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Sample records for infection impairs toll-like

  1. Toll-like receptor sensing of human herpesvirus infection

    PubMed Central

    West, John A.; Gregory, Sean M.; Damania, Blossom

    2012-01-01

    Toll-like receptors (TLRs) are evolutionarily conserved pathogen sensors that constitute the first line of defense in the human immune system. Herpesviruses are prevalent throughout the world and cause significant disease in the human population. Sensing of herpesviruses via TLRs has only been documented in the last 10 years and our understanding of the relationship between these sentinels of the immune system and herpesvirus infection has already provided great insight into how the host cell responds to viral infection. This report will summarize the activation and modulation of TLR signaling in the context of human herpesvirus infections. PMID:23061052

  2. Toll-Like Receptor 4 Deficiency Impairs Motor Coordination

    PubMed Central

    Zhu, Jian-Wei; Li, Yi-Fei; Wang, Zhao-Tao; Jia, Wei-Qiang; Xu, Ru-Xiang

    2016-01-01

    The cerebellum plays an essential role in balance and motor coordination. Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex and are critical for the execution of its functions, including motor coordination. Toll-like receptor (TLR) 4 is involved in the innate immune response and is abundantly expressed in the central nervous system; however, little is known about its role in cerebellum-related motor functions. To address this question, we evaluated motor behavior in TLR4 deficient mice. We found that TLR4−∕− mice showed impaired motor coordination. Morphological analyses revealed that TLR4 deficiency was associated with a reduction in the thickness of the molecular layer of the cerebellum. TLR4 was highly expressed in PCs but not in Bergmann glia or cerebellar granule cells; however, loss of TLR4 decreased the number of PCs. These findings suggest a novel role for TLR4 in cerebellum-related motor coordination through maintenance of the PC population. PMID:26909014

  3. Toll-Like Receptors in Leishmania Infections: Guardians or Promoters?

    PubMed Central

    Faria, Marilia S.; Reis, Flavia C. G.; Lima, Ana Paula C. A.

    2012-01-01

    Protozoa of the genus Leishmania cause a wide variety of pathologies ranging from self-healing skin lesions to visceral damage, depending on the parasite species. The outcome of infection depends on the quality of the adaptive immune response, which is determined by parasite factors and the host genetic background. Innate responses, resulting in the generation of mediators with anti-leishmanial activity, contribute to parasite control and help the development of efficient adaptive responses. Among those, the potential contribution of members of the Toll-like receptors (TLRs) family in the control of Leishmania infections started to be investigated about a decade ago. Although most studies appoint a protective role for TLRs, there is growing evidence that in some cases, TLRs facilitate infection. This review highlights recent advances in TLR function during Leishmania infections and discusses their potential role in restraining parasite growth versus yielding disease. PMID:22523644

  4. Toll-Like Receptor Gene Expression during Trichinella spiralis Infection

    PubMed Central

    Kim, Sin; Park, Mi Kyung; Yu, Hak Sun

    2015-01-01

    In Trichinella spiralis infection, type 2 helper T (Th2) cell-related and regulatory T (Treg) cell-related immune responses are the most important immune events. In order to clarify which Toll-like receptors (TLRs) are closely associated with these responses, we analyzed the expression of mouse TLR genes in the small intestine and muscle tissue during T. spiralis infection. In addition, the expression of several chemokine- and cytokine-encoding genes, which are related to Th2 and Treg cell mediated immune responses, were analyzed in mouse embryonic fibroblasts (MEFs) isolated from myeloid differentiation factor 88 (MyD88)/TIR-associated proteins (TIRAP) and Toll receptor-associated activator of interferons (TRIF) adapter protein deficient and wild type (WT) mice. The results showed significantly increased TLR4 and TLR9 gene expression in the small intestine after 2 weeks of T. spiralis infection. In the muscle, TLR1, TLR2, TLR5, and TLR9 gene expression significantly increased after 4 weeks of infection. Only the expression of the TLR4 and TLR9 genes was significantly elevated in WT MEF cells after treatment with excretory-secretory (ES) proteins. Gene expression for Th2 chemokine genes were highly enhanced by ES proteins in WT MEF cells, while this elevation was slightly reduced in MyD88/TIRAP-/- MEF cells, and quite substantially decreased in TRIF-/- MEF cells. In contrast, IL-10 and TGF-β expression levels were not elevated in MyD88/TIRAP-/- MEF cells. In conclusion, we suggest that TLR4 and TLR9 might be closely linked to Th2 cell and Treg cell mediated immune responses, although additional data are needed to convincingly prove this observation. PMID:26323841

  5. Toll-Like Receptor Gene Expression during Trichinella spiralis Infection.

    PubMed

    Kim, Sin; Park, Mi Kyung; Yu, Hak Sun

    2015-08-01

    In Trichinella spiralis infection, type 2 helper T (Th2) cell-related and regulatory T (Treg) cell-related immune responses are the most important immune events. In order to clarify which Toll-like receptors (TLRs) are closely associated with these responses, we analyzed the expression of mouse TLR genes in the small intestine and muscle tissue during T. spiralis infection. In addition, the expression of several chemokine- and cytokine-encoding genes, which are related to Th2 and Treg cell mediated immune responses, were analyzed in mouse embryonic fibroblasts (MEFs) isolated from myeloid differentiation factor 88 (MyD88)/TIR-associated proteins (TIRAP) and Toll receptor-associated activator of interferons (TRIF) adapter protein deficient and wild type (WT) mice. The results showed significantly increased TLR4 and TLR9 gene expression in the small intestine after 2 weeks of T. spiralis infection. In the muscle, TLR1, TLR2, TLR5, and TLR9 gene expression significantly increased after 4 weeks of infection. Only the expression of the TLR4 and TLR9 genes was significantly elevated in WT MEF cells after treatment with excretory-secretory (ES) proteins. Gene expression for Th2 chemokine genes were highly enhanced by ES proteins in WT MEF cells, while this elevation was slightly reduced in MyD88/TIRAP(-/-) MEF cells, and quite substantially decreased in TRIF(-/-) MEF cells. In contrast, IL-10 and TGF-β expression levels were not elevated in MyD88/TIRAP(-/-) MEF cells. In conclusion, we suggest that TLR4 and TLR9 might be closely linked to Th2 cell and Treg cell mediated immune responses, although additional data are needed to convincingly prove this observation. PMID:26323841

  6. Toll-Like Receptor 2 Targeted Rectification of Impaired CD8+ T Cell Functions in Experimental Leishmania donovani Infection Reinstates Host Protection

    PubMed Central

    Bandyopadhyay, Syamdas; Kar Mahapatra, Santanu; Paul Chowdhury, Bidisha; Kumar Jha, Mukesh; Das, Shibali; Halder, Kuntal; Bhattacharyya Majumdar, Suchandra; Saha, Bhaskar; Majumdar, Subrata

    2015-01-01

    Leishmania donovani, a protozoan parasite, causes the disease visceral leishmanisis (VL), characterized by inappropriate CD8+ T-cell activation. Therefore, we examined whether the Toll-like Receptor 2 (TLR2) ligand Ara-LAM, a cell wall glycolipid from non-pathogenic Mycobacterium smegmatis, would restore CD8+ T-cell function during VL. We observed that by efficient upregulation of TLR2 signaling-mediated NF-κB translocation and MAPK signaling in CD8+ T-cells (CD25+CD28+IL-12R+IFN-γR+), Ara-LAM triggered signaling resulted in the activation of T-bet, which in turn, induced transcription favourable histone modification at the IFN-γ, perforin, granzyme-B promoter regions in CD8+ T-cells. Thus, we conclude that Ara-LAM induced efficient activation of effector CD8+ T-cells by upregulating the expression of IFN-γ, perforin and granzyme-B in an NF-κB and MAPK induced T-bet dependent manner in VL. PMID:26559815

  7. Toll-Like Receptor 9 Contributes to Defense against Acinetobacter baumannii Infection

    PubMed Central

    Noto, Michael J.; Boyd, Kelli L.; Burns, William J.; Varga, Matthew G.; Peek, Richard M.

    2015-01-01

    Acinetobacter baumannii is a common nosocomial pathogen capable of causing severe diseases associated with significant morbidity and mortality in impaired hosts. Pattern recognition receptors, such as the Toll-like receptors (TLRs), play a key role in pathogen detection and function to alert the immune system to infection. Here, we examine the role for TLR9 signaling in response to A. baumannii infection. In a murine model of A. baumannii pneumonia, TLR9−/− mice exhibit significantly increased bacterial burdens in the lungs, increased extrapulmonary bacterial dissemination, and more severe lung pathology compared with those in wild-type mice. Following systemic A. baumannii infection, TLR9−/− mice have significantly increased bacterial burdens in the lungs, as well as decreased proinflammatory cytokine and chemokine production. These results demonstrate that TLR9-mediated pathogen detection is important for host defense against the opportunistic pathogen Acinetobacter baumannii. PMID:26238713

  8. Bovine Viral Diarrhea Virus Type 2 Impairs Macrophage Responsiveness to Toll-Like Receptor Ligation with the Exception of Toll-Like Receptor 7.

    PubMed

    Schaut, Robert G; Ridpath, Julia F; Sacco, Randy E

    2016-01-01

    Bovine viral diarrhea virus (BVDV) is a member of the Flaviviridae family. BVDV isolates are classified into two biotypes based on the development of cytopathic (cp) or non-cytopathic (ncp) effects in epithelial cell culture. BVDV isolates are further separated into species, BVDV1 and 2, based on genetic differences. Symptoms of BVDV infection range from subclinical to severe, depending on strain virulence, and may involve multiple organ systems and induction of a generalized immunosuppression. During BVDV-induced immune suppression, macrophages, critical to innate immunity, may have altered pathogen recognition receptor (PRR) signaling, including signaling through toll-like receptors (TLRs). Comparison of BVDV 2 strains with different biotypes and virulence levels is valuable to determining if there are differences in host macrophage cellular responses between viral phenotypes. The current study demonstrates that cytopathic (cp), noncytopathic (ncp), high (hv) or low virulence (lv) BVDV2 infection of bovine monocyte-derived macrophages (MDMΦ) result in differential expression of pro-inflammatory cytokines compared to uninfected MDMΦ. A hallmark of cp BVDV2 infection is IL-6 production. In response to TLR2 or 4 ligation, as might be observed during secondary bacterial infection, cytokine secretion was markedly decreased in BVDV2-infected MDMΦ, compared to non-infected MDMΦ. Macrophages were hyporesponsive to viral TLR3 or TLR8 ligation. However, TLR7 stimulation of BVDV2-infected MDMΦ induced cytokine secretion, unlike results observed for other TLRs. Together, these data suggest that BVDV2 infection modulated mRNA responses and induced a suppression of proinflammatory cytokine protein responses to TLR ligation in MDMΦ with the exception of TLR7 ligation. It is likely that there are distinct differences in TLR pathways modulated following BVDV2 infection, which have implications for macrophage responses to secondary infections. PMID:27420479

  9. Bovine Viral Diarrhea Virus Type 2 Impairs Macrophage Responsiveness to Toll-Like Receptor Ligation with the Exception of Toll-Like Receptor 7

    PubMed Central

    Schaut, Robert G.; Ridpath, Julia F.; Sacco, Randy E.

    2016-01-01

    Bovine viral diarrhea virus (BVDV) is a member of the Flaviviridae family. BVDV isolates are classified into two biotypes based on the development of cytopathic (cp) or non-cytopathic (ncp) effects in epithelial cell culture. BVDV isolates are further separated into species, BVDV1 and 2, based on genetic differences. Symptoms of BVDV infection range from subclinical to severe, depending on strain virulence, and may involve multiple organ systems and induction of a generalized immunosuppression. During BVDV-induced immune suppression, macrophages, critical to innate immunity, may have altered pathogen recognition receptor (PRR) signaling, including signaling through toll-like receptors (TLRs). Comparison of BVDV 2 strains with different biotypes and virulence levels is valuable to determining if there are differences in host macrophage cellular responses between viral phenotypes. The current study demonstrates that cytopathic (cp), noncytopathic (ncp), high (hv) or low virulence (lv) BVDV2 infection of bovine monocyte-derived macrophages (MDMΦ) result in differential expression of pro-inflammatory cytokines compared to uninfected MDMΦ. A hallmark of cp BVDV2 infection is IL-6 production. In response to TLR2 or 4 ligation, as might be observed during secondary bacterial infection, cytokine secretion was markedly decreased in BVDV2-infected MDMΦ, compared to non-infected MDMΦ. Macrophages were hyporesponsive to viral TLR3 or TLR8 ligation. However, TLR7 stimulation of BVDV2-infected MDMΦ induced cytokine secretion, unlike results observed for other TLRs. Together, these data suggest that BVDV2 infection modulated mRNA responses and induced a suppression of proinflammatory cytokine protein responses to TLR ligation in MDMΦ with the exception of TLR7 ligation. It is likely that there are distinct differences in TLR pathways modulated following BVDV2 infection, which have implications for macrophage responses to secondary infections. PMID:27420479

  10. Toll-like receptor genetic variants are associated with Gram-negative infections in VLBW infants

    PubMed Central

    Sampath, Venkatesh; Mulrooney, Neil P.; Garland, Jeffery S.; He, Jie; Patel, Aloka L.; Cohen, Jonathan D.; Simpson, Pippa M.; Hines, Ronald N.

    2015-01-01

    OBJECTIVE To test the hypothesis that single nucleotide polymorphisms (SNPs) in Toll-like receptor (TLR) genes alter susceptibility to bacterial infections and modulate WBC counts during infections in very low birth-weight infants (birth weight <1500g, VLBW). STUDY DESIGN VLBW infants recruited in a multi-center study were genotyped for 9 functional TLR SNPs and associations between SNPs and infection rates examined. WBC counts obtained during infections were compared among infants with and without SNPs. RESULTS In our cohort (n=408), 90 infants developed bacterial infections. Presence of TLR4 (rs4986790 & 4986791) variants were associated with Gram-negative infections. Female infants heterozygous for the X-linked IRAK1 (rs1059703) SNP had less Gram-negative infections. In regression models controlling for confounders, the TLR4 (rs4986790) SNP was associated with increased Gram-negative infections. The TLR5 (rs5744105) variant was associated with elevated WBC counts during infections. CONCLUSION TLR genetic variants can contribute to increased risk of bacterial infections and altered immune responses in VLBW infants. PMID:23867959

  11. The role of Toll-like receptors in host defense against microbial infection.

    PubMed

    Krutzik, S R; Sieling, P A; Modlin, R L

    2001-02-01

    The Toll family of proteins is central to Drosophila host defense against microbial infection. Maintained throughout evolution, mammalian Toll-like receptors (TLRs) are proteins that participate in innate immunity to bacteria in at least four ways. First, TLRs participate in the recognition of molecular patterns present on microorganisms. Second, TLRs are expressed at the interface with the environment, the site of microbial invasion. Third, activation of TLRs induces expression of co-stimulatory molecules and the release of cytokines that instruct the adaptive immune response. Fourth, activation of TLRs leads to direct antimicrobial effector pathways that can result in elimination of the foreign invader. The recent investigation of TLRs in these areas has provided new insights into mechanisms of innate immunity. PMID:11154925

  12. Recent insights into the role of Toll-like receptors in viral infection

    PubMed Central

    Carty, M; Bowie, A G

    2010-01-01

    Toll-like receptors (TLRs) have a central role in innate immunity as they detect conserved pathogen-associated molecular patterns (PAMPs) on a range of microbes, including viruses, leading to innate immune activation and orchestration of the adaptive immune response. To date, a large number of viruses have been shown to trigger innate immunity via TLRs, suggesting that these receptors are likely to be important in the outcome to viral infection. This suggestion is supported by the observation that many viruses have evolved mechanisms not only to evade the innate immune system, but also to subvert it for the benefit of the virus. In this review we will discuss earlier evidence, mainly from knock-out mice studies, implicating TLRs in the innate immune response to viruses, in light of more recent clinical data demonstrating that TLRs are important for anti-viral immunity in humans. PMID:20560984

  13. Trichomonas vaginalis infection activates cells through toll-like receptor 4.

    PubMed

    Zariffard, M Reza; Harwani, Sailesh; Novak, Richard M; Graham, Parrie J; Ji, Xin; Spear, Gregory T

    2004-04-01

    While Trichomonas vaginalis infection can cause inflammation and influx of leukocytes into the female genital tract, the molecular pathways important in inducing these effects are not known. This study determined if infection with T. vaginalis activates cells through toll-like receptor 4 (TLR4). Genital tract secretions from infected women stimulated TNF-alpha production by cells with functional TLR4 (350 pg/ml) but significantly less by cells that are unresponsive to TLR4 ligands (44 pg/ml, P = 0.001). Secretions collected after clearance of infection also induced significantly lower responses by cells with functional TLR4 (136 pg/ml, P = 0.008). TNF-alpha responses were not reduced by Polymyxin B and did not correlate with beta(2)-defensin levels, indicating that stimulation of cells was not through lipopolysaccharide or beta(2)-defensin. These studies show that T. vaginalis infection results in the appearance in the genital tract of substance(s) that stimulate cells through TLR4, suggesting a mechanism for the inflammation caused by this infection. PMID:15093558

  14. Regulation of toll like receptors in intestinal epithelial cells by stress and Toxoplasma gondii infection

    PubMed Central

    Gopal, R.; Birdsell, D.; Monroy, F. P.

    2008-01-01

    SUMMARY Intestinal epithelial cells (IECs) form a barrier between invading microorganisms and the underlying host tissues. IECs express Toll-like receptors (TLRs) that recognize specific molecular signatures on microbes which activate intracellular signaling pathways leading to production of proinflammatory cytokines and chemokines. Stress hormones play an important role in modulation of proinflammatory cytokines and downregulation of immune responses. Here we demonstrated that expression levels of TLR-2, TLR-4, TLR-9 and TLR-11 were significantly increased in mouse IECs following infection with Toxoplasma gondii on day 8 post infection. In contrast, expression of TLRs was significantly decreased in infected mice subjected to cold water stress (CWS+INF). Expression of TLR-9 and TLR-11 in the mouse MODE-K cell line was significantly increased after infection. Expression of TLR-9 and TLR-11 in cells exposed to norepinephrine (NE) and parasites was significantly decreased when compared to cells exposed to parasites only. A significant increase was observed in SIGIRR, a negative regulator of TLRs in the CWS+INF group when compared to the INF group. Stress components were able to decrease expression levels of TLRs in IECs, decrease parasite load, and increase expression of a negative regulator thereby ameliorating intestinal inflammatory responses commonly observed during per oral T. gondii infection in C57BL/6 mice. PMID:19067837

  15. Signaling through Toll-like receptors triggers HIV-1 replication in latently infected mast cells.

    PubMed

    Sundstrom, J Bruce; Little, Dawn M; Villinger, Francois; Ellis, Jane E; Ansari, Aftab A

    2004-04-01

    Evidence that human progenitor mast cells are susceptible to infection with CCR5-tropic strains of HIV-1 and that circulating HIV-1-infected FcepsilonRIalpha(+) cells with a similar progenitor phenotype have been isolated from AIDS patients has led to speculation that mast cells may serve as a potential reservoir for infectious HIV-1. In this study, progenitor mast cells, developed in vitro from CD34(+) cord blood stem cells, were experimentally infected with the CCR5-tropic strain HIV-1Bal after 28 days in culture as they reached their HIV-1-susceptible progenitor stage. HIV-1 p24 Ag levels were readily detectable by day 7 postinfection (PI), peaked at 2-3 wk PI as mature (tryptase/chymase-positive) HIV-1 infection-resistant mast cells emerged, and then steadily declined to below detectable limits by 10 wk PI, at which point integrated HIV-1 proviral DNA was confirmed by PCR quantitation in ( approximately 34% of) latently infected mast cells. Stimulation by ligands for Toll-like receptor (TLR) 2, TLR4, or TLR9 significantly enhanced viral replication in a dose- and time-dependent manner in both HIV-1-infected progenitor and latently infected mature mast cells, without promoting degranulation, apoptosis, cellular proliferation, or dysregulation of TLR agonist-induced cytokine production in infected mast cells. Limiting dilution analysis of TLR activated, latently infected mature mast cells indicated that one in four was capable of establishing productive infections in A301 sentinel cells. Taken together, these results indicate that mast cells may serve both as a viral reservoir and as a model for studying mechanisms of postintegration latency in HIV infection. PMID:15034054

  16. Toll-Like Receptor 9 Signaling in Dendritic Cells Regulates Neutrophil Recruitment to Inflammatory Foci following Leishmania infantum Infection

    PubMed Central

    Sacramento, Laís; Trevelin, Silvia C.; Nascimento, Manuela S.; Lima-Jùnior, Djalma S.; Costa, Diego L.; Almeida, Roque P.; Cunha, Fernando Q.

    2015-01-01

    Leishmania infantum is a protozoan parasite that causes visceral leishmaniasis (VL). This infection triggers dendritic cell (DC) activation through the recognition of microbial products by Toll-like receptors (TLRs). Among the TLRs, TLR9 is required for DC activation by different Leishmania species. We demonstrated that TLR9 is upregulated in vitro and in vivo during infection. We show that C57BL/6 mice deficient in TLR9 expression (TLR9−/− mice) are more susceptible to infection and display higher parasite numbers in the spleen and liver. The increased susceptibility of TLR9−/− mice was due to the impaired recruitment of neutrophils to the infection foci associated with reduced levels of neutrophil chemoattractants released by DCs in the target organs. Moreover, both Th1 and Th17 cells were also committed in TLR9−/− mice. TLR9-dependent neutrophil recruitment is mediated via the MyD88 signaling pathway but is TIR domain-containing adapter-inducing interferon beta (TRIF) independent. Furthermore, L. infantum failed to activate both plasmacytoid and myeloid DCs from TLR9−/− mice, which presented reduced surface costimulatory molecule expression and chemokine release. Interestingly, neutrophil chemotaxis was affected both in vitro and in vivo when DCs were derived from TLR9−/− mice. Our results suggest that TLR9 plays a critical role in neutrophil recruitment during the protective response against L. infantum infection that could be associated with DC activation. PMID:26371124

  17. Toll-Like Receptor-4 Dependent Small Intestinal Immune Responses Following Murine Arcobacter Butzleri Infection

    PubMed Central

    Heimesaat, Markus M.; Karadas, Gül; Fischer, André; Göbel, Ulf B.; Alter, Thomas; Bereswill, Stefan; Gölz, Greta

    2015-01-01

    Sporadic cases of gastroenteritis have been attributed to Arcobacter butzleri infection, but information about the underlying immunopathological mechanisms is scarce. We have recently shown that experimental A. butzleri infection induces intestinal, extraintestinal and systemic immune responses in gnotobiotic IL-10–/– mice. The aim of the present study was to investigate the immunopathological role of Toll-like Receptor-4, the receptor for lipopolysaccharide and lipooligosaccharide of Gram-negative bacteria, during murine A. butzleri infection. To address this, gnotobiotic IL-10–/– mice lacking TLR-4 were generated by broad-spectrum antibiotic treatment and perorally infected with two different A. butzleri strains isolated from a patient (CCUG 30485) or fresh chicken meat (C1), respectively. Bacteria of either strain stably colonized the ilea of mice irrespective of their genotype at days 6 and 16 postinfection. As compared to IL-10–/– control animals, TLR-4–/– IL-10–/– mice were protected from A. butzleri-induced ileal apoptosis, from ileal influx of adaptive immune cells including T lymphocytes, regulatory T-cells and B lymphocytes, and from increased ileal IFN-γ secretion. Given that TLR-4-signaling is essential for A. butzleri-induced intestinal inflammation, we conclude that bacterial lipooligosaccharide or lipopolysaccharide compounds aggravate intestinal inflammation and may thus represent major virulence factors of Arcobacter. Future studies need to further unravel the molecular mechanisms of TLR-4-mediated A. butzleri-host interactions. PMID:26716022

  18. Role of Toll-like receptors in Helicobacter pylori infection and immunity.

    PubMed

    Smith, Sinéad M

    2014-08-15

    The gram-negative bacterium Helicobacter pylori (H. pylori) infects the stomachs of approximately half of the world's population. Although infection induces an immune response that contributes to chronic gastric inflammation, the response is not sufficient to eliminate the bacterium. H. pylori infection causes peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Disease outcome is linked to the severity of the host inflammatory response. Gastric epithelial cells represent the first line of innate immune defence against H. pylori, and respond to infection by initiating numerous cell signalling cascades, resulting in cytokine induction and the subsequent recruitment of inflammatory cells to the gastric mucosa. Pathogen recognition receptors of the Toll-like receptor (TLR) family mediate many of these cell signalling events. This review discusses recent findings on the role of various TLRs in the recognition of H. pylori in distinct cell types, describes the TLRs responsible for the recognition of individual H. pylori components and outlines the influence of innate immune activation on the subsequent development of the adaptive immune response. The mechanistic identification of host mediators of H. pylori-induced pathogenesis has the potential to reveal drug targets and opportunities for therapeutic intervention or prevention of H. pylori-associated disease by means of vaccines or immunomodulatory therapy. PMID:25133016

  19. Role of Toll-like receptors in Helicobacter pylori infection and immunity

    PubMed Central

    Smith, Sinéad M

    2014-01-01

    The gram-negative bacterium Helicobacter pylori (H. pylori) infects the stomachs of approximately half of the world’s population. Although infection induces an immune response that contributes to chronic gastric inflammation, the response is not sufficient to eliminate the bacterium. H. pylori infection causes peptic ulcers, gastric cancer and mucosa-associated lymphoid tissue lymphoma. Disease outcome is linked to the severity of the host inflammatory response. Gastric epithelial cells represent the first line of innate immune defence against H. pylori, and respond to infection by initiating numerous cell signalling cascades, resulting in cytokine induction and the subsequent recruitment of inflammatory cells to the gastric mucosa. Pathogen recognition receptors of the Toll-like receptor (TLR) family mediate many of these cell signalling events. This review discusses recent findings on the role of various TLRs in the recognition of H. pylori in distinct cell types, describes the TLRs responsible for the recognition of individual H. pylori components and outlines the influence of innate immune activation on the subsequent development of the adaptive immune response. The mechanistic identification of host mediators of H. pylori-induced pathogenesis has the potential to reveal drug targets and opportunities for therapeutic intervention or prevention of H. pylori-associated disease by means of vaccines or immunomodulatory therapy. PMID:25133016

  20. Cancer-associated toll-like receptor modulation and insinuation in infection susceptibility: association or coincidence?

    PubMed

    Khan, A A; Khan, Z; Warnakulasuriya, S

    2016-06-01

    Toll-like receptors (TLRs) are key players in maintaining protection against any invading pathogen. These molecules are microbial sensing proteins which detect pathogen-associated molecular patterns and induce the body's innate immune system to elicit a response against invading pathogens. In addition to their role in pathogen recognition and elimination, these proteins are highly important in cancer biology and also play a variety of roles in normal to cancerous transformation or its prevention. There is much published literature on the role of TLRs in pathogen recognition and elimination, but recently the number of articles relevant to the role of TLR in carcinogenesis has increased due to their importance in this area. On the one hand, they are involved in microbial elimination and, on the other hand, their modulation during cancer development has several implications. Accumulating a diverse thread of cancer-associated TLR modulation and infection susceptibility has several caveats. Some cancer-associated TLR modulation increases susceptibility to particular infections, while increased expression of certain TLR was found to help in the carcinogenic process through inducing inflammation. This article concludes that clinicians should consider TLR modulation during infection risk assessment in cancer patients. These modulations should also be considered while designing management strategies against cancer and its associated infections. PMID:26861598

  1. Toll-like receptors in prostate infection and cancer between bench and bedside

    PubMed Central

    Gambara, Guido; Cesaris, Paola; Nunzio, Cosimo; Ziparo, Elio; Tubaro, Andrea; Filippini, Antonio; Riccioli, Anna

    2013-01-01

    Toll-Like receptors (TLRs) are a family of evolutionary conserved transmembrane proteins that recognize highly conserved molecules in pathogens. TLR-expressing cells represent the first line of defence sensing pathogen invasion, triggering innate immune responses and subsequently priming antigen-specific adaptive immunity. In vitro and in vivo studies on experimental cancer models have shown both anti- and pro-tumoural activity of different TLRs in prostate cancer, indicating these receptors as potential targets for cancer therapy. In this review, we highlight the intriguing duplicity of TLR stimulation by pathogens: their protective role in cases of acute infections, and conversely their negative role in favouring hyperplasia and/or cancer onset, in cases of chronic infections. This review focuses on the role of TLRs in the pathophysiology of prostate infection and cancer by exploring the biological bases of the strict relation between TLRs and prostate cancer. In particular, we highlight the debated question of how reliable mutations or deregulated expression of TLRs are as novel diagnostic or prognostic tools for prostate cancer. So far, the anticancer activity of numerous TLR ligands has been evaluated in clinical trials only in organs other than the prostate. Here we review recent clinical trials based on the most promising TLR agonists in oncology, envisaging a potential application also in prostate cancer therapy. PMID:23551576

  2. Characterization of Toll-like receptor gene expression in goldfish (Carassius auratus) during Dactylogyrus intermedius infection.

    PubMed

    Tu, Xiao; Liu, Lei; Qi, Xiaozhou; Chen, Weichao; Wang, Gaoxue; Ling, Fei

    2016-10-01

    Toll-like receptors (TLRs), the first and best understood innate immune receptors, play a notable role in the innate immune system by sensing pathogenic agents and initiating appropriate immune responses. However, studies about the roles of fish TLRs in response to the infection of the ectoparasitic monogenean Dactylogyrus intermedius have been surprisingly vacant. In the present study, cDNA fragments of five members of TLRs family in goldfish (Carassius auratus) were cloned and the expression patterns of nine TLRs in five tissues at different time points during D. intermedius infection were subsequently investigated. We found that the expressions of TLR4, TLR5, TLR20 and TLR22 were significantly elevated after infection at some time points, of which the transcription of TLR5 was progressively increased nearly in all tissues, whereas the mRNA levels of other TLRs (TLR2, 3, 7, 9 and 21) were down-regulated or showed no significant change compared with the control at most time points. Additionally, this paper was also conducted to explore the expression of above TLRs after re-infected with D. intermedius. The results showed a significant upregulation of TLR4, TLR5 and TLR22 in all tested tissues at these two time points, especially the levels of TLR4 and TLR22 expression, were even higher comparing with the first infection. Besides, tissue-specific expression analysis revealed that spleen featured the highest expressions of almost all the TLR-encoding genes among detected tissues. The informations obtained here could be helpful towards understanding the functions of TLRs in response to parasitic infection in goldfish and provide new insights for the development of preventive and therapeutic approaches against D. intermedius infection. PMID:27238769

  3. Use of Toll-Like Receptor 3 Agonists Against Respiratory Viral Infections

    PubMed Central

    Christopher, ME; Wong, JP

    2011-01-01

    Respiratory RNA viruses are constantly evolving, thus requiring development of additional prophylactic and therapeutic strategies. Harnessing the innate immune system to non-specifically respond to viral infection has the advantage of being able to circumvent viral mutations that render the virus resistant to a particular therapeutic agent. Viruses are recognized by various cellular receptors, including Toll-like receptor (TLR) 3 which recognizes double-stranded (ds)RNA produced during the viral replication cycle. TLR3 agonists include synthetic dsRNA such as poly (IC), poly (ICLC) and poly (AU). These agents have been evaluated and found to be effective against a number of viral agents. One major limitation has been the toxicity associated with administration of these drugs. Significant time and effort have been spent to develop alternatives/modifications that will minimize these adverse effects. This review will focus on the TLR3 agonist, poly (IC)/(ICLC) with respect to its use in treatment/prevention of respiratory viral infections.

  4. Role of Toll-like receptors in systemic Candida albicans infections.

    PubMed

    Luisa Gil, Maria; Murciano, Celia; Yáñez, Alberto; Gozalbo, Daniel

    2016-01-01

    Toll-like receptors (TLRs) constitute a family of pattern-recognition receptors (PRRs) that recognize molecular signatures of microbial pathogens and function as sensors for infection. Recognition of Candida albicans by TLRs on mature immune cells, such as phagocytic cells, activates intracellular signalling pathways that trigger production of proinflammatory cytokines which are critical for innate host defence and orchestrate the adaptive response. TLR2, and TLR4 in a minor extent, recognize cell wall-associated ligands; endosomal TLR9 and TLR7 recognize DNA and RNA respectively. Interaction of C. albicans with TLRs is a complex process, as TLRs may collaborate with other PRRs and expression of surface-associated fungal ligands depends on the strain and the morphotype (yeasts or hyphae), thus defining the final induced adaptive response (Th1/Th2/Th17). TLRs are also expressed on hematopoietic stem and progenitor cells (HSPCs) where they may play a role in modulating hematopoiesis; engagement of TLR2 induces, upon recognition of C. albicans, the differentiation of HSPCs towards specific subsets of mature myeloid cells. This has opened a new perspective for anti-Candida immunointervention. PMID:26709773

  5. Toll-Like Receptor 6 Plays an Important Role in Host Innate Resistance to Brucella abortus Infection in Mice

    PubMed Central

    de Almeida, Leonardo A.; Macedo, Gilson C.; Marinho, Fábio A. V.; Gomes, Marco T. R.; Corsetti, Patrícia P.; Silva, Aristóbolo M.; Cassataro, Juliana; Giambartolomei, Guillermo H.

    2013-01-01

    Brucella abortus is recognized by several Toll-like receptor (TLR)-associated pathways triggering proinflammatory responses that affect both the nature and intensity of the immune response. Previously, we demonstrated that B. abortus-mediated dendritic cell (DC) maturation and control of infection are dependent on the adaptor molecule MyD88. However, the involvement of all TLRs in response to B. abortus infection is not completely understood. Therefore, we decided to evaluate the requirement for TLR6 in host resistance to B. abortus. Here, we demonstrated that TLR6 is an important component for triggering an innate immune response against B. abortus. An in vitro luciferase assay indicated that TLR6 cooperates with TLR2 to sense Brucella and further activates NF-κB signaling. However, in vivo analysis showed that TLR6, not TLR2, is required for the efficient control of B. abortus infection. Additionally, B. abortus-infected dendritic cells require TLR6 to induce tumor necrosis factor alpha (TNF-α) and interleukin-12 (IL-12). Furthermore, our findings demonstrated that the mitogen-activated protein kinase (MAPK) signaling pathway is impaired in TLR2, TLR6, and TLR2/6 knockout (KO) DCs when infected with B. abortus, which may account for the lower proinflammatory cytokine production observed in TLR6 KO mouse dendritic cells. In summary, the results presented here indicate that TLR6 is required to trigger innate immune responses against B. abortus in vivo and is required for the full activation of DCs to induce robust proinflammatory cytokine production. PMID:23460520

  6. Toll-like receptor 2 mediates high-fat diet-induced impairment of vasodilator actions of insulin

    PubMed Central

    Jang, Hyun-Ju; Kim, Hae-Suk; Hwang, Daniel H.; Quon, Michael J.

    2013-01-01

    Obesity is characterized by a chronic proinflammatory state that leads to endothelial dysfunction. Saturated fatty acids (SFA) stimulate Toll-like receptors (TLR) that promote metabolic insulin resistance. However, it is not known whether TLR2 mediates impairment of vascular actions of insulin in response to high-fat diet (HFD) to cause endothelial dysfunction. siRNA knockdown of TLR2 in primary endothelial cells opposed palmitate-stimulated expression of proinflammatory cytokines and splicing of X box protein 1 (XBP-1). Inhibition of unfolding protein response (UPR) reduced SFA-stimulated expression of TNFα. Thus, SFA stimulates UPR and proinflammatory response through activation of TLR2 in endothelial cells. Knockdown of TLR2 also opposed impairment of insulin-stimulated phosphorylation of eNOS and subsequent production of NO. Importantly, insulin-stimulated vasorelaxation of mesenteric arteries from TLR2 knockout mice was preserved even on HFD (in contrast with results from arteries examined in wild-type mice on HFD). We conclude that TLR2 in vascular endothelium mediates HFD-stimulated proinflammatory responses and UPR that accompany impairment of vasodilator actions of insulin, leading to endothelial dysfunction. These results are relevant to understanding the pathophysiology of the cardiovascular complications of diabetes and obesity. PMID:23531618

  7. Toll-like receptors.

    PubMed

    Lien, Egil; Ingalls, Robin R

    2002-01-01

    The ability of a host to sense invasion by pathogenic organisms and to respond appropriately to control infection is paramount to survival. In the case of sepsis and septic shock, however, an exaggerated systemic response may, in fact, contribute to the morbidity and mortality associated with overwhelming infections. The innate immune system has evolved as the first line of defense against invading microorganisms. The Toll-like receptors (TLRs) are a part of this innate immune defense, recognizing conserved patterns on microorganisms. These TLRs and their signaling pathways are represented in such diverse creatures as mammals, fruit flies, and plants. Ten members of the TLR family have been identified in humans, and several of them appear to recognize specific microbial products, including lipopolysaccharide, bacterial lipoproteins, peptidoglycan, and bacterial DNA. Signals initiated by the interaction of TLRs with specific microbial patterns direct the subsequent inflammatory response. Thus, TLR signaling represents a key component of the innate immune response to microbial infection. PMID:11782555

  8. Modulation of Toll-Like Receptor Activity by Leukocyte Ig-Like Receptors and Their Effects during Bacterial Infection

    PubMed Central

    Pilsbury, Louise E.; Allen, Rachel L.; Vordermeier, Martin

    2010-01-01

    Toll-like receptors (TLRs) are a potent trigger for inflammatory immune responses. Without tight regulation their activation could lead to pathology, so it is imperative to extend our understanding of the regulatory mechanisms that govern TLR expression and function. One family of immunoregulatory proteins which can provide a balancing effect on TLR activity are the Leukocyte Ig-like receptors (LILRs), which act as innate immune receptors for self-proteins. Here we describe the LILR family, their inhibitory effect on TLR activity in cells of the monocytic lineage, their signalling pathway, and their antimicrobial effects during bacterial infection. Agents have already been identified which enhances or inhibits LILR activity raising the future possibility that modulation of LILR function could be used as a means to modulate TLR activity. PMID:20634939

  9. Toll-Like Receptor Stimulation Induces Nondefensin Protein Expression and Reverses Antibiotic-Induced Gut Defense Impairment

    PubMed Central

    Wu, Ying-Ying; Hsu, Ching-Mei; Chen, Pei-Hsuan; Fung, Chang-Phone

    2014-01-01

    Prior antibiotic exposure is associated with increased mortality in Gram-negative bacteria-induced sepsis. However, how antibiotic-mediated changes of commensal bacteria promote the spread of enteric pathogenic bacteria in patients remains unclear. In this study, the effects of systemic antibiotic treatment with or without Toll-like receptor (TLR) stimulation on bacterium-killing activity, antibacterial protein expression in the intestinal mucosa, and bacterial translocation were examined in mice receiving antibiotics with or without oral supplementation of dead Escherichia coli or Staphylococcus aureus. We developed a systemic ampicillin, vancomycin, and metronidazole treatment protocol to simulate the clinical use of antibiotics. Antibiotic treatment decreased the total number of bacteria, including aerobic bacteria belonging to the family Enterobacteriaceae and the genus Enterococcus as well as organisms of the anaerobic genera Lactococcus and Bifidobacterium in the intestinal mucosa and lumen. Antibiotic treatment significantly decreased the bacterium-killing activity of the intestinal mucosa and the expression of non-defensin-family proteins, such as RegIIIβ, RegIIIγ, C-reactive protein-ductin, and RELMβ, but not the defensin-family proteins, and increased Klebsiella pneumoniae translocation. TLR stimulation after antibiotic treatment increased NF-κB DNA binding activity, nondefensin protein expression, and bacterium-killing activity in the intestinal mucosa and decreased K. pneumoniae translocation. Moreover, germfree mice showed a significant decrease in nondefensin proteins as well as intestinal defense against pathogen translocation. Since TLR stimulation induced NF-κB DNA binding activity, TLR4 expression, and mucosal bacterium-killing activity in germfree mice, we conclude that the commensal microflora is critical in maintaining intestinal nondefensin protein expression and the intestinal barrier. In turn, we suggest that TLR stimulation induces

  10. Effect of porcine reproductive and respiratory syndrome virus infection of porcine alveolar macrophages on Toll-like receptors elicitation of type I interferon responses

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of virus replication initially depends on rapid activation of the innate immune responses. Toll-like receptor (TLR) ligands are potent inducers of innate immunity against viral infections. Porcine reproductive and respiratory syndrome virus (PRRSV) initiates infection in pulmonary alveolar m...

  11. Toll-Like Receptor-4 Dependent Intestinal Gene Expression During Arcobacter Butzleri Infection of Gnotobiotic Il-10 Deficient Mice

    PubMed Central

    Gölz1, Greta; Alter, Thomas; Bereswill, Stefan; Heimesaat, Markus M.

    2016-01-01

    We have previously shown that Arcobacter butzleri infection induces Toll-like receptor (TLR) -4 dependent immune responses in perorally infected gnotobiotic IL-10–/– mice. Here, we analyzed TLR-4-dependent expression of genes encoding inflammatory mediators and matrix-degrading gelatinases MMP-2 and -9 in the small and large intestines of gnotobiotic TLR-4-deficient IL-10–/– mice that were perorally infected with A. butzleri strains CCUG 30485 or C1, of human and chicken origin, respectively. At day 6 following A. butzleri infection, colonic mucin-2 mRNA, as integral part of the intestinal mucus layer, was downregulated in the colon, but not ileum, of IL-10–/– but not TLR-4–/– IL-10–/– mice. CCUG 30485 strain-infected TLR-4-deficient IL-10–/– mice displayed less distinctly upregulated IFN-γ, IL-17A, and IL-1β mRNA levels in ileum and colon, which was also true for colonic IL-22. These changes were accompanied by upregulated colonic MMP-2 and ileal MMP-9 mRNA exclusively in IL-10–/– mice. In conclusion, TLR-4 is essentially involved in A. butzleri mediated modulation of gene expression in the intestines of gnotobiotic IL-10–/– mice. PMID:27141316

  12. Acanthamoeba infection in lungs of mice expressed by toll-like receptors (TLR2 and TLR4).

    PubMed

    Derda, Monika; Wojtkowiak-Giera, Agnieszka; Kolasa-Wołosiuk, Agnieszka; Kosik-Bogacka, Danuta; Hadaś, Edward; Jagodziński, Paweł P; Wandurska-Nowak, Elżbieta

    2016-06-01

    Toll-like receptors (TLRs) play a key role in the innate immune responses to a variety of pathogens including parasites. TLRs are among the most highly conserved in the evolution of the receptor family, localized mainly on cells of the immune system and on other cells such as lung cells. The aim of this study was to determine for the first time the expression of TLR2 and TLR4 in the lung of Acanthamoeba spp. infected mice using quantitative real-time polymerase chain reaction (Q-PCR) and immunohistochemical (IHC) staining. The Acanthamoeba spp. were isolated from a patient with Acanthamoeba keratitis (AK) (strain Ac 55) and from environmental samples of water from Malta Lake (Poznań, Poland - strain Ac 43). We observed a significantly increased level of expression of TLR2 as well as TLR4 mRNA from 2 to 30 days post Acanthamoeba infection (dpi) in the lungs of mice infected with Ac55 (KP120880) and Ac43 (KP120879) strains. According to our observations, increased TLR2 and TLR4 expression in the pneumocytes, interstitial cells and epithelial cells of the bronchial tree may suggest an important role of these receptors in protective immunity against Acanthamoeba infection in the lung. Moreover, increased levels of TLR2 and TLR4 mRNA expression in infected Acanthamoeba mice may suggest the involvement of these TLRs in the recognition of this amoeba pathogen-associated molecular pattern (PAMP). PMID:26940205

  13. Polymorphism in the promoter region of the Toll-like receptor 9 gene and cervical human papillomavirus infection

    PubMed Central

    Oliveira, Lucas Boeno; Louvanto, Karolina; Ramanakumar, Agnihotram V.; Franco, Eduardo L.

    2013-01-01

    Polymorphism in the Toll-like receptor (TLR) 9 gene has been shown to have a significant role in some diseases; however, little is known about its possible role in the natural history of human papillomavirus (HPV) infections. We investigated the association between a single-nucleotide polymorphism (SNP) (rs5743836) in the promoter region of TLR9 (T1237C) and type-specific HPV infections. Specimens were derived from a cohort of 2462 women enrolled in the Ludwig–McGill Cohort Study. We randomly selected 500 women who had a cervical HPV infection detected at least once during the study as cases. We defined two control groups: (i) a random sample of 300 women who always tested HPV negative, and (ii) a sample of 234 women who were always HPV negative but had a minimum of ten visits during the study. TLR9 genotyping was performed using bidirectional PCR amplification of specific alleles. Irrespective of group, the WT homozygous TLR9 genotype (TT) was the most common form, followed by the heterozygous (TC) and the mutant homozygous (CC) forms. There were no consistent associations between polymorphism and infection risk, either overall or by type or species. Likewise, there were no consistently significant associations between polymorphism and HPV clearance or persistence. We concluded that this polymorphism in the promoter region of TLR9 gene does not seem to have a mediating role in the natural history of the HPV infection. PMID:23677790

  14. Immunostimulatory effect of salmon prolactin on expression of Toll-like receptors in Oncorhynchus mykiss infected with Piscirickettsia salmonis.

