基于NLRP3炎性小体调控机制探讨淫羊藿苷调节小胶质细胞表型极化抑制多发性硬化免疫炎症反应的研究

Multiple sclerosis (MS) is an autoimmune and neurodegenerative disease with central white matter lesion mainly, which is kidney deficiency syndrome in traditional Chinese medicine. At present, the main treatment principle is to inhibit inflammatory demyelination, and the medications are extremely limited. Current studies have shown that the polarization of microglia, especially the disorder of anti-inflammatory M2 polarization, is closely related to the demyelination of MS. Abnormal over-activation of NLRP3 inflammatory body and its downstream Caspase-1 inflammatory cascade reaction plays an important role in promoting M1 polarization of microglia and inhibiting M2 polarization. Our previous studies have found that icariin (ICA), the main active ingredient of herbal medicine for reinforcing kidney, can improve the behavioral dysfunction of various MS-like animal models through inhibit inflammatory infiltration and promote the regeneration and repairmen of myelin sheath, especially inhibit the activation of M1 microglia. Based on the founding, this project intends to explore the function and regulatory mechanism of ICA in inhibiting the activation of NLRP3 inflammasome and its related signaling pathway, regulating immune microenvironment and interfering the polarization of microglia in vitro and in vivo; meanwhile, to clarify the detailed molecular mechanism of ICA through promoting myelin regeneration and playing neuroprotective effect, so as to provide a new target and strategy for MS treatment.

多发性硬化（MS）是一种主要累及中枢白质的自身免疫系统疾病和神经退行性疾病，属中医肾虚症；目前以抑制炎性脱髓鞘病变为主要治则，药物选择极其有限。现有研究显示，小胶质细胞的极化状态尤其是抗炎态M2型极化障碍与MS脱髓鞘密切相关。NLRP3炎症小体及其下游的Caspase-1炎症级联反应的异常过度激活，在促进小胶质细胞M1型极化、抑制M2型极化中发挥重要作用。课题组前期研究发现补肾中药淫羊藿的主要活性成分淫羊藿苷（ICA）能够改善多种拟MS动物模型的行为功能障碍，抑制炎性浸润、促进髓鞘再生修复，尤其对M1型小胶质细胞活化有明显的抑制作用。本项目在此基础上，拟在体内外深入探讨ICA抑制小胶质细胞中NLRP3炎症小体及相关信号通路激活，调节免疫微环境，干预小胶质细胞极化状态的作用及调控机制，阐明ICA通过促髓鞘再生修复和神经保护发挥治疗MS作用的精细分子机制，为MS治疗提供新的靶点和策略。

多发性硬化（MS）是一种主要累及中枢白质的自身免疫系统疾病和神经退行性疾病，属中医肾虚症；目前以抑制炎性脱髓鞘病变为主要治则，药物选择极其有限。现有研究显示，小胶质细胞的极化状态尤其是抗炎态M2型极化障碍与MS脱髓鞘密切相关。NLRP3炎症小体及其下游的Caspase-1炎症级联反应的异常过度激活，在促进小胶质细胞M1型极化、抑制M2型极化中发挥重要作用。本项目深入探讨ICA抑制小胶质细胞中NLRP3炎症小体及相关信号通路激活，调节免疫微环境，干预小胶质细胞极化状态的作用及调控机制，阐明淫羊藿苷（ICA）通过促髓鞘再生修复和神经保护发挥治疗MS作用的精细分子机制。该项目发现：（1）ICA能够改善EAE拟MS动物模型的行为功能障碍，促进白质髓鞘再生修复，减少灰质神经元丢失；（2）ICA抑制小胶质细胞异常活化；采用LPS/INF-γ诱导小胶质细胞向M1型极化，ICA干预后课促进小胶质细胞表型由M1型转化为M2型；（3）ICA可抑制EAE小鼠模型脑内及LPS/INF-γ损伤小胶质细胞内NLRP3、凋亡相关斑点样蛋白（ASC）和半胱天冬酶1（Caspase-1）蛋白表达，进而抑制炎症小体的形成；通过计算机虚拟对接技术发现ICA与NLPR3的结合力为-9.3 kcal/mol，与ASC的结合力为-7.6 kcal/mol，与Caspase-1的结合力为-6.4 kcal/mol，其中与NLRP3的结合力最强。（4）为了验证ICA与NLRP3之间的作用，建立NLRP3过表达的细胞模型，结果发现ICA能够抑制NLRP3的过表达。通过本课题研究，从MS免疫反应早期调控NLRP3炎性小体活性的角度阐明中药ICA调节小胶质细胞极化方向、促进髓鞘再生修复发挥治疗MS的作用及分子机制，为MS的治疗探索新的药物作用靶点；同时，研究结果将为MS有效治疗药物的研发提供新的研究思路，具有重要的科学意义和应用价值。