THE ROLE OF FIBRONECTIN, LAMININ, VITRONECTIN AND THEIR RECEPTORS ON CELLULAR ADHESION IN PROLIFERATIVE VITREORETINOPATHY

Purpose. To examine the possible role of some adhesion multifunctional glycoproteins of the extracellular matrix, such as fibronectin (FN), laminin (LN), vitronectin CVN) and their receptors (beta(1)-subunit co mplex and alpha(v) beta(3) integrins) in events of cell migration and adhesion in proliferative vitreoretinopathy (PVR). Methods. Optical an d electron-immunocytochemical techniques were carried out on epiretina l 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 statisti cal analysis.Results. FN was detected as a major component in the extr acellular matrix in both fibrillar and pericellular arrangement. A cha nge in pericellular distribution to more fibrillous organization was r elated 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. Increas ed levels of FN concentration were observed in both subretinal fluid a nd pathologic vitreous; intravitreal FN concentration tends to increas e with clinical stages of the evolution of PVR, whereas intravitreal V N levels tend to decrease. Conclusions. Results suggest that FN could mediate the initial events involved in epiretinal membrane formation, and VN could modulate the adhesion mechanisms in established membranes .