TLR3、TLR4-Peli1轴介导的炎症微环境在甲基苯丙胺致海马神经元损伤中的作用及机制

The new-type drug abusing, mostly referred to as methamphetamine (Meth), in recent years, have increased significantly. Therefore, Meth abusing has posed serious challenges for both human health and social stability. As one of the main targets for Meth, the central nervous system is more vulnerable to Meth exposure. To date, accumulating data showed that Meth exposure contributed to neural damage from a direct way, however, the interactions between neurons and other glial cells during Meth exposure are still yet to be known. In our previous work, we found that the inflammatory micro-environment mediated by Meth through the activated microglia significantly decreased neural dendrites and spines, and down-regulated the expression of post-synapse protein. Moreover, toll like receptor 3 (TLR3), 4 (TLR4) as well as Peli1, which facilitated inflammation, was significantly up-regulated in our research. Therefore, we hypothesized that Meth-mediated microglia activation and inflammatory reaction “cross-talked” with the hippocampal neurons, and caused neural damage. To support the hypothesis, microglia and neurons were co-cultured with transwell assay, furthermore, Sigma-1R-/-,MyD88-/- ,TRIF-/- mouse, behavior research, electrophysiology and other assays were performed to elucidate the effects of Sigma-1 receptor-Toll like receptor 3,4-Peli1 axis in Meth-mediated inflammatory reaction and the potential damage of the neurons. These studies, taken together, might provide the newly insights into the early interventional strategies for Meth-mediated neural damage and the corresponding cognitive defects.

以甲基苯丙胺（Meth）为代表的新型毒品滥用已成为危害人类健康的重大公共卫生问题。神经系统一直是Meth毒性研究的热点，其中以神经元直接毒性作用研究为主，而由小胶质细胞介导的炎症微环境对神经元的影响尚未清楚。本课题组前期发现：Meth激活小胶质细胞产生的炎症微环境明显减少神经元树突、棘突数量及突触蛋白的表达；此外，Toll样受体3、4及下游Peli1泛素化酶等蛋白显著上调。因此，我们认为TLR3、4-Peli1轴介导的炎症微环境可能在Meth引起神经元损伤的过程中发挥作用。该项目拟基于神经元-小胶质细胞混合培养模型，借助Sigma-1R-/-, MyD88-/- ,TRIF-/-小鼠，通过行为学、电生理等方法，系统阐述Sigma-1R-Toll样受体-Peli1轴在Meth引起的炎性微环境及在神经元损伤中的作用。该研究可望为Meth引起神经元损伤的及早干预提供新靶点和策略。

甲基苯丙胺（Methamhetamine，Meth）作为一种人工合成的新型毒品，其滥用已成为全球严峻的公共卫生问题。神经系统是Meth的主要靶组织，可导致神经退行性，神经衰老等病理性改变，但其机制仍不清楚。该研究立足于Meth滥用引起的炎性反应，从TLRs-Peli1轴在引起炎性反应中的潜在作用出发，阐述了该信号轴在引起神经炎性及其损伤作用。结果显示，Meth可引起TLRs家族多种TLR的上调，该家族系列的上调可能是激活下游MyD88依赖性或非依赖性接头蛋白（TRIF）的重要上游事件。此外，结果进一步显示，TRIF可能在小胶质细胞炎性反应中发挥主要作用，而其下游Peli1蛋白明显上调，该蛋白的上调受TRIF调控；通过构建稳定下调Peli1的小胶质细胞系，我们发现下游炎性信号通路MAPKs(ERK1/2， p38 MAPK, JNK)及NF-κB通路的激活被显著抑制，同样其下游炎性因子如IL-1β，IL-6及TNF-α的表达明显减少，此外，peli1亦可介导细胞损伤途径RIP1的调控，表现为RIP1的表达增高，其磷酸化程度明显上调，提示小胶质细胞在Meth作用下发生死亡。此外，借助于TLR4缺陷小鼠，我们发现Meth作用后，神经元发生显著损伤，棘突减少，表现为棘突标志性蛋白drebrin的下调，突触后蛋白标志物PSD95表达的减少，而TLR4缺陷小鼠中，上述现象被明显逆转，该保护作用可能和TLR4缺陷小鼠中TRIF，Peli1表达下调相关，说明TLR4在Meth引起神经元尤其是棘突，树突的损伤过程中发挥重要作用。. 该研究通过TLR4缺陷小鼠，Peli1敲除小鼠以及Peli1稳定敲减的细胞系等实验手段，充分阐述了TLR4-TRIF-Peli1轴在引起下游炎性信号通路激活及炎性因子释放中的作用，同时亦证明了TLR4-TRIF-Peli1轴在引起神经元损伤中的作用，因而该轴可作为Meth潜在的干预靶点，在治疗Meth引起的神经毒性损伤中可能具有潜在的干预价值。