 2 (BCL2) overexpression revealed that temperature-dependent host cell death could partially account for the temperature-dependent growth observed during RV amplification, but also suggested additional mechanisms of virus control. In search of a redundant antiviral pathway, we identified a role for the RNA-degrading enzyme RNAseL. Simultaneous antagonism of apoptosis and RNAseL increased viral replication and dramatically reduced temperature dependence. These findings reveal two IFN-independent mechanisms active in innate defense against RV, and demonstrate that even in the absence of IFNs, temperature-dependent RV amplification is largely a result of host cell antiviral restriction mechanisms operating more effectively at 37 °C than at 33 °C.

The change in aggressiveness of neoplasms with age.

PubMed

Ershler, W B

1987-01-01

With aging, tumors occur more frequently. The "malignant" characteristics of tumors (ie, rapid growth and metastases), however, appear to be less prominent in the elderly. In experimental tumor models, similar observations have been recorded. The reason for this phenomenon could be that tumors (ie, malignant cells) are different in different-aged hosts. Alternatively, host features such as the fibrotic, angiogenic, or immune response may be altered by the aging process and may render the host "soil" less fertile for "malignant" tumor growth. Indeed, experimental evidence has supported the importance of each of these host features. The significance of the exploration and eventual understanding of the age-related change in tumor behavior extends beyond clinical geriatric medicine; it may, in fact, involve the very unraveling of some of the basic biology of both tumor control and the aging process itself.

Use of OmpU porins for attachment and invasion of Crassostrea gigas immune cells by the oyster pathogen Vibrio splendidus

PubMed Central

Duperthuy, Marylise; Schmitt, Paulina; Garzón, Edwin; Caro, Audrey; Rosa, Rafael D.; Le Roux, Frédérique; Lautrédou-Audouy, Nicole; Got, Patrice; Romestand, Bernard; de Lorgeril, Julien; Kieffer-Jaquinod, Sylvie; Bachère, Evelyne; Destoumieux-Garzón, Delphine

2011-01-01

OmpU porins are increasingly recognized as key determinants of pathogenic host Vibrio interactions. Although mechanisms remain incompletely understood, various species, including the human pathogen Vibrio cholera, require OmpU for host colonization and virulence. We have shown previously that OmpU is essential for virulence in the oyster pathogen Vibrio splendidus LGP32. Here, we showed that V. splendidus LGP32 invades the oyster immune cells, the hemocytes, through subversion of host-cell actin cytoskeleton. In this process, OmpU serves as an adhesin/invasin required for β-integrin recognition and host cell invasion. Furthermore, the major protein of oyster plasma, the extracellular superoxide dismutase Cg-EcSOD, is used as an opsonin mediating the OmpU-promoted phagocytosis through its RGD sequence. Finally, the endocytosed bacteria were found to survive intracellularly, evading the host defense by preventing acidic vacuole formation and limiting reactive oxygen species production. We conclude that (i) V. splendidus is a facultative intracellular pathogen that manipulates host defense mechanisms to enter and survive in host immune cells, and (ii) that OmpU is a major determinant of host cell invasion in Vibrio species, used by V. splendidus LGP32 to attach and invade oyster hemocytes through opsonisation by the oyster plasma Cg-EcSOD. PMID:21282662

Trypanosoma cruzi subverts the sphingomyelinase-mediated plasma membrane repair pathway for cell invasion

PubMed Central

Fernandes, Maria Cecilia; Cortez, Mauro; Flannery, Andrew R.; Tam, Christina; Mortara, Renato A.

2011-01-01

Upon host cell contact, the protozoan parasite Trypanosoma cruzi triggers cytosolic Ca2+ transients that induce exocytosis of lysosomes, a process required for cell invasion. However, the exact mechanism by which lysosomal exocytosis mediates T. cruzi internalization remains unclear. We show that host cell entry by T. cruzi mimics a process of plasma membrane injury and repair that involves Ca2+-dependent exocytosis of lysosomes, delivery of acid sphingomyelinase (ASM) to the outer leaflet of the plasma membrane, and a rapid form of endocytosis that internalizes membrane lesions. Host cells incubated with T. cruzi trypomastigotes are transiently wounded, show increased levels of endocytosis, and become more susceptible to infection when injured with pore-forming toxins. Inhibition or depletion of lysosomal ASM, which blocks plasma membrane repair, markedly reduces the susceptibility of host cells to T. cruzi invasion. Notably, extracellular addition of sphingomyelinase stimulates host cell endocytosis, enhances T. cruzi invasion, and restores normal invasion levels in ASM-depleted cells. Ceramide, the product of sphingomyelin hydrolysis, is detected in newly formed parasitophorous vacuoles containing trypomastigotes but not in the few parasite-containing vacuoles formed in ASM-depleted cells. Thus, T. cruzi subverts the ASM-dependent ceramide-enriched endosomes that function in plasma membrane repair to infect host cells. PMID:21536739

Comparative proteomics analysis of apoptotic Spodoptera frugiperda cells during p35 knockout Autographa californica multiple nucleopolyhedrovirus infection.

PubMed

Yu, Qian; Xiong, Youhua; Liu, Jianliang; Wang, Qin; Qiu, Yuanxin; Wen, Dongling

2016-06-01

Infection with Autographa californica multiple nucleopolyhedrovirus (AcMNPV) mutants lacking a functional p35 gene can induce host cell apoptosis, which provides the possibility to use the potential of these viruses in the biological control of pest insects. Nonetheless, the proteomics or the protein changes of Spodoptera frugiperda (Sf9) cells infected with p35 knockout AcMNPV have not yet been studied. To further improve the use of AcMNPV, we set out to analyze the protein composition and protein changes of Sf9 cells of different infection stages by isobaric tag for relative and absolute quantification (iTRAQ) techniques. A total of 4004 sf9 proteins were identified by iTRAQ. After comparation of the significantly expressed 483 proteins from p35koAcMNPV-infected Sf9 cells and the significantly expressed 413 proteins from wtAcMNPV-infected Sf9 cells, we found that 226 proteins were specific to p35koAcMNPV-infected Sf9 cells. The 226 proteins were categorized according to GO classification for insects and were categorized into: biological processes, molecular functions and cellular components. Of interest, the most up-regulated proteins related to Epstein-Barr virus infection, RNA transport, Calcium signaling pathway, cGMP-PKG signaling pathway, oxidative phosphorylation and N-Glycan biosynthesis. Determination of the protein changes in p35 knockout AcMNPV-infected Sf9 cells would facilitate the better use of this virus-host cell interaction in pest insect control and other related fields. Copyright © 2016 Elsevier Inc. All rights reserved.

Identification of Cell-Binding Adhesins of Leptospira interrogans

PubMed Central

Evangelista, Karen V.; Hahn, Beth; Wunder, Elsio A.; Ko, Albert I.; Haake, David A.; Coburn, Jenifer

2014-01-01

Leptospirosis is a globally distributed bacterial infectious disease caused by pathogenic members of the genus Leptospira. Infection can lead to illness ranging from mild and non-specific to severe, with jaundice, kidney and liver dysfunction, and widespread endothelial damage. The adhesion of pathogenic Leptospira species (spp.), the causative agent of leptospirosis, to host tissue components is necessary for infection and pathogenesis. While it is well-established that extracellular matrix (ECM) components play a role in the interaction of the pathogen with host molecules, we have shown that pathogenic Leptospira interrogans binds to host cells more efficiently than to ECM components. Using in vitro phage display to select for phage clones that bind to EA.hy926 endothelial cells, we identified the putative lipoproteins LIC10508 and LIC13411, and the conserved hypothetical proteins LIC12341 and LIC11574, as candidate L. interrogans sv. Copenhageni st. Fiocruz L1–130 adhesins. Recombinant LIC11574, but not its L. biflexa homologue LBF1629, exhibited dose-dependent binding to both endothelial and epithelial cells. In addition, LIC11574 and LIC13411 bind to VE-cadherin, an endothelial cell receptor for L. interrogans. Extraction of bacteria with the non-ionic detergent Triton X-114 resulted in partitioning of the candidate adhesins to the detergent fraction, a likely indication that these proteins are outer membrane localized. All candidate adhesins were recognized by sera obtained from leptospirosis patients but not by sera from healthy individuals as assessed by western blot. This work has identified bacterial adhesins that are potentially involved in L. interrogans infection of the mammalian host, and through cadherin binding, may contribute to dissemination and vascular damage. Our findings may be of value in leptospirosis control and prevention, with the bacterial adhesins potentially serving as targets for development of diagnostics, therapeutics, and vaccines. PMID:25275630

Microsporidia infection impacts the host cell's cycle and reduces host cell apoptosis

PubMed Central

Higes, Mariano; Sagastume, Soledad; Juarranz, Ángeles; Dias-Almeida, Joyce; Budge, Giles E.; Meana, Aránzazu; Boonham, Neil

2017-01-01

Intracellular parasites can alter the cellular machinery of host cells to create a safe haven for their survival. In this regard, microsporidia are obligate intracellular fungal parasites with extremely reduced genomes and hence, they are strongly dependent on their host for energy and resources. To date, there are few studies into host cell manipulation by microsporidia, most of which have focused on morphological aspects. The microsporidia Nosema apis and Nosema ceranae are worldwide parasites of honey bees, infecting their ventricular epithelial cells. In this work, quantitative gene expression and histology were studied to investigate how these two parasites manipulate their host’s cells at the molecular level. Both these microsporidia provoke infection-induced regulation of genes involved in apoptosis and the cell cycle. The up-regulation of buffy (which encodes a pro-survival protein) and BIRC5 (belonging to the Inhibitor Apoptosis protein family) was observed after infection, shedding light on the pathways that these pathogens use to inhibit host cell apoptosis. Curiously, different routes related to cell cycle were modified after infection by each microsporidia. In the case of N. apis, cyclin B1, dacapo and E2F2 were up-regulated, whereas only cyclin E was up-regulated by N. ceranae, in both cases promoting the G1/S phase transition. This is the first report describing molecular pathways related to parasite-host interactions that are probably intended to ensure the parasite’s survival within the cell. PMID:28152065

Identification of host transcriptional networks showing concentration-dependent regulation by HPV16 E6 and E7 proteins in basal cervical squamous epithelial cells

PubMed Central

Smith, Stephen P.; Scarpini, Cinzia G.; Groves, Ian J.; Odle, Richard I.; Coleman, Nicholas

2016-01-01

Development of cervical squamous cell carcinoma requires increased expression of the major high-risk human-papillomavirus (HPV) oncogenes E6 and E7 in basal cervical epithelial cells. We used a systems biology approach to identify host transcriptional networks in such cells and study the concentration-dependent changes produced by HPV16-E6 and -E7 oncoproteins. We investigated sample sets derived from the W12 model of cervical neoplastic progression, for which high quality phenotype/genotype data were available. We defined a gene co-expression matrix containing a small number of highly-connected hub nodes that controlled large numbers of downstream genes (regulons), indicating the scale-free nature of host gene co-expression in W12. We identified a small number of ‘master regulators’ for which downstream effector genes were significantly associated with protein levels of HPV16 E6 (n = 7) or HPV16 E7 (n = 5). We validated our data by depleting E6/E7 in relevant cells and by functional analysis of selected genes in vitro. We conclude that the network of transcriptional interactions in HPV16-infected basal-type cervical epithelium is regulated in a concentration-dependent manner by E6/E7, via a limited number of central master-regulators. These effects are likely to be significant in cervical carcinogenesis, where there is competitive selection of cells with elevated expression of virus oncoproteins. PMID:27457222

The Basis of OncoImmunology

PubMed Central

2016-01-01

Cancer heterogeneity, which enables clonal survival and treatment resistance, is shaped by active immune responses. Antigen-specific T cells can control cancer, as revealed clinically by immunotherapeutics such as adoptive T–cell transfer and checkpoint blockade. The host immune system is thus a powerful tool that if better harnessed could significantly enhance the efficacy of chemotherapeutics and improve outcomes for cancer sufferers. To realize this vision, however, a number of research frontiers must be tackled. These include developing strategies for neutralizing tumor-promoting inflammation, broadening T cell repertoires (via vaccination), and elucidating the mechanisms by which immune cells organize tumor microenvironments to regulate T cell activity. Such efforts will pave the way for identifying new targets for combination therapies that overcome resistance to current treatments and promote long-term cancer control. PMID:26967289

Protecting cows in small holder farms in East Africa from tsetse flies by mimicking the odor profile of a non-host bovid

PubMed Central

Orindi, Benedict O.; Mbahin, Norber; Muasa, Peter N.; Mbuvi, David M.; Muya, Caroline M.; Pickett, John A.; Borgemeister, Christian W.