    PubMed

    Peña, B; Isla, A; Haussmann, D; Figueroa, J

    2016-04-01

    In aquaculture, antibiotics are the traditional treatment used against bacterial infections. However, their use has increasingly come into question given their effects on fish and, possibly, on human health. Consequently, there is interest in developing alternative treatments aimed at stimulating the innate immune response of fish, which is the first line of defense against pathogens. In relation to this, the Toll-like receptors (TLR) aid in the selective identification of pathogens. The present study evaluated immunostimulatory activity of prolactin (PRL) hormone on expression levels of TLR1, 9, and 22, MyD88, and IL-1β during in vitro infection with the fish pathogen Piscirickettsia salmonis, in primary cultures of Oncorhynchus mykiss head kidney cells. Results indicated that PRL increased expression of TLRs and MyD88 during the first hours of bacterial infection, while a constant increase in expression was found for IL-1β. These findings suggest that PRL indirectly modulates expression of TLRs by activating expression of suppressors of cytokine signaling, thereby regulating immune response over long periods of time during bacterial infection. PMID:26537800

  15. Expression profiles of toll-like receptors in anterior kidney of channel catfish Ictalurus punctatus (Rafinesque), acutely infected by Edwardsiella ictaluri

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using quantitative PCR (QPCR), the relative transcriptional levels of five toll-like receptors (TLR2, TLR3, TLR5, TLR20a, and TLR21) were studied in the channel catfish, Ictalurus punctatus (Rafinesque), under normal and acutely infected conditions (1, 2, 4, 6, 12, 24, 36, and 48 h post injection (h...

  16. Toll-like receptor 2 ligand, lipoteichoic acid is inhibitory against infectious laryngotracheitis virus infection in vitro and in vivo.

    PubMed

    Haddadi, S; Thapa, S; Kameka, A M; Hui, J; Czub, M; Nagy, E; Muench, G; Abdul-Careem, M F

    2015-01-01

    Lipoteichoic acid (LTA) is one of the pathogen associated molecular patterns (PAMPs) that activates toll-like receptor (TLR)2-cluster of differentiation (CD)14 signalling pathway. This recognition elicits antiviral responses that have been recorded against viruses of mammals although such responses have not been characterized adequately against avian viruses. In this investigation, we characterized the LTA induced antiviral responses against infectious laryntotracheitis virus (ILTV) infection in vitro and in vivo. We found that LTA is capable of up regulating mRNA expression of innate proteins in macrophages such as MyD88, iNOS and IL-1β and reduces the ILTV plaques in vitro. Similarly, we found that LTA treatment of embryonic day 18 (ED18) eggs can lead to the antiviral response against pre-hatch ILTV infection in vivo and is associated with expansion of macrophage populations and expression of IL-1β and MyD88 in the lung. The data highlight that LTA can be a potential innate immune stimulant that can be used against ILTV infection in chickens. PMID:25195716

  17. Toll-Like Receptor 4 Agonistic Antibody Promotes Host Defense against Chronic Pseudomonas aeruginosa Lung Infection in Mice.

    PubMed

    Nakamura, Shigeki; Iwanaga, Naoki; Seki, Masafumi; Fukudome, Kenji; Oshima, Kazuhiro; Miyazaki, Taiga; Izumikawa, Koichi; Yanagihara, Katsunori; Miyazaki, Yoshitsugu; Mukae, Hiroshi; Kohno, Shigeru

    2016-07-01

    Chronic lower respiratory tract infection with Pseudomonas aeruginosa is difficult to treat due to enhanced antibiotic resistance and decreased efficacy of drug delivery to destroyed lung tissue. To determine the potential for restorative immunomodulation therapies, we evaluated the effect of Toll-like receptor 4 (TLR4) stimulation on the host immune response to Pseudomonas infection in mice. We implanted sterile plastic tubes precoated with P. aeruginosa in the bronchi of mice, administered the TLR4/MD2 agonistic monoclonal antibody UT12 intraperitoneally every week, and subsequently analyzed the numbers of viable bacteria and inflammatory cells and the levels of cytokines. We also performed flow cytometry-based phagocytosis and opsonophagocytic killing assays in vitro using UT12-treated murine peritoneal neutrophils. UT12-treated mice showed significantly enhanced bacterial clearance, increased numbers of Ly6G(+) neutrophils, and increased concentrations of macrophage inflammatory protein 2 (MIP-2) in the lungs (P < 0.05). Depletion of CD4(+) T cells eliminated the ability of the UT12 treatment to improve bacterial clearance and promote neutrophil recruitment and MIP-2 production. Additionally, UT12-pretreated peritoneal neutrophils exhibited increased opsonophagocytic killing activity via activation of the serine protease pathway, specifically neutrophil elastase activity, in a TLR4-dependent manner. These data indicated that UT12 administration significantly augmented the innate immune response against chronic bacterial infection, in part by promoting neutrophil recruitment and bactericidal function. PMID:27091927

  18. Toll-like receptor gene variants and bacterial vaginosis among HIV-1 infected and uninfected African women.

    PubMed

    Mackelprang, R D; Scoville, C W; Cohen, C R; Ondondo, R O; Bigham, A W; Celum, C; Campbell, M S; Essex, M; Wald, A; Kiarie, J; Ronald, A; Gray, G; Lingappa, J R

    2015-01-01

    Bacterial vaginosis (BV) is a common vaginal syndrome associated with altered microflora that increases the risk of preterm delivery and acquisition of sexually transmitted diseases. The cause of BV is unknown although toll-like receptors (TLRs), that are central to innate immune responses, may be important. We evaluated associations between TLR SNPs and BV among HIV-1 infected and uninfected African women. Logistic regression was used to assess associations between SNPs (N=99) in TLRs 2-4, 7-9 and BV (as classified by Nugent's criteria). Among HIV-1 uninfected women, TLR7 rs5743737 and TLR7 rs1634323 were associated with a decreased risk of BV, whereas TLR7 rs179012 was associated with an increased risk. TLR2 SNP rs3804099 was associated with a decreased risk of BV among HIV-1 infected women. Our findings indicate that there may be differences in TLR association with BV among HIV-1 infected and HIV-1 uninfected women. PMID:25928881

  19. Synthetic Toll-like receptor 7 ligand inhibits porcine reproductive and respiratory syndrome virus infection in primary porcine alveolar macrophages.

    PubMed

    Du, Yongkun; Du, Taofeng; Shi, Yunpeng; Zhang, Angke; Zhang, Chong; Diao, Yuwen; Jin, Guangyi; Zhou, En-Min

    2016-07-01

    Porcine reproductive and respiratory syndrome virus (PRRSV), a common viral pathogen, causes huge annual economic losses to the swine industry worldwide. After triggering by specific ligands, the Toll-like receptor 7 (TLR7), a type of pattern-recognition receptor (PRR), induces antiviral cytokines production. Previously, we synthesized an adenine analog, designated SZU101, a TLR7-specific ligand. In this study, we assessed the inhibitory effect of SZU101 on PRRSV infection in vitro. SZU101 significantly suppressed PRRSV infection in primary porcine alveolar macrophages (PAMs) in a dose-dependent manner. Moreover, SZU101-induced inhibition involved NF-κB pathway activation in PAMs to initiate expression of TLR7-mediated cytokines and induce expression of downstream signaling IFN-stimulated genes (ISGs). Chloroquine, a TLR7 inhibitor, and BAY 11-7082, an NF-κB inhibitor, reversed both the SZU101-induced antiviral effect and induction of cytokine genes and ISGs expression. Therefore, SZU101 antiviral effects depend at least in part on TLR7-NF-κB signaling pathway. Additionally, administration of SZU101 enhanced the humoral and cell-mediated immune responses against PRRSV antigens in mice. Given these results, SZU101 holds promise as an antiviral agent and a vaccine adjuvant to prevent PRRSV infection in pigs. PMID:27079946

  20. The role of MAPK in CD4{sup +} T cells toll-like receptor 9-mediated signaling following HHV-6 infection

    SciTech Connect

    Chi, Jing; Wang, Fang; Li, Lingyun; Feng, Dongju; Qin, Jian; Xie, Fangyi; Zhou, Feng; Chen, Yun; Wang, Jinfeng; Yao, Kun

    2012-01-05

    Human herpesvirus-6 (HHV-6) is an important immunosuppressive and immunomodulatory virus that primarily infects immune cells (mainly CD4{sup +} T cells) and strongly suppresses the proliferation of infected cells. Toll-like receptors are pattern-recognition receptors essential for the development of an appropriate innate immune defense against infection. To understand the role of CD4{sup +} T cells in the innate response to HHV-6 infection and the involvement of TLRs, we used an in vitro infection model and observed that the infection of CD4{sup +} T cells resulted in the activation of JNK/SAPK via up-regulation of toll-like receptor 9 (TLR9). Associated with JNK activation, annexin V-PI staining indicated that HHV-6A was a strong inducer of apoptosis. Apoptotic response associated cytokines, IL-6 and TNF-{alpha} also induced by HHV-6A infection.

  1. Toll-like receptor 2 of tongue sole Cynoglossus semilaevis: Signaling pathway and involvement in bacterial infection.

    PubMed

    Li, Xue-peng; Sun, Li

    2016-04-01

    Toll-like receptor (TLR) 2 is a member of the TLR family that plays a pivotal role in innate immunity. In mammals, TLR2 is known to recognize specific microbial structures and trigger MyD88-dependent signaling to induce various cytokine responses. In this study, we examined the expression and function of the tongue sole Cynoglossus semilaevis TLR2, CsTLR2. CsTLR2 is composed of 898 amino acid residues and shares 25.6%-27.3% overall sequence identities with known teleost TLR2. CsTLR2 is a transmembrane protein with a toll/interleukin-1 receptor domain and eight leucine-rich repeats. Expression of CsTLR2 occurred in multiple tissues and was upregulated during bacterial infection. Stimulation of the CsTLR2 pathway led to enhanced expression of MyD88-dependent signaling molecules. Recombinant CsTLR2 (rCsTLR2) corresponding to the extracellular region was able to bind to a wide range of bacteria. Under both in vitro and in vivo conditions, rCsTLR2 significantly reduced bacterial infection. These observations add new insights into the signaling and function of teleost TLR2. PMID:26947353

  2. Requirement of UNC93B1 reveals a critical role for Toll-Like Receptor 7 in host resistance to primary infection with Trypanosoma cruzi1,2

    PubMed Central

    Caetano, Braulia C.; Carmo, Bianca B.; Melo, Mariane B.; Cerny, Anna; dos Santos, Sara L.; Bartholomeu, Daniella C.; Golenbock, Douglas T.; Gazzinelli, Ricardo T.

    2011-01-01

    UNC93B1 associates with Toll-Like Receptor (TLR) 3, 7 and 9, mediating their translocation from the endoplasmic reticulum to the endolysosome, thus allowing proper activation by microbial nucleic acids. We found that the triple deficient ‘3d’ mice, which lack functional UNC93B1 as well as functional endossomal TLRs, are highly susceptible to infection with Trypanosoma cruzi. The enhanced parasitemia and mortality in 3d animals were associated with impaired pro-inflammatory response, including reduced levels of IL-12p40 and IFN-γ. Importantly, the phenotype of 3d mice was intermediary between MyD88−/− (highly susceptible) and TLR9−/− (less susceptible), indicating the involvement of an additional UN93B1-dependent-TLR(s) on host resistance to T. cruzi. Hence, our experiments also revealed that TLR7 is a critical innate immune receptor involved in recognition of parasite RNA, induction of IL-12p40 by dendritic cells, and consequent IFN-γ by T lymphocytes. Furthermore, we show that upon T. cruzi infection triple TLR3/7/9−/− mice had similar phenotype than 3d mice. These data imply that the nucleic acid-sensing TLRs are critical determinants of host resistance to primary infection with T. cruzi. PMID:21753151

  3. Unexpected Roles for Toll-Like Receptor 4 and TRIF in Intraocular Infection with Gram-Positive Bacteria

    PubMed Central

    Parkunan, Salai Madhumathi; Randall, C. Blake; Coburn, Phillip S.; Astley, Roger A.; Staats, Rachel L.

    2015-01-01

    Inflammation caused by infection with Gram-positive bacteria is typically initiated by interactions with Toll-like receptor 2 (TLR2). Endophthalmitis, an infection and inflammation of the posterior segment of the eye, can lead to vision loss when initiated by a virulent microbial pathogen. Endophthalmitis caused by Bacillus cereus develops as acute inflammation with infiltrating neutrophils, and vision loss is potentially catastrophic. Residual inflammation observed during B. cereus endophthalmitis in TLR2−/− mice led us to investigate additional innate pathways that may trigger intraocular inflammation. We first hypothesized that intraocular inflammation during B. cereus endophthalmitis would be controlled by MyD88- and TRIF-mediated signaling, since MyD88 and TRIF are the major adaptor molecules for all bacterial TLRs. In MyD88−/− and TRIF−/− mice, we observed significantly less intraocular inflammation than in eyes from infected C57BL/6J mice, suggesting an important role for these TLR adaptors in B. cereus endophthalmitis. These results led to a second hypothesis, that TLR4, the only TLR that signals through both MyD88 and TRIF signaling pathways, contributed to inflammation during B. cereus endophthalmitis. Surprisingly, B. cereus-infected TLR4−/− eyes also had significantly less intraocular inflammation than infected C57BL/6J eyes, indicating an important role for TLR4 in B. cereus endophthalmitis. Taken together, our results suggest that TLR4, TRIF, and MyD88 are important components of the intraocular inflammatory response observed in experimental B. cereus endophthalmitis, identifying a novel innate immune interaction for B. cereus and for this disease. PMID:26195555

  4. Host Avian Beta-Defensin and Toll-Like Receptor Responses of Pigeons following Infection with Pigeon Paramyxovirus Type 1

    PubMed Central

    Li, Yanyan; Xu, Qianqian; Zhang, Tingting; Gao, Mengying; Wang, Qiuling; Han, Zongxi; Shao, Yuhao

    2015-01-01

    The high morbidity and mortality in pigeons caused by pigeon paramyxovirus type 1 (PPMV-1) highlights the need for new insights into the host immune response and novel treatment approaches. Host defense peptides (HDPs) are key components of the innate immune system. In this study, three novel avian β-defensins (AvBDs 2, 7, and 10) were characterized in pigeons and shown to possess direct antiviral activity against PPMV-1 in vitro. In addition, we evaluated the mRNA expression of these AvBDs and other immune-related genes in tissues of 2-month-old infected pigeons at 3 and 7 days postinfection. We observed that the expression of AvBD2 in the cecal tonsil, lungs, and proventriculus, as well as the expression of AvBD10 in the spleen, lungs, proventriculus, and kidneys, was upregulated in infected pigeons. Similarly, the expression of both Toll-like receptor 3 (TLR3) and TLR7 was increased in the spleen, trachea, and proventriculus, while TLR15 expression was increased only in the lungs of infected pigeons. In addition, inducible nitric oxide synthase (iNOS) expression was upregulated in the spleen, the bursa of Fabricius, the trachea, and the proventriculus of infected pigeons. Furthermore, we observed a high correlation between the expression of AvBD2 and the expression of either TLR7 or TLR15, as well as between AvBD10 expression and either TLR3 or TLR7 expression in respective tissues. The results suggest that PPMV-1 infection can induce innate host responses characterized by the activation of TLRs, particularly TLR3 and TLR7, AvBDs (2 and 10), and iNOS in pigeons. PMID:26162868

  5. AP1S3 mutations are associated with pustular psoriasis and impaired Toll-like receptor 3 trafficking.

    PubMed

    Setta-Kaffetzi, Niovi; Simpson, Michael A; Navarini, Alexander A; Patel, Varsha M; Lu, Hui-Chun; Allen, Michael H; Duckworth, Michael; Bachelez, Hervé; Burden, A David; Choon, Siew-Eng; Griffiths, Christopher E M; Kirby, Brian; Kolios, Antonios; Seyger, Marieke M B; Prins, Christa; Smahi, Asma; Trembath, Richard C; Fraternali, Franca; Smith, Catherine H; Barker, Jonathan N; Capon, Francesca

    2014-05-01

    Adaptor protein complex 1 (AP-1) is an evolutionary conserved heterotetramer that promotes vesicular trafficking between the trans-Golgi network and the endosomes. The knockout of most murine AP-1 complex subunits is embryonically lethal, so the identification of human disease-associated alleles has the unique potential to deliver insights into gene function. Here, we report two founder mutations (c.11T>G [p.Phe4Cys] and c.97C>T [p.Arg33Trp]) in AP1S3, the gene encoding AP-1 complex subunit σ1C, in 15 unrelated individuals with a severe autoinflammatory skin disorder known as pustular psoriasis. Because the variants are predicted to destabilize the 3D structure of the AP-1 complex, we generated AP1S3-knockdown cell lines to investigate the consequences of AP-1 deficiency in skin keratinocytes. We found that AP1S3 silencing disrupted the endosomal translocation of the innate pattern-recognition receptor TLR-3 (Toll-like receptor 3) and resulted in a marked inhibition of downstream signaling. These findings identify pustular psoriasis as an autoinflammatory phenotype caused by defects in vesicular trafficking and demonstrate a requirement of AP-1 for Toll-like receptor homeostasis. PMID:24791904

  6. Viral and host factors induce macrophage activation and loss of Toll Like Receptor tolerance in chronic HCV infection

    PubMed Central

    Dolganiuc, Angela; Norkina, Oxana; Kodys, Karen; Catalano, Donna; Bakis, Gennadiy; Marshall, Christopher; Mandrekar, Pranoti; Szabo, Gyongyi

    2007-01-01

    Background&Aims Persistent inflammation contributes to progression of liver damage in chronic HCV (cHCV) infection. Repeated exposure to Toll like receptor (TLR) ligands results in tolerance, a protective mechanism aimed at limiting inflammation. Methods Monocytes/macrophages were repeatedly stimulated via pro-inflammatory cytokine-inducing TLRs and evaluated for activation markers. Results Unlike monocytes (Mo) of controls or patients with non-alcoholic steatohepatitis, the Mo of cHCV patients were hyper-responsive and failed to show homo- or hetero-tolerance to TLR ligands, manifested by elevated TNFα production. Serum levels of IFNγ, endotoxin (TLR4 ligand) and HCV core protein (TLR2 ligand) were elevated in cHCV patients suggesting potential mechanisms for in vivo monocyte pre-activation. Treatment of normal monocytes with IFNγ resulted in loss of tolerance to LPS or HCV core protein. Further, we found increased levels of MyD88-IRAK1 complexes and NFκB activity both in monocytes of cHCV patients and in normal monocytes that lost TLR tolerance after IFNγ+LPS pretreatment. In vitro differentiation of TLR tolerant cHCV monocytes into macrophages restored their capacity to exhibit TLR tolerance to LPS and HCV core protein and this could be reversed by administration of IFNγ. cHCV patients exhibited increased TNFα in the circulation and in the liver. In cHCV livers we found Kupffer cell/macrophage activation indicated by increased CD163 and CD33 expression. Conclusions We identified that host-derived factors (IFNγ and endotoxin) and viral factors (HCV core protein) act in tandem to induce and maintain monocyte/macrophage activation, thus favoring persistent inflammation in patients with cHCV infection. PMID:17916356

  7. Role for Toll-like receptor 2 in the immune response to Streptococcus pneumoniae infection in mouse otitis media.

    PubMed

    Han, Fengchan; Yu, Heping; Tian, Cong; Li, Shengli; Jacobs, Michael R; Benedict-Alderfer, Cindy; Zheng, Qing Y

    2009-07-01

    Streptococcus pneumoniae is the most common pathogen associated with otitis media. To examine the role of Toll-like receptor 2 (TLR2) in host defense against Streptococcus pneumoniae infection in the middle ear, wild-type (WT; C57BL/6) and TLR2-deficient (TLR2(-/-)) mice were inoculated with Streptococcus pneumoniae (1 x 10(6) CFU) through the tympanic membrane. Nineteen of 37 TLR2(-/-) mice showed bacteremia and died within 3 days after the challenge, compared to only 4 of 32 WT mice that died. Of those that survived, more severe hearing loss in the TLR2(-/-) mice than in the WT mice was indicated by an elevation in auditory-evoked brain stem response thresholds at 3 or 7 days postinoculation. The histological pathology was characterized by effusion and tissue damage in the middle ear, and in the TLR2(-/-) mice, the outcome of infection became more severe at 7 days. At both 3 and 7 days postchallenge, the TLR2(-/-) mice had higher blood bacterial titers than the WT mice (P < 0.05), and typical bacteria were identified in the effusion from both ears of both mouse groups by acridine orange staining. Moreover, by 3 days postchallenge, the mRNA accumulation levels of NF-kappaB, tumor necrosis factor alpha, interleukin 1beta, MIP1alpha, Muc5ac, and Muc5b were significantly lower in the ears of TLR2(-/-) mice than in WT mice. In summary, TLR2(-/-) mice may produce relatively low levels of proinflammatory cytokines following pneumococcal challenge, thus hindering the clearance of bacteria from the middle ear and leading to sepsis and a high mortality rate. This study provides evidence that TLR2 is important in the molecular pathogenesis and host response to otitis media. PMID:19414550

  8. Administration of a Toll-like receptor 9 agonist decreases the proviral reservoir in virologically suppressed HIV-infected patients.

    PubMed

    Winckelmann, Anni A; Munk-Petersen, Lærke V; Rasmussen, Thomas A; Melchjorsen, Jesper; Hjelholt, Thomas J; Montefiori, David; Østergaard, Lars; Søgaard, Ole S; Tolstrup, Martin

    2013-01-01

    Toll-like receptor (TLR) agonists can reactivate HIV from latently infected cells in vitro. We aimed to investigate the TLR-9 agonist, CPG 7909's in vivo effect on the proviral HIV reservoir and HIV-specific immunity. This was a post-hoc analysis of a double-blind randomized controlled vaccine trial. HIV-infected adults were randomized 1:1 to receive pneumococcal vaccines with or without 1 mg CPG 7909 as adjuvant at 0, 3 and 9 months. In patients on suppressive antiretroviral therapy we quantified proviral DNA at 0, 3, 4, 9, and 10 months (31 subjects in the CPG group and 37 in the placebo-adjuvant group). Furthermore, we measured HIV-specific antibodies, characterized T cell phenotypes and HIV-specific T cell immunity. We observed a mean reduction in proviral DNA in the CPG group of 12.6% (95% CI: -23.6-0.0) following each immunization whereas proviral DNA in the placebo-adjuvant group remained largely unchanged (6.7% increase; 95% CI: -4.2-19.0 after each immunization, p = 0.02). Among participants with additional cryo-preserved PBMCs, HIV-specific CD8+ T cell immunity as indicated by increased expression of degranulation marker CD107a and macrophage inflammatory protein 1β (MIP1β) tended to be up-regulated following immunization with CPG 7909 compared with placebo as adjuvant. Further, increasing proportion of HIV-specific CD107a and MIP1β-expressing CD8+ T cells were strongly correlated with decreasing proviral load. No changes were observed in T cell phenotype distribution, HIV-specific CD4+ T cell immunity, or HIV-specific antibodies. TLR9-adjuvanted pneumococcal vaccination decreased proviral load. Reductions in proviral load correlated with increasing levels of HIV specific CD8+ T cells. Further investigation into the potential effect of TLR9 agonists on HIV latency is warranted. PMID:23637967

  9. Patency of Litomosoides sigmodontis infection depends on Toll-like receptor 4 whereas Toll-like receptor 2 signalling influences filarial-specific CD4(+) T-cell responses.

    PubMed

    Rodrigo, Maria B; Schulz, Sandy; Krupp, Vanessa; Ritter, Manuel; Wiszniewsky, Katharina; Arndts, Kathrin; Tamadaho, Ruth S E; Endl, Elmar; Hoerauf, Achim; Layland, Laura E

    2016-04-01

    BALB/c mice develop a patent state [release of microfilariae (Mf), the transmission life-stage, into the periphery] when exposed to the rodent filariae Litomosoides sigmodontis. Interestingly, only a portion of the infected mice become patent, which reflects the situation in human individuals infected with Wuchereria bancrofti. Since those individuals had differing filarial-specific profiles, this study compared differences in immune responses between Mf(+) and Mf(-) infected BALB/c mice. We demonstrate that cultures of total spleen or mediastinal lymph node cells from Mf(+) mice produce significantly more interleukin-5 (IL-5) to filarial antigens but equal levels of IL-10 when compared with Mf(-) mice. However, isolated CD4(+) T cells from Mf(+) mice produced significantly higher amounts of all measured cytokines, including IL-10, when compared with CD4(+) T-cell responses from Mf(-) mice. Since adaptive immune responses are influenced by triggering the innate immune system we further studied the immune profiles and parasitology in infected Toll-like receptor-2-deficient (TLR2(-/-)) and TLR4(-/-) BALB/c mice. Ninety-three per cent of L. sigmodontis-exposed TLR4(-/-) BALB/c mice became patent (Mf(+)) although worm numbers remained comparable to those in Mf(+) wild-type controls. Lack of TLR2 had no influence on patency outcome or worm burden but infected Mf(+) mice had significantly lower numbers of Foxp3(+) regulatory T cells and dampened peripheral immune responses. Interestingly, in vitro culturing of CD4(+) T cells from infected wild-type mice with granulocyte-macrophage colony-stimulating factor-derived TLR2(-/-) dendritic cells resulted in an overall diminished cytokine profile to filarial antigens. Hence, triggering TLR4 or TLR2 during chronic filarial infection has a significant impact on patency and efficient CD4(+) T-cell responses, respectively. PMID:26714796

  10. Gedunin Binds to Myeloid Differentiation Protein 2 and Impairs Lipopolysaccharide-Induced Toll-Like Receptor 4 Signaling in Macrophages.

    PubMed

    Borges, Perla Villani; Moret, Katelim Hottz; Maya-Monteiro, Clarissa Menezes; Souza-Silva, Franklin; Alves, Carlos Roberto; Batista, Paulo Ricardo; Caffarena, Ernesto Raúl; Pacheco, Patrícia; Henriques, Maria das Graças; Penido, Carmen

    2015-11-01

    Recognition of bacterial lipopolysaccharide (LPS) by innate immune system is mediated by the cluster of differentiation 14/Toll-like receptor 4/myeloid differentiation protein 2 (MD-2) complex. In this study, we investigated the modulatory effect of gedunin, a limonoid from species of the Meliaceae family described as a heat shock protein Hsp90 inhibitor, on LPS-induced response in immortalized murine macrophages. The pretreatment of wild-type (WT) macrophages with gedunin (0.01-100 µM, noncytotoxic concentrations) inhibited LPS (50 ng/ml)-induced calcium influx, tumor necrosis factor-α, and nitric oxide production in a concentration-dependent manner. The selective effect of gedunin on MyD88-adapter-like/myeloid differentiation primary response 88- and TRIF-related adaptor molecule/TIR domain-containing adapter-inducing interferon-β-dependent signaling pathways was further investigated. The pretreatment of WT, TIR domain-containing adapter-inducing interferon-β knockout, and MyD88 adapter-like knockout macrophages with gedunin (10 µM) significantly inhibited LPS (50 ng/ml)-induced tumor necrosis factor-α and interleukin-6 production, at 6 hours and 24 hours, suggesting that gedunin modulates a common event between both signaling pathways. Furthermore, gedunin (10 µM) inhibited LPS-induced prostaglandin E2 production, cyclooxygenase-2 expression, and nuclear factor κB translocation into the nucleus of WT macrophages, demonstrating a wide-range effect of this chemical compound. In addition to the ability to inhibit LPS-induced proinflammatory mediators, gedunin also triggered anti-inflammatory factors interleukin-10, heme oxygenase-1, and Hsp70 in macrophages stimulated or not with LPS. In silico modeling studies revealed that gedunin efficiently docked into the MD-2 LPS binding site, a phenomenon further confirmed by surface plasmon resonance. Our results reveal that, in addition to Hsp90 modulation, gedunin acts as a competitive inhibitor of LPS, blocking

  11. Antagonist-mediated down-regulation of toll-like receptors increases the prevalence of human papillomavirus infection in systemic lupus erythematosus

    PubMed Central

    2012-01-01

    Introduction Prevalence of an abnormal Papanicolaou smear was significantly increased in lupus patients in cross-sectional studies, associated with a higher prevalence of high-risk human papillomavirus (HPV) infection. The nucleic acid-specific Toll-like receptors (TLRs) locate at the endolysosomal compartments and trigger the induction of cytokines for the innate immune response. This study evaluated whether abnormal host innate immune response in lupus patients may enhance HPV persistence. Methods Protein levels of TLRs 3, 7, 8 and 9 in cervical epithelial cells of lupus patients and controls with or without HPV infection were assessed using flow cytometry. Characteristics associated with the differential expression of TLRs in systemic lupus erythematosus (SLE) were elucidated. The effect and interferon-stimulated genes (ISGs) (ISG15 and Mx-1) gene expressions were then measured in oncogenic HeLa (HPV18), CaSki (HPV) and C33A (HPV negative) cell lines using flow cytometry and quantitative real-time PCR. Ex vivo productions of cytokines and interferon-gamma (IFN-γ) upon TLR ligands stimulations were subsequently measured using cytometric bead array and ELISA. Results For subjects with HPV infection, levels of TLR3 and TLR7 were significantly lower in lupus patients compared with controls. Significantly decreased TLRs 7, 8 and 9 levels were observed in HPV-negative SLE compared to healthy controls. For SLE with and without HPV infection, TLR7 and 9 levels were significantly lower in infected SLE than those in HPV-negative patients. Independent explanatory variables associated with down-regulation of TLR7 level included HPV infection and a higher cumulative dose of prednisolone; while a higher cumulative dose of hydroxychloroquine and HPV infection were associated with down-regulation of TLR9 level. In cervical cell lines, TLRs 3, 7, 8, 9 protein levels and antiviral ISG15 and Mx-1 gene expressions were inhibited in two oncogenic HPV types. Functional data showed

  12. Vaccine-mediated immunity to experimental Mycobacterium tuberculosis is not impaired in the absence of Toll-like receptor 9.

    PubMed

    Gopalakrishnan, Archana; Dietzold, Jillian; Salgame, Padmini

    2016-04-01

    Accumulating evidence indicates that inflammatory signals required for maximizing effector T cell generation have opposing effects on the development of memory T cell precursors. Toll-like receptor (TLR)2, and TLR9 significantly contribute to the inflammatory milieu and therefore in this study we examined whether the absence of TLR9 alone or the combined absence of TLR2 and TLR9 would affect vaccine-mediated immunity to Mtb. We found that TLR9KO and TLR2/9DKO mice vaccinated with a live Mtb auxotroph, akin to vaccinated WT mice, exhibited early control of Mtb growth in the lungs compared to their naïve counterparts. The granulomatous response, IFNγ production and cellular recruitment to the lungs were also similar in all the vaccinated groups of mice. These findings indicate that there is minimal contribution from TLR2 and TLR9 in generating memory immunity to Mtb with live vaccines. Defining the innate milieu that can drive maximal memory T cell generation with a tuberculosis vaccine needs further inquiry. PMID:26748860

  13. A Temporal Gate for Viral Enhancers to Co-opt Toll-Like-Receptor Transcriptional Activation Pathways upon Acute Infection

    PubMed Central

    Kropp, Kai A.; Hsieh, Wei Yuan; Isern, Elena; Forster, Thorsten; Krause, Eva; Brune, Wolfram; Angulo, Ana; Ghazal, Peter

    2015-01-01

    Viral engagement with macrophages activates Toll-Like-Receptors (TLRs) and viruses must contend with the ensuing inflammatory responses to successfully complete their replication cycle. To date, known counter-strategies involve the use of viral-encoded proteins that often employ mimicry mechanisms to block or redirect the host response to benefit the virus. Whether viral regulatory DNA sequences provide an opportunistic strategy by which viral enhancer elements functionally mimic innate immune enhancers is unknown. Here we find that host innate immune genes and the prototypical viral enhancer of cytomegalovirus (CMV) have comparable expression kinetics, and positively respond to common TLR agonists. In macrophages but not fibroblasts we show that activation of NFκB at immediate-early times of infection is independent of virion-associated protein, M45. We find upon virus infection or transfection of viral genomic DNA the TLR-agonist treatment results in significant enhancement of the virus transcription-replication cycle. In macrophage time-course infection experiments we demonstrate that TLR-agonist stimulation of the viral enhancer and replication cycle is strictly delimited by a temporal gate with a determined half-maximal time for enhancer-activation of 6 h; after which TLR-activation blocks the viral transcription-replication cycle. By performing a systematic siRNA screen of 149 innate immune regulatory factors we identify not only anticipated anti-viral and pro-viral contributions but also new factors involved in the CMV transcription-replication cycle. We identify a central convergent NFκB-SP1-RXR-IRF axis downstream of TLR-signalling. Activation of the RXR component potentiated direct and indirect TLR-induced activation of CMV transcription-replication cycle; whereas chromatin binding experiments using wild-type and enhancer-deletion virus revealed IRF3 and 5 as new pro-viral host transcription factor interactions with the CMV enhancer in macrophages. In a

  14. Toll-like receptors 2 and 4 impair insulin-mediated brain activity by interleukin-6 and osteopontin and alter sleep architecture.

    PubMed

    Sartorius, Tina; Lutz, Stefan Z; Hoene, Miriam; Waak, Jens; Peter, Andreas; Weigert, Cora; Rammensee, Hans-Georg; Kahle, Philipp J; Häring, Hans-Ulrich; Hennige, Anita M

    2012-05-01

    Impaired insulin action in the brain represents an early step in the progression toward type 2 diabetes, and elevated levels of saturated free fatty acids are known to impair insulin action in prediabetic subjects. One potential mediator that links fatty acids to inflammation and insulin resistance is the Toll-like receptor (TLR) family. Therefore, C3H/HeJ/TLR2-KO (TLR2/4-deficient) mice were fed a high-fat diet (HFD), and insulin action in the brain as well as cortical and locomotor activity was analyzed by using telemetric implants. TLR2/4-deficient mice were protected from HFD-induced glucose intolerance and insulin resistance in the brain and displayed an improvement in cortical and locomotor activity that was not observed in C3H/HeJ mice. Sleep recordings revealed a 42% increase in rapid eye movement sleep in the deficient mice during daytime, and these mice spent 41% more time awake during the night period. Treatment of control mice with a neutralizing IL-6 antibody improved insulin action in the brain as well as cortical activity and diminished osteopontin protein to levels of the TLR2/4-deficient mice. Together, our data suggest that the lack of functional TLR2/4 protects mice from a fat-mediated impairment in insulin action, brain activity, locomotion, and sleep architecture by an IL-6/osteopontin-dependent mechanism. PMID:22278939

  15. Toll-like receptor 4 is involved in the cell cycle modulation and required for effective human cytomegalovirus infection in THP-1 macrophages

    SciTech Connect

    Arcangeletti, Maria-Cristina; Germini, Diego; Rodighiero, Isabella; Mirandola, Prisco; De Conto, Flora; Medici, Maria-Cristina; Gatti, Rita; Chezzi, Carlo; Calderaro, Adriana

    2013-05-25

    Suitable host cell metabolic conditions are fundamental for the effective development of the human cytomegalovirus (HCMV) lytic cycle. Indeed, several studies have demonstrated the ability of this virus to interfere with cell cycle regulation, mainly by blocking proliferating cells in G1 or G1/S. In the present study, we demonstrate that HCMV deregulates the cell cycle of THP-1 macrophages (a cell line irreversibly arrested in G0) by pushing them into S and G2 phases. Moreover, we show that HCMV infection of THP-1 macrophages leads to Toll-like receptor 4 (TLR4) activation. Since various studies have indicated TLR4 to be involved in promoting cell proliferation, here we investigate the possible role of TLR4 in the observed HCMV-induced cell cycle perturbation. Our data strongly support TLR4 as a mediator of HCMV-triggered cell cycle activation in THP-1 macrophages favouring, in turn, the development of an efficient viral lytic cycle. - Highlights: ► We studied HCMV infection impact on THP-1 macrophage cell cycle. ► We analysed the role played by Toll-like receptor (TLR) 4 upon HCMV infection. ► HCMV pushes THP-1 macrophages (i.e. resting cells) to re-enter the cell cycle. ► TLR4 pathway inhibition strongly affects the effectiveness of HCMV replication. ► TLR4 pathway inhibition significantly decreases HCMV-induced cell cycle re-entry.

  16. Proinflammatory Stimulation of Toll-Like Receptor 9 with High Dose CpG ODN 1826 Impairs Endothelial Regeneration and Promotes Atherosclerosis in Mice

    PubMed Central

    Steinmetz, Martin; Asdonk, Tobias; Lahrmann, Catharina; Lütjohann, Dieter; Nickenig, Georg; Zimmer, Sebastian

    2016-01-01

    Background Toll-like receptors (TLR) of the innate immune system have been closely linked with the development of atherosclerotic lesions. TLR9 is activated by unmethylated CpG motifs within ssDNA, but also by CpG motifs in nucleic acids released during vascular apoptosis and necrosis. The role of TLR9 in vascular disease remains controversial and we sought to investigate the effects of a proinflammatory TLR9 stimulation in mice. Methods and Findings TLR9-stimulation with high dose CpG ODN at concentrations between 6.25nM to 30nM induced a significant proinflammatory cytokine response in mice. This was associated with impaired reendothelialization upon acute denudation of the carotid and increased numbers of circulating endothelial microparticles, as a marker for amplified endothelial damage. Chronic TLR9 agonism in apolipoprotein E-deficient (ApoE-/-) mice fed a cholesterol-rich diet increased aortic production of reactive oxygen species, the number of circulating endothelial microparticles, circulating sca-1/flk-1 positive cells, and most importantly augmented atherosclerotic plaque formation when compared to vehicle treated animals. Importantly, high concentrations of CpG ODN are required for these proatherogenic effects. Conclusions Systemic stimulation of TLR9 with high dose CpG ODN impaired reendothelialization upon acute vascular injury and increased atherosclerotic plaque development in ApoE-/- mice. Further studies are necessary to fully decipher the contradictory finding of TLR9 agonism in vascular biology. PMID:26751387

  17. Toll-like receptor 2 mediates high-fat diet-induced impairment of vasodilator actions of insulin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rationale - Obesity is characterized by a chronic pro-inflammatory state that promotes insulin resistance in liver, adipose tissue, and skeletal muscle as well as impairing insulin action in vascular endothelium that contributes to endothelial dysfunction. Cadiovascular complications of obesity are ...

  18. Plasmacytoid dendritic cell precursors/type I interferon-producing cells sense viral infection by Toll-like receptor (TLR) 7 and TLR9.

    PubMed

    Ito, Tomoki; Wang, Yui-Hsi; Liu, Yong-Jun

    2005-01-01

    Plasmacytoid dendritic cell (pDC) precursors, also called type I IFN (alpha/beta/omega)-producing cells (IPCs), are the key effectors in the innate immune system because of their extraordinary capacity to produce type I IFNs against microbial infection, particularly viral infection. In contrast to myeloid DCs, human pDC/IPCs selectively express Toll-like receptor (TLR) 7 and TLR9 within the endosomal compartment. These receptors are specifically designed to recognize the nucleoside-based products derived from RNA viruses and DNA viruses. Therefore, this expression profile potentially enables pDC/IPCs to sense a variety of viruses. Stimulation of TLR7 or TLR9 leads to type I IFN responses through the MyD88 pathway. Thus, pDC/IPCs may play a central role in host defense against viral infection through the TLR7 and TLR9 system. PMID:15592841

  19. Impaired interferon-alpha production by plasmacytoid dendritic cells after cord blood transplantation in children: implication for post-transplantation toll-like receptor ligand-based immunotherapy.

    PubMed

    Charrier, Emily; Cordeiro, Paulo; Brito, Rose-Marie; Harnois, Michaël; Mezziani, Samira; Herblot, Sabine; Le Deist, Françoise; Duval, Michel

    2014-10-01

    Plasmacytoid dendritic cells (pDCs) initiate both innate and adaptive immune responses, making them attractive targets for post-transplantation immunotherapy, particularly after cord blood transplantation (CBT). Toll-like receptor (TLR) agonists are currently studied for pDC stimulation in various clinical settings. Their efficacy depends on pDC number and functionality, which are unknown after CBT. We performed a longitudinal study of pDC reconstitution in children who underwent bone marrow transplantation (BMT) and single-unit CBT. Both CBT and unrelated BMT patients received antithymocyte globulin as part of their graft-versus-host disease prophylaxis regimen. pDC blood counts were higher in CBT patients than in healthy volunteers from 2 to 9 months after transplantation, whereas they remained lower in BMT patients. We showed that cord blood progenitors gave rise in vitro to a 500-fold increase in functional pDCs over bone marrow counterparts. Upon stimulation with a TLR agonist, pDCs from both CBT and BMT recipients upregulated T cell costimulatory molecules, whereas interferon-alpha (IFN-α) production was impaired for 9 months after CBT. TLR agonist treatment is thus not expected to induce IFN-α production by pDCs after CBT, limiting its immunotherapeutic potential. Fortunately, in vitro production of large amounts of functional pDCs from cord blood progenitors paves the way for the post-transplantation adoptive transfer of pDCs. PMID:25128615

  20. Contribution of Toll-Like Receptor 2 to the Innate Response against Staphylococcus aureus Infection in Mice

    PubMed Central

    Kohanawa, Masashi; Zhao, Songji; Ozaki, Michitaka; Haga, Sanae; Kuge, Yuji; Tamaki, Nagara

    2013-01-01

    Staphylococcus aureus is a common pathogen that causes a wide range of infectious diseases. The function of TLRs, specifically TLR2, during S. aureus infection is still debated. In this study, we investigated the extent to which TLR2 contributes to the host innate response against the bacterial infection using TLR2-deficient mice. Intravenous inoculation with S. aureus resulted in all TLR2-deficient mice dying within 4 d, along with a high bacterial burden in the livers. However, histological examination showed the same degree of macrophage and neutrophil accumulation in the livers of infected TLR2-deficient mice as that in infected wild-type (WT) mice. TLR2-deficient mouse macrophages also showed normal phagocytic activity, although they failed to express CD36 that appeared on the surface of WT mouse cells upon challenge with heat-killed S. aureus. These data indicate that TLR2, as well as CD36, does not directly affect S. aureus clearance and that CD36 expression on macrophages depends on the presence of TLR2. In vivo infection with S. aureus caused significantly elevated production of TNF-α and IL-6 in the livers and blood of TLR2-deficient mice compared with those in WT mice, while the hepatic and serum levels of IL-10 decreased in these mice. In contrast, lower expression of IL-6 and IL-10, but not of TNF-α, at both the gene and protein levels was found in TLR2-deficient mouse macrophages compared to that in WT mouse cells, in response to challenge with heat-killed S. aureus. These findings suggest that the S. aureus-induced pro-inflammatory cytokine response is not dependent on macrophages and that TLR2 deficiency results in decreased IL-10 release by macrophages, which contributes to dysregulated cytokine balance, impaired bacterial clearance, and mouse death. Therefore, TLR2 possesses a protective function during S. aureus infection by regulating pro- and anti-inflammatory cytokine responses. PMID:24058538

  1. Molecular cloning, characterization and expression analysis of Toll-like receptor 5M gene in Japanese sea perch (Lateolabrax japonicas) after bacterial infection.

