The Heat Shock Protein 70 Plays a Protective Role in Sepsis by Maintenance of the Endothelial Permeability

Sepsis is a severe system inflammatory response syndrome in response to infection. The vascular endothelium cells play a key role in sepsis-induced organ dysfunction. The heat shock protein 70 (HSP70) has been reported to play an anti-inflammatory role and protect from sepsis. The present study is aimed at finding the function of HSP70 against sepsis in vascular endothelium cells. Lipopolysaccharide (LPS) and HSP70 agonist and inhibitor were used to treat HUVEC. Cell permeability was measured by transepithelial electrical resistance (TEER) assay and FITC-Dextrans. Cell junction protein levels were measured by western blot. Mice were subjected to cecal ligation and puncture (CLP) to establish a sepsis model and were observed for survival. After LPS incubation, HSP70 expression was decreased in HUVEC. LPS induced the inhibition of cell viability and the increases of IL-1 beta, IL-6, and TNF-alpha. Furthermore, cell permeability was increased and cell junction proteins (E-cadherin, occludin, and ZO-1) were downregulated after treatment with LPS. However, HSP70 could reverse these effects induced by LPS in HUVEC. In addition, LPS-induced elevated phosphorylation of p38 can be blocked by HSP70. On the other hand, we found that inhibition of HSP70 had similar effects as LPS and these effects could be alleviated by the inhibitor of p38. Subsequently, HSP70 was also found to increase survival of sepsis micein vivo. In conclusion, HSP70 plays a protective role in sepsis by maintenance of the endothelial permeability via regulating p38 signaling.