2017-01-01

Background For the first time, differential attraction of pathogen vectors to vertebrate animals is investigated for novel repellents which when applied to preferred host animals turn them into non-hosts thereby providing a new paradigm for innovative vector control. For effectively controlling tsetse flies (Glossina spp.), vectors of African trypanosomosis, causing nagana, repellents more powerful than plant derived, from a non-host animal the waterbuck, Kobus ellipsiprymnus defassa, have recently been identified. Here we investigate these repellents in the field to protect cattle from nagana by making cattle as unattractive as the buck. Methodology/Principal findings To dispense the waterbuck repellents comprising guaiacol, geranylacetone, pentanoic acid and δ-octalactone, (patent application) we developed an innovative collar-mounted release system for individual cattle. We tested protecting cattle, under natural tsetse challenge, from tsetse transmitted nagana in a large field trial comprising 1,100 cattle with repellent collars in Kenya for 24 months. The collars provided substantial protection to livestock from trypanosome infection by reducing disease levels >80%. Protected cattle were healthier, showed significantly reduced disease levels, higher packed cell volume and significantly increased weight. Collars >60% reduced trypanocide use, 72.7% increase in ownership of oxen per household and enhanced traction power (protected animals ploughed 66% more land than unprotected). Land under cultivation increased by 73.4%. Increase in traction power of protected animals reduced by 69.1% acres tilled by hand per household per ploughing season. Improved food security and household income from very high acceptance of collars (99%) motivated the farmers to form a registered community based organization promoting collars for integrated tsetse control and their commercialization. Conclusion/Significance Clear demonstration that repellents from un-preferred hosts prevent contact between host and vector, thereby preventing disease transmission: a new paradigm for vector control. Evidence that deploying water buck repellents converts cattle into non-hosts for tsetse flies—‘cows in waterbuck clothing’. PMID:29040267

Post-secretory fate of host defence components in mucus.

PubMed

Salathe, Matthias; Forteza, Rosanna; Conner, Gregory E

2002-01-01

Airway mucus is a complex mixture of secretory products that provide a multifaceted defence against infection. Among many antimicrobial substances, mucus contains a peroxidase identical to milk lactoperoxidase (LPO) that is produced by goblet cells and submucosal glands. Airway secretions contain the substrates for LPO, namely thiocyanate and hydrogen peroxide, at concentrations sufficient for production of the biocidal compound hypothiocyanite, a fact confirmed by us in vitro. In vivo, inhibition of airway LPO in sheep significantly inhibits bacterial clearance, suggesting that the LPO system is a major contributor to host defences. Since secretory products including LPO are believed to be steadily removed by mucociliary clearance, their amount and availability on the surface is thought to be controlled solely by secretion. In contrast to this paradigm, new data suggest that LPO and other substances are retained at the ciliary border of the airway epithelium by binding to surface-associated hyaluronan, thereby providing an apical, fully active enzyme pool. Thus, hyaluronan, secreted from submucosal gland cells, plays a previously unrecognized pivotal role in mucosal host defence by retaining LPO and possibly other substances important for first line host defence at the apical surface 'ready for use' and protected from ciliary clearance.

Cytokine Diedel and a viral homologue suppress the IMD pathway in Drosophila.

PubMed

Lamiable, Olivier; Kellenberger, Christine; Kemp, Cordula; Troxler, Laurent; Pelte, Nadège; Boutros, Michael; Marques, Joao Trindade; Daeffler, Laurent; Hoffmann, Jules A; Roussel, Alain; Imler, Jean-Luc

2016-01-19

Viruses are obligatory intracellular parasites that suffer strong evolutionary pressure from the host immune system. Rapidly evolving viral genomes can adapt to this pressure by acquiring genes that counteract host defense mechanisms. For example, many vertebrate DNA viruses have hijacked cellular genes encoding cytokines or cytokine receptors to disrupt host cell communication. Insect viruses express suppressors of RNA interference or apoptosis, highlighting the importance of these cell intrinsic antiviral mechanisms in invertebrates. Here, we report the identification and characterization of a family of proteins encoded by insect DNA viruses that are homologous to a 12-kDa circulating protein encoded by the virus-induced Drosophila gene diedel (die). We show that die mutant flies have shortened lifespan and succumb more rapidly than controls when infected with Sindbis virus. This reduced viability is associated with deregulated activation of the immune deficiency (IMD) pathway of host defense and can be rescued by mutations in the genes encoding the homolog of IKKγ or IMD itself. Our results reveal an endogenous pathway that is exploited by insect viruses to modulate NF-κB signaling and promote fly survival during the antiviral response.

LAMP-2 absence interferes with plasma membrane repair and decreases T. cruzi host cell invasion.

PubMed

Couto, Natália Fernanda; Pedersane, Dina; Rezende, Luisa; Dias, Patrícia P; Corbani, Tayanne L; Bentini, Lívia C; Oliveira, Anny C S; Kelles, Ludmila F; Castro-Gomes, Thiago; Andrade, Luciana O

2017-06-01

Trypanosoma cruzi enters host cells by subverting the mechanism of cell membrane repair. In this process, the parasite induces small injuries in the host cell membrane leading to calcium entry and lysosomal exocytosis, which are followed by compensatory endocytosis events that drive parasites into host cells. We have previously shown that absence of both LAMP-1 and 2, major components of lysosomal membranes, decreases invasion of T. cruzi into host cells, but the mechanism by which they interfere with parasite invasion has not been described. Here we investigated the role of these proteins in parasitophorous vacuole morphology, host cell lysosomal exocytosis, and membrane repair ability. First, we showed that cells lacking only LAMP-2 present the same invasion phenotype as LAMP1/2-/- cells, indicating that LAMP-2 is an important player during T. cruzi invasion process. Second, neither vacuole morphology nor lysosomal exocytosis was altered in LAMP-2 lacking cells (LAMP2-/- and LAMP1/2-/- cells). We then investigated the ability of LAMP-2 deficient cells to perform compensatory endocytosis upon lysosomal secretion, the mechanism by which cells repair their membrane and T. cruzi ultimately enters cells. We observed that these cells perform less endocytosis upon injury when compared to WT cells. This was a consequence of impaired cholesterol traffic in cells lacking LAMP-2 and its influence in the distribution of caveolin-1 at the cell plasma membrane, which is crucial for plasma membrane repair. The results presented here show the major role of LAMP-2 in caveolin traffic and membrane repair and consequently in T. cruzi invasion.

LAMP-2 absence interferes with plasma membrane repair and decreases T. cruzi host cell invasion

PubMed Central

Rezende, Luisa; Bentini, Lívia C.; Oliveira, Anny C. S.

2017-01-01

Trypanosoma cruzi enters host cells by subverting the mechanism of cell membrane repair. In this process, the parasite induces small injuries in the host cell membrane leading to calcium entry and lysosomal exocytosis, which are followed by compensatory endocytosis events that drive parasites into host cells. We have previously shown that absence of both LAMP-1 and 2, major components of lysosomal membranes, decreases invasion of T. cruzi into host cells, but the mechanism by which they interfere with parasite invasion has not been described. Here we investigated the role of these proteins in parasitophorous vacuole morphology, host cell lysosomal exocytosis, and membrane repair ability. First, we showed that cells lacking only LAMP-2 present the same invasion phenotype as LAMP1/2-/- cells, indicating that LAMP-2 is an important player during T. cruzi invasion process. Second, neither vacuole morphology nor lysosomal exocytosis was altered in LAMP-2 lacking cells (LAMP2-/- and LAMP1/2-/- cells). We then investigated the ability of LAMP-2 deficient cells to perform compensatory endocytosis upon lysosomal secretion, the mechanism by which cells repair their membrane and T. cruzi ultimately enters cells. We observed that these cells perform less endocytosis upon injury when compared to WT cells. This was a consequence of impaired cholesterol traffic in cells lacking LAMP-2 and its influence in the distribution of caveolin-1 at the cell plasma membrane, which is crucial for plasma membrane repair. The results presented here show the major role of LAMP-2 in caveolin traffic and membrane repair and consequently in T. cruzi invasion. PMID:28586379

Alterations in the nuclear proteome of HIV-1 infected T-cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeBoer, Jason; Jagadish, Teena; Haverland, Nicole A.

Virus infection of a cell involves the appropriation of host factors and the innate defensive response of the cell. The identification of proteins critical for virus replication may lead to the development of novel, cell-based inhibitors. In this study we mapped the changes in T-cell nuclei during human immunodeficiency virus type 1 (HIV-1) at 20 hpi. Using a stringent data threshold, a total of 13 and 38 unique proteins were identified in infected and uninfected cells, respectively, across all biological replicates. An additional 15 proteins were found to be differentially regulated between infected and control nuclei. STRING analysis identified fourmore » clusters of protein–protein interactions in the data set related to nuclear architecture, RNA regulation, cell division, and cell homeostasis. Immunoblot analysis confirmed the differential expression of several proteins in both C8166-45 and Jurkat E6-1 T-cells. These data provide a map of the response in host cell nuclei upon HIV-1 infection. - Highlights: • We identify changes in the expression of nuclear proteins during HIV-1 infection. • 163 nuclear proteins were found differentially regulated during HIV-1 infection. • Bioinformatic analysis identified several nuclear pathways altered by HIV infection. • Candidate factors were validated in two independent cell lines.« less

Systemic Delivery of Salmonella Typhimurium Transformed with IDO shRNA Enhances Intratumoral Vector Colonization and Suppresses Tumor Growth

PubMed Central

Blache, Celine A.; Manuel, Edwin R.; Kaltcheva, Teodora I.; Wong, Andrea N.; Ellenhorn, Joshua D.I.; Blazar, Bruce R.; Diamond, Don J.

2012-01-01

Generating antitumor responses through the inhibition of tumor-derived immune suppression represents a promising strategy in the development of cancer immunotherapeutics. Here we present a strategy incorporating delivery of the bacterium Salmonella typhimurium (ST), naturally tropic for the hypoxic tumor environment, transformed with an shRNA plasmid against the immunosuppressive molecule indoleamine 2,3-dioxygenase 1 (shIDO). When systemically delivered into mice, shIDO silences host IDO expression and leads to massive intratumoral cell death that is associated with significant tumor infiltration by polymorphonuclear neutrophils (PMNs). shIDO-ST treatment causes tumor cell death independently of host IDO and adaptive immunity, which may have important implications for use in immunosuppressed cancer patients. Further, shIDO-ST treatment increases reactive oxygen species (ROS) produced by infiltrating PMNs and conversely, PMN immunodepletion abrogates tumor control. Silencing of host IDO significantly enhances ST colonization, suggesting that IDO expression within the tumor controls the immune response to ST. In summary, we present a novel approach to cancer treatment that involves the specific silencing of tumor-derived IDO that allows for the recruitment of ROS-producing PMNs, which may act primarily to clear ST infection, but in the process, also induces apoptosis of surrounding tumor tissue resulting in a vigorous anti-tumor effect. PMID:23090116

Contextual control of skin immunity and inflammation by Corynebacterium.

PubMed

Ridaura, Vanessa K; Bouladoux, Nicolas; Claesen, Jan; Chen, Y Erin; Byrd, Allyson L; Constantinides, Michael G; Merrill, Eric D; Tamoutounour, Samira; Fischbach, Michael A; Belkaid, Yasmine

2018-03-05

How defined microbes influence the skin immune system remains poorly understood. Here we demonstrate that Corynebacteria , dominant members of the skin microbiota, promote a dramatic increase in the number and activation of a defined subset of γδ T cells. This effect is long-lasting, occurs independently of other microbes, and is, in part, mediated by interleukin (IL)-23. Under steady-state conditions, the impact of Corynebacterium is discrete and noninflammatory. However, when applied to the skin of a host fed a high-fat diet, Corynebacterium accolens alone promotes inflammation in an IL-23-dependent manner. Such effect is highly conserved among species of Corynebacterium and dependent on the expression of a dominant component of the cell envelope, mycolic acid. Our data uncover a mode of communication between the immune system and a dominant genus of the skin microbiota and reveal that the functional impact of canonical skin microbial determinants is contextually controlled by the inflammatory and metabolic state of the host. © 2018 Ridaura et al.

MTOR-Driven Metabolic Reprogramming Regulates Legionella pneumophila Intracellular Niche Homeostasis

PubMed Central

Abshire, Camille F.; Roy, Craig R.

2016-01-01

Vacuolar bacterial pathogens are sheltered within unique membrane-bound organelles that expand over time to support bacterial replication. These compartments sequester bacterial molecules away from host cytosolic immunosurveillance pathways that induce antimicrobial responses. The mechanisms by which the human pulmonary pathogen Legionella pneumophila maintains niche homeostasis are poorly understood. We uncovered that the Legionella-containing vacuole (LCV) required a sustained supply of host lipids during expansion. Lipids shortage resulted in LCV rupture and initiation of a host cell death response, whereas excess of host lipids increased LCVs size and housing capacity. We found that lipids uptake from serum and de novo lipogenesis are distinct redundant supply mechanisms for membrane biogenesis in Legionella-infected macrophages. During infection, the metabolic checkpoint kinase Mechanistic Target of Rapamycin (MTOR) controlled lipogenesis through the Serum Response Element Binding Protein 1 and 2 (SREBP1/2) transcription factors. In Legionella-infected macrophages a host-driven response that required the Toll-like receptors (TLRs) adaptor protein Myeloid differentiation primary response gene 88 (Myd88) dampened MTOR signaling which in turn destabilized LCVs under serum starvation. Inactivation of the host MTOR-suppression pathway revealed that L. pneumophila sustained MTOR signaling throughout its intracellular infection cycle by a process that required the upstream regulator Phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and one or more Dot/Icm effector proteins. Legionella-sustained MTOR signaling facilitated LCV expansion and inhibition of the PI3K-MTOR-SREPB1/2 axis through pharmacological or genetic interference or by activation of the host MTOR-suppression response destabilized expanding LCVs, which in turn triggered cell death of infected macrophages. Our work identified a host metabolic requirement for LCV homeostasis and demonstrated that L. pneumophila has evolved to manipulate MTOR-dependent lipogenesis for optimal intracellular replication. PMID:27942021

Injectable Polyethylene Glycol Hydrogel for Islet Encapsulation: an in vitro and in vivo Characterization

PubMed Central

Knobeloch, Tracy; Abadi, Sakineh Esmaeili Mohsen; Bruns, Joseph; Zustiak, Silviya Petrova; Kwon, Guim

2017-01-01

An injection of hydrogel-encapsulated islets that controls blood glucose levels over long term would provide a much needed alternative treatment for type 1 diabetes mellitus (T1DM). To this end, we tested the feasibility of using an injectable polyethylene glycol (PEG) hydrogel as a scaffold for islet encapsulation. Encapsulated islets cultured in vitro for 6 days showed excellent cell viability and released insulin with higher basal and stimulated insulin secretion than control islets. Host responses to PEG hydrogels were studied by injecting PEG hydrogels (no treatment and vehicle controls used) into the peritoneal cavities of B6D2F1 mice and monitoring alterations in body weight, food and water intake, and blood glucose levels. After 2 weeks, peritoneal cavity cells were harvested, followed by hydrogel retrieval, and extraction of spleens. Body weights, food and water intake, and blood glucose levels were unaltered in mice injected with hydrogels compared to no treatment and vehicle-injected control mice. Frozen sections of a hydrogel showed the presence of tissues and small number of immune cells surrounding the hydrogel but no cell infiltration into the hydrogel bulk. Spleen sizes were not significantly different under the experimental conditions. Peritoneal cavity cells were slightly higher in mice injected with hydrogels compared to control mice but no statistical difference between vehicle- and hydrogel-injected mice was noted. As an in vivo feasibility study, streptozotocin-induced diabetic mice were injected with vehicle or hydrogels containing 50 islets each into two sites, the peritoneal cavity and a subcutaneous site on the back. Transient control of blood glucose levels were observed in mice injected with hydrogels containing islets. In summary, we developed an injectable PEG hydrogel that supported islet function and survival in vitro and in vivo and elicited only a mild host response. Our work illustrates the feasibility of using injectable PEG hydrogels for islet encapsulation. PMID:29527325

The role played by the group A streptococcal negative regulator Nra on bacterial interactions with epithelial cells.

