Abstract 453: Hydrogen Sulfide Increases Endothelial Permeability through Sulfane Sulfur Modification of Occludin

Abstract

Objective: Hydrogen sulfide (H2S) is an endogenous signaling molecule which exists in three biological pools, namely free H2S, sulfane sulfur and acid labile sulfur. H2S also regulates protein function by protein sulfuration. Fine tuning endothelial permeability is crucial for vascular functions. Therefore, we sought to determine how sulfane sulfur and sulfuration of cell junction proteins alters endothelial permeability. Methods: Endothelial permeability was evaluated by albumin leakage or transendothelial electrical resistance (TEER) in transwell inserts. Exogenous H2S was studied by treating human umbilical vein endothelial cells (HUVECs) with H2S donors including sodium sulfide (Na2S), diallyl trisulfide (DATS). To investigate the effect of endogenous H2S, endothelial cells were isolated from aorta (MAECs) of wild type and CSE knockout mice. Biological pools of H2S were measured using monobromobimane followed by detection of sulfide-dibimane with reverse phase HPLC. Protein sulfhydration is determined by 2-methylsulfonyl benzothiazole (MSBT)/cyanoacetate tag-switch assay. Results: DATS treatment elevated sulfane sulfur and induced rapid albumin leakage through HUVEC monolayer. Comparatively, Na2S increased permeability only at later time points and to a lesser extent. Total sulfide and sulfane sulfur were reduced in CSE deficient MAECs. Moreover, MAECs lacking CSE showed enhanced barrier function compared to wild-type MAECs, characterized by decreased albumin leakage and increased of TEER. The tag-switch assay showed increased sulfuration of occludin in HUVECs. In conclusion, H2S bioavailability regulates endothelial solute permeability.