PEDF表达降低介导IL-34刺激的滑膜MSC异常调控类风湿关节炎Tfh的机制研究

Our previous data have shown that circulating follicular helper T cell (Tfh) in rheumatoid arthritis (RA) was increased and positively correlated with disease progression，and allogenic umbilical cord mesenchymal stem cell (MSC) inhibited RA Tfh proliferation and differentiation. However, the immune modulation of MSC can be affected by body internal environment. Interleukin-34 (IL-34) is new inflammatory cytokine. Our preliminary experiment showed that serum IL-34 level was increased in RA patients. In addition, IL-34-stimulated synovial MSC showed a deficiency in inhibiting RA Tfh and decreased expression of pigment epithelium-derived factor (PEDF). Based on above, we speculated that IL-34-stimulated MSC exhibited impaired immune regulation on Tfh, which may be mediated by decreased PEDF expression. In the present study, we will explore the effect of IL-34-stimulated synovial MSC on the differentiation and proliferation of RA Tfh，and investigate the mechanism of abnormal Tfh regulation mediated by decreased PEDF on IL-34-stimulated synovial MSC. In addition，we will clarify the related signal pathway of down-regulated PEDF expression mediated by the interaction of IL-34 and IL-34 receptor on synovial MSC. The biological properties of synovial MSC including multilineage differentiation were also studied. This study will further uncover the effect and mechanism of RA internal environment on synovial MSC immune regulation and provide new evidence for MSC transplantation.

我们已经证实类风湿关节炎(RA)患者循环滤泡辅助T细胞(Tfh)比例升高且与疾病进展密切相关；而间充质干细胞(MSC)可抑制RA Tfh增殖分化。然而体内炎症环境影响MSC免疫调控作用的发挥。IL-34是新发现的炎性细胞因子。我们预实验显示，RA患者血清IL-34水平增高；且IL-34刺激的滑膜MSC抑制Tfh功能下降，其表达色素上皮细胞衍生因子(PEDF) 减少。推测IL-34刺激的滑膜MSC免疫调控功能减弱，并与下调的PEDF表达有关。本课题将研究IL-34刺激的滑膜MSC对RA Tfh分化增殖的具体作用；深入探讨PEDF表达降低介导IL-34刺激的滑膜MSC异常调控Tfh机制；阐明IL-34通过与其受体结合下调滑膜MSC表达PEDF的信号传导通路以及IL-34对滑膜MSC多向分化等功能的影响。本课题揭示RA内环境影响滑膜MSC发挥免疫调控作用的机制，为异基因MSC治疗RA提供依据。

间充质干细胞（MSC）具有自我更新和多向分化功能，有强大的免疫调节作用，能抑制T细胞、B细胞等免疫细胞的增殖与活化，用于治疗类风湿关节炎（RA）等多种自身免疫病，其免疫调节能力也受到机体多种因素的影响。在本课题中，我们发现白介素-34（IL-34）可通过激活NF-κB和P38-MAPK通路抑制RA滑膜MSC分泌色素上皮细胞衍生因子（PEDF）从而介导炎症反应；内质网应激的MSC能够进一步下调RA患者CD4+CXCR5+ICOS+ T细胞；印度刺猬因子（IHH）能够调节骨髓MSC（BMSC）的衰老而TL1A/TNFR2通路可增强BMSC的免疫调节作用。细胞因子（如IL-34、瘦素等），滑膜成纤维细胞（FLS）以及CD4+ T淋巴细胞相互作用参与RA发病，在本研究中发现：IL-34、瘦素能够促进RA-FLS迁移；IL-34可通过促进RA-FLS和THP-1细胞分泌IL-6从而上调Th17细胞比例；瘦素可通过促进IL-6分泌上调滤泡辅助性T（Tfh）细胞比例。在本项目执行中，已发表相关SCI文章16篇，国内核心期刊3篇，综述2篇。通过上述研究，为揭示RA内环境影响MSC免疫调节作用的机制以及细胞因子、CD4+ T淋巴细胞和FLS在RA发病中的相互作用提供重要理论和实验依据。