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

Abstract

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.

Keywords: PI3K/Akt signaling pathway; Toddalia asiatica; inflammation; pannus; rheumatoid arthritis.

图1

大鼠足肿胀度变化情况 Fig.1 Changes in foot swelling of the rats (Mean±SD, n=10). **P<0.01 vs control group; ^# P<0.05, ^## P<0.01 vs model group.

图2

大鼠关节指数变化情况 Fig.2 Changes in joint index of the rats (Mean±SD, n=10). **P<0.01 vs control group; ^# P<0.05, ^## P<0.01 vs model group.

图3

TAAE与TGT的干预对CIA大鼠血清中TNF-α、IL-6、IL-1β含量的影响 Fig.3 Effects of TAAE and TGT on serum levels of TNF-α, IL-6 and IL-1β in CIA rats (Mean±SD, n=10). **P<0.01 vs control group; ^## P<0.01 vs model group.

图4

CIA大鼠关节组织病理学变化 Fig.4 Histopathological changes of the joints in CIA rats (HE staining, original magnification: ×100).

图5

各组大鼠滑膜组织相关蛋白表达的比较 Fig.5 Comparison of protein expressions in the synovial tissue of the rats in different groups (Mean±SD, n=6). **P<0.01 vs control group; ^# P<0.05, ^## P<0.01 vs model group.

图6

各组大鼠滑膜组织通路相关蛋白表达的比较 Fig.6 Comparison of expressions of pathway-related proteins in synovial tissue of rats in each group (Mean±SD, n=6). **P<0.01 vs control group; ^# P<0.05, ^## P<0.01 vs model group.