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Lerner A, Benzvi C, Vojdani A. SARS-CoV-2 Gut-Targeted Epitopes: Sequence Similarity and Cross-Reactivity Join Together for Molecular Mimicry. Biomedicines 2023; 11:1937. [PMID: 37509576 PMCID: PMC10376948 DOI: 10.3390/biomedicines11071937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Revised: 07/02/2023] [Accepted: 07/06/2023] [Indexed: 07/30/2023] Open
Abstract
The gastrointestinal tract can be heavily infected by SARS-CoV-2. Being an auto-immunogenic virus, SARS-CoV-2 represents an environmental factor that might play a role in gut-associated autoimmune diseases. However, molecular mimicry between the virus and the intestinal epitopes is under-investigated. The present study aims to elucidate sequence similarity between viral antigens and human enteric sequences, based on known cross-reactivity. SARS-CoV-2 epitopes that cross-react with human gut antigens were explored, and sequence alignment was performed against self-antigens implicated in enteric autoimmune conditions. Experimental SARS-CoV-2 epitopes were aggregated from the Immune Epitope Database (IEDB), while enteric antigens were obtained from the UniProt Knowledgebase. A Pairwise Local Alignment tool, EMBOSS Matcher, was employed for the similarity search. Sequence similarity and targeted cross-reactivity were depicted between 10 pairs of immunoreactive epitopes. Similar pairs were found in four viral proteins and seven enteric antigens related to ulcerative colitis, primary biliary cholangitis, celiac disease, and autoimmune hepatitis. Antibodies made against the viral proteins that were cross-reactive with human gut antigens are involved in several essential cellular functions. The relationship and contribution of those intestinal cross-reactive epitopes to SARS-CoV-2 or its potential contribution to gut auto-immuno-genesis are discussed.
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Affiliation(s)
- Aaron Lerner
- Chaim Sheba Medical Center, The Zabludowicz Research Center for Autoimmune Diseases, Ramat Gan 52621, Israel
- Research Department, Ariel University, Ariel 40700, Israel
| | - Carina Benzvi
- Chaim Sheba Medical Center, The Zabludowicz Research Center for Autoimmune Diseases, Ramat Gan 52621, Israel
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2
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Czaja AJ. Incorporating the Molecular Mimicry of Environmental Antigens into the Causality of Autoimmune Hepatitis. Dig Dis Sci 2023:10.1007/s10620-023-07967-5. [PMID: 37160542 PMCID: PMC10169207 DOI: 10.1007/s10620-023-07967-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Accepted: 05/01/2023] [Indexed: 05/11/2023]
Abstract
Molecular mimicry between foreign and self-antigens has been implicated as a cause of autoimmune hepatitis in experimental models and cross-reacting antibodies in patients. This review describes the experimental and clinical evidence for molecular mimicry as a cause of autoimmune hepatitis, indicates the limitations and uncertainties of this premise, and encourages investigations that assess diverse environmental antigens as sources of disease-relevant molecular mimics. Pertinent articles were identified in PubMed using multiple search phrases. Several pathogens have linear or conformational epitopes that mimic the self-antigens of autoimmune hepatitis. The occurrence of an acute immune-mediated hepatitis after vaccination for severe acute respiratory syndrome (SARS)-associated coronavirus 2 (SARS-CoV-2) has suggested that vaccine-induced peptides may mimic disease-relevant tissue antigens. The intestinal microbiome is an under-evaluated source of gut-derived antigens that could also engage in molecular mimicry. Chaperone molecules may enhance the pathogenicity of molecular mimics, and they warrant investigation. Molecular mimics of immune dominant epitopes within cytochrome P450 IID6, the autoantigen most closely associated with autoimmune hepatitis, should be sought in diverse environmental antigens and assessed for pathogenicity. Avoidance strategies, dietary adjustments, vaccine improvement, and targeted manipulation of the intestinal microbiota may emerge as therapeutic possibilities. In conclusion, molecular mimicry may be a missing causality of autoimmune hepatitis. Molecular mimics of key immune dominant epitopes of disease-specific antigens must be sought in diverse environmental antigens. The ubiquity of molecular mimicry compels rigorous assessments of peptide mimics for immunogenicity and pathogenicity in experimental models. Molecular mimicry may complement epigenetic modifications as causative mechanisms of autoimmune hepatitis.
