The aqueous extract of Lycopus lucidus Turcz ameliorates streptozotocin-induced diabetic renal damage via inhibiting TGF-β1 signaling pathway

Abstract Purpose Renal fibrosis characterized by accumulation of extracellular matrix protein results in chronic renal diseases including diabetic nephropathy. Transforming growth factor β1 (TGF-β1) signaling pathway plays a key role in mediating renal fibrosis. Hence, agents that antagonize TGF-β signaling could be candidate for kidney disease therapy. Methods We established renal fibrosis model both in vitro with fibroblast cells treated with rhTGF-β1 and streptozocin(STZ)-induced diabetic nephropathy rats model in vivo and evaluated the effect of the aqueous extract of Lycopus lucidus Turcz , the blood-circulation-promoting Chinese herb, on diabetic nephropathy and investigated the mechanism of action. Results We found that Lycopus suppressed rhTGF-β1-induced Smad2 and ERK1/2 activation, down-regulated the expression of TGF-βRI, TGF-βRII, Smad4 and Smad7 in SV40 MES13 cells without inhibiting cell viability. In vivo , lycopus inhibited Smad2 phosphorylation, reduced mRNA level of TGF-β1, ameliorated expansion of the mesangial area in glomerular tissue and reduced the levels of Scr and BUN of serum and total-SOD (superoxide dismutase) activity in STZ-induced diabetic rats. Conclusion Lycopus is a novel inhibitor of renal fibrosis by blocking TGF-β signaling pathway and possess a protective effect on renal damage of STZ-induced diabetic nephropathy in rats.