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Sample records for complex antigens inhibition

  1. Inhibition of Class II Major Histocompatibility Complex Antigen Processing by Escherichia coli Heat-Labile Enterotoxin Requires an Enzymatically Active A Subunit

    PubMed Central

    Matousek, Milita P.; Nedrud, John G.; Cieplak, Witold; Harding, Clifford V.

    1998-01-01

    Escherichia coli heat-labile enterotoxin (LT) and cholera toxin (CT) were found to inhibit intracellular antigen processing. Processing was not inhibited by mutant LT with attenuated ADP-ribosyltransferase activity, CT B or LT B subunit, which enhanced presentation of preexisting cell surface peptide-class II major histocompatibility complex complexes. Inhibition of antigen processing correlated with A subunit ADP-ribosyltransferase activity. PMID:9632629

  2. An Annular Lipid Belt Is Essential for Allosteric Coupling and Viral Inhibition of the Antigen Translocation Complex TAP (Transporter Associated with Antigen Processing)*

    PubMed Central

    Eggensperger, Sabine; Fisette, Olivier; Parcej, David; Schäfer, Lars V.; Tampé, Robert

    2014-01-01

    The transporter associated with antigen processing (TAP) constitutes a focal element in the adaptive immune response against infected or malignantly transformed cells. TAP shuttles proteasomal degradation products into the lumen of the endoplasmic reticulum for loading of major histocompatibility complex (MHC) class I molecules. Here, the heterodimeric TAP complex was purified and reconstituted in nanodiscs in defined stoichiometry. We demonstrate that a single heterodimeric core-TAP complex is active in peptide binding, which is tightly coupled to ATP hydrolysis. Notably, with increasing peptide length, the ATP turnover was gradually decreased, revealing that ATP hydrolysis is coupled to the movement of peptide through the ATP-binding cassette transporter. In addition, all-atom molecular dynamics simulations show that the observed 22 lipids are sufficient to form an annular belt surrounding the TAP complex. This lipid belt is essential for high affinity inhibition by the herpesvirus immune evasin ICP47. In conclusion, nanodiscs are a powerful approach to study the important role of lipids as well as the function, interaction, and modulation of the antigen translocation machinery. PMID:25305015

  3. Major Histocompatibility Complex Class II Inhibits Fas Antigen-Mediated Gastric Mucosal Cell Apoptosis through Actin-Dependent Inhibition of Receptor Aggregation

    PubMed Central

    Stoicov, Calin; Cai, Xun; Li, Hanchen; Klucevsek, Kristine; Carlson, Jane; Saffari, Reza; Houghton, JeanMarie

    2005-01-01

    Escape from normal apoptotic controls is thought to be essential for the development of cancer. During Helicobacter pylori infection, the leading cause of gastric cancer, activation of the Fas antigen (Fas Ag) apoptotic pathway is responsible for early atrophy and tissue loss. As disease progresses, metaplastic and dysplastic glands arise which express Fas Ag but are resistant to apoptosis and are believed to be the precursor cells for adenocarcinoma. In this report, we show that one mechanism of acquired Fas resistance is inhibition of receptor aggregation via a major histocompatibility complex class II (MHCII)-mediated, actin-dependent mechanism. For these studies we used the well-described C57BL/6 mouse model of Helicobacter pylori and Helicobacter felis infection. Under normal conditions, Fas Ag is expressed at low levels, and MHCII expression on gastric mucosal cells is negligible. With infection and inflammation, both receptors are upregulated, and 6.1% of gastric mucosal cells express MHCII in combination with Fas Ag. Using the rat gastric mucosal cell line RGM-1 transfected with murine Fas Ag and MHCIIαβ chains, we demonstrate that MHCII prevents Fas receptor aggregation and inhibits Fas-mediated signaling through its effects on the actin cytoskeleton. Depolymerization of actin with cytochalasin D allows receptors to aggregate and restores Fas sensitivity. These findings offer one mechanism by which gastric mucosal cells acquire Fas resistance. PMID:16177302

  4. Inhibition of Intracellular Transport of B Cell Antigen Receptor Complexes by Kaposi's Sarcoma–Associated Herpesvirus K1

    PubMed Central

    Lee, Bok-Soo; Alvarez, Xavier; Ishido, Satoshi; Lackner, Andrew A.; Jung, Jae U.

    2000-01-01

    The B cell antigen receptor (BCR) is a large complex that consists of a disulfide-linked tetramer of two transmembrane heavy (μ) chains and two light (λ or κ) chains in association with a heterodimer of Igα and Igβ. Kaposi's sarcoma–associated herpesvirus (KSHV) encodes a transforming protein called K1, which has structural and functional similarity to Igα and Igβ. We demonstrate that K1 downregulates the expression of BCR complexes on the surface. The NH2-terminal region of K1 specifically interacts with the μ chains of BCR complexes, and this interaction retains BCR complexes in the endoplasmic reticulum, preventing their intracellular transport to the cell surface. Thus, KSHV K1 resembles Igα and Igβ in its ability to induce signaling and to interact with μ chains of the BCR. However, unlike Igα and Igβ, which interact with μ chains to direct BCR complexes to the cell surface, K1 interacts with μ chains to block the intracellular transport of BCR complexes to the cell surface. These results demonstrate a unique feature of the K1 transforming protein, which may confer virus-infected cells with a long-term survival advantage. PMID:10880522

  5. Cyclosporine inhibits macrophage-mediated antigen presentation

    SciTech Connect

    Ziegler, H.K.; Palay, D.; Wentworth, P.; Cluff, C.

    1986-03-01

    The influence of cyclosporine on antigen-specific, macrophage-dependent T cell activation was analyzed in vitro. Murine T cell activation by antigens derived from Listeria monocytogenes was monitored by the production of interleukin-2. Pretreatment (2 hrs., 37/sup 0/C) of macrophages with cyclosporine resulted in a population of macrophages with a markedly diminished capacity to support the activation of T lymphocytes. When cyclosporine-pretreated macrophages were added to cultures of antigen and untreated T cells, the dose of cyclosporine which produced 50% inhibition was 1.5 ..mu..g/ml. Appropriate control experiments indicated that cyclosporine was indeed inhibiting at the macrophage level. The addition of interleukin-1 or indomethacin to the cultures did not alter the inhibitory effect of cyclosporine. Under conditions which produced >90% inhibition of antigen presentation, macrophage surface Ia expression was not altered, and the uptake and catabolism of radiolabelled antigen was normal. Thus, cyclosporine inhibits antigen presentation by a mechanism which appears unrelated to changes in Il-1 elaboration, prostaglandin production, Ia expression, or antigen uptake and catabolism.

  6. Immunosuppressant deoxyspergualin inhibits antigen processing in monocytes.

    PubMed

    Hoeger, P H; Tepper, M A; Faith, A; Higgins, J A; Lamb, J R; Geha, R S

    1994-11-01

    Deoxyspergualin (DSG) is a novel immunosuppressive agent recently shown to bind to the constitutive heat shock protein 70, which is involved in binding and intracellular transport of antigenic peptides. In this study, we show that DSG inhibits the proliferation of PBMCs to the Ags tetanus toxoid and diphtheria toxoid, but not to the mitogens PHA and PMA/ionomycin, nor to the superantigens toxic shock syndrome toxin-1 and staphylococcal enterotoxin A. DSG's effect was specific for monocytes as preincubation of T cells with DSG did not inhibit their proliferation to monocytes pulsed with tetanus toxoid Ag for 16 h, whereas the presence of DSG during Ag pulsing of the monocytes inhibited their ability to stimulate T cell proliferation. DSG did not down-regulate the expression of MHC class II molecules by monocytes, and the inhibitory effect of DSG on T cell proliferation was not reversed by the addition of IL-2, nor by the addition of the costimulatory signals IL-1, IL-6, and anti-CD28. Studies with two human T cell clones, HA1.7 and PF5, specific, respectively, to peptides spanning amino acids 307-319 and 256-270 of influenza hemagglutinin, showed that DSG inhibited the proliferation of the clones to the native hemagglutinin molecule but minimally affected their proliferation to the peptides. These data suggest that DSG interferes with Ag processing and/or presentation. PMID:7930603

  7. Inhibition by chloroquine of the class II major histocompatibility complex-restricted presentation of endogenous antigens varies according to the cellular origin of the antigen-presenting cells, the nature of the T-cell epitope, and the responding T cell.

    PubMed Central

    Lombard-Platlet, S; Bertolino, P; Deng, H; Gerlier, D; Rabourdin-Combe, C

    1993-01-01

    Chloroquine treatment of antigen-presenting cells (APC) was explored as a tool to investigate the processing pathway for major histocompatibility complex (MHC) class II-restricted presentation of the endogenous secreted hen egg lysozyme (HEL) and transmembrane measles virus haemagglutinin (HA). A 72-hr pretreatment of the APC with 25 microM chloroquine blocked the presentation of the HEL(52-61) T-cell epitope generated from endogenous HEL to the I-Ak-restricted 3A9 T-cell hybridoma by MHC class II-transfected L cells expressing the invariant chain (Ii). The presentation of exogenously added HEL peptides was not affected. Under the same conditions, no inhibition of the presentation of HEL(106-116) to the I-Ed-restricted G28 high-avidity T-cell hybridoma, nor of HA when synthesized by L cells, was observed. When B-lymphoid APC were used, inhibition was observed in every case with a low number of B APC pretreated for 48 hr with chloroquine prior to the T-cell stimulation test. Moreover, addition of chloroquine to untreated B APC during the T-cell stimulation assay was sufficient to inhibit completely the presentation of HEL(106-116) to the B10.D24.42 low avidity T-cell hybridoma. Altogether these studies suggest that an apparent resistance of endogenous Ag presentation to chloroquine inhibition may not necessarily indicate the existence of a non-endosomal pathway but may be due to the nature of the T-cell epitope, to the use of 'non-professional' APC such as L cells, to the use of T cells of high avidity, and to high amounts of pre-existing MHC class II-peptide complexes expressed by the APC. We demonstrate here that, at least in conventional APC such as B cells, class II-restricted presentation of both endogenous secreted HEL and transmembrane HA involves an endosomal pathway. PMID:7508420

  8. T-antigen-DNA polymerase alpha complex implicated in simian virus 40 DNA replication.

    PubMed Central

    Smale, S T; Tjian, R

    1986-01-01

    We have combined in vitro DNA replication reactions and immunological techniques to analyze biochemical interactions between simian virus (SV40) large T antigen and components of the cellular replication apparatus. First, in vitro SV40 DNA replication was characterized with specific origin mutants. Next, monoclonal antibodies were used to demonstrate that a specific domain of T antigen formed a complex with cellular DNA polymerase alpha. Several antibodies were identified that coprecipitated T antigen and DNA polymerase alpha, while others were found to selectively prevent this interaction and concomitantly inhibit DNA replication. DNA polymerase alpha also bound efficiently to a T-antigen affinity column, confirming the immunoprecipitation results and providing a useful method for purification of the complete protein complex. Taken together, these results suggest that the T-antigen-polymerase association may be a key step in the initiation of SV40 DNA replication. Images PMID:3025630

  9. Complex Antigens Drive Permissive Clonal Selection in Germinal Centers.

    PubMed

    Kuraoka, Masayuki; Schmidt, Aaron G; Nojima, Takuya; Feng, Feng; Watanabe, Akiko; Kitamura, Daisuke; Harrison, Stephen C; Kepler, Thomas B; Kelsoe, Garnett

    2016-03-15

    Germinal center (GC) B cells evolve toward increased affinity by a Darwinian process that has been studied primarily in genetically restricted, hapten-specific responses. We explored the population dynamics of genetically diverse GC responses to two complex antigens-Bacillus anthracis protective antigen and influenza hemagglutinin-in which B cells competed both intra- and interclonally for distinct epitopes. Preferred VH rearrangements among antigen-binding, naive B cells were similarly abundant in early GCs but, unlike responses to haptens, clonal diversity increased in GC B cells as early "winners" were replaced by rarer, high-affinity clones. Despite affinity maturation, inter- and intraclonal avidities varied greatly, and half of GC B cells did not bind the immunogen but nonetheless exhibited biased VH use, V(D)J mutation, and clonal expansion comparable to antigen-binding cells. GC reactions to complex antigens permit a range of specificities and affinities, with potential advantages for broad protection. PMID:26948373

  10. Trade-offs in antibody repertoires to complex antigens

    PubMed Central

    Childs, Lauren M.; Baskerville, Edward B.; Cobey, Sarah

    2015-01-01

    Pathogens vary in their antigenic complexity. While some pathogens such as measles present a few relatively invariant targets to the immune system, others such as malaria display considerable antigenic diversity. How the immune response copes in the presence of multiple antigens, and whether a trade-off exists between the breadth and efficacy of antibody (Ab)-mediated immune responses, are unsolved problems. We present a theoretical model of affinity maturation of B-cell receptors (BCRs) during a primary infection and examine how variation in the number of accessible antigenic sites alters the Ab repertoire. Naive B cells with randomly generated receptor sequences initiate the germinal centre (GC) reaction. The binding affinity of a BCR to an antigen is quantified via a genotype–phenotype map, based on a random energy landscape, that combines local and distant interactions between residues. In the presence of numerous antigens or epitopes, B-cell clones with different specificities compete for stimulation during rounds of mutation within GCs. We find that the availability of many epitopes reduces the affinity and relative breadth of the Ab repertoire. Despite the stochasticity of somatic hypermutation, patterns of immunodominance are strongly shaped by chance selection of naive B cells with specificities for particular epitopes. Our model provides a mechanistic basis for the diversity of Ab repertoires and the evolutionary advantage of antigenically complex pathogens. PMID:26194759

  11. Gonococcal pilus vaccine. Studies of antigenicity and inhibition of attachment.

    PubMed Central

    Tramont, E C; Sadoff, J C; Boslego, J W; Ciak, J; McChesney, D; Brinton, C C; Wood, S; Takafuji, E

    1981-01-01

    A gonococcal pilus vaccine or placebo was injected subcutaneously or intramuscularly into 71 human volunteers. The vaccine was found to be safe. The principal adverse reaction was a complaint of a sore arm, which was caused, at least in part, to the volume of material injected. 6 of 64 (9%) volunteers receiving the larger doses also complained of malaise. The vaccine was found to be antigenic. All of the volunteers developed an immunoglobulin class-specific antibody response as measured by a solid phase radioimmunoassay. The antibody was capable of blocking the attachment of gonococci to epithelial cells. A slight antibody response was also demonstrated to gonococcal lipopolysaccharide but the antibody responsible for blocking attachment of gonococci was directed entirely at the pilus protein. The stimulated antibodies were shown to crossreact with isolated pili of heterologous gonococcal strains and to block the attachment of heterologous gonococci. Absorption of immune sera by a heterologous pilus reduced the inhibition of attachment antibodies to pre-immune level, suggesting that the immune response was directed at a common pilus determinant. PMID:6116723

  12. Enhanced Direct Major Histocompatibility Complex Class I Self-Antigen Presentation Induced by Chlamydia Infection

    PubMed Central

    Cram, Erik D.; Simmons, Ryan S.; Palmer, Amy L.; Hildebrand, William H.; Rockey, Daniel D.

    2015-01-01

    The direct major histocompatibility complex (MHC) class I antigen presentation pathway ensures intracellular peptides are displayed at the cellular surface for recognition of infected or transformed cells by CD8+ cytotoxic T lymphocytes. Chlamydia spp. are obligate intracellular bacteria and, as such, should be targeted by CD8+ T cells. It is likely that Chlamydia spp. have evolved mechanisms to avoid the CD8+ killer T cell responses by interfering with MHC class I antigen presentation. Using a model system of self-peptide presentation which allows for posttranslational control of the model protein's stability, we tested the ability of various Chlamydia species to alter direct MHC class I antigen presentation. Infection of the JY lymphoblastoid cell line limited the accumulation of a model host protein and increased presentation of the model-protein-derived peptides. Enhanced self-peptide presentation was detected only when presentation was restricted to defective ribosomal products, or DRiPs, and total MHC class I levels remained unaltered. Skewed antigen presentation was dependent on a bacterial synthesized component, as evidenced by reversal of the observed phenotype upon preventing bacterial transcription, translation, and the inhibition of bacterial lipooligosaccharide synthesis. These data suggest that Chlamydia spp. have evolved to alter the host antigen presentation machinery to favor presentation of defective and rapidly degraded forms of self-antigen, possibly as a mechanism to diminish the presentation of peptides derived from bacterial proteins. PMID:26597986

  13. Immune complexes that contain HIV antigens activate peripheral blood T cells.

    PubMed

    Korolevskaya, L B; Shmagel, K V; Saidakova, E V; Shmagel, N G; Chereshnev, V A

    2016-07-01

    Uninfected donor T cells were treated in vitro by model immune complexes that contained either HIV or hepatitis C virus (HCV) antigens. Unlike HCV antigen-containing complexes, the immune complexes that contained HIV antigens have been shown to activate peripheral blood T cells of uninfected donors under in vitro conditions. Both the antiviral antibodies and HIV antigen were involved in the activation process. The unique properties of the immune complexes formed by HIV antigens and antiviral antibodies are believed to result from the virus-specific antibody properties and molecular conformation of the antigen-antibody complex. PMID:27595830

  14. Effective Inhibition of Kb- and Db-Restricted Antigen Presentation in Primary Macrophages by Murine Cytomegalovirus

    PubMed Central

    LoPiccolo, Diane M.; Gold, Marielle C.; Kavanagh, Daniel G.; Wagner, Markus; Koszinowski, Ulrich H.; Hill, Ann B.

    2003-01-01

    Macrophages play an important role in murine cytomegalovirus (MCMV) infection in vivo, both in disseminating infection and in harboring latent virus. MCMV encodes three immune evasion genes (m4, m6, and m152) that interfere with the ability of cytotoxic T cells (CTL) to detect virus-infected fibroblasts, but the efficacy of immune evasion in macrophages has been controversial. Here we show that MCMV immune evasion genes function in H-2b primary bone marrow macrophages (BMMφ) in the same way that they do in fibroblasts. Metabolic labeling experiments showed that class I is retained in the endoplasmic reticulum by MCMV infection and associates with m4/gp34 to a similar extent in fibroblasts and BMMφ. We tested a series of Kb- and Db-restricted CTL clones specific for MCMV early genes against a panel of MCMV wild-type virus and mutants lacking m152, m4, or m6. MCMV immune evasion genes effectively inhibited antigen presentation. m152 appeared sufficient to abolish Db-restricted presentation in infected macrophages, as has been previously observed in infected fibroblasts. However, for inhibition of recognition of infected macrophages by Kb-restricted CTL, m4, m6, and m152 were all required. The contribution of m4 to inhibition of recognition appeared much more important in macrophages than in fibroblasts. Thus, MCMV immune evasion genes function effectively in primary macrophages to prevent CTL recognition of early antigens and show the same pattern of major histocompatibility complex class I allele discrimination as is seen in fibroblasts. Furthermore, for inhibition of Kb-restricted presentation, a strong synergistic effect was noted among m152, m4, and m6. PMID:12477835

  15. Electron Microscopic Studies of the Antigen-Antibody Complex

    PubMed Central

    Easty, G. C.; Mercer, E. H.

    1958-01-01

    Electron micrographs of the ferritin antibody (rabbit) and ferritin (horse) complex have been obtained. The high iron content of the ferritin molecule (23 per cent Fe) allows its molecules to be recognized within the particles of precipitate. Three methods of visualizing the molecular distribution have been developed: (a) small particles of the precipitated complex have been dried on to electron microscope grids and either examined directly or first shadowed with metal and then examined, (b) the precipitate has been centrifuged to a plug which was embedded and thin sections cut from it for examination, (c) the bands formed by allowing antibody and antigen to diffuse together in agar gels have been fixed, embedded and sectioned. All methods have yielded pictures of the distribution of the ferritin within the complex which are broadly similar to what might have been expected from a somewhat irregular lattice as pictured in the Marrack-Heidelberger Lattice Theory. The antibody molecules are not clearly defined but appear as a halo of low density enveloping the ferritin clusters. The distance, centre to centre, between the ferritin molecules is variable, but is, on the average, in the range 200–400 Å. This is greater than the ferritin-ferritin contact distance (100 Å) and is thought to mean that the ferritin molecules are bridged by antibody molecules as pictured in the Lattice Theory. The bands produced in the gel-diffusion test contain islands of ferritin-antibody complex. When equivalent concentrations of reagents are used a single band of precipitate is formed. When excess of either antigen or antibody is used multiple bands of precipitate are formed which contain islands of ferritin antibody complex indistinguishable from those formed in the single band at equivalent concentrations, providing direct evidence for the formation of multiple bands from a single antigen. Ferritin-ferritin contacts have been observed within the complex. Under all the conditions of

  16. Efficient major histocompatibility complex class I presentation of exogenous antigen upon phagocytosis by macrophages.

    PubMed Central

    Kovacsovics-Bankowski, M; Clark, K; Benacerraf, B; Rock, K L

    1993-01-01

    Antigens in extracellular fluids can be processed and presented with major histocompatibility complex (MHC) class I molecules by a subset of antigen presenting cells (APCs). Chicken egg ovalbumin (Ova) linked to beads was presented with MHC class I molecules by these cells up to 10(4)-fold more efficiently than soluble Ova. This enhanced presentation was observed with covalently or noncovalently linked Ova and with beads of different compositions. A key parameter in the activity of these conjugates was the size of the beads. The APC that is responsible for this form of presentation is a macrophage. These cells internalize the antigen constructs through phagocytosis, since cytochalasin B inhibited presentation. Processing of the antigen and association with MHC class I molecules appears to occur intracellularly as presentation was observed under conditions where there was no detectable release of peptides into the extracellular fluids. When injected in vivo in C57BL/6 mice, Ova-beads, but not soluble Ova, primed CD4- CD8+ cytotoxic T lymphocytes (CTLs). Similar results were obtained in BALB/c mice immunized with beta-galactosidase-beads. The implications of these findings for development of nonliving vaccines that stimulate CTL immunity are discussed. PMID:8506338

  17. Monomeric and oligomeric complexes of the B cell antigen receptor.

    PubMed

    Schamel, W W; Reth, M

    2000-07-01

    The current structural model of the B cell antigen receptor (BCR) describes it as a symmetric protein complex in which one membrane-bound immunoglobulin molecule (mIg) is noncovalently bound on each side by an Ig-alpha/Ig-beta heterodimer. Using peptide-tagged Ig-alpha proteins, blue native polyacrylamide gel electrophoresis (BN-PAGE), and biosynthetical labeling of B cells, we find that the mIg:Ig-alpha/Ig-beta complex has a stoichiometry of 1:1 and not 1:2. An anti-Flag stimulation of B cells coexpressing Flag-tagged and wild-type Ig-alpha proteins results in the phosphorylation of both Ig-alpha proteins, suggesting that on the surface of living B cells, several BCR monomers are in contact with each other. A BN-PAGE analysis after limited detergent lysis provides further evidence for an oligomeric BCR structure. PMID:10933390

  18. Antigen

    MedlinePlus

    An antigen is any substance that causes your immune system to produce antibodies against it. This means your immune ... and is trying to fight it off. An antigen may be a substance from the environment, such ...

  19. Antigens of Lyme disease of spirochaete Borrelia burgdorferi inhibits antigen or mitogen-induced lymphocyte proliferation.

    PubMed

    Chiao, J W; Pavia, C; Riley, M; Altmann-Lasekan, W; Abolhassani, M; Liegner, K; Mittelman, A

    1994-02-01

    Modulation of cellular immune responses by the spirochaete Borrelia burgdorferi, the bacteria that causes Lyme disease, was demonstrated. When cultured in the presence of sonicated Borrelia preparation (Bb), the mitogen- or antigen-stimulated proliferative responses of normal lymphocytes were consistently lowered. Bb caused the greatest reduction in Concanavalin A (ConA) or antigen-stimulated proliferation, where almost 100% reduction in proliferation could be achieved. Bb also reduced phytohemagglutinin-M (PHA) or pokeweed mitogen (PWM)-stimulated peripheral blood lymphocyte (PBL) proliferation, with the PWM proliferation being the least affected. This regulatory activity was not due to toxicity and was determined to be caused by Bb protein antigens. The degree of the proliferation reduction was directly proportional to both Bb quantity and length of exposure to lymphocytes. IL-2 production was significantly reduced from Bb-exposed lymphocytes. The entry of lymphocytes into the proliferating phases of the cell cycle was also shown to be blocked. These results have demonstrated an immune suppressive mechanism of B. burgdorferi. The magnitude of host immune responses may be dependent on the degree of suppression which is related to the spirochaete quantity and their length of presence in the host. PMID:8173554

  20. Optimisation of immuno-gold nanoparticle complexes for antigen detection.

    PubMed

    van der Heide, Susan; Russell, David A

    2016-06-01

    The aim of this investigation was to define the optimum method of binding antibodies to the surface of gold nanoparticles (AuNPs) and then to apply the optimised antibody-functionalised AuNPs for the detection of a target antigen. A detailed investigation of three different techniques for the functionalisation of AuNPs with anti-cocaine antibody and methods for the subsequent characterisation of the antibody-functionalised AuNP are reported. The addition of anti-cocaine antibody onto the AuNP surface was facilitated by either: a polyethylene glycol (PEG) linker with a COOH terminal functional group; an aminated PEG ligand; or an N-succinimidyl 3-(2-pyridyldithio)-propionate (SPDP)-Protein A/G intermediate. Characterisation of the functionalised particles was performed using transmission electron microscopy, UV-Visible spectrophotometry and by agarose gel electrophoresis. In addition, the cocaine binding efficacy of the resultant AuNPs and their cocaine-binding capacity was determined using a cocaine-horseradish peroxidase conjugate, and by the application of a microtiter plate-based immunoassay. The results showed that the number of antibody per particle was the highest when the AuNP were functionalised with the Protein A/G intermediate. As compared to free antibody, the cocaine binding efficacy was significantly enhanced using the AuNP-Protein A/G-antibody complex. This optimal antibody-antigen binding efficacy is thought to be the result of the large number of antibody per particle and the oriented binding of the antibody to the Protein A/G on the AuNP surface. These results highlight the ideal immuno-gold nanoparticle characteristics for the detection of target antigens such as cocaine. PMID:26994353

  1. Inhibition of MHC class I-restricted antigen presentation by gamma 2-herpesviruses.

    PubMed

    Stevenson, P G; Efstathiou, S; Doherty, P C; Lehner, P J

    2000-07-18

    The gamma-herpesviruses, in contrast to the alpha- and beta-herpesviruses, are not known to inhibit antigen presentation to CD8(+) cytotoxic T lymphocytes (CTLs) during lytic cycle replication. However, murine gamma-herpesvirus 68 causes a chronic lytic infection in CD4(+) T cell-deficient mice despite the persistence of a substantial CTL response, suggesting that CTL evasion occurs. Here we show that, distinct from host protein synthesis shutoff, gamma-herpesvirus 68 down-regulates surface MHC class I expression on lytically infected fibroblasts and inhibits their recognition by antigen-specific CTLs. The viral K3 gene, encoding a zinc-finger-containing protein, dramatically reduced the half-life of nascent class I molecules and the level of surface MHC class I expression and was by itself sufficient to block antigen presentation. The homologous K3 and K5 genes of the related Kaposi's sarcoma-associated virus also inhibited antigen presentation and decreased cell surface expression of HLA class I antigens. Thus it appears that an immune evasion strategy shared by at least two gamma-herpesviruses allows continued lytic infection in the face of strong CTL immunity. PMID:10890918

  2. Vaccinia Virus A35R Inhibits MHC Class II Antigen Presentation

    PubMed Central

    Rehm, Kristina E.; Connor, Ramsey F.; Jones, Gwendolyn J.B.; Yimbu, Kenneth; Roper, Rachel L.

    2009-01-01

    The Vaccinia virus gene A35R (Copenhagen designation) is highly conserved in mammalian-tropic poxviruses and is an important virulence factor, but its function was unknown. We show herein that A35 does not affect viral infectivity, apoptosis induction, or replication; however, we found that A35 significantly inhibited MHC class II-restricted antigen presentation, immune priming of T lymphocytes, and subsequent chemokine and cytokine synthesis. A35 localized to endosomes and reduced the amount of a model antigenic peptide displayed in the cleft of class II MHC. In addition, A35 decreased VV specific T cell responses in vivo. Thus, this is the first report identifying a function for the A35 protein in virulence as well as the first report identifying a VV gene that inhibits peptide antigen presentation. PMID:19954808

  3. Relationship between Fc receptors, antigen-binding sites on T and B cells, and H-2 complex-associated determinants.

    PubMed

    Basten, A; Miller, J F; Abraham, R

    1975-03-01

    The relationship between H-2 complex-associated determinants, Fc receptors, and specific antigen-recognition sites on T and B cells was examined by binding and functional assays. The Fc receptor was detected by radiolabeled immune complexes or aggregated human IgG. Both these reagents selectively bound to B cells, not to T cells. When spleen cells, from mice primed to several antigens, were exposed to highly substituted radioactive aggregates, their capacity to transfer both a direct and indirect plaque-forming cell response to these antigens was abrogated. Addition of B cells, but not of T cells, restored responsiveness. Complexed Ig binding to Fc receptors was prevented by pretreatment of mixed lymphoid cell populations with antisera directed against membrane components on the same cell (e.g., H-2) and on other cells (e.g., theta). The lack of specificity of inhibition was thought to be due to the formation on cell surfaces of antigen-antibody complexes which would then attach to the Fc receptor during the incubation precedure. Specific blockade of the Fc receptor during the incubation procedure. Specific blockade of the Fc receptor however occurred when B cells were pretreated with the Fab fragments of anti-H-2 antibody. This was demonstrated autoradiographically and by inhibition of aggregate-induced suicide. The blocking activity of ante-H-2 Fab was removed by absorption with spleen cells from thymectomized irradiated mice but not with thymus cells of appropriate specificity. This suggested that the antibodies involved had specificity for determinants on the B-cell membrane distinct from those coded by the K or D end of the H-2 complex, and either absent from, or poorly represented on, thymus cells. Specific antigen-induced suicide of B cells was achieved simply by incubating the cells with radioactive antigen in the cold. T-cell suicide on the other hand required that the 125I-labeled antigen be presented to the T cells at 37 degrees-C on the surface of

  4. Mapping Epitopes on a Protein Antigen by the Proteolysis of Antigen-Antibody Complexes

    NASA Astrophysics Data System (ADS)

    Jemmerson, Ronald; Paterson, Yvonne

    1986-05-01

    A monoclonal antibody bound to a protein antigen decreases the rate of proteolytic cleavage of the antigen, having the greatest effect on those regions involved in antibody contact. Thus, an epitope can be identified by the ability of the antibody to protect one region of the antigen more than others from proteolysis. By means of this approach, two distinct epitopes, both conformationally well-ordered, were characterized on horse cytochrome c.

  5. Novel Mycobacteria Antigen 85 Complex Binding Motif on Fibronectin*

    PubMed Central

    Kuo, Chih-Jung; Bell, Hannah; Hsieh, Ching-Lin; Ptak, Christopher P.; Chang, Yung-Fu

    2012-01-01

    The members of the antigen 85 protein family (Ag85), consisting of members Ag85A, Ag85B, and Ag85C, are the predominantly secreted proteins of mycobacteria and possess the ability to specifically interact with fibronectin (Fn). Because Fn-binding proteins are likely to be important virulence factors of Mycobacterium spp., Ag85 may contribute to the adherence, invasion, and dissemination of organisms in host tissue. In this study, we reported the Fn binding affinity of Ag85A, Ag85B, and Ag85C from Mycobacterium avium subsp. paratuberculosis (MAP) (KD values were determined from 33.6 to 68.4 nm) and mapped the Ag85-binding motifs of Fn. Fn14, a type III module located on the heparin-binding domain II (Hep-2) of Fn, was discovered to interact with Ag85 from MAP. The peptide inhibition assay subsequently demonstrated that a peptide consisting of residues 17–26 from Fn14 (17SLLVSWQPPR26, termed P17–26) could interfere with Ag85B binding to Fn (73.3% reduction). In addition, single alanine substitutions along the sequence of P17–26 revealed that the key residues involved in Ag85-Fn binding likely contribute through hydrophobic and charge interactions. Moreover, binding of Ag85 on Fn siRNA-transfected Caco2 cells was dramatically reduced (44.6%), implying the physiological significance of the Ag85-Fn interaction between mycobacteria and host cells during infection. Our results indicate that Ag85 binds to Fn at a novel motif and plays a critical role in mycobacteria adherence to host cells by initiating infection. Ag85 might serve as an important colonization factor potentially contributing to mycobacterial virulence. PMID:22128161

  6. Phospholipase treatment of accessory cells that have been exposed to antigen selectively inhibits antigen-specific Ia-restricted, but not allospecific, stimulation of T lymphocytes.

    PubMed Central

    Falo, L D; Benacerraf, B; Rock, K L

    1986-01-01

    The corecognition of antigen and class II major histocompatibility complex (MHC) molecules (Ia molecules) by the T-cell receptor is a cell surface event. Before antigen is recognized, it must be taken up, processed, and displayed on the surface of an Ia-bearing accessory cell (antigen-presenting cell, APC). The exact nature of antigen processing and the subsequent associations of antigen with the APC plasma membrane, Ia molecules, and/or the T-cell receptor are not well defined. To further analyze these events, we have characterized the processing and presentation of the soluble polypeptide antigen bovine insulin. We found that this antigen requires APC-dependent processing, as evidenced by the inability of metabolically inactivated APCs to present native antigen to antigen plus Ia-specific T-T hybridomas. The ability of the same APCs to present antigen after uptake and processing showed that this antigen subsequently becomes stably associated with the APC plasma membrane. To characterize the basis for this association, we analyzed its sensitivity to enzymatic digestion. APCs exposed to antigen, treated with phospholipase A2, and then immediately fixed lost the ability to stimulate bovine insulin plus I-Ad-specific hybridomas. In contrast, the ability of these same APCs to stimulate I-Ad allospecific hybridomas was unaffected. This effect of phospholipase is not mimicked by the broadly active protease Pronase, nor is there evidence for contaminating proteases in the phospholipase preparation. These results suggest that one consequence of antigen processing may be an antigen-lipid association that contributes to the anchoring of antigen to the APC membrane. The implications of this model are discussed. PMID:3529095

  7. Avian P1 antigens inhibit agglutination mediated by P fimbriae of uropathogenic Escherichia coli.

    PubMed Central

    Johnson, J R; Swanson, J L; Neill, M A

    1992-01-01

    Whole egg white from pigeon, dove, and cockatiel eggs, as well as the ovomucoid fraction of pigeon egg white, exhibited strong P1 antigenic activities and inhibited agglutination of human P1 erythrocytes and of digalactoside-coated latex beads by P-fimbriated Escherichia coli strains. In contrast, chicken egg white exhibited only weak P1 antigenic activity and had little impact on P-fimbrial agglutination. These preparations did not affect hemagglutination by E. coli strains expressing mannose-resistant adhesins other than P fimbriae, i.e., Dr, F1845, and S adhesins. Human anti-P1 serum diminished the P-fimbrial inhibitory activities of pigeon egg white and pigeon ovomucoid. Pigeon ovomucoid was equipotent on a molar basis with globoside, and the pigeon, dove, and cockatiel egg white preparations were equipotent with each other in P-fimbrial inhibition. Incubation of p erythrocytes in whole egg whites or in pigeon ovomucoid did not render them agglutinable by P-fimbriated bacteria, whereas incubation in globoside did. These data demonstrate that whole egg whites (and their ovomucoid fraction) from members of the families Columbidae (pigeons and doves) and Psittacidae (parrots) specifically and potently inhibit P-fimbrial agglutination, probably by providing P1 antigen as a receptor for the P-fimbrial adhesin. Avian egg white preparations may facilitate adhesin characterization of wild-type uropathogenic strains and may useful in preventing upper urinary tract infections due to P-fimbriated E. coli. PMID:1346125

  8. Human Antibodies to a Mr 155,000 Plasmodium falciparum Antigen Efficiently Inhibit Merozoite Invasion

    NASA Astrophysics Data System (ADS)

    Wahlin, Birgitta; Wahlgren, Mats; Perlmann, Hedvig; Berzins, Klavs; Bjorkman, Anders; Patarroyo, Manuel E.; Perlmann, Peter

    1984-12-01

    IgG from a donor clinically immune to Plasmodium falciparum malaria strongly inhibited reinvasion in vitro of human erythrocytes by the parasite. When added to monolayers of glutaraldehyde-fixed and air-dried erythrocytes infected with the parasite, this IgG also displayed a characteristic immunofluorescence restricted to the surface of infected erythrocytes. Elution of the IgG adsorbed to such monolayers gave an antibody fraction that was 40 times more efficient in the reinvasion inhibition assay (50% inhibition titer, <1 μ g/ml) than the original IgG preparation. The major antibody in this eluate was directed against a parasite-derived antigen of Mr 155,000 (Pf 155) deposited by the parasite in the erythrocyte membrane in the course of invasion. A detailed study of IgG fractions from 11 donors with acute P. falciparum malaria or clinical immunity revealed the existence of an excellent correlation between their capacities to stain the surface of infected erythrocytes, their titers in reinvasion inhibition, and the presence of antibodies to Pf 155 as detected by immunoblotting. No such correlations were seen when the IgG fractions were analyzed for immunofluorescence of intracellular parasites or for the presence of antibodies to other parasite antigens as detected by immunoprecipitation of [35S]methionine-labeled and NaDodSO4/PAGE-separated parasite extracts. The results suggest that Pf 155 has an important role in the process of erythrocyte infection and that host antibodies to this antigen may efficiently interfere with this process.

  9. Estradiol-induced vaginal mucus inhibits antigen penetration and CD8+ T cell priming in response to intravaginal immunization

    PubMed Central

    Seavey, Matthew M.; Mosmann, Tim R.

    2010-01-01

    Although vaginal immunization has been explored as a strategy to induce mucosal immunity in the female reproductive tract, this site displays unique immunological features that probably evolved to inhibit anti-paternal T cell responses after insemination to allow successful pregnancy. We previously demonstrated that estradiol, which induces an estrus-like state, prevented CD8+ T cell priming during intravaginal immunization of mice. We now show that estradiol prevented antigen loading of vaginal antigen presenting cells (APC) after intravaginal immunization. Histological examination confirmed that estradiol prevented penetration of peptide antigen into the vaginal wall. Removal of the estradiol-induced mucus barrier by mucinase partially restored antigen loading of vaginal APC and CD8+ T cell proliferation in vivo. The estradiol-induced mucus barrier may thus prevent exposure to antigens delivered intravaginally, supplementing additional estradiol-dependent mechanism(s) that inhibit CD8+ T cell priming after insemination or vaginal vaccination. PMID:19428849

  10. Chick myotendinous antigen. II. A novel extracellular glycoprotein complex consisting of large disulfide-linked subunits.

    PubMed

    Chiquet, M; Fambrough, D M

    1984-06-01

    This report describes the biochemical characterization of a novel extracellular matrix component, " myotendinous antigen," which appears early in chick limb morphogenesis at sites connecting developing muscle fibers, tendons, and bone ( Chiquet , M., and D. Fambrough , 1984; J. Cell Biol., 98:1926-1936). This extracellular matrix antigen is a major component of the secretory proteins released into the medium by fibroblast and muscle cultures; the soluble form is characterized here. This form of myotendinous antigen is a large glycoprotein complex consisting of several disulfide linked subunits (Mr approximately 150,000-240,000). The differently sized antigen subunits are related, since they yielded very similar proteolytic cleavage patterns. M1 antibody can bind to the denatured subunits. The antigen subunits, as well as a Mr approximately 80,000 pepsin-resistant antigenic domain derived from them, are resistant to bacterial collagenase. Despite possessing subunits similar in size to fibronectin, myotendinous antigen appears to be both structurally and antigenically unrelated to fibronectin or to other known extracellular matrix components. About seven times more M1 antigen per cell nucleus was released into the medium in fibroblast as compared to muscle cultures. In muscle conditioned medium, myotendinous antigen is noncovalently complexed to very high molecular weight material that could be heavily labeled by [3H]glucosamine and [35S]sulfate. This material is sensitive to chondroitinase ABC and hence appears to contain sulfated glycosaminoglycans. We speculate that myotendinous antigen might interact with proteoglycans on the surface of muscle fibers, thereby acting as a link to tendons. PMID:6202699

  11. Mutations which affect the inhibition of protein phosphatase 2A by simian virus 40 small-t antigen in vitro decrease viral transformation.

    PubMed Central

    Mungre, S; Enderle, K; Turk, B; Porrás, A; Wu, Y Q; Mumby, M C; Rundell, K

    1994-01-01

    Three independent point mutations within residues 97 to 103 of the simian virus 40-small-t antigen (small-t) greatly reduced the ability of purified small-t to inhibit protein phosphatase 2A in vitro. These mutations affected the interaction of small-t antigen with the protein phosphatase 2A A subunit translated in vitro, and a peptide from the region identified by these mutations released the A subunit from immune complexes. When introduced into virus, the mutations eliminated the ability of small-t to enhance viral transformation of growth-arrested rat F111 cells. In contrast, the mutant small-t antigens were unimpaired in the transactivation of the adenovirus E2 promoter, an activity which was reduced by a double mutation in small-t residues 43 and 45. Images PMID:8107228

  12. Application of 13C NMR spectroscopy to paratope mapping for larger antigen-Fab complexes.

    PubMed

    Kim, H; Kato, K; Yamato, S; Igarashi, T; Matsunaga, C; Ohtsuka, H; Higuchi, A; Nomura, N; Noguchi, H; Arata, Y

    1994-06-13

    For the purpose of engineering the antibody combining site, mapping residues that are involved in antigen binding provide us with valuable information. By use of 13C NMR spectroscopy with selectively 13C-labeled Fv fragments, we have established a general strategy to identify the residues that are perturbed upon binding of small antigen (hapten) molecules [(1990) Biochemistry 30, 6604-6610]. In the present paper, we demonstrate that this strategy can be extended to molecular structural analyses of the complexes of an Fab fragment and a larger antigen molecule such as Pseudomonas aeruginosa exotoxin A with a molecular mass of 67 kDa. PMID:8013642

  13. Structural investigation of the alpha-1-antichymotrypsin: prostate-specific antigen complex by comparative model building.

    PubMed Central

    Villoutreix, B. O.; Lilja, H.; Pettersson, K.; Lövgren, T.; Teleman, O.

    1996-01-01

    Prostate-specific antigen (PSA), produced by prostate cells, provides an excellent serum marker for prostate cancer. It belongs to the human kallikrein family of enzymes, a second prostate-derived member of which is human glandular kallikrein-1 (hK2). Active PSA and hK2 are both 237-residue kallikrein-like proteases, based on sequence homology. An hK2 model structure based on the serine protease fold is presented and compared to PSA and six other serine proteases in order to analyze in depth the role of the surface-accessible loops surrounding the active site. The results show that PSA and hK2 share extensive structural similarity and that most amino acid replacements are centered on the loops surrounding the active site. Furthermore, the electrostatic potential surfaces are very similar for PSA and hK2. PSA interacts with at least two serine protease inhibitors (serpins): alpha-1-antichymotrypsin (ACT) and protein C inhibitor (PCI). Three-dimensional model structures of the uncleaved ACT molecule were developed based upon the recent X-ray structure of uncleaved antithrombin. The serpin was docked both to PSA and hK2. Amino acid replacements and electrostatic complementarities indicate that the overall orientation of the proteins in these complexes is reasonable. In order to investigate PSA's heparin interaction sites, electrostatic computations were carried out on PSA, hK2, protein C, ACT, and PCI. Two heparin binding sites are suggested on the PSA surface and could explain the enhanced complex formation between PSA and PCI, while inhibiting the formation of the ACT-PSA complex, PSA, hK2, and their preliminary complexes with ACT should facilitate the understanding and prediction of structural and functional properties for these important proteins also with respect to prostate diseases. PMID:8732755

  14. A novel T cell receptor single-chain signaling complex mediates antigen-specific T cell activity and tumor control

    PubMed Central

    Stone, Jennifer D.; Harris, Daniel T.; Soto, Carolina M.; Chervin, Adam S.; Aggen, David H.; Roy, Edward J.; Kranz, David M.

