Cytokines Modulate Integrin αvβ3-Mediated Human Endothelial Cell Adhesion and Calcium Signaling (original) (raw)

1999, Experimental Cell Research

Angiogenesis is a complex process regulated by the interactions of endothelial cells with cytokines and the adhesive protein matrix. The cytokines basic fibroblast growth factor (bFGF) and tumor necrosis factor-␣ (TNF-␣) are two of the modulators of angiogenesis. One mechanism by which these cytokines induce their effects may be through the regulation of integrin adhesion receptor activity, in particular, ␣ v ␤ 3. In this study, we examined the ability of these angiogenic factors to modulate the adhesion of human umbilical vein endothelial cells (HUVECs) to immobilized disintegrins (i.e., rhodostomin and arietin), which are specific in antagonizing integrin ␣ v ␤ 3 in cells. As these disintegrins were immobilized as substrates, they acted as agonists to induce HUVEC adhesion in a doseand ␣ v ␤ 3-dependent manner. In addition, adhesion also triggered a sustained increase of intracellular free calcium. Furthermore, bFGF-primed HUVECs potentiated, but TNF-␣ primed cells attenuated, about 50% adhesion events and calcium signaling triggered by immobilized disintegrin compared to naive cells, respectively. The mechanisms of modulating ␣ v ␤ 3-dependent HUVEC adhesion by cytokines may be related to changes of integrin ␣ v ␤ 3 conformation, as demonstrating the antagonistic effect of Mn 2؉ on decreased adhesion by TNF-␣ pretreatment, and confirmed with flow cytometric analysis probed by anti-LIBS1 mAb. However, cytokine pretreatment 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.