PubMed

Molinari, G; Rohde, M; Talay, S R; Chhatwal, G S; Beckert, S; Podbielski, A

2001-04-01

Group A streptococci (GAS) specifically attach to and internalize into human epithelial host cells. In some GAS isolates, fibronectin-binding proteins were identified as being responsible for these virulence traits. In the present study, the previously identified global negative regulator Nra was shown to control the binding of soluble fibronectin probably via regulation of protein F2 and/or SfbII expression in the serotype M49 strain 591. According to results from a conventional invasion assay based on the recovery of viable intracellular bacteria, the increased fibronectin binding did not affect bacterial adherence to HEp-2 epithelial cells, but was associated with a reduction in the internalization rates. However, when examined by confocal and electron microscopy techniques, the nra-mutant bacteria were shown to exhibit higher adherence and internalization rates than the corresponding wild type. The mutant bacteria escaped from the phagocytic vacuoles much faster, promoting consistent morphological changes which resulted in severe host cell damage. The apoptotic and lytic processes observed in nra-mutant infected host cells were correlated with an increased expression of the genes encoding superantigen SpeA, the cysteine protease SpeB, and streptolysin S in the nra-mutant bacteria. Adherence and internalization rates of a nra/speB-double mutant at wild-type levels indicated that the altered speB expression in the nra mutant contributed to the observed changes in both processes. The Nra-dependent effects on bacterial virulence were confined to infections carried out with stationary growth phase bacteria. In conclusion, the obtained results demonstrated that the global GAS regulator Nra modulates virulence genes, which are involved in host cell damage. Thus, by helping to achieve a critical balance of virulence factor expression that avoids the injury of target cells, Nra may facilitate GAS persistence in a safe intracellular niche.

Simultaneous Evaluation of Life Cycle Dynamics between a Host Paramecium and the Endosymbionts of Paramecium bursaria Using Capillary Flow Cytometry.

PubMed

Takahashi, Toshiyuki

2016-08-17

Endosymbioses are driving forces underlying cell evolution. The endosymbiosis exhibited by Paramecium bursaria is an excellent model with which to study symbiosis. A single-cell microscopic analysis of P. bursaria reveals that endosymbiont numbers double when the host is in the division phase. Consequently, endosymbionts must arrange their cell cycle schedule if the culture-condition-dependent change delays the generation time of P. bursaria. However, it remains poorly understood whether endosymbionts keep pace with the culture-condition-dependent behaviors of P. bursaria, or not. Using microscopy and flow cytometry, this study investigated the life cycle behaviors occurring between endosymbionts and the host. To establish a connection between the host cell cycle and endosymbionts comprehensively, multivariate analysis was applied. The multivariate analysis revealed important information related to regulation between the host and endosymbionts. Results show that dividing endosymbionts underwent transition smoothly from the division phase to interphase, when the host was in the logarithmic phase. In contrast, endosymbiont division stagnated when the host was in the stationary phase. This paper explains that endosymbionts fine-tune their cell cycle pace with their host and that a synchronous life cycle between the endosymbionts and the host is guaranteed in the symbiosis of P. bursaria.

Simultaneous Evaluation of Life Cycle Dynamics between a Host Paramecium and the Endosymbionts of Paramecium bursaria Using Capillary Flow Cytometry

PubMed Central

Takahashi, Toshiyuki

2016-01-01

Endosymbioses are driving forces underlying cell evolution. The endosymbiosis exhibited by Paramecium bursaria is an excellent model with which to study symbiosis. A single-cell microscopic analysis of P. bursaria reveals that endosymbiont numbers double when the host is in the division phase. Consequently, endosymbionts must arrange their cell cycle schedule if the culture-condition-dependent change delays the generation time of P. bursaria. However, it remains poorly understood whether endosymbionts keep pace with the culture-condition-dependent behaviors of P. bursaria, or not. Using microscopy and flow cytometry, this study investigated the life cycle behaviors occurring between endosymbionts and the host. To establish a connection between the host cell cycle and endosymbionts comprehensively, multivariate analysis was applied. The multivariate analysis revealed important information related to regulation between the host and endosymbionts. Results show that dividing endosymbionts underwent transition smoothly from the division phase to interphase, when the host was in the logarithmic phase. In contrast, endosymbiont division stagnated when the host was in the stationary phase. This paper explains that endosymbionts fine-tune their cell cycle pace with their host and that a synchronous life cycle between the endosymbionts and the host is guaranteed in the symbiosis of P. bursaria. PMID:27531180

Butanol tolerance in microorganisms

DOEpatents

Bramucci, Michael G.; Nagarajan, Vasantha

2016-03-01

Provided herein are recombinant yeast host cells and methods for their use for production of fermentation products from a pyruvate utilizing pathway. Yeast host cells provided herein comprise reduced pyruvate decarboxylase activity and modified adenylate cyclase activity. In embodiments, yeast host cells provided herein comprise resistance to butanol and increased biomass production.

Methods for production of proteins in host cells

DOEpatents

Donnelly, Mark; Joachimiak, Andrzej

2004-01-13

The present invention provides methods for the production of proteins, particularly toxic proteins, in host cells. The invention provides methods which use a fusion protein comprising a chaperonin binding domain in host cells induced or regulated to have increased levels of chaperonin which binds the chaperonin binding domain.

Cloning and sequencing of pyruvate decarboxylase (PDC) genes from bacteria and uses therefor

DOEpatents

Maupin-Furlow, Julie A [Gainesville, FL; Talarico, Lee Ann [Gainesville, FL; Raj, Krishnan Chandra [Tamil Nadu, IN; Ingram, Lonnie O [Gainesville, FL

2008-02-05

The invention provides isolated nucleic acids molecules which encode pyruvate decarboxylase enzymes having improved decarboxylase activity, substrate affinity, thermostability, and activity at different pH. The nucleic acids of the invention also have a codon usage which allows for high expression in a variety of host cells. Accordingly, the invention provides recombinant expression vectors containing such nucleic acid molecules, recombinant host cells comprising the expression vectors, host cells further comprising other ethanologenic enzymes, and methods for producing useful substances, e.g., acetaldehyde and ethanol, using such host cells.

Oxygen-Dependent Globin Coupled Sensor Signaling Modulates Motility and Virulence of the Plant Pathogen Pectobacterium carotovorum.

PubMed

Burns, Justin L; Jariwala, Parth B; Rivera, Shannon; Fontaine, Benjamin M; Briggs, Laura; Weinert, Emily E

2017-08-18

Bacterial pathogens utilize numerous signals to identify the presence of their host and coordinate changes in gene expression that allow for infection. Within plant pathogens, these signals typically include small molecules and/or proteins from their plant hosts and bacterial quorum sensing molecules to ensure sufficient bacterial cell density for successful infection. In addition, bacteria use environmental signals to identify conditions when the host defenses are weakened and potentially to signal entry into an appropriate host/niche for infection. A globin coupled sensor protein (GCS), termed PccGCS, within the soft rot bacterium Pectobacterium carotovorum ssp. carotovorum WPP14 has been identified as an O 2 sensor and demonstrated to alter virulence factor excretion and control motility, with deletion of PccGCS resulting in decreased rotting of a potato host. Using small molecules that modulate bacterial growth and quorum sensing, PccGCS signaling also has been shown to modulate quorum sensing pathways, resulting in the PccGCS deletion strain being more sensitive to plant-derived phenolic acids, which can function as quorum sensing inhibitors, and exhibiting increased N-acylhomoserine lactone (AHL) production. These findings highlight a role for GCS proteins in controlling key O 2 -dependent phenotypes of pathogenic bacteria and suggest that modulating GCS signaling to limit P. carotovorum motility may provide a means to decrease rotting of plant hosts.

OSI-027 modulates acute graft-versus-host disease after liver transplantation in a rat model.

PubMed

Zhi, Xiao; Xue, Fei; Chen, Wei; Liang, Chao; Liu, Hao; Ma, Tao; Xia, Xuefeng; Hu, Liqiang; Bai, Xueli; Liang, Tingbo

2017-09-01

Despite its rarity (1%-2%), acute graft-versus-host disease after liver transplantation (LT-aGVHD) has a high mortality rate (85%). A gradual decrease in regulatory T cells (Tregs) correlates with disease progression in a rat LT-GVHD model, and treatments which increase Tregs exert therapeutic effects on LT-aGVHD. In this study, LT-aGVHD model rats were treated with rapamycin (RAPA), OSI-027, or an equal quantity of vehicle. Rats treated with OSI-027 survived longer (>100 days) than those in the RAPA (70 ± 8 days) or control (24 ± 3 days) groups. Flow cytometric analysis showed that the Treg ratios in peripheral blood mononuclear cells in the OSI-027 group were higher than those in the RAPA or control groups. The proportions of donor-derived lymphocytes in the OSI-027 group were lower than those in the RAPA or control groups. Hematoxylin-eosin staining of skin tissue demonstrated less severe lymphocyte infiltration in the OSI-027 group than that in the RAPA or control groups. In vitro, OSI-027 induced differentiation of CD4 + CD25 - T cells into CD4 + CD25 + forkhead box P3 + Tregs. Furthermore, injection of OSI-027-induced donor-derived CD4 + CD25 + T cells into the peripheral blood of LT-aGVHD model rats prevented LT-aGVHD. Thus, OSI-027 is implicated as a novel method for the treatment of LT-aGVHD. Liver Transplantation 23 1186-1198 2017 AASLD. © 2017 by the American Association for the Study of Liver Diseases.

Potential Sabotage of Host Cell Physiology by Apicomplexan Parasites for Their Survival Benefits

PubMed Central

Chakraborty, Shalini; Roy, Sonti; Mistry, Hiral Uday; Murthy, Shweta; George, Neena; Bhandari, Vasundhra; Sharma, Paresh

2017-01-01

Plasmodium, Toxoplasma, Cryptosporidium, Babesia, and Theileria are the major apicomplexan parasites affecting humans or animals worldwide. These pathogens represent an excellent example of host manipulators who can overturn host signaling pathways for their survival. They infect different types of host cells and take charge of the host machinery to gain nutrients and prevent itself from host attack. The mechanisms by which these pathogens modulate the host signaling pathways are well studied for Plasmodium, Toxoplasma, Cryptosporidium, and Theileria, except for limited studies on Babesia. Theileria is a unique pathogen taking into account the way it modulates host cell transformation, resulting in its clonal expansion. These parasites majorly modulate similar host signaling pathways, however, the disease outcome and effect is different among them. In this review, we discuss the approaches of these apicomplexan to manipulate the host–parasite clearance pathways during infection, invasion, survival, and egress. PMID:29081773

Amino Acid Control over Deoxyribonucleic Acid Synthesis in Escherichia coli Infected With T-Even Bacteriophage

PubMed Central

Donini, Pierluigi

1970-01-01

Starvation for a required amino acid of normal or RCstrEscherichia coli infected with T-even phages arrests further synthesis of phage deoxyribonucleic acid (DNA). This amino acid control over phage DNA synthesis does not occur in RCrelE. coli mutants. Heat inactivation of a temperature-sensitive aminoacyl-transfer ribonucleic acid (RNA) synthetase similarly causes an arrest of phage DNA synthesis in infected cells of RCstr phenotype but not in cells of RCrel phenotype. Inhibition of phage DNA synthesis in amino acid-starved RCstr host cells can be reversed by addition of chloramphenicol to the culture. Thus, the general features of amino acid control over T-even phage DNA synthesis are entirely analogous to those known for amino acid control over net RNA synthesis of uninfected bacteria. This analogy shows that the bacterial rel locus controls a wider range of macromolecular syntheses than had been previously thought. PMID:4914067

Systematical analysis of cutaneous squamous cell carcinoma network of microRNAs, transcription factors, and target and host genes.