    2014-01-01

    Adoptive transfer of genetically modified T cells to treat cancer has shown promise in several clinical trials. Two main strategies have been applied to redirect T cells against cancer: 1) introduction of a full-length T cell receptor (TCR) specific for a tumor-associated peptide-MHC, or 2) introduction of a chimeric antigen receptor (CAR), including an antibody fragment specific for a tumor cell surface antigen, linked intracellularly to T cell signaling domains. Each strategy has advantages and disadvantages for clinical applications. Here, we present data on the in vitro and in vivo effectiveness of a single-chain signaling receptor incorporating a TCR variable fragment as the targeting element (referred to as TCR-SCS). This receptor contained a single-chain TCR (Vβ-linker-Vα) from a high-affinity TCR called m33, linked to the intracellular signaling domains of CD28 and CD3ζ. This format avoided mispairing with endogenous TCR chains, and mediated specific T cell activity when expressed in either CD4 or CD8 T cells. TCR-SCS-transduced CD8-negative cells showed an intriguing sensitivity, compared to full-length TCRs, to higher densities of less stable pepMHC targets. T cells that expressed this peptide-specific receptor persisted in vivo, and exhibited polyfunctional responses. Growth of metastatic antigen-positive tumors was significantly inhibited by T cells that expressed this receptor, and tumor cells that escaped were antigen loss variants. TCR-SCS receptors represent an alternative targeting receptor strategy that combines the advantages of single-chain expression, avoidance of TCR chain mispairing, and targeting of intracellular antigens presented in complex with MHC proteins. PMID:25082071

  15. Cancer-testis antigen MAGE-C2 binds Rbx1 and inhibits ubiquitin ligase-mediated turnover of cyclin E

    PubMed Central

    Wang, Jingjing; Guo, Chengli; Li, Yan; Li, Bing; Zhang, Yu; Yin, Yanhui

    2015-01-01

    Cancer-testis antigen MAGE-C2 is normally expressed in testis but aberrantly expressed in various kinds of tumors. Its functions in tumor cells are mostly unknown. Here, we show that MAGE-C2 binds directly to the RING domain protein Rbx1, and participates in Skp1-Cullin1-F box protein (SCF) complex. Furthermore, MAGE-C2 can inhibit the E3 ubiquitin ligase activity of SCF complex. Ablation of endogenous MAGE-C2 decreases the level of cyclin E and accelerates cyclin E turnover by inhibiting ubiquitin-mediated proteasome degradation. Overexpression of MAGE-C2 increases the level of cyclin E and promotes G1-S transition and cell proliferation, and the results are further confirmed by knockdown of MAGE-C2. Overall, the study indicates that MAGE-C2 is involved in SCF complex and increases the stability of cyclin E in tumor cells. PMID:26540345

  16. Mitochondrial electron transfer chain complexes inhibition by different organochalcogens.

    PubMed

    Puntel, Robson L; Roos, Daniel H; Seeger, Rodrigo Lopes; Rocha, João B T

    2013-02-01

    Mitochondrial dysfunction plays a pivotal role in the cell toxicology and death decision. The aim of the present study was to investigate the effect of three organocompounds (ebselen [Ebs], diphenyl diselenide [(PhSe)(2)] and diphenyl ditelluride [(PhTe)(2)]) on mitochondrial complexes (I, II, I-III, II-III and IV) activity from rat liver and kidney to determine their potential role as molecular targets of organochalcogens. All studied organochalcogens caused a statistically significant inhibition of the mitochondrial complex I activity. Ebs and (PhTe)(2) caused a statistically significant inhibition of the mitochondrial complex II activity in both hepatic and renal membranes. Hepatic mitochondrial complex II activity was practically unchanged by (PhSe)(2), whereas it significantly inhibited renal complex II activity. Mitochondrial complex IV activity was practically unchanged by the organochalcogens. Furthermore, organochalcogens inhibited the mitochondrial respiration supported by complex I or complex II substrates. The inhibitory effect of Ebs, (PhSe)(2) and (PhTe)(2) on mitochondrial complex I was prevented by NADH, but it was not prevented by catalase (CAT) and/or superoxide dismutase (SOD). Additionally, the organochalcogens-induced inhibition of complex I and II was completely reversed by reduced glutathione (GSH). In conclusion, Ebs, (PhSe)(2) and (PhTe)(2) were more effective inhibitors of renal and hepatic mitochondrial complex I than complex II, whereas complexes III and IV were little modified by these compounds. Taking into account the presented results, we suggest that organochalcogen-induced mitochondrial complexes I and II inhibition can be mediated by their thiol oxidation activity, i.e., Ebs, (PhSe)(2) and (PhTe)(2) can oxidize critical thiol groups from mitochondrial complexes I and II. So, mitochondrial dysfunction can be considered an important factor in the toxicity of Ebs, (PhSe)(2) and (PhTe)(2). PMID:23103426

  17. Evaluation of the Secretor Status of ABO Blood Group Antigens in Saliva among Southern Rajasthan Population Using Absorption Inhibition Method

    PubMed Central

    Khajuria, Nidhi; Mamta; Ramesh, Gayathri

    2016-01-01

    Introduction The ABO blood group system was the significant element for forensic serological examination of blood and body fluids in the past before the wide adaptation of DNA typing. A significant proportion of individuals (80%) are secretors, meaning that antigens present in the blood are also found in other body fluids such as saliva. Absorption inhibition is one such method that works by reducing strength of an antiserum based on type and amount of antigen present in the stains. Aim To check the efficacy of identifying the blood group antigens in saliva and to know the secretor status using absorption inhibition method among southern Rajasthan population. Materials and Methods Blood and saliva samples were collected from 80 individuals comprising 20 individuals in each blood group. The absorption inhibition method was used to determine the blood group antigens in the saliva and then the results were correlated with the blood group of the collected blood sample. The compiled data was statistically analysed using chi-square test. Results Blood groups A & O revealed 100% secretor status for both males and females. While blood groups B and AB revealed 95% secretor status. Conclusion Secretor status evaluation of the ABO blood group antigen in saliva using absorption inhibition method can be a useful tool in forensic examination. PMID:27042574

  18. Antibodies against a Plasmodium falciparum antigen PfMSPDBL1 inhibit merozoite invasion into human erythrocytes.

    PubMed

    Sakamoto, Hirokazu; Takeo, Satoru; Maier, Alexander G; Sattabongkot, Jetsumon; Cowman, Alan F; Tsuboi, Takafumi

    2012-03-01

    One approach to develop a malaria blood-stage vaccine is to target proteins that play critical roles in the erythrocyte invasion of merozoites. The merozoite surface proteins (MSPs) and the erythrocyte-binding antigens (EBAs) are considered promising vaccine candidates, for they are known to play important roles in erythrocyte invasion and are exposed to host immune system. Here we focused on a Plasmodium falciparum antigen, PfMSPDBL1 (encoded by PF10_0348 gene) that is a member of the MSP3 family and has both Duffy binding-like (DBL) domain and secreted polymorphic antigen associated with merozoites (SPAM) domain. Therefore, we aimed to characterize PfMSPDBL1 as a vaccine candidate. Recombinant full-length protein (rFL) of PfMSPDBL1 was synthesized by a wheat germ cell-free system, and rabbit antiserum was raised against rFL. We show that rabbit anti-PfMSPDBL1 antibodies inhibited erythrocyte invasion of wild type parasites in vitro in a dose dependent manner, and the specificity of inhibitory activity was confirmed using PfMSPDBL1 knockout parasites. Pre-incubation of the anti-PfMSPDBL1 antibodies with the recombinant SPAM domain had no effect on the inhibitory activity suggesting that antibodies to this region were not involved. In addition, antibodies to rFL were elicited by P. falciparum infection in malaria endemic area, suggesting the PfMSLDBL1 is immunogenic to humans. Our results suggest that PfMSPDBL1 is a novel blood-stage malaria vaccine candidate. PMID:22248820

  19. mTOR inhibition improves antitumor effects of vaccination with antigen-encoding RNA.

    PubMed

    Diken, Mustafa; Kreiter, Sebastian; Vascotto, Fulvia; Selmi, Abderraouf; Attig, Sebastian; Diekmann, Jan; Huber, Christoph; Türeci, Özlem; Sahin, Ugur

    2013-12-01

    Vaccination with in vitro transcribed RNA encoding tumor antigens is an emerging approach in cancer immunotherapy. Attempting to further improve RNA vaccine efficacy, we have explored combining RNA with immunomodulators such as rapamycin. Rapamycin, the inhibitor of mTOR, was used originally for immunosuppression. Recent reports in mouse systems, however, suggest that mTOR inhibition may enhance the formation and differentiation of the memory CD8(+) T-cell pool. Because memory T-cell formation is critical to the outcome of vaccination approaches, we studied the impact of rapamycin on the in vivo primed RNA vaccine-induced immune response using the chicken ovalbumin-expressing B16 melanoma model in C57BL/6 mice. Our data show that treatment with rapamycin at the effector-to-memory transition phase skews the vaccine-induced immune response toward the formation of a quantitatively and qualitatively superior memory pool and results in a better recall response. Tumor-infiltrating immune cells from these mice display a favorable ratio of effector versus suppressor cell populations. Survival of mice treated with the combined regimen of RNA vaccination with rapamycin is significantly longer (91.5 days) than that in the control groups receiving only one of these compounds (32 and 46 days, respectively). Our findings indicate that rapamycin enhances therapeutic efficacy of antigen-specific CD8(+) T cells induced by RNA vaccination, and we propose further clinical exploration of rapamycin as a component of immunotherapeutic regimens. PMID:24778131

  20. Vaccinia virus infection induces dendritic cell maturation but inhibits antigen presentation by MHC class II

    PubMed Central

    Yao, Yongxue; Li, Ping; Singh, Pratibha; Thiele, Allison T.; Wilkes, David S.; Renukaradhya, Gourapura J.; Brutkiewicz, Randy R.; Travers, Jeffrey B.; Luker, Gary D.; Hong, Soon-Cheol; Blum, Janice S.; Chang, Cheong-Hee

    2007-01-01

    Vaccinia virus (VV) infection is known to inhibit dendritic cells (DC) functions in vitro. Paradoxically, VV is also highly immunogenic and thus has been used as a vaccine. In the present study, we investigated the effects of an in vivo VV infection on DC function by focusing on early innate immunity. Our data indicated that DC are activated upon in vivo VV infection of mice. Splenic DC from VV-infected mice expressed elevated levels of MHC class I and co-stimulatory molecules on their cell surface and exhibited the enhanced potential to produce cytokines upon LPS stimulation. DC from VV-infected mice also expressed a high level of interferon-β. However, a VV infection resulted in the down-regulation of MHC class II expression and the impairment of antigen presentation to CD4 T cells by DC. Thus, during the early stage of a VV infection, although DC are impaired in some of the critical antigen presentation functions, they can promote innate immune defenses against viral infection. PMID:17678637

  1. Rapid assessment of the antigenic integrity of tetrameric HLA complexes by human monoclonal HLA antibodies.

    PubMed

    Eijsink, Chantal; Kester, Michel G D; Franke, Marry E I; Franken, Kees L M C; Heemskerk, Mirjam H M; Claas, Frans H J; Mulder, Arend

    2006-08-31

    The ability of tetrameric major histocompatibility complex (MHC) class I-peptide complexes (tetramers) to detect antigen-specific T lymphocyte responses has yielded significant information about the generation of in vivo immunity in numerous antigenic systems. Here we present a novel method for rapid validation of tetrameric HLA molecules based on the presence of allodeterminants. Human monoclonal antibodies (mAbs) recognizing polymorphic determinants on HLA class I were immobilized on polystyrene microparticles and used to probe the structural integrity of tetrameric HLA class I molecules by flow cytometry. A total of 22 tetramers, based on HLA-A1, A2, A3, A24, B7 and B8 were reactive with their counterpart mAbs, thus confirming their antigenic integrity. A positive outcome of this mAb test ensures that tetrameric HLA class I can be used with greater confidence in subsequent functional assays. PMID:16973172

  2. HIV infection of monocytes inhibits the T-lymphocyte proliferative response to recall antigens, via production of eicosanoids.

    PubMed Central

    Foley, P; Kazazi, F; Biti, R; Sorrell, T C; Cunningham, A L

    1992-01-01

    Human monocytes infected in vitro with human immunodeficiency virus (HIV) soon after adherence to plastic substrate demonstrated a significantly decreased ability to restimulate autologous immune T-lymphocyte proliferation after exposure to soluble (tetanus toxoid) and particulate [herpes simplex virus (HSV)] antigen. Incubation with the cyclo-oxygenase inhibitor, indomethacin (2-5 microM), prevented inhibition of antigen-stimulated lymphocyte proliferation. The inhibitory activity was identified in ultrafiltrates containing the low molecular weight fraction (less than 3000 MW) of supernatants from HIV-infected monocyte cultures. This activity was significantly and markedly reduced in similar ultrafiltrates prepared from indomethacin-treated cultures. Increased concentrations of prostaglandin E2 (PGE2) were detected in ultrafiltrates from HIV-infected monocyte cultures compared with uninfected cultures and cultures preincubated with indomethacin. Ultrafiltrates were inhibitory when added during the presentation of antigen to T lymphocytes but not when removed from monocyte cultures prior to the addition of lymphocytes. In addition, ultrafiltrates inhibited antigen-stimulated lymphocyte proliferation and PHA-induced lymphocyte proliferation to the same extent. These data indicate that cyclo-oxygenase products of arachidonic acid, including PGE2, are produced in excess by HIV-infected monocytes and that PGE2 and perhaps other cyclo-oxygenase products are implicated in the inhibition of antigen-stimulated lymphocyte proliferation via a direct effect on T lymphocytes. PMID:1572689

  3. Diacylglycerol kinase ζ limits B cell antigen receptor-dependent activation of ERK signaling to inhibit early antibody responses.

    PubMed

    Wheeler, Matthew L; Dong, Matthew B; Brink, Robert; Zhong, Xiao-Ping; DeFranco, Anthony L

    2013-10-15

    Signaling downstream of the B cell antigen receptor (BCR) is tightly regulated to enable cells to gauge the strength and duration of antigen-receptor interactions and to respond appropriately. We investigated whether metabolism of the second messenger diacylglycerol (DAG) by members of the family of DAG kinases (DGKs) played a role in modulating the magnitude of signaling by DAG downstream of the BCR. In the absence of DGKζ, the threshold for BCR signaling, measured as activation of the Ras-extracellular signal-regulated kinase (ERK) pathway, was markedly reduced in mature follicular B cells, which resulted in enhanced responses to antigen in vitro and in vivo. Inhibition of DAG signaling by DGKζ limited the number of antibody-secreting cells that were generated early in response to T cell-independent type 2 antigens, as well as to T cell-dependent antigens. Furthermore, the effect of loss of DGKζ closely resembled the effect of increasing the affinity of the BCR for antigen during the T cell-dependent antibody response. These results suggest that the magnitude of DAG signaling is important for translating the affinity of the BCR for antigen into the amount of antibody produced during the early stages of an immune response. PMID:24129701

  4. Lysophosphatidic Acid (LPA) Receptor 5 Inhibits B Cell Antigen Receptor Signaling and Antibody Response1

    PubMed Central

    Shotts, Kristin; Donovan, Erin E.; Strauch, Pamela; Pujanauski, Lindsey M.; Victorino, Francisco; Al-Shami, Amin; Fujiwara, Yuko; Tigyi, Gabor; Oravecz, Tamas; Pelanda, Roberta; Torres, Raul M.

    2014-01-01

    Lysophospholipids have emerged as biologically important chemoattractants capable of directing lymphocyte development, trafficking and localization. Lysophosphatidic acid (LPA) is a major lysophospholipid found systemically and whose levels are elevated in certain pathological settings such as cancer and infections. Here, we demonstrate that BCR signal transduction by mature murine B cells is inhibited upon LPA engagement of the LPA5 (GPR92) receptor via a Gα12/13 – Arhgef1 pathway. The inhibition of BCR signaling by LPA5 manifests by impaired intracellular calcium store release and most likely by interfering with inositol 1,4,5-trisphosphate receptor activity. We further show that LPA5 also limits antigen-specific induction of CD69 and CD86 expression and that LPA5-deficient B cells display enhanced antibody responses. Thus, these data show that LPA5 negatively regulates BCR signaling, B cell activation and immune response. Our findings extend the influence of lysophospholipids on immune function and suggest that alterations in LPA levels likely influence adaptive humoral immunity. PMID:24890721

  5. Small molecule and peptide-mediated inhibition of Epstein-Barr virus nuclear antigen 1 dimerization

    SciTech Connect

    Kim, Sun Young; Song, Kyung-A; Kieff, Elliott; Kang, Myung-Soo

    2012-07-27

    Highlights: Black-Right-Pointing-Pointer Evidence that targeting EBNA1 dimer, an EBV onco-antigen, can be achievable. Black-Right-Pointing-Pointer A small molecule and a peptide as EBNA1 dimerization inhibitors identified. Black-Right-Pointing-Pointer Both inhibitors associated with EBNA1 and blocked EBNA1 DNA binding activity. Black-Right-Pointing-Pointer Also, prevented its dimerization, and repressed viral gene transcription. -- Abstract: Latent Epstein-Barr virus (EBV) infection is associated with human B cell lymphomas and certain carcinomas. EBV episome persistence, replication, and gene expression are dependent on EBV-encoded nuclear antigen 1 (EBNA1)'s DNA binding domain (DBD)/dimerization domain (DD)-mediated sequence-specific DNA binding activity. Homodimerization of EBNA1 is essential for EBNA1 DNA binding and transactivation. In this study, we characterized a novel small molecule EBNA1 inhibitor EiK1, screened from the previous high throughput screening (HTS). The EiK1 compound specifically inhibited the EBNA1-dependent, OriP-enhanced transcription, but not EBNA1-independent transcription. A Surface Plasmon Resonance Biacore assay revealed that EiK1 associates with EBNA1 amino acid 459-607 DBD/DD. Consistent with the SPR data, in vitro gel shift assays showed that EiK1 suppressed the activity of EBNA1 binding to the cognate familial repeats (FR) sequence, but not control RBP-J{kappa} binding to the J{kappa} site. Subsequently, a cross-linker-mediated in vitro multimerization assay and EBNA1 homodimerization-dependent yeast two-hybrid assay showed that EiK1 significantly inhibited EBNA1 dimerization. In an attempt to identify more highly specific peptide inhibitors, small peptides encompassing the EBNA1 DBD/DD were screened for inhibition of EBNA1 DBD-mediated DNA binding function. The small peptide P85, covering EBNA1 a.a. 560-574, significantly blocked EBNA1 DNA binding activity in vitro, prevented dimerization in vitro and in vivo, associated with

  6. Isoflurane Selectively Inhibits Distal Mitochondrial Complex I in Caenorhabditis Elegans

    PubMed Central

    Kayser, Ernst-Bernhard; Suthammarak, Wichit; Morgan, Phil G.; Sedensky, Margaret M.

    2011-01-01

    BACKGROUND Complex I of the electron transport chain (ETC) is a possible target of volatile anesthetics (VAs). Complex I enzymatic activities are inhibited by VAs, and dysfunction of complex I can lead to hypersensitivity to VAs in worms and in people. Mutant analysis in Caenorhabditis (C.) elegans suggests that VAs may specifically interfere with complex I function at the binding site for its substrate ubiquinone. We hypothesized that isoflurane inhibits electron transport by competing with ubiquinone for binding to complex I. METHODS Wildtype and mutant C. elegans were used to study the effects of isoflurane on isolated mitochondria. Enzymatic activities of the ETC were assayed and dose-response curves determined using established techniques. Two-dimensional native gels of mitochondrial proteins were performed after exposure of mitochondria to isoflurane. RESULTS Complex I is the most sensitive component of the ETC to isoflurane inhibition; however the proximal portion of complex I (the flavoprotein) is relatively insensitive to isoflurane. Isoflurane and quinone do not compete for a common binding site on complex I. The absolute rate of complex I enzymatic activity in vitro does not predict immobilization of the animal by isoflurane. Isoflurane had no measurable effect on stability of mitochondrial supercomplexes. Reduction of ubiquinone by complex I displayed positive cooperative kinetics not disrupted by isoflurane. CONCLUSIONS Isoflurane directly inhibits complex I at a site distal to the flavoprotein subcomplex. However, we have excluded our original hypothesis that isoflurane and ubiquinone compete for a common hydrophobic binding site on complex I. In addition, immobilization of the nematode by isoflurane is not due to limiting absolute amounts of complex I electron transport as measured in isolated mitochondria. PMID:21467554

  7. Complex Minigene Library Vaccination for Discovery of Pre-Erythrocytic Plasmodium T Cell Antigens

    PubMed Central

    Stone, Brad C.; Kas, Arnold; Billman, Zachary P.; Fuller, Deborah H.; Fuller, James T.; Shendure, Jay; Murphy, Sean C.

    2016-01-01

    Development of a subunit vaccine targeting liver-stage Plasmodium parasites requires the identification of antigens capable of inducing protective T cell responses. However, traditional methods of antigen identification are incapable of evaluating T cell responses against large numbers of proteins expressed by these parasites. This bottleneck has limited development of subunit vaccines against Plasmodium and other complex intracellular pathogens. To address this bottleneck, we are developing a synthetic minigene technology for multi-antigen DNA vaccines. In an initial test of this approach, pools of long (150 bp) antigen-encoding oligonucleotides were synthesized and recombined into vectors by ligation-independent cloning to produce two DNA minigene library vaccines. Each vaccine encoded peptides derived from 36 (vaccine 1) and 53 (vaccine 2) secreted or transmembrane pre-erythrocytic P. yoelii proteins. BALB/cj mice were vaccinated three times with a single vaccine by biolistic particle delivery (gene gun) and screened for interferon-γ-producing T cell responses by ELISPOT. Library vaccination induced responses against four novel antigens. Naïve mice exposed to radiation-attenuated sporozoites mounted a response against only one of the four novel targets (PyMDH, malate dehydrogenase). The response to PyMDH could not be recalled by additional homologous sporozoite immunizations but could be partially recalled by heterologous cross-species sporozoite exposure. Vaccination against the dominant PyMDH epitope by DNA priming and recombinant Listeria boosting did not protect against sporozoite challenge. Improvements in library design and delivery, combined with methods promoting an increase in screening sensitivity, may enable complex minigene screening to serve as a high-throughput system for discovery of novel T cell antigens. PMID:27070430

  8. Complex Minigene Library Vaccination for Discovery of Pre-Erythrocytic Plasmodium T Cell Antigens.

    PubMed

    Stone, Brad C; Kas, Arnold; Billman, Zachary P; Fuller, Deborah H; Fuller, James T; Shendure, Jay; Murphy, Sean C

    2016-01-01

    Development of a subunit vaccine targeting liver-stage Plasmodium parasites requires the identification of antigens capable of inducing protective T cell responses. However, traditional methods of antigen identification are incapable of evaluating T cell responses against large numbers of proteins expressed by these parasites. This bottleneck has limited development of subunit vaccines against Plasmodium and other complex intracellular pathogens. To address this bottleneck, we are developing a synthetic minigene technology for multi-antigen DNA vaccines. In an initial test of this approach, pools of long (150 bp) antigen-encoding oligonucleotides were synthesized and recombined into vectors by ligation-independent cloning to produce two DNA minigene library vaccines. Each vaccine encoded peptides derived from 36 (vaccine 1) and 53 (vaccine 2) secreted or transmembrane pre-erythrocytic P. yoelii proteins. BALB/cj mice were vaccinated three times with a single vaccine by biolistic particle delivery (gene gun) and screened for interferon-γ-producing T cell responses by ELISPOT. Library vaccination induced responses against four novel antigens. Naïve mice exposed to radiation-attenuated sporozoites mounted a response against only one of the four novel targets (PyMDH, malate dehydrogenase). The response to PyMDH could not be recalled by additional homologous sporozoite immunizations but could be partially recalled by heterologous cross-species sporozoite exposure. Vaccination against the dominant PyMDH epitope by DNA priming and recombinant Listeria boosting did not protect against sporozoite challenge. Improvements in library design and delivery, combined with methods promoting an increase in screening sensitivity, may enable complex minigene screening to serve as a high-throughput system for discovery of novel T cell antigens. PMID:27070430

  9. Immunization against hepatitis B virus by mucosal administration of antigen-antibody complexes.

    PubMed

    McCluskie, M J; Wen, Y M; Di, Q; Davis, H L

    1998-01-01

    Antigen-antibody complexes have been shown to enhance immune responses against several antigens given by parenteral immunization. Herein, we have evaluated the potential of administering such immunostimulatory complexes by a mucosal route. Hepatitis B surface antigen (HBsAg) complexed with antibodies against HBsAg (anti-HBs) (HBsAg/Ab) was administered to BALB/c mice by intranasal inhalation. HBsAg by itself did not induce immune responses, whereas with HBsAg/Ab complexes, both systemic and mucosal immune responses were observed and these could be modulated by adjuvants. With HBsAg/Ab (1 or 10 microg), anti-HBs antibodies induced were predominantly of the IgG1 isotype (Th2-like). In contrast, anti-HBs induced by HBsAg/Ab plus cholera toxin (CT) or oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs (CpG) (1 microg each) were predominantly IgG2a (Th1-like). Results from this study indicate that HBsAg/Ab complexes can induce strong humoral immune responses when delivered by a noninvasive route, whether used alone or in combination with other mucosal adjuvants. PMID:10189191

  10. Experimental studies on the inhibition effects of 1000 Chinese medicinal herbs on the surface antigen of hepatitis B virus.

    PubMed

    Zheng, M; Zheng, Y

    1992-09-01

    The reverse passive hemagglutination inhibition test was used in the screening of 1000 Chinese materia medica for inhibitors of hepatitis B virus surface antigen. The herbal drugs were commercially available and the surface antigen was from sera of hepatitis B patients. 127 effective drugs were obtained from the survey of which 28 were highly inhibitory (8:1), 35 were moderately effective (4:1), and 64 mildly effective (2:1). Further experiments with varying dosages of the drug, dosages of HBsAg and duration of contact showed 10 drugs to be of optimal effect. PMID:1453758

  11. Formation of DNA triple helices inhibits DNA unwinding by the SV40 large T-antigen helicase.

    PubMed Central

    Peleg, M; Kopel, V; Borowiec, J A; Manor, H

    1995-01-01

    Previous studies have indicated that d(TC)n.d(GA)n microsatellites may serve as arrest signals for mammalian DNA replication through the ability of such sequences to form DNA triple helices and thereby inhibit replication enzymes. To further test this hypothesis, we examined the ability of d(TC)i.d(GA)i.d(TC)i triplexes to inhibit DNA unwinding in vitro by a model eukaryotic DNA helicase, the SV40 large T-antigen. DNA substrates that were able to form triplexes, and non-triplex-forming control substrates, were tested. We found that the presence of DNA triplexes, as assayed by endonuclease S1 and osmium tetroxide footprinting, significantly inhibited DNA unwinding by T-antigen. Strong inhibition was observed not only at acidic pH values, in which the triplexes were most stable, but also at physiological pH values in the range 6.9-7.2. Little or no inhibition was detected at pH 8.7. Based on these results, and on previous studies of DNA polymerases, we suggest that DNA triplexes may form in vivo and cause replication arrest through a dual inhibition of duplex unwinding by DNA helicases and of nascent strand synthesis by DNA polymerases. DNA triplexes also have the potential to inhibit recombination and repair processes in which helicases and polymerases are involved. Images PMID:7753619

  12. Mycobacterial antigen 85 complex (Ag85) as a target for ficolins and mannose-binding lectin.

    PubMed

    Świerzko, Anna S; Bartłomiejczyk, Marcin A; Brzostek, Anna; Łukasiewicz, Jolanta; Michalski, Mateusz; Dziadek, Jarosław; Cedzyński, Maciej

    2016-06-01

    The pattern recognition molecules (PRMs) able to activate complement via the lectin pathway are suspected to be involved in the interaction between pathogenic Mycobacteria and the host immune response. Recently, we have found strong interactions between 25 and 35kDa mycobacterial cell fractions and mannose-binding lectin (MBL) and ficolins. Here we demonstrate that two biologically important mycobacterial structures, mannosylated lipoarabinomannan (ManLAM) and the antigen 85 (Ag85) complex, induce activation of the lectin pathway of complement. The strong interaction of recombinant MBL with purified ManLAM was confirmed, but no binding of recombinant ficolins (ficolin-1, -2, -3) with this structure was observed. Interestingly, all PRMs tested reacted with the mycobacterial antigen 85 (Ag85) complex. Based on the use of specific inhibitors (mannan for MBL, acetylated bovine serum albumin for ficolin-1 and -2, Hafnia alvei PCM 1200 lipopolysaccharide for ficolin-3), we concluded that carbohydrate-recognition (MBL) and fibrinogen-like domains (ficolins) were involved in these interactions. Our results indicate that the mycobacterial antigen 85 complex is a target for ficolins and MBL. Furthermore, those PRMs also bound to fibronectin and therefore might influence the Ag85 complex-dependent interaction of Mycobacterium with the extracellular matrix. PMID:27141819

  13. Concurrent feline immune-complex nephritis. Tubular antigen-positive and renal amyloidosis.

    PubMed

    Saegusa, S; Shimizu, F; Nagase, M; Kasegawa, A

    1979-08-01

    We describe tubular antigen-positive immune-complex nephritis in a case of feline renal amyloidosis. Amyloid deposition was observed in mesangial area, and thickening of capillary walls was shown in the majority of the glomeruli. This case was also characterized with typical fluorescent granular depositions of cat IgG and C3 along the glomerular capillary walls as seen in human membranous glomerulonephritis. The fluorescent pattern of tubular antigen was identical with that of IgG and C3. Electron micrograph showed the thickening and irregularity of glomerular basement membranes, fusion of foot processes, and deposits of electron-dense or sometimes translucent materials, mostly in the intramembranous location. The causal sequence of the coincidental deposition of amyloid and immune complexes is discussed. PMID:157110

  14. Recognition of Major Histocompatibility Complex Antigens on Cultured Human Biliary Epithelial Cells by Alloreactive Lymphocytes

    PubMed Central

    Saidman, Susan L.; Duquesnoy, Rene J.; Zeevi, Adriana; Fung, John J.; Starzl, Thomas E.; Demetris, A. Jake

    2010-01-01

    We have developed an in vitro system to study the interactions between biliary epithelium and lymphocytes using cultured human biliary epithelial cells. No class II antigens were detected by immunoperoxidase staining of the normal biliary epithelial cells, but alloactivated lymphocyte culture supernatants were able to induce class II expression. The activity of the supernatants was blocked with an anti-γ-interferon monoclonal antibody. In addition, recombinant human γ-interferon alone induced the expression of class II antigens and increased the intensity of class I staining of cultured biliary epithelial cells. Biliary epithelial cell–induced proliferation of alloreactive T lymphocytes demonstrated that the major histocompatibility complex molecules carry functional lymphocyte-activating determinants. The recognition of major histocompatibility complex determinants was confirmed by monoclonal antibody–blocking studies and by stimulation of an alloreactive T-cell clone. However, the biliary epithelial cells were much less potent stimulators than arterial endothelial cells tested in the same assay system. PMID:1704868

  15. Epstein-Barr Viral BNLF2a Protein Hijacks the Tail-anchored Protein Insertion Machinery to Block Antigen Processing by the Transport Complex TAP*

    PubMed Central

    Wycisk, Agnes I.; Lin, Jiacheng; Loch, Sandra; Hobohm, Kathleen; Funke, Jessica; Wieneke, Ralph; Koch, Joachim; Skach, William R.; Mayerhofer, Peter U.; Tampé, Robert

    2011-01-01

    Virus-infected cells are eliminated by cytotoxic T lymphocytes, which recognize viral epitopes displayed on major histocompatibility complex class I molecules at the cell surface. Herpesviruses have evolved sophisticated strategies to escape this immune surveillance. During the lytic phase of EBV infection, the viral factor BNLF2a interferes with antigen processing by preventing peptide loading of major histocompatibility complex class I molecules. Here we reveal details of the inhibition mechanism of this EBV protein. We demonstrate that BNLF2a acts as a tail-anchored protein, exploiting the mammalian Asna-1/WRB (Get3/Get1) machinery for posttranslational insertion into the endoplasmic reticulum membrane, where it subsequently blocks antigen translocation by the transporter associated with antigen processing (TAP). BNLF2a binds directly to the core TAP complex arresting the ATP-binding cassette transporter in a transport-incompetent conformation. The inhibition mechanism of EBV BNLF2a is distinct and mutually exclusive of other viral TAP inhibitors. PMID:21984826

  16. Crystallization and preliminary X-ray diffraction studies of antigen--antibody complexes.

    PubMed

    Chitarra-Guillon, V; Souchon, H; Boulot, G; Riottot, M M; Mariuzza, R; Tello, D; Poljak, R J

    1988-08-01

    Monoclonal antibodies of predefined specificity have been purified and crystallized as single components or complexed with their specific antigens. The intersegmental flexibility of antibody molecules has imposed the strategy of attempting to crystallize their Fab fragments separately. Intrasegmental mobility in Fabs has rarely been an obstacle to their crystallization. The immune system, however, provides a large functional and structural diversity of antibody molecules suitable for crystallization and X-ray diffraction studies. PMID:3147699

  17. Application of Fluorescent Monocytes for Probing Immune Complexes on Antigen Microarrays

    PubMed Central

    Szittner, Zoltán; Papp, Krisztián; Sándor, Noémi; Bajtay, Zsuzsa; Prechl, József

    2013-01-01

    Microarrayed antigens are used for identifying serum antibodies with given specificities and for generating binding profiles. Antibodies bind to these arrayed antigens forming immune complexes and are conventionally identified by secondary labelled antibodies.In the body immune complexes are identified by bone marrow derived phagocytic cells, such as monocytes. In our work we were looking into the possibility of replacing secondary antibodies with monocytoid cells for the generation of antibody profiles. Using the human monocytoid cell line U937, which expresses cell surface receptors for immune complex components, we show that cell adhesion is completely dependent on the interaction of IgG heavy chains and Fcγ receptors, and this recognition is susceptible to differences between heavy chain structures and their glycosylation. We also report data on a possible application of this system in autoimmune diagnostics.Compared to secondary antibodies, fluorescent monocytesas biosensors are superior in reflecting biological functions of microarray-bound antibodies and represent an easy and robust alternative for profiling interactions between serum proteins and antigens. PMID:24039758

  18. Nitric oxide (NO) inhibits antigen-stimulated increases in vasoconstriction and glycogenolysis in perfused livers derived from sensitized rats

    SciTech Connect

    Hines, K.L.; Bates, J.N.; Fisher, R.A. )

    1991-03-11

    Recent studies in the authors laboratory demonstrated that infusion of antigen into perfused livers from sensitized rats produces increases in hepatic portal pressure, increases in hepatic glucose output and decreases in hepatic oxygen consumption. In the present study, effects of NO on these hepatic responses to antigen challenge were investigated. Infusion of NO into perfused livers from sensitized rats attenuated ovalbumin induced increases in hepatic portal pressure and glucose output approximately 85% and 90%, respectively, and abolished ovalbumin-induced decreases in hepatic oxygen consumption. The duration of ovalbumin-stimulated increases in hepatic portal pressure was reduced nearly 90% by NO. Similarly, infusion of NO into perfused livers from sensitized rats inhibited increases in hepatic portal pressure and glucose output in response to platelet-activating factor (PAF) nearly 80 and 90%, respectively. In contrast, NO inhibited completely hepatic vasoconstriction in response to phenylephrine without altering glycogenolytic responses to this {alpha}-adrenergic agonist. These results provide evidence for regulatory effects of NO on hemodynamic and glycogenolytic responses to antigen in perfused livers from sensitized rats. These observations support previous findings which suggest that hepatic responses to sensitizing antigen may be mediated by PAF or other autacoid mediators which stimulate glycogenolysis in liver by indirect mechanisms involving hepatic vasoconstriction.

  19. Structure of the Malaria Antigen AMA1 in Complex with a Growth-Inhibitory Antibody

    PubMed Central

    Bai, Tao; Kim, Hanna; Anders, Robin F; Foley, Michael; Batchelor, Adrian H

    2007-01-01

    Identifying functionally critical regions of the malaria antigen AMA1 (apical membrane antigen 1) is necessary to understand the significance of the polymorphisms within this antigen for vaccine development. The crystal structure of AMA1 in complex with the Fab fragment of inhibitory monoclonal antibody 1F9 reveals that 1F9 binds to the AMA1 solvent-exposed hydrophobic trough, confirming its importance. 1F9 uses the heavy and light chain complementarity-determining regions (CDRs) to wrap around the polymorphic loops adjacent to the trough, but uses a ridge of framework residues to bind to the hydrophobic trough. The resulting 1F9-AMA1–combined buried surface of 2,470 Å2 is considerably larger than previously reported Fab–antigen interfaces. Mutations of polymorphic AMA1 residues within the 1F9 epitope disrupt 1F9 binding and dramatically reduce the binding of affinity-purified human antibodies. Moreover, 1F9 binding to AMA1 is competed by naturally acquired human antibodies, confirming that the 1F9 epitope is a frequent target of immunological attack. PMID:17907804

  20. Investigation of vesicle-capsular plague antigen complex formation by elastic laser radiation scattering

    NASA Astrophysics Data System (ADS)

    Guseva, N. P.; Maximova, Irina S.; Romanov, Sergey V.; Shubochkin, L. P.; Tatarintsev, Sergey N.

    1991-05-01

    Recently a great deal of attention has been given to the investigation artificial lipid liposomes, due to their application as "containers" for directed transport of biologically active compounds into particular cells, organs and tissues for prophylaxis and therapy of infectious diseases. The use of traditional methods of liposome investigation, such as sedimentation, electrophoresis and chromatography is impeded by low liposome resistivity to different deformations. In conjunction with this, optical methods of laser light scattering are promising as they allow nondisturbing, precise and quick investigations. This paper describes the investigation of vesicle systems prepared from egg lecithin of Serva Corporation and their complexes with the capsular antigen of the plague microbe. The capsular antigen Fl was obtained from EV plague microbe grown at 37° C on Huttinger agar. Fl was isolated by gel-filtration on ASA-22 followed by freeze drying of the preparation. Angular dependences of polarized radiation scattering were measured for several liposome suspension samples in a saline solution before and after the interaction with the plague microbe capsular antigen. The aim of the investigation was to analyze the nature of mutual antigen arrangement in a liposome and to develop methods for measuring its inclusion percentage.

  1. Engineering an intracellular pathway for major histocompatibility complex class II presentation of antigens.

    PubMed Central

    Wu, T C; Guarnieri, F G; Staveley-O'Carroll, K F; Viscidi, R P; Levitsky, H I; Hedrick, L; Cho, K R; August, J T; Pardoll, D M

    1995-01-01

    The presentation of antigenic peptides by major histocompatibility complex (MHC) class II molecules to CD4+ T cells is critical to the function of the immune system. In this study, we have utilized the sorting signal of the lysosomal-associated membrane protein LAMP-1 to target a model antigen, human papillomavirus 16 E7 (HPV-16 E7), into the endosomal and lysosomal compartments. The LAMP-1 sorting signal reroutes the antigen into the MHC class II processing pathway, resulting in enhanced presentation to CD4+ cells in vitro. In vivo immunization experiments in mice demonstrated that vaccinia containing the chimeric E7/LAMP-1 gene generated greater E7-specific lymphoproliferative activity, antibody titers, and cytotoxic T-lymphocyte activities than vaccinia containing the wild-type HPV-16 E7 gene. These results suggest that specific targeting of an antigen to the endosomal and lysosomal compartments enhances MHC class II presentation and vaccine potency. Images Fig. 2 Fig. 3 PMID:8524826

  2. Antigen targeting to dendritic cells combined with transient regulatory T cell inhibition results in long-term tumor regression

    PubMed Central

    Unger, Wendy WJ; Mayer, Christian T; Engels, Steef; Hesse, Christina; Perdicchio, Maurizio; Puttur, Franz; Streng-Ouwehand, Ingeborg; Litjens, Manja; Kalay, Hakan; Berod, Luciana; Sparwasser, Tim; van Kooyk, Yvette

    2014-01-01

    Therapeutic vaccinations against cancer are still largely ineffective. Major caveats are inefficient delivery of tumor antigens to dendritic cells (DCs) and excessive immune suppression by Foxp3+ regulatory T cells (Tregs), resulting in defective T cell priming and failure to induce tumor regression. To circumvent these problems we evaluated a novel combinatorial therapeutic strategy. We show that tumor antigen targeting to DC-SIGN in humanized hSIGN mice via glycans or specific antibodies induces superior T cell priming. Next, this targeted therapy was combined with transient Foxp3+ Treg depletion employing hSIGNxDEREG mice. While Treg depletion alone slightly delayed B16-OVA melanoma growth, only the combination therapy instigated long-term tumor regression in a substantial fraction of mice. This novel strategy resulted in optimal generation of antigen-specific activated CD8+ T cells which accumulated in regressing tumors. Notably, Treg depletion also allowed the local appearance of effector T cells specific for endogenous B16 antigens. This indicates that antitumor immune responses can be broadened by therapies aimed at controlling Tregs in tumor environments. Thus, transient inhibition of Treg-mediated immune suppression potentiates DC targeted antigen vaccination and tumor-specific immunity. PMID:26405564

  3. Immunostimulatory complexes containing Eimeria tenella antigens and low toxicity plant saponins induce antibody response and provide protection from challenge in broiler chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Immunostimulating complexes (ISCOMs) are unique multimolecular structures formed by encapsulating antigens, lipids and triterpene saponins and are one of the most successful antigen delivery systems for microbial antigens. In the current study, both the route of administration and the antigen conce...

  4. Stability of free and complexed human immunodeficiency virus type 1 antigen at 4 degrees C and at room temperature.

    PubMed Central

    Griffith, B P; Garner, R B; Chacko, T M

    1995-01-01

    Free and immune-complex-dissociated (ICD) human immunodeficiency virus type 1 (HIV-1) antigenemias in serum specimens stored at room temperature (RT) and 4 degrees C for 1 to 35 days were evaluated. At all time points examined, there was no significant loss in detectable levels of ICD HIV-1 antigen at either RT or 4 degrees C. Free HIV-1 antigen was not stable in serum samples stored at RT for more than 2 days but was stable in samples stored at 4 degrees C for up to 4 days. Loss of free antigen occurred more rapidly in samples with high antigen content at baseline. Use of the ICD antigen assay allowed accurate quantitation of antigen in samples stored at RT or 4 degrees C for as long as 1 month. PMID:7615753

  5. Pseudomonas aeruginosa Cif Protein Enhances the Ubiquitination and Proteasomal Degradation of the Transporter Associated with Antigen Processing (TAP) and Reduces Major Histocompatibility Complex (MHC) Class I Antigen Presentation*

    PubMed Central

    Bomberger, Jennifer M.; Ely, Kenneth H.; Bangia, Naveen; Ye, Siying; Green, Kathy A.; Green, William R.; Enelow, Richard I.; Stanton, Bruce A.

    2014-01-01

    Cif (PA2934), a bacterial virulence factor secreted in outer membrane vesicles by Pseudomonas aeruginosa, increases the ubiquitination and lysosomal degradation of some, but not all, plasma membrane ATP-binding cassette transporters (ABC), including the cystic fibrosis transmembrane conductance regulator and P-glycoprotein. The goal of this study was to determine whether Cif enhances the ubiquitination and degradation of the transporter associated with antigen processing (TAP1 and TAP2), members of the ABC transporter family that play an essential role in antigen presentation and intracellular pathogen clearance. Cif selectively increased the amount of ubiquitinated TAP1 and increased its degradation in the proteasome of human airway epithelial cells. This effect of Cif was mediated by reducing USP10 deubiquitinating activity, resulting in increased polyubiquitination and proteasomal degradation of TAP1. The reduction in TAP1 abundance decreased peptide antigen translocation into the endoplasmic reticulum, an effect that resulted in reduced antigen available to MHC class I molecules for presentation at the plasma membrane of airway epithelial cells and recognition by CD8+ T cells. Cif is the first bacterial factor identified that inhibits TAP function and MHC class I antigen presentation. PMID:24247241

  6. A novel inhibition ELISA for the detection and monitoring of Penicillium marneffei antigen in human serum.

    PubMed

    Prakit, K; Nosanchuk, J D; Pruksaphon, K; Vanittanakom, N; Youngchim, S

    2016-04-01

    The thermally dimorphic fungus Penicillium marneffei is a causative agent of penicilliosis marneffei, a disease considered to be an acquired immune deficiency syndrome (AIDS)-defining illness in Southeast Asia and southern China. We have developed an inhibition enzyme-linked immunosorbent assay (inh-ELISA) incorporating the yeast phase specific mannoprotein-binding monoclonal antibody 4D1 for the detection of P. marneffei infection. In our sample set, the test detected antigenemia in all 45 (100 %) patients with P. marneffei, with a mean antigen concentration of 4.32 μg/ml. No cross-reactivity in this assay was found using serum from 44 additional patients with other fungal infections, such as Aspergillus fumigatus, Cryptococcus neoformans, and Candida albicans, as well as 44 patients with bacterial infections, such as Mycobacterium tuberculosis and Streptococcus suis. Additionally, no reactivity occurred using serum from 31 human immunodeficiency virus (HIV)-infected patients without a history of fungal infections and 113 healthy controls residing in endemic areas. To investigate the potential of the inh-ELISA for disease monitoring, we followed the reduction in antigenemia in six patients who clinically responded to itraconazole and P. marneffei was no longer isolated from their blood or tissues. In contrast, we correlated increased concentrations of antigenemia in patients with relapsed P. marneffei infection with the progression of their clinical symptoms and the isolation of P. marneffei from their clinical specimens. In summary, the P. marneffei inh-ELISA is a promising new assay for the rapid diagnosis of P. marneffei, as well as a tool for evaluating clinical response and clearance of the fungus during treatment. PMID:26838686

  7. Lymphocyte Function-Associated Antigen-1-Dependent Inhibition of Corneal Wound Healing

    PubMed Central

    Li, Zhijie; Burns, Alan R.; Smith, C. Wayne

    2006-01-01

    Abrasion of murine corneal epithelium induces neutrophil emigration through limbal vessels into the avascular corneal stroma, peaking within 12 to 18 hours after wounding. A central corneal wound closes within 24 hours by epithelial cell migration and division, and during wound closure corneal epithelial cells express intercellular adhesion molecule (ICAM)-1 (CD54). We investigated the contributions of lymphocyte function-associated antigen (LFA)-1 (CD11a/CD18) and Mac-1 (CD11b/CD18) by analyzing wound closure in mice with targeted deletions of CD11a (CD11a−/−) or CD11b (CD11b−/−). In contrast to CD11a−/− mice, CD11b deficiency revealed a much greater delay in epithelial wound closure with >90% inhibition of epithelial cell division at a time when neutrophil accumulation in the cornea was approximately threefold higher than normal. Treating CD11b−/− mice with anti-CD11a monoclonal antibody at the time of epithelial abrasion resulted in significant reductions in neutrophils and significant increases in corneal epithelial cell division and migration. Treating CD11b−/− mice with anti-ICAM-1 significantly increased measures of healing but marginally reduced neutrophil influx. In conclusion, wound healing after corneal epithelial abrasion is disrupted by the absence of CD11b. The disruption is apparently linked to excessive neutrophil accumulation at a time when epithelial division is essential to wound repair, and neutrophils appear to be detrimental through processes involving LFA-1 and ICAM-1. PMID:17071583

  8. Cinacalcet inhibits neuroblastoma tumor growth and upregulates cancer-testis antigens

    PubMed Central

    Casalà, Carla; Briansó, Ferran; Castrejón, Nerea; Rodríguez, Eva; Suñol, Mariona; Carcaboso, Angel M.; Lavarino, Cinzia; Mora, Jaume; de Torres, Carmen

    2016-01-01

    The calcium–sensing receptor is a G protein-coupled receptor that exerts cell-type specific functions in numerous tissues and some cancers. We have previously reported that this receptor exhibits tumor suppressor properties in neuroblastoma. We have now assessed cinacalcet, an allosteric activator of the CaSR approved for clinical use, as targeted therapy for this developmental tumor using neuroblastoma cell lines and patient-derived xenografts (PDX) with different MYCN and TP53 status. In vitro, acute exposure to cinacalcet induced endoplasmic reticulum stress coupled to apoptosis via ATF4-CHOP-TRB3 in CaSR-positive, MYCN-amplified cells. Both phenotypes were partially abrogated by phospholipase C inhibitor U73122. Prolonged in vitro treatment also promoted dose- and time-dependent apoptosis in CaSR-positive, MYCN-amplified cells and, irrespective of MYCN status, differentiation in surviving cells. Cinacalcet significantly inhibited tumor growth in MYCN-amplified xenografts and reduced that of MYCN-non amplified PDX. Morphology assessment showed fibrosis in MYCN-amplified xenografts exposed to the drug. Microarrays analyses revealed up-regulation of cancer-testis antigens (CTAs) in cinacalcet-treated MYCN-amplified tumors. These were predominantly CTAs encoded by genes mapping on chromosome X, which are the most immunogenic. Other modulated genes upon prolonged exposure to cinacalcet were involved in differentiation, cell cycle exit, microenvironment remodeling and calcium signaling pathways. CTAs were up-regulated in PDX and in vitro models as well. Moreover, progressive increase of CaSR expression upon cinacalcet treatment was seen both in vitro and in vivo. In summary, cinacalcet reduces neuroblastoma tumor growth and up-regulates CTAs. This effect represents a therapeutic opportunity and provides surrogate circulating markers of neuroblastoma response to this treatment. PMID:26893368

  9. Trivalent Arsenic Inhibits the Functions of Chaperonin Complex

    PubMed Central

    Pan, Xuewen; Reissman, Stefanie; Douglas, Nick R.; Huang, Zhiwei; Yuan, Daniel S.; Wang, Xiaoling; McCaffery, J. Michael; Frydman, Judith; Boeke, Jef D.

