Pankow, James S.

Incident hypertension varies across races/ethnicities. Mechanisms implicated in the pathogenesis are endothelial dysfunction with reduction of nitric oxide and alterations of the Renin-Angiotensin-Aldosterone System (RAAS). Stromal Derived Factor 1 (SDF1) and Transforming Growth Factor β1 (TGFβ1) are essential in these processes. SDF1 is a chemotactic protein that regulates migration of endothelial progenitor cells from the bone marrow to the arterial wall to repair endothelial damage; TGFβ1 promotes extra-cellular matrix deposition within arterial vessels, inhibits nitric oxide production and stimulates renin release. In order to investigate the association of circulating levels of these proteins with incident hypertension across different ethnicities, an ethnic stratified random sample of 2,880 participants from the Multi-Ethnic Study of Atherosclerosis (MESA) was used. Of those, 988 participants had available plasma samples and were without hypertension, defined as blood pressure ≥ 140/90 mmHg, or current use of antihypertensive medications, at baseline. During a median follow up of 8.5 years, 388 new cases of hypertension (101 in non-Hispanic whites, 94 in Chinese, 101 in African Americans and 92 in Hispanics) were observed. Time to hypertension incidence was estimated using Cox proportional hazards regression. Hazard Ratios were adjusted for age, sex, diabetes, LDL, HDL, triglycerides, BMI, smoking status and current alcohol use. The race/ethnicity by protein interaction p-values were 0.055 and 0.066 for TGFβ1 and SDF1 respectively, suggesting heterogeneity across races/ethnicities. In Chinese, a difference of one standard deviation of plasma TGFβ1 was associated with a 22% increase in incident hypertension (HR (95% CI) 1.22 (1.02, 1.47), p-value=0.03); and a difference of one standard deviation of plasma SDF1 was associated with a 31% decrease in incident hypertension (HR (95% CI) 0.69 (0.52, 0.91), p-value 0.008). No significant association was found between these proteins and incident hypertension among non-Hispanic whites, African or Hispanic Americans. In conclusion, soluble markers of endothelial integrity and of RAAS activation were associated with the incidence of hypertension among Chinese Americans. These results suggest heterogeneity in the pathophysiology of hypertension according to race/ethnicity.

L-selectin is an adhesion molecule constitutively expressed on leukocytes and mediating their interaction with the endothelium. As a member of the selectin family, it plays a crucial role in leukocyte adhesion to and migration through the endothelial wall during inflammation. A protective role of L-selectin in early atherosclerosis was demonstrated in animal models. Previous studies assessing the relationship of this protein with cardiovascular disease were inconsistent. Lower serum L-selectin levels were found in patients with coronary artery disease (CHD) and peripheral artery disease (PAD) compared to controls. In contrast, plasma levels of L-selectin were increased in patients with CHD and PAD. These inconsistencies might be due to an interaction of soluble L-selectin with clotting factors or anticoagulants present in plasma but not in serum. Also, the small number and Caucasian predominance of patients included in previous studies represent limitations that need to be addressed using a rigorous, population-based approach. Herein, we seek to investigate the association of serum L-selectin with subclinical outcomes in a large, ethnically heterogeneous population. In a randomly selected subset of 720 subjects for each of the four ethnicities included in the Multi-Ethnic Study of Atherosclerosis (MESA), serum samples were available for 2403 individuals (579 African Americans, 620 Caucasians, 600 Chinese and 604 Hispanics). Serum L-selectin levels and intima-media thickness (IMT) were measured at exam 2 and CAC was measured at exam 2 or 3 during the cohort follow up. Regression analysis and the Tobit model were used to assess the association of L-selectin levels with IMT and CAC respectively. The mean age was 63±10 years and 47% were men. The mean±SD protein levels were significantly different across ethnicities (867±192 ng/mL in African Americans, 956±215 ng/mL in Caucasians, 834±174 ng/mL in Chinese and 904±195 ng/mL in Hispanics; p<0.0001). In the univariate analysis, age was inversely correlated to the protein levels; in addition, levels were lower in males, regardless of ethnicity and in smokers, except among Hispanics. L-selectin was associated with modestly lower CAC only among Chinese (p=0.030), the association persisted after adjustment for traditional risk factors (p=0.046). No significant association was demontrated between the protein levels and IMT. In conclusion, in this large diverse population, we found that serum L-selectin was modestly associated to measures of subclinical atherosclerosis in Chinese but not in African, European or Hispanic Americans.

