Qixia Wang

Interleukin-17 Contributes to the Pathogenesis of Autoimmune Hepatitis through Inducing Hepatic Interleukin-6 Expression

T helper cells that produce IL-17 (Th17 cells) have recently been identified as the third distinct subset of effector T cells. Emerging data suggests that Th17 cells play an important role in the pathogenesis of many liver diseases by regulating innate immunity, adaptive immunity, and autoimmunity. In this study, we examine the role and mechanism of Th17 cells in the pathogenesis of autoimmune hepatitis (AIH). The serum levels of IL-17 and IL-23, as well as the frequency of IL-17+ cells in the liver, were significantly elevated in patients with AIH, compared to other chronic hepatitis and healthy controls. The hepatic expressions of IL-17, IL-23, ROR-γt, IL-6 and IL-1β in patients with AIH were also significantly increased and were associated with increased inflammation and fibrosis. IL-17 induces IL-6 expression via the MAPK signaling pathway in hepatocytes, which, in turn, may further stimulate Th17 cells and forms a positive feedback loop. In conclusion, Th17 cells are key effector T cells that regulate the pathogenesis of AIH, via induction of MAPK dependent hepatic IL-6 expression. Blocking the signaling pathway and interrupting the positive feedback loop are potential therapeutic targets for autoimmune hepatitis.

Interleukin-17 exacerbates hepatic steatosis and inflammation in non-alcoholic fatty liver disease

Mechanisms associated with the progression of simple steatosis to non‐alcoholic fatty liver disease (NAFLD) remain undefined. Regulatory T cells (Tregs) play a critical role in regulating inflammatory processes in non‐alcoholic steatohepatitis (NASH) and because T helper type 17 (Th17) functionally oppose Treg‐mediated responses, this study focused on characterizing the role of Th17 cells using a NAFLD mouse model. C57BL/6 mice were fed either a normal diet (ND) or high fat (HF) diet for 8 weeks. Mice in the HF group had a significantly higher frequency of liver Th17 cells compared to ND‐fed mice. Neutralization of interleukin (IL)‐17 in HF mice ameliorated lipopolysaccharide (LPS)‐induced liver injury reflected by decreased serum alanine aminotransferase (ALT) levels and reduced inflammatory cell infiltrates in the liver. In vitro, HepG2 cells cultured in the presence of free fatty acids (FFA; oleic acid and palmitic acid) for 24 h and IL‐17 developed steatosis via insulin‐signalling pathway interference. IL‐17 and FFAs synergized to induce IL‐6 production by HepG2 cells and murine primary hepatocytes which, in combination with transforming growth factor (TGF‐β), expanded Th17 cells. It is likely that a similar process occurs in NASH patients, as there were significant levels of IL‐17+ cell infiltrates in NASH patient livers. The hepatic expression of Th17 cell‐related genes [retinoid‐related orphan receptor gamma (ROR)γt, IL‐17, IL‐21 and IL‐23] was also increased significantly in NASH patients compared to healthy controls. Th17 cells and IL‐17 were associated with hepatic steatosis and proinflammatory response in NAFLD and facilitated the transition from simple steatosis to steatohepatitis. Strategies designed to alter the balance between Th17 cells and Tregs should be explored as a means of preventing progression to NASH and advanced liver diseases in NAFLD patients.

Validation of the simplified criteria for diagnosis of autoimmune hepatitis in Chinese patients

BACKGROUND & AIMS In 1999, the International Autoimmune Hepatitis Group (IAIHG) revised the diagnostic criteria for autoimmune hepatitis (AIH). It subsequently developed the simplified criteria in 2008 to enhance clinical applicability and practicability. In this study, we validated the simplified diagnostic criteria in Chinese patients with AIH or other chronic liver diseases in comparison with the revised original criteria. METHODS Diagnostic scores were determined using the revised original criteria and the simplified criteria in 405 patients with diverse liver diseases. The sample included 127 patients with AIH type I diagnosed by the descriptive criteria, 77 patients with primary biliary cirrhosis (PBC), 6 patients with AIH-PBC overlap syndrome, 47 patients with drug-induced liver injury (DILI), 36 patients with non-alcoholic steatohepatitis (NASH), 82 patients with chronic hepatitis B (CHB), and 30 patients with chronic hepatitis C (CHC). The simplified criteria were compared to the revised original criteria based on sensitivity, specificity, and predictability for the pre-treatment diagnosis of AIH. RESULTS The simplified criteria had sensitivity and specificity of 90% and 95%, respectively, for the diagnosis of probable AIH in the Chinese patients. This compares well with the more rigorous revised original criteria, which had sensitivity and specificity of 100% and 93%, respectively, for probable AIH. On definite AIH, the simplified criteria had sensitivity and specificity of 62% and 99%, respectively, compared to 64% and 100% for definite AIH by the revised original criteria. In addition, the predictabilities of the revised original criteria and simplified criteria were 96% and 94% for probable AIH, and 88% and 87% for definite AIH, respectively, in our groups. Using the revised original criteria, 84 patients were diagnosed with definite AIH. On the other hand, among these 84 patients, the simplified criteria diagnosed only 61 patients with definite AIH (accordant diagnosis) and provided the 23 other patients with downgraded diagnosis. Comparison of the clinical and laboratory features of these two groups (accordant diagnosis vs. downgraded/excluded diagnosis) showed that the patients with downgraded diagnosis had significantly higher histological scores than the patients with accordant diagnosis. CONCLUSIONS The simplified criteria are comparable to the revised original criteria and have high sensitivity and specificity for the diagnosis of AIH in Chinese patients. Liver histology is critical for the diagnosis of AIH especially when using the simplified criteria. Further study or prospective evaluation is needed to confirm these observations, however, due to the small group of CHC patients as well as the absence of primary sclerosing cholangitis (PSC) patients in our study.

