Acteoside inhibits inflammatory response via JAK/STAT signaling pathway in osteoarthritic rats.

Background: Osteoarthritis (OA) is a common degenerative disease of synovial joints caused by inflammation. Acteoside (ACT), a major component and lipase inhibitor from the Chinese tea Ligustrum purpurascens kudingcha, has been reported to regulate the inflammation and immune response. The study aims to investigate the effects of ACT on inflammatory responses and joint protection in OA rats.

Methods: Cell proliferation was examined by MTT and colony formation assay. Apoptosis was analyzed using flow cytometry with Annexin V/PI staining. ELISA was employed to examine the concentration of inflammatory cytokines. OA rat model was established by surgery stimulation.

Results: ACT treatment significantly inhibited the upregulation of inflammatory cytokines induced by IL-1β in primary chondrocytes, including IL-6, IL-12, TNF-α and IFN-γ. ACT stimulation also enhanced the cell proliferation, while inhibited cell apoptosis in IL-1β-treated chondrocytes. Consistently, ACT treatment led to downregulation of cleaved-caspase-3 and apoptosis regulator Bax, and upregulation of Bcl-2. Furthermore, ACT treatment inhibited IL-1β-induced activation of JAK/STAT pathway. The results were confirmed in surgery-induced OA rat model. Moreover, ACT treatment significantly inhibited synovial inflammation and articular chondrocyte apoptosis in OA rats.

Conclusion: Our findings indicate that ACT has the potential therapeutic effect on OA through inhibiting the inflammatory responses via inactivating JAK/STAT signaling pathway.