SRGN 放大小胶质细胞介导的神经炎症，加重缺血性脑损伤。

SRGN amplifies microglia-mediated neuroinflammation and exacerbates ischemic brain injury.

机构信息

Department of Neurology, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Nanjing University, Nanjing, 210008, China.

Department of Neurology, Nanjing Drum Tower Hospital, State Key Laboratory of Pharmaceutical Biotechnology and Institute of Translational Medicine for Brain Critical Diseases, Nanjing University, Nanjing, 210008, China.

出版信息

J Neuroinflammation. 2024 Jan 29;21(1):35. doi: 10.1186/s12974-024-03026-6.

DOI:10.1186/s12974-024-03026-6

PMID:38287411

原文链接:https://pmc.ncbi.nlm.nih.gov/articles/PMC10826034/

Abstract

BACKGROUND

Microglia is the major contributor of post-stroke neuroinflammation cascade and the crucial cellular target for the treatment of ischemic stroke. Currently, the endogenous mechanism underlying microglial activation following ischemic stroke remains elusive. Serglycin (SRGN) is a proteoglycan expressed in immune cells. Up to now, the role of SRGN on microglial activation and ischemic stroke is largely unexplored.

METHODS

Srgn knockout (KO), Cd44-KO and wild-type (WT) mice were subjected to middle cerebral artery occlusion (MCAO) to mimic ischemic stroke. Exogenous SRGN supplementation was achieved by stereotactic injection of recombinant mouse SRGN (rSRGN). Cerebral infarction was measured by 2,3,5-triphenyltetrazolium chloride (TTC) staining. Neurological functions were evaluated by the modified neurological severity score (mNSS) and grip strength. Microglial activation was detected by Iba1 immunostaining, morphological analysis and cytokines' production. Neuronal death was examined by MAP2 immunostaining and FJB staining.

RESULTS

The expression of SRGN and its receptor CD44 was significantly elevated in the ischemic mouse brains, especially in microglia. In addition, lipopolysaccharide (LPS) induced SRGN upregulation in microglia in vitro. rSRGN worsened ischemic brain injury in mice and amplified post-stroke neuroinflammation, while gene knockout of Srgn exerted reverse impacts. rSRGN promoted microglial proinflammatory activation both in vivo and in vitro, whereas Srgn-deficiency alleviated microglia-mediated inflammatory response. Moreover, the genetic deletion of Cd44 partially rescued rSRGN-induced excessed neuroinflammation and ischemic brain injury in mice. Mechanistically, SRGN boosted the activation of NF-κB signal, and increased glycolysis in microglia.

CONCLUSION

SRGN acts as a novel therapeutic target in microglia-boosted proinflammatory response following ischemic stroke.

摘要

背景

小胶质细胞是卒中后神经炎症级联反应的主要贡献者，也是缺血性卒中治疗的关键细胞靶点。目前，缺血性卒中后小胶质细胞激活的内源性机制仍不清楚。硫酸软骨素蛋白聚糖（SRGN）是一种在免疫细胞中表达的蛋白聚糖。到目前为止，SRGN 对小胶质细胞激活和缺血性卒中的作用在很大程度上尚未被探索。

方法

采用大脑中动脉闭塞（MCAO）模拟缺血性卒中，对 Srgn 敲除（KO）、Cd44-KO 和野生型（WT）小鼠进行处理。通过立体定向注射重组鼠 SRGN（rSRGN）实现外源性 SRGN 补充。采用 2,3,5-三苯基氯化四氮唑（TTC）染色测量脑梗死。通过改良神经功能缺损评分（mNSS）和握力评估神经功能。通过 Iba1 免疫染色、形态分析和细胞因子产生检测小胶质细胞激活。通过 MAP2 免疫染色和 FJB 染色检测神经元死亡。

结果

SRGN 及其受体 CD44 的表达在缺血性小鼠大脑中明显升高，特别是在小胶质细胞中。此外，脂多糖（LPS）在体外诱导小胶质细胞中 SRGN 的上调。rSRGN 加重了小鼠缺血性脑损伤并放大了卒中后神经炎症，而 Srgn 基因敲除则产生了相反的影响。rSRGN 促进了体内和体外小胶质细胞的促炎激活，而 Srgn 缺陷减轻了小胶质细胞介导的炎症反应。此外，Cd44 的基因缺失部分挽救了 rSRGN 诱导的小鼠过度神经炎症和缺血性脑损伤。机制上，SRGN 增强了小胶质细胞中 NF-κB 信号的激活，并增加了小胶质细胞中的糖酵解。