PubMed

Wang, Ning; Xu, Zhi-Wen; Wang, Kun-Hao

2014-01-01

MicroRNAs (miRNAs) are small non-coding RNA molecules found in multicellular eukaryotes which are implicated in development of cancer, including cutaneous squamous cell carcinoma (cSCC). Expression is controlled by transcription factors (TFs) that bind to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to messenger RNA. Interactions result in biological signal control networks. Molecular components involved in cSCC were here assembled at abnormally expressed, related and global levels. Networks at these three levels were constructed with corresponding biological factors in term of interactions between miRNAs and target genes, TFs and miRNAs, and host genes and miRNAs. Up/down regulation or mutation of the factors were considered in the context of the regulation and significant patterns were extracted. Participants of the networks were evaluated based on their expression and regulation of other factors. Sub-networks with two core TFs, TP53 and EIF2C2, as the centers are identified. These share self-adapt feedback regulation in which a mutual restraint exists. Up or down regulation of certain genes and miRNAs are discussed. Some, for example the expression of MMP13, were in line with expectation while others, including FGFR3, need further investigation of their unexpected behavior. The present research suggests that dozens of components, miRNAs, TFs, target genes and host genes included, unite as networks through their regulation to function systematically in human cSCC. Networks built under the currently available sources provide critical signal controlling pathways and frequent patterns. Inappropriate controlling signal flow from abnormal expression of key TFs may push the system into an incontrollable situation and therefore contributes to cSCC development.

Lake viruses lyse cyanobacteria, Cylindrospermopsis raciborskii, enhances filamentous-host dispersal in Australia

NASA Astrophysics Data System (ADS)

Pollard, Peter C.; Young, Loretta M.

2010-01-01

Globally, cyanobacterial blooms are increasing along with observations of the controlling influence of viruses. Our aim here was to test whether viruses from an Australian freshwater lake could lyse the cyanobacterium Cylindrospermopsis raciborskii (Woloszynska) Seenaya and Subba Raju. C. raciborskii was selectively isolated from Lake Samsonvale southeast Queensland Australia using a Modified Jaworski Medium (without any form of inorganic nitrogen). Microscopy confirmed the resulting culture of a single cyanobacterial species. Natural viral-like particles (VLPs) were incubated with C. raciborskii cells, the host abundance decreased by 86% in 5 days, while the number of VLPs increased stepwise. As a cell lysed, the filaments of cells split into smaller, but viable, fragments. This process may help disperse the cyanobacterium in the wild. Hence the use of this virus to control blooms may inadvertently encourage the dispersal of toxic filamentous cyanobacteria. The cyanophage (virus infecting cyanobacteria) replication time was 21 h, with an average burst size of 64 viruses cell -1. Transmission Electron Microscopy showed this cyanophage for C. raciborskii, with its long, non-contractile tail and a capsid diameter of 70 nm, belongs to the Siphoviridae family of viruses. This cyanophage can affect the abundance and distribution of the cyanobacterium C. raciborskii in this Australian freshwater lake.

The Impact of Prophage on the Equilibria and Stability of Phage and Host

NASA Astrophysics Data System (ADS)

Yu, Pei; Nadeem, Alina; Wahl, Lindi M.

2017-06-01

In this paper, we present a bacteriophage model that includes prophage, that is, phage genomes that are incorporated into the host cell genome. The general model is described by an 18-dimensional system of ordinary differential equations. This study focuses on asymptotic behaviour of the model, and thus the system is reduced to a simple six-dimensional model, involving uninfected host cells, infected host cells and phage. We use dynamical system theory to explore the dynamic behaviour of the model, studying in particular the impact of prophage on the equilibria and stability of phage and host. We employ bifurcation and stability theory, centre manifold and normal form theory to show that the system has multiple equilibrium solutions which undergo a series of bifurcations, finally leading to oscillating motions. Numerical simulations are presented to illustrate and confirm the analytical predictions. The results of this study indicate that in some parameter regimes, the host cell population may drive the phage to extinction through diversification, that is, if multiple types of host emerge; this prediction holds even if the phage population is likewise diverse. This parameter regime is restricted, however, if infecting phage are able to recombine with prophage sequences in the host cell genome.

Legionella phospholipases implicated in virulence.

PubMed

Kuhle, Katja; Flieger, Antje

2013-01-01

Phospholipases are diverse enzymes produced in eukaryotic hosts and their bacterial pathogens. Several pathogen phospholipases have been identified as major virulence factors acting mainly in two different modes: on the one hand, they have the capability to destroy host membranes and on the other hand they are able to manipulate host signaling pathways. Reaction products of bacterial phospholipases may act as secondary messengers within the host and therefore influence inflammatory cascades and cellular processes, such as proliferation, migration, cytoskeletal changes as well as membrane traffic. The lung pathogen and intracellularly replicating bacterium Legionella pneumophila expresses a variety of phospholipases potentially involved in disease-promoting processes. So far, genes encoding 15 phospholipases A, three phospholipases C, and one phospholipase D have been identified. These cell-associated or secreted phospholipases may contribute to intracellular establishment, to egress of the pathogen from the host cell, and to the observed lung pathology. Due to the importance of phospholipase activities for host cell processes, it is conceivable that the pathogen enzymes may mimic or substitute host cell phospholipases to drive processes for the pathogen's benefit. The following chapter summarizes the current knowledge on the L. pneumophila phospholipases, especially their substrate specificity, localization, mode of secretion, and impact on host cells.

Graft-versus-host disease

MedlinePlus

GVHD; Bone marrow transplant - graft-versus-host disease; Stem cell transplant - graft-versus-host disease; Allogeneic transplant - ... GVHD may occur after a bone marrow, or stem cell, transplant in which someone receives bone marrow ...

High bacterial loads of Ureaplasma may be associated with non-specific cervicitis.

PubMed

Liu, Lu; Cao, Guojun; Zhao, Zhen; Zhao, Fang; Huang, Yanqun

2014-09-01

Ureaplasma parvum and Ureaplasma urealyticum are commonly found in the cervix of women with non-chlamydial and non-gonococcal cervicitis or non-specific cervicitis (NSC). However their contribution to the aetiology of NSC is controversial. U. parvum and U. urealyticum were identified and quantified in cervical swabs collected from 155 women with NSC and 312 controls without NSC, using real-time PCR. The relative bacterial quantification was then calculated using the Ureaplasma copy number divided by the number of host cells; this is important for the correction of bias linked to the number of cells harvested in different swabs. Ureaplasma was detected in 58.7% (91/155) of NSC patients: U. parvum in 30.3%, U. urealyticum in 16.1%, and mixed infection in 12.3%. It was also detected in 54.5% (170/312) of controls: U. parvum in 33.0%, U. urealyticum in 11.5%, and mixed infection in 9.9%. There were no significant differences for U. parvum, U. urealyticum, or mixed infection between the 2 groups (p > 0.05). However, both biovars were present at higher concentrations in NSC patients than in controls (p < 0.05). Using >10 copies/1000 cells as a reference, the positive rate of U. parvum in NSC patients was 16.1%, significantly higher than that in controls at 5.1% (relative risk 3.145, p < 0.05); positive rates of U. urealyticum in NSC patients and controls were 28.4% and 8.7%, respectively, with a statistically significant difference (relative risk 3.131, p < 0.05). Ureaplasma can adhere to host cells, colonize, internalize, and subsequently produce pathological lesions. A high density of Ureaplasma in the cervix may be associated with the aetiology of NSC.

Fierce Competition between Toxoplasma and Chlamydia for Host Cell Structures in Dually Infected Cells

PubMed Central

Romano, Julia D.; de Beaumont, Catherine; Carrasco, Jose A.; Ehrenman, Karen; Bavoil, Patrik M.

2013-01-01

The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients. PMID:23243063

Fierce competition between Toxoplasma and Chlamydia for host cell structures in dually infected cells.

PubMed

Romano, Julia D; de Beaumont, Catherine; Carrasco, Jose A; Ehrenman, Karen; Bavoil, Patrik M; Coppens, Isabelle

2013-02-01

The prokaryote Chlamydia trachomatis and the protozoan Toxoplasma gondii, two obligate intracellular pathogens of humans, have evolved a similar modus operandi to colonize their host cell and salvage nutrients from organelles. In order to gain fundamental knowledge on the pathogenicity of these microorganisms, we have established a cell culture model whereby single fibroblasts are coinfected by C. trachomatis and T. gondii. We previously reported that the two pathogens compete for the same nutrient pools in coinfected cells and that Toxoplasma holds a significant competitive advantage over Chlamydia. Here we have expanded our coinfection studies by examining the respective abilities of Chlamydia and Toxoplasma to co-opt the host cytoskeleton and recruit organelles. We demonstrate that the two pathogen-containing vacuoles migrate independently to the host perinuclear region and rearrange the host microtubular network around each vacuole. However, Toxoplasma outcompetes Chlamydia to the host microtubule-organizing center to the detriment of the bacterium, which then shifts to a stress-induced persistent state. Solely in cells preinfected with Chlamydia, the centrosomes become associated with the chlamydial inclusion, while the Toxoplasma parasitophorous vacuole displays growth defects. Both pathogens fragment the host Golgi apparatus and recruit Golgi elements to retrieve sphingolipids. This study demonstrates that the productive infection by both Chlamydia and Toxoplasma depends on the capability of each pathogen to successfully adhere to a finely tuned developmental program that aims to remodel the host cell for the pathogen's benefit. In particular, this investigation emphasizes the essentiality of host organelle interception by intravacuolar pathogens to facilitate access to nutrients.

Yersinia pestis and host macrophages: immunodeficiency of mouse macrophages induced by YscW.

PubMed

Bi, Yujing; Du, Zongmin; Han, Yanping; Guo, Zhaobiao; Tan, Yafang; Zhu, Ziwen; Yang, Ruifu

2009-09-01

The virulence of the pathogenic Yersinia species depends on a plasmid-encoded type III secretion system (T3SS) that transfers six Yersinia outer protein (Yop) effector proteins into the cytoplasm of eukaryotic cells, leading to disruption of host defence mechanisms. It is shown in this study that Yersinia pestis YscW, a protein of the T3SS injectisome, contributes to the induction of a deficiency in phagocytosis in host macrophages and a reduction in their antigen-presenting capacity. A Y. pestis strain lacking yscW had no effect on uptake by host macrophages. In mice infected with wild-type Y. pestis, the yscW mutant or a complement strain, immunodeficiency was observed in host macrophages compared with those from uninfected mice. However, the phagocytosis and antigen presenting capacities of macrophages infected by yscW mutant strain both in vivo and in vitro were significantly higher than those by wild type strain. Consistent with this finding, when YscW was expressed in the RAW264.7 macrophage cell line, phagocytosis and antigen-presenting capacities were significantly lower than those of the control groups. These results indicate that Y. pestis YscW may directly induce immunodeficiency in murine macrophages by crippling their phagocytosis and antigen-presenting capacities. These data provide evidences to Y. pestis pathogenesis that some proteins in T3SS injectisome, such as YscW protein, might play independent roles in disrupting host defense apart from their known functions.

Plasmodium falciparum exhibits markers of regulated cell death at high population density in vitro.

PubMed

Engelbrecht, Dewaldt; Coetzer, Thérèsa Louise

2016-12-01

The asexual erythrocytic cycle of the protozoan parasite Plasmodium falciparum is responsible for the pathogenesis of malaria and causes the overwhelming majority of malaria deaths. Rapidly increasing parasitaemia during this 48hour cycle threatens the survival of the human host and the parasite prior to transmission of the slow-maturing sexual stages to the mosquito host. The parasite may utilise regulated cell death (RCD) to control the burden of infection on the host and thus aid its own survival and transmission. The occurrence of RCD in P. falciparum remains a controversial topic. We provide strong evidence for the occurrence of an apoptosis-like phenotype of RCD in P. falciparum under conditions of high parasite density. P. falciparum was maintained in vitro and stressed by allowing growth to an unrestricted peak parasitaemia. Cell death markers, including morphological changes, DNA fragmentation, mitochondrial polarisation and phosphatidylserine externalisation were used to characterise parasite death at the time of peak parasitaemia and 24h later. At peak parasitaemia, mitochondrial depolarisation was observed, together with phosphatidylserine externalisation in both parasitised- and neighbouring non-infected erythrocytes. DNA fragmentation coincided with a decline in parasitaemia. Fewer merozoites were observed in mature schizonts at peak parasitaemia. Growth recovery to near-peak parasitaemia was noted within two intraerythrocytic cycles. The combination and chronological order of the biochemical markers of cell death suggest the occurrence of an apoptosis-like phenotype. The identification of a RCD pathway in P. falciparum may provide novel drug targets, particularly if the pathway differs from the host machinery. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Role and contribution of pulmonary CD103+ dendritic cells in the adaptive immune response to Mycobacterium tuberculosis.