    2010-01-01

    The exact molecular mechanisms by which the environmental pollutant arsenic works in biological systems are not completely understood. Using an unbiased chemogenomics approach in Saccharomyces cerevisiae, we found that mutants of the chaperonin complex TRiC and the functionally related prefoldin complex are all hypersensitive to arsenic compared to a wild-type strain. In contrast, mutants with impaired ribosome functions were highly arsenic resistant. These observations led us to hypothesize that arsenic might inhibit TRiC function, required for folding of actin, tubulin, and other proteins postsynthesis. Consistent with this hypothesis, we found that arsenic treatment distorted morphology of both actin and microtubule filaments. Moreover, arsenic impaired substrate folding by both bovine and archaeal TRiC complexes in vitro. These results together indicate that TRiC is a conserved target of arsenic inhibition in various biological systems. PMID:20660648

  10. Trivalent arsenic inhibits the functions of chaperonin complex.

    PubMed

    Pan, Xuewen; Reissman, Stefanie; Douglas, Nick R; Huang, Zhiwei; Yuan, Daniel S; Wang, Xiaoling; McCaffery, J Michael; Frydman, Judith; Boeke, Jef D

    2010-10-01

    The exact molecular mechanisms by which the environmental pollutant arsenic works in biological systems are not completely understood. Using an unbiased chemogenomics approach in Saccharomyces cerevisiae, we found that mutants of the chaperonin complex TRiC and the functionally related prefoldin complex are all hypersensitive to arsenic compared to a wild-type strain. In contrast, mutants with impaired ribosome functions were highly arsenic resistant. These observations led us to hypothesize that arsenic might inhibit TRiC function, required for folding of actin, tubulin, and other proteins postsynthesis. Consistent with this hypothesis, we found that arsenic treatment distorted morphology of both actin and microtubule filaments. Moreover, arsenic impaired substrate folding by both bovine and archaeal TRiC complexes in vitro. These results together indicate that TRiC is a conserved target of arsenic inhibition in various biological systems. PMID:20660648

  11. Mechanism of HIV-1 Tat induced inhibition of antigen-specific T cell responsiveness.

    PubMed

    Subramanyam, M; Gutheil, W G; Bachovchin, W W; Huber, B T

    1993-03-15

    HIV-1 Tat has been shown to have an inhibitory effect on the Ag-specific responsiveness of human peripheral T cells. We have previously demonstrated that this retroviral protein binds to and partially inhibits the enzymatic activity of dipeptidyl aminopeptidase type IV (DP IV), also known as CD26, which is expressed on a variety of mammalian tissue, including T lymphocytes. A number of studies have implicated a role for DP IV in the activation of T lymphocytes. By utilizing HIV-1 Tat, as well as ProboroPro, a potent and specific boronic acid analog inhibitor of DP IV, we show here that blocking DP IV partially inactivates Ag and anti-CD3-mediated T cell proliferation. Neither mitogen nor anti-CD2 mediated proliferation of T lymphocytes, however, is impaired by blocking DP IV. The target molecule for the inhibition induced by both compounds was confirmed by the finding that soluble DP IV neutralized the reduced Ag responsiveness. The Ag-specific inhibition could be overcome by the addition of exogenous IL-2, suggesting that blocking or inactivation of DP IV results in a state of anergy, probably by interfering with the delivery or amplification of a signal necessary for IL-2 production. This is further substantiated by the finding that costimulation of human PBMC via the CD28 molecule, which initiates a non-TCR-dependent signaling pathway, overcomes the reduced Ag responsiveness induced by Tat and ProboroPro. The fact that ProboroPro has no impact on stimulation of T cells with PMA and ionomycin implies that blocking DP IV is influencing events before the activation of protein kinase C and Ca2+ flux. These results suggest that DP IV is necessary for amplification of signals generated by the engagement of the TCR-CD3 complex by nominal Ag. PMID:8095514

  12. A Cronobacter turicensis O1 Antigen-Specific Monoclonal Antibody Inhibits Bacterial Motility and Entry into Epithelial Cells

    PubMed Central

    Lehner, Angelika; Dietrich, Richard; Kleinsteuber, Ina; Canals, Rocío; Zurfluh, Katrin; Weiner, Kerstin; Märtlbauer, Erwin

    2014-01-01

    Cronobacter turicensis is an opportunistic foodborne pathogen that can cause a rare but sometimes lethal infection in neonates. Little is known about the virulence mechanisms and intracellular lifestyle of this pathogen. In this study, we developed an IgG monoclonal antibody (MAb; MAb 2G4) that specifically recognizes the O1 antigen of C. turicensis cells. The antilipopolysaccharide antibody bound predominantly monovalently to the O antigen and reduced bacterial growth without causing cell agglutination. Furthermore, binding of the antibody to the O1 antigen of C. turicensis cells caused a significant reduction of the membrane potential which is required to energize flagellar rotation, accompanied by a decreased flagellum-based motility. These results indicate that binding of IgG to the O antigen of C. turicensis causes a direct antimicrobial effect. In addition, this feature of the antibody enabled new insight into the pathogenicity of C. turicensis. In a tissue culture infection model, pretreatment of C. turicensis with MAb 2G4 showed no difference in adhesion to human epithelial cells, whereas invasion of bacteria into Caco-2 cells was significantly inhibited. PMID:25534937

  13. Immunoglobulin-like Transcript 4 (ILT4) Inhibits Lipid Antigen Presentation through Direct CD1d Interaction1

    PubMed Central

    Li, Demin; Wang, Lili; Yu, Li; Freundt, Eric C.; Jin, Boquan; Screaton, Gavin R.; Xu, Xiao-Ning

    2008-01-01

    Natural killer T (NKT) cells recognize lipid antigens presented by CD1d molecules and play an important role in the regulation of innate and adaptive immune responses. Here we report the identification of a membrane-associated protein, immunoglobulin-like transcript 4 (ILT4), as a novel human CD1d receptor that inhibits CD1d-mediated immune responses. We found that native CD1d tetramer generated by mammalian cells was able to specifically bind human monocytes in the peripheral blood, and this binding was at least partly mediated by monocyte-expressed ILT4. The interaction between ILT4 and CD1d involves the two N-terminal domains of ILT4 and the antigen-binding groove of CD1d (α1/α2 domain). This interaction has been identified on the cell surface as well as in the endosomal and lysosomal compartments. Functional analysis showed that ILT4 could block the loading of lipid antigens such as α-GalCer, and consequently inhibited NKT recognition. The interaction between ILT4 and CD1d may provide new insights into the regulation of NKT-mediated immunity. PMID:19124746

  14. Induction of embryonic major histocompatibility complex antigen expression by gamma-IFN.

    PubMed

    Warner, C M; Almquist, C D; Toulimat, M H; Xu, Y

    1993-07-01

    Preimplantation mouse embryos were incubated in vitro with mouse recombinant gamma-interferon (IFN). The effect of the gamma-IFN on major histocompatibility complex (MHC) class I antigen expression was tested using an ELISA procedure. It was found that there is a doubling of Db antigens and a tripling of Qa-2 antigens on C57BL/6 mouse embryos cultured from the 8-cell stage for 24 h in the presence of 10(5) units/ml gamma-IFN. The effect of gamma-IFN on the rate of preimplantation embryonic development was tested by culturing 2-cell embryos for 48 h and 8-cell embryos for 24 h in the presence of varying concentrations of gamma-IFN up to 10(6) units/ml. Two methods were used to assess the cell number per embryo after the culture period: incorporation of [3H]thymidine into DNA, and direct counting of nuclei in fixed and stained embryos. Both methods showed that treatment with gamma-IFN increases the rate of development of preimplantation mouse embryos. Since rate of preimplantation embryonic development is genetically controlled by the Ped gene, it is suggested that gamma-IFN has a direct effect on the Ped gene phenotype of preimplantation mouse embryos. PMID:8229991

  15. Expression of major histocompatibility complex class II antigens in porcine leptospiral nephritis.

    PubMed

    Radaelli, E; Del Piero, F; Aresu, L; Sciarrone, F; Vicari, N; Mattiello, S; Tagliabue, S; Fabbi, M; Scanziani, E

    2009-09-01

    Class II major histocompatibility complex (MHCII) is required for the presentation of antigens to CD4 helper T cells. During nephritis, not only primary antigen presenting cells such as histiocytes and lymphocytes, but also cytokine-stimulated tubular epithelial cells express MHCII. Leptospirosis in fattening pigs is characterized by several degrees of nephritis, from absence of lesions to severe multifocal tubulo-interstitial inflammation. Renal tissue from 20 8-month-old pigs with spontaneous nephritis and 6 control pigs without renal lesions were investigated for leptospirosis by indirect immunohistochemistry (IHC) and polymerase chain reaction (PCR). IHC for MHCII also was performed on renal samples. Serum samples were tested for different serovars of Leptospira interrogans. Control pigs were free of interstitial nephritis and negative for leptospirosis by all tests. In pigs with nephritis, serology was positive for serovar Pomona in 19/20 pigs. In 16 of these 19 pigs, leptospiral renal infection was confirmed by PCR and/or indirect IHC. Nephritic lesions were classified histologically into perivascular lymphocytic (4 pigs), lymphofollicular (6 pigs), lymphohistiocytic (8 pigs), and neutrophilic (2 pigs) pattern. MHCII expression by histiocytes and lymphocytes was observed in all lesions. Prominent MHCII expression in regenerating tubular epithelium was observed in lymphofollicular and lymphohistiocytic nephritis. No tubular colocalization between leptospiral and MHCII antigen was observed. Results suggest that during leptospiral nephritis, MHCII contributes to the intensity of the inflammatory response. Furthermore de novo MHCII expression in regenerating tubules may play a role in the defence mechanism against leptospiral tubular colonization. PMID:19179617

  16. Parasite Manipulation of the Invariant Chain and the Peptide Editor H2-DM Affects Major Histocompatibility Complex Class II Antigen Presentation during Toxoplasma gondii Infection

    PubMed Central

    Leroux, Louis-Philippe; Nishi, Manami; El-Hage, Sandy; Fox, Barbara A.; Bzik, David J.

    2015-01-01

    Toxoplasma gondii is an obligate intracellular protozoan parasite. This apicomplexan is the causative agent of toxoplasmosis, a leading cause of central nervous system disease in AIDS. It has long been known that T. gondii interferes with major histocompatibility complex class II (MHC-II) antigen presentation to attenuate CD4+ T cell responses and establish persisting infections. Transcriptional downregulation of MHC-II genes by T. gondii was previously established, but the precise mechanisms inhibiting MHC-II function are currently unknown. Here, we show that, in addition to transcriptional regulation of MHC-II, the parasite modulates the expression of key components of the MHC-II antigen presentation pathway, namely, the MHC-II-associated invariant chain (Ii or CD74) and the peptide editor H2-DM, in professional antigen-presenting cells (pAPCs). Genetic deletion of CD74 restored the ability of infected dendritic cells to present a parasite antigen in the context of MHC-II in vitro. CD74 mRNA and protein levels were, surprisingly, elevated in infected cells, whereas MHC-II and H2-DM expression was inhibited. CD74 accumulated mainly in the endoplasmic reticulum (ER), and this phenotype required live parasites, but not active replication. Finally, we compared the impacts of genetic deletion of CD74 and H2-DM genes on parasite dissemination toward lymphoid organs in mice, as well as activation of CD4+ T cells and interferon gamma (IFN-γ) levels during acute infection. Cyst burdens and survival during the chronic phase of infection were also evaluated in wild-type and knockout mice. These results highlight the fact that the infection is influenced by multiple levels of parasite manipulation of the MHC-II antigen presentation pathway. PMID:26195549

  17. Parasite Manipulation of the Invariant Chain and the Peptide Editor H2-DM Affects Major Histocompatibility Complex Class II Antigen Presentation during Toxoplasma gondii Infection.

    PubMed

    Leroux, Louis-Philippe; Nishi, Manami; El-Hage, Sandy; Fox, Barbara A; Bzik, David J; Dzierszinski, Florence S

    2015-10-01

    Toxoplasma gondii is an obligate intracellular protozoan parasite. This apicomplexan is the causative agent of toxoplasmosis, a leading cause of central nervous system disease in AIDS. It has long been known that T. gondii interferes with major histocompatibility complex class II (MHC-II) antigen presentation to attenuate CD4(+) T cell responses and establish persisting infections. Transcriptional downregulation of MHC-II genes by T. gondii was previously established, but the precise mechanisms inhibiting MHC-II function are currently unknown. Here, we show that, in addition to transcriptional regulation of MHC-II, the parasite modulates the expression of key components of the MHC-II antigen presentation pathway, namely, the MHC-II-associated invariant chain (Ii or CD74) and the peptide editor H2-DM, in professional antigen-presenting cells (pAPCs). Genetic deletion of CD74 restored the ability of infected dendritic cells to present a parasite antigen in the context of MHC-II in vitro. CD74 mRNA and protein levels were, surprisingly, elevated in infected cells, whereas MHC-II and H2-DM expression was inhibited. CD74 accumulated mainly in the endoplasmic reticulum (ER), and this phenotype required live parasites, but not active replication. Finally, we compared the impacts of genetic deletion of CD74 and H2-DM genes on parasite dissemination toward lymphoid organs in mice, as well as activation of CD4(+) T cells and interferon gamma (IFN-γ) levels during acute infection. Cyst burdens and survival during the chronic phase of infection were also evaluated in wild-type and knockout mice. These results highlight the fact that the infection is influenced by multiple levels of parasite manipulation of the MHC-II antigen presentation pathway. PMID:26195549

  18. Analysis of tuberculous meningitis cases by an immunoblotting assay based on a mycobacterial antigen complex.

    PubMed Central

    Zou, Y L; Van Antwerpen, M P; Shi, G Q; Chen, Q X; Sindic, C J; Cocito, C

    1994-01-01

    Tuberculous meningitis cases were analyzed by an immunoblotting test based on Mycobacterium bovis BCG antigen complex A60. Anti-A60 immunoglobulin G (IgG) in cerebrospinal fluid (CSF) allowed early diagnosis, and concentrations decreased after recovery. In primary meningitis forms, anti-A60 IgGs were intrathecally synthesized and specific oligoclonal IgGs were present in CSF. In meningeal complications of pulmonary tuberculosis, there were matching titers of anti-A60 IgG in blood and CSF (mirror pattern). Correlation between CSF-restricted patterns and CSF pleocytosis was shown. Images PMID:7496976

  19. T-cell recognition of a cross-reactive antigen(s) in erythrocyte stages of Plasmodium falciparum and Plasmodium yoelii: inhibition of parasitemia by this antigen(s).

    PubMed Central

    Lucas, B; Engels, A; Camus, D; Haque, A

    1993-01-01

    In the current study, we investigated the presence of a cross-reactive antigen(s) in the erythrocyte stage from Plasmodium yoelii (265 BY strain) and Plasmodium falciparum through recognition by T cells primed in vivo with antigens from each of these parasites. BALB/c mice are naturally resistant to P. falciparum but are susceptible to P. yoelii infection. Mice that had recovered from P. yoelii primary infection became resistant to a second infection. A higher in vitro proliferative response to a soluble blood stage preparation of P. falciparum was observed in splenic cells from immune animals than in those from mice with a patent P. yoelii infection. The antigen-induced proliferative response was enhanced when animals were exposed to a secondary infection. Animals exposed to a challenge infection were treated with anti-CD4 or anti-CD8 monoclonal antibodies to deplete the corresponding subset of T cells. There was a marked diminution in P. falciparum antigen-induced proliferative response in the total splenic cell populations from CD8-depleted but not from CD4-depleted mice. In CD8-depleted and nondepleted animals, the antigen-induced proliferation in the total cell populations was markedly lower than in the T-cell-rich populations, indicating inhibitory activities of B cells and/or macrophages. There was no such difference in the stimulation between total and T-enriched cell populations from CD4-depleted animals. Flow cytometry analysis demonstrated the presence of an almost equal percentage of CD8+ (59.6%) and CD4+ (64%) T cells in the spleen preparations following in vivo depletion of CD4- and CD8-bearing T cells, respectively. When cultured with P. yoelii blood stage antigen, splenocytes from animals immunized with P. falciparum antigen displayed a significant proliferative response which was markedly diminished by treatment with anti-Thy-1.2 antibody plus complement. Animals immunized with P. falciparum antigen and then challenged with P. yoelii blood stage

  20. Hepatitis delta virus antigen forms dimers and multimeric complexes in vivo.

    PubMed Central

    Wang, J G; Lemon, S M

    1993-01-01

    Although the hepatitis delta virus genome contains multiple open reading frames, only one of these reading frames is known to be expressed during replication of the virus. This open reading frame encodes two distinct molecular species of hepatitis delta antigen (HDAg), p24 delta and p27 delta, depending on the location of the stop codon which terminates translation. We found antibody specific for p27 delta to be capable of precipitating p24 delta in extracts of infected liver, indicating that p27 delta and p24 delta form heterologous complexes in vivo. After cross-linking with 0.05% glutaraldehyde, specific HDAg dimers were detected in antigen prepared from both the liver and serum of an HDV-infected woodchuck carrier of woodchuck hepatitis virus. Guanidine HCl-denatured HDAg extracted from liver and dialyzed against phosphate-buffered saline sedimented in rate-zonal sucrose density gradients as 15S multimeric complexes. These 15S multimers were stable in the presence of 1.2% Nonidet P-40. After RNase digestion, the 15S complex was reduced to a 12S complex without associated RNA, while boiling for 3 min in 1% sodium dodecyl sulfate-0.5% 2-mercaptoethanol further reduced the 15S complex to 3S HDAg monomers. In the absence of glutaraldehyde cross-linking, HDAg extracted from liver migrated as monomer species in reducing and nonreducing gels, suggesting that the conserved cysteine residue present in p27 delta does not play a role in the formation of either dimers or multimers. On the other hand, an amino-terminal chymotrypsin-digested HDAg fragment, with a predicted length of 81 or less amino acids, retained the ability to form dimers, consistent with the hypothesis that a coiled-coil motif present between residues 27 and 58 may play a role in HDAg protein interactions in vivo. Images PMID:7677957

  1. The preferentially expressed antigen in melanoma (PRAME) inhibits myeloid differentiation in normal hematopoietic and leukemic progenitor cells

    PubMed Central

    Guthrie, Katherine A.; Cummings, Carrie L.; Sabo, Kathleen; Wood, Brent L.; Gooley, Ted; Yang, Taimei; Epping, Mirjam T.; Shou, Yaping; Pogosova-Agadjanyan, Era; Ladne, Paula; Stirewalt, Derek L.; Abkowitz, Janis L.; Radich, Jerald P.

    2009-01-01

    The preferentially expressed antigen in melanoma (PRAME) is expressed in several hematologic malignancies, but either is not expressed or is expressed at only low levels in normal hematopoietic cells, making it a target for cancer therapy. PRAME is a tumor-associated antigen and has been described as a corepressor of retinoic acid signaling in solid tumor cells, but its function in hematopoietic cells is unknown. PRAME mRNA expression increased with chronic myeloid leukemia (CML) disease progression and its detection in late chronic-phase CML patients before tyrosine kinase inhibitor therapy was associated with poorer therapeutic responses and ABL tyrosine kinase domain point mutations. In leukemia cell lines, PRAME protein expression inhibited granulocytic differentiation only in cell lines that differentiate along this lineage after all-trans retinoic acid (ATRA) exposure. Forced PRAME expression in normal hematopoietic progenitors, however, inhibited myeloid differentiation both in the presence and absence of ATRA, and this phenotype was reversed when PRAME was silenced in primary CML progenitors. These observations suggest that PRAME inhibits myeloid differentiation in certain myeloid leukemias, and that its function in these cells is lineage and phenotype dependent. Lastly, these observations suggest that PRAME is a target for both prognostic and therapeutic applications. PMID:19625708

  2. Dissecting the genetic complexity of the association between human leukocyte antigens and rheumatoid arthritis.

    PubMed

    Jawaheer, Damini; Li, Wentian; Graham, Robert R; Chen, Wei; Damle, Aarti; Xiao, Xiangli; Monteiro, Joanita; Khalili, Houman; Lee, Annette; Lundsten, Robert; Begovich, Ann; Bugawan, Teodorica; Erlich, Henry; Elder, James T; Criswell, Lindsey A; Seldin, Michael F; Amos, Christopher I; Behrens, Timothy W; Gregersen, Peter K

    2002-09-01

    Rheumatoid arthritis (RA) is an inflammatory disease with a complex genetic component. An association between RA and the human leukocyte antigen (HLA) complex has long been observed in many different populations, and most studies have focused on a direct role for the HLA-DRB1 "shared epitope" in disease susceptibility. We have performed an extensive haplotype analysis, using 54 markers distributed across the entire HLA complex, in a set of 469 multicase families with RA. The results show that, in addition to associations with the DRB1 alleles, at least two additional genetic effects are present within the major histocompatibility complex. One of these lies within a 497-kb region in the central portion of the HLA complex, an interval that excludes DRB1. This genetic risk factor is present on a segment of a highly conserved ancestral A1-B8-DRB1*03 (8.1) haplotype. Additional risk genes may also be present in the HLA class I region in a subset of DRB1*0404 haplotypes. These data emphasize the importance of defining haplotypes when trying to understand the HLA associations with disease, and they clearly demonstrate that such associations with RA are complex and cannot be completely explained by the DRB1 locus. PMID:12181776

  3. Dissecting the Genetic Complexity of the Association between Human Leukocyte Antigens and Rheumatoid Arthritis

    PubMed Central

    Jawaheer, Damini; Li, Wentian; Graham, Robert R.; Chen, Wei; Damle, Aarti; Xiao, Xiangli; Monteiro, Joanita; Khalili, Houman; Lee, Annette; Lundsten, Robert; Begovich, Ann; Bugawan, Teodorica; Erlich, Henry; Elder, James T.; Criswell, Lindsey A.; Seldin, Michael F.; Amos, Christopher I.; Behrens, Timothy W.; Gregersen, Peter K.

    2002-01-01

    Rheumatoid arthritis (RA) is an inflammatory disease with a complex genetic component. An association between RA and the human leukocyte antigen (HLA) complex has long been observed in many different populations, and most studies have focused on a direct role for the HLA-DRB1 “shared epitope” in disease susceptibility. We have performed an extensive haplotype analysis, using 54 markers distributed across the entire HLA complex, in a set of 469 multicase families with RA. The results show that, in addition to associations with the DRB1 alleles, at least two additional genetic effects are present within the major histocompatibility complex. One of these lies within a 497-kb region in the central portion of the HLA complex, an interval that excludes DRB1. This genetic risk factor is present on a segment of a highly conserved ancestral A1-B8-DRB1*03 (8.1) haplotype. Additional risk genes may also be present in the HLA class I region in a subset of DRB1*0404 haplotypes. These data emphasize the importance of defining haplotypes when trying to understand the HLA associations with disease, and they clearly demonstrate that such associations with RA are complex and cannot be completely explained by the DRB1 locus. PMID:12181776

  4. Sialic acid-modified antigens impose tolerance via inhibition of T-cell proliferation and de novo induction of regulatory T cells.

    PubMed

    Perdicchio, Maurizio; Ilarregui, Juan M; Verstege, Marleen I; Cornelissen, Lenneke A M; Schetters, Sjoerd T T; Engels, Steef; Ambrosini, Martino; Kalay, Hakan; Veninga, Henrike; den Haan, Joke M M; van Berkel, Lisette A; Samsom, Janneke N; Crocker, Paul R; Sparwasser, Tim; Berod, Luciana; Garcia-Vallejo, Juan J; van Kooyk, Yvette; Unger, Wendy W J

    2016-03-22

    Sialic acids are negatively charged nine-carbon carboxylated monosaccharides that often cap glycans on glycosylated proteins and lipids. Because of their strategic location at the cell surface, sialic acids contribute to interactions that are critical for immune homeostasis via interactions with sialic acid-binding Ig-type lectins (siglecs). In particular, these interactions may be of importance in cases where sialic acids may be overexpressed, such as on certain pathogens and tumors. We now demonstrate that modification of antigens with sialic acids (Sia-antigens) regulates the generation of antigen-specific regulatory T (Treg) cells via dendritic cells (DCs). Additionally, DCs that take up Sia-antigen prevent formation of effector CD4(+) and CD8(+)T cells. Importantly, the regulatory properties endowed on DCs upon Sia-antigen uptake are antigen-specific: only T cells responsive to the sialylated antigen become tolerized. In vivo, injection of Sia-antigen-loaded DCs increased de novo Treg-cell numbers and dampened effector T-cell expansion and IFN-γ production. The dual tolerogenic features that Sia-antigen imposed on DCs are Siglec-E-mediated and maintained under inflammatory conditions. Moreover, loading DCs with Sia-antigens not only inhibited the function of in vitro-established Th1 and Th17 effector T cells but also significantly dampened ex vivo myelin-reactive T cells, present in the circulation of mice with experimental autoimmune encephalomyelitis. These data indicate that sialic acid-modified antigens instruct DCs in an antigen-specific tolerogenic programming, enhancing Treg cells and reducing the generation and propagation of inflammatory T cells. Our data suggest that sialylation of antigens provides an attractive way to induce antigen-specific immune tolerance. PMID:26941238

  5. Inhibition of respiratory complex I by copper(ii)-bis(thiosemicarbazonato) complexes.

    PubMed

    Djoko, Karrera Y; Donnelly, Paul S; McEwan, Alastair G

    2014-12-01

    Several copper(ii) complexes of bis(thiosemicarbazones) [Cu(btsc)s] show promise as therapeutics for the treatment of neurological diseases, cancers and bacterial infections. These complexes are thought to act primarily as copper ionophores or "copper boosting" agents, whereby the Cu(II) centre is reduced by cytosolic reductants and Cu(I) is released as "free" or "bioavailable" ion. It is then assumed that the dissociated Cu(I) ion is the species responsible for many of the observed biological effects of Cu(btsc)s. We recently showed that Cu(btsc) complexes inhibited NADH dehydrogenases in the bacterial respiratory chain. In this work, we demonstrate that Cu(btsc) complexes also inhibit mitochondrial respiration and that Complex I in the mitochondrial electron transport chain is a specific target of inhibition. However, bioavailable Cu ions do not appear to contribute to the action of Cu(btsc) as a respiratory inhibitor. Instead, an intact Cu(btsc) molecule may bind reversibly and competitively to the site of ubiquinone binding in Complex I. Our results add to the growing body of evidence that the intact complex may be important in the overall cellular activity of Cu(btsc) complexes and further the understanding of their biological effects as a potential therapeutic. PMID:25366244

  6. [The differentiation of the antigens making up the circulating immune complexes].

    PubMed

    Gorina, L G; Vul'fovich, Iu V

    1996-01-01

    A simple method for the detection and analysis of circulating immune complexes (CIC) in specimens of biological fluids is proposed. The method was approved in the examination of patients with chronic infections caused by mycoplasmas and Streptococcus pyogenes L-forms. The method made it possible to diagnose infectious diseases accompanied by the formation of immune complexes and to study the dynamics of the processes of the accumulation and elimination of CIC in the course of the disease. Thus, the detection rate of specific antigens (Ag) incorporated into CIC in patients with mycoplasmal pneumonia exceeded 90 %. In children aged up to 1 year this rate decreased to 40 %. The diagnostic value of the determination of specific Ag incorporated into CIC was shown in streptococcal infections caused by S.pyogenes L-forms, viz. in frequently relapsing erysipelas, as well as in subacute rheumatism and in infectious allergic myocarditis. PMID:8820681

  7. Inhibition of selective signaling events in natural killer cells recognizing major histocompatibility complex class I.

    PubMed Central

    Kaufman, D S; Schoon, R A; Robertson, M J; Leibson, P J

    1995-01-01

    Many studies have characterized the transmembrane signaling events initiated after T-cell antigen receptor recognition of major histocompatibility complex (MHC)-bound peptides. Yet, little is known about signal transduction from a set of MHC class I recognizing receptors on natural killer (NK) cells whose ligation dramatically inhibits NK cell-mediated killing. In this study we evaluated the influence of MHC recognition on the proximal signaling events in NK cells binding tumor targets. We utilized two experimental models where NK cell-mediated cytotoxicity was fully inhibited by the recognition of specific MHC class I molecules. NK cell binding to either class I-deficient or class I-transfected target cells initiated rapid protein tyrosine kinase activation. In contrast, whereas NK cell binding to class I-deficient targets led to inositol phosphate release and increased intracellular free calcium ([Ca2+]i), NK recognition of class I-bearing targets did not induce the activation of these phospholipase C-dependent signaling events. The recognition of class I by NK cells clearly had a negative regulatory effect since blocking this interaction using anti-class I F(ab')2 fragments increased inositol 1,4,5-trisphosphate release and [Ca2+]i and increased the lysis of the targets. These results suggest that one of the mechanisms by which NK cell recognition of specific MHC class I molecules can block the development of cell-mediated cytotoxicity is by inhibiting specific critical signaling events. Images Fig. 2 Fig. 4 PMID:7604018

  8. Activation/Inhibition of mast cells by supra-optimal antigen concentrations.

    PubMed

    Huber, Michael

    2013-01-01

    Mast cells (MCs) are tissue resident cells of hemopoietic origin and are critically involved in allergic diseases. MCs bind IgE by means of their high-affinity receptor for IgE (FcεRI). The FcεRI belongs to a family of multi-chain immune recognition receptors and is activated by cross-linking in response to multivalent antigens (Ags)/allergens. Activation of the FcεRI results in immediate release of preformed granular substances (e.g. histamine, heparin, and proteases), generation of arachidonic acid metabolites, and production of pro-inflammatory cytokines. The FcεRI shows a remarkable, bell-shaped dose-response behavior with weak induction of effector responses at both low and high (so-called supra-optimal) Ag concentrations. This is significantly different from many other receptors, which reach a plateau phase in response to high ligand concentrations. To explain this unusual dose-response behavior of the FcεRI, scientists in the past have drawn parallels to so-called precipitin curves resulting from titration of Ag against a fixed concentration of antibody (Ab) in solution (a.k.a. Heidelberger curves). Thus, for high, supra-optimal Ag concentrations one could assume that every IgE-bound FcεRI formed a monovalent complex with "its own Ag", thus resulting in marginal induction of effector functions due to absence of receptor cross-linking. However, this was never proven to be the case. More recently, careful studies of FcεRI activation and signaling events in MCs in response to supra-optimal Ag concentrations have suggested a molecular explanation for the descending part of this bell-shaped curve. It is obvious now that extensive FcεRI/IgE/Ag clusters are formed and inhibitory molecules and signalosomes are engaged in response to supra-optimal cross-linking (amongst them the Src family kinase Lyn and the inositol-5'-phosphatase SHIP1) and they actively down-regulate MC effector responses. Thus, the analysis of MC signaling triggered by supra

  9. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine.

    PubMed

    Guo, Lili; Shestov, Alexander A; Worth, Andrew J; Nath, Kavindra; Nelson, David S; Leeper, Dennis B; Glickson, Jerry D; Blair, Ian A

    2016-01-01

    The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism. PMID:26521302

  10. Inhibition of Mitochondrial Complex II by the Anticancer Agent Lonidamine*

    PubMed Central

    Guo, Lili; Shestov, Alexander A.; Worth, Andrew J.; Nath, Kavindra; Nelson, David S.; Leeper, Dennis B.; Glickson, Jerry D.; Blair, Ian A.

    2016-01-01

    The antitumor agent lonidamine (LND; 1-(2,4-dichlorobenzyl)-1H-indazole-3-carboxylic acid) is known to interfere with energy-yielding processes in cancer cells. However, the effect of LND on central energy metabolism has never been fully characterized. In this study, we report that a significant amount of succinate is accumulated in LND-treated cells. LND inhibits the formation of fumarate and malate and suppresses succinate-induced respiration of isolated mitochondria. Utilizing biochemical assays, we determined that LND inhibits the succinate-ubiquinone reductase activity of respiratory complex II without fully blocking succinate dehydrogenase activity. LND also induces cellular reactive oxygen species through complex II, which reduced the viability of the DB-1 melanoma cell line. The ability of LND to promote cell death was potentiated by its suppression of the pentose phosphate pathway, which resulted in inhibition of NADPH and glutathione generation. Using stable isotope tracers in combination with isotopologue analysis, we showed that LND increased glutaminolysis but decreased reductive carboxylation of glutamine-derived α-ketoglutarate. Our findings on the previously uncharacterized effects of LND may provide potential combinational therapeutic approaches for targeting cancer metabolism. PMID:26521302

  11. The antigen 85 complex: a major secretion product of Mycobacterium tuberculosis.

    PubMed Central

    Wiker, H G; Harboe, M

    1992-01-01

    The large number of different proteins synthesized by the mycobacterial cell are currently classified and studied in terms of groups of proteins with certain common properties such as physical and chemical characteristics, function, and localization in the mycobacterial cell. Proteins that are actively secreted during culture on synthetic media represent a particular group of great current interest. At least eight proteins secreted by Mycobacterium tuberculosis have been isolated and characterized to various extents. The genes coding for five proteins secreted from M. tuberculosis and/or Mycobacterium bovis BCG have been cloned and sequenced. All of them contain typical signal sequences. The proteins of the antigen 85 complex, which form the main subject of this review, are often the most common proteins in M. tuberculosis culture fluid. The constituents denoted 85A, 85B, and 85C are encoded by three genes located at different sites in the mycobacterial genome and show extensive cross-reactivity as well as homology at amino acid and gene levels. The proteins differ slightly in molecular mass in the 30- to 31-kDa region, and all of them are fibronectin-binding proteins, but the significance of the latter observation and the role of these proteins in mycobacterial physiology and interaction with the infected host remain to be elucidated. The antigen 85 complex proteins are strongly immunogenic in natural and experimental mycobacterial infections in terms of both induction of antibody synthesis and T-cell-mediated reactions. The well-recognized difference in the efficacy of live and dead mycobacterial vaccines should be considered in relation to the group of secreted antigens. After inoculation, live bacteria in vaccines such as BCG multiply in the host, probably releasing several constituents belonging to the class of secreted proteins and hence resulting in more efficient stimulation of the immune system. Secreted mycobacterial antigens are expected to be of

  12. Antigen/IgG immune complex-primed mucosal mast cells mediate antigen-specific activation of co-cultured T cells

    PubMed Central

    Ding, Jie; Fang, Yu; Xiang, Zou

    2015-01-01

    Mast cells are proposed to be one of the targets for mucosal vaccine adjuvants. We previously demonstrated that mucosal adjuvants containing IgG immune complexes could activate connective tissue mast cells enhancing immune responses. Here we suggest that mucosal mast cells (MMC) may also contribute to augmentation of antigen-specific immune responses following treatment with antigens complexed with IgG. We demonstrated that both bone marrow-derived cultured MMC and tissue resident MMC incorporated ovalbumin (OVA) at a greater level in the presence of anti-OVA IgG. Co-culture of OVA/IgG-pulsed bone marrow-derived MMC with splenocytes from OT-II mice promoted OVA-specific activation and proliferation of T cells, a process known as cross-presentation. Furthermore, bone marrow-derived cultured MMC underwent apoptosis following treatment with IgG immune complexes, a feature that has been described as favouring phagocytosis of mast cells by professional antigen-presenting cells. PMID:25196548

  13. Metformin Suppresses MHC-Restricted Antigen Presentation by Inhibiting Co-Stimulatory Factors and MHC Molecules in APCs

    PubMed Central

    Shin, Seulmee; Hyun, Bobae; Lee, Aeri; Kong, Hyunseok; Han, Shinha; Lee, Chong-Kil; Ha, Nam-Joo; Kim, Kyungjae

    2013-01-01

    Metformin is widely used for T2D therapy but its cellular mechanism of action is undefined. Recent studies on the mechanism of metformin in T2D have demonstrated involvement of the immune system. Current immunotherapies focus on the potential of immunomodulatory strategies for the treatment of T2D. In this study, we examined the effects of metformin on the antigen-presenting function of antigen-presenting cells (APCs). Metformin decreased both MHC class I and class II-restricted presentation of OVA and suppressed the expression of both MHC molecules and co-stimulatory factors such as CD54, CD80, and CD86 in DCs, but did not affect the phagocytic activity toward exogenous OVA. The class II-restricted OVA presentation-regulating activity of metformin was also confirmed using mice that had been injected with metformin followed by soluble OVA. These results provide an understanding of the mechanisms of the T cell response-regulating activity of metformin through the inhibition of MHC-restricted antigen presentation in relation to its actions on APCs. PMID:24009856

  14. Sialic acid-modified antigens impose tolerance via inhibition of T-cell proliferation and de novo induction of regulatory T cells

    PubMed Central

    Perdicchio, Maurizio; Ilarregui, Juan M.; Verstege, Marleen I.; Cornelissen, Lenneke A. M.; Schetters, Sjoerd T. T.; Engels, Steef; Ambrosini, Martino; Kalay, Hakan; Veninga, Henrike; den Haan, Joke M. M.; van Berkel, Lisette A.; Samsom, Janneke N.; Crocker, Paul R.; Sparwasser, Tim; Berod, Luciana; Garcia-Vallejo, Juan J.; van Kooyk, Yvette; Unger, Wendy W. J.

    2016-01-01

    Sialic acids are negatively charged nine-carbon carboxylated monosaccharides that often cap glycans on glycosylated proteins and lipids. Because of their strategic location at the cell surface, sialic acids contribute to interactions that are critical for immune homeostasis via interactions with sialic acid-binding Ig-type lectins (siglecs). In particular, these interactions may be of importance in cases where sialic acids may be overexpressed, such as on certain pathogens and tumors. We now demonstrate that modification of antigens with sialic acids (Sia-antigens) regulates the generation of antigen-specific regulatory T (Treg) cells via dendritic cells (DCs). Additionally, DCs that take up Sia-antigen prevent formation of effector CD4+ and CD8+ T cells. Importantly, the regulatory properties endowed on DCs upon Sia-antigen uptake are antigen-specific: only T cells responsive to the sialylated antigen become tolerized. In vivo, injection of Sia-antigen–loaded DCs increased de novo Treg-cell numbers and dampened effector T-cell expansion and IFN-γ production. The dual tolerogenic features that Sia-antigen imposed on DCs are Siglec-E–mediated and maintained under inflammatory conditions. Moreover, loading DCs with Sia-antigens not only inhibited the function of in vitro–established Th1 and Th17 effector T cells but also significantly dampened ex vivo myelin-reactive T cells, present in the circulation of mice with experimental autoimmune encephalomyelitis. These data indicate that sialic acid-modified antigens instruct DCs in an antigen-specific tolerogenic programming, enhancing Treg cells and reducing the generation and propagation of inflammatory T cells. Our data suggest that sialylation of antigens provides an attractive way to induce antigen-specific immune tolerance. PMID:26941238

  15. [Elaboration of new adjuvant lipid-saponin complex and its use at experimental immunization by bacterial antigen].

    PubMed

    Tsybul'skiĭ, A V; Sanina, N M; Li, I A; Popov, A M; Kostetskiĭ, E Ia; Portniagina, O Iu; Shnyrov, V L

    2007-01-01

    Results of experiments on modification of immunostimulating complexes (ISCOM's) matrix by the replacement of the phospholipid for the glycolipid (monogalactosyldiacylglycerol) from sea macrophytes, and saponin QuillA to triterpene glycoside of cucumarioside A2-2 from Cucumaria japonica are shown. The resultant complexes include the morphological structures of two types: ISCOM-like structures with the characteristic morphology and sizes and also the tubular structures with diameter of approximately 40 nm and length of 150-400 nm. We have named these structures as TI-complexes. These TI-complexes exhibit considerably lower toxicity than ISCOM. They may include an amphiphilic protein antigen and provide immunoadjuvant effect during experimental vaccination. Under conditions of experimental immunization of mice by a weak immunogen--(subunit membrane pore protein from Y. pseudotuberculosis), TI-complexes with antigen provided stronger humoral immune response to antigen than the complexes of porin with classical ISCOM, liposomes and Freund's adjuvant. Thus, it's shown the prospect of the use of TI-complexes as a new type of adjuvant carriers for antigens. PMID:17722580

  16. Synthesis of biocompatible nanoparticle drug complexes for inhibition of mycobacteria

    NASA Astrophysics Data System (ADS)

    Bhave, Tejashree; Ghoderao, Prachi; Sanghavi, Sonali; Babrekar, Harshada; Bhoraskar, S. V.; Ganesan, V.; Kulkarni, Anjali

    2013-12-01

    Tuberculosis (TB) is one of the most critical infectious diseases affecting the world today. Current TB treatment involves six months long daily administration of four oral doses of antibiotics. Due to severe side effects and the long treatment, a patient's adherence is low and this results in relapse of symptoms causing an alarming increase in the prevalence of multi-drug resistant (MDR) TB. Hence, it is imperative to develop a new drug delivery technology wherein these effects can be reduced. Rifampicin (RIF) is one of the widely used anti-tubercular drugs (ATD). The present study discusses the development of biocompatible nanoparticle-RIF complexes with superior inhibitory activity against both Mycobacterium smegmatis (M. smegmatis) and Mycobacterium tuberculosis (M. tuberculosis). Iron oxide nanoparticles (NPs) synthesized by gas phase condensation and NP-RIF complexes were tested against M. smegmatis SN2 strain as well as M. tuberculosis H37Rv laboratory strain. These complexes showed significantly better inhibition of M. smegmatis SN2 strain at a much lower effective concentration (27.5 μg ml-1) as compared to neat RIF (125 μg ml-1). Similarly M. tuberculosis H37Rv laboratory strain was susceptible to both nanoparticle-RIF complex and neat RIF at a minimum inhibitory concentration of 0.22 and 1 μg ml-1, respectively. Further studies are underway to determine the efficacy of NPs-RIF complexes in clinical isolates of M. tuberculosis as well as MDR isolates.

  17. Immune complexes in the spleen. The difference between competitive inhibition of immune complex trapping in spleen follicles and inhibition by paratyphoid vaccine.

