内源性大麻素(eCB)系统对ASD模型鼠小胶质细胞活化的调控作用及机制研究

Autism spectrum disorders (ASD) are a heterogeneous group of neurodevelopmental disorders with unclear causes. It has been identified that abnormal activation of microglia was linked to ASD. Our previous work has reported that lower levels of endocannabinoid (eCB) system in autistic children. The eCB system as a potential immune modulator could regulate microglia-mediated neuroinflammatory response, which implied that eCB system might act anti-inflammatory and neuroprotective effect by inhibiting M1 (neurotoxic phenotype) microglial activation and promoting M2 (neuroprotective phenotype) microglial activation. In the current study, the autistic children and BTBR mice (ASD model mice) are used as the research objects to indicate the differences in eCB system expression between autistic children and controls, between BTBR mice and controls, and to analyze the correlation between eCB system expression and cognitive and social function. Furthermore, eCB metabolizing enzyme inhibitors are administered to BTBR mice, using in vivo and vitro experiments, to detect the effect of eCB system on cognitive and social function, neuronal impairment, and M1/M2 microglia polarized process, to explore the potential mechanism that eCB system play a crucial role in the management of microglial activation, which could provide evidence for etiology of ASD and new insight attributed to targeted treatment of ASD.

孤独症谱系障碍（ASD）是一种病因不明的神经发育障碍性疾病，研究表明ASD与小胶质细胞异常活化有关。课题组前期发现ASD存在内源性大麻素（eCB）系统低表达，eCB系统可作为潜在的免疫调节剂调控小胶质细胞介导的神经炎症反应，推测是通过抑制M1型（神经毒性型）并促进M2型（神经保护型）小胶质细胞活化，起到抗炎和神经保护作用。本课题以ASD儿童及BTBR（ASD模型）鼠为研究对象，明确ASD儿童与对照儿童、ASD模型鼠与对照鼠体内eCB系统表达水平及其差异以及eCB系统表达水平与认知和社交功能的关联。此外，以BTBR鼠为研究对象，应用eCB降解酶抑制剂进行干预，从体内到体外两个水平，阐明干预后eCB系统对ASD模型鼠认知及社交功能、神经元损伤以及小胶质细胞M1/M2表型转化的影响，探讨eCB系统对小胶质细胞活化的调控作用及机制，为明确ASD的病因及发病机制提供依据，为ASD靶向治疗提供新思路。

孤独症谱系障碍（ASD）是一种病因不明的神经发育障碍性疾病，研究表明ASD与小胶质细胞异常活化有关。课题组前期发现ASD存在内源性大麻素（eCB）系统低表达，eCB系统可作为潜在的免疫调节剂调控小胶质细胞介导的神经炎症反应，推测是通过抑制M1型（神经毒性型）并促进M2型（神经保护型）小胶质细胞活化，起到抗炎和神经保护作用。本课题以ASD儿童及BTBR（近交系ASD模型鼠）鼠为研究对象，明确ASD儿童与对照儿童、ASD模型鼠与对照鼠体内eCB系统表达水平及其差异以及eCB系统表达水平与认知和社交功能的关联。此外，以两种公认的ASD模型鼠（BTBR鼠和VPA鼠）为研究对象，应用eCB降解酶（MAGL和FAAH）抑制剂（JZL184和URB597）进行干预，阐明干预后eCB系统对ASD模型鼠认知及社交功能、神经元损伤以及小胶质细胞M1/M2表型转化的影响，探讨eCB系统对小胶质细胞活化的调控作用。结果发现ASD儿童和BTBR鼠均存在eCB系统代谢异常，表现在eCB水平降低、降解酶表达升高、CB2R表达代偿性升高，且低eCB信号与ASD发病有关。BTBR鼠海马和皮质中花生四烯酸甘油（2-AG）均显著降低，对BTBR鼠进行JZL184干预，发现增强2-AG信号可以明显改善ASD核心症状，并纠正过度的神经炎症和神经元凋亡。此外，在另一种ASD模型鼠-VPA鼠中，前期发现2-AG和花生四烯酸乙醇胺（AEA）均显著降低，对VPA鼠分别进行JZL184/URB597干预，发现增强2-AG和AEA信号可以调节小胶质细胞极化，促进小胶质细胞向M2型转化，并改善VPA鼠存在的异常神经炎症和神经元凋亡。以上结果均证实了“eCB系统可促进小胶质细胞向抗炎M2型转化，发挥神经保护作用，进而改善ASD的认知及社交损伤”的假说，为明确ASD的病因及发病机制提供依据，为ASD靶向治疗提供新思路。