Leukocyte-endothelial interactions and brain capillary function in neurological diseases.

Enhanced leukocyte-endothelial interactions are a hallmark pathological feature in brain disease. Preclinical studies have demonstrated increased leukocyte adhesion at the capillary level as a major contributor to cerebral blood flow (CBF) reductions across diverse neurological disorders, including Alzheimer's disease, ischemic stroke, and epilepsy. Remarkably, even modest levels of capillary obstruction (2%-5%) lead to disproportionate reductions in cerebral perfusion at the network level. Beyond acute perfusion deficits, chronic leukocyte obstruction contributes to long-term consequences such as structural capillary remodeling and altered blood-brain barrier function. This review synthesizes preclinical and clinical evidence across various neurological conditions to establish mechanistic links between leukocyte-driven neuroinflammatory pathology and cerebrovascular dysfunction at the capillary level. We integrate evidence on the structural and molecular basis of leukocyte adhesion, the multiscale impacts of increased leukocyte recruitment on capillary dysfunction, downstream inflammatory cascades, and neurological disease pathology. We address translational implications for therapeutic intervention arising from these mechanistic links.