Shenqi Xiezhuo Decoction ameliorates renal fibrosis in rats by inhibiting excessive autophagy via modulating the ERK1/2-mTOR signaling pathway

To investigate the mechanism of Shenqi Xiezhuo Decoction (SQXZD) for delaying progression of renal fibrosis (RF).

Network pharmacology and molecular docking were used to identify the active components of SQXZD and their targets and pathways. Forty-nine male SD rats were randomly divided into control group, sham-operated group, unilateral ureteral obstruction (UUO)-induced RF model group, losartan (4.6 mg/kg) group, and low-, medium-, high-dose SQXZD (9.7, 19.4, and 38.8 g/kg, respectively) groups. Renal tissues of the rats were collected to examine collagen distribution with Masson staining and detect expressions of E-cadherin, LC3B, p62/SQSTM1, and the ERK1/2-mTOR pathway. In TGF-β₁-induced NRK-49F and NRK-52E cells, the effects of blank rat serum, DMSO, SQXZD-medicated serum, digallic acid (DGA), SQXZD-medicated serum combined with U0126, or DGA combined with U0126 were assessed on autophagy levels and expressions of α-SMA, collagen-I, E-eadherin, LC3B, p62/SQSTM1, and the ERK1/2-mTOR pathway.

The 54 active components (including 4-O-methylpaeoniflorin and DGA) identified in SQXZD showed strong binding affinity to their targets including IGF1, KDR, and ALB. The RF rat models showed obviously increased renal expression of LC3B-Ⅱ with lowered expressions of E-cadherin, p62/SQSTM1, and p-mTOR/mTOR, and these changes were significantly ameliorated by SQXZD treatment. TGF-β₁ treatment significantly upregulated α-SMA expression in NRK-49F cells and NRK-52E cells, whose viability was effectively inhibited by SQXZD-medicated serum. The IC₅₀ of DGA was 90.15 ng/mL and 610.66 ng/mL in NRK-49F and NRK-52E cells, respectively. The TGF-β₁-induced cells showed enhanced autophagy with increased autophagosome, upregulated α-SMA, collagen-Ⅰ, LC3B-Ⅱ, and p-ERK1/2/ERK1/2 expressions, and downregulated E-cadherin, p62/SQSTM1, and p-mTOR/mTOR expressions. These changes were significantly reversed by treatment with SQXZD-medicated serum or DGA, either alone or in combination with U0126.

SQXZD inhibits fibroblast activation and epithelial-mesenchymal transition to ameliorate renal fibrosis potentially by inhibiting excessive autophagy via regulating the ERK1/2-mTOR pathway.