    PubMed Central

    van Rooijen, N

    1975-01-01

    Paratyphoid vaccine injected between 4 days and 3 hours before injection of labelled immune complexes (125-I-labelled BGG-anti-BGG), inhibits follicular trapping of these complexes in the mouse spleen. Inhibition is maximal when paratyphoid vaccine is given 1 day before, almost no label being found in the spleen follicles. No inhibition of follicular trapping of the complexes occurred when paratyphoid vaccine was injected simultaneously with the labelled immune complexes. Competitive inhibition was found when unlabelled immune complexes were given together with labelled immune complexes. Simultaneous injection of mice with paratyphoid vaccine and labelled immune complexes resulted in an additonal form of localization of the labelled immune complexes in the white pulp, heavily labelled clumps also appearing in the periarteriolar lymphocyte sheaths and follicles. The results are discussed in relation to the mechanism of immune complex trapping in spleen follicles. Images FIG. 1 FIG. 2 FIG. 3 PMID:1132890

  18. Cancer-testis antigens and immunotherapy in the light of cancer complexity.

    PubMed

    Grizzi, F; Mirandola, L; Qehajaj, D; Cobos, E; Figueroa, J A; Chiriva-Internati, M

    2015-03-01

    The ability of immunotherapy to evoke successful antitumor immune responses has been well documented over the past decade. Despite abundant preclinical data, it is only with the recent approval by the Food and Drug Administration (FDA) of the drugs such as sipuleucel-T and ipilimumab that immunotherapy is finally being recognized as a viable alternative to traditional therapies for treatment of various cancers. Despite the ability of immunotherapy to elicit successful antitumor immune responses, its efficacy is hindered by several factors. Among these are the paucity of tumor-associated antigens (TAA) that can be used as effective targets and the systemic toxicities that often lead to treatment interruption. Indeed, such adverse effects, which can be immunological and/or parenchymal, can be particularly severe and even fatal to some patients. A family of TAA called cancer-testis antigens (CTA) has been identified and their encoding genes have been extensively investigated. CTA expression has been demonstrated in a variety of human cancer tissues, and at least 19 CTA have been found to elicit humoral and/or cellular immune responses in cancer patients. Here we discuss how CTA and immunotherapy will most likely play a major role in the cure of cancer in the light of cancer complexity. PMID:25901859

  19. Identification of the Ro and La antigens in the endoribonuclease VII--ribonucleoprotein complex.

    PubMed Central

    Bachmann, M; Mayet, W J; Schröder, H C; Pfeifer, K; Meyer zum Büschenfelde, K H; Müller, W E

    1987-01-01

    45 S RNP (ribonucleoprotein) particles from calf thymus or L5178y mouse lymphoma cells contain the poly(A)-modulated and oligo(U)-binding endoribonuclease VII [Bachmann, Zahn & Müller (1983) J. Biol. Chem. 258, 7033-7040]. From these particles a 4.5 S RNA was isolated that possesses an oligo(U) sequence. By using monospecific and non-cross-reacting antibodies directed against the La or Ro antigen, both proteins were identified in the endoribonuclease VII-RNP complex after phosphorylation in vitro. In a second approach, endoribonuclease VII activity was identified in immunoaffinity-purified Ro RNPs after preparative isoelectric focusing. Therefore we conclude that the 4.5 S RNA belongs to the Ro RNAs. The results indicate a possible function of endoribonuclease VII in activating stored mRNAs. Images Fig. 1. Fig. 3. PMID:2440423

  20. The influence of monogalactosyldiacylglycerols from different marine macrophytes on immunogenicity and conformation of protein antigen of tubular immunostimulating complex.

    PubMed

    Sanina, Nina M; Kostetsky, Eduard Y; Shnyrov, Valery L; Tsybulsky, Alexander V; Novikova, Olga D; Portniagina, Olga Y; Vorobieva, Natalia S; Mazeika, Andrey N; Bogdanov, Mikhail V

    2012-04-01

    The tubular immunostimulating complex (TI-complex) is a novel nanoparticulate antigen delivery system consisting of cholesterol, triterpene glycoside cucumarioside A(2)-2, and glycolipid monogalactosyldiacylglycerol (MGDG) isolated from marine macrophytes. MGDG is crucial for the formation of a lipid matrix for the protein antigen incorporated in TI-complexes. Fatty acid composition and the physical state of this glycolipid depend on the taxonomic position of marine macrophytes. Therefore, the aim of the present work was to study the capacity of MGDGs, isolated from five species of marine macrophytes, to influence conformation and to enhance immunogenicity of porin from Yersinia pseudotuberculosis (YOmpF) as a model antigen of subunit vaccine based on TI-complexes. The trimeric porin was chosen for these experiments, because it was approximately two times more immunogenic than monomeric porin incorporated in TI-complexes. Immunization of mice with YOmpF within TI-complexes, comprised of different MGDGs, revealed a dependence of the immunostimulating effect of TI-complexes on the microvicosity of this glycolipid. TI-complexes comprising MGDGs from Sargassum pallidum and Ulva fenestrata with medium microviscosity induced maximal levels of anti-porin antibodies (four times higher when compared with those induced by pure porin). The adjuvant effect of TI-complexes based on other MGDGs varied by 2.8, 2.3 and 1.3 times for TI-complexes comprised of MGDGs from Zostera marina, Ahnfeltia tobuchiensis, and Laminaria japonica, respectively. MGDGs are also able to influence cytokine mechanisms of immunological regulation. DSC and spectroscopic studies showed that maximal immunostimulating effect of TI-complexes correlated with a moderate stabilizing influence of MGDGs from S. pallidum and U. fenestrata on the conformation of porin. The results obtained suggest lipid "nanofluidics" as a novel strategy for optimizing the immune response to protein antigens within lipid

  1. Characterization of anti-P monoclonal antibodies directed against the ribosomal protein–RNA complex antigen and produced using Murphy Roths large autoimmune-prone mice

    PubMed Central

    Sato, H; Onozuka, M; Hagiya, A; Hoshino, S; Narita, I; Uchiumi, T

    2015-01-01

    Autoantibodies, including anti-ribosomal P proteins (anti-P), are thought to be produced by an antigen-driven immune response in systemic lupus erythematosus (SLE). To test this hypothesis, we reconstituted the ribosomal antigenic complex in vitro using human P0, phosphorylated P1 and P2 and a 28S rRNA fragment covering the P0 binding site, and immunized Murphy Roths large (MRL)/lrp lupus mice with this complex without any added adjuvant to generate anti-P antibodies. Using hybridoma technology, we subsequently obtained 34 clones, each producing an anti-P monoclonal antibody (mAb) that recognized the conserved C-terminal tail sequence common to all three P proteins. We also obtained two P0-specific monoclonal antibodies, but no antibody specific to P1, P2 or rRNA fragment. Two types of mAbs were found among these anti-P antibodies: one type (e.g. 9D5) reacted more strongly with the phosphorylated P1 and P2 than that with their non-phosphorylated forms, whereas the other type (e.g. 4H11) reacted equally with both phosphorylated and non-phosphorylated forms of P1/P2. Both 9D5 and 4H11 inhibited the ribosome/eukaryotic elongation factor-2 (eEF-2)-coupled guanosine triphosphate (GTP)ase activity. However, preincubation with a synthetic peptide corresponding to the C-terminal sequence common to all three P proteins, but not the peptide that lacked the last three C-terminal amino acids, mostly prevented the mAb-induced inhibition of GTPase activity. Thus, at least two types of anti-P were produced preferentially following the immunization of MRL mice with the reconstituted antigenic complex. Presence of multiple copies of the C-termini, particularly that of the last three C-terminal amino acid residues, in the antigenic complex appears to contribute to the immunogenic stimulus. PMID:25255895

  2. Seminal plasma inhibits lymphocyte response to T-dependent and -independent antigens in vitro.

    PubMed Central

    Thomas, I K; Erickson, K L

    1984-01-01

    The effect of seminal plasma, epididymal spermatozoa, or whole semen on antibody producing cells was examined in vitro after (i) direct culture with spleen or B cells, and (ii) cocultivation of B cells with T cells previously incubated with seminal plasma. Seminal plasma, and not epididymal spermatozoa, have an inhibitory effect on the direct hemolytic plague forming cell response. This was mediated by a direct inhibitory effect on the B cell and not through the generation of suppressor T cells as demonstrated by responses to T-independent and -dependent antigens. Thus, the mode of suppressive action of seminal plasma in vitro is probably different from that previously reported in vivo. PMID:6235181

  3. Immunostimulating complexes incorporating Eimeria tenella antigens and plant saponins as effective delivery system for coccidia vaccine immunization.

    PubMed

    Berezin, V E; Bogoyavlenskiy, A P; Tolmacheva, V P; Makhmudova, N R; Khudyakova, S S; Levandovskaya, S V; Omirtaeva, E S; Zaitceva, I A; Tustikbaeva, G B; Ermakova, O S; Aleksyuk, P G; Barfield, R C; Danforth, H D; Fetterer, R H

    2008-04-01

    Immunostimulating complexes (ISCOMs) are unique, multimolecular structures formed by encapsulating antigens, lipids, and triterpene saponins of plant origin, and are an effective delivery system for various kinds of antigens. The uses of ISCOMs formulated with saponins from plants collected in Kazakhstan, with antigens from the poultry coccidian parasite Eimeria tenella, were evaluated for their potential use in developing a vaccine for control of avian coccidiosis. Saponins isolated from the plants Aesculus hippocastanum and Glycyrrhiza glabra were partially purified by HPLC. The saponin fractions obtained from HPLC were evaluated for toxicity in chickens and chicken embryos. The HPLC saponin fractions with the least toxicity, compared to a commercial saponin Quil A, were used to assemble ISCOMs. When chicks were immunized with ISCOMs prepared with saponins from Kazakhstan plants and E. tenella antigens, and then challenged with E. tenella oocysts, significant protection was conveyed compared to immunization with antigen alone. The results of this study indicate that ISCOMs formulated with saponins isolated from plants indigenous to Kazakhstan are an effective antigen delivery system which may be successfully used, with low toxicity, for preparation of highly immunogenic coccidia vaccine. PMID:18564738

  4. Inhibition of Simian Virus 40 replication by targeting the molecular chaperone function and ATPase activity of T antigen

    PubMed Central

    Wright, Christine M.; Seguin, Sandlin P.; Fewell, Sheara W.; Zhang, Haijiang; Ishwad, Chandra; Vats, Abhay; Lingwood, Cifford A.; Wipf, Peter; Fanning, Ellen; Pipas, James M.; Brodsky, Jeffrey L.

    2009-01-01

    Polyomaviruses such as BK virus and JC virus have been linked to several diseases, but treatments that thwart their propagation are limited in part because of slow growth and cumbersome culturing conditions. In contrast, the replication of one member of this family, Simian Virus 40 (SV40), is robust and has been well-characterized. SV40 replication requires two domains within the viral-encoded large tumor antigen (TAg): The ATPase domain and the N-terminal J domain, which stimulates the ATPase activity of the Hsp70 chaperone. To assess whether inhibitors of polyomavirus replication could be identified, we examined a recently described library of small molecules, some of which inhibit chaperone function. One compound, MAL2-11B, inhibited both TAg’s endogenous ATPase activity and the TAg-mediated activation of Hsp70. MAL2-11B also reduced SV40 propagation in plaque assays and compromised DNA replication in cell culture and in vitro. Furthermore, the compound significantly reduced the growth of BK virus in a human kidney cell line. These data indicate that pharmacological inhibition of TAg’s chaperone and ATPase activities may provide a route to combat polyomavirus-mediated disease. PMID:19200446

  5. Structural Insights into the Inhibition of Wnt Signaling by Cancer Antigen 5T4/Wnt-Activated Inhibitory Factor 1

    PubMed Central

    Zhao, Yuguang; Malinauskas, Tomas; Harlos, Karl; Jones, E. Yvonne

    2014-01-01

    Summary The tumor antigen 5T4/WAIF1 (Wnt-activated inhibitory factor 1; also known as Trophoblast glycoprotein TPBG) is a cell surface protein targeted in multiple cancer immunotherapy clinical trials. Recently, it has been shown that 5T4/WAIF1 inhibits Wnt/β-catenin signaling, a signaling system central to many developmental and pathological processes. Wnt/β-catenin signaling is controlled by multiple inhibitors and activators. Here, we report crystal structures for the extracellular domain of 5T4/WAIF1 at 1.8 Å resolution. They reveal a highly glycosylated, rigid core, comprising eight leucine-rich repeats (LRRs), which serves as a platform to present evolutionarily conserved surface residues in the N-terminal LRR1. Structural and cell-based analyses, coupled with previously reported in vivo data, suggest that Tyr325 plus the LRR1 surface centered on a second exposed aromatic residue, Phe97, are essential for inhibition of Wnt/β-catenin signaling. These results provide a structural basis for the development of 5T4/WAIF1-targeted therapies that preserve or block 5T4/WAIF1-mediated inhibition of Wnt/β-catenin signaling. PMID:24582434

  6. Mechanism of inhibition of immunoglobulin G-mediated phagocytosis by monoclonal antibodies that recognize the Mac-1 antigen.

    PubMed Central

    Brown, E J; Bohnsack, J F; Gresham, H D

    1988-01-01

    plasma membrane. Indeed, only approximately 60% of 125I-M1/70-biding sites were lost even after 4 h when monocytes were adherent to M1/70-coated surfaces. We conclude that some anti-Mac-1 antibodies can inhibit EA binding because of their epitope specificity, independent of any direct interaction with monocyte Fc receptors. This interference with IgG-Fc receptor-mediated binding and ingestion apparently occurs because of antibody binding to a subpopulation of Mac-1 molecules which are associated with IgG Fc receptors and remain on the apical membrane of monocytes adherent to anti-Mac-1-coated surfaces. We suggest that there may be two functionally distinct molecules on human monocytes recognized by M1/70 and Mo-1 that can be distinguished by their mobility in the plane of the monocyte membrane. The more mobile form of Mac-1 is involved in C3bi rosettes, and does not affect IgG-mediated phagocytosis. The other antigen recognized by M1/70 does not diffuse within the plane of the membrane; ligation of the latter molecule by antibody is associated with inhibition of IgG-mediated phagocytosis. Images PMID:2963020

  7. Heat-solubilized curry spice curcumin inhibits antibody-antigen interaction in in vitro studies: a possible therapy to alleviate autoimmune disorders.

    PubMed

    Kurien, Biji T; D'Souza, Anil; Scofield, R Hal

    2010-08-01

    Chronic and complex autoimmune diseases, currently treated palliatively with immunosuppressives, require multi-targeted therapy for greater effectiveness. The naturally occurring polyphenol curcumin has emerged as a powerful "nutraceutical" that interacts with multiple targets to regress diseases safely and inexpensively. Up to 8 g/day of curcumin for 18 months was non-toxic to humans. However, curcumin's utility is limited by its aqueous insolubility. We have demonstrated a heat-mediated 12-fold increase in curcumin's aqueous solubility. Here, we show by SDS-PAGE and surface plasmon resonance that heat-solubilized curcumin binds to proteins. Based on this binding we hypothesized that heat-solubilized curcumin or turmeric would prevent autoantibody targeting of cognate autoantigens. Heat-solubilized curcumin/turmeric significantly decreased binding of autoantibodies from Sjögren's syndrome (up to 43/70%, respectively) and systemic lupus erythematosus (up to 52/70%, respectively) patients as well as an animal model of Sjögren's syndrome (up to 50/60%, respectively) to their cognate antigens. However, inhibition was not specific to autoimmunity. Heat-solubilized curcumin/turmeric also inhibited binding of commercial polyclonal anti-spectrin to spectrin (50/56%, respectively). Thus, we suggest that the multifaceted heat-solubilized curcumin can ameliorate autoimmune disorders. In addition, the non-toxic curcumin could serve as a new protein stain in SDS-PAGE even though it is less sensitive than the Coomassie system which involves toxic chemicals. PMID:20146265

  8. Pharmacologic IKK/NF-κB inhibition causes antigen presenting cells to undergo TNFα dependent ROS-mediated programmed cell death

    NASA Astrophysics Data System (ADS)

    Tilstra, Jeremy S.; Gaddy, Daniel F.; Zhao, Jing; Davé, Shaival H.; Niedernhofer, Laura J.; Plevy, Scott E.; Robbins, Paul D.

    2014-01-01

    Monocyte-derived antigen presenting cells (APC) are central mediators of the innate and adaptive immune response in inflammatory diseases. As such, APC are appropriate targets for therapeutic intervention to ameliorate certain diseases. APC differentiation, activation and functions are regulated by the NF-κB family of transcription factors. Herein, we examined the effect of NF-κB inhibition, via suppression of the IκB Kinase (IKK) complex, on APC function. Murine bone marrow-derived macrophages and dendritic cells (DC), as well as macrophage and DC lines, underwent rapid programmed cell death (PCD) after treatment with several IKK/NF-κB inhibitors through a TNFα-dependent mechanism. PCD was induced proximally by reactive oxygen species (ROS) formation, which causes a loss of mitochondrial membrane potential and activation of a caspase signaling cascade. NF-κB-inhibition-induced PCD of APC may be a key mechanism through which therapeutic targeting of NF-κB reduces inflammatory pathologies.

  9. Pharmacologic IKK/NF-κB inhibition causes antigen presenting cells to undergo TNFα dependent ROS-mediated programmed cell death

    PubMed Central

    Tilstra, Jeremy S.; Gaddy, Daniel F.; Zhao, Jing; Davé, Shaival H.; Niedernhofer, Laura J.; Plevy, Scott E.; Robbins, Paul D.

    2014-01-01

    Monocyte-derived antigen presenting cells (APC) are central mediators of the innate and adaptive immune response in inflammatory diseases. As such, APC are appropriate targets for therapeutic intervention to ameliorate certain diseases. APC differentiation, activation and functions are regulated by the NF-κB family of transcription factors. Herein, we examined the effect of NF-κB inhibition, via suppression of the IκB Kinase (IKK) complex, on APC function. Murine bone marrow-derived macrophages and dendritic cells (DC), as well as macrophage and DC lines, underwent rapid programmed cell death (PCD) after treatment with several IKK/NF-κB inhibitors through a TNFα-dependent mechanism. PCD was induced proximally by reactive oxygen species (ROS) formation, which causes a loss of mitochondrial membrane potential and activation of a caspase signaling cascade. NF-κB-inhibition-induced PCD of APC may be a key mechanism through which therapeutic targeting of NF-κB reduces inflammatory pathologies. PMID:24406986

  10. Inactivation of the Mycobacterium tuberculosis antigen 85 complex by covalent, allosteric inhibitors.

    PubMed

    Favrot, Lorenza; Lajiness, Daniel H; Ronning, Donald R

    2014-09-01

    The rise of multidrug-resistant and totally drug-resistant tuberculosis and the association with an increasing number of HIV-positive patients developing tuberculosis emphasize the necessity to find new antitubercular targets and drugs. The antigen 85 (Ag85) complex from Mycobacterium tuberculosis plays important roles in the biosynthesis of major components of the mycobacterial cell envelope. For this reason, Ag85 has emerged as an attractive drug target. Recently, ebselen was identified as an effective inhibitor of the Ag85 complex through covalent modification of a cysteine residue proximal to the Ag85 active site and is therefore a covalent, allosteric inhibitor. To expand the understanding of this process, we have solved the x-ray crystal structures of Ag85C covalently modified with ebselen and other thiol-reactive compounds, p-chloromercuribenzoic acid and iodoacetamide, as well as the structure of a cysteine to glycine mutant. All four structures confirm that chemical modification or mutation at this particular cysteine residue leads to the disruption of the active site hydrogen-bonded network essential for Ag85 catalysis. We also describe x-ray crystal structures of Ag85C single mutants within the catalytic triad and show that a mutation of any one of these three residues promotes the same conformational change observed in the cysteine-modified forms. These results provide evidence for active site dynamics that may afford new strategies for the development of selective and potent Ag85 inhibitors. PMID:25028518

  11. Cytokines Regulate Proteolysis in Major Histocompatibility Complex Class II–Dependent Antigen Presentation by Dendritic Cells

    PubMed Central

    Fiebiger, Edda; Meraner, Paul; Weber, Ekkehard; Fang, I-Fei; Stingl, Georg; Ploegh, Hidde; Maurer, Dieter

    2001-01-01

    Endo/lysosomal proteases control two key events in antigen (Ag) presentation: the degradation of protein Ag and the generation of peptide-receptive major histocompatibility complex (MHC) class II molecules. Here we show that the proinflammatory cytokines tumor necrosis factor α and interleukin (IL)-1β rapidly increase the activity of cathepsin (cat) S and catB in human dendritic cells (DCs). As a consequence, a wave of MHC class II sodium dodecyl sulfate stable dimer formation ensues in a catS-dependent fashion. In contrast, the antiinflammatory cytokine IL-10 renders DCs incapable of upregulating catS and catB activity and in fact, attenuates the level of both enzymes. Suppressed catS and catB activity delays MHC class II sodium dodecyl sulfate stable dimer formation and impairs Ag degradation. In DCs exposed to tetanus toxoid, IL-10 accordingly reduces the number of MHC class II–peptide complexes accessible to tetanus toxoid–specific T cell receptors, as analyzed by measuring T cell receptor downregulation in Ag-specific T cell clones. Thus, the control of protease activity by pro- and antiinflammatory cytokines is an essential feature of the Ag presentation properties of DCs. PMID:11304549

  12. Accurate structure prediction of peptide–MHC complexes for identifying highly immunogenic antigens

    SciTech Connect

    Park, Min-Sun; Park, Sung Yong; Miller, Keith R.; Collins, Edward J.; Lee, Ha Youn

    2013-11-01

    Designing an optimal HIV-1 vaccine faces the challenge of identifying antigens that induce a broad immune capacity. One factor to control the breadth of T cell responses is the surface morphology of a peptide–MHC complex. Here, we present an in silico protocol for predicting peptide–MHC structure. A robust signature of a conformational transition was identified during all-atom molecular dynamics, which results in a model with high accuracy. A large test set was used in constructing our protocol and we went another step further using a blind test with a wild-type peptide and two highly immunogenic mutants, which predicted substantial conformational changes in both mutants. The center residues at position five of the analogs were configured to be accessible to solvent, forming a prominent surface, while the residue of the wild-type peptide was to point laterally toward the side of the binding cleft. We then experimentally determined the structures of the blind test set, using high resolution of X-ray crystallography, which verified predicted conformational changes. Our observation strongly supports a positive association of the surface morphology of a peptide–MHC complex to its immunogenicity. Our study offers the prospect of enhancing immunogenicity of vaccines by identifying MHC binding immunogens.

  13. Inactivation of the Mycobacterium tuberculosis Antigen 85 Complex by Covalent, Allosteric Inhibitors*

    PubMed Central

    Favrot, Lorenza; Lajiness, Daniel H.; Ronning, Donald R.

    2014-01-01

    The rise of multidrug-resistant and totally drug-resistant tuberculosis and the association with an increasing number of HIV-positive patients developing tuberculosis emphasize the necessity to find new antitubercular targets and drugs. The antigen 85 (Ag85) complex from Mycobacterium tuberculosis plays important roles in the biosynthesis of major components of the mycobacterial cell envelope. For this reason, Ag85 has emerged as an attractive drug target. Recently, ebselen was identified as an effective inhibitor of the Ag85 complex through covalent modification of a cysteine residue proximal to the Ag85 active site and is therefore a covalent, allosteric inhibitor. To expand the understanding of this process, we have solved the x-ray crystal structures of Ag85C covalently modified with ebselen and other thiol-reactive compounds, p-chloromercuribenzoic acid and iodoacetamide, as well as the structure of a cysteine to glycine mutant. All four structures confirm that chemical modification or mutation at this particular cysteine residue leads to the disruption of the active site hydrogen-bonded network essential for Ag85 catalysis. We also describe x-ray crystal structures of Ag85C single mutants within the catalytic triad and show that a mutation of any one of these three residues promotes the same conformational change observed in the cysteine-modified forms. These results provide evidence for active site dynamics that may afford new strategies for the development of selective and potent Ag85 inhibitors. PMID:25028518

  14. An AXL/LRP-1/RANBP9 complex mediates DC efferocytosis and antigen cross-presentation in vivo

    PubMed Central

    Subramanian, Manikandan; Hayes, Crystal D.; Thome, Joseph J.; Thorp, Edward; Matsushima, Glenn K.; Herz, Joachim; Farber, Donna L.; Liu, Kang; Lakshmana, Madepalli; Tabas, Ira

    2014-01-01

    The phagocytosis of apoptotic cells (ACs), or efferocytosis, by DCs is critical for self-tolerance and host defense. Although many efferocytosis-associated receptors have been described in vitro, the functionality of these receptors in vivo has not been explored in depth. Using a spleen efferocytosis assay and targeted genetic deletion in mice, we identified a multiprotein complex — composed of the receptor tyrosine kinase AXL, LDL receptor–related protein–1 (LRP-1), and RAN-binding protein 9 (RANBP9) — that mediates DC efferocytosis and antigen cross-presentation. We found that AXL bound ACs, but required LRP-1 to trigger internalization, in murine CD8α+ DCs and human-derived DCs. AXL and LRP-1 did not interact directly, but relied on RANBP9, which bound both AXL and LRP-1, to form the complex. In a coculture model of antigen presentation, the AXL/LRP-1/RANBP9 complex was used by DCs to cross-present AC-associated antigens to T cells. Furthermore, in a murine model of herpes simplex virus–1 infection, mice lacking DC-specific LRP-1, AXL, or RANBP9 had increased AC accumulation, defective viral antigen-specific CD8+ T cell activation, enhanced viral load, and decreased survival. The discovery of this multiprotein complex that mediates functionally important DC efferocytosis in vivo may have implications for future studies related to host defense and DC-based vaccines. PMID:24509082

  15. Genetic factors influence level of proteinuria in cationic antigen-induced immune complex glomerulonephritis in the rat.

    PubMed Central

    Kato, A; Thaiss, F; Oite, T; Günther, E; Batsford, S; Vogt, A

    1985-01-01

    The influence of genetic factors on the susceptibility of the rat to cationic antigen-induced in situ immune complex glomerulonephritis was investigated. The levels of proteinuria developing in 11 inbred strains of rats differing in MHC and in genetic background varied markedly. Susceptibility was not MHC associated but resided in the genetic background. PMID:3159528

  16. Cestode Antigens Induce a Tolerogenic-Like Phenotype and Inhibit LPS Inflammatory Responses in Human Dendritic Cells

    PubMed Central

    Terrazas, César A.; Sánchez-Muñoz, Fausto; Mejía-Domínguez, Ana M.; Amezcua-Guerra, Luis M.; Terrazas, Luis I.; Bojalil, Rafael; Gómez-García, Lorena

    2011-01-01

    Pathogens have developed strategies to modify Dendritic Cells (DCs) phenotypes and impair their functions in order to create a safer environment for their survival. DCs responses to helminths and their derivatives vary among different studies. Here we show that excretory/secretory products of the cestode Taenia crassiceps (TcES) do not induce the maturation of human DCs judged by a lack of increment in the expression of CD83, HLA-DR, CD80 and CD86 molecules but enhanced the production of IL-10 and positively modulated the expression of the C-type lectin receptor MGL and negatively modulated the expression of DC-SIGN. Additionally, these antigens were capable of down-modulating the inflammatory response induced by LPS in these cells by reducing the expression of the maturation markers and the production of the inflammatory cytokines IL-1β, TNF, IL-12 and IL-6. The effects of TcES upon the DCs responses to LPS were stronger if cells were exposed during their differentiation to the helminth antigens. All together, these findings suggest the ability of TcES to induce the differentiation of human DCs into a tolerogenic-like phenotype and to inhibit the effects of inflammatory stimuli. PMID:22110390

  17. The Human EKC/KEOPS Complex Is Recruited to Cullin2 Ubiquitin Ligases by the Human Tumour Antigen PRAME

    PubMed Central

    Costessi, Adalberto; Mahrour, Nawel; Sharma, Vikram; Stunnenberg, Rieka; Stoel, Marieke A.; Tijchon, Esther; Conaway, Joan W.; Conaway, Ronald C.; Stunnenberg, Hendrik G.

    2012-01-01

    The human tumour antigen PRAME (preferentially expressed antigen in melanoma) is frequently overexpressed during oncogenesis, and high PRAME levels are associated with poor clinical outcome in a variety of cancers. However, the molecular pathways in which PRAME is implicated are not well understood. We recently characterized PRAME as a BC-box subunit of a Cullin2-based E3 ubiquitin ligase. In this study, we mined the PRAME interactome to a deeper level and identified specific interactions with OSGEP and LAGE3, which are human orthologues of the ancient EKC/KEOPS complex. By characterizing biochemically the human EKC complex and its interactions with PRAME, we show that PRAME recruits a Cul2 ubiquitin ligase to EKC. Moreover, EKC subunits associate with PRAME target sites on chromatin. Our data reveal a novel link between the oncoprotein PRAME and the conserved EKC complex and support a role for both complexes in the same pathways. PMID:22912744

  18. Viral Inhibition of the Transporter Associated with Antigen Processing (TAP): A Striking Example of Functional Convergent Evolution

    PubMed Central

    Verweij, Marieke C.; Horst, Daniëlle; Griffin, Bryan D.; Luteijn, Rutger D.; Davison, Andrew J.; Ressing, Maaike E.; Wiertz, Emmanuel J. H. J.

    2015-01-01

    Herpesviruses are large DNA viruses that are highly abundant within their host populations. Even in the presence of a healthy immune system, these viruses manage to cause lifelong infections. This persistence is partially mediated by the virus entering latency, a phase of infection characterized by limited viral protein expression. Moreover, herpesviruses have devoted a significant part of their coding capacity to immune evasion strategies. It is believed that the close coexistence of herpesviruses and their hosts has resulted in the evolution of viral proteins that specifically attack multiple arms of the host immune system. Cytotoxic T lymphocytes (CTLs) play an important role in antiviral immunity. CTLs recognize their target through viral peptides presented in the context of MHC molecules at the cell surface. Every herpesvirus studied to date encodes multiple immune evasion molecules that effectively interfere with specific steps of the MHC class I antigen presentation pathway. The transporter associated with antigen processing (TAP) plays a key role in the loading of viral peptides onto MHC class I molecules. This is reflected by the numerous ways herpesviruses have developed to block TAP function. In this review, we describe the characteristics and mechanisms of action of all known virus-encoded TAP inhibitors. Orthologs of these proteins encoded by related viruses are identified, and the conservation of TAP inhibition is discussed. A phylogenetic analysis of members of the family Herpesviridae is included to study the origin of these molecules. In addition, we discuss the characteristics of the first TAP inhibitor identified outside the herpesvirus family, namely, in cowpox virus. The strategies of TAP inhibition employed by viruses are very distinct and are likely to have been acquired independently during evolution. These findings and the recent discovery of a non-herpesvirus TAP inhibitor represent a striking example of functional convergent evolution

  19. Targeting Tumor Initiating Cells through Inhibition of Cancer Testis Antigens and Notch Signaling: A Hypothesis.

    PubMed

    Colombo, Michela; Mirandola, Leonardo; Reidy, Adair; Suvorava, Natallia; Konala, Venu; Chiaramonte, Raffaella; Grizzi, Fabio; Rahman, Rakhshanda Layeequr; Jenkins, Marjorie R; Nugyen, Diane D; Dalhbeck, Scott; Cobos, Everardo; Figueroa, Jose A; Chiriva-Internati, Maurizio

    2015-03-01

    Tumor initiating cells (TICs) differ from normal stem cells (SCs) in their ability to initiate tumorigenesis, invasive growth, metastasis and the acquisition of chemo and/or radio-resistance. Over the past years, several studies have indicated the potential role of the Notch system as a key regulator of cellular stemness and tumor development. Furthermore, the expression of cancer testis antigens (CTA) in TICs, and their role in SC differentiation and biology, has become an important area of investigation. Here, we propose a model in which CTA expression and Notch signaling interacts to maintain the sustainability of self-replicating tumor populations, ultimately leading to the development of metastasis, drug resistance and cancer progression. We hypothesize that Notch-CTA interactions in TICs offer a novel opportunity for meaningful therapeutic interventions in cancer. PMID:25901861

  20. Inhibition of Histo-blood Group Antigen Binding as a Novel Strategy to Block Norovirus Infections

    PubMed Central

    Zhang, Xu-Fu; Tan, Ming; Chhabra, Monica; Dai, Ying-Chun; Meller, Jarek; Jiang, Xi

    2013-01-01

    Noroviruses (NoVs) are the most important viral pathogens that cause epidemic acute gastroenteritis. NoVs recognize human histo-blood group antigens (HBGAs) as receptors or attachment factors. The elucidation of crystal structures of the HBGA-binding interfaces of a number of human NoVs representing different HBGA binding patterns opens a new strategy for the development of antiviral compounds against NoVs through rational drug design and computer-aided virtual screening methods. In this study, docking simulations and virtual screening were used to identify hit compounds targeting the A and B antigens binding sites on the surface of the capsid P protein of a GII.4 NoV (VA387). Following validation by re-docking of the A and B ligands, these structural models and AutoDock suite of programs were used to screen a large drug-like compound library (derived from ZINC library) for inhibitors blocking GII.4 binding to HBGAs. After screening >2 million compounds using multistage protocol, 160 hit compounds with best predicted binding affinities and representing a number of distinct chemical classes have been selected for subsequent experimental validation. Twenty of the 160 compounds were found to be able to block the VA387 P dimers binding to the A and/or B HBGAs at an IC50<40.0 µM, with top 5 compounds blocking the HBGA binding at an IC50<10.0 µM in both oligosaccharide- and saliva-based blocking assays. Interestingly, 4 of the top-5 compounds shared the basic structure of cyclopenta [a] dimethyl phenanthren, indicating a promising structural template for further improvement by rational design. PMID:23894462

  1. Inhibition of histo-blood group antigen binding as a novel strategy to block norovirus infections.

    PubMed

    Zhang, Xu-Fu; Tan, Ming; Chhabra, Monica; Dai, Ying-Chun; Meller, Jarek; Jiang, Xi

    2013-01-01

    Noroviruses (NoVs) are the most important viral pathogens that cause epidemic acute gastroenteritis. NoVs recognize human histo-blood group antigens (HBGAs) as receptors or attachment factors. The elucidation of crystal structures of the HBGA-binding interfaces of a number of human NoVs representing different HBGA binding patterns opens a new strategy for the development of antiviral compounds against NoVs through rational drug design and computer-aided virtual screening methods. In this study, docking simulations and virtual screening were used to identify hit compounds targeting the A and B antigens binding sites on the surface of the capsid P protein of a GII.4 NoV (VA387). Following validation by re-docking of the A and B ligands, these structural models and AutoDock suite of programs were used to screen a large drug-like compound library (derived from ZINC library) for inhibitors blocking GII.4 binding to HBGAs. After screening >2 million compounds using multistage protocol, 160 hit compounds with best predicted binding affinities and representing a number of distinct chemical classes have been selected for subsequent experimental validation. Twenty of the 160 compounds were found to be able to block the VA387 P dimers binding to the A and/or B HBGAs at an IC50<40.0 µM, with top 5 compounds blocking the HBGA binding at an IC50<10.0 µM in both oligosaccharide- and saliva-based blocking assays. Interestingly, 4 of the top-5 compounds shared the basic structure of cyclopenta [a] dimethyl phenanthren, indicating a promising structural template for further improvement by rational design. PMID:23894462

  2. The Protective Antigen Component of Anthrax Toxin Forms Functional Octameric Complexes

    PubMed Central

    Kintzer, Alexander F.; Thoren, Katie L.; Sterling, Harry J.; Dong, Ken C.; Feld, Geoffrey K.; Tang, Iok I.; Zhang, Teri T.; Williams, Evan R.; Berger, James M.; Krantz, Bryan A.

    2009-01-01

    The assembly of bacterial toxins and virulence factors is critical to their function, but the regulation of assembly during infection has not been studied. We begin to address this question using anthrax toxin as a model. The protective antigen (PA) component of the toxin assembles into ring-shaped homooligomers that bind the two other enzyme components of the toxin, lethal factor (LF) and edema factor (EF), to form toxic complexes. To disrupt the host, these toxic complexes are endocytosed, such that the PA oligomer forms a membrane-spanning channel that LF and EF translocate through to enter the cytosol. We show using single-channel electrophysiology that PA channels contain two populations of conductance states, which correspond with two different PA pre-channel oligomers observed by electron microscopy—the well-described heptamer and a novel octamer. Mass spectrometry demonstrates that the PA octamer binds four LFs, and assembly routes leading to the octamer are populated with even-numbered, dimeric and tetrameric, PA intermediates. Both heptameric and octameric PA complexes can translocate LF and EF with similar rates and efficiencies. Here we also report a 3.2-Å crystal structure of the PA octamer. The octamer comprises ∼20−30% of the oligomers on cells, but outside of the cell, the octamer is more stable than the heptamer under physiological pH. Thus the PA octamer is a physiological, stable, and active assembly state capable of forming lethal toxins that may withstand the hostile conditions encountered in the bloodstream. This assembly mechanism may provide a novel means to control cytotoxicity. PMID:19627991

  3. Carcinoembryonic antigen promotes colorectal cancer progression by targeting adherens junction complexes

    SciTech Connect

    Bajenova, Olga; Chaika, Nina; Tolkunova, Elena; Davydov-Sinitsyn, Alexander; Gapon, Svetlana; Thomas, Peter; O’Brien, Stephen

    2014-06-10

    Oncomarkers play important roles in the detection and management of human malignancies. Carcinoembryonic antigen (CEA, CEACAM5) and epithelial cadherin (E-cadherin) are considered as independent tumor markers in monitoring metastatic colorectal cancer. They are both expressed by cancer cells and can be detected in the blood serum. We investigated the effect of CEA production by MIP101 colorectal carcinoma cell lines on E-cadherin adherens junction (AJ) protein complexes. No direct interaction between E-cadherin and CEA was detected; however, the functional relationships between E-cadherin and its AJ partners: α-, β- and p120 catenins were impaired. We discovered a novel interaction between CEA and beta-catenin protein in the CEA producing cells. It is shown in the current study that CEA overexpression alters the splicing of p120 catenin and triggers the release of soluble E-cadherin. The influence of CEA production by colorectal cancer cells on the function of E-cadherin junction complexes may explain the link between the elevated levels of CEA and the increase in soluble E-cadherin during the progression of colorectal cancer. - Highlights: • Elevated level of CEA increases the release of soluble E-cadherin during the progression of colorectal cancer. • CEA over-expression alters the binding preferences between E-cadherin and its partners: α-, β- and p120 catenins in adherens junction complexes. • CEA produced by colorectal cancer cells interacts with beta-catenin protein. • CEA over-expression triggers the increase in nuclear beta-catenin. • CEA over-expression alters the splicing of p120 catenin protein.

  4. Transcriptional activation by simian virus 40 large T antigen: interactions with multiple components of the transcription complex.

    PubMed Central

    Gruda, M C; Zabolotny, J M; Xiao, J H; Davidson, I; Alwine, J C

    1993-01-01

    Simian virus 40 (SV40) large T antigen is a potent transcriptional activator of both viral and cellular promoters. Within the SV40 late promoter, a specific upstream element necessary for T-antigen transcriptional activation is the binding site for transcription-enhancing factor 1 (TEF-1). The promoter structure necessary for T-antigen-mediated transcriptional activation appears to be simple. For example, a promoter consisting of upstream TEF-1 binding sites (or other factor-binding sites) and a downstream TATA or initiator element is efficiently activated. It has been demonstrated that transcriptional activation by T antigen does not require direct binding to the DNA; thus, the most direct effect that T antigen could have on these simple promoters would be through protein-protein interactions with either upstream-bound transcription factors, the basal transcription complex, or both. To determine whether such interactions occur, full-length T antigen or segments of it was fused to the glutathione-binding site (GST fusions) or to the Gal4 DNA-binding domain (amino acids 1 to 147) (Gal4 fusions). With the GST fusions, it was found that TEF-1 and the TATA-binding protein (TBP) bound different regions of T antigen. A GST fusion containing amino acids 5 to 172 (region T1) efficiently bound TBP. TEF-1 bound neither region T1 nor a region between amino acids 168 and 373 (region T2); however, it bound efficiently to the combined region (T5) containing amino acids 5 to 383.(ABSTRACT TRUNCATED AT 250 WORDS) Images PMID:8423815

  5. Antigen Transfer from Exosomes to Dendritic Cells as an Explanation for the Immune Enhancement Seen by IgE Immune Complexes

    PubMed Central

    Henningsson, Frida; Heyman, Birgitta; Conrad, Daniel H.

    2014-01-01

    IgE antigen complexes induce increased specific T cell proliferation and increased specific IgG production. Immediately after immunization, CD23+ B cells capture IgE antigen complexes, transport them to the spleen where, via unknown mechanisms, dendritic cells capture the antigen and present it to T cells. CD23, the low affinity IgE receptor, binds IgE antigen complexes and internalizes them. In this study, we show that these complexes are processed onto B-cell derived exosomes (bexosomes) in a CD23 dependent manner. The bexosomes carry CD23, IgE and MHC II and stimulate antigen specific T-cell proliferation in vitro. When IgE antigen complex stimulated bexosomes are incubated with dendritic cells, dendritic cells induce specific T-cell proliferation in vivo, similar to IgE antigen complexes. This suggests that bexosomes can provide the essential transfer mechanism for IgE antigen complexes from B cells to dendritic cells. PMID:25330118

  6. Crystal Structure of Plasmodium knowlesi Apical Membrane Antigen 1 and Its Complex with an Invasion-Inhibitory Monoclonal Antibody

    PubMed Central

    van der Eijk, Marjolein; Thomas, Alan W.; Singh, Balbir; Kocken, Clemens H. M.

    2015-01-01

    The malaria parasite Plasmodium knowlesi, previously associated only with infection of macaques, is now known to infect humans as well and has become a significant public health problem in Southeast Asia. This species should therefore be targeted in vaccine and therapeutic strategies against human malaria. Apical Membrane Antigen 1 (AMA1), which plays a role in Plasmodium merozoite invasion of the erythrocyte, is currently being pursued in human vaccine trials against P. falciparum. Recent vaccine trials in macaques using the P. knowlesi orthologue PkAMA1 have shown that it protects against infection by this parasite species and thus should be developed for human vaccination as well. Here, we present the crystal structure of Domains 1 and 2 of the PkAMA1 ectodomain, and of its complex with the invasion-inhibitory monoclonal antibody R31C2. The Domain 2 (D2) loop, which is displaced upon binding the Rhoptry Neck Protein 2 (RON2) receptor, makes significant contacts with the antibody. R31C2 inhibits binding of the Rhoptry Neck Protein 2 (RON2) receptor by steric blocking of the hydrophobic groove and by preventing the displacement of the D2 loop which is essential for exposing the complete binding site on AMA1. R31C2 recognizes a non-polymorphic epitope and should thus be cross-strain reactive. PkAMA1 is much less polymorphic than the P. falciparum and P. vivax orthologues. Unlike these two latter species, there are no polymorphic sites close to the RON2-binding site of PkAMA1, suggesting that P. knowlesi has not developed a mechanism of immune escape from the host’s humoral response to AMA1. PMID:25886591

  7. Pectinesterase Inhibitor from Jelly Fig (Ficus awkeotsang Makino) Achene Inhibits Surface Antigen Expression by Human Hepatitis B Virus.

    PubMed

    Huang, Yu-Chuen; Jiang, Chii-Ming; Chen, Yu-Jen; Chen, Yu-Yawn

    2013-01-01

    Pectinesterase inhibitor (PEI) isolated from jelly fig (Ficus awkeotsang Makino) is an edible component of a popular drink consumed in Asia. Hepatitis B virus (HBV) infection is prevalent in Asia, and current treatments for HBV infection need improvement. This study aimed to evaluate the effect of PEI on the surface antigen expression by HBV (HBsAg). Human hepatoma cell lines Hep3B and Huh7 served as in vitro models for assessing the cytotoxicity and HBsAg expression. A culture of primary hepatocytes cultured from mice served as the normal counterpart. Cell viability was measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. HBsAg expression was evaluated by measuring HBsAg secretion into the culture medium using an enzyme-linked immunosorbent assay. The results showed that PEI did not affect the viability of the human hepatoma cell lines or primary mouse hepatocytes. PEI inhibited the expression of HBsAg in hepatoma cell lines harboring endogenous (Hep3B) and integrated (Huh7) HBV genomes in a concentration- and time-dependent manner, thus implicating a universal activity against HBV gene expression. In conclusion, it suggests that PEI from jelly fig inhibits the expression of human HBsAg in host cells without toxic effects on normal primary hepatocytes. PMID:24302965

  8. Class II major histocompatibility complex antigen expression on peripheral blood monocytes in patients with inflammatory bowel disease.

    PubMed Central

    Gardiner, K R; Crockard, A D; Halliday, M I; Rowlands, B J

    1994-01-01

    Macrophage major histocompatibility complex (MHC) class II antigen expression is associated with defective antigen presentation to T lymphocytes in animals and is predictive of patient outcome after major trauma or sepsis. In this study, class II antigen (HLA-DR and DQ) expression on peripheral blood monocytes was investigated in patients with inflammatory bowel disease in relation to disease activity and outcome. The percentage positivity and fluorescent intensity of expression of HLA-DR and DQ antigens on monocytes were determined in whole blood samples using dual colour immunofluorescence labelling and flow cytometry. Disease activity was assessed using clinical and laboratory indices. There was no significant difference in percentage positivity or fluorescent intensity of class II antigen expression between patients with Crohn's disease, those with ulcerative colitis, and healthy volunteers. The percentage of monocytes displaying HLA-DR positivity was significantly decreased in patients with active ulcerative colitis (active %: 49.5 (5.6); inactive %: 78.9 (6.9); p = 0.01). Data expressed as mean (SEM). In patients requiring surgical resection of diseased bowel, the percentage of monocytes displaying HLA-DR positivity (51.9 (4.0) %) was significantly reduced compared with patients receiving medical treatment alone (81.1 (3.5) %; p < 0.001). Reduced monocyte HLA-DR expression is therefore associated with disease activity and seems to predict outcome in patients with inflammatory bowel disease. PMID:8174990

  9. Effects of messenger RNA structure and other translational control mechanisms on major histocompatibility complex-I mediated antigen presentation

    PubMed Central

    Murat, Pierre; Tellam, Judy

    2015-01-01

    Effective T-cell surveillance of antigen-presenting cells is dependent on the expression of an array of antigenic peptides bound to major histocompatibility complex (MHC) class I (MHC-I) or class II (MHC-II) molecules. Pathogens co-evolving with their hosts exploit crucial translational regulatory mechanisms in order to evade host immune recognition and thereby sustain their infection. Evasion strategies that downregulate viral protein synthesis and thereby restrict antigen presentation to cytotoxic T-cells through the endogenous MHC-I pathway have been implicated in the pathogenesis of viral-associated malignancies. An understanding of the mechanisms by which messenger RNA (mRNA) structure modulates both viral mRNA translation and the antigen processing machinery to escape immune surveillance, will stimulate the development of alternative therapeutic strategies focused on RNA-directed drugs designed to enhance immune responses against infected cells. In this review, we discuss regulatory aspects of the MHC-I pathway and summarize current knowledge of the role attributed by mRNA structure and other translational regulatory mechanisms in immune evasion. In particular we highlight the impact of recently identified G-quadruplex structures within virally encoded transcripts as unique regulatory signals for translational control and antigen presentation. WIREs RNA 2015, 6:157–171. doi: 10.1002/wrna.1262 PMID:25264139

  10. Porous nanoparticles as delivery system of complex antigens for an effective vaccine against acute and chronic Toxoplasma gondii infection.