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Affiliation(s)
- Albert J Czaja
- Professor Emeritus of Medicine, Mayo Clinic College of Medicine and Science, 200 First Street SW, Rochester, MN, 55905, USA.
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Liu SP, Bian ZH, Zhao ZB, Wang J, Zhang W, Leung PSC, Li L, Lian ZX. Animal Models of Autoimmune Liver Diseases: a Comprehensive Review. Clin Rev Allergy Immunol 2020; 58:252-271. [PMID: 32076943 DOI: 10.1007/s12016-020-08778-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Autoimmune liver diseases (AILDs) are potentially life-threatening chronic liver diseases which include autoimmune hepatitis, primary biliary cholangitis, primary sclerosing cholangitis, and recently characterized IgG4-related sclerosing cholangitis. They are caused by immune attack on hepatocytes or bile ducts, with different mechanisms and clinical manifestations. The etiologies of AILDs include a susceptible genetic background, environment insults, infections, and changes of commensal microbiota, but remain complicated. Understanding of the underlying mechanisms of AILDs is mandatory for early diagnosis and intervention, which is of great importance for better prognosis. Thus, animal models are developed to mimic the pathogenesis, find biomarkers for early diagnosis, and for therapeutic attempts of AILDs. However, no animal models can fully recapitulate features of certain AILD, especially the late stages of diseases. Certain limitations include different living condition, cell composition, and time frame of disease development and resolution. Moreover, there is no IgG4 in rodents which exists in human. Nevertheless, the understanding and therapy of AILDs have been greatly advanced by the development and mechanistic investigation of animal models. This review will provide a comprehensive overview of traditional and new animal models that recapitulate different features and etiologies of distinct AILDs.
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Affiliation(s)
- Shou-Pei Liu
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, Guangdong, China.,Chronic Disease Laboratory, Institutes for Life Sciences and School of Medicine, South China University of Technology, Guangzhou, 510006, China
| | - Zhen-Hua Bian
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, Guangdong, China.,Chronic Disease Laboratory, Institutes for Life Sciences and School of Medicine, South China University of Technology, Guangzhou, 510006, China.,School of Biology and Biological Engineering, South China University of Technology, Guangzhou, 510006, Guangdong, China
| | - Zhi-Bin Zhao
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, Guangdong, China.,Chronic Disease Laboratory, Institutes for Life Sciences and School of Medicine, South China University of Technology, Guangzhou, 510006, China
| | - Jinjun Wang
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, 225127, Jiangsu, China
| | - Weici Zhang
- Division of Rheumatology/Allergy and Clinical Immunology, University of California, Davis, CA, 95616, USA
| | - Patrick S C Leung
- Division of Rheumatology/Allergy and Clinical Immunology, University of California, Davis, CA, 95616, USA
| | - Liang Li
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, Guangdong, China. .,Chronic Disease Laboratory, Institutes for Life Sciences and School of Medicine, South China University of Technology, Guangzhou, 510006, China.
| | - Zhe-Xiong Lian
- Department of General Surgery, Guangzhou Digestive Disease Center, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, Guangzhou, 510180, Guangdong, China. .,Chronic Disease Laboratory, Institutes for Life Sciences and School of Medicine, South China University of Technology, Guangzhou, 510006, China.
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4
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Wang H, Feng X, Yan W, Tian D. Regulatory T Cells in Autoimmune Hepatitis: Unveiling Their Roles in Mouse Models and Patients. Front Immunol 2020; 11:575572. [PMID: 33117375 PMCID: PMC7575771 DOI: 10.3389/fimmu.2020.575572] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 09/07/2020] [Indexed: 12/11/2022] Open
Abstract
Autoimmune hepatitis (AIH) is a severe and chronic liver disease, and its incidence has increased worldwide in recent years. Research into the pathogenesis of AIH remains limited largely owing to the lack of suitable mouse models. The concanavalin A (ConA) mouse model is a typical and well-established model used to investigate T cell-dependent liver injury. However, ConA-induced hepatitis is acute and usually disappears after 48 h; thus, it does not mimic the pathogenesis of AIH in the human body. Several studies have explored various AIH mouse models, but as yet there is no widely accepted and valid mouse model for AIH. Immunosuppression is the standard clinical therapy for AIH, but patient side effects and recurrence limit its use. Regulatory T cells (Tregs) play critical roles in the maintenance of immune homeostasis and in the prevention of autoimmune diseases, which may provide a potential therapeutic target for AIH therapy. However, the role of Tregs in AIH has not yet been clarified, partly because of difficulties in diagnosing AIH and in collecting patient samples. In this review, we discuss the studies related to Treg in various AIH mouse models and patients with AIH and provide some novel insights for this research area.
