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1.  The Role of Epidemiology in the Era of Molecular Epidemiology and Genomics: Summary of the 2013 AJE-sponsored Society of Epidemiologic Research Symposium 
American Journal of Epidemiology  2013;178(9):1350-1354.
On June 20, 2013, the American Journal of Epidemiology sponsored a symposium at the Society for Epidemiologic Research's 46th Annual Meeting in Boston, Massachusetts, entitled, “What Is the Role of Epidemiology in the Era of Molecular Biology and Genomics?” The future of epidemiology depends on innovation in generating interesting and important testable hypotheses that are relevant to population health. These new strategies will depend on new technology, both in measurement of agents and environment and in the fields of pathophysiology and outcomes, such as cellular epidemiology and molecular pathology. The populations to be studied, sample sizes, and study designs should be selected based on the hypotheses to be tested and include case-control, cohort, and clinical trials. Developing large mega cohorts without attention to specific hypotheses is inefficient, will fail to address many associations with high-quality data, and may well produce spurious results.
doi:10.1093/aje/kwt239
PMCID: PMC3988450  PMID: 24105654
immunology; pathology; study design
2.  Fibrosis-Related Biomarkers and Incident Cardiovascular Disease in Older Adults: The Cardiovascular Health Study 
Background
Fibrotic changes in the heart and arteries have been implicated in a diverse range of cardiovascular diseases (CVD), but whether circulating biomarkers that reflect fibrosis are associated with CVD is unknown.
Methods and Results
We determined the associations of two biomarkers of fibrosis, transforming growth factor- β (TGF-β) and procollagen type III N-terminal propeptide (PIIINP), with incident heart failure, myocardial infarction (MI), and stroke among community-living older adults in the Cardiovascular Health Study. We measured circulating TGF-β (n=1,371) and PIIINP (n=2,568) from plasma samples collected in 1996 and ascertained events through 2010. Given TGF-β’s pleiotropic effects on inflammation and fibrogenesis, we investigated potential effect modification by C-reactive protein (CRP) in secondary analyses. After adjustment for sociodemographic, clinical, and biochemical risk factors, PIIINP was associated with total CVD (hazard ratio [HR] per standard deviation [SD]=1.07, 95% confidence interval [CI]: 1.01-1.14) and heart failure (HR per SD=1.08, CI: 1.01-1.16), but not MI or stroke. TGF-β was not associated with any CVD outcomes in the full cohort, but was associated with total CVD (HR per SD=1.16, CI: 1.02-1.31), heart failure (HR per SD=1.16, CI: 1.01-1.34), and stroke (HR per SD=1.20, CI: 1.01-1.42) among individuals with CRP above the median, 2.3 mg/L (P-interaction < 0.05).
Conclusions
Our findings provide large-scale, prospective evidence that circulating biomarkers of fibrosis, measured in community-living individuals late in life, are associated with CVD. Further research on whether TGF-β has a stronger fibrogenic effect in the setting of inflammation is warranted.
doi:10.1161/CIRCEP.114.001610
PMCID: PMC4140969  PMID: 24963008
collagen; cardiovascular disease; heart failure; epidemiology
3.  Switch to Raltegravir Decreases Soluble CD14 in Virologically Suppressed Overweight Women: The Women, Integrase, and Fat Accumulation Trial 
HIV medicine  2014;15(7):431-441.
Objectives
Soluble CD14 (sCD14) is a monocyte activation marker associated with increased mortality in HIV. We assessed 48-week changes in sCD14 and other inflammatory biomarkers in virologically suppressed, HIV-infected women switching to raltegravir (RAL) from PI or NNRTI.
Methods
HIV-infected women with central adiposity and HIV-1 RNA <50 copies/mL continued their thymidine-sparing NRTI backbone and were randomized to switch to open-label RAL at week 0 (immediate) or 24 (delayed). In an exploratory analysis, inflammatory biomarkers were measured on stored fasting plasma.
Results
Thirty-seven evaluable subjects were 78% non-White and had median age 43 years, BMI 32 kg/m2 and CD4+ T cell count 558 cells/µL. At baseline, biomarker values were similar between groups. After 24 weeks, median sCD14 significantly declined in subjects switching to RAL (−21% (p<0.001) vs. PI/NNRTI −5% (p=0.49), between group p<0.01). After 48 weeks, immediate switch subjects maintained this decline and delayed switch subjects experienced a similar decline following switch to RAL (−10%, within-group p<0.01). Immediate switch subjects also experienced an initial increase in TNF-α that was neither maintained after 48 weeks nor seen in delayed switch subjects. After adjustment for multiple testing, only declines in sCD14 remained significant.
Conclusions
In this randomized trial of women with central adiposity, switch to RAL from PI or NNRTI was associated with a statistically significant decline in sCD14. Further studies are needed to determine whether integrase inhibitors have improved monocyte activation profiles compared to PIs and/or NNRTIs, and whether measured differences between antiretroviral agents translate to demonstrable clinical benefit.
doi:10.1111/hiv.12128
PMCID: PMC4107004  PMID: 24506429
raltegravir; sCD14; monocyte activation; inflammation; women
4.  Estimated GFR and Circulating 24,25-Dihydroxyvitamin D3 Concentration: A Participant-Level Analysis of 5 Cohort Studies and Clinical Trials 
Background
Decreased glomerular filtration rate (GFR) leads to reduced production of 1,25-dihydroxyvitamin D3 from 25-hydroxyvitamin D3 (25(OH)D3). Effects of low GFR on vitamin D catabolism are less well understood. We tested associations of estimated GFR (eGFR) with the circulating concentration of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3), the most abundant product of 25(OH)D3 catabolism, across populations with a wide range of GFR.
Study Design
Cross-sectional study.
