The role of osteopontin and tumor necrosis factor alpha receptor-1 in xenobiotic-induced cholangitis and biliary fibrosis in mice.

Proinflammatory and profibrotic cytokines such as osteopontin (OPN) and tumor necrosis factor-alpha receptor-1 (TNFR(1)) may be critically involved in the pathogenesis of cholangiopathies and biliary fibrosis. We therefore aimed to determine the role of genetic loss of either OPN or TNFR(1) in 3,5-diethoxycarbonyl-1,4-dihydrocollidine (DDC)-fed mice as a model of xenobiotic-induced sclerosing cholangitis with biliary-type liver fibrosis using respective knock-out mice. OPN and TNFR(1) knock-out mice were fed a 0.1% DDC-supplemented diet for 4 weeks and compared with corresponding wild-type (WT) controls. Liver morphology (H&E staining), serum markers of liver injury and cholestasis (ALT, AP, bilirubin), markers of inflammation in liver (CD11b and F4/80 immunostaining, mRNA expression of iNOS, MCP-1, IL-1beta, INF-gamma, TNF-alpha and OPN), degree of ductular reaction (immunohistochemistry with morphometric analysis and western blotting for cholangiocyte-specific marker keratin 19) and degree of liver fibrosis (Sirius-red staining, hepatic hydroxyproline content for quantification) were compared between groups. DDC feeding in OPN and TNFR(1) knock-out mice and respective WT controls resulted in comparable extent of liver injury, inflammatory response, ductular reaction and liver fibrosis. Our data indicate that genetic loss of neither OPN nor TNFR(1) significantly effects on the pathogenesis of DDC-induced sclerosing cholangitis, ductular reaction and resulting biliary fibrosis.