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Affiliation(s)
- Han Wang
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Xinxia Feng
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Wei Yan
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Dean Tian
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
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Fuchs S, Bayer M, Taubert R, Manns MP, Pfeilschifter JM, Christen U, Hintermann E. Effects of adenovirus-induced hepatocyte damage on chronic bile duct inflammation in a sclerosing cholangitis mouse model. Liver Int 2019; 39:2330-2340. [PMID: 31225929 DOI: 10.1111/liv.14183] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 05/10/2019] [Accepted: 06/15/2019] [Indexed: 12/14/2022]
Abstract
BACKGROUND & AIMS Four major autoimmune diseases target the liver. They develop because of bile duct destruction, leading to chronic cholestasis or result from hepatocyte damage like autoimmune hepatitis (AIH). Interestingly, some patients simultaneously show features of both cholangitis and AIH. Our goal was to mimic such concurrent characteristics in a mouse model that would help deciphering mechanisms possibly involved in an inflammatory crosstalk between cholestatic disease and hepatitis. METHODS Mdr2-/- mice, which spontaneously develop sclerosing cholangitis because of accumulation of toxic bile salts, were infected with adenovirus (Ad) encoding human Cytochrome P4502D6 (hCYP2D6), the major target autoantigen in type-2 AIH, to trigger hepatocyte injury. Wild type FVB mice were controls. RESULTS Resulting Ad-Mdr2-/- mice presented with cholangitis, fibrosis and cellular infiltrations that were higher than in Mdr2-/- or Ad-FVB mice. Increased levels of anti-neutrophil cytoplasmic antibodies but similar anti-hCYP2D6 antibody titres were detected in Ad-Mdr2-/- compared to Mdr2-/- and Ad-FVB mice respectively. IFNγ-expressing hCYP2D6-specific CD4 T cells declined, whereas hCYP2D6-specific CD8 T cells increased in Ad-Mdr2-/- compared to Ad-FVB mice. The overall T cell balance in Ad-Mdr2-/- mice was a combination of a type 17 T cell response typically found in Mdr2-/- mice with a type 1 dominated T cell response characteristic for Ad-FVB mice. Simultaneously, the type 2 T cell compartment was markedly reduced. CONCLUSIONS Experimental hepatitis induction in a mouse with sclerosing cholangitis results in a disorder which represents not simply the sum of the individual characteristics but depicts a more complex entity which urges on further analysis.
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Affiliation(s)
- Sina Fuchs
- Pharmazentrum Frankfurt / ZAFES, Goethe University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Monika Bayer
- Pharmazentrum Frankfurt / ZAFES, Goethe University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Richard Taubert
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Michael P Manns
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, Germany
| | - Josef M Pfeilschifter
- Pharmazentrum Frankfurt / ZAFES, Goethe University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Urs Christen
- Pharmazentrum Frankfurt / ZAFES, Goethe University Hospital Frankfurt, Frankfurt am Main, Germany
| | - Edith Hintermann
- Pharmazentrum Frankfurt / ZAFES, Goethe University Hospital Frankfurt, Frankfurt am Main, Germany
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Wang H, Feng X, Han P, Lei Y, Xia Y, Tian D, Yan W. The JAK inhibitor tofacitinib ameliorates immune‑mediated liver injury in mice. Mol Med Rep 2019; 20:4883-4892. [PMID: 31638166 PMCID: PMC6854585 DOI: 10.3892/mmr.2019.10750] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Accepted: 08/08/2019] [Indexed: 12/18/2022] Open
Abstract
The prevalence of immune-mediated liver diseases such as autoimmune liver disease or viral hepatitis has increased in recent years, and the side effects of pre-existing treatments are a worldwide problem. Regulatory T cells (Tregs) and T helper 17 (Th17) cells play important roles in the development of immune-mediated hepatitis and may serve as potential therapeutic targets. Tofacitinib, a new Janus kinase (JAK) inhibitor, is under investigation for the treatment of rheumatoid arthritis; it is also helpful in treating ulcerative colitis and psoriasis. The roles of tofacitinib were investigated in conferring protection against immune-mediated liver injury in mice. T cell-mediated hepatitis was induced by concanavalin A (ConA). The mice in the treatment groups were administered with tofacitinib intragastrically before the ConA injection. Histopathological examination was performed by hematoxylin and eosin (H&E) staining, and the serum transaminase and inflammatory cytokine levels were determined using an automatic biochemistry analysis apparatus or cytometric bead array (CBA) kits. Flow cytometric analysis was used to detect Tregs and Th17 cells. Tofacitinib significantly decreased the hepatic injury induced by ConA and prominently decreased the liver transaminase level. The secretion of several anti-inflammatory cytokines such as interleukin (IL)-10 was upregulated in mice from the treatment group, compared to that in mice treated with ConA alone, while the expression of interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) decreased. Tofacitinib treatment increased the number of Tregs and reduced the number of Th17 cells. Furthermore, tofacitinib could relieve liver fibrosis under conditions of autoimmune hepatitis (AIH). The present results indicated that tofacitinib improved immune-mediated hepatitis and restored the impaired Treg/Th17 cell ratio, which suggests that it may serve as a novel treatment approach for immune-mediated liver diseases.
