CXCL13 Is Involved in the Lipopolysaccharide-Induced Hyperpermeability of Umbilical Vein Endothelial Cells

Sepsis is a disease that is characterized by a severe systemic inflammatory response to microbial infection and lipopolysaccharide (LPS) and is a well-known inducer of sepsis, as well as endothelial cell hyperpermeability. In the present study, we confirm the elevation of CXC chemokine ligand 13 (CXCL13) in sepsis patients. We also show that LPS exposure increases the release of CXCL13, as well as the mRNA and protein expression of CXCL13 and its receptor, CXC chemokine receptor 5 (CXCR5) in human umbilical vein endothelial cells (HUVECs) in a dose- and time-dependent manner. We also examined the effects of CXCL13 knockdown on LPS-mediated endothelial hyperpermeability and tight junction (TJ) protein expression in HUVECs. Our results show that HUVECs exposed to LPS result in a significant decrease in transendothelial electrical resistance (TER) and TJ protein (Zonula occluden-1, occludin, and claudin-4) expression, and a notable increase in fluorescein isothiocyanate (FITC)-dextran flux and p38 phosphorylation, which was partially reversed by CXCL13 knockdown. Recombinant CXCL13 treatment had a similar effect as LPS exposure, which was attenuated by a p38 inhibitor, SB203580. Moreover, the CXCL13-neutralizing antibody significantly increased the survival rate of LPS-induced sepsis mice. Collectively, our results show that CXCL13 plays a key role in LPS-induced endothelium hyperpermeability via regulating p38 signaling and suggests that therapeutically targeting CXCL13 may be beneficial for the treatment of sepsis.