Animal Models of Primary Biliary Cirrhosis

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primary biliary cirrhosis (PBC) with antimitochondrial antibodies (AMAs) and immune- mediated biliary duct pathology have been reported. Here, the authors ...
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Animal Models of Primary Biliary Cirrhosis Jinjun Wang, PhD1,2 Guo-Xiang Yang, PhD1 Koichi Tsuneyama, MD3 William M. Ridgway, MD4 Patrick S.C. Leung, PhD1

University of California, Davis, California 2 College of Environmental Science and Engineering, Yangzhou University, Yangzhou, Jaingsu Province, China 3 Department of Diagnostic Pathology, Graduate School of Medicine and Pharmaceutical Science for Research, University of Toyama, Toyama, Japan 4 Division of Immunology, Allergy and Rheumatology, University of Cincinnati College of Medicine, Cincinnati, Ohio

Address for correspondence Patrick S.C. Leung, PhD, Division of Rheumatology, Allergy and Clinical Immunology, University of California at Davis School of Medicine, 451 Health Sciences Drive, Suite 6510, Davis, CA 95616 (e-mail: [email protected]).

Semin Liver Dis 2014;34:285–296.

Abstract

Keywords

► antimitochondrial antibodies ► cholangiocytes ► dnTGFBRII ► intrahepatic bile ducts ► NOD.ABD ► xenobiotics ► microbial immunization

Within the last decade, several mouse models that manifest characteristic features of primary biliary cirrhosis (PBC) with antimitochondrial antibodies (AMAs) and immunemediated biliary duct pathology have been reported. Here, the authors discuss the current findings on two spontaneous (nonobese diabetic autoimmune biliary disease [NOD.ABD] and dominant negative transforming growth factor-β receptor II [dnTGFβRII]) and two induced (chemical xenobiotics and microbial immunization) models of PBC. These models exhibit the serological, immunological, and histopathological features of human PBC. From these animal models, it is evident that the etiology of PBC is multifactorial and requires both specific genetic predispositions and environmental insults (either xenobiotic chemicals or microbial), which lead to the breaking of tolerance and eventually liver pathology. Human PBC is likely orchestrated by multiple factors and hence no single model can fully mimic the immunopathophysiology of human PBC. Nevertheless, knowledge gained from these models has greatly advanced our understanding of the major immunological pathways as well as the etiology of PBC.

Animal models are invaluable in the study of human diseases. Not only do they greatly advance our understanding of the etiology and progression of human diseases, animal models have proven to be effective tools in designing therapeutic regimens. Mouse models are the most common experimental mammalian models because they have a relatively short life span and gestational period, and are easy to maintain and breed in captivity. Moreover, the immunology, genetics, anatomy, and physiology of mice are also well characterized. Within the last few decades, a large multitude of inbreed mouse strains have been further genetically manipulated and offer a wide battery of genetic modifications that can be readily used for defining physiological pathways in liver diseases.1 Here we will discuss salient animal models in the study of an autoimmune liver disorder, primary biliary cirrhosis (PBC).

Issue Theme Primary Biliary Cirrhosis; Guest Editor, Pietro Invernizzi, MD, PhD

Primary biliary cirrhosis is a liver-specific autoimmune disorder, characterized by high-titer antimitochondrial autoantibodies (AMAs) and immunomediated destruction of intrahepatic bile duct epithelial cells (cholangiocytes) mediated by a progressive portal lymphocytic inflammatory response. Primary biliary cirrhosis often develops in middle-aged women and the etiology is unknown.2 The major mitochondrial autoantigens are the E2 subunits of pyruvate dehydrogenase (PDC-E2), branched chain 2-oxo acid dehydrogenase (BCOADC-E2), and 2-oxo-glutarate dehydrogenase (OGDCE2).3–6 Granulomas are present in 15% of PBC patients. A recent immunohistochemical study suggests that dendritic cells are key to the pathogenesis of granulomas in PBC.7 Fibrosis develops as the disease advances, particularly in the periportal areas. Extensive efforts in defining the target mitochondrial autoantigens, T- and B-cell epitopes, the innate

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DOI http://dx.doi.org/ 10.1055/s-0034-1383728. ISSN 0272-8087.

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1 Division of Rheumatology, Allergy and Clinical Immunology,

M. Eric Gershwin, MD1

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and adaptive immune responses, the immunobiology of the biliary epithelium, and the pathology of biliary cells destruction have greatly advanced the knowledge of the molecular mechanisms in the pathogenesis of PBC.8–23 However, understanding of the early events in the induction of tissue inflammation and autoimmunity in PBC has been greatly impeded by the cryptic onset of the disease, limitations in accessing human liver samples, and the lack of a suitable animal model. Fortunately, this picture has changed dramatically within the last decade with the reports of several murine models that manifest characteristic clinical features of human PBC with AMAs and lymphocyte infiltration with biliary epithelial cell pathology. Here, we discuss the current findings on two spontaneous and two induced murine models of PBC. The spontaneous models are nonobese diabetic autoimmune biliary disease (NOD.ABD) and dominant negative transforming growth factor-β (TGF-β) receptor II (dnTGFßRII) mouse models. The two induced models utilize chemical xenobiotics and microbial immunization. In each model we will discuss the main characteristics to highlight their significance in PBC (►Table 1). The availability of these PBC animal models provides unique systems to further dissect the immunological, genetic, and environmental components that are intrinsic for the development of clinical PBC.24–27

Spontaneous Mouse Models NOD.ABD Mouse Lines The NOD. c3c4 congenic mouse model was the first characterized spontaneous model of PBC, originally generated by introgression of chromosome 3 and 4 B6/B10-derived genomic regions onto the NOD background for the purpose of studying the genetics of autoimmune type 1 diabetes (T1D).28–33 NOD.c3c4 mice developed liver lesions and AMAs with some similarities to patients with PBC.34 These mice demonstrate liver histopathological abnormalities including liver lymphocytic infiltrates, portal tract lesions, and epithelial granuloma-like formation. Fifty to 60% of NOD.c3c4 mice spontaneously develop autoantibodies to PDC-E2 at a relatively young age of 9 to 10 weeks,34 and 80 to 90% develop antinuclear antibodies at 20 to 25 weeks of age. Histochemical staining demonstrated biliary tracts infiltrated with CD3þ, CD4þ, and CD8þ T cells. NOD.c3c4 mice treated with monoclonal antibody to CD3 can be partially protected from ABD. NOD.c3c4-scid mice are also protected from disease (without clinical symptoms), which is important because it emphasizes the critical role of the autoimmune response in the pathogenesis of NOD.c3c4 disease. Supporting this view, NOD.c3c4-scid mice do develop disease after adoptive transfer of splenocytes, demonstrating a central role for T cells in the pathogenesis in this model.34 However, one major difference between the NOD.c3c4 pathological process and human PBC was that the mice showed much more extensive biliary proliferation than humans (although moderate to severe biliary proliferation is seen at some stages of PBC). In addition, these immunopathological changes also affect the extrahepatic bile ducts, which is not characteristic of PBC. Seminars in Liver Disease