The clinical phenotypes of autoimmune hepatitis: A comprehensive review.

Autoimmune hepatitis (AIH) fulfills the generally accepted contemporary criteria of an autoimmune liver disease: the presence of autoantibodies and autoreactive T cells, a female gender bias, association with other autoimmune diseases, response to immunosuppressive therapy and strong associations with the major histocompatibility complex HLA loci. It occurs worldwide in both children and adults and is marked by both etiopathogenic and clinical heterogeneity, differing from the other putative autoimmune liver diseases, primary biliary cirrhosis (PBC) and primary sclerosing cholangitis (PSC), albeit occasionally presenting with overlapping features of PBC or PSC. Although diagnostic criteria have been established and validated, there are still major issues to be clarified due to its variability, such as autoantibody-negative AIH, drug-induced AIH, AIH sharing features with PBC or PSC, and post-transplant de novo AIH. In view of the diverse presentations and courses, including classical chronic onset, acute and acute severe onset, cirrhosis and decompensated cirrhosis, individualized management of patients is indicated. Each patient should receive a personalized analysis of the benefits and side effect risks of drugs. Herein we describe a comprehensive review of the clinical phenotypes of AIH underscoring its clinical heterogeneity.

THE IMMUNOPATHOLOGY OF LIVER GRANULOMAS IN PRIMARY BILIARY CIRRHOSIS

Liver granulomas and elevated serum IgM are commonly observed in patients with primary biliary cirrhosis (PBC) but their pathogenetic significance remains largely unknown. To address this issue we performed an extensive immunostaining and colocalization study of markers associated with dendritic cells and IgM in a large cohort of tissue samples from PBC and control livers as well as from non-hepatic granulomatous diseases. First, the classical dendritic cell CD11c marker is highly expressed and more sensitive than classical hematoxylin-eosin staining in detecting granulomas associated with PBC and other conditions. Second, PBC cases with CD11c-positive granulomas have significantly higher serum IgM levels and earlier disease stages. Third, granulomas from PBC and other diseases demonstrate markers of dendritic cell immaturity, i.e. CD11b, reduced MHC II, IL-23, CCR7 and CD83 expression, and elevated C1q expression. Lastly, B cells and IgM-positive plasma cells are largely represented around PBC granulomas along with macrophages. In conclusion, our comprehensive immunohistochemical study suggests that dendritic cells are key to the pathogenesis of granulomas, regardless of their origin. More specifically, PBC liver granulomas may result from the interaction between immature dendritic cells and IgM.

CCN1 expression in hepatocytes contributes to macrophage infiltration in nonalcoholic fatty liver disease in mice

Our objective was to investigate the potential roles of CCN1 in the inflammation and macrophage infiltration of nonalcoholic fatty liver disease (NAFLD). The regulation of hepatic CCN1 expression was investigated in vitro with murine primary hepatocytes treated with free fatty acids or lipopolysaccharide (LPS) and in vivo with high-fat (HF) diet-fed mice or ob/ob mice. CCN1 protein and a liver-specific CCN1 expression plasmid were administered to mice fed a normal diet (ND) or HF diet. Myeloid-derived macrophages and RAW264.7 cells were also treated with CCN1 in vitro to determine the chemotactic effects of CCN1 on macrophages. LPS treatment significantly increased hepatic CCN1 expression in HF diet-fed mice and ob/ob mice. LPS and FFAs induced CCN1 expression in primary murine hepatocytes in vitro through the TLR4/MyD88/AP-1 pathway. CCN1 protein and overexpression of CCN1 in the liver induced more severe hepatic inflammation and macrophage infiltrates in HF mice than in ND mice. CCN1 recruited macrophages through activation of the Mek/Erk signaling pathway in myeloid-derived macrophages and RAW264.7 cells in vitro. Endotoxin and FFA-induced CCN1 expression in hepatocytes is involved in the hepatic proinflammatory response and macrophage infiltration in murine NAFLD.

