Background: Microvascular hyperpermeability is a crucial contributor to the gastrointestinal injury, for which the current clinical therapy remains unsatisfied. Src regulates the hyperpermeability-related proteins, such as caveolin-1, VE-cadherin and ZO-1. This study aimed to evaluate whether salvianolic acid B (SalB) binds to Src to regulate caveolin-1, VE-cadherin and ZO-1, to ameliorate mesenteric venules hyperpermeability in endotoxmia rats.
Methods: The male Wistar rats were challenged by infusion of LPS (2mg/kg/h) for 90 min, with or without SalB (5mg/kg/h). Human umbilical vein endothelial cells (HUVECs) were incubated with LPS or/and SalB. Microcirculation was assessed by intravital microscopy, caveolae in microvascular endothelial cells by electron microscopy, endothelial cell junctional proteins, caveolin-1 and Src by Western blot and confocal microscopy, and the interaction of Src and SalB by Surface Plasmon Resonance (SPR) and BioLayer Interferometry (BLI).
Results: SPR and BLI demonstrated that SalB was able to bind to Src in a dose-dependent manner, further to inhibit the phosphorylation of Src, caveolin-1 and vascular endothelial cadherin increased in human umbilical vein endothelial cells, to restore the distribution of Zonula occluden-1 and VE-cadherin degradated in cells exposed to LPS. Furthermore, SalB alleviated the inclement of caveolae in microvascular venules, and the evoked albumin leakage from venules in endotoxmia rat mesentery.
Conclusions: SalB prevents endothelial barrier dysfunction and hyperpermeability via binding to Src to inhibit the activity of Src. These findings identify SalB as a promising approach to permeability, and indicate Src as novel target for hyperpermeability treatment.
