Effect of Heat Shock Treatment on Endothelial Cell Integrity after Histamine Challenge

Abstract

Endothelial cells and endothelial cell integrity play a central role in circulatory homeostasis. Our previous study indicated that heat shock treatment reduces protein leakage and attenuates the hypotension caused by anaphylactic shock. Also, heat shock treatment maintains cerebral vascular permeability, while the blood brain barrier is opened by high osmotic stress. In this study we investigated the potential mechanism by which heat shock protein 72 (Hsp72), the major product after heat shock, maintains cellular integrity of cultured histamine-induced human umbilical vein endothelial cells (HUVECs) upon challenge by histamine. Tight junction proteins (ZO-1 and occludin) and a cytoskeleton component (F-actin) were evaluated by an immunocytochemical study. The immunochemical density of ZO-1 and occludin was clearly decreased in the non-heated cells after histamine challenge, and associated with the proportional decline of F-actin. The adverse phenomenon was prevented in the heated cells in which Hsp72 was significantly over-expressed. It was further demonstrated that Hsp72 could be exclusively coimmunoprecipitated with ZO-1 or occludin in heated cells. In conclusion, histamine-induced conformational alteration of HUVECs is attenuated by previous heat shock treatment, and the Hsp72-mediated preservation of tight junction proteins, as well as cytoskeletal structure, could be the possible mechanism of action.