Nasal cell DNA methylation, inflammation, lung function and wheezing in children with asthma

Aims: DNA methylation is increasingly proposed as a mechanism for underlying asthma-related inflammation. However, epigenetic studies are constrained by uncertainties on whether samples that can be easily collected in human individuals can provide informative results. Methods: Two nasal cell DNA samples were collected on different days by nasal brushings from 35 asthmatic children aged between 8 and 11 years old. We correlated DNA methylation of IL-6, iNOS, Alu and LINE-1 with fractional exhaled nitric oxide, forced expiratory volume in 1 s and wheezing. Results: Fractional exhaled nitric oxide increased in association with lower promoter methylation of both IL-6 (+29.0%; p = 0.004) and iNOS (+41.0%; p = 0.002). Lower IL-6 methylation was nonsignificantly associated with wheezing during the week of the study (odds ratio = 2.3; p = 0.063). Conclusion: Our findings support the use of nasal cell DNA for human epigenetic studies of asthma.