Cytokines modulate endothelial cell intracellular signal transduction required for VCAM-1-dependent lymphocyte transendothelial migration

Vascular cell adhesion molecule-1 (VCAM-1) activates endothelial cell NADPH oxidase which catalyzes production of reactive oxygen species (ROS). This activity is required for VCAM-1-dependent lymphocyte migration. The focus o f our study was to determine whether these VCAM-1-dependent functions are m odulated by cytokines. TGF-beta1 or IFN-gamma pretreatment of mouse endothe lial cell lines inhibited VCAM-1-dependent B and T cell transendothelial mi gration without affecting initial lymphocyte adhesion. Neutralizing anti-TG F-beta1 blocked the effects of TGF-beta1 pretreatment of endothelial cells, whereas addition of anti-TGF-beta1 after TGF-beta1 pretreatment of the end othelial cells did not block TGF-beta1-mediated inhibition. Neutralizing an ti-IFN-gamma also blocked the inhibitory effects of IFN-gamma. TGF-beta1 an d IFN-gamma blocked migration by inhibiting the VCAM-1-stimulated productio n of low levels of ROS (0.1-0.9 muM H2O2). These results demonstrate that b oth TGF-beta1 and IFN-gamma directly affect the endothelial cells' ability to promote lymphocyte migration. IL-4 had differing effects on T and B cell s during transmigration. IL-4 augmented T cell migration across the endothe lial cell lines but did not affect T cell adhesion. Conversely, IL-4 increa sed B cell adhesion to the endothelial cell lines without affecting migrati on. In summary, cytokines can directly modulate microvascular endothelial c ell intracellular signaling, demonstrating a new level of cytokine regulati on of lymphocyte diapedesis. (C) 2001 Academic Press.