Cytokines modulate integrin alpha(v)beta(3)-mediated human endothelial cell adhesion and calcium signaling

Angiogenesis is a complex process regulated by the interactions of endothel ial cells with cytokines and the adhesive protein matrix. The cytokines bas ic fibroblast growth factor (bFGF) and tumor necrosis factor-alpha (TNF-alp ha) are two of the modulators of angiogenesis. One mechanism by which these cytokines induce their effects may be through the regulation of integrin a dhesion receptor activity, in particular, alpha(v)beta(3). In this study, w e examined the ability of these angiogenic factors to modulate the adhesion of human umbilical vein endothelial cells (HUVECs) to immobilized disinteg rins (i.e., rhodostomin and arietin), which are specific in antagonizing in tegrin alpha(v)beta(3) in cells. As these disintegrins were immobilized as substrates, they acted as agonists to induce HUVEC adhesion in a dose- and alpha(v)beta(3)-dependent manner. In addition, adhesion also triggered a su stained increase of intracellular free calcium. Furthermore, bFGF-primed HU VECs potentiated, but TNF-alpha primed cells attenuated, about 50% adhesion events and calcium signaling triggered by immobilized disintegrin compared to naive cells, respectively. The mechanisms of modulating alpha(v)beta(3) -dependent HUVEC adhesion by cytokines may be related to changes of integri n alpha(v)beta(3) conformation, as demonstrating the antagonistic effect of Mn2+ on decreased adhesion by TNF-alpha pretreatment, and confirmed with f low cytometric analysis probed by anti-LIBS1 mAb, However, cytokine pretrea tment did not alter the expression of this integrin on the cell surface, as determined by flow cytometry. Phosphoinositide-3 kinase may be one of the signaling molecules involved in the enhanced adhesion of bFGF-primed cells. (C) 1999 Academic Press.