[CXCR2 participates in cerebral endothelial activation and neutrophil migration in mice with septic encephalopathy]

Objective To investigate the role of CXCR2 in the cerebral endothelial activation and migration of neutrophils into the brain in septic encephalopathy (SE) induced by lipopolysaccharide (LPS). Methods C57BL/6J mice and CXCR2-knockout mice were randomly divided into a normal control group, a wildtype mice group with LPS treatment and CXCR2-knockout mice group with LPS treatment. Mouse SE models were induced by intraperitoneal LPS injection. Naphthol AS-D chloroacetate histochemical staining of the brain section was performed to quantitate the neutrophils infiltrating into the cerebral cortex. TNF-α and CXCL1 concentrations in the brain and plasma were determined by ELISA. After the stimulation of LPS (1 μg/mL) and TNF-α (200 ng/mL), the levels of CXCR2 protein in the primary mouse brain microvascular endothelial cells isolated from the cerebral cortex were detected by Western blotting. The levels of F-actin and vascular cell adhesion molecule 1 (VCAM-1) protein in the primary mouse brain microvascular endothelial cells stimulated by CXCL1 (100 ng/mL) were detected by Western blotting. Results After intraperitoneal LPS injection, there was a significant increase in the level of TNF-α in the brain and plasma and there was also an evident increase in the level of CXCL1 in the brain of wild type mice (C57BL/6J mice). And intraperitoneal LPS injection caused increased neutrophil infiltration into the cerebral cortex in the wild type mice (C57BL/6J mice). But CXCR2-knockout mice displayed evidently reduced neutrophil infiltration into the cerebral cortex compared with the wildtype mice. In vitro LPS and TNF-α upregulated the expression of CXCR2 in the primary brain microvascular endothelial cells. CXCL1 increased remarkably the expression of endothelial F-actin and VCAM-1. Conclusion In the SE model, CXCR2 participates in the cerebral endothelial activation and neutrophil migration into the brain.