COL6A3-derived endotrophin mediates the effect of obesity on coronary artery disease: an integrative proteogenomics analysis

Obesity strongly increases the risk of cardiometabolic diseases, yet the underlying mediators of this relationship are not fully understood. Given that obesity has broad effects on circulating protein levels, we investigated circulating proteins that mediate the effects of obesity on coronary artery disease (CAD), stroke, and type 2 diabetes—since doing so may prioritize targets for therapeutic intervention. By integrating proteome-wide Mendelian randomization (MR) screening 4,907 plasma proteins, colocalization, and mediation analyses, we identified seven plasma proteins, including collagen type VI α3 (COL6A3). COL6A3 was strongly increased by body mass index (BMI) (β = 0.32, 95% CI: 0.26–0.38, P = 3.7 × 10-8 per s.d. increase in BMI) and increased the risk of CAD (OR = 1.47, 95% CI:1.26–1.70, P = 4.5 × 10-7 per s.d. increase in COL6A3). Notably, COL6A3 is cleaved at its C-terminus to produce endotrophin, which was found to mediate this effect on CAD. In single-cell RNA sequencing of adipose tissues and coronary arteries, COL6A3 was highly expressed in cell types involved in metabolic dysfunction and fibrosis. Finally, we found that body fat reduction can reduce plasma levels of COL6A3-derived endotrophin, thereby highlighting a tractable way to modify endotrophin levels. In summary, we provide actionable insights into how circulating proteins mediate the effect of obesity on cardiometabolic diseases and prioritize endotrophin as a potential therapeutic target. ### Competing Interest Statement J.B.R. has served as an advisor to GlaxoSmithKline and Deerfield Capital. J.B.R.'s institution has received investigator-initiated grant funding from Eli Lilly, GlaxoSmithKline, and Biogen for projects unrelated to this research. J.B.R is the CEO of 5 Prime Sciences (www.5primesciences.com), which provides research services for biotech, pharma, and venture capital companies for projects unrelated to this research. T.L. and V.F. are employees of 5 Prime Sciences. The remaining authors declare no competing interests. ### Funding Statement The Richards research group is supported by the Canadian Institutes of Health Research (CIHR: 365825, 409511, 100558, 169303), the McGill Interdisciplinary Initiative in Infection and Immunity (MI4), the Lady Davis Institute of the Jewish General Hospital, the Jewish General Hospital Foundation, the Canadian Foundation for Innovation, the NIH Foundation, Cancer Research UK, Genome Quebec, the Public Health Agency of Canada, McGill University, Cancer Research UK [grant number C18281/A29019] and the Fonds de Recherche Quebec Sante (FRQS). J.B.R. is supported by an FRQS Merite Clinical Research Scholarship. Support from Calcul Quebec and Compute Canada is acknowledged. TwinsUK is funded by the Welcome Trust, Medical Research Council, European Union, the National Institute for Health Research (NIHR)-funded BioResource, Clinical Research Facility and Biomedical Research Centre based at Guy's and St Thomas' NHS Foundation Trust in partnership with King's College London. NJT is a Wellcome Trust Investigator (202802/Z/16/Z), is the PI of the Avon Longitudinal Study of Parents and Children (MRC & WT 217065/Z/19/Z), is supported by the University of Bristol NIHR Biomedical Research Centre (BRC-1215-2001), the MRC Integrative Epidemiology Unit (MC\_UU\_00011/1) and works within the CRUK Integrative Cancer Epidemiology Programme (C18281/A29019). The Genotype-Tissue Expression (GTEx) Project was supported by the Common Fund of the Office of the Director of the National Institutes of Health, and by NCI, NHGRI, NHLBI, NIDA, NIMH, and NINDS. The data used for the analyses described in this manuscript were obtained from: the GTEx Portal on March 26, 2023. S.Y. is supported by the Japan Society for the Promotion of Science. T.L. is supported by a Schmidt AI in Science Postdoctoral Fellowship, a Vanier Canada Graduate Scholarship, an FRQS doctoral training fellowship, and a McGill University Faculty of Medicine Studentship. G.B.L. is supported by scholarships from the FRQS, the CIHR, and Quebec's ministry of health and social services. Y.C. is supported by an FRQS doctoral training fellowship and the Lady Davis Institute/TD Bank Studentship Award. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All contributing cohorts obtained ethical approval from their intuitional ethics review boards. The contributing cohorts include UK Biobank, GIANT consortium, deCODEstudy, Fenland study, AGES Reykjavik study, INTERVAL study, CARDIoGRAMplusC4D, GIGASTROKE, and MAGIC consortium. The study was approved by the Norfolk Research Ethics Committee (no. 05/ Q0101/191), and all participants gave their informed written consent. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes We used GWAS summary statistics from the following source: BMI GWAS from GIANT and UK Biobank (https://portals.broadinstitute.org/collaboration/giant/). Plasma proteome GWAS from the deCODEstudy (https://www.deCODE.com/summarydata/), UK Biobank (https://doi.org/10.1101/2022.06.17.496443), Fenland (https://omicscience.org/apps/pgwas/), and the AGES Reykjavik study (https://doi.org/.1126/science.aaq1327). We also used coronary artery disease GWAS from CARDIoGRAMplusC4D (http://www.cardiogramplusc4d.org/), stroke GWAS from GIGASTROKE (GCST90104534 and GCST90104535, at https://www.ebi.ac.uk/gwas/studies/), and type 2 diabetes GWAS from Mahajan et al. (https://doi.org/10.1038/s41588-022-01058-3). For gene expression data, we used data from Nathan et al. (SCP498 at Single Cell Portal https://singlecell.broadinstitute.org/) and Wirka et al (GSE131780 at Gene Expression Omnibus database https://www.ncbi.nlm.nih.gov/geo/). Code availability We used R v4.1.2 (https://www.r-project.org/), TwoSampleMR v.0.5.6 (https://mrcieu.github.io/TwoSampleMR/), snappy v1.0 (https://gitlab.com/richards-lab/vince.forgetta/snappy), coloc v5.1.0 (https://chr1swallace.github.io/coloc/), PLINK v1.9 (http://pngu.mgh.harvard.edu/purcell/plink/), GCTA fastGWA v1.93.3 (https://yanglab.westlake.edu.cn/software/gcta/), and Seurat v4.0.6 (https://satijalab.org/seurat/). Custom codes will be made available on GitHub (https://github.com/satoshi-yoshiji/cm_proteogenomics/) upon publication of the manuscript.