Setting & Participants
9596 participants in 5 cohort studies and clinical trials: the Diabetes Control and Complications Trial (N=1193), Multi-Ethnic Study of Atherosclerosis (N=6470), Cardiovascular Health Study (N=932), Seattle Kidney Study (N=289), and Hemodialysis Study (N=712).
Predictor
eGFR.
Outcome
Circulating 24,25(OH)2D3 concentration.
Measurements
GFR was estimated from serum creatinine using the Chronic Kidney Disease Epidemiology Collaboration equation. Vitamin D metabolites were measured by mass spectrometry.
Results
Circulating 24,25(OH)2D3 concentration was correlated with circulating 25(OH)D3 concentration (Pearson r range, 0.64–0.88). This correlation was weaker with lower eGFR. Moreover, the increment in 24,25(OH)2D3 associated with higher 25(OH)D3 (“slope”) was lower with lower eGFR: 2.06 (95% CI, 2.01–2.10), 1.77 (95% CI, 1.74–1.81), 1.55 (95% CI, 1.48–1.62), 1.17 (95% CI, 1.05–1.29), 0.92 (95% CI, 0.74–1.10), 0.61 (95% CI, 0.22–1.00), and 0.37 (95% CI, 0.35–0.39) ng/mL 24,25(OH)2D3 per 10 ng/mL 25(OH)D3 for eGFR ≥90, 60–89, 45–59, 30–44, 15–29, and <15 mL/min/1.73 m2 and ESRD treated with hemodialysis, respectively. As a result, at a 25(OH)D3 concentration of 20 ng/mL, mean 24,25(OH)2D3 concentration was 2.92 (95% CI, 2.87–2.96), 2.68 (95% CI, 2.64–2.72), 2.35 (95% CI, 2.26–2.45), 1.92 (95% CI, 1.74–2.10), 1.69 (95% CI, 1.43–1.95), 1.14 (95% CI, 0.62–1.66), and 1.04 (95% CI,1.02–1.07) ng/mL for each category, respectively. This interaction was independent of other relevant clinical characteristics. Race, diabetes, urine albumin excretion, and the circulating concentrations of parathyroid hormone and fibroblast growth factor 23 more modestly modified the association of 24,25(OH)2D3 with 25(OH)D3.
Limitations
Lack of direct pharmacokinetic measurements of vitamin D catabolism.
Conclusions
Lower eGFR is strongly associated with reduced vitamin D catabolism as measured by circulating 24,25(OH)2D3 concentration.
doi:10.1053/j.ajkd.2014.02.015
PMCID: PMC4111986  PMID: 24703961
decreased renal function; low estimated glomerular filtration rate; vitamin D catabolism; 1,25-dihydroxyvitamin D3; 25-hydroxyvitamin D3; active vitamin D; chronic kidney disease (CKD); biomarker
5.  Large Multiethnic Candidate Gene Study for C-Reactive Protein Levels: Identification of a Novel Association at CD36 in African Americans 
Human genetics  2014;133(8):985-995.
C-reactive protein (CRP) is a heritable biomarker of systemic inflammation and a predictor of cardiovascular disease (CVD). Large-scale genetic association studies for CRP have largely focused on individuals of European descent. We sought to uncover novel genetic variants for CRP in a multi-ethnic sample using the ITMAT Broad-CARe (IBC) array, a custom 50,000 SNP gene-centric array having dense coverage of over 2,000 candidate CVD genes. We performed analyses on 7570 African Americans (AA) from the Candidate gene Association Resource (CARe) study and race-combined meta-analyses that included 29,939 additional individuals of European descent from CARe, the Women’s Health Initiative (WHI) and KORA studies. We observed array-wide significance (p<2.2×10−6) for four loci in AA, three of which have been reported previously in individuals of European descent (IL6R, p=2.0×10−6; CRP, p=4.2×10−71; APOE, p=1.6×10−6). The fourth significant locus, CD36 (p=1.6×10−6), was observed at a functional variant (rs3211938) that is extremely rare in individuals of European descent. We replicated the CD36 finding (p=1.8×10−5) in an independent sample of 8041 AA women from WHI; a meta-analysis combining the CARe and WHI AA results at rs3211938 reached genome-wide significance (p=1.5×10−10). In the race-combined meta-analyses, 13 loci reached significance, including ten (CRP, TOMM40/APOE/APOC1, HNF1A, LEPR, GCKR, IL6R, IL1RN, NLRP3, HNF4A and BAZ1B/BCL7B) previously associated with CRP, and one (ARNTL) previously reported to be nominally associated with CRP. Two novel loci were also detected (RPS6KB1, p=2.0×10−6; CD36, p=1.4×10−6). These results highlight both shared and unique genetic risk factors for CRP in AA compared to populations of European descent.
doi:10.1007/s00439-014-1439-z
PMCID: PMC4104766  PMID: 24643644
C-reactive protein; Inflammation; Multi-ethnic; Candidate gene
6.  A genetic association study of D-dimer levels with 50K SNPs from a candidate gene chip in four ethnic groups 
Thrombosis research  2014;134(2):462-467.
Introduction
D-dimer, a fibrin degradation product, is related to risk of cardiovascular disease and venous thromboembolism. Genetic determinants of D-dimer are not well characterized; notably, few data have been reported for African American (AA), Asian, and Hispanic populations.
Materials and Methods
We conducted a large-scale candidate gene association study to identify variants in genes associated with D-dimer levels in multi-ethnic populations. Four cohorts, comprising 6,848 European Americans (EAs), 2,192 AAs, 670 Asians, and 1,286 Hispanics in the NHLBI Candidate Gene Association Resource (CARe) consortium, were assembled. Approximately 50,000 genotyped SNPs in 2,000 cardiovascular disease gene loci were analyzed by linear regression, adjusting for age, sex, study site, and principal components in each cohort and ethnic group. Results across studies were combined within each ethnic group by meta-analysis.