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Affiliation(s)
- Han Wang
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Xinxia Feng
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Ping Han
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Yu Lei
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Yujia Xia
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Dean Tian
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
| | - Wei Yan
- Department of Gastroenterology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, P.R. China
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7
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Affiliation(s)
- Albert J. Czaja
- Professor Emeritus of Medicine, Mayo Clinic College of Medicine, Rochester, MN, USA
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8
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He ZX, Chen XW, Zhou ZW, Zhou SF. Impact of physiological, pathological and environmental factors on the expression and activity of human cytochrome P450 2D6 and implications in precision medicine. Drug Metab Rev 2015; 47:470-519. [PMID: 26574146 DOI: 10.3109/03602532.2015.1101131] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
With only 1.3-4.3% in total hepatic CYP content, human CYP2D6 can metabolize more than 160 drugs. It is a highly polymorphic enzyme and subject to marked inhibition by a number of drugs, causing a large interindividual variability in drug clearance and drug response and drug-drug interactions. The expression and activity of CYP2D6 are regulated by a number of physiological, pathological and environmental factors at transcriptional, post-transcriptional, translational and epigenetic levels. DNA hypermethylation and histone modifications can repress the expression of CYP2D6. Hepatocyte nuclear factor-4α binds to a directly repeated element in the promoter of CYP2D6 and thus regulates the expression of CYP2D6. Small heterodimer partner represses hepatocyte nuclear factor-4α-mediated transactivation of CYP2D6. GW4064, a farnesoid X receptor agonist, decreases hepatic CYP2D6 expression and activity while increasing small heterodimer partner expression and its recruitment to the CYP2D6 promoter. The genotypes are key determinants of interindividual variability in CYP2D6 expression and activity. Recent genome-wide association studies have identified a large number of genes that can regulate CYP2D6. Pregnancy induces CYP2D6 via unknown mechanisms. Renal or liver diseases, smoking and alcohol use have minor to moderate effects only on CYP2D6 activity. Unlike CYP1 and 3 and other CYP2 members, CYP2D6 is resistant to typical inducers such as rifampin, phenobarbital and dexamethasone. Post-translational modifications such as phosphorylation of CYP2D6 Ser135 have been observed, but the functional impact is unknown. Further functional and validation studies are needed to clarify the role of nuclear receptors, epigenetic factors and other factors in the regulation of CYP2D6.
