Correlation Between mRNA Expression of Activated Eosinophils and Air Pollutant Exposure in Patients With Asthma

Abstract

Background: Eosinophil activation is associated with asthma. Whether air pollution affects the activation of blood eosinophils in patients with asthma remains unknown. In this study, we investigated the correlation between transcriptional activity in eosinophils and air pollutant exposure in patients receiving different levels of Global Initiative for Asthma (GINA) treatment.

Methods: We evaluated the expression levels of activation- and function-related genes in eosinophils from patients with GINA 4 or 5 (n = 20), those with GINA 3 (n = 12), and normal individuals (n = 7); the eosinophils were activated with interleukin (IL)-5 or IL-17. A land use regression model was used to estimate air pollutant exposure. The correlations between mRNA expression, lung function, and air pollutant exposure were investigated.

Results: The expression levels of TGFB1, IL7R, and TLR3 were significantly higher for patients with GINA 4 or 5 than for those with GINA 3 or normal individuals. The expression of certain genes, particularly in IL-17-activated eosinophils, was correlated with lung function decline in patients with GINA 4 or 5. For patients with GINA 4 or 5, NO₂ exposure was correlated with upregulated TGFB1 expression in IL-5-activated eosinophils. For patients with GINA 3, O₃ exposure was correlated with upregulated CCR5, IL5RA, IL7R, and TGFB1 expression in IL-17-activated eosinophils and upregulated IL7R expression in IL-5-activated eosinophils.

Conclusion: Patients with GINA 4 or 5 may exhibit elevated transcriptional activity in eosinophils; this elevation is correlated with lung function decline. Air pollution may affect eosinophil mRNA expression in patients with asthma.

Keywords: air pollution; asthma; eosinophil; mRNA.