脐带MSCs移植抑制TLR9介导B细胞活化延缓MRL/lpr狼疮鼠发病研究

Systemic lupus erythematosus(SLE) is a multisystem autoimmune disease characterized with abnormal B lymphocytes activation and autoantibody production. Toll like receptor 9（TLR9）plays a key role in B-cell activation and autoantibody production, which is involved in the pathogenesis of lupus. Umbilical cord mesenchymal stem cells (UC-MSCs) transplantation could ameliorate the disease activity in MRL/lpr lupus prone mice and SLE patients, but the mechanism and optimal time window of UC-MSCs transplantation in the treatment of lupus is not very clear. Our previous study demonstrated that UC-MSCs could significantlyinhibit the proliferation and differentiation of B cells. In this study, UC-MSCs transplantation will be conducted either before or after the onset of disease in MRL/lpr mice and we will examine the serum anti-dsDNA antibody and urine protein continuously to explore the optimal time of UC-MSCs transplantation. In addition, the effect of UC-MSCs on TLR9-induced B-cell activation will be investigated both in vivo and in vitro.We aim to provide theoretical basis for the reasonableand standardizedapplication of UC-MSC transplantation in the treatment of lupus.

系统性红斑狼疮（SLE）是以B淋巴细胞异常活化及自身抗体产生为主要特征的多系统损害的自身免疫病。Toll样受体9（TLR9）在B细胞的活化及自身抗体的产生过程中起重要作用，参与狼疮发病。脐带间充质干细胞(UC-MSCs)移植治疗MRL/lpr狼疮鼠及狼疮患者疗效显著，但移植的具体机制及最佳时间窗尚不清楚。我们之前的研究表明，UC-MSCs能够显著抑制B细胞的增殖与分化。本研究通过在MRL/lpr狼疮鼠发病前后不同时间点UC-MSCs移植，连续监测血清抗ds-DNA抗体及尿蛋白水平，探讨UC-MSCs移植的最佳时间窗，并分别在体内外探究UC-MSCs对TLR-9介导的B细胞活化的影响，从而为临床更加合理规范应用间充质干细胞移植治疗狼疮提供理论依据。

系统性红斑狼疮（SLE）是一种累及多系统的自身免疫病，部分患者使用激素及免疫抑制剂治疗效果不佳。我们前期研究发现，脐带间充质干细胞（UC-MSCs）治疗狼疮鼠及SLE患者安全有效，但最佳治疗时机尚不明确。SLE的主要病理表现为B淋巴细胞的异常活化和大量自身抗体产生，Toll样受体9（TLR9）在B细胞的活化及自身抗体的产生中起重要作用，参与狼疮发病。UC-MSCs能够显著抑制B细胞的增殖与分化。本研究通过对发病前（10周龄）及发病后（20周龄）的MRL/lpr小鼠进行UC-MSCs移植，动态（每4周）监测小鼠尿蛋白水平，发现UC-MSCs移植可显著降低狼疮鼠尿蛋白水平，且发病前移植可延缓狼疮鼠发病。于26周龄处死小鼠，发现UC-MSCs移植可显著降低狼疮鼠血清IgG及自身抗体水平；降低狼疮鼠脾脏大小及脾脏指数；减轻肾脏免疫复合物沉积和病理改变，预防组与治疗组比较无统计学差异。同时，UC-MSCs预防性移植可显著降低狼疮鼠脾脏重量、脾脏总细胞数量及过渡区T1B细胞数量；UC-MSCs预防性及治疗性移植均可显著降低T1B/FOB比例、脾脏浆母细胞数量及浆细胞数量，预防组与治疗组间无显著差异。预防组和治疗组UC-MSCs移植后B细胞TLR9表达有下降趋势；治疗组UC-MSCs移植后B细胞表达TLR7显著下降，预防组TLR7有下降趋势。本研究显示发病前予UC-MSCs移植可延缓狼疮鼠发病，UC-MSCs移植可通过抑制TLR7及TLR9介导的B细胞增殖及分化发挥治疗作用，为临床更加合理规范应用MSCs移植治疗SLE提供依据。