Mechanism of Yi Ceng Application in Alleviating Synovial Fibrosis Induced by Transforming Growth Factor-β1 in Rats with Knee Osteoarthritis Based on PI3K/AKT/HIF-1α Signal Pathway

  OBJECTIVE  To investigate the effect of Yi Ceng application on the expression of TGF-β1, α-SMA and COL1A1 in synovial fibrosis of rats with knee osteoarthritis (KOA) and the regulation of PI3K/AKT/HIF-1α signal pathway.

  METHODS  30 SPF SD rats were randomly divided into blank group, model group and Yi Ceng group. The animal model of synovial fibrosis of knee joint was established with 200 ng transforming growth factor-β1 (TGF-β1) recombinant protein, once every 2 days, lasting for 3 times. After 14 days of modeling, the synovial tissue was obtained after the external application of Yi Ceng for 28 days. HE and Masson staining were used to observe the pathological changes of synovium. The expression of p-PI3K, p-AKT, HIF-1α, TGF-β1, α-SMA and COL1A1 in synovium was detected by immunohistochemistry. Fibroblast-like synoviocytes (FLSs) were isolated from the knee joint of male SD rats and induced with 10 ng·mL^-1 TGF-β1 for 24 h to establish KOA synovial fibrosis cell model, then intervened with Yi Ceng freeze-dried powder for 24 h. PI3K, p-PI3K, AKT, p-AKT, HIF-1α, TGF-β1, α-SMA and COL1A1 protein expressions in synoviocytes were detected by Western blot. HIF-1α, TGF-β1, α-SMA and COL1A1 mRNA expressions in synoviocytes were detected by qPCR.

  RESULTS  Compared with the control group, the synovitis and synovial fibrosis of the model group were significantly aggravated (P < 0.01) in HE and Masson staining, and the expressions of p-PI3K, p-AKT, HIF-1α, TGF-β1, α-SMA and COL1A1 were increased (P < 0.01). The protein expressions of p-PI3K/PI3K, p-AKT/AKT, HIF-1α, TGF-β1, α-SMA and COL1α1 in synoviocytes were increased (P < 0.05, P < 0.01), and the mRNA expressions of HIF-1α, TGF-β1, α-SMA and COL1A1 in synoviocytes were increased (P < 0.01). Compared with the model group, synovitis and synovial fibrosis were improved, and the expression levels of p-PI3K, p-AKT, HIF-1α, TGF-β1, α-SMA and COL1A1 were decreased in the Yi Ceng group (P < 0.05, P < 0.01).The protein expressions of p-PI3K/PI3K, p-AKT/AKT, HIF-1α, TGF-β1, α-SMA and COL1A1 were decreased (P < 0.05), and mRNA levels of HIF-1α, TGF-β1, α-SMA and COL1A1 were downregulated (P < 0.05, P < 0.01).

  CONCLUSION  Yi Ceng application can effectively improve the synovial fibrosis induced by recombinant TGF-β1 in KOA rats by decreasing the expression of TGF-β1, α-SMA and COL1A1 via the PI3K/AKT/HIF-1α signal pathway.