Developmental exposure to air pollution particulates increases asthma severity, alters the RNA transcriptome, and DNA methylation in female adult progeny [WGMS]

Maternal exposure to particulate air pollution increases the incidence and severity of asthma in offspring, yet the mechanisms for this are unclear. Known susceptibility loci are a minor component of this effect. We interrogate a mouse allergic airway disease model to assess epigenetic associations between maternal air pollution exposure and asthma-like responses in offspring. Maternal air pollution exposure increased allergic airway disease severity in adult offspring associated with a suppressed transcriptomic response to allergen. Control progeny showed differential expression of 2842 genes across several important pathways, including the SMAD and TGFßR pathways, whilst air pollutant progeny showed an 80% reduction in differentially expressed genes and abrogation of many pathway associations. Whole genome CpG methylome analysis following allergen challenge detected differential methylation regions across the genome. Approximately 20% of differentially expressed genes were associated with differential methylation. Differentially methylated regions were markedly reduced in offspring of air pollution exposed mothers, and this was most evident in intronic regions and some transposable element classes. This study shows that allergic airways disease in adult offspring of PM2.5 exposed mothers had a markedly repressed transcriptomic response, a proportion of which was associated with identifiable changes in the lung's methylome. The results point to an epigenetic contribution to the severity of asthma in offspring of mothers exposed to particulate air pollution. Overall design: Lung homogenates of 13 week old female offspring (+/- OVA challenge) of (+/-) PM2.5 exposed dams examined by RNA-seq and WGMS