Renal fibrosis is a final common manifestation of CKD resulting in progressive loss of kidney function. The activation of SMAD3 and STAT3 played central roles in the pathogenesis of renal fibrosis, which has been recognized as potential targets for antifibrotic therapy. As we known, the potential of natural products as the candidates for drug discovery has been well recognized. Here, we identified that pectolinarigenin (PEC), as a natural flavonoid and a reported STAT3 inhibitor, dose-dependently suppressed TGFβ/SMADs activity in HEK293 cells by luciferase reporter assay. In TGFβ1-stimulated NRK-49F fibroblast, PEC blocked the phosphorylation of SMAD3 and STAT3, and downregulated the major fibrotic gene and protein expression of TGFβ, α-SMA, COL-1, and FN. Notably, oral administration of PEC at a dose of 25 mg/kg/d for 7 days or 14 days effectively ameliorated kidney injury and tubulointerstitial fibrosis after unilateral ureteral obstruction (UUO) surgery in mice. Mechanically, PEC treatment inhibited the phosphorylated activation of SMAD3 and STAT3, which further reduced the protein expression of TGFβ, α-SMA, COL-1, and FN in the obstructed kidneys of UUO mice. In summary, our results suggested that pectolinarigenin alleviated tubulointerstitial fibrosis by inhibiting the activation of SMAD3 and STAT3 signaling.
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