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Aim <p>Hypoxic-ischemic encephalopathy is a major cause of neonatal disability and mortality. Its core pathology involves extensive neuronal apoptosis and persistent inflammatory responses. Microglia play a crucial role in maintaining brain homeostasis and promoting injury repair by recognizing and clearing apoptotic neurons. However, the regulatory mechanisms underlying this process remain unclear.</p> Method <p>This study employed a co-culture model of apoptotic neurons, phagocytic function assays, cytokine analysis, transcriptome sequencing, Gas6 gene knockout and rescue experiments, combined with a mouse model of hypoxic-ischemic brain injury, to elucidate the role of microglia in the phagocytic process and the regulatory function of Gas6.</p> Result <p>Injured neurons induced an early phase of pro-inflammatory activation and enhanced phagocytic capacity in microglia, followed by a shift towards an anti-inflammatory function. Transcriptome analysis suggested that co-culture with injured neurons activated pathways such as PI3K-AKT and NF-κB in microglia, concomitant with a significant upregulation of Gas6. Furthermore, we found that Gas6 deficiency significantly reduced the phosphorylation level of TAM receptors, leading to impaired downstream PI3K/AKT activation and a marked decrease in Rac1-GTP, thereby suppressing cytoskeletal rearrangement and phagocytic function. In parallel, Gas6-deficient microglia exhibited a sustained pro-inflammatory response, with both their efferocytic capacity and ability to regulate inflammation being significantly compromised. In vivo experiments showed that Gas6-KO mice displayed more severe neurological deficits, increased neuronal apoptosis, and stronger inflammatory responses after HIE. Supplementation with exogenous Gas6 elevated TAM receptor phosphorylation and the PI3K/AKT–Rac1 signaling pathway, partially restoring the phagocytic capacity of microglia.</p> Conclusion <p>This study demonstrates the important role of the Gas6–TAM–PI3K/AKT–Rac1 signaling axis in modulating microglial efferocytic function and inflammatory state transition. It provides a potential therapeutic strategy for improving HIE prognosis by targeting the regulation of microglial phagocytosis.</p>

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Gas6 restores microglial efferocytosis and limits neuroinflammation in neonatal hypoxic-ischemic encephalopathy by activating MerTK and the PI3K–Rac1 pathway

  • 期刊论文

  • 出版模式：

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  • 发表日期：

    2026年5月2日

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  • Yu Liu,
  • Ayipaxiaguli Kasimu,
  • Yuting Song,
  • Jinke Liu,
  • Chenqin Si,
  • Qiuyi Chen,
  • Yiyun Zhang,
  • Lijian Xie,
  • Danmei Chen,
  • Bing Li

摘要

Aim

Hypoxic-ischemic encephalopathy is a major cause of neonatal disability and mortality. Its core pathology involves extensive neuronal apoptosis and persistent inflammatory responses. Microglia play a crucial role in maintaining brain homeostasis and promoting injury repair by recognizing and clearing apoptotic neurons. However, the regulatory mechanisms underlying this process remain unclear.

Method

This study employed a co-culture model of apoptotic neurons, phagocytic function assays, cytokine analysis, transcriptome sequencing, Gas6 gene knockout and rescue experiments, combined with a mouse model of hypoxic-ischemic brain injury, to elucidate the role of microglia in the phagocytic process and the regulatory function of Gas6.

Result

Injured neurons induced an early phase of pro-inflammatory activation and enhanced phagocytic capacity in microglia, followed by a shift towards an anti-inflammatory function. Transcriptome analysis suggested that co-culture with injured neurons activated pathways such as PI3K-AKT and NF-κB in microglia, concomitant with a significant upregulation of Gas6. Furthermore, we found that Gas6 deficiency significantly reduced the phosphorylation level of TAM receptors, leading to impaired downstream PI3K/AKT activation and a marked decrease in Rac1-GTP, thereby suppressing cytoskeletal rearrangement and phagocytic function. In parallel, Gas6-deficient microglia exhibited a sustained pro-inflammatory response, with both their efferocytic capacity and ability to regulate inflammation being significantly compromised. In vivo experiments showed that Gas6-KO mice displayed more severe neurological deficits, increased neuronal apoptosis, and stronger inflammatory responses after HIE. Supplementation with exogenous Gas6 elevated TAM receptor phosphorylation and the PI3K/AKT–Rac1 signaling pathway, partially restoring the phagocytic capacity of microglia.

Conclusion

This study demonstrates the important role of the Gas6–TAM–PI3K/AKT–Rac1 signaling axis in modulating microglial efferocytic function and inflammatory state transition. It provides a potential therapeutic strategy for improving HIE prognosis by targeting the regulation of microglial phagocytosis.