Decreased CD57 expression of natural killer cells enhanced cytotoxicity in patients with primary sclerosing cholangitis.

Background/aims: Primary sclerosing cholangitis (PSC) is a chronic inflammatory biliary disease for which the immunopathological basis remains an enigma. Natural killer (NK) cells are key components of innate immunity and seemingly play diversified roles in different autoimmune disorders (AIDs). The aim of this study was to determine the role of NK cells in the pathogenesis of PSC. Methods: The frequency and phenotype of circulating NK cells in a large cohort of patients with PSC and healthy controls (HCs) were systematically examined. In addition, the functional capacity of NK cells including cytotoxicity and cytokine production was studied. Results: The frequency of CD3-CD56dimCD16+ (defined as CD56dim) NK cells in PSC patients was significantly lower in comparison to HCs. CD56dim NK cells from PSC displayed a more immature phenotype including high expression of the natural killing receptor NKp46 and downregulation of the highly differentiated NK cell marker CD57. Interestingly, the reduction of CD57 expression of NK cells was associated with the disease severity of PSC. In addition, PSC CD56dim NK cells exhibited increased CD107a degranulation and cytolytic activity toward target cells compared with HCs. Further analysis demonstrated that CD57-CD56dim NK cells from PSC had elevated expression of NKp46, NKp30, IL-2 receptor, and KLRG1 and higher cytotoxic capacity as compared to CD57+CD56dim NK cells. Conclusions: Our data demonstrate that the differentiation of PSC NK cells is dysregulated with enhanced cytotoxic activity. This change is likely to be functionally involved in pathogenesis and disease progression, deducing the potential of NK-directed immunotherapy for PSC.

Glycomic analysis of antibody indicates distinctive glycosylation profile in patients with autoimmune cholangitis.

Glycosylation of antibodies, particularly in the Fc domain, critically modulate the ability of antibodies to bind to FcRs, maintaining immune quiescence to achieve a finely orchestrated immune response. The removal of sialic acid and galactose residues dramatically alters the physiological function of IgGs, and alterations of Ig glycosylation have been associated with several autoimmune disorders. However, Ig glycosylation has not been extensively studied in autoimmune cholangitis. We applied triple quadruple mass spectroscopy with subsequent multiple reaction monitoring to elucidate the profile, composition and linkage of sugar residues of antibody glycans in patients with primary biliary cholangitis (PBC), primary sclerosing cholangitis (PSC) and healthy controls (HC). Agalactosylated, HexNAc terminated IgG1 glycoforms were enriched in both PBC and PSC. Levels of IgM glycans at site N439 and fucosylated glycans in J chain, were significantly decreased in PBC compared to PSC and HC. PSC patients had decreased bisecting glycoforms and increased biantennary glycoforms on IgA compared to PBC. Importantly, our data demonstrate the association of distinct branching and composition patterns of Ig glycoforms with disease severity and liver cirrhosis, which highlight the importance of glycan biology as a potential mechanism and/or a disease specific signal of inflammation.

Therapeutic trials of biologics in primary biliary cholangitis: An open label study of abatacept and review of the literature.

