Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Physical Sciences, Biochemistry & Molecular Biology, Chemistry, Multidisciplinary, Chemistry, proliferative diabetic retinopathy, proliferative vitreoretinopathy, macrophage-myofibroblast transition, M2 macrophages, DIABETIC-RETINOPATHY, MESENCHYMAL TRANSITION, FIBROCYTES, ACTIVATION, CELLS, Humans, Endothelial Cells, Myofibroblasts, Epiretinal Membrane, Tumor Necrosis Factor-alpha, Eye Diseases, Diabetic Retinopathy, Vitreoretinopathy, Proliferative, 1293422N#56289383, G0A3820N#55523812, C16/17/010#54271312, 0399 Other Chemical Sciences, 0604 Genetics, 0699 Other Biological Sciences, Chemical Physics, 3101 Biochemistry and cell biology, 3107 Microbiology, 3404 Medicinal and biomolecular chemistry

Abstract:

Inflammation and fibrosis are key features of proliferative vitreoretinal disorders. We aimed to define the macrophage phenotype and investigate the role of macrophage-myofibroblast transition (MMT) in the contribution to myofibroblast populations present in epiretinal membranes. Vitreous samples from proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR) and nondiabetic control patients, epiretinal fibrovascular membranes from PDR patients and fibrocellular membranes from PVR patients, human retinal Müller glial cells and human retinal microvascular endothelial cells (HRMECs) were studied by ELISA, immunohistochemistry and flow cytometry analysis. Myofibroblasts expressing α-SMA, fibroblast activation protein-α (FAP-α) and fibroblast-specific protein-1 (FSP-1) were present in all membranes. The majority of CD68+ monocytes/macrophages co-expressed the M2 macrophage marker CD206. In epiretinal membranes, cells undergoing MMT were identified by co-expression of the macrophage marker CD68 and myofibroblast markers α-SMA and FSP-1. Further analysis revealed that CD206+ M2 macrophages co-expressed α-SMA, FSP-1, FAP-α and ß-catenin. Soluble (s) CD206 and sFAP-α levels were significantly higher in vitreous samples from PDR and PVR patients than in nondiabetic control patients. The proinflammatory cytokine TNF-α and the hypoxia mimetic agent cobalt chloride induced upregulation of sFAP-α in culture media of Müller cells but not of HRMECs. The NF-ĸß inhibitor BAY11-7085 significantly attenuated TNF-α-induced upregulation of sFAP-α in Müller cells. Our findings suggest that the process of MMT might contribute to myofibroblast formation in epiretinal membranes, and this transition involved macrophages with a predominant M2 phenotype. In addition, sFAP-α as a vitreous biomarker may be derived from M2 macrophages transitioned to myofibroblasts and from Müller cells.