Hematoma clearance by reactive microglia after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of stroke with high incidence rate and mortality. The pathogenesis of ICH involves primary brain injury and secondary brain injury. Unfortunately, no approved treatment options and therapies targeting them have shown satisfactory outcomes. Microglia are resident innate immune cells with phagocytic function in the central nervous system that rapidly respond to brain injury. Recent research has indicated that reactive microglia with enhanced phagocytosis reprogrammed by the interleukin 10 (IL-10) signaling pathway are critical for endogenous hematoma clearance. In this review, we first summarize the progress of microglial activation and function after ICH, focusing on specific microglial markers, pro- and anti-inflammatory molecules, as well as phenotypic and functional changes. The available evidence supports that microglia play a dual role after ICH. Second, we summarize the results of previous studies on hematoma clearance, focusing on reactive microglia in clearing hematoma through endogenous pathways reprogrammed by IL-10 or other molecules and necessitating the prospect of further research in this field. This review will help us better understand the role of reactive microglia in hematoma clearance and identify potential therapeutic targets to facilitate translational research in this direction.