Polyethylene glycol 35 preserves endothelial barrier integrity by stabilizing the glycocalyx and intercellular...

Endothelial dysfunction is a hallmark of numerous inflammatory and ischemic conditions, characterized by increased permeability, disruption of intercellular junctions and endothelial glycocalyx (eGCX) degradation. In the present study, we investigated the ability of polyethylene glycol 35 (PEG35) to preserve endothelial barrier integrity in cultured human umbilical vein endothelial cells (HUVECs) exposed to inflammatory, thrombotic, hypoxia-mimetic and eGCX-disrupting stimuli. PEG35 mitigated the loss of cellular metabolic activity induced by apoptotic and hypoxia-mimetic stress. Functionally, PEG35 attenuated stimulus-induced increases in FITC-dextran permeability and helped maintain trans-endothelial electrical resistance (TEER) under pro-inflammatory and eGCX-disrupting agents. PEG35 also reduced LDH release and maintained higher TEER values in endothelial cells exposed to plasma collected from pancreas transplant recipients after reperfusion, which contained increased circulating levels of the endothelial glycocalyx component syndecan-1. Mechanistically, PEG35 reduced NFĸB p65 nuclear translocation under thrombin, TNFα, and hyaluronidase stimulation and attenuated inflammatory and endothelial activation-related transcriptional responses. PEG35 also modulated intercellular junction gene expression in a stimulus and target-dependent manner, helped maintain occludin and claudin-5 protein expression under selected injurious conditions, and limited the loss of eGCX-associated syndecan-1 and heparan sulfate staining after enzymatic degradation. Collectively, these findings support a multifactorial endothelial-protective effect of PEG35 involving preservation of endothelial surface layer, maintenance of junctional integrity and attenuation of inflammatory signalling. These results identify PEG35 as a potential vasoprotective candidate for conditions involving acute endothelial barrier injury.