Curtis, J.L.

Abstract Rationale: Adverse social determinants of health (SDOH) are common in COPD and associated with increased mortality. However, cause-specific mortality is understudied. We evaluated associations of neighborhood-level SDOH with all-cause and cause-specific mortality among individuals with or at-risk for COPD. Methods: SPIROMICS is an ongoing, multi-center, longitudinal observational study of individuals across the US with current or former personal smoking histories (≥20 pack-years), with or without spirometrically-defined COPD. We established geocoded neighborhood-level SDOH at baseline using 2010 census tract data, including specifically, area deprivation index (ADI) (range 0-100, 100 = most disadvantaged), poverty level (percentage of households below the poverty line), poor food access (>1/3 of residents with no access to fresh food stores within 1 mile in urban areas and 10 miles in rural areas), and food desert (low income plus poor food access). We ascertained all-cause and cause-specific mortality through 12/31/2021 using the National Death Index. Using Cox proportional hazards models, we evaluated the risk of all-cause mortality for each SDOH. We utilized competing-risk regression models to evaluate the risk of cardiovascular, respiratory, COPD (a subset of respiratory), and neoplastic causes of death individually with each SDOH. Models were adjusted for demographics, smoking status, pack-years, BMI categories, coronary heart disease, FEV1% predicted and study site. Effect modification by lung function was assessed using multiplicative interactions between SDOH and FEV1% predicted. Results: Among 2977 participants, mean ADI was 40.1±27.8. Within a participant's neighborhood, on average 10.4±10.4% of households were below the poverty line, 933 (31.3%) had poor food access, and 220 (7.4%) resided in a food desert. During a median follow-up of 7.8 years (IQR 5.6-9.2), 744 (25.0%) participants died, most commonly from respiratory causes including COPD. Neither ADI nor neighborhood poverty level were associated with all-cause mortality or any specific cause of death (Table). Despite lack of associations between food access and mortality (Table), individuals residing in a food desert had elevated risks of all-cause (HR: 1.36 [95%CI: 1.03-1.79]) and cardiovascular (HR: 2.62 [95%CI: 1.5-4.35]) deaths. There was no significant effect modification by lung function. Conclusions: In a large cohort of individuals with personal smoking histories, with or without COPD, living in a food desert was associated with increased all-cause and cardiovascular mortality. However, neighborhood poverty level and food access, the two components of food desert, were not independently associated with mortality, suggesting the association of multimodal SDOH variables with mortality in this population.

Abstract Rationale: MUC5B and MUC5AC are neighboring genes on chromosome 11p15 that encode the two predominant mucins secreted in the respiratory airways. Increased airway mucin concentrations and an imbalance between these two mucins drive COPD symptoms and the development of airflow obstruction or COPD, but the epigenomic regulation of this loci has not been characterized in the airways. Methods: We isolated DNA from bronchial airway brushings of 72 participants with >20 pack-years smoking history from the Subpopulations and Intermediate Outcomes Measures in COPD Study (SPIROMICS). 36 participants had GOLD-based moderate-to-severe COPD (FEV1/FVC<0.70, FEV1<80%) and 36 were without or with mild COPD. We used the Illumina Infinium Methylation EPIC BeadChip Array to assess proportion of DNA methylation (β) spanning 689,937 CpG sites. We evaluated proportional DNA methylation (β) at 96 CpG loci within a 103kB region using matrixQTL for cis-expression quantitative trait methylation (eQTM: 10kB flanks relative to MUC5AC/MUC5B) integrating bulk RNA-seq data and mQTL models integrating gene sequencing data to identify DNA variation associated with proportion eQTM methylation. Models included age, sex, BMI, clinical site, current smoking vs past smoking, total pack-years, three ancestral components of ancestry, chipset, and position. Results: We identified a top eQTM, cg00524486, marginally associated with MUC5B expression (coefficient estimate=8.75, punadjusted=0.0014, pFDR=0.065, Figure 1B). This eQTM was associated with CT scan parametric response mapping-based functional small airways disease (PRM-fSAD, beta coefficient[β]=3.64, p=0.011). We tested for DNA variation associated with methylation of this top eQTM which identified two methylation quantitative trait loci (mQTL: rs885454 [β=0.044, minor allele frequency[MAF]=0.09, pFDR=0.01], rs868902 [β=0.020, MAF=0.43, pFDR=0.08, Figure 1A) associated with cg00524486 methylation, of which the more frequent mQTL, rs868902, was marginally associated with PRM-fSAD (p=0.07) in the larger SPIROMICS cohort with MUC5B DNA sequencing data. Conclusions: This preliminary multi-omic study of the lower airway epithelium demonstrates that the expression of MUC5B is epigenetically regulated by neighboring CpG probe methylation (eQTM) represented by DNA variation (mQTL). These studies require further confirmation in a larger dataset of airway samples and support a role for epigenetic variation as a biologic contributor and biomarker of early COPD pathogenesis.