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We derived a new congenic model of PBC from the NOD. c3c4 mouse, coined NOD.ABD, that has much reduced B6- and B10-derived congenic segments on chromosomes 3 and 4, respectively, compared with the NOD.c3c4 mouse, but develops similar biliary disease.35 Genetic analysis of this and the prior NOD.c3c4 mouse also demonstrated a role for non-NOD genetic regions on chromosome 1. Detailed analysis of the immunopathology using transfer models demonstrated some surprising, but salient genetic restrictions on ABD.35 First, whole spleen from NOD.ABD mice could transfer both T1D and ABD into NOD.c3c4-scid recipients, but could not transfer biliary disease into NOD-scid recipients, suggesting that the recipient mice must express the genes important for ABD in the target tissue, not only in the hematopoietic cells.35 Second, the disease-transfer model showed that ductule damage and lymphocytic infiltration preceded biliary epithelial proliferation in these mice, which is important because it demonstrates that biliary epithelial proliferative defect is caused by the autoimmune attack on the tissue. This implies that the immunopathological mechanisms may in fact be similar to the human disease (i.e., a T-cell-mediated attack on cholangiocytes) even if the specific tissue manifestation (i.e., excess cholangiocyte proliferation) differs in the mouse. Finally, NOD.ABD CD8þ T cells alone, but not CD4 T cells, transferred severe biliary disease—whereas NOD CD8 cells did not, suggesting that genetically regulated pathogenic CD8 T cells are important in the induction of disease in this model.35 There were two possible explanations for this finding: (1) that the genetic regions responsible for ABD must be found in the donor CD8 cells, or (2) that CD8 memory cells are stimulated in ABD mice by tissue abnormalities in the target organ (which are lacking in NOD mice, hence memory autoreactive T cells cannot develop). We are addressing this question using bone marrow chimera studies. In summary, the NOD.ABD congenic mice illustrate that (1) a genetic abnormality in the autoimmune target tissue (e.g., the biliary tract) is critical for the pathogenesis of the autoimmune attack on cholangiocytes, and (2) CD8 T cells, probably with a specific genetic composition, are central to the autoimmune process. These findings point the way for new studies illustrating a close interaction between target tissue and genetically programmed immune system abnormalities in causing autoimmune biliary disease.

Dominant Negative TGF-β Receptor II (dnTGFßRII) Mice TGF-β receptor II is critical for signal transduction of TGF-β, which regulates the activation of lymphocytes.36,37 Deficiency in TGF-β results in various pleiotropic immunological abnormalities, including autoimmune cholangitis, colitis, and early death.38–40 The dnTGFßRII mouse model of autoimmune cholangitis was first reported in 2006.41 dnTGFßRII mice overexpress a dominant-negative form of TGF-β receptor type II under the control of the CD4 promoter, resulting in specific abrogation of TGF-β signaling in CD4þ T cells.42 Notably, however, TGF-β signaling is not completely eliminated in these T cells, which

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þþ þ  þ þ þ

þþþ

þ

þþ

þ

þ- þ þþ

þ- þ þ

þ

Portal lymphoid infiltrates

CD4 cell

CD8 cell

B cell

Bile duct destruction

Granuloma

Eosinophilia

20, 21

Also develop common bile duct dilation and biliary epithelial cell proliferation.

PDC-E2

27

Spontaneously develop inflammatory bowel disease unless maintained by a Helicobacter-free diet and antibiotics in drinking water.





þþ

þ

þþ

þ

þþþ

Lipoyl domain

PDC-E2

100%

C57BL/6 Overexpression of a dn form of TGFβRII under CD4 promoter

dnTGFβRII Mice

62

Proof of hypothesis that molecular mimics of lipoylated PDC-E2 in the environment can lead to loss of tolerance to PDC-E2 and autoimmune cholangitis.



þ

þ

þ

þþ

þ

þ

Lipoyl domain

PDC-E2

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65

The only chemical-induced murine model of PBC that exhibits fibrosis.



þ

þþ

þ

þþþ

þ

þþ

Lipoyl domain

PDC-E2

100%

C57BL/6

C57BL/6

100%

2-OA-BSA þ α  glyceramide immunization

2-OA-BSA immunization

Xenobiotic model

Abbreviations: AMA, antimitochondrial antibody; N/A, not applicable; NKT, natural killer T; NOD, nonobese diabetic.

Reference

Remarks

2, 8

þþþ

Lipoyl domain

Dominant PDC-E2 Epitope

Liver histology

Lipoyl domain

PDC-E2

Dominant AMA target protein

50–60%

90–95%

AMA

B-cell immunity

NOD.c3c4

N/A

NOD.ABD Mice

PBC Patients

Background/strain

Spontaneous models

Human

Table 1 Immunological features in patients with primary biliary cirrhosis (PBC) and mouse models of PBC

77

Sequence homology between lipoylated proteins of xenobiotic metabolizing N. aromaticivorans together with the natural liver tropism of NKT cells and the accumulation of N. aromaticivorans in the liver likely explains the liver specificity of destructive responses and AMA.





þ

þ

þ

þ

þ

Lipoyl domain

PDC-E2

100%

NOD 1101

Novosphingobium aromaticivorans immunization

Microbial Model

82

Highlight the importance of microbial infections in autoimmunity either as primary or co-existing secondary events.





þ







þ

Lipoyl domain

PDC-E2

100%

NOD.B6-Idd10/Idd18

Escherichia coli immunized mice

Animal Models of Primary Biliary Cirrhosis Wang et al.

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Fig. 1 Histological analysis of liver sections dnTGFßRII mouse (at 24–28 weeks of age). (A–C) Note different degrees of lymphocytic infiltration (red arrows) surrounding the small bile ducts were detected within the portal tracts (hematoxylin and eosin staining).

explains why the dnTGFßRII mice can survive for almost normal lifespans compared with mice in which TGF-β receptor signaling is completely knocked out and mice die at age 4 weeks. The dnTGFßRII mice are maintained by mating male dnTGFßRII mice with normal B6 females (because female dnTGFßRII mice experience reproductive failure) to produce heterozygote dnTGFßRII mice and normal B6 offspring.42 dnTGFßRII mice are fed a sterile rodent Helicobacter diet and sterile drinking water including Sulfatrim, and are maintained individually in ventilated cages under specific pathogen-free conditions. The dnTGFßRII mice exhibit several major serological and histological characteristics of human PBC (►Fig. 1), suggesting that the dnTGFßRII pathway is important in the pathogenesis of PBC.41,43 They are 100% AMA positive with autoantibodies directed against the major mitochondrial autoantigens in human PBC including PDC-E2, BCOADC-E2 and OGDC-E2, gp210, and sp100.44 Their liver and serum cytokine levels reflect a Th1 profile. The liver histology of dnTGFßRII mice manifests lymphoid cell infiltration in the portal tracts of mice including CD4þ, CD8þ, and CD19þ cells as in human PBC. This is accompanied by bile duct injury in 25 to 50% of mice up to 22 weeks of age.43 To examine the role of CD4þ and CD8þ T cells in liver pathology in these mice, we performed adoptive transfer studies by transferring dnTGFßRII mice-derived splenic CD4þ and/or CD8þ T cells into Rag1/ recipients. Rag1/ recipients of dnTGFßRII mice unfractionated splenocytes developed features of liver pathology similar to human PBC, suggesting that splenic T and B cell loss of tolerance are associated with autoimmune cholangitis in the dnTGFßRII mice. Furthermore, transfer of dnTGFßRII derived CD8þ T cells into Rag1/ recipients resulted in liver-specific autoimmunity, whereas CD4þ T cell transfer led to colitis, indicating that CD8þ T cells are the primary contributors for bile duct destruction in this model.43 This is very similar to the NOD. c3c4 model wherein CD8 cells alone can cause biliary disease.35 To further delineate whether autoimmune cholangitis in the dnTGFßRII mice was secondary to antigen-specific autoreactive CD8þ T cells or due to antigen nonspecific effects of Seminars in Liver Disease