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Affiliation(s)
- Zhi-Xu He
- a Guizhou Provincial Key Laboratory for Regenerative Medicine, Stem Cell and Tissue Engineering Research Center & Sino-US Joint Laboratory for Medical Sciences, Guizhou Medical University , Guiyang , Guizhou , China
| | - Xiao-Wu Chen
- b Department of General Surgery , The First People's Hospital of Shunde, Southern Medical University , Shunde , Foshan , Guangdong , China , and
| | - Zhi-Wei Zhou
- c Department of Pharmaceutical Science , College of Pharmacy, University of South Florida , Tampa , FL , USA
| | - Shu-Feng Zhou
- a Guizhou Provincial Key Laboratory for Regenerative Medicine, Stem Cell and Tissue Engineering Research Center & Sino-US Joint Laboratory for Medical Sciences, Guizhou Medical University , Guiyang , Guizhou , China .,c Department of Pharmaceutical Science , College of Pharmacy, University of South Florida , Tampa , FL , USA
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Czaja AJ. Transitioning from Idiopathic to Explainable Autoimmune Hepatitis. Dig Dis Sci 2015; 60:2881-900. [PMID: 25999246 DOI: 10.1007/s10620-015-3708-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Accepted: 05/06/2015] [Indexed: 02/08/2023]
Abstract
Autoimmune hepatitis lacks an identifiable cause, and its diagnosis requires the exclusion of etiologically defined diseases that resemble it. Insights into its pathogenesis are moving autoimmune hepatitis from an idiopathic to explainable disease, and the goal of this review is to describe the insights that are hastening this transition. Two types of autoimmune hepatitis are justified by serological markers, but they also have distinctive genetic associations (DRB1 and DQB1 genes) and autoantigens. DRB1 alleles are the principal susceptibility factors in white adults, and a six amino acid sequence encoded in the antigen-binding groove of class II molecules of the major histocompatibility complex can influence the selection of autoantigens. Polymorphisms, including variants of SH2B3 and CARD10 genes, may affect immune reactivity and disease severity. The cytochrome mono-oxygenase, CYP2D6, is the autoantigen associated with type 2 autoimmune hepatitis, and it shares homologies with multiple viruses that might promote self-intolerance by molecular mimicry. Chemokines, especially CXCL9 and CXCL10, orchestrate the migration of effector cells to sites of injury and are associated with disease severity. Cells of the innate and adaptive immune responses promote tissue damage, and possible deficiencies in the number and function of regulatory T cells may facilitate the injurious process. Receptor-mediated apoptosis is the principal mechanism of hepatocyte loss, and cell-mediated and antibody-dependent mechanisms of cytotoxicity also contribute. Insights that explain autoimmune hepatitis will allow triggering exogenous antigens to be characterized, risk management to be improved, prognostic indices to be refined, and site-specific therapeutic interventions to emerge.
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Affiliation(s)
- Albert J Czaja
- Professor Emeritus of Medicine, Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN, 55905, USA.
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Alexandropoulos K, Bonito AJ, Weinstein EG, Herbin O. Medullary thymic epithelial cells and central tolerance in autoimmune hepatitis development: novel perspective from a new mouse model. Int J Mol Sci 2015; 16:1980-2000. [PMID: 25603179 PMCID: PMC4307344 DOI: 10.3390/ijms16011980] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2014] [Accepted: 01/07/2015] [Indexed: 02/07/2023] Open
Abstract
Autoimmune hepatitis (AIH) is an immune-mediated disorder that affects the liver parenchyma. Diagnosis usually occurs at the later stages of the disease, complicating efforts towards understanding the causes of disease development. While animal models are useful for studying the etiology of autoimmune disorders, most of the existing animal models of AIH do not recapitulate the chronic course of the human condition. In addition, approaches to mimic AIH-associated liver inflammation have instead led to liver tolerance, consistent with the high tolerogenic capacity of the liver. Recently, we described a new mouse model that exhibited spontaneous and chronic liver inflammation that recapitulated the known histopathological and immunological parameters of AIH. The approach involved liver-extrinsic genetic engineering that interfered with the induction of T-cell tolerance in the thymus, the very process thought to inhibit AIH induction by liver-specific expression of exogenous antigens. The mutation led to depletion of specialized thymic epithelial cells that present self-antigens and eliminate autoreactive T-cells before they exit the thymus. Based on our findings, which are summarized below, we believe that this mouse model represents a relevant experimental tool towards elucidating the cellular and molecular aspects of AIH development and developing novel therapeutic strategies for treating this disease.
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Affiliation(s)
- Konstantina Alexandropoulos
- Department of Medicine and Clinical Immunology, the Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1089, New York, NY 10029, USA.
| | - Anthony J Bonito
- Department of Medicine and Clinical Immunology, the Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1089, New York, NY 10029, USA.
| | - Erica G Weinstein
- Department of Medicine and Clinical Immunology, the Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1089, New York, NY 10029, USA
| | - Olivier Herbin
- Department of Medicine and Clinical Immunology, the Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1089, New York, NY 10029, USA.
