Microglia amplify inflammatory activation of astrocytes in manganese neurotoxicity.
Microglia amplify inflammatory activation of astrocytes in manganese neurotoxicity.
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DOI：
10.1186/s12974-017-0871-0
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发表时间：
2017-05-05
影响因子：
9.3
通讯作者：
Tjalkens RB
中科院分区：
文献类型：
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作者：
Kirkley KS;Popichak KA;Afzali MF;Legare ME;Tjalkens RB
作为中枢神经系统中的主要免疫反应细胞，小胶质细胞不断监测微环境并对应激、感染和损伤迅速作出反应，使其成为神经炎症反应的重要调节剂。在诸如帕金森病、阿尔茨海默病、多发性硬化和人类免疫缺陷病毒诱导的痴呆的疾病中，小胶质细胞的激活先于星形胶质细胞增生和明显的神经元损失。虽然小胶质细胞增生与锰（Mn）神经毒性有关，但小胶质细胞和胶质细胞串扰在Mn诱导的神经变性中的作用知之甚少。实验利用免疫纯化的小鼠小胶质细胞和星形胶质细胞，使用无柱磁分离。锰对小胶质细胞的影响进行了研究，使用基因表达分析，锰吸收测量，蛋白质的生产，和形态学的变化。此外，基因表达分析用于确定Mn处理的小胶质细胞对Mn暴露的星形胶质细胞中的炎症反应的影响。免疫荧光和流式细胞仪分析免疫纯化的小胶质细胞和星形胶质细胞表明文化分别为97%和90%纯。Mn处理小胶质细胞导致促炎基因表达的剂量依赖性增加，转变为混合M1/M2表型，以及去分枝形态。来自Mn暴露的小胶质细胞（MCM）的条件培养基显著增强星形胶质细胞中Tnf、IL-1β、IL-6、Ccl 2和Ccl 5的mRNA表达，如在存在共培养的小胶质细胞的情况下暴露于Mn。MCM具有增加的细胞因子和趋化因子水平，包括IL-6、TNF、CCL 2和CCL 5。使用Bay 11-7082对小胶质细胞中NF-κB的药理学抑制完全阻断了小胶质细胞诱导的星形胶质细胞活化，而在原代小胶质细胞中TNF的siRNA敲低仅部分抑制了星形胶质细胞中的神经炎症反应。这些结果提供了证据表明，NF-κB信号在小胶质细胞中起着至关重要的作用，通过调节细胞因子和趋化因子，放大星形胶质细胞的活化锰中毒的炎症反应。
As the primary immune response cell in the central nervous system, microglia constantly monitor the microenvironment and respond rapidly to stress, infection, and injury, making them important modulators of neuroinflammatory responses. In diseases such as Parkinson’s disease, Alzheimer’s disease, multiple sclerosis, and human immunodeficiency virus-induced dementia, activation of microglia precedes astrogliosis and overt neuronal loss. Although microgliosis is implicated in manganese (Mn) neurotoxicity, the role of microglia and glial crosstalk in Mn-induced neurodegeneration is poorly understood. Experiments utilized immunopurified murine microglia and astrocytes using column-free magnetic separation. The effect of Mn on microglia was investigated using gene expression analysis, Mn uptake measurements, protein production, and changes in morphology. Additionally, gene expression analysis was used to determine the effect Mn-treated microglia had on inflammatory responses in Mn-exposed astrocytes. Immunofluorescence and flow cytometric analysis of immunopurified microglia and astrocytes indicated cultures were 97 and 90% pure, respectively. Mn treatment in microglia resulted in a dose-dependent increase in pro-inflammatory gene expression, transition to a mixed M1/M2 phenotype, and a de-ramified morphology. Conditioned media from Mn-exposed microglia (MCM) dramatically enhanced expression of mRNA for Tnf, Il-1β, Il-6, Ccl2, and Ccl5 in astrocytes, as did exposure to Mn in the presence of co-cultured microglia. MCM had increased levels of cytokines and chemokines including IL-6, TNF, CCL2, and CCL5. Pharmacological inhibition of NF-κB in microglia using Bay 11-7082 completely blocked microglial-induced astrocyte activation, whereas siRNA knockdown of Tnf in primary microglia only partially inhibited neuroinflammatory responses in astrocytes. These results provide evidence that NF-κB signaling in microglia plays an essential role in inflammatory responses in Mn toxicity by regulating cytokines and chemokines that amplify the activation of astrocytes.