    PubMed

    Wang, Chengyang; Zhao, Chao; Fu, Mingjun; Bao, Weiyang; Qiu, Lihua

    2016-09-01

    Toll-like receptor 5M belongs to Toll-like receptors (TLRs) family, which plays a crucial role in innate immunity due to its important role in the recognition of bacteria invasion and in the activation of immune related pathways downstream. In the present study, we firstly cloned the full-length cDNAs of TLR 5M (LjTLR 5M) from Japanese sea perch (Lateolabrax japonicas). The full-length cDNAs of LjTLR 5M include an open reading frame (ORF) of 2676 bp encoding a polypeptide of 891 amino acid residues. The deduced amino acid sequence analysis showed that LiTLR 5M contains LRRs (extracellular leucine rich repeats), transmembrane and TIR (Toll/interleukin-1 receptor) domain. Transcriptional expression analysis indicated that LiTLR 5M mRNAs were ubiquitously expressed in wide array of tissues and the peak level was observed in the head-kidney. The expression patterns of LjTLR 5M after Vibro harveyi and Streptococus agalactiae infection were detected by qRT-PCR, and the results showed that LjTLR 5M was significant up-regulated in spleen, liver and head-kidney. Additionally, the expression patterns of LjTLR 5M in infected spleen and head-kidney were further validated by in situ hybridization (ISH). In summary, these findings indicate that LjTLR 5M is significant induced after different bacterial infection and is involved in immune response. Furthermore, this study will provide foundational information for other TLRs research of L. japonicas against different bacterial pathogens invasion. PMID:27417233

  2. Attenuation of Toll-Like Receptor Expression and Function in Latent Tuberculosis by Coexistent Filarial Infection with Restoration Following Antifilarial Chemotherapy

    PubMed Central

    Babu, Subash; Bhat, Sajid Q.; Kumar, N. Pavan; Anuradha, R.; Kumaran, Paul; Gopi, P. G.; Kolappan, C.; Kumaraswami, V.; Nutman, Thomas B.

    2009-01-01

    Mycobacterium tuberculosis (Mtb) and filarial coinfection is highly prevalent, and the presence of filarial infections may regulate the Toll-like receptor (TLR)-dependent immune response needed to control Mtb infection. By analyzing the baseline and mycobacterial antigen–stimulated expression of TLR1, 2, 4, and 9 (in individuals with latent tuberculosis [TB] with or without filarial infection), we were able to demonstrate that filarial infection, coincident with Mtb, significantly diminishes both baseline and Mtb antigen-specific TLR2 and TLR9 expression. In addition, pro-inflammatory cytokine responses to TLR2 and 9 ligands are significantly diminished in filaria/TB-coinfected individuals. Definitive treatment of lymphatic filariasis significantly restores the pro-inflammatory cytokine responses in individuals with latent TB. Coincident filarial infection exerted a profound inhibitory effect on protective mycobacteria-specific TLR-mediated immune responses in latent tuberculosis and suggests a novel mechanism by which concomitant filarial infections predispose to the development of active tuberculosis in humans. PMID:19636364

  3. A Cellular Micro-RNA, let-7i, Regulates Toll-like Receptor 4 Expression and Contributes to Cholangiocyte Immune Responses against Cryptosporidium parvum Infection*

    PubMed Central

    Chen, Xian-Ming; Splinter, Patrick L.; O'Hara, Steven P.; LaRusso, Nicholas F.

    2007-01-01

    Toll-like receptors (TLRs) are important pathogen recognition molecules and are key to epithelial immune responses to microbial infection. However, the molecular mechanisms that regulate TLR expression in epithelia are obscure. Micro-RNAs play important roles in a wide range of biological events through post-transcriptional suppression of target mRNAs. Here we report that human biliary epithelial cells (cholangiocytes) express let-7 family members, micro-RNAs with complementarity to TLR4 mRNA. We found that let-7 regulates TLR4 expression via post-transcriptional suppression in cultured human cholangiocytes. Infection of cultured human cholangiocytes with Cryptosporidium parvum, a parasite that causes intestinal and biliary disease, results in decreased expression of primary let-7i and mature let-7 in a MyD88/NF-κB-dependent manner. The decreased let-7 expression is associated with C. parvum-induced up-regulation of TLR4 in infected cells. Moreover, experimentally induced suppression or forced expression of let-7i causes reciprocal alterations in C. parvum-induced TLR4 protein expression, and consequently, infection dynamics of C. parvum in vitro. These results indicate that let-7i regulates TLR4 expression in cholangiocytes and contributes to epithelial immune responses against C. parvum infection. Furthermore, the data raise the possibility that micro-RNA-mediated post-transcriptional pathways may be critical to host-cell regulatory responses to microbial infection in general. PMID:17660297

  4. Pregnane X Receptor Regulates Pathogen-Induced Inflammation and Host Defense against an Intracellular Bacterial Infection through Toll-like Receptor 4

    PubMed Central

    Qiu, Zhijuan; Cervantes, Jorge L.; Cicek, Basak B.; Mukherjee, Subhajit; Venkatesh, Madhukumar; Maher, Leigh A.; Salazar, Juan C.; Mani, Sridhar; Khanna, Kamal M.

    2016-01-01

    The nuclear pregnane X receptor (PXR) plays a central role in regulating xenobiotic metabolism. We now report a novel role for PXR as a critical negative regulator of innate immunity after infection. Pxr−/− mice exhibited remarkably elevated pro-inflammatory cytokine and chemokine production following infection with Listeria monocytogenes (Lm). Despite the more robust innate immune response, Pxr−/− mice were highly susceptible to Lm infection. Surprisingly, disruption of the Toll-like receptor 4 (TLR4) but not TLR2 signaling restored the inflammation to normal levels and the ability to clear Lm in Pxr−/− mice. Mechanistically, the heightened inflammation in Pxr−/− mice resulted in the death of inflammatory monocytes that led to the enhanced susceptibility to Lm infection. These data demonstrated that PXR regulated pathogen-induced inflammation and host defense against Lm infection through modulating the TLR4 pathway. In summary, we discovered an apical role for PXR in regulating innate immunity. In addition, we uncovered a remarkable negative impact of the TLR4 pathway in controlling the quality of the inflammatory response and host defense against a gram-positive bacterial infection. PMID:27550658

  5. Pregnane X Receptor Regulates Pathogen-Induced Inflammation and Host Defense against an Intracellular Bacterial Infection through Toll-like Receptor 4.

    PubMed

    Qiu, Zhijuan; Cervantes, Jorge L; Cicek, Basak B; Mukherjee, Subhajit; Venkatesh, Madhukumar; Maher, Leigh A; Salazar, Juan C; Mani, Sridhar; Khanna, Kamal M

    2016-01-01

    The nuclear pregnane X receptor (PXR) plays a central role in regulating xenobiotic metabolism. We now report a novel role for PXR as a critical negative regulator of innate immunity after infection. Pxr(-/-) mice exhibited remarkably elevated pro-inflammatory cytokine and chemokine production following infection with Listeria monocytogenes (Lm). Despite the more robust innate immune response, Pxr(-/-) mice were highly susceptible to Lm infection. Surprisingly, disruption of the Toll-like receptor 4 (TLR4) but not TLR2 signaling restored the inflammation to normal levels and the ability to clear Lm in Pxr(-/-) mice. Mechanistically, the heightened inflammation in Pxr(-/-) mice resulted in the death of inflammatory monocytes that led to the enhanced susceptibility to Lm infection. These data demonstrated that PXR regulated pathogen-induced inflammation and host defense against Lm infection through modulating the TLR4 pathway. In summary, we discovered an apical role for PXR in regulating innate immunity. In addition, we uncovered a remarkable negative impact of the TLR4 pathway in controlling the quality of the inflammatory response and host defense against a gram-positive bacterial infection. PMID:27550658

  6. Expression of Toll-like receptor signaling-related genes in pigs co-infected with porcine reproductive and respiratory syndrome virus and porcine circovirus type 2.

    PubMed

    Dong, Van Hieu; Tu, Pang-Yan; Tsai, Pei-Chun; Lin, Yi-Hsin; Chang, Hsiu-Luan; Kuo, Tsun-Yung; Chiou, Ming-Tang; Lin, Chao-Nan; Chung, Wen-Bin

    2015-08-01

    Pigs co-infected with porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV2) have been shown to develop more severe diseases than pigs infected with PRRSV or PCV2 only. The underlying interaction mechanisms between the two viruses in developing the disease are unclear. The present study investigates the mRNA expression of Toll-like receptor (TLR) signaling-related molecules in peripheral blood mononuclear cells from pigs infected with PRRSV or PCV2 or both. The mRNA expression levels were determined by quantitative real-time RT-PCR. Co-infection of pigs with PRRSV and PCV2 resulted in a negatively synergistic effect on the mRNA expression of the negative regulators of TLR, including A20, Bcl-3, IRAK-M, MKP-1, SARM1 and SIGIRR, as well as the TLR downstream transcription factors IRF-1 and IRF-3. A positively synergistic effect of a combined infection of PRRSV and PCV2 on the CD14 mRNA expression was also observed. PMID:26022073

  7. In ovo delivery of Toll-like receptor 2 ligand, lipoteichoic acid induces pro-inflammatory mediators reducing post-hatch infectious laryngotracheitis virus infection.

    PubMed

    Thapa, S; Nagy, E; Abdul-Careem, M F

    2015-04-15

    Toll-like receptor (TLR) ligands are pathogen associated molecular patterns (PAMPs) recognized by the TLRs resulting in induction of host innate immune responses. One of the PAMPs that binds to TLR2 and cluster of differentiation (CD) 14 is lipotechoic acid (LTA), which activates downstream signals culminating in the release of pro-inflammatory cytokines. In this study, we investigated whether in ovo LTA delivery leads to the induction of antiviral responses against post-hatch infectious laryngotracheitis virus (ILTV) infection. We first delivered the LTA into embryo day (ED)18 eggs via in ovo route so that the compound is available at the respiratory mucosa. Then the LTA treated and control ED18 eggs were allowed to hatch and the hatched chicken was infected with ILTV intratracheally on the day of hatch. We found that in ovo delivered LTA reduces ILTV infection post-hatch. We also found that in ovo delivery of LTA significantly increases mRNA expression of pro-inflammatory mediators in pre-hatch embryo lungs as well as mononuclear cell infiltration, predominantly macrophages, in lung of post-hatch chickens. Altogether, the data suggest that in ovo delivered LTA could be used to reduce ILTV infection in newly hatched chickens. PMID:25764942

  8. Therapeutic Administration of KM+ Lectin Protects Mice Against Paracoccidioides brasiliensis Infection via Interleukin-12 Production in a Toll-Like Receptor 2-Dependent Mechanism

    PubMed Central

    Coltri, Kely C.; Oliveira, Leandro L.; Pinzan, Camila F.; Vendruscolo, Patrícia E.; Martinez, Roberto; Goldman, Maria Helena; Panunto-Castelo, Ademilson; Roque-Barreira, Maria-Cristina

    2008-01-01

    KM+ is a mannose-binding lectin from Artocarpus integrifolia that induces interleukin (IL)-12 production by macrophages and protective T helper 1 immune response against Leishmania major infection. In this study, we performed experiments to evaluate the therapeutic activity of jackfruit KM+ (jfKM+) and its recombinant counterpart (rKM+) in experimental paracoccidioidomycosis. To this end, jfKM+ or rKM+ was administered to BALB/c mice 10 days after infection with Paracoccidiodes brasiliensis. Thirty days postinfection, lungs from the KM+-treated mice contained significantly fewer colony-forming units and little to no organized granulomas compared to the controls. In addition, lung homogenates from the KM+-treated mice presented higher levels of nitric oxide, IL-12, interferon-γ, and tumor necrosis factor-α, whereas higher levels of IL-4 and IL-10 were detected in the control group. With mice deficient in IL-12, Toll-like receptor (TLR) 2, TLR4, or TLR adaptor molecule MyD88, we demonstrated that KM+ led to protection against P. brasiliensis infection through IL-12 production, which was dependent on TLR2. These results demonstrated a beneficial effect of KM+ on the severity of P. brasiliensis infection and may expand its potential use as a novel immunotherapeutic molecule. PMID:18599609

  9. A Toll-Like Receptor 5 Agonist Improves the Efficacy of Antibiotics in Treatment of Primary and Influenza Virus-Associated Pneumococcal Mouse Infections

    PubMed Central

    Porte, Rémi; Fougeron, Delphine; Muñoz-Wolf, Natalia; Tabareau, Julien; Georgel, Anne-France; Wallet, Fréderic; Paget, Christophe; Trottein, François; Chabalgoity, José A.; Carnoy, Christophe

    2015-01-01

    Prophylactic intranasal administration of the Toll-like receptor 5 (TLR5) agonist flagellin protects mice against respiratory pathogenic bacteria. We hypothesized that TLR5-mediated stimulation of lung immunity might improve the therapeutic index of antibiotics for the treatment of Streptococcus pneumoniae respiratory infections in mice. Intranasal administration of flagellin was combined with either oral administration of amoxicillin or intraperitoneal injection of trimethoprim-sulfamethoxazole to treat S. pneumoniae-infected animals. Compared with standalone treatments, the combination of antibiotic and flagellin resulted in a lower bacterial load in the lungs and greater protection against S. pneumoniae dissemination and was associated with an early increase in neutrophil infiltration in the airways. The antibiotic-flagellin combination treatment was, however, not associated with any exacerbation of inflammation. Moreover, combination treatment was more efficacious than standalone antibiotic treatments in the context of post-influenza virus pneumococcal infection. Lastly, TLR5 signaling was shown to be mandatory for the efficacy of the combined antibacterial therapy. This report is the first to show that combining antibiotic treatment with the stimulation of mucosal innate immunity is a potent antibacterial strategy against pneumonia. PMID:26195519

  10. Roles of Toll-like receptors 2 and 6 in the inflammatory response to Mycoplasma gallisepticum infection in DF-1 cells and in chicken embryos.

    PubMed

    Tian, Wei; Zhao, Chengcheng; Hu, Qingchuang; Sun, Jianjun; Peng, Xiuli

    2016-06-01

    While Mycoplasma gallisepticum (MG) is a major pathogen that causes chronic respiratory diseases in chicken, the molecular mechanism of MG infection is not clear. In this study, we investigated the roles of Toll-like receptor 2 (TLR2) and 6 (TLR6) in MG infection. We found that TLR2 type 2 (TLR2-2) and TLR6 had differential expressions in chicken embryo fibroblasts (DF-1 cells), where TLR6 was highly expressed, but TLR2-2 was barely expressed. Upon MG infection, TLR6 expression was upregulated, followed by upregulation of downstream factors, MyD88, NF-κB, IL2, IL6, and TNF-α. Knockdown of TLR6 expression by shRNA abolished the MG-induced inflammatory responses. More interestingly, in the presence of TLR6, TLR2-2 didn't respond to MG infection in DF-1 cells. When TLR6 was knocked down by shRNA, however, TLR2 was upregulated upon MG infection, which was followed by upregulation of proinflammatory genes. Finally, we tested effects of the MG infection on expression of TLR2-2 and TLR6 in the lungs and trachea tissues of chicken embryos. We found both TLR2-2 and TLR6 were upregulated upon MG infection, followed by upregulation of the downstream NF-κB-mediated inflammatory responses. This study was the first to report the differential roles of TLR2-2 and TLR6 in MG-infected DF-1 cells and chicken embryos. PMID:26797426

  11. Interleukin-1 receptor but not Toll-like receptor 2 is essential for MyD88-dependent Th17 immunity to Coccidioides infection.

    PubMed

    Hung, Chiung-Yu; Jiménez-Alzate, María del Pilar; Gonzalez, Angel; Wüthrich, Marcel; Klein, Bruce S; Cole, Garry T

    2014-05-01

    Interleukin-17A (IL-17A)-producing CD4(+) T helper (Th17) cells have been shown to be essential for defense against pulmonary infection with Coccidioides species. However, we have just begun to identify the required pattern recognition receptors and understand the signal pathways that lead to Th17 cell activation after fungal infection. We previously reported that Card9(-/-) mice vaccinated with formalin-killed spherules failed to acquire resistance to Coccidioides infection. Here, we report that both MyD88(-/-) and Card9(-/-) mice immunized with a live, attenuated vaccine also fail to acquire protective immunity to this respiratory disease. Like Card9(-/-) mice, vaccinated MyD88(-/-) mice revealed a significant reduction in numbers of both Th17 and Th1 cells in their lungs after Coccidioides infection. Both Toll-like receptor 2 (TLR2) and IL-1 receptor type 1 (IL-1r1) upstream of MyD88 have been implicated in Th17 cell differentiation. Surprisingly, vaccinated TLR2(-/-) and wild-type (WT) mice showed similar outcomes after pulmonary infection with Coccidioides, while vaccinated IL-1r1(-/-) mice revealed a significant reduction in the number of Th17 cells in their infected lungs compared to WT mice. Thus, activation of both IL-1r1/MyD88- and Card9-mediated Th17 immunity is essential for protection against Coccidioides infection. Our data also reveal that the numbers of Th17 cells were reduced in IL-1r1(-/-) mice to a lesser extent than in MyD88(-/-) mice, raising the possibility that other TLRs are involved in MyD88-dependent Th17 immunity to coccidioidomycosis. An antimicrobial action of Th17 cells is to promote early recruitment of neutrophils to infection sites. Our data revealed that neutrophils are required for vaccine immunity to this respiratory disease. PMID:24614655

  12. Toll-Like Receptor 9 Is Required for Full Host Resistance to Mycobacterium avium Infection but Plays No Role in Induction of Th1 Responses▿

    PubMed Central

    Carvalho, Natália B.; Oliveira, Fernanda S.; Durães, Fernanda V.; de Almeida, Leonardo A.; Flórido, Manuela; Prata, Luana O.; Caliari, Marcelo V.; Appelberg, Rui; Oliveira, Sérgio C.

    2011-01-01

    To investigate the role of Toll-like receptor 9 (TLR9) in innate immunity to Mycobacterium avium, TLR9, TLR2, and MyD88 knockout (KO) mice were infected with this bacterium. Bacterial burdens were higher in the spleens, livers, and lungs of infected TLR9 KO mice than in those of C57BL/6 mice, indicating that TLR9 is required for efficient control of M. avium infection. However, TLR9 KO or TLR2 KO spleen cells displayed normal M. avium-induced tumor necrosis factor alpha (TNF-α) and gamma interferon (IFN-γ) responses. This finding was confirmed by determining the number of splenic CD4+ T cells producing IFN-γ by flow cytometry. Furthermore, TLR2 and MyD88, but not TLR9, played a major role in interleukin-12 and TNF-α production by M. avium-infected macrophages and dendritic cells (DCs). We also found that major histocompatibility complex class II molecule expression on DCs is regulated by TLR2 and MyD88 signaling but not by TLR9. Finally, lack of TLR9, TLR2, or MyD88 reduced the numbers of macrophages, epithelioid cells, and lymphocytes in M. avium-induced granulomas but only MyD88 deficiency affected the number of liver granulomas. In summary, our data demonstrated that the involvement of TLR9 in the control of M. avium infection is not related to the induction of Th1 responses. PMID:21300776

  13. BVDV infection alters toll-like and TNF-alpha receptor signalling in bovine aortic endothelial cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aim. Bovine aortic endothelial cells (BAEC) are readily available commercially and are used in many labs in a variety of experiments. However, most lots of BAEC are contaminated with BVDV. It was unknown what effect BVDV had on normal function of BAEC. Here, we examined the effect of BVDV infect...

  14. Toll-Like Receptor 9-Mediated Protection of Enterovirus 71 Infection in Mice Is Due to the Release of Danger-Associated Molecular Patterns

    PubMed Central

    Hsiao, Hung-Bo; Chou, Ai-Hsiang; Lin, Su-I; Chen, I-Hua; Lien, Shu-Pei; Liu, Chia-Chyi; Chong, Pele

    2014-01-01

    ABSTRACT Enterovirus 71 (EV71), a positive-stranded RNA virus, is the major cause of hand, foot, and mouth disease (HFMD) with severe neurological symptoms. Antiviral type I interferon (alpha/beta interferon [IFN-α/β]) responses initiated from innate receptor signaling are inhibited by EV71-encoded proteases. It is less well understood whether EV71-induced apoptosis provides a signal to activate type I interferon responses as a host defensive mechanism. In this report, we found that EV71 alone cannot activate Toll-like receptor 9 (TLR9) signaling, but supernatant from EV71-infected cells is capable of activating TLR9. We hypothesized that TLR9-activating signaling from plasmacytoid dendritic cells (pDCs) may contribute to host defense mechanisms. To test our hypothesis, Flt3 ligand-cultured DCs (Flt3L-DCs) from both wild-type (WT) and TLR9 knockout (TLR9KO) mice were infected with EV71. More viral particles were produced in TLR9KO mice than by WT mice. In contrast, alpha interferon (IFN-α), monocyte chemotactic protein 1 (MCP-1), tumor necrosis factor-alpha (TNF-α), IFN-γ, interleukin 6 (IL-6), and IL-10 levels were increased in Flt3L-DCs from WT mice infected with EV71 compared with TLR9KO mice. Seven-day-old TLR9KO mice infected with a non-mouse-adapted EV71 strain developed neurological lesion-related symptoms, including hind-limb paralysis, slowness, ataxia, and lethargy, but WT mice did not present with these symptoms. Lung, brain, small intestine, forelimb, and hind-limb tissues collected from TLR9KO mice exhibited significantly higher viral loads than equivalent tissues collected from WT mice. Histopathologic damage was observed in brain, small intestine, forelimb, and hind-limb tissues collected from TLR9KO mice infected with EV71. Our findings demonstrate that TLR9 is an important host defense molecule during EV71 infection. IMPORTANCE The host innate immune system is equipped with pattern recognition receptors (PRRs), which are useful for defending

  15. Infection Mobilizes Hematopoietic Stem Cells through Cooperative NOD-like Receptor and Toll-like Receptor Signaling

    PubMed Central

    Burberry, Aaron; Zeng, Melody Y.; Ding, Lei; Wicks, Ian; Inohara, Naohiro; Morrison, Sean J.; Núñez, Gabriel

    2014-01-01

    Summary Adult hematopoietic stem cells (HSCs) are maintained in specialized niches within the bone marrow under steady-state conditions and mobilized for extramedullary hematopoiesis during periods of stress such as bacterial infections. However, the underlying mechanisms are unclear. We show that systemic infection of mice with Escherichia coli, commonly associated with bacteremia in humans, mobilizes functional HSCs to the spleen. Accumulation of splenic HSCs (CD150+CD48-Lin−/lowScal1+cKit+) was diminished in TLR4-deficient and RIPK2-deficient mice, implicating TLRs and cytosolic NOD1/NOD2 signaling in the process. Accordingly, dual stimulation of NOD1 and TLR4 in radio-resistant cells alone was sufficient to mobilize HSCs, while TLR4 expression on HSCs was dispensable. Mechanistically, TLR4 and NOD1 synergistically induced granulocyte-colony stimulating factor (G-CSF), which was required for extramedullary HSC accumulation. Mobilized HSCs and progenitor cells gave rise to neutrophils and monocytes and contributed to limiting secondary infection. PMID:24882704

  16. Infection mobilizes hematopoietic stem cells through cooperative NOD-like receptor and Toll-like receptor signaling.

    PubMed

    Burberry, Aaron; Zeng, Melody Y; Ding, Lei; Wicks, Ian; Inohara, Naohiro; Morrison, Sean J; Núñez, Gabriel

    2014-06-11

    Adult hematopoietic stem cells (HSCs) are maintained in specialized niches within the bone marrow under steady-state conditions and mobilize for extramedullary hematopoiesis during periods of stress such as bacterial infections. However, the underlying mechanisms are unclear. We show that systemic infection of mice with Escherichia coli, commonly associated with bacteremia in humans, mobilizes functional HSCs to the spleen. Accumulation of splenic HSCs (CD150+CD48-Lin(-/low)Sca1+cKit+) was diminished in TLR4-deficient and RIPK2-deficient mice, implicating TLRs and cytosolic NOD1/NOD2 signaling in the process. Accordingly, dual stimulation of NOD1 and TLR4 in radio-resistant cells alone was sufficient to mobilize HSCs, while TLR4 expression on HSCs was dispensable. Mechanistically, TLR4 and NOD1 synergistically induced granulocyte colony-stimulating factor (G-CSF), which was required for extramedullary HSC accumulation. Mobilized HSCs and progenitor cells gave rise to neutrophils and monocytes and contributed to limiting secondary infection. PMID:24882704

  17. Type I Interferons Triggered through the Toll-Like Receptor 3–TRIF Pathway Control Coxsackievirus A16 Infection in Young Mice

    PubMed Central

    Yang, Juhao; Yang, Chunfu; Guo, Nining; Zhu, Kai; Luo, Kaiming; Zhang, Na; Zhao, Hui; Cui, Ying; Chen, Lei; Wang, Hongyang; Gu, Jun; Ge, Baoxue; Qin, Cheng-Feng

    2015-01-01

    ABSTRACT Coxsackievirus A16 (CVA16) is one of the major etiological agents of hand, foot, and mouth disease (HFMD) in children. The host defense mechanisms against CVA16 infection remain almost entirely unknown. Unlike previous observations with enterovirus 71 (EV71) infection, here we show that gamma interferon (IFN-γ) or invariant NK T cell deficiency does not affect disease development or the survival of CVA16-infected mice. In contrast, type I interferon receptor deficiency resulted in the development of more severe disease in mice, and the mice had a lower survival rate than wild-type mice. Similarly, a deficiency of Toll-like receptor 3 (TLR3) and TRIF, but not other pattern recognition receptors, led to the decreased survival of CVA16-infected mice. TLR3-TRIF signaling was indispensable for the induction of type I interferons during CVA16 infection in mice and protected young mice from disease caused by the infection. In particular, TRIF-mediated immunity was critical for preventing CVA16 replication in the neuronal system before disease occurred. IFN-β treatment was also found to compensate for TRIF deficiency in mice and decreased the disease severity in and mortality of CVA16-infected mice. Altogether, type I interferons induced by TLR3-TRIF signaling mediate protective immunity against CVA16 infection. These findings may shed light on therapeutic strategies to combat HFMD caused by CVA16 infection. IMPORTANCE Hand, foot, and mouth disease (HFMD) is a major threat to public health in the Asia-Pacific region. Both CVA16 and EV71 are major pathogens that are responsible for HFMD. The majority of research efforts have focused on the more virulent EV71, but little has been done with CVA16. Thus far, host immune responses to CVA16 infection have not yet been elucidated. The present study discovered an initial molecular mechanism underlying host protective immunity against CVA16 infection, providing the first explanation for why CVA16 and EV71 cause different

  18. Toll like receptor (TLR)-induced differential expression of microRNAs (MiRs) promotes proper immune response against infections: a systematic review.

    PubMed

    Aalaei-andabili, Seyed Hossein; Rezaei, Nima

    2013-10-01

    Toll like receptors (TLRs) are one of the major families of pattern recognition receptors (PRRs). MicroRNAs (MiRs) are small noncoding RNAs with regulatory effects on biological process, and it has been recently shown that they can control inflammatory process and the response to an infection by modulating the function of TLRs. In this study, we designed a systematic review to clarify the reciprocal interaction between TLRs and MiRs, in order to identify possible future therapeutic targets and strategies. On the one hand, TLRs stimulation can change expression level of miRs in various ways, which can lead to modulating their effects. On the other hand, MiRs also influence the expression of TLRs and the intensity of the inflammatory reaction. We therefore conclude that the interaction between MiRs and TLRs is a key regulator of innate immune system. Investigations discovering therapeutic approaches by manipulation of miRs expression level may open a new approach for the treatment of inflammatory diseases. PMID:23850616

  19. Toll-like receptors and interferon associated immune factors responses to spring viraemia of carp virus infection in common carp (Cyprinus carpio).

    PubMed

    Wei, Xinxian; Li, Xiao Zheng; Zheng, Xiaocong; Jia, Peng; Wang, Jinjin; Yang, Xianle; Yu, Li; Shi, Xiujie; Tong, Guixiang; Liu, Hong

    2016-08-01

    Pattern recognition receptor (PRR) toll-like receptors (TLRs), antiviral agent interferon (IFN) and the effector IFN stimulated genes (ISGs) play a fundamental role in the innate immune response against viruses among all vertebrate classes. Common carp is a host for spring viraemia of carp virus (Rhabdovirus carpio, SVCV), which belong to Rhabdoviridae family. The present in-vivo experiment was conducted to investigate the expression of these innate immune factors in early phase as well as during recovery of SVCV infection by real-time quantitative reverse transcriptase polymerase chain reaction. A less lethal SVCV infection was generated in common carp (Cyprinus carpio) and was sampled at 3, 6, 12 h post infection (hpi), 1, 3, 5, 7 and 10 days post infection (dpi). At 3 hpi, the SVCV N gene was detected in all three fish and all three fish showed a relative fold increase of TLR2, TLR3 and TLR7, IFNa1, ISG15 and Vig1. Viral copies rapidly increased at 12 hpi then remained high until 5 dpi. When viral copy numbers were high, a higher expression of immune genes TLR2, TLR3, TLR7, IFNa1, IFNa2, IFNa1S, IFN regulatory factor 3 (IRF3), IRF7, interleukin 1β (IL1β), IL6, IL10, ADAR, ISG15, Mx1, PKR and Vig1 were observed. Viral copies were gradually reduced in 5 to 10 dpi fish, and also the immune response was considerably reduced but remained elevated. A high degree of correlation was observed between immune genes and viral copy number in each of the sampled fish at 12 hpi. The quick and prolonged elevated expression of the immune genes indicates their crucial role in survival of host against SVCV. PMID:27263115

  20. Toll-Like Receptor (TLR) 2 and TLR9 Expressed in Trigeminal Ganglia are Critical to Viral Control During Herpes Simplex Virus 1 Infection

    PubMed Central

    Lima, Graciela Kunrath; Zolini, Guilherme Pimenta; Mansur, Daniel Santos; Freire Lima, Bráulio Henrique; Wischhoff, Uschi; Astigarraga, Ruiz Gerhardt; Dias, Marcela França; Silva, Mariana das Graças Almeida; Béla, Samantha Ribeiro; do Valle Antonelli, Lis Ribeiro; Arantes, Rosa Maria; Gazzinelli, Ricardo Tostes; Báfica, André; Kroon, Erna Geessien; Campos, Marco Antônio

    2010-01-01

    Herpes simplex virus 1 (HSV-1) is a neurotropic DNA virus that is responsible for several clinical manifestations in humans, including encephalitis. HSV-1 triggers toll-like receptors (TLRs), which elicit cytokine production. Viral multiplication and cytokine expression in C57BL/6 wild-type (WT) mice infected with HSV-1 were evaluated. Virus was found in the trigeminal ganglia (TG), but not in the brains of animals without signs of encephalitis, between 2 and 6 days postinfection (d.p.i.). Cytokine expression in the TG peaked at 5 d.p.i. TLR9−/− and TLR2/9−/− mice were more susceptible to the virus, with 60% and 100% mortality, respectively, as opposed to 10% in the WT and TLR2−/− mice. Increased levels of both CXCL10/IP-10 and CCL2/MCP-1, as well as reduced levels of interferon-γ and interleukin 1-β transcripts, measured in both the TG and brains at 5 d.p.i., and the presence of virus in the brain were correlated with total mortality in TLR2/9−/− mice. Cytokine alterations in TLR2/9−/− mice coincided with histopathological changes in their brains, which did not occur in WT and TLR2−/− mice and occurred only slightly in TLR9−/− mouse brain. Increased cellularity, macrophages, CD8 T cells producing interferon-γ, and expression levels of TLR2 and TLR9 were detected in the TG of WT-infected mice. We hypothesize that HSV-1 infection is controlled by TLR-dependent immune responses in the TG, which prevent HSV-1 encephalitis. PMID:20864677

  1. A species-specific activation of Toll-like receptor signaling in bovine and sheep bronchial epithelial cells triggered by Mycobacterial infections.

    PubMed

    Ma, Yan; Han, Fei; Liang, Jinping; Yang, Jiali; Shi, Juan; Xue, Jing; Yang, Li; Li, Yong; Luo, Meihui; Wang, Yujiong; Wei, Jun; Liu, Xiaoming

    2016-03-01

    Pulmonary tuberculosis caused by a Mycobacterium infection remains a major public health problem in most part of the world, in part owing to the transmission of its pathogens between hosts including human, domestic and wild animals. To date, molecular mechanisms of the pathogenesis of TB are still incompletely understood. In addition to alveolar macrophages, airway epithelial cells have also been recently recognized as main targets for Mycobacteria infections. In an effort to understand the pathogen-host interaction between Mycobacteria and airway epithelial cells in domestic animals, in present study, we investigated the Toll-like receptor (TLR) signaling in bovine and sheep airway epithelial cells in response to an infection of Mycobacterium tuberculosis avirulent H37Ra stain or Mycobacterium bovis BCG vaccine strain, using primary air-liquid interface (ALI) bronchial epithelial culture models. Our results revealed a host and pathogen species-specific TLR-mediated recognition of pathogen-associated molecular patterns (PAMPs), induction and activation of TLR signaling pathways, and substantial induction of inflammatory response in bronchial epithelial cells in response to Mycobacteria infections between these two species. Interestingly, the activation TLR signaling in bovine bronchial epithelial cells induced by Mycobacteria infection was mainly through a myeloid differentiation factor 88 (MyD88)-independent TLR signaling pathway, while both MyD88-dependent and independent TLR signaling cascades could be induced in sheep epithelial cells. Equally noteworthy, a BCG infection was able to induce both MyD88-dependent and independent signaling in sheep and bovine airway epithelial cells, but more robust inflammatory responses were induced in sheep epithelial cells relative to the bovines; whereas an H37Ra infection displayed an ability to mainly trigger a MyD88-independent TLR signaling cascade in these two host species, and induce a more extent expression of

  2. Intrahepatic Toll-Like Receptor 3 in Chronic HBV Infection Subjects: Asymptomatic Carriers, Active Chronic Hepatitis, Cirrhosis, and Hepatocellular Carcinoma

    PubMed Central

    Yin, Jia Wen; Ping Huang, Mao; Zhong, Bei

    2016-01-01

    Background The entire disease spectrum of chronic HBV infection (CHB) includes asymptomatic carriers (AC), active chronic hepatitis (ACH), cirrhosis (Cir), and hepatocellular carcinoma (HCC). Previous study have demonstrated that the costimulation profiles from the livers of patients influenced immune responses and played various immunological roles in AC, ACH, Cir, and HCC. In addition, activation of TLR3 signaling in the liver may contribute to HBV clearance, although some HBV components are able to block TLR3 signaling and counteract HBV clearance through positive or negative feedback loops. Previous clinical studies have demonstrated that different TLR3 expressions are present in ACH patients, but no studies investigated the expression of TLR3 proteins in the livers of patients with AC, Cir, or HCC. Objectives This study investigated intrahepatic TLR3 expression throughout the entire disease spectrum of CHB patients and assessed the interrelations between TLR3 and costimulation proteins. Patients and Methods Patients with ACH, Cir, HCC, and AC and healthy donors (HD) were recruited. TLR3 expression in the livers of patients were investigated using western blot analysis and immunohistochemistry. Correlations between TLR3 and costimulation proteins, including CD80, CD86, CD83, CD28, CTLA-4, CD40, and ICAM-1, were assessed. Results The TLR3 protein in the ACH group tended toward reduction although the P Value of the comparison between the ACH group and HD group was not statistically significant. The TLR3 levels in the HCC, AC, and Cir groups were higher than those in the HD and ACH groups. TLR3 was not interrelated with all costimulation proteins in the DCs and T cells in all five groups. No group presented any interrelation between TLR3 and CD40, except the AC group. Conclusions The AC, HCC, and Cir patients displayed increased levels of the intrahepatic TLR3 protein compared to the HD and AC patients. Both activation of TLR3/INF-β signaling and inhibition of

  3. Toll-like receptor 4 signaling pathway can be triggered by grass carp reovirus and Aeromonas hydrophila infection in rare minnow Gobiocypris rarus.

    PubMed

    Su, Jianguo; Yang, Chunrong; Xiong, Feng; Wang, Yaping; Zhu, Zuoyan

    2009-07-01

    Toll-like receptor 4 (TLR4) is critical for LPS recognition and cellular responses. It also recognizes some viral envelope proteins. Detection mostly results in the inflammation rather than specific antiviral responses. However, it's unclear in fish. In this report, a TLR4 gene (named as GrTLR4b) was cloned and characterized from rare minnow Gobiocypris rarus. The full length of GrTLR4b cDNA consists of 2766 nucleotides and encodes a polypeptide of 818 amino acids with an estimated molecular mass of 94,518Da and a predicted isoelectric point of 8.41. The predicted amino acid sequence comprises a signal peptide, six leucine-rich repeat (LRR) motifs, one leucine-rich repeat C-terminal (LRRCT) motif, followed by a transmembrane segment of 23 amino acids, and a cytoplasmic region of 167 amino acids containing one Toll--interleukin 1--receptor (TIR) motif. It's closely similar to the zebrafish (Danio rerio) TLR4b amino acid sequence with an identity of 77%. Quantitative RT-PCR analysis showed GrTLR4b mRNA was constitutive expression in gill, heart, intestine, kidney, liver, muscle and spleen tissues in healthy animals and up-regulated by viruses and bacteria. After being infected by grass carp reovirus or Aeromonas hydrophila, GrTLR4b expressions were up-regulated from 24h post-injection and lasted until the fish became moribund (P<0.05). These data implied that TLR4 signaling pathway could be activated by both viral and bacterial infection in rare minnow. PMID:19264133

  4. A Novel Mouse Model of Campylobacter jejuni Gastroenteritis Reveals Key Pro-inflammatory and Tissue Protective Roles for Toll-like Receptor Signaling during Infection

    PubMed Central

    Stahl, Martin; Yang, Hong; Sham, Ho Pan; Crowley, Shauna M.; Badayeva, Yuliya; Turvey, Stuart E.; Gaynor, Erin C.; Li, Xiaoxia; Vallance, Bruce A.

    2014-01-01

    Campylobacter jejuni is a major source of foodborne illness in the developed world, and a common cause of clinical gastroenteritis. Exactly how C. jejuni colonizes its host's intestines and causes disease is poorly understood. Although it causes severe diarrhea and gastroenteritis in humans, C. jejuni typically dwells as a commensal microbe within the intestines of most animals, including birds, where its colonization is asymptomatic. Pretreatment of C57BL/6 mice with the antibiotic vancomycin facilitated intestinal C. jejuni colonization, albeit with minimal pathology. In contrast, vancomycin pretreatment of mice deficient in SIGIRR (Sigirr−/−), a negative regulator of MyD88-dependent signaling led to heavy and widespread C. jejuni colonization, accompanied by severe gastroenteritis involving strongly elevated transcription of Th1/Th17 cytokines. C. jejuni heavily colonized the cecal and colonic crypts of Sigirr−/− mice, adhering to, as well as invading intestinal epithelial cells. This infectivity was dependent on established C. jejuni pathogenicity factors, capsular polysaccharides (kpsM) and motility/flagella (flaA). We also explored the basis for the inflammatory response elicited by C. jejuni in Sigirr−/− mice, focusing on the roles played by Toll-like receptors (TLR) 2 and 4, as these innate receptors were strongly stimulated by C. jejuni. Despite heavy colonization, Tlr4−/−/Sigirr−/− mice were largely unresponsive to infection by C. jejuni, whereas Tlr2−/−/Sigirr−/− mice developed exaggerated inflammation and pathology. This indicates that TLR4 signaling underlies the majority of the enteritis seen in this model, whereas TLR2 signaling had a protective role, acting to promote mucosal integrity. Furthermore, we found that loss of the C. jejuni capsule led to increased TLR4 activation and exaggerated inflammation and gastroenteritis. Together, these results validate the use of Sigirr−/− mice as an exciting and relevant animal

  5. Susceptibility to paratuberculosis infection in cattle is associated with single nucleotide polymorphisms in Toll-like receptor 2 which modulate immune responses against Mycobacterium avium subspecies paratuberculosis.

    PubMed

    Koets, A; Santema, W; Mertens, H; Oostenrijk, D; Keestra, M; Overdijk, M; Labouriau, R; Franken, P; Frijters, A; Nielen, M; Rutten, V

    2010-03-01

    Paratuberculosis is a chronic intestinal infection in ruminants, caused by Mycobacterium avium subspecies paratuberculosis (Map). To study the role of host genetics in disease susceptibility, the Toll-like receptor 2 (TLR2) gene, selected based on its potential role in immunity to mycobacterial infections, was analyzed for single nucleotide polymorphisms (SNP) and their potential association with disease. For SNP discovery and to study SNP association with disease, a case-control study including 24 cows from farms with paratuberculosis was conducted. Sequence analysis of the TLR2 genes from 12 paratuberculosis-infected animals and 12 age-matched healthy herd mates revealed 21 different SNP. The TLR2-1903 T/C SNP was significantly associated with resistance to Map. This and four additional TLR2 SNP were studied in a subsequent observational field study with 553 cows from farms with paratuberculosis. The allelic distribution of the TLR2-1903 T/C SNP was confirmed to be significantly different between the infected and non-infected animals. For the TLR2-1903 T/C SNP the odds ratio was calculated, and similar to the dominance model in the association study, the CT and CC genotypes were compared to the TT genotype. Cows with the TLR2-1903 T/C mutation (i.e., the CT and CC genotypes) were at 1.7 (95% CI: 1.2, 2.8) times the odds of being Map-infected compared to cows with the TT genotype. In in vitro functional assays, monocyte-derived macrophages from animals with a TLR2-1903 TT genotype produced more IL12p40 and IL1beta when stimulated with Map compared to cells derived from TLR2-1903 CT and CC genotypes. Also, T cell proliferative responses to mycobacterial antigens were higher in animals with a TLR2-1903 TT genotype. In conclusion, we have found a significant association between SNP TLR2-1903 T/C in the bovine TLR2 gene and bovine paratuberculosis infection. This SNP and other genetic markers could be useful in marker-assisted breeding strategies as an additional tool

  6. Hepatic and Renal Cytochrome P450 Gene Regulation During Citrobacter rodentium Infection in Wildtype and Toll-like Receptor 4 Mutant Mice

    PubMed Central

    Richardson, Terrilyn A.; Sherman, Melanie; Antonovic, Leposava; Kardar, Sean S.; Strobel, Henry W.; Kalman, Daniel; Morgan, Edward T.

    2005-01-01

    C. rodentium is the rodent equivalent of human enteropathogenic E. coli infection. This study investigated regulation of hepatic and renal cytochrome P450 (P450) mRNAs, hepatic P450 proteins, cytokines and acute phase proteins during C. rodentium infection. Female C3H/HeOuJ (HeOu) and C3H/HeJ (HeJ) mice (which lack functional toll-like receptor 4 [TLR4]) were infected with C. rodentium by oral gavage, and sacrificed 6 days later. Hepatic CYP4A10 and 4A14 mRNAs were decreased in HeOu mice (<4% of control). CYP3A11, 2C29, 4F14, and 4F15 mRNAs were reduced to 16–55% of control levels, whereas CYP2A5, 4F16, and 4F18 mRNAs were induced (180, 190, and 600% of control, respectively). The pattern of P450 regulation in HeJ mice was similar to that in HeOu mice for most P450s, with the exception of the TLR4-dependence of CYP4F15. Hepatic CYP2C, 3A, and 4A proteins in both groups were decreased, whereas CYP2E protein was not. Renal CYP4A10 and 4A14 mRNAs were significantly down-regulated in HeOu mice, whereas other P450s were unaffected. Most renal P450 mRNAs in infected HeJ mice were increased, notably CYP4A10, 4A14, 4F18, 2A5 and 3A13. Hepatic levels of IL-1β, IL-6, and TNFα mRNAs were significantly increased in infected HeOu mice, whereas only TNFα mRNA was significantly increased in HeJ mice. Hepatic α1-acid glycoprotein was induced in both groups, whereas α-fibrinogen and angiotensinogen were unchanged. These data indicate that hepatic inflammation induced by C. rodentium infection is mainly TLR4-independent, and suggest that hepatic P450 down-regulation in this model may be cytokine-mediated. PMID:16339354

  7. FSL-1, a bacterial-derived toll-like receptor 2/6 agonist, enhances resistance to experimental HSV-2 infection

    PubMed Central

    2009-01-01

    Background Herpes simplex virus type 2 (HSV-2) is a leading cause of genital ulceration that can predispose individuals to an increased risk of acquiring other sexually transmitted infections. There are no approved HSV-2 vaccines and current suppressive therapies require daily compound administration that does not prevent all recurrences. A promising experimental strategy is the use of toll-like receptor (TLR) agonists to induce an innate immune response that provides resistance to HSV-2 infection. Previous studies showed that anti-herpetic activity varied based on origin of the agonists and activation of different TLR indicating that activity likely occurs through elaboration of a specific innate immune response. To test the hypothesis, we evaluated the ability of a bacterial-derived TLR2/6 agonist (FSL-1) to increase resistance to experimental genital HSV-2 infection. Methods Vaginal application of FSL-1 at selected doses and times was evaluated to identify potential increased resistance to genital HSV-2 infection in the mouse model. The FSL-1 induced cytokine profile was quantified using kinetically collected vaginal lavages. Additionally, cytokine elaboration and organ weights were evaluated after single or multiple FSL-1 doses to establish a preliminary safety profile. Human vaginal EC cultures were used to confirm the mouse model outcomes. Results The results showed that vaginally-applied FSL-1 created an environment resistant to a 25-fold higher HSV-2 challenge dose. Mechanistically, vaginal FSL-1 application led to transient elaboration of cytokines linked to anti-herpetic innate immune responses. No gross local or peripheral immunotoxicity was observed even after multiple dosing. FSL-1 also created an anti-herpetic environment in cultures of human vaginal epithelial cells (EC). Conclusion The results showed, for the first time, that the bacterial-derived TLR2/6 agonist FSL-1 induced significant resistance to HSV-2 infection when applied in mice or human

  8. Increased expression of Toll-like receptors 7 and 9 in myasthenia gravis thymus characterized by active Epstein-Barr virus infection.