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Luong KVQ, Nguyen LTH. The role of vitamin d in autoimmune hepatitis. J Clin Med Res 2013; 5:407-15. [PMID: 24171052 PMCID: PMC3808258 DOI: 10.4021/jocmr1505w] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/18/2013] [Indexed: 12/21/2022] Open
Abstract
Autoimmune hepatitis is an inflammation of the liver characterized by the presence of peri-portal hepatitis, hypergammaglobulinemia, and the serum autoantibodies. The disease is classified into 2 distinct types according to the nature of auto-antibodies. Disturbances of the calcium-parathyroid hormone-vitamin D axis are frequently associated with chronic liver disease. Patients with AIH have a high prevalence of vitamin D deficiency. Genetic studies have provided the opportunity to determine which proteins link vitamin D to AIH pathology, namely, the major histocompatibility complex class II molecules, vitamin D receptors, toll-like receptors, cytotoxic T lymphocyte antigen-4, cytochrome P450 CYP2D6, regulatory T cells (Tregs) and the forkhead/winged helix transcription factor 3. Vitamin D also exerts its effect on AIH through non-genomic factors, namely, mitogen-activated protein kinase signaling pathways, γδT cells, interferon-gamma nitric oxide synthase, and reactive oxygen stress. In conclusion, vitamin D may have a beneficial role in AIH and improves liver function in concanavalin A-induced mouse AIH. Calcitriol is best used for AIH because it is the active form of a vitamin D3 metabolite and its receptors are present in sinusoidal endothelial cells, Kupffer cells, stellate cells of normal livers, and the biliary cell line.
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Hintermann E, Ehser J, Bayer M, Pfeilschifter JM, Christen U. Mechanism of autoimmune hepatic fibrogenesis induced by an adenovirus encoding the human liver autoantigen cytochrome P450 2D6. J Autoimmun 2013; 44:49-60. [PMID: 23809878 DOI: 10.1016/j.jaut.2013.05.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 05/06/2013] [Accepted: 05/09/2013] [Indexed: 01/03/2023]
Abstract
Autoimmune hepatitis type 2 (AIH-2) is a severe autoimmune liver disease with unknown etiology. We recently developed the CYP2D6 mouse model for AIH-2, in which mice are challenged with an adenovirus (Ad-2D6) expressing human cytochrome P450 2D6 (hCYP2D6), the major autoantigen in AIH-2. Such mice develop chronic hepatitis with cellular infiltrations and generation of hCYP2D6-specific antibodies and T cells. Importantly, the CYP2D6 model represents the only model displaying chronic fibrosis allowing for a detailed investigation of the mechanisms of chronic autoimmune-mediated liver fibrogenesis. We found that hCYP2D6-dependent chronic activation of hepatic stellate cells (HSC) resulted in an increased extracellular matrix deposition and elevated expression of α-smooth muscle actin predominantly in and underneath the liver capsule. The route of Ad-2D6 infection dramatically influenced the activation and trafficking of inflammatory monocytes, NK cells and hCYP2D6-specific T cells. Intraperitoneal Ad-2D6 infection caused subcapsular fibrosis and persistent clustering of inflammatory monocytes. In contrast, intravenous infection caused an accumulation of hCYP2D6-specific CD4 T cells throughout the liver parenchyma and induced a strong NK cell response preventing chronic HSC activation and fibrosis. In summary, we found that the location of the initial site of inflammation and autoantigen expression caused a differential cellular trafficking and activation and thereby determined the outcome of AIH-2-like hepatic damage and fibrosis.
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Affiliation(s)
- Edith Hintermann
- Pharmazentrum Frankfurt/ZAFES, Johann Wolfgang Goethe University, Frankfurt am Main, Germany
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13
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Liu Y, Meyer C, Xu C, Weng H, Hellerbrand C, ten Dijke P, Dooley S. Animal models of chronic liver diseases. Am J Physiol Gastrointest Liver Physiol 2013; 304:G449-68. [PMID: 23275613 DOI: 10.1152/ajpgi.00199.2012] [Citation(s) in RCA: 139] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Chronic liver diseases are frequent and potentially life threatening for humans. The underlying etiologies are diverse, ranging from viral infections, autoimmune disorders, and intoxications (including alcohol abuse) to imbalanced diets. Although at early stages of disease the liver regenerates in the absence of the insult, advanced stages cannot be healed and may require organ transplantation. A better understanding of underlying mechanisms is mandatory for the design of new drugs to be used in clinic. Therefore, rodent models are being developed to mimic human liver disease. However, no model to date can completely recapitulate the "corresponding" human disorder. Limiting factors are the time frame required in humans to establish a certain liver disease and the fact that rodents possess a distinct immune system compared with humans and have different metabolic rates affecting liver homeostasis. These features account for the difficulties in developing adequate rodent models for studying disease progression and for testing new pharmaceuticals to be translated into the clinic. Nevertheless, traditional and new promising animal models that mimic certain attributes of chronic liver diseases are established and being used to deepen our understanding in the underlying mechanisms of distinct liver diseases. This review aims at providing a comprehensive overview of recent advances in animal models recapitulating different features and etiologies of human liver diseases.
