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CXC chemokine ligand 5 (CXCL5) disrupted the permeability of human brain microvascular endothelial cells via regulating p38 signal

The ischemia‐reperfusion‐induced damage in human brain microvascular endothelial cells (BMECs) is associated with disruption of the blood–brain barrier. CXC chemokine ligand 5 (CXCL5) is reported to be up‐regulated in ischemic stroke. However, the detailed function of CXCL5 in this pathological process remains largely unclear. To further analyze the function of CXCL5 in ischemic stroke, an oxygen–glucose deprivation model on human BMECs was constructed to mimic the ischemic stroke condition in vitro. Cell proliferation was analyzed using a cell counting kit‐8 (CCK‐8) assay. Quantitative real‐time polymerase chain reaction and western blot were utilized to determine gene expression. The barrier function of BMECs was assessed using a fluorescently labeled dextran assay and a trans‐epithelial/endothelial electrical resistance (TEER) technique. The results indicated that CXCL5 antibody (anti‐CXCL5) promoted the proliferation of model cells, whereas it reduced the permeability. Moreover, the TEER value of model cells was enhanced in the presence of anti‐CXCL5. Therefore, these findings demonstrated that CXCL5 silencing attenuated the ischemic/hypoxic‐induced injury in human BMECs. Importantly, human recombinant protein CXCL5 (Re‐CXCL5) deeply disrupted the function of BMECs in the normoxic condition. Furthermore, the p38 inhibitor SB203580 significantly abolished the function of CXCL5 in model cells. More importantly, similar results were also obtained in BMECs under normoxic conditions in the presence of Re‐CXCL5. These results indicated that CXCL5 might regulate the function of BMECs by mediating the p38 pathway. This investigation not only enhanced the understanding of the biological effect of CXCL5 in human BMECs under ischemic/hypoxic conditions but also indicated its potential value as a therapeutic target for ischemic‐induced brain disease.