Pulse pressure (PP), defined as the difference between systolic and diastolic blood pressure, is considered a marker of large artery stiffness and has been shown to independently predict cardiovascular disease. Differences among ethnicities with regard to PP have been previously described, yet the underlying biological mechanisms are poorly understood. In addition, biomarkers of inflammation and matrix remodeling have been shown to be involved in the development of arterial stiffness. The aim of this study was to investigate the role of adhesion pathway components in the development of arterial stiffness measured by PP among four ethnicities. E-cadherin, HGF, L-selectin, P-selectin, 6-Ckine, MMP1, MMP2, RANTES, SDF1, SLPI, TGFβ1, TIMP2 and VCAM were measured in a random sample of 2402 participants (579 African Americans, 619 Caucasians, 600 Chinese and 604 Hispanics) in the Multi-Ethnic Study of Atherosclerosis (MESA) study at Exam 2. PP was measured concurrently and its association with each adhesion protein level was assessed via linear regression in each ethnicity. All analyses were adjusted for age, sex, and traditional cardiovascular risk factors. Mean PP was significantly different among ethnicities: 55.9±18.0 mmHg in African Americans, 52.1± 16.1 mmHg in Caucasians, 51.4±16.4 mmHg in Chinese, and 55.0±17.5 in Hispanics, p<0.001. MMP2 was positively associated with PP among African Americans (β=2.3 (0.6), p<0.001) and Caucasians (β=1.7 (0.5), p=0.001); TIMP2 among Caucasians (β=1.5 (0.5), p=0.002) and to a lesser extent among African Americans (β=1.2 (0.6) p=0.050) and Chinese (β=1.3 (0.6), p=0.034). SDF1 was associated to PP in African Americans (β=1.4 (0.6), p=0.017) and in Chinese (β=1.1 (0.5), p=0.042); finally an association existed between TGFβ1 and PP in C (β=1.1 (0.5), p=0.025). None of the studied proteins was associated with PP in Hispanics. In conclusion, components of the adhesion pathway were correlated to PP in this large multi-ethnic cohort, possibly giving new insight on the pathophysiology of arterial stiffness. In addition, heterogeneity by ethnicity suggests different mechanisms in the development of arterial stiffness.

Background: The Trans-Omics for Precision Medicine (TOPMed) program is performing whole-genome sequencing across multiple studies, including longitudinal cohorts, case-control, and case-only sample sets. Detecting the effects of low frequency variants requires large sample sizes, which can only be achieved by combining data across diverse study designs, including matching of case-only sample sets with controls from other studies. Here we present a strategy for combined analysis of venous thromboembolism (VTE) case status in 3 longitudinal cohorts and 3 case-only sample sets, in the context of whole-genome association studies. Methods: For each cohort study, we sampled ‘pure’ controls (without replacement) from the risk set of each incident case, within strata defined by sex, ancestry and birth-cohort. Pure controls had no event throughout their period of observation. A case’s risk set was defined as controls with no prior VTE history and under observation through an age at least as old as the case. For case-only sample sets, controls for each case were sampled from a cohort study, using the same risk set definition. Because of limited overlap in birth years between the cohort studies and the case-only sample sets, this matching was done within strata defined only by sex and ancestry group. Mixed model logistic regression will be used to account for relatedness as a random effect. Although conditional logistic regression is not practical for whole-genome association studies, case-control matching is implicitly recognized by a fixed effect for age-at-event for each matched set (1 case and >=1 matched controls). Additional fixed effects will include sample set and sex. We will also adjust for variations in case-control ratio among the matched sets. Results: In two cohort studies, we matched 1,231 cases to 4,820 controls (overall ratio = 1:3.9); only 500 controls and 5 cases could not be matched. For the case-only sample sets we matched 2,141 cases to 2,780 controls from one cohort study (overall ratio = 1:1.3); zero controls and only 14 cases could not be matched. Conclusions: We were successfully able to match nearly all cases to controls, and more than 90% of controls were also matched. By matching controls to cases based on age at event, we can account for the different risk of VTE by age clusters. Although this strategy does not provide an asymptotically unbiased estimated of the hazard ratio, compared to classical risk set sampling, it uses a large portion of the available data, it provides odds ratio estimates yielding the correct sign of association, and it reduces the potential influence of resampling subjects with rare variants. This strategy also enables combined analysis of multiple studies with different designs.