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dnTGFßRII accumulating in the liver, we generated OT-I/ dnTGFßRII/Rag1/ and OT- II/dnTGFßRII/Rag1/ mice in which the entire T-cell repertoire was replaced with ovalbumin- (OVA-) specific CD8þ or CD4þ T cells, respectively.25 Importantly, neither the parental OT-I/dnTGFßRII/Rag1/ mice and/or OT- II/ dnTGFßRII/Rag1/ mice developed cholangitis. However, data from adoptive transfer demonstrated that only transfer of CD8þ T cells from dnTGFßRII mice, but not CD8þ T cells from OT-I/Rag1/ mice or from OT-I/ dnTGFßRII/Rag1/ mice, transferred disease. These observations were not due to an absence of CD4þ T-cell help because a combination of CD8þ T cells from OT-I/dnTGFßRII/Rag1/ and CD4þ T cells from OT II/dnTGFßRII/Rag1/ or CD8þ T cells from OT-I/dnTGFßRII/Rag1/ with CD4þ T cells from OT-II/Rag1/ mice failed to transfer disease. Altogether, the data showed that defective TGFßRII signaling and antigenspecific clonal CD8þ T cells that target biliary cells are required for induction of autoimmune cholangitis.25 Although the presence of high titers of AMAs is present in 95% of patients with PBC, there is no direct correlation between AMAs and pathogenesis.45,46 We have investigated the role of AMAs in disease pathology in the dnTGFßRII mice model of PBC. Briefly, dnTGFßRII mice were crossed with Bcell-deficient mice (Igµ–/–), and were evaluated for the development of liver inflammation, as well as the severity of accompanying colitis. Surprisingly, Igµ/ dnTGFßRII mice developed a more severe cholangitis and colitis compared with dnTGFßRII mice, indicating a suppressive effect of B cells on the inflammatory response in the dnTGFßRII mice.47 To further determine the role of B cells in tissue pathology in dnTGFßRII mice, we examined the effects of therapeutic B cell depletion. Young (4–6 weeks) and old (20–22 weeks) dnTGFßRII mice were injected intraperitoneally with antimouse CD20 monoclonal antibody (mAb) every 2 weeks, and the disease phenotype compared with control Ab-treated mice.47 Treatment of young mice demonstrated fully depleted serum AMAs, a lower incidence of liver inflammation, and a fewer number of activated hepatic CD8þ T cells, whereas colon inflammation was significantly exacerbated. In contrast, anti-CD20 treatment of animals with established disease was ineffective, suggesting that B cells play both a

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positive and negative regulatory role in the pathogenesis of PBC. Previous studies have shown that CD1d expression and the frequency of CD1d-restricted natural killer T (NKT) cells were increased in the livers of patients with PBC.48 Thus, to examine the role of CD1d-restricted NKT cells in the pathogenesis of PBC, we generated CD1d/ dnTGFßRII mice and showed that these mice had decreased mononuclear cell infiltration in the liver and lower interferon-γ(IFN-γ) serum levels, which ultimately ameliorated liver injury compared with that of dnTGFßRII mice.43 Data from this work suggests that CD1d-restricted NKT cells have a primarily proinflammatory phenotype with a Th1 cytokine bias, and promote deprivation of TGF-β signaling. The complexity of the IL-12/IL-23 cytokine milieu in autoimmunity in dnTGFßRII mice was dissected by generating a series of cytokine knockouts with the dnTGFßRII mice. These include IFN-γ/, IL-12p35/, IL-12/IL-23p40/, IL23p19/, and IL-17A/ (►Table 2). IL-12 promotes IFN-γ production and the triggering of Th1 cell responses, which contribute to loss of tolerance in several models of autoimmunity.43,49,50 Our data on IL-12p40–/– dnTGF-βRII mice has established that the IL-12p40 subunit is essential for the development of autoimmune cholangitis. Deletion of IL-12p40 in dnTGFßRII mice resulted in lower

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levels of inflammatory cytokines, immune cell infiltrates, and bile duct damage, but does not alter AMA levels.49 However, in mice depleted of IFN-γ mediated signaling (IFN-γ–/– dnTGFβRII mice), cholangitis was not abrogated, suggesting that IFN-γ is dispensable for the development of autoimmunity. We therefore deleted the IL-12p35 in dnTGFßRII mice, which is deficient in two members of the IL-12 family, IL-12 and IL35. Although the mice demonstrated a distinct cytokine profile shift from Th1 to Th17, deletion of IL-12p35 resulted in liver inflammation and bile duct damage with similar severity as in the dnTGFßRII mice, but with delayed onset.50 Surprising, significant hepatic periportal fibrosis occurs in 50% of mice at 24 weeks of age in IL-12p35/ mice, suggesting the contribution of the Th17 family to the progressive fibrosis in the dnTGFßRII mice. We next generated IL-23p19/ dnTGFßRII mice to examine whether IL-12p40 mediates protection by the IL-23/Th17 pathways. Our data showed that IL-23p19/ mice exhibited dramatic improvement in the colitis, but no changes in biliary pathology. Th17 cell populations were reduced, whereas IFNγ levels remained unchanged in IL-23p19/ mice. Altogether, our data indicated that IL-12/Th1 pathway is essential for biliary disease pathogenesis, whereas the IL-23/Th17 pathway mediates colitis.51 Because IL-17A is a major effector cytokine produced by IL-23-dependent Th17 cells, we further

Table 2 Autoantibody and liver pathology in immune knockout dnTGFßRII mice AMAa

ANAb

Lymphoid cell infiltration

Bile duct injury

Fibrosis

þ

þþþ

þ

þ



þ

þþ

þ

þ

IL-12p40/ dnTGFßRII

þ

þ

IL-23p19/ dnTGFßRIIc

þþ

þþ

IL-17A/ dnTGFßRII

þ

IL-12p35/ dnTGFßRII

þþ

dnTGFßRII IFN-γ

/

dnTGFßRII

Th1/Th17 deficiency

Remarks



Th1

IFN-γ deficiency does not alter AMA, ANA, and liver pathology





Th1/Th17

Lower levels of inflammatory cytokines, immune infiltrates, and bile duct damage, but does not alter AMA levels

þ

þ



Th17

IL-23/Th17 pathway mediates colitis

þþ

þ

þ



Th17

IL-23/ Th17 pathway contributes colitis in an IL-17-independent manner

þþ

þ

þ

þd

Th1

Distinct cytokine profile shift from Th1 to Th17. Liver fibrosis is frequently observed.



Abbreviations: AMA, antimitochondrial antibody; ANA, antinuclear antibody. a Detected by enzyme-linked immunosorbent assay and immunoblot against rPDC-E2. b Detected by immunofluorescence on HEp-2 cells. c Improvement in colitis, but no changes in biliary pathology. d Fibrosis in 50% of mice at 24 weeks of age.

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generated IL-17A/ dnTGFßRII mice to dissect the role of IL17A in the pathogenesis of cholangitis in dnTGFßRII mice and to assess the mechanism of the IL-23-mediated protection from colitis. Our data demonstrated that IL-17A/ dnTGFßRII mice did not have decreased severity of autoimmune cholangitis or colitis, showing that IL-17A is not important for autoimmune cholangitis or colitis. These data suggest that the IL-23/ Th17 pathway contributes colitis in an IL-17-independent manner.51 Although the dnTGFßRII mice exhibit features resembling those seen in PBC, it is also important to note that there are some differences from human PBC, such as the lack of a female bias, eosinophilic infiltration, and granuloma formation.52 Nevertheless, the association of decrease in peripheral Tregs with disease in PBC patients53 and the role of TGF-β in immunomodulation make the dnTGFßRII mice a useful model for PBC.