PubMed

Koh, Vanessa Hui Qi; Ng, See Liang; Ang, Michelle Lay Teng; Lin, Wenwei; Ruedl, Christiane; Alonso, Sylvie

2017-01-01

Despite international control programmes, the global burden of tuberculosis remains enormous. Efforts to discover novel drugs have largely focused on targeting the bacterium directly. Alternatively, manipulating the host immune response may represent a valuable approach to enhance immunological clearance of the bacilli, but necessitates a deeper understanding of the immune mechanisms associated with protection against Mycobacterium tuberculosis infection. Here, we examined the various dendritic cells (DC) subsets present in the lung and draining lymph nodes (LN) from mice intra-tracheally infected with M. tuberculosis. We showed that although limited in number, pulmonary CD103 + DCs appeared to be involved in the initial transport of mycobacteria to the draining mediastinal LN and subsequent activation of T cells. Using CLEC9A-DTR transgenic mice enabling the inducible depletion of CD103 + DCs, we established that this DC subset contributes to the control of mycobacterial burden and plays a role in the early activation of T cells, in particular CD8 + T cells. Our findings thus support a previously unidentified role for pulmonary CD103 + DCs in the rapid mobilization of mycobacteria from the lungs to the draining LN soon after exposure to M. tuberculosis, which is a critical step for the development of the host adaptive immune response. Copyright © 2016 Elsevier Ltd. All rights reserved.

Viral Interactions with PDZ Domain-Containing Proteins-An Oncogenic Trait?

PubMed

James, Claire D; Roberts, Sally

2016-01-18

Many of the human viruses with oncogenic capabilities, either in their natural host or in experimental systems (hepatitis B and C, human T cell leukaemia virus type 1, Kaposi sarcoma herpesvirus, human immunodeficiency virus, high-risk human papillomaviruses and adenovirus type 9), encode in their limited genome the ability to target cellular proteins containing PSD95/ DLG/ZO-1 (PDZ) interaction modules. In many cases (but not always), the viruses have evolved to bind the PDZ domains using the same short linear peptide motifs found in host protein-PDZ interactions, and in some cases regulate the interactions in a similar fashion by phosphorylation. What is striking is that the diverse viruses target a common subset of PDZ proteins that are intimately involved in controlling cell polarity and the structure and function of intercellular junctions, including tight junctions. Cell polarity is fundamental to the control of cell proliferation and cell survival and disruption of polarity and the signal transduction pathways involved is a key event in tumourigenesis. This review focuses on the oncogenic viruses and the role of targeting PDZ proteins in the virus life cycle and the contribution of virus-PDZ protein interactions to virus-mediated oncogenesis. We highlight how many of the viral associations with PDZ proteins lead to deregulation of PI3K/AKT signalling, benefitting virus replication but as a consequence also contributing to oncogenesis.

Calcium Signaling throughout the Toxoplasma gondii Lytic Cycle

PubMed Central

Borges-Pereira, Lucas; Budu, Alexandre; McKnight, Ciara A.; Moore, Christina A.; Vella, Stephen A.; Hortua Triana, Miryam A.; Liu, Jing; Garcia, Celia R. S.; Pace, Douglas A.; Moreno, Silvia N. J.

2015-01-01

Toxoplasma gondii is an obligate intracellular parasite that invades host cells, creating a parasitophorous vacuole where it communicates with the host cell cytosol through the parasitophorous vacuole membrane. The lytic cycle of the parasite starts with its exit from the host cell followed by gliding motility, conoid extrusion, attachment, and invasion of another host cell. Here, we report that Ca2+ oscillations occur in the cytosol of the parasite during egress, gliding, and invasion, which are critical steps of the lytic cycle. Extracellular Ca2+ enhances each one of these processes. We used tachyzoite clonal lines expressing genetically encoded calcium indicators combined with host cells expressing transiently expressed calcium indicators of different colors, and we measured Ca2+ changes in both parasites and host simultaneously during egress. We demonstrated a link between cytosolic Ca2+ oscillations in the host and in the parasite. Our approach also allowed us to measure two new features of motile parasites, which were enhanced by Ca2+ influx. This is the first study showing, in real time, Ca2+ signals preceding egress and their direct link with motility, an essential virulence trait. PMID:26374900

CD62L− memory T cells enhance T-cell regeneration after allogeneic stem cell transplantation by eliminating host resistance in mice

PubMed Central

Zhang, Jifeng; Barefoot, Brice E.; Mo, Wenjian; Deoliveira, Divino; Son, Jessica; Cui, Xiuyu; Ramsburg, Elizabeth

2012-01-01

A major challenge in allogeneic hematopoietic cell transplantation is how to transfer T-cell immunity without causing graft-versus-host disease (GVHD). Effector memory T cells (CD62L−) are a cell subset that can potentially address this challenge because they do not induce GVHD. Here, we investigated how CD62L− T cells contributed to phenotypic and functional T-cell reconstitution after transplantation. On transfer into allogeneic recipients, CD62L− T cells were activated and expressed multiple cytokines and cytotoxic molecules. CD62L− T cells were able to deplete host radioresistant T cells and facilitate hematopoietic engraftment, resulting in enhanced de novo T-cell regeneration. Enhanced functional immune reconstitution was demonstrated in CD62L− T-cell recipients using a tumor and an influenza virus challenge model. Even though CD62L− T cells are able to respond to alloantigens and deplete host radioresistant immune cells in GVHD recipients, alloreactive CD62L− T cells lost the reactivity over time and were eventually tolerant to alloantigens as a result of prolonged antigen exposure, suggesting a mechanism by which CD62L− T cells were able to eliminate host resistance without causing GVHD. These data further highlight the unique characteristics of CD62L− T cells and their potential applications in clinical hematopoietic cell transplantation. PMID:22596261

Integration of living cells into nanostructures using non-conventional self-assembly

NASA Astrophysics Data System (ADS)

Carnes, Eric C.

Patternable cell immobilization is an essential feature of any solid-state device designed for interrogating or exploiting living cells. Immobilized cells must remain viable in a robust matrix that promotes fluidic connectivity between the cells and their environment while retaining the ability to establish and maintain necessary chemical gradients. A suitable inorganic matrix can be constructed via evaporation-induced self-assembly of nanostructured silica, in which phospholipids are used in place of traditional surfactant structure-directing agents in order to enhance cell viability and to create a coherent interface between the cell and the surrounding three-dimensional nanostructure. We have used this technique to develop two distinct cell encapsulation processes: cell-directed assembly and cell-directed integration. Cell-directed assembly is a one-step procedure that provides superior viability of immobilized cells by encouraging cells to interact with the developing host matrix. Limitations of this system include low viability for some cell types due to exposure to solvents and stresses, as well as a lack of control over the developing host nanostructure. Cell-directed integration addresses these shortcomings by introducing a two-step process in which cells become encapsulated in a pre-formed silica matrix. The validity of each encapsulation method has been demonstrated with Gram-positive and Gram-negative bacteria, yeast, and mammalian cells. The ability of the immobilized cells to establish relevant gradients of ions or signaling molecules, a key feature of these systems, has been characterized. Additionally, extension of cell encapsulation to address lingering questions in cell biology is addressed. We have also adapted these immobilization processes to be compatible with a variety of patterning strategies having tailorable properties. Widely available photolithography techniques, as well as direct aerosol deposition, have been adapted to provide methods for obtaining both positive and negative transfer of desired cell patterns. Multi-step lithography is also used to create a highly functional system allowing spatial control of not only cells but also media and other molecules of interest.

Picornaviruses and nuclear functions: targeting a cellular compartment distinct from the replication site of a positive-strand RNA virus

PubMed Central

Flather, Dylan; Semler, Bert L.

2015-01-01

The compartmentalization of DNA replication and gene transcription in the nucleus and protein production in the cytoplasm is a defining feature of eukaryotic cells. The nucleus functions to maintain the integrity of the nuclear genome of the cell and to control gene expression based on intracellular and environmental signals received through the cytoplasm. The spatial separation of the major processes that lead to the expression of protein-coding genes establishes the necessity of a transport network to allow biomolecules to translocate between these two regions of the cell. The nucleocytoplasmic transport network is therefore essential for regulating normal cellular functioning. The Picornaviridae virus family is one of many viral families that disrupt the nucleocytoplasmic trafficking of cells to promote viral replication. Picornaviruses contain positive-sense, single-stranded RNA genomes and replicate in the cytoplasm of infected cells. As a result of the limited coding capacity of these viruses, cellular proteins are required by these intracellular parasites for both translation and genomic RNA replication. Being of messenger RNA polarity, a picornavirus genome can immediately be translated upon entering the cell cytoplasm. However, the replication of viral RNA requires the activity of RNA-binding proteins, many of which function in host gene expression, and are consequently localized to the nucleus. As a result, picornaviruses disrupt nucleocytoplasmic trafficking to exploit protein functions normally localized to a different cellular compartment from which they translate their genome to facilitate efficient replication. Furthermore, picornavirus proteins are also known to enter the nucleus of infected cells to limit host-cell transcription and down-regulate innate antiviral responses. The interactions of picornavirus proteins and host-cell nuclei are extensive, required for a productive infection, and are the focus of this review. PMID:26150805

Stem cell recruitment of newly formed host cells via a successful seduction? Filling the gap between neurogenic niche and injured brain site.

PubMed

Tajiri, Naoki; Kaneko, Yuji; Shinozuka, Kazutaka; Ishikawa, Hiroto; Yankee, Ernest; McGrogan, Michael; Case, Casey; Borlongan, Cesar V

2013-01-01

Here, we report that a unique mechanism of action exerted by stem cells in the repair of the traumatically injured brain involves their ability to harness a biobridge between neurogenic niche and injured brain site. This biobridge, visualized immunohistochemically and laser captured, corresponded to an area between the neurogenic subventricular zone and the injured cortex. That the biobridge expressed high levels of extracellular matrix metalloproteinases characterized initially by a stream of transplanted stem cells, but subsequently contained only few to non-detectable grafts and overgrown by newly formed host cells, implicates a novel property of stem cells. The transplanted stem cells manifest themselves as pathways for trafficking the migration of host neurogenic cells, but once this biobridge is formed between the neurogenic site and the injured brain site, the grafted cells disappear and relinquish their task to the host neurogenic cells. Our findings reveal that long-distance migration of host cells from the neurogenic niche to the injured brain site can be achieved through transplanted stem cells serving as biobridges for initiation of endogenous repair mechanisms. This is the first report of a stem cell-paved "biobridge". Indeed, to date the two major schools of discipline in stem cell repair mechanism primarily support the concept of "cell replacement" and bystander effects of "trophic factor secretion". The present novel observations of a stem cell seducing a host cell to engage in brain repair advances basic science concepts on stem cell biology and extracellular matrix, as well as provokes translational research on propagating this stem cell-paved biobridge beyond cell replacement and trophic factor secretion for the treatment of traumatic brain injury and other neurological disorders.

Innate lymphoid cells in graft-versus-host disease.

PubMed

Konya, V; Mjösberg, J

2015-11-01

Innate lymphoid cells (ILC) are lymphocytes lacking rearranged antigen receptors such as those expressed by T and B cells. ILC are important effector and regulatory cells of the innate immune system, controlling lymphoid organogenesis, tissue inflammation, and homeostasis. The family of ILC consists of cytotoxic NK cells and the more recently described noncytotoxic group 1, 2, and 3 ILC. The classification of noncytotoxic ILC-in many aspects-mirrors that of T helper cells, which is based on the expression of master transcription factors and signature cytokines specific for each subset. The IL-22 producing RORγt(+) ILC3 subset was recently found to be critical in the prevention of intestinal graft-versus-host disease (GVHD) following allogeneic hematopoietic cell transplantation (HCT) via strengthening the intestinal mucosal barrier. In this review, we summarize the current view of the immunological functions of human noncytotoxic ILC subsets and discuss the potentially beneficial features of IL-22 producing ILC3 in improving allo-HCT efficacy by attenuating susceptibility to GVHD. In addition, we explore the possibility of other ILC subsets playing a role in GVHD. © 2015 The Authors. American Journal of Transplantation published by Wiley Periodicals, Inc. on behalf of American Society of Transplant Surgeons.

Bacillus megaterium SF185 induces stress pathways and affects the cell cycle distribution of human intestinal epithelial cells.

PubMed

Di Luccia, B; D'Apuzzo, E; Varriale, F; Baccigalupi, L; Ricca, E; Pollice, A

2016-09-01

The interaction between the enteric microbiota and intestinal cells often involves signal molecules that affect both microbial behaviour and host responses. Examples of such signal molecules are the molecules secreted by bacteria that induce quorum sensing mechanisms in the producing microorganism and signal transduction pathways in the host cells. The pentapeptide competence and sporulation factor (CSF) of Bacillus subtilis is a well characterized quorum sensing factor that controls competence and spore formation in the producing bacterium and induces cytoprotective heat shock proteins in intestinal epithelial cells. We analysed several Bacillus strains isolated from human ileal biopsies of healthy volunteers and observed that some of them were unable to produce CSF but still able to act in a CSF-like fashion on model intestinal epithelial cells. One of those strains belonging to the Bacillus megaterium species secreted at least two factors with effects on intestinal HT29 cells: a peptide smaller than 3 kDa able to induce heat shock protein 27 (hsp27) and p38-MAPK, and a larger molecule able to induce protein kinase B (PKB/Akt) with a pro-proliferative effect.

Functional paralysis of GM-CSF-derived bone marrow cells productively infected with ectromelia virus.

