UMLS:C0019158 - FACTA Search

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Query: UMLS:C0019158 (hepatitis)
30,205 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Prednisone alone or a lower dose of prednisone in combination with azathioprine induces remission and enhances survival in autoimmune hepatitis. Treatment failure, incomplete response, drug-induced side effects, and relapse after drug withdrawal are unsatisfactory outcomes that justify the search for new therapies. Potent new drugs promise greater blanket immunosuppression than current regimens, and insights into the pathogenic mechanisms of the disease make site-specific interventions possible. Cyclosporine and tacrolimus are calcineurin inhibitors that impair the transcription of interleukin 2, reduce the expression of cytokines, and diminish T lymphocyte proliferation. Mycophenolate mofetil antagonizes the synthesis of purines and depletes stores of guanine nucleotides necessary for DNA synthesis and expansion of T cell clones. Controlled clinical trials are warranted to establish the role of these new drugs in the treatment of autoimmune hepatitis. Promising site-specific therapies include peptides that competitively block autoantigen presentation, agents such as cytotoxic T lymphocyte antigen 4 that inhibit the second co-stimulatory signal of immunocyte activation, T cell vaccination, oral tolerance therapy, and cytokine manipulation with monoclonal antibodies and recombinant supplements. Confident animal models of experimental autoimmune hepatitis are necessary to mature these interventions. In conclusion, promising immunosuppressive agents that alter cytokine expression and T lymphocyte proliferation may be of value in the treatment of autoimmune hepatitis. Critical mechanisms of immunocyte activation, cytotoxic T cell expansion, and cytokine modulation are the targets of site-specific interventions.
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PMID:Emerging treatments for autoimmune hepatitis. 1456 Nov 79

Human formiminotransferase-cyclodeaminase (hFTCD) is the autoantigen recognized by anti-liver cytosol type 1 (LC1) autoantibodies in type 2 autoimmune hepatitis (AIH) patients. In rats, this octameric protein is localized on the Golgi apparatus and binds brain microtubules (MTs) and vimentin. Subcellular localization of human formiminotransferase-cyclodeaminase and its implication in the pathogenesis of autoimmune hepatitis are unknown. Localization of the human formiminotransferase-cyclodeaminase in human hepatocytes was done using indirect immunofluorescence and subcellular fractionations followed by in vitro binding techniques. The formiminotransferase-cyclodeaminase antigen at two distinct locations in hepatocytes, free in the cytosol and associated with the Golgi membranes are recognized by anti-liver cytosol type 1 autoantibodies. The human formiminotransferase-cyclodeaminase binds reversibly to the Golgi membranes and this complex formation is increased by anti-liver cytosol type 1 autoantibodies. Finally, human formiminotransferase-cyclodeaminase does not interact with liver-specific cytoskeleton proteins. Anti-liver cytosol type 1 autoantibodies are directed against the mature high molecular form of human formiminotransferase-cyclodeaminase. Therefore, the subcellular location of the protein may influence the production of autoantibodies and their role in the pathogenesis of type 2 autoimmune hepatitis. This antigen-driven response does not appear to be facilitated or enhanced by a possible interaction between human formiminotransferase-cyclodeaminase and hepatocyte cytoskeleton proteins.
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PMID:Characterization of the antigenicity of the formiminotransferase-cyclodeaminase in type 2 autoimmune hepatitis. 1469 41

A role for viruses in autoimmune hepatitis (AH) has been repeatedly proposed but convincing evidence links only two viruses, hepatitis A and Epstein-Barr virus, to the type 1 form of the disease, and only in those rare cases where a genetic predisposition exists and the viral infection occurs at the right time, i.e. when other unknown factors are cooperating. In spite of an impressive amount of information conclusively showing molecular mimicry between cytochrome P450IID6 (the target autoantigen of autoantibodies characteristic of AH type 2) sequences and viral (hepatitis C virus, herpes simplex virus 1, cytomegalovirus, human T lymphotropic viruses 1 and 2) or bacterial (Salmonella typhimurium) antigens, no infectious agent is clearly able to induce this second form of the disease. In conclusion, the molecular mimicry theory has so far found little clinical evidence in its support and many more clinical observations are needed in order to unreveal possible links between viruses and AH.
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PMID:Is there a role for viruses in triggering autoimmune hepatitis? 1487 51