Induced Mouse Models of Primary Biliary Cirrhosis Accumulating evidence suggests environmental factors are involved in the etiology of PBC.54–63 Our laboratory has addressed the role of xenobiotic chemicals and microbial infections in the induction of PBC. Here, we will discuss our current data on a xenobiotic induced and two bacterially induced mouse models.

coexpress CD44, and an elevation of serum TNF-α and IFN-γ. These data provide a persuasive argument in favor of an environmental origin for human PBC.75,77–79 The NOD.1101 mice immunized with 2-OA-BSA, but not with BSA alone, developed high-titer AMAs and histological features, including portal infiltrates enriched in CD8þ cells and liver granulomas, similar to human PBC. We believe these models will allow the rigorous dissection of early environmental agents interacting with immunogenetic factors to cause biliary damage.76 Using this mouse model, we investigated the role of B cells in PBC by depleting B cells using two different monoclonal antibodies, CD20 and CD79. The results revealed that B-cell depletion led to exacerbated cholangitis, with higher T-cell infiltrates and inflammatory cytokines, indicating a protective role of B cells in PBC.12 Furthermore, we investigated the role of IL-12-Th1/IL-23-Th17 pathways in autoimmune cholangitis in this 2-OA-BSA PBC model in specific cytokine knockout mice (►Table 3).24 In particular, we constructed several unique gene-deleted mice, including C57/BL6 mice deleted of IL-12p40, IL-12p35, IFN-γ, IL-23p19, IL-17A, IL-17F, and IL-22. To identify key cytokine pathways that might provide clues for successful therapy, we immunized each of these cytokine deletion mice with 2-OA-BSA and followed the natural history of their immunopathology. Our data indicate

Xenobiotic Induction of AMA and Autoimmune Cholangitis In PBC, the T-cell and B-cell epitopes are focused on the lipoyl binding motif of PDC-E2.60,64–66 Accumulating evidence implicates that the loss of tolerance to PDC-E2 is pivotal in the initiation event of PBC and that AMA specificities reflect aspects of the induction phase of the disease.67,68 We hypothesized that xenobiotic modification of the native lipoyl moiety of the major mitochondrial autoantigen PDC-E2, may lead to the loss of self-tolerance in PBC.69 This thesis is based on the findings of (1) readily detectable levels of immunoreactivity of PBC sera against comprehensive panels of protein microarrays, which mimic the inner lipoyl domain of PDC-E2; and (2) subsequent quantitative structure-activity relationships.70 Recent data further suggest that chemical modification of PDC-E2 lipoic acid, via an electrophilic attack on the lipoic acid disulfide bond, triggers the breaking of tolerance to PDC-E2.71–73 Such modifications could substantially affect the conformation of the PDC-E2 lipoyl domain and its immunogenicity in genetically susceptible hosts. Importantly, one of these chemical compounds is 2-octynoic acid (2-OA), a chemical commonly found in cosmetics and food additives.74 Interestingly, immunization of C57BL/6 mice75 and NOD.1101 (NOD.B6 Idd10 Idd18r2) mice with 2-OA coupled to bovine serum albumin (BSA), but not BSA alone, induced high-titer AMAs, portal inflammation, and autoimmune cholangitis similar to human PBC (►Figs. 2 and 3).76 C57BL/6 mice immunized with 2-OA-BSA, but not with BSA alone also manifest increased liver lymphoid cell numbers, an increase in CD8þ liver infiltrating cells, particularly CD8þ T cells that Seminars in Liver Disease

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Fig. 2 Anti-PDC-E2 in serum of 2OA-BSA immunized mice. Sera samples obtained at 2-week intervals after immunization were quantified for IgG, IgM, and IgA to PDC-E2 by enzyme-linked immunosorbent assay. Note the significant increase in optical density (O.D.) values after immunization between responder and control mice. p < 0.05.  p < 0.01. p < 0.001.

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that although both IL-12/Th1 and IL-23/Th17 are involved in cholangitis, it is the IL-12/Th1 signaling pathway that elicits liver pathology in this xenobiotic induction disease model of PBC. In fact, deletion of IFN-γ prevents disease and suppresses autoantibodies. Importantly, deletion of the Th17 cytokines IL-17A and IL-22, but not IL-17F, reduces biliary damage; IL17A-knockout mice have reduced levels of AMAs. We further demonstrate that the production of IFN-γ is significantly decreased in livers of IL-23p19/, IL-17A/, and IL-22/ mice compared with controls. However, the ability of T cells to produce IFN-γ was not affected in Th17 cytokine-deficient mice. In summary, in the 2-OA-BSA immunized mice model: (1) Both IL-12/Th1 and IL-23/Th17 are involved in cholangitis; (2) the IL-12/Th1 signaling pathway is critical in eliciting liver pathology; and (3) the IL-23/Th17 pathway is involved in perpetuating the IL-12/IFN-γ mediated pathology. In addition, we have investigated the role of innate immunity and NKT cells on modulating disease activity in this xenobiotic induced mouse model. Briefly, we immunized mice with and without the addition of α-galactosylceramide (α-GalCer), an invariant NKT cell activator. 2-OA-BSA-immunized mice exposed to α-GalCer developed a profound exacerbation of their autoimmune cholangitis, including significant increases in CD8þ T cell infiltrates, portal inflammation, granuloma formation, and bile duct damage. More

excitingly, these mice produced increased levels of AMAs and have evidence of fibrosis, a feature not previously reported in any other induced murine models of PBC.80 These results are critical and emphasize the role of innate immunity in the natural history of PBC. Furthermore, the data also provide clues to the mechanisms by which biliary disease becomes perpetuated in humans as well as explaining the recurrence of PBC following liver transplantation in the absence of major histocompatability complex (MHC) compatibility. Thus, in the absence of MHC restriction, disease reoccurrence would depend on non-MHC-restricted cellular mechanisms, suggesting that biliary epithelial cells are more than simply an innocent victim of an immune attack (as also suggested by the NOD congenic studies above). Rather, they attract immune attack by virtue of the unique biochemical mechanisms by which they process PDC-E2 during apoptosis.13,81 These results also explain the success of ursodiol, a drug that appears to have antiapoptotic properties and also may modulate innate responses. Our data would also explain the relative failure of immunosuppressive drugs to alter PBC because such agents are ineffective against innate mechanisms. Finally, the induction of fibrosis in 2-OA-BSA-immunized mice exposed to α-GalCer permits not only dissection of its induction, but also has the potential to be useful in studies of intervention.

Table 3 Effect of IL-12/Th1 and IL-23/Th17 pathways on liver pathology in 2OA-BSA immunized mice Pathway

Cytokine knockout

Th1

IL-12p35

Th1

IFN-γ/

Th1/Th17

/

Liver pathology Reduced liver infiltrates; reduced bile duct damage Marked reduced liver infiltrates; normal bile duct

IL12/IL23p40 /

/

Abolished autoimmune cholangitis

Th17

IL-23p19

Th17

IL-17A/

Th17

/

Similar to positive control

/

Reduced liver infiltrates; reduced bile duct damage

Th17

IL-17F IL-22

Reduced liver infiltrates; reduced bile duct damage Reduced liver infiltrates; reduced bile duct damage

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Fig. 3 Microscopic examination of liver tissues from (A) nonimmunized control mice and (B) 2OA-BSA immunized mice at 12 weeks postimmunization (magnification 400). Note the presence of infiltration of lymphocytes in portal tracts, particularly surrounding damaged intralobular bile ducts (green asterisk) in the 2OA-BSA immunized mice (hematoxylin and eosin staining).