Primary biliary cholangitis (PBC) is a classic autoimmune disease in which humoral, cytotoxic, and innate immune responses have been implicated with the specific targeting of a mitochondrial antigen. The mainstay of treatment remains the bile acid ursodeoxycholic acid (UDCA). Corticosteroids may have some benefits, but to date, clinical trials of biologics targeting B cells and IL-12/23 have not shown any efficacy. Because activated T cells target the intrahepatic bile ducts in PBC and pre-clinical models suggested that blocking CD80/CD86 with CTLA-4 Ig might have therapeutic benefit in PBC, we performed an open-label trial to determine if CTLA-4 Ig (abatacept) is safe and potentially efficacious in PBC patients with an incomplete response to UDCA. PBC patients with an alkaline phosphatase (ALP) > 1.67 × the upper limit of normal after 6 months on UDCA treatment or who were intolerant of UDCA received abatacept 125 mg s.q. weekly for 24 weeks. The co-primary endpoint was ALP normalization or a >40% reduction from baseline. Among 16 subjects enrolled and who received at least 1 dose of abatacept, 1 (6.3%) met the co-primary endpoint. Absolute and percent changes in ALP [median (95% CI)] were +2.8 U/L (-90.9-96.6) and -0.28% (-21.1-15.5), respectively. No significant changes were observed in ALP, ALT, total bilirubin, albumin, immunoglobulins, or liver stiffness. Abatacept treatment decreased several non-terminally differentiated CD4+ but not CD8+ T cell populations, including decreases in CD4+ CCR5+ (p = 0.02) and CD4+ PD1+ (p = 0.03) lymphocytes. In contrast there were increases in CD4+ CCR7+ lymphocytes (p = 0.034). Treatment emergent adverse events occurred in 4 subjects. Abatacept was well tolerated in this population of PBC patients but like other biologics in PBC was ineffective in achieving biochemical responses associated with improved clinical outcomes.

Microbiota and Food Allergy.

Emerging evidence suggests that the increasing prevalence of food allergies is associated with compositional and functional changes in our gut microbiota. Microbiota-host interactions play a key role in regulating the immune system. Development of a healthy gut microbiota and immune system occurs early in life and is largely shaped by exposure to maternal microbes through vaginal/natural delivery and breast milk, whereas use of antibiotics can disrupt gut homeostasis and significantly raise the risk of allergic diseases. Thus, changes in the quantity or diversity of gut microbes affect oral toleranace through interations of microbial molecules with pattern recognition receptors on immune cells and confer susceptibility to food allergies. On the other hand, short chain fatty acids which are fermentation end products of insoluble fibers by intestinal micoorganisms have been shown to confer protective effects on food allergy. As a preventive and therapeutic treatment for food allergies, probiotics have gained widespread attention in recent years. Reintroducing certain commensal microbes, such as Clostridia, both in animal models and clinical trials led to the prevention or resolution of allergic symptoms. This review highlights recent progress in our understanding of the gut microbiota's role in food allergy. However, mechanistic details underlying the anti-allergic effects of probiotics and the interaction between the gut microbiota and the immune system remain circumstantial and are not fully understood. Future studies should address possible factors and underlying mechanisms for microbiota-host interactions and gut immunity, as well as the efficacy, safety, and appropriate use of probiotics in establishing a standard treatment regimen for food allergies.

Anti-drug Antibodies Against a Novel Humanized Anti-CD20 Antibody Impair Its Therapeutic Effect on Primary Biliary Cholangitis in Human CD20- and FcγR-Expressing Mice.

There is considerable interest in expanding B cell-targeted therapies in human autoimmune diseases. However, clinical trials in human primary biliary cholangitis (PBC) using a chimeric antibody against human CD20 (hCD20) have showed limited efficacy. Two potential explanations for these disappointing results are the appearance of anti-drug antibodies (ADAs) and the high frequency of patients with moderate PBC or patients who had failed ursodeoxycholic acid treatment. Here, we studied a novel humanized IgG1 antibody against hCD20 and explored its efficacy in early stage PBC using a well-defined murine model. We developed a unique murine model consisting of dnTGF-ßRII mice expressing hCD20 and human Fcγ receptors (hFcγRs). Beginning at 4-6 weeks of age, equivalent to stage I/II human PBC, female mice were given weekly injections of an anti-hCD20 antibody (TKM-011) or vehicle control, and monitored for liver histology as well as a broad panel of immunological readouts. After 16 weeks' treatment, we observed a significant reduction in portal inflammation, a decrease in liver-infiltrating mononuclear cells as well as a reduction in liver CD8+ T cells. Importantly, direct correlations between numbers of liver non-B cells and B cells (r = 0.7426, p = 0.0006) and between numbers of liver memory CD8+ T cells and B cells (r = 0.6423, p = 0.0054) were apparent. Accompanying these changes was a dramatic reduction in anti-mitochondrial antibodies (AMAs), interleukin (IL)-12p40 and IL-5, and elevated levels of the anti-inflammatory chemokine CXCL1/KC. In mice that developed ADAs, clinical improvements were less pronounced. Sustained treatment with B cell-targeted therapies may broadly inhibit effector pathways in PBC, but may need to be administered early in the natural history of PBC.

