Cinnamaldehyde (CA), as an active compound isolated from the bark of Cinnamomum cassia, has been reported to possess the anti-fungal, anti-bacterial, anti-inflammatory, anti-mutagenic, and anti-oxidant properties. However, the possible effects and underlying mechanisms of CA on rheumatoid arthritis (RA) have not been revealed yet. In the present study, we found that CA obviously improved the type II collagen-induced RA in rats, accompanied with decreasing pro-inflammatory factors, proliferation and metastasis. In addition, CA decreased the expression levels of TNF-α, IL-1β, and IL-6 in RA-FLSs. Besides, CA remarkably inhibited the proliferation, downregulated the EdU-positive cells, and promoted apoptosis of RA-FLSs by CCK-8, EdU and flow cytometry analysis. Moreover, the results of wound healing, transwell migration and invasion assays showed that CA inhibited the migration and invasion of RA-FLSs. Further, western blot experiment showed CA inhibited the activation of PI3K/AKT signaling pathway in RA-FLSs. Finally, 740Y-P, the PI3K/AKT signaling pathway activator, could reverse the effects of CA on the proliferation and metastasis in RA-FLSs. In conclusion, we confirmed that CA exhibited potential therapeutic properties against RA via suppressing proliferation and metastasis of RA-FLSs by blockage of PI3K/AKT signaling pathway. Therefore, our study provides evidence that CA may emerge as a therapeutic option for RA treatment.

肉桂醛（CA），从肉桂肉桂皮中分离的活性化合物据报道，其具有抗真菌，抗细菌，抗炎，抗诱变和抗氧化的特性。但是，CA对类风湿关节炎（RA）的可能作用和潜在机制尚未揭示。在本研究中，我们发现CA明显改善了II型胶原诱导的大鼠RA，并伴有促炎因子减少，增殖和转移。另外，CA降低了RA-FLS中TNF-α，IL-1β和IL-6的表达水平。此外，通过CCK-8，EdU和流式细胞术分析，CA显着抑制增殖，下调EdU阳性细胞，并促进RA-FLS的凋亡。此外，伤口愈合，transwell迁移和侵袭试验的结果表明，CA抑制了RA-FLS的迁移和侵袭。进一步，蛋白质印迹实验表明，CA抑制了RA-FLSs中PI3K / AKT信号通路的激活。最后，PI3K / AKT信号通路激活剂740Y-P可以逆转CA对RA-FLSs增殖和转移的影响。总之，我们证实了CA对RA具有潜在的治疗作用通过阻断PI3K / AKT信号通路抑制RA-FLSs的增殖和转移。因此，我们的研究提供证据表明CA可能会成为RA治疗的一种治疗选择。