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Microbial Induction Models Novosphingobium aromaticivorans-Immunized Mice Novosphingobium aromaticivorans (N. aro), a proteobacterium of the Sphingomonodaceae family of gram-negative alphaproteo-bacteria, is commonly found in soil, water, and coastal plain sediments.82 The distinctive xenobiotic metabolizing properties and remarkable amino acid sequence homology between its lipoyl-containing proteins and human PDC-E283 suggests that exposure to N. aro, perhaps the xenobiotic modified lipoyl proteins, could lead to a break in tolerance to PDC-E2 and can trigger PBC.62,84–87 Interestingly, instead of possessing the common lipopolysaccharide on their cell walls, N. aro express glycosphingolipids such as α-glycuronosylceramides, which are recognized by CD1d-restricted NKT cells.88,89 This is important for the activation of NKT cells and the subsequent release of Th1 and Th2 cytokines and chemokines.90,91 It has been observed that PBC patients have an increase of NKT cells and increased expression of CD1d, leading to the hypothesis and subsequent experimental discovery that PBC-like liver disease can be caused by the infection of mice with N. aro and requires NKT cells.92 Briefly, the infection of mice strains (NOD, C57BL/6 and SJL) with N. aro at 5  107 colonyforming units (CFU) intravenously at week 0 and week 2 not only induced signature antibodies against microbial PDCE2 and its mitochondrial counterpart, but also triggered chronic T-cell-mediated autoimmunity against small bile ducts. Further work has been directed to the role of NKT cells in autoimmune cholangitis and has focused on the NOD.1101 mouse strain because it exhibited particularly severe liver disease similar to PBC. NOD.1101 belongs to a set of NOD subcongenic strains originating from NOD.c3c4 mice and was produced by introgressing Idd loci 10 and 18r2

from B6 (chromosome 3) onto an NOD background.34,93–96 In this model, disease induction requires NKT cells, which specifically respond to the N. aro cell wall, α-glycuronosylceramides, presented by CD1d molecules. Combined with the natural liver tropism of NKT cells, the accumulation of N. aro in the liver likely explains the liver specificity of destructive responses. Furthermore, once established, liver disease could be adoptively transferred by T cells independently of NKT cells and microbes, illustrating the importance of early microbial activation of NKT cells in the initiation of autonomous organ-specific autoimmunity.92

Escherichia coli-Immunized Mice Although the presence of AMAs and liver infiltration in N. aroinfected NOD.1101 mice is intriguing, it has been reported that intravenous inoculation of two different strains of Escherichia coli (E. coli; DH5α and ATCC 25922) or Salmonella into NOD1101 mice could induce transient mild liver inflammation early after inoculation, which resolved within a few weeks.92 This has prompted us to ask the question whether autoimmune cholangitis can be induced in mice by enteric bacteria without the activation of NKT cells. Indeed, our group demonstrated that NOD.B6-Idd10/Idd18 mice infected with E. coli developed AMAs and severe cholangitis (►Fig. 4).97 It has been reported that there are six E. coli peptide sequences that mimic the human PDC-E2 autoepitope with 6–8 identical amino acid residues,56 which may also account for the E. coli-induced anti-PDCE2 response in the NOD.B6-Idd10/Idd18 mice. The difference in microflora between animal colonies may also partly account for the discrepancies between this study and others.92,98 Although the serological antibody reactivity to PDC-E2 is relatively weak in microbially infected (E. coli, N. aro) mice when compared with sera from patients with PBC or other models

Fig. 4 Antimitochondrial antibodies (AMAs) and liver histology of E. coli immunized mice. (A) AMA determination of Escherichia coli (E. coli) infected mice and control mice. Sera from NOD.B6 Idd10/Idd18 mice administrated with E. coli (n ¼ 13) or PBS only (n ¼ 6) were collected at 12 weeks postinfection and assayed for anti-PDC-E2 by enzyme-linked immunosorbent assay at 1:500 sera dilution. Note that antibody to recombinant PDC-E2 was significantly higher (p < 0.001) in the E. coli group when compared with PBS group. (B) Histological analysis of liver sections of E. coli infected mice and negative control mice at 26 weeks postimmunization (magnification 400). Striking portal inflammation accompanied by granuloma formation was present in livers of E. coli-infected mice, but not in the PBS control group. Significant biliary cell damage was also detected in E. coli-infected mice (blue arrow). Seminars in Liver Disease

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Conclusions These models demonstrate the characteristic serological, biochemical, and histological features of human PBC (►Table 1). From these animal models, it is evident that the etiology of PBC is multifactorial and requires both specific genetic predispositions and environmental insults (either xenobiotic chemicals or microbial), which lead to the breaking of tolerance and eventually liver pathology. 73,77,79,101,102 Furthermore, the initiation of disease from the asymptomatic serologically positive patients may be dependent on the activation of NKT cells.80,92 CD8þ memory T cells play a critical role in directly attacking cholangiocytes in many of the models.25,35 The use of αGalCer promotes the development of hepatic fibrosis, more akin to the human disease.80 Finally, the discovery of E. coli infection-triggered autoimmunity and liver pathology97 warrant further consideration in the elucidation of etiological mechanisms of autoimmune syndromes and may suggest new and simpler ways to diagnose and treat these debilitating diseases. However, we should caution that there are certainly differences in the natural history between human and animal models. For example, human PBC has a middle-age onset and AMAs can be present long before any symptoms, whereas the disease is much accelerated in the mouse models. In addition, the physiological and biochemical responses between human and mice to either chemical or microbial insults are not necessarily identical and cannot be easily extrapolated. Finally, human PBC is likely orchestrated by multiple factors and no single model can fully mimic the immunopathophysiology of human PBC. Nevertheless, knowledge gained from these animal models has already greatly advanced our understanding on the major immunological pathways as well as the etiology of PBC. We believe that the informative knowledge gained in these animal models will allow us to address further issues that will reveal the immunological mechanisms underlying the natural history of autoimmune cholangitis and shed light on novel therapeutic approaches for patients with PBC.

References 1 Liu Y, Meyer C, Xu C, et al. Animal models of chronic liver diseases.

Am J Physiol Gastrointest Liver Physiol 2013;304(5):G449–G468 2 Gershwin ME, Ansari AA, Mackay IR, et al. Primary biliary

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9

10

11

12

13

14

15

16

17

18

19

Acknowledgments This work was supported in part by National Institutes of Health grants DK39588, DK090019, and DK067003.

