Tumor necrosis factor-α and diabetic retinopathy: Review and meta-analysis

Background: Tumor necrosis factor-alpha (TNF-alpha) is produced by multinuclear giant cells and acts as local intensification signals in pathological processes associated with chronic eye inflammation. This meta-analysis was performed to provide a better understanding of the relationship between TNF-alpha and diabetic retinopathy (DR). Method: Online electric databases were searched to retrieve all relevant articles published before October 2017. The standard mean difference (SMD) and their 95% confidence intervals (CI) were included and then pooled with a random effects model. Results: A total of 16 articles with 1286 participants were included in this meta-analysis. No difference in the level of TNF-alpha was found between DR patients and healthy controls (SMD = 0.39, 95% CI = -0.09 to 0.68, P = 0.01). Subgroup analysis showed that with respect to the level of TNF-alpha, the association was significant for studies conducted in Europe (SMD: 0.57, 95% CI: 0.11-1.02, P = 0.01), patients with type 1 DM (SMD: 1.06, 95% CI: 0.09-2.04, P = 0.03), studies based on serum samples (SMD: 0.57, 95% CI: 0.12-1.02, P = 0.01) and studies with a sample size > 50 (SMD: 0.39, 95% CI: 0.03-0.75, P = 0.04). Conclusion: The results this meta-analysis indicated that the level of TNF-alpha in DR patients was significantly different from that in the healthy controls, so TNF-alpha represents a candidate biomarker for DR.