    PubMed

    Dimier-Poisson, Isabelle; Carpentier, Rodolphe; N'Guyen, Thi Thanh Loi; Dahmani, Fatima; Ducournau, Céline; Betbeder, Didier

    2015-05-01

    Development of sub-unit mucosal vaccines requires the use of specific delivery systems or immune-modulators such as adjuvants to improve antigen immunogenicity. Nasal route for vaccine delivery by nanoparticles has attracted much interest but mechanisms triggering effective mucosal and systemic immune response are still poorly understood. Here we study the loading of porous nanoparticles (DGNP) with a total extract of Toxoplasma gondii antigens (TE), the delivery of TE by DGNP into airway epithelial, macrophage and dendritic cells, and the subsequent cellular activation. In vitro, DGNP are able to load complex antigens in a stable and quantitative manner. The outstanding amount of antigen association by DGNP is used to deliver TE in airway mucosa cells to induce a cellular maturation with an increased secretion of pro-inflammatory cytokines. Evaluation of nasal vaccine efficiency is performed in vivo on acute and chronic toxoplasmosis mouse models. A specific Th1/Th17 response is observed in vivo after vaccination with DGNP/TE. This is associated with high protection against toxoplasmosis regarding survival and parasite burden, correlated with an increased delivery of antigens by DGNP in airway mucosa cells. This study provides evidence of the potential of DGNP for the development of new vaccines against a range of pathogens. PMID:25736506

  11. Outcome of limbic encephalitis with VGKC-complex antibodies: relation to antigenic specificity.

    PubMed

    Malter, M P; Frisch, C; Schoene-Bake, J C; Helmstaedter, C; Wandinger, K P; Stoecker, W; Urbach, H; Surges, R; Elger, C E; Vincent, A V; Bien, C G

    2014-09-01

    In limbic encephalitis (LE) with antibodies (Abs) to the voltage-gated potassium channel complex (VGKC), the Abs are mainly directed to the VGKC-complex proteins, leucine-rich, glioma inactivated 1 protein (LGI1) or contactin-associated protein-like 2 (CASPR-2) or neither. Here, we relate the outcomes of VGKC-LE patients to the presence of Abs to LGI1, CASPR-2 or neither antigen (LGI1/CASPR-2-Ab(-)). Clinical, neuropsychology and MRI data were obtained from patient records for all LE patients from the Bonn Epilepsy Centre positive for VGKC-Abs by radioimmunoprecipitation assay between 2002 and 2011. Eighteen VGKC-LE patients were identified: nine patients (50 %) had LGI1-Abs, three (16 %) had CASPR-2-Abs; and six (33 %) were negative for both LGI1- and CASPR-2-Abs. At first assessment, the groups did not differ clinically or radiologically, but faciobrachial dystonic seizures were only observed in two LGI1-Ab(+) patients. All patients received monthly intravenous methylprednisolone (MP) pulses. At the most recent follow up (median 26 months), thirteen (72 %) were seizure-free, and seizure-freedom rates did not differ between the Ab groups. Hippocampal atrophy had developed in 7/9 LGI1-Ab(+) patients, but in none of the CASPR-2-Ab(+) or LGI/CASPR-2-Ab(-) patients (p = 0.003). While all subgroups improved, memory scores only normalized in six patients (33 %) and LGI1-Ab(+) patients were left with significantly poorer memory than the other two subgroups. Most VGKC-LE patients become seizure-free with pulsed monthly MP, but memory outcome is less favourable. Hippocampal atrophy and poor memory recovery is common in patients with LGI1-Abs and suggests permanent functional damage. More intense immunotherapies could improve outcomes in LGI1-Ab(+)-LE. PMID:24935858

  12. Tissue Localization of Australia Antigen Immune Complexes in Acute and Chronic Hepatitis and Liver Cirrhosis

    PubMed Central

    Nowosławski, Adam; Krawczyński, Krzysztof; Brzosko, Witold J.; Madaliński, Kazimierz

    1972-01-01

    In a significant percentage of examined cases of fulminant hepatitis, subacute hepatitis, chronic aggressive hepatitis, liver cirrhosis and chronic persistent hepatitis, Australia (hepatitis-associated) antigen (Au HAA) was identified in the liver and in extrahepatic locations. The several immunofluorescent patterns of Au HAA localization in hepatocytes strongly suggested various stages of Au HAA accumulation and release. Deposits of a mixture of immunoglobulins G and M and occasionally β1C-globulin were found in the cytoplasm of Au HAA containing hepatocytes, on their plasma membranes, on or in the nuclei, in the cytoplasm of Kupffer cells and, rarely, in the sinusoids. The accompanying tissue changes were hepatocellular degeneration and necrosis. These intra- and extracellular complexes of Au HAA and immunoglobulins displayed strong affinity for guinea pig complement in the immunohistochemical complement fixation reaction. When tested by immunodiffusion in agar, IgG dissociated from these complexes by potassium thiocyanate (KSCN) treatment showed anti-Au HAA specificity. In fulminant hepatitis neither Au HAA nor immunoglobulins and complement were found in the liver. In chronic aggressive hepatitis and subacute hepatitis the amount of the Au HAA immune complexes identified in the liver was approximately inversely proportional to the extent and severity of the parenchymal lesions. In liver cirrhosis and chronic persistent hepatitis there was a positive correlation between the amount of the Au HAA immune complexes found in the liver and the degree of hepatocellular damage. The deposits of Au HAA, identified in extrahepatic locations including germinal centers of lymph nodes and spleen, kidney glomeruli and blood vessel walls, were as a rule accompanied by deposits of IgG, IgM, β1C-globulin and fibrin. All these deposits showed strong affinity for guinea pig complement in the immunohistochemical reaction of complement fixation. Germinal center activation, chronic

  13. A prostate-specific antigen-dependent fusion polypeptide inhibits growth of prostate cancer cells in vitro and in vivo

    PubMed Central

    Zhang, Xiang; Ma, Yueyun; Wei, Hua; Li, Bin; Xiao, Fengjing; Yang, Jing; Yue, Qiaohong; Yang, Angang; Hao, Xiaoke

    2016-01-01

    Polypeptide APP8 is a prostate-specific antigen (PSA)-activated prodrug that was designed to synergize the effects of the Bcl-2 homology domain 3 (BH3) peptide, K237 and the DG2 peptide. The aim of this study is to evaluate its biodistribution and anticancer effect in vitro and in vivo. In this study, APP8 and each component peptide were synthesized. The biodistribution was identified using con-focal microscopyin both PSA+ cell line and PSA- cell line in vitro. Then cell cycle, MTT and in-cell western blot were accessed to analyze the effect mechanisms. Finally, xenografts were used to confirm the anticancer effect in vivo. Here, it was shown that APP8 was hydrolyzed and BH3 was released into the nucleus, while K237 and DG2 were located predominantly in the cytoplasm, only in LNCaP cells (PSA+), but not PC3 cells (PSA-). K237 and DG2 could induce cell apoptosis through decreasing the phosphorylation of ERK-2 and Flk-1. APP8 also caused the death of LNCaP cells, and was predominantly dependent on BH3 in vitro. In addition, It was noted that as the tumor grew in vivo, APP8 could inhibit the tumor volume to 77.3%, mainly depending on K237 and DG2 via inhibition of the growth of vascular endothelial cells. Our results suggested that APP8 could promote prostate cancer cell death and stop prostate cancer growth via synergizing apoptosis induction of tumor cell and inhibition of the growth of vascular endothelial cells. It provides a novel candidate prodrug for specific therapy of prostate cancer. PMID:27293998

  14. BRAF and MEK inhibition variably affect GD2-specific chimeric antigen receptor (CAR) T-cell function in vitro.

    PubMed

    Gargett, Tessa; Fraser, Cara K; Dotti, Gianpietro; Yvon, Eric S; Brown, Michael P

    2015-01-01

    Cancer immunotherapy has long been used in the treatment of metastatic melanoma, and an anti-CTLA-4 monoclonal antibody treatment has recently been approved by the US Food and Drug Administration. Targeted therapies such as small molecule kinase inhibitors targeting deregulated mitogen-activated protein kinase (MAPK) signaling have markedly improved melanoma control in up to 50% of metastatic disease patients and have likewise been recently approved. Combination therapies for melanoma have been proposed as a way to exploit the high-level but short-term responses associated with kinase inhibitor therapies and the low-level but longer-term responses associated with immunotherapy. Cancer immunotherapy now includes adoptive transfer of autologous tumor-specific chimeric antigen receptor (CAR) T cells and this mode of therapy is a candidate for combination with small molecule drugs. This paper describes CART cells that target GD2-expressing melanoma cells and investigates the effects of approved MAPK pathway-targeted therapies for melanoma [vemurafenib (Vem), dabrafenib (Dab), and trametinib (Tram)] on the viability, activation, proliferation, and cytotoxic T lymphocyte activity of these CAR T cells, as well as on normal peripheral blood mononuclear cells. We report that, although all these drugs lead to inhibition of stimulated T cells at high concentrations in vitro, only Vem inhibited T cells at concentrations equivalent to reported plasma concentrations in treated patients. Although the combination of Dab and Tram also resulted in inhibition of T-cell effector functions at some therapeutic concentrations, Dab itself had little adverse effect on CAR T-cell function. These findings may have implications for novel therapeutic combinations of adoptive CAR T-cell immunotherapy and MAPK pathway inhibitors. PMID:25415284

  15. Human hepatitis B viral e antigen and its precursor P20 inhibit T lymphocyte proliferation

    SciTech Connect

    Purvina, Maija; Hoste, Astrid; Rossignol, Jean-Michel; Lagaudriere-Gesbert, Cecile

    2012-01-27

    Highlights: Black-Right-Pointing-Pointer P20, precursor of the HBeAg, interacts with the cellular protein gC1qR. Black-Right-Pointing-Pointer HBeAg and P20 bind to T cell surface and inhibit mitogen-induced T cell division. Black-Right-Pointing-Pointer HBeAg and P20 inhibition of T cell proliferation is gC1qR and IL-1RAcP-independent. -- Abstract: The hepatitis B virus (HBV) Precore protein is processed through the secretory pathway directly as HBeAg or with the generation of an intermediate (P20). Precore gene has been shown to be implicated in viral persistence, but the functions of HBeAg and its precursors have not been fully elucidated. We show that the secreted proteins HBeAg and P20 interact with T cell surface and alter Kit-225 and primary T cells proliferation, a process which may facilitate the establishment of HBV persistence. Our data indicate that the N-terminal end of Precore is important for these inhibitory effects and exclude that they are dependent on the association of HBeAg and P20 with two characterized cell surface ligands, the Interleukin-1 Receptor Accessory Protein and gC1qR (present study).

  16. Chimeric antigen receptor T cells targeting HERV-K inhibit breast cancer and its metastasis through downregulation of Ras

    PubMed Central

    Zhou, Fuling; Krishnamurthy, Janani; Wei, Yongchang; Li, Ming; Hunt, Kelly; Johanning, Gary L; Cooper, Laurence JN; Wang-Johanning, Feng

    2015-01-01

    We have previously reported that human endogenous retrovirus-K (HERV-K) envelope (env) protein is a tumor-associated antigen (TAA) for cancer vaccines, and that its antibodies (mAbs) possess antitumor activity against cancer. In this study, a chimeric antigen receptor (CAR) specific for HERV-K env protein (K-CAR) was generated using anti-HERV-K mAb. K-CAR T cells from peripheral blood mononuclear cells (PBMCs) of 9 breast cancer (BC) patients and 12 normal donors were able to inhibit growth of, and to exhibit significant cytotoxicity toward, BC cells but not MCF-10A normal breast cells. The antitumor effects in cancer cells were significantly reduced when control T cells were used, or the expression of HERV-K was knocked down by an shRNA. Secretion of multiple cytokines, including IFNγ, TNF-α, and IL-2, was significantly enhanced in culture media of BC cells treated with K-CARs. Significantly reduced tumor growth and tumor weight was observed in xenograft models bearing MDA-MB-231 or MDA-MB-435.eB1 BC cells. Importantly, the K-CAR prevented tumor metastasis to other organs. Furthermore, downregulation of HERV-K expression in tumors of mice treated with K-CAR correlated with upregulation of p53 and downregulation of MDM2 and p-ERK. Importantly, the expression of HERV-K env protein in metastatic tumor tissues treated with K-CAR T cells correlated with the expression of Ras. Our results indicate that HERV-K env protein is an oncoprotein and may play an important role in tumorigenesis related to p53 and Ras signaling pathways. Anti-HERV-K treatment, including K-CAR treatment, shows potential for immunotherapy of BC. PMID:26451325

  17. Inhibition of Cullin-RING E3 ubiquitin ligase 7 by simian virus 40 large T antigen

    PubMed Central

    Hartmann, Thomas; Xu, Xinsong; Kronast, Mira; Muehlich, Susanne; Meyer, Kathleen; Zimmermann, Wolfgang; Hurwitz, Jerard; Pan, Zhen-Qiang; Engelhardt, Stefan; Sarikas, Antonio

    2014-01-01

    Simian virus 40 (SV40) large tumor antigen (LT) triggers oncogenic transformation by inhibition of key tumor suppressor proteins, including p53 and members of the retinoblastoma family. In addition, SV40 transformation requires binding of LT to Cullin 7 (CUL7), a core component of Cullin-RING E3 ubiquitin ligase 7 (CRL7). However, the pathomechanistic effects of LT–CUL7 interaction are mostly unknown. Here we report both in vitro and in vivo experimental evidence that SV40 LT suppresses the ubiquitin ligase function of CRL7. We show that SV40 LT, but not a CUL7 binding-deficient mutant (LTΔ69–83), impaired 26S proteasome-dependent proteolysis of the CRL7 target protein insulin receptor substrate 1 (IRS1), a component of the insulin and insulin-like growth factor 1 signaling pathway. SV40 LT expression resulted in the accumulation and prolonged half-life of IRS1. In vitro, purified SV40 LT reduced CRL7-dependent IRS1 ubiquitination in a concentration-dependent manner. Expression of SV40 LT, or depletion of CUL7 by RNA interference, resulted in the enhanced activation of IRS1 downstream signaling pathways phosphatidylinositol-3-kinase/AKT and Erk mitogen-activated pathway kinase, as well as up-regulation of the downstream target gene c-fos. Finally, SV40 LT-positive carcinoma of carcinoembryonic antigen 424/SV40 LT transgenic mice displayed elevated IRS1 protein levels and activation of downstream signaling. Taken together, these data suggest that SV40 LT protects IRS1 from CRL7-mediated degradation, thereby sustaining high levels of promitogenic IRS1 downstream signaling pathways. PMID:24550499

  18. Immunization with Immune Complexes Modulates the Fine Specificity of Antibody Responses to a Flavivirus Antigen

    PubMed Central

    Tsouchnikas, Georgios; Zlatkovic, Juergen; Jarmer, Johanna; Strauß, Judith; Vratskikh, Oksana; Kundi, Michael; Stiasny, Karin

    2015-01-01

    ABSTRACT The antibody response to proteins may be modulated by the presence of preexisting antigen-specific antibodies and the formation of immune complexes (ICs). Effects such as a general increase or decrease of the response as well as epitope-specific phenomena have been described. In this study, we investigated influences of IC immunization on the fine specificity of antibody responses in a structurally well-defined system, using the envelope (E) protein of tick-borne encephalitis (TBE) virus as an immunogen. TBE virus occurs in Europe and Asia and—together with the yellow fever, dengue, West Nile, and Japanese encephalitis viruses—represents one of the major human-pathogenic flaviviruses. Mice were immunized with a dimeric soluble form of E (sE) alone or in complex with monoclonal antibodies specific for each of the three domains of E, and the antibody response induced by these ICs was compared to that seen after immunization with sE alone. Immunoassays using recombinant domains and domain combinations of TBE virus sE as well as the distantly related West Nile virus sE allowed the dissection and quantification of antibody subsets present in postimmunization sera, thus generating fine-specificity patterns of the polyclonal responses. There were substantially different responses with two of the ICs, and the differences could be mechanistically related to (i) epitope shielding and (ii) antibody-mediated structural changes leading to dissociation of the sE dimer. The phenomena described may also be relevant for polyclonal responses upon secondary infections and/or booster immunizations and may affect antibody responses in an individual-specific way. IMPORTANCE Infections with flaviviruses such as yellow fever, dengue, Japanese encephalitis, West Nile, and tick-borne encephalitis (TBE) viruses pose substantial public health problems in different parts of the world. Antibodies to viral envelope protein E induced by natural infection or vaccination were shown to

  19. Suppressive effects of Schizandra chinensis Baillon water extract on allergy-related cytokine generation and degranulation in IgE-antigen complex-stimulated RBL-2H3 cells

    PubMed Central

    Chung, Mi Ja; Kim, Jeong-Mi; Lee, Sangchul; Kim, Taewoo; Kim, Daejung; Baek, Jongmi; Kim, Taehyuk; Lee, Jaesung; Kim, Kyoungkon; Yoon, Jin A

    2012-01-01

    Schizandra chinensis Baillon is a traditional folk medicine plant that is used to treat and prevent several inflammatory diseases and cancer in Korea, but the underlying mechanisms involved in its anti-allergic activity are not fully understood. This study was designed to investigate mechanisms of anti-allergic activity of a Schizandra chinensis Baillon water extract (SCWE) in immunoglobulin E (IgE)-antigen complex-stimulated RBL2H3 cells and to assess whether gastric and intestinal digestion affects the anti-allergic properties of SCWE. Oxidative stress is an important consequence of the allergic inflammatory response. The antioxidant activities of SCWE increased in a concentration-dependent manner. RBL-2H3 cells were sensitized with monoclonal anti-dinitrophenol (DNP) specific IgE, treated with SCWE, and challenged with the antigen DNP-human serum albumin. SCWE inhibited β-hexosaminidase release and expression of interleukin (IL)-4, IL-13, and tumor necrosis factor-alpha (TNF-α) mRNA and protein in IgE-antigen complex-stimulated RBL2H3 cells. We found that digested SCWE fully maintained its antioxidant activity and anti-allergic activity against the IgE-antigen complex-induced activation of RBL-2H3 cells. SCWE may be useful for preventing allergic diseases, such as asthma. Thus, SCWE could be used as a natural functional ingredient for allergic diseases in the food and/or pharmaceutical industries. PMID:22586497

  20. Characterization of nuclear targeting signal of hepatitis delta antigen: nuclear transport as a protein complex.

    PubMed Central

    Xia, Y P; Yeh, C T; Ou, J H; Lai, M M

    1992-01-01

    Hepatitis delta antigen (HDAg) is the only protein encoded by hepatitis delta virus (HDV). HDAg has been demonstrated in the nuclei of HDV-infected hepatocytes, and its nuclear transport may be important for the replication of HDV RNA. In this report, we investigated the mechanism of nuclear transport of HDAg. By expressing fusion proteins consisting of the different portions of HDAg and alpha-globin, we have identified a nuclear localization signal (NLS) within the N-terminal one-third of HDAg. It consists of two stretches of basic amino acid domains separated by a short run of nonbasic amino acids. Both of the basic domains are necessary for the efficient nuclear transport of HDAg. The nonbasic spacer amino acids could be removed without affecting the nuclear targeting of HDAg significantly. Thus, the HDAg NLS belongs to a newly identified class of NLS which consists of two discontiguous stretches of basic amino acids. This NLS is separated from a stretch of steroid receptor NLS-like sequence, which is also present but not functioning as an NLS, in HDAg. Furthermore, we have shown that subfragments of HDAg which do not contain the NLS can be passively transported into the nucleus by a trans-acting full-length HDAg, provided that these subfragments contain the region with a leucine zipper sequence. Thus, our results indicate that HDAg forms aggregates in the cytoplasm and that the HDAg oligomerization is probably mediated by the leucine zipper sequence. Therefore, HDAg is likely transported into the nucleus as a protein complex. Images PMID:1731113

  1. A miniaturized assay for influenza neuraminidase‐inhibiting antibodies utilizing reverse genetics‐derived antigens

    PubMed Central

    Sandbulte, Matthew R.; Gao, Jin; Straight, Timothy M.; Eichelberger, Maryna C.

    2009-01-01

    Background  Antibodies to neuraminidase (NA) contribute to protection during influenza virus infection, but NA inhibition (NI) titers are not routinely analyzed in vaccine trials. One reason is the cumbersome nature of the conventional thiobarbituric acid (TBA) NI assay, which uses chemical methods to quantify free sialic acid following incubation of NA with substrate in the presence of serum. In addition, the assay is complicated by the need to use virus of a hemagglutinin (HA) subtype novel to the host to detect NA‐specific antibodies only. Objectives  Our primary objectives were to miniaturize the colorimetric NI assay to a format suitable for quantitative analysis of large numbers of samples, and validate the specificity and sensitivity of the miniaturized format with ferret and human sera. An additional aim was to use reverse genetics to construct HA‐mismatched viral reagents bearing NA of recent influenza A vaccine strains and H6 HA. Results  Analysis of ferret antisera by the miniaturized assay demonstrated sensitivity and specificity comparable with the conventional assay. Similar increases in the NI titers in sera from vaccinated human volunteers were measured in miniaturized and conventional assays. Inactivated and live‐attenuated vaccines increased NI titers against a given subtype at approximately the same rate. Conclusions  The reagents and miniaturized format of the TBA method described here provide a platform for practical serological monitoring of functional antibodies against NA. PMID:21462400

  2. Small organic compounds enhance antigen loading of class II major histocompatibility complex proteins by targeting the polymorphic P1 pocket.

    PubMed

    Höpner, Sabine; Dickhaut, Katharina; Hofstätter, Maria; Krämer, Heiko; Rückerl, Dominik; Söderhäll, J Arvid; Gupta, Shashank; Marin-Esteban, Viviana; Kühne, Ronald; Freund, Christian; Jung, Günther; Falk, Kirsten; Rötzschke, Olaf

    2006-12-15

    Major histocompatibility complex (MHC) molecules are a key element of the cellular immune response. Encoded by the MHC they are a family of highly polymorphic peptide receptors presenting peptide antigens for the surveillance by T cells. We have shown that certain organic compounds can amplify immune responses by catalyzing the peptide loading of human class II MHC molecules HLA-DR. Here we show now that they achieve this by interacting with a defined binding site of the HLA-DR peptide receptor. Screening of a compound library revealed a set of adamantane derivatives that strongly accelerated the peptide loading rate. The effect was evident only for an allelic subset and strictly correlated with the presence of glycine at the dimorphic position beta86 of the HLA-DR molecule. The residue forms the floor of the conserved pocket P1, located in the peptide binding site of MHC molecule. Apparently, transient occupation of this pocket by the organic compound stabilizes the peptide-receptive conformation permitting rapid antigen loading. This interaction appeared restricted to the larger Gly(beta86) pocket and allowed striking enhancements of T cell responses for antigens presented by these "adamantyl-susceptible" MHC molecules. As catalysts of antigen loading, compounds targeting P1 may be useful molecular tools to amplify the immune response. The observation, however, that the ligand repertoire can be affected through polymorphic sites form the outside may also imply that environmental factors could induce allergic or autoimmune reactions in an allele-selective manner. PMID:17005558

  3. Sequestration of inhaled particulate antigens by lung phagocytes. A mechanism for the effective inhibition of pulmonary cell-mediated immunity.

    PubMed Central

    MacLean, J. A.; Xia, W.; Pinto, C. E.; Zhao, L.; Liu, H. W.; Kradin, R. L.

    1996-01-01

    Dendritic cells (DCs) have emerged as the dominant antigen-presenting cells (APCs) of the lung, playing a vital role in the induction of cell-mediated immunity to inhaled antigens. We have previously demonstrated that an airway challenge with the soluble antigen hen egg lysozyme yields rapid acquisition of specific antigen-presenting cell activity by purified pulmonary DCs and a cell-mediated immune response in the lung upon secondary challenge. To examine how a particulate antigen leads to a cell-mediated response in vivo, graded concentrations of heat-killed Listeria (HKL) were injected intratracheally into Lewis rats. The bacteria were rapidly ingested by lung macrophages and polymorphonuclear leukocytes. The ability of purified pulmonary DCs pulsed in vivo by an airway challenge with HKL to subsequently stimulate HKL-specific responses ex vivo showed a threshold response, requiring a dose in excess of 10(9) organisms/rat. By contrast, all dosages of HKL yielded specific sensitization of lymphocytes in the draining bilar nodes. Pulmonary DCs purified from rats after a secondary in vivo airway challenge with HKL at day 14 were ineffective antigen-presenting cells except at high dosages of antigen. The generation of cell-mediated pulmonary inflammation paralleled the antigen-presenting cell activity of pulmonary DCs and was observed only at high antigen dosages. Hen egg lysozyme immobilized onto polystyrene beads and injected intratracheally yielded comparable results to those observed with HKL. We suggest that a pulmonary cellular immune response is generated to an inhaled particulate antigen when the protective phagocytic capacities of the lung are exceeded and antigen is able to interact directly with interstitial DCs. The diversion of particulate antigens by pulmonary phagocytes may help to limit undesirable pulmonary inflammation while allowing the generation of antigen-specific immune lymphocytes in vivo. Images Figure 2 Figure 4 Figure 5 Figure 7 Figure 9

  4. [Use of cell-surface antigens of Bacteroides thetaiotaomicron in the passive hemagglutination test and in the inhibition of passive hemagglutination].

    PubMed

    Rokosz, A; Meisel-Mikołajczyk, F

    1995-01-01

    The antigens were prepared from three B. thetaiotaomicron strains of different origin (NCTC 10582--reference strain, 312/85--isolated from a pancreas fistula drain of a patient, and 9/18--derived from normal human intestinal microflora). Lipopolysaccharides were extracted by the hot phenol-water method and purified by nuclease tretment. Degradation of lipopolysaccharides was achieved by mild acid hydrolysis obtaining polysaccharide (PS) and lipid (LA) fractions. Capsular polysaccharide (CPS) was extracted from the clinical strain 312/85 producing thick capsules. Antibacterial sera were prepared by immunization of rabbits with formolized suspensions of investigated strains. HA and IHA were performed with all antigens and immune sera. Examined cell-surface antigens (LPSs and CPS) were capable of coating formolized sheep erythrocytes. The titres obtained in the passive hemagglutination test in homologous reactions were 160-320. Polysaccharide fractions (PS) prepared by means of mild acid hydrolysis of LPSs were unable to coat formolized sheep red blood cells. The activity of sensitization of sheep erythrocytes was revealed by lipid fractions of LPSs. All preparations were active as inhibitors in the inhibition of passive hemagglutination. The strongest inhibitors in homologous systems were polysaccharide fractions of LPSs and capsular polysaccharide (the concentration of inhuibitor 8-15 micrograms/ml). The results of performed serological tests indicated the antigenic similarity of standard B. thetaiotaomicron strain NCTC 10582 and clinical strain 312/85. The strain 9/18 from normal human intestinal microflora showed distinct antigenicity. High-molecular cell-surface B. thetaiotaomicron antigens containing carbohydrates (LPS and CPS) can be applied in the passive hemagglutination test and in the inhibition of passive hemagglutination. PMID:8833931

  5. Synthesis of a peptide-universal nucleotide antigen: towards next-generation antibodies to detect topoisomerase I-DNA covalent complexes.

    PubMed

    Perkins, Angela L; Peterson, Kevin L; Beito, Thomas G; Flatten, Karen S; Kaufmann, Scott H; Harki, Daniel A

    2016-04-26

    The topoisomerase (topo) I-DNA covalent complex represents an attractive target for developing diagnostic antibodies to measure responsiveness to drugs. We report a new antigen, peptide , and four murine monoclonal antibodies raised against that exhibit excellent specificity for recognition of in comparison to structurally similar peptides by enzyme-linked immunosorbent assays. Although topo I-DNA complex detection was not achieved in cellular samples by these new antibodies, a new strategy for antigen design is reported. PMID:27113574

  6. The pathogenesis of arthritis associated with acute hepatitis-B surface antigen-positive hepatitis. Complement activation and characterization of circulating immune complexes.

    PubMed Central

    Wands, J R; Mann, E; Alpert, E; Isselbacher, K J

    1975-01-01

    Circulating immune complexes were identified in cryoproteins isolated from serial samples of serum from six patients with acute viral hepatitis with and without arthritic symptoms. Cryoprecipitates were analyzed for the presence of hepatitis-B surface antigen (HBsAg) and hepatitis-B surface antibody (anti-HBs) by hemagglutination inhibition and hemagglutination. Complement components were detected by counter electrophoresis, and immunoglobulins were detected by gel diffusion. HBsAg, IgG, and IgM were identified in cryoprecipitates from all hepatitis patients, but were higher in concentration in patients with arthritis. Only cryoprecipitates from hepatitis patients with arthritis contained IgA and complement components C3, C4, and C5 as well as IgG and IgM, which disappear with resolution of the arthritis. The subtypes of IgG in these cryoprecipitates were predominantly the complement-fixing IgG1 and IgG3, HBsAg and anti-HBs were concentrated several-fold in the cryoprecipitates when compared to the serum concentration. Sequential studies in two patients demonstrated that the initial appearance of anti-HBs in the cryoprotein complex was associated with the detection in the complex of IgM suggesting a primary immune response to HBsAg. The C3 activator fragment (C3A) of the properdin complex was found in fresh serum obtained from three hepatitis patients with arthritis and not in uncomplicated hepatitis. The cryoprecipitable immune complexes from patients with arthritis converted C3PA in fresh normal sera to C3A in vitro whereas cryoprotein isolated from patients with uncomplicated hepatitis had no such effect. Thus, the transient appearance of circulating complement-fixing immune complexes in patients with the arthritis of acute hepatitis is associated with activation of both classical and alternate complement pathways and suggests that they play an important role in the pathogenesis of these serum sickness-like extrahepatic symptoms. Images PMID:1123429

  7. Inhibition of the HCV core protein on the immune response to HBV surface antigen and on HBV gene expression and replication in vivo.

    PubMed

    Zhu, Wenbo; Wu, Chunchen; Deng, Wanyu; Pei, Rongjun; Wang, Yun; Cao, Liang; Qin, Bo; Lu, Mengji; Chen, Xinwen

    2012-01-01

    The hepatitis C virus (HCV) core protein is a multifunctional protein that can interfere with the induction of an immune response. It has been reported that the HCV core protein inhibits HBV replication in vitro. In this study, we test the effect of the HCV core gene on the priming of the immune response to hepatitis B surface antigen (HBsAg) and on the replication of HBV in vivo. Our results showed that the full-length HCV core gene inhibits the induction of an immune response to the heterogeneous antigen, HBsAg, at the site of inoculation when HCV core (pC191) and HBsAg (pHBsAg) expression plasmids are co-administered as DNA vaccines into BALB/c mice. The observed interference effect of the HCV core occurs in the priming stage and is limited to the DNA form of the HBsAg antigen, but not to the protein form. The HCV core reduces the protective effect of the HBsAg when the HBsAg and the HCV core are co-administered as vaccines in an HBV hydrodynamic mouse model because the HCV core induces immune tolerance to the heterogeneous HBsAg DNA antigen. These results suggest that HCV core may play an important role in viral persistence by the attenuation of host immune responses to different antigens. We further tested whether the HCV core interfered with the priming of the immune response in hepatocytes via the hydrodynamic co-injection of an HBV replication-competent plasmid and an HCV core plasmid. The HCV core inhibited HBV replication and antigen expression in both BALB/c (H-2d) and C57BL/6 (H-2b) mice, the mouse models of acute and chronic hepatitis B virus infections. Thus, the HCV core inhibits the induction of a specific immune response to an HBsAg DNA vaccine. However, HCV C also interferes with HBV gene expression and replication in vivo, as observed in patients with coinfection. PMID:23024803

  8. Resveratrol Suppresses Cytokine Production Linked to FcεRI-MAPK Activation in IgE-Antigen Complex-Exposed Basophilic Mast Cells and Mice.

    PubMed

    Han, Seon-Young; Choi, Yean-Jung; Kang, Min-Kyung; Park, Jung Han Yoon; Kang, Young-Hee

    2015-01-01

    A complicated interplay between resident mast cells and other recruited inflammatory cells contributes to the development and progression of allergic inflammation entailing the promotion of T helper 2 (Th2) cytokine responses. The current study examined whether resveratrol suppressed the production of inflammatory Th2 cytokines in cultured rat basophilic leukemia RBL-2H3 cells. Cells pre-treated with resveratrol nontoxic at 1–25 μM were sensitized with anti-dinitrophenyl (anti-DNP), and subsequently stimulated by dinitrophenyl-human serum albumin (DNP–HSA) antigen. Resveratrol dose-dependently diminished the secretion of interleukin (IL)-3, IL-4, IL-13 as well as tumor necrosis factor (TNF)-α by the antigen stimulation from sensitized cells. It was found that resveratrol mitigated the phosphorylation of p38 MAPK, ERK, and JNK elevated in mast cells exposed to Fc epsilon receptor I (FcεRI)-mediated immunoglobulin E (IgE)-antigen complex. The FcεRI aggregation was highly enhanced on the surface of mast cells following the HSA stimulation, which was retarded by treatment with 1–25 μM resveratrol. The IgE-receptor engagement rapidly induced tyrosine phosphorylation of c-Src-related focal adhesion protein paxillin involved in the cytoskeleton rearrangement. The FcεRI-mediated rapid activation of c-Src and paxillin was attenuated in a dose-dependent manner. In addition, the paxillin activation entailed p38 MAPK and ERK-responsive signaling, but the JNK activation was less involved. Consistently, oral administration of resveratrol reduced the tissue level of phosphorylated paxillin in the dorsal skin of DNP–HSA-challenged mice. The other tyrosine kinase Tyk2-STAT1 signaling was activated in the dorsal epidermis of antigen-exposed mice, which was associated with allergic inflammation. These results showed that resveratrol inhibited Th2 cytokines- and paxillin-linked allergic responses dependent upon MAPK signaling. Therefore, resveratrol may possess the

  9. Hsp90-peptide complexes stimulate antigen presentation through the class II pathway after binding scavenger receptor SREC-I

    PubMed Central

    Murshid, Ayesha; Gong, Jianlin; Calderwood, Stuart K

    2016-01-01

    Molecular chaperones such as heat shock protein 90 (Hsp90) have been shown to form complexes with tumor antigens and can be used to prepare anticancer vaccines largely due to this property. Earlier studies had suggested that, mice immunized with a molecular chaperone based vaccine derived from tumors became immune to further vaccination and that both CD8+ and CD4+ T cells were activated by the chaperone vaccine in a manner dependent on scavenger receptor SREC-I. Here we have investigated mechanisms whereby SREC-I might facilitate uptake of Hsp90 conjugated peptides by APC into the MHC class II pathway for presentation to CD4+ T cells. Our studies showed that antigenic peptides associated with Hsp90 were taken up into the Class II pathway by a mechanism dependent on SREC-I binding and internalization and presented to CD4+ T cells. In addition our studies showed that SREC-I could associate with MHC class II molecules on the cell surface and in intracellular endosomes, suggesting a mechanism involving facilitated uptake of peptides into the MHC class II pathway. These studies in addition to our earlier findings showed SREC-I to play a primary role in chaperone-associated antigen uptake both through cross priming of MHC class I molecules and entry into the class II pathway. PMID:25155057

  10. Stoichiometric complex formation by proliferating cell nuclear antigen (PCNA) and its interacting protein: purification and crystallization of the DNA polymerase and PCNA monomer mutant complex from Pyrococcus furiosus

    SciTech Connect

    Nishida, Hirokazu; Matsumiya, Shigeki; Tsuchiya, Daisuke; Ishino, Yoshizumi; Morikawa, Kosuke

    2006-03-01

    A stable stoichiometric complex of archaeal DNA polymerase with proliferating cell nuclear antigen (PCNA) was formed using a PCNA monomer mutant and the complex was successfully crystallized. Replicative DNA polymerase interacts with processivity factors, the β-subunit of DNA polymerase III or proliferating cell nuclear antigen (PCNA), in order to function with a long template DNA. The archaeal replicative DNA polymerase from Pyrococcus furiosus interacts with PCNA via its PCNA-interacting protein (PIP) motif at the C-terminus. The PCNA homotrimeric ring contains one PIP interacting site on each monomer and since the ring can accommodate up to three molecules simultaneously, formation of a stable stoichiometric complex of PCNA with its interacting protein has been difficult to control in vitro. A stable complex of the DNA polymerase with PCNA, using a PCNA monomer mutant, has been purified and crystallized. The best ordered crystal diffracted to 3.0 Å resolution using synchrotron radiation. The crystals belong to space group P2{sub 1}2{sub 1}2, with unit-cell parameters a = 225.3, b = 123.3, c = 91.3 Å.

  11. Enriched HLA-DQ3 phenotype and decreased class I major histocompatibility complex antigen expression in recurrent respiratory papillomatosis.

    PubMed Central

    Bonagura, V R; Siegal, F P; Abramson, A L; Santiago-Schwarz, F; O'Reilly, M E; Shah, K; Drake, D; Steinberg, B M

    1994-01-01

    Respiratory papillomas, caused by human papillomaviruses, are benign tumors that recur following removal. We evaluated immune function and major histocompatibility complex (MHC) phenotype and expression in these patients. MHC-independent immune function appeared normal. The frequency of peripheral blood MHC class II phenotypes was highly enriched for DQ3 and DR11, one split of DR5. Class I MHC antigen expression on papilloma tissue was markedly reduced. Together, these phenomena may facilitate papillomavirus evasion of the cellular immune response. Images PMID:7496977

  12. Preparation and diagnostic utility of a hemagglutination inhibition test antigen derived from the baculovirus-expressed hemagglutinin-neuraminidase protein gene of Newcastle disease virus.

    PubMed

    Choi, Kang-Seuk; Kye, Soo-Jeong; Jeon, Woo-Jin; Park, Mi-Ja; Kim, Saeromi; Seul, Hee-Jung; Kwon, Jun-Hun

    2013-01-01

    A recombinant hemagglutinin-neuraminidase (rHN) protein from Newcastle disease virus (NDV) with hemagglutination (HA) activity was expressed in Spodoptera frugiperda cells using a baculovirus expression system. The rHN protein extracted from infected cells was used as an antigen in a hemagglutination inhibition (HI) test for the detection and titration of NDV-specific antibodies present in chicken sera. The rHN antigen produced high HA titers of 2(13) per 25 μL, which were similar to those of the NDV antigen produced using chicken eggs, and it remained stable without significant loss of the HA activity for at least 12 weeks at 4°C. The rHN-based HI assay specifically detected NDV antibodies, but not the sera of other avian pathogens, with a specificity and sensitivity of 100% and 98.0%, respectively, in known positive and negative chicken sera (n = 430). Compared with an NDV-based HI assay, the rHN-based HI assay had a relative sensitivity and specificity of 96.1% and 95.5%, respectively, when applied to field chicken sera. The HI titers of the rHN-based HI assay were highly correlated with those in an NDV-based HI assay (r = 0.927). Overall, these results indicate that rHN protein provides a useful alternative to NDV antigen in HI assays. PMID:23820164

  13. Immunostimulatory complexes containing Eimeria tenella antigens and low toxicity plant saponins induce antibody response and provide protection from challenge in broiler chickens.

    PubMed

    Berezin, V E; Bogoyavlenskyi, A P; Khudiakova, S S; Alexuk, P G; Omirtaeva, E S; Zaitceva, I A; Tustikbaeva, G B; Barfield, R C; Fetterer, R H

    2010-01-20

    Immunostimulating complexes (ISCOMs) are unique multimolecular structures formed by encapsulating antigens, lipids and triterpene saponins and are one of the most successful antigen delivery systems for microbial antigens. In the current study, both the route of administration and the antigen concentration of ISCOMs, containing Eimeria tenella antigens and saponins from native plants, were evaluated in their ability to stimulate humoral immunity and to protect chickens against a challenge infection with E. tenella. Broiler chickens were immunized with ISCOM preparations containing E. tenella antigens and the purified saponins Gg6, Ah6 and Gp7 isolated from Glycyrrhiza glabra, Aesculus hippocastanum and Gipsophila paniculata, respectively. The effects of the route of administration, dose of antigen and type of saponin used for construction of ISCOMs were evaluated for ability to stimulate serum IgG and IgM and to protect chickens against a homologous challenge. A single intranasal immunization was the most effective route for administering ISCOMs although the in ovo route was also quite effective. Dose titration experiments demonstrated efficacy after single immunization with various ISCOM doses but maximum effects were observed when ISCOMs contain 5-10mug antigen. Immunization of birds by any of the three routes with E. tenella antigens alone or antigens mixed with alum hydroxide adjuvant resulted in lower serum antibody and reduced protection to challenge relative to immunization with ISCOMs. Overall the results of this study confirm that significant immunostimulation and protection to challenge are achieved by immunization of chickens with ISCOMs containing purified saponins and native E. tenella antigens and suggest that ISCOMs may be successfully used to develop a safe and effective vaccine for prevention of avian coccidiosis. PMID:19879050

  14. Aptamer-targeted Antigen Delivery

    PubMed Central

    Wengerter, Brian C; Katakowski, Joseph A; Rosenberg, Jacob M; Park, Chae Gyu; Almo, Steven C; Palliser, Deborah; Levy, Matthew

    2014-01-01

    Effective therapeutic vaccines often require activation of T cell-mediated immunity. Robust T cell activation, including CD8 T cell responses, can be achieved using antibodies or antibody fragments to direct antigens of interest to professional antigen presenting cells. This approach represents an important advance in enhancing vaccine efficacy. Nucleic acid aptamers present a promising alternative to protein-based targeting approaches. We have selected aptamers that specifically bind the murine receptor, DEC205, a C-type lectin expressed predominantly on the surface of CD8α+ dendritic cells (DCs) that has been shown to be efficient at facilitating antigen crosspresentation and subsequent CD8+ T cell activation. Using a minimized aptamer conjugated to the model antigen ovalbumin (OVA), DEC205-targeted antigen crosspresentation was verified in vitro and in vivo by proliferation and cytokine production by primary murine CD8+ T cells expressing a T cell receptor specific for the major histocompatibility complex (MHC) I-restricted OVA257–264 peptide SIINFEKL. Compared with a nonspecific ribonucleic acid (RNA) of similar length, DEC205 aptamer-OVA-mediated antigen delivery stimulated strong proliferation and production of interferon (IFN)-γ and interleukin (IL)-2. The immune responses elicited by aptamer-OVA conjugates were sufficient to inhibit the growth of established OVA-expressing B16 tumor cells. Our results demonstrate a new application of aptamer technology for the development of effective T cell-mediated vaccines. PMID:24682172

  15. Antigen nature and complexity influence human antibody light chain usage and specificity.

    PubMed

    Smith, Kenneth; Shah, Hemangi; Muther, Jennifer J; Duke, Angie L; Haley, Kathleen; James, Judith A

    2016-05-27

    Human antibodies consist of a heavy chain and one of two possible light chains, kappa (κ) or lambda (λ). Here we tested how these two possible light chains influence the overall antibody response to polysaccharide and protein antigens by measuring light chain usage in human monoclonal antibodies from antibody secreting cells obtained following vaccination with Pneumovax23. Remarkably, we found that individuals displayed restricted light chain usage to certain serotypes and that lambda antibodies have different specificities and modes of cross-reactivity than kappa antibodies. Thus, at both the monoclonal (7 kappa, no lambda) and serum levels (145μg/mL kappa, 2.82μg/mL lambda), antibodies to cell wall polysaccharide were nearly always kappa. The pneumococcal reference serum 007sp was analyzed for light chain usage to 12 pneumococcal serotypes for which it is well characterized. Similar to results at the monoclonal level, certain serotypes tended to favor one of the light chains (14 and 19A, lambda; 6A and 23F, kappa). We also explored differences in light chain usage at the serum level to a variety of antigens. We examined serum antibodies to diphtheria toxin mutant CRM197 and Epstein-Barr virus protein EBNA-1. These responses tended to be kappa dominant (average kappa-to-lambda ratios of 4.52 and 9.72 respectively). Responses to the influenza vaccine were more balanced with kappa-to-lambda ratio averages having slight strain variations: seasonal H1N1, 1.1; H3N2, 0.96; B, 0.91. We conclude that antigens with limited epitopes tend to produce antibodies with restricted light chain usage and that in most individuals, antibodies with lambda light chains have specificities different and complementary to kappa-containing antibodies. PMID:27113164

  16. Aguacate virus, a new antigenic complex of the genus Phlebovirus (family Bunyaviridae)

    PubMed Central

    Travassos da Rosa, Amelia; Savji, Nazir; Sze, Wilson; Wick, Ivan; Guzman, Hilda; Hutchison, Stephen; Tesh, Robert; Lipkin, W. Ian

    2011-01-01

    Genomic and antigenic characterization of Aguacate virus, a tentative species of the genus Phlebovirus, and three other unclassified viruses, Armero virus, Durania virus and Ixcanal virus, demonstrate a close relationship to one another. They are distinct from the other nine recognized species within the genus Phlebovirus. We propose to designate them as a new (tenth) serogroup or species (Aguacate virus) within the genus. The four viruses were all isolated from phlebotomine sandflies (Lutzomyia sp.) collected in Central and South America. Aguacate virus appears to be a natural reassortant and serves as one more example of the high frequency of reassortment in this genus. PMID:21325481

  17. Aguacate virus, a new antigenic complex of the genus Phlebovirus (family Bunyaviridae).

    PubMed

    Palacios, Gustavo; da Rosa, Amelia Travassos; Savji, Nazir; Sze, Wilson; Wick, Ivan; Guzman, Hilda; Hutchison, Stephen; Tesh, Robert; Lipkin, W Ian

    2011-06-01

    Genomic and antigenic characterization of Aguacate virus, a tentative species of the genus Phlebovirus, and three other unclassified viruses, Armero virus, Durania virus and Ixcanal virus, demonstrate a close relationship to one another. They are distinct from the other nine recognized species within the genus Phlebovirus. We propose to designate them as a new (tenth) serogroup or species (Aguacate virus) within the genus. The four viruses were all isolated from phlebotomine sandflies (Lutzomyia sp.) collected in Central and South America. Aguacate virus appears to be a natural reassortant and serves as one more example of the high frequency of reassortment in this genus. PMID:21325481

  18. Identification of interface residues in protease-inhibitor and antigen-antibody complexes: a support vector machine approach

    PubMed Central

    Honavar, Vasant; Dobbs, Drena

    2010-01-01

    In this paper, we describe a machine learning approach for sequence-based prediction of protein-protein interaction sites. A support vector machine (SVM) classifier was trained to predict whether or not a surface residue is an interface residue (i.e., is located in the protein-protein interaction surface), based on the identity of the target residue and its ten sequence neighbors. Separate classifiers were trained on proteins from two categories of complexes, antibody-antigen and protease-inhibitor. The effectiveness of each classifier was evaluated using leave-one-out (jack-knife) cross-validation. Interface and non-interface residues were classified with relatively high sensitivity (82.3% and 78.5%) and specificity (81.0% and 77.6%) for proteins in the antigen-antibody and protease-inhibitor complexes, respectively. The correlation between predicted and actual labels was 0.430 and 0.462, indicating that the method performs substantially better than chance (zero correlation). Combined with recently developed methods for identification of surface residues from sequence information, this offers a promising approach to predict residues involved in protein-protein interactions from sequence information alone. PMID:20526429

  19. Immune-stimulating complexes as adjuvants for inducing local and systemic immunity after oral immunization with protein antigens.