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20

cirrhosis: an orchestrated immune response against epithelial cells. Immunol Rev 2000;174:210–225 Leung PS, Chuang DT, Wynn RM, et al. Autoantibodies to BCOADCE2 in patients with primary biliary cirrhosis recognize a conformational epitope. Hepatology 1995;22(2):505–513 Moteki S, Leung PS, Dickson ER, et al. Epitope mapping and reactivity of autoantibodies to the E2 component of 2-oxoglutarate dehydrogenase complex in primary biliary cirrhosis using recombinant 2-oxoglutarate dehydrogenase complex. Hepatology 1996;23(3):436–444 Van de Water J, Ansari A, Prindiville T, et al. Heterogeneity of autoreactive T cell clones specific for the E2 component of the pyruvate dehydrogenase complex in primary biliary cirrhosis. J Exp Med 1995;181(2):723–733 Gershwin ME, Mackay IR, Sturgess A, Coppel RL. Identification and specificity of a cDNA encoding the 70 kd mitochondrial antigen recognized in primary biliary cirrhosis. J Immunol 1987;138(10):3525–3531 You Z, Wang Q, Bian Z, et al. The immunopathology of liver granulomas in primary biliary cirrhosis. J Autoimmun 2012; 39(3):216–221 Ishibashi H, Shimoda S, Gershwin ME. The immune response to mitochondrial autoantigens. Semin Liver Dis 2005;25(3): 337–346 Chuang YH, Ridgway WM, Ueno Y, Gershwin ME. Animal models of primary biliary cirrhosis. Clin Liver Dis 2008;12(2):333–347, ix ix Gershwin ME, Mackay IR. The causes of primary biliary cirrhosis: convenient and inconvenient truths. Hepatology 2008;47(2): 737–745 Leung PS, Coppel RL, Gershwin ME. Etiology of primary biliary cirrhosis: the search for the culprit. Semin Liver Dis 2005;25(3): 327–336 Dhirapong A, Lleo A, Yang GX, et al. B cell depletion therapy exacerbates murine primary biliary cirrhosis. Hepatology 2011; 53(2):527–535 Lleo A, Bowlus CL, Yang GX, et al. Biliary apotopes and antimitochondrial antibodies activate innate immune responses in primary biliary cirrhosis. Hepatology 2010;52(3):987–998 Oertelt S, Rieger R, Selmi C, et al. A sensitive bead assay for antimitochondrial antibodies: chipping away at AMA-negative primary biliary cirrhosis. Hepatology 2007;45(3):659–665 Folci M, Meda F, Gershwin ME, Selmi C. Cutting-edge issues in primary biliary cirrhosis. Clin Rev Allergy Immunol 2012;42(3): 342–354 Ali F, Rowley M, Jayakrishnan B, Teuber S, Gershwin ME, Mackay IR. Stiff-person syndrome (SPS) and anti-GAD-related CNS degenerations: protean additions to the autoimmune central neuropathies. J Autoimmun 2011;37(2):79–87 Jin Q, Moritoki Y, Lleo A, et al. Comparative analysis of portal cell infiltrates in antimitochondrial autoantibody-positive versus antimitochondrial autoantibody-negative primary biliary cirrhosis. Hepatology 2012;55(5):1495–1506 Lleo A, Liao J, Invernizzi P, et al. Immunoglobulin M levels inversely correlate with CD40 ligand promoter methylation in patients with primary biliary cirrhosis. Hepatology 2012;55(1): 153–160 Persani L, Bonomi M, Lleo A, et al. Increased loss of the Y chromosome in peripheral blood cells in male patients with autoimmune thyroiditis. J Autoimmun 2012;38(2-3):J193–J196 Rong G, Zhong R, Lleo A, et al. Epithelial cell specificity and apotope recognition by serum autoantibodies in primary biliary cirrhosis. Hepatology 2011;54(1):196–203

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of autoimmune cholangitis, including the dnTGFßRII mice and xenobiotic 2-octynonic acid BSA conjugate immunized C57BL/6 mice,41,75 the initiation of anti-PDC-E2 during earlystage E. coli infection is sufficient to break tolerance and lead to PBC-like liver pathology in E. coli-infected mice. It is also interesting to note that frequent inoculation of Streptococcus intermedius could induce chronic nonsuppurative destructive cholangitis and autoantibodies in C57BL/6 and BALB/c, but not in C3H/HeJ mice.99,100 These animal models of microbialinduced PBC-like liver pathology clearly support the thesis of microbial involvement in the etiology of PBC.

Wang et al.

Animal Models of Primary Biliary Cirrhosis

Wang et al.

21 Takahashi T, Miura T, Nakamura J, et al. Plasma cells and the

41 Oertelt S, Lian ZX, Cheng CM, et al. Anti-mitochondrial antibodies

chronic nonsuppurative destructive cholangitis of primary biliary cirrhosis. Hepatology 2012;55(3):846–855 Wang Q, Selmi C, Zhou X, et al. Epigenetic considerations and the clinical reevaluation of the overlap syndrome between primary biliary cirrhosis and autoimmune hepatitis. J Autoimmun 2013; 41:140–145 Zhang W, Ono Y, Miyamura Y, Bowlus CL, Gershwin ME, Maverakis E. T cell clonal expansions detected in patients with primary biliary cirrhosis express CX3CR1. J Autoimmun 2011; 37(2):71–78 Kawata K, Tsuda M, Yang GX, et al. Identification of potential cytokine pathways for therapeutic intervention in murine primary biliary cirrhosis. PLoS ONE 2013;8(9):e74225 Kawata K, Yang GX, Ando Y, et al. Clonality, activated antigenspecific CD8(þ) T cells, and development of autoimmune cholangitis in dnTGFβRII mice. Hepatology 2013;58(3):1094–1104 Ando Y, Yang GX, Kenny TP, et al. Overexpression of microRNA-21 is associated with elevated pro-inflammatory cytokines in dominant-negative TGF-β receptor type II mouse. J Autoimmun 2013; 41:111–119 Dhirapong A, Yang GX, Nadler S, et al. Therapeutic effect of cytotoxic T lymphocyte antigen 4/immunoglobulin on a murine model of primary biliary cirrhosis. Hepatology 2013;57(2): 708–715 Kikutani H, Makino S. The murine autoimmune diabetes model: NOD and related strains. Adv Immunol 1992;51:285–322 Chen YG, Scheuplein F, Osborne MA, Tsaih SW, Chapman HD, Serreze DV. Idd9/11 genetic locus regulates diabetogenic activity of CD4 T-cells in nonobese diabetic (NOD) mice. Diabetes 2008; 57(12):3273–3280 Fox CJ, Paterson AD, Mortin-Toth SM, Danska JS. Two genetic loci regulate T cell-dependent islet inflammation and drive autoimmune diabetes pathogenesis. Am J Hum Genet 2000;67(1):67–81 Fraser HI, Dendrou CA, Healy B, et al. Nonobese diabetic congenic strain analysis of autoimmune diabetes reveals genetic complexity of the Idd18 locus and identifies Vav3 as a candidate gene. J Immunol 2010;184(9):5075–5084 Aoki CA, Borchers AT, Ridgway WM, Keen CL, Ansari AA, Gershwin ME. NOD mice and autoimmunity. Autoimmun Rev 2005; 4(6):373–379 Koarada S, Wu Y, Fertig N, et al. Genetic control of autoimmunity: protection from diabetes, but spontaneous autoimmune biliary disease in a nonobese diabetic congenic strain. J Immunol 2004; 173(4):2315–2323 Irie J, Wu Y, Wicker LS, et al. NOD.c3c4 congenic mice develop autoimmune biliary disease that serologically and pathogenetically models human primary biliary cirrhosis. J Exp Med 2006; 203(5):1209–1219 Yang GX, Wu Y, Tsukamoto H, et al. CD8 T cells mediate direct biliary ductule damage in nonobese diabetic autoimmune biliary disease. J Immunol 2011;186(2):1259–1267 Taylor AW. Review of the activation of TGF-beta in immunity. J Leukoc Biol 2009;85(1):29–33 Yoshimura A, Wakabayashi Y, Mori T. Cellular and molecular basis for the regulation of inflammation by TGF-beta. J Biochem 2010; 147(6):781–792 Ebert EC, Panja A, Das KM, et al. Patients with inflammatory bowel disease may have a transforming growth factor-beta-, interleukin (IL)-2- or IL-10-deficient state induced by intrinsic neutralizing antibodies. Clin Exp Immunol 2009;155(1):65–71 Kel JM, Girard-Madoux MJ, Reizis B, Clausen BE. TGF-beta is required to maintain the pool of immature Langerhans cells in the epidermis. J Immunol 2010;185(6):3248–3255 Perruche S, Zhang P, Maruyama T, Bluestone JA, Saas P, Chen W. Lethal effect of CD3-specific antibody in mice deficient in TGFbeta1 by uncontrolled flu-like syndrome. J Immunol 2009; 183(2):953–961

