Inflammatory activity in diabetic neovascular membranes: Immunohistochemical and ultrastructural study

Abstract

Abstract: : Purpose: to identify inflammatory activity in diabetic neovascular membranes using histopathologic examination with immunohistochemistry (IHQ), light and transmission electron microscopy (TEM). Methods: Fifteen neovascular membranes from type II diabetic proliferative retinopathy and retinal detachment were studied. A 5µm section was stained with hematoxylin and eosin, Masson trichrome and Gomori in all cases. The avidin–biotin peroxidase (ABC) technique was performed in each case using antibodies to the following antigens: vimentin (Monoclonal–Biogenex)(MB), actin muscle–specific (MB), vascular endothelial growth factor (VEGF. MB), leukocyte common antigen (LCA, CD45. MB), B cells (CD 20. MB), T cells (MB), intercellular adhesion molecule–1 (ICAM 1. MB) and Interleukin 8 (Policlonal). Appropriate positive and negative controls were used in each run. After that, it was desparaffinated, postfixed with osmium tetroxide and embedded in epoxi resin, and studied by TEM. Results: All fifteen cases had remarkably similar histologic features: collagen matrix (15/15), myofibroblasts–like cells (12/15), VEGF (15/15). Inflammation was present in all the membranes (ACL + focal or diffuse), ICAM–1 + focal in hipovascularized areas. Isolation of lymphoid cells was remarkable with TEM. Interleukin 8 was strongly positive only in a focal way in endothelial cells. Conclusions: Intraocular neovascularization is the most important cause of vision loss in patiens with diabetic retinopathy. Retinal ischemia often precedes the presence of VEGF or other angiogenic factors like inflammation (lymphocytes in membranes with TEM). The pathologic role of leucocyte cytokines expression in diabetic membranes was also examined in the present study.

Keywords: diabetic retinopathy • immunohistochemistry • vitreoretinal surgery