The microglial NLRP3 inflammasome is activated by amyotrophic lateral sclerosis proteins
The microglial NLRP3 inflammasome is activated by amyotrophic lateral sclerosis proteins
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DOI：
10.1002/glia.23728
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发表时间：
2020-02-01
期刊：
影响因子：
6.2
通讯作者：
Woodruff, Trent M.
中科院分区：
文献类型：
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作者：
Deora, Vandana;Lee, John D.;Woodruff, Trent M.
小胶质细胞 NLRP3 炎症小体激活正在成为神经变性过程中神经炎症的关键因素。 β-淀粉样蛋白和 α-突触核蛋白等致病蛋白聚集物会触发小胶质细胞 NLRP3 激活，从而导致 caspase-1 激活和 IL-1 β 分泌。 caspase-1 和 IL-1 beta 均有助于肌萎缩侧索硬化症 (ALS) 小鼠 SOD1 (G93A) 模型的疾病进展，表明小胶质细胞 NLRP3 的作用。然而，之前的研究表明 SOD1G93A 小鼠小胶质细胞不表达 NLRP3，并且 SOD1G93A 蛋白在小胶质细胞中独立于 NLRP3 产生 IL-1 β。在这里，我们使用 Nlrp3-GFP 基因敲入小鼠证明 SOD1G93A 小鼠的小胶质细胞表达 NLRP3。我们发现聚集和可溶性 SOD1G93A 都会激活原代小鼠小胶质细胞中的炎症小体，导致 caspase-1 和 IL-1 β 裂解、ASC 斑点形成以及以剂量和时间依赖性方式分泌 IL-1 β。重要的是，SOD1G93A 无法诱导 Nlrp3 缺陷的小胶质细胞分泌 IL-1 β，或用特异性 NLRP3 抑制剂 MCC950 预处理，证实 NLRP3 是介导 SOD1 诱导的小胶质细胞 IL-1 β 分泌的关键炎症体复合物。在 TDP-43(Q331K) ALS 小鼠模型中也观察到小胶质细胞 NLRP3 上调，并且 TDP-43 野生型和突变蛋白也可以以 NLRP3 依赖性方式激活小胶质细胞炎症小体。从机制上讲，我们确定活性氧和 ATP 的产生是 SOD1（G93A）介导的 NLRP3 激活所需的关键事件。综上所述，我们的数据表明 ALS 小胶质细胞表达 NLRP3，并且病理性 ALS 蛋白激活小胶质细胞 NLRP3 炎性体。因此，NLRP3 抑制可能是阻止小胶质细胞神经炎症和 ALS 疾病进展的潜在治疗方法。
Microglial NLRP3 inflammasome activation is emerging as a key contributor to neuroinflammation during neurodegeneration. Pathogenic protein aggregates such as beta-amyloid and a-synuclein trigger microglial NLRP3 activation, leading to caspase-1 activation and IL-1 beta secretion. Both caspase-1 and IL-1 beta contribute to disease progression in the mouse SOD1(G93A) model of amyotrophic lateral sclerosis (ALS), suggesting a role for microglial NLRP3. Prior studies, however, suggested SOD1G93A mice microglia do not express NLRP3, and SOD1G93A protein generated IL-1 beta in microglia independent to NLRP3. Here, we demonstrate using Nlrp3-GFP gene knock-in mice that microglia express NLRP3 in SOD1G93A mice. We show that both aggregated and soluble SOD1G93A activates inflammasome in primary mouse microglia leading caspase-1 and IL-1 beta cleavage, ASC speck formation, and the secretion of IL-1 beta in a dose- and time-dependent manner. Importantly, SOD1G93A was unable to induce IL-1 beta secretion from microglia deficient for Nlrp3, or pretreated with the specific NLRP3 inhibitor MCC950, confirming NLRP3 as the key inflammasome complex mediating SOD1-induced microglial IL-1 beta secretion. Microglial NLRP3 upregulation was also observed in the TDP-43(Q331K) ALS mouse model, and TDP-43 wild-type and mutant proteins could also activate microglial inflammasomes in a NLRP3-dependent manner. Mechanistically, we identified the generation of reactive oxygen species and ATP as key events required for SOD1(G93A)-mediated NLRP3 activation. Taken together, our data demonstrate that ALS microglia express NLRP3, and that pathological ALS proteins activate the microglial NLRP3 inflammasome. NLRP3 inhibition may therefore be a potential therapeutic approach to arrest microglial neuroinflammation and ALS disease progression.