Abstract
Objective: To investigate the role of piperine on the transformation of endothelial cells into fibroblasts. Methods: Cultured human umbilical vein endothelial cells (HUVECs, 4-6 passage) were used for the main experiments. The transformation models of endothelial cells into fibroblasts were induced by transforming growth factor β (TGF-β) stimulation. HUVECs were divided into 6 groups: control group, TGF-β group and 4 groups treated with various concentrations of piperine (1, 5, 10, 20 μmol/L). CKK-8 was used to detect cell proliferation. The CD31/α-smooth muscle actin (α-SMA) expression level was detected by fluorescent staining. The vascular endothelial cadherin (VE-cadherin)/vimentin expression was detected by immunofluorescence staining. RT-PCR was used detect the mRNA expressions of transformation markers. Western blot was used to detect the protein expression of snail and twist. Results: TGF-β increased HUVECs proliferation (P<0.05), which could be significantly inhibited by 10 and 20 μmol/L of piperine, but not by 1 and 5 μmol/L of piperine. Immunofluorescence results demonstrated that TGF-β increased HUVECs transformation to fibroblasts as shown by downregulated expression of endothelial markers CD31, VE-cadherin, and upregulated expression of α-SMA and vimentin, again, these effects could be attenuated by 10 and 20 μmol/L piperine. The expression levels of collagen type Ⅰ and type Ⅲ were significantly higher in TGF-β group than in control group (P<0.05), significantly lower in TGF-β+10 μmol/L piperine group and TGF-β+20 μmol/L piperine group than in TGF-β group (P<0.05).In addition, RT-PCR results showed that TGF-β increased mRNA expression of transformation markers (snail1, snail2, twist1, twist2), while 10 and 20 μmol/L of piperine could significantly downregulated the mRNA expressions of these markers. The protein expression levels of snail and twist were significantly higher in TGF-β group than in control group (both P<0.05), which was significantly lower in TGF-β+20 μmol/L piperine group than in TGF-β group (both P<0.05). Conclusions: Piperine can inhibit the transformation of endothelial cells into fibroblasts. This effect might be viewed as one of the potential mechanisms of reduced myocardial fibrosis post piperine treatment.
