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Background: Little is known about the association of newborn DNA methylation (DNAm) with asthma acquisition across adolescence and early adult life. Objective: We aim to identify epigenetic biomarkers in newborns for asthma acquisition during adolescence or young adulthood. Methods: The Isle of Wight Birth Cohort (IOWBC) (n = 1456) data at ages 10, 18 and 26 years were assessed. To screen cytosine‐phosphate‐guanine site (CpGs) potentially associated with asthma acquisition, at the genome scale, we examined differentially methylated regions (DMR) using dmrff R package and individual CpG sites using linear regression on such associations. For CpGs that passed screening, we examined their enrichment in biological pathways using their mapping genes and tested their associations with asthma acquisitions using logistic regressions. Findings in IOWBC were tested in an independent cohort, the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort. Results: In total, 2636 unique CpGs passed screening, based on which we identified one biological pathway linked to asthma acquisition during adolescence in females (FDR adjusted p‐value =.003 in IOWBC). Via logistic regressions, for females, four CpGs were shown to be associated with asthma acquisition during adolescence, and another four CpGs with asthma acquisition in young adulthood (FDR adjusted p‐value <.05 in IOWBC) and these eight CpGs were replicated in ALSPAC (all p‐values <.05). DNAm at all the identified CpGs was shown to be temporally consistent, and at six of the CpGs was associated with expressions of adjacent or mapping genes in females (all p‐values <.05). For males, 622 CpGs were identified in IOWBC (FDR = 0.01), but these were not tested in ALSPAC due to small sample sizes. Conclusion and clinical relevance: Eight CpGs on LHX5, IL22RA2, SOX11, CBX4, ACPT, CFAP46, MUC4, and ATP1B2 genes have the potential to serve as candidate epigenetic biomarkers in newborns for asthma acquisition in females during adolescence or young adulthood. [ABSTRACT FROM AUTHOR]

Summary: Background: Underlying biological mechanisms involved in sex differences in asthma status changes from pre‐ to post‐adolescence are unclear. DNA methylation (DNAm) has been shown to be associated with the risk of asthma. Objective: We hypothesized that asthma acquisition from pre‐ to post‐adolescence was associated with changes in DNAm during this period at asthma‐associated cytosine‐phosphate‐guanine (CpG) sites and such an association was sex‐specific. Methods: Subjects from the Isle of Wight birth cohort (IOWBC) with DNAm in blood at ages 10 and 18 years (n = 124 females, 151 males) were studied. Using a training‐testing approach, epigenome‐wide CpGs associated with asthma were identified. Logistic regression was used to examine sex‐specific associations of DNAm changes with asthma acquisition between ages 10 and 18 at asthma‐associated CpGs. The ALSPAC birth cohort was used for independent replication. To assess functional relevance of identified CpGs, association of DNAm with gene expression in blood was assessed. Results: We identified 535 CpGs potentially associated with asthma. Significant interaction effects of DNAm changes and sex on asthma acquisition in adolescence were found at 13 of the 535 CpGs in IOWBC (P‐values <1.0 × 10−3). In the replication cohort, consistent interaction effects were observed at 10 of the 13 CpGs. At 7 of these 10 CpGs, opposite DNAm changes across adolescence were observed between sexes in both cohorts. In both cohorts, cg20891917, located on IFRD1 linked to asthma, shows strong sex‐specific effects on asthma transition (P‐values <.01 in both cohorts). Conclusion and clinical relevance: Gender reversal in asthma acquisition is associated with opposite changes in DNAm (males vs females) from pre‐ to post‐adolescence at asthma‐associated CpGs. These CpGs are potential biomarkers of sex‐specific asthma acquisition in adolescence. [ABSTRACT FROM AUTHOR]

