The role of fibronectin, laminin, vitronectin and their receptors on cellular adhesion in proliferative vitreoretinopathy.

To examine the possible role of some adhesion multifunctional glycoproteins of the extracellular matrix, such as fibronectin (FN), laminin (LN), vitronectin (VN) and their receptors (beta 1-subunit complex and alpha v beta 3 integrins) in events of cell migration and adhesion in proliferative vitreoretinopathy (PVR). Optical and electron-immunocytochemical techniques were carried out on epiretinal membranes. Electrophoretic immunoblotting methods and densitometric analysis of normal and PVR vitreous were also undertaken. Chi-square (chi 2) and unbalanced analysis of variance were employed for statistical analysis. FN was detected as a major component in the extracellular matrix in both fibrillar and pericellular arrangement. A change in pericellular distribution to more fibrillous organization was related to the time of intraocular proliferative tissue development (P < 0.001). LN and VN were observed as minor components in extracellular matrix. A colocalized pattern between VN and FN in collagenic bundles of the matrix was often observed. Beta-1 subunit and alpha v beta 3 receptors were usually localized in a position that could mediate the interaction of FN, VN, and/or LN to the cell plasma membrane. Increased levels of FN concentration were observed in both subretinal fluid and pathologic vitreous; intravitreal FN concentration tends to increase with clinical stages of the evolution of PVR, whereas intravitreal VN levels tend to decrease. Results suggest that FN could mediate the initial events involved in epiretinal membrane formation, and VN could modulate the adhesion mechanisms in established membranes.