[Tujia medicine Toddalia asiatica improves synovial pannus in rats with collagen-induced arthritis through the PI3K/Akt signaling pathway].

Objective: To investigate the therapeutic mechanism of Tujia medicine Toddalia asiatica alcohol extract (TAAE) for synovial pannus formation in rats with college-induced arthritis (CIA).

Methods: Sixty male SD rats were randomized into normal control group, CIA model group, TGT group, 3 TAAE treatment groups at low, medium and high doses (n=10). Except for those in the normal control group, all the rats were subjected to CIA modeling using a secondary immunization method and treatment with saline, TGT or TAAE by gavage once daily for 35 days. The severity of arthritis was assessed using arthritis index (AI) score, and knee joint synovium pathologies were examined with HE staining. Serum levels of TNF-α, IL-6, and IL-1β were detected with ELISA; the protein expressions of PI3K, Akt, p-PI3K, p-Akt, VEGF, endostatin, HIF-1α, MMP1, MMP3, and MMP9 in knee joint synovial tissues were determined using Western blotting, and the mRNA expressions of TNF‑α, IL-6, IL-1β, VEGF, HIF-1α, PI3K, and Akt were detected with RT-PCR.

Results: Treatment of CIA rat models with TAAE and TGT significantly alleviated paw swelling, lowered AI scores, and reduced knee joint pathology, neoangiogenesis, and serum levels of inflammatory factors. TAAE treatment obviously increased endostatin protein expression, downregulated p-PI3K, p-Akt, MMP1, MMP3, MMP9, VEGF, and HIF-1α proteins, and reduced TNF‑α, IL-6, IL-1β, PI3K, Akt, VEGF, and HIF-1α mRNA levels in the synovial tissues, and these changes were comparable between high-dose TAAE group and TGT group.

Conclusion: TAAE can improve joint symptoms and inhibit synovial pannus formation in CIA rats by regulating the expressions of HIF-1α, VEGF, endostatin, MMP1, MMP3, and MMP9 via the PI3K/Akt signalling pathway.