Effect of adipose tissue-derived inflammatory and proangiogenic cytokines on proliferative diabetic retinopathy

Objective: To determine the vitreous and serum concentrations of TNF-alpha, IL-6, VEGF, IL-1 beta, IL-8, IL-17, MCP-1, IL-1Ra, IL-10 in patients with proliferative diabetic retinopathy (PDR) and to investigate the effect of adipose tissue on the pathogenesis of PDR. Methods: Twenty-two patients with PDR were prospectively evaluated. Seven cadavers and 11 patients with idiopathic epiretinal membrane or macular hole served as the controls. Multiplex bead array technology was employed to assess the concentrations of the cytokines. Results: The intravitreal levels of VEGF, IL-8, IL-6 were significantly higher in PDR group than control groups. In PDR group, the levels of IL-17, IL-8, IL-6 were significantly elevated in the vitreous, whereas the intravitreal levels of IL-10, IL-1Ra were found to be significantly lower than the serum concentrations. No significant correlation was found between cytokine levels and body mass index (BMI), fasting blood glucose (FBG), or glycated haemoglobin (HbA1c) of diabetic patients. Conclusion: In PDR the balance between the intravitreal pro-and anti-inflammatory adipo-cytokines is disturbed in favor of proinflammatory and proangiogenic cytokines in the vitreous humour. This study supports the role of adipocytokines in vascular pathology in PDR. It seems that PDR is a local inflammatory disease. However, obesity may not be the root of the inflammatory mediators in PDR.