Abstract
BackgroundEvidences that oxidative stress plays a role in the associations between outdoor air pollution and asthma are growing. We aimed to study the role of plasma fluorescent oxidation products levels (FlOPs; an oxidative stress-related biomarker), as potential mediators, in the associations between outdoor air pollution and persistent asthma.MethodsAnalyses were conducted in 204 adult asthmatics followed up in the French case-control and family study on asthma (EGEA; the Epidemiological study of the Genetic and Environmental factors of Asthma). Persistent asthma was defined as having current asthma at EGEA2 (baseline, 2003–2007) and EGEA3 (follow-up, 2011–2013). Exposures to nitrogen dioxide, nitrogen oxides, road traffic, particulate matter with a diameter ≤ 10 μm (PM10) and ≤ 2.5 μm were estimated by ESCAPE models (2009–2010), and ozone (O3) by IFEN models (2004). We used a mediation analysis to assess the mediated effect by FlOPs levels and the interaction between FlOPs levels and air pollution.ResultsFlOPs levels increased with PM10 and O3 (adjusted β = 0.04 (95%CI 0.001–0.08), aβ = 0.04 (95%CI 0.009–0.07) per 10 μg/m3, respectively), and the risk of persistent asthma increased with FlOPs levels (aOR = 1.81 (95%CI 1.08–3.02)). The risk of persistent asthma decreased with exposures to NO2, NOx and PM2.5 (aOR ranging from 0.62 to 0.94), and increased with exposures to PM10, O3, O3-summer and road traffic, the greater effect being observed for O3 (aOR = 1.78, 95% CI 0.73–4.37, per 10 μg/m3). Using mediation analysis, we observed a positive total effect (aOR = 2.16, 95%CI 0.70–11.9), a positive direct effect of O3 on persistent asthma (OR = 1.68, 95%CI 0.57–7.25), and a positive indirect effect mediated by FIOPs levels (aOR = 1.28 (95%CI 1.01–2.29)) accounting for 41% of the total effect.ConclusionsOur results add insights on the role of oxidative stress in the association between air pollution and persistent asthma.
Highlights
Evidences that oxidative stress plays a role in the associations between outdoor air pollution and asthma are growing
Associations between outdoor air pollution, plasma fluorescent oxidation products levels (FlOPs) levels and persistent asthma Among all pollutants studied, plasma FlOPs levels increased by 1 RFU/mL with PM10 and O3 exposures (adjusted (a)β = 0.04, 95% confidence interval (CI) 0.001–0.08, p = 0.03 and aβ = 0.04, 95% CI 0.009–0.07, p = 0.02 for an increase of 10 μg/m3 of O3 and PM10, respectively, Table 2)
The association between PM10 and plasma FlOPs levels did not remain significant with back-extrapolated data
Summary
Evidences that oxidative stress plays a role in the associations between outdoor air pollution and asthma are growing. We aimed to study the role of plasma fluorescent oxidation products levels (FlOPs; an oxidative stress-related biomarker), as potential mediators, in the associations between outdoor air pollution and persistent asthma. Among adults from the Epidemiological study of the Genetic and Environmental factors of Asthma (EGEA), we recently reported higher plasma FlOPs levels significantly associated with asthma attacks, poor asthma control and poor lung function [11]. In the EGEA study, occupational exposure to irritant cleaning products and to low molecular weight agents, especially highly reactive chemicals, were significantly and positively associated with higher plasma FlOPs levels in men, and an association was suggested for irritant cleaning products in women [13]. The role of plasma FlOPs levels in the association between outdoor air pollution and asthma has never been studied
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