Results
Twelve SNPs in coagulation factor V (F5) and 3 SNPs in the fibrinogen alpha chain (FGA) were significantly associated with D-dimer level in EAs with p < 2.0×10−6. The signal for the most associated SNP in F5 (rs6025, F5 Leiden) was replicated in Hispanics (p = 0.023), while that for the top functional SNP in FGA (rs6050) was replicated in AAs (p = 0.006). No additional SNPs were significantly associated with D-dimer.
Conclusions
Our study replicated previously reported associations of D-dimer with SNPs in F5 (F5-Leiden) and FGA in EAs; we demonstrated replication of the association of D-dimer with FGA rs6050 in AAs and the F5-Leiden variant in Hispanics.
doi:10.1016/j.thromres.2014.05.018
PMCID: PMC4111961  PMID: 24908450
D-dimer; genetic association study; CARe consortium; single nucleotide polymorphisms
7.  Advanced Glycation/Glycoxidation Endproduct Carboxymethyl-Lysine and Incidence of Coronary Heart Disease and Stroke in Older Adults 
Atherosclerosis  2014;235(1):116-121.
Background
Advanced glycation/glycoxidation endproducts (AGEs) accumulate in settings of increased oxidative stress – such as diabetes, chronic kidney disease and aging – where they promote vascular stiffness and atherogenesis, but the prospective association between AGEs and cardiovascular events in elders has not been previously examined.
Methods
To test the hypothesis that circulating levels of Nε-carboxymethyl-lysine (CML), a major AGE, increase the risk of incident coronary heart disease and stroke in older adults, we measured serum CML by immunoassay in 2,111 individuals free of prevalent cardiovascular disease participating in a population-based study of U.S. adults ages 65 and older.
Results
During median follow-up of 9.1 years, 625 cardiovascular events occurred. CML was positively associated with incident cardiovascular events after adjustment for age, sex, race, systolic blood pressure, anti-hypertensive treatment, diabetes, smoking status, triglycerides, albumin, and self-reported health status (hazard ratio [HR] per SD [0.99 pmol/l] increase = 1.11, 95% confidence interval [CI]=1.03–1.19). This association was not materially attenuated by additional adjustment for C-reactive protein, estimated glomerular filtration rate (eGFR), and urine albumin/creatinine ratio. Findings were similar for the component endpoints of coronary heart disease and stroke.
Conclusions
In this large older cohort, CML was associated with an increased risk of cardiovascular events independent of a wide array of potential confounders and mediators. Although the moderate association limits CML’s value for risk prediction, these community-based findings provide support for clinical trials to test AGE-lowering therapies for cardiovascular prevention in this population.
doi:10.1016/j.atherosclerosis.2014.04.013
PMCID: PMC4169874  PMID: 24825341
Advanced glycation endproducts; Carboxymethyl-lysine; Aging; Older Adults; Coronary Heart Disease; Stroke
8.  T‐Helper Type 1 Bias in Healthy People Is Associated With Cytomegalovirus Serology and Atherosclerosis: The Multi‐Ethnic Study of Atherosclerosis 
Background
Although T‐helper type 1 (Th1) cells are considered important in atherosclerosis, the relationships between Th1 and Th2 cells and atherosclerosis have not been examined in population‐based studies.
Methods and Results
We measured Th cells as a percentage of lymphocytes by flow cytometry using CD4 staining (%CD4) in 917 participants of the Multi‐Ethnic Study of Atherosclerosis. We also measured interferon gamma–positive and interleukin‐4‐positive CD4+ cells, representing Th1 and Th2 subpopulations (%Th1 and %Th2), respectively. We found that %CD4 was 1.5% lower per 10 years of age (P<0.0001). Whites had higher %CD4 and lower %Th1 and %Th2 values than other race/ethnic groups. Body mass index (BMI) and blood pressure were associated with %CD4, but no traditional cardiovascular disease (CVD) risk factors were associated with %Th1 or %Th2. In multivariable models, the major independent variable associated with %Th1 was cytomegalovirus (CMV) antibody titer, with minor contributions from age, sex, seasonality, and interleukin‐6. In models with coronary artery calcification level as the outcome, significant independent variables included age, sex, smoking status, and %Th1 (β=0.25; P≤0.01). Both %Th1 and %Th2 were associated with common carotid intimal media thickness (β=0.02 and −0.02, respectively; both P<0.05), as were age, sex, race/ethnicity, blood pressure, and BMI.
Conclusions
Th1 bias is associated with subclinical atherosclerosis in a multiethnic population. The main Th1 correlate was CMV infectious burden. These findings are consistent with a role of Th1 cells in atherosclerosis and suggest the importance of prospective studies of T‐helper cell biasing in CVD.
doi:10.1161/JAHA.113.000117
PMCID: PMC3698770  PMID: 23688675
atherosclerosis; epidemiology; immunology; inflammation; T‐helper cell
9.  Fibrosis-Related Biomarkers and Risk of Total and Cause-Specific Mortality 
American Journal of Epidemiology  2014;179(11):1331-1339.
