Th17 cell frequency and IL-17A concentrations in peripheral blood mononuclear cells and vitreous fluid from patients with diabetic retinopathy

OBJECTIVE: To quantify T helper (Th)17 cells and determine interleukin (IL)-17A levels in peripheral blood mononuclear cell (PBMC) culture and vitreous fluid from patients with type 2 diabetes mellitus (T2DM) with diabetic retinopathy (DR). METHODS: Th17 cell frequency and IL-17A concentrations in PBMCs from 60 patients with T2DM with DR, 30 without DR and 30 sex- and age-matched healthy individuals were measured by flow cytometry and enzyme-linked immunosorbent assay (ELISA), respectively. IL-17A levels in vitreous fluid from 31 eyes with proliferative DR and diabetic macular oedema (DR group) and 32 eyes with an epiretinal membrane and macular hole (control group) that underwent vitrectomy were also examined by ELISA. RESULTS: Compared with the control group, the proportion of Th17 cells and IL-17A concentrations in PBMCs were significantly increased in patients without DR but decreased in those with DR. IL-17A concentrations and Th17 cell frequency in PBMCs tended to decrease with DR severity and were negatively correlated with body mass index, T2DM duration and glycated haemoglobin. Additionally, vitreous fluid IL-17A levels were significantly elevated in patients with DR compared with those of the control group. CONCLUSIONS: We conclude that disturbances in Th17 cells and IL-17A levels are possibly associated with DR.