Vitronectin and proliferative intraocular disorders. I. A colocalisation study of the serum spreading factor, vitronectin, and fibronectin in traction membranes from patients with proliferative vitreoretinopathy

Abstract

The presence of a scaffold for cellular spreading and proliferation is a precondition for the development of traction membranes in proliferative vitreoretinopathy (PVR). This study shows the presence of the serum spreading factor, vitronectin, in the extracellular matrix of periretinal membranes removed during vitreoretinal surgery. By means of a double label immunofluorescence protocol, a partial colocalisation of vitronectin with fibronectin at the magnification of light microscopy can be detected. Fibronectin is a high-molecular glycoprotein with multiple biological functions including the mediation of cell attachment and migration. Both proteins share a special cell recognition site which could be a target for experimental pharmacological approaches to PVR. Preliminary studies of vitreous aspirates using electrophoresis and Western blotting indicate that vitronectin may play a more important role in post-traumatic PVR as compared to PVR following rhegmatogenous retinal detachment.

Components of the fibrinolytic system in the vitreous body in patients with vitreoretinal disorders

“…A limited number of reports exist regarding details of cellular metabolism in macular pucker, RD and PVR. Also the glycoprotein vitronectin has been identified in epiretinal membranes 40 . This glycoprotein stabilizes PAI‐1 41 and mediates its binding to extracellular matrix 42 .…”

Plasminogen in proliferative vitreoretinal disorders

“…Alteration of coagulation factors, especially increased levels of antithrombin III, have been reported 3839 We have previously reported the presence of vitronectin in epiretinal membranes40 and elevated plasma levels of this protein in diabetic patients 2241 stabilises plasminogen activator inhibitor-1 (PAI-1),42 and mediates PAI-1 binding to extracellular matrix 43…”

Proliferative vitreoretinopathy ? is it anything more than wound healing at the wrong place?

“…Similarly, the levels of intravitreal fibronectin, an indicator of proliferative process activity [47], are higher in vitreous aspirates from patients with traumatic PVR, especially in relation to the total protein content of the vitreous samples [124]. Immunofluorescence labeling of periretinal membranes for the serum spreading factor, vitronectin, has produced a third piece of evidence for a different course in idiopathic and traumatic PVR [122]. None of these findings, however, proves a qualitative difference between traumatic and idiopathic PVR.…”

“…Progress in the insight into the pathogenesis of PVR will be made more rapidly by the analysis of human vitreous aspirates and periretinal membranes than by animal models of PVR. Recent ideas which have introduced new aspects of PVR involved TGF-~ [34,35], transferrin [125], and vitronectin [122]. None of these studies was based on an animal model.…”

“…The important role of fibronectin can be deduced from interactions with all six cellular elements involved in soft tissue repair (see above). It remains to be seen whether the presence of the serum spreading factor, vitronectin, in periretinal membranes [122] will be confirmed in future studies on would healing elsewhere in the body. Both fibronectin and vitronectin belong to a class of distict attachment proteins which exhibit a cell binding domain containing the amino acid sequence arg-gly-asp or, following the amino acid code, RGD [1,9,97].…”