and primary biliary cirrhosis in TGF-beta receptor II dominantnegative mice. J Immunol 2006;177(3):1655–1660 Gorelik L, Flavell RA. Abrogation of TGFbeta signaling in T cells leads to spontaneous T cell differentiation and autoimmune disease. Immunity 2000;12(2):171–181 Chuang YH, Lian ZX, Yang GX, et al. Natural killer T cells exacerbate liver injury in a transforming growth factor beta receptor II dominant-negative mouse model of primary biliary cirrhosis. Hepatology 2008;47(2):571–580 Yang CY, Leung PS, Yang GX, et al. Epitope-specific anti-nuclear antibodies are expressed in a mouse model of primary biliary cirrhosis and are cytokine-dependent. Clin Exp Immunol 2012; 168(3):261–267 Invernizzi P, Crosignani A, Battezzati PM, et al. Comparison of the clinical features and clinical course of antimitochondrial antibody-positive and -negative primary biliary cirrhosis. Hepatology 1997;25(5):1090–1095 Kim WR, Poterucha JJ, Jorgensen RA, et al. Does antimitochondrial antibody status affect response to treatment in patients with primary biliary cirrhosis? Outcomes of ursodeoxycholic acid therapy and liver transplantation. Hepatology 1997;26(1):22–26 Moritoki Y, Lian ZX, Lindor K, et al. B-cell depletion with antiCD20 ameliorates autoimmune cholangitis but exacerbates colitis in transforming growth factor-beta receptor II dominant negative mice. Hepatology 2009;50(6):1893–1903 Chuang YH, Lian ZX, Tsuneyama K, et al. Increased killing activity and decreased cytokine production in NK cells in patients with primary biliary cirrhosis. J Autoimmun 2006;26(4):232–240 Yoshida K, Yang GX, Zhang W, et al. Deletion of interleukin-12p40 suppresses autoimmune cholangitis in dominant negative transforming growth factor beta receptor type II mice. Hepatology 2009;50(5):1494–1500 Tsuda M, Zhang W, Yang GX, et al. Deletion of interleukin (IL)12p35 induces liver fibrosis in dominant-negative TGFβ receptor type II mice. Hepatology 2013;57(2):806–816 Ando Y, Yang GX, Tsuda M, et al. The immunobiology of colitis and cholangitis in interleukin-23p19 and interleukin-17A deleted dominant negative form of transforming growth factor beta receptor type II mice. Hepatology 2012;56(4):1418–1426 Nakamura A, Yamazaki K, Suzuki K, Sato S. Increased portal tract infiltration of mast cells and eosinophils in primary biliary cirrhosis. Am J Gastroenterol 1997;92(12):2245–2249 Lan RY, Cheng C, Lian ZX, et al. Liver-targeted and peripheral blood alterations of regulatory T cells in primary biliary cirrhosis. Hepatology 2006;43(4):729–737 Shimoda S, Nakamura M, Ishibashi H, Hayashida K, Niho Y. HLA DRB4 0101-restricted immunodominant T cell autoepitope of pyruvate dehydrogenase complex in primary biliary cirrhosis: evidence of molecular mimicry in human autoimmune diseases. J Exp Med 1995;181(5):1835–1845 Shimoda S, Van de Water J, Ansari A, et al. Identification and precursor frequency analysis of a common T cell epitope motif in mitochondrial autoantigens in primary biliary cirrhosis. J Clin Invest 1998;102(10):1831–1840 Bogdanos DP, Baum H, Grasso A, et al. Microbial mimics are major targets of crossreactivity with human pyruvate dehydrogenase in primary biliary cirrhosis. J Hepatol 2004;40(1):31–39 Bogdanos DP, Baum H, Okamoto M, et al. Primary biliary cirrhosis is characterized by IgG3 antibodies cross-reactive with the major mitochondrial autoepitope and its Lactobacillus mimic. Hepatology 2005;42(2):458–465 Bogdanos DP, Baum H, Sharma UC, et al. Antibodies against homologous microbial caseinolytic proteases P characterise primary biliary cirrhosis. J Hepatol 2002;36(1):14–21 Bogdanos DP, Koutsoumpas A, Baum H, Vergani D. Borrelia Burgdorferi: a new self-mimicking trigger in primary biliary cirrhosis. Dig Liver Dis 2006;38(10):781–782, author reply 782–783

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28 29

30

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33

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55

56

57

58

59

Downloaded by: IP-Proxy CONSORTIUM:NERL (Cornell), Cornell. Copyrighted material.

294

Wang et al.

