Chromosome 17q12–21 remains the most highly replicated and significant asthma locus. Genotypes in the core region defined by the first genome-wide association study correlate with expression of 2 genes, ORM1-like 3 (ORMDL3) and gasdermin B (GSDMB), making these prime candidate asthma genes, although recent studies have implicated gasdermin A (GSDMA) distal to and post-GPI attachment to proteins 3 (PGAP3) proximal to the core region as independent loci. We review 10 years of studies on the 17q12–21 locus and suggest that genotype-specific risks for asthma at the proximal and distal loci are not specific to early-onset asthma and mediated by PGAP3, ORMDL3, and/or GSDMA expression. We propose that the weak and inconsistent associations of 17q single nucleotide polymorphisms with asthma in African Americans is due to the high frequency of some 17q alleles, the breakdown of linkage disequilibrium on African-derived chromosomes, and possibly different early-life asthma endotypes in these children. Finally, the inconsistent association between asthma and gene expression levels in blood or lung cells from older children and adults suggests that genotype effects may mediate asthma risk or protection during critical developmental windows and/or in response to relevant exposures in early life. Thus studies of young children and ethnically diverse populations are required to fully understand the relationship between genotype and asthma phenotype and the gene regulatory architecture at this locus. (J Allergy Clin Immunol 2018;142:749–64.)

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Idiopathic pulmonary fibrosis (IPF) is the most common and the most aggressive fibrosing interstitial lung disease (ILD). Despite recent promising clinical trials, IPF remains incurable and largely untreatable. Genetic studies have identified several risk loci for both sporadic and familial forms of IPF. A single variant upstream of MUC5B is predicted to account for more than 30% of all IPF risk. This variant, rs35705950, is associated with expression of MUC5B in healthy lung tissue. However, the mechanism underlying the relationship between rs35705950 and MUC5B expression remains unclear.The first goal of my thesis research was to determine whether rs35705950 is also a risk factor for other forms of ILD. Genomic DNA from individuals with IPF, HP, COPD, iNSIP, and RB-ILD was obtained and genotyped for the common MUC5B promoter variant. In these populations the risk allele was associated with IPF and iNSIP which suggested a potential shared disease mechanism. Additionally, I showed that in the IPF and control populations rs35705950 is associated with lung MUC5B expression.The second goal of my thesis research was to investigate MUC5B promoter DNA methylation which has previously been shown to play a role in MUC5B expression.Methylation analysis of the 4KB region upstream of MUC5B identified two differentially methylated regions (DMRs) associated with IPF, one DMR associated with MUC5B iv expression, and one DMR associated with rs35705950. The IPF, MUC5B expression, and rs35705950 associated DMRs are all differentially methylated at a cluster of 11 CpG motifs. overlapping DMR, including the motif disrupted by rs35705950. These findings suggest that DNA methylation may play a role in MUC5B gene regulation and IPF risk.Next, I used cross species analysis to identify highly conserved domains within the overlapping DMR. Evolutionary conservation indicated selective pressures to maintain sequences overtime and suggests biological importance. The overlapping DMR contains a highly conserved binding motif for FOXA2, a transcription factor. Further analysis using ChIP-qPCR, reporter constructs, and siRNA, established a role for FOXA2 in regulation of MUC5B expression in lung tissue. Additionally, siRNA knock down identified 3 other transcription factors which are associated with MUC5B expression; STAT3, HOXA9 and ZBTB7A. These transcriptional regulators provide insight into possible therapeutic intervention for MUC5B dysregulation and IPF.The form and content of this abstract are approved. I recommend its publication.

There is a life-long relationship between rhinovirus (RV) infection and the development and clinical manifestations of asthma. In this study we demonstrate that cultured primary bronchial epithelial cells from adults with asthma (n = 9) show different transcriptional and chromatin responses to RV infection compared to those without asthma (n = 9). Both the number and magnitude of transcriptional and chromatin responses to RV were muted in cells from asthma cases compared to controls. Pathway analysis of the transcriptionally responsive genes revealed enrichments of apoptotic pathways in controls but inflammatory pathways in asthma cases. Using promoter capture Hi-C we tethered regions of RV-responsive chromatin to RV-responsive genes and showed enrichment of these regions and genes at asthma GWAS loci. Taken together, our studies indicate a delayed or prolonged inflammatory state in cells from asthma cases and highlight genes that may contribute to genetic risk for asthma.

Background Genome-wide association studies (GWASs) have identified thousands of variants associated with asthma and other complex diseases. However, the functional effects of most of these variants are unknown. Moreover, GWASs do not provide context-specific information on cell types or environmental factors that affect specific disease risks and outcomes. To address these limitations, we used an upper airway epithelial cell (AEC) culture model to assess transcriptional and epigenetic responses to rhinovirus (RV), an asthma-promoting pathogen, and provide context-specific functional annotations to variants discovered in GWASs of asthma. Methods Genome-wide genetic, gene expression, and DNA methylation data in vehicle- and RV-treated upper AECs were collected from 104 individuals who had a diagnosis of airway disease (n=66) or were healthy participants (n=38). We mapped cis expression and methylation quantitative trait loci (cis-eQTLs and cis-meQTLs, respectively) in each treatment condition (RV and vehicle) in AECs from these individuals. A Bayesian test for colocalization between AEC molecular QTLs and adult onset asthma and childhood onset asthma GWAS SNPs, and a multi-ethnic GWAS of asthma, was used to assign the function to variants associated with asthma. We used Mendelian randomization to demonstrate DNA methylation effects on gene expression at asthma colocalized loci. Results Asthma and allergic disease-associated GWAS SNPs were specifically enriched among molecular QTLs in AECs, but not in GWASs from non-immune diseases, and in AEC eQTLs, but not among eQTLs from other tissues. Colocalization analyses of AEC QTLs with asthma GWAS variants revealed potential molecular mechanisms of asthma, including QTLs at the TSLP locus that were common to both the RV and vehicle treatments and to both childhood onset and adult onset asthma, as well as QTLs at the 17q12-21 asthma locus that were specific to RV exposure and childhood onset asthma, consistent with clinical and epidemiological studies of these loci. Conclusions This study provides evidence of functional effects for asthma risk variants in AECs and insight into RV-mediated transcriptional and epigenetic response mechanisms that modulate genetic effects in the airway and risk for asthma.