Kirsch, Phillip S.

P-selectin is a cellular adhesion molecule that enhances procoagulant activity and activation of leukocyte integrins. P-selectin has been shown to be crucial in the development of atherosclerosis. Using a stratified random sample of 2406 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) at Exam 2, we investigated the association of soluble P-selectin and cardiovascular disease. The Tobit model was used to investigate the association of P-selectin levels and coronary artery calcium (CAC) and Cox proportional hazards regression was used to assess the association between protein level and incident cardiovascular disease (CVD) events (myocardial infarction, stroke, angina, or other atherosclerotic death). Mean levels of soluble P-selectin differed significantly by ethnicity; 46±18 ng/mL African Americans, 58±20 ng/mL Caucasians, 43±15 ng/mL Chinese, and 61±20 ng/mL Hispanics (p<0.0001). CAC was present in 46% of African Americans, 61% of Caucasians, 52% of Chinese, and 53% of Hispanics. P-selectin levels were significantly associated with CAC in Caucasians (p < 0.001) and African Americans (p = 0.025), see Table. This association was robust to adjustment for traditional risk factors and a significant interaction of P-selectin and ethnicity was observed (p= 0.02). Over an average of 6.5 years of follow-up there were 111 incident CVD events after MESA exam 2, 26 in African Americans, 33 in Caucasians, 16 in Chinese, and 36 in Hispanics. The risk of CVD events increased 34% per standard deviation increase in P-selectin levels only in Caucasians (p = 0.007) and this finding was consistent after adjustment for CVD risk factors (HR = 1.30, p = 0.017). We have shown in this large cohort that mean circulating P-selectin levels differed by ethnicity. Despite similar percentages of subjects with CAC in each ethnic group, P-selectin levels were significantly associated with CAC only in African Americans and Caucasians. Furthermore, in Caucasians only, P-selectin levels were associated with incident CVD events. Association of P-selectin, per SD (20 ng/mL) for the population and cardiovascular disease Outcome African Americans n = 579 Caucasians n = 620 Chinese n = 602 Hispanics n = 605 CAC, Agatston Score Beta (S.E.) P-value Beta (S.E.) P-value Beta (S.E.) P-value Beta (S.E.) P-value Model 1 85.9 (38.4) 0.025 99.4 (28.7) <0.001 8.2 (33.3) 0.81 32.1 (27.3) 0.24 Model 2 79.3 (39.8) 0.046 94.7 (29.1) 0.001 −19.5 (33.6) 0.56 27.8 (27.6) 0.31 CVD Events HR (CI) HR (CI) HR (CI) HR (CI) Model 1 1.08 (0.75, 1.57) 0.67 1.34 (1.08, 1.65) 0.007 1.09 (0.57, 2.08) 0.80 0.99 (0.71, 1.39) 0.97 Model 2 1.10 (0.76, 1.58) 0.61 1.30 (1.05, 1.62) 0.017 0.82 (0.38, 1.78) 0.62 1.00 (0.71, 1.43) 0.98 Model 1 = age and sex ; Model 2 = age, sex, BMI, smoking status, LDL, HDL, triglycerides, hypertension, diabetes

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.

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.

ObjectiveAt the cellular level, how excess adiposity promotes atherogenesis is not fully understood. One pathway involves secretion of adipokines that stimulate endothelial dysfunction through increased expression of adhesion molecules. However, the relationship of adiposity to adhesion molecules that promote atherosclerosis is largely unknown.MethodsLinear regression models were used to assess the sex‐specific associations of soluble cellular adhesion molecules (sP‐ and sL‐selectin, sICAM‐1, sVCAM‐1, and sHGF) and adiposity in 5,974 adults examined as part of the Multi‐Ethnic Study of Atherosclerosis (MESA). Adiposity measures included body mass index (BMI), waist‐to‐hip‐ratio (WHR), and computed tomography measures of subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT).ResultsThe mean age was 64 years and 52% were female. In multivariable models adjusting for traditional cardiovascular risk factors, sHGF was positively associated with BMI, WHR, and VAT in both males and females, and sP‐selectin with WHR and VAT in males. sVCAM‐1 was inversely associated with VAT in females only.ConclusionsOur results showed the relation of adiposity to soluble cellular adhesion proteins was similar across adiposity measures and for both sexes. However, the relationship between adiposity and sVCAM‐1 and P‐selectin may be modified by sex and the measure used to assess adiposity.

SummaryHepatocyte growth factor (HGF) is a mesenchyme‐derived pleiotropic factor that regulates cell growth, motility, mitogenesis, and morphogenesis in a variety of cells, and increased serum levels of HGF have been linked to a number of clinical and subclinical cardiovascular disease phenotypes. However, little is currently known regarding which genetic factors influence HGF levels, despite evidence of substantial genetic contributions to HGF variation. Based upon ethnicity‐stratified single‐variant association analysis and trans‐ethnic meta‐analysis of 6201 participants of the Multi‐Ethnic Study of Atherosclerosis (MESA), we discovered five statistically significant common and low‐frequency variants: HGF missense polymorphism rs5745687 (p.E299K) as well as four variants (rs16844364, rs4690098, rs114303452, rs3748034) within or in proximity to HGFAC. We also identified two significant ethnicity‐specific gene‐level associations (A1BG in African Americans; FASN in Chinese Americans) based upon low‐frequency/rare variants, while meta‐analysis of gene‐level results identified a significant association for HGFAC. However, identified single‐variant associations explained modest proportions of the total trait variation and were not significantly associated with coronary artery calcium or coronary heart disease. Our findings indicate that genetic factors influencing circulating HGF levels may be complex and ethnically diverse.