60 Shimoda S, Nakamura M, Shigematsu H, et al. Mimicry peptides of

80 Wu SJ, Yang YH, Tsuneyama K, et al. Innate immunity and primary

human PDC-E2 163-176 peptide, the immunodominant T-cell epitope of primary biliary cirrhosis. Hepatology 2000;31(6): 1212–1216 Burroughs AK, Butler P, Sternberg MJ, Baum H. Molecular mimicry in liver disease. Nature 1992;358(6385):377–378 Selmi C, Balkwill DL, Invernizzi P, et al. Patients with primary biliary cirrhosis react against a ubiquitous xenobiotic-metabolizing bacterium. Hepatology 2003;38(5):1250–1257 Abdulkarim AS, Petrovic LM, Kim WR, Angulo P, Lloyd RV, Lindor KD. Primary biliary cirrhosis: an infectious disease caused by Chlamydia pneumoniae? J Hepatol 2004;40(3):380–384 Kita H, Matsumura S, He XS, et al. Quantitative and functional analysis of PDC-E2-specific autoreactive cytotoxic T lymphocytes in primary biliary cirrhosis. J Clin Invest 2002;109(9):1231–1240 Liu H, Norman GL, Shums Z, et al. PBC screen: an IgG/IgA dual isotype ELISA detecting multiple mitochondrial and nuclear autoantibodies specific for primary biliary cirrhosis. J Autoimmun 2010;35(4):436–442 Wang J, Budamagunta MS, Voss JC, et al. Antimitochondrial antibody recognition and structural integrity of the inner lipoyl domain of the E2 subunit of pyruvate dehydrogenase complex. J Immunol 2013;191(5):2126–2133 Hirschfield GM, Gershwin ME. The immunobiology and pathophysiology of primary biliary cirrhosis. Annu Rev Pathol 2013; 8:303–330 Benson GD, Kikuchi K, Miyakawa H, Tanaka A, Watnik MR, Gershwin ME. Serial analysis of antimitochondrial antibody in patients with primary biliary cirrhosis. Clin Dev Immunol 2004; 11(2):129–133 Long SA, Quan C, Van de Water J, et al. Immunoreactivity of organic mimeotopes of the E2 component of pyruvate dehydrogenase: connecting xenobiotics with primary biliary cirrhosis. J Immunol 2001;167(5):2956–2963 Rieger R, Leung PS, Jeddeloh MR, et al. Identification of 2-nonynoic acid, a cosmetic component, as a potential trigger of primary biliary cirrhosis. J Autoimmun 2006;27(1):7–16 Leung PS, Lam K, Kurth MJ, Coppel RL, Gershwin ME. Xenobiotics and autoimmunity: does acetaminophen cause primary biliary cirrhosis? Trends Mol Med 2012;18(10):577–582 Naiyanetr P, Butler JD, Meng L, et al. Electrophile-modified lipoic derivatives of PDC-E2 elicits anti-mitochondrial antibody reactivity. J Autoimmun 2011;37(3):209–216 Leung PS, Wang J, Naiyanetr P, et al. Environment and primary biliary cirrhosis: electrophilic drugs and the induction of AMA. J Autoimmun 2013;41:79–86 Amano K, Leung PS, Rieger R, et al. Chemical xenobiotics and mitochondrial autoantigens in primary biliary cirrhosis: identification of antibodies against a common environmental, cosmetic, and food additive, 2-octynoic acid. J Immunol 2005;174(9): 5874–5883 Wakabayashi K, Lian ZX, Leung PS, et al. Loss of tolerance in C57BL/6 mice to the autoantigen E2 subunit of pyruvate dehydrogenase by a xenobiotic with ensuing biliary ductular disease. Hepatology 2008;48(2):531–540 Wakabayashi K, Yoshida K, Leung PS, et al. Induction of autoimmune cholangitis in non-obese diabetic (NOD).1101 mice following a chemical xenobiotic immunization. Clin Exp Immunol 2009; 155(3):577–586 Selmi C, Leung PS, Sherr DH, et al. Mechanisms of environmental influence on human autoimmunity: a National Institute of Environmental Health Sciences expert panel workshop. J Autoimmun 2012;39(4):272–284 Bogdanos DP, Smyk DS, Rigopoulou EI, et al. Twin studies in autoimmune disease: genetics, gender and environment. J Autoimmun 2012;38(2-3):J156–J169 Shoenfeld Y, Tincani A, Gershwin ME. Sex gender and autoimmunity. J Autoimmun 2012;38(2-3):J71–J73

biliary cirrhosis: activated invariant natural killer T cells exacerbate murine autoimmune cholangitis and fibrosis. Hepatology 2011;53(3):915–925 Lleo A, Invernizzi P, Gao B, Podda M, Gershwin ME. Definition of human autoimmunity—autoantibodies versus autoimmune disease. Autoimmun Rev 2010;9(5):A259–A266 Takeuchi M, Hamana K, Hiraishi A. Proposal of the genus Sphingomonas sensu stricto and three new genera, Sphingobium, Novosphingobium and Sphingopyxis, on the basis of phylogenetic and chemotaxonomic analyses. Int J Syst Evol Microbiol 2001; 51(Pt 4):1405–1417 Padgett KA, Selmi C, Kenny TP, et al. Phylogenetic and immunological definition of four lipoylated proteins from Novosphingobium aromaticivorans, implications for primary biliary cirrhosis. J Autoimmun 2005;24(3):209–219 Brodie EL, DeSantis TZ, Parker JP, Zubietta IX, Piceno YM, Andersen GL. Urban aerosols harbor diverse and dynamic bacterial populations. Proc Natl Acad Sci U S A 2007;104(1):299–304 Cavicchioli R, Fegatella F, Ostrowski M, Eguchi M, Gottschal J. Sphingomonads from marine environments. J Ind Microbiol Biotechnol 1999;23(4-5):268–272 Kaplan MM. Novosphingobium aromaticivorans: a potential initiator of primary biliary cirrhosis. Am J Gastroenterol 2004;99(11): 2147–2149 Olafsson S, Gudjonsson H, Selmi C, et al. Antimitochondrial antibodies and reactivity to N. aromaticivorans proteins in Icelandic patients with primary biliary cirrhosis and their relatives. Am J Gastroenterol 2004;99(11):2143–2146 Kawahara K, Moll H, Knirel YA, Seydel U, Zähringer U. Structural analysis of two glycosphingolipids from the lipopolysaccharidelacking bacterium Sphingomonas capsulata. Eur J Biochem 2000; 267(6):1837–1846 Kosako Y, Yabuuchi E, Naka T, Fujiwara N, Kobayashi K. Proposal of Sphingomonadaceae fam. nov., consisting of Sphingomonas Yabuuchi et al. 1990, Erythrobacter Shiba and Shimidu 1982, Erythromicrobium Yurkov et al. 1994, Porphyrobacter Fuerst et al. 1993, Zymomonas Kluyver and van Niel 1936, and Sandaracinobacter Yurkov et al. 1997, with the type genus Sphingomonas Yabuuchi et al. 1990. Microbiol Immunol 2000;44(7): 563–575 Kinjo Y, Wu D, Kim G, et al. Recognition of bacterial glycosphingolipids by natural killer T cells. Nature 2005;434(7032):520–525 Mattner J, Debord KL, Ismail N, et al. Exogenous and endogenous glycolipid antigens activate NKT cells during microbial infections. Nature 2005;434(7032):525–529 Mattner J, Savage PB, Leung P, et al. Liver autoimmunity triggered by microbial activation of natural killer T cells. Cell Host Microbe 2008;3(5):304–315 Lyons PA, Hancock WW, Denny P, et al. The NOD Idd9 genetic interval influences the pathogenicity of insulitis and contains molecular variants of Cd30, Tnfr2, and Cd137. Immunity 2000; 13(1):107–115 Wicker LS, Leiter EH, Todd JA, et al. Beta 2-microglobulin-deficient NOD mice do not develop insulitis or diabetes. Diabetes 1994;43(3):500–504 Koarada S, Wu Y, Yim YS, Wakeland EW, Ridgway WM. Nonobese diabetic CD4 lymphocytosis maps outside the MHC locus on chromosome 17. Immunogenetics 2004;56(5):333–337 Podolin PL, Denny P, Armitage N, et al. Localization of two insulindependent diabetes (Idd) genes to the Idd10 region on mouse chromosome 3. Mamm Genome 1998;9(4):283–286 Wang J, Yang GX, Zhang W, et al. Escherichia coli infection induces autoimmune cholangitis and antimitochondrial antibodies in . non-obese diabetic (NOD).B6 (Idd10/Idd18) mice. Clin Exp Immunol 2014;175(2):192–201 Mohammed JP, Fusakio ME, Rainbow DB, et al. Identification of Cd101 as a susceptibility gene for Novosphingobium

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75

76

77

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Wang et al.

aromaticivorans-induced liver autoimmunity. J Immunol 2011; 187(1):337–349 99 Haruta I, Kikuchi K, Hashimoto E, et al. Long-term bacterial exposure can trigger nonsuppurative destructive cholangitis associated with multifocal epithelial inflammation. Lab Invest 2010;90(4):577–588 100 Haruta I, Kikuchi K, Nakamura M, et al. Involvement of commensal bacteria may lead to dysregulated inflammatory and

autoimmune responses in a mouse model for chronic nonsuppurative destructive cholangitis. J Clin Immunol 2012; 32(5):1026–1037 101 Gershwin ME, Leung PS, Ridgway WM, Coppel RL, Ansari AA. Reply: To PMID 22996325. Hepatology 2013;58(2):830 102 Lleo A, Oertelt-Prigione S, Bianchi I, et al. Y chromosome loss in male patients with primary biliary cirrhosis. J Autoimmun 2013; 41:87–91

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