Effect of PM2.5 exposure on circulating fibrinogen and IL-6 levels: A systematic review and meta-analysis

Background Ambient fine particulate matter (PM2.5) pollution poses a great threat on global health. Previous studies have reported that PM2.5 regulates circulating fibrinogen and IL-6 levels in the development of cardiovascular and respiratory disease. However, the correlation between PM2.5 exposure and both biomarkers remains inconsistent. Methods We searched related articles through PubMed, Web of Science and ScienceDirect. Random effects model was used to obtain a pooled estimate effect of both biomarkers as PM2.5 concentration increased by every 10 μg/m3. Meta-regression analysis, sensitivity analysis and publication bias test were conducted to evaluate the heterogeneity, stability and reliability of this meta-analysis. Results A total of 22 articles were included. Each 10 μg/m3 increase in PM2.5 concentration was significantly correlated with a 1.76% increase in circulating fibrinogen level (95% CI: 0.38%–3.14%, P = 0.013) and a 4.66% increase in IL-6 level (95% CI: 1.14%–8.18%, P = 0.010). Subgroup analysis revealed that high-level PM2.5 exposure had a more significant association with circulating IL-6 level (11.67%, 95% CI: 0.66%–22.69%, P = 0.038) than low-level exposure, but this association was not observed in fibrinogen (2.50%, 95% CI: −0.78%–5.77%, P = 0.135). Sensitivity analysis and publication bias test confirmed the stability of the results. Conclusion Circulating fibrinogen and IL-6 significantly increased with exposure to PM2.5, may serve as promising biomarkers for PM2.5-related adverse effects.