    PubMed Central

    Mowat, A M; Maloy, K J; Donachie, A M

    1993-01-01

    Orally active synthetic vaccines containing purified antigens would have many benefits for immunizing against systemic and mucosal diseases. However, several factors have limited the development of such vaccines, including the poor immunogenicity of purified proteins and their usual ability to induce tolerance when given orally. Here, we show that incorporation of ovalbumin (OVA) into immune-stimulating complexes (ISCOMS) containing saponin prevents the induction of oral tolerance in mice. In parallel, the spleen and mesenteric lymph node of mice fed OVA ISCOMS are primed for class I major histocompatibility complex (MHC)-restricted cytotoxic T-cell activity which recognizes physiologically processed epitopes on OVA. Oral immunization with OVA ISCOMS also stimulates high secretory IgA antibody responses in the intestine itself, as well as serum IgG antibodies. None of these active immune responses are detectable in mice fed OVA alone. Despite the potent priming of mucosal priming by OVA ISCOMS, re-exposure to antigen does not induce the intestinal immunopathology found in other systems after the breakdown of oral tolerance. Thus, ISCOMS have several unique properties as vectors for oral immunization and could provide a basis for future mucosal vaccines. PMID:7508416

  20. Structure of a Major Antigenic Site on the Respiratory Syncytial Virus Fusion Glycoprotein in Complex with Neutralizing Antibody 101F

    SciTech Connect

    McLellan, Jason S.; Chen, Man; Chang, Jung-San; Yang, Yongping; Kim, Albert; Graham, Barney S.; Kwong, Peter D.

    2010-11-19

    Respiratory syncytial virus (RSV) is a major cause of pneumonia and bronchiolitis in infants and elderly people. Currently there is no effective vaccine against RSV, but passive prophylaxis with neutralizing antibodies reduces hospitalizations. To investigate the mechanism of antibody-mediated RSV neutralization, we undertook structure-function studies of monoclonal antibody 101F, which binds a linear epitope in the RSV fusion glycoprotein. Crystal structures of the 101F antigen-binding fragment in complex with peptides from the fusion glycoprotein defined both the extent of the linear epitope and the interactions of residues that are mutated in antibody escape variants. The structure allowed for modeling of 101F in complex with trimers of the fusion glycoprotein, and the resulting models suggested that 101F may contact additional surfaces located outside the linear epitope. This hypothesis was supported by surface plasmon resonance experiments that demonstrated 101F bound the peptide epitope {approx}16,000-fold more weakly than the fusion glycoprotein. The modeling also showed no substantial clashes between 101F and the fusion glycoprotein in either the pre- or postfusion state, and cell-based assays indicated that 101F neutralization was not associated with blocking virus attachment. Collectively, these results provide a structural basis for RSV neutralization by antibodies that target a major antigenic site on the fusion glycoprotein.

  1. Loss of T Cell Antigen Recognition Arising from Changes in Peptide and Major Histocompatibility Complex Protein Flexibility: Implications for Vaccine Design

    SciTech Connect

    Insaidoo, Francis K.; Borbulevych, Oleg Y.; Hossain, Moushumi; Santhanagopolan, Sujatha M.; Baxter, Tiffany K.; Baker, Brian M.

    2012-05-08

    Modification of the primary anchor positions of antigenic peptides to improve binding to major histocompatibility complex (MHC) proteins is a commonly used strategy for engineering peptide-based vaccine candidates. However, such peptide modifications do not always improve antigenicity, complicating efforts to design effective vaccines for cancer and infectious disease. Here we investigated the MART-1{sub 27-35} tumor antigen, for which anchor modification (replacement of the position two alanine with leucine) dramatically reduces or ablates antigenicity with a wide range of T cell clones despite significantly improving peptide binding to MHC. We found that anchor modification in the MART-1{sub 27-35} antigen enhances the flexibility of both the peptide and the HLA-A*0201 molecule. Although the resulting entropic effects contribute to the improved binding of the peptide to MHC, they also negatively impact T cell receptor binding to the peptide {center_dot} MHC complex. These results help explain how the 'anchor-fixing' strategy fails to improve antigenicity in this case, and more generally, may be relevant for understanding the high specificity characteristic of the T cell repertoire. In addition to impacting vaccine design, modulation of peptide and MHC flexibility through changes to antigenic peptides may present an evolutionary strategy for the escape of pathogens from immune destruction.

  2. Identification of an elaborate complex mediating postsynaptic inhibition.

    PubMed

    Uezu, Akiyoshi; Kanak, Daniel J; Bradshaw, Tyler W A; Soderblom, Erik J; Catavero, Christina M; Burette, Alain C; Weinberg, Richard J; Soderling, Scott H

    2016-09-01

    Inhibitory synapses dampen neuronal activity through postsynaptic hyperpolarization. The composition of the inhibitory postsynapse and the mechanistic basis of its regulation, however, remain poorly understood. We used an in vivo chemico-genetic proximity-labeling approach to discover inhibitory postsynaptic proteins. Quantitative mass spectrometry not only recapitulated known inhibitory postsynaptic proteins but also revealed a large network of new proteins, many of which are either implicated in neurodevelopmental disorders or are of unknown function. Clustered regularly interspaced short palindromic repeats (CRISPR) depletion of one of these previously uncharacterized proteins, InSyn1, led to decreased postsynaptic inhibitory sites, reduced the frequency of miniature inhibitory currents, and increased excitability in the hippocampus. Our findings uncover a rich and functionally diverse assemblage of previously unknown proteins that regulate postsynaptic inhibition and might contribute to developmental brain disorders. PMID:27609886

  3. [Complexation between triterpene glycosides of holothurians and cholesterol is the basis of lipid-saponin carriers of subunit protein antigens].

    PubMed

    Mazeĭka, A N; Popov, A M; Kalinin, V I; Avilov, S A; Sil'chenko, A S; Kostetskiĭ, E Ia

    2008-01-01

    The ability of some triterpene glycosides of holothurians: cucumarioside A2-2 from Cucumaria japonica, cucumarioside G1 from Cucumaria fraudatrix, frondoside A from Cucumaria frondosa, and holotoxin A1 from A postichopus japonicus to form lipid-saponin supramolecular complexes was studied. The formation of supramolecular cholesterol-glycosides complexes between cholesterol and these glycosides in water medium was observed by transmission electron microscopy. These complexes were considered as nanoparticles with different structure. Complexes formed by cholesterol with cucumarioside A2-2, holotoxin A1, and frondoside A are tubular nanoparticles. In contrast, complexes between cholesterol and cucumarioside G1 have different structured. The structure of nanoparticles formed in the presence of cucumarioside A2-2, holotoxin A1, and cucumarioside G1 was dependent on the ratio of cholesterol in the lipid-saponin system. On the other hand, frondoside A did not shown this tendency. In lipid-saponin systems with a similar molar ratio cholesterol-glycoside, the ordering of the supramolecular structure decreases in the following order: cucumarioside A2-2, holotoxin A1, frondoside A. A comparative analysis of the morphology of the supramolecular complexes and the peculiarities of the molecular structure of triterpene glycosides studied, demonstrated that the structure of supramolecular complexes formed depends on the branching and length of the glycoside carbohydrate chain. On the other hand, the formation of monomeric cholesterol-glycosides complexes depends on the peculiarities of the structure of aglycone. Thus, the possibility of the formation of a new type of antigen carries on the basis of marine triterpene glycosides was proved. PMID:18954012

  4. TAR RNA decoys inhibit tat-activated HIV-1 transcription after preinitiation complex formation.

    PubMed Central

    Bohjanen, P R; Liu, Y; Garcia-Blanco, M A

    1997-01-01

    The ability of the HIV-1 Tat protein to trans -activate HIV-1 transcription in vitro is specifically inhibited by a circular TAR RNA decoy. This inhibition is not overcome by adding an excess of Tat to the reaction but is partially overcome by adding Tat in combination with nuclear extract, suggesting that TAR RNA might function by interacting with a complex containing Tat and cellular factor(s). A cell-free transcription system involving immobilized DNA templates was used to further define the factor(s) that interact with TAR RNA. Preinitiation complexes formed in the presence or absence of Tat were purified on immobilized templates containing the HIV-1 promoter. After washing, nucleotides and radiolabelled UTP were added and transcription was measured. The presence of Tat during preinitiation complex formation resulted in an increase in the level of full-length HIV-1 transcripts. This Tat-activated increase in HIV-1 transcription was not inhibited by circular TAR decoys added during preinitiation complex formation but was inhibited by circular TAR decoys subsequently added during the transcription reaction. These results suggest that TAR decoys inhibit Tat-activated HIV-1 transcription after preinitiation complex formation, perhaps by interacting with components of transcription complexes. PMID:9358155

  5. Inhibition of antigen receptor-dependent Ca(2+) signals and NF-AT activation by P2X7 receptors in human B lymphocytes.

    PubMed

    Pippel, Anja; Beßler, Björn; Klapperstück, Manuela; Markwardt, Fritz

    2015-04-01

    One of the first intracellular signals after antigen binding by the antigen receptor of B lymphocytes is the increased intracellular Ca(2+) concentration ([Ca(2+)]i), which is followed by several intracellular signaling events like the nuclear translocation of the transcription factor NF-AT controlling the fate of B lymphocytes after their activation. Extracellular ATP, which is released from cells under several pathological conditions, is considered a danger-associated signal serving as an immunomodulator. We investigated the interaction of antigen receptor (BCR) and P2X7 receptor (P2X7R) activation on [Ca(2+)]i signaling and on nuclear translocation of the transcription factor NF-AT in human B lymphocytes. Although the P2X7R is an ATP-gated Ca(2+)-permeable ion channel, P2X7R activation inhibits the BCR-mediated [Ca(2+)]i responses. This effect is mimicked by cell membrane depolarization induced by an increase in the extracellular K(+) concentration or by application of the Na(+) ionophore gramicidin, but is abolished by stabilization of the membrane potential using the K(+) ionophore valinomycin, by extracellular Mg(2+), which is known to inhibit P2X7R-dependent effects, or by replacing Na(+) by the less P2X7R-permeable Tris(+) ion. Furthermore, P2X7R activation by ATP inhibits the BCR-dependent translocation of the transcription factor NF-ATc1 to the nucleus. We therefore conclude that extracellular ATP via the P2X7R mediates inhibitory effects on B cell activation. This may be of relevance for understanding of the activation of the BCR under pathological conditions and for the development of therapeutic strategies targeting human B lymphocytes or P2X7 receptors. PMID:25678443

  6. TCRβ Feedback Signals Inhibit the Coupling of Recombinationally Accessible Vβ14 Segments with DJβ Complexes

    PubMed Central

    Yang-Iott, Katherine S.; Carpenter, Andrea C.; Rowh, Marta A. W.; Steinel, Natalie; Brady, Brenna L.; Hochedlinger, Konrad; Jaenisch, Rudolf; Bassing, Craig H.

    2010-01-01

    Antigen receptor allelic exclusion is thought to occur through mono-allelic initiation and subsequent feedback inhibition of recombinational accessibility. However, our previous analysis of mice containing a V(D)J recombination reporter inserted into Vβ14 (Vβ14Rep) indicated that Vβ14 chromatin accessibility is bi-allelic. To determine whether Vβ14 recombinational accessibility is subject to feedback inhibition, we analyzed TCRβ rearrangements in Vβ14Rep mice containing a pre-assembled in frame transgenic Vβ8.2Dβ1Jβ1.1 or an endogenous Vβ14Dβ1Jβ1.4 rearrangement on the homologous chromosome. Expression of either pre-assembled VβDJβCβ chain accelerated thymocyte development due to enhanced cellular selection, demonstrating that the rate-limiting step in early αβ T cell development is the assembly of an in-frame VβDJβ rearrangement. Expression of these pre-assembled VβDJβ rearrangements inhibited endogenous Vβ14-to-DJβ rearrangements as expected. However, in contrast to results predicted by the accepted model of TCRβ feedback inhibition, we found that expression of these pre-assembled TCRβ chains did not down-regulate recombinational accessibility of Vβ14 chromatin. Our findings suggest that TCRβ mediated feedback inhibition of Vβ14 rearrangements depends upon inherent properties of Vβ14, Dβ, and Jβ recombination signal sequences. PMID:20042591

  7. Major histocompatibility complex class II (DR) antigen and costimulatory molecules on in vitro and in vivo activated human polymorphonuclear neutrophils

    PubMed Central

    Sandilands, Gavin P; McCrae, Jame; Hill, Kathryn; Perry, Martin; Baxter, Derek

    2006-01-01

    We have previously shown that normal human peripheral blood polymorphonuclear neutrophils (PMNs) contain cytoplasmic ‘stores’ of three key molecules normally associated with antigen presentation and T-cell costimulation, i.e. major histocompatibility complex class II (DR) antigen, CD80 (B7-1) and CD86 (B7-2). These cytoplasmic molecules were found to translocate to the cell surface within a few minutes following cross-linking (X-L) of Mac-1: an early neutrophil activation signal. In this study we have compared X-L of Mac −1 in parallel with four other well documented in vitro neutrophil activators: phorbol myristate acetate, N-formyl methionyl leucyl phenylalanine, lipopolysaccharide, and phagocytosis of immunoglobulin G–Latex particles. In addition, we have used paired samples of neutrophils obtained from peripheral blood (as a control) and synovial fluid from patients with rheumatoid arthritis as a source of in vivo activated cells. With the exception of phagocytosis, all activators resulted in the rapid (within 30 min) generation of two populations of activated neutrophils (designated P1 and P2) based on flow-cytometry measurements of size, granularity and phenotype. Significant up-regulation of DR and costimulatory molecules was observed, predominantly on P2 cells, with all activators except phagocytosis. CD80 and CD86 were noted to respond to the various activation signals in a different pattern suggesting that their intracellular granule location may be different. Dual-staining confocal laser microscopy studies showed that CD80 is largely confined to secretory vesicles (SVs) while CD86 appears to have a much wider distribution being found in SVs and within secondary (specific) and primary (azurophilic) granules. Increased surface expression of these antigens was also observed on P2 synovial fluid neutrophils appearing as large heterogeneous clusters on the cell surface when visualized by confocal laser microscopy. PMID:17034427

  8. Structure of a lamprey variable lymphocyte receptor in complex with a protein antigen

    PubMed Central

    Velikovsky, C Alejandro; Deng, Lu; Tasumi, Satoshi; Iyer, Lakshminarayan M; Kerzic, Melissa C; Aravind, L; Pancer, Zeev; Mariuzza, Roy A

    2009-01-01

    Variable lymphocyte receptors (VLRs) are leucine-rich repeat (LRR) proteins that mediate adaptive immunity in jawless vertebrates. VLRs are fundamentally different from the antibodies of jawed vertebrates, which consist of immunoglobulin (Ig) domains. We determined the structure of an anti-hen egg white lysozyme (HEL) VLRB, isolated by yeast display, bound to HEL. The VLR, whose affinity resembles that of IgM antibodies, uses nearly all its concave surface to bind the protein, in addition to a loop that penetrates into the enzyme active site. The VLR-HEL structure, combined with sequence analysis, revealed an almost perfect match between ligand-contacting positions and positions with highest sequence diversity. Thus, we have defined the generalized antigen-binding site of VLRs. We further demonstrated that VLRs can be affinity-matured to affinities as high as those of IgG antibodies, making VLRs potential alternatives to antibodies for biotechnology applications. PMID:19543291

  9. LSPR biomolecular assay with high sensitivity induced by aptamer-antigen-antibody sandwich complex.

    PubMed

    Guo, Longhua; Kim, Dong-Hwan

    2012-01-15

    Herein we demonstrate a sensitive approach for protein detection based on peak shifts of localized surface plasmon resonance (LSPR) induced by aptamer-antigen-antibody sandwich structures. The applicability of the proposed method is demonstrated using human α-thrombin as a model analyte. While the binding of thrombin to its specific receptor, thrombin binding aptamer (TBA) modified on Au nanorods (AuNRs), causes a measurable LSPR shift, a subsequent binding of an anti-thrombin antibody to the captured thrombin can exhibit a nearly 150% amplification in the LSPR response. This enhanced signal essentially leads to an improvement of limit of detection (LOD) by more than one order of magnitude. In addition, the use of TBA as thrombin recognition units makes the biosensor reusable. The feasibility of the proposed method was further exploited by the detection of thrombin in human serum, opening the possibility of a real application for diagnostics and medical investigations. PMID:22099957

  10. Muscle FBPase in a complex with muscle aldolase is insensitive to AMP inhibition.

    PubMed

    Rakus, D; Pasek, M; Krotkiewski, H; Dzugaj, A

    2003-07-17

    Real-time interaction analysis, using the BIAcore biosensor, of rabbit muscle FBPase-aldolase complex revealed apparent binding constant [K(Aapp)] values of about 4.4x10(8) M(-1). The stability of the complex was down-regulated by the glycolytic intermediates dihydroxyacetone phosphate and fructose 6-phosphate, and by the regulator of glycolysis and glyconeogenesis--fructose 2,6-bisphosphate. FBPase in a complex with aldolase was entirely insensitive to inhibition by physiological concentrations of AMP (I(0.5) was 1.35 mM) and the cooperativity of the inhibition was not observed. The existence of an FBPase-aldolase complex that is insensitive to AMP inhibition explains the possibility of glycogen synthesis from carbohydrate precursors in vertebrates' myocytes. PMID:12860378

  11. Schistosoma japonicum egg antigen up-regulates fibrogenesis and inhibits proliferation in primary hepatic stellate cells in a concentration-dependent manner

    PubMed Central

    Liu, Ping; Wang, Mi; Lu, Xiao-Dan; Zhang, Shu-Juan; Tang, Wang-Xian

    2013-01-01

    AIM: To investigate the effects of different concentrations of Schistosoma japonicum (S. japonicum) egg antigen on fibrogenesis and apoptosis in primary hepatic stellate cells (HSCs). METHODS: A mouse model of schistosomiasis-associated liver fibrosis (SSLF) was established by infecting mice with schistosomal cercaria via the abdomen. HSCs were isolated from SSLF mice by discontinuous density gradient centrifugation, and their identity was confirmed by immunofluorescence double staining of α-smooth muscle actin (α-SMA) and desmin. The growth inhibitory effect and 50% inhibitory concentration (IC50) of S. japonicum egg antigen for primary HSCs (24 h) were determined using a cell counting kit-8 (CCK-8) assay. The expression levels of α-SMA, matrix metalloproteinase-9 (MMOL/LP-9) and tissue inhibitor of metalloproteinases-1 (TIMP-1) in HSCs in response to different concentrations of S. japonicum egg antigen were detected by Western blotting and real-time reverse transcription-polymerase chain reaction. The levels of phospho-P38 (P-P38), phospho-Jun N-terminal kinase (P-JNK) and phospho-Akt (P-AKT) in HSCs were detected by Western blotting. RESULTS: An SSLF mouse model was established, and primary HSCs were successfully isolated and cultured. S. japonicum egg antigen inhibited HSC proliferation in a concentration-dependent manner. The IC50 of the S. japonicum egg antigen was 244.53 ± 35.26 μg/mL. S. japonicum egg antigen enhanced α-SMA expression at both the mRNA and protein levels and enhanced TIMP-1 expression at the mRNA level in HSCs (P < 0.05), whereas the expression of MMOL/LP-9 was attenuated at both the mRNA and protein levels in a concentration-dependent manner (P < 0.05). A high concentration of S. japonicum egg antigen enhanced P-P38, P-JNK and P-AKT activation (P < 0.05). The changes in α-SMA and MMOL/LP-9 expression induced by S. japonicum egg antigen were closely correlated with P-P38 and P-JNK activation (P < 0.05). The attenuation of MMOL/LP-9

  12. Proteasome Subtypes and Regulators in the Processing of Antigenic Peptides Presented by Class I Molecules of the Major Histocompatibility Complex

    PubMed Central

    Vigneron, Nathalie; Van den Eynde, Benoît J.

    2014-01-01

    The proteasome is responsible for the breakdown of cellular proteins. Proteins targeted for degradation are allowed inside the proteasome particle, where they are cleaved into small peptides and released in the cytosol to be degraded into amino acids. In vertebrates, some of these peptides escape degradation in the cytosol, are loaded onto class I molecules of the major histocompatibility complex (MHC) and displayed at the cell surface for scrutiny by the immune system. The proteasome therefore plays a key role for the immune system: it provides a continued sampling of intracellular proteins, so that CD8-positive T-lymphocytes can kill cells expressing viral or tumoral proteins. Consequently, the repertoire of peptides displayed by MHC class I molecules at the cell surface depends on proteasome activity, which may vary according to the presence of proteasome subtypes and regulators. Besides standard proteasomes, cells may contain immunoproteasomes, intermediate proteasomes and thymoproteasomes. Cells may also contain regulators of proteasome activity, such as the 19S, PA28 and PA200 regulators. Here, we review the effects of these proteasome subtypes and regulators on the production of antigenic peptides. We also discuss an unexpected function of the proteasome discovered through the study of antigenic peptides: its ability to splice peptides. PMID:25412285

  13. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    PubMed Central

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-01-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1–40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1–40 peptide on the basis of their emission response. PMID:26419607

  14. Inhibition of Beta-Amyloid Fibrillation by Luminescent Iridium(III) Complex Probes

    NASA Astrophysics Data System (ADS)

    Lu, Lihua; Zhong, Hai-Jing; Wang, Modi; Ho, See-Lok; Li, Hung-Wing; Leung, Chung-Hang; Ma, Dik-Lung

    2015-09-01

    We report herein the application of kinetically inert luminescent iridium(III) complexes as dual inhibitors and probes of beta-amyloid fibrillogenesis. These iridium(III) complexes inhibited Aβ1-40 peptide aggregation in vitro, and protected against Aβ-induced cytotoxicity in neuronal cells. Furthermore, the complexes differentiated between the aggregated and unaggregated forms of Aβ1-40 peptide on the basis of their emission response.

  15. Effect of mitochondrial complex I inhibition on Fe-S cluster protein activity

    SciTech Connect

    Mena, Natalia P.; Bulteau, Anne Laure; Salazar, Julio; Hirsch, Etienne C.; Nunez, Marco T.

    2011-06-03

    Highlights: {yields} Mitochondrial complex I inhibition resulted in decreased activity of Fe-S containing enzymes mitochondrial aconitase and cytoplasmic aconitase and xanthine oxidase. {yields} Complex I inhibition resulted in the loss of Fe-S clusters in cytoplasmic aconitase and of glutamine phosphoribosyl pyrophosphate amidotransferase. {yields} Consistent with loss of cytoplasmic aconitase activity, an increase in iron regulatory protein 1 activity was found. {yields} Complex I inhibition resulted in an increase in the labile cytoplasmic iron pool. -- Abstract: Iron-sulfur (Fe-S) clusters are small inorganic cofactors formed by tetrahedral coordination of iron atoms with sulfur groups. Present in numerous proteins, these clusters are involved in key biological processes such as electron transfer, metabolic and regulatory processes, DNA synthesis and repair and protein structure stabilization. Fe-S clusters are synthesized mainly in the mitochondrion, where they are directly incorporated into mitochondrial Fe-S cluster-containing proteins or exported for cytoplasmic and nuclear cluster-protein assembly. In this study, we tested the hypothesis that inhibition of mitochondrial complex I by rotenone decreases Fe-S cluster synthesis and cluster content and activity of Fe-S cluster-containing enzymes. Inhibition of complex I resulted in decreased activity of three Fe-S cluster-containing enzymes: mitochondrial and cytosolic aconitases and xanthine oxidase. In addition, the Fe-S cluster content of glutamine phosphoribosyl pyrophosphate amidotransferase and mitochondrial aconitase was dramatically decreased. The reduction in cytosolic aconitase activity was associated with an increase in iron regulatory protein (IRP) mRNA binding activity and with an increase in the cytoplasmic labile iron pool. Since IRP activity post-transcriptionally regulates the expression of iron import proteins, Fe-S cluster inhibition may result in a false iron deficiency signal. Given that

  16. Branched-chain amino acids complex inhibits melanogenesis in B16F0 melanoma cells.

    PubMed

    Cha, Jae-Young; Yang, Hyun-Ju; Moon, Hyung-In; Cho, Young-Su

    2012-04-01

    Present study was investigated the effect of each or complex of three branched-chain amino acids (BCAAs; isoleucine, leucine, and valine) on melanin production in B16F0 melanoma cells treated with various concentrations (1-16 mM) for 72 h. Among the 20 amino acids, lysine and glycine showed the highest activities of DPPH radical scavenging and mushroom tyrosinase inhibition, respectively. Each and combination of BCAAs reduced melanogenesis in a concentration-dependent manner without any morphological changes and cell viability in melanoma cells. Present study was also investigated the inhibitory effects of each or complex of BCAAs at each 10 mM concentration on the 100 μM IBMX-mediated stimulation of melanogenesis in melanoma cells for 72 h and found that IBMX treatment was stimulated to enhance melanin synthesis and that the complex of BCAAs was the most effectively inhibited in the melanin amounts of cellular and extracellular and the whitening the cell pellet. When the inhibitory effect of BCAAs on tyrosinase was examined by intracellular tyrosinase assay, both isoleucine and valine exhibit slightly inhibition, but leucine and combination of BCAAs did not inhibit the cell-derived tyrosinase activity. Present study demonstrated that complex of BCAAs inhibited melanin production without changes intercellular tyrosinase activity. Thus, the complex of BCAAs may be used in development of safe potentially depigmenting agents. PMID:21854182

  17. Complex formation with nucleic acids and aptamers alters the antigenic properties of platelet factor 4

    PubMed Central

    Jaax, Miriam E.; Krauel, Krystin; Marschall, Thomas; Brandt, Sven; Gansler, Julia; Fürll, Birgitt; Appel, Bettina; Fischer, Silvia; Block, Stephan; Helm, Christiane A.; Müller, Sabine; Preissner, Klaus T.

    2013-01-01

    The tight electrostatic binding of the chemokine platelet factor 4 (PF4) to polyanions induces heparin-induced thrombocytopenia, a prothrombotic adverse drug reaction caused by immunoglobulin G directed against PF4/polyanion complexes. This study demonstrates that nucleic acids, including aptamers, also bind to PF4 and enhance PF4 binding to platelets. Systematic assessment of RNA and DNA constructs, as well as 4 aptamers of different lengths and secondary structures, revealed that increasing length and double-stranded segments of nucleic acids augment complex formation with PF4, while single nucleotides or single-stranded polyA or polyC constructs do not. Aptamers were shown by circular dichroism spectroscopy to induce structural changes in PF4 that resemble those induced by heparin. Moreover, heparin-induced anti-human–PF4/heparin antibodies cross-reacted with human PF4/nucleic acid and PF4/aptamer complexes, as shown by an enzyme immunoassay and a functional platelet activation assay. Finally, administration of PF4/44mer–DNA protein C aptamer complexes in mice induced anti–PF4/aptamer antibodies, which cross-reacted with murine PF4/heparin complexes. These data indicate that the formation of anti-PF4/heparin antibodies in postoperative patients may be augmented by PF4/nucleic acid complexes. Moreover, administration of therapeutic aptamers has the potential to induce anti-PF4/polyanion antibodies and a prothrombotic diathesis. PMID:23673861

  18. Schwann cell differentiation inhibits interferon-gamma induction of expression of major histocompatibility complex class II and intercellular adhesion molecule-1.

    PubMed

    Lisak, Robert P; Bealmear, Beverly; Benjamins, Joyce A

    2016-06-15

    Interferon-gamma (IFN-γ) upregulates major histocompatibility complex class II (MHC class II) antigens and intercellular adhesion molecule-1 (ICAM-1) on Schwann cells (SC) in vitro, but in nerves of animals and patients MHC class II is primarily expressed on inflammatory cells. We investigated whether SC maturation influences their expression. IFN-γ induced MHC class II and upregulated ICAM-1; the axolemma-like signal 8-bromo cyclic adenosine monophosphate (8 Br cAMP) with IFN-γ inhibited expression. Delaying addition of 8 Br cAMP to SC already exposed to IFN-γ inhibited ongoing expression; addition of IFN-γ to SC already exposed to 8 Br cAMP resulted in minimal expression. Variability of cytokine-induced MHC class II and ICAM-1 expression by SC in vivo may represent the variability of signals from axolemma. PMID:27235355

  19. Generation of a monoclonal antibody recognizing the CEACAM glycan structure and inhibiting adhesion using cancer tissue-originated spheroid as an antigen

    PubMed Central

    Sato, Yumi; Tateno, Hiroaki; Adachi, Jun; Okuyama, Hiroaki; Endo, Hiroko; Tomonaga, Takeshi; Inoue, Masahiro

    2016-01-01

    Spheroids cultured directly from tumours can better reflect in vivo tumour characteristics than two-dimensional monolayer culture or three-dimensional culture of established cell lines. In this study, we generated antibodies by directly immunizing mice with primary-cultured living spheroids from human colorectal cancer. We performed phenotypic screening via recognition of the surface of the spheroids and inhibition of their adhesion to extracellular matrices to identify a monoclonal antibody, clone 5G2. The antibody inhibited cell migration in two-dimensional culture and promoted cell detachment. Western blotting and immunohistochemistry detected the 5G2 signal in many colorectal cancer spheroids, as well as patient tumours, but failed to detect in various cell lines examined. We found that 5G2 recognized the Lea and Lec on N-glycan, and their major carrier proteins were CEACAM5 and CEACAM6. Pre-incubation of the spheroids with 5G2 impaired translocation of integrin β4 from the lateral membrane to the contact interface between the extracellular matrix when embedded in it. As we successfully obtained a functional antibody, which antigen was glycan structures and lost in cell lines, cancer tissue-originated spheroids can be a useful antigen for generating novel anti-cancer antibodies. PMID:27098764

  20. Contribution of dopamine to mitochondrial complex I inhibition and dopaminergic deficits caused by methylenedioxymethamphetamine in mice.

    PubMed

    Barros-Miñones, L; Goñi-Allo, B; Suquia, V; Beitia, G; Aguirre, N; Puerta, E

    2015-06-01

    Methylenedioxymethamphetamine (MDMA) causes a persistent loss of dopaminergic cell bodies in the substantia nigra of mice. Current evidence indicates that MDMA-induced neurotoxicity is mediated by oxidative stress probably due to the inhibition of mitochondrial complex I activity. In this study we investigated the contribution of dopamine (DA) to such effects. For this, we modulated the dopaminergic system of mice at the synthesis, uptake or metabolism levels. Striatal mitochondrial complex I activity was decreased 1 h after MDMA; an effect not observed in the striatum of DA depleted mice or in the hippocampus, a dopamine spare region. The DA precursor, L-dopa, caused a significant reduction of mitochondrial complex I activity by itself and exacerbated the dopaminergic deficits when combined with systemic MDMA. By contrast, no damage was observed when L-dopa was combined with intrastriatal injections of MDMA. On the other hand, dopamine uptake blockade using GBR 12909, inhibited both, the acute inhibition of complex I activity and the long-term dopaminergic toxicity caused by MDMA. Moreover, the inhibition of DA metabolism with the monoamine oxidase (MAO) inhibitor, pargyline, afforded a significant protection against MDMA-induced complex I inhibition and neurotoxicity. Taken together, these findings point to the formation of hydrogen peroxide subsequent to DA metabolism by MAO, rather than a direct DA-mediated mitochondrial complex I inhibition, and the contribution of a peripheral metabolite of MDMA, as the key steps in the chain of biochemical events leading to DA neurotoxicity caused by MDMA in mice. PMID:25666033

  1. Targeting metabolic flexibility by simultaneously inhibiting respiratory complex I and lactate generation retards melanoma progression

    PubMed Central

    Chaube, Balkrishna; Malvi, Parmanand; Singh, Shivendra Vikram; Mohammad, Naoshad; Meena, Avtar Singh; Bhat, Manoj Kumar

    2015-01-01

    Melanoma is a largely incurable skin malignancy owing to the underlying molecular and metabolic heterogeneity confounded by the development of resistance. Cancer cells have metabolic flexibility in choosing either oxidative phosphorylation (OXPHOS) or glycolysis for ATP generation depending upon the nutrient availability in tumor microenvironment. In this study, we investigated the involvement of respiratory complex I and lactate dehydrogenase (LDH) in melanoma progression. We show that inhibition of complex I by metformin promotes melanoma growth in mice via elevating lactate and VEGF levels. In contrast, it leads to the growth arrest in vitro because of enhanced extracellular acidification as a result of increased glycolysis. Inhibition of LDH or lactate generation causes decrease in glycolysis with concomitant growth arrest both in vitro and in vivo. Blocking lactate generation in metformin-treated melanoma cells results in diminished cell proliferation and tumor progression in mice. Interestingly, inhibition of either LDH or complex I alone does not induce apoptosis, whereas inhibiting both together causes depletion in cellular ATP pool resulting in metabolic catastrophe induced apoptosis. Overall, our study suggests that LDH and complex I play distinct roles in regulating glycolysis and cell proliferation. Inhibition of these two augments synthetic lethality in melanoma. PMID:26484566

  2. Affinities of human histo-blood group antigens for norovirus capsid protein complexes

    PubMed Central

    Han, Ling; Kitova, Elena N; Tan, Ming; Jiang, Xi; Pluvinage, Benjamin; Boraston, Alisdair B; Klassen, John S

    2015-01-01

    The binding profiles of many human noroviruses (huNoVs) for human histo-blood group antigens have been characterized. However, quantitative-binding data for these important virus–host interactions are lacking. Here, we report on the intrinsic (per binding site) affinities of HBGA oligosaccharides for the huNoV VA387 virus-like particles (VLPs) and the associated subviral P particles measured using electrospray ionization mass spectrometry. The affinities of 13 HBGA oligosaccharides, containing A, B and H epitopes, with variable sizes (disaccharide to tetrasaccharide) and different precursor chain types (types 1, 2, 3, 5 and 6), were measured for the P particle, while the affinities of the A and B trisaccharides and A and B type 6 tetrasaccharides for the VLP were determined. The intrinsic affinities of the HBGA oligosaccharides for the P particle range from 500 to 2300 M−1, while those of the A and B trisaccharides and the A and B type 6 tetrasaccharides for the VLP range from 1000 to 4000 M−1. Comparison of these binding data with those measured previously for the corresponding P dimer reveals that the HBGA oligosaccharides tested exhibit similar intrinsic affinities for the P dimer and P particle. The intrinsic affinities for the VLP are consistently higher than those measured for the P particle, but within a factor of three. While the cause of the subtle differences in HBGA oligosaccharide affinities for the P dimer and P particle and those for the VLP remains unknown, the present data support the use of P dimers or P particles as surrogates to the VLP for huNoV-receptor-binding studies. PMID:25395406

  3. T cell receptor reversed polarity recognition of a self-antigen major histocompatibility complex.

    PubMed

    Beringer, Dennis X; Kleijwegt, Fleur S; Wiede, Florian; van der Slik, Arno R; Loh, Khai Lee; Petersen, Jan; Dudek, Nadine L; Duinkerken, Gaby; Laban, Sandra; Joosten, Antoinette; Vivian, Julian P; Chen, Zhenjun; Uldrich, Adam P; Godfrey, Dale I; McCluskey, James; Price, David A; Radford, Kristen J; Purcell, Anthony W; Nikolic, Tatjana; Reid, Hugh H; Tiganis, Tony; Roep, Bart O; Rossjohn, Jamie

    2015-11-01

    Central to adaptive immunity is the interaction between the αβ T cell receptor (TCR) and peptide presented by the major histocompatibility complex (MHC) molecule. Presumably reflecting TCR-MHC bias and T cell signaling constraints, the TCR universally adopts a canonical polarity atop the MHC. We report the structures of two TCRs, derived from human induced T regulatory (iT(reg)) cells, complexed to an MHC class II molecule presenting a proinsulin-derived peptide. The ternary complexes revealed a 180° polarity reversal compared to all other TCR-peptide-MHC complex structures. Namely, the iT(reg) TCR α-chain and β-chain are overlaid with the α-chain and β-chain of MHC class II, respectively. Nevertheless, this TCR interaction elicited a peptide-reactive, MHC-restricted T cell signal. Thus TCRs are not 'hardwired' to interact with MHC molecules in a stereotypic manner to elicit a T cell signal, a finding that fundamentally challenges our understanding of TCR recognition. PMID:26437244

  4. Envelope protein complexes of Mycobacterium avium subsp. paratuberculosis and their antigenicity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne’s disease, a chronic enteric disease of ruminant animals. In the present study, blue native PAGE electrophoresis and 2D SDS-PAGE were used to separate MAP envelope protein complexes, followed by mass spectrometry (MS) ...

  5. A model of motor inhibition for a complex skill: baseball batting.

    PubMed

    Gray, Rob

    2009-06-01

    The ability to inhibit an ongoing action in response to a signal from the environment is important for many perceptual-motor actions. This paper examines a particular example of this behavior: attempting to inhibit or "check" a swing in baseball batting. A model of motor inhibition in batting is proposed. In the model there are three different inhibition signals (out of range launch angle, early expected-actual trajectory discrepancy, and late expected-actual trajectory discrepancy) resulting in four possible response outcomes for the batter's swing (full swing, inhibited swing, partial response, or interrupted swing). The predictions of the model were compared with the actual batting performance of 20 baseball players using a high-fidelity batting simulator. The proportions of the different response outcomes could be explained by the inhibition model for 17/20 of the batters in the study. These findings suggest that models of motor inhibition developed for simple, discrete tasks can be applied to complex, multistage behaviors. This batting inhibition model could be used to provide a quantitative measure of a player's bat control for training and player-screening purposes. (PsycINFO Database Record (c) 2009 APA, all rights reserved). PMID:19586249

  6. Injury and differentiation following inhibition of mitochondrial respiratory chain complex IV in rat oligodendrocytes

    PubMed Central

    Ziabreva, Iryna; Campbell, Graham; Rist, Julia; Zambonin, Jessica; Rorbach, Joanna; Wydro, Mateusz M; Lassmann, Hans; Franklin, Robin J M; Mahad, Don

    2010-01-01

    Oligodendrocyte lineage cells are susceptible to a variety of insults including hypoxia, excitotoxicity, and reactive oxygen species. Demyelination is a well-recognized feature of several CNS disorders including multiple sclerosis, white matter strokes, progressive multifocal leukoencephalopathy, and disorders due to mitochondrial DNA mutations. Although mitochondria have been implicated in the demise of oligodendrocyte lineage cells, the consequences of mitochondrial respiratory chain defects have not been examined. We determine the in vitro impact of established inhibitors of mitochondrial respiratory chain complex IV or cytochrome c oxidase on oligodendrocyte progenitor cells (OPCs) and mature oligodendrocytes as well as on differentiation capacity of OPCs from P0 rat. Injury to mature oligodendrocytes following complex IV inhibition was significantly greater than to OPCs, judged by cell detachment and mitochondrial membrane potential (MMP) changes, although viability of cells that remained attached was not compromised. Active mitochondria were abundant in processes of differentiated oligodendrocytes and MMP was significantly greater in differentiated oligodendrocytes than OPCs. MMP dissipated following complex IV inhibition in oligodendrocytes. Furthermore, complex IV inhibition impaired process formation within oligodendrocyte lineage cells. Injury to and impaired process formation of oligodendrocytes following complex IV inhibition has potentially important implications for the pathogenesis and repair of CNS myelin disorders. © 2010 Wiley-Liss, Inc. PMID:20665559

  7. The 2.5 Å Structure of CD1c in Complex with a Mycobacterial Lipid Reveals an Open Groove Ideally Suited for Diverse Antigen Presentation

    SciTech Connect

    Scharf, Louise; Li, Nan-Sheng; Hawk, Andrew J.; Garzón, Diana; Zhang, Tejia; Fox, Lisa M.; Kazen, Allison R.; Shah, Sneha; Haddadian, Esmael J.; Gumperz, Jenny E.; Saghatelian, Alan; Faraldo-Gómez, José D.; Meredith, Stephen C.; Piccirilli, Joseph A.; Adams, Erin J.

    2011-08-24

    CD1 molecules function to present lipid-based antigens to T cells. Here we present the crystal structure of CD1c at 2.5 {angstrom} resolution, in complex with the pathogenic Mycobacterium tuberculosis antigen mannosyl-{beta}1-phosphomycoketide (MPM). CD1c accommodated MPM's methylated alkyl chain exclusively in the A pocket, aided by a unique exit portal underneath the {alpha}1 helix. Most striking was an open F pocket architecture lacking the closed cavity structure of other CD1 molecules, reminiscent of peptide binding grooves of classical major histocompatibility complex molecules. This feature, combined with tryptophan-fluorescence quenching during loading of a dodecameric lipopeptide antigen, provides a compelling model by which both the lipid and peptide moieties of the lipopeptide are involved in CD1c presentation of lipopeptides.

  8. Serum from mice immunized in the context of Treg inhibition identifies DEK as a neuroblastoma tumor antigen

    PubMed Central

    Zheng, Jin; Kohler, M Eric; Chen, Qingrong; Weber, James; Khan, Javed; Johnson, Bryon D; Orentas, Rimas J

    2007-01-01

    Background We have developed a cell-based vaccine that features the expression of both CD80 and CD86 on the surface of a murine neuroblastoma cell line. The cellular immunity induced by this vaccine is enhanced by treatment with antibody that interferes with T-regulatory cell (Treg) function and we report here that immunization combined with interfering with Treg function also produces a profound serological effect. Serum from mice immunized with our cell-based vaccine in the context of Treg blockade was used to screen a cDNA expression library constructed from the parental neuroblastoma tumor cell line, AGN2a. Results Serum from mice vaccinated in the context of Treg blockade identified a number of potentially oncogenic transcripts that may serve as important immune targets in a tumor-derived cDNA library screen. This novel approach identified far more candidates than could be seen with serum derived from vaccine-treated only, Treg-depleted only, or tumor-bearing mice. The most commonly identified tumor-associated antigen, using serum from immunized and Treg-depleted mice, was the DEK oncogene. Altered expression of the DEK oncogene has been implicated in a number of human cancers. Importantly, we were able to demonstrate that the DEK oncogene also induces a T cell response. Conclusion The use of post-vaccine immune serum in this report differs from previous approaches where serum collected at the time of cancer onset or diagnosis and was used for tumor antigen identification. We hypothesize that the use of diagnostic serum samples may be inadequate for the clinical translation of this approach, and that identification of protective immunogenic tumor antigens may require the use of serum from post-treatment or vaccinated subjects. The identification of DEK as a tumor-associated antigen capable of eliciting a T cell response validates our experimental approach and argues for the antigens we have identified here to be evaluated as targets of effector immunity and as

  9. Immunization with antigenic peptides complexed with β-glucan induces potent cytotoxic T-lymphocyte activity in combination with CpG-ODNs.

