Irisin modulates the association of interleukin-17A with the presence of non-proliferative diabetic retinopathy in patients with type 2 diabetes

The role of inflammation in pathogenesis of diabetic retinopathy (DR) is getting increasingly recognized. However, it is unclear whether and how non-proliferative diabetic retinopathy (NPDR) is affected by Interleukin-17A (IL-17A) and Interleukin-22 (IL-22), two well-known inflammatory factors, and irisin, a novel potential anti-inflammatory factor. Here we recruited 40 type 2 diabetes mellitus (T2DM) patients with NPDR, 60 T2DM patients without DR (no-DR), and 20 normal glucose tolerance (NGT) controls. Serum levels of IL-17A, IL-22, and irisin were examined. Compared with NGT and no-DR subjects, NPDR group had significantly higher IL-17A levels. Irisin levels were significantly lower in T2DM patients, while IL-22 levels were not significantly different across all three groups. Multiple logistic regression analysis revealed that IL-17A significantly increased the risk of NPDR (OR = 1.22, P < 0.05) before adjusting for irisin. When irisin was included in the model, neither irisin nor IL-17A was associated with NPDR. Further partial correlation analysis showed that irisin was intrinsically correlated with IL-17A even after multiple adjustment (r = −0.252; P = 0.018). These findings suggest that IL-17A is an independent risk factor of NPDR, and irisin could protect against DR through potential anti-IL-17A effects.