Herb medicine Inchin-ko-to (TJ-135) regulates PDGF-BB-dependent signaling pathways of hepatic stellate cells in primary culture and attenuates development of liver fibrosis induced by thioacetamide administration in rats

Background/Aims We studied the effect of Inchin-ko-to (TJ-135), a herb medicine that has been clinically used for liver cirrhosis in Japan, on liver fibrosis in a rat model and on the function of stellate cells. Methods Rat liver fibrosis was generated by thioacetamide (TAA) administration. DNA synthesis was assessed by 5-bromo-2′-deoxyuridine incorporation assay. Protein expression was analysed by western blotting. Collagen and fibronectin mRNA expression were analysed by reverse transcription-polymerase chain reaction (RT-PCR). Results TJ-135 improved liver fibrosis induced in rats by TAA administration. TJ-135 reduced collagen deposition and the expression of smooth muscle α-actin in fibrotic liver tissues and decreased the serum level of hyaluronic acid. In primary-cultured stellate cells, TJ-135 suppressed DNA synthesis and the expression of collagen α1(I), collagen III, and fibronectin mRNAs. It hampered DNA synthesis and migration of PDGF-BB-stimulated stellate cells through inhibiting phosphorylation of PDGF receptor-β and down-stream signaling pathways. Among TJ-135 components, 3-methyl-1,6,8-trihydroxyanthraquinone (emodin) derived from Rhei rhizoma was found to be the most active molecule. Conclusions TJ-135 and emodin regulate PDGF-dependent events in stellate cells and attenuate the development of liver fibrosis. Their clinical use may be beneficial for the therapy of human liver fibrosis.