Background: Periodontal disease (PD) is associated positively with neurocognitive outcomes. Few studies have investigated the relationship between PD and indicators of brain aging and vascular changes. Hypothesis: PD is associated with greater cerebral small vessel disease, lower total and regional brain volumes and elevated β-amyloid (Aβ) deposition. Methods: We included 6,793 participants who received full-mouth periodontal examinations and tooth counts at Visit 4 (1996-1998) of the Atherosclerosis Risk in Communities Study. We used a modified 3-level version of the Periodontal Profile Class to categorize PD based on severity and extent of gingival inflammation and tissue loss. Among participants who attended Visit 5 (2011-2013), n=1,306 received a brain MRI and n=248 received a PET scan. Total brain volume, Alzheimer’s disease signature volume, and presence of microhemorrhages and cerebral infarctions were ascertained via 3T MRI; Aβ deposition was assessed from PET. We regressed brain volumes on baseline PD status using weighted multivariable linear regression. Presence of cerebrovascular microhemorrhages, infarctions, or elevated Aβ (standardized uptake value ratio>1.2) were regressed on PD category using logistic models. We examined the interaction between Apolipoprotein E ε4 ( APOE ) allele possession and PD categories on the Aβ outcome. Results: Prevalence of baseline periodontal disease was 73% (959/1306) and 87% (206/248) among the MRI and PET subgroups, respectively. PD was not associated with volumetric brain measures nor microhemorrhages. PD was inversely associated with the odds of subcortical and lacunar infarctions. PD and Aβ were not associated in main effect or interaction analyses, although there was a notably stronger association among carriers of APOE . Conclusion: PD was not associated with altered brain structure, cerebral microhemorrhages or elevated Aβ deposition. Counter to the hypothesis, PD and complete tooth loss were inversely associated with cerebral infarctions.

In this work related to familial aggregation of familial venous thromboembolism, the investigators report genomic and transcriptomic association of 16 novel susceptibility loci for venous thromboembolism.

Introduction: Diabetes mellitus (DM) is a complication of chronic pancreatitis (CP). Whether pancreatogenic diabetes associated with CP-DM represents a discrete pathophysiologic entity from type 2 DM (T2DM) remains uncertain. Addressing this question is needed for development of specific measures to manage CP-DM. We approached this question from a unique standpoint, hypothesizing that if CP-DM and T2DM are separate disorders, they should be genetically distinct. To test this hypothesis, we sought to determine whether a genetic risk score (GRS) based on validated single nucleotide polymorphisms for T2DM could distinguish between groups with CP-DM and T2DM. Methods: We used 60 T2DM single nucleotide polymorphisms to construct a weighted GRS in 1,613 subjects from the North American Pancreatitis Study 2 and 2,685 subjects from the Multi-Ethnic Study of Atherosclerosis, all of European origin. Results: The mean GRS was identical between 321 subjects with CP-DM and 423 subjects with T2DM (66.53 vs 66.42, P = 0.95), and the GRS of both diabetic groups was significantly higher than that of nondiabetic controls (n = 3,554, P < 0.0001). Exploratory analyses attempting to enrich the CP-DM group for pancreatogenic diabetes, such as eliminating diabetes diagnosed before CP, requiring pancreas-specific comorbidities, or removing those with a family history of diabetes, did not improve the ability of the GRS to distinguish between CP-DM and T2DM. Discussion: Recognizing that we lacked a gold standard to define CP-DM, our study suggests that CP-DM may be a subtype of T2DM, a notion that should be tested in future, large prospective studies.

