Background: Patients diagnosed with chronic obstructive pulmonary disease (COPD) have increased risks for a series of physical and mental illnesses. Tumor necrosis factor-α (TNF-α) has been reported to participate in the development of COPD and its complications. However, the values of blood TNF-α level used in the diagnosis of COPD remains controversial. In view of this, we performed a systematic review and meta-analysis to evaluate the correlation between TNF-α level and COPD. Methods: We searched PubMed, Web of Science, Embase and CNKI up to May 2018. The selection criteria were set according to the PICOS framework. A random-effects model was then applied to evaluate the overall effect sizes by calculating standard mean difference (SMD) and its 95% confidence intervals (CIs). Results: A total of 40 articles containing 4189 COPD patients and 1676 healthy controls were included in this meta-analysis. The results indicated a significant increase in TNF-α level in the COPD group compared with the control group (SMD: 1.24, 95% CI: 0.78–1.71, p < 0.00001). According to the subgroup analyses, we noted that TNF-α level was associated with predicted first second of forced expiration (FEV₁) (%) and study region. However, no association between TNF-α level and COPD was found when the participants were nonsmokers, and the mean age was less than 60 years. Conclusions: Our results indicated that TNF-α level was increased in COPD patients when compared with healthy controls. Illness progression and a diagnosis of COPD might contribute to higher TNF-α levels. However, the underlying mechanism still remains unknown and needs further investigation. The reviews of this paper are available via the supplemental material section.

Backgroud: Interleukin-6 (IL-6) is produced by a variety of cells involved in inflammation 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 IL-6 and Diabetic Retinopathy. Methods: The study was started with systematic search for literatures by using the PubMed, Web of Science and Embase online databases. The standard mean difference (SMD) and its 95% confidence intervals (CIs) were was included and then pooled with a random effects model. Results: 31 articles, containing1099 DR patients and 1010 controls, were included in this meta-analysis. The level of IL-6 in the DR group was found to be higher than that in the control group (SMD: 2.12, 95% CI: 1.53 −2.70, p < 0.00001).Obvious heterogeneity existed between the studies(p < 0.00001,I² = 96%). So a subgroup analysis and sensitivity analysis were performed. Removing the sensitivity studies, the stability of the overall treatment effect was good. Subgroup analysis showed that the level of IL-6 in case group were observed to be higher than those in the control group. and the IL-6 levels in the proliferative diabetic retinopathy(PDR) group were also higher than those in the non-proliferative diabetic retinopathy(NPDR) group. (SMD: 0.78, 95% CI: 0.26–1.31, p = 0.003) Conclusion: The results from this current meta-analysis indicated that increased level of IL-6 generally exist in DR patients. And it may associated with the severity of DR. However, large-scale and high-quality studies in future are required to confirm the present findings.

Elevated levels of proinflammatory markers are evident in patients with diabetic retinopathy (DR) and are associated with disease progression and prognosis. Intercellular adhesion molecule-1 (ICAM-1) is involved in inflammation and acts as a local intensifying signal in the pathological processes associated with chronic eye inflammation. The aim of this systematic review and meta-analysis was to investigate the relationship between ICAM-1 level and DR. Online electronic databases were searched to retrieve all relevant articles published before December 2017. The standard mean difference (SMD) and their 95% CI were included and then pooled with a random effects model. Subgroup analysis and metaregression analysis were applied to explore the sources of heterogeneity, and publication bias was calculated to assess the quality of pooled studies. A total of 11 articles, containing 428 patients with DR and 789 healthy controls, were included in this meta-analysis. The results indicated a significant increase in ICAM-1 level in the DR group compared with the control group (SMD: 1.20, 95%CI 0.83 to 1.57, p<0.001). Subgroup analyses and metaregression analysis indicated that publication year, region, study method, diabetes mellitus type, Newcastle-Ottawa Scale and sample size were not the potential sources of heterogeneity. The results of this current meta-analysis indicated that the increased level of ICAM-1 generally exists in the patients with DR and it may associated with the severity of DR. However, large-scale and high-quality studies are required to confirm this finding in the future.