A new 3-arylbenzofuran derivative EIE-2 reestablishes Tregdependent tolerance in rheumatoid arthritis by targeting on Syk induced mTOR and PKCθ imbalance

Ping Li^1,2Xin Yin²Xinzhu Wen²Xuyu Li²Yuqing Wang²Hongyan Zhan²Hanqing Che²Chunsuo Yao²Qi Hou²Ziqian Zhang^2*Ruifang Zheng^3*Mingbao Lin^2*

• ¹Peking University Sixth Hospital, Beijing, Beijing Municipality, China
• ²Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union Medical College, Beijing, China
• ³Xinjiang Institute of Materia Medica, Ürümqi, Xinjiang Uyghur Region, China

Dysfunctional self-tolerance is thought to play a crucial role in the onset of rheumatoid arthritis (RA) pathogenesis. Poorly functioning regulatory T cells (Tregs) lead to extreme situations where selftolerance is robustly disrupted. However, there are many uncertainties regarding its immunosuppressive pathways, especially concerning therapeutic drugs that are still in their infancy. Therefore, deciphering potential targets and developing novel drugs to ameliorate functional Tregs deficiency appears to be an efficient therapeutic approach for controlling RA. In this study, the presented results showed that EIE-2, a novel 3-arylbenzofuran derivative, significantly ameliorated arthritic symptoms and pathological damage in rats with collagen-induced arthritis (CIA) by reducing pro-inflammatory cytokines and increasing anti-inflammatory factors in synovium and serum, which exhibiting similar ameliorative effects in carrageenan-induced pedal edema model mice. Additionally, EIE-2 potently inhibited the inflammatory response of human synoviocyte SW982 cells, primary isolated lymphocytes and CD4+ Jurkat cells. The potential therapeutic effect of EIE-2 was accompanied by up-regulation of Tregs in the active phase and down-regulation in the inactive phase of RA. At the molecular level, EIE-2 regulated the PKCθ/mTOR ratio by targeting Syk, thereby restoring homeostasis in Tregs. In conclusion, this study suggested that EIE-2 is a potential therapeutic candidate for RA. The underlying mechanism may involve its targeting on Syk to upregulate the PKCθ/mTOR ratio during the active phase of RA and downregulate the PKCθ/mTOR ratio during the inactive phase of RA, ultimately promoting Treg-dependent tolerance restoration.