ABSTRACT

Chemokine (C-X-C motif) ligand 6 (CXCL6), a member of the CXC chemokine family, reportedly mediates several processes such as inflammation, immunoreaction, cell growth, and metastasis through interaction with the chemokine receptors CXCR1 and CXCR2 in humans; further, CXCR1 and CXCR2 can promote repair and regeneration of organs or tissues after ischemia–reperfusion injury (IRI). In this study, we found that HIF-1α, CXCL6, and CXCR2 expression levels were elevated in human brain microvascular endothelial cells (HBMECs) after IRI, whereas silent information regulator of transcription (Sirt) 3 expression level had reduced. HIF-1α inhibition in an IRI model potently promoted HBMEC proliferation, accompanied by increased Sirt3 and decreased CXCL6/CXCR2 expression levels. CXCL6 knockdown in the IRI model significantly decreased HBMEC permeability and promoted HBMEC proliferation, concurrent with a decrease in apoptosis; it also increased Sirt3 expression levels and decreased CXCL6/CXCR2 protein and phosphorylated AKT (p-AKT) and class O of forkhead box (FOXO) 3a (p-FOXO3a) levels. In addition, CXCL6-induced HBMEC permeability and inhibition of HBMEC proliferation were counteracted by Sirt3 overexpression, and the AKT inhibitor LY294002 counteracted the effect of CXCL6 recombinant proteins on Sirt3, p-AKT, and p-FOXO3a expressions. These results suggest that CXCL6 and Sirt3 are downstream of HIF-1α and that CXCL6 regulatesHBMEC permeability, proliferation, and apoptosis after IRI by modulating Sirt3 expression via AKT/FOXO3a activation.

摘要

据报道，趋化因子（CXC 基序）配体 6 (CXCL6) 是 CXC 趋化因子家族的成员，据报道通过与人类趋化因子受体 CXCR1 和 CXCR2 的相互作用介导炎症、免疫反应、细胞生长和转移等多种过程；此外，CXCR1和CXCR2可以促进缺血再灌注损伤（IRI）后器官或组织的修复和再生。在本研究中，我们发现 IRI 后人脑微血管内皮细胞 (HBMEC) 中 HIF-1α、CXCL6 和 CXCR2 的表达水平升高，而转录的沉默信息调节因子 (Sirt) 3 的表达水平降低。IRI 模型中的 HIF-1α 抑制有效地促进了 HBMEC 增殖，伴随着 Sirt3 的增加和 CXCL6/CXCR2 表达水平的降低。IRI 模型中 CXCL6 敲低显着降低 HBMEC 通透性并促进 HBMEC 增殖，同时减少细胞凋亡；它还增加了 Sirt3 的表达水平并降低了 CXCL6/CXCR2 蛋白和磷酸化的 AKT（p -AKT) 和 O 类叉头盒 (FOXO) 3a ( p -FOXO3a) 水平。此外，CXCL6 诱导的 HBMEC 通透性和对 HBMEC 增殖的抑制被 Sirt3 过表达抵消，AKT 抑制剂 LY294002 抵消了 CXCL6 重组蛋白对 Sirt3、p- AKT 和p- FOXO3a 表达的影响。这些结果表明 CXCL6 和 Sirt3 位于 HIF-1α 的下游，并且 CXCL6 通过通过 AKT/FOXO3a 激活调节 Sirt3 表达来调节 IRI 后 HBMEC 通透性、增殖和凋亡。