Purpose: To investigate the role of chemokines in the pathogenesis of proliferative diabetic retinopathy (PDR).
Subjects and methods: In total, 41 eyes of 38 patients undergoing vitrectomy were divided into two groups; PDR and non-PDR. The PDR group was comprised of 30 eyes, and the non-PDR group of 11 eyes. Vitreous specimens obtained at vitrectomy were centrifuged and separated into supernatants and cellular components. Concentrations of vascular endothelial growth factor(VEGF), interleukin-8 (IL-8), monocyte chemotactic protein-1 (MCP-1), and regulated upon activation, normal T cell expressed and secreted(RANTES) in the supernatants were determined by enzyme-linked immunosorbent assay(ELISA) or chemiluminescence enzyme immunoassay(CLEIA). Expression of VEGF in the cellular components was determined by immunohistochemistry.
Results: Vitreous levels of VEGF(p < 0.05), IL8 (p < 0.0001) and MCP-1 (p < 0.05) in the PDR group were significantly higher than in the non-PDR group. However, there was no significant difference in RANTES between the two groups. There was a significant correlation (p < 0.0001, r = 0.84) between vitreous IL-8 and MCP-1 levels in the PDR group. After immunohistochemical staining with antiVEGF monoclonal antibody, VEGF positivity was localized in polymorphonuclear leukocytes and monocytes of the cellular components of PDR vitreous specimens.
Conclusions: These results indicate that chemokines are possibly involved in the recruitment of neutrophils and monocytes into the vitreous and that they play a role in the intraocular neovascularization characteristic of PDR.