Expression of receptors for extracellular matrix proteins in human endothelial cells

The interaction with matrix components of the basal membrane is an important factor in the control of vascular endothelial cell function in both normal and pathological conditions. In the present work we define integrin receptors in vascular endothelial cells and analyze whether their expression is affected by endothelial cell activators. Using in vitro adhesion tests we show that human endothelial cells (HEC) can attach and spread on substrates coated with several matrix components including fibronectin, laminin, collagen type IV, fibrinogen and vitronectin. Using specific antibodies we detect integrin receptor complexes of the beta 1 and beta 3 families that can support adhesion of HEC to the above matrix proteins. These are the alpha 2/beta 1 collagen receptor, the alpha 3/beta 1 receptor for fibronectin, collagens and laminin, the alpha 5/beta 1 fibronectin receptor, the alpha 6/beta 1 laminin receptor and the alpha V/beta 3 receptor for vitronectin and fibrinogen. When HEC are exposed to a combination of tumor necrosis factor alpha (TNF alpha) and immune interferon (IFN-gamma) the amount of the alpha V/beta 3 vitronectin receptor at the cell surface was decreased by a factor of 50-70%, while the beta 1 integrin complexes were not affected. HEC cells thus express receptors for several matrix components and inflammatory mediators such as TNF alpha and IFN-gamma can selectively alter the expression of some of them.