Department of Neurology, Guangzhou First People's Hospital, School of Medicine, South China University of Technology, 510180, Guangzhou, China.
Department of Neurology, Nanfang Hospital, Southern Medical University, 510515, Guangzhou, China.
Cell Death Dis. 2023 Feb 10;14(2):103. doi: 10.1038/s41419-023-05621-6.
The activation of the NOD-like receptor family pyrin domain-containing protein 3 (NLRP3) inflammasome triggers pyroptosis proinflammatory cell death in experimental autoimmune encephalomyelitis (EAE). However, the underlying mechanisms of the inflammatory processes of microglia in EAE remain unclear. Our previous studies suggested that interleukin-1 receptor-associated kinase (IRAK)-M down-regulates the toll-like receptor 4/interleukin-1 receptor signaling pathway. Here, we used IRAK-M knockout (IRAK-M) mice and their microglia to dissect the role of IRAK-M in EAE. We found that deletion of IRAK-M increased the incidence rate and exacerbated the clinical symptoms in EAE mice. We then found that IRAK-M deficiency promoted the activation of microglia, activated NLRP3 inflammasomes, and enhanced GSDMD-mediated pyroptosis in the microglia of EAE. In contrast, over-expression of IRAK-M exerted inhibitory effects on neuroinflammation, NLRP3 activation, and pyroptosis. Moreover, IRAK-M deficiency enhanced the phosphorylation of IRAK1, while IRAK-M over-expression downregulated the level of phosphorylated IRAK1. Finally, we found upregulated binding of IRAK1 and TNF receptor-associated factor 6 (TRAF6) in IRAK-M EAE mice compared to WT mice, which was blocked in AAV EAE mice. Our study reveals a complex signaling network of IRAK-M, which negatively regulates microglial NLRP3 inflammasomes and pyroptosis by inhibiting IRAK1 phosphorylation during EAE. These findings suggest a potential target for the novel therapeutic approaches of multiple sclerosis (MS)/EAE and NLRP3-related inflammatory diseases.
NOD 样受体家族 pyrin 结构域包含蛋白 3(NLRP3)炎症小体的激活触发实验性自身免疫性脑脊髓炎(EAE)中的细胞焦亡炎症性细胞死亡。然而,EAE 中小胶质细胞炎症过程的潜在机制仍不清楚。我们之前的研究表明,白细胞介素-1 受体相关激酶(IRAK)-M 下调 Toll 样受体 4/白细胞介素-1 受体信号通路。在这里,我们使用 IRAK-M 敲除(IRAK-M)小鼠及其小胶质细胞来剖析 IRAK-M 在 EAE 中的作用。我们发现,IRAK-M 的缺失增加了 EAE 小鼠的发病率并加重了其临床症状。然后,我们发现 IRAK-M 缺失促进了小胶质细胞的激活,激活了 NLRP3 炎症小体,并增强了 EAE 中小胶质细胞中 GSDMD 介导的细胞焦亡。相比之下,IRAK-M 的过表达对神经炎症、NLRP3 激活和细胞焦亡具有抑制作用。此外,IRAK-M 缺失增强了 IRAK1 的磷酸化,而 IRAK-M 过表达则下调了磷酸化 IRAK1 的水平。最后,我们发现与 WT 小鼠相比,IRAK-M EAE 小鼠中 IRAK1 和肿瘤坏死因子受体相关因子 6(TRAF6)的结合上调,而在 AAV EAE 小鼠中则被阻断。我们的研究揭示了 IRAK-M 的一个复杂信号网络,它通过抑制 IRAK1 磷酸化来负调控 EAE 中小胶质细胞的 NLRP3 炎症小体和细胞焦亡。这些发现为多发性硬化症(MS)/EAE 和 NLRP3 相关炎症性疾病的新型治疗方法提供了潜在的靶点。