Objective To determine if hepatocyte growth factor (HGF), a promising biomarker of coronary heart disease (CHD) given its release into circulation in response to endothelial damage, is associated with subclinical and clinical CHD in a racial/ethnic diverse population. Methods HGF was measured in 6738 participants of the Multi-Ethnic Study of Atherosclerosis (MESA). Highest mean HGF values (pg/mL) were observed in Hispanic, followed by African, non-Hispanic white, then Chinese Americans. Results In all races/ethnicities, HGF levels were associated with older age, higher systolic blood pressure (SBP) and body mass index, lower high-density lipoprotein, diabetes and current smoking. In fully adjusted models, each SD higher HGF was associated with an average increase in coronary artery calcium (CAC) of 55 Agatston units for non-Hispanic whites (p<0.001) and 51 Agatston units for African-Americans (p=0.007) but was not in the other race/ethnic groups (interaction p=0.02). There were 529 incident CHD events, and CHD risk was 41% higher in African (p<0.001), 17% in non-Hispanic white (p=0.026) and Chinese (p=0.36), and 6% in Hispanic Americans (p=0.56) per SD increase in HGF. Conclusion In a large and diverse population-based cohort, we report that HGF is associated with subclinical and incident CHD. We demonstrate evidence of racial/ethnic heterogeneity within these associations, as the results are most compelling in African-Americans and non-Hispanic white Americans. We provide evidence that HGF is a biomarker of atherosclerotic disease that is independent of traditional risk factors.

Background and Purpose— Hepatocyte growth factor (HGF) is positively associated with ischemic and hemorrhagic stroke risk factors. However, understanding the relation between HGF and stroke is in its infancy. Therefore, we sought to examine the association of circulating HGF with incident stroke using data from the MESA (Multi-Ethnic Study of Atherosclerosis). We hypothesized that circulating HGF would be positively associated with an increased risk of stroke. Methods— Participants aged 45 to 84 years (n=6711) had HGF measured between 2000 and 2002 and were followed for incident stroke through 2013 (n=233). Cox proportional hazards regression was used to calculate hazard ratios and 95% confidence intervals for incident stroke. A secondary analysis stratified results by adjudicated stroke type (n=183 ischemic; n=39 hemorrhagic; n=11 other). Results— After adjustment for potential confounding variables, risk of stroke was 17% higher with each standard deviation increase in HGF (hazard ratio, 1.17; 95% confidence interval, 1.03–1.34). This association was mainly driven by ischemic stroke and did not change on exclusion of cardioembolic strokes, although the number of excluded cases was small. The few hemorrhagic and other types of stroke were not associated with HGF. Conclusions— Circulating HGF was positively associated with the incidence of stroke in a diverse, population-based cohort of men and women from the United States. Our findings support the hypothesis that circulating HGF is a marker of endothelial damage and suggest that HGF may have utility as a prognostic marker of stroke risk.

Inflammation plays a pivotal role in peripheral artery disease (PAD). Cellular adhesion proteins mediate the interaction of leukocytes with endothelial cells during inflammation. To determine the association of cellular adhesion molecules with ankle–brachial index (ABI) and ABI category (≤1.0 vs >1.0) in a diverse population, 15 adhesion proteins were measured in the Multi-Ethnic Study of Atherosclerosis (MESA). To assess multivariable associations of each protein with ABI and ABI category, linear and logistic regression was used, respectively. Among 2364 participants, 23 presented with poorly compressible arteries (ABI > 1.4) and were excluded and 261 had ABI ≤ 1.0. Adjusting for traditional risk factors, elevated levels of soluble P-selectin, hepatocyte growth factor, and secretory leukocyte protease inhibitor were associated with lower ABI ( P = .0004, .001, and .002, respectively). Per each standard deviation of protein, we found 26%, 20%, and 19% greater odds of lower ABI category ( P = .001, .01, and .02, respectively). Further investigation into the adhesion pathway may shed new light on biological mechanisms implicated in PAD.