Proteomic analysis reveals distinctive protein profiles involved in CD8+ T cell-mediated murine autoimmune cholangitis.

Autoimmune cholangitis arises from abnormal innate and adaptive immune responses in the liver, and T cells are critical drivers in this process. However, little is known about the regulation of their functional behavior during disease development. We previously reported that mice with T cell-restricted expression of a dominant negative form of transforming growth factor beta receptor type II (dnTGFßRII) spontaneously develop an autoimmune cholangitis that resembles human primary biliary cholangitis (PBC). Adoptive transfer of CD8+ but not CD4+ T cells into Rag1-/- mice reproduced the disease, demonstrating a critical role for CD8+ T cells in PBC pathogenesis. Herein, we used SOMAscan technology to perform proteomic analysis of serum samples from dnTGFßRII and B6 control mice at different ages. In addition, we analyzed CD8 protein profiles after adoptive transfer of splenic CD8+ cells into Rag1-/- recipients. The use of the unique SOMAscan aptamer technology revealed critical and distinct profiles of CD8 cells, which are key to biliary mediation. In total, 254 proteins were significantly increased while 216 proteins were significantly decreased in recipient hepatic CD8+ cells compared to donor splenic CD8+ cells. In contrast to donor splenic CD8+ cells, recipient hepatic CD8+ cells expressed distinct profiles for proteins involved in chemokine signaling, focal adhesion, T cell receptor and natural killer cell-mediated cytotoxicity pathways.

The interplay of type I and type II interferons in murine autoimmune cholangitis as a basis for sex-biased autoimmunity.

We have reported on a murine model of autoimmune cholangitis, generated by altering the AU-rich element (ARE) by deletion of the interferon gamma (IFN-γ) 3' untranslated region (coined ARE-Del-/- ), that has striking similarities to human primary biliary cholangitis (PBC) with female predominance. Previously, we suggested that the sex bias of autoimmune cholangitis was secondary to intense and sustained type I and II IFN signaling. Based on this thesis, and to define the mechanisms that lead to portal inflammation, we specifically addressed the hypothesis that type I IFNs are the driver of this disease. To accomplish these goals, we crossed ARE-Del-/- mice with IFN type I receptor alpha chain (Ifnar1) knockout mice. We report herein that loss of type I IFN receptor signaling in the double construct of ARE-Del-/- Ifnar1-/- mice dramatically reduces liver pathology and abrogated sex bias. More importantly, female ARE-Del-/- mice have an increased number of germinal center (GC) B cells as well as abnormal follicular formation, sites which have been implicated in loss of tolerance. Deletion of type I IFN signaling in ARE-Del-/- Ifnar1-/- mice corrects these GC abnormalities, including abnormal follicular structure. CONCLUSION: Our data implicate type I IFN signaling as a necessary component of the sex bias of this murine model of autoimmune cholangitis. Importantly these data suggest that drugs that target the type I IFN signaling pathway would have potential benefit in the earlier stages of PBC. (Hepatology 2018;67:1408-1419).

Common Variable Immunodeficiency and Liver Involvement.

