BAFF/BlyS在AQP4-Ab诱导的视神经脊髓炎大鼠模型复发中的作用及相关机制研究

Neuromyelitis Optica (NMO) is a severe demyelinating disease of the central nervous system, and has high incidence among Asians. The recurrence of NMO may lead to high rate of morbidity. B Lymphocytes played an important role in the relapse of NMO, including production of AQP4-Ab and inflammatory factors, as well as T cell activation. BAFF/BLys is a key cytokine in B cell proliferation and survival. In clinical practice, we found that targeted therapy against B cells leads to significant elevation of blood BAFF, which may cause the short term activation of residual B cells and leading to disease recurrence. BAFF blocking therapy may attenuate the clinical symptoms of other autoimmune diseases, such as multiple sclerosis, systemic lupus erythematosus and rheumatoid arthritis, but has not been applied in NMO. In conclusion, we hypothesized that BAFF blocking therapy might be effective in preventing NMO recurrence. In the previous research, we established an animal model of Lewis rats through implantation of tiny catheter intrathecally for repeated administration of AQP4-Ab. This study intends to apply BAFF and BAFF blocking agent to the established animal model, and evaluate the animal behavioral performance, histopathological features and percentage of B lymphocyte subsets in the central nervous system, in order to interpret the pathogenic mechanisms of recurrent NMO and provide evidences for BAFF blocker application in NMO spectrum disorders.

视神经脊髓炎（NMO）是一种以反复复发为特点的严重的中枢神经系统脱髓鞘性疾病，亚洲人群易感，致残率高。B细胞相关的体液免疫机制在NMO复发中起到了至关重要的作用。BAFF/BLys是B细胞存活和增殖所必需的细胞因子，在临床中我们发现，针对B细胞的靶向治疗药物可引起BAFF的显著升高，可能引起短期内的残余B细胞活化，导致疾病复发。BAFF阻断药物已被证实可以缓解多发性硬化、系统性红斑狼疮、类风湿关节炎的临床症状，但在NMO中尚未应用，亦无相关的临床及实验室证据支持。我们推测BAFF阻断药物可能对控制NMO复发有效。本课题组前期已通过鞘内置管反复注射AQP4-Ab的方法建立了大鼠NMO动物模型。本研究拟将BAFF及阻断剂应用于该动物模型，通过观察动物的行为学变化、组织病理学特点及中枢神经系统B淋巴细胞亚群变化，以期为NMO复发的致病机制及BAFF阻断剂在NMO谱系疾病中的应用提供基础。

本研究通过鞘内置管及反复注入人源性NMO-IgG与补体的的方法建立了视神经脊髓炎复发的大鼠模型，并进行了密切的观察与行为学评分。通过病理切片、髓鞘染色及免疫荧光染色的方法证实了复发性视神经脊髓炎大鼠模型的病理改变，包括水通道蛋白4（AQP4）的丢失、星形胶质细胞的损伤、髓鞘脱失及炎症细胞的浸润。在评估B细胞活化因子（BAFF）鞘内注射的安全浓度后，对模型组大鼠进行BAFF的处理，发现BAFF可能加重了复发性视神经脊髓炎大鼠模型的炎症过程，应用抗BAFF单抗（Belimumab）对模型组大鼠进行治疗，可观察到行为学评分的下降以及病理改变的减轻。通过流式细胞学方法检测实验动物脊髓中B淋巴细胞亚群，结果显示BAFF可能通过调节记忆性B细胞和浆细胞比例参与动物模型的病理过程。本研究的结果为BAFF阻断药物在视神经脊髓炎谱系疾病中的应用提供了部分依据，具有良好的应用前景。项目结果被2020年第二十五次全国眼科年会录用为大会发言，项目资助待发表英文论著2篇。本项目投入经费17.0万元，支出14.2万元，合作单位内部调增材料费1.2万元，相应调减测试费及差旅费，已通过合作单位审批。剩余经费2.8万元，计划用于本研究后续支出及论文发表。