Makrophagen in der Ultrastruktur der PDR- und AMD-Membranen - Potenzieller Einfluss auf Neoangiogenese?

Abstract

Proliferative diabetic retinopathy (PDR) and age-related macular degeneration (AMD) are sight-threatening diseases with high social impact. The aim of our study is to compare the ultrastructure of PDR membranes and those in AMD with a special focus on the macrophages. In our study 24 PDR patients and 11 AMD patients were enrolled. They all underwent complete ophthalmological examination including OCT. In all cases pars plana vitrectomy with excision of epiretinal or subretinal membranes was performed. Proliferations taken directly from the eye have been studied by transmission and scanning electron microscopy and with safranin O. The fibrovascular proliferations in PDR consisted mostly of fibroblasts and occasional macrophages near the blood vessels. The prevailing type of blood vessels had one thin layer of endothelial cells, very thin basal membrane and no pericytes. Subretinal membranes in AMD patients consisted mainly of fibroblasts, isolated RPE cells and elements of the blood. Numerous macrophages and leukocytes in groups and clusters were found around the capillaries of subretinal blood vessels. The cells showed some peculiarities: diminished number of pseudopodia, altered shape. Groups of cytofilaments became visible in macrophages cell periphery. The number of proteoglycans in the matrix was increased. Our results point out that macrophages play a key role in the formation of the fibrovascular proliferations in both PDR and AMD. Inflammation is assumed to act in the pathogenesis of both diseases. Probably the senescence of macrophages, which we found in our study, is responsible for their proangiogenic response and promotion of new vessel formation. It is reasonable to expect that anti-inflammatory therapy might be helpful in patients with AMD and PDR.