The role of microglia in neurodegenerative diseases

As resident immune surveillance cells within the central nervous system (CNS), microglia exert pivotal biological functions in maintaining CNS homeostasis through dynamic modulation of their proliferative capacity, chemotactic motility, efferocytosis activity, and biphasic secretory mechanisms involving both neuromodulatory factors and pro-inflammatory mediators. These specialized macrophages not only serve as the first line of defense in innate immunity but also orchestrate the regulation of adaptive immune responses; whose functional status directly governs both the physiological integrity of neural circuits and the progression of pathological outcomes. Notably, in neurodegenerative disease models, microglial functional states exhibit pronounced heterogeneity and are tightly regulated by microenvironmental cues. Upon encountering sustained hyperactivation or functional impairment, these cells precipitate a cascade of deleterious events within the neurovascular unit. Building upon these pathophysiological mechanisms, targeted modulation of microglial polarization equilibrium has emerged as a pivotal research focus in developing innovative neuroprotective therapeutic strategies. This review systematically integrates empirical evidence derived from cutting-edge methodologies—including molecular imaging, single-cell multi-omics profiling, and conditional genetic ablation—to mechanistically dissect the dual regulatory roles of microglia in orchestrating neural homeostatic maintenance and driving pathological progression in neurological disorders.