PubMed

Szulc-Dąbrowska, Lidia; Struzik, Justyna; Ostrowska, Agnieszka; Guzera, Maciej; Toka, Felix N; Bossowska-Nowicka, Magdalena; Gieryńska, Małgorzata M; Winnicka, Anna; Nowak, Zuzanna; Niemiałtowski, Marek G

2017-01-01

Ectromelia virus (ECTV) is an orthopoxvirus responsible for mousepox, a lethal disease of certain strains of mice that is similar to smallpox in humans, caused by variola virus (VARV). ECTV, similar to VARV, exhibits a narrow host range and has co-evolved with its natural host. Consequently, ECTV employs sophisticated and host-specific strategies to control the immune cells that are important for induction of antiviral immune response. In the present study we investigated the influence of ECTV infection on immune functions of murine GM-CSF-derived bone marrow cells (GM-BM), comprised of conventional dendritic cells (cDCs) and macrophages. Our results showed for the first time that ECTV is able to replicate productively in GM-BM and severely impaired their innate and adaptive immune functions. Infected GM-BM exhibited dramatic changes in morphology and increased apoptosis during the late stages of infection. Moreover, GM-BM cells were unable to uptake and process antigen, reach full maturity and mount a proinflammatory response. Inhibition of cytokine/chemokine response may result from the alteration of nuclear translocation of NF-κB, IRF3 and IRF7 transcription factors and down-regulation of many genes involved in TLR, RLR, NLR and type I IFN signaling pathways. Consequently, GM-BM show inability to stimulate proliferation of purified allogeneic CD4+ T cells in a primary mixed leukocyte reaction (MLR). Taken together, our data clearly indicate that ECTV induces immunosuppressive mechanisms in GM-BM leading to their functional paralysis, thus compromising their ability to initiate downstream T-cell activation events.

The REP2 Repeats of the Genome of Neisseria meningitidis Are Associated with Genes Coordinately Regulated during Bacterial Cell Interaction

PubMed Central

Morelle, Sandrine; Carbonnelle, Etienne; Nassif, Xavier

2003-01-01

Interaction with host cells is essential in meningococcal pathogenesis especially at the blood-brain barrier. This step is likely to involve a common regulatory pathway allowing coordinate regulation of genes necessary for the interaction with endothelial cells. The analysis of the genomic sequence of Neisseria meningitidis Z2491 revealed the presence of many repeats. One of these, designated REP2, contains a −24/−12 type promoter and a ribosome binding site 5 to 13 bp before an ATG. In addition most of these REP2 sequences are located immediately upstream of an ORF. Among these REP2-associated genes are pilC1 and crgA, described as being involved in steps essential for the interaction of N. meningitidis with host cells. Furthermore, the REP2 sequences located upstream of pilC1 and crgA correspond to the previously identified promoters known to be induced during the initial localized adhesion of N. meningitidis with human cells. This characteristic led us to hypothesize that at least some of the REP2-associated genes were upregulated under the same circumstances as pilC1 and crgA. Quantitative PCR in real time demonstrated that the expression of 14 out of 16 REP2-associated genes were upregulated during the initial localized adhesion of N. meningitidis. Taken together, these data suggest that these repeats control a set of genes necessary for the efficient interaction of this pathogen with host cells. Subsequent mutational analysis was performed to address the role of these genes during meningococcus-cell interaction. PMID:12670987

Dynamic Immune Cell Recruitment After Murine Pulmonary Aspergillus fumigatus Infection under Different Immunosuppressive Regimens

PubMed Central

Kalleda, Natarajaswamy; Amich, Jorge; Arslan, Berkan; Poreddy, Spoorthi; Mattenheimer, Katharina; Mokhtari, Zeinab; Einsele, Hermann; Brock, Matthias; Heinze, Katrin Gertrud; Beilhack, Andreas

2016-01-01

Humans are continuously exposed to airborne spores of the saprophytic fungus Aspergillus fumigatus. However, in healthy individuals pulmonary host defense mechanisms efficiently eliminate the fungus. In contrast, A. fumigatus causes devastating infections in immunocompromised patients. Host immune responses against A. fumigatus lung infections in immunocompromised conditions have remained largely elusive. Given the dynamic changes in immune cell subsets within tissues upon immunosuppressive therapy, we dissected the spatiotemporal pulmonary immune response after A. fumigatus infection to reveal basic immunological events that fail to effectively control invasive fungal disease. In different immunocompromised murine models, myeloid, notably neutrophils, and macrophages, but not lymphoid cells were strongly recruited to the lungs upon infection. Other myeloid cells, particularly dendritic cells and monocytes, were only recruited to lungs of corticosteroid treated mice, which developed a strong pulmonary inflammation after infection. Lymphoid cells, particularly CD4+ or CD8+ T-cells and NK cells were highly reduced upon immunosuppression and not recruited after A. fumigatus infection. Moreover, adoptive CD11b+ myeloid cell transfer rescued cyclophosphamide immunosuppressed mice from lethal A. fumigatus infection but not cortisone and cyclophosphamide immunosuppressed mice. Our findings illustrate that CD11b+ myeloid cells are critical for anti-A. fumigatus defense under cyclophosphamide immunosuppressed conditions. PMID:27468286

CD4 T cells promote rather than control tuberculosis in the absence of PD-1-mediated inhibition.

PubMed

Barber, Daniel L; Mayer-Barber, Katrin D; Feng, Carl G; Sharpe, Arlene H; Sher, Alan

2011-02-01

Although CD4 T cells are required for host resistance to Mycobacterium tuberculosis, they may also contribute to pathology. In this study, we examine the role of the inhibitory receptor PD-1 and its ligand PD-L1 during M. tuberculosis infection. After aerosol exposure, PD-1 knockout (KO) mice develop high numbers of M. tuberculosis-specific CD4 T cells but display markedly increased susceptibility to infection. Importantly, we show that CD4 T cells themselves drive the increased bacterial loads and pathology seen in infected PD-1 KO mice, and PD-1 deficiency in CD4 T cells is sufficient to trigger early mortality. PD-L1 KO mice also display enhanced albeit less severe susceptibility, indicating that T cells are regulated by multiple PD ligands during M. tuberculosis infection. M. tuberculosis-specific CD8 T cell responses were normal in PD-1 KO mice, and CD8 T cells only had a minor contribution to the exacerbated disease in the M. tuberculosis-infected PD-1 KO and PD-L1 KO mice. Thus, in the absence of the PD-1 pathway, M. tuberculosis benefits from CD4 T cell responses, and host resistance requires inhibition by PD-1 to prevent T cell-driven exacerbation of the infection.

Fine-mapping classical HLA variation associated with durable host control of HIV-1 infection in African Americans.

PubMed

McLaren, Paul J; Ripke, Stephan; Pelak, Kimberly; Weintrob, Amy C; Patsopoulos, Nikolaos A; Jia, Xiaoming; Erlich, Rachel L; Lennon, Niall J; Kadie, Carl M; Heckerman, David; Gupta, Namrata; Haas, David W; Deeks, Steven G; Pereyra, Florencia; Walker, Bruce D; de Bakker, Paul I W

2012-10-01

A small proportion of human immunodeficiency virus-1 (HIV-1) infected individuals, termed HIV-1 controllers, suppress viral replication to very low levels in the absence of therapy. Genetic investigations of this phenotype have strongly implicated variation in the class I major histocompatibility complex (MHC) region as key to HIV-1 control. We collected sequence-based classical class I HLA genotypes at 4-digit resolution in HIV-1-infected African American controllers and progressors (n = 1107), and tested them for association with host control using genome-wide single nucleotide polymorphism data to account for population structure. Several classical alleles at HLA-B were associated with host control, including B*57:03 [odds ratio (OR) = 5.1; P= 3.4 × 10(-18)] and B*81:01 (OR = 4.8; P= 1.3 × 10(-9)). Analysis of variable amino acid positions demonstrates that HLA-B position 97 is the most significant association with host control in African Americans (omnibus P = 1.2 × 10(-21)) and explains the signal of several HLA-B alleles, including B*57:03. Within HLA-B, we also identified independent effects at position 116 (omnibus P= 2.8 × 10(-15)) in the canonical F pocket, position 63 in the B pocket (P= 1.5 × 10(-3)) and the non-pocket position 245 (P= 8.8 × 10(-10)), which is thought to influence CD8-binding kinetics. Adjusting for these HLA-B effects, there is evidence for residual association in the MHC region. These results underscore the key role of HLA-B in affecting HIV-1 replication, likely through the molecular interaction between HLA-B and viral peptides presented by infected cells, and suggest that sites outside the peptide-binding pocket also influence HIV-1 control.

Adaptive Immune Responses following Senecavirus A Infection in Pigs.

PubMed

Maggioli, Mayara F; Lawson, Steve; de Lima, Marcelo; Joshi, Lok R; Faccin, Tatiane C; Bauermann, Fernando V; Diel, Diego G

2018-02-01

Senecavirus A (SVA), an emerging picornavirus of swine, causes vesicular disease (VD) that is clinically indistinguishable from foot-and-mouth disease (FMD) in pigs. Many aspects of SVA interactions with the host and the host immune responses to infection, however, remain unknown. In the present study, humoral and cellular immune responses to SVA were evaluated following infection in pigs. We show that SVA infection elicited an early and robust virus-neutralizing (VN) antibody response, which coincided and was strongly correlated with VP2- and VP3-specific IgM responses. Notably, the neutralizing antibody (NA) responses paralleled the reduction of viremia and resolution of the disease. Analysis of the major porcine T-cell subsets revealed that during the acute/clinical phase of SVA infection (14 days postinfection [p.i.]), T-cell responses were characterized by an increased frequency of αβ T cells, especially CD4 + T cells, which were first detected by day 7 p.i. and increased in frequency until day 14 p.i. Additionally, the frequency of CD8 + and double-positive CD4 + CD8 + T cells (effector/memory T cells) expressing interferon gamma (IFN-γ) or proliferating in response to SVA antigen stimulation increased after day 10 p.i. Results presented here show that SVA elicits B- and T-cell activation early upon infection, with IgM antibody levels being correlated with early neutralizing activity against the virus and peak B- and T-cell responses paralleling clinical resolution of the disease. The work provides important insights into the immunological events that follow SVA infection in the natural host. IMPORTANCE Senecavirus A (SVA) has recently emerged in swine, causing outbreaks of vesicular disease (VD) in major swine-producing countries around the world, including the United States, Brazil, China, Thailand, and Colombia. Notably, SVA-induced disease is clinically indistinguishable from other high-consequence VDs of swine, such as FMD, swine vesicular disease, vesicular stomatitis, and vesicular exanthema of swine. Despite the clinical relevance of SVA-induced VD, many aspects of the virus infection biology remain unknown. Here, we assessed host immune responses to SVA infection. The results show that SVA infection elicits early B- and T-cell responses, with the levels of VN antibody and CD4 + T-cell responses paralleling the reduction of viremia and resolution of the disease. SVA-specific CD8 + T cells are detected later during infection. A better understanding of SVA interactions with the host immune system may allow the design and implementation of improved control strategies for this important pathogen of swine. Copyright © 2018 American Society for Microbiology.

Brain microvascular endothelial-astrocyte cell responses following Japanese encephalitis virus infection in an in vitro human blood-brain barrier model.

PubMed

Patabendige, Adjanie; Michael, Benedict D; Craig, Alister G; Solomon, Tom

2018-06-01

Japanese encephalitis virus (JEV) remains a leading cause of encephalitis, globally, which continues to grow in importance despite the availability of vaccines. Viral entry into the brain can occur via the blood-brain barrier (BBB), and inflammation at the BBB is a common final pathway in many brain infections. However, the role of the BBB during JEV infection and the contribution of the endothelial and astrocytic cell inflammation in facilitating virus entry into the brain are incompletely understood. We established a BBB model using human brain endothelial cells (HBECs) and human astrocytes. HBECs are polarised, and therefore the model was inoculated by JEV from the apical side to simulate the in vivo situation. The effects of JEV on the BBB permeability and release of inflammatory mediators from both apical and basolateral sides, representing the blood and the brain side respectively were investigated. JEV infected HBECs with limited active virus production, before crossing the BBB and infecting astrocytes. Control of JEV production by HBECs was associated with a significant increase in permeability, and with elevation of many host mediators, including cytokines, chemokines, cellular adhesion molecules, and matrix metalloproteases. When compared to the controls, significantly higher amounts of mediators were released from the apical side as opposed to the basolateral side. The increased release of mediators over time also correlated with increased BBB permeability. Treatment with dexamethasone led to a significant reduction in the release of interleukin 6 (IL6), C-C motif chemokine ligand 5 (CCL5) and C-X-C motif chemokine ligand 10 (CXCL10) from the apical side with a reduction in BBB disruption and no change in JEV production. The results are consistent with the hypothesis that JEV infection of the BBB triggers the production of a range of host mediators from both endothelial cells and astrocytes, which control JEV production but disrupt BBB integrity thus allowing virus entry into the brain. Dexamethasone treatment controlled the host response and limited BBB disruption in the model without increasing JEV production, supporting a re-investigation of its use therapeutically. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

Variation in antibiotic-induced microbial recolonization impacts on the host metabolic phenotypes of rats.

