NLRP1炎症小体在酸中毒诱导皮层神经元损伤中的作用

Acidosis is a common feature of many neuronal diseases, such as brain ischemia, epileptic seizure, and neurodegenerative disease. However, the precise mechanism of acidosis-induced neuronal injury remains unclear. Previous studies shown NLRP1 inflammasome plays an important role in acidosis-associated diseases,such as brain ischemia, spord injury and neurogenerative disease. Meanwhile, acidosis can active voltage-gated potassium channel（Kv）and large conductance calcium activated potassium channel（BK）resulting in K+ efflux and low [K+]i， which can activate NLRP1 inflammasome. These indicate acidosis can activate NLRP1 inflammasome via potassium channels in neurons, which maybe mediate acidosis induced neuronal injury. In the present study, we will investigate the effect of exetracellular acidosis on NLRP1 inflammasome in primary cultured cortical neurons by molecular biology techniques, fluorescent ion imaging technology, electrophysiology techniques and immunocytochemical techniques. Moreover, we will also examine the regulation mechanism of acidosis on NLRP1 inflammasome and clarify the role of NLRP1 inflammasome in acidosis induced neuronal injury. We hope to determine the regulation mechanism of NLRP1 inflammasome in centre nervous system and make NLRP1 inflammasome become novol therapeutic target of acidosis-associated nervous system diseases,such as brain ischemia, seizure, neurodegenerative disease and so on.

酸中毒是脑缺血、癫痫、神经退行性疾病等多种神经疾病共有的现象，但是酸中毒诱导神经元损伤的机制还未完全阐明。研究发现NLRP1炎症小体在酸中毒相关的神经疾病如脑缺血、脊髓损伤、神经退行性疾病等病理过程中扮演重要的角色，它可被细胞内钾离子浓度降低所激活，而酸中毒能激活电压门控钾通道、大电导钙激活钾通道等钾离子通道，导致钾离子外流，细胞内钾离子浓度降低，提示酸中毒可能通过钾离子通道激活NLRP1炎症小体，从而介导了神经元的损伤甚至死亡。本项目综合运用分子生物学、荧光离子成像、电生理学、免疫细胞化学等方法观察细胞外酸中毒对原代培养皮层神经元NLRP1炎症小体激活的影响，阐明酸中毒调节NLRP1炎症小体激活的机制，探讨NLRP1炎症小体在酸中毒诱导皮层神经元损伤中的作用。通过以上研究以期明确NLRP1炎症小体在神经系统激活的机制，为LRP1炎症小体成为脑缺血、神经退行性疾病等治疗靶点提供理论依据。

酸中毒是脑缺血、癫痫、神经退行性疾病等多种神经疾病共有的现象，而神经退行性疾病AD发生发展与体内糖皮质激素水平密切相关，它们导致神经元损伤的机制一直是研究的热点。NLRP1炎症小体是第一个被鉴定的炎症小体，参与了多种神经系统疾病的生理病理过程，它的调节也备受关注。本项目研究了细胞外酸中毒和糖皮质激素长期暴露对神经元NLRP1炎症小体的影响及其在神经元损伤中的作用。我们发现细胞外酸中毒PH依赖性激活皮层神经元NLRP1炎症小体，进一步机制研究发现酸敏感离子通道（acid-sensing ion channels， ASICs）和大电导钙激活钾通道（Large-conductance Ca2+and voltage-activated K+ channel， BK）共表达在皮层神经元，细胞外酸中毒激活ASICs通道，进而导致BK通道电流增加，钾离子外流，引起细胞内低钾，从而激活NLRP1炎症小体，ASIC1a特异性抑制剂PcTx1和BK通道特异性抑制剂IbTX均能阻断细胞外酸中毒对NLRP1炎症小体激活的影响，同时，抑制NLRP1炎症小体的激活能对抗酸中毒诱导的皮层神经元损伤；另外，我们的研究还发现糖皮质激素长期暴露（21天， 28天）激活小鼠皮层和海马NLRP1炎症小体，导致神经元的损伤。我们的研究丰富了NLRP1炎症小体激活机制，为其成为脑缺血、癫痫、神经退行性疾病等酸中毒相关疾病的治疗靶点提供理论依据。