Fibrosis has been implicated in diverse diseases of the liver, kidney, lungs, and heart, but its importance as a risk factor for mortality remains unconfirmed. We determined the prospective associations of 2 complementary biomarkers of fibrosis, transforming growth factor-β (TGF-β) and procollagen type III N-terminal propeptide (PIIINP), with total and cause-specific mortality risks among community-living older adults in the Cardiovascular Health Study (1996–2010). We measured circulating TGF-β and PIIINP levels in plasma samples collected in 1996 and ascertained the number of deaths through 2010. Both TGF-β and PIIINP were associated with elevated risks of total and pulmonary mortality after adjustment for sociodemographic, clinical, and biochemical risk factors. For total mortality, the hazard ratios per doubling of TGF-β and PIIINP were 1.09 (95% confidence interval (CI): 1.01, 1.17; P = 0.02) and 1.14 (CI: 1.03, 1.27; P = 0.01), respectively. The corresponding hazard ratios for pulmonary mortality were 1.27 (CI: 1.01, 1.60; P = 0.04) for TGF-β and 1.52 (CI: 1.11, 2.10; P = 0.01) for PIIINP. Associations of TGF-β and PIIINP with total and pulmonary mortality were strongest among individuals with higher C-reactive protein concentrations (P for interaction < 0.05). Our findings provide some of the first large-scale prospective evidence that circulating biomarkers of fibrosis measured late in life are associated with death.
doi:10.1093/aje/kwu067
PMCID: PMC4036218  PMID: 24771724
biomarkers; fibrosis; inflammation; mortality
10.  Serum Carboxymethyl-Lysine, Disability, and Frailty in Older Persons: The Cardiovascular Health Study 
Background.
Advanced glycation endproducts are biologically active compounds that accumulate in disordered metabolism and normal aging. Carboxymethyl-lysine (CML), a ubiquitous human advanced glycation endproduct, has been associated with age-related conditions and mortality. Our objective was to ascertain the relationship between CML and geriatric outcomes (disability and frailty) in a large cohort of older men and women.
Methods.
In 1996–1997, serum CML was measured in 3,373 Cardiovascular Health Study participants (mean age 78.1 ± 4.8 years). Disability, defined as difficulty in any of six activities of daily living, was assessed every 6–12 months for 14 years. Frailty was defined according to five standard criteria at the 1996–1997 visit. Cox proportional hazard models estimated the relationship between CML and incident disability (N = 2,643). Logistic regression models estimated the relationship between CML and prevalent frailty.
Results.
Adjusting for multiple potential confounders, higher CML was associated with incident disability (hazard ratio per standard deviation [225 ng/mL] increase: 1.05, 95% CI 1.01–1.11). In men, odds of frailty increased with higher CML values (odds ratio = 1.30 per standard deviation, 95% CI 1.14–1.48), but the relationship was attenuated by adjustment for cognitive status, kidney function, and arthritis. CML was not associated with frailty in women.
Conclusions.
Higher serum CML levels in late life are associated with incident disability and prevalent frailty. Further work is needed to understand CML’s value as a risk stratifier, biomarker, or target for interventions that promote healthy aging.
doi:10.1093/gerona/glt155
PMCID: PMC4022092  PMID: 24127427
Biomarkers; Disablement process; Epidemiology; Frailty; Metabolism.
11.  Age-related variations in the methylome associated with gene expression in human monocytes and T cells 
Nature communications  2014;5:5366.
Age-related variations in DNA methylation have been reported; however, the functional relevance of these differentially methylated sites (age-dMS) are unclear. Here we report potentially functional age-dMS, defined as age- and cis-gene expression-associated methylation sites (age-eMS), identified by integrating genome-wide CpG methylation and gene expression profiles collected ex vivo from circulating T cells (227 CD4+ samples) and monocytes (1,264 CD14+ samples, age range: 55–94 years). None of the age-eMS detected in 227 T cell samples are detectable in 1,264 monocyte samples, in contrast to the majority of age-dMS detected in T cells that replicated in monocytes. Age-eMS tend to be hypomethylated with older age, located in predicted enhancers, and preferentially linked to expression of antigen processing and presentation genes. These results identify and characterize potentially functional age-related methylation in human T cells and monocytes, and provide novel insights into the role age-dMS may play in the aging process.
doi:10.1038/ncomms6366
PMCID: PMC4280798  PMID: 25404168
12.  Genome-Wide Association Study for Circulating Tissue Plasminogen Activator (tPA) Levels and Functional Follow-up Implicates Endothelial STXBP5 and STX2 
Huang, Jie | Huffman, Jennifer E. | Yamkauchi, Munekazu | Trompet, Stella | Asselbergs, Folkert W. | Sabater-Lleal, Maria | Trégouët, David-Alexandre | Chen, Wei-Min | Smith, Nicholas L. | Kleber, Marcus E. | Shin, So-Youn | Becker, Diane M. | Tang, Weihong | Dehghan, Abbas | Johnson, Andrew D. | Truong, Vinh | Folkersen, Lasse | Yang, Qiong | Oudot-Mellakh, Tiphaine | Buckley, Brendan M. | Moore, Jason H. | Williams, Frances M.K. | Campbell, Harry | Silbernagel, Günther | Vitart, Veronique | Rudan, Igor | Tofler, Geoffrey H. | Navis, Gerjan J. | DeStefano, Anita | Wright, Alan F. | Chen, Ming-Huei | de Craen, Anton J.M. | Worrall, Bradford B. | Rudnicka, Alicja R. | Rumley, Ann | Bookman, Ebony B. | Psaty, Bruce M. | Chen, Fang | Keene, Keith L. | Franco, Oscar H. | Böhm, Bernhard O. | Uitterlinden, Andre G. | Carter, Angela M. | Jukema, J. Wouter | Sattar, Naveed | Bis, Joshua C. | Ikram, Mohammad A. | Sale, Michèle M. | McKnight, Barbara | Fornage, Myriam | Ford, Ian | Taylor, Kent | Slagboom, P. Eline | McArdle, Wendy L. | Hsu, Fang-Chi | Franco-Cereceda, Anders | Goodall, Alison H. | Yanek, Lisa R. | Furie, Karen L. | Cushman, Mary | Hofman, Albert | Witteman, Jacqueline CM. | Folsom, Aaron R. | Basu, Saonli | Matijevic, Nena | van Gilst, Wiek H. | Wilson, James F. | Westendorp, Rudi G.J. | Kathiresan, Sekar | Reilly, Muredach P. | Tracy, Russell P. | Polasek, Ozren | Winkelmann, Bernhard R. | Grant, Peter J. | Hillege, Hans L. | Cambien, Francois | Stott, David J. | Lowe, Gordon D. | Spector, Timothy D. | Meigs, James B. | Marz, Winfried | Eriksson, Per | Becker, Lewis C. | Morange, Pierre-Emmanuel | Soranzo, Nicole | Williams, Scott M. | Hayward, Caroline | van der Harst, Pim | Hamsten, Anders | Lowenstein, Charles J. | Strachan, David P. | O'Donnell, Christopher J.