Common variable immunodeficiency (CVID) is a primary B-cell immunodeficiency disorder, characterized by remarkable hypogammaglobulinemia. The disease can develop at any age without gender predominance. The prevalence of CVID varies widely worldwide. The underlying causes of CVID remain largely unknown; primary B-cell dysfunctions, defects in T cells and antigen-presenting cells are involved. Although some monogenetic defects have been identified in some CVID patients, it is likely that CVID is polygenic. Patients with CVID develop recurrent and chronic infections (e.g., bacterial infections of the respiratory or gastrointestinal tract), autoimmune diseases, lymphoproliferation, malignancies, and granulomatous lesions. Interestingly, autoimmunity can be the only clinical manifestation of CVID at the time of diagnosis and may even develop prior to hypogammaglobulinemia. The diagnosis of CVID is largely based on the criteria established by European Society for Immunodeficiencies and Pan-American Group for Immunodeficiency (ESID/PAGID) and with some recent modifications. The disease can affect multiple organs, including the liver. Clinical features of CVID patients with liver involvement include abnormal liver biochemistries, primarily elevation of alkaline phosphatase (ALP), nodular regenerative hyperplasia (NRH), or liver cirrhosis and its complications. Replacement therapy with immunoglobulin (Ig) and anti-infection therapy are the primary treatment regimen for CVID patients. No specific therapy for liver involvement of CVID is currently available, and liver transplantation is an option only in select cases. The prognosis of CVID varies widely. Further understanding in the etiology and pathophysiology will facilitate early diagnosis and treatments to improve prognosis.

Autoreactive monoclonal antibodies from patients with primary biliary cholangitis recognize environmental xenobiotics.

A major problem in autoimmunity has been identification of the earliest events that lead to breach of tolerance. Although there have been major advances in dissecting effector pathways and the multilineage immune responses to mitochondrial self-antigens in primary biliary cholangitis, the critical links between environmental factors and tolerance remain elusive. We hypothesized that environmental xenobiotic modification of the E2 subunit of the pyruvate dehydrogenase (PDC-E2) inner lipoyl domain can lead to loss of tolerance to genetically susceptible hosts. Previously we demonstrated that serum anti-PDC-E2 autoantibodies cross-react with the chemical xenobiotics 2-octynoic acid and 6,8-bis (acetylthio) octanoic acid and further that there is a high frequency of PDC-E2-specific peripheral plasmablasts. Herein we generated 104 recombinant monoclonal antibodies (mAbs) based on paired heavy-chain and light-chain variable regions of individual plasmablasts derived from primary biliary cholangitis patients. We identified 32 mAbs reactive with native PDC-E2, including 20 specific for PDC-E2 and 12 cross-reactive with both PDC-E2 and 2-octynoic acid and 6,8-bis (acetylthio) octanoic acid. A lower frequency of replacement somatic hypermutations, indicating a lower level of affinity maturation, was observed in the complementarity-determining regions of the cross-reactive mAbs in comparison to mAbs exclusively recognizing PDC-E2 or those for irrelevant antigens. In particular, when the highly mutated heavy-chain gene of a cross-reactive mAb was reverted to the germline sequence, the PDC-E2 reactivity was reduced dramatically, whereas the xenobiotic reactivity was retained. Importantly, cross-reactive mAbs also recognized lipoic acid, a mitochondrial fatty acid that is covalently bound to PDC-E2. CONCLUSION: Our data reflect that chemically modified lipoic acid or lipoic acid itself, through molecular mimicry, is the initial target that leads to the development of primary biliary cholangitis. (Hepatology 2017;66:885-895).

The modulation of co-stimulatory molecules by circulating exosomes in primary biliary cirrhosis.

