Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019158 (hepatitis)
 30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Theiler's murine encephalomyelitis virus (TMEV) is a picornavirus which induces a chronic demyelinating disease of the central nervous system (CNS) in certain susceptible mouse strains. Demyelination has been shown to result from immunopathological responses mediated by CD4+, major histocompatibility complex (MHC) class II-restricted T cells. As little or no class II is expressed in the normal mouse CNS, the ability of astrocytes to express these proteins and present antigen to T cells from TMEV-infected mice was investigated here. It is shown that astrocytes are capable of presenting TMEV to virus-specific T cells in vitro, and that this ability is dependent on prior induction of MHC class II by interferon-gamma (IFN-gamma) treatment. Unlike other viruses such as murine hepatitis virus-JHM (a coronavirus) and measles, TMEV is not capable of inducing class II on astrocytes directly. There is a correlation between the ease of class II induction on astrocytes from different mouse strains by IFN-gamma and mouse strain susceptibility to TMEV-induced demyelinating disease. These results suggest that following viral infection and initial T-cell infiltration into the CNS, class II induction on astrocytes is a key step allowing local antigen presentation and amplification of immunopathological responses within the CNS and hence the development of demyelinating disease.
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PMID:Susceptibility to Theiler's virus-induced demyelinating disease correlates with astrocyte class II induction and antigen presentation. 162 91

Toxic agents may induce immunological manifestations by interfering with either non specific or specific pathways of immunity. The interference with the specific pathways may result in stimulatory (autoimmunity or hypersensitivity) or suppressive reactions. Mechanisms responsible for autoimmunity of hypersensitivity are now better understood. Hypersensitive reaction may be the consequence of the recognition by T cells of the xenobiotic presented by MHC class II molecules. Mechanisms leading to autoimmune reaction probably differ according to the nature of the drug. Thus drugs metabolized by liver enzymes could induce autoimmune hepatitis as a consequence of the binding of a reactive metabolite to the enzyme, thus rendered immunogenic. Other drugs like thiol or metal-containing chemicals could be responsible for autoimmunity reaction by interacting with molecules involved in T-B lymphocyte cooperation. The knowledge of the involved mechanisms should allow to develop predictive assays.
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PMID:[Manifestation of immunologic origin produced by toxic compounds]. 178 2

A flow cytometric phenotype for isolated adult central nervous system (CNS) ramified microglia was previously defined (CD45low CD11b/c+) in the Lewis strain rat, that clearly distinguished these cells from all blood-derived leucocytes, the latter being CD45high. Consistent with the reported lack of major histocompatibility complex (MHC) expression in the CNS, isolated microglia were mostly MHC class II-. Employing these phenotypic criteria, we now show that a proportion of microglia in Brown Norway (BN) strain rats are constitutively MHC class II+. In spinal cord, up to 25% of microglia are distinctly positive and most have some level of expression. In situ staining of MHC class II+ microglial cells in BN rats indicates that positive cells are typical of ramified microglia on the grounds of both morphological appearance and anatomical location. In Lewis (LEW) rats, the few MHC class II-expressing cells isolated from the normal CNS are CD45high blood-derived cells and not resident microglia. After infection of both LEW and BN rats with a neurotropic murine hepatitis virus (MHV-JHM), MHC class II was rapidly upregulated on microglia in the BN but not in the LEW strain. In the latter, inflammatory cells were the predominant MHC class II-expressing population. Nevertheless, most microglia in the LEW strain could, after some delay, be induced to express MHC class II after transfer of an experimental autoimmune encephalomyelitis (EAE)-inducing encephalitogenic T cell line. Paradoxically, strains resistant to EAE (exemplified by the BN) contained more constitutive MHC class II-expressing microglia than susceptible ones, when a variety of strains were examined. The results clearly establish that the normal CNS may contain MHC class II-expressing cells that are a resident rather than a transient blood-derived population. It is significant that this expression is strain related, but there is no evidence that microglial cell constitutive MHC class II expression predisposes to EAE susceptibility.
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PMID:Resident macrophages (ramified microglia) of the adult brown Norway rat central nervous system are constitutively major histocompatibility complex class II positive. 845 8