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Affiliation(s)
- Yan Liu
- Department of Medicine II, Section Molecular Hepatology-Alcohol Associated Diseases, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany
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Czaja AJ. Diagnosis, pathogenesis, and treatment of autoimmune hepatitis after liver transplantation. Dig Dis Sci 2012; 57:2248-66. [PMID: 22562533 DOI: 10.1007/s10620-012-2179-3] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2012] [Accepted: 04/12/2012] [Indexed: 02/06/2023]
Abstract
Autoimmune hepatitis can recur or appear de novo after liver transplantation, and it can result in hepatic fibrosis, graft loss, and re-transplantation. The goals of this review are to describe the prevalence, manifestations, putative pathogenic mechanisms, outcomes, and management of these occurrences. Autoimmune hepatitis recurs in 8-12 % of transplanted patients at 1 year and 36-68 % at 5 years. Recurrence may be asymptomatic and detected only by surveillance liver test abnormalities or protocol liver tissue examination. Autoantibodies that characterized the original disease, hypergammaglobulinemia, increased serum immunoglobulin G level, and histological findings of interface hepatitis, lymphoplasmacytic infiltration, perivenular hepatocyte necrosis, pseudo-rosetting, and acidophil bodies typify recurrence. Premature corticosteroid withdrawal and pre-transplant severity of the original disease are possible risk factors. De novo autoimmune hepatitis occurs in 1-7 % of patients 0.1-9 years after transplantation, especially in children. The appearance of autoantibodies may herald its emergence, and antibodies to glutathione-S-transferase T1 have been predictive of the disease. Recurrent disease may reflect recruitment of residual memory T lymphocytes and host-specific genetic predispositions, whereas de novo disease may reflect an allo-antigenic immune response and molecular mimicries that override self-tolerance. Treatment should be appropriate for autoimmune hepatitis and not based on anti-rejection drugs. Corticosteroid therapy alone or combined with azathioprine is the essential treatment. The substitution of mycophenolate mofetil for azathioprine and switch of the calcineurin inhibitor or its replacement with rapamycin have also been used for refractory disease. Re-transplantation has been necessary in 8-23 %.
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Affiliation(s)
- Albert J Czaja
- Division of Gastroenterology and Hepatology, Mayo Clinic College of Medicine, 200 First Street S.W., Rochester, MN 55905, USA.
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Wang HX, Liu M, Weng SY, Li JJ, Xie C, He HL, Guan W, Yuan YS, Gao J. Immune mechanisms of Concanavalin A model of autoimmune hepatitis. World J Gastroenterol 2012; 18:119-25. [PMID: 22253517 PMCID: PMC3257438 DOI: 10.3748/wjg.v18.i2.119] [Citation(s) in RCA: 197] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Revised: 07/06/2011] [Accepted: 07/13/2011] [Indexed: 02/06/2023] Open
Abstract
As a chronic inflammatory disease of the liver, the pa-thogenic mechanisms of autoimmune hepatitis (AIH) have not yet been elucidated, with prognosis and diagnosis remaining unsatisfied. Currently the only viable treatments of AIH are immunosuppressant application and liver transplantation. It is considered that lack of good animal AIH models is the main reason for the shortage of a simple and efficient cure. The Concanavalin A (Con A) model is a typical and well established model for investigating T-cell and macrophage dependent liver injury in mice, which closely mimics the pathogenesis mechanisms and pathological changes of patients, and is regarded as the best experimental model for AIH research so far. In this paper we elucidated the pathogenic mechanisms of AIH and the evolution of relative animal models. We go on to further focus on Con A-induced liver injury from the point of immunological mechanisms and the change of cytokine levels. Finally, we manifested the clinical significance of the AIH animal models and the challenges they would meet during their future development.
