[Improvement effect and mechanism of Wuling San on TGF-β1-induced fibrosis, inflammation, and oxidative stress damage in HK-2 cells].

This study investigated the effect of Wuling San on transforming growth factor-β1(TGF-β1)-induced fibrosis, inflammation, and oxidative stress in human renal tubular epithelial cells(HK-2) and its mechanism of antioxidant stress injury. HK-2 cells were cultured in vitro and divided into a control group, a TGF-β1 model group, and three treatment groups receiving Wuling San-containing serum at low(2.5%), medium(5.0%), and high(10.0%) doses. TGF-β1 was used to establish the model in all groups except the control group. CCK-8 was used to analyze the effect of different concentrations of Wuling San on the activity of HK-2 cells with or without TGF-β1 stimulation. The expression of key fibrosis molecules, including actin alpha 2(Acta2), collagen type Ⅰ alpha 1 chain(Col1α1), collagen type Ⅲ alpha 1 chain(Col3α1), TIMP metallopeptidase inhibitor 1(Timp1), and fibronectin 1(Fn1), was detected using qPCR. The expression levels of inflammatory cytokines, including tumor necrosis factor-α(TNF-α), interleukin-1β(IL-1β), interleukin-6(IL-6), interleukin-8(IL-8), and interleukin-4(IL-4), were measured using ELISA kits. Glutathione peroxidase(GSH-Px), malondialdehyde(MDA), catalase(CAT), and superoxide dismutase(SOD) biochemical kits were used to analyze the effect of Wuling San on TGF-β1-induced oxidative stress injury in HK-2 cells, and the expression of nuclear factor E2-related factor 2(Nrf2), heme oxygenase 1(HO-1), and NAD(P)H quinone oxidoreductase 1(NQO1) was analyzed by qPCR and immunofluorescence. The CCK-8 results indicated that the optimal administration concentrations of Wuling San were 2.5%, 5.0%, and 10.0%. Compared with the control group, the TGF-β1 model group showed significantly increased levels of key fibrosis molecules(Acta2, Col1α1, Col3α1, Timp1, and Fn1) and inflammatory cytokines(TNF-α, IL-1β, IL-6, IL-8, and IL-4). In contrast, the Wuling San administration groups were able to dose-dependently inhibit the expression levels of key fibrosis molecules and inflammatory cytokines compared with the TGF-β1 model group. Wuling San significantly increased the activities of GSH-Px, CAT, and SOD enzymes in TGF-β1-stimulated HK-2 cells and significantly inhibited the level of MDA. Furthermore, compared with the control group, the TGF-β1 model group exhibited a significant reduction in the expression of Nrf2, HO-1, and NQO1 genes and proteins. After Wuling San intervention, the expression of Nrf2, HO-1, and NQO1 genes and proteins was significantly increased. Correlation analysis showed that antioxidant stress enzymes(GSH-Px, CAT, and SOD) and Nrf2 signaling were significantly negatively correlated with key fibrosis molecules and inflammatory cytokines in the TGF-β1-stimulated HK-2 cell model. In conclusion, Wuling San can inhibit TGF-β1-induced fibrosis in HK-2 cells by activating the Nrf2 signaling pathway, improving oxidative stress injury, and reducing inflammation.