Role of tumour necrosis factor-alpha and interleukin-6 in the development and progression of diabetic retinopathy in type 2 diabetes mellitus patients

Abstract

Diabetic retinopathy is one of the most serious complications of diabetes mellitus(DM) worldwide. Purpose: To evaluated the role of tumour necrosis factor-alpha (TNF-a) and interleukin-6 (IL-6) in the diabetic retinopathy. Methods: This study included 85 subjects divided into 4 groups: Group A included 25 healthy controls. Group B: 20 diabetic patients without evidence of retinopathy. Group C: 20 non proliferative diabetic retinopathy patients. Group D included 20 proliferative diabetic retinopathy patients. Participants were subjected to full clinical history, clinical and ophthalmologic examination and laboratory investigation including measurements of fasting blood sugar(FBS), glycosylated hemoglobin(HbA₁c), lipid profile, serum TNF-a, IL-6 and ultrasensitive C-reactive protein.

Results: This study showed significantly higher values of FBS, HbA₁c, lipid profiles, TNF-a, IL-6 and CRP in diabetic patients when compared to healthy controls (p<0.05). Groups C and D patients showed significant increase of FBS, HbA₁c, lipid profile, TNF-a, IL-6 and CRP when compared to group B. Moreover, high levels of FBS, HbA₁c, TNF-a and IL-6 were observed in group D compared to group C but no difference was observed between the 2 groups regarding lipid profile and CRP. Postive correlation between serum levels of TNF-a and HbA₁c and between serum levels of IL-6 and CRP was observed in all patient groups. There was a significant positive correlation between severity of diabetic retinopathy and serum levels of TNF-a and HbA₁c in addition to the duration of diabetes.

Conclusion: The study provides evidence that TNF-α and IL-6 may play a role in the development and progression of diabetic retinopathy.