Exosomes are nanoparticles of endocytic origin, secreted by a myriad of cell populations that are attracting increased attention by virtue of their ability to modulate cell-to-cell communications. They are also attracting attention in a variety of immunological issues, including autoimmunity and, in particular, their ability to regulate cytokine and chemokine activation. Primary biliary cirrhosis (PBC) is considered a model autoimmune disease, which has a highly focused cytotoxic response against biliary epithelial cells. We have isolated exosomes from plasma from 29 patients with PBC and 30 healthy controls (HCs), and studied the effect of these exosomes on co-stimulatory molecule expression and cytokine production in mononuclear cell populations using an ex vivo system. We also identified the microRNA (miRNA) populations in PBC compared to HC exosomes. We report herein that although exosomes do not change cytokine production, they do significantly alter co-stimulatory molecule expression on antigen-presenting populations. Further, we demonstrated that CD86 up-regulated expression on CD14+ monocytes, whereas CD40 up-regulated on CD11c+ dendritic cells by exosomes from patients with PBC. In addition, there were differences of miRNA expression of circulating exosomes in patients with PBC. These data have significant importance based on observations that co-stimulatory molecules play a differential role in the regulation of T-cell activation. Our observation indicated that aberrant exosomes from PBC selectively induce expression of co-stimulatory molecules in different subset of antigen-presenting cells. These alterations may involve in pathogenesis of autoimmune liver disease.Cellular & Molecular Immunology advance online publication, 21 September 2015; doi:10.1038/cmi.2015.86.

Isolation and characterization of adenoviruses infecting endangered golden snub-nosed monkeys (Rhinopithecus roxellana).

BACKGROUND: Adenoviruses are important pathogens with the potential for interspecies transmission between humans and non-human primates. Although many adenoviruses have been identified in monkeys, the knowledge of these viruses from the Colobinae members is quite limited. FINDINGS: We conducted a surveillance of viral infection in endangered golden snub-nosed monkeys (Rhinopithecus roxellana) in the subfamily Colobinae in China, and found that 5.1% of sampled individuals were positive for adenovirus. One of the adenoviruses (SAdV-WIV19) was successfully isolated and its full-length genome was sequenced. The full-length genome of WIV19 is 33,562 bp in size, has a G + C content of 56.2%, and encodes 35 putative genes. Sequence analysis revealed that this virus represents a novel species in the genus Mastadenovirus. Diverse cell lines, including those of human origin, were susceptible to WIV19. CONCLUSION: We report the first time the isolation and full-length genomic characterization of an adenovirus from the subfamily Colobinae.

Chronic expression of interferon-gamma leads to murine autoimmune cholangitis with a female predominance.

UNLABELLED: In most autoimmune diseases the serologic hallmarks of disease precede clinical pathology by years. Therefore, the use of animal models in defining early disease events becomes critical. We took advantage of a "designer" mouse with dysregulation of interferon gamma (IFNγ) characterized by prolonged and chronic expression of IFNγ through deletion of the IFNγ 3'-untranslated region adenylate uridylate-rich element (ARE). The ARE-Del(-/-) mice develop primary biliary cholangitis (PBC) with a female predominance that mimics human PBC that is characterized by up-regulation of total bile acids, spontaneous production of anti-mitochondrial antibodies, and portal duct inflammation. Transfer of CD4 T cells from ARE-Del(-/-) to B6/Rag1(-/-) mice induced moderate portal inflammation and parenchymal inflammation, and RNA sequencing of liver gene expression revealed that up-regulated genes potentially define early stages of cholangitis. Interestingly, up-regulated genes specifically overlap with the gene expression signature of biliary epithelial cells in PBC, implying that IFNγ may play a pathogenic role in biliary epithelial cells in the initiation stage of PBC. Moreover, differentially expressed genes in female mice have stronger type 1 and type 2 IFN signaling and lymphocyte-mediated immune responses and thus may drive the female bias of the disease. CONCLUSION: Changes in IFNγ expression are critical for the pathogenesis of PBC. (Hepatology 2016;64:1189-1201).

[Monitoring of sentinel mice and risk assessment of schistosomiasis transmission in key regions of Yunnan Province in 2014].

