Identification of growth differentiation factor 15 as a pro-fibrotic factor in mouse liver fibrosis progression.

The aim of this study was elucidate the inhibitory role of growth differentiation factor 15 (GDF15) in liver fibrosis and its possible activation mechanism in hepatic stellate cells (HSCs) of mice. We generated a GDF15-neutralizing antibody that can inhibit TGF-β1-induced activation of the TGF-β/Smad2/3 pathway in LX-2 cells. All the mice in this study were induced by carbon tetrachloride and thioacetamide. In addition, primary HSCs from mice were isolated from fresh livers using Nycodenz density gradient separation. The severity and extent of liver fibrosis were evaluated by Sirius Red and Masson staining. The effect of GDF15 on the activation of the TGF-β pathway was detected using dual-luciferase reporter and Western blotting assays. The expression of GDF15 in cirrhotic liver tissue was higher than that in normal liver tissue. Blocking GDF15 with a neutralizing antibody resulted in a delay in primary hepatic stellate cell activation and remission of liver fibrosis induced by carbon tetrachloride or thioacetamide. Meanwhile, TGF-β pathway activation was partly inhibited by a GDF15-neutralizing antibody in primary HSCs. These results indicated that GDF15 plays an important role in regulating HSC activation and liver fibrosis progression. The inhibition of GDF15 attenuates chemical-inducible liver fibrosis and delays hepatic stellate cell activation, and this effect is probably mainly attributed to its regulatory role in TGF-β signalling.