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 (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).
METHODS: 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.
RESULTS: 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.
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.