    PubMed

    Cavalcante, Paola; Galbardi, Barbara; Franzi, Sara; Marcuzzo, Stefania; Barzago, Claudia; Bonanno, Silvia; Camera, Giorgia; Maggi, Lorenzo; Kapetis, Dimos; Andreetta, Francesca; Biasiucci, Amelia; Motta, Teresio; Giardina, Carmelo; Antozzi, Carlo; Baggi, Fulvio; Mantegazza, Renato; Bernasconi, Pia

    2016-04-01

    Considerable data implicate the thymus as the main site of autosensitization to the acetylcholine receptor in myasthenia gravis (MG), a B-cell-mediated autoimmune disease affecting the neuromuscular junction. We recently demonstrated an active Epstein-Barr virus (EBV) infection in the thymus of MG patients, suggesting that EBV might contribute to the onset or maintenance of the autoimmune response within MG thymus, because of its ability to activate and immortalize autoreactive B cells. EBV has been reported to elicit and modulate Toll-like receptor (TLR) 7- and TLR9-mediated innate immune responses, which are known to favor B-cell dysfunction and autoimmunity. Aim of this study was to investigate whether EBV infection is associated with altered expression of TLR7 and TLR9 in MG thymus. By real-time PCR, we found that TLR7 and TLR9 mRNA levels were significantly higher in EBV-positive MG compared to EBV-negative normal thymuses. By confocal microscopy, high expression levels of TLR7 and TLR9 proteins were observed in B cells and plasma cells of MG thymic germinal centers (GCs) and lymphoid infiltrates, where the two receptors co-localized with EBV antigens. An increased frequency of Ki67-positive proliferating B cells was found in MG thymuses, where we also detected proliferating cells expressing TLR7, TLR9 and EBV antigens, thus supporting the idea that EBV-associated TLR7/9 signaling may promote abnormal B-cell activation and proliferation. Along with B cells and plasma cells, thymic epithelium, plasmacytoid dendritic cells and macrophages exhibited enhanced TLR7 and TLR9 expression in MG thymus; TLR7 was also increased in thymic myeloid dendritic cells and its transcriptional levels positively correlated with those of interferon (IFN)-β. We suggested that TLR7/9 signaling may be involved in antiviral type I IFN production and long-term inflammation in EBV-infected MG thymuses. Our overall findings indicate that EBV-driven TLR7- and TLR9-mediated innate immune

  9. Toll-like Receptor 3 Is Required for Development of Retinopathy Caused by Impaired All-trans-retinal Clearance in Mice*

    PubMed Central

    Shiose, Satomi; Chen, Yu; Okano, Kiichiro; Roy, Sanhita; Kohno, Hideo; Tang, Johnny; Pearlman, Eric; Maeda, Tadao; Palczewski, Krzysztof; Maeda, Akiko

    2011-01-01

    Chronic inflammation is an important component that contributes to many age-related neurodegenerative diseases, including macular degeneration. Here, we report a role for toll-like receptor 3 (TLR3) in cone-rod dystrophy (CORD) of mice lacking ATP-binding cassette transporter 4 (ABCA4) and retinol dehydrogenase 8 (RDH8), proteins critical for all-trans-retinal clearance in the retina. Increased expression of toll-like receptor-signaling elements and inflammatory changes were observed in Rdh8−/−Abca4−/− eyes by RNA expression analysis. Unlike 3-month-old Rdh8−/−Abca4−/− mice that developed CORD, 6-month-old Tlr3−/−Rdh8−/−Abca4−/− mice did not evidence an abnormal retinal phenotype. Light-induced retinal degeneration in Tlr3−/−Rdh8−/−Abca4−/− mice was milder than that in Rdh8−/−Abca4−/− mice, and a 2-fold increased TLR3 expression was detected in light-illuminated retinas of Rdh8−/−Abca4−/− mice compared with nonilluminated retinas. Poly(I-C), a TLR3 ligand, caused caspase-8-independent cellular apoptosis. Whereas poly(I-C) induced retinal cell death in Rdh8−/−Abca4−/− and WT mice both in vivo and ex vivo, this was not seen in mice lacking Tlr3. Far fewer invasive macrophage/microglial cells in the subretinal space and weaker activation of Muller glial cells were exhibited by Tlr3−/−Rdh8−/− Abca4−/− mice compared with Rdh8−/−Abca4−/− mice at 3 and 6 months of age, indicating that loss of TLR3 inhibits local inflammation in the retina. Both poly(I-C) and endogenous products emanating from dying/dead retinal cells induced NF-κB and IRF3 activation. These findings demonstrate that endogenous products from degenerating retina stimulate TLR3 that causes cellular apoptosis and retinal inflammation and that loss of TLR3 protects mice from CORD. PMID:21383019

  10. Toll-like Receptor function of murine macrophages, probed by cytokine induction, is biphasic and is not impaired globally with age.

    PubMed

    Pattabiraman, Goutham; Palasiewicz, Karol; Ucker, David S

    2016-07-01

    Aging is associated with a waning of normal immune function. This "immunosenescence" is characterized by a diverse repertoire of seemingly discreet and unbalanced immune alterations. A number of studies have suggested that aging-associated alterations in innate immune responsiveness, especially responsiveness dependent on Toll-like Receptor (TLR) engagement, are causally involved. We find, however, that the magnitude and dose-dependency of responsiveness to TLR engagement (assessed with respect to cytokine production) in distinct populations of murine macrophages are not altered generally with animal age or as a consequence of immunosenescence. Responses elicited with a wide array of TLR agonists were examined by extensive functional analyses, principally on the level of the individual cell. These studies reveal an intriguing "all-or-nothing" response behavior of macrophages, independent of animal age. Although reports to the contrary have been cited widely, aging-associated immune decline cannot be attributed to widespread alterations in the extents of TLR-dependent innate immune macrophage responses. PMID:27453067

  11. Toll-Like Receptors in Chronic Pain

    PubMed Central

    Nicotra, Lauren; Loram, Lisa C; Watkins, Linda R; Hutchinson, Mark R

    2011-01-01

    Proinflammatory central immune signaling contributes significantly to the initiation and maintenance of heightened pain states. Recent discoveries have implicated the innate immune system, pattern recognition Toll-like receptors in triggering these proinflammatory central immune signaling events. These exciting developments have been complemented by the discovery of neuronal expression of Toll-like receptors, suggesting pain pathways can be activated directly by the detection of pathogen associated molecular patterns or danger associated molecular patterns. This review will examine the evidence to date implicating Toll-like receptors and their associated signaling components in heightened pain states. In addition, insights into the impact Toll-like receptors have on priming central immune signaling systems for heightened pain states will be discussed. The influence possible sex differences in Toll-like receptor signaling have for female pain and the recognition of small molecule xenobiotics by Toll-like receptors will also be reviewed. PMID:22001158

  12. Mycobacterial signaling through toll-like receptors

    PubMed Central

    Basu, Joyoti; Shin, Dong-Min; Jo, Eun-Kyeong

    2012-01-01

    Studies over the past decade have helped to decipher molecular networks dependent on Toll-like receptor (TLR) signaling, in mycobacteria-infected macrophages. Stimulation of TLRs by mycobacteria and their antigenic components rapidly induces intracellular signaling cascades involved in the activation of nuclear factor-κB and mitogen-activated protein kinase pathways, which play important roles in orchestrating proinflammatory responses and innate defense through generation of a variety of antimicrobial effector molecules. Recent studies have provided evidence that mycobacterial TLR-signaling cross talks with other intracellular antimicrobial innate pathways, the autophagy process and functional vitamin D receptor (VDR) signaling. In this article we describe recent advances in the recognition, responses, and regulation of mycobacterial signaling through TLRs. PMID:23189273

  13. Toll-Like Receptor Adaptor MyD88 is Essential for Pathogen Control During Oral Toxoplasma gondii Infection but not Adaptive Immunity Induced by a Vaccine Strain of the Parasite1

    PubMed Central

    Sukhumavasi, Woraporn; Egan, Charlotte E.; Warren, Amy L.; Taylor, Gregory A.; Fox, Barbara A.; Bzik, David J.; Denkers, Eric Y.

    2008-01-01

    Toll-like receptor (TLR)/MyD88 activation is important in host resistance to Toxoplasma gondii during i. p. infection, but the function of this signaling pathway during oral infection, in which mucosal immunity assumes a predominant role, has not been examined. Here, we show that MyD88−/− mice fail to control the parasite and succumb within two weeks of oral infection. Early during infection, T cell IFN-γ production, recruitment of neutrophils and induction of p47 GTPase Irgm3/IGTP in the intestinal mucosa were dependent upon functional MyD88. Unexpectedly, these responses were MyD88-independent later during acute infection. In particular, CD4+ T cell IFN-γ reached normal levels independently of MyD88, despite continued absence of IL-12 in these animals. Intraperitoneal vaccination of MyD88−/− mice with an avirulent T. gondii uracil axotroph elicited robust IFN-γ responses and protective immunity to challenge with a high virulence T. gondii strain. Our results demonstrate that MyD88 is required to control Toxoplasma infection, but that the parasite can trigger adaptive immunity without the need for this TLR adaptor molecule. PMID:18714019

  14. Molecular cloning of Salmo salar Toll-like receptors (TLR1, TLR22, TLR5M and TLR5S) and expression analysis in SHK-1 cells during Piscirickettsia salmonis infection.

    PubMed

    Salazar, C; Haussmann, D; Kausel, G; Figueroa, J

    2016-02-01

    In fish, the innate immune system is the primary response against infection. Toll-like receptors (TLRs) recognize pathogens through pathogen-associated molecular patterns (PAMPs), and some target molecules of TLRs are homologous between fish and mammals. Piscirickettsia salmonis is one of the main pathogens affecting the salmon industry in Chile. Better knowledge of mechanisms underlying its invasive capacity and recognition of target cells is crucial for vaccine development. Therefore, Salmo salar L. TLR1, TLR22, membrane TLR5M and soluble TLR5S sequences were cloned, and expression kinetics were analysed by RT-qPCR in salmon head kidney cells (SHK-1) infected with three different P. salmonis preparations: alive, formaldehyde treated, extract. Clearly, all analysed TLRs were expressed and transcription level changes were revealed at 2 hpi, 12 or 16 hpi and 24 hpi depending on P. salmonis infection scheme. Increased IL1-beta expression confirmed TLR pathway response. Furthermore, significant expression modulations of several members of the TLR pathway in this in vitro model suggest that P. salmonis extract rather than formaldehyde-inactivated bacteria might strengthen the salmon immune system. PMID:25903926

  15. A role for Toll-like receptor 4 in the host response to the lung infection of Yersinia pseudotuberculosis in mice.

    PubMed

    Choi, Jin-A; Jeong, Yu-Jin; Kim, Jae-Eun; Kang, Min-Jung; Kim, Jee-Cheon; Oh, Sang-Muk; Lee, Kyung-Bok; Kim, Dong-Hyun; Kim, Dong-Jae; Park, Jong-Hwan

    2016-02-01

    Although a Yersinia pseudotuberculosis (Yptb) lung infection model has been developed to study Y. pestis pathogenesis, it is still necessary to establish a new animal model to mimic the pathophysiological features induced by Y. pestis infection. Here, we provide a new lung infection model using the Yptb strain, IP2777, which displayed rapid spread of bacteria to the liver, spleen, and blood. In addition, we examined whether TLR4 is involved in Yptb-induced pathogenesis in the lung infection model of mice we generated. Following lung infection of WT and TLR4-deficient mice with the Yptb strain IP2777, the survival rate, bacterial colonization, histopathology, and level of cytokines and chemokines in the lung, spleen, liver, and blood were analyzed. TLR4-deficient mice had a lower survival rate than WT mice in response to Yptb lung infection. Although the bacterial colonization and pathology of the lung were comparable between WT and TLR4-deficient mice, those of the spleen and liver were more severe in TLR4-deficient mice. In addition, the levels of TNF-α and CXCL2 in the liver and IL-6 and CXCL2 in the blood were higher in TLR4-deficient mice than in WT mice. Our results demonstrate that TLR4 is necessary for optimal host protection against Yptb lung infection and TLR4-deficient mice may serve as a better genetic model of Yptb infection for mimicking Y. pestis infection. PMID:26851596

  16. Role of Toll-like receptors in lung innate defense against invasive aspergillosis. Distinct impact in immunocompetent and immunocompromized hosts.

    PubMed

    Chignard, Michel; Balloy, Viviane; Sallenave, Jean-Michel; Si-Tahar, Mustapha

    2007-09-01

    Toll-like receptors are key to pathogen recognition by a host and to the subsequent triggering of an innate immune response. Experimental and clinical evidence shows that defects in Toll-like receptors or in signaling pathways downstream from these receptors render hosts susceptible to various types of infection, including aspergillosis. Patients receiving an immunosuppressive regimen, including corticosteroid therapy or cytotoxic chemotherapy, are also susceptible to infections. Aspergillus fumigatus is an opportunistic pathogen that infects the lungs of immunosuppressed hosts. Here, we review the evidence that experimental inactivation of various Toll-like receptors and of their signaling pathways may worsen cases of invasive pulmonary aspergillosis. Moreover, the literature clearly indicates that the type of immunosuppression is very important, as it influences whether or not Toll-like receptors contribute to infection. The involvement of Toll-like receptors, based on the immunological status of the patient, should be considered if an immunosuppressive treatment must be administered. PMID:17604224

  17. Analysis of Genes Induced by Sendai Virus Infection of Mutant Cell Lines Reveals Essential Roles of Interferon Regulatory Factor 3, NF-κB, and Interferon but Not Toll-Like Receptor 3†

    PubMed Central

    Elco, Christopher P.; Guenther, Jeanna M.; Williams, Bryan R. G.; Sen, Ganes C.

    2005-01-01

    Sendai virus (SeV) infection causes the transcriptional induction of many cellular genes that are also induced by interferon (IFN) or double-stranded RNA (dsRNA). We took advantage of various mutant cell lines to investigate the putative roles of the components of the IFN and dsRNA signaling pathways in the induction of those genes by SeV. Profiling the patterns of gene expression in SeV-infected cells demonstrated that Toll-like receptor 3, although essential for gene induction by dsRNA, was dispensable for gene induction by SeV. In contrast, Jak1, which mediates IFN signaling, was required for the induction of a small subset of genes by SeV. NF-κB and interferon regulatory factor 3 (IRF-3), the two major transcription factors activated by virus infection, were essential for the induction of two sets of genes by SeV. As expected, some of the IRF-3-dependent genes, such as ISG56, were more strongly induced by SeV in IRF-3-overexpressing cells. Surprisingly, in those cells, a number of NF-κB-dependent genes, such as the A20 gene, were induced poorly. Using a series of cell lines expressing increasing levels of IRF-3, we demonstrated that the degree of induction of A20 mRNA, upon SeV infection, was inversely proportional to the cellular level of IRF-3, whereas that of ISG56 mRNA was directly proportional. Thus, IRF-3 can suppress the expression of NF-κB-dependent genes in SeV-infected cells. PMID:15767394

  18. Toll-Like Receptor 2-Dependent Extracellular Signal-Regulated Kinase Signaling in Mycobacterium tuberculosis-Infected Macrophages Drives Anti-Inflammatory Responses and Inhibits Th1 Polarization of Responding T Cells

    PubMed Central

    Richardson, Edward T.; Shukla, Supriya; Sweet, David R.; Wearsch, Pamela A.; Tsichlis, Philip N.; Boom, W. Henry

    2015-01-01

    Mycobacterium tuberculosis survives within macrophages and employs immune evasion mechanisms to persist in the host. Protective T helper type 1 (Th1) responses are induced, and the immune response in most individuals is sufficient to restrict M. tuberculosis to latent infection, but most infections are not completely resolved. As T cells and macrophages respond, a balance is established between protective Th1-associated and other proinflammatory cytokines, such as interleukin-12 (IL-12), interferon gamma (IFN-γ), and tumor necrosis factor alpha, and anti-inflammatory cytokines, such as IL-10. The mechanisms by which M. tuberculosis modulates host responses to promote its survival remain unclear. In these studies, we demonstrate that M. tuberculosis induction of IL-10, suppression of IL-12, and inhibition of class II major histocompatibility complex (MHC-II) molecules in infected macrophages are all driven by Toll-like receptor 2 (TLR2)-dependent activation of the extracellular signal-regulated kinases (ERK). Elimination of ERK signaling downstream of TLR2 by pharmacologic inhibition with U0126 or genetic deletion of Tpl2 blocks IL-10 secretion and enhances IL-12 p70 secretion. We demonstrate that M. tuberculosis regulation of these pathways in macrophages affects T cell responses to infected macrophages. Thus, genetic blockade of the ERK pathway in Tpl2−/− macrophages enhances Th1 polarization and IFN-γ production by antigen-specific CD4+ T cells responding to M. tuberculosis infection. These data indicate that M. tuberculosis and its potent TLR2 ligands activate ERK signaling in macrophages to promote anti-inflammatory macrophage responses and blunt Th1 responses against the pathogen. PMID:25776754

  19. Key Role of Toll-Like Receptor 2 in the Inflammatory Response and Major Histocompatibility Complex Class II Downregulation in Brucella abortus-Infected Alveolar Macrophages

    PubMed Central

    Ferrero, Mariana C.; Hielpos, M. Soledad; Carvalho, Natalia B.; Barrionuevo, Paula; Corsetti, Patricia P.; Giambartolomei, Guillermo H.; Oliveira, Sergio C.

    2014-01-01

    Alveolar macrophages (AM) seem to constitute the main cellular target of inhaled brucellae. Here, we show that Brucella abortus invades and replicates in murine AM without inducing cytotoxicity. B. abortus infection induced a statistically significant increase of tumor necrosis factor alpha (TNF-α), CXCL1 or keratinocyte chemoattractant (KC), interleukin-1β (IL-1β), IL-6, and IL-12 in AM from C57BL/6 mice and BALB/c mice, but these responses were generally weaker and/or delayed compared to those elicited in peritoneal macrophages. Studies using knockout mice for TLR2, TLR4, and TLR9 revealed that TNF-α and KC responses were mediated by TLR2 recognition. Brucella infection reduced in a multiplicity of infection-dependent manner the expression of major histocompatibility complex class II (MHC-II) molecules induced by gamma interferon (IFN-γ) in AM. The same phenomenon was induced by incubation with heat-killed B. abortus (HKBA) or the lipidated form of the 19-kDa outer membrane protein of Brucella (L-Omp19), and it was shown to be mediated by TLR2 recognition. In contrast, no significant downregulation of MHC-II was induced by either unlipidated Omp19 or Brucella LPS. In a functional assay, treatment of AM with either L-Omp19 or HKBA reduced the MHC-II-restricted presentation of OVA peptides to specific T cells. One week after intratracheal infection, viable B. abortus was detected in AM from both wild-type and TLR2 KO mice, but CFU counts were higher in the latter. These results suggest that B. abortus survives in AM after inhalatory infection in spite of a certain degree of immune control exerted by the TLR2-mediated inflammatory response. Both the modest nature of the latter and the modulation of MHC-II expression by the bacterium may contribute to such survival. PMID:24478078

  20. Aeromonas salmonicida Infection Only Moderately Regulates Expression of Factors Contributing to Toll-Like Receptor Signaling but Massively Activates the Cellular and Humoral Branches of Innate Immunity in Rainbow Trout (Oncorhynchus mykiss).

    PubMed

    Brietzke, Andreas; Korytář, Tomáš; Jaros, Joanna; Köllner, Bernd; Goldammer, Tom; Seyfert, Hans-Martin; Rebl, Alexander

    2015-01-01

    Toll-like receptors (TLRs) are known to detect a defined spectrum of microbial structures. However, the knowledge about the specificity of teleost Tlr factors for distinct pathogens is limited so far. We measured baseline expression profiles of 18 tlr genes and associated signaling factors in four immune-relevant tissues of rainbow trout Oncorhynchus mykiss. Intraperitoneal injection of a lethal dose of Aeromonas salmonicida subsp. salmonicida induced highly increased levels of cytokine mRNAs during a 72-hour postinfection (hpi) period. In contrast, only the fish-specific tlr22a2 and the downstream factor irak1 featured clearly increased transcript levels, while the mRNA concentrations of many other tlr genes decreased. Flow cytometry quantified cell trafficking after infection indicating a dramatic influx of myeloid cells into the peritoneum and a belated low level immigration of lymphoid cells. T and B lymphocytes were differentiated with RT-qPCR revealing that B lymphocytes emigrated from and T lymphocytes immigrated into head kidney. In conclusion, no specific TLR can be singled out as a dominant receptor for A. salmonicida. The recruitment of cellular factors of innate immunity rather than induced expression of pathogen receptors is hence of key importance for mounting a first immune defense against invading A. salmonicida. PMID:26266270

  1. Molecular cloning and comparative responses of Toll-like receptor 22 following ligands stimulation and parasitic infection in yellowtail (Seriola lalandi).

    PubMed

    Reyes-Becerril, Martha; Ascencio-Valle, Felipe; Alamillo, Erika; Hirono, Ikuo; Kondo, Hidehiro; Jirapongpairoj, Walissara; Angulo, Carlos

    2015-10-01

    TLR22 is exclusively present in teleosts and amphibians and is expected to play the distinctive role in innate immunity. In this study, we cloned the full-length cDNA sequence of yellowtail (Seriola lalandi) TLR22 (SlTLR22). The complete cDNA sequence of SlTLR22 was 4208 bp and encodes a polypeptide of 961 amino acids. Analysis of the deduced amino acid sequence indicated that SlTLR22 has typical structural features of proteins belonging to the TLR family. These included 17 LRR domains (residues 91-633) and one C-terminal LRR domain (LRR-CT, residues 693-744) in the extracellular region, and a TIR domain (residues 800-943) in the cytoplasmic region. Comparison with homologous proteins showed that the deduced SlTLR22 has the highest sequence identity to turbot TLR22 (76%). Quantitative real-time PCR (qPCR) analysis demonstrated the constitutive expression of SlTLR22 mRNA in all examined tissues with higher levels in the head kidney, intestine, skin and spleen. Further, SlTLR22 expression was significantly up-regulated following TLR ligands injection with lipopolysaccharide (LPS), CpG ODN2006 and polyinosinic: polycytidylic acid (poly I:C) in spleen and liver. Amyloodinium ocellatum infection also induced a high expression of SlTLR22 in spleen, intestine, muscle, skin and gill, with maximum increases ranging from 1000 to 100 fold upon different ligands and organs. Finally, histological examination in gill tissue confirmed infection by the parasite and histopathological lesion was observed also in spleen and skin. These findings suggest a possible role of SlTLR22 in the immune responses to the infections of a broad range of pathogens that include DNA and RNA viruses and parasites. PMID:26102460

  2. Transcription of Toll-Like Receptors 2, 3, 4 and 9, FoxP3 and Th17 Cytokines in a Susceptible Experimental Model of Canine Leishmania infantum Infection

    PubMed Central

    Hosein, Shazia; Rodríguez-Cortés, Alhelí; Blake, Damer P.; Allenspach, Karin; Alberola, Jordi; Solano-Gallego, Laia

    2015-01-01

    Canine leishmaniosis (CanL) due to Leishmania infantum is a chronic zoonotic systemic disease resulting from complex interactions between protozoa and the canine immune system. Toll-like receptors (TLRs) are essential components of the innate immune system and facilitate the early detection of many infections. However, the role of TLRs in CanL remains unknown and information describing TLR transcription during infection is extremely scarce. The aim of this research project was to investigate the impact of L. infantum infection on canine TLR transcription using a susceptible model. The objectives of this study were to evaluate transcription of TLRs 2, 3, 4 and 9 by means of quantitative reverse transcription polymerase chain reaction (qRT-PCR) in skin, spleen, lymph node and liver in the presence or absence of experimental L. infantum infection in Beagle dogs. These findings were compared with clinical and serological data, parasite densities in infected tissues and transcription of IL-17, IL-22 and FoxP3 in different tissues in non-infected dogs (n = 10), and at six months (n = 24) and 15 months (n = 7) post infection. Results revealed significant down regulation of transcription with disease progression in lymph node samples for TLR3, TLR4, TLR9, IL-17, IL-22 and FoxP3. In spleen samples, significant down regulation of transcription was seen in TLR4 and IL-22 when both infected groups were compared with controls. In liver samples, down regulation of transcription was evident with disease progression for IL-22. In the skin, upregulation was seen only for TLR9 and FoxP3 in the early stages of infection. Subtle changes or down regulation in TLR transcription, Th17 cytokines and FoxP3 are indicative of the silent establishment of infection that Leishmania is renowned for. These observations provide new insights about TLR transcription, Th17 cytokines and Foxp3 in the liver, spleen, lymph node and skin in CanL and highlight possible markers of disease susceptibility in

  3. De Novo Transcriptome Analysis Shows That SAV-3 Infection Upregulates Pattern Recognition Receptors of the Endosomal Toll-Like and RIG-I-Like Receptor Signaling Pathways in Macrophage/Dendritic Like TO-Cells

    PubMed Central

    Xu, Cheng; Evensen, Øystein; Mweemba, Hetron Munang’andu

    2016-01-01

    A fundamental step in cellular defense mechanisms is the recognition of “danger signals” made of conserved pathogen associated molecular patterns (PAMPs) expressed by invading pathogens, by host cell germ line coded pattern recognition receptors (PRRs). In this study, we used RNA-seq and the Kyoto encyclopedia of genes and genomes (KEGG) to identify PRRs together with the network pathway of differentially expressed genes (DEGs) that recognize salmonid alphavirus subtype 3 (SAV-3) infection in macrophage/dendritic like TO-cells derived from Atlantic salmon (Salmo salar L) headkidney leukocytes. Our findings show that recognition of SAV-3 in TO-cells was restricted to endosomal Toll-like receptors (TLRs) 3 and 8 together with RIG-I-like receptors (RLRs) and not the nucleotide-binding oligomerization domain-like receptors NOD-like receptor (NLRs) genes. Among the RLRs, upregulated genes included the retinoic acid inducible gene I (RIG-I), melanoma differentiation association 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2). The study points to possible involvement of the tripartite motif containing 25 (TRIM25) and mitochondrial antiviral signaling protein (MAVS) in modulating RIG-I signaling being the first report that links these genes to the RLR pathway in SAV-3 infection in TO-cells. Downstream signaling suggests that both the TLR and RLR pathways use interferon (IFN) regulatory factors (IRFs) 3 and 7 to produce IFN-a2. The validity of RNA-seq data generated in this study was confirmed by quantitative real time qRT-PCR showing that genes up- or downregulated by RNA-seq were also up- or downregulated by RT-PCR. Overall, this study shows that de novo transcriptome assembly identify key receptors of the TLR and RLR sensors engaged in host pathogen interaction at cellular level. We envisage that data presented here can open a road map for future intervention strategies in SAV infection of salmon. PMID:27110808

  4. De Novo Transcriptome Analysis Shows That SAV-3 Infection Upregulates Pattern Recognition Receptors of the Endosomal Toll-Like and RIG-I-Like Receptor Signaling Pathways in Macrophage/Dendritic Like TO-Cells.

    PubMed

    Xu, Cheng; Evensen, Øystein; Mweemba Munang'andu, Hetron

    2016-01-01

    A fundamental step in cellular defense mechanisms is the recognition of "danger signals" made of conserved pathogen associated molecular patterns (PAMPs) expressed by invading pathogens, by host cell germ line coded pattern recognition receptors (PRRs). In this study, we used RNA-seq and the Kyoto encyclopedia of genes and genomes (KEGG) to identify PRRs together with the network pathway of differentially expressed genes (DEGs) that recognize salmonid alphavirus subtype 3 (SAV-3) infection in macrophage/dendritic like TO-cells derived from Atlantic salmon (Salmo salar L) headkidney leukocytes. Our findings show that recognition of SAV-3 in TO-cells was restricted to endosomal Toll-like receptors (TLRs) 3 and 8 together with RIG-I-like receptors (RLRs) and not the nucleotide-binding oligomerization domain-like receptors NOD-like receptor (NLRs) genes. Among the RLRs, upregulated genes included the retinoic acid inducible gene I (RIG-I), melanoma differentiation association 5 (MDA5) and laboratory of genetics and physiology 2 (LGP2). The study points to possible involvement of the tripartite motif containing 25 (TRIM25) and mitochondrial antiviral signaling protein (MAVS) in modulating RIG-I signaling being the first report that links these genes to the RLR pathway in SAV-3 infection in TO-cells. Downstream signaling suggests that both the TLR and RLR pathways use interferon (IFN) regulatory factors (IRFs) 3 and 7 to produce IFN-a2. The validity of RNA-seq data generated in this study was confirmed by quantitative real time qRT-PCR showing that genes up- or downregulated by RNA-seq were also up- or downregulated by RT-PCR. Overall, this study shows that de novo transcriptome assembly identify key receptors of the TLR and RLR sensors engaged in host pathogen interaction at cellular level. We envisage that data presented here can open a road map for future intervention strategies in SAV infection of salmon. PMID:27110808

  5. Toll-Like Receptor 2-Mediated Innate Immune Responses against Junín Virus in Mice Lead to Antiviral Adaptive Immune Responses during Systemic Infection and Do Not Affect Viral Replication in the Brain

    PubMed Central

    Cuevas, Christian D.

    2014-01-01

    ABSTRACT Successful adaptive immunity to virus infection often depends on the initial innate response. Previously, we demonstrated that Junín virus, the etiological agent responsible for Argentine hemorrhagic fever (AHF), activates an early innate immune response via an interaction between the viral glycoprotein and Toll-like receptor 2 (TLR2). Here we show that TLR2/6 but not TLR1/2 heterodimers sense Junín virus glycoprotein and induce a cytokine response, which in turn upregulates the expression of the RNA helicases RIG-I and MDA5. NF-κB and Erk1/2 were important in the cytokine response, since both proteins were phosphorylated as a result of the interaction of virus with TLR2, and treatment with an Erk1/2-specific inhibitor blocked cytokine production. We show that the Junín virus glycoprotein activates cytokine production in a human macrophage cell line as well. Moreover, we show that TLR2-mediated immune response plays a role in viral clearance because wild-type mice cleared Candid 1 (JUNV C1), the vaccine strain of Junín virus, more rapidly than did TLR2 knockout mice. This clearance correlated with the generation of Junín virus-specific CD8+ T cells. However, infected wild-type and TLR2 knockout mice developed TLR2-independent blocking antibody responses with similar kinetics. We also show that microglia and astrocytes but not neurons are susceptible to infection with JUNV C1. Although JUNV C1 infection of the brain also triggered a TLR2-dependent cytokine response, virus levels were equivalent in wild-type and TLR2 knockout mice. IMPORTANCE Junín virus is transmitted by rodents native to Argentina and is associated with both systemic disease and, in some patients, neurological symptoms. Humans become infected when they inhale aerosolized Junín virus. AHF has a 15 to 30% mortality rate, and patients who clear the infection develop a strong antibody response to Junín virus. Here we investigated what factors determine the immune response to Jun

  6. Toll-like Receptor 4 in CNS Pathologies

    PubMed Central

    Buchanan, Madison M.; Hutchinson, Mark; Watkins, Linda R.; Yin, Hang

    2010-01-01

    The responses of the brain to infection, ischemia and trauma share remarkable similarities. These and other conditions of the CNS coordinate an innate immune response marked by activation of microglia, the macrophage-like cells of the nervous system. An important contributor to microglial activation is toll-like receptor 4 (TLR4), a pathogen-associated molecular pattern receptor known to initiate an inflammatory cascade in response to various CNS stimuli. The present review traces new efforts to characterize and control the contribution of TLR4 to inflammatory etiologies of the nervous system. PMID:20402965

  7. Species-specific engagement of human nucleotide oligomerization domain 2 (NOD)2 and Toll-like receptor (TLR) signalling upon intracellular bacterial infection: role of Crohn's associated NOD2 gene variants.

    PubMed

    Salem, M; Seidelin, J B; Eickhardt, S; Alhede, M; Rogler, G; Nielsen, O H

    2015-03-01

    Recognition of bacterial peptidoglycan-derived muramyl-dipeptide (MDP) by nucleotide oligomerization domain 2 (NOD2) induces crucial innate immune responses. Most bacteria carry the N-acetylated form of MDP (A-MDP) in their cell membranes, whereas N-glycolyl MDP (G-MDP) is typical for mycobacteria. Experimental murine studies have reported G-MDP to have a greater NOD2-stimulating capacity than A-MDP. As NOD2 polymorphisms are associated with Crohn's disease (CD), a link has been suggested between mycobacterial infections and CD. Thus, the aim was to investigate if NOD2 responses are dependent upon type of MDP and further to determine the role of NOD2 gene variants for the bacterial recognition in CD. The response pattern to A-MDP, G-MDP, Mycobacterium segmatis (expressing mainly G-MDP) and M. segmatisΔnamH (expressing A-MDP), Listeria monocytogenes (LM) (an A-MDP-containing bacteria) and M. avium paratuberculosis (MAP) (a G-MDP-containing bacteria associated with CD) was investigated in human peripheral blood mononuclear cells (PBMCs). A-MDP and M. segmatisΔnamH induced significantly higher tumour necrosis factor (TNF)-α protein levels in healthy wild-type NOD2 PBMCs compared with G-MDP and M. segmatis. NOD2 mutations resulted in a low tumour necrosis factor (TNF)-α protein secretion following stimulation with LM. Contrary to this, TNF-α levels were unchanged upon MAP stimulation regardless of NOD2 genotype and MAP solely activated NOD2- and Toll-like receptor (TLRs)-pathway with an enhanced production of interleukin (IL)-1β and IL-10. In conclusion, the results indicate that CD-associated NOD2 deficiencies might affect the response towards a broader array of commensal and pathogenic bacteria expressing A-MDP, whereas they attenuate the role of mycobacteria in the pathogenesis of CD. PMID:25335775

  8. Species-specific engagement of human nucleotide oligomerization domain 2 (NOD)2 and Toll-like receptor (TLR) signalling upon intracellular bacterial infection: role of Crohn’s associated NOD2 gene variants

    PubMed Central

    Salem, M; Seidelin, J B; Eickhardt, S; Alhede, M; Rogler, G; Nielsen, O H

    2015-01-01

    Recognition of bacterial peptidoglycan-derived muramyl-dipeptide (MDP) by nucleotide oligomerization domain 2 (NOD2) induces crucial innate immune responses. Most bacteria carry the N-acetylated form of MDP (A-MDP) in their cell membranes, whereas N-glycolyl MDP (G-MDP) is typical for mycobacteria. Experimental murine studies have reported G-MDP to have a greater NOD2-stimulating capacity than A-MDP. As NOD2 polymorphisms are associated with Crohn's disease (CD), a link has been suggested between mycobacterial infections and CD. Thus, the aim was to investigate if NOD2 responses are dependent upon type of MDP and further to determine the role of NOD2 gene variants for the bacterial recognition in CD. The response pattern to A-MDP, G-MDP, Mycobacterium segmatis (expressing mainly G-MDP) and M. segmatisΔnamH (expressing A-MDP), Listeria monocytogenes (LM) (an A-MDP-containing bacteria) and M. avium paratuberculosis (MAP) (a G-MDP-containing bacteria associated with CD) was investigated in human peripheral blood mononuclear cells (PBMCs). A-MDP and M. segmatisΔnamH induced significantly higher tumour necrosis factor (TNF)-α protein levels in healthy wild-type NOD2 PBMCs compared with G-MDP and M. segmatis. NOD2 mutations resulted in a low tumour necrosis factor (TNF)-α protein secretion following stimulation with LM. Contrary to this, TNF-α levels were unchanged upon MAP stimulation regardless of NOD2 genotype and MAP solely activated NOD2- and Toll-like receptor (TLRs)-pathway with an enhanced production of interleukin (IL)-1β and IL-10. In conclusion, the results indicate that CD-associated NOD2 deficiencies might affect the response towards a broader array of commensal and pathogenic bacteria expressing A-MDP, whereas they attenuate the role of mycobacteria in the pathogenesis of CD. PMID:25335775

  9. Differential chemokine and cytokine production by neonatal bovine gamma delta T-cell subsets in response to viral toll-like receptor agonists and in vivo respiratory syncytial virus infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Gamma delta T cells have recently been shown to respond to stimulation via toll like receptors (TLR). Bovine gamma delta T cells express TLR3 and TLR7, endosomal receptors that are key for the recognition of viruses such as bovine respiratory syncytial virus (BRSV); however, responses of gamma delta...

  10. Toll-like Receptors in Tumor Immunotherapy

    PubMed Central

    Paulos, Chrystal M.; Kaiser, Andrew; Wrzesinski, Claudia; Hinrichs, Christian S.; Cassard, Lydie; Boni, Andrea; Muranski, Pawel; Sanchez-Perez, Luis; Palmer, Douglas C.; Yu, Zhiya; Antony, Paul A.; Gattinoni, Luca; Rosenberg, Steven A.; Restifo, Nicholas P.

    2007-01-01

    Lymphodepletion with chemotherapeutic agents or total body irradiation (TBI) before adoptive transfer of tumor-specific T cells is a critical advancement in the treatment of patients with melanoma. More than 50% of patients that are refractory to other treatments experience an objective or curative response with this approach. Emerging data indicate that the key mechanisms underlying how TBI augments the functions of adoptively transferred T cells include (a) the depletion of regulatory Tcells (Treg) and myeloid-derived suppressor cells that limit the function and proliferation of adoptively transferred cells; (b) the removal of immune cells that act as “sinks” for homeostatic cytokines, whose levels increase after lymphodepletion; and (c) the activation of the innate immune system via Toll-like receptor 4 signaling, which is engaged by microbial lipopolysaccharide that translocated across the radiation-injured gut. Here, we review these mechanisms and focus on the effect of Toll-like receptor agonists in adoptive immunotherapy. We also discuss alternate regimens to chemotherapy or TBI, which might be used to safely treat patients with advanced disease and promote tumor regression. PMID:17875756

  11. The biology of Toll-like receptors.

    PubMed

    Means, T K; Golenbock, D T; Fenton, M J

    2000-09-01

    In 1997, a human homologue of the Drosophila Toll protein was described, a protein later to be designated Toll-like receptor 4 (TLR4). Since that time, additional human and murine TLR proteins have been identified. Mammalian TLR proteins appear to represent a conserved family of innate immune recognition receptors. These receptors are coupled to a signaling pathway that is conserved in mammals, insects, and plants, resulting in the activation of genes that mediate innate immune defenses. Numerous studies have now identified a wide variety of chemically-diverse bacterial products that serve as putative ligands for TLR proteins. More recent studies have identified the first endogenous protein ligands for TLR proteins. TLR signaling represents a key feature of innate immune response to pathogen invasion. PMID:10817965

  12. Structure of toll-like receptors.

    PubMed

    Gay, Nicholas J; Gangloff, Monique

    2008-01-01

    The ten human Toll-like receptors are able to respond to an extremely diverse range of microbial products ranging from di- and tri-acylated lipids to nucleic acids. An understanding of the molecular structure adopted by the receptor extracellular, transmembrane, and cytoplasmic domains and the way in which these structures interact with ligands and downstream signaling adapters can explain how recognition and signal transduction are achieved at a molecular level. In this article we discuss how the leucine-rich repeats of the receptor ectodomain have evolved to bind a wide variety of biological molecules. We also discuss how ligand binding induces dimerization of two receptor chains and initiates a series of protein conformational changes that lead to a signaling event in the cytoplasm of the immune system cell. Thus, the signaling process of the TLRs can be viewed as a unidirectional molecular switch. PMID:18071660

  13. Toll-Like Receptor Signaling Pathways

    PubMed Central

    Kawasaki, Takumi; Kawai, Taro

    2014-01-01

    Toll-like receptors (TLRs) play crucial roles in the innate immune system by recognizing pathogen-associated molecular patterns derived from various microbes. TLRs signal through the recruitment of specific adaptor molecules, leading to activation of the transcription factors NF-κB and IRFs, which dictate the outcome of innate immune responses. During the past decade, the precise mechanisms underlying TLR signaling have been clarified by various approaches involving genetic, biochemical, structural, cell biological, and bioinformatics studies. TLR signaling appears to be divergent and to play important roles in many aspects of the innate immune responses to given pathogens. In this review, we describe recent progress in our understanding of TLR signaling regulation and its contributions to host defense. PMID:25309543

  14. Dysregulation of Human Toll-like Receptor Function in Aging

    PubMed Central

    Shaw, Albert C.; Panda, Alexander; Joshi, Samit R.; Qian, Feng; Allore, Heather G.; Montgomery, Ruth R.

    2010-01-01

    Studies addressing immunosenescence in the immune system have expanded to focus on the innate as well as the adaptive responses. In particular, aging results in alterations in the function of Toll-like receptors (TLRs), the first described pattern recognition receptor family of the innate immune system. Recent studies have begun to elucidate the consequences of aging on TLR function in human cohorts and add to existing findings performed in animal models. In general, these studies show that human TLR function is impaired in the context of aging, and in addition there is evidence for inappropriate persistence of TLR activation in specific systems. These findings are consistent with an overarching theme of age-associated dysregulation of TLR signaling that likely contributes to the increased morbidity and mortality from infectious diseases found in geriatric patients. PMID:21074638

  15. Novel drugs targeting Toll-like receptors for antiviral therapy

    PubMed Central

    Patel, Mira C; Shirey, Kari Ann; Pletneva, Lioubov M; Boukhvalova, Marina S; Garzino-Demo, Alfredo; Vogel, Stefanie N; Blanco, Jorge CG

    2014-01-01

    Toll-like receptors (TLRs) are sentinel receptors of the host innate immune system that recognize conserved ‘pathogen-associated molecular patterns’ of invading microbes, including viruses. The activation of TLRs establishes antiviral innate immune responses and coordinates the development of long-lasting adaptive immunity in order to control viral pathogenesis. However, microbe-induced damage to host tissues may release ‘danger-associated molecular patterns’ that also activate TLRs, leading to an overexuberant inflammatory response and, ultimately, to tissue damage. Thus, TLRs have proven to be promising targets as therapeutics for the treatment of viral infections that result in inflammatory damage or as adjuvants in order to enhance the efficacy of vaccines. Here, we explore recent advances in TLR biology with a focus on novel drugs that target TLRs (agonists and antagonists) for antiviral therapy. PMID:25620999

  16. Unique features of chicken Toll-like receptors.

    PubMed

    Keestra, A Marijke; de Zoete, Marcel R; Bouwman, Lieneke I; Vaezirad, Mahdi M; van Putten, Jos P M

    2013-11-01

    Toll-like receptors (TLRs) are a major class of innate immune pattern recognition receptors that have a key role in immune homeostasis and the defense against infections. The research explosion that followed the discovery of TLRs more than a decade ago has boosted fundamental knowledge on the function of the immune system and the resistance against disease, providing a rational for clinical modulation of the immune response. In addition, the conserved nature of the ancient TLR system throughout the animal kingdom has enabled a comparative biology approach to understand the evolution, structural architecture, and function of TLRs. In the present review we focus on TLR biology in the avian species, and, especially, on the unique functional properties of the chicken TLR repertoire. PMID:23628643

  17. Toll-Like Receptors and Ischemic Brain Injury

    PubMed Central

    Gesuete, Raffaella; Kohama, Steven G.; Stenzel-Poore, Mary

    2014-01-01

    Toll-like receptors (TLRs) are master regulators of innate immunity and play an integral role in the activation of the inflammatory response during infections. In addition, TLRs influence the body’s response to numerous forms of injury. Recent data have shown that TLRs play a modulating role in ischemic brain damage after stroke. Interestingly, their stimulation prior to ischemia induces a tolerant state that is neuroprotective. This phenomenon, referred to as TLR preconditioning, is the result of reprogramming of the TLR response to ischemic injury. This review addresses the role of TLRs in brain ischemia and the activation of endogenous neuroprotective pathways in the setting of preconditioning. We highlight the protective role of the interferon-related response and the potential site of action for TLR preconditioning involving the blood-brain-barrier. Pharmacological modulation of TLR activation to promote protection against stroke is a promising approach for the development of prophylactic and acute therapies targeting ischemic brain injury. PMID:24709682

  18. Vitamin D Rescues Impaired Mycobacterium tuberculosis-Mediated Tumor Necrosis Factor Release in Macrophages of HIV-Seropositive Individuals through an Enhanced Toll-Like Receptor Signaling Pathway In Vitro

    PubMed Central

    Sinha, Sanjeev; Bole, Medhavi; Sharma, Surendra K.; Kumar, Narendra; Luthra, Kalpana; Li, Xin; Zhou, Xiuqin; Nelson, Benjamin; Han, Xinbing; Tachado, Souvenir D.; Patel, Naimish R.; Koziel, Henry

    2013-01-01

    Mycobacterium tuberculosis disease represents an enormous global health problem, with exceptionally high morbidity and mortality in HIV-seropositive (HIV+) persons. Alveolar macrophages from HIV+ persons demonstrate specific and targeted impairment of critical host cell responses, including impaired M. tuberculosis-mediated tumor necrosis factor (TNF) release and macrophage apoptosis. Vitamin D may promote anti-M. tuberculosis responses through upregulation of macrophage NO, NADPH oxidase, cathelicidin, and autophagy mechanisms, but whether vitamin D promotes anti-M. tuberculosis mechanisms in HIV+ macrophages is not known. In the current study, human macrophages exposed to M. tuberculosis demonstrated robust release of TNF, IκB degradation, and NF-κB nuclear translocation, and these responses were independent of vitamin D pretreatment. In marked contrast, HIV+ U1 human macrophages exposed to M. tuberculosis demonstrated very low TNF release and no significant IκB degradation or NF-κB nuclear translocation, whereas vitamin D pretreatment restored these critical responses. The vitamin D-mediated restored responses were dependent in part on macrophage CD14 expression. Importantly, similar response patterns were observed with clinically relevant human alveolar macrophages from healthy individuals and asymptomatic HIV+ persons at high clinical risk of M. tuberculosis infection. Taken together with the observation that local bronchoalveolar lavage fluid (BALF) levels of vitamin D are severely deficient in HIV+ persons, the data from this study demonstrate that exogenous vitamin D can selectively rescue impaired critical innate immune responses in vitro in alveolar macrophages from HIV+ persons at risk for M. tuberculosis disease, supporting a potential role for exogenous vitamin D as a therapeutic adjuvant in M. tuberculosis infection in HIV+ persons. PMID:23071135

  19. DIESEL EXHAUST ENHANCES TOLL-LIKE RECEPTOR 3 EXPRESSION AND SIGNALING IN RESPIRATORY EPITHELIAL CELLS

    EPA Science Inventory

    Our previous studies have shown that prior exposure of respiratory epithelial cells to an aqueous-trapped solution of DE (DEas) enhances the susceptibility to Influenza infections. Here we examined the effect of DEas on the toll-like receptor 3 (TLR3) pathway, which is responsib...

