Human rhinovirus infection causes different DNA methylation changes in nasal epithelial cells from healthy and asthmatic subjects. Homo sapiens

Background: Mechanisms underlying the development of virus-induced asthma exacerbations remain unclear. Objective: To investigate if epigenetic mechanisms could be involved in virus-induced asthma exacerbations, we undertook DNA methylation profiling in asthmatic and healthy nasal epithelial cells (NECs) during Human Rhinovirus (HRV) infection in vitro. Methods: Global and loci-specific methylation profiles were determined via Alu element and Infinium Human Methylation 450K microarray respectively. Principal components analysis identified the genomic loci influenced the most by disease-status and infection. Real-time PCR and pyrosequencing was used to confirm gene expression and DNA methylation respectively. Results: Global methylation was increased in Asthmatics during infection. Disease status and virus infection influenced the methylation of 389 loci. Healthy and asthmatic NECs were characterized predominately by methylation profiles and patterns in loci that were not influenced by virus infection. However, both groups also exhibited distinct DNA methylation profiles in response to infection. Despite these differences, we found that the methylation of small nucleolar RNA, H/ACA box 12 (SNORA12) was common during infection. Further analysis indicated a relationship existed between SNORA12 DNA methylation and gene expression in response to infection. Conclusions: Findings from our study indicate that in addition to the well described phenotypic and genomic differences, the airway epithelium of asthmatics is characterized by a distinct methylome and that epigenetic mechanism may contribute to the development of virus-induced asthma exacerbations. Overall design: Bisulphite converted DNA from matched mock and human rhinovirus-16 infected nasal epithelial cells from Healthy (n=3) and Asthmatics (n=6) adults were hybridized to the Illumina DNA methylation 450K Bead Array.