Background: The presence of allergic sensitization has a major influence on the development and course of common childhood conditions such as asthma and rhinitis. The etiology of allergic sensitization is poorly understood, and its underlying biological mechanisms are not well established. Several studies showed that DNA methylation (DNAm) at some CpGs is associated with allergic sensitization. However, no studies have focused on the critical adolescence period. Methods: We assessed the association of pre‐ and postadolescence genome‐wide DNAm with allergic sensitization against indoor, outdoor and food allergens, using linear mixed models. We hypothesized that DNAm is associated with sensitization in general, and with poly‐sensitization status, and these associations are age‐ and gender‐specific. We tested these hypotheses in the IoW cohort (n = 376) and examined the findings in the BAMSE cohort (n = 267). Results: Via linear mixed models, we identified 35 CpGs in IoW associated with allergic sensitization (at false discovery rate of 0.05), of which 33 were available in BAMSE and replicated with respect to the direction of associations with allergic sensitization. At the 35 CpGs except for cg19210306 on C13orf27, a reduction in methylation among atopic subjects was observed, most notably for cg21220721 and cg11699125 (ACOT7). DNAm at cg10159529 was strongly correlated with expression of IL5RA in peripheral blood (P‐value = 6.76 × 10−20). Three CpGs (cg14121142, cg23842695, and cg26496795) were identified in IoW with age‐specific association between DNAm and allergic sensitization. Conclusion: In adolescence, the status of allergic sensitization was associated with DNAm differentiation and at some CpGs the association is likely to be age‐specific. [ABSTRACT FROM AUTHOR]

Summary: Background: Understanding of adolescent-onset asthma remains limited. We sought to characterise this state and identify associated factors within a longitudinal birth cohort study. Methods: The Isle of Wight Whole Population Birth Cohort was recruited in 1989 (N =1456) and characterised at 1, 2, 4, 10 and 18-years. “Adolescent-onset asthma” was defined as asthma at age 18 without prior history of asthma, “persistent-adolescent asthma” as asthma at both 10 and 18 and “never-asthma” as those without asthma at any assessment. Results: Adolescent-onset asthma accounted for 28.3% of asthma at 18-years and was of similar severity to persistent-adolescent asthma. Adolescent-onset asthmatics showed elevated bronchial hyper-responsiveness (BHR) and atopy at 10 and 18 years. BHR in this group at 10 was intermediate to that of never-asthmatics and persistent-adolescent asthma. By 18 their BHR, bronchodilator reversibility and sputum eosinophilia was greater than never-asthmatics and comparable to persistent-adolescent asthma. At 10, males who later developed adolescent-onset asthma had reduced FEV1 and FEF25–75, while females had normal lung function but then developed impaired FEV1 and FEF25–75 in parallel with adolescent asthma. Factors independently associated with adolescent-onset asthma included atopy at 10 (OR=2.35; 95% CI=1.08–5.09), BHR at 10 (3.42; 1.55–7.59), rhinitis at 10 (2.35; 1.11–5.01) and paracetamol use at 18-years (1.10; 1.01–1.19). Conclusions: Adolescent-onset asthma is associated with significant morbidity. Predisposing factors are atopy, rhinitis and BHR at age 10 while adolescent paracetamol use is also associated with this state. Awareness of potentially modifiable influences may offer avenues for mitigating this disease state. [ABSTRACT FROM AUTHOR]

The role of epigenetics in the pathogenesis of asthma acquisition in adolescence and post-adolescence has been unknown. We carried out a longitudinal epigenome-wide association study, using data from the Isle of Wight Birth Cohort (IOWBC). To improve statistical power, we first screened CpGs based on associations of DNA methylation (DNAm) at an age of 10 years (pre-adolescence) with asthma acquisition at 10–18 years (during adolescence). A logistic regression with repeated measures was applied to CpGs that passed screening to examine the associations of pre-adolescence DNAm with asthma acquisition from 10–18 years and 18–26 years, with an interaction term to evaluate transition period specificity. Findings were further tested in an independent birth cohort, ALSPAC. In total, 205 CpGs (with 150 being females) showed associations with asthma acquisition (main or interaction effects) at FDR = 0.05 in IOWBC, of which 112 (90 being females) showed consistent associations in the ALSPAC. Genes that the identified CpGs were mapped to, e.g., AKAP1 and ENO1, have been shown to be associated with the risk of asthma. Our findings indicated that DNAm at specific CpGs was associated with asthma acquisition. CpGs showing such associations were likely to be different between males and females and, at certain CpGs, were unique to a specific transition period. [ABSTRACT FROM AUTHOR]