C. Corpechot

Genetic factors of susceptibility and of severity in primary biliary cirrhosis

BACKGROUND/AIMS In primary biliary cirrhosis (PBC), pathogenesis is influenced by genetic factors that remain poorly elucidated up to now. We investigated the impact of sequence diversity in candidate genes involved in immunity (CTLA-4 and TNFalpha), in bile formation (10 hepatobiliary transporter genes) and in the adaptative response to cholestasis (three nuclear receptor genes) on the susceptibility and severity of PBC. METHODS A total of 42 Ht SNPs were identified and compared in 258 PBC patients and two independent groups of 286 and 269 healthy controls. All participants were white continental individuals with French ancestry. RESULTS Ht SNPs of CTLA-4 and TNFalpha genes were significantly associated with susceptibility to PBC. The progression rate of liver disease under ursodeoxycholic acid (UDCA) therapy was significantly linked to SNPs of TNFalpha and SLC4A2/anion exchanger 2 (AE2) genes. A multivariate Cox regression analysis including clinical and biochemical parameters showed that SLC4A2/AE2 variant was an independent prognostic factor. CONCLUSIONS These data point to a primary role of genes encoding regulators of the immune system in the susceptibility to PBC. They also demonstrate that allelic variations in TNFalpha and SLC4A2/AE2 have a significant impact on the evolutive profile of PBC under UDCA therapy.

Gender and liver: is the liver stiffness weaker in weaker sex?

giving reference to published literature data. We agree that the mechanisms by which -catenin signaling might influence GS expression are not fully understood. However, in contrast to the statement that GS expression “is somehow dependent on -catenin signaling”, a fundamental role of -catenin in regulation of GS expression has been clearly established by several groups: (i) GS is expressed in all hepatocytes of mice carrying an activated -catenin transgene2 or a hepatocyte-targeted knockout of the -catenin antagonist APC.3 (ii) By contrast, mice with hepatocyte-specific knockout of -catenin or overexpression of the Wnt/ -catenin-signaling inhibitor DKK1 lack GS expression in liver.3,4 Notably, livers of -catenin knockout mice also lack expression of several cytochrome P450 isozymes,4 which are, like GS, overexpressed in liver tumors with mutated -catenin.5 The fact that the Wnt antagonist DKK1 blocks expression of GS and other perivenous markers in mouse liver3 indicates that Wnt molecules are indeed involved in regulation of several perivenous markers as suggested in our hypothesis.1 Gebhardt and Ueberham criticize that only perivenous hepatocytes might have responded to -catenin activation by Wnt or a GSK3 inhibitor.1 Earlier studies by Gebhardt’s group have shown, however, that GS can be induced in periportal hepatocytes by co-cultivation with endothelial-like cells,6 demonstrating that periportal hepatocytes are capable of responding to external stimuli that induce “perivenous” mRNAs. In addition, preferential localization of activated -catenin in perivenous hepatocytes has been demonstrated recently.3 Regarding Ras activation in periportal hepatocytes, we agree that no experimental data directly supporting this hypothesis are presented, but relevant indirect evidence has been cited in our recent paper.1 The statement that “many liver tumors with activated -catenin do not express GS” is made without giving any references and does not reflect previous results showing an almost 100% congruity between mutational activation of -catenin and GS expression, both in mouse and human liver tumors.2,5,7,8 The notion that “hepatocellular tumors develop rarely in response to -catenin mutation alone” does not apply to initiation/promotion experiments with phenobarbital which strongly selects for -catenin, but not Ha-ras mutated liver tumors in mice.9 We routinely screen liver tumors for mutations in both genes and can exclude a coincidental occurrence of -catenin and Ha-ras mutations, as suspected by Gebhardt and Ueberham. Following appearance of our paper,1 other studies have been published,3,4 supporting important parts of our hypothesis. We have also obtained new results, including serum effects on gene expression, which favor our original hypothesis. These data are described in a manuscript submitted for publication, which cannot be cited because it is presently undergoing the review process. STEPHAN HAILFINGER MAIKE JAWORSKI ALBERT BRAEUNING ALBRECHT BUCHMANN MICHAEL SCHWARZ Institute of Pharmacology and Toxicology Department of Toxicology University of Tübingen Tübingen, Germany

