FIBRONECTIN, LAMININ, VITRONECTIN AND THEIR RECEPTORS AT NEWLY-FORMEDCAPILLARIES IN PROLIFERATIVE DIABETIC-RETINOPATHY

Proliferative diabetic retinopathy (PDR) is characterized by intraocul ar formation of fibroglial vascularized tissue by active vasoprolifera tive mechanisms. Using immunocytochemistry, we have studied changes in the distribution pattern of fibronectin (FN), laminin (LN), vitronect in (VN) and their receptors in the newly-formed capillaries of PDR. In intraocular vascularized tissue of PDR patients, FN was present on bo th luminal and basal surfaces of endothelial cells, and was diffusely distributed in the interpericyte space. LN was also associated with th e interpericyte space. VN was occasionally detected on the luminal cap illary side, but was frequent in the basal aspect of the endothelium i n the interpericyte space, where it was colocalized with FN. Beta-1 su bunit complex receptors were detected on the luminal side, while alpha (v) beta(3) integrin was identified on both sides, more so in the lumi nal than in the basal endothelial domain. By slot-blotting techniques and densitometric analysis, increased concentrations of intravitreous FN and VN were found in PDR in comparison with normal samples. These r esults suggest that FN, VN and LN have a key role in the structural ar rangement of newly formed capillaries in PDR, and that receptor expres sion could be involved in events of endothelial cell adhesion and prol iferation.