Xiong Ma

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.

IL‐12/Th1 and IL‐23/Th17 biliary microenvironment in primary biliary cirrhosis: Implications for therapy

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. (Hepatology 2014;59:1944–1953)

Changing nomenclature for PBC: From ‘cirrhosis’ to ‘cholangitis’

T he disease entity today widely called ‘primary biliary cirrhosis’ was first described by Addison & Gull in 1851 and Hanot in 1876. One hundred years after its first description, MacMahon & Thannhauser proposed the term ‘xanthomatous biliary cirrhosis’ for this disease based on the typical xanthoma formation with accumulation of cholesterol esters in the skin around the eyes in association with inflammatory destruction of small intrahepatic bile ductules leading to a biliary type cirrhosis. Xanthoma formation, however, is not a very common sign in this disorder. This may be the reason why the term ‘primary biliary cirrhosis,’ proposed one year later for the same disorder by Ahrens et al., gained wider acceptance when most patients were presenting with advanced liver disease. Dame Sheila Sherlock, already in 1959, opposed the term ‘primary biliary cirrhosis’ as many of her patients were free of cirrhosis at the time of diagnosis and the mean survival was 5 and a half years (3-11) even for the fatal cases, whereas many asymptomatic patients would survive more than 10 years. The term ‘primary biliary cirrhosis’ remained an issue of concern as reflected by the name change proposal of Rubin, Schaffner and Popper in 1965 with their paper “Primary Biliary Cirrhosis— Chronic Nonsuppurative Destructive Cholangitis.” S. Sherlock wisely commented on this new name: ‘‘. . .a better one, although it is unlikely that it will replace the more popular, although inaccurate, one of primary biliary cirrhosis.’’ She was right, again. And even 40 years later, the European and American Clinical Practice Guidelines still used the term ‘primary biliary cirrhosis’ even though it was an anachronism and did not accurately reflect the natural history of disease in the vast majority of patients as it is today. The early diagnosis of primary biliary cirrhosis has dramatically improved with the more accurate measurements of markers of cholestasis and improvements in the detection of the classic serologic hallmark, anti-mitochondrial antibodies. Furthermore, the prognosis has dramatically improved with the introduction of orthotopic liver transplantation in the 1970s and 1980s, and of ursodeoxycholic acid (UDCA, 13-15 mg/kg daily) treatment in the 1980s and 1990s. Today, two out of three patients diagnosed with primary biliary cirrhosis and treated with UDCA have an expected survival not different from the general population and only a minority will ever develop cirrhosis. The pathogenesis of primary biliary cirrhosis remains enigmatic although enormous progress has been made in unravelling genetic, immunological and pathophysiological molecular mechanisms involved. This has also led to new therapeutic approaches which are now under evaluation.

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.

Changing Nomenclature for PBC: From ‘Cirrhosis’ to ‘Cholangitis’

The disease entity today widely called ‘primary biliary cirrhosis’ was first described by Addison and Gull in 18511 and Hanot in 1876.2 One hundred years after its first description, MacMahon and Thannhauser3 proposed the term ‘xanthomatous biliary cirrhosis’ for this disease based on the typical xanthoma formation with accumulation of cholesterol esters in the skin around the eyes in association with inflammatory destruction of small intrahepatic bile ductules leading to a biliary type cirrhosis. Xanthoma formation, however, is not a very common sign in this disorder. This may be the reason why the term ‘primary biliary cirrhosis’, proposed 1 year later for the same disorder by Ahrens et al ,4 gained wider acceptance when most patients were presenting with advanced liver disease. Dame Sheila Sherlock, already in 1959, opposed the term ‘primary biliary cirrhosis’ as many of her patients were free of cirrhosis at the time of diagnosis and the mean survival was 5 and a half years (3–11) even for the fatal cases, whereas many asymptomatic patients would survive more than 10 years.5 The term ‘primary biliary cirrhosis’ remained an issue of concern as reflected by the name change proposal of Rubin, Schaffner and Popper in 1965 with their paper ‘Primary biliary cirrhosis—Chronic non-suppurative destructive cholangitis’.6 Sherlock7 wisely commented on this new name: “…a better one, although it is unlikely that it will replace the more popular, although inaccurate, one of primary biliary cirrhosis”. She was right, again. And even 40 years later, the European8 and American9 Clinical Practice Guidelines still used the term ‘primary biliary cirrhosis’ even though it was an anachronism and did not accurately reflect the natural history of disease in the vast majority of patients as it is today. The early diagnosis of primary biliary cirrhosis has …

Common variable immunodeficiency and autoimmunity – an inconvenient truth ☆

Coexisting morbidities in CVID include bronchiectasis, autoimmunity and malignancies. The incidence of autoimmune disease in CVID patients may approach 20% of cases. The most common autoimmune disease found in CVID patients is autoimmune cytopenia, but rheumatoid arthritis, lupus, and now primary biliary cirrhosis have also been reported. The coexistence of immunodeficiency and autoimmunity appears paradoxical, since one represents a hypoimmune state and the other a hyperimmune state. However, this paradox may not actually be all that implausible due to the complex nature of immune cells, signaling pathways and their interactions. The cellular alterations in combined variable immunodeficiency include a range of T and B cell abnormalities. Selective immune derangements found in CVID include a downregulation of regulatory T cells (Treg cells), accelerated T cell apoptosis, abnormal cytokine production secondary to cytokine gene polymorphisms and increased autoreactive B cell production. The impact of these abnormalities on T and B cell interaction may not only explain the immunodeficiency but also the development of autoimmunity in select groups of patients with CVID. The variability in the clinical manifestations of CVID as a result of this immune interaction suggests that CVID is not one disease but many. This is important because it follows that the treatment of CVID may not always be the same, but may need to be directed specifically towards each individual patient.

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.