PubMed

Swann, Jonathan R; Tuohy, Kieran M; Lindfors, Peter; Brown, Duncan T; Gibson, Glenn R; Wilson, Ian D; Sidaway, James; Nicholson, Jeremy K; Holmes, Elaine

2011-08-05

The interaction between the gut microbiota and their mammalian host is known to have far-reaching consequences with respect to metabolism and health. We investigated the effects of eight days of oral antibiotic exposure (penicillin and streptomycin sulfate) on gut microbial composition and host metabolic phenotype in male Han-Wistar rats (n = 6) compared to matched controls. Early recolonization was assessed in a third group exposed to antibiotics for four days followed by four days recovery (n = 6). Fluorescence in situ hybridization analysis of the intestinal contents collected at eight days showed a significant reduction in all bacterial groups measured (control, 10(10.7) cells/g feces; antibiotic-treated, 10(8.4)). Bacterial suppression reduced the excretion of mammalian-microbial urinary cometabolites including hippurate, phenylpropionic acid, phenylacetylglycine and indoxyl-sulfate whereas taurine, glycine, citrate, 2-oxoglutarate, and fumarate excretion was elevated. While total bacterial counts remained notably lower in the recolonized animals (10(9.1) cells/g faeces) compared to the controls, two cage-dependent subgroups emerged with Lactobacillus/Enterococcus probe counts dominant in one subgroup. This dichotomous profile manifested in the metabolic phenotypes with subgroup differences in tricarboxylic acid cycle metabolites and indoxyl-sulfate excretion. Fecal short chain fatty acids were diminished in all treated animals. Antibiotic treatment induced a profound effect on the microbiome structure, which was reflected in the metabotype. Moreover, the recolonization process was sensitive to the microenvironment, which may impact on understanding downstream consequences of antibiotic consumption in human populations.

Host manipulation by cancer cells: Expectations, facts, and therapeutic implications.

PubMed

Tissot, Tazzio; Arnal, Audrey; Jacqueline, Camille; Poulin, Robert; Lefèvre, Thierry; Mery, Frédéric; Renaud, François; Roche, Benjamin; Massol, François; Salzet, Michel; Ewald, Paul; Tasiemski, Aurélie; Ujvari, Beata; Thomas, Frédéric

2016-03-01

Similar to parasites, cancer cells depend on their hosts for sustenance, proliferation and reproduction, exploiting the hosts for energy and resources, and thereby impairing their health and fitness. Because of this lifestyle similarity, it is predicted that cancer cells could, like numerous parasitic organisms, evolve the capacity to manipulate the phenotype of their hosts to increase their own fitness. We claim that the extent of this phenomenon and its therapeutic implications are, however, underappreciated. Here, we review and discuss what can be regarded as cases of host manipulation in the context of cancer development and progression. We elaborate on how acknowledging the applicability of these principles can offer novel therapeutic and preventive strategies. The manipulation of host phenotype by cancer cells is one more reason to adopt a Darwinian approach in cancer research. © 2016 WILEY Periodicals, Inc.

A novel pathway to detect and cope with exogenous dsDNA.

PubMed

Kobayashi, Shouhei; Haraguchi, Tokuko

2015-01-01

How a living cell responds to exogenous materials is one of the fundamental questions in the life sciences. In particular, understanding the mechanisms by which a cell recognizes exogenous double-stranded DNA (dsDNA) is important for immunology research because it will facilitate the control of pathogen infections that entail the presence of exogenous dsDNA in the cytoplasm of host cells. Several cytosolic dsDNA sensor proteins that trigger innate immune responses have been identified and the downstream signaling pathways have been investigated. However, the events that occur at the site of exogenous dsDNA when it is exposed to the cytosol of the host cell remain unknown. Using dsDNA-coated polystyrene beads incorporated into living cells, we recently found that barrier-to-autointegration factor (BAF) binds to the exogenous dsDNA immediately after its appearance in the cytosol and plays a role in DNA avoidance of autophagy. Our findings reveal a novel pathway in which BAF plays a key role in the detection of and response to exogenous dsDNA.

Control of Paneth Cell Fate, Intestinal Inflammation, and Tumorigenesis by PKCλ/ι.

PubMed

Nakanishi, Yuki; Reina-Campos, Miguel; Nakanishi, Naoko; Llado, Victoria; Elmen, Lisa; Peterson, Scott; Campos, Alex; De, Surya K; Leitges, Michael; Ikeuchi, Hiroki; Pellecchia, Maurizio; Blumberg, Richard S; Diaz-Meco, Maria T; Moscat, Jorge

2016-09-20

Paneth cells are a highly specialized population of intestinal epithelial cells located in the crypt adjacent to Lgr5(+) stem cells, from which they differentiate through a process that requires downregulation of the Notch pathway. Their ability to store and release antimicrobial peptides protects the host from intestinal pathogens and controls intestinal inflammation. Here, we show that PKCλ/ι is required for Paneth cell differentiation at the level of Atoh1 and Gfi1, through the control of EZH2 stability by direct phosphorylation. The selective inactivation of PKCλ/ι in epithelial cells results in the loss of mature Paneth cells, increased apoptosis and inflammation, and enhanced tumorigenesis. Importantly, PKCλ/ι expression in human Paneth cells decreases with progression of Crohn's disease. Kaplan-Meier survival analysis of colorectal cancer (CRC) patients revealed that low PRKCI levels correlated with significantly worse patient survival rates. Therefore, PKCλ/ι is a negative regulator of intestinal inflammation and cancer through its role in Paneth cell homeostasis. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Orchestration of pulmonary T cell immunity during Mycobacterium tuberculosis infection: immunity interruptus

PubMed Central

Behar, Samuel M.; Carpenter, Stephen M.; Booty, Matthew G.; Barber, Daniel L.; Jayaraman, Pushpa

2014-01-01

Despite the introduction almost a century ago of Mycobacterium bovis BCG (BCG), an attenuated form of M. bovis that is used as a vaccine against Mycobacterium tuberculosis, tuberculosis remains a global health threat and kills more than 1.5 million people each year. This is mostly because BCG fails to prevent pulmonary disease – the contagious form of tuberculosis. Although there have been significant advances in understanding how the immune system responds to infection, the qualities that define protective immunity against M. tuberculosis remain poorly characterized. The ability to predict who will maintain control over the infection and who will succumb to clinical disease would revolutionize our approach to surveillance, control, and treatment. Here we review the current understanding of pulmonary T cell responses following M. tuberculosis infection. While infection elicits a strong immune response that contains infection, M. tuberculosis evades eradication. Traditionally, its intracellular lifestyle and alteration of macrophage function are viewed as the dominant mechanisms of evasion. Now we appreciate that chronic inflammation leads to T cell dysfunction. While this may arise as the host balances the goals of bacterial sterilization and avoidance of tissue damage, it is becoming clear that T cell dysfunction impairs host resistance. Defining the mechanisms that lead to T cell dysfunction is crucial as memory T cell responses are likely to be subject to the same subject to the same pressures. Thus, success of T cell based vaccines is predicated on memory T cells avoiding exhaustion while at the same time not promoting overt tissue damage. PMID:25311810

Orchestration of pulmonary T cell immunity during Mycobacterium tuberculosis infection: immunity interruptus.

PubMed

Behar, Samuel M; Carpenter, Stephen M; Booty, Matthew G; Barber, Daniel L; Jayaraman, Pushpa

2014-12-01

Despite the introduction almost a century ago of Mycobacterium bovis BCG (BCG), an attenuated form of M. bovis that is used as a vaccine against Mycobacterium tuberculosis, tuberculosis remains a global health threat and kills more than 1.5 million people each year. This is mostly because BCG fails to prevent pulmonary disease--the contagious form of tuberculosis. Although there have been significant advances in understanding how the immune system responds to infection, the qualities that define protective immunity against M. tuberculosis remain poorly characterized. The ability to predict who will maintain control over the infection and who will succumb to clinical disease would revolutionize our approach to surveillance, control, and treatment. Here we review the current understanding of pulmonary T cell responses following M. tuberculosis infection. While infection elicits a strong immune response that contains infection, M. tuberculosis evades eradication. Traditionally, its intracellular lifestyle and alteration of macrophage function are viewed as the dominant mechanisms of evasion. Now we appreciate that chronic inflammation leads to T cell dysfunction. While this may arise as the host balances the goals of bacterial sterilization and avoidance of tissue damage, it is becoming clear that T cell dysfunction impairs host resistance. Defining the mechanisms that lead to T cell dysfunction is crucial as memory T cell responses are likely to be subject to the same subject to the same pressures. Thus, success of T cell based vaccines is predicated on memory T cells avoiding exhaustion while at the same time not promoting overt tissue damage. Copyright © 2014 Elsevier Ltd. All rights reserved.

O-linked β-N-acetylglucosamine transferase directs cell proliferation in idiopathic pulmonary arterial hypertension.

PubMed

Barnes, Jarrod W; Tian, Liping; Heresi, Gustavo A; Farver, Carol F; Asosingh, Kewal; Comhair, Suzy A A; Aulak, Kulwant S; Dweik, Raed A

2015-04-07

Idiopathic pulmonary arterial hypertension (IPAH) is a cardiopulmonary disease characterized by cellular proliferation and vascular remodeling. A more recently recognized characteristic of the disease is the dysregulation of glucose metabolism. The primary link between altered glucose metabolism and cell proliferation in IPAH has not been elucidated. We aimed to determine the relationship between glucose metabolism and smooth muscle cell proliferation in IPAH. Human IPAH and control patient lung tissues and pulmonary artery smooth muscle cells (PASMCs) were used to analyze a specific pathway of glucose metabolism, the hexosamine biosynthetic pathway. We measured the levels of O-linked β-N-acetylglucosamine modification, O-linked β-N-acetylglucosamine transferase (OGT), and O-linked β-N-acetylglucosamine hydrolase in control and IPAH cells and tissues. Our data suggest that the activation of the hexosamine biosynthetic pathway directly increased OGT levels and activity, triggering changes in glycosylation and PASMC proliferation. Partial knockdown of OGT in IPAH PASMCs resulted in reduced global O-linked β-N-acetylglucosamine modification levels and abrogated PASMC proliferation. The increased proliferation observed in IPAH PASMCs was directly impacted by proteolytic activation of the cell cycle regulator, host cell factor-1. Our data demonstrate that hexosamine biosynthetic pathway flux is increased in IPAH and drives OGT-facilitated PASMC proliferation through specific proteolysis and direct activation of host cell factor-1. These findings establish a novel regulatory role for OGT in IPAH, shed a new light on our understanding of the disease pathobiology, and provide opportunities to design novel therapeutic strategies for IPAH. © 2015 American Heart Association, Inc.

Impact of calcium signaling during infection of Neisseria meningitidis to human brain microvascular endothelial cells.

PubMed

Asmat, Tauseef M; Tenenbaum, Tobias; Jonsson, Ann-Beth; Schwerk, Christian; Schroten, Horst

2014-01-01

The pili and outer membrane proteins of Neisseria meningitidis (meningococci) facilitate bacterial adhesion and invasion into host cells. In this context expression of meningococcal PilC1 protein has been reported to play a crucial role. Intracellular calcium mobilization has been implicated as an important signaling event during internalization of several bacterial pathogens. Here we employed time lapse calcium-imaging and demonstrated that PilC1 of meningococci triggered a significant increase in cytoplasmic calcium in human brain microvascular endothelial cells, whereas PilC1-deficient meningococci could not initiate this signaling process. The increase in cytosolic calcium in response to PilC1-expressing meningococci was due to efflux of calcium from host intracellular stores as demonstrated by using 2-APB, which inhibits the release of calcium from the endoplasmic reticulum. Moreover, pre-treatment of host cells with U73122 (phospholipase C inhibitor) abolished the cytosolic calcium increase caused by PilC1-expressing meningococci demonstrating that active phospholipase C (PLC) is required to induce calcium transients in host cells. Furthermore, the role of cytosolic calcium on meningococcal adherence and internalization was documented by gentamicin protection assay and double immunofluorescence (DIF) staining. Results indicated that chelation of intracellular calcium by using BAPTA-AM significantly impaired PilC1-mediated meningococcal adherence to and invasion into host endothelial cells. However, buffering of extracellular calcium by BAPTA or EGTA demonstrated no significant effect on meningococcal adherence to and invasion into host cells. Taken together, these results indicate that meningococci induce calcium release from intracellular stores of host endothelial cells via PilC1 and cytoplasmic calcium concentrations play a critical role during PilC1 mediated meningococcal adherence to and subsequent invasion into host endothelial cells.

Comparative Transcriptomic Analysis of Race 1 and Race 4 of Fusarium oxysporum f. sp. cubense Induced with Different Carbon Sources

PubMed Central

Qin, Shiwen; Ji, Chunyan; Li, Yunfeng; Wang, Zhenzhong

2017-01-01

The fungal pathogen Fusarium oxysporum f. sp. cubense causes Fusarium wilt, one of the most destructive diseases in banana and plantain cultivars. Pathogenic race 1 attacks the “Gros Michel” banana cultivar, and race 4 is pathogenic to the Cavendish banana cultivar and those cultivars that are susceptible to Foc1. To understand the divergence in gene expression modules between the two races during degradation of the host cell wall, we performed RNA sequencing to compare the genome-wide transcriptional profiles of the two races grown in media containing banana cell wall, pectin, or glucose as the sole carbon source. Overall, the gene expression profiles of Foc1 and Foc4 in response to host cell wall or pectin appeared remarkably different. When grown with host cell wall, a much larger number of genes showed altered levels of expression in Foc4 in comparison with Foc1, including genes encoding carbohydrate-active enzymes (CAZymes) and other virulence-related genes. Additionally, the levels of gene expression were higher in Foc4 than in Foc1 when grown with host cell wall or pectin. Furthermore, a great majority of genes were differentially expressed in a variety-specific manner when induced by host cell wall or pectin. More specific CAZymes and other pathogenesis-related genes were expressed in Foc4 than in Foc1 when grown with host cell wall. The first transcriptome profiles obtained for Foc during degradation of the host cell wall may provide new insights into the mechanism of banana cell wall polysaccharide decomposition and the genetic basis of Foc host specificity. PMID:28468818

Comparative Transcriptomic Analysis of Race 1 and Race 4 of Fusarium oxysporum f. sp. cubense Induced with Different Carbon Sources.

