TGF-β2 silencing to target biliary-derived liver diseases.

Abstract

TGF-β2 (TGF-β, transforming growth factor beta), the less-investigated sibling of TGF-β1, is deregulated in rodent and human liver diseases. Former data from bile duct ligated and MDR2 knockout (KO) mouse models for human cholestatic liver disease suggested an involvement of TGF-β2 in biliary-derived liver diseases. As we also found upregulated <i>TGFB2</i> in liver tissue of patients with primary sclerosing cholangitis (PSC) and primary biliary cholangitis (PBC), we now fathomed the positive prospects of targeting TGF-β2 in early stage biliary liver disease using the MDR2-KO mice. Specifically, the influence of <i>TgfB2</i> silencing on the fibrotic and inflammatory niche was analysed on molecular, cellular and tissue levels. <i>TgfB2</i>-induced expression of fibrotic genes in cholangiocytes and hepatic stellate cellswas detected. <i>TgfB2</i> expression in MDR2-KO mice was blunted using <i>TgfB2</i>-directed antisense oligonucleotides (AON). Upon AON treatment, reduced collagen deposition, hydroxyproline content and αSMA expression as well as induced <i>PparG</i> expression reflected a significant reduction of fibrogenesis without adverse effects on healthy livers. Expression analyses of fibrotic and inflammatory genes revealed AON-specific regulatory effects on <i>Ccl3</i>, <i>Ccl4</i>, <i>Ccl5</i>, <i>Mki67</i> and <i>Notch3</i> expression. Further, AON treatment of MDR2-KO mice increased tissue infiltration by F4/80-positive cells including eosinophils, whereas the number of CD45-positive inflammatory cells decreased. In line, <i>TGFB2</i> and CD45 expression correlated positively in PSC/PBC patients and localised in similar areas of the diseased liver tissue. Taken together, our data suggest a new mechanistic explanation for amelioration of fibrogenesis by TGF-β2 silencing and provide a direct rationale for TGF-β2-directed drug development.