Gut microbial profile is altered in primary biliary cholangitis and partially restored after UDCA therapy

Objective A close relationship between gut microbiota and some chronic liver disorders has recently been described. Herein, we systematically performed a comparative analysis of the gut microbiome in primary biliary cholangitis (PBC) and healthy controls. Design We first conducted a cross-sectional study of 60 ursodeoxycholic acid (UDCA) treatment-naïve patients with PBC and 80 matched healthy controls. Second, an independent cohort composed of 19 treatment-naïve patients and 34 controls was used to validate the results. Finally, a prospective study was performed in a subgroup of 37 patients with PBC who underwent analysis before and after 6 months of UDCA treatment. Faecal samples were collected, and microbiomes were analysed by 16S ribosomal RNA gene sequencing. Results A significant reduction of within-individual microbial diversity was noted in PBC (p=0.03). A signature defined by decreased abundance of four genera and increased abundance of eight genera strongly correlated with PBC (area under curve=0.86, 0.84 in exploration and validation data, respectively). Notably, the abundance of six PBC-associated genera was reversed after 6 months of UDCA treatment. In particular, Faecalibacterium, enriched in controls, was further decreased in gp210-positive than gp210-negative patients (p=0.002). Of interest was the finding that the increased capacity for the inferred pathway, bacterial invasion of epithelial cells in PBC, highly correlated with the abundance of bacteria belonging to Enterobacteriaceae. Conclusions This study presents a comprehensive landscape of gut microbiota in PBC. Dysbiosis was found in the gut microbiome in PBC and partially relieved by UDCA. Our study suggests that gut microbiota is a potential therapeutic target and diagnostic biomarker for PBC.

The risk predictive values of UK-PBC and GLOBE scoring system in Chinese patients with primary biliary cholangitis: the additional effect of anti-gp210

Adequate risk stratification is critical for the management of the patients with primary biliary cholangitis (PBC). The UK‐PBC and GLOBE scoring systems for prognosis of PBC have been proposed recently, but have not been validated in Asian population.

Autoimmune hepatitis: East meets west.

Autoimmune hepatitis (AIH) is an inflammatory liver disease with diverse clinical spectrum, which predominantly affects females. This review provides detailed comparisons of epidemiology, genetic predispositions, clinical features, risk factors of hepatocellular carcinoma, and mortality in AIH patients between eastern and western countries. AIH prevalence and incidence are lower in Asia‐Pacific area than in Europe and America. European and American patients seem to have more severe disease, characterized with human leukocyte antigen‐DR3 haplotype, younger age, more AIH‐induced “cirrhosis” at diagnosis, higher elevated serum immunoglobulin G levels, and positive rate of antisoluble liver antigen/liver pancreatitis. The overall AIH diagnostic accuracy of revised original criteria and simplified scoring system are similar in European/American populations and Asian. Cirrhosis at presentation and non‐response to immunosuppressive therapy within 1 year are the most important predictors for poor prognosis of AIH patients.

Treatment of cholestatic fibrosis by altering gene expression of Cthrc1: Implications for autoimmune and non-autoimmune liver disease.

Collagen triple helix repeat containing-1 (Cthrc1) is a documented specific inhibitor of TGF-β signaling. Based on this observation, we developed the hypothesis that knocking in/knocking out the Cthrc1 gene in murine models of cholestasis would alter the natural history of cholestatic fibrosis. To study this thesis, we studied two murine models of fibrosis, first, common bile duct ligation (CBDL) and second, feeding of 3, 5-diethoxy-carbonyl-1, 4-dihydrocollidine (DDC). In both models, we administered well-defined adenoviral vectors that expressed either Cthrc1 or, alternatively, a short hairpin RNA (shRNA)-targeting Cthrc1 either before or after establishment of fibrosis. Importantly, when Cthrc1 gene expression was enhanced, we noted a significant improvement of hepatic fibrosis, both microscopically and by analysis of fibrotic gene expression. In contrast, when Cthrc1 gene expression was deleted, there was a significant exacerbation of fibrosis. To identify the mechanism of action of these significant effects produced by knocking in/knocking out Cthrc gene expression, we thence studied the interaction of Cthrc1 gene expression using hepatic stellate cells (HSCs) and human LX-2 cells. Importantly, we demonstrate that Cthrc1 is induced by TGF-β1 via phospho-Smad3 binding to the promoter with subsequent transcription activation. In addition, we demonstrate that Cthrc1 inhibits TGF-β signaling by accelerating degradation of phospho-Smad3 through a proteosomal pathway. Importantly, the anti-fibrotic effects can be recapitulated with a truncated fragment of Cthrc1. In conclusion, our findings uncover a critical negative feedback regulatory loop in which TGF-β1 induces Cthrc1, which can attenuate fibrosis by accelerating degradation of phospho-Smad3.