The relationship between PM2.5 and inflammation biomarkers in mice: a systematic review and meta-analysis

INTRODUCTION: Numerous studies have reported PM2.5 effects on lung and inflammation activation in mice with different models to treat mice. A proper mice model plays a key role in saving experimental time and cost. Nonetheless, the systematic review about this has not existed. EVIDENCE ACQUISITON: Systematic searches were conducted in four common English and Chinese electronic databases (i.e., PubMed, Embase, Web of Science, Clinical Trial, CNKI, VIP, Wan Fang, Chinese BioMedical). A meta- analysis including 19 studies was performed using R software to estimate the relationship between PM2.5 and inflammation markers and investigate the effect of modeling method on inflammation markers. Publication bias and heterogeneity of samples were tested using a funnel plot. Studies were analyzed using either a random-effect model or a fixed-effect model. EVIDENCE SYNTHESIS: The search yielded 19 studies suitable for meta-analysis during the period from their initiation to September 1st, 2020. PM2.5 could increase IL-6, TNF-alpha, IL-1 beta, IL-4, and IL-8 levels in mice suffering PM2.5. Compared with inhalation group (SMD=2.16., 95% CI: 0.86-3.46), there was a higher level of IL-6 in serum in instillation group (SMD=3.06, 95% CI: 1.52-4.60) (P<0.01). By Contrast with inhalation group (SMD=3.80. 95% CI: 1.55-6.05), there was a lower level of TNF-alpha in serum in instillation group (SMD=2.78, 95% CI: 1.77-3.78) (P<0.01). Compared with inhalation group (SMD 3.06, 95% CI: 0.94-5.17), there was a higher level of IL-1 beta in scrum in instillation group (SMD=13.98, 95% CI: -9.45-37.40) (P<0.01). CONCLUSIONS: Intratracheal instillation of PM2.5 took a shorter time to make model of PM2.5 injury on lung and gave an alternative for investigation of different inflammation biomarkers with different model method.