Molecular Epidemiology of Cardiovascular Disease

Abstract: Cardiovascular disease is a major cause of morbidity and mortality, with increasing prevalence worldwide.Identification of risk markers may enable improved prevention by targeting high-risk individuals, earlier disease diagnosis and treatment, as well as stratification of disease subtypes with different treatment options, thereby minimizing side effects while increasing success rates.The overall aim of this thesis was to investigate associations between proteomic and metabolomic biomarkers, and the development of heart failure and ischemic stroke. Specific objectives were to examine potential causal pathways, and the added value in risk prediction of the identified risk markers.In Studies I–II, we performed proximity extension assay based proteomic profiling of ≥80 circulating proteins in the Swedish cohorts Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS n=901, median age 70), and the Uppsala Longitudinal Study of Adult Men (ULSAM, n=685, median age 77). In Study I, we identified nine proteins involved in apoptosis, inflammation, matrix remodeling, and fibrinolysis associated with incident heart failure, including growth differentiation factor-15 (GDF-15). In Study II, we identified several proteins associated with incident ischemic stroke, including GDF-15. Both studies revealed potential to improve disease risk prediction by using proteomic data.In Study III, we performed mass spectrometry-based metabolomic profiling in plasma or serum samples from PIVUS, ULSAM, and TwinGene (total n=3,924). The metabolites urobilin and sphingomyelin (30:1) were associated with incident heart failure.In Study IV, we followed up on the results of Studies I–II, performing Mendelian randomization analyses (a framework for causal analysis using genetic variants) in 1,053,527 individuals, with 88,448 coronary artery disease cases, 70,305 ischemic stroke cases, and 1,420 heart failure cases. This study supports a causal role of genetically elevated GDF-15 levels in heart failure development, but not in coronary artery disease or ischemic stroke.In conclusion, we identified multiple biomarkers associated with incident heart failure and ischemic stroke, potentially involved in early disease development. We also saw potential to improve disease risk prediction for incident heart failure and ischemic stroke using proteomics data.Our findings encourage further large-scale proteomic, metabolomic, and genetic studies to give new insights into heart failure and stroke pathogenesis.