Autoimmune hepatitis (AIH) is an inflammatory disease of unknown cause characterized by periportal hepatitis, increased serum globulins and the presence of certain antibodies. The disorder can be classified in three types. Type 1 AIH is characterized by the presence of antinuclear antibodies (ANA) and smooth muscle autoantibodies (SMA) in up to 70-80% of patients. ANA and SMA can be the only antibodies present in 13 and 33% of cases respectively. Type 2 AIH is defined by the presence of liver and kidney antimicrosomal antibodies (LKM1). Type 2 AIH is the only form of the disease in which the autoantigen has been identified: cytochrome mono-oxygenase (P-450 IID6) CYP2D6. In type 3 AIH the presence of anti-SLA/LP (soluble liver antigen/liver pancreas) targets a cytosolic protein involved in the incorporation of selenocysteine into peptidic chains. The pathophysiology of AIH is complex and involves genetic predisposition, previous exposure to antigens (autoantigens), presence of triggering factors and defects in immunoregulation. In spite of the advances in the understanding of AIH, the role of autoantibodies in the pathophysiology of this disease has not been fully established and their presence does not clearly distinguish any prognostic groups. Further investigations will help in the diagnosis of this disorder, the comprehension of its origins and the establishment of new forms of treatment.
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PMID:[Antibodies and physiopathogeny of autoimmune hepatitis]. 1496 79

The features of autoantibodies (autoAb) to liver fumarylacetoacetate hydrolase (FAH) elicited in mice infected with mouse hepatitis virus (MHV) were studied by ELISA and western-blot competition assays. All sera tested contained Ab to cryptic FAH epitopes according with results from western-blot tests, whereas ELISA data indicated that some of these same sera did recognize native epitopes of the autoantigen (autoAg). Such differences were detected in individual sera from various mouse strains, and were ascribed to the fact that proteins insolubilized on solid supports expose a variety of conformational and cryptic antigenic determinants. On the other hand, whereas results from both experimental protocols showed that anti-MHV Ab did not cross-react with the soluble autoAg, the opposite situation did not show analogous results. Thus, binding of autoAb to insolubilized FAH could be inhibited by MHV depending on the mouse serum or the experimental protocol used. Additionally, a set of synthetic homologous peptides from mouse FAH and various viral proteins was employed to analyze the Ab repertoire of MHV-infected mice. Results indicated that two homologous peptides were recognized by most Ab: the N-terminal sequences (1-10) from FAH and the nucleocapside, both sharing 50% of identity, and sequence 2317-2326 of the RNA polymerase, a peptide showing 30% of identity with FAH 11-20. Results indicated that MHV-infection triggers at least three distinct Ab populations: anti-MHV, anti-FAH and cross-reacting Ab. This cross-reaction implies either sequential or conformational epitopes from both the viral proteins and the autoAg and may differ between individuals.
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PMID:Sequence similarity and structural homologies are involved in the autoimmune response elicited by mouse hepatitis virus A59. 1532 30

