Project description:Background: Asthma is highly heterogeneous and severity evaluation is key to asthma management. DNA methylation (DNAm) contributes to asthma pathogenesis. This study aimed to identify nasal epithelial DNAm differences between severe and non-severe asthmatic children and evaluate the impact of environmental exposures. Methods: Thirty-three non-severe and 22 severe asthmatic African-American children were included in an epigenome-wide association study. Genome-wide nasal epithelial DNAm and gene expression were measured. CpG sites associated with asthma severity and environmental exposures and predictive of severe asthma were identified. DNAm was correlated with gene expression. Enrichment for transcription factor (TF) binding sites or histone modifications surrounding DNAm differences were determined. Results: We identified 816 differentially methylated CpG positions (DMPs) and 10 differentially methylated regions (DMRs) associated with asthma severity. Three DMPs exhibited discriminatory ability for severe asthma. Intriguingly, six DMPs were simultaneously associated with asthma, allergic asthma, total IgE, environmental IgE, and FeNO in an independent cohort of children. 27 DMPs were associated with traffic-related air pollution or secondhand smoke. DNAm at 22 DMPs were altered by diesel particles or allergen in human bronchial epithelial cells. DNAm levels at 39 DMPs were correlated with mRNA expression. Proximal to 816 DMPs, three histone marks and several TFs involved in asthma pathogenesis were enriched. Conclusions: Significant differences in nasal epithelial DNAm were observed between non-severe and severe asthma in African-American children, a subset of which may be useful to predict disease severity. These CpG sites are subject to the influences of environmental exposures and may regulate gene expression.
Project description:Management of severe asthma remains a challenge despite treatment with glucocorticosteroid therapy. The majority of studies investigating disease mechanisms in treatment-resistant severe asthma have previously focused on the large central airways, with very few utilizing transcriptomic approaches. The small peripheral airways, which comprise the majority of the airway surface area, remain an unexplored area in severe asthma and were targeted for global epithelial gene expression profiling in this study.
Project description:In this study we explore the underlying differences in bronchial epithelial cells from asthma patinets compared to healthy controls. In addition we also explore the differential gene expression of severe asthma patients compared to mild and moderate asthma patients to determine if there are genes that lead to severity of the disease
Project description:Severe asthma is a clinically and physiologically heterogeneous disease. Benralizumab is a monoclonal antibody which binds the alpha chain of the interleukin-5 receptor and used for severe eosinophilic asthma worldwide. However, not all eosinophilic asthma patients will benefit from benralizumab due to heterogeneity of this disease. Therefore, we performed comprehensive gene expression analysis of whole blood cells that examine severe asthma disease heterogeneity in response to benralizumab. This study is the first to perform comprehensive transcriptome analysis of whole blood cells to identify transcriptomic endotypes of severe asthma clusters that correlate with benralizumab response. The identified transcriptomic endotypes of severe asthma clusters are associated with gene signatures of eosinophils and neutrophilis.
Project description:Polymorphisms in the interleukin-4 receptor α chain (IL-4Rα) have been linked to asthma incidence and severity, but a causal relationship has remained uncertain. In particular, a glutamine to arginine substitution at position 576 (Q576R) of IL-4Rα has been associated with severe asthma, especially in African Americans. We show that mice carrying the Q576R polymorphism exhibited intense allergen-induced airway inflammation and remodeling. The Q576R polymorphism did not affect proximal signal transducer and activator of transcription (STAT) 6 activation, but synergized with STAT6 in a gene target– and tissue-specific manner to mediate heightened expression of a subset of IL-4– and IL-13–responsive genes involved in allergic inflammation. Our findings indicate that the Q576R polymorphism directly promotes asthma in carrier populations by selectively augmenting IL-4Rα–dependent signaling. Keywords: Cell population analysis
Project description:Polymorphisms in the interleukin-4 receptor ? chain (IL-4R?) have been linked to asthma incidence and severity, but a causal relationship has remained uncertain. In particular, a glutamine to arginine substitution at position 576 (Q576R) of IL-4R? has been associated with severe asthma, especially in African Americans. We show that mice carrying the Q576R polymorphism exhibited intense allergen-induced airway inflammation and remodeling. The Q576R polymorphism did not affect proximal signal transducer and activator of transcription (STAT) 6 activation, but synergized with STAT6 in a gene target– and tissue-specific manner to mediate heightened expression of a subset of IL-4– and IL-13–responsive genes involved in allergic inflammation. Our findings indicate that the Q576R polymorphism directly promotes asthma in carrier populations by selectively augmenting IL-4R?–dependent signaling. Keywords: Cell population analysis To determine potential mechanisms underlying the trophic effects of the R576 allele on airway inflammation and remodeling, we first compared the gene expression profile in the lungs of doxycycline-treated B6.129Il4raR576/R576/IL-13tg mice versus B6.129Il4raR576/R576 littermates that lacked the IL-13tg (n = 11 and 5, respectively). We similarly compared the gene expression profile in the lungs of doxycycline-treated B6.Il4raQ576/Q576/IL-13tg mice versus tg-negative littermates (n = 8 and 5, respectively). Lastly, we directly compared the gene expression profiles in the doxycycline-treated B6.129Il4raR576/R576/IL-13tg versus B6.Il4raQ576/Q576/IL-13tg mice.
Project description:Sputum airway cells transcriptome from 19 asthmatics from the Severe Asthma Research Program at baseline and 6-8 weeks follow-up after a 40mg dose of intramuscular corticosteroid triamcinolone acetonide.
Project description:By incompletely understood mechanisms, type 2 (T2) inflammation present in the airways of severe asthmatics drives the formation of pathologic mucus which leads to airway mucus plugging. Here we investigate the molecular role and clinical significance of intelectin-1 (ITLN-1) in the development of pathologic airway mucus in asthma. Through analyses of human airway epithelial cells we find that ITLN1 gene expression is highly induced by interleukin-13 (IL-13) in a subset of metaplastic MUC5AC+ mucus secretory cells, and that ITLN-1 protein is a secreted component of IL-13-induced mucus. Additionally, we find ITLN-1 protein binds the C-terminus of the MUC5AC mucin and that its deletion in airway epithelial cells partially reverses IL-13-induced mucostasis. Through analysis of nasal airway epithelial brushings, we find that ITLN1 is highly expressed in T2-high asthmatics, when compared to T2-low children. Furthermore, we demonstrate that ITLN1 gene expression is significantly reduced and ITLN-1 protein expression is lost through a common genetic variant that is associated with protection from the formation of mucus plugs in T2-high asthma. This work identifies one of the first biomarkers and targetable pathways for the treatment of mucus obstruction in asthma.