BASEMENT-MEMBRANE ABNORMALITIES IN HUMAN EYES WITH DIABETIC-RETINOPATHY

Vascular and parenchymal basement membranes (BMs) are thickened in dia betes, but alterations in individual BM components in diabetic eyes, e specially in diabetic retinopathy (DR), are obscure. To identify abnor malities in the distribution of specific constituents, we analyzed cry ostat sections of human eyes obtained at autopsy (seven normal, five d iabetic without DR, and 13 diabetic with DR) by immunofluorescence wit h antibodies to 30 BM and extracellular matrix components. In non-DR e yes, no qualitative changes of ocular BM components were seen. In some DR corneas, epithelial BM: was stained discontinuously for laminin-l, entactin/nidogen, and alpha 3-alpha 4 Type IV collagen, in contrast t o non-DR corneas. Major BM alterations were found in DR retinas compar ed to normals and non-DR diabetics. The inner limiting membrane (retin al BM) of DR eyes had accumulations of fibronectin (including cellular ) and Types I, III, IV (alpha 1-alpha 2), and V collagen. The BM zone of new retinal blood vessels in neovascularized areas accumulated tena scin and Type XII ; collagen, whereas normal, diabetic, and adjacent D R retinas showed only weak and irregular staining. In preretinal membr anes, perlecan, bamacan, and Types VI, VIII, XII, and XIV collagen wer e newly identified. Diabetic BM thickening appears to involve qualitat ive alterations of specific BM markers at an advanced disease stage, w ith the appearance of DR.