Abstract
Abstract: :
Purpose: Integrins are a class of heterodimeric plasma membrane proteins that play an important role in cell–extracellular matrix and/or cell–cell interactions. Recently, integrins have been shown to play a role in the pathogenesis of a variety of proliferative diseases including angiogenesis. The integrins implicated in an angiogenic response include α1 ß1, α2 ß1, α5 ß1, αV ß3, ß3 and αV ß5. The purpose of the study is to investigate the expression and co–localization of integrins and endothelial cells in various stages of proliferative diabetic retinopathy (PDR). Methods: Eight PDR membranes were collected from eyes via vitreoretinal surgery. A double immunohistochemical staining procedure was used to identify the presence and co–localization of integrins and endothelial cells. Primary antibodies against α1 ß1, α2 ß1, α5 ß1, αV ß3, ß3 and αV ß5 were used in combination with primary antibodies against Von Willibrand Factor (VWF) or CD31, both markers of endothelial cells. Secondary antibodies were tagged with Alexa–488 or Cy3. The Zeiss Inverted Axiovert 200M Confocal Laser–scanning Microscope (Zeiss–LSM 510 META) was used to visualize immunohistochemical labeling. Tonsil tissues were used as positive control tissue in this study. Results: Cells in PDR membranes expressed α1 ß1, α2 ß1, αV ß3, and ß3, but not α5 ß1 or αV ß5. Of the four that are expressed in PDR membranes, only two, αV ß3 and ß3, demonstrated colocalization with endothelial cells. Late stage PDR membranes, characterized by fibrosis, were negative for both integrins and endothelial cells. Conclusions: PDR membranes are positive for α1 ß1, α2 ß1, αV ß3 and ß3 integrins. Of these, only αV ß3 and ß3 colocalize with endothelial cells within PDR membranes. These results suggest that therapeutic applications focused on blocking α V ß3 and/or ß3 may be helpful in minimizing neovascularization in proliferative diabetic retinopathy.
Keywords: diabetic retinopathy • growth factors/growth factor receptors • immunohistochemistry