Omega-3 fatty acids and genome-wide interaction analyses reveal DPP10-pulmonary function association

Rationale: Omega-3 polyunsaturated fatty acids (n-3 PUFAs) have anti-inflammatory properties that could benefit adults with comprised pulmonary health. Objective: To investigate n-3 PUFA associations with spirometric measures of pulmonary function tests (PFTs) and determine underlying genetic susceptibility. Methods: Associations of n-3 PUFA biomarkers (a-linolenic acid, eicosapentaenoic acid, docosapentaenoic acid [DPA], and docosahexaenoic acid [DHA]) were evaluated with PFTs (FEV1, FVC, and FEV1/FVC) in meta-analyses across seven cohorts from the Cohorts for Heart and Aging Research in Genomic Epidemiology Consortium (N=16,134 of European or African ancestry). PFT-associated n-3 PUFAs were carried forward to genome-wide interaction analyses in the four largest cohorts (N=11,962) and replicated in one cohort (N=1,687). Cohort-specific results were combined using joint 2 degree-of-freedom (2df) meta-analyses of SNPassociations and their interactions with n-3PUFAs. Results: DPA and DHA were positively associated with FEV1 and FVC (P < 0.025), with evidence for effect modification by smoking and by sex. Genome-wide analyses identified a novel association of rs11693320-an intronic DPP10 SNP-with FVC when incorporating an interaction with DHA, and the finding was replicated (P-2df = 9.4 x 10(-9) across discovery and replication cohorts). The rs11693320-A allele (frequency, similar to 80%) was associated with lower FVC (P-SNP = 2.1 x 10(-9); beta(SNP) = 2161.0 ml), and the association was attenuated by higher DHA levels (P-SNPxDHA interaction = 2.1x10(-7); beta(SNPxDHA interaction) = 36.2 ml). Conclusions: We corroborated beneficial effects of n-3 PUFAs on pulmonary function. By modeling genome-wide n-3 PUFA interactions, we identified a novel DPP10 SNP association with FVC that was not detectable in much larger studies ignoring this interaction

INVESTIGATING THE CAUSAL ROLE OF VITAMIN D AND OMEGA-3 FATTY ACIDS IN LUNG HEALTH

232 pagesThis dissertation aimed to investigate causality in the associations of vitamin D and omega-3 fatty acids (ω-3 FAs), two nutrients recognized for their immunomodulatory and antiinflammatory properties,with lung health and disease. We used multiple methods with the goal of addressing context-specific limitations and improving causal inference. We first investigated causality in the association of serum vitamin D levels and COVID-19. We conducted a Mendelian Randomization (MR) study of genetic variants associated with vitamin D nutritional status and COVID-19 susceptibility and severity, including severe respiratory infection and hospitalization. We found no evidence for a causal effect of genetically predicted differences in long-term vitamin D nutritional status on susceptibility to and severity of COVID-19 infection. Next, we investigated causality in the association of circulating ω-3 FAs with spirometry-measured long-term lung outcomes. We applied two complementary approaches: 1) a longitudinal study of plasma phospholipid ω-3 FAs, lung function decline, and incident airway obstruction, and 2) an MR study of genetically predicted ω-3 FAs and lung function parameters. The longitudinal study found that higher ω-3 FAs were associated with an attenuation in lung function decline and reduced risk of airway obstruction, with the strongest effects for docosahexaenoic acid (DHA). The MR study corroborated these findings, with evidence for positive effects of genetically predicted ω-3 FAs on lung function parameters. Lastly, we studied the evidence for the efficacy of vitamin D supplementation in early life for preventing childhood asthma. We conducted a systematic review and meta-analysis of randomized controlled trials of vitamin D supplementation in pregnant or lactating women or young children. We identified 17 studies meeting the eligibility criteria for the review, and found moderate-certainty evidence that vitamin D supplementation in pregnancy or early childhood reduces the risk of childhood asthma or wheeze, and may also reduce the risk of atopic dermatitis and decrease markers of allergic sensitization, both of which are thought to contribute to the development of asthma. Ultimately the studies comprising this dissertation demonstrate the application of different methods to improve causal inference for nutrition and lung health. The findings could help inform public health strategies to prevent lung disease.2024-09-0

A systematic analysis of protein-altering exonic variants in chronic obstructive pulmonary disease

Genome-wide association studies (GWASs) have identified regions associated with chronic obstructive pulmonary disease (COPD). GWASs of other diseases have shown an approximately 10-fold overrepresentation of nonsynonymous variants, despite limited exonic coverage on genotyping arrays. We hypothesized that a large-scale analysis of coding variants could discover novel genetic associations with COPD, including rare variants with large effect sizes. We performed a meta-analysis of exome arrays from 218,399 controls and 33,851 moderate-to-severe COPD cases. All exome-wide significant associations were present in regions previously identified by GWAS. We did not identify any novel rare coding variants with large effect sizes. Within GWAS regions on chromosomes 5q, 6p, and 15q, four coding variants were conditionally significant (p < 0.00015) when adjusting for lead GWAS SNPs. A common GSDMB splice variant (rs11078928) previously associated with decreased risk for asthma, was nominally associated with decreased risk for COPD (MAF = 0.46, p=1.8e-4). Two stop variants in CCHCR1, a gene involved in regulating cell proliferation, were associated with COPD (both p < 0.0001). The SERPINA1 Z allele was associated with a random effects odds ratio of 1.43 for COPD (95% CI: 1.17-1.74), though with marked heterogeneity across studies. Overall, COPD-associated exonic variants were identified in genes involved in DNA methylation, cell-matrix interactions, cell proliferation, and cell death. In conclusion, we performed the largest exome array meta-analysis of COPD to date and identified potential functional coding variants. Future studies are needed to identify rarer variants, and further define the role of coding variants in COPD pathogenesis

A systematic analysis of protein-altering exonic variants in chronic obstructive pulmonary disease

Genome-wide association studies (GWASs) have identified regions associated with chronic obstructive pulmonary disease (COPD). GWASs of other diseases have shown an approximately 10-fold overrepresentation of nonsynonymous variants, despite limited exonic coverage on genotyping arrays. We hypothesized that a large-scale analysis of coding variants could discover novel genetic associations with COPD, including rare variants with large effect sizes. We performed a meta-analysis of exome arrays from 218,399 controls and 33,851 moderate-to-severe COPD cases. All exome-wide significant associations were present in regions previously identified by GWAS. We did not identify any novel rare coding variants with large effect sizes. Within GWAS regions on chromosomes 5q, 6p, and 15q, four coding variants were conditionally significant (P < 0.00015) when adjusting for lead GWAS single-nucleotide polymorphisms A common gasdermin B (GSDMB) splice variant (rs11078928) previously associated with a decreased risk for asthma was nominally associated with a decreased risk for COPD [minor allele frequency (MAF)=0.46, P = 1.8e-4]. Two stop variants in coiled-coil a-helical rod protein 1 (CCHCR1), a gene involved in regulating cell proliferation, were associated with COPD (both P < 0.0001). The SERPINA1 Z allele was associated with a random-effects odds ratio of 1.43 for COPD (95% confidence interval = 1.17–1.74), though with marked heterogeneity across studies. Overall, COPD-associated exonic variants were identified in genes involved in DNA methylation, cell-matrix interactions, cell proliferation, and cell death. In conclusion, we performed the largest exome array meta-analysis of COPD to date and identified potential functional coding variants. Future studies are needed to identify rarer variants and further define the role of coding variants in COPD pathogenesis