    PubMed

    Mochizuki, Shinichi; Morishita, Hiromi; Kobiyama, Kouji; Aoshi, Taiki; Ishii, Ken J; Sakurai, Kazuo

    2015-12-28

    The induction of antigen-specific immune responses requires immunization with not only antigens, but also adjuvants. CpG oligonucleotides (CpG-ODNs) are well-known ligands for Toll-like receptor 9 and a potent adjuvant that induces both Th1-type humoral and cellular immune responses including cytotoxic T-lymphocyte responses. We previously demonstrated that β-glucan schizophyllan (SPG) can form complexes with CpG-ODNs with attached dA40 (CpG-dA/SPG), which can accumulate in macrophages in the draining inguinal lymph nodes and induce strong immune responses by co-administration of antigenic proteins, namely ovalbumin (OVA). Immunization with antigenic peptides, OVA257-264, did not induce these antigen-specific immune responses even in combination with CpG-dA/SPG, indicating that peptides require a carrier to antigen presenting cells. In this study, we prepared conjugates comprising OVA257-264 and dA40, and made complexes with SPG. Immunization with OVA257-264-dA/SPG induced peptide-specific immune responses in combination with CpG-dA regardless of complexation with SPG both in vitro and in vivo. When splenocytes from immunized mice were incubated with E.G7-OVA tumor model cells presenting OVA peptides, the number of cells drastically decreased after 24h. Furthermore, mice pre-immunized with OVA257-264-dA/SPG and CpG-ODNs exhibited a long delay in tumor growth after tumor inoculation. Therefore, these peptide-dA/SPG and CpG-dA/SPG complexes could be used as a potent vaccine for the treatment of cancers and infectious diseases. PMID:26562685

  10. Functional effects of the antigen glatiramer acetate are complex and tightly associated with its composition.

    PubMed

    Hasson, Tal; Kolitz, Sarah; Towfic, Fadi; Laifenfeld, Daphna; Bakshi, Shlomo; Beriozkin, Olga; Shacham-Abramson, Maya; Timan, Bracha; Fowler, Kevin D; Birnberg, Tal; Konya, Attila; Komlosh, Arthur; Ladkani, David; Hayden, Michael R; Zeskind, Benjamin; Grossman, Iris

    2016-01-15

    Glatiramer acetate (Copaxone®; GA) is a non-biological complex drug for multiple sclerosis. GA modulated thousands of genes in genome-wide expression studies conducted in THP-1 cells and mouse splenocytes. Comparing GA with differently-manufactured glatiramoid Polimunol (Synthon) in mice yielded hundreds of differentially expressed probesets, including biologically-relevant genes (e.g. Il18, adj p<9e-6) and pathways. In human monocytes, 700+ probesets differed between Polimunol and GA, enriching for 130+ pathways including response to lipopolysaccharide (adj. p<0.006). Key differences were confirmed by qRT-PCR (splenocytes) or proteomics (THP-1). These studies demonstrate the complexity of GA's mechanisms of action, and may help inform therapeutic equivalence assessment. PMID:26711576

  11. Endothelial nitric oxide synthase regulates N-Ras activation on the Golgi complex of antigen-stimulated T cells.

    PubMed

    Ibiza, Sales; Pérez-Rodríguez, Andrea; Ortega, Angel; Martínez-Ruiz, Antonio; Barreiro, Olga; García-Domínguez, Carlota A; Víctor, Víctor M; Esplugues, Juan V; Rojas, José M; Sánchez-Madrid, Francisco; Serrador, Juan M

    2008-07-29

    Ras/ERK signaling plays an important role in T cell activation and development. We recently reported that endothelial nitric oxide synthase (eNOS)-derived NO regulates T cell receptor (TCR)-dependent ERK activation by a cGMP-independent mechanism. Here, we explore the mechanisms through which eNOS exerts this regulation. We have found that eNOS-derived NO positively regulates Ras/ERK activation in T cells stimulated with antigen on antigen-presenting cells (APCs). Intracellular activation of N-, H-, and K-Ras was monitored with fluorescent probes in T cells stably transfected with eNOS-GFP or its G2A point mutant, which is defective in activity and cellular localization. Using this system, we demonstrate that eNOS selectively activates N-Ras but not K-Ras on the Golgi complex of T cells engaged with APC, even though Ras isoforms are activated in response to NO from donors. We further show that activation of N-Ras involves eNOS-dependent S-nitrosylation on Cys(118), suggesting that upon TCR engagement, eNOS-derived NO directly activates N-Ras on the Golgi. Moreover, wild-type but not C118S N-Ras increased TCR-dependent apoptosis, suggesting that S-nitrosylation of Cys(118) contributes to activation-induced T cell death. Our data define a signaling mechanism for the regulation of the Ras/ERK pathway based on the eNOS-dependent differential activation of N-Ras and K-Ras at specific cell compartments. PMID:18641128

  12. Endothelial nitric oxide synthase regulates N-Ras activation on the Golgi complex of antigen-stimulated T cells

    PubMed Central

    Ibiza, Sales; Pérez-Rodríguez, Andrea; Ortega, Ángel; Martínez-Ruiz, Antonio; Barreiro, Olga; García-Domínguez, Carlota A.; Víctor, Víctor M.; Esplugues, Juan V.; Rojas, José M.; Sánchez-Madrid, Francisco; Serrador, Juan M.

    2008-01-01

    Ras/ERK signaling plays an important role in T cell activation and development. We recently reported that endothelial nitric oxide synthase (eNOS)-derived NO regulates T cell receptor (TCR)-dependent ERK activation by a cGMP-independent mechanism. Here, we explore the mechanisms through which eNOS exerts this regulation. We have found that eNOS-derived NO positively regulates Ras/ERK activation in T cells stimulated with antigen on antigen-presenting cells (APCs). Intracellular activation of N-, H-, and K-Ras was monitored with fluorescent probes in T cells stably transfected with eNOS-GFP or its G2A point mutant, which is defective in activity and cellular localization. Using this system, we demonstrate that eNOS selectively activates N-Ras but not K-Ras on the Golgi complex of T cells engaged with APC, even though Ras isoforms are activated in response to NO from donors. We further show that activation of N-Ras involves eNOS-dependent S-nitrosylation on Cys118, suggesting that upon TCR engagement, eNOS-derived NO directly activates N-Ras on the Golgi. Moreover, wild-type but not C118S N-Ras increased TCR-dependent apoptosis, suggesting that S-nitrosylation of Cys118 contributes to activation-induced T cell death. Our data define a signaling mechanism for the regulation of the Ras/ERK pathway based on the eNOS-dependent differential activation of N-Ras and K-Ras at specific cell compartments. PMID:18641128

  13. Detection and purification of two antibody-antigen complexes via selective adsorption on lowly activated anion exchangers.

    PubMed

    Fuentes, Manuel; Pessela, Benevides C C; Mateo, Cesar; Munilla, Roberto; Guisán, Jose M; Fernandez-Lafuente, Roberto

    2004-12-01

    Taken advantage of the mechanism of adsorption of macro-molecules on ionic exchangers, (a multipoint interaction between the protein and the support), it is possible to selectively adsorb large proteins leaving small ones in the supernatant. Associated proteins should present a significant difference in its size as compared to the non-associated forms. Thus, the protein complexes may have much larger surfaces to interact with the support. Here, by selecting the support with the highest activation degree that was unable to adsorb the non-associated proteins, we have shown the simple and selective adsorption of immuno complexes (as a model), while antibodies and antigens remained in the supernatant. Therefore, it was possible to selectively adsorb on lowly activated supports (e.g., agarose 4BCL having only 1 micromol of amino groups per g of support) rabbit IgG/anti-rabbit immunoglobulins (immuno complex), while these supports were unable to adsorb the individual immunoglobulines. Similarly, horseradish peroxidase (HRP)/anti-HRP were selectively adsorbed on lowly activated supports, while the individual proteins were not adsorbed at all. Afterwards, the adsorbed associated proteins (purified at least from the non-associated counterparts and concentrated by the adsorption on the support) may be cross-linked with aldehyde-dextran and be desorbed from the matrix for their analysis. This strategy may permit very simple experiments to detect the presence of protein-protein complexes. Finally, we have shown the advantages of this technique compared to the use of one of the proteins previous immobilized on a support. PMID:15628128

  14. Dectin-1 Is Essential for Reverse Transcytosis of Glycosylated SIgA-Antigen Complexes by Intestinal M Cells

    PubMed Central

    Rochereau, Nicolas; Drocourt, Daniel; Perouzel, Eric; Pavot, Vincent; Redelinghuys, Pierre; Brown, Gordon D.; Tiraby, Gerard; Roblin, Xavier; Verrier, Bernard; Genin, Christian; Corthésy, Blaise; Paul, Stéphane

    2013-01-01

    Intestinal microfold (M) cells possess a high transcytosis capacity and are able to transport a broad range of materials including particulate antigens, soluble macromolecules, and pathogens from the intestinal lumen to inductive sites of the mucosal immune system. M cells are also the primary pathway for delivery of secretory IgA (SIgA) to the gut-associated lymphoid tissue. However, although the consequences of SIgA uptake by M cells are now well known and described, the mechanisms whereby SIgA is selectively bound and taken up remain poorly understood. Here we first demonstrate that both the Cα1 region and glycosylation, more particularly sialic acid residues, are involved in M cell–mediated reverse transcytosis. Second, we found that SIgA is taken up by M cells via the Dectin-1 receptor, with the possible involvement of Siglec-5 acting as a co-receptor. Third, we establish that transcytosed SIgA is taken up by mucosal CX3CR1+ dendritic cells (DCs) via the DC-SIGN receptor. Fourth, we show that mucosal and systemic antibody responses against the HIV p24-SIgA complexes administered orally is strictly dependent on the expression of Dectin-1. Having deciphered the mechanisms leading to specific targeting of SIgA-based Ag complexes paves the way to the use of such a vehicle for mucosal vaccination against various infectious diseases. PMID:24068891

  15. Citrullinated vimentin as an important antigen in immune complexes from synovial fluid of rheumatoid arthritis patients with antibodies against citrullinated proteins

    PubMed Central

    2010-01-01

    Introduction Rheumatoid arthritis (RA) is an inflammatory disease, which results in destruction of the joint. The presence of immune complexes (IC) in serum and synovial fluid of RA patients might contribute to this articular damage through different mechanisms, such as complement activation. Therefore, identification of the antigens from these IC is important to gain more insight into the pathogenesis of RA. Since RA patients have antibodies against citrullinated proteins (ACPA) in their serum and synovial fluid (SF) and since elevated levels of citrullinated proteins are detected in the joints of RA patients, citrullinated antigens are possibly present in IC from RA patients. Methods IC from serum of healthy persons, serum of RA patients and IC from synovial fluid of RA patients and Spondyloarthropathy (SpA) patients were isolated by immunoprecipitation. Identification of the antigens was performed by SDS-PAGE, mass spectrometry and immunodetection. The presence of citrullinated proteins was evaluated by anti-modified citrulline (AMC) staining. Results Circulating IC in the serum of RA patients and healthy controls contain fibrinogenβ and fibronectin, both in a non-citrullinated form. Additionally, in IC isolated from RA SF, fibrinogenγ and vimentin were identified as well. More importantly, vimentin and a minor portion of fibrinogenβ were found to be citrullinated in the isolated complexes. Moreover these citrullinated antigens were only found in ACPA+ patients. No citrullinated antigens were found in IC from SF of SpA patients. Conclusions Citrullinated fibrinogenβ and citrullinated vimentin were found in IC from SF of ACPA+ RA patients, while no citrullinated antigens were found in IC from SF of ACPA- RA patients or SpA patients or in IC from serum of RA patients or healthy volunteers. The identification of citrullinated vimentin as a prominent citrullinated antigen in IC from SF of ACPA+ RA patients strengthens the hypothesis that citrullinated vimentin

  16. Association of the bovine leukocyte antigen major histocompatibility complex class II DRB3*4401 allele with host resistance to the Lone Star Tick, Amblyomma americanum

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The MHC of cattle, known as the bovine leukocyte antigen (BoLA) complex, plays an integral role in disease and parasite susceptibility, and immune responsiveness of the host. While susceptibility to tick infestation in cattle is believed to be heritable, genes that may be responsible for the manife...

  17. The cytolytic C5b-9 complement complex: feedback inhibition of complement activation.

    PubMed Central

    Bhakdi, S; Maillet, F; Muhly, M; Kazatchkine, M D

    1988-01-01

    We describe a regulatory function of the terminal cytolytic C5b-9 complex [C5b-9(m)] of human complement. Purified C5b-9(m) complexes isolated from target membranes, whether in solution or bound to liposomes, inhibited lysis of sensitized sheep erythrocytes by whole human serum in a dose-dependent manner. C9 was not required for the inhibitory function since C5b-7 and C5b-8 complexes isolated from membranes were also effective. No effect was found with the cytolytically inactive, fluid-phase SC5b-9 complex. However, tryptic modification of SC5b-9 conferred an inhibitory capacity to the complex, due probably to partial removal of the S protein. Experiments using purified components demonstrated that C5b-9(m) exerts a regulatory effect on the formation of the classical- and alternative-pathway C3 convertases and on the utilization of C5 by cell-bound C5 convertases. C5b-9(m) complexes were unable to inhibit the lysis of cells bearing C5b-7(m) by C8 and C9. Addition of C5b-9(m) to whole human serum abolished its bactericidal effect on the serum-sensitive Escherichia coli K-12 strain W 3110 and suppressed its hemolytic function on antibody-sensitized, autologous erythrocytes. Feedback inhibition by C5b-9(m) represents a biologically relevant mechanism through which complement may autoregulate its effector functions. Images PMID:3162317

  18. The Impact of Mitochondrial Complex Inhibition on mESC Differentiation

    EPA Science Inventory

    The Impact of Mitochondrial Complex Inhibition on mESC Differentiation JE Royland, SH Warren, S Jeffay, MR Hoopes, HP Nichols, ES Hunter U.S. Environmental Protection Agency, Integrated Systems Toxicology Division, Research Triangle Park, NC The importance of mitochondrial funct...

  19. Eliminating Inhibition of Return by Changing Salient Nonspatial Attributes in a Complex Environment

    ERIC Educational Resources Information Center

    Hu, Frank K.; Samuel, Arthur G.; Chan, Agnes S.

    2011-01-01

    Inhibition of return (IOR) occurs when a target is preceded by an irrelevant stimulus (cue) at the same location: Target detection is slowed, relative to uncued locations. In the present study, we used relatively complex displays to examine the effect of repetition of nonspatial attributes. For both color and shape, attribute repetition produced a…

  20. Crystal structure of tarocystatin-papain complex: implications for the inhibition property of group-2 phytocystatins.

    PubMed

    Chu, Ming-Hung; Liu, Kai-Lun; Wu, Hsin-Yi; Yeh, Kai-Wun; Cheng, Yi-Sheng

    2011-08-01

    Tarocystatin (CeCPI) from taro (Colocasia esculenta cv. Kaohsiung no. 1), a group-2 phytocystatin, shares a conserved N-terminal cystatin domain (NtD) with other phytocystatins but contains a C-terminal cystatin-like extension (CtE). The structure of the tarocystatin-papain complex and the domain interaction between NtD and CtE in tarocystatin have not been determined. We resolved the crystal structure of the phytocystatin-papain complex at resolution 2.03 Å. Surprisingly, the structure of the NtD-papain complex in a stoichiometry of 1:1 could be built, with no CtE observed. Only two remnant residues of CtE could be built in the structure of the CtE-papain complex. Therefore, CtE is easily digested by papain. To further characterize the interaction between NtD and CtE, three segments of tarocystatin, including the full-length (FL), NtD and CtE, were used to analyze the domain-domain interaction and the inhibition ability. The results from glutaraldehyde cross-linking and yeast two-hybrid assay indicated the existence of an intrinsic flexibility in the region linking NtD and CtE for most tarocystatin molecules. In the inhibition activity assay, the glutathione-S-transferase (GST)-fused FL showed the highest inhibition ability without residual peptidase activity, and GST-NtD and FL showed almost the same inhibition ability, which was higher than with NtD alone. On the basis of the structures, the linker flexibility and inhibition activity of tarocystatins, we propose that the overhangs from the cystatin domain may enhance the inhibition ability of the cystatin domain against papain. PMID:21416241

  1. Mechanisms of cell death pathway activation following drug-induced inhibition of mitochondrial complex I

    PubMed Central

    Imaizumi, Naoki; Kwang Lee, Kang; Zhang, Carmen; Boelsterli, Urs A.

    2015-01-01

    Respiratory complex I inhibition by drugs and other chemicals has been implicated as a frequent mode of mitochondria-mediated cell injury. However, the exact mechanisms leading to the activation of cell death pathways are incompletely understood. This study was designed to explore the relative contributions to cell injury of three distinct consequences of complex I inhibition, i.e., impairment of ATP biosynthesis, increased formation of superoxide and, hence, peroxynitrite, and inhibition of the mitochondrial protein deacetylase, Sirt3, due to imbalance of the NADH/NAD+ ratio. We used the antiviral drug efavirenz (EFV) to model drug-induced complex I inhibition. Exposure of cultured mouse hepatocytes to EFV resulted in a rapid onset of cell injury, featuring a no-effect level at 30 µM EFV and submaximal effects at 50 µM EFV. EFV caused a concentration-dependent decrease in cellular ATP levels. Furthermore, EFV resulted in increased formation of peroxynitrite and oxidation of mitochondrial protein thiols, including cyclophilin D (CypD). This was prevented by the superoxide scavenger, Fe-TCP, or the peroxynitrite decomposition catalyst, Fe-TMPyP. Both ferroporphyrins completely protected from EFV-induced cell injury, suggesting that peroxynitrite contributed to the cell injury. Finally, EFV increased the NADH/NAD+ ratio, inhibited Sirt3 activity, and led to hyperacetylated lysine residues, including those in CypD. However, hepatocytes isolated from Sirt3-null mice were protected against 40 µM EFV as compared to their wild-type controls. In conclusion, these data are compatible with the concept that chemical inhibition of complex I activates multiple pathways leading to cell injury; among these, peroxynitrite formation may be the most critical. PMID:25625582

  2. Autoantibodies to ribosomal P antigens with immune complex glomerulonephritis in SJL mice treated with pristane.

    PubMed

    Satoh, M; Hamilton, K J; Ajmani, A K; Dong, X; Wang, J; Kanwar, Y S; Reeves, W H

    1996-10-01

    BALB/c ByJ mice develop a lupus-like syndrome characterized by anti-nRNP/Sm and Su autoantibodies and immune complex glomerulonephritis after a single i.p. pristane injection. In contrast, mercuric chloride induces anti-fibrillarin Abs only in SJL and other H-2s mice, and not in BALB/c (H-2d) mice. In the present study, the specificities of autoantibodies induced by pristane and HgCl2 were compared in SJL and BALB/c mice to examine whether these strains are "programmed" to make different sets of autoantibodies in response to nonspecific immune stimulation. Unexpectedly, the predominant autoantibodies induced by pristane in SJL mice were neither those characteristic of HgCl2-treated SJL mice nor those associated with pristane-induced disease in BALB/c mice but, rather, anti-ribosomal P, another lupus-related specificity. The autoantibodies were strongly reactive with the C-terminal 22 amino acids of the ribosomal P2 protein, indicating that they exhibited similar fine specificities to anti-P Abs in human SLE and MRL/Ipr mice. Like BALB/c mice, pristane-treated SJL mice developed severe glomerulonephritis characterized by proteinuria, mesangial proliferation, and glomerular immune complex deposits. This is the first evidence that the induction of a lupus-like syndrome by pristane is not restricted to BALB/c mice. The predominance of anti-P Abs in SJL mice contrasts sharply with the predominance of anti-nRNP/Sm and Su, in pristane-treated BALB/c mice, even though the renal lesions were similar in both strains. The data suggest that H-2s does not program mice to produce anti-fibrillarin Abs in response to nonspecific immune stimulation, arguing that autoantibody induction by pristane involves Ag-specific mechanisms. PMID:8816434

  3. Identification and Expression of a Mycoplasma gallisepticum Surface Antigen Recognized by a Monoclonal Antibody Capable of Inhibiting Both Growth and Metabolism

    PubMed Central

    Yoshida, Shigeto; Fujisawa, Ayumi; Tsuzaki, Yoshinari; Saitoh, Shuji

    2000-01-01

    In order to identify antigenic proteins of Mycoplasma gallisepticum, monoclonal antibodies (MAbs) against virulent M. gallisepticum R strain were produced in mice. MAb 35A6 was selected for its abilities to inhibit both growth and metabolism of M. gallisepticum in vitro. The MAb recognized a membrane protein with an apparent molecular mass of 120 kDa. The corresponding gene, designated the mgc3 gene, was cloned from an M. gallisepticum genomic DNA expression library and sequenced. The mgc3 gene is a homologue of the ORF6 gene encoding 130-kDa protein in the P1 operon of M. pneumoniae and is localized downstream of the mgc1 gene, a homologue of the P1 gene. To assess the characteristics of MGC3 protein, all 10 TGA codons in the mgc3 gene, which encode a tryptophan in the Mycoplasma species, were replaced with TGG codons, and recombinant fowlpox viruses (FPV) harboring the altered mgc3 gene were constructed. One of the recombinant FPVs was improved to express MGC3 protein on the cell surface in which the signal peptide of MGC3 protein was replaced with one from Marek's disease virus gB. These results should provide the impetus to develop a vaccine based on MGC3 protein which can induce antibodies with both growth inhibition and metabolic-inhibition activities using a recombinant FPV. PMID:10816462

  4. Primary structure of the 175K Plasmodium falciparum erythrocyte binding antigen and identification of a peptide which elicits antibodies that inhibit malaria merozoite invasion.

    PubMed

    Sim, B K; Orlandi, P A; Haynes, J D; Klotz, F W; Carter, J M; Camus, D; Zegans, M E; Chulay, J D

    1990-11-01

    The Plasmodium falciparum gene encoding erythrocyte binding antigen-175 (EBA-175), a putative receptor for red cell invasion (Camus, D., and T. J. Hadley. 1985. Science (Wash. DC). 230:553-556.), has been isolated and characterized. DNA sequencing demonstrated a single open reading frame encoding a translation product of 1,435 amino acid residues. Peptides corresponding to regions on the deduced amino acid sequence predicted to be B cell epitopes were assessed for immunogenicity. Immunization of mice and rabbits with EBA-peptide 4, a synthetic peptide encompassing amino acid residues 1,062-1,103, produced antibodies that recognized P. falciparum merozoites in an indirect fluorescent antibody assay. When compared to sera from rabbits immunized with the same adjuvant and carrier protein, sera from rabbits immunized with EBA-peptide 4 inhibited merozoite invasion of erythrocytes in vitro by 80% at a 1:5 dilution. Furthermore, these sera inhibited the binding of purified, authentic EBA-175 to erythrocytes, suggesting that their activity in inhibiting merozoite invasion of erythrocytes is mediated by blocking the binding of EBA-175 to erythrocytes. Since the nucleotide sequence of EBA-peptide 4 is conserved among seven strains of P. falciparum from throughout the world (Sim, B. K. L. 1990. Mol. Biochem. Parasitol. 41:293-296.), these data identify a region of the protein that should be a focus of vaccine development efforts. PMID:2229177

  5. Immunocytochemical and biochemical characterization of the Heymann nephritis antigenic complex in rat L2 yolk sac cells.

    PubMed Central

    Lundstrom, M.; Orlando, R. A.; Saedi, M. S.; Woodward, L.; Kurihara, H.; Farquhar, M. G.

    1993-01-01

    Heymann nephritis in the rat is the most widely used model of human membranous glomerulonephritis. Glycoprotein (gp)330, a large (M(r) > 550,000) membrane-associated glycoprotein, has been identified as the main antigen in this autoimmune disease. Studies of gp330 and receptor-associated protein (RAP), its 44-kd subunit, have been restricted largely to rat kidney, as no stable cultured cell line has been available that expresses gp330. We have recently identified a rat yolk sac carcinoma cell line (L2) that expresses both gp330 and RAP. In this report, we have carried out detailed morphological, immunocytochemical, and biochemical studies characterizing the biosynthesis and localization of gp330 and RAP in the L2 rat yolk sac cell line. At the electron microscope level, the L2 cells are seen to be attached by cell junctions, and their predominant morphological features include extensive networks of rough endoplasmic reticulum (ER) and numerous clathrin-coated pits found on the cell membrane. By immunocytochemistry, gp330 was localized primarily to clathrin-coated pits at the cell surface, whereas RAP was localized predominantly to the lumen of the rough ER. Pulse-chase experiments indicated that gp330 spends a prolonged time maturing in the ER of L2 cells, as transport of gp330 to the Golgi complex (based on acquisition of endoglycosidase H resistance) is slow (t1/2 = 90 to 120 minutes). Gp330 reached the L2 cell surface beginning at 2 hours after synthesis, where it could be detected by cell surface immunoprecipitation. RAP was found to be an N-linked glycoprotein, and it remained endoglycosidase H-sensitive up to 4 hours after synthesis. Co-precipitation and co-sedimentation experiments demonstrated that gp330 and RAP form a large heterodimer (M(r) approximately 669,000) immediately after biosynthesis and are further assembled into a large hetero-oligomer in the ER. These findings demonstrate that the localization and the kinetics of assembly of gp330 and RAP

  6. Expression and T cell recognition of hybrid antigens with amino-terminal domains encoded by Qa-2 region of major histocompatibility complex and carboxyl termini of transplantation antigens.

    PubMed

    Stroynowski, I; Forman, J; Goodenow, R S; Schiffer, S G; McMillan, M; Sharrow, S O; Sachs, D H; Hood, L

    1985-05-01

    Coding potential of the Q6 gene from the Qa-2a region of BALB/c Crgl mice was analyzed by a combination of hybrid class I gene construction and DNA-mediated gene transfer. Recombinant genes were created by exon shuffling of the 5' coding region of the Q6 gene and the 3' coding region of a gene encoding a transplantation antigen (Kd, Dd, or Ld), or the inverse. Some of these hybrid class I genes were expressed in the transfected mouse fibroblasts (L cells). The hybrid class I molecules encoded by the 5' end of the Q6 gene and the 3' end of the Ld gene precipitated as 45,000 mol wt molecules associated with beta 2-microglobulin. The expression of the hybrid proteins indicates that 926 basepairs of the 5' flanking region upstream of the structural Q6 gene contain a promoter that functions as a transcription initiation site in L cells. The 3' portion of the Q6 gene appears to be responsible for the lack of cell surface expression of the intact Q6 and the hybrid Ld/Q6 genes in mouse fibroblasts. Accordingly, this portion of the Q6 class I gene may play a regulatory role in tissue-specific expression. Serological analyses of hybrid Q6 proteins suggested that Q6 may be a structural gene for CR (H-2 crossreactive) antigen found normally on subpopulations of lymphocytes. If this identification is correct, Q6 gene will define a new category of class I genes encoding approximately 40,000 mol wt molecules and carrying a characteristic truncated cytoplasmic tail. Analysis of L cells transfected with Q6 hybrid genes demonstrated also that the cytotoxic T cells specific for Qa-2a region-coded antigens recognize the amino-terminal alpha 1-alpha 2 domain of Q6 fusion products. This recognition can be blocked by anti-Qa-2a alloantiserum and monoclonal antibodies reactive with the alpha 3-beta 2-microglobulin portion of the Q6 hybrids. We propose that the structural requirements for the anti-Qa-2a cytotoxic T lymphocyte-specific epitopes on target molecules are the same as for anti

  7. Physical mapping of the human T-cell antigen receptor (TCR) {beta}-chain gene complex

    SciTech Connect

    Yashim, Y.; So, A.K.

    1994-09-01

    The genetic variation of the TCR loci and their contribution to autoimmune diseases is poorly defined, in direct contrast to the clear examples of disease association with the Class I and II alleles of the major histocompatibility complex. We have therefore started to determine the gene organization and polymorphism of the TCR {beta} locus. Yeast artificial chromosomes (YACs) were used to construct a physical map of the germline human TCR {beta}-chain gene complex. Variable gene (V{beta}) sequences for the 25 known V{beta} subfamilies were amplified by PCR and were used as probes to screen a YAC library. Five positive YACs were identified. YACs designated B3, E11 and H11 of sizes 820, 400 and 600 kbp, respectively, were analyzed for their V{beta} content by pulse-field gel electrophoresis (PFGE). YAC B3 was found to contain all 25 V{beta} subfamilies, E11 for 14 and H11 for 7. B3 was also positive for the constant region genes. Restriction enzyme mapping of B3 located V{beta} and C{beta} gene regions to four Sfi I fragments of 280, 110, 90 and 125 kbp, and was in accordance with published data. The data thus showed that YAC B3 encoded a complete and unrearranged TCR {beta}-gene locus. The map was further resolved by locating restriction sites for Sal I and Bssll II on B3. Fluorescent in situ hybridization to human metaphase chromosomes localized B3 to chromosome 7q35. However, two additional signals were obtained: one attributable to V{beta} orphon cluster on chromosome 9q21; the second to the long arm of chromosome 2. PCR amplification of a chromosome 2 somatic cell hybrid using primers for all 25 V{beta} gene families revealed the signal was not attributable to a second orphon cluster. It is suggested that B3 is a chimeric YAC with an intact TCR {beta} locus flanked by chromosome 2 sequences. The determination of the TCR genomic organization will help extend studies of the role T-cells play in autoimmune diseases.

  8. cAMP prevents TNF-induced apoptosis through inhibiting DISC complex formation in rat hepatocytes

    PubMed Central

    Bhattacharjee, Rajesh; Xiang, Wenpei; Wang, Yinna; Zhang, Xiaoying; Billiar, Timothy R.

    2013-01-01

    Tumor necrosis factor α (TNF) is a pleiotropic proinflammatory cytokine that plays a role in immunity and the control of cell proliferation, cell differentiation, and apoptosis. The pleiotropic nature of TNF is due to the formation of different signaling complexes upon the binding of TNF to its receptor, TNF receptor type 1 (TNFR1). TNF induces apoptosis in various mammalian cells when the cells are co-treated with a transcription inhibitor like actinomycin D (ActD). When TNFR1 is activated, it recruits an adaptor protein, TNF receptor-associated protein with death domain (TRADD), through its cytoplasmic death effector domain (DED). TRADD, in turn, recruits other signaling proteins, including TNF receptor-associated protein 2 (TRAF2) and receptor-associated protein kinase (RIPK) 1, to form a complex. Subsequently, this complex combines with FADD and procaspase-8, converts into a death-inducing signaling complex (DISC) to induce apoptosis. Cyclic AMP (cAMP) is a second messenger that regulates various cellular processes such as cell proliferation, gene expression, and apoptosis. cAMP analogues are reported to act as anti-apoptotic agents in various cell types, including hepatocytes. We found that a cAMP analogue, dibutyryl cAMP (db-cAMP), inhibits TNF + ActD-induced apoptosis in rat hepatocytes. The protein kinase A (PKA) inhibitor KT-5720 reverses this inhibitory effect of cAMP on apoptosis. Cytoprotection by cAMP involves down-regulation of various apoptotic signal regulators like TRADD and FADD and inhibition of caspase-8 and caspase-3 cleavage. We also found that cAMP exerts its affect at the proximal level of TNF signaling by inhibiting the formation of the DISC complex upon the binding of TNF to TNFR1. In conclusion, our study shows that cAMP prevents TNF + ActD-induced apoptosis in rat hepatocytes by inhibiting DISC complex formation. PMID:22634003

  9. A natural IgM antibody does inhibit polyclonal and antigen-specific IgM but not IgG B-cell responses.

    PubMed

    Kiss, K; Uher, F; Gergely, J

    1994-03-01

    Since a B-cell growth-inhibitory natural IgM antibody was identified in the culture supernatants of LPS-stimulated murine splenic B lymphocytes [11], attempts have been made to define other possible functional role(s) of this antibody. Here we show that this regulatory IgM is able to inhibit not only the proliferation of splenic B cells, but also their IgM secretion during LPS-induced polyclonal, as well as antigen (FITC-KLH)-specific antibody responses. In contrast, IgG1 production of hapten (FITC)-specific B cells neither during restimulation with LPS nor in the presence of carrier-specific T lymphocytes in vitro was affected by regulatory IgM. Therefore, whereas newly emerging naive B cells are highly susceptible, IgG-secreting B cells appear to be completely resistant to inactivation by the regulatory IgM autoantibody. PMID:7518418

  10. Complex Living Conditions Impair Behavioral Inhibition but Improve Attention in Rats.

    PubMed

    van der Veen, Rixt; Kentrop, Jiska; van der Tas, Liza; Loi, Manila; van IJzendoorn, Marinus H; Bakermans-Kranenburg, Marian J; Joëls, Marian

    2015-01-01

    Rapid adaptation to changes, while maintaining a certain level of behavioral inhibition is an important feature in every day functioning. How environmental context and challenges in life can impact on the development of this quality is still unknown. In the present study, we examined the effect of a complex rearing environment during adolescence on attention and behavioral inhibition in adult male rats. We also tested whether these effects were affected by an adverse early life challenge, maternal deprivation (MD). We found that animals that were raised in large, two floor Marlau(TM) cages, together with 10 conspecifics, showed improved attention, but impaired behavioral inhibition in the 5-choice serial reaction time task. The early life challenge of 24 h MD on postnatal day 3 led to a decline in bodyweight during adolescence, but did not by itself influence responses in the 5-choice task in adulthood, nor did it moderate the effects of complex housing. Our data suggest that a complex rearing environment leads to a faster adaptation to changes in the environment, but at the cost of lower behavioral inhibition. PMID:26733839

  11. Complex Living Conditions Impair Behavioral Inhibition but Improve Attention in Rats

    PubMed Central

    van der Veen, Rixt; Kentrop, Jiska; van der Tas, Liza; Loi, Manila; van IJzendoorn, Marinus H.; Bakermans-Kranenburg, Marian J.; Joëls, Marian

    2015-01-01

    Rapid adaptation to changes, while maintaining a certain level of behavioral inhibition is an important feature in every day functioning. How environmental context and challenges in life can impact on the development of this quality is still unknown. In the present study, we examined the effect of a complex rearing environment during adolescence on attention and behavioral inhibition in adult male rats. We also tested whether these effects were affected by an adverse early life challenge, maternal deprivation (MD). We found that animals that were raised in large, two floor MarlauTM cages, together with 10 conspecifics, showed improved attention, but impaired behavioral inhibition in the 5-choice serial reaction time task. The early life challenge of 24 h MD on postnatal day 3 led to a decline in bodyweight during adolescence, but did not by itself influence responses in the 5-choice task in adulthood, nor did it moderate the effects of complex housing. Our data suggest that a complex rearing environment leads to a faster adaptation to changes in the environment, but at the cost of lower behavioral inhibition. PMID:26733839

  12. Inhibition of mitochondrial complex II affects dopamine metabolism and decreases its uptake into striatal synaptosomes.

    PubMed

    Cakała, Magdalena; Drabik, Jacek; Kaźmierczak, Anna; Kopczuk, Dorota; Adamczyk, Agata

    2006-01-01

    The mitochondrial toxin, 3-nitropropionic acid (3-NP), is a specific inhibitor of succinate dehydrogenase, complex II in the mitochondrial respiratory chain. The aim of our study was to determine the relationship between inhibition of mitochondrial complex II and dopamine (DA) metabolism and its transport into rat striatal synaptosomes after exposure to 3-NP. The study was carried out using spectrophotometric, radiochemical and HPLC methods. Our data showed that inhibition of succinate dehydrogenase by intraperitoneal (i.p.) injection of 3-NP (cumulated dose 100 mg/kg in 4 days) significantly affected DA metabolism, leading to the accumulation of its metabolites, 3,4-dihydroxylphenylacetic acid (DOPAC) and homovanillic acid (HVA) in the rat striatum. These experimental conditions had no effect on free radical dependent lipid peroxidation in the brain. In vitro experiments revealed that DA and DOPAC significantly decrease lipid peroxidation in the brain homogenate. Moreover, 3-NP significantly inhibited [3H]DA uptake into striatal synaptosomes by specific dopamine transporter (DAT). The scavengers of superoxide radical (O2-) Tempol and Trolox had no effect on DAT function, but the nitric oxide synthase (NOS) inhibitor N w-nitro-L-arginine (100 microM) prevented 3-NP-evoked DAT down-regulation. In summary, our results indicate that inhibition of mitochondrial complex II by 3-NP enhances DA degradation and decreases its uptake into synaptosomes. It is suggested that NO and energy failure are responsible for alteration of the dopaminergic system in the striatum. PMID:17183449

  13. Multi-antigen vaccines based on complex adenovirus vectors induce protective immune responses against H5N1 avian influenza viruses.

    PubMed

    Holman, David H; Wang, Danher; Raja, Nicholas U; Luo, Min; Moore, Kevin M; Woraratanadharm, Jan; Mytle, Nutan; Dong, John Y

    2008-05-19

    There are legitimate concerns that the highly pathogenic H5N1 avian influenza virus could adapt for human-to-human transmission and cause a pandemic similar to the 1918 "Spanish flu" that killed 50 million people worldwide. We have developed pandemic influenza vaccines by incorporating multiple antigens from both avian and Spanish influenza viruses into complex recombinant adenovirus vectors. In vaccinated mice, these vaccines induced strong humoral and cellular immune responses against pandemic influenza virus antigens, and protected vaccinated mice against lethal H5N1 virus challenge. These results indicate that this multi-antigen, broadly protective vaccine may serve as a safer and more effective approach than traditional methods for development of a pandemic influenza vaccine. PMID:18395306

  14. Dharmendra antigen but not integral M. leprae is an efficient inducer of immunostimulant cytokine production by human monocytes, and M. leprae lipids inhibit the cytokine production.

    PubMed

    Nakamura, C; Fukutomi, Y; Kashiwabara, Y; Oomoto, Y; Kojima, M; Hayashi, H; Onozaki, K

    1997-03-01

    Killed integral Mycobacterium leprae, Mitsuda antigen, and chloroform-treated M. leprae, Dharmendra antigen (Dh-Ag), have been used for the classification of leprosy patients based on cell-mediated immunity. Heat-killed M. leprae also were used as a component of the Convit vaccine. Human blood monocytes were stimulated with M. leprae or Dh-Ag and their cytokine-inducing ability was compared. Monocytes were cultured in the presence of fresh human serum because of the efficiency of cytokine induction and the phagocytosis of M. leprae have been shown to be optimal in the presence of fresh serum. M. leprae and Dh-Ag were equally phagocytosed by monocytes. Dh-Ag was more potent than M. leprae in the induction of immunostimulatory/proinflammatory cytokines, interleukin-1 (IL-1), IL-6 and tumor necrosis factor (TNF). In contrast, a comparable level of IL-1ra, an immunosuppressive cytokine, was induced by M. leprae and Dh-Ag. The lipids extracted from M. leprae induced none of these cytokines by monocytes. Nevertheless, when monocytes were pretreated with the lipids followed by stimulation with Dh-Ag, productions of IL-1, IL-6 and TNF were all inhibited in a dose-dependent manner. However, the lipids did not inhibit the cytokine production induced by other stimuli including BCG and lipopolysaccharide. Moreover the lipids did not affect the production of IL-1ra. These results suggest that the lipids from M. leprae are responsible for the poor cytokine-inducing ability of M. leprae, thus favoring their infection. These results also suggest that Dh-Ag rather than integral M. leprae may be useful as a vaccine candidate because Dh-Ag is able to induce a large amount of cytokines from monocytes. PMID:9207755

  15. Inhibition of replicon initiation in human cells following stabilization of topoisomerase-DNA cleavable complexes.

    PubMed Central

    Kaufmann, W K; Boyer, J C; Estabrooks, L L; Wilson, S J

    1991-01-01

    Diploid human fibroblast strains were treated for 10 min with inhibitors of type I and type II DNA topoisomerases, and after removal of the inhibitors, the rate of initiation of DNA synthesis at replicon origins was determined. By alkaline elution chromatography, 4'-(9-acridinylamino)methanesulfon-m-anisidide (amsacrine), an inhibitor of DNA topoisomerase II, was shown to produce DNA strand breaks. These strand breaks are thought to reflect drug-induced stabilization of topoisomerase-DNA cleavable complexes. Removal of the drug led to a rapid resealing of the strand breaks by dissociation of the complexes. Velocity sedimentation analysis was used to quantify the effects of amsacrine treatment on DNA replication. It was demonstrated that transient exposure to low concentrations of amsacrine inhibited replicon initiation but did not substantially affect DNA chainelongation within operating replicons. Maximal inhibition of replicon initiation occurred 20 to 30 min after drug treatment, and the initiation rate recovered 30 to 90 min later. Ataxia telangiectasia cells displayed normal levels of amsacrine-induced DNA strand breaks during stabilization of cleavable complexes but failed to downregulate replicon initiation after exposure to the topoisomerase inhibitor. Thus, inhibition of replicon initiation in response to DNA damage appears to be an active process which requires a gene product which is defective or missing in ataxia telangiectasia cells. In normal human fibroblasts, the inhibition of DNA topoisomerase I by camptothecin produced reversible DNA strand breaks. Transient exposure to this drug also inhibited replicon initiation. These results suggest that the cellular response pathway which downregulates replicon initiation following genotoxic damage may respond to perturbations of chromatin structure which accompany stabilization of topoisomerase-DNA cleavable complexes. PMID:1646393

  16. Inhibition of antigen- and lectin-induced proliferation of rat spleen cells by a Taenia taeniaeformis proteinase inhibitor.

    PubMed Central

    Leid, R W; Suquet, C M; Perryman, L E

    1984-01-01

    Rat splenic lymphocytes, cultured in vitro for 3 days in the presence of a larval cestode proteinase inhibitor, exhibited a marked suppression of proliferation when stimulated with Con A, PHA, PWM and ovalbumin. Reduced responsiveness was observed over a full range of concentrations of Con A (16-fold), PHA (50-fold), PWM (four-fold) and ovalbumin (16-fold). These results indicated that the inhibitory action could not be overcome by increasing the mitogen or antigen doses beyond optimal levels. This suppressive effect disappeared when the Taenia taeniaeformis proteinase inhibitor was added 20 h after the initiation of culture, suggesting that the inhibitor affects lymphocyte blastogenesis during the early stages of lymphocyte activation. PMID:6744668

  17. The Crystal Structure of the SV40 T-Antigen Origin Binding Domain in Complex with DNA

    PubMed Central

    Meinke, Gretchen; Phelan, Paul; Moine, Stephanie; Bochkareva, Elena; Bochkarev, Alexey; Bullock, Peter A; Bohm, Andrew

    2007-01-01

    DNA replication is initiated upon binding of “initiators” to origins of replication. In simian virus 40 (SV40), the core origin contains four pentanucleotide binding sites organized as pairs of inverted repeats. Here we describe the crystal structures of the origin binding domain (obd) of the SV40 large T-antigen (T-ag) both with and without a subfragment of origin-containing DNA. In the co-structure, two T-ag obds are oriented in a head-to-head fashion on the same face of the DNA, and each T-ag obd engages the major groove. Although the obds are very close to each other when bound to this DNA target, they do not contact one another. These data provide a high-resolution structural model that explains site-specific binding to the origin and suggests how these interactions help direct the oligomerization events that culminate in assembly of the helicase-active dodecameric complex of T-ag. PMID:17253903

  18. Relationship between target antigens and major histocompatibility complex (MHC) class II genes in producing two pathogenic antibodies simultaneously

    PubMed Central

    Zakka, L R; Keskin, D B; Reche, P; Ahmed, A R

    2010-01-01

    In this report, we present 15 patients with histological and immunopathologically proven pemphigus vulgaris (PV). After a mean of 80 months since the onset of disease, when evaluated serologically, they had antibodies typical of PV and pemphigoid (Pg). Similarly, 18 patients with bullous pemphigoid (BP) and mucous membrane pemphigoid (MMP) were diagnosed on the basis of histology and immunopathology. After a mean of 60 months since the onset of disease, when their sera were evaluated they were found to have Pg and PV autoantibodies. In both groups of patients the diseases were characterized by a chronic course, which included several relapses and recurrences and were non-responsive to conventional therapy. The major histocompatibility complex class II (MHC II) genes were studied in both groups of patients and phenotypes associated typically with them were observed. Hence, in 33 patients, two different pathogenic autoantibodies were detected simultaneously. The authors provide a computer model to show that each MHC II gene has relevant epitopes that recognize the antigens associated with both diseases. Using the databases in these computer models, the authors present the hypothesis that these two autoantibodies are produced simultaneously due to the phenomena of epitope spreading. PMID:21069937

  19. MAGE-A Cancer/Testis Antigens Inhibit MDM2 Ubiquitylation Function and Promote Increased Levels of MDM4

    PubMed Central

    Marcar, Lynnette; Ihrig, Bianca; Hourihan, John; Bray, Susan E.; Quinlan, Philip R.; Jordan, Lee B.; Thompson, Alastair M.; Hupp, Ted R.; Meek, David W.

    2015-01-01

    Melanoma antigen A (MAGE-A) proteins comprise a structurally and biochemically similar sub-family of Cancer/Testis antigens that are expressed in many cancer types and are thought to contribute actively to malignancy. MAGE-A proteins are established regulators of certain cancer-associated transcription factors, including p53, and are activators of several RING finger-dependent ubiquitin E3 ligases. Here, we show that MAGE-A2 associates with MDM2, a ubiquitin E3 ligase that mediates ubiquitylation of more than 20 substrates including mainly p53, MDM2 itself, and MDM4, a potent p53 inhibitor and MDM2 partner that is structurally related to MDM2. We find that MAGE-A2 interacts with MDM2 via the N-terminal p53-binding pocket and the RING finger domain of MDM2 that is required for homo/hetero-dimerization and for E2 ligase interaction. Consistent with these data, we show that MAGE-A2 is a potent inhibitor of the E3 ubiquitin ligase activity of MDM2, yet it does not have any significant effect on p53 turnover mediated by MDM2. Strikingly, however, increased MAGE-A2 expression leads to reduced ubiquitylation and increased levels of MDM4. Similarly, silencing of endogenous MAGE-A expression diminishes MDM4 levels in a manner that can be rescued by the proteasomal inhibitor, bortezomid, and permits increased MDM2/MDM4 association. These data suggest that MAGE-A proteins can: (i) uncouple the ubiquitin ligase and degradation functions of MDM2; (ii) act as potent inhibitors of E3 ligase function; and (iii) regulate the turnover of MDM4. We also find an association between the presence of MAGE-A and increased MDM4 levels in primary breast cancer, suggesting that MAGE-A-dependent control of MDM4 levels has relevance to cancer clinically. PMID:26001071

  20. Transformation with Oncogenic Ras and the Simian Virus 40 T Antigens Induces Caspase-Dependent Sensitivity to Fatty Acid Biosynthetic Inhibition

    PubMed Central

    Xu, Shihao; Spencer, Cody M.