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Xiang D, Xia Q, Chen D, Feng X, Zhao Y, Liu Y, Liao H, Liu Y, Li N, Yan H. Detection of D-3-phosphoglycerate dehydrogenase autoantibodies in patients with autoimmune hepatitis: Clinical significance evaluation. Hepatol Res 2011; 41:867-76. [PMID: 21707887 DOI: 10.1111/j.1872-034x.2011.00839.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
AIM D-3-phosphoglycerate dehydrogenase (3-PHGDH) was identified as a putative target of autoantibodies in autoimmune hepatitis (AIH). The aims of the present study were to detect anti-3-PHGDH in patients with AIH and other chronic liver diseases and to analyze their clinical relevance. METHODS Human 3-PHGDH gene was cloned and expressed in Escherichia coli and used in enzyme-linked immunosorbent assays and Western blots. Serum from patients with AIH (n = 101), primary biliary cirrhosis (PBC, n = 122), chronic hepatitis C (CHC, n = 117), chronic hepatitis B (CHB, n = 112), and from patients with other autoimmune disease (n = 125) were investigated. RESULTS The highest incidence and activity of anti-PHGDH was observed in AIH patients. Thirty-two of 40 untreated (80%) and 37 of 61 AIH patients treated with corticosteroid (60.7%) were positive. Antibody titers decreased significantly during corticosteroid treatment. 15.8% of PBC patients, 9.8% of CHB and 12.8% of CHC patients, were anti-PHGDH-positive, with less than 12% of patients positive with other autoimmune diseases via reactions with recombinant 3-PHGDH protein. CONCLUSION Anti-PHGDH were detected in chronic liver diseases. They occur predominantly in AIH, and corticosteroid treatment seems to decrease antibody titers. Whether the antibodies are primary or secondary phenomena and whether they are related to the etiology or pathogenesis, at least in a subgroup of patients with chronic liver diseases, has still to be evaluated.
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Affiliation(s)
- Daijun Xiang
- Clinical Research Center for Autoimmune Liver Disease of Beijing You'an Hospital, Capital Medical University Department of Molecular Immunology, Institute of Basic Medical Sciences STD/AIDS Research Center, Beijing You'an Hospital, Capital Medical University Department of Clinical Laboratory Medicine, Chinese People's Liberation Army General Hospital, Beijing, China
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Muratori L, Muratori P, Granito A, Pappas G, Cassani F, Lenzi M. Current topics in autoimmune hepatitis. Dig Liver Dis 2010; 42:757-64. [PMID: 20615766 DOI: 10.1016/j.dld.2010.05.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2010] [Revised: 05/23/2010] [Accepted: 05/31/2010] [Indexed: 12/11/2022]
Abstract
Autoimmune hepatitis is a chronic liver disease of unknown aetiology characterized by interface hepatitis, hypergammaglobulinaemia and circulating autoantibodies. In the last decade a number of advancements have been made in the field of clinical and basic research: the simplified diagnostic criteria, the complete response defined as normalization of transaminase levels, the molecular identification of the antigenic targets of anti-liver cytosol antibody type 1 and anti-soluble liver antigen, the detection of anti-actin antibodies, the description of de novo autoimmune hepatitis after liver transplantation for non-autoimmune liver diseases, the characterization of autoimmune hepatitis with overlapping features of primary biliary cirrhosis or primary sclerosing cholangitis, the preliminary experience with novel treatment strategies based on cyclosporine, mycophenolate mofetil and budesonide, the role played by "impaired" regulatory T cells and the development of novel animal models of autoimmune hepatitis.
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Affiliation(s)
- Luigi Muratori
- Department of Clinical Medicine, Alma Mater Studiorum - University of Bologna, Policlinico Sant'Orsola-Malpighi, Padiglione 11, Bologna, Italy.
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Abstract
Animal models of autoimmune hepatitis have been important in defining pathogenic mechanisms, and they promise to aid in the evaluation of new molecular and cellular treatments. They have evolved from models based on crude liver homogenates that produced a transient hepatitis to models that express antibodies to human antigens, manifest liver-infiltrating T cells, persist for at least 3 months and develop fibrosis. Animal models allow the study of autoimmune hepatitis from its inception, and they can detail the progression of pathological events. Key imbalances in counter-regulatory mechanisms can be isolated and manipulated. Models can be humanized by the insertion of human genetic promoters and the expression of human antigens. Genetic engineering and preconditioning have been milestones in the evolution of animal models. Vaccination or infection of murine models with viral vectors carrying human antigens are the most recent developments. Animal models promise to extend the knowledge of etiological agents and improve treatment algorithms.
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Affiliation(s)
- Albert J Czaja
- Mayo Clinic College of Medicine, 200 First Street SW, Rochester, MN 55905, USA.
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