CD8+ T cells actively penetrate hepatocytes via the CD44/p-ERM/F-actin pathway in autoimmune hepatitis.

OBJECTIVE: Emperipolesis is a pathological feature for the diagnosis of autoimmune hepatitis (AIH). We have previously found that CD8+ T cells participated in the emperipolesis in AIH. In this study we aimed to clarify the characteristics and molecular mechanisms of emperipolesis in patients with AIH in vitro and in mice with α-Galactosylceramide (α-GalCer)-induced acute hepatitis. METHODS: The peripheral blood mononuclear cells (PBMC) of patients with various chronic liver diseases and healthy controls were co-cultured with hepatic cell lines to induce emperipolesis in vitro. Confocal staining was performed to illustrate the cellular types and potential mechanisms of emperipolesis in AIH. In addition, a murine model of α-GalCer-induced acute hepatitis that mimics human AIH was used to confirm the role of CD44/p-ERM/F-actin in the emperipolesis process in vivo. RESULTS: In the co-cultured system of PBMC and hepatic cell line, emperipolesis was observed most commonly in patients with AIH. The main cells participating in emperipolesis were CD8+ T cells, and they penetrated hepatic cells actively via the CD44/p-ERM/F-actin pathway. As a result, most CD8+ T cells engulfed by hepatic cells underwent apoptosis. In the α-GalCer-induced acute hepatitis model, emperipolesis was observed around the inflammatory foci and was inhibited by the ezrin phosphorylation inhibitor NSC668394. Similarly, activated murine CD8+ T cells penetrated primary hepatocytes via the CD44/p-ERM/F-actin pathway in vitro. CONCLUSIONS: CD8+ T cells penetrate hepatic cells actively via the CD44/p-ERM/F-actin signaling pathway and undergo apoptosis. This may be a compensatory mechanism to attenuate the overwhelming immune attack in AIH.

CTHRC1 expression in primary biliary cholangitis.

OBJECTIVES: Collagen triple helix repeat containing-1 (CTHRC1) is a highly conserved extracellular matrix glycoprotein that is overexpressed in two murine models of cholestatic liver fibrosis. Elevated CTHRC1 has been found to attenuate liver fibrosis in these murine models, thus we aimed to study the expression of CTHRC1 in patients with cholestatic liver diseases and its correlation with hepatic conditions. METHODS: Ninety patients with chronic liver disease, including 48 had primary biliary cholangitis (PBC), 18 had primary sclerosing cholangitis (PSC) and 24 had chronic hepatitis B (CHB), together with five healthy controls (HC), were recruited to this study. Participants' liver sections were analyzed using immunohistochemistry. Serum CTHRC1 levels in another cohort of 59 patients with PBC and 10 age-matched HC were detected by enzyme-linked immunosorbent assay. RESULTS: CTHRC1 protein was primarily expressed in activated hepatic stellate cells (HSC). CTHRC1 expression was significantly increased in the PBC and PSC groups, compared with the HC and CHB groups. Importantly, the hepatic fibrosis stage of the PBC group was positively correlated with hepatic CTHRC1 expression (r = 0.425, P = 0.003). Meanwhile, there were significant correlations between serum CTHRC1 levels and both the degrees of hepatic inflammation and fibrosis stage in the PBC group (r = 0.300, P = 0.022; r = 0.321, P = 0.012). CONCLUSION: CTHRC1 may play a role in hepatic fibrogenesis in PBC and that serum CTHRC1 may be a potential novel noninvasive biomarker in the assessment of liver fibrosis and inflammation.