    2015-01-01

    ABSTRACT Oncogenesis is frequently accompanied by the activation of specific metabolic pathways. One such pathway is fatty acid biosynthesis, whose induction is observed upon transformation of a wide variety of cell types. Here, we explored how defined oncogenic alleles, specifically the simian virus 40 (SV40) T antigens and oncogenic Ras12V, affect fatty acid metabolism. Our results indicate that SV40/Ras12V-mediated transformation of fibroblasts induces fatty acid biosynthesis in the absence of significant changes in the concentration of fatty acid biosynthetic enzymes. This oncogene-induced activation of fatty acid biosynthesis was found to be mammalian target of rapamycin (mTOR) dependent, as it was attenuated by rapamycin treatment. Furthermore, SV40/Ras12V-mediated transformation induced sensitivity to treatment with fatty acid biosynthetic inhibitors. Pharmaceutical inhibition of acetyl-coenzyme A (CoA) carboxylase (ACC), a key fatty acid biosynthetic enzyme, induced caspase-dependent cell death in oncogene-transduced cells. In contrast, isogenic nontransformed cells were resistant to fatty acid biosynthetic inhibition. This oncogene-induced sensitivity to fatty acid biosynthetic inhibition was independent of the cells' growth rates and could be attenuated by supplementing the medium with unsaturated fatty acids. Both the activation of fatty acid biosynthesis and the sensitivity to fatty acid biosynthetic inhibition could be conveyed to nontransformed breast epithelial cells through transduction with oncogenic Ras12V. Similar to what was observed in the transformed fibroblasts, the Ras12V-induced sensitivity to fatty acid biosynthetic inhibition was independent of the proliferative status and could be attenuated by supplementing the medium with unsaturated fatty acids. Combined, our results indicate that specific oncogenic alleles can directly confer sensitivity to inhibitors of fatty acid biosynthesis. IMPORTANCE Viral oncoproteins and cellular mutations

  1. Versatility of using major histocompatibility complex class II dextramers for derivation and characterization of antigen-specific, autoreactive T cell hybridomas.

    PubMed

    Krishnan, Bharathi; Massilamany, Chandirasegaran; Basavalingappa, Rakesh H; Rajasekaran, Rajkumar A; Kuszynski, Charles; Switzer, Barbara; Peterson, Daniel A; Reddy, Jay

    2015-11-01

    Antigen-specific, T cell hybridomas are useful to study the cellular, molecular and functional events, but their generation is a lengthy process. Thus, there is a need to develop robust methods to generate the hybridoma clones rapidly in a short period of time. To this end, we have demonstrated a novel approach using major histocompatibility complex (MHC) class II dextramers to generate T cell hybridomas for an autoantigen, proteolipid protein (PLP) 139-151. Using MHC class II dextramers assembled with PLP 139-151 as screening and sorting tools, we successfully obtained mono antigen-specific clones within seven to eight weeks. In conjunction with other T cell markers, dextramers permitted phenotypic characterization of hybridoma clones for their antigen specificity in a single step by flow cytometry. Importantly, we achieved successful fusions using dextramer(+) cells sorted by flow cytometry as a starting population, resulting in direct identification of multiple antigen-specific clones. Characterization of selected clones led us to identify chemokine receptor, CCR4(+) to be expressed consistently, but their cytokine-producing ability was variable. Our work provides a proof-of principle that the antigen-specific, CD4 T cell hybridoma clones can be generated directly using MHC class II dextramers. The availability of hybridoma clones that bind dextramers may serve as useful tools for various in vitro and in vivo applications. PMID:26268454

  2. Validation of nanodiamond-extracted CFP-10 antigen as a biomarker in clinical isolates of Mycobacterium tuberculosis complex in broth culture media.

    PubMed

    Soo, Po-Chi; Horng, Yu-Tze; Chen, Ai-Ti; Yang, Shih-Chieh; Chang, Kai-Chih; Lee, Jen-Jyh; Peng, Wen-Ping

    2015-09-01

    With detonation nanodiamonds (DNDs) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF MS), we previously identified early secreted cell filtrate protein 10 (CFP-10) as a candidate Mycobacterium tuberculosis complex (MTC) biomarker. The performance of the CFP-10 biomarker was initially evaluated in relatively small mycobacterial samples (n = 42 samples) in our previous study. In this study, we conducted DND MALDI-TOF MS experiments to investigate the specificity and sensitivity of the MTC biomarker with 312 MTC and 52 nontuberculous mycobacteria (NTM) clinical samples. The frequency and intensity of the acquired CFP-10 mass-to-charge (m/z) peaks were checked with a program to validate that the singly and doubly charged CFP-10 antigen can be treated as a MTC biomarker. We confirmed that by detecting the singly charged species of CFP-10 antigen, the sensitivity and the specificity of MTC samples could reach 97.4% and 100% and no CFP-10 biomarker could be found in NTM samples. This indicates with CFP-10 biomarker it is easy to distinguish MTC from NTM. Besides, the observed intensity ratio of singly and doubly charged species of CFP-10 antigen was 3.3 ± 2.6 and the CFP-10 antigen could maintain good signal intensity for a week. Our results suggest that, with the DND MALDI-TOF mass spectrometry approach, CFP-10 antigen can be used as an early diagnosis biomarker in clinical practice. PMID:26071665

  3. Mitochondrial Complex 1 Inhibition Increases 4-Repeat Isoform Tau by SRSF2 Upregulation

    PubMed Central

    De Andrade, Anderson; Höglinger, Günter

    2014-01-01

    Progressive Supranuclear Palsy (PSP) is a neurodegenerative disorder characterised by intracellular aggregation of the microtubule-associated protein tau. The tau protein exists in 6 predominant isoforms. Depending on alternative splicing of exon 10, three of these isoforms have four microtubule-binding repeat domains (4R), whilst the others only have three (3R). In PSP there is an excess of the 4R tau isoforms, which are thought to contribute significantly to the pathological process. The cause of this 4R increase is so far unknown. Several lines of evidence link mitochondrial complex I inhibition to the pathogenesis of PSP. We demonstrate here for the first time that annonacin and MPP+, two prototypical mitochondrial complex I inhibitors, increase the 4R isoforms of tau in human neurons. We show that the splicing factor SRSF2 is necessary to increase 4R tau with complex I inhibition. We also found SRSF2, as well as another tau splicing factor, TRA2B, to be increased in brains of PSP patients. Thereby, we provide new evidence that mitochondrial complex I inhibition may contribute as an upstream event to the pathogenesis of PSP and suggest that splicing factors may represent an attractive therapeutic target to intervene in the disease process. PMID:25402454

  4. Simian virus 40 large T antigen's association with the CUL7 SCF complex contributes to cellular transformation.

    PubMed

    Kasper, Jocelyn S; Kuwabara, Hiroshi; Arai, Takehiro; Ali, Syed Hamid; DeCaprio, James A

    2005-09-01

    Simian virus 40 large T antigen (T Ag) is capable of immortalizing and transforming rodent cells. The transforming activity of T Ag is due in large part to perturbation of the tumor suppressor proteins p53 and the retinoblastoma (pRB) family members. Inactivation of these tumor suppressors may not be sufficient for T Ag-mediated cellular transformation. It has been shown that T Ag associates with an SCF-like complex that contains a member of the cullin family of E3 ubiquitin ligases, CUL7, as well as SKP1, RBX1, and an F-box protein, FBXW8. We identified T Ag residues 69 to 83 as required for T Ag binding to the CUL7 complex. We demonstrate that delta69-83 T Ag, while it lost its ability to associate with CUL7, retained binding to p53 and pRB family members. In the presence of CUL7, wild-type (WT) T Ag but not delta69-83 T Ag was able to induce proliferation of mouse embryo fibroblasts, an indication of cellular transformation. In contrast, WT and delta69-83 T Ag enabled mouse embryo fibroblasts to proliferate to similarly high densities in the absence of CUL7. Our data suggest that, in addition to p53 and the pRB family members, T Ag serves to bind to and inactivate the growth-suppressing properties of CUL7. In addition, these results imply that, at least in the presence of T Ag, CUL7 may function as a tumor suppressor. PMID:16140746

  5. The mammalian exocyst, a complex required for exocytosis, inhibits tubulin polymerization.

    PubMed

    Wang, Sheng; Liu, Yan; Adamson, Crista L; Valdez, Gregorio; Guo, Wei; Hsu, Shu C

    2004-08-20

    The exocyst is a 734-kDa complex essential for development. Perturbation of its function results in early embryonic lethality. Extensive investigation has revealed that this complex participates in multiple biological processes, including protein synthesis and vesicle/protein targeting to the plasma membrane. In this article we report that the exocyst may also play a role in modulating microtubule dynamics. Using monoclonal antibodies, we observed that endogenous exocyst subunits co-localized with microtubules and mitotic spindles in normal rat kidney cells. To test for a functional relationship between the exocyst complex and microtubules, we established an in vitro exocyst reconstitution assay and studied exocyst effect on microtubule dynamics. We found that the exocyst complex reconstituted from eight recombinant exocyst subunits inhibited tubulin polymerization in vitro. Deletion of exocyst subunit sec5, sec6, sec15, or exo70 diminished its tubulin polymerization inhibition activity. Surprisingly, exocyst subunit exo70 itself was also capable of inhibiting tubulin polymerization, although exocyst complex with exo70 deletion did not lose its activity completely. Overexpression of exo70 in NRK cells resulted in microtubule network disruption and the formation of filopodia-like plasma membrane protrusions. The formation of these membrane protrusions was greatly hampered by stabilizing microtubules with taxol. Overexpression of exo84, an exocyst subunit that did not show tubulin polymerization inhibition activity, did not cause this phenotype. Results shown in this article, along with a previous report that localized microtubule instability induces plasma membrane addition, implicates a novel role for the exocyst in modulating microtubule dynamics underlying exocytosis. PMID:15205466

  6. Antigenic sites in carcinoembryonic antigen.

    PubMed

    Hammarstrom, S; Shively, J E; Paxton, R J; Beatty, B G; Larsson, A; Ghosh, R; Bormer, O; Buchegger, F; Mach, J P; Burtin, P

    1989-09-01

    The epitope reactivities of 52 well-characterized monoclonal antibodies (Mabs) against carcinoembryonic antigen from 11 different research groups were studied using competitive solid-phase immunoassays. About 60% of all possible combinations of Mabs as inhibitors and as the primary binding antibody were investigated. The inhibition data were analyzed by a specially developed computer program "EPITOPES" which measures concordance and discordance in inhibition patterns between Mabs. The analysis showed that 43 of the 52 Mabs (83%) could be classified into one of five essentially noninteracting epitope groups (GOLD 1-5) containing between four and 15 Mabs each. The epitopes recognized by the Mabs belonging to groups 1 to 5 were peptide in nature. With one or two possible exceptions non-classifiable Mabs were either directed against carbohydrate epitopes (4 Mabs) or were inactive in the tests used. Within epitope groups GOLD 1, 4, and 5 two partially overlapping subgroups were distinguished. Mabs with a high degree of carcinoembryonic antigen specificity generally belonged to epitope groups GOLD 1 and 3. PMID:2474375

  7. Complex I and complex III inhibition specifically increase cytosolic hydrogen peroxide levels without inducing oxidative stress in HEK293 cells

    PubMed Central

    Forkink, Marleen; Basit, Farhan; Teixeira, José; Swarts, Herman G.; Koopman, Werner J.H.; Willems, Peter H.G.M.

    2015-01-01

    Inhibitor studies with isolated mitochondria demonstrated that complex I (CI) and III (CIII) of the electron transport chain (ETC) can act as relevant sources of mitochondrial reactive oxygen species (ROS). Here we studied ROS generation and oxidative stress induction during chronic (24 h) inhibition of CI and CIII using rotenone (ROT) and antimycin A (AA), respectively, in intact HEK293 cells. Both inhibitors stimulated oxidation of the ROS sensor hydroethidine (HEt) and increased mitochondrial NAD(P)H levels without major effects on cell viability. Integrated analysis of cells stably expressing cytosolic- or mitochondria-targeted variants of the reporter molecules HyPer (H2O2-sensitive and pH-sensitive) and SypHer (H2O2-insensitive and pH-sensitive), revealed that CI- and CIII inhibition increased cytosolic but not mitochondrial H2O2 levels. Total and mitochondria-specific lipid peroxidation was not increased in the inhibited cells as reported by the C11-BODIPY581/591 and MitoPerOx biosensors. Also expression of the superoxide-detoxifying enzymes CuZnSOD (cytosolic) and MnSOD (mitochondrial) was not affected. Oxyblot analysis revealed that protein carbonylation was not stimulated by CI and CIII inhibition. Our findings suggest that chronic inhibition of CI and CIII: (i) increases the levels of HEt-oxidizing ROS and (ii) specifically elevates cytosolic but not mitochondrial H2O2 levels, (iii) does not induce oxidative stress or substantial cell death. We conclude that the increased ROS levels are below the stress-inducing level and might play a role in redox signaling. PMID:26516986

  8. Deep Brain Stimulation: More Complex than the Inhibition of Cells and Excitation of Fibers.

    PubMed

    Florence, Gerson; Sameshima, Koichi; Fonoff, Erich T; Hamani, Clement

    2016-08-01

    High-frequency deep brain stimulation (DBS) is an effective treatment for some movement disorders. Though mechanisms underlying DBS are still unclear, commonly accepted theories include a "functional inhibition" of neuronal cell bodies and the excitation of axonal projections near the electrodes. It is becoming clear, however, that the paradoxical dissociation "local inhibition" and "distant excitation" is far more complex than initially thought. Despite an initial increase in neuronal activity following stimulation, cells are often unable to maintain normal ionic concentrations, particularly those of sodium and potassium. Based on currently available evidence, we proposed an alternative hypothesis. Increased extracellular concentrations of potassium during DBS may change the dynamics of both cells and axons, contributing not only to the intermittent excitation and inhibition of these elements but also to interrupt abnormal pathological activity. In this article, we review mechanisms through which high extracellular potassium may mediate some of the effects of DBS. PMID:26150316

  9. Angiopoietin-like protein 4 inhibition of lipoprotein lipase: evidence for reversible complex formation.

    PubMed

    Lafferty, Michael J; Bradford, Kira C; Erie, Dorothy A; Neher, Saskia B

    2013-10-01

    Elevated triglycerides are associated with an increased risk of cardiovascular disease, and lipoprotein lipase (LPL) is the rate-limiting enzyme for the hydrolysis of triglycerides from circulating lipoproteins. The N-terminal domain of angiopoietin-like protein 4 (ANGPTL4) inhibits LPL activity. ANGPTL4 was previously described as an unfolding molecular chaperone of LPL that catalytically converts active LPL dimers into inactive monomers. Our studies show that ANGPTL4 is more accurately described as a reversible, noncompetitive inhibitor of LPL. We find that inhibited LPL is in a complex with ANGPTL4, and upon dissociation, LPL regains lipase activity. Furthermore, we have generated a variant of ANGPTL4 that is dependent on divalent cations for its ability to inhibit LPL. We show that LPL inactivation by this regulatable variant of ANGPTL4 is fully reversible after treatment with a chelator. PMID:23960078

  10. Lectin-dependent inhibition of antigen-antibody reaction: application for measuring α2,6-sialylated glycoforms of transferrin.

    PubMed

    Hoshi, Kyoka; Kariya, Yoshinobu; Nara, Kiyomitsu; Ito, Hiromi; Matsumoto, Kana; Nagae, Masamichi; Yamaguchi, Yoshiki; Nakajima, Madoka; Miyajima, Masakazu; Arai, Hajime; Kuno, Atsushi; Narimatsu, Hisashi; Shirotani, Keiro; Hashimoto, Yasuhiro

    2013-09-01

    We developed a high-throughput Enzyme-linked immunosorbent assay (ELISA) for measuring α2,6-sialylated transferrin (Tf), based on inhibition of anti-Tf antibody binding to α2,6-sialylated Tf by a lectin, Sambucus sieboldiana Agglutinin (SSA). The inhibition was not observed with other glycoforms, such as periodate-treated, sialidase-treated and sialidase/galactosidase-treated Tf, suggesting that the assay was glycoform specific. This finding was applied to an automated latex-agglutination immunoassay, using SSA lectin as an inhibitor (SSA-ALI). The concentration of α2,6-sialylated Tf measured by SSA-ALI in human cerebrospinal fluid was correlated with that of ELISA (r2 = 0.8554), previously developed for measuring α2,6-sialylated Tf. PMID:23921500

  11. Modified bimolecular fluorescence complementation assay to study the inhibition of transcription complex formation by JAZ proteins.

    PubMed

    Qi, Tiancong; Song, Susheng; Xie, Daoxin

    2013-01-01

    The jasmonate (JA) ZIM-domain (JAZ) proteins of Arabidopsis thaliana repress JA signaling and negatively regulate the JA responses. Recently, JAZ proteins have been found to inhibit the transcriptional function of several transcription factors, among which the basic helix-loop-helix (bHLH) (GLABRA3 [GL3], ENHANCER OF GLABRA3 [EGL3], and TRANSPARENT TESTA8 [TT8]) and R2R3-MYB (GL1 and MYB75) that can interact with each other to form bHLH-MYB complexes and further control gene expression. The bimolecular fluorescence complementation (BiFC) assay is a widely used technique to study protein-protein interactions in living cells. Here we describe a modified BiFC experimental procedure to study the inhibition of the formation of the bHLH (GL3)-MYB (GL1) complex by JAZ proteins. PMID:23615997

  12. Protein encoded by HSV-1 stimulation-related gene 1 (HSRG1) interacts with and inhibits SV40 large T antigen.

    PubMed

    Guo, H X; Cun, W; Liu, L D; Dong, S Z; Wang, L C; Dong, C H; Li, Q H

    2006-12-01

    Herpes simplex virus (HSV)-1 stimulation-related gene 1 (HSRG1) protein expression is induced in HSV-1 infected cells. We found that HSRG1 interacts with SV40 large T antigen (LT) in yeast two-hybrid assay and bimolecular fluorescence complementation (BiFC) assay. This interaction alters LT's regulation of the SV40 promoter and its ability to influence the cell cycle. Choramphenicol acetyl-transferase (CAT) assays revealed that initiation of gene transcription by LT is changed by HSRG1 expression. HSRG1 inhibits the ability of LT to activate SV40 late gene transcription. Further data indicate that the ability of LT protein to stimulate S-phase entry is also inhibited by the expression of HSRG1. The results of a colony-forming assay suggested that expression of HSRG1 in cells transfected by LT gene decreased the rate of colony formation. Yeast two-hybrid beta-galactosidase assay revealed that amino acid residues 132-450 in LT bind HSRG1. PMID:17109635

  13. Inhibition of acid, alkaline, and tyrosine (PTP1B) phosphatases by novel vanadium complexes.

    PubMed

    McLauchlan, Craig C; Hooker, Jaqueline D; Jones, Marjorie A; Dymon, Zaneta; Backhus, Emily A; Greiner, Bradley A; Dorner, Nicole A; Youkhana, Mary A; Manus, Lisa M

    2010-03-01

    In the course of our investigations of vanadium-containing complexes for use as insulin-enhancing agents, we have generated a series of novel vanadium coordination complexes with bidentate ligands. Specifically we have focused on two ligands: anthranilate (anc(-)), a natural metabolite of tryptophan, and imidizole-4-carboxylate (imc(-)), meant to mimic naturally occurring N-donor ligands. For each ligand, we have generated a series of complexes containing the V(III), V(IV), and V(V) oxidation states. Each complex was investigated using phosphatase inhibition studies of three different phosphatases (acid, alkaline, and tyrosine (PTP1B) phosphatase) as prima facia evidence for potential use as an insulin-enhancing agent. Using p-nitrophenyl phosphate as an artificial phosphatase substrate, the levels of inhibition were determined by measuring the absorbance of the product at 405nm using UV/vis spectroscopy. Under our experimental conditions, for instance, V(imc)(3) appears to be as potent an inhibitor of alkaline phosphatase as sodium orthovanadate when comparing the K(cat)/K(m) term. VO(anc)(2) is as potent an inhibitor of acid phosphatase and tyrosine phosphatase as the Na(3)VO(4). Thus, use of these complexes can increase our mechanistic understanding of the effects of vanadium in vivo. PMID:20071031

  14. Cadmium inhibits mismatch repair by blocking the ATPase activity of the MSH2-MSH6 complex.

    PubMed

    Banerjee, Sreeparna; Flores-Rozas, Hernan

    2005-01-01

    Cadmium (Cd2+) is a known carcinogen that inactivates the DNA mismatch repair (MMR) pathway. In this study, we have tested the effect of Cd2+ exposure on the enzymatic activity of the mismatch binding complex MSH2-MSH6. Our results indicate that Cd2+ is highly inhibitory to the ATP binding and hydrolysis activities of MSH2-MSH6, and less inhibitory to its DNA mismatch binding activity. The inhibition of the ATPase activity appears to be dose and exposure time dependent. However, the inhibition of the ATPase activity by Cd2+ is prevented by cysteine and histidine, suggesting that these residues are essential for the ATPase activity and are targeted by Cd2+. A comparison of the mechanism of inhibition with N-ethyl maleimide, a sulfhydryl group inhibitor, indicates that this inhibition does not occur through direct inactivation of sulfhydryl groups. Zinc (Zn2+) does not overcome the direct inhibitory effect of Cd2+ on the MSH2-MSH6 ATPase activity in vitro. However, the increase in the mutator phenotype of yeast cells exposed to Cd2+ was prevented by excess Zn2+, probably by blocking the entry of Cd2+ into the cell. We conclude that the inhibition of MMR by Cd2+ is through the inactivation of the ATPase activity of the MSH2-MSH6 heterodimer, resulting in a dominant negative effect and causing a mutator phenotype. PMID:15746000

  15. The transcriptional corepressor DSP1 inhibits activated transcription by disrupting TFIIA-TBP complex formation.

    PubMed Central

    Kirov, N C; Lieberman, P M; Rushlow, C

    1996-01-01

    Transcriptional repression of eukaryotic genes is essential for many cellular and developmental processes, yet the precise mechanisms of repression remain poorly understood. The Dorsal Switch Protein (DSP1) was identified in a genetic screen for activities which convert Dorsal into a transcriptional repressor. DSP1 shares structural homology with the HMG-1/2 family and inhibits activation by the rel transcription factors Dorsal and NF-kappaB in transfection studies. Here we investigate the mechanism of transcriptional repression by DSP1. We found that DSP1 protein can act as a potent transcriptional repressor for multiple activator families in vitro and in transfection studies. DSP1 bound directly to the TATA binding protein (TBP), and formed a stable ternary complex with TBP bound to DNA. DSP1 preferentially disrupted the DNA binding of TBP complexes containing TFIIA and displaced TFIIA from binding to TBP. Consistent with the inhibition of TFIIA-bound complexes, DSP1 was shown to inhibit activated but not basal transcription reactions in vitro. The ability of DSP1 to interact with TBP and to repress transcription was mapped to the carboxy-terminal domain which contains two HMG boxes. Our results support the model that DSP1 represses activated transcription by interfering with the binding of TFIIA, a general transcription factor implicated in activated transcription pathways. Images PMID:9003783

  16. Wnt signaling through inhibition of β-catenin degradation in an intact Axin1 complex.

    PubMed

    Li, Vivian S W; Ng, Ser Sue; Boersema, Paul J; Low, Teck Y; Karthaus, Wouter R; Gerlach, Jan P; Mohammed, Shabaz; Heck, Albert J R; Maurice, Madelon M; Mahmoudi, Tokameh; Clevers, Hans

    2012-06-01

    Degradation of cytosolic β-catenin by the APC/Axin1 destruction complex represents the key regulated step of the Wnt pathway. It is incompletely understood how the Axin1 complex exerts its Wnt-regulated function. Here, we examine the mechanism of Wnt signaling under endogenous levels of the Axin1 complex. Our results demonstrate that β-catenin is not only phosphorylated inside the Axin1 complex, but also ubiquinated and degraded via the proteasome, all within an intact Axin1 complex. In disagreement with current views, we find neither a disassembly of the complex nor an inhibition of phosphorylation of Axin1-bound β-catenin upon Wnt signaling. Similar observations are made in primary intestinal epithelium and in colorectal cancer cell lines carrying activating Wnt pathway mutations. Wnt signaling suppresses β-catenin ubiquitination normally occurring within the complex, leading to complex saturation by accumulated phospho-β-catenin. Subsequently, newly synthesized β-catenin can accumulate in a free cytosolic form and engage nuclear TCF transcription factors. PMID:22682247

  17. The effect of stable macromolecular complexes of ionic polyphosphazene on HIV Gag antigen and on activation of human dendritic cells and presentation to T-cells.

    PubMed

    Palmer, Christine D; Ninković, Jana; Prokopowicz, Zofia M; Mancuso, Christy J; Marin, Alexander; Andrianov, Alexander K; Dowling, David J; Levy, Ofer

    2014-10-01

    Neonates and infants are susceptible to infection due to distinct immune responses in early life. Therefore, development of vaccine formulation and delivery systems capable of activating human newborn leukocytes is of global health importance. Poly[di(carboxylatophenoxy)phosphazene] (PCPP) belongs to a family of ionic synthetic polyphosphazene polyelectrolyte compounds that can form non-covalent interactions with protein antigens and demonstrate adjuvant activity in animals and in human clinical trials. However, little is known about their ability to activate human immune cells. In this study, we characterized the effects of PCPP alone or in combination with a model antigen (recombinant HIV-Gag (Gag)), on the maturation, activation and antigen presentation by human adult and newborn dendritic cells (DCs) in vitro. PCPP treatment induced DC activation as assessed by upregulation of co-stimulatory molecules and cytokine production. Studies benchmarking PCPP to Alum, the most commonly used vaccine adjuvant, demonstrated that both triggered cell death and release of danger signals in adult and newborn DCs. When complexed with Gag antigen, PCPP maintained its immunostimulatory characteristics while permitting internalization and presentation of Gag by DCs to HIV-Gag-specific CD4(+) T cell clones. The PCPP vaccine formulation outlined here has intrinsic adjuvant activity, can facilitate effective delivery of antigen to DCs, and may be advantageous for induction of beneficial T cell-mediated immunity. Moreover, polyphosphazenes can further reduce cost of vaccine production and distribution through their dose-sparing and antigen-stabilizing properties, thus potentially eliminating the need for cold chain distribution. PMID:25023392

  18. Evolutionary genetics and vector adaptation of recombinant viruses of the western equine encephalitis antigenic complex provides new insights into alphavirus diversity and host switching

    PubMed Central

    Allison, Andrew B.; Stallknecht, David E.; Holmes, Edward C.

    2014-01-01

    Western equine encephalitis virus (WEEV), Highlands J virus (HJV), and Fort Morgan virus (FMV) are the sole representatives of the WEE antigenic complex of the genus Alphavirus, family Togaviridae, that are endemic to North America. All three viruses have their ancestry in a recombination event involving eastern equine encephalitis virus (EEEV) and a Sindbis (SIN)-like virus that gave rise to a chimeric alphavirus that subsequently diversified into the present-day WEEV, HJV, and FMV. Here, we present a comparative analysis of the genetic, ecological, and evolutionary relationships among these recombinant-origin viruses, including the description of a nsP4 polymerase mutation in FMV that allows it to circumvent the host range barrier to Asian tiger mosquito cells, a vector species that is normally refractory to infection. Notably, we also provide evidence that the recombination event that gave rise to these three WEEV antigenic complex viruses may have occurred in North America. PMID:25463613

  19. Diphosphoryl lipid A from Rhodobacter sphaeroides inhibits complexes that form in vitro between lipopolysaccharide (LPS)-binding protein, soluble CD14, and spectrally pure LPS.

    PubMed Central

    Jarvis, B W; Lichenstein, H; Qureshi, N

    1997-01-01

    An early event in septic shock is the activation of macrophages by a complex consisting of lipopolysaccharide (LPS), LPS-binding protein (LBP), and the cell surface antigen CD14. The complexes that form between [3H]ReLPS (ReLPS is deep-rough-chemotype hexacyl LPS from E. coli D31m4), soluble CD14 (sCD14), and LBP were analyzed by two independent methods, native (nondenaturing) gel electrophoresis and size-exclusion high-performance liquid chromatography (HPLC). This is the first reported use of HPLC to purify and study LPS-protein complexes. The binding of [3H]ReLPS to LBP and sCD14 was inhibited by preincubation with diphosphoryl lipid A from Rhodobacter sphaeroides (RsDPLA), a potent LPS antagonist. In addition, [3H]ReLPS bound to LBP and to a truncated form of sCD14 [sCD14(1-152)] that contained the LPS binding domain. Binding to both proteins was blocked by RsDPLA. Thus, RsDPLA competes in a 1:1 ratio for the same or nearby binding sites on ReLPS complexes. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis of aggregated ReLPS eluting from the HPLC indicated that only LBP, not sCD14, was bound to the aggregated ReLPS. This finding supports the binary model of LPS complex formation with LBP and sCD14. PMID:9234747

  20. Inhibition and promotion of tumor growth with adeno-associated virus carcinoembryonic antigen vaccine and Toll-like receptor agonists.

    PubMed

    Triozzi, P L; Aldrich, W; Ponnazhagan, S

    2011-12-01

    Carcinoembryonic antigen (CEA) is a cancer vaccines' target. Several features of recombinant adeno-associated virus (rAAV) are attractive for vaccine applications. Combining other viral vector vaccines with Toll-like receptor (TLR) agonists enhances antitumor immunity. Wild-type and CEA transgenic (Tg) mice were immunized with rAAV-expressing CEA, the TLR9 agonist, oligodinucleotide (ODN)1826 and the TLR7 agonist, imiquimod. Mice were challenged with MC38 colon tumor cells and MC38 cells expressing CEA. rAAV-CEA immunization combined with ODN1826 or imiquimod enhanced CEA-specific T-helper 1 immunity and protected against tumor challenge in wild-type but not in CEA-Tg mice. In contrast, immunization with rAAV-CEA in CEA-Tg mice could abrogate the antitumor effects of ODN1826 and promote tumor growth. Compared to wild-type, CEA-Tg mice were characterized by a greater myeloid suppressor cell and T-helper 2 response to TLR agonists and to syngeneic tumors. Depleting PDCA1(+) plasmacytoid dendritic cells and Gr1(+) myeloid cells increased anti-CEA immune responses in CEA-Tg mice to rAAV-CEA-ODN1826 immunization, whereas depleting CD25(+) T cells did not. There are differences in the response of wild-type and CEA-Tg mice to rAAV-CEA, TLR agonists and syngeneic tumor. In CEA-Tg mice, tumor growth can be promoted with rAAV-CEA and TLR agonists. Dendritic and myeloid cells play a regulatory role. PMID:21869824

  1. Inhibition of cerebral vascular inflammation by brain endothelium-targeted oligodeoxynucleotide complex.

    PubMed

    Hu, Jing; Al-Waili, Daniah; Hassan, Aishlin; Fan, Guo-Chang; Xin, Mei; Hao, Jiukuan

    2016-08-01

    The present study generated a novel DNA complex to specifically target endothelial NF-κB to inhibit cerebral vascular inflammation. This DNA complex (GS24-NFκB) contains a DNA decoy which inhibits NF-κB activity, and a DNA aptamer (GS-24), a ligand of transferrin receptor (TfR), which allows for targeted delivery of the DNA decoy into cells. The results indicate that GS24-NFκB was successfully delivered into a murine brain-derived endothelial cell line, bEND5, and inhibited inflammatory responses induced by tumor necrosis factor α (TNF-α) or oxygen-glucose deprivation/re-oxygenation (OGD/R) via down-regulation of the nuclear NF-κB subunit, p65, as well as its downstream inflammatory cytokines, inter-cellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule (VCAM-1). The inhibitory effect of the GS24-NFκB was demonstrated by a significant reduction in TNF-α or OGD/R induced monocyte adhesion to the bEND5 cells after GS24-NFκB treatment. Intravenous (i.v.) injection of GS24-'NFκB (15mg/kg) was able to inhibit the levels of phoseph-p65 and VCAM-1 in brain endothelial cells in a mouse lipopolysaccharide (LPS)-induced inflammatory model in vivo. In conclusion, our approach using DNA nanotechnology for DNA decoy delivery could potentially be utilized for inhibition of inflammation in ischemic stroke and other neuro-inflammatory diseases affecting cerebral vasculature. PMID:27132231

  2. Inhibiting oral intoxication of botulinum neurotoxin A complex by carbohydrate receptor mimics.

    PubMed

    Lee, Kwangkook; Lam, Kwok-Ho; Kruel, Anna-Magdalena; Mahrhold, Stefan; Perry, Kay; Cheng, Luisa W; Rummel, Andreas; Jin, Rongsheng

    2015-12-01

    Botulinum neurotoxins (BoNTs) cause the disease botulism manifested by flaccid paralysis that could be fatal to humans and animals. Oral ingestion of the toxin with contaminated food is one of the most common routes for botulism. BoNT assembles with several auxiliary proteins to survive in the gastrointestinal tract and is subsequently transported through the intestinal epithelium into the general circulation. Several hemagglutinin proteins form a multi-protein complex (HA complex) that recognizes host glycans on the intestinal epithelial cell surface to facilitate BoNT absorption. Blocking carbohydrate binding to the HA complex could significantly inhibit the oral toxicity of BoNT. Here, we identify lactulose, a galactose-containing non-digestible sugar commonly used to treat constipation, as a prototype inhibitor against oral BoNT/A intoxication. As revealed by a crystal structure, lactulose binds to the HA complex at the same site where the host galactose-containing carbohydrate receptors bind. In vitro assays using intestinal Caco-2 cells demonstrated that lactulose inhibits HA from compromising the integrity of the epithelial cell monolayers and blocks the internalization of HA. Furthermore, co-administration of lactulose significantly protected mice against BoNT/A oral intoxication in vivo. Taken together, these data encourage the development of carbohydrate receptor mimics as a therapeutic intervention to prevent BoNT oral intoxication. PMID:26272706

  3. Campylobacter jejuni binds intestinal H(O) antigen (Fuc alpha 1, 2Gal beta 1, 4GlcNAc), and fucosyloligosaccharides of human milk inhibit its binding and infection.

    PubMed

    Ruiz-Palacios, Guillermo M; Cervantes, Luz Elena; Ramos, Pilar; Chavez-Munguia, Bibiana; Newburg, David S

    2003-04-18

    The most common cause of infant mortality is diarrhea; the most common cause of bacterial diarrhea is Campylobacter jejuni, which is also the primary cause of motor neuron paralysis. The first step in campylobacter pathogenesis is adherence to intestinal mucosa. We found that such binding was inhibited in vitro by human milk and, with high avidity, by alpha1,2-fucosylated carbohydrate moieties containing the H(O) blood group epitope (Fuc alpha 1,2Gal beta 1,4GlcNAc em leader ). In studies on the mechanism of adherence, campylobacter, which normally does not bind to Chinese hamster ovary cells, bound avidly when the cells were transfected with a human alpha1,2-fucosyltransferase gene that caused overexpression of H-2 antigen; binding was specifically inhibited by H-2 ligands (lectins Ulex europaeus and Lotus tetragonolobus and H-2 monoclonal antibody), H-2 mimetics, and human milk oligosaccharides. Human milk oligosaccharides inhibited campylobacter colonization of mice in vivo and human intestinal mucosa ex vivo. Campylobacter colonization of nursing mouse pups was inhibited if their dams had been transfected with a human alpha1,2-fucosyltransferase gene that caused expression of H(O) antigen in milk. We conclude that campylobacter binding to intestinal H-2 antigen is essential for infection. Milk fucosyloligosaccharides and specific fucosyl alpha1,2-linked molecules inhibit this binding and may represent a novel class of antimicrobial agents. PMID:12562767

  4. cAMP prevents TNF-induced apoptosis through inhibiting DISC complex formation in rat hepatocytes

    SciTech Connect

    Bhattacharjee, Rajesh; Xiang, Wenpei; Wang, Yinna; Zhang, Xiaoying

    2012-06-22

    Highlights: Black-Right-Pointing-Pointer cAMP blocks cell death induced by TNF and actinomycin D in cultured hepatocytes. Black-Right-Pointing-Pointer cAMP blocks NF-{kappa}B activation induced by TNF and actinomycin D. Black-Right-Pointing-Pointer cAMP blocks DISC formation following TNF and actinomycin D exposure. Black-Right-Pointing-Pointer cAMP blocks TNF signaling at a proximal step. -- Abstract: Tumor necrosis factor {alpha} (TNF) is a pleiotropic proinflammatory cytokine that plays a role in immunity and the control of cell proliferation, cell differentiation, and apoptosis. The pleiotropic nature of TNF is due to the formation of different signaling complexes upon the binding of TNF to its receptor, TNF receptor type 1 (TNFR1). TNF induces apoptosis in various mammalian cells when the cells are co-treated with a transcription inhibitor like actinomycin D (ActD). When TNFR1 is activated, it recruits an adaptor protein, TNF receptor-associated protein with death domain (TRADD), through its cytoplasmic death effector domain (DED). TRADD, in turn, recruits other signaling proteins, including TNF receptor-associated protein 2 (TRAF2) and receptor-associated protein kinase (RIPK) 1, to form a complex. Subsequently, this complex combines with FADD and procaspase-8, converts into a death-inducing signaling complex (DISC) to induce apoptosis. Cyclic AMP (cAMP) is a second messenger that regulates various cellular processes such as cell proliferation, gene expression, and apoptosis. cAMP analogues are reported to act as anti-apoptotic agents in various cell types, including hepatocytes. We found that a cAMP analogue, dibutyryl cAMP (db-cAMP), inhibits TNF + ActD-induced apoptosis in rat hepatocytes. The protein kinase A (PKA) inhibitor KT-5720 reverses this inhibitory effect of cAMP on apoptosis. Cytoprotection by cAMP involves down-regulation of various apoptotic signal regulators like TRADD and FADD and inhibition of caspase-8 and caspase-3 cleavage. We also found

  5. Differential susceptibility of mitochondrial complex II to inhibition by oxaloacetate in brain and heart.

    PubMed

    Stepanova, Anna; Shurubor, Yevgeniya; Valsecchi, Federica; Manfredi, Giovanni; Galkin, Alexander

    2016-09-01

    Mitochondrial Complex II is a key mitochondrial enzyme connecting the tricarboxylic acid (TCA) cycle and the electron transport chain. Studies of complex II are clinically important since new roles for this enzyme have recently emerged in cell signalling, cancer biology, immune response and neurodegeneration. Oxaloacetate (OAA) is an intermediate of the TCA cycle and at the same time is an inhibitor of complex II with high affinity (Kd~10(-8)M). Whether or not OAA inhibition of complex II is a physiologically relevant process is a significant, but still controversial topic. We found that complex II from mouse heart and brain tissue has similar affinity to OAA and that only a fraction of the enzyme in isolated mitochondrial membranes (30.2±6.0% and 56.4±5.6% in the heart and brain, respectively) is in the free, active form. Since OAA could bind to complex II during isolation, we established a novel approach to deplete OAA in the homogenates at the early stages of isolation. In heart, this treatment significantly increased the fraction of free enzyme, indicating that OAA binds to complex II during isolation. In brain the OAA-depleting system did not significantly change the amount of free enzyme, indicating that a large fraction of complex II is already in the OAA-bound inactive form. Furthermore, short-term ischemia resulted in a dramatic decline of OAA in tissues, but it did not change the amount of free complex II. Our data show that in brain OAA is an endogenous effector of complex II, potentially capable of modulating the activity of the enzyme. PMID:27287543

  6. Dual-targeting organometallic ruthenium(II) anticancer complexes bearing EGFR-inhibiting 4-anilinoquinazoline ligands.

    PubMed

    Zhang, Yang; Zheng, Wei; Luo, Qun; Zhao, Yao; Zhang, Erlong; Liu, Suyan; Wang, Fuyi

    2015-08-01

    We have recently demonstrated that complexation with (η(6)-arene)Ru(II) fragments confers 4-anilinoquinazoline pharmacophores a higher potential for inducing cellular apoptosis while preserving the highly inhibitory activity of 4-anilinoquinazolines against EGFR and the reactivity of the ruthenium centre to 9-ethylguanine (Chem. Commun., 2013, 49, 10224-10226). Reported herein are the synthesis, characterisation and evaluation of the biological activity of a new series of ruthenium(ii) complexes of the type [(η(6)-arene)Ru(N,N-L)Cl]PF6 (arene = p-cymene, benzene, 2-phenylethanol or indane, L = 4-anilinoquinazolines). These organometallic ruthenium complexes undergo fast hydrolysis in aqueous solution. Intriguingly, the ligation of (arene)Ru(II) fragments with 4-anilinoquinazolines not only makes the target complexes excellent EGFR inhibitors, but also confers the complexes high affinity to bind to DNA minor grooves while maintaining their reactivity towards DNA bases, characterising them with dual-targeting properties. Molecular modelling studies reveal that the hydrolysis of these complexes is a favourable process which increases the affinity of the target complexes to bind to EGFR and DNA. In vitro biological activity assays show that most of this group of ruthenium complexes are selectively active inhibiting the EGF-stimulated growth of the HeLa cervical cancer cell line, and the most active complex [(η(6)-arene)Ru(N,N-L13)Cl]PF6 (, IC50 = 1.36 μM, = 4-(3'-chloro-4'-fluoroanilino)-6-(2-(2-aminoethyl)aminoethoxy)-7-methoxyquinazoline) is 29-fold more active than its analogue, [(η(6)-arene)Ru(N,N-ethylenediamine)Cl]PF6, and 21-fold more active than gefitinib, a well-known EGFR inhibitor in use clinically. These results highlight the strong promise to develop highly active ruthenium anticancer complexes by ligation of cytotoxic ruthenium pharmacophores with bioactive organic molecules. PMID:26106875

  7. Monoclonal antibodies directed against major histocompatibility complex antigens bind to the surface of Treponema pallidum isolated from infected rabbits or humans.

    PubMed

    Marchitto, K S; Kindt, T J; Norgard, M V

    1986-09-01

    Evidence is presented for the association of class I major histocompatibility complex (MHC) antigens with the surface of Treponema pallidum during infection. A monoclonal antibody (IgG2a) directed against a murine H-2Kb epitope of public specificity reacted with the cell surface of T. pallidum, as assayed by the binding of protein A-colloidal gold in immunoelectron microscopy. Monoclonal antibodies directed against class I rabbit MHC antigens also reacted in immunofluorescence assays with material on the surface of rabbit-cultivated T. pallidum. In addition, impression smears of human syphilitic genital ulcers that were darkfield-positive for the presence of spirochetes were tested in immunofluorescence assays with monoclonal antibodies directed against human MHC antigens; antibody directed against HLA-ABC (class I) was reactive whereas antibody directed against HLA-DR (class II) was nonreactive. Results of the study suggest that the association of host-derived class I MHC antigens or molecular mimicry may play a role in T. pallidum evasion of host immune defenses. PMID:2428519

  8. Molecular components of the B cell antigen receptor complex of class IgD differ partly from those of IgM.

    PubMed Central

    Wienands, J; Hombach, J; Radbruch, A; Riesterer, C; Reth, M

    1990-01-01

    Two classes of immunoglobulin, IgM and IgD, are present as antigen receptors on the surface of mature B lymphocytes. We show here that IgD molecules are noncovalently associated in the B cell membrane with a heterodimer consisting of two proteins of 35 kd (IgD-alpha) and 39 kd (Ig-beta), respectively. The two novel proteins are not found in the IgD-expressing myeloma J558L delta m, which fails to bring IgD antigen receptor onto the cell surface. In a surface IgD positive variant line of this myeloma, however, membrane-bound IgD molecules are associated with the heterodimer, suggesting that the formation of an antigen receptor complex is required for surface IgD expression. We further demonstrate that the IgD-associated heterodimer differs partly from that of the IgM antigen receptor and that its binding to the heavy chain only requires the presence of the last constant domain and the transmembrane part of the delta m chain. Images Fig. 3. Fig. 5. Fig. 6. Fig. 7. PMID:2303036

  9. Cnn1 inhibits the interactions between the KMN complexes of the yeast kinetochore

    PubMed Central

    Bock, Lucy J.; Pagliuca, Cinzia; Kobayashi, Norihiko; Grove, Ryan A.; Oku, Yusuke; Shrestha, Kriti; Alfieri, Claudio; Golfieri, Cristina; Oldani, Amanda; Maschio, Marianna Dal; Bermejo, Rodrigo; Hazbun, Tony R.; Tanaka, Tomoyuki U.; De Wulf, Peter

    2012-01-01

    Kinetochores attach the replicated chromosomes to the mitotic spindle and orchestrate their transmission to the daughter cells. Kinetochore–spindle binding and chromosome segregation are mediated by the multi-copy KNL1Spc105, MIS12Mtw1 and NDC80Ndc80 complexes that form the so-called KMN network. KMN–spindle attachment is regulated by the Aurora BIpl1 and MPS1Mps1 kinases. It is unclear whether other mechanisms exist that support KMN activity during the cell cycle. Using budding yeast, we show that kinetochore protein Cnn1 localizes to the base of the Ndc80 complex and promotes a functionally competent configuration of the KMN network. Cnn1 regulates KMN activity in a spatiotemporal manner by inhibiting the interaction between its complexes. Cnn1 activity peaks in anaphase and is driven by the Cdc28, Mps1 and Ipl1 kinases. PMID:22561345

  10. Transcutaneous antigen delivery system

    PubMed Central

    Lee, Mi-Young; Shin, Meong-Cheol; Yang, Victor C.

    2013-01-01

    Transcutaneous immunization refers to the topical application of antigens onto the epidermis. Transcutaneous immunization targeting the Langerhans cells of the skin has received much attention due to its safe, needle-free, and noninvasive antigen delivery. The skin has important immunological functions with unique roles for antigen-presenting cells such as epidermal Langerhans cells and dermal dendritic cells. In recent years, novel vaccine delivery strategies have continually been developed; however, transcutaneous immunization has not yet been fully exploited due to the penetration barrier represented by the stratum corneum, which inhibits the transport of antigens and adjuvants. Herein we review recent achievements in transcutaneous immunization, focusing on the various strategies for the enhancement of antigen delivery and vaccination efficacy. [BMB Reports 2013; 46(1): 17-24] PMID:23351379