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DNA methylation signatures in airway cells from adult children of asthmatic mothers reflect subtypes of severe asthma (DNA methylation)

ABSTRACT: Maternal asthma (MA) is among the most consistent risk factors for asthma in her children. Possible mechanisms for this observation are epigenetic modifications in utero that have lasting effects on developmental programs in children of mothers with asthma. To test this hypothesis, we performed differential DNA methylation analyses of 398,186 individual CpG sites in primary bronchial epithelial cells (BECs) from 42 non-asthma controls and 88 asthma cases, including 56 without MA (NMA) and 32 with MA. We used weighted gene co-expression network analysis (WGCNA) of 69 and 554 differentially methylated CpGs (DMCs) that were specific to NMA or MA cases, respectively, compared to controls. WGCNA grouped 66 NMA-DMCs and 203 MA-DMCs into two and five co-methylation modules, respectively. The eigenvector of one MA-associated module (turquoise) was uniquely correlated with 85 genes expressed in BECs and enriched for 36 pathways, 16 of which discriminated between NMA and MA using machine learning. Genes in all 16 pathways were decreased in MA compared to NMA cases (P=7.1x10-3), a finding that replicated in nasal epithelial cells from an independent cohort (P=0.02). Functional interpretation of these pathways suggested impaired T cell signaling and responses to viral and bacterial pathogens. The MA-associated turquoise module eigenvector was additionally correlated with clinical features of severe asthma and reflective of type 2 (T2)-low asthma (i.e., low total serum IgE, fractional exhaled nitric oxide, and eosinophilia). Overall, these data suggest that maternal asthma alters diverse epigenetically-mediated pathways that lead to distinct subtypes of severe asthma in adults including hard-to-treat T2-low asthma.

ORGANISM(S): Homo sapiens

PROVIDER: GSE201872 | GEO | 2022/05/02

REPOSITORIES: GEO

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Project description:Background: Asthma, a complex chronic lung disease affecting the airways, has striking disparities across ancestral groups, but the molecular underpinning of these differences is poorly understood and minimally studied. A major goal of the Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to understand multi-omics signatures of asthma risk in the nasal epithelium focusing on populations of African ancestry. Methods: RNASeq data were generated from nasal epithelium in subjects recruited from up to 7 sites (Baltimore, Washington DC, Chicago, Denver, Salvador Brazil, Barbados, and Nigeria). Current asthma cases (N=253) were compared to never-asthma controls (N=283) to identify differentially expressed genes (DEGs; q <0.05). Network analyses were performed with Ingenuity Pathway Analysis (IPA; DEGs with q<0.05) and weighted gene co-expression network analysis (WGCNA; DEGs with q<0.15). All models were fully adjusted for ancestry, sampling site, and appropriate latent factors. Findings: CAAPA represents diversity across the African Diaspora with a wide range of continental African ancestry (9%-100%). We identified 389 DEGs; the top DEG, FN1, was downregulated in asthma cases (q=3.26x10-9) and encodes fibronectin which plays a role in wound healing. Others in the top 10 DEGs have high relevance for asthma: SNTG2 (q = 1.12x10-4) is the target of multiple miRNAs related to asthma; PPP1R9A expression (q=7.60x10-5) was previously determined to be influenced by IL-13 in mouse lung; and SPTBN1 (q=1.12x10-4) plays a key role in mediating TGFβ signaling. IPA revealed networks with upstream regulators relevant for immune response (IL4; p=7.25x10-10 and TGFβ1; p=5.47x10-8) and drug response (dexamethasone; p=4.31x10-10 and fluticasone propionate; p=9.42x10-8). Among asthma cases, genes regulated by dexamethasone and fluticasone propionate were not associated with inhaled corticosteroid medication use. The top three WGCNA modules implicate networks related to immune response (CEACAM5; p=9.62x10-16 and CPA3; p=2.39x10-14) and wound healing (FN1; p=7.63x10-9). Multi-omic analysis identified FKBP5 as a key contributor to asthma risk, whereby the association between nasal epithelium gene expression is mediated through methylation and is associated with increased use of inhaled corticosteroids. FKBP5 is a co-chaperone of glucocorticoid receptor signaling and known to be involved in drug response in asthma. Interpretation: Our analyses reveal genes and networks in asthma that are differentially expressed in nasal epithelium of asthma cases of African ancestry in CAAPA. Importantly, this work reveals molecular dysregulation on three axes – increased Th2 inflammation, decreased capacity for wound healing, and impaired drug response – that may play a critical role in asthma within the African Diaspora.

Project description:Background: Asthma, a complex chronic lung disease affecting the airways, has striking disparities across ancestral groups, but the molecular underpinning of these differences is poorly understood and minimally studied. A major goal of the Consortium on Asthma among African-ancestry Populations in the Americas (CAAPA) is to understand multi-omics signatures of asthma risk in the nasal epithelium focusing on populations of African ancestry. Methods: DNA methylation (DNAm) quantification was performed using Illumina’s Infinium MethylationEPIC array® using genomic DNA from nasal airway epithelial cells collected across the 4 US recruitment sites (Baltimore, Chicago, Denver, and Washington DC) for 331 subjects (N=149 asthma cases, N= 182 never asthmatic controls). We performed association analysis to identify eQTMs (CpG-gene associations) for DEGs limiting to CpGs ≤5kb from the transcription start site or within enhancer regions identified through promoter-capture HiC in bronchial epithelial cells. CpGs from significant eQTMs (p<0.05) were tested for differential methylation by asthma (DMCs) to assess the relative contribution of expression and methylation in asthma risk. All models were fully adjusted for ancestry, sampling site, and appropriate latent factors. Findings: Multi-omic analysis identified FKBP5 as a key contributor to asthma risk, where the association between nasal epithelium gene expression is likely regulated by methylation and is associated with increased use of inhaled corticosteroids. FKBP5 is a co-chaperone of glucocorticoid receptor signaling and known to be involved in drug response in asthma. Interpretation: Our analyses reveal genes and networks in asthma that are differentially expressed in nasal epithelium of current asthma cases of African ancestry in CAAPA. Importantly, this work reveals molecular dysregulation on three axes – increased Th2 inflammation, decreased capacity for wound healing, and impaired drug response – that may play a critical role in asthma within the African Diaspora.