Immune Cells After Ischemic Stroke Onset: Roles, Migration, and Target Intervention

Ischemic stroke is one of the leading health issues and the major cause of permanent disability in adults worldwide. Energy depletion and hypoxia occurring after ischemic stroke result in cell death, which activates resident glia cells and promotes the peripheral immune cells breaching into brain performing various functions even contradictory effects. The infiltration of immune cells may mediate neuron apoptosis and escalate ischemic damage, while it enhances neuron repair, differentiation, and neuroregeneration. The central nervous system (CNS) is immune-privileged site as it is separated from the peripheral immune system by the blood-brain barrier (BBB). Pathologically, the diapedesis of peripheral immune cells to CNS is controlled by BBB and regulated by immune cells/endothelial interactions. As immune responses play a key role in modulating the progression of ischemic injury development, understanding the characteristics and the contribution on regulating inflammatory responses of glia cells and peripheral immune cells may provide novel approaches for potential therapies. This review summarizes the multistep process of periphery immune cell extravasation into brain parenchyma during immunosurveillance and chronic inflammation after ischemic stroke onset. Furthermore, the review highlights promising target intervention, which may promote the development of future therapeutics for ischemic stroke.