Interaction Between Early-Life Pet Exposure and Methylation Pattern of ADAM33 on Allergic Rhinitis among Children Aged 3-6 Years in China

Background Recent research has pointed out the important roles of epigenetic modifications in the development and persistence of allergic rhinitis (AR), especially in relation to DNA methylation of disease-associated genes. We investigated whether AR susceptibility genes were epigenetically regulated, and whether methylation modulation of these genes in response to early-life environment could be a molecular mechanism underlying the risk for AR onset in a cohort of children aged 3-6 years in China. Methods Peripheral blood mononuclear cell (PBMC) samples were collected from 130 children patients, aged 3-6 years and diagnosed with AR; and 154 matched controls to detect promoter methylation in 25 AR susceptibility genes with the MethylTarget approach. Methylation levels were compared for each CpG site, each amplified region, and each gene. In addition, the relationship among DNA methylation, early-life environmental risk factors and AR onset were assessed. Results Maternal allergic history (P = 0.0390) and pet exposure (P = 0.0339) were significantly associated with increased AR risk. Differential methylation analyses were successfully performed for 507 CpG sites, 34 amplified regions and 17 genes and significant hypomethylation was observed in the promoter region of ADAM33 in AR patients [multiple test-corrected (FDR) P-value < 0.05]. Spearman correlation analysis revealed that the hypomethylation of ADAM33 was significantly associated with higher eosinophil counts (Spearman's rho: - 0.187, P-value = 0.037). According to the results of the multiple regression analysis, after adjusting for cofounders, the interaction of early-life pet exposure with methylation level of ADAM33 increased the risk for AR onset 1.423 times more in children (95% CI = 0.0290-4.109, P-value = 0.005). Conclusion This study provides evidence that early-life pet exposure and low methylation level of ADAM33 increase AR risk in children, and the interaction between pet exposure and methylation level of ADAM33 may play an important role in the development of AR.