Molecular Epidemiology of Aortic Diameter and Subclinical Cardiovascular Disease

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PROJECT SUMMARY Cardiovascular disease (CVD) is the leading cause of death worldwide and the global burden of CVD has accelerated the need to better understand its epidemiology, identification, and treatment, particularly in high-risk and understudied population groups. African ancestry individuals have a higher risk of CVD events and mortality compared to European ancestry individuals and, although mechanisms for the racial differences in CVD are complex, it is clear that molecular and genetic differences play an important role. Emerging evidence indicates that the Wingless (Wnt) signaling pathway plays a role in CVD; however, there has been limited research on this role in humans. The funded K01 award (HL-125658 PI: Kuipers) aims to comprehensively investigate this relationship by leveraging data from a unique longitudinal cohort study of African ancestry men aged ≥40 years – the Tobago Health Study (THS), which has been ongoing since 1997. The K01 research is the first study of CVD in the THS and has recruited and collected data on 421 African ancestry men. Data collected for the K01 study include: serum and RNA samples, and multiple measures of subclinical CVD, including carotid intima- media thickness and diameter, pulse-wave velocity, ankle-brachial index, and coronary and aortic calcification. Part of the recruitment was targeted to include THS men known to carry a functional, African ancestry-specific missense variant (Ala64Thr) in the Wnt receptor, Frizzled-1 (FZD1) gene. In in vitro studies, this variant leads to over-activation of the Wnt pathway and the Hypothesis was that carriers of the variant would have a greater burden of subclinical CVD compared to non-carriers. Indeed, carriers (N=64) have larger carotid diameter than non-carriers, even after adjusting for age and other traditional cardiovascular risk factors. Thus, THS men with more Wnt activation appear to show greater outward arterial remodeling than men with usual Wnt function. In the current study, we will further investigate Wnt’s role in arterial remodeling by assessing a newly identified subclinical CVD marker thought to be reflective of early arterial changes: aortic diameter. Aortic diameter and cross sectional area will be assessed at multiple sites along the length of the aorta using archived computed tomography images from the THS study. These data will be used to test the hypothesis that changes in aortic diameter reflect the earliest measurable subclinical vascular changes compared to other established subclinical CVD markers. In addition, these data will further refine the vascular location of Wnt pathway function. Lastly, since CVD is a new focus of the THS, there are no data on cardiovascular biomarkers in the cohort, which is a big limitation for following-up on the molecular underpinnings of subclinical CVD in manuscripts or funding proposals. Therefore, a state-of-the-art, microfluidic assay (O-Link: “CVDIII” panel) will be used to measure 92 pre-determined serum CV biomarkers. These represent both established and novel CVD biomarkers and will be used as critical covariates in the planned K01 study analyses, as well as, a source for hypothesis generation on novel biomarkers of subclinical CVD in this high-risk, but understudied, African ancestry cohort.