Objective
Tissue plasminogen activator (tPA), a serine protease, catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for endogenous fibrinolysis. In some populations, elevated plasma levels of tPA have been associated with myocardial infarction and other cardiovascular diseases (CVD). We conducted a meta-analysis of genome-wide association studies (GWAS) to identify novel correlates of circulating levels of tPA.
Approach and Results
Fourteen cohort studies with tPA measures (N=26,929) contributed to the meta-analysis. Three loci were significantly associated with circulating tPA levels (P <5.0×10−8). The first locus is on 6q24.3, with the lead SNP (rs9399599, P=2.9×10−14) within STXBP5. The second locus is on 8p11.21. The lead SNP (rs3136739, P=1.3×10−9) is intronic to POLB and less than 200kb away from the tPA encoding gene PLAT. We identified a non-synonymous SNP (rs2020921) in modest LD with rs3136739 (r2 = 0.50) within exon 5 of PLAT (P=2.0×10−8). The third locus is on 12q24.33, with the lead SNP (rs7301826, P=1.0×10−9) within intron 7 of STX2. We further found evidence for association of lead SNPs in STXBP5 and STX2 with expression levels of the respective transcripts. In in vitro cell studies, silencing STXBP5 decreased release of tPA from vascular endothelial cells, while silencing of STX2 increased tPA release. Through an in-silico lookup, we found no associations of the three lead SNPs with coronary artery disease or stroke.
Conclusions
We identified three loci associated with circulating tPA levels, the PLAT region, STXBP5 and STX2. Our functional studies implicate a novel role for STXBP5 and STX2 in regulating tPA release.
doi:10.1161/ATVBAHA.113.302088
PMCID: PMC4009733  PMID: 24578379
tissue plasminogen activator; genome-wide association study; meta-analysis; cardiovascular disease risk; fibrinolysis; hemostasis
13.  Transcriptomic profiles of aging in purified human immune cells 
BMC Genomics  2015;16(1):333.
Background
Transcriptomic studies hold great potential towards understanding the human aging process. Previous transcriptomic studies have identified many genes with age-associated expression levels; however, small samples sizes and mixed cell types often make these results difficult to interpret.
Results
Using transcriptomic profiles in CD14+ monocytes from 1,264 participants of the Multi-Ethnic Study of Atherosclerosis (aged 55–94 years), we identified 2,704 genes differentially expressed with chronological age (false discovery rate, FDR ≤ 0.001). We further identified six networks of co-expressed genes that included prominent genes from three pathways: protein synthesis (particularly mitochondrial ribosomal genes), oxidative phosphorylation, and autophagy, with expression patterns suggesting these pathways decline with age. Expression of several chromatin remodeler and transcriptional modifier genes strongly correlated with expression of oxidative phosphorylation and ribosomal protein synthesis genes. 17% of genes with age-associated expression harbored CpG sites whose degree of methylation significantly mediated the relationship between age and gene expression (p < 0.05). Lastly, 15 genes with age-associated expression were also associated (FDR ≤ 0.01) with pulse pressure independent of chronological age.
Comparing transcriptomic profiles of CD14+ monocytes to CD4+ T cells from a subset (n = 423) of the population, we identified 30 age-associated (FDR < 0.01) genes in common, while larger sets of differentially expressed genes were unique to either T cells (188 genes) or monocytes (383 genes). At the pathway level, a decline in ribosomal protein synthesis machinery gene expression with age was detectable in both cell types.
Conclusions
An overall decline in expression of ribosomal protein synthesis genes with age was detected in CD14+ monocytes and CD4+ T cells, demonstrating that some patterns of aging are likely shared between different cell types. Our findings also support cell-specific effects of age on gene expression, illustrating the importance of using purified cell samples for future transcriptomic studies. Longitudinal work is required to establish the relationship between identified age-associated genes/pathways and aging-related diseases.
Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1522-4) contains supplementary material, which is available to authorized users.
doi:10.1186/s12864-015-1522-4
PMCID: PMC4417516  PMID: 25898983
Aging; Monocyte; T cell; Transcriptome; Mitochondrial ribosome; Translation; Protein synthesis; Ribonucleoprotein complex; Oxidative phosphorylation; Autophagy; Methylation
14.  ANGIOTENSIN CONVERTING ENZYME INHIBITION AND NOVEL CARDIOVASCULAR RISK BIOMARKERS 
American heart journal  2009;157(2):334.e1-334.e8.
Background
Beneficial effects of angiotensin converting enzyme (ACE) inhibitors seem to be mediated by mechanisms that are partly independent of blood pressure lowering. The present study evaluates effects of an ACE-inhibitor (i.e. fosinopril) intervention on novel cardiovascular risk factors.
Methods
Data are from the Trial of Angiotensin Converting Enzyme Inhibition and Novel Cardiovascular Risk Factors (TRAIN), a double-blind, crossover, randomized, placebo-controlled trial enrolling subjects aged ≥55 years and older with high cardiovascular disease risk profile. Biomarkers of hemostasis (i.e. plasminogen activator inhibitor-1 [PAI-1], D-dimer), inflammation (i.e. C-reactive protein [CRP], interleukin-6 [IL-6]), and endothelial function (i.e. endothelin-1, vascular cell adhesion molecule-1 [VCAM-1]) were measured at the baseline, at the mid-term, and at end of follow-up (after one year) clinic visits. Paired t-test analyses (after Sidak’s adjustment, p value<0.009) were performed to compare biomarkers modifications after fosinopril/placebo interventions.
