Epigenome-wide DNA methylation association study of circulating IgE levels identifies novel targets for asthma
Kathryn Recto, Priyadarshini Kachroo, Tianxiao Huan, David Van Den Berg, Gha Young Lee, Helena Bui, Dong Heon Lee, Jessica Gereige, Chen Yao, Shih‐Jen Hwang, Roby Joehanes, Scott T. Weiss, Namiko Abe, Gonçalo R. Abecasis, François Aguet, Christine M. Albert, Laura Almasy, Álvaro Alonso, Seth A. Ament, Peter H. Anderson, Pramod Anugu, Deborah Applebaum‐Bowden, Kristin Ardlie, Dan E. Arking, Donna K. Arnett, Allison E. Ashley‐Koch, Stella Aslibekyan, Tim Assimes, Paul L. Auer, Dimitrios Avramopoulos, Najib Ayas, Adithya Balasubramanian, John Barnard, Kathleen C. Barnes, R. Graham Barr, Emily Barron‐Casella, Lucas Barwick, Terri H. Beaty, Gerald J. Beck, Diane M. Becker, Lewis C. Becker, Rebecca Beer, Amber L. Beitelshees, Emelia J. Benjamin, Takis Benos, Marcos Bezerra, Larry Bielak, Joshua C. Bis, Thomas W. Blackwell, John Blangero, Nathan R. Blue, Eric Boerwinkle, Donald W. Bowden, Russell P. Bowler, Jennifer A. Brody, Ulrich Broeckel, Jai Broome, Deborah Brown, Karen Bunting, Esteban G. Burchard, Carlos D. Bustamante, Erin Buth, Brian E. Cade, Jonathan Cardwell, Vincent J. Carey, Julie Carrier, April P. Carson, Cara L. Carty, Richard Casaburi, Juan P. Romero, James F. Casella, Peter J. Castaldi, Mark Chaffin, Christy Chang, Yi‐Cheng Chang, Daniel I. Chasman, Sameer Chavan, Bo-Juen Chen, Wei‐Min Chen, Yii‐Der Ida Chen, Michael Cho, Seung Hoan Choi, Lee‐Ming Chuang, Mina K. Chung, Ren‐Hua Chung, Clary B. Clish, Suzy Comhair, Matthew P. Conomos, Elaine Cornell, Adolfo Correa, Carolyn Crandall, James D. Crapo, L. Adrienne Cupples, Joanne E. Curran, Jeffrey L. Curtis, Brian Custer, Coleen Damcott, Dawood Darbar, Sean P. David, Colleen Davis
Abstract
BACKGROUND: Identifying novel epigenetic signatures associated with serum immunoglobulin E (IgE) may improve our understanding of molecular mechanisms underlying asthma and IgE-mediated diseases. METHODS: We performed an epigenome-wide association study using whole blood from Framingham Heart Study (FHS; n = 3,471, 46% females) participants and validated results using the Childhood Asthma Management Program (CAMP; n = 674, 39% females) and the Genetic Epidemiology of Asthma in Costa Rica Study (CRA; n = 787, 41% females). Using the closest gene to each IgE-associated CpG, we highlighted biologically plausible pathways underlying IgE regulation and analyzed the transcription patterns linked to IgE-associated CpGs (expression quantitative trait methylation loci; eQTMs). Using prior UK Biobank summary data from genome-wide association studies of asthma and allergy, we performed Mendelian randomization (MR) for causal inference testing using the IgE-associated CpGs from FHS with methylation quantitative trait loci (mQTLs) as instrumental variables. FINDINGS: We identified 490 statistically significant differentially methylated CpGs associated with IgE in FHS, of which 193 (39.3%) replicated in CAMP and CRA (FDR < 0.05). Gene ontology analysis revealed enrichment in pathways related to transcription factor binding, asthma, and other immunological processes. eQTM analysis identified 124 cis-eQTMs for 106 expressed genes (FDR < 0.05). MR in combination with drug-target analysis revealed CTSB and USP20 as putatively causal regulators of IgE levels (Bonferroni adjusted P < 7.94E-04) that can be explored as potential therapeutic targets. INTERPRETATION: By integrating eQTM and MR analyses in general and clinical asthma populations, our findings provide a deeper understanding of the multidimensional inter-relations of DNA methylation, gene expression, and IgE levels. FUNDING: US NIH/NHLBI grants: P01HL132825, K99HL159234. N01-HC-25195 and HHSN268201500001I.