OBJECTIVE: To establish and perfect the surveillance and forecast system of schistosomiasis, and timely discover the suspicious high risk environments for preventing the human and livestock from schistosomiasis. METHODS: Eight villages of three counties were selected as survey points. Then, the surveillance and forecast of sentinel mice were carried out in the key water regions. The recovered sentinel mice were dissected in laboratory. The sentinel mouse serum antibodies against schistosome were detected by ELISA, the suspicious water contacts of residents and livestock were investigated and the results were analyzed, and the epidemic risk was assessed. RESULTS: Totally 300 sentinel mice were placed, the recovery rate was 94.67%, and the mortality rate was 8.80%. There were no mice with positive serum antibodies against schistosome, and the results of the dissection of all the sentinel mice were negative. The humans who contacted with the suspicious water were mainly villagers, students, children and fishermen by washing hands and feet, washing vegetables, harvesting, fishing and swimming. The Oncomelania hupensis snail areas, human infection rates, and cattle infection rates were obviously declined in recent 3 years. However, the epidemic risks still existed. CONCLUSION: Although schistosomiasis transmission was effectively controlled in the three counties, the comprehensive control measures still should be strengthened.

Animal models of primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is characterized histologically by the presence of chronic non-suppurative destructive cholangitis of the small interlobular bile duct, leading to chronic progressive cholestasis. Most PBC patients are asymptomatic and have a reasonable prognosis, but a few develop esophageal varices or jaundice, rapidly leading to liver failure within a short period. As multiple factors appear to be involved in the onset of PBC, its clinical course may be complicated. Therefore, the use of an animal model would be valuable for clarifying the pathogenesis of PBC. Here, we review recent data of selected PBC models, particularly spontaneous models, xenobiotic immunized models, and infection-triggered models. There are a number of spontaneous models: the NOD.c3c4, dominant-negative TGF-ß receptor II, IL-2Rα-/-, Scurfy, and Ae2a,b-/- mice. These animal models manifest distinct clinical and immunological features similar, but also often different, from those of human PBC. It is clear that a combination of genetic predisposition, environmental factors, and immunological dysfunction contribute to the pathogenesis of PBC. The diverse clinical course and complexity of the immunological mechanisms of PBC cannot be fully recapitulated solely any single animal model. The challenge remains to develop a progressive PBC disease model that exhibits fibrosis, and ultimately hepatic failure.

Ongoing activation of autoantigen-specific B cells in primary biliary cirrhosis.

UNLABELLED: The serologic hallmark of primary biliary cirrhosis (PBC), the antimitochondrial response to the E2 component of the pyruvate dehydrogenase complex (PDC-E2), has unique features, including continuous high titers of immunoglobulin M (IgM) and IgG reactivity throughout all stages of disease, capable not only of target enzyme inhibition, but also crossreactive with chemical xenobiotics that share molecular homology with the inner lipoyl domain of PDC-E2; such chemicals have been proposed as potential etiological agents. We used flow cytometry and enzyme-linked immunospot assay (ELISPOT) to examine B-cell subsets in 59 subjects, including 28 with PBC, 13 with primary sclerosing cholangitis (PSC), and 18 healthy controls. Strikingly, in PBC, although there were no significant differences in B-cell phenotype subpopulations, 10% of the total IgG and IgA plasmablast population and 23% of the IgM plasmablast population were uniquely reactive with PDC-E2, detected in the CXCR7+ CCR10low plasmablast population. In contrast, plasmablast reactivity to a control antigen, tetanus toxoid, was minimal and similar in all groups. Additionally, we isolated plasmablast-derived polyclonal antibodies and compared reactivity with plasma-derived antibodies and noted a distinct noncirculating tissue source of xenobiotic crossreacting antibodies. The high levels of autoantigen specific peripheral plasmablasts indicate recent activation of naive or memory B cells and a continuous and robust activation. The presence of CXCR7+ CCR10low PDC-E2-specific ASCs suggests a mechanistic basis for the migration of circulating antigen specific plasmablasts to the mucosal epithelial ligands CXCL12 and CCL28. CONCLUSION: Our findings suggest a sustained rigorous B-cell response in PBC, likely activated and perpetuated by cognate autoantigen.

Animal models of primary biliary cirrhosis.

Within the last decade, several mouse models that manifest characteristic features of primary biliary cirrhosis (PBC) with antimitochondrial antibodies (AMAs) and immune-mediated 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-ß receptor II [dnTGFßRII]) 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.