Results
Mean age of the sample (n=290, women 43.4%) was 66.0 years old. No significant differences were reported for CRP, IL-6, PAI-1, VCAM-1, and endothelin-1 levels in the comparisons between fosinopril and placebo interventions. D-Dimer was the only biomarker showing a significant difference between fosinopril intervention (median 0.32 [interquartile range, IQR 0.22–0.52] µg/mL) and placebo (median 0.29 [IQR 0.20–0.47] µg/mL, p=0.007) when analyses were restricted to participants with higher compliance to treatment and receiving the maximum ACE-inhibitor dosage.
Conclusions
ACE-inhibition does not significantly modify major biomarkers of inflammation, hemostasis, and endothelial function. Further studies should confirm the possible effect of ACE-inhibitors on the fibrinolysis pathway.
doi:10.1016/j.ahj.2008.10.026
PMCID: PMC4384444  PMID: 19185642
ACE-inhibition; inflammation; clinical trial; coagulation/thrombosis; endothelium; clinical science; antihypertensive drug
15.  Monthly hemostatic factor variability in women and men 
Background
Hormonal status influences hemostatic factors including fibrinogen, factor VII and plasminogen activator inhibitor (PAI-1), and concentrations differ among men, premenopausal and postmenopausal women. This study examines how phases of the menstrual cycle influence variability of fibrinogen, factor VII and PAI-1.
Design
We studied 103 subjects (39 premenopausal women, 18 postmenopausal women, and 46 men) during three, randomized, 8-week energy and nutrient-controlled experimental diets in the DELTA (Dietary Effects on Lipids and Thrombotic Activity) Study. Fasting blood samples were collected weekly during the last four weeks of each diet period and hemostatic factors were quantified. Two linear mixed-effects models were used for fibrinogen, factor VII and PAI-1: one to estimate and compare group-specific components of variance, the other to estimate additional fixed effects representing cyclical functions of day of menstrual cycle in premenopausal women.
Results
Systematic cyclical variation with day of menstrual cycle was observed for fibrinogen (p<0.0001), factor VII (p=0.0012), and PAI-1 (p=0.0024) in premenopausal women. However, the amplitude of cycling was small relative to the total magnitude of intra-individual variability. In addition, the intra-individual variance and corresponding coefficient of variation observed in premenopausal women did not differ from postmenopausal women and men.
Conclusions
The variability in hemostatic factors in premenopausal women is no greater than for postmenopausal women or men. Consequently, premenopausal women can be included in studies investigating hemostatic factor responses without controlling for stage of menstrual cycle.
doi:10.1111/eci.12235
PMCID: PMC4153833  PMID: 24382103
menstrual cycle; fibrinogen; factor VII; plasminogen activator inhibitor; controlled dietary intervention
16.  CD8+ T-Cells Count in Acute Myocardial Infarction in HIV Disease in a Predominantly Male Cohort 
BioMed Research International  2015;2015:246870.
Human Immunodeficiency Virus- (HIV-) infected persons have a higher risk for acute myocardial infarction (AMI) than HIV-uninfected persons. Earlier studies suggest that HIV viral load, CD4+ T-cell count, and antiretroviral therapy are associated with cardiovascular disease (CVD) risk. Whether CD8+ T-cell count is associated with CVD risk is not clear. We investigated the association between CD8+ T-cell count and incident AMI in a cohort of 73,398 people (of which 97.3% were men) enrolled in the U.S. Veterans Aging Cohort Study-Virtual Cohort (VACS-VC). Compared to uninfected people, HIV-infected people with high baseline CD8+ T-cell counts (>1065 cells/mm3) had increased AMI risk (adjusted HR = 1.82, P < 0.001, 95% CI: 1.46 to 2.28). There was evidence that the effect of CD8+ T-cell tertiles on AMI risk differed by CD4+ T-cell level: compared to uninfected people, HIV-infected people with CD4+ T-cell counts ≥200 cells/mm3 had increased AMI risk with high CD8+ T-cell count, while those with CD4+ T-cell counts <200 cells/mm3 had increased AMI risk with low CD8+ T-cell count. CD8+ T-cell counts may add additional AMI risk stratification information beyond that provided by CD4+ T-cell counts alone.
doi:10.1155/2015/246870
PMCID: PMC4320893  PMID: 25688354
17.  Relation of Plasma Total and High-Molecular-Weight Adiponectin to New-Onset Heart Failure in Adults ≥ 65 Years of Age (From the Cardiovascular Health Study) 
The American journal of cardiology  2013;113(2):328-334.
Adiponectin exhibits cardioprotective properties in experimental studies, but elevated levels have been linked to increased mortality in older adults and patients with chronic heart failure (HF). The adipokine’s association with new-onset HF remains less well defined. We investigated the associations of total and HMW adiponectin with incident HF (n=780) and, in a subset, echocardiographic parameters in a community-based cohort of adults 65 and older. Total and high molecular weight (HMW) adiponectin were measured in 3,228 subjects without prevalent HF or CVD. The relationships of total and HMW adiponectin with HF were nonlinear, with significant associations observed only above their medians (12.4 and 6.2 mg/L, respectively). After adjustment for potential confounders, the hazard ratios (HR) per standard deviation (SD) increment in total adiponectin were 0.93 (95% confidence interval [CI]=0.72–1.21) below the median and 1.25 (95% CI=1.14–1.38) above it. There was a suggestion of effect modification by body mass index (BMI), whereby the association appeared strongest among participants with lower BMIs. Consistent with the HF findings, higher adiponectin tended to be associated with left ventricular systolic dysfunction and left atrial enlargement. Results were similar for HMW adiponectin. In conclusion, total and HMW adiponectin showed comparable relationships with incident HF in this older cohort, with a threshold effect of increasing risk occurring at their median concentrations. High levels of adiponectin may mark or mediate age-related processes that lead to HF in older adults.
doi:10.1016/j.amjcard.2013.09.027
PMCID: PMC3968249  PMID: 24169012
Adiponectin; Aging; Heart Failure
18.  A variational Bayes discrete mixture test for rare variant association 
Genetic epidemiology  2014;38(1):21-30.