Autoimmune hepatitis (AIH) is a chronic necroinflammatory disease of the liver characterized by hypergammaglobulinemia, characteristic autoantibodies, association with HLA DR3 or DR4 and a favorable response to immunosuppressive treatment. The etiology is unknown. The detection of non-organ and liver-related autoantibodies remains the hallmark for the diagnosis of the disease in the absence of viral, metabolic, genetic, and toxic etiology of chronic hepatitis or hepatic injury. The current classification of AIH and the several autoantibodies/target-autoantigens found in this disease are reported. Current aspects on the significance of these markers in the differential diagnosis and the study of pathogenesis of AIH are also stated. AIH is subdivided into two major types; AIH type 1 (AIH-1) and type 2 (AIH-2). AIH-1 is characterized by the detection of smooth muscle autoantibodies (SMA) and/or antinuclear antibodies (ANA). Determination of antineutrophil cytoplasmic autoantibodies (ANCA), antibodies against the asialoglycoprotein receptor (anti-ASGP-R) and antibodies against to soluble liver antigens or liver-pancreas (anti-SLA/LP) may be useful for the identification of patients who are seronegative for ANA/SMA. AIH-2 is characterized by the presence of specific autoantibodies against liver and kidney microsomal antigens (anti-LKM type 1 or infrequently anti-LKM type 3) and/or autoantibodies against liver cytosol 1 antigen (anti-LC1). Anti-LKM-1 and anti-LKM-3 autoantibodies are also detected in some patients with chronic hepatitis C (HCV) and chronic hepatitis D (HDV). Cytochrome P450 2D6 (CYP2D6) has been documented as the major target-autoantigen of anti-LKM-1 autoantibodies in both AIH-2 and HCV infection. Recent convincing data demonstrated the expression of CYP2D6 on the surface of hepatocytes suggesting a pathogenetic role of anti-LKM-1 autoantibodies for the liver damage. Family 1 of UDP-glycuronosyltransferases has been identified as the target-autoantigen of anti-LKM-3. For these reasons the distinction between AIH and chronic viral hepatitis (especially of HCV) is of particular importance. Recently, the molecular target of anti-SLA/LP and anti-LC1 autoantibodies were identified as a 50 kDa UGA-suppressor tRNA-associated protein and a liver specific enzyme, the formiminotransferase cyclodeaminase, respectively. Anti-ASGP-R and anti-LC1 autoantibodies appear to correlate closely with disease severity and response to treatment suggesting a pathogenetic role of these autoantibodies for the hepatocellular injury. In general however, autoantibodies should not be used to monitor treatment, predict AIH activity or outcome. Finally, the current aspects on a specific form of AIH that may develop in some patients with a rare genetic syndrome, the autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy syndrome (APECED) are also given. Autoantibodies against liver microsomes (anti-LM) are the specific autoantibodies detected in AIH as a disease component of APECED but also in cases of dihydralazine-induced hepatitis. Cytochrome P450 1A2 has been identified as the target-autoantigen of anti-LM autoantibodies in both APECED-related AIH and dihydralazine-induced hepatitis. The latter may indicate that similar autoimmune pathogenetic mechanisms can lead to liver injury in susceptible individuals irrespective of the primary defect. Characterization of the autoantigen-autoantibody repertoire continues to be an attractive and important tool to get access to the correct diagnosis and to gain insight into the as yet unresolved mystery of how hepatic tolerance is given up and AIH ensues.
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PMID:Autoantibodies and autoantigens in autoimmune hepatitis: important tools in clinical practice and to study pathogenesis of the disease. 1567 7

Autoimmune hepatitis (AIH) is a disease of unknown etiology, characterized by liver-related autoantibodies. Autoimmune hepatitis is subdivided into two major types: AIH type 1 is characterized by the detection of ANA, SMA, ANCA, anti-ASGP-R, and anti-SLA/LP. Autoimmune hepatitis type 2 is characterized to be mainly related with drug-metabolizing enzymes as autoantigens, such as anti-LKM (liver-kidney microsomal antigen)-1 against CYP2D6, anti-LKM-2 against CYP2C9-tienilic acid, anti-LKM-3 against UGT1A, and anti-LC1 (liver cytosol antigen)-1 and anti-APS (autoimmune polyglandular syndrome type-1) against CYP1A2, CYP2A6, and others. Anti-LKM-1 sera inhibited CYP2D6 activity in vitro but did not inhibit cellular drug metabolism in vivo. CYP2D6 is the major target autoantigen of LKM-1 and expressed on plasma membrane (PM) of hepatocytes, suggesting a pathogenic role for anti-LKM-1 in liver injury as a trigger. Anti-CYP1A2 was observed in dihydralazine-induced hepatitis, and radiolabeled CYP1A2 disappeared from the PM with a half-life of less than 30 min, whereas microsomal CYP1A2 was stably radiolabeled for several hours. Main antigenic epitopes on CYP2D6 are aa 193-212, aa 257-269, and aa 321-351; and D263 is essential. The third epitope is located on the surface of the protein CYP2D6 and displays a hydrophobic patch that is situated between an aromatic residue (W316) and histidine (H326). Some drugs such as anticonvulsants (phenobarbital, phenytoin, and carbamazepine) and halothane are suggested to induce hepatitis with anti-CYP3A and anti-CYP2E1, respectively. Autoantibodies against CYP11A1, CYP17, and/or CYP21 involved in the synthesis of steroid hormones are also detected in patients with adrenal failure, gonadal failure, and/or Addison disease.
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PMID:Autoantibodies against CYP2D6 and other drug-metabolizing enzymes in autoimmune hepatitis type 2. 1574 2