Demyelination in multiple sclerosis and in animal models is associated with infiltrating CD8+ and CD4+ T cells. Although oligodendrocytes and axons are damaged in these diseases, the roles T cells play in the demyelination process are not completely understood. Antigen-specific CD8+ T cell lysis of target cells is dependent on interactions between the T cell receptor and major histocompatibility complex (MHC) class I-peptide complexes on the target cell. In the normal central nervous system, expression of MHC molecules is very low but often increases during inflammation. We set out to precisely define which central nervous system cells express MHC molecules in vivo during infection with a strain of murine hepatitis virus that causes a chronic, inflammatory demyelinating disease. Using double immunofluorescence labeling, we show that during acute infection with murine hepatitis virus, MHC class I is expressed in vivo by oligodendrocytes, neurons, microglia, and endothelia, and MHC class II is expressed only by microglia. These data indicate that oligodendrocytes and neurons have the potential to present antigen to T cells and thus be damaged by direct antigen-specific interactions with CD8+ T lymphocytes.
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PMID:In vivo expression of major histocompatibility complex molecules on oligodendrocytes and neurons during viral infection. 1158 48

A significant CD4+ T cell response against the transmembrane (M) protein can be detected in the spleens of C57Bl/6 mice infected intraperitoneally with a sublethal injection of the neurotropic JHM strain of mouse hepatitis virus (MHV-JHM), but not in those of mice with the chronic demyelinating encephalomyelitis caused by this virus. With the ultimate goal of determining the role of the M-specific response in the pathogenesis of MHV-JHM-induced neurological diseases, CD4+ T cell epitopes within the M protein were identified using vaccinia virus recombinants expressing truncated forms of the protein and peptides spanning most of the M protein in cell proliferation assays. Peptides covering residues 128-147 contain at least one CD4+ T cell epitope for MHV-JHM. Within this region is a sequence (residues 135-143) which matches the recently described MHC class II I-Ab binding motif. Delineation of this epitope should facilitate analysis of the role of the M-specific CD4+ T cell response in the development of acute and chronic neurological infections caused by MHV-JHM.
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PMID:Identification of a CD4+ T cell epitope within the M protein of a neurotropic coronavirus. 1183 97

The ability to activate CD4 T cells is restricted to antigen-presenting cells that express major histocompatibility complex (MHC) class II molecules. Parenchymal cells normally do not express MHC class II molecules; however, in clinical hepatitis, viral or autoimmune, hepatocytes often exhibit aberrant MHC class II expression. It is not known whether MHC class II-expressing hepatocytes can function as antigen-presenting cells, but it has been suggested that aberrant MHC class II expression by parenchymal cells may cause autoimmune disease. Therefore, we generated transgenic mice that specifically overexpress class II transactivator molecules in hepatocytes. Hepatocytes from these mice exhibited stable MHC class II expression and were used to stimulate CD4 T cells from T-cell receptor transgenic mice and CD4 T-cell lines. MHC II-expressing hepatocytes featured costimulatory CD80 molecules and could serve as antigen-presenting cells that were able to process protein antigen and to activate specific CD4 T cells. Nevertheless, the transgenic mice with aberrant hepatocellular MHC class II expression did not exhibit any symptoms of autoimmune disease. In conclusion, MHC II-expressing hepatocytes, as found in clinical hepatitis, can present antigen and activate CD4 T cells. The ability of hepatocytes to present antigen on MHC II molecules does not seem to be a sufficient cause for inflammatory autoimmunity and hepatitis. However, we still need to explore whether such antigen presentation is occurring in vivo. The transgenic mice described in this study may serve as a model to study the immune interaction of hepatocytes and CD4 T cells in both in vitro and in vivo.
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PMID:MHC class II-expressing hepatocytes function as antigen-presenting cells and activate specific CD4 T lymphocyutes. 1271 88

The functions of resident antigen-presenting cells (APC) may be compromised in inflammatory microenvironment of the host. However, little is known regarding the phenotype and function of the liver resident APC in this condition. This issue was addressed by evaluating the function of liver dendritic cells (DC) from mice with concanavalin-A-induced experimental hepatitis. In sharp contrast to normal mice, the expressions of MHC class II and CD86 antigens were not upregulated on liver DC from mice with hepatitis due to interactions with specific antigens like hepatitis B surface antigen and keyhole limpet hemocyanin. Accordingly, these DC were completely unable to induce proliferation of antigen-specific memory lymphocytes. Moreover, liver DC from mice with hepatitis produced significantly lower levels of interleukin-12 and interferon-gamma compared with those from control mice. The lack of antigen internalization capacity of liver DC from mice with hepatitis was evident from their low endocytosis capacity. These data indicate that impaired antigen capturing and T cell activating capacity of liver DC may contribute to low magnitude of antigen-specific immune responses in mice with experimental hepatitis.
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PMID:Inability of liver dendritic cells from mouse with experimental hepatitis to process and present specific antigens. 1278 6