Recently, many statistical methods have been proposed to test for associations between rare genetic variants and complex traits. Most of these methods test for association by aggregating genetic variations within a predefined region, such as a gene. Although there is evidence that “aggregate” tests are more powerful than the single marker test, these tests generally ignore neutral variants and therefore are unable to identify specific variants driving the association with phenotype. We propose a novel aggregate rare-variant test that explicitly models a fraction of variants as neutral, tests associations at the gene-level, and infers the rare-variants driving the association. Simulations show that in the practical scenario where there are many variants within a given region of the genome with only a fraction causal our approach has greater power compared to other popular tests such as the Sequence Kernel Association Test (SKAT), the Weighted Sum Statistic (WSS), and the collapsing method of Morris and Zeggini (MZ). Our algorithm leverages a fast variational Bayes approximate inference methodology to scale to exome-wide analyses, a significant computational advantage over exact inference model selection methodologies. To demonstrate the efficacy of our methodology we test for associations between von Willebrand Factor (VWF) levels and VWF missense rare-variants imputed from the National Heart, Lung, and Blood Institute’s Exome Sequencing project into 2,487 African Americans within the VWF gene. Our method suggests that a relatively small fraction (~10%) of the imputed rare missense variants within VWF are strongly associated with lower VWF levels in African Americans.
PMCID: PMC4030763  PMID: 24482836
Exome sequencing study; approximate inference; von Willebrand Factor genetics
19.  Methylomics of gene expression in human monocytes 
Human Molecular Genetics  2013;22(24):5065-5074.
DNA methylation is one of several epigenetic mechanisms that contribute to the regulation of gene expression; however, the extent to which methylation of CpG dinucleotides correlates with gene expression at the genome-wide level is still largely unknown. Using purified primary monocytes from subjects in a large community-based cohort (n = 1264), we characterized methylation (>485 000 CpG sites) and mRNA expression (>48K transcripts) and carried out genome-wide association analyses of 8370 expression phenotypes. We identified 11 203 potential cis-acting CpG loci whose degree of methylation was associated with gene expression (eMS) at a false discovery rate threshold of 0.001. Most of the associations were consistent in effect size and direction of effect across sex and three ethnicities. Contrary to expectation, these eMS were not predominately enriched in promoter regions, or CpG islands, but rather in the 3′ UTR, gene bodies, CpG shores or ‘offshore’ sites, and both positive and negative correlations between methylation and expression were observed across all locations. eMS were enriched for regions predicted to be regulatory by ENCODE (Encyclopedia of DNA Elements) data in multiple cell types, particularly enhancers. One of the strongest association signals detected (P < 2.2 × 10−308) was a methylation probe (cg17005068) in the promoter/enhancer region of the glutathione S-transferase theta 1 gene (GSTT1, encoding the detoxification enzyme) with GSTT1 mRNA expression. Our study provides a detailed description of the epigenetic architecture in human monocytes and its relationship to gene expression. These data may help prioritize interrogation of biologically relevant methylation loci and provide new insights into the epigenetic basis of human health and diseases.
doi:10.1093/hmg/ddt356
PMCID: PMC3836482  PMID: 23900078
20.  CPAP versus Oxygen in Obstructive Sleep Apnea 
The New England journal of medicine  2014;370(24):2276-2285.
Background
Obstructive sleep apnea is associated with hypertension, inflammation, and increased cardiovascular risk. Continuous positive airway pressure (CPAP) reduces blood pressure, but adherence is often suboptimal, and the benefit beyond management of conventional risk factors is uncertain. Since intermittent hypoxemia may underlie cardiovascular sequelae of sleep apnea, we evaluated the effects of nocturnal supplemental oxygen and CPAP on markers of cardiovascular risk.
Methods
We conducted a randomized, controlled trial in which patients with cardiovascular disease or multiple cardiovascular risk factors were recruited from cardiology practices. Patients were screened for obstructive sleep apnea with the use of the Berlin questionnaire, and home sleep testing was used to establish the diagnosis. Participants with an apnea–hypopnea index of 15 to 50 events per hour were randomly assigned to receive education on sleep hygiene and healthy lifestyle alone (the control group) or, in addition to education, either CPAP or nocturnal supplemental oxygen. Cardiovascular risk was assessed at baseline and after 12 weeks of the study treatment. The primary outcome was 24-hour mean arterial pressure.
Results
Of 318 patients who underwent randomization, 281 (88%) could be evaluated for ambulatory blood pressure at both baseline and follow-up. On average, the 24-hour mean arterial pressure at 12 weeks was lower in the group receiving CPAP than in the control group (−2.4 mm Hg; 95% confidence interval [CI], −4.7 to −0.1; P = 0.04) or the group receiving supplemental oxygen (−2.8 mm Hg; 95% CI, −5.1 to −0.5; P = 0.02). There was no significant difference in the 24-hour mean arterial pressure between the control group and the group receiving oxygen. A sensitivity analysis performed with the use of multiple imputation approaches to assess the effect of missing data did not change the results of the primary analysis.
