New Insights into Microglia as Therapeutic Targets in Alzheimer’s Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease, accounting for 60–70% of dementia cases globally. Inflammation of the central nervous system (CNS) caused by microglia is a common characteristic of neurodegenerative illnesses such as Parkinson's disease and AD. Research has recently examined the relationship between neurodegenerative diseases and CNS microglia. Microglial cells comprise 10–15% of all CNS cells and are brain-resident myeloid cells mediating critical processes to support the CNS. Microglia have a variety of receptors that operate as molecular sensors, detecting exogenous and endogenous CNS injuries and triggering an immune response. Microglia serve as brain guardians by boosting phagocytic clearance and providing trophic support to enable tissue repair and maintain cerebral homeostasis, in addition to their traditional immune cell activity. At rest, microglia manage CNS homeostasis by phagocytic action, which removes pathogens and cell debris. Microglia cells that have been "resting" convert into active cells that create inflammatory mediators, protecting neurons and protecting against invading pathogens. Neuronal damage and neurodegenerative disorders are caused by excessive inflammation. Different microglial cells reply at different phases of the disease can lead to new therapy options and reduced inflammatory activity. This review focuses on the potential function of microglia, microglia subtypes, and M1/M2 phenotypic changes associated with neurodegenerative disorders. Microglial membrane receptors, the involvement of microglia in neuroinflammation, microglial targets in AD and the double role of microglia in AD pathogenesis are also discussed in this review.