Murine autoimmune cholangitis requires two hits: cytotoxic KLRG1(+) CD8 effector cells and defective T regulatory cells.

Primary biliary cirrhosis (PBC) is an enigmatic disease mediated by autoimmune destruction of cholangiocytes in hepatic bile ducts. The early immunological events leading to PBC are poorly understood; clinical signs of disease occur very late in the pathological process. We have used our unique murine model of PBC in dominant-negative TGF-ß receptor type II transgenic mice to delineate critical early immunopathological pathways, and previously showed that dnTGFßRII CD8 T cells transfer biliary disease. Herein we report significantly increased numbers of hepatic dnTGFßRII terminally differentiated (KLRG1(+)) CD8 T cells, a CD8 subset previously shown to be enriched in antigen specific cells during hepatic immune response to viral infections. We performed bone marrow chimera studies to assess whether dnTGFßRII CD8 mediated disease was cell intrinsic or extrinsic. Unexpectedly, mixed (dnTGFßRII and B6) bone marrow chimeric (BMC) mice were protected from biliary disease compared to dnTGFßRII single bone marrow chimerics. To define the protective B6 cell subset, we performed adoptive transfer studies, which showed that co-transfer of B6 Tregs prevented dnTGFßRII CD8 T cell mediated cholangitis. Treg mediated disease protection was associated with significantly decreased numbers of hepatic KLRG1(+) CD8 T cells. In contrast, co-transfer of dnTGFßRII Tregs offered no protection, and dnTGFßRII Treg cells were functionally defective in suppressing effector CD8 T cells in vitro compared to wild type B6 Tregs. In vitro cholangiocyte cytotoxicity assays demonstrated significantly increased numbers of cytotoxic hepatic dnTGFßRII KLRG1(+) CD8 cells compared to B6. Protection from disease by B6 Tregs was associated with elimination of hepatic dnTGFßRII CD8 mediated cholangiocyte cytotoxicity. These results emphasize that autoimmune cholangitis requires defects in both the T effector and regulatory compartments, and that an intrinsic T cell effector defect is not sufficient to mediate autoimmune biliary disease in the setting of intact immune regulation. These results have important implications for understanding the early pathogenesis of human PBC.

IL-12/Th1 and IL-23/Th17 biliary microenvironment in primary biliary cirrhosis: implications for therapy.

UNLABELLED: The interleukin (IL)-12/IL-23-mediated Th1/Th17 signaling pathway has been associated with the etiopathogenesis of primary biliary cirrhosis (PBC). To address the cytokine microenvironment specifically in the liver, we examined the localized expression of cytokine subunits and their corresponding receptors using previously optimized immunohistochemistry with an extensive panel of antibodies directed at IL-12p70, IL-12p35, interferon-gamma (IFN-γ), IL-12RB2, IL-23p40, IL-23p19, IL-17, and IL-23R using liver from PBC (n = 51) and non-PBC (n = 80) control liver disease patients. Multiple portal tracts in each patient were blindly evaluated and individually scored. We report herein that although IL-12/Th1 and IL-23/Th17 staining was detected in all of the liver sections, they were primarily localized around the damaged interlobular bile ducts in PBC. Most important, Th17 skewing was prominent in advanced PBC patients with intensive secretion of IL-23p19 by inflamed hepatocytes around IL-23R, IL-12RB2, and IFN-γ expressing degenerated cholangiocytes. Our novel finding on the direct association of Th17 skewing and disease severity illustrates the significance of the IL-23/Th17 pathway in the perpetuation of IL-12/Th1-mediated immunopathology in PBC. Furthermore, localized IL-23p19 production by hepatocytes may enhance profibrotic Th17 signaling and proinflammatory IFN-γ production that contribute to PBC pathology. CONCLUSION: Our data emphasize the pathogenic relevance of IL-12/Th1 and IL-23/Th17 in the evolution of PBC. Of significance, however, the shift from a Th1 to a Th17 imbalance at advanced stages of the disease suggests the necessity to consider modulation of the IL-23/Th17 pathway as a potential target for therapeutic intervention.

