Perivascular macrophages in the central nervous system: insights into their roles in health and disease.

Perivascular macrophages (PVMs) are a specialized subset of macrophages situated near blood vessels in the brain. Their strategic positioning around these vessels enables them to perform key functions in immune surveillance and response to inflammation and injury. These cells are crucial for modulating the immune response within the brain, contributing to normal central nervous system (CNS) processes. In pathological conditions, the role of PVMs becomes more complex. Depending on the specific disease or injury, they may contribute to inflammation, blood-brain barrier (BBB) dysfunction, and the clearance of abnormal materials. PVMs are implicated in degenerative diseases, cerebrovascular impairment, and microhemorrhages associated with amyloid-β immunotherapy. Despite their important roles in the CNS, research on PVMs remains limited, and the mechanisms underlying their involvement in both physiological and pathological processes within the brain are not yet fully elucidated. Therefore, this review will focus on the current advancements in PVM research, including their origin, classification, roles in neuroinflammation and neuroprotection, and their potential roles as therapeutic targets for neurodegenerative diseases.