Inhibitory Effect of Resveratrol on LPS-induced Glomerular Mesangial Cells Proliferation and TGF-β1 Expression via Sphingosine Kinase 1 Pathway.

Abstract

To elucidate the renoprotective effect of resveratrol (RSV) on sphingosine kinase 1 (SphK1) signaling pathway and expression of its downstream molecules including activator protein 1 (AP-1) and transformation growth factor-β1 (TGF-β1) in lipopolysaccharide (LPS)-induced glomerular mesangial cells (GMCs). The rat GMCs line (HBZY-1) were cultured and randomly divided into 5 groups, including control, LPS (100 ng/mL), and 5, 10, 20 µmol/L RSV-treated groups. In addition, SphK1 inhibitor (SK-II) was used as positive control. GMCs were pretreated with RSV for 2 h and treated with LPS for another 24 h. GMCs proliferation was determined by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide (MTT) assay. The proteins expression of SphK1, p-c-Jun and TGF-β1 in GMCs were detected by Western blot, and DNA-binding activity of AP-1 was performed by electrophoretic mobility shift assay (EMSA). The binding activity between RSV and SphK1 protein was detected by AutoDock Vina and visualized by Discovery Studio 2016. LPS could obviously stimulate GMCs proliferation, elevate SphK1, p-c-Jun and TGF-β1 expression levels and increase the DNA-binding activity of AP-1 (P<0.05 or P<0.01), whereas these effects were significantly blocked by RSV pretreatment. It was also suggested that the effect of RSV was similar to SK-II (P>0.05). Moreover, RSV exhibited good binding affinity towards SphK1, with docking scores of -8.1 kcal/moL and formed hydrogen bonds with ASP-178 and LEU-268 in SphK1. RSV inhibited LPS-induced GMCs proliferation and TGF-β1 expression, which may be independent of its hypoglycemic effect on preventing the development of mesangial cell fibrosis and closely related to the direct inhibition of SphK1 pathway.