  20. Toll-like receptors in bony fish: from genomics to function

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Receptors that recognize conserved pathogen molecules are the first line of cellular innate immunity defense. Toll-like receptors (TLRs) are the best understood of the innate immune receptors that detect infections in mammals. Key features of the fish TLRs and the factors involved in their signali...

  1. Mincle suppresses Toll-like receptor 4 activation.

    PubMed

    Greco, Stephanie H; Mahmood, Syed Kashif; Vahle, Anne-Kristin; Ochi, Atsuo; Batel, Jennifer; Deutsch, Michael; Barilla, Rocky; Seifert, Lena; Pachter, H Leon; Daley, Donnele; Torres-Hernandez, Alejandro; Hundeyin, Mautin; Mani, Vishnu R; Miller, George

    2016-07-01

    Regulation of Toll-like receptor responses is critical for limiting tissue injury and autoimmunity in both sepsis and sterile inflammation. We found that Mincle, a C-type lectin receptor, regulates proinflammatory Toll-like receptor 4 signaling. Specifically, Mincle ligation diminishes Toll-like receptor 4-mediated inflammation, whereas Mincle deletion or knockdown results in marked hyperresponsiveness to lipopolysaccharide in vitro, as well as overwhelming lipopolysaccharide-mediated inflammation in vivo. Mechanistically, Mincle deletion does not up-regulate Toll-like receptor 4 expression or reduce interleukin 10 production after Toll-like receptor 4 ligation; however, Mincle deletion decreases production of the p38 mitogen-activated protein kinase-dependent inhibitory intermediate suppressor of cytokine signaling 1, A20, and ABIN3 and increases expression of the Toll-like receptor 4 coreceptor CD14. Blockade of CD14 mitigates the increased sensitivity of Mincle(-/-) leukocytes to Toll-like receptor 4 ligation. Collectively, we describe a major role for Mincle in suppressing Toll-like receptor 4 responses and implicate its importance in nonmycobacterial models of inflammation. PMID:26747838

  2. Toll-Like Receptors of Deuterostome Invertebrates

    PubMed Central

    Satake, Honoo; Sekiguchi, Toshio

    2012-01-01

    Defensive systems against pathogens are responsible not only for survival or lifetime of an individual but also for the evolution of a species. Innate immunity is expected to be more important for invertebrates than mammals, given that adaptive immunity has not been acquired in the former. Toll-like receptors (TLRs) have been shown to play a crucial role in host defense of pathogenic microbes in innate immunity of mammals. Recent genome-wide analyses have suggested that TLR or their related genes are conserved in invertebrates. In particular, numerous TLR-related gene candidates were detected in deuterostome invertebrates, including a sea urchin (222 TLR-related gene candidates) and amphioxus (72 TLR-related gene candidates). Molecular phylogenetic analysis verified that most of sea urchin or amphioxus TLR candidates are paralogous, suggesting that these organisms expanded TLR-related genes in a species-specific manner. In contrast, another deuterostome invertebrate, the ascidian Ciona intestinalis, was found to possess only two TLR genes. Moreover, Ciona TLRs, Ci-TLR1 and Ci-TLR2, were shown to possess “hybrid” functionality of mammalian TLRs. Such functionality of Ci-TLRs could not be predicted by sequence comparison with vertebrate TLRs, indicating confounding evolutionary lineages of deuterostome invertebrate TLRs or their candidates. In this review article, we present recent advances in studies of TLRs or their candidates among deuterostome invertebrates, and provide insight into an evolutionary process of TLRs. PMID:22566918

  3. Toll-Like Receptors and Prostate Cancer

    PubMed Central

    Zhao, Shu; Zhang, Yifan; Zhang, Qingyuan; Wang, Fen; Zhang, Dekai

    2014-01-01

    Prostate cancer is the second leading cause of cancer-related death in men after lung cancer. Immune responses clearly play a critical role in the tumorigenesis and in the efficacy of radiation therapy and chemotherapy in prostate cancer; however, the underlying molecular mechanisms are still poorly understood. Toll-like receptors (TLRs) are a well-known family of pattern recognition receptors that play a key role in host immune system. Recent studies demonstrate that there are links between TLRs and cancer; however, the function and biological importance of TLRs in prostate cancer seems complex. To elucidate the role of TLRs and innate immunity in prostate cancer might provide us with a better understanding of the molecular mechanisms of this disease. Moreover, utilizing the agonists or antagonists of TLRs might represent a promising new strategy against prostate cancer. In this review, we summarize recent advances on the studies of association between TLR signaling and prostate cancer, TLR polymorphisms and prostate cancer risk, and provide some insights about TLRs as potential targets for prostate cancer immunotherapy. PMID:25101092

  4. Interplay between HIV-1 and Toll-like receptors in human myeloid cells: friend or foe in HIV-1 pathogenesis?

    PubMed

    Donninelli, Gloria; Gessani, Sandra; Del Cornò, Manuela

    2016-01-01

    The Toll-like receptors are the first line of the host response to pathogens, representing an essential component of the innate and adaptive immune response. They recognize different pathogens and trigger responses directed at eliminating the invader and at developing immunologic long-term memory, ultimately affecting viral pathogenesis. In viral infections, sensing of nucleic acids and/or viral structural proteins generally induces a protective immune response. Thus, it is not surprising that many viruses have developed strategies to evade or counteract signaling through the Toll-like receptor pathways, to survive the host defense machinery and ensure propagation. Thus, Toll-like receptor engagement can also be part of viral pathogenic mechanisms. Evidence for a direct interaction of Toll-like receptors with human immunodeficiency virus type 1 (HIV-1) structures has started to be achieved, and alterations of their expression and function have been described in HIV-1-positive subjects. Furthermore, Toll-like receptor triggering by bacterial and viral ligands have been described to modulate HIV-1 replication and host response, leading to protective or detrimental effects. This review covers major advances in the field of HIV-1 interplay with Toll-like receptors, focusing on human myeloid cells (e.g., monocytes/macrophages and dendritic cells). The role of this interaction in the dysregulation of myeloid cell function and in dictating aspects of the multifaceted pathogenesis of acquired immunodeficiency syndrome will be discussed. PMID:26307548

  5. Differential Toll-Like Receptor-Signalling of Burkholderia pseudomallei Lipopolysaccharide in Murine and Human Models

    PubMed Central

    Weehuizen, Tassili A. F.; Prior, Joann L.; van der Vaart, Thomas W.; Ngugi, Sarah A.; Nepogodiev, Sergey A.; Field, Robert A.; Kager, Liesbeth M.; van ‘t Veer, Cornelis; de Vos, Alex F.; Wiersinga, W. Joost

    2015-01-01

    The Gram-negative bacterium Burkholderia pseudomallei causes melioidosis and is a CDC category B bioterrorism agent. Toll-like receptor (TLR)-2 impairs host defense during pulmonary B.pseudomallei infection while TLR4 only has limited impact. We investigated the role of TLRs in B.pseudomallei-lipopolysaccharide (LPS) induced inflammation. Purified B.pseudomallei-LPS activated only TLR2-transfected-HEK-cells during short stimulation but both HEK-TLR2 and HEK-TLR4-cells after 24 h. In human blood, an additive effect of TLR2 on TLR4-mediated signalling induced by B.pseudomallei-LPS was observed. In contrast, murine peritoneal macrophages recognized B.pseudomallei-LPS solely through TLR4. Intranasal inoculation of B.pseudomallei-LPS showed that both TLR4-knockout(-/-) and TLR2x4-/-, but not TLR2-/- mice, displayed diminished cytokine responses and neutrophil influx compared to wild-type controls. These data suggest that B.pseudomallei-LPS signalling occurs solely through murine TLR4, while in human models TLR2 plays an additional role, highlighting important differences between specificity of human and murine models that may have important consequences for B.pseudomallei-LPS sensing by TLRs and subsequent susceptibility to melioidosis. PMID:26689559

  6. MAP1S Protein Regulates the Phagocytosis of Bacteria and Toll-like Receptor (TLR) Signaling.

    PubMed

    Shi, Ming; Zhang, Yifan; Liu, Leyuan; Zhang, Tingting; Han, Fang; Cleveland, Joseph; Wang, Fen; McKeehan, Wallace L; Li, Yu; Zhang, Dekai

    2016-01-15

    Phagocytosis is a critical cellular process for innate immune defense against microbial infection. The regulation of phagocytosis process is complex and has not been well defined. An intracellular molecule might regulate cell surface-initiated phagocytosis, but the underlying molecular mechanism is poorly understood (1). In this study, we found that microtubule-associated protein 1S (MAP1S), a protein identified recently that is involved in autophagy (2), is expressed primarily in macrophages. MAP1S-deficient macrophages are impaired in the phagocytosis of bacteria. Furthermore, we demonstrate that MAP1S interacts directly with MyD88, a key adaptor of Toll-like receptors (TLRs), upon TLR activation and affects the TLR signaling pathway. Intriguingly, we also observe that, upon TLR activation, MyD88 participates in autophagy processing in a MAP1S-dependent manner by co-localizing with MAP1 light chain 3 (MAP1-LC3 or LC3). Therefore, we reveal that an intracellular autophagy-related molecule of MAP1S controls bacterial phagocytosis through TLR signaling. PMID:26565030

  7. Toll-Like Receptor 7-Targeted Therapy in Respiratory Disease.

    PubMed

    Lebold, Katie M; Jacoby, David B; Drake, Matthew G

    2016-03-01

    Allergic asthma and allergic rhinitis are inflammatory diseases of the respiratory tract characterized by an excessive type-2 T helper cell (Th2) immune response. Toll-like receptor 7 (TLR7) is a single-stranded viral RNA receptor expressed in the airway that initiates a Th1 immune response and has garnered interest as a novel therapeutic target for treatment of allergic airway diseases. In animal models, synthetic TLR7 agonists reduce airway hyperreactivity, eosinophilic inflammation, and airway remodeling while decreasing Th2-associated cytokines. Furthermore, activation of TLR7 rapidly relaxes airway smooth muscle via production of nitric oxide. Thus, TLR7 has dual bronchodilator and anti-inflammatory effects. Two TLR7 ligands with promising pharmacologic profiles have entered clinical trials for the treatment of allergic rhinitis. Moreover, TLR7 agonists are potential antiviral therapies against respiratory viruses. TLR7 agonists enhance influenza vaccine efficacy and also reduce viral titers when given during an active airway infection. In this review, we examine the current data supporting TLR7 as a therapeutic target in allergic airway diseases. PMID:27226793

  8. Toll-like receptors as sensors of pathogens.

    PubMed

    Hallman, M; Rämet, M; Ezekowitz, R A

    2001-09-01

    Initial recognition of microbes, as they enter the body, is based on germ line-encoded pattern recognition receptors that selectively bind to essential components of pathogens. This allows the body to respond immediately to the microbial invasion before the development of active immunity. The signal-transducing receptors that trigger the acute inflammatory cascade have been elusive until very recently. On the basis of their genetic similarity to the Toll signaling pathway in Drosophila, mammalian Toll-like receptors (TLRs) have been identified. By now, nine transmembrane proteins in the TLR family have been described. Mammalian TLR4 is the signal-transducing receptor activated by the bacterial lipopolysaccharide. The activation of TLR4 leads to DNA binding of the transcription factor NF-kappaB, resulting in activation of the inflammatory cascade. Activation of other TLRs is likely to have similar consequences. TLR2 mediates the host response to Gram-positive bacteria and yeast. TLR1 and TLR6 may participate in the activation of macrophages by Gram-positive bacteria, whereas TLR9 appears to respond to a specific sequence of bacterial DNA. The TLRs that control the onset of an acute inflammatory response are critical antecedents for the development of adaptive acquired immunity. Genetic and developmental variation in the expression of microbial pattern recognition receptors may affect the individual's predisposition to infections in childhood and may contribute to susceptibility to severe neonatal inflammatory diseases, allergies, and autoimmune diseases. PMID:11518816

  9. Subverting Toll-Like Receptor Signaling by Bacterial Pathogens

    PubMed Central

    McGuire, Victoria A.; Arthur, J. Simon C.

    2015-01-01

    Pathogenic bacteria are detected by pattern-recognition receptors (PRRs) expressed on innate immune cells, which activate intracellular signal transduction pathways to elicit an immune response. Toll-like receptors are, perhaps, the most studied of the PRRs and can activate the mitogen-activated protein kinase (MAPK) and Nuclear Factor-κB (NF-κB) pathways. These pathways are critical for mounting an effective immune response. In order to evade detection and promote virulence, many pathogens subvert the host immune response by targeting components of these signal transduction pathways. This mini-review highlights the diverse mechanisms that bacterial pathogens have evolved to manipulate the innate immune response, with a particular focus on those that target MAPK and NF-κB signaling pathways. Understanding the elaborate strategies that pathogens employ to subvert the immune response not only highlights the importance of these proteins in mounting effective immune responses, but may also identify novel approaches for treatment or prevention of infection. PMID:26648936

  10. Toll-like receptor signaling in primary immune deficiencies.

    PubMed

    Maglione, Paul J; Simchoni, Noa; Cunningham-Rundles, Charlotte

    2015-11-01

    Toll-like receptors (TLRs) recognize common microbial or host-derived macromolecules and have important roles in early activation of the immune system. Patients with primary immune deficiencies (PIDs) affecting TLR signaling can elucidate the importance of these proteins to the human immune system. Defects in interleukin-1 receptor-associated kinase-4 and myeloid differentiation factor 88 (MyD88) lead to susceptibility to infections with bacteria, while mutations in nuclear factor-κB essential modulator (NEMO) and other downstream mediators generally induce broader susceptibility to bacteria, viruses, and fungi. In contrast, TLR3 signaling defects are specific for susceptibility to herpes simplex virus type 1 encephalitis. Other PIDs induce functional alterations of TLR signaling pathways, such as common variable immunodeficiency in which plasmacytoid dendritic cell defects enhance defective responses of B cells to shared TLR agonists. Dampening of TLR responses is seen for TLRs 2 and 4 in chronic granulomatous disease (CGD) and X-linked agammaglobulinemia (XLA). Enhanced TLR responses, meanwhile, are seen for TLRs 5 and 9 in CGD, TLRs 4, 7/8, and 9 in XLA, TLRs 2 and 4 in hyper IgE syndrome, and for most TLRs in adenosine deaminase deficiency. PMID:25930993

  11. Toll-Like Receptor 7-Targeted Therapy in Respiratory Disease

    PubMed Central

    Lebold, Katie M.; Jacoby, David B.; Drake, Matthew G.

    2016-01-01

    Summary Allergic asthma and allergic rhinitis are inflammatory diseases of the respiratory tract characterized by an excessive type-2 T helper cell (Th2) immune response. Toll-like receptor 7 (TLR7) is a single-stranded viral RNA receptor expressed in the airway that initiates a Th1 immune response and has garnered interest as a novel therapeutic target for treatment of allergic airway diseases. In animal models, synthetic TLR7 agonists reduce airway hyperreactivity, eosinophilic inflammation, and airway remodeling while decreasing Th2-associated cytokines. Furthermore, activation of TLR7 rapidly relaxes airway smooth muscle via production of nitric oxide. Thus, TLR7 has dual bronchodilator and anti-inflammatory effects. Two TLR7 ligands with promising pharmacologic profiles have entered clinical trials for the treatment of allergic rhinitis. Moreover, TLR7 agonists are potential antiviral therapies against respiratory viruses. TLR7 agonists enhance influenza vaccine efficacy and also reduce viral titers when given during an active airway infection. In this review, we examine the current data supporting TLR7 as a therapeutic target in allergic airway diseases. PMID:27226793

  12. GENES, IN ADDITION TO TOLL-LIKE RECEPTOR 2, PLAY A ROLE IN ANTIBACTERIAL DEFENSE TO STREPTOCOCCAL PNEUMONIA

    EPA Science Inventory

    Streptococcus infection in human populations continues to be a major cause of morbidity and mortality. To evaluate the effect of genetic background and toll-like receptor 2 (TLR2) on antibacterial defense to streptococcal infection, eight genetically diverse strains of mic...

  13. Differential roles of Toll-like receptors in the elicitation of type I interferon responses by alveolar macrophages

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of virus replication initially depends on rapid activation of the innate immune responses. Toll-like receptor (TLR) ligands are potent inducers of innate immunity against viral infections. Porcine reproductive and respiratory syndrome virus (PRRSV) initiates infection in pulmonary alveolar...

  14. Hepatitis B virus genome replication triggers toll-like receptor 3-dependent interferon responses in the absence of hepatitis B surface antigen.

    PubMed

    Real, Catherine Isabell; Lu, Mengji; Liu, Jia; Huang, Xuan; Trippler, Martin; Hossbach, Markus; Deckert, Jochen; Jahn-Hofmann, Kerstin; Ickenstein, Ludger Markus; John, Matthias Johannes; Gibbert, Kathrin; Dittmer, Ulf; Vornlocher, Hans-Peter; Schirmbeck, Reinhold; Gerken, Guido; Schlaak, Joerg Friedrich; Broering, Ruth

    2016-01-01

    The hepatitis B virus (HBV) has been described as stealth virus subverting immune responses initially upon infection. Impaired toll-like receptor signaling by the HBV surface antigen (HBsAg) attenuates immune responses to facilitate chronic infection. This implies that HBV replication may trigger host innate immune responses in the absence of HBsAg. Here we tested this hypothesis, using highly replicative transgenic mouse models. An HBV replication-dependent expression of antiviral genes was exclusively induced in HBsAg-deficient mice. These interferon responses attributed to toll-like receptor 3 (TLR3)-activated Kupffer and liver sinusoidal endothelial cells and further controlled the HBV genome replication. However, activation of TLR3 with exogenous ligands indicated additional HBs-independent immune evasion events. Our data demonstrate that in the absence of HBsAg, hepatic HBV replication leads to Tlr3-dependent interferon responses in non-parenchymal liver cells. We hypothesize that HBsAg is a major HBV-mediated evasion mechanism controlling endogenous antiviral responses in the liver. Eradication of HBsAg as a therapeutic goal might facilitate the induction of endogenous antiviral immune responses in patients chronically infected with HBV. PMID:27121087

  15. Hepatitis B virus genome replication triggers toll-like receptor 3-dependent interferon responses in the absence of hepatitis B surface antigen

    PubMed Central

    Real, Catherine Isabell; Lu, Mengji; Liu, Jia; Huang, Xuan; Trippler, Martin; Hossbach, Markus; Deckert, Jochen; Jahn-Hofmann, Kerstin; Ickenstein, Ludger Markus; John, Matthias Johannes; Gibbert, Kathrin; Dittmer, Ulf; Vornlocher, Hans-Peter; Schirmbeck, Reinhold; Gerken, Guido; Schlaak, Joerg Friedrich; Broering, Ruth

    2016-01-01

    The hepatitis B virus (HBV) has been described as stealth virus subverting immune responses initially upon infection. Impaired toll-like receptor signaling by the HBV surface antigen (HBsAg) attenuates immune responses to facilitate chronic infection. This implies that HBV replication may trigger host innate immune responses in the absence of HBsAg. Here we tested this hypothesis, using highly replicative transgenic mouse models. An HBV replication-dependent expression of antiviral genes was exclusively induced in HBsAg-deficient mice. These interferon responses attributed to toll-like receptor 3 (TLR3)-activated Kupffer and liver sinusoidal endothelial cells and further controlled the HBV genome replication. However, activation of TLR3 with exogenous ligands indicated additional HBs-independent immune evasion events. Our data demonstrate that in the absence of HBsAg, hepatic HBV replication leads to Tlr3-dependent interferon responses in non-parenchymal liver cells. We hypothesize that HBsAg is a major HBV-mediated evasion mechanism controlling endogenous antiviral responses in the liver. Eradication of HBsAg as a therapeutic goal might facilitate the induction of endogenous antiviral immune responses in patients chronically infected with HBV. PMID:27121087

  16. Stimulation by toll-like receptors inhibits osteoclast differentiation.

    PubMed

    Takami, Masamichi; Kim, Nacksung; Rho, Jaerang; Choi, Yongwon

    2002-08-01

    Osteoclasts, the cells capable of resorbing bone, are derived from hemopoietic precursor cells of monocyte-macrophage lineage. The same precursor cells can also give rise to macrophages and dendritic cells, which are essential for proper immune responses to various pathogens. Immune responses to microbial pathogens are often triggered because various microbial components induce the maturation and activation of immunoregulatory cells such as macrophages or dendritic cells by stimulating Toll-like receptors (TLRs). Since osteoclasts arise from the same precursors as macrophages, we tested whether TLRs play any role during osteoclast differentiation. We showed here that osteoclast precursors prepared from mouse bone marrow cells expressed all known murine TLRs (TLR1-TLR9). Moreover, various TLR ligands (e.g., peptidoglycan, poly(I:C) dsRNA, LPS, and CpG motif of unmethylated DNA, which act as ligands for TLR2, 3, 4, and 9, respectively) induced NF-kappa B activation and up-regulated TNF-alpha production in osteoclast precursor cells. Unexpectedly, however, TLR stimulation of osteoclast precursors by these microbial products strongly inhibited their differentiation into multinucleated, mature osteoclasts induced by TNF-related activation-induced cytokine. Rather, TLR stimulation maintained the phagocytic activity of osteoclast precursors in the presence of osteoclastogenic stimuli M-CSF and TNF-related activation-induced cytokine. Taken together, these results suggest that TLR stimulation of osteoclast precursors inhibits their differentiation into noninflammatory mature osteoclasts during microbial infection. This process favors immune responses and may be critical to prevent pathogenic effects of microbial invasion on bone. PMID:12133979

  17. Toll-like receptors in the pathogenesis of inflammatory diseases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Toll-like receptors (TLRs) are newly established immune receptors which are critical for host defense through the activation of both innate and adaptive immunity. TLRs can recognize molecules with both microbial and non-microbial origins. Emerging evidence now suggests that TLRs are implicated in th...

  18. MAPPING OF TOLL LIKE RECEPTOR (TLR) GENES IN RAINBOW TROUT

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Toll-like receptors (TLRs) are a family of transmembrane proteins that recognize conserved pathogen structures to induce innate immune effector molecules. In vertebrates, TLRs can distinguish among classes of pathogens and serve an important role in orchestrating the appropriate adaptive immune resp...

  19. Toll-like receptor 3 expression and function in childhood idiopathic nephrotic syndrome.

    PubMed

    Jamin, A; Dehoux, L; Dossier, C; Fila, M; Heming, N; Monteiro, R C; Deschênes, G

    2015-12-01

    The efficacy of steroids and immunosuppressive treatments in idiopathic nephrotic syndrome (INS) hints at the implication of immune cells in the pathophysiology of the disease. Toll-like receptor (TLR) dysfunctions are involved in many kidney diseases of immune origin, but remain little described in INS. We investigated the expression and function of TLRs in peripheral blood mononuclear cells (PBMC) of INS children, including 28 in relapse, 23 in remission and 40 controls. No child had any sign of infection, but a higher Epstein-Barr virus viral load was measured in the PBMC of relapsing patients. TLR-3 expression was increased in B cells only during INS remission. There was a negative correlation between proteinuria and TLR-3 expression in total and the main subsets of PBMC from INS patients. The expression of TLR-8 was also increased in both CD4(+) T cells and B cells in INS remission. There was a negative correlation between proteinuria and TLR-8 expression in total PBMC, CD4(+) T cells and B cells of INS patients. Nevertheless, TLR-3 and TLR-8 expression was normalized in all PBMC subsets in an additional group of 15 INS patients in remission with B cell repletion after rituximab therapy. Paradoxically, interferon (IFN) regulatory factor 3 transactivation was increased in PBMC of all INS patients. In-vitro secretion of IFN-α and interleukin 6 were increased spontaneously in PBMC of INS remission patients, whereas PBMC from all INS patients displayed an impaired IFN-α secretion after TLR-3 stimulation. Thus, TLR-3 pathway dysfunctions may be closely involved in INS pathogenesis. PMID:26123900

  20. The adenosine system modulates Toll-like receptor function: basic mechanisms, clinical correlates and translational opportunities

    PubMed Central

    Coombs, Melanie R. Power; Belderbos, Mirjam E.; Gallington, Leighanne C.; Bont, Louis; Levy, Ofer

    2014-01-01

    Adenosine is an endogenous purine metabolite whose concentration in human blood plasma rises from nanomolar to micromolar during stress or hypoxia. Leukocytes express seven-transmembrane adenosine receptors whose engagement modulates Toll-like receptor-mediated cytokine responses, in part via modulation of intracellular cyclic adenosine monophosphate (cAMP). Adenosine congeners are used clinically to treat arrhythmias and apnea of prematurity. Herein we consider the potential of adenosine congeners as innate immune response modifiers to prevent and/or treat infection. PMID:21342073

  1. Elevated Toll-Like Receptor-Induced CXCL8 Secretion in Human Blood Basophils from Allergic Donors Is Independent of Toll-Like Receptor Expression Levels

    PubMed Central

    Steiner, Markus; Hawranek, Thomas; Schneider, Michael; Ferreira, Fatima; Horejs-Hoeck, Jutta; Harrer, Andrea; Himly, Martin

    2016-01-01

    Human blood basophils have recently gained interest in addition to their function as allergic effector cells. Previous work suggests the involvement of innate immune mechanisms in the development and exacerbation of allergic responses, which might be mediated by basophils. We assayed the expression levels of Toll-like receptor (TLR) 1, 2, 4 and 6 on purified basophils from birch pollen-, house dust mite-, and non-allergic individuals. Additionally, we compared cytokine and chemokine secretion upon TLR stimulation in these basophil donor groups. Expression of TLR4 on the basophils of the allergic donor groups was decreased and CXCL8 secretion was elevated upon stimulation of TLR1/2 and TLR2/6 compared to the non-allergic donors. Decreased TLR expression and elevated CXCL8 secretion may represent possible mechanisms for aggravation of allergic symptoms in case of parasitic infection. PMID:26870962

  2. TRADITIONAL BIOCHEMICAL ASSAYS FOR STUDYING TOLL-LIKE RECEPTOR 9

    PubMed Central

    Leifer, Cynthia A.; Rose, William A.; Botelho, Fernando

    2015-01-01

    Understanding the mechanistic basis of receptor activation and regulation can offer therapeutic targets for disease treatment. Evidence is emerging for a role of the normally foreign responsive Toll-like receptors (TLRs) in the development of autoimmunity through response to self-patterns. Regulatory mechanisms governing this class of receptors are poorly understood, and failures within this system likely contribute to development of autoimmunity. In this article, we review biochemical assays used to study one of the self-pattern responsive TLRs, TLR9, and suggest that these studies are critical for development of new targets for autoimmune therapies. PMID:23323977

  3. Therapeutic potential of Toll-like receptor 9 activation.

    PubMed

    Krieg, Arthur M

    2006-06-01

    In the decade since the discovery that mouse B cells respond to certain unmethylated CpG dinucleotides in bacterial DNA, a specific receptor for these 'CpG motifs' has been identified, Toll-like receptor 9 (TLR9), and a new approach to immunotherapy has moved into the clinic based on the use of synthetic oligodeoxynucleotides (ODN) as TLR9 agonists. This review highlights the current understanding of the mechanism of action of these CpG ODN, and provides an overview of the preclinical data and early human clinical trial results using these drugs to improve vaccines and treat cancer, infectious disease and allergy/asthma. PMID:16763660

  4. Activation of epidermal toll-like receptor 2 enhances tight junction function: implications for atopic dermatitis and skin barrier repair.

    PubMed

    Kuo, I-Hsin; Carpenter-Mendini, Amanda; Yoshida, Takeshi; McGirt, Laura Y; Ivanov, Andrei I; Barnes, Kathleen C; Gallo, Richard L; Borkowski, Andrew W; Yamasaki, Kenshi; Leung, Donald Y; Georas, Steve N; De Benedetto, Anna; Beck, Lisa A

    2013-04-01

    Atopic dermatitis (AD) is characterized by epidermal tight junction (TJ) defects and a propensity for Staphylococcus aureus skin infections. S. aureus is sensed by many pattern recognition receptors, including Toll-like receptor 2 (TLR2). We hypothesized that an effective innate immune response will include skin barrier repair, and that this response is impaired in AD subjects. S. aureus-derived peptidoglycan (PGN) and synthetic TLR2 agonists enhanced TJ barrier and increased expression of TJ proteins, claudin-1 (CLDN1), claudin-23 (CLDN23), occludin, and Zonulae occludens 1 (ZO-1) in primary human keratinocytes. A TLR2 agonist enhanced skin barrier recovery in human epidermis wounded by tape stripping. Tlr2(-/-) mice had a delayed and incomplete barrier recovery following tape stripping. AD subjects had reduced epidermal TLR2 expression as compared with nonatopic subjects, which inversely correlated (r=-0.654, P=0.0004) with transepidermal water loss (TEWL). These observations indicate that TLR2 activation enhances skin barrier in murine and human skin and is an important part of a wound repair response. Reduced epidermal TLR2 expression observed in AD patients may have a role in their incompetent skin barrier. PMID:23223142

  5. Toll-Like Receptors: A Key Marker for Periodontal Disease and Preterm Birth – A Contemporary Review

    PubMed Central

    Mahendra, Jaideep

    2015-01-01

    The receptors of the innate immune system have evolved to recognize pathogenic bacteria in a complex manner. Out of these immune receptors, the pattern recognition receptors (PRRs) such as Toll like receptors have gained importance off late to play a key role in the activation of cascade of inflammatory cytokines in pathogenesis of preterm birth. Preterm birth has become leading cause of neonatal deaths globally. The concept of oral infection influencing the occurrence of preterm delivery has gained importance. Translocation of periodontal pathogens and inflammatory mediators play role in the pathogenesis of preterm labour. The transmembrane toll like receptors of innate immunity have been recently implicated in the association of periodontal infection and preterm labour. The TLRs are considered as a key marker and TLR blockade can be a critical method for treating women who are exposed to periodontal pathogens. This review is aimed at discussing the role of TLR in periodontal disease and its relationship with preterm birth. PMID:26501032

  6. Regulation of antigen presentation by Mycobacterium tuberculosis: a role for Toll-like receptors

    PubMed Central

    Harding, Clifford V.; Boom, W. Henry

    2011-01-01

    Mycobacterium tuberculosis survives in antigen-presenting cells (APCs) such as macrophages and dendritic cells. APCs present antigens in association with major histocompatibility complex (MHC) class II molecules to stimulate CD4+ T cells, and this process is essential to contain M. tuberculosis infection. Immune evasion allows M. tuberculosis to establish persistent or latent infection in macrophages and results in Toll-like receptor 2 (TLR2)-dependent inhibition of MHC class II transactivator expression, MHC class II molecule expression and antigen presentation. This reduction of antigen presentation might reflect a general mechanism of negative-feedback regulation that prevents excessive T cell-mediated inflammation and that M. tuberculosis has subverted to create a niche for survival in infected macrophages and evasion of recognition by CD4+ T cells. PMID:20234378

  7. Immunomodulatory parasites and toll-like receptor-mediated tumour necrosis factor alpha responsiveness in wild mammals

    PubMed Central

    Jackson, Joseph A; Friberg, Ida M; Bolch, Luke; Lowe, Ann; Ralli, Catriona; Harris, Philip D; Behnke, Jerzy M; Bradley, Janette E

    2009-01-01

    Background Immunological analyses of wild populations can increase our understanding of how vertebrate immune systems respond to 'natural' levels of exposure to diverse infections. A major recent advance in immunology has been the recognition of the central role of phylogenetically conserved toll-like receptors in triggering innate immunity and the subsequent recruitment of adaptive response programmes. We studied the cross-sectional associations between individual levels of systemic toll-like receptor-mediated tumour necrosis factor alpha responsiveness and macro- and microparasite infections in a natural wood mouse (Apodemus sylvaticus) population. Results Amongst a diverse group of macroparasites, only levels of the nematode Heligmosomoides polygyrus and the louse Polyplax serrata were correlated (negatively) with innate immune responsiveness (measured by splenocyte tumour necrosis factor alpha responses to a panel of toll-like receptor agonists). Polyplax serrata infection explained a strikingly high proportion of the total variation in innate responses. Contrastingly, faecal oocyst count in microparasitic Eimeria spp. was positively associated with innate immune responsiveness, most significantly for the endosomal receptors TLR7 and TLR9. Conclusion Analogy with relevant laboratory models suggests the underlying causality for the observed patterns may be parasite-driven immunomodulatory effects on the host. A subset of immunomodulatory parasite species could thus have a key role in structuring other infections in natural vertebrate populations by affecting the 'upstream' innate mediators, like toll-like receptors, that are important in initiating immunity. Furthermore, the magnitude of the present result suggests that populations free from immunosuppressive parasites may exist at 'unnaturally' elevated levels of innate immune activation, perhaps leading to an increased risk of immunopathology. PMID:19386086

  8. Effect of Chlamydia pneumoniae on Cellular ATP Content in Mouse Macrophages: Role of Toll-Like Receptor 2

    PubMed Central

    Yaraei, Kambiz; Campbell, Lee Ann; Zhu, Xiaodong; Liles, W. Conrad; Kuo, Cho-chou; Rosenfeld, Michael E.

    2005-01-01

    Chlamydiae are obligate intracellular gram-negative bacteria and are dependent on the host cell for ATP. Thus, chlamydial infection may alter the intracellular levels of ATP and affect all energy-dependent processes within the cell. We have shown that both live C. pneumoniae and inactivated C. pneumoniae induce markers of cell death prior to completion of the bacterial growth cycle. As depletion of ATP could account for the observed increase in cell death, the effects of C. pneumoniae on ATP concentrations within mouse macrophages were investigated. Live, heat-killed, and UV-inactivated C. pneumoniae cultures (at multiplicities of infection [MOIs] of 0.01, 0.1, and 1.0) were incubated with mouse bone marrow macrophages isolated from C57BL/6J mice and mice deficient in Toll-like receptors. Treatment of the macrophages with both live and inactivated C. pneumoniae increased the ATP content of the cells. In cells infected with live C. pneumoniae, the increase was inversely proportional to the MOI. In cells treated with inactivated C. pneumoniae, the increase in ATP content was smaller than that induced by infection with live organisms and was proportional to the MOI. The increase in ATP content early in the developmental cycle was independent of the growth of C. pneumoniae, while sustained induction required live organisms. The capacity of C. pneumoniae to increase the ATP content was ablated in macrophages deficient in expression of either Toll-like receptor 2 or the Toll-like receptor accessory protein MyD88. In contrast, no effect was observed in macrophages lacking expression of Toll-like receptor 4. PMID:15972526

  9. The role of toll-like receptors 2 and 4 in the pathogenesis of feline pyometra.

    PubMed

    Jursza, E; Kowalewski, M P; Boos, A; Skarzynski, D J; Socha, P; Siemieniuch, M J

    2015-03-01

    Pyometra is the most common uterine disease in queens. To protect itself from infection, the female reproductive tract possesses several immune mechanisms that are based on germline-encoded pattern recognition receptors (toll-like receptors [TLRs]). The aim of our study was to examine endometrial immunolocalization of TLR2/4, study the influence of lipopolysaccharide (LPS) and tumor necrosis factor (TNF) α on messenger RNA expression of both receptors in pyometric queens, and compare these patterns between estrous cycling queens and those hormonally treated with medroxyprogesterone acetate (MPA). Thirty-six queens, ranging in age from 7 months to 11 years, were allocated into seven groups (anestrus, estrus, mid-diestrus and late diestrus, short-term and long-term hormonally treated queens, and pyometric queens). At the messenger RNA level, the real-time polymerase chain reaction was applied, whereas at the TLR2/4 protein level, the expression was tested by immunohistochemistry. In queens at estrus, gene expression of TLR2 was upregulated after stimulation of endometrial explants by TNF (P < 0.001) and by TNF together with the LPS (P < 0.01). Moreover, gene expression of TLR2 was significantly upregulated after stimulation by TNF (P < 0.001) and LPS (P < 0.01) explants derived from queens that had been long-term hormonally treated with MPA. Endometrial gene expression of TLR4 was significantly upregulated after incubation of explants with TNF (P < 0.001) in queens at estrus and with LPS (P < 0.05) in queens short-term hormonally treated with MPA. Immunolocalization reported that TLR2/4 receptors are mainly localized in the surface and glandular epithelia. These data show that short-term and especially long-term administration of progesterone derivatives impairs TLRs in the endometrial epithelium, presumably enabling pathogens to break through this first natural barrier and thereby increase the risk of pyometra development. PMID:25481489

  10. Application potential of toll-like receptors in cancer immunotherapy

    PubMed Central

    Shi, Ming; Chen, Xi; Ye, Kangruo; Yao, Yuanfei; Li, Yu

    2016-01-01

    Abstract Toll-like receptors (TLRs), as the most important pattern recognition receptors in innate immunity, play a pivotal role in inducing immune response through recognition of microbial invaders or specific agonists. Recent studies have suggested that TLRs could serve as important regulators in the development of a variety of cancer. However, increasing evidences have shown that TLRs may display quite opposite outcomes in cancer development. Although several potential therapeutic Toll-like receptor ligands have been found, the mechanism and therapy prospect of TLRs in cancer development has to be further elucidated to accelerate the clinical application. By performing a systematic review of the present findings on TLRs in cancer immunology, we attempted to evaluate the therapeutic potential of TLRs in cancer therapy and elucidate the potential mechanism of cancer progress regulated by TLR signaling and the reported targets on TLRs for clinical application. An electronic databases search was conducted in PubMed, Chinese Scientific Journal Database, and Chinese Biomedical Literature Database from their inception to February 1, 2016. The following keywords were used to search the databases: Toll-like receptors, cancer therapy, therapeutic target, innate immunity. Of 244 studies that were identified, 97 nonrelevant studies were excluded. In total, 147 full-text articles were assessed, and from these, 54 were excluded as they did not provide complete key information. Thus, 93 studies were considered eligible and included in the analysis. According to the data from the included trials, 14 TLR ligands (77.8%) from 82 studies have been demonstrated to display antitumor property in various cancers, whereas 4 ligands (22.2%) from 11 studies promote tumors. Among them, only 3 TLR ligands have been approved for cancer therapy, and 9 ligands were in clinical trials. In addition, the potential mechanism of recently reported targets on TLRs for clinical application was also

  11. Innate Immune Regulation by Toll-Like Receptors in the Brain

    PubMed Central

    Mallard, Carina

    2012-01-01

    The innate immune system plays an important role in cerebral health and disease. In recent years the role of innate immune regulation by toll-like receptors in the brain has been highlighted. In this paper the expression of toll-like receptors and endogenous toll-like receptor ligands in the brain and their role in cerebral ischemia will be discussed. Further, the ability of systemic toll-like receptor ligands to induce cerebral inflammation will be reviewed. Finally, the capacity of toll-like receptors to both increase (sensitization) and decrease (preconditioning/tolerance) the vulnerability of the brain to damage will be disclosed. Studies investigating the role of toll-like receptors in the developing brain will be emphasized. PMID:23097717

  12. Assembly and localization of Toll-like receptor signalling complexes.

    PubMed

    Gay, Nicholas J; Symmons, Martyn F; Gangloff, Monique; Bryant, Clare E

    2014-08-01

    Signal transduction by the Toll-like receptors (TLRs) is central to host defence against many pathogenic microorganisms and also underlies a large burden of human disease. Thus, the mechanisms and regulation of signalling by TLRs are of considerable interest. In this Review, we discuss the molecular basis for the recognition of pathogen-associated molecular patterns, the nature of the protein complexes that mediate signalling, and the way in which signals are regulated and integrated at the level of allosteric assembly, post-translational modification and subcellular trafficking of the components of the signalling complexes. These fundamental molecular mechanisms determine whether the signalling output leads to a protective immune response or to serious pathologies such as sepsis. A detailed understanding of these processes at the molecular level provides a rational framework for the development of new drugs that can specifically target pathological rather than protective signalling in inflammatory and autoimmune disease. PMID:25060580

  13. Current Views of Toll-Like Receptor Signaling Pathways

    PubMed Central

    Yamamoto, Masahiro; Takeda, Kiyoshi

    2010-01-01

    On microbial invasion, the host immediately evokes innate immune responses. Recent studies have demonstrated that Toll-like receptors (TLRs) play crucial roles in innate responses that lead not only to the clearance of pathogens but also to the efficient establishment of acquired immunity by directly detecting molecules from microbes. In terms of intracellular TLR-mediated signaling pathways, cytoplasmic adaptor molecules containing Toll/IL-1R (TIR) domains play important roles in inflammatory immune responses through the production of proinflammatory cytokines, nitric oxide, and type I interferon, and upregulation of costimulatory molecules. In this paper, we will describe our current understanding of the relationship between TLRs and their ligands derived from pathogens such as viruses, bacteria, fungi, and parasites. Moreover, we will review the historical and current literature to describe the mechanisms behind TLR-mediated activation of innate immune responses. PMID:21197425

  14. Toll-like receptors and diabetes complications: recent advances.

    PubMed

    Rosa Ramirez, Sandra; Ravi Krishna Dasu, Mohan

    2012-11-01

    Diabetes mellitus (DM) is a disease with constellation of metabolic aberrations resulting in debilitating complications. The prevalence of DM worldwide was 2.8% (171 million people) in 2000 and estimated to be at 4.4% (366 million people) in 2030. DM is a major risk factor for heart, kidney diseases, and lower limb amputations. Emerging in vitro and in vivo data suggest that systemic inflammation plays a role in the pathogenesis of DM complications via innate immune receptors. Toll-like receptors (TLRs) are key innate immune receptors that mediate the inflammatory responses in DM. There are no reviews that collectively summarize and examine the detrimental role of TLRs in the manifestation of DM complications namely heart disease, nephropathy, neuropathy, and wound healing. Thus, in this review, we will provide summaries of the TLR expression and activation and elucidate their role in propagating inflammation seen in DM complications. PMID:22934553

  15. Toll-like receptors in antiviral innate immunity

    PubMed Central

    Lester, Sandra N.; Li, Kui

    2014-01-01

    Toll-like receptors (TLRs) are fundamental sensor molecules of the host innate immune system, which detect conserved molecular signatures of a wide range of microbial pathogens and initiate innate immune responses via distinct signaling pathways. Various TLRs are implicated in the early interplay of host cells with invading viruses, which regulates viral replication and/or host responses, ultimately impacting on viral pathogenesis. To survive the host innate defense mechanisms, many viruses have developed strategies to evade or counteract signaling through the TLR pathways, creating an advantageous environment for their propagation. Here we review the current knowledge of the roles TLRs play in antiviral innate immune responses, discuss examples of TLR-mediated viral recognition, and describe strategies used by viruses to antagonize the host antiviral innate immune responses. PMID:24316048

  16. Degranulation of Paneth Cells via Toll-Like Receptor 9

    PubMed Central

    Rumio, Cristiano; Besusso, Dario; Palazzo, Marco; Selleri, Silvia; Sfondrini, Lucia; Dubini, Francesco; Ménard, Sylvie; Balsari, Andrea

    2004-01-01

    The release of antimicrobial peptides and growth factors by Paneth cells is thought to play an important role in protecting the small intestine, but the mechanisms involved have remained obscure. Immunohistochemistry and immunofluorescence showed that Paneth cells express Toll-like receptor 9 (TLR9) in the granules. Injection of mice with oligonucleotides containing CpG sequence (CpG-ODNs) led to a down-modulation of TLR9 and a striking decrease in the number of large secretory granules, consistent with degranulation. Moreover CpG-ODN treatment increased resistance to oral challenge with virulent Salmonella typhimurium. Moreover, our findings demonstrate a sentinel role for Paneth cells through TLR9. PMID:15277213

  17. Nucleic acid recognizing Toll-like receptors and autoimmunity.

    PubMed

    von Landenberg, Philipp; Bauer, Stefan

    2007-12-01

    The understanding of autoimmune diseases experienced an impressive boost since the Toll-like receptors (TLRs) have been identified as possible key players in autoimmune pathophysiology. Although these receptors recognize a variety of structures derived from viruses, bacteria, and fungi leading to subsequent initiation of the relevant immune responses, recent data support the idea that TLRs are crucial in the induction and perpetuation of certain autoimmune diseases, especially the systemic lupus erythematosus (SLE). In this review, we will summarize recent data on involvement of TLRs in the development of autoimmune diseases. We will focus on TLRs 7, 8, and 9 that were originally identified as receptors specific for bacterial and viral RNA/DNA, but more recent in vitro and in vivo studies have linked these receptors to the detection of host RNA, DNA, and RNA-associated or DNA-associated proteins in the context of autoimmunity. PMID:18060756

  18. Antiinfective applications of toll-like receptor 9 agonists.

    PubMed

    Krieg, Arthur M

    2007-07-01

    The innate immune system detects pathogens by the presence of highly conserved pathogen-expressed molecules, which trigger host immune defenses. Toll-like receptor (TLR) 9 detects unmethylated CpG dinucleotides in bacterial or viral DNA, and can be stimulated for therapeutic applications with synthetic oligodeoxynucleotides containing immune stimulatory "CpG motifs." TLR9 activation induces both innate and adaptive immunity. The TLR9-induced innate immune activation can be applied in the prevention or treatment of infectious diseases, and the adaptive immune-enhancing effects can be harnessed for improving vaccines. This article highlights the current understanding of the mechanism of action of CpG oligodeoxynucleotides, and provides an overview of the preclinical data and early human clinical trial results, applying these TLR9 agonists in the field of infectious diseases. PMID:17607015

  19. Reprint of: Microglial toll-like receptors and Alzheimer's disease.

    PubMed

    Su, Fan; Bai, Feng; Zhou, Hong; Zhang, Zhijun

    2016-07-01

    Microglial activation represents an important pathological hallmark of Alzheimer's disease (AD), and emerging data highlight the involvement of microglial toll-like receptors (TLRs) in the course of AD. TLRs have been observed to exert both beneficial and detrimental effects on AD-related pathologies, and transgenic animal models have provided direct and credible evidence for an association between TLRs and AD. Moreover, analyses of genetic polymorphisms have suggested interactions between genetic polymorphisms in TLRs and AD risk, further supporting the hypothesis that TLRs are involved in AD. In this review, we summarize the key evidence in this field. Future studies should focus on exploring the mechanisms underlying the potential roles of TLRs in AD. PMID:27255539

  20. Toll-like receptor signaling and regulation of intestinal immunity.

    PubMed

    Kamdar, Karishma; Nguyen, Vivien; DePaolo, R William

    2013-04-01

    The intestine is a complex organ that must maintain tolerance to innocuous food antigens and commensal microbiota while being also able to mount inflammatory responses against invading pathogenic microorganisms. The ability to restrain tolerogenic responses while permitting inflammatory responses requires communication between commensal bacteria, intestinal epithelial cells and immune cells. Disruption or improper signaling between any of these factors may lead to uncontrolled inflammation and the development of inflammatory diseases. Toll-like receptors (TLR) recognize conserved molecular motifs of microorganisms and, not surprisingly, are important for maintaining tolerance to commensal microbiota, as well as inducing inflammation against pathogens. Perturbations in individual TLR signaling can lead to a number of different outcomes and illustrate a system of regulation within the intestine in which each TLR plays a largely non-redundant role in mucosal immunity. This review will discuss recent findings on the roles of individual TLRs and intestinal homeostasis. PMID:23334153

  1. Toll-like receptor activation of XBP1 regulates innate immune responses in macrophages

    PubMed Central

    Martinon, Fabio; Chen, Xi; Lee, Ann-Hwee; Glimcher, Laurie H.

