The changing phenotype of microglia from homeostasis to disease

Luo, Xiao-Guang; Chen, Sheng-Di

I. Introduction II. The origin of microglia III.Microlgia the dual natures of neurotoxicity and neuroprotection IV.Crosstalk between microglia and other brain cells 1. Cross talk between microglia and neurons: neurons as regulators of microglial activation 2. Cross talk between astrocytes and microglia: reciprocal influences 3. Microglia-T cell crosstalk:key determinants for the Introduction Microglia are generally considered the immune cells of the central nervous system (CNS) and account for 10% of the total glial cell population in the brain. In a normal physiological environment, they work as sentinel cells by continually screening the brain tissue; they actively participate in pathological processes by changing morphology, expressing various antigens and becoming phagocytic. During the past 20 years, thousands of papers have been published describing both the detrimental and beneficial roles of microglia in various brain disorders, from acute infection or stroke to the long and chronic process of neurodegeneration. Microglia have been firmly established as a key cellular component involved in the eventual outcome of inflammation and eventually contribute to the chronic neurodegeneration; The physiology and signaling of microglia have been comprehensively reviewed by Kettenmann's series papers [1] [2] [3] [4] [5] [6] , however, the regulation of microglial activity is a highly complex system, and the responses of microglia are tailored in a multi-factor dependent manner, and which are the focus we try to review in this paper.