Major histocompatibility complex (MHC) class II antigen expression in hepatocytes and its correlation with mononuclear cell infiltration into the liver were studied using immunohistochemical techniques in 38 Dobermans with Doberman hepatitis (DH). Liver biopsy samples were obtained from 18 dogs at the subclinical stage. Autopsy samples were taken from 6 DH dogs euthanized for a reason other than DH, from 14 dogs euthanized because of advanced liver failure and from 6 control Dobermans. Upon examination of the control liver samples, no expression of MHC class II antigens was detected in hepatocytes. By contrast, in 15 of the 18 DH biopsies (83%) and in all 20 DH autopsy liver samples, hepatocytes expressed MHC class II molecules. MHC class II expression was either cytoplasmic or membranous and occurred in conjunction with lymphocyte infiltration. A correlation between the inflammatory reaction and the expression of MHC class II in hepatocytes suggests that the aberrant expression of MHC class II in hepatocytes is induced by cytokines. Hepatocytes presenting a putative MHC class II molecule-associated autoantigen could thus become the target of an immune attack mediated by CD4+ T cells. In addition, corticosteroid treatment was observed to significantly decrease MHC class II expression in DH hepatocytes. Inappropriate MHC class II expression in hepatocytes and mononuclear cell infiltration are suggesting an autoimmune nature for chronic hepatitis in Dobermans.
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PMID:Upregulation of major histocompatibility complex class II antigens in hepatocytes in Doberman hepatitis. 1452 29

This study evaluates the cross-reactivity of seven anti-human and one anti-bovine antibodies in formalin-fixed, paraffin-embedded tissue samples of liver and mesenteric lymph nodes of 13 striped dolphins (Stenella coeruleoalba). Four antibodies (CD3, IgG, lysozyme and S100 protein) reacted with striped dolphin lymph nodes in a similar pattern to that observed in the species of origin. The anti-human MHC class II mAb reacted strongly with macrophages and dendritic-like cells of striped dolphins, whereas a small number of lymphocytes were labelled with this antibody. These antibodies were used to study the immunophenotype of the inflammatory infiltrated in non-specific chronic reactive hepatitis (eight cases) and chronic parasite cholangitis (two cases) and normal liver (three cases) of striped dolphins. Non-specific chronic reactive hepatitis was composed of inflammatory infiltration of CD3+ T lymphocytes and IgG+ plasma cells in portal spaces and hepatic sinusoids. Lymphonodular aggregates observed in chronic parasitic cholangitis showed a cellular distribution similar to that found in lymph node cortex, including the presence of S100+ and MHC class II+ dendritic-like cells in lymphoid follicles and interfollicular areas. This result suggests that those inflammatory infiltrates are highly organised to enhance antigen presentation to B and T cells.
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PMID:Cross-reactivity of human and bovine antibodies in striped dolphin paraffin wax-embedded tissues. 1452 35

Hepatitis C virus (HCV) causes non-A, non-B hepatitis and infects an estimated 170 million people worldwide. The treatment for HCV infection is often unsuccessful with high costs and many side-effects. There is a great need for alternative therapies including preventive and therapeutic vaccination for HCV infection. The experiments in this study were carried out to elucidate whether endogenously expressed antigen can be presented to helper T-cells restricted by class II molecules and to determine whether responses to plasmid-derived antigen resemble those that we have reported for recombinant antigens or synthetic peptides. To address these issues, a multi-epitope minigene was expressed in 293T-cells and Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cells (BLCL). The transfected BLCLs were employed as APCs to stimulate epitope-specific T-cell hybridomas (THC). The results demonstrated that the endogenously expressed minigene antigens could be processed and presented to T-cell hybridomas by HLA matched BLCL. Five out of seven incorporated epitopes were recognized. Blockade of HLA DR could abolish the release of IL-2, which demonstrated that the endogenously expressed minigene antigens were presented by MHC class II molecules. The presentation of endogenously expressed antigens was much more efficient than that of exogenous antigens, at least in the present study. The findings obtained here have important significance for the development of an HCV DNA vaccine.
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PMID:Recognition of endogenously synthesized HLA-DR4 restricted HCV epitopes presented by autologous EBV transformed B-lymphoblastoid cell line. 1560 98


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