title: Plasminogen activator inhibitor-1 overexpression in nonproliferative diabetic retinopathy.
abstract: Plasminogen activator inhibitor-1 is secreted bidirectionally by endothelial cells, acts as the primary regulator of fibrinolysis and as a key modulator of extracellular matrix proteolysis. Elevated serum levels of plasminogen activator inhibitor-1 are observed in serum of diabetic individuals. We investigated whether plasminogen activator inhibitor-1 is overexpressed in capillaries of diabetic donors with non-proliferative retinopathy compared to non-diabetic donors. We also assessed plasminogen activator inhibitor-1 expression in an animal model of retinopathy induced by exposing rabbit retinas to insulin-like growth factor-I. Colloidal gold immunocytochemistry was used to quantify plasminogen activator-1 antigen in donor retinas from diabetic subjects (n = 10) and control subjects (n = 10). This technique was also used to examine expression of plasminogen activator inhibitor-1 for correlation with retinal changes in the insulin-like growth factor-I-induced retinopathy model (n = 14). Plasminogen activator inhibitor-1 immunoreactivity was significantly increased in the retinas of all diabetic subjects as compared to controls. In the rabbit model, the expression of plasminogen activator inhibitor-1 immunoreactivity correlated with pathological retinal changes. In both the diabetic human and insulin-like growth factor-I-injected rabbit, overproduction of plasminogen activator inhibitor-1 was seen within the lumen of capillaries, within the cytoplasm of endothelial cells and in the basement membrane and extracellular matrix surrounding these capillaries. Minimal plasminogen activator inhibitor-1 was detected in the retinas of non-diabetics and in control rabbits injected with either heat-inactivated insulin-like growth factor-I or balanced salt solution. These studies support the conclusion that plasminogen activator inhibitor-1 is overexpressed in the retinal capillaries of diabetics with non-proliferative diabetic retinopathy and in rabbits with insulin-like growth factor-I-induced retinopathy.
authors.affiliation: Division of Endocrinology and Metabolism, College of Medicine, University of Florida, Gainesville 32610-0226, USA.
authors.forename: M B
authors.initials: MB
authors.lastname: Grant
authors.forename: E A
authors.initials: EA
authors.lastname: Ellis
authors.forename: S
authors.initials: S
authors.lastname: Caballero
authors.forename: R N
authors.initials: RN
authors.lastname: Mames
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D001485:Basement Membrane / Q000378:metabolism; D002196:Capillaries / Q000378:metabolism; D003930:Diabetic Retinopathy / Q000378:metabolism* / Q000473:pathology; D005109:Extracellular Matrix / Q000378:metabolism; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008854:Microscopy, Electron; D008875:Middle Aged; D017395:Plasminogen Activator Inhibitor 1 / Q000032:analysis / Q000378:metabolism*; D011817:Rabbits
chemical_list: D017395:Plasminogen Activator Inhibitor 1