Effect of sphingosine 1-phosphate on morphological and functional responses in endothelia and venules after scalding injury

Objective: The uncontrolled increase of vascular permeability is the major obstacle in treatment of severe burns. Sphingosine 1-phosphate (S1P) has emerged as an important modulator of EC barrier function. This study was designed to explore the effect of S1P on morphological alteration in cultured endothelial cells (ECs) after burned plasma stimulation, and second to investigate the hyper-permeability response in intact vessels after scalding injury. Methods: The distribution of VE-cadherin and F-actin was observed by double staining in primary cultured human umbilical vein endothelial cells (HUVECs) with immunofluorescence and fluorescent probes; respectively. Permeability changes were measured by a fluorescence ratio technique in isolated venules from rat skin. Burned plasma was obtained from a third-degree scald covering 30% of the total body surface area. Results: The intervention with burned plasma on injured rats cultured HUVECs caused a significant disruption of intercellular adherens junction labeled by VE-cadherin staining, accompanied by the formation of F-actin stress fibers in the cells. S1P prevented or reversed these burned plasma-induced morphological alterations in cultured endothelial cells. The inhibition of S1P synthesis with N,N-dimethylsphingosine (DMS) mimicked the burned plasma-evoked redistribution of VE-cadherin and reorganization of F-actin. Venules isolated from burned rats demonstrated similar endothelial cytoskeleton changes with cultured cells under the influence of S1P or DMS. Both pre- and post-bum application of S1P attenuated increased permeability in isolated and perfused skin venules after burned plasma stimulation. Conclusion: Our results indicate that S1P plays a role in maintaining basal vascular barrier function and could be protective in burn injury by enhancing the endothelial barrier function. (C) 2009 Elsevier Ltd and ISBI. All rights reserved.