Vascular Endothelial Cell Injury Partly Induced by Mesenteric Lymph in Heat Stroke

Animal models have shown that mesenteric lymph plays important roles in the pathogenesis of endothelium injury in many critical ill states. Gut-derived septicemia and endothelium injury are the two key pathogenesis of heat stroke (HS); however, it is unclear whether mesenteric lymph is cytotoxic to endothelium in HS. HS rat models were prepared in a prewarmed incubator. Mesenteric lymph, collected pre-, during, and post-HS, was analyzed for biological activity on human umbilical vein endothelial cell (HUVEC) in vitro. The effect of HS lymph on the production of von Willebrand factor (vWF), thrombomodulin (TM), and IL-6 by HUVEC was investigated. In vivo, vascular endothelium injury biomarkers, circulating endothelial cell (CEC), as well as serum soluble vWF and TM were tested in rats of HS and HS with mesenteric lymph duct ligation (HS-LDL). HS but not heat stroke sham mesenteric lymph-injured endothelial cells showed significantly increased HUVEC cytotoxicity and enhanced HUVEC monolayer permeability as well as elevated levels of vWF and TM production by HUVEC. IL-6 production by HUVEC was augmented by HS lymph in vitro. The effects of HS lymph on IL-6 production had a time course resembling that of the toxic effects of HS lymph on HUVEC. In vivo, when compared with HS rats, decreased CEC counts as well as lower serum vWF and TM concentrations were detected in HS-LDL rats. HS mesenteric lymph is probably harmful to vascular endothelium, which indicates that the modulation of mesenteric lymph may have some potential benefits to HS.