Endotoxic shock is associated with acute vascular endothelial injury resulting in edema. Tumor necrosis factor (TNF) and interleukin 1 (IL-1) are cytokines produced by endotoxin-stimulated mononuclear phagocytes that are potential mediators of endotoxic shock. In this study, we investigated the effects of TNF and IL-1 alpha on vascular endothelial cell permeability in vitro. The movement of radiolabeled macromolecules of different sizes (57Co-vitamin B12, 125I-cytochrome c, and 131I-albumin; 6.5-35A) across bovine aortic endothelial cell monolayers was measured after exposure to these cytokines. TNF induced a time- and dose-dependent increase in endothelial cell monolayer permeability that was enhanced in the presence of serum. The peak increase was noted after 12 h of incubation with less alteration of permeability with longer incubations. IL-1 alpha caused a similar time-dependent increase in endothelial cell monolayer permeability, but the peak effect of IL-1 alpha was seen after 24 h. Therefore the increased permeability seen with TNF cannot be explained by release of endogenous IL-1 alone. Neither TNF nor IL-1 alpha increased release of [14C]adenine, and the only effect on lactate dehydrogenase release was a small, but statistically significant, increase after 24 h of incubation. From these studies, we conclude that TNF and IL-1 alpha directly increase vascular endothelial cell permeability in vitro and speculate that these cytokines may be involved in the acute vascular endothelial injury associated with endotoxic shock.
Vascular Endothelial Growth Factor-C, a Potential Paracrine Regulator of Glomerular Permeability, Increases Glomerular Endothelial Cell Monolayer Integrity and Intracellular Calcium