    2011-01-01

    Sensors of pathogens, such as Toll-like receptors (TLRs), detect microbes to activate transcriptional programs that orchestrate adaptive responses to specific insults. Here we report that TLR4 and TLR2 specifically activated the endoplasmic reticulum (ER)-stress sensor kinase IRE1α and its downstream target, the transcription factor XBP1. Previously described XBP1 ER stress target genes were not induced by TLR signaling. Instead, TLR-activated XBP1 was required for optimal and sustained production of proinflammatory cytokines in macrophages. Consistent with this finding, IRE1α activation by ER-stress synergized with TLR activation for cytokine production. Moreover, XBP1 deficiency markedly increased bacterial burden in animals infected with the TLR2-activating human pathogen Francisella tularensis. Our findings uncover an unsuspected critical new function for the XBP1 transcription factor in mammalian host defenses. PMID:20351694

  2. Innate Immune Sensing by Toll-like Receptors in Newborns and the Elderly

    PubMed Central

    Kollmann, Tobias R.; Levy, Ofer; Montgomery, Ruth R.; Goriely, Stanislas

    2012-01-01

    Summary Given the "inborn" nature of the innate immune system, it is surprising to find that innate immune function does in fact change with age. Similar patterns of distinct Toll-like receptor (TLR)-mediated immune responses come to light when one contrasts innate immune development at the beginning of life with that toward the end of life. Importantly, these developmental patterns of innate cytokine responses correlate with clinical patterns of susceptibility to disease: A heightened risk of suffering from excessive inflammation is often detected in prematurely born infants, disappears over the first few months of life, and reappears toward the end of life. In addition, risk periods for particular infections in early life reemerge in older adults. The near-mirror-image patterns that emerge in contrasts of early versus late innate immune ontogeny emphasize changes in host-environment interactions as the underlying molecular and teleologic drivers. PMID:23159225

  3. The Role of Toll-Like Receptor 4 in Infectious and Noninfectious Inflammation

    PubMed Central

    Molteni, Monica; Gemma, Sabrina

    2016-01-01

    Toll-like receptor 4 (TLR4) belongs to the family of pattern recognition receptors (PRRs). They are highly conserved receptors that recognize conserved pathogen-associated molecular patterns (PAMPs), thus representing the first line of defense against infections. TLR4 has been long recognized as the sensing receptor for gram-negative lipopolysaccharide (LPS). In addition, it also binds endogenous molecules produced as a result of tissue injury. Hence, TLR4 represents a key receptor on which both infectious and noninfectious stimuli converge to induce a proinflammatory response. TLR4-mediated inflammation, triggered by exogenous or endogenous ligands, is also involved in several acute and chronic diseases, having a pivotal role as amplifier of the inflammatory response. This review focuses on the research progress about the role of TLR4 activation in infectious and noninfectious (e.g., sterile) inflammation and the effects of TLR4 signaling in some pathological conditions. PMID:27293318

  4. Toll-like receptors in autoimmunity with special reference to systemic lupus erythematosus.

    PubMed

    Pradhan, Vandana D; Das, Swaptagni; Surve, Prathamesh; Ghosh, Kanjaksha

    2012-05-01

    The Toll-like receptor (TLR) family plays a fundamental role in host innate immunity by mounting a rapid and potent inflammatory response to pathogen infection. TLRs recognize distinct microbial components and activate intracellular signaling pathways that induce expression of host inflammatory genes. Several studies have indicated that TLRs are implicated in many inflammatory and immune disorders. Extensive research in the past decade to understand TLR-mediated mechanisms of innate immunity has enabled pharmaceutical companies to begin to develop novel therapeutics for the purpose of controlling an inflammatory disease. The roles of TLRs in the development of autoimmune diseases have been studied. TLR7 and TLR9 have key roles in production of autoantibodies and/or in development of systemic autoimmune disease. It remains to be determined their role in apoptosis, in the pathogenesis of RNA containing immune complexes, differential expression of TLRs by T regulatory cells. PMID:23162288

  5. Single nucleotide polymorphisms of Toll-like receptors and susceptibility to infectious diseases

    PubMed Central

    Skevaki, C; Pararas, M; Kostelidou, K; Tsakris, A; Routsias, J G

    2015-01-01

    Toll-like receptors (TLRs) are the best-studied family of pattern-recognition receptors (PRRs), whose task is to rapidly recognize evolutionarily conserved structures on the invading microorganisms. Through binding to these patterns, TLRs trigger a number of proinflammatory and anti-microbial responses, playing a key role in the first line of defence against the pathogens also promoting adaptive immunity responses. Growing amounts of data suggest that single nucleotide polymorphisms (SNPs) on the various human TLR proteins are associated with altered susceptibility to infection. This review summarizes the role of TLRs in innate immunity, their ligands and signalling and focuses on the TLR SNPs which have been linked to infectious disease susceptibility. PMID:25560985

  6. 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.

  7. The acylation state of mycobacterial lipomannans modulates innate immunity response through toll-like receptor 2.

    PubMed

    Gilleron, Martine; Nigou, Jérôme; Nicolle, Delphine; Quesniaux, Valérie; Puzo, Germain

    2006-01-01

    Detection of Mycobacterium tuberculosis antigens by professional phagocytes via toll-like receptors (TLR) contributes to controlling chronic M. tuberculosis infection. Lipomannans (LM), which are major lipoglycans of the mycobacterial envelope, were recently described as agonists of TLR2 with potent activity on proinflammatory cytokine regulation. LM correspond to a heterogeneous population of acyl- and glyco-forms. We report here the purification and the complete structural characterization of four LM acyl-forms from Mycobacterium bovis BCG using MALDI MS and 2D (1)H-(31)P NMR analyses. All this biochemical work provided the tools to investigate the implication of LM acylation degree on its proinflammatory activity. The latter was ascribed to the triacylated LM form, essentially an agonist of TLR2, using TLR2/TLR1 heterodimers for signaling. Altogether, these findings shed more light on the molecular basis of LM recognition by TLR. PMID:16426970

  8. MicroRNAs: New Regulators of Toll-Like Receptor Signalling Pathways

    PubMed Central

    He, Xiaobing; Jing, Zhizhong; Cheng, Guofeng

    2014-01-01

    Toll-like receptors (TLRs), a critical family of pattern recognition receptors (PRRs), are responsible for the innate immune responses via signalling pathways to provide effective host defence against pathogen infections. However, TLR-signalling pathways are also likely to stringently regulate tissue maintenance and homeostasis by elaborate modulatory mechanisms. MicroRNAs (miRNAs) have emerged as key regulators and as an essential part of the networks involved in regulating TLR-signalling pathways. In this review, we highlight our understanding of the regulation of miRNA expression profiles by TLR-signalling pathways and the regulation of TLR-signalling pathways by miRNAs. We focus on the roles of miRNAs in regulating TLR-signalling pathways by targeting multiple molecules, including TLRs themselves, their associated signalling proteins and regulatory molecules, and transcription factors and functional cytokines induced by them, at multiple levels. PMID:24772440

  9. CPG-7909 (PF-3512676, ProMune): toll-like receptor-9 agonist in cancer therapy.

    PubMed

    Murad, Yanal M; Clay, Timothy M; Lyerly, H Kim; Morse, Michael A

    2007-08-01

    Stimulation of toll-like receptor (TLR)9 activates human plasmacytoid dendritic cells and B cells, and induces potent innate immune responses in preclinical tumor models and in patients. CpG oligodeoxynucleotides (ODNs) are TLR9 agonists that show promising results as vaccine adjuvants and in the treatment of cancers, infections, asthma and allergy. PF-3512676 (ProMune) was developed as a TLR9 agonist for the treatment of cancer as monotherapy and as an adjuvant in combination with chemo- and immunotherapy. Phase I and II trials have tested this drug in several hematopoietic and solid tumors. Pfizer has initiated Phase III trials to test PF-3512676 in combination with standard chemotherapy for non-small-cell lung cancer. PMID:17696823

  10. Trypanosoma cruzi and its components as exogenous mediators of inflammation recognized through Toll-like receptors.

    PubMed Central

    Campos, Marco A; Gazzinelli, Ricardo T

    2004-01-01

    Trypanosoma cruzi is the etiologic agent of Chagas' disease, a parasitic disease of enormous importance in Latin America. Herein we review the studies that revealed the receptors from innate immunity that are involved in the recognition of this protozoan parasite. We showed that the recognition of T. cruzi and its components occurs through Toll-like receptors (TLR) 2/CD14. Further, we showed in vivo the importance of the myeloid differentiation factor (MyD88), an adapter protein essential for the function of TLRs, in determining the parasitemia and mortality rate of mice infected with T. cruzi. We also discuss the implications of these findings in the pathophysiology of Chagas' disease. PMID:15223603

  11. Adaptors in toll-like receptor signaling and their potential as therapeutic targets.

    PubMed

    Ve, Thomas; Gay, Nicholas J; Mansell, Ashley; Kobe, Bostjan; Kellie, Stuart

    2012-10-01

    To initiate the innate immune response, Toll-like receptors (TLRs) associate with cytoplasmic adaptor proteins through TIR (Toll/interleukin-1 receptor) domain interactions. The four principal signaling adaptor proteins include MyD88, MAL, TRIF and TRAM, and the fifth protein SARM, involved in negative regulation of TLR pathways, is usually considered a part of the TIR domain-containing adaptor protein group. Other TIR domain-containing proteins have also been shown to regulate these signaling pathways, including ST2 and SIGIRR, as well as several bacterial and viral TIR domain-containing proteins that modulate these pathways as virulence factors. TLR pathways and the adaptor proteins are associated with a number of diseases, including infection, sepsis, inflammatory, allergic and autoimmune diseases and cancer. We review our current understanding of the structure and function of adaptor proteins and their regulatory proteins, their association with disease and their potential as therapeutic targets in human disease. PMID:22664090

  12. Lipopolysaccharides belonging to different Salmonella serovars are differentially capable of activating Toll-like receptor 4.

    PubMed

    Chessa, Daniela; Spiga, Luisella; De Riu, Nicola; Delaconi, Paola; Mazzarello, Vittorio; Ganau, Giulia; Rubino, Salvatore

    2014-11-01

    Salmonella enterica subsp. enterica serovar (serotype) Abortusovis is a member of the Enterobacteriaceae. This serotype is naturally restricted to ovine species and does not infect humans. Limited information is available about the immune response of sheep to S. Abortusovis. S. Abortusovis, like Salmonella enterica subsp. enterica serovar Typhi, causes a systemic infection in which, under natural conditions, animals are not able to raise a rapid immune response. Failure to induce the appropriate response allows pathogens to reach the placenta and results in an abortion. Lipopolysaccharides (LPSs) are pathogen-associated molecular patterns (PAMPs) that are specific to bacteria and are not synthesized by the host. Toll-like receptors (TLRs) are a family of receptors that specifically recognize PAMPs. As a first step, we were able to identify the presence of Toll-like receptor 4 (TLR4) on the ovine placenta by using an immunohistochemistry technique. To our knowledge, this is the first work describing the interaction between S. Abortusovis LPS and TLR4. Experiments using an embryonic cell line (HEK293) transfected with human and ovine TLR4s showed a reduction of interleukin 8 (IL-8) production by S. Abortusovis and Salmonella enterica subsp. enterica serovar Paratyphi upon LPS stimulation compared to Salmonella enterica subsp. enterica serovar Typhimurium. Identical results were observed using heat-killed bacteria instead of LPS. Based on data obtained with TLR4 in vitro stimulation, we demonstrated that the serotype S. Abortusovis is able to successfully evade the immune system whereas S. Typhimurium and other serovars fail to do so. PMID:25135686

  13. Bacterial lipopolysaccharide induces increased expression of toll-like receptor (TLR) 4 and downstream TLR signaling molecules in bovine mammary epithelial cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine mammary epithelial cells contribute to the innate immune response to intramammary infections by recognizing pathogens through specialized pattern recognition receptors. Toll-like receptor 4 (TLR4) is one such receptor that binds and is activated by lipopolysaccharide (LPS), a component of the...

  14. Escherichia coli lipopolysaccharide upregulates the expression of both toll like receptor 4 and 2 (TLR4 and TLR2) in cultured bovine mammary epithelial cells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Bovine mammary epithelial cells contribute to the innate immune response to intramammary infection. Their ability to mount such a response is dependent upon mammary epithelial recognition of the invading pathogen by specialized receptors. Toll-like receptor 4 (TLR4) is one such receptor that recog...

  15. The influence of immunogenomics on the innate immune response to avian influenza-comparison of toll-like receptor 7 and cytokine responses between chickens and ducks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The early responses of the innate host defense are dedicated to the containment of pathogens, holding infections to a level that can be resolved by the ensuing acquired immune mechanisms. Toll-like receptor (TLR) family members are responsible for initiation of the innate immune response. In parti...

  16. [The correlation study between the changes of intestinal mucosa predominant bacteria and Toll-like receptor 2, Toll-like receptor 4 gene expressions in diarrhea-predominant irritable bowel syndrome patients].

    PubMed

    Guo, W T; Liu, P; Dong, L N; Wang, J P

    2016-07-01

    Based on high throughput sequencing and PCR detection technology, this study has found out that intestinal microbial diversity was impaired and the quantities of two main bacteria flora (Bacteroidetes and Clostridium) were significantly reduced in patients with diarrhea-predominant irritable bowel syndrome (D-IBS). Meanwhile mucosal expression of toll-like receptor (TLR) 2 and TLR4 were significantly enhanced, which was inversely correlated with the reduction of Bacteroidetes and Clostridium. Thus, it suggests that D-IBS may be associated with TLR signal transduction triggered by the intestinal dysbacteriosis. PMID:27373290

  17. Toll-like receptor signalling and their therapeutic targeting in colorectal cancer.

    PubMed

    Moossavi, Shirin; Rezaei, Nima

    2013-06-01

    Intestinal homeostasis is dependent on the proper host/microbiota interaction via pattern recognition receptors. Toll-like receptors are a specialised group of membrane receptors which detect pathogen-associated conserved structures. They are present in the intestinal tract and are required for intestinal homeostasis. Dysregulation in the Toll-like receptor signalling can conceivably result in a dysregulated immune response which could contribute to major intestinal pathologies including colorectal cancer. Evidence for the role of microbiota and toll-like receptors in colorectal cancer is emerging. In this report the evidence for the contribution of toll-like receptors to the pathogenesis of colorectal cancer; potential mechanisms affecting toll-like receptor signalling; and their therapeutic targeting in colorectal cancer are reviewed. PMID:23602501

  18. Allergens and Activation of the Toll-Like Receptor Response.

    PubMed

    Monie, Tom P; Bryant, Clare E

    2016-01-01

    Pattern recognition receptors (PRRs) provide a crucial function in the detection of exogenous and endogenous danger signals. The Toll-like receptors (TLRs) were the first family of PRRs to be discovered and have been extensively studied since. Whilst TLRs remain the best characterized family of PRRs there is still much to be learnt about their mode of activation and the mechanisms of signal transduction they employ. Much of our understanding of these processes has been gathered through the use of cell based signaling assays utilizing specific gene-reporters or cytokine secretion based readouts. More recently it has become apparent that the repertoire of ligands recognized by these receptors may be wider than originally assumed and that their activation may be sensitized, or at least modulated by the presence of common household allergens such as the cat dander protein Fel d 1, or the house dust mite allergen Der p 2. In this chapter we provide an overview of the cell culture and stimulation processes required to study TLR signaling in HEK293 based assays and in bone marrow-derived macrophages. PMID:26803639

  19. Toll-like receptors: potential targets for lupus treatment

    PubMed Central

    Wu, Yan-wei; Tang, Wei; Zuo, Jian-ping

    2015-01-01

    Systemic lupus erythematosus (SLE) is a complex autoimmune disease characterized by the loss of tolerance to self-nuclear antigens. Accumulating evidence shows that Toll-like receptors (TLRs), previously proven to be critical for host defense, are implicated in the pathogenesis of autoimmune diseases by recognition of self-molecules. Genome-wide association studies, experimental mouse models and clinical sample studies have provided evidence for the involvement of TLRs, including TLR2/4, TLR5, TLR3 and TLR7/8/9, in SLE pathogenesis. A number of downstream proteins in the TLR signaling cascade (such as MyD88, IRAKs and IFN-α) are identified as potential therapeutic targets for SLE treatment. Numerous antagonists targeting TLR signaling, including oligonucleotides, small molecular inhibitors and antibodies, are currently under preclinical studies or clinical trials for SLE treatment. Moreover, the emerging new manipulation of TLR signaling by microRNA (miRNA) regulation shows promise for the future treatment of SLE. PMID:26592511

  20. Toll-Like Receptor 9 in Breast Cancer

    PubMed Central

    Sandholm, Jouko; Selander, Katri S.

    2014-01-01

    Toll-like receptor 9 (TLR9) is a cellular DNA receptor of the innate immune system. DNA recognition via TLR9 results in an inflammatory reaction, which eventually also activates a Th1-biased adaptive immune attack. In addition to cells of the immune system, TLR9 mRNA and protein are also widely expressed in breast cancer cell lines and in clinical breast cancer specimens. Although synthetic TLR9-ligands induce cancer cell invasion in vitro, the role of TLR9 in cancer pathophysiology has remained unclear. In the studies conducted so far, tumor TLR9 expression has been shown to have prognostic significance only in patients that have triple-negative breast cancer (TNBC). Specifically, high tumor TLR9 expression predicts good prognosis among TNBC patients. Pre-clinical studies suggest that TLR9 expression may affect tumor immunophenotype and contribute to the immunogenic benefit of chemotherapy. In this review, we discuss the possible contribution of tumor TLR9 to the pathogenesis and treatment responses in breast cancer. PMID:25101078

  1. Cathepsins are required for Toll-like receptor 9 responses

    SciTech Connect

    Matsumoto, Fumi; Saitoh, Shin-ichiroh; Fukui, Ryutaroh; Kobayashi, Toshihiko; Tanimura, Natsuko; Konno, Kazunori; Kusumoto, Yutaka; Akashi-Takamura, Sachiko; Miyake, Kensuke

    2008-03-14

    Toll-like receptors (TLR) recognize a variety of microbial products and activate defense responses. Pathogen sensing by TLR2/4 requires accessory molecules, whereas little is known about a molecule required for DNA recognition by TLR9. After endocytosis of microbes, microbial DNA is exposed and recognized by TLR9 in lysosomes. We here show that cathepsins, lysosomal cysteine proteases, are required for TLR9 responses. A cell line Ba/F3 was found to be defective in TLR9 responses despite enforced TLR9 expression. Functional cloning with Ba/F3 identified cathepsin B/L as a molecule required for TLR9 responses. The protease activity was essential for the complementing effect. TLR9 responses were also conferred by cathepsin S or F, but not by cathepsin H. TLR9-dependent B cell proliferation and CD86 upregulation were apparently downregulated by cathepsin B/L inhibitors. Cathepsin B inhibitor downregulated interaction of CpG-B with TLR9 in 293T cells. These results suggest roles for cathepsins in DNA recognition by TLR9.

  2. Toll-Like Receptor Pathways in Autoimmune Diseases.

    PubMed

    Chen, Ji-Qing; Szodoray, Peter; Zeher, Margit

    2016-02-01

    Autoimmune diseases are a family of chronic systemic inflammatory disorders, characterized by the dysregulation of the immune system which finally results in the break of tolerance to self-antigen. Several studies suggest that Toll-like receptors (TLRs) play an essential role in the pathogenesis of autoimmune diseases. TLRs belong to the family of pattern recognition receptors (PRRs) that recognize a wide range of pathogen-associated molecular patterns (PAMPs). TLRs are type I transmembrane proteins and located on various cellular membranes. Two main groups have been classified based on their location; the extracelluar group referred to the ones located on the plasma membrane while the intracellular group all located in endosomal compartments responsible for the recognition of nucleic acids. They are released by the host cells and trigger various intracellular pathways which results in the production of proinflammatory cytokines, chemokines, as well as the expression of co-stimulatory molecules to protect against invading microorganisms. In particular, TLR pathway-associated proteins, such as IRAK, TRAF, and SOCS, are often dysregulated in this group of diseases. TLR-associated gene expression profile analysis together with single nucleotide polymorphism (SNP) assessment could be important to explain the pathomechanism driving autoimmune diseases. In this review, we summarize recent findings on TLR pathway regulation in various autoimmune diseases, including Sjögren's syndrome (SS), systemic lupus erythematosus (SLE), multiple sclerosis (MS), rheumatoid arthritis (RA), systemic sclerosis (SSc), and psoriasis. PMID:25687121

  3. Tyrosine Phosphorylation in Toll-Like Receptor Signaling

    PubMed Central

    Chattopadhyay, Saurabh; Sen, Ganes C.

    2014-01-01

    There is a wealth of knowledge about how different Ser/Thr protein kinases participate in Toll-like receptor (TLR) signaling. In many cases, we know the identities of the Ser/Thr residues of various components of the TLR-signaling pathways that are phosphorylated, the functional consequences of the phosphorylation and the responsible protein kinases. In contrast, the analysis of Tyr-phosphorylation of TLRs and their signaling proteins is currently incomplete, because several existing analyses are not systematic or they do not rely on robust experimental data. Nevertheless, it is clear that many TLRs require, for signaling, ligand-dependent phosphorylation of specific Tyr residues in their cytoplasmic domains; the list includes TLR2, TLR3, TLR4, TLR5, TLR8 and TLR9. In this article, we discuss the current status of knowledge on the effect of Tyr-phosphorylation of TLRs and their signaling proteins on their biochemical and biological functions, the possible identities of the relevant protein tyrosine kinases (PTKs) and the nature of regulations of PTK-mediated activation of TLR signaling pathways. PMID:25022196

  4. Selective Toll-Like Receptor Expression in Human Fetal Lung

    PubMed Central

    Petrikin, Joshua E; Gaedigk, Roger; Leeder, J Steven; Truog, William E

    2010-01-01

    Toll-like receptors (TLRs) are critical components of the innate immune system, acting as pattern recognition molecules and triggering an inflammatory response. TLR associated gene products are of interest in modulating inflammatory related pulmonary diseases of the neonate. The ontogeny of TLR related genes in human fetal lung has not been previously described and could elucidate additional functions and identify strategies for attenuating the effects of fetal inflammation. We examined the expression of 84 TLR related genes on 23 human fetal lung samples from three groups with estimated ages of 60 (57-59d), 90 (89-91d), and 130 (117-154d) days. Using a false detection rate algorithm, we identified 32 genes displaying developmental regulation with TLR2 having the greatest up-regulation of TLR genes (9.2 fold increase) and TLR4 unchanged. We confirmed the TLR2 up-regulation by examining an additional 133 fetal lung tissue samples with a fluorogenic polymerase chain reaction assay (TaqMan®) and found an exponential best-fit curve over the time studied. The best-fit curve predicts a 6.1 fold increase from 60d to 130d. We conclude that TLR2 is developmentally expressed from the early pseudoglandular stage of lung development to the canalicular stage. PMID:20581745

  5. [Negative regulation of Toll-like receptor signalling].

    PubMed

    Antosz, Halina; Choroszyńska, Dorota

    2013-01-01

    The mechanism of innate immunity is based on the pattern recognition receptors (PRR) that recognize molecular patterns associated with pathogens (PAMPs). Among PRR receptors Toll-like receptors (TLR) are distinguished. As a result of contact with pathogens, TLRs activate specific intracellular signaling pathways. It happens through proteins such as adaptor molecules, e.g. MyD88, TIRAP, TRIF, TRAM, and IPS-1, which participate in the cascade activation of kinases (IKK, MAP, RIP-1, TBK-1) as well as transcription factors (NF-κB, AP-1) and regulatory factor (IRF3). The result of this activation is the production of active proinflammatory cytokines, chemokines, interferons and enzymes. The PRR pathways are controlled by extra- and intracellular molecules to prevent overexpression of PRR. They include soluble receptors (sTLR), transmembrane proteins (ST2, SIGIRR, RP105, TRAIL-R) and intracellular inhibitors (SOCS-1, SOCS-3, sMyD88, TOLLIP, IRAK-M, SARM, A20, β-arrestin, CYLD, SHP). These molecules maintain the balance between activation and inhibition and ensure balancing of the beneficial and adverse effects of antigen recognition. PMID:23619234

  6. DIFFERENTIAL TOLL-LIKE RECEPTOR ACTIVATION IN LUNG ISCHEMIA REPERFUSION INJURY

    PubMed Central

    Phelan, Patrick; Merry, Heather E.; Hwang, Billanna; Mulligan, Michael S.

    2015-01-01

    Objective The requirement for toll-like receptors in lung ischemia reperfusion injury (LIRI) has been demonstrated but not fully characterized. We have previously reported that toll-like receptor-4 is required by alveolar macrophages but not pulmonary endothelial or epithelial cells for the development of LIRI. Additionally, we have demonstrated differential patterns of mitogen-activated protein kinase activation and cytokine release in these cell types during LIRI. We sought to determine whether the differences in their activation responses related to cell specific toll-like receptor activation requirements. Methods Primary cultures of alveolar macrophages, pulmonary endothelial, and immortalized epithelial cells were pretreated with toll-like receptor-2 or -4 short interference (si)RNA prior to hypoxia and reoxygenation. Cell lysates and media were analyzed for receptor knockdown, mitogen-activated protein kinase activation, and cytokine production. Rats were pretreated with toll-like receptor-2 or -4 siRNA prior to lung ischemia reperfusion and changes in lung vascular permeability were assessed. Results Toll-like receptor-2 knockdown in alveolar macrophages did not affect mitogen-activated protein kinase phosphorylation or cytokine secretion. Conversely, toll-like receptor-2 knockdown in pulmonary endothelial and epithelial cells demonstrated significant reductions in ERK 1/2 activation and cytokine secretion. Toll-like receptor-4, but not toll-like receptor-2, decreased lung permeability index in LIRI. Conclusions Differential toll-like receptor signaling and mitogen-activated protein kinase activation in response to LIRI appear to be cell specific. siRNA provides an outstanding tool for examination of the underlying mechanism. PMID:25911179

  7. Structural characterisation of Toll-like receptor 1 (TLR1) and Toll-like receptor 6 (TLR6) in elephant and harbor seals.

    PubMed

    Woodman, Sally; Gibson, Amanda J; García, Ana Rubio; Contreras, Guillermo Sanchez; Rossen, John W; Werling, Dirk; Offord, Victoria

    2016-01-01

    Pinnipeds are a diverse clade of semi-aquatic mammals, which act as key indicators of ecosystem health. Their transition from land to marine environments provides a complex microbial milieu, making them vulnerable to both aquatic and terrestrial pathogens, thereby contributing to pinniped population decline. Indeed, viral pathogens such as influenza A virus and phocine distemper virus (PDV) have been identified as the cause of several of these mass mortality events. Furthermore, bacterial infection with mammalian Brucella sp. and methicillin-resistant Staphylococcus aureus strains have also been observed in marine mammals, posing further risk to both co-habiting endangered species and public health. During these disease outbreaks, mortality rates have varied amongst different pinniped species. Analyses of innate immune receptors at the host-pathogen interface have previously identified variants which may drive these species-specific responses. Through a combination of both sequence- and structure-based methods, this study characterises members of the Toll-like receptor (TLR) 1 superfamily from both harbour and elephant seals, identifying variations which will help us to understand these species-specific innate immune responses, potentially aiding the development of specific vaccine-adjuvants for these species. PMID:26827833

  8. Deviation from major codons in the Toll-like receptor genes is associated with low Toll-like receptor expression

    PubMed Central

    Zhong, Fei; Cao, Weiping; Chan, Edmund; Tay, Puei Nam; Cahya, Florence Feby; Zhang, Haifeng; Lu, Jinhua

    2005-01-01

    Microbial structures activate Toll-like receptors (TLRs) and TLR-mediated cell signalling elicits and regulates host immunity. Most TLRs are poorly expressed but the underlying expression mechanism is not clear. Examination TLR sequences revealed that most human TLR genes deviated from using major human codons. CD14 resembles TLRs in sequence but its gene preferentially uses major codons. Indeed, CD14 expression on monocytes was higher than expression of TLR1 and TLR2. The TLR9 gene is abundant in major codons and it also showed higher expression than TLR1, TLR2 and TLR7 in transfected 293T cells. Change of the 5′-end 302 base pairs of the TLR2 sequence into major human codons markedly increased TLR2 expression, which led to increased TLR2-mediated constitutive nuclear factor-κB activation. Change of the 5′-end 381 base pairs of the CD14 sequence into prevalent TLR codons markedly reduced CD14 expression. These results collectively show that the deviation of TLR sequences from using major codons dictates the low TLR expression and this may protect the host against excessive inflammation and tissue damages. PMID:15606798

  9. Toll like receptor polymorphisms in allogeneic hematopoietic cell transplantation

    PubMed Central

    Kornblit, Brian; Enevold, Christian; Wang, Tao; Spellman, Stephen; Haagenson, Mike; Lee, Stephanie J; Müller, Klaus

    2014-01-01

    To assess the impact of the genetic variation in toll-like receptors (TLR) on outcome after allogeneic myeloablative conditioning hematopoietic cell transplantation (HCT) we have investigated 29 single nucleotide polymorphisms (SNP) across 10 TLRs in 816 patients and donors. Only donor genotype of TLR8 rs3764879, which is located on the X chromosome, was significantly associated with outcome at the Bonferroni corrected level P≤0.001. Male hemizygosity and female homozygosity for the minor allele were significantly associated with disease free survival (DFS) (hazard ratio (HR) 1.47 (95% confidence interval (CI) 1.16–1.85); P=0.001). Further analysis stratified by donor sex due to confounding by sex, was suggestive for associations with overall survival (male donor: HR 1.41 (95% CI 1.09–1.83), P=0.010); female donor: (HR 2.78 (95% CI 1.43–5.41), P=0.003), DFS (male donor: HR 1.45 (95% CI 1.12–1.87), P=0.005; female donor: HR 2.34 (95% CI 1.18–4.65), P=0.015) and treatment related mortality (male donor: HR 1.49 (95% CI 1.09–2.04), P=0.012; female donor: HR 3.12 (95% CI 1.44–6.74), P=0.004). In conclusion our findings suggest that the minor allele of TLR8 rs3764879 of the donor is associated with outcome after myeloablative conditioned allogeneic HCT. PMID:25464115

  10. Evidence for adaptation of porcine Toll-like receptors.

    PubMed

    Darfour-Oduro, Kwame A; Megens, Hendrik-Jan; Roca, Alfred; Groenen, Martien A M; Schook, Lawrence B

    2016-03-01

    Naturally endemic infectious diseases provide selective pressures for pig populations. Toll-like receptors (TLRs) represent the first line of immune defense against pathogens and are likely to play a crucial adaptive role for pig populations. This study was done to determine whether wild and domestic pig populations representing diverse global environments demonstrate local TLR adaptation. The genomic sequence encoding the ectodomain, responsible for interacting with pathogen ligands of bacterial (TLR1, TLR2 and TLR6) and viral (TLR3, TLR7 and TLR8) receptors, was obtained. Mitochondrial D-loop region sequences were obtained and a phylogenetic analysis using these sequences revealed a clear separation of animals into Asian (n = 27) and European (n = 40) clades. The TLR sequences were then analyzed for population-specific positive selection signatures within wild boars and domesticated pig populations derived from Asian and European clades. Using within-population and between-population tests for positive selection, a TLR2-derived variant 376A (126Thr), estimated to have arisen in 163,000 years ago with a frequency of 83.33% within European wild boars, 98.00% within domestic pig breeds of European origin, 40.00% within Asian wild boars, and 11.36% within Asian domestic pigs, was identified to be under positive selection in pigs of European origin. The variant is located within the N terminal domain of the TLR2 protein 3D crystal structure and could affect ligand binding. This study suggests the TLR2 gene contributing to responses to bacterial pathogens has been crucial in adaptation of pigs to pathogens. PMID:26701185

  11. Toll-like Receptors of the Ascidian Ciona intestinalis

    PubMed Central

    Sasaki, Naoko; Ogasawara, Michio; Sekiguchi, Toshio; Kusumoto, Shoichi; Satake, Honoo

    2009-01-01

    Key transmembrane proteins in the innate immune system, Toll-like receptors (TLRs), have been suggested to occur in the genome of non-mammalian organisms including invertebrates. However, authentic invertebrate TLRs have been neither structurally nor functionally investigated. In this paper, we originally present the structures, localization, ligand recognition, activities, and inflammatory cytokine production of all TLRs of the ascidian Ciona intestinalis, designated as Ci-TLR1 and Ci-TLR2. The amino acid sequence of Ci-TLR1 and Ci-TLR2 were found to possess unique structural organization with moderate sequence similarity to functionally characterized vertebrate TLRs. ci-tlr1 and ci-tlr2 genes were expressed predominantly in the stomach and intestine as well as in hemocytes. Ci-TLR1 and Ci-TLR2 expressed in HEK293 cells, unlike vertebrate TLRs, were localized to both the plasma membrane and endosomes. Intriguingly, both Ci-TLR1 and Ci-TLR2 stimulate NF-κB induction in response to multiple pathogenic ligands such as double-stranded RNA, and bacterial cell wall components that are differentially recognized by respective vertebrate TLRs, revealing that Ci-TLRs recognize broader pathogen-associated molecular patterns than vertebrate TLRs. The Ci-TLR-stimulating pathogenic ligands also induced the expression of Ci-TNFα in the intestine and stomach where Ci-TLRs are expressed. These results provide evidence that the TLR-triggered innate immune systems are essentially conserved in ascidians, and that Ci-TLRs possess “hybrid” biological and immunological functions, compared with vertebrate TLRs. Moreover, it is presumed that chordate TLR ancestors also acquired the Ci-TLR-like multiple cellular localization and pathogen-associated molecular pattern recognition. PMID:19651780

  12. Microbiota regulates type 1 diabetes through Toll-like receptors

    PubMed Central

    Burrows, Michael P.; Volchkov, Pavel; Kobayashi, Koichi S.; Chervonsky, Alexander V.

    2015-01-01

    Deletion of the innate immune adaptor myeloid differentiation primary response gene 88 (MyD88) in the nonobese diabetic (NOD) mouse model of type 1 diabetes (T1D) results in microbiota-dependent protection from the disease: MyD88-negative mice in germ-free (GF), but not in specific pathogen-free conditions develop the disease. These results could be explained by expansion of particular protective bacteria (“specific lineage hypothesis”) or by dominance of negative (tolerizing) signaling over proinflammatory signaling (“balanced signal hypothesis”) in mutant mice. Here we found that colonization of GF mice with a variety of intestinal bacteria was capable of reducing T1D in MyD88-negative (but not wild-type NOD mice), favoring the balanced signal hypothesis. However, the receptors and signaling pathways involved in prevention or facilitation of the disease remained unknown. The protective signals triggered by the microbiota were revealed by testing NOD mice lacking MyD88 in combination with knockouts of several critical components of innate immune sensing for development of T1D. Only MyD88- and TIR-domain containing adapter inducing IFN β (TRIF) double deficient NOD mice developed the disease. Thus, TRIF signaling (likely downstream of Toll-like receptor 4, TLR4) serves as one of the microbiota-induced tolerizing pathways. At the same time another TLR (TLR2) provided prodiabetic signaling by controlling the microbiota, as reduction in T1D incidence caused by TLR2 deletion was reversed in GF TLR2-negative mice. Our results support the balanced signal hypothesis, in which microbes provide signals that both promote and inhibit autoimmunity by signaling through different receptors, including receptors of the TLR family. PMID:26216961

  13. Study of Toll-like receptor gene loci in sarcoidosis

    PubMed Central

    Schürmann, M; Kwiatkowski, R; Albrecht, M; Fischer, A; Hampe, J; Müller-Quernheim, J; Schwinger, E; Schreiber, S

    2008-01-01

    Sarcoidosis is a multi-factorial systemic disease of granulomatous inflammation. Current concepts of the aetiology include interactions of unknown environmental triggers with an inherited susceptibility. Toll-like receptors (TLRs) are main components of innate immunity and therefore TLR genes are candidate susceptibility genes in sarcoidosis. Ten members of the human TLR gene family have been identified and mapped to seven chromosomal segments. The aim of this study was to investigate all known TLR gene loci for genetic linkage with sarcoidosis and to follow positive signals with different methods. We analysed linkage of TLR gene loci to sarcoidosis by use of closely flanking microsatellite markers in 83 families with 180 affected siblings. We found significant linkage between sarcoidosis and markers of the TLR4 gene locus on chromosome 9q (non-parametric linkage score 2·63, P = 0·0043). No linkage was found for the remaining TLR gene loci. We subsequently genotyped 1203 sarcoidosis patients from 997 families, 1084 relatives and 537 control subjects for four single nucleotide polymorphisms of TLR4, including Asp299Gly and Thr399Ile. This genotype data set was studied by case–control comparisons and transmission disequilibrium tests, but showed no significant results. In summary, TLR4 − w ith significant genetic linkage results − appears to be the most promising member of the TLR gene family for further investigation in sarcoidosis. However, our results do not confirm the TLR4 polymorphisms Asp299Gly and Thr399Ile as susceptibility markers. Our results rather point to another as yet unidentified variant within or close to TLR4 that might confer susceptibility to sarcoidosis. PMID:18422738

  14. A Role for the Adaptor Proteins TRAM and TRIF in Toll-like Receptor 2 Signaling*

    PubMed Central

    Nilsen, Nadra J.; Vladimer, Gregory I.; Stenvik, Jørgen; Orning, M. Pontus A.; Zeid-Kilani, Maria V.; Bugge, Marit; Bergstroem, Bjarte; Conlon, Joseph; Husebye, Harald; Hise, Amy G.; Fitzgerald, Katherine A.; Espevik, Terje; Lien, Egil

    2015-01-01

    Toll-like receptors (TLRs) are involved in sensing invading microbes by host innate immunity. TLR2 recognizes bacterial lipoproteins/lipopeptides, and lipopolysaccharide activates TLR4. TLR2 and TLR4 signal via the Toll/interleukin-1 receptor adaptors MyD88 and MAL, leading to NF-κB activation. TLR4 also utilizes the adaptors TRAM and TRIF, resulting in activation of interferon regulatory factor (IRF) 3. Here, we report a new role for TRAM and TRIF in TLR2 regulation and signaling. Interestingly, we observed that TLR2-mediated induction of the chemokine Ccl5 was impaired in TRAM or TRIF deficient macrophages. Inhibition of endocytosis reduced Ccl5 release, and the data also suggested that TRAM and TLR2 co-localize in early endosomes, supporting the hypothesis that signaling may occur from an intracellular compartment. Ccl5 release following lipoprotein challenge additionally involved the kinase Tbk-1 and Irf3, as well as MyD88 and Irf1. Induction of Interferon-β and Ccl4 by lipoproteins was also partially impaired in cells lacking TRIF cells. Our results show a novel function of TRAM and TRIF in TLR2-mediated signal transduction, and the findings broaden our understanding of how Toll/interleukin-1 receptor adaptor proteins may participate in signaling downstream from TLR2. PMID:25505250

  15. Role of Toll-Like Receptor (TLR) 2 in Experimental Bacillus cereus Endophthalmitis

    PubMed Central

    Novosad, Billy D.; Astley, Roger A.; Callegan, Michelle C.

