Liver and Biliary Tract Physiology/Pathophysiology WNT-5A regulates TGF-beta-related activities in liver fibrosis

摘要

Beljaars L, Daliri S, Dijkhuizen C, Poelstra K, Gosens R. WNT-5A regulates TGF-beta-related activities in liver fibrosis. Am J Physiol Gastrointest Liver Physiol 312: G219-G227, 2017. First published January 5, 2017; doi:10.1152/ajpgi.00160.2016.—WNT-5A is a secreted growth factor that belongs to the noncanonical members of the Wingless-related MMTV-integration family. Previous studies pointed to a connection between WNT-5A and the fibrogenic factor TGF-beta warranting further studies into the functional role of WNT-5A in liver fibrosis. Therefore, we studied WNT-5A expressions in mouse and human fibrotic livers and examined the relation between WNT-5A and various fibrosis-associated growth factors, cytokines, and extracellular matrix proteins. WNT-5A gene and protein expressions were significantly increased in fibrotic mouse and human livers compared with healthy livers. Regression or therapeutic intervention in mice resulted in decreased hepatic WNT-5A levels paralleled by lower collagen levels. Immunohistochemical analysis showed WNT-5A staining in fibrotic septa colocalizing with desmin staining indicating WNT-5A expression in myofibroblasts. In vitro studies confirmed WNT-5 A expression in this cell type and showed that TGF-beta significantly enhanced WNT-5A expression in contrast to PDGF-BB and proinflammatory cytokines IL-1beta and TNF-alpha. Additionally, TGF-beta induces the expression of the WNT receptors FZD2 and FZD8. After silencing of WNT-5A, reduced levels of collagen type I, vimentin, and fibronectin in TGF-beta-stimulated myofibroblasts were measured compared with nonsilencing siRNA-treated controls. Interestingly, the antifibrotic cytokine IFNgamma suppressed WNT-5A in vitro and in vivo. IFNgamma-treated fibrotic mice showed significantly less WNT-5A expression compared with untreated fibrotic mice. In conclusion, WNT-5A paralleled collagen I levels in fibrotic mouse and human livers. WNT-5A expression in myofibroblasts is induced by the profibrotic factor TGF-beta and plays an important role in TGF-beta-induced regulation of fibrotic matrix proteins, whereas its expression can be reversed upon treatment, both in vitro and in vivo. NEW & NOTEWORTHY This study describes the localization and functional role of WNT-5A in human and mouse fibrotic livers. Hepatic WNT-5A expression parallels collagen type I expression. In vivo and in vitro, the myofibroblasts were identified as the key hepatic cells producing WNT-5A. WNT-5A is under control of TGF-beta and its activities are primarily profibrotic.