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.

中文翻译：

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CXC趋化因子配体5（CXCL5）通过调节p38信号破坏人脑微血管内皮细胞的通透性

人脑微血管内皮细胞 (BMECs) 缺血再灌注诱导的损伤与血脑屏障的破坏有关。据报道，CXC 趋化因子配体 5 (CXCL5) 在缺血性中风中上调。然而，CXCL5 在这一病理过程中的详细功能仍不清楚。为了进一步分析 CXCL5 在缺血性中风中的功能，构建了人类 BMEC 的氧-葡萄糖剥夺模型以模拟体外缺血性中风状况。使用细胞计数试剂盒-8 (CCK-8) 测定法分析细胞增殖。利用定量实时聚合酶链反应和蛋白质印迹来确定基因表达。使用荧光标记的葡聚糖测定和跨上皮/内皮电阻 (TEER) 技术评估 BMEC 的屏障功能。结果表明，CXCL5抗体（抗CXCL5）促进了模型细胞的增殖，而降低了通透性。此外，模型细胞的 TEER 值在抗 CXCL5 存在下增强。因此，这些发现表明 CXCL5 沉默减轻了人类 BMEC 中缺血/缺氧诱导的损伤。重要的是，人类重组蛋白CXCL5（Re-CXCL5）在常氧条件下严重破坏了BMECs的功能。此外，p38 抑制剂 SB203580 显着消除了模型细胞中 CXCL5 的功能。更重要的是，在含 Re-CXCL5 的常氧条件下，在 BMEC 中也获得了类似的结果。这些结果表明CXCL5可能通过介导p38通路来调节BMECs的功能。