Department of Critical Care Medicine, Jing'an District Central Hospital of Shanghai, Fudan University, Shanghai, People's Republic of China.
Eur J Neurosci. 2024 Jul;60(1):3629-3642. doi: 10.1111/ejn.16363. Epub 2024 May 2.
Microglia are endogenous immune cells in the brain, and their pyroptosis and phenotype dichotomy are proved to play roles in neurodegenerative diseases. We investigated whether and how hypoxia affected pyroptosis and phenotype polarization in mouse microglia. Primary mouse microglia and BV2 microglia were exposed to hypoxia. Pyroptosis and M1/M2 phenotype were assessed by measuring gasdermin D truncation and M1/M2 surface marker expression. Mechanisms including purinergic ionotropic receptor (P2XR), peroxisome proliferator-activated receptor coactivator-1α (PGC-1α) and NOD-like receptor protein 3 (NLRP3) inflammasome were investigated. We reported hypoxia (90% N, 5% O and 5% CO) induced pyroptosis and promoted M1 phenotype polarization in primary mouse microglia and BV2 microglia, and the effect appeared after 6 h exposure. Although hypoxia (90% N, 5% O and 5% CO, 6 h) had no effect on P2X1R and P2X7R expression, it increased P2X4R expression and decreased PGC-1α expression. Interestingly, blockade of P2X4R or P2X7R abolished hypoxia-modulated PGC-1α expression, pyroptosis and M1 polarization. PGC-1α overexpression or overactivation alleviated hypoxia-induced pyroptosis and M1 polarization, while PGC-1α knockdown or deactivation promoted pyroptosis and M1 polarization under normoxic situation. Further, hypoxia induced NLRP3 expression and activated caspase-1 and induced the phosphorylation of NF-κB and reduced the phosphorylation of STAT3/6. NLRP3 inhibitor and caspase-1 inhibitor abolished hypoxia-induced pyroptosis, while NF-κB inhibitor and STAT phosphorylation inducer ameliorated hypoxia-induced M1 polarization. In addition, NF-κB activator and STAT3/6 inhibitor caused microglia M1 polarization under normoxic situation. We concluded in cultured mouse microglia, hypoxia may induce pyroptosis via P2XR/PGC-1α/NLRP3/caspase-1 pathway and trigger M1 polarization through P2XR/PGC-1α/NF-κB/STAT3/6 pathway.
小胶质细胞是大脑中的内源性免疫细胞，其细胞焦亡和表型二分法被证明在神经退行性疾病中发挥作用。我们研究了缺氧是否以及如何影响小鼠小胶质细胞的细胞焦亡和表型极化。原代小鼠小胶质细胞和 BV2 小胶质细胞暴露于缺氧环境中。通过测量天冬氨酸半胱氨酸蛋白酶 1（caspase-1）的剪切片段和 M1/M2 表面标志物的表达来评估细胞焦亡和 M1/M2 表型极化。研究了包括嘌呤能离子型受体（P2XR）、过氧化物酶体增殖物激活受体共激活因子 1α（PGC-1α）和 NOD 样受体蛋白 3（NLRP3）炎性小体在内的机制。我们报道了低氧（90%N、5%O 和 5%CO）诱导原代小鼠小胶质细胞和 BV2 小胶质细胞发生细胞焦亡，并促进 M1 表型极化，这种效应在暴露 6 小时后出现。尽管低氧（90%N、5%O 和 5%CO，6 小时）对 P2X1R 和 P2X7R 的表达没有影响，但它增加了 P2X4R 的表达，降低了 PGC-1α 的表达。有趣的是，阻断 P2X4R 或 P2X7R 消除了低氧调节的 PGC-1α 表达、细胞焦亡和 M1 极化。PGC-1α 过表达或过度激活减轻了低氧诱导的细胞焦亡和 M1 极化，而 PGC-1α 敲低或失活促进了常氧条件下的细胞焦亡和 M1 极化。此外，低氧诱导了 NLRP3 的表达，并激活了半胱氨酸天冬氨酸蛋白酶 1，诱导了核因子-κB 的磷酸化和 STAT3/6 的磷酸化减少。NLRP3 抑制剂和半胱氨酸天冬氨酸蛋白酶 1 抑制剂消除了低氧诱导的细胞焦亡，而核因子-κB 抑制剂和 STAT 磷酸化诱导剂改善了低氧诱导的 M1 极化。此外，NF-κB 激活剂和 STAT3/6 抑制剂在常氧条件下引起小胶质细胞 M1 极化。我们得出结论，在培养的小鼠小胶质细胞中，低氧可能通过 P2XR/PGC-1α/NLRP3/caspase-1 途径诱导细胞焦亡，并通过 P2XR/PGC-1α/NF-κB/STAT3/6 途径引发 M1 极化。
