DLPC decreases TGF-β1-induced collagen mRNA by inhibiting p38 MAPK in hepatic stellate cells

Abstract

Dilinoleoylphosphatidylcholine (DLPC), the active component of polyenylphosphatidylcholine extracted from soybeans, decreases collagen accumulation induced by TGF-β1 in cultured hepatic stellate cells (HSCs). Because DLPC exerts antioxidant effects and TGF-β1 generates oxidative stress, we evaluated whether the antifibrogenic effect of DLPC is linked to its antioxidant action. In passage 1 culture of rat HSCs, TGF-β1 induced a concentration-dependent increase in procollagen-α1(I) mRNA levels and enhanced intracellular H2O2 and superoxide anion formation and lipid peroxidation but decreased GSH levels. These changes were prevented by DLPC. Upregulation of collagen mRNA by TGF-β1 was likewise inhibited by catalase and p38 MAPK inhibitor SB-203580, suggesting involvement of H2O2 and p38 MAPK signaling in this process. TGF-β1 or addition of H2O2 to HSCs activated p38 MAPK with a rise in procollagen mRNA level; these changes were blocked by catalase and SB-203580 and likewise by DLPC. α-Smooth muscle actin abundance in HSCs was not altered by TGF-β1 treatment (with or without DLPC), indicating that downregulation of procollagen mRNA by DLPC was not due to alteration in HSC activation. These results demonstrate that DLPC prevents TGF-β1-induced increase in collagen mRNA by inhibiting generation of oxidative stress and associated H2O2-dependent p38 MAPK activation, which explains its antifibrogenic effect. DLPC, an innocuous phospholipid, may be considered for prevention and treatment of liver fibrosis.