    2011-01-01

    Bacillus cereus causes a uniquely rapid and blinding intraocular infection, endophthalmitis. B. cereus replicates in the eye, synthesizes numerous toxins, and incites explosive intraocular inflammation. The mechanisms involved in the rapid and explosive intraocular immune response have not been addressed. Because Toll-like receptors (TLRs) are integral to the initial recognition of organisms during infection, we hypothesized that the uniquely explosive immune response observed during B. cereus endophthalmitis is directly influenced by the presence of TLR2, a known Gram-positive pathogen recognition receptor. To address this hypothesis, we compared the courses of experimental B. cereus endophthalmitis in wild type C57BL/6J mice to that of age-matched homozygous TLR2-/- mice. Output parameters included analysis of bacterial growth, inflammatory cell (PMN) infiltration, cytokine/chemokine kinetics, retinal function testing, and histology, with N≥4 eyes/assay/time point/mouse strain. B. cereus grew at similar rates to108 CFU/eye by 12 h, regardless of the mouse strain. Retinal function was preserved to a greater degree in infected TLR2-/- eyes compared to that of infected wild type eyes, but infected eyes of both mouse strains lost significant function. Retinal architecture was preserved in infected TLR2-/- eyes, with limited retinal and vitreal cellular infiltration compared to that of infected wild type eyes. Ocular myeloperoxidase activities corroborated these results. In general, TNFα, IFNγ, IL6, and KC were detected in greater concentrations in infected wild type eyes than in infected TLR2-/- eyes. The absence of TLR2 resulted in decreased intraocular proinflammatory cytokine/chemokine levels and altered recruitment of inflammatory cells into the eye, resulting in less intraocular inflammation and preservation of retinal architecture, and a slightly greater degree of retinal function. These results demonstrate TLR2 is an important component of the initial

  16. Characterization, expression analysis and localization pattern of toll-like receptor 1 (tlr1) and toll-like receptor 2 (tlr2) genes in grass carp Ctenopharyngodon idella.

    PubMed

    He, L B; Wang, H; Luo, L F; Jiang, S H; Liu, L Y; Li, Y M; Huang, R; Liao, L J; Zhu, Z Y; Wang, Y P

    2016-08-01

    In this study, the toll-like receptor 1 (tlr1) and toll-like receptor 2 (tlr2) genes of grass carp Ctenopharyngodon idella were cloned and characterized. tlr1 and tlr2 were found to be highly expressed in immune system organs such as spleen, middle kidney and heart kidney. The expression level of tlr1 and tlr2 was found to be up-regulated at the later stage of viral challenge process. Moreover, subcellular localization indicated that Tlr1 and Tlr2 shared similar localization pattern and both of them may locate in the plasma membrane of transfected cells. PMID:27221024

  17. Methamphetamine inhibits Toll-like receptor 9-mediated anti-HIV activity in macrophages.

    PubMed

    Cen, Ping; Ye, Li; Su, Qi-Jian; Wang, Xu; Li, Jie-Liang; Lin, Xin-Qin; Liang, Hao; Ho, Wen-Zhe

    2013-08-01

    Toll-like receptor 9 (TLR9) is one of the key sensors that recognize viral infection/replication in the host cells. Studies have demonstrated that methamphetamine (METH) dysregulated host cell innate immunity and facilitated HIV infection of macrophages. In this study, we present new evidence that METH suppressed TLR9-mediated anti-HIV activity in macrophages. Activation of TLR9 by its agonist CpG-ODN 2216 inhibits HIV replication, which was demonstrated by increased expression of TLR9, interferon (IFN)-α, IFN regulatory factor-7 (IRF-7), myeloid differentiation factor 88 (MyD88), and myxovirus resistance gene A (MxA) in macrophages. However, METH treatment of macrophages greatly compromised the TLR9 signaling-mediated anti-HIV effect and inhibited the expression of TLR9 downstream signaling factors. Dopamine D1 receptor (D1R) antagonists (SCH23390) could block METH-mediated inhibition of anti-HIV activity of TLR9 signaling. Investigation of the underlying mechanisms of the METH action showed that METH treatment selectively down-regulated the expression of TLR9 on macrophages, whereas it had little effect on the expression of other TLRs. Collectively, our results provide further evidence that METH suppresses host cell innate immunity against HIV infection by down-regulating TLR9 expression and its signaling-mediated antiviral effect in macrophages. PMID:23751096

  18. Antagonistic antibody prevents toll-like receptor 2–driven lethal shock-like syndromes

    PubMed Central

    Meng, Guangxun; Rutz, Mark; Schiemann, Matthias; Metzger, Jochen; Grabiec, Alina; Schwandner, Ralf; Luppa, Peter B.; Ebel, Frank; Busch, Dirk H.; Bauer, Stefan; Wagner, Hermann; Kirschning, Carsten J.

    2004-01-01

    Hyperactivation of immune cells by bacterial products through toll-like receptors (TLRs) is thought of as a causative mechanism of septic shock pathology. Infections with Gram-negative or Gram-positive bacteria provide TLR2-specific agonists and are the major cause of severe sepsis. In order to intervene in TLR2-driven toxemia, we raised mAb’s against the extracellular domain of TLR2. Surface plasmon resonance analysis showed direct and specific interaction of TLR2 and immunostimulatory lipopeptide, which was blocked by T2.5 in a dose-dependent manner. Application of mAb T2.5 inhibited cell activation in experimental murine models of infection. T2.5 also antagonized TLR2-specific activation of primary human macrophages. TLR2 surface expression by murine macrophages was surprisingly weak, while both intra- and extracellular expression increased upon systemic microbial challenge. Systemic application of T2.5 upon lipopeptide challenge inhibited release of inflammatory mediators such as TNF-α and prevented lethal shock-like syndrome in mice. Twenty milligrams per kilogram of T2.5 was sufficient to protect mice, and administration of 40 mg/kg of T2.5 was protective even 3 hours after the start of otherwise lethal challenge with Bacillus subtilis. These results indicate that epitope-specific binding of exogenous ligands precedes specific TLR signaling and suggest therapeutic application of a neutralizing anti-TLR2 antibody in acute infection. PMID:15146245

  19. Toll-like receptor-mediated immune response inhibits prion propagation.

    PubMed

    Kang, Sang-Gyun; Kim, Chiye; Cortez, Leonardo M; Carmen Garza, María; Yang, Jing; Wille, Holger; Sim, Valerie L; Westaway, David; McKenzie, Debbie; Aiken, Judd

    2016-06-01

    Prion diseases are progressive neurodegenerative disorders affecting humans and various mammals. The prominent neuropathological change in prion diseases is neuroinflammation characterized by activation of neuroglia surrounding prion deposition. The cause and effect of this cellular response, however, is unclear. We investigated innate immune defenses against prion infection using primary mixed neuronal and glial cultures. Conditional prion propagation occurred in glial cultures depending on their immune status. Preconditioning of the cells with the toll-like receptor (TLR) ligand, lipopolysaccharide, resulted in a reduction in prion propagation, whereas suppression of the immune responses with the synthetic glucocorticoid, dexamethasone, increased prion propagation. In response to recombinant prion fibrils, glial cells up-regulated TLRs (TLR1 and TLR2) expression and secreted cytokines (tumor necrosis factor-α, interleukin-1β, interleukin-6, granulocyte-macrophage colony-stimulating factor, and interferon-β). Preconditioning of neuronal and glial cultures with recombinant prion fibrils inhibited prion replication and altered microglial and astrocytic populations. Our results provide evidence that, in early stages of prion infection, glial cells respond to prion infection through TLR-mediated innate immunity. PMID:26880394

  20. Anaerobic Infections in Children with Neurological Impairments.

    ERIC Educational Resources Information Center

    Brook, Itzhak

    1995-01-01

    Children with neurological impairments are prone to develop serious infection with anaerobic bacteria. The most common anaerobic infections are decubitus ulcers; gastrostomy site wound infections; pulmonary infections (aspiration pneumonia, lung abscesses, and tracheitis); and chronic suppurative otitis media. The unique microbiology of each of…

  1. Association between Toll-like Receptors expression and Human Papillomavirus Type 16 Persistence

    PubMed Central

    Daud, Ibrahim I.; Scott, Mark E.; Ma, Yifei; Shiboski, Stephen; Farhat, Sepideh; Moscicki, Anna-Barbara

    2010-01-01

    The mechanisms involved in mucosal immune control of cervical human papillomavirus (HPV) infection remain ill-defined. Because Toll-like receptors (TLRs) are key players in innate immune responses, we investigated the association between TLR expression and viral persistence or clearance in young women with incident infections with oncogenic HPV types 16 or 51. Messenger RNA expression of TLR1, TLR2, TLR3, TLR4, TLR6, TLR7, TLR8, and TLR9 was measured by quantitative reverse transcription-PCR using human endocervical specimens, collected before and following viral acquisition, in a cohort well characterized for HPV infections. Wilcoxon rank sum test was used to compare the change seen from pre-infection to incident infection between women who subsequently cleared infection with those who did not. HPV 16 infections that cleared were significantly (P < 0.05) associated with an increase in expression of the four viral nucleic acid-sensing TLRs (TLR3, TLR7, TLR8 and TLR9) as well as TLR2 upon viral acquisition. Similar associations were not observed for HPV 51. In women who subsequently cleared their HPV 16 infection, changes in TLR1, TLR3, TLR7, and TLR8 expression levels between pre-incident and incident visits were significantly correlated with parallel changes in the levels of interferon-α2, measured by immunoassay in cervical lavage specimens. This study suggests that dampened TLR expression in the cervical mucosa is a type-specific mechanism by which HPV 16 interferes with innate immune responses, contributing to viral persistence, and that TLR upregulation and resultant cytokine induction is important in subsequent viral clearance. PMID:20473890

  2. Hypoxia attenuates inflammatory mediators production induced by Acanthamoeba via Toll-like receptor 4 signaling in human corneal epithelial cells

    SciTech Connect

    Pan, Hong; Wu, Xinyi

    2012-04-13

    Highlights: Black-Right-Pointing-Pointer Hypoxia attenuates Acanthamoeba-induced the production of IL-8 and IFN-{beta}. Black-Right-Pointing-Pointer Hypoxia inhibits TLR4 expression in a time-dependent manner in HCECs. Black-Right-Pointing-Pointer Hypoxia inhibits Acanthamoeba-induced the activation of NF-{kappa}B and ERK1/2 in HCECs. Black-Right-Pointing-Pointer Hypoxia decreases Acanthamoeba-induced inflammatory response via TLR4 signaling. Black-Right-Pointing-Pointer LPS-induced the secretion of IL-6 and IL-8 is abated by hypoxia via TLR4 signaling. -- Abstract: Acanthamoeba keratitis (AK) is a vision-threatening corneal infection that is intimately associated with contact lens use which leads to hypoxic conditions on the corneal surface. However, the effect of hypoxia on the Acanthamoeba-induced host inflammatory response of corneal epithelial cells has not been studied. In the present study, we investigated the effect of hypoxia on the Acanthamoeba-induced production of inflammatory mediators interleukin-8 (IL-8) and interferon-{beta} (IFN-{beta}) in human corneal epithelial cells and then evaluated its effects on the Toll-like receptor 4 (TLR4) signaling, including TLR4 and myeloid differentiation primary response gene (88) (MyD88) expression as well as the activation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-{kappa}B) and extracellular signal-regulated kinases 1/2 (ERK1/2). We then studied the effect of hypoxia on a TLR4-specific inflammatory response triggered by the TLR4 ligand lipopolysaccharide (LPS). Our data showed that hypoxia significantly decreased the production of IL-8 and IFN-{beta}. Furthermore, hypoxia attenuated Acanthamoeba-triggered TLR4 expression as well as the activation of NF-{kappa}B and ERK1/2, indicating that hypoxia abated Acanthamoeba-induced inflammatory responses by affecting TLR4 signaling. Hypoxia also inhibited LPS-induced IL-6 and IL-8 secretion, myeloid differentiation primary response gene (88

  3. Trypanosoma cruzi and Its Soluble Antigens Induce NET Release by Stimulating Toll-Like Receptors

    PubMed Central

    Diniz, Larissa Figueiredo Alves; Souza, Priscila Silva Sampaio; Pinge-Filho, Phileno; Toledo, Karina Alves

    2015-01-01

    Neutrophils release fibrous traps of DNA, histones, and granule proteins known as neutrophil extracellular traps (NETs), which contribute to microbicidal killing and have been implicated in autoimmunity. The role of NET formation in the host response to nonbacterial pathogens is not well-understood. In this study, we investigated the release of NETs by human neutrophils upon their interaction with Trypanosoma cruzi (Y strain) parasites. Our results showed that human neutrophils stimulated by T. cruzi generate NETs composed of DNA, histones, and elastase. The release occurred in a dose-, time-, and reactive oxygen species-dependent manner to decrease trypomastigote and increase amastigote numbers of the parasites without affecting their viability. NET release was decreased upon blocking with antibodies against Toll-like receptors 2 and 4. In addition, living parasites were not mandatory in the release of NETs induced by T. cruzi, as the same results were obtained when molecules from its soluble extract were tested. Our results increase the understanding of the stimulation of NETs by parasites, particularly T. cruzi. We suggest that contact of T. cruzi with NETs during Chagas’s disease can limit infection by affecting the infectivity/pathogenicity of the parasite. PMID:26431537

  4. Posttranslational Modification of HOIP Blocks Toll-Like Receptor 4-Mediated Linear-Ubiquitin-Chain Formation

    PubMed Central

    Bowman, James; Rodgers, Mary A.; Shi, Mude; Amatya, Rina; Hostager, Bruce; Iwai, Kazuhiro; Gao, Shou-Jiang

    2015-01-01

    ABSTRACT Linear ubiquitination is an atypical posttranslational modification catalyzed by the linear-ubiquitin-chain assembly complex (LUBAC), containing HOIP, HOIL-1L, and Sharpin. LUBAC facilitates NF-κB activation and inflammation upon receptor stimulation by ligating linear ubiquitin chains to critical signaling molecules. Indeed, linear-ubiquitination-dependent signaling is essential to prevent pyogenic bacterial infections that can lead to death. While linear ubiquitination is essential for intracellular receptor signaling upon microbial infection, this response must be measured and stopped to avoid tissue damage and autoimmunity. While LUBAC is activated upon bacterial stimulation, the mechanisms regulating LUBAC activity in response to bacterial stimuli have remained elusive. We demonstrate that LUBAC activity itself is downregulated through ubiquitination, specifically, ubiquitination of the catalytic subunit HOIP at the carboxyl-terminal lysine 1056. Ubiquitination of Lys1056 dynamically altered HOIP conformation, resulting in the suppression of its catalytic activity. Consequently, HOIP Lys1056-to-Arg mutation led not only to persistent LUBAC activity but also to prolonged NF-κB activation induced by bacterial lipopolysaccharide-mediated Toll-like receptor 4 (TLR4) stimulation, whereas it showed no effect on NF-κB activation induced by CD40 stimulation. This study describes a novel posttranslational regulation of LUBAC-mediated linear ubiquitination that is critical for specifically directing TLR4-mediated NF-κB activation. PMID:26578682

  5. Murine retroviruses activate B cells via interaction with toll-like receptor 4

    PubMed Central

    Rassa, John C.; Meyers, Jennifer L.; Zhang, Yuanming; Kudaravalli, Rama; Ross, Susan R.

    2002-01-01

    Although most retroviruses require activated cells as their targets for infection, it is not known how this is achieved in vivo. A candidate protein for the activation of B cells by either mouse mammary tumor virus (MMTV) or murine leukemia virus is the toll-like receptor 4 (TLR4), a component of the innate immune system. MMTV caused B cell activation in C3H/HeN mice but not in C3H/HeJ or BALB/c (C.C3H Tlr4lps-d) congenic mice, both of which have a mutant TLR4 gene. This activation was independent of viral gene expression, because it occurred after treatment of MMTV with ultraviolet light or 2,2′-dithiodipyridine and in azidothymidine-treated mice. Nuclear extracts prepared from the lymphocytes of MMTV-injected C3H/HeN but not C3H/HeJ mice showed increased nuclear factor κB activity. Additionally, the MMTV- and Moloney murine leukemia virus envelope proteins coimmunoprecipitated with TLR4 when expressed in 293T cells. The MMTV receptor failed to coimmunoprecipitate with TLR4, suggesting that MMTV/TLR4 interaction is independent of virus attachment and fusion. These results identify retroviral proteins that interact with a mammalian toll receptor and show that direct activation by such viruses may initiate in vivo infection pathways. PMID:11854525

  6. Starring role of toll-like receptor-4 activation in the gut-liver axis

    PubMed Central

    Carotti, Simone; Guarino, Michele Pier Luca; Vespasiani-Gentilucci, Umberto; Morini, Sergio

    2015-01-01

    Since the introduction of the term “gut-liver axis”, many studies have focused on the functional links of intestinal microbiota, barrier function and immune responses to liver physiology. Intestinal and extra-intestinal diseases alter microbiota composition and lead to dysbiosis, which aggravates impaired intestinal barrier function via increased lipopolysaccharide translocation. The subsequent increased passage of gut-derived product from the intestinal lumen to the organ wall and bloodstream affects gut motility and liver biology. The activation of the toll-like receptor 4 (TLR-4) likely plays a key role in both cases. This review analyzed the most recent literature on the gut-liver axis, with a particular focus on the role of TLR-4 activation. Findings that linked liver disease with dysbiosis are evaluated, and links between dysbiosis and alterations of intestinal permeability and motility are discussed. We also examine the mechanisms of translocated gut bacteria and/or the bacterial product activation of liver inflammation and fibrogenesis via activity on different hepatic cell types. PMID:26600967

  7. Toll-like receptor 9 trafficking and signaling for type I interferons requires PIKfyve activity.

    PubMed

    Hayashi, Kachiko; Sasai, Miwa; Iwasaki, Akiko

    2015-09-01

    Toll-like receptors (TLRs) traffic to distinct membranes for signaling. TLR7 and TLR9 recognize viral nucleic acids in the endosomes and induce robust anti-viral program. Signaling from these TLRs bifurcate at the level of distinct endosomal compartments, namely VAMP3(+) and LAMP(+) endosomes, to mediate the induction of cytokine and type I interferon (IFN) genes, respectively. The formation of the TLR9 endosome competent for IFNs induction requires AP-3. Phosphoinositides (PIs) mark distinct subcellular membranes and control membrane trafficking. However, their role in TLR trafficking and signaling in different dendritic cell (DC) subsets remains unclear. Here, we examined the role of phosphatidylinositol 3P 5-kinase, PIKfyve, in TLR9 trafficking and signaling. We demonstrate that inhibition of PIKfyve activity preferentially blocks TLR9 signaling for type I IFN induction in FLT3L-bone marrow-derived DCs. By confocal microscopy using RAW264.7 cells, we show that trafficking of both TLR9 and CpG to the LAMP1(+) compartment was blocked by PIKfyve inhibitor treatment, whereas their trafficking to the VAMP3(+) endosome remained intact. Further, AP-3 recruitment to TLR9 endosomes was impaired by PIKfyve inhibition. These data indicate that PIKfyve provides critical PIs necessary for the formation of endosome from which TLR9 signals to induce type I IFNs. PMID:25925170

  8. Toll-like receptor-2 deficiency induces schizophrenia-like behaviors in mice

    PubMed Central

    Park, Se Jin; Lee, Jee Youn; Kim, Sang Jeong; Choi, Se-Young; Yune, Tae Young; Ryu, Jong Hoon

    2015-01-01

    Dysregulation of the immune system contributes to the pathogenesis of neuropsychiatric disorders including schizophrenia. Here, we demonstrated that toll-like receptor (TLR)-2, a family of pattern-recognition receptors, is involved in the pathogenesis of schizophrenia-like symptoms. Psychotic symptoms such as hyperlocomotion, anxiolytic-like behaviors, prepulse inhibition deficits, social withdrawal, and cognitive impairments were observed in TLR-2 knock-out (KO) mice. Ventricle enlargement, a hallmark of schizophrenia, was also observed in TLR-2 KO mouse brains. Levels of p-Akt and p-GSK-3α/β were markedly higher in the brain of TLR-2 KO than wild-type (WT) mice. Antipsychotic drugs such as haloperidol or clozapine reversed behavioral and biochemical alterations in TLR-2 KO mice. Furthermore, p-Akt and p-GSK-3α/β were decreased by treatment with a TLR-2 ligand, lipoteichoic acid, in WT mice. Thus, our data suggest that the dysregulation of the innate immune system by a TLR-2 deficiency may contribute to the development and/or pathophysiology of schizophrenia-like behaviors via Akt-GSK-3α/β signaling. PMID:25687169

  9. Reduced cerebral ischemia-reperfusion injury in Toll-like receptor 4 deficient mice

    SciTech Connect

    Cao Canxiang; Yang Qingwu . E-mail: yangqwmlys@hotmail.com; Lv Fenglin; Cui Jie; Fu Huabin; Wang Jingzhou

    2007-02-09

    Inflammatory reaction plays an important role in cerebral ischemia-reperfusion injury, however, its mechanism is still unclear. Our study aims to explore the function of Toll-like receptor 4 (TLR4) in the process of cerebral ischemia-reperfusion. We made middle cerebral artery ischemia-reperfusion model in mice with line embolism method. Compared with C3H/OuJ mice, scores of cerebral water content, cerebral infarct size and neurologic impairment in C3H/Hej mice were obviously lower after 6 h ischemia and 24 h reperfusion. Light microscopic and electron microscopic results showed that cerebral ischemia-reperfusion injury in C3H/Hej mice was less serious than that in C3H/OuJ mice. TNF-{alpha} and IL-6 contents in C3H/HeJ mice were obviously lower than that in C3H/OuJ mice with ELISA. The results showed that TLR4 participates in the process of cerebral ischemia-reperfusion injury probably through decrease of inflammatory cytokines. TLR4 may become a new target for prevention of cerebral ischemia-reperfusion injury. Our study suggests that TLR4 is one of the mechanisms of cerebral ischemia-reperfusion injury besides its important role in innate immunity.

  10. Toll-like Receptor Polymorphisms Are Associated with Increased Neurosyphilis Risk

    PubMed Central

    Marra, Christina M.; Sahi, Sharon K.; Tantalo, Lauren C.; Ho, Emily L.; Dunaway, Shelia B.; Jones, Trudy; Hawn, Thomas R.

    2015-01-01

    Background Single nucleotide polymorphisms (SNPs) in Toll-like receptors (TLR) 1, 2, and 6 impair cell signaling in response to spirochetal lipoproteins. We investigated whether common SNPs in TLR1, 2, or 6 were associated with laboratory- or clinically-defined neurosyphilis. Methods Polymorphisms in the genes for TLR1 (a T->G mutation at position 1805), TLR2 (a G->A mutation at position 2258), and TLR6 (a C->T mutation at position 745) were sought in 456 Caucasian patients with syphilis. Laboratory-defined neurosyphilis included a reactive CSF-Venereal Disease Research Laboratory test. Clinically-defined neurosyphilis included new vision or hearing loss. Controls had CSF white blood cells ≤5/ul, nonreactive CSF-VDRL, and no vision or hearing loss. Results Overall, 26.2% of patients had laboratory-defined and 36.2% had clinically-defined neurosyphilis. Compared to controls, patients with any of the 3 SNPs were more likely to have laboratory-defined neurosyphilis. Those with TLR2 or TLR6 SNPs were more likely to have clinically-defined neurosyphilis. These associations were independent of serum rapid plasma reagin titer. Conclusions A common TLR1 polymorphism is associated with an increased risk of laboratory-defined neurosyphilis and common TLR2 and TLR6 polymorphisms are associated with an increased risk of both laboratory- and clinically-defined neurosyphilis. These data suggest that host factors impact the natural history of syphilis. PMID:24922103

  11. The Molecular Chaperone GRP78 Contributes to Toll-like Receptor 3-mediated Innate Immune Response to Hepatitis C Virus in Hepatocytes.

    PubMed

    Wei, Dahai; Li, Nan L; Zeng, Yanli; Liu, Baoming; Kumthip, Kattareeya; Wang, Tony T; Huo, Dezheng; Ingels, Jesse F; Lu, Lu; Shang, Jia; Li, Kui

    2016-06-01

    Toll-like receptor-3 (TLR3) senses double-stranded RNA intermediates produced during hepatitis C virus (HCV) replication, leading to activation of interferon regulatory factor-3 (IRF3) and NF-κB and subsequent antiviral and proinflammatory responses. Yet, how this TLR3-dependent pathway operates in hepatocytes is unclear. Upon fractionating cultured hepatocytes into various cellular organelles, we observed that TLR3 predominantly resides in endolysosomes of hepatocytes. To determine the critical regulators of TLR3 signaling in response to HCV infection in human hepatocytes, we isolated endolysosome fractions from mock-infected and HCV-infected hepatoma Huh7.5 cells that had been reconstituted for TLR3 expression, separated these fractions on two-dimensional gels, and identified up-regulated/down-regulated proteins by mass spectrometry. Approximately a dozen of cellular proteins were found to be differentially expressed in endolysosome fractions following HCV infection. Of these, expression of several molecular chaperone proteins was elevated. Knockdown of one of these chaperones, glucose-regulated protein 78 kDa (GRP78), compromised TLR3-dependent induction of interferon-stimulated genes and chemokines following HCV infection or poly(I:C) stimulation in cultured hepatocytes. Consistent with this finding, GRP78 depletion impaired TLR3-mediated establishment of an antiviral state. Mechanistically, although TLR3 trafficking to endolysosomes was not affected, phosphorylated IRF3 diminished faster following GRP78 knockdown. Remarkably, GRP78 transcript was significantly up-regulated in liver biopsies of chronic hepatitis C patients as compared with normal liver tissues. Moreover, the GRP78 expression level correlated with that of RANTES (regulated upon activation, normal T-cell expressed and secreted) and CXCL10, two inflammatory chemokines most frequently elevated in HCV-infected liver. Altogether, our data suggest that GRP78 contributes to TLR3-mediated, IRF3

  12. Toll-Like Receptor 9-Mediated Inflammation Triggers Alveolar Bone Loss in Experimental Murine Periodontitis.

    PubMed

    Kim, Paul D; Xia-Juan, Xia; Crump, Katie E; Abe, Toshiharu; Hajishengallis, George; Sahingur, Sinem E

    2015-07-01

    Chronic periodontitis is a local inflammatory disease induced by a dysbiotic microbiota and leading to destruction of the tooth-supporting structures. Microbial nucleic acids are abundantly present in the periodontium, derived through release after phagocytic uptake of microbes and/or from biofilm-associated extracellular DNA. Binding of microbial DNA to its cognate receptors, such as Toll-like receptor 9 (TLR9), can trigger inflammation. In this study, we utilized TLR9 knockout (TLR9(-/-)) mice and wild-type (WT) controls in a murine model of Porphyromonas gingivalis-induced periodontitis and report the first in vivo evidence that TLR9 signaling mediates the induction of periodontal bone loss. P. gingivalis-infected WT mice exhibited significantly increased bone loss compared to that in sham-infected WT mice or P. gingivalis-infected TLR9(-/-) mice, which were resistant to bone loss. Consistent with this, the expression levels of interleukin 6 (IL-6), tumor necrosis factor (TNF), and receptor-activator of nuclear factor kappa B ligand (RANKL) were significantly elevated in the gingival tissues of the infected WT mice but not in infected TLR9(-/-) mice compared to their levels in controls. Ex vivo studies using splenocytes and bone marrow-derived macrophages revealed significantly diminished cytokine production in TLR9(-/-) cells relative to the cytokine production in WT cells in response to P. gingivalis, thereby implicating TLR9 in inflammatory responses to this organism. Intriguingly, compared to the cytokine production in WT cells, TLR9(-/-) cells exhibited significantly decreased proinflammatory cytokine production upon challenge with lipopolysaccharide (LPS) (TLR4 agonist) or Pam3Cys (TLR2 agonist), suggesting possible cross talk between TLR9, TLR4, and TLR2. Collectively, our results provide the first proof-of-concept evidence implicating TLR9-triggered inflammation in periodontal disease pathogenesis, thereby identifying a new potential therapeutic target

  13. Toll-Like Receptor 9-Mediated Inflammation Triggers Alveolar Bone Loss in Experimental Murine Periodontitis

    PubMed Central

    Kim, Paul D.; Xia-Juan, Xia; Crump, Katie E.; Abe, Toshiharu; Hajishengallis, George

    2015-01-01

    Chronic periodontitis is a local inflammatory disease induced by a dysbiotic microbiota and leading to destruction of the tooth-supporting structures. Microbial nucleic acids are abundantly present in the periodontium, derived through release after phagocytic uptake of microbes and/or from biofilm-associated extracellular DNA. Binding of microbial DNA to its cognate receptors, such as Toll-like receptor 9 (TLR9), can trigger inflammation. In this study, we utilized TLR9 knockout (TLR9−/−) mice and wild-type (WT) controls in a murine model of Porphyromonas gingivalis-induced periodontitis and report the first in vivo evidence that TLR9 signaling mediates the induction of periodontal bone loss. P. gingivalis-infected WT mice exhibited significantly increased bone loss compared to that in sham-infected WT mice or P. gingivalis-infected TLR9−/− mice, which were resistant to bone loss. Consistent with this, the expression levels of interleukin 6 (IL-6), tumor necrosis factor (TNF), and receptor-activator of nuclear factor kappa B ligand (RANKL) were significantly elevated in the gingival tissues of the infected WT mice but not in infected TLR9−/− mice compared to their levels in controls. Ex vivo studies using splenocytes and bone marrow-derived macrophages revealed significantly diminished cytokine production in TLR9−/− cells relative to the cytokine production in WT cells in response to P. gingivalis, thereby implicating TLR9 in inflammatory responses to this organism. Intriguingly, compared to the cytokine production in WT cells, TLR9−/− cells exhibited significantly decreased proinflammatory cytokine production upon challenge with lipopolysaccharide (LPS) (TLR4 agonist) or Pam3Cys (TLR2 agonist), suggesting possible cross talk between TLR9, TLR4, and TLR2. Collectively, our results provide the first proof-of-concept evidence implicating TLR9-triggered inflammation in periodontal disease pathogenesis, thereby identifying a new potential

  14. Effects of P-MAPA immunomodulator on Toll-like receptor 2, ROS, nitric oxide, MAPKp38 and IKK in PBMC and macrophages from dogs with visceral leishmaniasis.

    PubMed

    Melo, L M; Perosso, J; Almeida, B F M; Silva, K L O; Somenzari, M A; de Lima, V M F

    2014-02-01

    Leishmania (L.) chagasi is the etiologic agent of visceral leishmaniasis (VL) that can be transmitted to humans and dogs. VL in Brazil represents a serious public health problem; therefore, it is important to study new alternatives to treat infected dogs. In dogs, the therapeutic arsenal against canine VL is limited. The immunomodulator protein aggregate magnesium-ammonium phospholinoleate-palmitoleate anhydride (P-MAPA) improves immunocompetence when the immune system is impaired, but its dependence on Toll-like receptors (TLRs) and the mechanisms involved in immune response remain unclear. The in vitro action of P-MAPA on the expression of TLR2 and TLR4, reactive oxygen species (ROS), nitric oxide (NO) and p38 mitogen-activated protein kinase (p38 MAPK) and IKK phosphorylation was studied in mononuclear cells from peripheral blood and macrophages from healthy and Leishmania-infected dogs. The PBMC or macrophages were isolated and cultured with different concentrations of P-MAPA (20,100 and 200 μg/ml) in a humid environment at 37°C with 5% CO(2). Observation revealed that Leishmania-infected dogs showed a decrease in TLR2 in macrophages compared with healthy dogs and in induction with P-MAPA. ROS were increased in PBMCs from Leishmania spp.-infected dogs compared with healthy dogs and P-MAPA improved ROS production. NO production was increased in culture supernatant from macrophages stimulated by P-MAPA in both healthy and Leishmania spp. infected dogs. Treatment of macrophages from healthy dogs with immunomodulatory P-MAPA induced p38 MAPK and IKK phosphorylation, suggesting signal transduction by this pathway. These findings suggest that P-MAPA has potential as a therapeutic drug in the treatment of canine visceral leishmaniasis. PMID:24374021

  15. Targeting Toll-like receptor 2 inhibits growth of head and neck squamous cell carcinoma

    PubMed Central

    Farnebo, Lovisa; Shahangian, Arash; Lee, Yunqin; Shin, June Ho; Scheeren, Ferenc A.; Sunwoo, John B.

    2015-01-01

    Infection-driven inflammation has been proposed to be involved in the tumorigenesis of head and neck squamous cell carcinoma (HNSCC). Oral HNSCC is often colonized with microbes such as gram-positive bacteria and yeast, where ligands derived from their wall components have been shown to specifically bind to Toll-like receptor 2 (TLR2). Although TLR2 has been described to be expressed in oral HNSCC, its function has not been well characterized. Here, we show the expression of TLR2 in both HNSCC cell lines and primary patient-derived HNSCC xenograft tumors. Activation of TLR2 with a yeast-derived ligand of TLR2, zymosan, promoted organoid formation in an ex vivo model of tumor growth, while blockade with anti-TLR2 antibodies inhibited organoid formation. Zymosan also induced phosphorylation of ERK and the p65 subunit of NF-κB, which was inhibited in the presence of anti-TLR2 antibodies, indicating that this receptor is functional in HNSCC and that the signaling through these pathways is intact. TLR2 blockade also inhibited growth of human xenografted tumors in immunodeficient mice. In summary, our data show that TLR2 is a functional receptor expressed in human HNSCC that plays a direct pro-tumorigenic role, and that it can be therapeutically targeted with blocking antibodies to reduce tumor growth. PMID:25846753

  16. Toll-like receptor 2 functions as a pattern recognition receptor for diverse bacterial products.

    PubMed

    Lien, E; Sellati, T J; Yoshimura, A; Flo, T H; Rawadi, G; Finberg, R W; Carroll, J D; Espevik, T; Ingalls, R R; Radolf, J D; Golenbock, D T

    1999-11-19

    Toll-like receptors (TLRs) 2 and 4 are signal transducers for lipopolysaccharide, the major proinflammatory constituent in the outer membrane of Gram-negative bacteria. We observed that membrane lipoproteins/lipopeptides from Borrelia burgdorferi, Treponema pallidum, and Mycoplasma fermentans activated cells heterologously expressing TLR2 but not those expressing TLR1 or TLR4. These TLR2-expressing cells were also stimulated by living motile B. burgdorferi, suggesting that TLR2 recognition of lipoproteins is relevant to natural Borrelia infection. Importantly, a TLR2 antibody inhibited bacterial lipoprotein/lipopeptide-induced tumor necrosis factor release from human peripheral blood mononuclear cells, and TLR2-null Chinese hamster macrophages were insensitive to lipoprotein/lipopeptide challenge. The data suggest a role for the native protein in cellular activation by these ligands. In addition, TLR2-dependent responses were seen using whole Mycobacterium avium and Staphylococcus aureus, demonstrating that this receptor can function as a signal transducer for a wide spectrum of bacterial products. We conclude that diverse pathogens activate cells through TLR2 and propose that this molecule is a central pattern recognition receptor in host immune responses to microbial invasion. PMID:10559223

  17. Rice bran feruloylated oligosaccharides activate dendritic cells via Toll-like receptor 2 and 4 signaling.

    PubMed

    Lin, Chi Chen; Chen, Hua Han; Chen, Yu Kuo; Chang, Hung Chia; Lin, Ping Yi; Pan, I-Hong; Chen, Der-Yuan; Chen, Chuan Mu; Lin, Su Yi

    2014-01-01

    This work presents the effects of feruloylated oligosaccharides (FOs) of rice bran on murine bone marrow-derived dendritic cells (BMDCs) and the potential pathway through which the effects are mediated. We found that FOs induced phenotypic maturation of DCs, as shown by the increased expression of CD40, CD80/CD86 and MHC-I/II molecules. FOs efficiently induced maturation of DCs generated from C3H/HeN or C57BL/6 mice with normal toll-like receptor 4 (TLR-4) or TLR-2 but not DCs from mice with mutated TLR4 or TLR2. The mechanism of action of FOs may be mediated by increased phosphorylation of ERK, p38 and JNK mitogen-activated protein kinase (MAPKs) and increased NF-kB activity, which are important signaling molecules downstream of TLR-4 and TLR-2. These data suggest that FOs induce DCs maturation through TLR-4 and/or TLR-2 and that FOs might have potential efficacy against tumor or virus infection or represent a candidate-adjuvant approach for application in immunotherapy and vaccination. PMID:24762969

  18. Reptile Toll-like receptor 5 unveils adaptive evolution of bacterial flagellin recognition

    PubMed Central

    Voogdt, Carlos G. P.; Bouwman, Lieneke I.; Kik, Marja J. L.; Wagenaar, Jaap A.; van Putten, Jos P. M.

    2016-01-01

    Toll-like receptors (TLR) are ancient innate immune receptors crucial for immune homeostasis and protection against infection. TLRs are present in mammals, birds, amphibians and fish but have not been functionally characterized in reptiles despite the central position of this animal class in vertebrate evolution. Here we report the cloning, characterization, and function of TLR5 of the reptile Anolis carolinensis (Green Anole lizard). The receptor (acTLR5) displays the typical TLR protein architecture with 22 extracellular leucine rich repeats flanked by a N- and C-terminal leucine rich repeat domain, a membrane-spanning region, and an intracellular TIR domain. The receptor is phylogenetically most similar to TLR5 of birds and most distant to fish TLR5. Transcript analysis revealed acTLR5 expression in multiple lizard tissues. Stimulation of acTLR5 with TLR ligands demonstrated unique responsiveness towards bacterial flagellin in both reptile and human cells. Comparison of acTLR5 and human TLR5 using purified flagellins revealed differential sensitivity to Pseudomonas but not Salmonella flagellin, indicating development of species-specific flagellin recognition during the divergent evolution of mammals and reptiles. Our discovery of reptile TLR5 fills the evolutionary gap regarding TLR conservation across vertebrates and provides novel insights in functional evolution of host-microbe interactions. PMID:26738735

  19. Activation of toll like receptor-3 induces corneal epithelial barrier dysfunction.

    PubMed

    Wei, Jie; Jiang, Hua; Gao, Hongrui; Wang, Guangjie

    2015-06-01

    The epithelial barrier is critical in the maintenance of the homeostasis of the cornea. A number of eye disorders are associated with the corneal epithelial barrier dysfunction. Viral infection is one common eye disease type. This study aims to elucidate the mechanism by which the activation of toll like receptor 3 (TLR3) in the disruption of the corneal epithelial barrier. In this study, HCE cells (a human corneal epithelial cell line) were cultured into epithelial layers using as an in vitro model of the corneal epithelial barrier. PolyI:C was used as a ligand of TLR3. The transepithelial electric resistance (TER) and permeability of the HCE epithelial layer were assessed using as the parameters to evaluate the corneal epithelial barrier integrity. The results showed that exposure to PolyI:C markedly decreased the TER and increased the permeability of the HCE epithelial layers; the levels of cell junction protein, E-cadherin, were repressed by PolyI:C via increasing histone deacetylase-1 (HDAC1), the latter binding to the promoter of E-cadherin and repressed the transcription of E-cadherin. The addition of butyrate (an inhibitor of HDAC1) to the culture blocked the corneal epithelial barrier dysfunction caused by PolyI:C. In conclusion, activation of TLR3 can disrupt the corneal epithelial barrier, which can be blocked by the inhibitor of HDAC1. PMID:25912142

  20. Reptile Toll-like receptor 5 unveils adaptive evolution of bacterial flagellin recognition.

    PubMed

    Voogdt, Carlos G P; Bouwman, Lieneke I; Kik, Marja J L; Wagenaar, Jaap A; van Putten, Jos P M

    2016-01-01

    Toll-like receptors (TLR) are ancient innate immune receptors crucial for immune homeostasis and protection against infection. TLRs are present in mammals, birds, amphibians and fish but have not been functionally characterized in reptiles despite the central position of this animal class in vertebrate evolution. Here we report the cloning, characterization, and function of TLR5 of the reptile Anolis carolinensis (Green Anole lizard). The receptor (acTLR5) displays the typical TLR protein architecture with 22 extracellular leucine rich repeats flanked by a N- and C-terminal leucine rich repeat domain, a membrane-spanning region, and an intracellular TIR domain. The receptor is phylogenetically most similar to TLR5 of birds and most distant to fish TLR5. Transcript analysis revealed acTLR5 expression in multiple lizard tissues. Stimulation of acTLR5 with TLR ligands demonstrated unique responsiveness towards bacterial flagellin in both reptile and human cells. Comparison of acTLR5 and human TLR5 using purified flagellins revealed differential sensitivity to Pseudomonas but not Salmonella flagellin, indicating development of species-specific flagellin recognition during the divergent evolution of mammals and reptiles. Our discovery of reptile TLR5 fills the evolutionary gap regarding TLR conservation across vertebrates and provides novel insights in functional evolution of host-microbe interactions. PMID:26738735

  1. In Vitro Inflammation Inhibition Model Based on Semi-Continuous Toll-Like Receptor Biosensing

    PubMed Central

    Jeon, Jin-Woo; Ha, Un-Hwan; Paek, Se-Hwan

    2014-01-01

    A chemical inhibition model of inflammation is proposed by semi-continuous monitoring the density of toll-like receptor 1 (TLR1) expressed on mammalian cells following bacterial infection to investigate an in vivo-mimicked drug screening system. The inflammation was induced by adding bacterial lysate (e.g., Pseudomonas aeruginosa) to a mammalian cell culture (e.g., A549 cell line). The TLR1 density on the same cells was immunochemically monitored up to three cycles under optimized cyclic bacterial stimulation-and-restoration conditions. The assay was carried out by adopting a cell-compatible immunoanalytical procedure and signal generation method. Signal intensity relative to the background control obtained without stimulation was employed to plot the standard curve for inflammation. To suppress the inflammatory response, sodium salicylate, which inhibits nuclear factor-κB activity, was used to prepare the standard curve for anti-inflammation. Such measurement of differential TLR densities was used as a biosensing approach discriminating the anti-inflammatory substance from the non-effector, which was simulated by using caffeic acid phenethyl ester and acetaminophen as the two components, respectively. As the same cells exposed to repetitive bacterial stimulation were semi-continuously monitored, the efficacy and toxicity of the inhibitors may further be determined regarding persistency against time. Therefore, this semi-continuous biosensing model could be appropriate as a substitute for animal-based experimentation during drug screening prior to pre-clinical tests. PMID:25136864

  2. Innate immune receptor Toll-like receptor 4 signalling in neuropsychiatric diseases.

    PubMed

    García Bueno, B; Caso, J R; Madrigal, J L M; Leza, J C

    2016-05-01

    The innate immunity is a stereotyped first line of defense against pathogens and unspecified damage signals. One of main actors of innate immunity are the Toll-like receptors (TLRs), and one of the better characterized members of this family is TLR-4, that it is mainly activated by Gram-negative bacteria lipopolysaccharide. In brain, TLR-4 organizes innate immune responses against infections or cellular damage, but also possesses other physiological functions. In the last years, some evidences suggest a role of TLR-4 in stress and stress-related neuropsychiatric diseases. Peripheral and brain TLR-4 activation triggers sickness behavior, and its expression is a risk factor of depression. Some elements of the TLR-4 signaling pathway are up-regulated in peripheral samples and brain post-mortem tissue from depressed and suicidal patients. The "leaky gut" hypothesis of neuropsychiatric diseases is based on the existence of an increase of the intestinal permeability which results in bacterial translocation able to activate TLR-4. Enhanced peripheral TLR-4 expression/activity has been described in subjects diagnosed with schizophrenia, bipolar disorder and in autistic children. A role for TLR-4 in drugs abuse has been also proposed. The therapeutic potential of pharmacological/genetic modulation of TLRs signaling pathways in neuropsychiatry is promising, but a great preclinical/clinical scientific effort is still needed. PMID:26905767

  3. Energetics of Endotoxin Recognition in the Toll-Like Receptor 4 Innate Immune Response

    PubMed Central

    Paramo, Teresa; Tomasio, Susana M.; Irvine, Kate L.; Bryant, Clare E.; Bond, Peter J.