Portal myofibroblasts promote vascular remodeling underlying cirrhosis formation through the release of microparticles

Liver fibrosis expanding from portal tracts and vascular remodeling are determinant factors in the progression of liver diseases to cirrhosis. In the present study, we examined the potential contribution of portal myofibroblasts (PMFs) to the vascular changes leading to cirrhosis. The analyses of liver cells based on the transcriptome of rat PMFs, compared to hepatic stellate cell HSC‐derived myofibroblasts in culture, identified collagen, type XV, alpha 1 (COL15A1) as a marker of PMFs. Normal liver contained rare COL15A1‐immunoreactive cells adjacent to the bile ducts and canals of Hering in the portal area. A marked increase in COL15A1 expression occurred together with that of the endothelial marker, von Willebrand factor, in human and rat liver tissue, at advanced stages of fibrosis caused by either biliary or hepatocellular injury. In cirrhotic liver, COL15A1‐expressing PMFs adopted a perivascular distribution outlining vascular capillaries proximal to reactive ductules, within large fibrotic septa. The effect of PMFs on endothelial cells (ECs) was evaluated by in vitro and in vivo angiogenesis assays. PMF‐conditioned medium increased the migration and tubulogenesis of liver ECs as well as human umbilical vein ECs and triggered angiogenesis within Matrigel plugs in mice. In coculture, PMFs developed intercellular junctions with ECs and enhanced the formation of vascular structures. PMFs released vascular endothelial growth factor (VEGF)A‐containing microparticles, which activated VEGF receptor 2 in ECs and largely mediated their proangiogenic effect. Cholangiocytes potentiated the angiogenic properties of PMFs by increasing VEGFA expression and microparticle shedding in these cells. Conclusion: PMFs are key cells in hepatic vascular remodeling. They signal to ECs through VEGFA‐laden microparticles and act as mural cells for newly formed vessels, driving scar progression from portal tracts into the parenchyma. (Hepatology 2015;61:1041–1055)

Spleen size for the prediction of clinical outcome in patients with primary sclerosing cholangitis

Dear Sir, We read with interest the work of van der Meer et al 1 who propose a risk score for patients with chronic Hepatitis C. The authors demonstrate that the assessment of readily available and objective parameters can stratify patients according to the risk of disease progression. Patients with primary sclerosing cholangitis (PSC) usually develop progressive liver fibrosis and end-stage liver disease within 10–20 years.2 Simple and non-invasive means for disease stratification and prediction of prognosis are urgently needed. Indeed, the International PSC Study Group recently declared the research on surrogate end-point markers as a high-priority task,3 since several clinical studies investigating novel treatment strategies …

Primary sclerosing cholangitis response to the combination of fibrates with ursodeoxycholic acid: French–Spanish experience

BACKGROUND & AIMS In patients with primary sclerosing cholangitis (PSC), ursodeoxycholic acid (UDCA) treatment improves serum liver tests and surrogate markers of prognosis but has no proven effect on survival. Additional therapies are obviously needed. Fibrates, PPAR agonists with anti-cholestatic properties, have a beneficial effect in primary biliary cholangitis. The aim of this study was to evaluate the safety and efficacy of fibrates in PSC patients. METHODS Retrospectively, we investigated PSC patients treated with fibrates (fenofibrate 200mg/day or bezafibrate 400mg/day) for at least 6 months in addition to UDCA, after an incomplete biochemical response (alkaline phosphatase [ALP] ≥1.5×upper limit of normal) to UDCA. Changes in biochemical parameters and clinical features were assessed. RESULTS Twenty patients were included (fourteen from Paris and six from Barcelona): median age 43.8 years, median liver stiffness 11kPa (≥F3). Upon treatment with fibrates (median duration of 1.56 years), liver tests significantly improved, including a reduction of ALP levels by 41% and pruritus significantly decreased. No serious adverse event attributable to fibrates occurred. Discontinuation of fibrates was followed by a clear rebound of ALP. Despite biochemical improvement, liver stiffness significantly increased. CONCLUSIONS Combining UDCA with fibrates results in a significant biochemical improvement and pruritus decrease in PSC patients with incomplete response to UDCA. These results provide a rationale for larger and prospectively designed studies to establish the efficacy and safety of fibrates in PSC.