小胶质细胞及其在中枢神经系统损伤后的作用

小胶质细胞属于单核巨噬细胞系统,广泛分布于中枢神经系统(central nervous system,CNS),是神经系统中发挥免疫功能的主要细胞.其最显著的特点是在中枢神经系统发生轻微病理变化变化时即可迅速活化并行使吞噬作用.活化的小胶质细胞是主要的清道夫细胞,同时可促进组织修复和再生功能.小胶质细胞形成的免疫网络具有免疫监视和调控功能,能够杀伤入侵的微生物,清除变性的细胞碎片,分泌生长因子促进组织修复,有助于恢复组织动态平衡.小胶质细胞向脑源性巨噬细胞分化时还可分泌某些蛋白酶、细胞因子、活性氧中间体、活性氮中间体等,这些物质过多地释放在继发性脑损伤中具有重要作用.因此,干预小胶质细胞的激活过程或阻止其释放细胞毒性代谢物,可能对避免中枢神经系统疾病中神经元死亡具有治疗意义.

Microglia and their roles in response to injury of the central nervous system

Microglia are cells of the mononuclear-phagocyte lineage and ubiquitously spread in the central nervous system(CNS).Functionally,microglia are the principal immune effector cells in CNS.The most characteristic property of microglia is their swift activation in response to even minor pathological changes in the CNS and their capacity for site-directed phagocytosis.Activated microglia are mainly scavenger cells and perform various other functions in tissue repair and neural regeneration.They form a network of immune alert resident macrophages with a capacity for immune surveillance and control.Activated microglia can destroy invading micro-organisms,remove potentially deleterious debris,promote tissue repair by secreting growth factors and thus facilitate the return to tissue homeostasis.Meanwhile,the differentiation of microglia into brain macrophages is accompanied by the release of several secretory products,such as proteinases,cytokines,reactive oxygen intermediates,and reactive nitrogen intermediates.The elevated expression of such molecules is responsible for increased secondary neuronal death after injury.Interference with microglial activation or productions of cytotoxic metabolites by microglia may thus offer new therapeutic opportunities for the prevention of neuronal cell death in CNS disease.