Troglitazone is a thiazolidinedione antidiabetic agent with insulin-sensitizing activities that was withdrawn from the market in 2000 due to its association with idiosyncratic hepatotoxicity. To address the suspected autoantibody production associated with troglitazone, we investigated autoantibodies in sera from patients with type II diabetes mellitus with troglitazone-induced liver dysfunction. Two female patients (47- and 70-year-old) ceased taking troglitazone (400 mg/day) after 23.5 and 16 weeks, respectively, due to increased serum ALT. Using two-dimensional electrophoresis and amino acid sequence analyses, aldolase B was identified as an autoantigen that reacted with antibodies in sera from both patients. The titer of anti-aldolase B remained high for several weeks after stopping troglitazone administration. The mean reactivity of autoantibodies to aldolase B determined by ELISA with sera of patients with chronic hepatitis (n = 40) and liver cirrhosis (n = 40) was significantly higher (p < 0.05 and p < 0.001, respectively) than with sera of healthy subjects (n = 80). These findings suggest that liver injury may cause the appearance of autoantibodies to aldolase B which may then aggravate the hepatitis. In addition, the anti-aldolase B titer might indicate the severity of liver dysfunction.
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PMID:Detection of autoantibody to aldolase B in sera from patients with troglitazone-induced liver dysfunction. 1611 20

Liver-kidney microsomal antibodies type 1 (LKM-1) are a diagnostic marker for autoimmune hepatitis type II (AIH-II). However, LKM autoantibodies are also detected in a small percentage of patients with chronic hepatitis C. The autoantigen to anti-LKM-1 has been identified to be CYP2D6. To identify the specific antigenic site of CYP2D6 for LKM-1 serum, we established an ELISA with peptides spanning the entire sequence of CYP2D6. Human CYP2D6 containing histidine tag was expressed in Escherichia coli. Purified CYP2D6 was digested by lysyl endopeptidase. The linker including the histidine tag has a lysine residue in its C-terminal and can be removed by digestion. Digested peptides were separated by reversed-phase HPLC and coated on ELISA plates chemically with glutaraldehyde. The immunoreactivity of two LKM-1-positive sera (HCV-negative) and five HCV-positive sera from Japanese patients was investigated with the plates. These sera recognized peptides 1-146, 181-214, 246-281, 284-391, and 412-429. The peptide 1-146 was recognized by LKM-1-positive sera but not HCV-positive sera and is a new epitope found in this study. Seven short peptides spanning peptide 1-146 were synthesized and ELISAs were conducted with these peptides. However, two sera recognized none of these peptides, suggesting that two LKM-1-positive sera recognize the conformational immunogenic site of peptide 1-146.
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PMID:A new epitope of CYP2D6 recognized by liver kidney microsomal autoantibody from japanese patients with autoimmune hepatitis. 1632 57

The treatment of autoimmune hepatitis is evolving as the pathogenic pathways that underlie the disease are defined, new immunosuppressive agents are tested, and site-specific molecular interventions become feasible. Prednisone alone or at a reduced dose combined with azathioprine is the conventional treatment. Patients with HLA genotype DRB1*0301 have a poorer treatment response and a more frequent need for liver transplantation than those with HLA genotype DRB1*0401. Therapy to the point when liver test results and histological findings are normal reduces, but does not eliminate, the occurrence of relapse. Treatment failure warrants reassessment with regard to the accuracy of the original diagnosis and the exclusion of variant forms of hepatitis or concomitant alternative diseases. Ciclosporin might be effective as short-term, front-line therapy in infants and adults, and calcineurin inhibitors might salvage patients who are refractory to corticosteroid regimens. Mycophenolate mofetil can induce an improvement in laboratory test results and reduce the requirement for corticosteroids. Sirolimus is effective for treatment of de novo autoimmune hepatitis that develops after liver transplantation. Synthetic peptides that block autoantigen presentation, cytokine manipulations, oral tolerance regimens, T-cell vaccination, and gene therapy are all interventions that will be able to emerge after a reliable animal model of the human disease has been developed.
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PMID:Current therapy for autoimmune hepatitis. 1740 88

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