The role of microglia in the development of neurodegeneration

Microglia-mediated central nervous system (CNS) inflammation is one of the key features of various neurodegenerative diseases, including Parkinson’s and Alzheimer’s diseases. In the last few years, a number of studies have investigated the link between neurodegenerative diseases and CNS glial cells, in particular microglia. Microglial cells are the main resident immune cells and comprise approximately 10–15% of all CNS cells. Microglia at rest regulates CNS homeostasis via phagocytic activity, by removing pathogens and cell detritus. “Resting” microglia cells transform into an activated form and produce inflammatory mediators, thus protecting neurons and providing defense against invading pathogens. Excessive inflammation leads to neuronal damage and neurodegenerative diseases. Various microglial reactions at different stages of the disease can open up new directions for treatment interventions and modification of the inflammatory activity. This review focuses on the potential role of microglia and the dynamic M1/M2 phenotype changes that are critically linked to certain neurodegenerative diseases.