Identification of potential cytokine pathways for therapeutic intervention in murine primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is considered a model autoimmune disease, with the most highly directed and specific autoantibody in both murine and human autoimmunity, the anti-mitochondrial autoantibody (AMA). However, therapeutic advances in this disease have lagged behind. Herein we have taken advantage of our unique model of murine PBC in which mice immunized with 2-octynoic acid coupled to BSA (2OA-BSA), a compound identified by quantitative structure activity relationships (QSAR) of human AMA binding, develop an intense inflammatory cholangitis with striking similarities to humans with PBC. In particular, we have constructed several unique gene-deleted mice, including mice deleted of IL-12p40, IL-12p35, IFN-γ, IL-23p19, IL-17A, IL-17F and IL-22, immunized these animals with 2OA-BSA and followed the natural history of immunopathology to identify key pathways that might provide clues for successful therapy. Our data indicate that whereas both IL-12/Th1 and IL-23/Th17 are involved in cholangitis, it is the IL-12/Th1 signaling pathway that elicits pathology. 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; IL-17A-knockout mice have reduced levels of anti-mitochondrial antibody. We further demonstrate that the production of IFN-γ is significantly decreased in the liver 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. Our data indicate that a deficient Th17 pathway suppresses the accumulation of IFN-γ producing cells in liver during the early phase of cholangitis. In conclusion, whereas IFN-γ has a pivotal role in the early events involved in the pathogenesis of autoimmune cholangitis induced by 2OA-BSA, the IL-23/Th17 pathway potentiates the effects of IL-12/IFN-γ-mediated immunopathology.

Clonality, activated antigen-specific CD8(+) T cells, and development of autoimmune cholangitis in dnTGFßRII mice.

UNLABELLED: There are several murine models described with features similar to human primary biliary cirrhosis (PBC). Among these models, the one which has the closest serologic features to PBC is a mouse with a T-cell-restricted expression of the dominant negative transforming growth factor ß receptor type II (dnTGFßRII). Our work has demonstrated that CD8(+) T cells from dnTGFßRII mice transfer autoimmune cholangitis to Rag1(-/-) recipients. However, it remained unclear whether the autoimmune cholangitis was secondary to an intrinsic function within CD8(+) T cells or due to the abnormal TGFßR environment within which CD8(+) T cells were generated. To address this mechanistic issue, we used our dnTGFßRII, OT-I/Rag1(-/-) , OT-II/Rag1(-/-) mice and in addition generated OT-I/dnTGFßRII/Rag1(-/-) , and OT-II/dnTGFßRII/Rag1(-/-) mice in which the entire T-cell repertoire was replaced with ovalbumin (OVA)-specific CD8(+) or CD4(+) T cells, respectively. Importantly, neither the parental OT-I/dnTGFßRII/Rag1(-/-) mice and/or OT-II/dnTGFßRII/Rag1(-/-) mice developed cholangitis. However, adoptive transfer demonstrated that only transfer of CD8(+) T cells from dnTGFßRII mice but not CD8(+) T cells from OT-I/Rag1(-/-) mice or from OT-I/dnTGFßRII/Rag1(-/-) mice transferred disease. These data were not secondary to an absence of CD4(+) T cell help since a combination of CD8(+) T cells from OT-I/dnTGFßRII/Rag1(-/-) and CD4(+) T cells from OT II/dnTGFßRII/Rag1(-/-) or CD8(+) T cells from OT-I/dnTGFßRII/Rag1(-/-) with CD4(+) T cells from OT-II/Rag1(-/-) mice failed to transfer disease. CONCLUSION: Defective TGFßRII signaling, in addition to clonal CD8(+) T cells that target biliary cells, are required for induction of autoimmune cholangitis.