PTN调控小胶质细胞功能异质性对多发性硬化脑白质早期损害的修复机制

If patients with multiple sclerosis (MS) do not receive timely treatment, the nerve fibers in "normal-appearing white matter " (NAWM) region, which is one of the key basic pathological changes for MS relapse, maybe receive irreversible damage. We found that the fractional anisotropy (FA) value was lowered along with the longer clinical course and more frequent relapse by using diffusion tensor imaging scanning (DTI) in both patients with MS and mice with experimental autoimmune encephalomyelitis（EAE）. We also found the level of pleiotrophin (PTN) increased in peripheral circulation of mice with EAE, and PTN regulated microglia functional heterogeneity by up-regulating ERK1/2. Therefore, we speculate that PTN protects for mild white matter damage of "NAWM" by modulating microglia functional heterogeneity in multiple sclerosis. In vivo, we investigate the relationship between FA value and microglia functional heterogeneity, and finally provide a basis for clinically evaluating and repairing white matter damage in "NAWM". In vitro, we use the relevant inhibitors or SiRNA in different function heterogeneous microglia to discuss the possible signal pathway for white matter damage and repair in "NAWM", and ultimately provide experimental evidence for preventing and controlling relapse of MS.

多发性硬化（MS）患者“貌似正常白质”（NAWM）神经纤维病变如不加以干预，则可发展为不可逆性损伤，是MS再发的关键病理基础。我们前期用弥散张量成像（DTI）技术检测发现，MS患者及MS小鼠EAE模型“NAWM”区域各向异性（FA）值降低且随病情进展、发作频繁而更明显；同时，EAE模型循环血中多效生长因子（PTN）含量明显升高，PTN上调ERK1/2表达并诱导小胶质细胞功能异质性变化。因此我们假设PTN通过激活MAPK信号通路调控小胶质细胞功能异质性而参与“NAWM”神经纤维损害的修复。本课题将采用MS小鼠EAE模型，根据病程长短在PTN给药前后动态观察FA值变化与小胶质细胞功能异质性的相关性，为临床DTI评价“NAWM”脑白质修复提供依据。进而在体外培养的不同功能异质性的小胶质细胞上，应用抑制剂或SiRNA，探讨PTN调控小胶质细胞功能异质性的信号通路，为临床预防MS再发提供实验依据。

多发性硬化(MS)是一种慢性、渐进性、炎症性中枢神经退行性疾病，主要表现为局灶性白质病变(WM)和轴突损失。减少或消除神经功能障碍的复发和进展是目前的治疗难点。在MS发病早期，作为先天免疫细胞，活化的小胶质细胞群迁移到病变前病变——貌似正常的白质 (NAWM)在病灶的早期形成。NAWM区域神经纤维病变如不加以干预，则可发展为不可逆性损伤，是MS再发的关键病理基础, 同时也是MS疾病进展可逆可控的第一个关键步骤。我们用弥散张量成像（DTI）技术检测发现，MS患者及MS小鼠EAE模型“NAWM”区域各向异性（FA）值降低且随病情进展、发作频繁而更明显。本课题首先采用MS小鼠EAE模型，根据病程长短（在4个时间点：7天、11天、15天、19天）在PTN给药前后发现FA值变化与小胶质细胞功能异质性具有相关性，即FA值越高则M2型小胶质细胞比例越高。且FA值的变化与PTN表达亦具有相关性。而后给予PTN，发现FA值明显升高、M2型小胶质细胞比例变化明显，为临床DTI定量评价MS患者脑白质损害和修复提供病理生理学依据。再后，在体外模型中，分别采用外源性给予，干扰及过表达PTN干预小胶质细胞，观察小胶质细胞功能异质性变化情况，证实PTN参与调控小胶质细胞功能异质性变化可减轻白质损害。最后，应用MAPK相应抑制剂或干扰质粒证实PTN可通过ERK1/2途径调节小胶质细胞功能异质性变化,为临床预防MS再发提供实验依据。