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

Abstract Background Tumor necrosis factor-alpha (TNF-α) 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-α 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-α 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-α, 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-α in DR patients was significantly different from that in the healthy controls, so TNF-α represents a candidate biomarker for DR.