The Role of Cytokines and Inflammatory Cells in Perinatal Brain Injury

Figure 2

Access pathways across the cerebrovascular endothelial cells. An illustration depicting purposed access routes of materials across the endothelial cells of the blood-brain barrier (BBB). The pathways for cellular molecular movement from the circulation across the BBB may include (a) paracellular aqueous pathway across tight junctions, (b) transcellular pathways including the lipophilic pathway, (c) transport proteins, (d) receptor-mediated transcytosis, and (e) adsorptive transcytosis. Cytokine trafficking may occur via receptor-mediated transcytosis or possibly across disrupted tight junctions in the setting of inflammation. Cytokine movement is thought to occur mainly in the blood-to-brain direction; however, in the blood-cerebrospinal fluid barrier, bulk flow movement may lead to cytokine absorbtion into blood [19]. Mononuclear cells may penetrate the BBB by a process of transcellular diapedesis, directly through the cytoplasm of the endothelial cells without tight junction disruption [29]. During proinflammatory conditions, tight junctions between endothelial cells may be disrupted allowing mononuclear cells to gain access from the blood to the brain via paracellular routes, along with cytokines [30].