PubMed

Qin, Shiwen; Ji, Chunyan; Li, Yunfeng; Wang, Zhenzhong

2017-07-05

The fungal pathogen Fusarium oxysporum f. sp. cubense causes Fusarium wilt, one of the most destructive diseases in banana and plantain cultivars. Pathogenic race 1 attacks the "Gros Michel" banana cultivar, and race 4 is pathogenic to the Cavendish banana cultivar and those cultivars that are susceptible to Foc1. To understand the divergence in gene expression modules between the two races during degradation of the host cell wall, we performed RNA sequencing to compare the genome-wide transcriptional profiles of the two races grown in media containing banana cell wall, pectin, or glucose as the sole carbon source. Overall, the gene expression profiles of Foc1 and Foc4 in response to host cell wall or pectin appeared remarkably different. When grown with host cell wall, a much larger number of genes showed altered levels of expression in Foc4 in comparison with Foc1, including genes encoding carbohydrate-active enzymes (CAZymes) and other virulence-related genes. Additionally, the levels of gene expression were higher in Foc4 than in Foc1 when grown with host cell wall or pectin. Furthermore, a great majority of genes were differentially expressed in a variety-specific manner when induced by host cell wall or pectin. More specific CAZymes and other pathogenesis-related genes were expressed in Foc4 than in Foc1 when grown with host cell wall. The first transcriptome profiles obtained for Foc during degradation of the host cell wall may provide new insights into the mechanism of banana cell wall polysaccharide decomposition and the genetic basis of Foc host specificity. Copyright © 2017 Qin et al.

Interaction of Human Tumor Viruses with Host Cell Surface Receptors and Cell Entry

PubMed Central

Schäfer, Georgia; Blumenthal, Melissa J.; Katz, Arieh A.

2015-01-01

Currently, seven viruses, namely Epstein-Barr virus (EBV), Kaposi’s sarcoma-associated herpes virus (KSHV), high-risk human papillomaviruses (HPVs), Merkel cell polyomavirus (MCPyV), hepatitis B virus (HBV), hepatitis C virus (HCV) and human T cell lymphotropic virus type 1 (HTLV-1), have been described to be consistently associated with different types of human cancer. These oncogenic viruses belong to distinct viral families, display diverse cell tropism and cause different malignancies. A key to their pathogenicity is attachment to the host cell and entry in order to replicate and complete their life cycle. Interaction with the host cell during viral entry is characterized by a sequence of events, involving viral envelope and/or capsid molecules as well as cellular entry factors that are critical in target cell recognition, thereby determining cell tropism. Most oncogenic viruses initially attach to cell surface heparan sulfate proteoglycans, followed by conformational change and transfer of the viral particle to secondary high-affinity cell- and virus-specific receptors. This review summarizes the current knowledge of the host cell surface factors and molecular mechanisms underlying oncogenic virus binding and uptake by their cognate host cell(s) with the aim to provide a concise overview of potential target molecules for prevention and/or treatment of oncogenic virus infection. PMID:26008702

The role of iron in cancer.

PubMed

Weinberg, E D

1996-02-01

Numerous laboratory and clinical investigations over the past few decades have observed that one of the dangers of iron is its ability to favour neoplastic cell growth. The metal is carcinogenic due to its catalytic effect on the formation of hydroxyl radicals, suppression of the activity of host defence cells and promotion of cancer cell multiplication. In both animals and humans, primary neoplasms develop at body sites of excessive iron deposits. The invaded host attempts to withhold iron from the cancer cells via sequestration of the metal in newly formed ferritin. The host also endeavours to withdraw the metal from cancer cells via macrophage synthesis of nitric oxide. Quantitative evaluation of body iron and of iron-withholding proteins has prognostic value in cancer patients. Procedures associated with lowering host iron intake and inducing host cell iron efflux can assist in prevention and management of neoplastic diseases. Pharmaceutical methods for depriving neoplastic cells of iron are being developed in experimental and clinical protocols.

Adenovirus E4ORF1-induced MYC activation promotes host cell anabolic glucose metabolism and virus replication

PubMed Central

Thai, Minh; Graham, Nicholas A; Braas, Daniel; Nehil, Michael; Komisopoulou, Evangelia; Kurdistani, Siavash K.; McCormick, Frank; Graeber, Thomas G.; Christofk, Heather R.

2014-01-01

SUMMARY Virus infections trigger metabolic changes in host cells that support the bioenergetic and biosynthetic demands of viral replication. While recent studies have characterized virus-induced changes in host cell metabolism (Munger et al., 2008; Terry et al., 2012), the molecular mechanisms by which viruses reprogram cellular metabolism have remained elusive. Here we show that the gene product of adenovirus E4ORF1 is necessary for adenovirus-induced upregulation of host cell glucose metabolism and sufficient to promote enhanced glycolysis in cultured epithelial cells by activation of MYC. E4ORF1 localizes to the nucleus, binds to MYC, and enhances MYC binding to glycolytic target genes, resulting in elevated expression of specific glycolytic enzymes. E4ORF1 activation of MYC promotes increased nucleotide biosynthesis from glucose intermediates and enables optimal adenovirus replication in primary lung epithelial cells. Our findings show how a viral protein exploits host cell machinery to reprogram cellular metabolism and promote optimal progeny virion generation. PMID:24703700

Lipopolysaccharide structure impacts the entry kinetics of bacterial outer membrane vesicles into host cells

PubMed Central

Hadis, Mohammed; Alderwick, Luke

2017-01-01

Outer membrane vesicles are nano-sized microvesicles shed from the outer membrane of Gram-negative bacteria and play important roles in immune priming and disease pathogenesis. However, our current mechanistic understanding of vesicle-host cell interactions is limited by a lack of methods to study the rapid kinetics of vesicle entry and cargo delivery to host cells. Here, we describe a highly sensitive method to study the kinetics of vesicle entry into host cells in real-time using a genetically encoded, vesicle-targeted probe. We found that the route of vesicular uptake, and thus entry kinetics and efficiency, are shaped by bacterial cell wall composition. The presence of lipopolysaccharide O antigen enables vesicles to bypass clathrin-mediated endocytosis, which enhances both their entry rate and efficiency into host cells. Collectively, our findings highlight the composition of the bacterial cell wall as a major determinant of secretion-independent delivery of virulence factors during Gram-negative infections. PMID:29186191

Seeing through the dark: New insights into the immune regulatory functions of vitamin A

PubMed Central

Brown, Chrysothemis C.; Noelle, Randolph J.

2015-01-01

Summary The importance of vitamin A for host defense is undeniable and the study of its mechanisms is paramount. Of the estimated 250 million preschool children who are vitamin A deficient (VAD), 10% will die from their increased susceptibility to infectious disease. Vitamin A supplementation was established in the 1980s as one of the most successful interventions in the developing world. Understanding how Vitamin A controls immunity will curb the mortality and morbidity associated with VAD and exploit the immune enhancing capacity of vitamin A to heighten host resistance to infectious disease. The discoveries that retinoic acid (RA) imprints the homing of leukocytes to the gut and enhanced the induction of regulatory T-cells highlighted a potential role for RA in mucosal tolerance. However, emerging data tells of a more profound systemic impact of RA on leukocyte function and commitment. In animal models using genetic manipulation of RA signaling, we learn when and how RA controls T-cell fate. Here we review the role for RA as a critical checkpoint regulator in the differentiation of CD4+ T-cells within the immune system. PMID:25808452

Seeing through the dark: New insights into the immune regulatory functions of vitamin A.

PubMed

Brown, Chrysothemis C; Noelle, Randolph J

2015-05-01

The importance of vitamin A for host defense is undeniable and the study of its mechanisms is paramount. Of the estimated 250 million preschool children who are vitamin A-deficient (VAD), 10% will die from their increased susceptibility to infectious disease. Vitamin A supplementation was established in the 1980s as one of the most successful interventions in the developing world. Understanding how vitamin A controls immunity will help curb the mortality and morbidity associated with vitamin A deficiency and exploit the immune-enhancing capacity of vitamin A to heighten host resistance to infectious disease. The discoveries that retinoic acid (RA) imprints the homing of leukocytes to the gut and enhances the induction of regulatory T cells, highlighted a potential role for RA in mucosal tolerance. However, more recently emerging data tell of a more profound systemic impact of RA on leukocyte function and commitment. In animal models using genetic manipulation of RA signaling, we learned when and how RA controls T cell fate. Here, we review the role for RA as a critical checkpoint regulator in the differentiation of CD4(+) T cells within the immune system. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

HCMV triggers frequent and persistent UL40-specific unconventional HLA-E-restricted CD8 T-cell responses with potential autologous and allogeneic peptide recognition.

PubMed

Jouand, Nicolas; Bressollette-Bodin, Céline; Gérard, Nathalie; Giral, Magali; Guérif, Pierrick; Rodallec, Audrey; Oger, Romain; Parrot, Tiphaine; Allard, Mathilde; Cesbron-Gautier, Anne; Gervois, Nadine; Charreau, Béatrice

2018-04-01

Immune response against human cytomegalovirus (HCMV) includes a set of persistent cytotoxic NK and CD8 T cells devoted to eliminate infected cells and to prevent reactivation. CD8 T cells against HCMV antigens (pp65, IE1) presented by HLA class-I molecules are well characterized and they associate with efficient virus control. HLA-E-restricted CD8 T cells targeting HCMV UL40 signal peptides (HLA-EUL40) have recently emerged as a non-conventional T-cell response also observed in some hosts. The occurrence, specificity and features of HLA-EUL40 CD8 T-cell responses remain mostly unknown. Here, we detected and quantified these responses in blood samples from healthy blood donors (n = 25) and kidney transplant recipients (n = 121) and we investigated the biological determinants involved in their occurrence. Longitudinal and phenotype ex vivo analyses were performed in comparison to HLA-A*02/pp65-specific CD8 T cells. Using a set of 11 HLA-E/UL40 peptide tetramers we demonstrated the presence of HLA-EUL40 CD8 αβT cells in up to 32% of seropositive HCMV+ hosts that may represent up to 38% of total circulating CD8 T-cells at a time point suggesting a strong expansion post-infection. Host's HLA-A*02 allele, HLA-E *01:01/*01:03 genotype and sequence of the UL40 peptide from the infecting strain are major factors affecting the incidence of HLA-EUL40 CD8 T cells. These cells are effector memory CD8 (CD45RAhighROlow, CCR7-, CD27-, CD28-) characterized by a low level of PD-1 expression. HLA-EUL40 responses appear early post-infection and display a broad, unbiased, Vβ repertoire. Although induced in HCMV strain-dependent, UL4015-23-specific manner, HLA-EUL40 CD8 T cells are reactive toward a broader set of nonapeptides varying in 1-3 residues including most HLA-I signal peptides. Thus, HCMV induces strong and life-long lasting HLA-EUL40 CD8 T cells with potential allogeneic or/and autologous reactivity that take place selectively in at least a third of infections according to virus strain and host HLA concordance.

[Distribution diversity of integrins and calcium channels on major human and mouse host cells of Leptospira species].

PubMed

Li, Cheng-xue; Zhao, Xin; Qian, Jing; Yan, Jie

2012-07-01

To determine the distribution of integrins and calcium channels on major human and mouse host cells of Leptospira species. The expression of β1, β2 and β3 integrins was detected with immunofluorescence assay on the surface of human monocyte line THP-1, mouse mononuclear-macrophage-like cell line J774A.1, human vascular endothelial cell line HUVEC, mouse vascular endothelial cell EOMA, human hepatocyte line L-02, mouse hepatocyte line Hepa1-6, human renal tubular epithelial cell line HEK-293, mouse glomerular membrane epithelial cell line SV40-MES13, mouse collagen blast line NIH/3T3, human and mouse platelets. The distribution of voltage gate control calcium channels Cav3.1, Cav3.2, Cav3.3 and Cav2.3, and receptor gate calcium channels P(2)X(1), P(2)2X(2), P(2)X(3), P(2)X(4), P(2)X(5), P(2)X(6) and P(2)X(7) were determined with Western blot assay. β1 integrin proteins were positively expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, L-02, Hepa1-6 and HEK-239 cells as well as human and mouse platelets. β2 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, and NIH/3T3 cells. β3 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, Hepa1-6, HEK-239 and NIH/3T3 cells as well as human and mouse platelets. P(2)X(1) receptor gate calcium channel was expressed on the membrane surface of human and mouse platelets, while P(2)X(5) receptor gate calcium channel was expressed on the membrane surface of J774A.1, THP-1, L-02, Hepa1-6, HEK-239 and HUVEC cells. However, the other calcium channels were not detected on the tested cell lines or platelets. There is a large distribution diversity of integrins and calcium channel proteins on the major human and mouse host cells of Leptospira species, which may be associated with the differences of leptospira-induced injury in different host cells.

Host cells and methods for production of isobutanol

DOEpatents

Anthony, Larry Cameron; He, Hongxian; Huang, Lixuan Lisa; Okeefe, Daniel P.; Kruckeberg, Arthur Leo; Li, Yougen; Maggio-Hall, Lori; McElvain, Jessica; Nelson, Mark J.; Patnaik, Ranjan; Rothman, Steven Cary

2017-10-17

Provided herein are recombinant yeast host cells and methods for their use for production of isobutanol. Yeast host cells provided comprise an isobutanol biosynthetic pathway and at least one of reduced or eliminated aldehyde dehydrogenase activity, reduced or eliminated acetolactate reductase activity; or a heterologous polynucleotide encoding a polypeptide having ketol-acid reductoisomerase activity.