Effects of tetrandrine on activation of rat hepatic stellate cells stimulated by TGF-β_1

Objective To investigate effects of lower concentration of tetrandrine on quiescent rat hepatic stellate cells(HSCs) activation initiated and perpetuated by transforming growth factor-β1(TGF-β1),and the involved mechanism related to TGF-β1 signaling via its receptors.Methods Primary-cultured rat HSCs(freshly isolated HSCs were cultured for 2 days,or 7 days following 1 day of secondary-culture in advance before subsequent treatment) were treated with lower concentration of tetrandrine(1.6 μmol/L) and/or TGF-β1(5 μg/L) for 3 days.The activation state of HSCs was determined by cell morphology and smooth muscle α-actin(α-SMA).TGF-β1 mRNA was analyzed with reverse transcriptional PCR,and protein of α-SMA and Smad7 were evaluated by Western blot.Results Tetrandrine 1.6 μmol/L prevented morphological transformation of HSCs from the quiescent state to the activated HSCs,and tetrandrine treatment restored the morphology of activated HSCs from myofibroblastic configuration to spider-like one,which was resembled to quiescent HSCs.Tetrandrine also inhibited TGF-β1-stimulated α-SMA and TGF-β1expression in HSCs at different stage of activation.Whether in the presence or absence of TGF-β1,Smad7 expression was up-regulated by tetrandrine in quiescent HSCs.In contrast,no significant change of Smad7 expression was observed in activated HSCs which subjected to tetrandrine treatment.Conclusion Tetrandrine at lower concentration has a significant inhibiting effect on rat HSCs activation initiated or perpetuated by TGF-β1.Tetrandrine may also reverse the phonotype of activated HSCs to quiescent HSCs.These effects of tetrandrine are associated with different mechanisms depending on the activation state of HSCs.