    2015-01-01

    Bacterial outer membrane lipopolysaccharide (LPS) potently stimulates the mammalian innate immune system, and can lead to sepsis, the primary cause of death from infections. LPS is sensed by Toll-like receptor 4 (TLR4) in complex with its lipid-binding coreceptor MD-2, but subtle structural variations in LPS can profoundly modulate the response. To better understand the mechanism of LPS-induced stimulation and bacterial evasion, we have calculated the binding affinity to MD-2 of agonistic and antagonistic LPS variants including lipid A, lipid IVa, and synthetic antagonist Eritoran, and provide evidence that the coreceptor is a molecular switch that undergoes ligand-induced conformational changes to appropriately activate or inhibit the receptor complex. The plasticity of the coreceptor binding cavity is shown to be essential for distinguishing between ligands, whilst similar calculations for a model bacterial LPS bilayer reveal the “membrane-like” nature of the protein cavity. The ability to predict the activity of LPS variants should facilitate the rational design of TLR4 therapeutics. PMID:26647780

  4. Discovery of toll-like receptor 13 exists in the teleost fish: Miiuy croaker (Perciformes, Sciaenidae).

    PubMed

    Wang, Yanjin; Bi, Xueyi; Chu, Qing; Xu, Tianjun

    2016-08-01

    Toll-like receptors (TLRs) play an indispensable role in the immune response for pathogen recognition and triggering not only innate immunity but also adaptive immunity. Here we report the TLR13 homologue, one member of TLRs, in Perciformes (especially Sciaenidae). And we used the miiuy croaker as represented species for further functional experiments. Former study reported the TLR13 only expressed in murine, and we are the first to report the teleost TLR13 (mmiTLR13). MmiTLR13 expressed highly in immune defense related tissues, such as the liver, spleen, and kidney, and Vibrio anguillarum or poly(I:C) infection showed the immune response of mmiTLR13. Further luciferase reporter assays showed the ability for activation of ISRE luciferase reporter, but it failed to active NF-κB. And further gene silence by short hairpin RNA (shRNA) confirmed the results. Immunofluorescence of mmiTLR13 presents the cytoplasmic distribution in Hela cell. In addition, the Toll/interleukin 1 receptor (TIR) domain of mammal TLR5 exhibits high identity with TLR13, which indicated the high homology between TLR5 and TLR13. These findings will lay the fundamental cornerstone for further research of teleost TLR13 and expand the horizon for better understand the teleost TLRs system. PMID:26952767

  5. Toll-like receptors: the swiss army knife of immunity and vaccine development

    PubMed Central

    Dowling, Jennifer K; Mansell, Ashley

    2016-01-01

    Innate immune cells have a critical role in defense against infection and disease. Central to this is the broad specificity with which they can detect pathogen-associated patterns and danger-associated patterns via the pattern recognition receptors (PRRs) they express. Several families of PRRs have been identified including: Toll-like receptors (TLRs), C-type lectin-like receptors, retinoic acid-inducible gene-like receptors and nucleotide-binding oligomerization domain–like receptors. TLRs are one of the most largely studied families of PRRs. The binding of ligands to TLRs on antigen presenting cells (APCs), mainly dendritic cells, leads to APC maturation, induction of inflammatory cytokines and the priming of naive T cells to drive acquired immunity. Therefore, activation of TLRs promotes both innate inflammatory responses and the induction of adaptive immunity. Consequently, in the last two decades mounting evidence has inextricably linked TLR activation with the pathogenesis of immune diseases and cancer. It has become advantageous to harness these aspects of TLR signaling therapeutically to accelerate and enhance the induction of vaccine-specific responses and also target TLRs with the use of biologics and small molecule inhibitors for the treatment of disease. In these respects, TLRs may be considered a ‘Swiss Army' knife of the immune system, ready to respond in a multitude of infectious and disease states. Here we describe the latest advances in TLR-targeted therapeutics and the use of TLR ligands as vaccine adjuvants. PMID:27350884

  6. Toll-like receptor 2 activation depends on lipopeptide shedding by bacterial surfactants

    PubMed Central

    Hanzelmann, Dennis; Joo, Hwang-Soo; Franz-Wachtel, Mirita; Hertlein, Tobias; Stevanovic, Stefan; Macek, Boris; Wolz, Christiane; Götz, Friedrich; Otto, Michael; Kretschmer, Dorothee; Peschel, Andreas

    2016-01-01

    Sepsis caused by Gram-positive bacterial pathogens is a major fatal disease but its molecular basis remains elusive. Toll-like receptor 2 (TLR2) has been implicated in the orchestration of inflammation and sepsis but its role appears to vary for different pathogen species and clones. Accordingly, Staphylococcus aureus clinical isolates differ substantially in their capacity to activate TLR2. Here we show that strong TLR2 stimulation depends on high-level production of phenol-soluble modulin (PSM) peptides in response to the global virulence activator Agr. PSMs are required for mobilizing lipoproteins, the TLR2 agonists, from the staphylococcal cytoplasmic membrane. Notably, the course of sepsis caused by PSM-deficient S. aureus is similar in wild-type and TLR2-deficient mice, but TLR2 is required for protection of mice against PSM-producing S. aureus. Thus, a crucial role of TLR2 depends on agonist release by bacterial surfactants. Modulation of this process may lead to new therapeutic strategies against Gram-positive infections. PMID:27470911

  7. Toll-like receptor 2 activation depends on lipopeptide shedding by bacterial surfactants.

    PubMed

    Hanzelmann, Dennis; Joo, Hwang-Soo; Franz-Wachtel, Mirita; Hertlein, Tobias; Stevanovic, Stefan; Macek, Boris; Wolz, Christiane; Götz, Friedrich; Otto, Michael; Kretschmer, Dorothee; Peschel, Andreas

    2016-01-01

    Sepsis caused by Gram-positive bacterial pathogens is a major fatal disease but its molecular basis remains elusive. Toll-like receptor 2 (TLR2) has been implicated in the orchestration of inflammation and sepsis but its role appears to vary for different pathogen species and clones. Accordingly, Staphylococcus aureus clinical isolates differ substantially in their capacity to activate TLR2. Here we show that strong TLR2 stimulation depends on high-level production of phenol-soluble modulin (PSM) peptides in response to the global virulence activator Agr. PSMs are required for mobilizing lipoproteins, the TLR2 agonists, from the staphylococcal cytoplasmic membrane. Notably, the course of sepsis caused by PSM-deficient S. aureus is similar in wild-type and TLR2-deficient mice, but TLR2 is required for protection of mice against PSM-producing S. aureus. Thus, a crucial role of TLR2 depends on agonist release by bacterial surfactants. Modulation of this process may lead to new therapeutic strategies against Gram-positive infections. PMID:27470911

  8. Role of Toll-like receptors in health and diseases of gastrointestinal tract.

    PubMed

    Harris, Greg; KuoLee, Rhonda; Chen, Wangxue

    2006-04-14

    The human gastrointestinal (GI) tract is colonized by non-pathogenic commensal microflora and frequently exposed to many pathogenic organisms. For the maintenance of GI homeostasis, the host must discriminate between pathogenic and non-pathogenic organisms and initiate effective and appropriate immune and inflammatory responses. Mammalian toll-like receptors (TLRs) are members of the pattern-recognition receptor (PRR) family that plays a central role in the initiation of innate cellular immune responses and the subsequent adaptive immune responses to microbial pathogens. Recent studies have shown that gastrointestinal epithelial cells express almost all TLR subtypes characterized to date and that the expression and activation of TLRs in the GI tract are tightly and coordinately regulated. This review summarizes the current understanding of the crucial dual roles of TLRs in the development of host innate and adaptive immune responses to GI infections and the maintenance of the immune tolerance to commensal bacteria through down-regulation of surface expression of TLRs in intestinal epithelial cells. PMID:16610014

  9. Release of Toll-Like Receptor-2-Activating Bacterial Lipoproteins in Shigella flexneri Culture Supernatants

    PubMed Central

    Aliprantis, Antonios O.; Weiss, David S.; Radolf, Justin D.; Zychlinsky, Arturo

    2001-01-01

    Shigella spp. cause dysentery, a severe form of bloody diarrhea. Apoptosis, or programmed cell death, is induced during Shigella infections and has been proposed to be a key event in the pathogenesis of dysentery. Here, we describe a novel cytotoxic activity in the sterile-culture supernatants of Shigella flexneri. An identical activity was identified in purified S. flexneri endotoxin, defined here as a mixture of lipopolysaccharide (LPS) and endotoxin-associated proteins (EP). Separation of endotoxin into EP and LPS revealed the activity to partition exclusively to the EP fraction. Biochemical characterization of S. flexneri EP and culture supernatants, including enzymatic deactivation, reverse-phase high-pressure liquid chromatography analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a Toll-like receptor-2 (TLR2) activation assay, indicates that the cytotoxic component is a mixture of bacterial lipoproteins (BLP). We show that biologically active BLP are liberated into culture supernatants of actively growing S. flexneri. In addition, our data indicate that BLP, and not LPS, are the component of endotoxin of gram-negative organisms responsible for activating TLR2. The activation of apoptosis by BLP shed from S. flexneri is discussed as a novel aspect of the interaction of bacteria with the host. PMID:11553567

  10. A coding IRAK2 protein variant compromises Toll-like receptor (TLR) signaling and is associated with colorectal cancer survival.

    PubMed

    Wang, Hui; Flannery, Sinead M; Dickhöfer, Sabine; Huhn, Stefanie; George, Julie; Kubarenko, Andriy V; Lascorz, Jesus; Bevier, Melanie; Willemsen, Joschka; Pichulik, Tica; Schafmayer, Clemens; Binder, Marco; Manoury, Bénédicte; Paludan, Søren R; Alarcon-Riquelme, Marta; Bowie, Andrew G; Försti, Asta; Weber, Alexander N R

    2014-08-15

    Within innate immune signaling pathways, interleukin-1 receptor-associated kinases (IRAKs) fulfill key roles downstream of multiple Toll-like receptors and the interleukin-1 receptor. Although human IRAK4 deficiency was shown to lead to severe immunodeficiency in response to pyogenic bacterial infection during childhood, little is known about the role of human IRAK2. We here identified a non-synonymous IRAK2 variant, rs35060588 (coding R214G), as hypofunctional in terms of NF-κB signaling and Toll-like receptor-mediated cytokine induction. This was due to reduced ubiquitination of TRAF6, a key step in signal transduction. IRAK2 rs35060588 occurs in 3-9% of individuals in different ethnic groups, and our studies suggested a genetic association of rs35060588 with colorectal cancer survival. This for the first time implicates human IRAK2 in a human disease and highlights the R214G IRAK2 variant as a potential novel and broadly applicable biomarker for disease or as a therapeutic intervention point. PMID:24973222

  11. Expression of Toll-Like Receptors 2 and 4 and Related Cytokines in Patients with Hepatic Cystic and Alveolar Echinococcosis

    PubMed Central

    Tuxun, Tuerhongjiang; Ma, Hai-Zhang; Apaer, Shadike; Zhang, Heng; Aierken, Amina; Li, Yu-Peng; Lin, Ren-Yong; Zhao, Jin-Ming; Zhang, Jin-Hui; Wen, Hao

    2015-01-01

    Several studies have demonstrated the important role of Toll-like receptors in various parasitic infections. This study aims to explore expression of Toll-like receptors (TLRs) and related cytokines in patients with human cystic echinococcosis (CE) and alveolar echinococcosis (AE). 78 subjects including AE group (N = 28), CE group (N = 22), and healthy controls (HC, N = 28) were enrolled in this study. The mRNA expression levels of TLR2 and TLR4 in blood and hepatic tissue and plasma levels related cytokines were detected by using ELISA. Median levels of TLR2 mRNA in AE and CE groups were significantly elevated as compared with that in healthy control group. Median levels of TLR4 expression were increased in AE and CE. Plasma concentration levels of IL-5, IL-6, and IL-10 were slightly increased in AE and CE groups compared with those in HC group with no statistical differences (p > 0.05). The IL-23 concentration levels were significantly higher in AE and CE groups than that in HC subjects with statistical significance. The increased expression of TLR2 and IL-23 might play a potential role in modulating tissue infiltrative growth of the parasite and its persistence in the human host. PMID:26635448

  12. Toll-like receptor 4-positive macrophages protect mice from Pasteurella pneumotropica-induced pneumonia

    NASA Technical Reports Server (NTRS)

    Hart, Marcia L.; Mosier, Derek A.; Chapes, Stephen K.

    2003-01-01

    This study investigates Toll-like receptor 4 (TLR4)-positive macrophages in early recognition and clearance of pulmonary bacteria. TLR4 is a trans-membrane receptor that is the primary recognition molecule for lipopolysaccharide of gram-negative bacteria. The TLR4(Lps-del) mouse strains C57BL10/ScN (B10) and STOCK Abb(tm1) TLR4(Lps-del) Slc11a1(s)(B10 x C2D) are susceptible to pulmonary infections and develop pneumonia when naturally or experimentally infected by the opportunistic bacterium Pasteurella pneumotropica. Since these mice have the TLR4(Lps-del) genotype, we hypothesized that reconstitution of mice with TLR4-positive macrophages would provide resistance to this bacterium. A cultured macrophage cell line (C2D macrophages) and bone marrow cells from C2D mice were adoptively transferred to B10 and B10 x C2D mice by intraperitoneal injection. C2D macrophages increased B10 and B10 x C2D mouse resistance to P. pneumotropica. In C2D-recipient mice there was earlier transcription of tumor necrosis factor alpha and chemokines JE and macrophage inflammatory protein 2 (MIP-2) in the lungs of B10 and B10 x C2D mice, and there was earlier transcription of KC and MIP-1alpha in B10 x C2D mice. In addition, the course of inflammation following experimental Pasteurella challenge was altered in C2D recipients. C2D macrophages also protected B10 x C2D mice, which lack CD4(+) T cells. These data indicate that macrophages are critical for pulmonary immunity and can provide host resistance to P. pneumotropica. This study indicates that TLR4-positive macrophages are important for early recognition and clearance of pulmonary bacterial infections.

  13. Novel Role of Toll-Like Receptor 3 in Hepatitis C-Associated Glomerulonephritis

    PubMed Central

    Wörnle, Markus; Schmid, Holger; Banas, Bernhard; Merkle, Monika; Henger, Anna; Roeder, Maximilian; Blattner, Simone; Bock, Elisabeth; Kretzler, Matthias; Gröne, Hermann-Josef; Schlöndorff, Detlef

    2006-01-01

    Hepatitis C virus (HCV) infection is frequently complicated by glomerulonephritis with immune complexes containing viral RNA. We examined the potential influence of Toll-like receptors (TLRs), specifically TLR3 recognition of viral dsRNA exemplified by polyriboinosinic:polyribocytidylic acid [poly(I:C) RNA]. Normal human kidney stained positive for TLR3 on mesangial cells (MCs), vascular smooth muscle cells, and collecting duct epithelium. Cultured MCs have low TLR3 mRNA levels with predominant intracellular protein localization, which was increased by tumor necrosis factor-α, interleukin (IL)-1β, interferon (IFN)-γ, and the TLR3 ligand poly(I:C) RNA. Poly(I:C) RNA stimulation of MCs increased mRNA and protein synthesis of IL-6, IL-1β, M-CSF, IL-8/CXCL8, RANTES/CCL5, MCP-1/CCL2, and ICAM-I; it also increased anti-proliferative and proapoptotic effects, the latter of which was decreased by inhibiting caspase-8. In microdissected glomeruli of normal and non-HCV membranoproliferative glomerulonephritis biopsies, TLR3 mRNA expression was low. In contrast TLR3 mRNA expression was significantly increased in hepatitis C-positive glomerulonephritis and was associated with enhanced mRNA for RANTES/CCL5 and MCP-1/CCL2. We hypothesize that immune complexes containing viral RNA activate mesangial TLR3 during HCV infection, thereby contributing to chemokine/cytokine release and effecting proliferation and apoptosis. Thus, TLR3 expression on renal cells, and especially MCs, may establish a link between viral infections and glomerular diseases. PMID:16436653

  14. Role of Toll-Like Receptor 13 in Innate Immune Recognition of Group B Streptococci

    PubMed Central

    Signorino, Giacomo; Mohammadi, Nastaran; Patanè, Francesco; Buscetta, Marco; Venza, Mario; Venza, Isabella; Mancuso, Giuseppe; Midiri, Angelina; Alexopoulou, Lena; Teti, Giuseppe; Beninati, Concetta

    2014-01-01

    Murine Toll-like receptor 13 (TLR13), an endosomal receptor that is not present in humans, is activated by an unmethylated motif present in the large ribosomal subunit of bacterial RNA (23S rRNA). Little is known, however, of the impact of TLR13 on antibacterial host defenses. Here we examined the role of this receptor in the context of infection induced by the model pathogen group B streptococcus (GBS). To this end, we used bacterial strains masked from TLR13 recognition by virtue of constitutive expression of the ErmC methyltransferase, which results in dimethylation of the 23S rRNA motif at a critical adenine residue. We found that TLR13-mediated rRNA recognition was required for optimal induction of tumor necrosis factor alpha and nitrous oxide in dendritic cell and macrophage cultures stimulated with heat-killed bacteria or purified bacterial RNA. However, TLR13-dependent recognition was redundant when live bacteria were used as a stimulus. Moreover, masking bacterial rRNA from TLR13 recognition did not increase the ability of GBS to avoid host defenses and replicate in vivo. In contrast, increased susceptibility to infection was observed under conditions in which signaling by all endosomal TLRs was abolished, i.e., in mice with a loss-of-function mutation in the chaperone protein UNC93B1. Our data lend support to the conclusion that TLR13 participates in GBS recognition, although blockade of the function of this receptor can be compensated for by other endosomal TLRs. Lack of selective pressure by bacterial infections might explain the evolutionary loss of TLR13 in humans. However, further studies using different bacterial species are needed to prove this hypothesis. PMID:25225249

  15. Insights into Soluble Toll-Like Receptor 2 as a Downregulator of Virally Induced Inflammation

    PubMed Central

    Henrick, Bethany M.; Yao, Xiao-Dan; Taha, Ameer Y.; German, J. Bruce; Rosenthal, Kenneth Lee

    2016-01-01

    The ability to distinguish pathogens from self-antigens is one of the most important functions of the immune system. However, this simple self versus non-self assignment belies the complexity of the immune response to threats. Immune responses vary widely and appropriately according to a spectrum of threats and only recently have the mechanisms for controlling this highly textured process emerged. A primary mechanism by which this controlled decision-making process is achieved is via Toll-like receptor (TLR) signaling and the subsequent activation of the immune response coincident with the presence of pathogenic organisms or antigens, including lipid mediators. While immune activation is important, the appropriate regulation of such responses is also critical. Recent findings indicate a parallel pathway by which responses to both viral and bacterial infections is controlled via the secretion of soluble TLR2 (sTLR2). sTLR2 is able to bind a wide range of pathogen-associated molecular patterns (PAMPs) and danger-associated molecular patterns (DAMPs). sTLR2 has been detected in many bodily fluids and is thus ubiquitous in sites of pathogen appearance. Interestingly, growing evidence suggests that sTLR2 functions to sequester PAMPs and DAMPs to avoid immune activation via detection of cellular-expressed TLRs. This immune regulatory function would serve to reduce the expression of the molecules required for cellular entry, and the recruitment of target cells following infection with bacteria and viruses. This review provides an overview of sTLR2 and the research regarding the mechanisms of its immune regulatory properties. Furthermore, the role of this molecule in regulating immune activation in the context of HIV infection via sTLR2 in breast milk provides actionable insights into therapeutic targets across a variety of infectious and inflammatory states. PMID:27531999

  16. Subclinical Congenital Cytomegalovirus Infection and Hearing Impairment

    ERIC Educational Resources Information Center

    Dahle, Arthur J.; And Others

    1974-01-01

    When the hearing sensitivity of children with subclinical congenital cytomegalovirus infection was evaluated and compared with that of a group of matched control subjects, nine of the 18 infected subjects were found to have some hearing loss, ranging from slight high-frequency impairments to a severe-to-profound unilateral loss. (MYS)

  17. CD4+ T Cells and Toll-Like Receptors Recognize Salmonella Antigens Expressed in Bacterial Surface Organelles

    PubMed Central

    Bergman, Molly A.; Cummings, Lisa A.; Barrett, Sara L. Rassoulian; Smith, Kelly D.; Lara, J. Cano; Aderem, Alan; Cookson, Brad T.

    2005-01-01

    A better understanding of immunity to infection is revealed from the characteristics of microbial ligands recognized by host immune responses. Murine infection with the intracellular bacterium Salmonella generates CD4+ T cells that specifically recognize Salmonella proteins expressed in bacterial surface organelles such as flagella and membrane vesicles. These natural Salmonella antigens are also ligands for Toll-like receptors (TLRs) or avidly associated with TLR ligands such as lipopolysaccharide (LPS). PhoP/PhoQ, a regulon controlling Salmonella virulence and remodeling of LPS to resist innate immunity, coordinately represses production of surface-exposed antigens recognized by CD4+ T cells and TLRs. These data suggest that genetically coordinated surface modifications may provide a growth advantage for Salmonella in host tissues by limiting both innate and adaptive immune recognition. PMID:15731032

  18. Role of Toll-Like Receptor Signaling in the Pathogenesis of Graft-versus-Host Diseases

    PubMed Central

    Tu, Sanfang; Zhong, Danli; Xie, Weixin; Huang, Wenfa; Jiang, Yangyang; Li, Yuhua

    2016-01-01

    Graft-versus-host disease (GVHD) and infection are major complications after allogeneic hematopoietic stem cell transplantation (allo-HSCT) and the leading causes of morbidity and mortality in HSCT patients. Recent work has demonstrated that the two complications are interdependent. GVHD occurs when allo-reactive donor T lymphocytes are activated by major histocompatibility antigens or minor histocompatibility antigens on host antigen-presenting cells (APCs), with the eventual attack of recipient tissues or organs. Activation of APCs is important for the priming of GVHD and is mediated by innate immune signaling pathways. Current evidence indicates that intestinal microbes and innate pattern-recognition receptors (PRRs) on host APCs, including both Toll-like receptors (TLRs) and nucleotide oligomerization domain (NOD)-like receptors (NLRs), are involved in the pathogenesis of GVHD. Patients undergoing chemotherapy and/or total body irradiation before allo-HSCT are susceptible to aggravated gastrointestinal epithelial cell damage and the subsequent translocation of bacterial components, followed by the release of endogenous dangerous molecules, termed pathogen-associated molecular patterns (PAMPs), which then activate the PRRs on host APCs to trigger local or systemic inflammatory responses that modulate T cell allo-reactivity against host tissues, which is equivalent to GVHD. In other words, infection can, to some extent, accelerate the progression of GVHD. Therefore, the intestinal flora’s PAMPs can interact with TLRs to activate and mature APCs, subsequently activate donor T cells with the release of pro-inflammatory cytokines, and eventually, induce GVHD. In the present article, we summarize the current perspectives on the understanding of different TLR signaling pathways and their involvement in the occurrence of GVHD. PMID:27529218

  19. Toll-like receptor and antimicrobial peptide expression in the bovine endometrium

    PubMed Central

    Davies, Darren; Meade, Kieran G; Herath, Shan; Eckersall, P David; Gonzalez, Deyarina; White, John O; Conlan, R Steven; O'Farrelly, Cliona; Sheldon, I Martin

    2008-01-01

    Background The endometrium is commonly infected with bacteria leading to severe disease of the uterus in cattle and humans. The endometrial epithelium is the first line of defence for this mucosal surface against bacteria and Toll-like receptors (TLRs) are a critical component of the innate immune system for detection of pathogen associated molecular patterns (PAMPs). Antimicrobial peptides, acute phase proteins and Mucin-1 (MUC-1) also provide non-specific defences against microbes on mucosal surfaces. The present study examined the expression of innate immune defences in the bovine endometrium and tested the hypothesis that endometrial epithelial cells express functional receptors of the TLR family and the non-specific effector molecules for defence against bacteria. Methods Bovine endometrial tissue and purified populations of primary epithelial and stromal cells were examined using RT-PCR for gene expression of TLRs, antimicrobial peptides and MUC-1. Functional responses were tested by evaluating the secretion of prostaglandin E2 and acute phase proteins when cells were treated with bacterial PAMPs such as bacterial lipopolysaccharide (LPS) and lipoproteins. Results The endometrium expressed TLRs 1 to 10, whilst purified populations of epithelial cells expressed TLRs 1 to 7 and 9, and stromal cells expressed TLRs 1 to 4, 6, 7, 9 and 10. The TLRs appear to be functional as epithelial cells secreted prostaglandin E2 in response to bacterial PAMPs. In addition, the epithelial cells expressed antimicrobial peptides, such as Tracheal and Lingual Antimicrobial Peptides (TAP and LAP) and MUC-1, which were upregulated when the cells were treated with LPS. However, the epithelial cells did not express appreciable amounts of the acute phase proteins haptoglobin or serum amyloid A. Conclusion Epithelial cells have an essential role in the orchestration of innate immune defence of the bovine endometrium and are likely to be the key to prevention of endometrial infection

  20. Novel Toll-like receptor-4 deficiency attenuates trastuzumab (Herceptin) induced cardiac injury in mice

    PubMed Central

    2011-01-01

    Background Cardiac inflammation and generation of oxidative stress are known to contribute to trastuzumab (herceptin) induced cardiac toxicity. Toll-like receptors (TLRs) are a part of the innate immune system and are involved in cardiac stress reactions. Since TLR4 might play a relevant role in cardiac inflammatory signaling, we investigated whether or not TLR4 is involved in trastuzumab induced cardiotoxicity. Methods Seven days after a single injection of herceptin (2 mg/kg; i.p.), left ventricular pressure volume loops were measured in HeN compotent (TLR4+/+) and HeJ mutant (TLR4-/-) treated with trastuzumab and control mice. Immunofluorescent staining for monocyte infiltration and analyses of plasma by (ELISAs) for different chemokines including: MCP-1and tumor necrosis factor-α (TNF-α), Western immunoblotting assay for ICAM-1, and used troponin I for cardiac injury marker. Results Trastuzumab injection resulted in an impairment of left ventricular function in TLR-4 competent (HeN), in contrast TLR4-/- trastuzumab mice showed improved left ventricular function EF%, CO; p < 0.05, attenuation of mononuclear cell infiltration in TLR4 -/-; p < 0.05 vs.TLR-4 competent (HeN), reduced level of cytokines TNF-α, MCP-1 and ICAM-1 expression in TLR4-/-, marked reduction of myocardial troponin-I levels in TLR4-deficient mice. Data are presented as means ± SE; n = 8 in each group p < 0.05 vs.TLR-4 competent (HeN). Conclusions Treatment with trastuzumab induces an inflammatory response that contributes to myocardial tissue TLR4 mediates chemokine expression (TNF-α, MCP-1and ICAM-1), so in experimental animals TLR4 deficiency improves left ventricular function and attenuates pathophysiological key mechanisms in trastuzumab induced cardiomyopathy. PMID:21999911

  1. A sustained increase in plasma NEFA upregulates the Toll-like receptor network in human muscle

    PubMed Central

    Hussey, Sophie E.; Lum, Helen; Alvarez, Andrea; Cipriani, Yolanda; Garduño-Garcia, José de Jesús; Anaya, Luis; Dube, John; Musi, Nicolas

    2014-01-01

    Aims/hypothesis Insulin-sensitive tissues (muscle, liver) of individuals with obesity and type 2 diabetes mellitus are in a state of low-grade inflammation, characterised by increased Toll-like receptor (TLR) expression and TLR-driven signalling. However, the cause of this mild inflammatory state is unclear. We tested the hypothesis that a prolonged mild increase in plasma NEFA will increase TLR expression and TLR-driven signalling (nuclear factor κB [NFκB] and mitogen-activated kinase [MAPK]) and impair insulin action in muscle of lean healthy individuals. Methods Twelve lean, normal-glucose-tolerant participants were randomised to receive a 48 h infusion (30 ml/h) of saline or Intralipid followed by a euglycaemic–hyperinsulinaemic clamp. Vastus lateralis muscle biopsies were performed before and during the clamp. Results Lipid infusion impaired insulin-stimulated IRS-1 tyrosine phosphorylation and reduced peripheral insulin sensitivity (p < 0.01). The elevation in circulating NEFA increased expression of TLR3, TLR4 and TLR5, and several MAPK (MAPK8, MAP4K4, MAP2K3) and inhibitor of κB kinase-NFκB (CHUK [IKKA], c-REL [REL] and p65 [RELA, NFKB3,p65]) signalling genes (p < 0.05). The lipid infusion also increased extracellular signal-regulated kinase (ERK) phosphorylation (p < 0.05) and tended to reduce the content of nuclear factor of light polypeptide gene enhancer in B cells inhibitor α (p = 0.09). The muscle content of most diacyglycerol, ceramide and acylcarnitine species was unaffected. In summary, insulin resistance induced by prolonged low-dose lipid infusion occurs together with increased TLR-driven inflammatory signalling and impaired insulin-stimulated IRS-1 tyrosine phosphorylation. Conclusions/interpretation A sustained, mild elevation in plasma NEFA is sufficient to increase TLR expression and TLR-driven signalling (NFκB and MAPK) in lean individuals. The activation of this pathway by NEFA may be involved in the pathogenesis of insulin

  2. Contributions of Unique Intracellular Domains to Switchlike Biosensing by Toll-like Receptor 4*

    PubMed Central

    Daringer, Nichole M.; Schwarz, Kelly A.; Leonard, Joshua N.

    2015-01-01

    Toll-like receptors (TLRs) mediate immune recognition of both microbial infections and tissue damage. Aberrant TLR signaling promotes disease; thus, understanding the regulation of TLR signaling is of medical relevance. Although downstream mediators of TLR signaling have been identified, the detailed mechanism by which ligand binding-mediated dimerization induces downstream signaling remains poorly understood. Here, we investigate this question for TLR4, which mediates responsiveness to bacterial LPS and drives inflammatory disease. TLR4 exhibits structural and functional features that are unique among TLRs, including responsiveness to a wide variety of ligands. However, the connection between these structural features and the regulation of signaling is not clear. Here, we investigated how the unique intracellular structures of TLR4 contribute to receptor signaling. Key conclusions include the following. 1) The unique intracellular linker of TLR4 is important for achieving LPS-inducible signaling via Toll/IL-1 receptor (TIR) domain-containing adapter-inducing interferon-β (TRIF) but less so for signaling via myeloid differentiation primary response 88 (MyD88). 2) Membrane-bound TLR4 TIR domains were sufficient to induce signaling. However, introducing long, flexible intracellular linkers neither induced constitutive signaling nor ablated LPS-inducible signaling. Thus, the initiation of TLR4 signaling is regulated by a mechanism that does not require tight geometric constraints. Together, these observations necessitate refining the model of TLR4 signal initiation. We hypothesize that TLR4 may interact with an inhibitory partner in the absence of ligand, via both TIR and extracellular domains of TLR4. In this speculative model, ligand binding induces dissociation of the inhibitory partner, triggering spontaneous, switchlike TIR domain homodimerization to initiate downstream signaling. PMID:25694428

  3. Age-related changes in expression and function of Toll-like receptors in human skin

    PubMed Central

    Iram, Nousheen; Mildner, Michael; Prior, Marion; Petzelbauer, Peter; Fiala, Christian; Hacker, Stefan; Schöppl, Alice; Tschachler, Erwin; Elbe-Bürger, Adelheid

    2012-01-01

    Toll-like receptors (TLRs) initiate innate immune responses and direct subsequent adaptive immunity. They play a major role in cutaneous host defense against micro-organisms and in the pathophysiology of several inflammatory skin diseases. To understand the role of TLRs in the acquisition of immunological competence, we conducted a comprehensive study to evaluate TLR expression and function in the developing human skin before and after birth and compared it with adults. We found that prenatal skin already expresses the same spectrum of TLRs as adult skin. Strikingly, many TLRs were significantly higher expressed in prenatal (TLRs 1-5) and infant and child (TLRs 1 and 3) skin than in adult skin. Surprisingly, neither dendritic cell precursors in prenatal skin nor epidermal Langerhans cells and dermal dendritic cells in adult skin expressed TLRs 3 and 6, whereas the staining pattern and intensity of both TLRs in fetal basal keratinocytes was almost comparable to those of adults. Stimulation of primary human keratinocytes from fetal, neonatal and adult donors with selected TLR agonists revealed that the synthetic TLR3 ligand poly (I:C) specifically, mimicking viral double-stranded RNA, induced a significantly enhanced secretion of CXCL8/IL8, CXCL10/IP-10 and TNFα in fetal and neonatal keratinocytes compared with adult keratinocytes. This study demonstrates quantitative age-specific modifications in TLR expression and innate skin immune reactivity in response to TLR activation. Thus, antiviral innate immunity already in prenatal skin may contribute to protect the developing human body from viral infections in utero in a scenario where the adaptive immune system is not yet fully functional. PMID:23034637

  4. Trichostatin A Protects Liver against Septic Injury through Inhibiting Toll-Like Receptor Signaling.

    PubMed

    Kim, So-Jin; Park, Jin-Sook; Lee, Do-Won; Lee, Sun-Mee

    2016-07-01

    Sepsis, a serious clinical problem, is characterized by a systemic inflammatory response to infection and leads to organ failure. Toll-like receptor (TLR) signaling is intimately implicated in hyper-inflammatory responses and tissue injury during sepsis. Histone deacetylase (HDAC) inhibitors have been reported to exhibit anti-inflammatory properties. The aim of this study was to investigate the hepatoprotective mechanisms of trichostatin A (TSA), a HDAC inhibitor, associated with TLR signaling pathway during sepsis. The anti-inflammatory properties of TSA were assayed in lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Polymicrobial sepsis was induced in mice by cecal ligation and puncture (CLP), a clinically relevant model of sepsis. The mice were intraperitoneally received TSA (1, 2 or 5 mg/kg) 30 min before CLP. The serum and liver samples were collected 6 and 24-h after CLP. TSA inhibited the increased production of tumor necrosis factor (TNF)-α and interleukin (IL)-6 in LPS-stimulated RAW264.7 cells. TSA improved sepsis-induced mortality, attenuated liver injury and decreased serum TNF-α and IL-6 levels. CLP increased the levels of TLR4, TLR2 and myeloid differentiation primary response protein 88 (MyD88) protein expression and association of MyD88 with TLR4 and TLR2, which were attenuated by TSA. CLP increased nuclear translocation of nuclear factor kappa B and decreased cytosolic inhibitor of kappa B (IκB) protein expression, which were attenuated by TSA. Moreover, CLP decreased acetylation of IκB kinase (IKK) and increased association of IKK with IκB and TSA attenuated these alterations. Our findings suggest that TSA attenuates liver injury by inhibiting TLR-mediated inflammatory response during sepsis. PMID:27068262

  5. Characterization of suppressive oligodeoxynucleotides that inhibit Toll-like receptor-9-mediated activation of innate immunity

    PubMed Central

    Peter, Mirjam; Bode, Konrad; Lipford, Grayson B; Eberle, Florian; Heeg, Klaus; Dalpke, Alexander H

    2008-01-01

    Synthetic oligodeoxynucleotides containing unmethylated CpG sequences (CpG-ODNs) stimulate Toll-like receptor-9 (TLR-9), thereby activating innate immunity. Stimulatory CpG-ODNs have been shown to be valuable in modifying immune responses in allergy, infection and cancer. Recently, it has been reported that the stimulation of TLR-9 by endogenous DNA might contribute to the pathogenesis of autoimmune diseases. We here report the identification of a suppressive, guanosine-rich ODN (G-ODN) that inhibited the activation of TLR-9 by stimulatory CpG-ODNs. The G-ODN was suppressive in murine macrophages and dendritic cells as well as in human plasmacytoid dendritic cells in vitro. G-ODN blocked the secretion of tumour necrosis factor-α (TNF-α) and interleukin-12p40 and interfered with the up-regulation of major histocompatibility complex (MHC) class II and costimulatory molecules. G-ODN was inhibitory even at a molar ratio of 1 : 10 (G-ODN:CpG-ODN) and when administered up to 7 hr after stimulation with CpG. G-ODN specifically inhibited TLR-9 but not other TLRs. Inhibition was dependent on a string of five guanosines. G-ODN was also inhibitory in an in vivo model of CpG/galactosamin (GalN) lethal shock. G-ODN interfered with upstream TLR-9 signalling. However, by extensive analysis we can exclude that G-ODN acts at the stage of cellular uptake. G-ODN therefore represents a class of suppressive ODNs that could be of therapeutic use in situations with pathologic TLR-9 activation, as has been proposed for certain autoimmune diseases. PMID:17961163

  6. Identification and functional characterization of nonmammalian Toll-like receptor 20.

    PubMed

    Pietretti, Danilo; Scheer, Marleen; Fink, Inge R; Taverne, Nico; Savelkoul, Huub F J; Spaink, Herman P; Forlenza, Maria; Wiegertjes, Geert F

    2014-02-01

    Like other vertebrate Toll-like receptors (TLRs), the TLRs of teleost fish can be subdivided into six major families, each of which recognize a general class of molecular patterns. However, there also are a number of Tlrs with unknown function, the presence of which seems unique to the bony fish, among which is Tlr20. We identified full-length complementary DNA (cDNA) sequences for tlr20 of zebrafish and common carp, two closely related fish species. Zebrafish have six copies of tlr20, whereas carp express only a single copy. Both zebrafish Tlr20 (at least Tlr20a-d) and carp Tlr20 have 26 leucine-rich repeats (LRRs). Three-dimensional modeling indicates a best fit to the crystal structure of TLR8. Phylogenetic analyses place Tlr20 in the TLR11 family closest to Tlr11 and Tlr12, which sense ligands from protozoan parasites in the mouse. Conservation of genes on zebrafish chromosome 9, which carries tlr20, with genes on mouse chromosome 14, which carries tlr11, indicates Tlr11 could be a possible ortholog of Tlr20. Confocal microscopy suggests a subcellular localization of Tlr20 at the endoplasmatic reticulum. Although in vitro reporter assays could not identify a ligand unique to Tlr20, in vivo infection experiments indicate a role for Tlr20 in the immune response of carp to protozoan parasites (Trypanoplasma borreli). Carp tlr20 is mainly expressed in peripheral blood leukocytes (PBL) with B lymphocytes, in particular, expressing relatively high levels of Tlr20. In vitro stimulation of PBL with T. borreli induces an upregulation of tlr20, supportive of a role for Tlr20 in the immune response to protozoan parasites. PMID:24327191

  7. TSLP expression induced via Toll-like receptor pathways in human keratinocytes.

    PubMed

    Takai, Toshiro; Chen, Xue; Xie, Yang; Vu, Anh Tuan; Le, Tuan Anh; Kinoshita, Hirokazu; Kawasaki, Junko; Kamijo, Seiji; Hara, Mutsuko; Ushio, Hiroko; Baba, Tadashi; Hiramatsu, Keiichi; Ikeda, Shigaku; Ogawa, Hideoki; Okumura, Ko

    2014-01-01

    The skin epidermis and mucosal epithelia (airway, ocular tissues, gut, and so on) are located at the interface between the body and environment and have critical roles in the response to various stimuli. Thymic stromal lymphopoietin (TSLP), a cytokine expressed mainly by epidermal keratinocytes (KCs) and mucosal epithelial cells, is a critical factor linking the innate response at barrier surfaces to Th2-skewed acquired immune response. TSLP is highly expressed in skin lesions of atopic dermatitis patients. Here, we describe on Toll-like receptor (TLR)-mediated induction of TSLP expression in primary cultured human KCs, placing emphasis on experimental methods used in our studies. Double-stranded RNA (TLR3 ligand), flagellin (TLR5 ligand), and diacylated lipopeptide (TLR2-TLR6 ligand) stimulated human KCs to express TSLP and Staphylococcus aureus membranes did so via the TLR2-TLR6 pathway. Atopic cytokine milieu upregulated the TLR-mediated induction of TSLP. Culturing in the absence of glucocorticoid before stimulation enhanced the TSLP expression. Extracellular double-stranded RNA induced TSLP via endosomal acidification- and NF-κB-dependent pathway. Specific measurement of the long TSLP transcript, which contributes to the production of the TSLP protein, rather than total or the short transcript is useful for accurate detection of functional human TSLP gene expression. The results suggest that environment-, infection-, and/or self-derived TLR ligands contribute to the initiation and/or amplification of Th2-type skin inflammation including atopic dermatitis and atopic march through the induction of TSLP expression in KCs and include information helpful for understanding the role of the gene-environment interaction relevant in allergic diseases. PMID:24377934

  8. Insights into the Relationship between Toll Like Receptors and Gamma Delta T Cell Responses

    PubMed Central

    Dar, Asif Amin; Patil, Rushikesh Sudam; Chiplunkar, Shubhada Vivek

    2014-01-01

    The tumor microenvironment is an important aspect of cancer biology that contributes to tumor initiation, tumor progression and responses to therapy. The composition and characteristics of the tumor microenvironment vary widely and are important in determining the anti-tumor immune response. Successful immunization requires activation of both innate and adaptive immunity. Generally, immune system is compromised in patients with cancer due to immune suppression, loss of tumor antigen expression and dysfunction of antigen presenting cells (APC). Thus, therapeutic immunization leading to cancer regression remains a significant challenge. Certain cells of the immune system, including dendritic cells (DCs) and gamma delta (γδ) T cells are capable of driving potent anti-tumor responses. The property of MHC-unrestricted cytotoxicity, high potential of cytokine release, tissue tropism and early activation in infections and malignant disease makes γδ T cells as an emerging candidate for immunotherapy. Various strategies are being developed to enhance anti-tumor immune responses of γδ T cells and DCs one of them is the use of novel adjuvants like toll like receptors (TLR) agonists, which enhance γδ T cell function directly or through DC activation, which has ability to prime γδ T cells. TLR agonists are being used clinically either alone or in combination with tumor antigens and has shown initial success in both enhancing immune responses and eliciting anti-tumor activity. TLR activated γδ T cells and DCs nurture each other’s activation. This provides a potent base for first line of defense and manipulation of the adaptive response against pathogens and cancer. The available data provides a strong rationale for initiating combinatorial therapy for the treatment of diseases and this review will summarize the application of adjuvants (TLRs) for boosting immune response of γδ T cells to treat cancer and infectious diseases and their use in combinatorial therapy

  9. Activation of human and chicken toll-like receptors by Campylobacter spp.

    PubMed

    de Zoete, Marcel R; Keestra, A Marijke; Roszczenko, Paula; van Putten, Jos P M

    2010-03-01

    Campylobacter infection in humans is accompanied by severe inflammation of the intestinal mucosa, in contrast to colonization of chicken. The basis for the differential host response is unknown. Toll-like receptors (TLRs) sense and respond to microbes in the body and participate in the induction of an inflammatory response. Thus far, the interaction of Campylobacter with chicken TLRs has not been studied. Here, we investigated the potential of four Campylobacter strains to activate human TLR1/2/6, TLR4, TLR5, and TLR9 and chicken TLR2t2/16, TLR4, TLR5, and TLR21. Live bacteria showed no or very limited potential to activate TLR2, TLR4, and TLR5 of both the human and chicken species, with minor but significant differences between Campylobacter strains. In contrast, lysed bacteria induced strong NF-kappaB activation through human TLR1/2/6 and TLR4 and chicken TLR2t2/16 and TLR4 but not via TLR5 of either species. Interestingly, C. jejuni induced TLR4-mediated beta interferon in human but not chicken cells. Furthermore, isolated chromosomal Campylobacter DNA was unable to activate human TLR9 in our system, whereas chicken TLR21 was activated by DNA from all of the campylobacters tested. Our data are the first comparison of TLR-induced immune responses in humans and chickens. The results suggest that differences in bacterial cell wall integrity and in TLR responses to Campylobacter LOS and/or DNA may contribute to the distinct clinical manifestation between the species. PMID:20038539

  10. Activation of Human and Chicken Toll-Like Receptors by Campylobacter spp.▿

    PubMed Central

    de Zoete, Marcel R.; Keestra, A. Marijke; Roszczenko, Paula; van Putten, Jos P. M.

    2010-01-01

    Campylobacter infection in humans is accompanied by severe inflammation of the intestinal mucosa, in contrast to colonization of chicken. The basis for the differential host response is unknown. Toll-like receptors (TLRs) sense and respond to microbes in the body and participate in the induction of an inflammatory response. Thus far, the interaction of Campylobacter with chicken TLRs has not been studied. Here, we investigated the potential of four Campylobacter strains to activate human TLR1/2/6, TLR4, TLR5, and TLR9 and chicken TLR2t2/16, TLR4, TLR5, and TLR21. Live bacteria showed no or very limited potential to activate TLR2, TLR4, and TLR5 of both the human and chicken species, with minor but significant differences between Campylobacter strains. In contrast, lysed bacteria induced strong NF-κB activation through human TLR1/2/6 and TLR4 and chicken TLR2t2/16 and TLR4 but not via TLR5 of either species. Interestingly, C. jejuni induced TLR4-mediated beta interferon in human but not chicken cells. Furthermore, isolated chromosomal Campylobacter DNA was unable to activate human TLR9 in our system, whereas chicken TLR21 was activated by DNA from all of the campylobacters tested. Our data are the first comparison of TLR-induced immune responses in humans and chickens. The results suggest that differences in bacterial cell wall integrity and in TLR responses to Campylobacter LOS and/or DNA may contribute to the distinct clinical manifestation between the species. PMID:20038539