Conclusions
In patients with cardiovascular disease or multiple cardiovascular risk factors, the treatment of obstructive sleep apnea with CPAP, but not nocturnal supplemental oxygen, resulted in a significant reduction in blood pressure. (Funded by the National Heart, Lung, and Blood Institute and others; HeartBEAT ClinicalTrials.gov number, NCT01086800.)
doi:10.1056/NEJMoa1306766
PMCID: PMC4172401  PMID: 24918372
21.  Do Differences in Risk Factors Explain the Lower Rates of Coronary Heart Disease in Japanese Versus U.S. Women? 
Journal of Women's Health  2013;22(11):966-977.
Abstract
Background
Mortality from coronary heart disease (CHD) in women in Japan is one of the lowest in developed countries. In an attempt to shed some light on possible reasons of lower CHD in women in Japan compared with the United States, we extensively reviewed and analyzed existing national data and recent literature.
Methods
We searched recent epidemiological studies that reported incidence of acute myocardial infarction (AMI) and examined risk factors for CHD in women in Japan. Then, we compared trends in risk factors between women currently aged 50–69 years in Japan and the United States, using national statistics and other available resources.
Results
Recent epidemiological studies have clearly shown that AMI incidence in women in Japan is lower than that reported from other countries, and that lipids, blood pressure (BP), diabetes, smoking, and early menopause are independent risk factors. Comparing trends in risk factors between women in Japan and the United States, current levels of serum total cholesterol are higher in women in Japan and levels have been similar at least since 1990. Levels of BP have been higher in in Japan for the past 3 decades. Prevalence of type 2 diabetes has been similar in Japanese and white women currently aged 60–69 for the past 2 decades. In contrast, rates of cigarette smoking, although low in women in both countries, have been lower in women in Japan.
Conclusions
Differences in risk factors and their trends are unlikely to explain the difference in CHD rates in women in Japan and the United States. Determining the currently unknown factors responsible for low CHD mortality in women in Japan may lead to new strategy for CHD prevention.
doi:10.1089/jwh.2012.4087
PMCID: PMC3820126  PMID: 24073782
22.  Common FABP4 Genetic Variants and Plasma Levels of Fatty Acid Binding Protein 4 in Older Adults 
Lipids  2013;48(11):10.1007/s11745-013-3838-7.
We examined common variants in the fatty acid binding protein 4 gene (FABP4) and plasma levels of FABP4 in adults aged 65 and older from the Cardiovascular Health Study. We genotyped rs16909187, rs1054135, rs16909192, rs10808846, rs7018409, rs2290201, and rs6992708 and measured circulating FABP4 levels among 3190 European Americans and 660 African Americans. Among European Americans, the minor alleles of six single nucleotide polymorphisms (SNP) were associated with lower FABP4 levels (all p ≤ 0.01). Among African Americans, the SNP with the lowest minor allele frequency was associated with lower FABP4 levels (p = 0.015). The C-A haplotype of rs16909192 and rs2290201 was associated with lower FABP4 levels in both European Americans (frequency = 16 %; p = 0.001) and African Americans (frequency = 8 %; p = 0.04). The haplotype combined a SNP in the first intron with one in the 3′untranslated region. However, the alleles associated with lower FABP4 levels were associated with higher fasting glucose in meta-analyses from the MAGIC consortium. These results demonstrate associations of common SNP and haplotypes in the FABP4 gene with lower plasma FABP4 but higher fasting glucose levels.
doi:10.1007/s11745-013-3838-7
PMCID: PMC3883501  PMID: 24043587
Fatty acid binding proteins; Metabolism; Genetics
23.  Increase in 2–Long Terminal Repeat Circles and Decrease in D-dimer After Raltegravir Intensification in Patients With Treated HIV Infection: A Randomized, Placebo-Controlled Trial 
The Journal of Infectious Diseases  2013;208(9):1436-1442.
Background. The degree to which human immunodeficiency virus (HIV) continues to replicate during antiretroviral therapy (ART) is controversial. We conducted a randomized, double-blind, placebo-controlled study to assess whether raltegravir intensification reduces low-level viral replication, as defined by an increase in the level of 2–long terminal repeat (2-LTR) circles.
Methods. Thirty-one subjects with an ART-suppressed plasma HIV RNA level of <40 copies/mL and a CD4+ T-cell count of ≥350 cells/mm3 for ≥1 year were randomly assigned to receive raltegravir 400 mg twice daily or placebo for 24 weeks. 2-LTR circles were analyzed by droplet digital polymerase chain reaction at weeks 0, 1, 2, and 8.
Results. The median duration of ART suppression was 3.8 years. The raltegravir group had a significant increase in the level of 2-LTR circles, compared to the placebo group. The week 1 to 0 ratio was 8.8-fold higher (P = .0025) and the week 2 to 0 ratio was 5.7-fold higher (P = .023) in the raltegravir vs. placebo group. Intensification also led to a statistically significant decrease in the D-dimer level, compared to placebo (P = .045).
Conclusions. Raltegravir intensification resulted in a rapid increase in the level of 2-LTR circles in a proportion of subjects, indicating that low-level viral replication persists in some individuals even after long-term ART. Intensification also reduced the D-dimer level, a coagulation biomarker that is predictive of morbidity and mortality among patients receiving treatment for HIV infection.
doi:10.1093/infdis/jit453
PMCID: PMC3789577  PMID: 23975885
HIV; raltegravir intensification; 2-LTR circles; ongoing viral replication; D-dimer
24.  T Helper Cell Polarization in Healthy People: Implications for Cardiovascular Disease 
Atherosclerosis is a chronic inflammatory disease characterized by T lymphocyte infiltration into the atherosclerotic plaque. Assessments of T cell subtypes have demonstrated a predominance of CD4+ T helper (Th) cells, implicated Th1 and Th17 immunity in both human and mouse atherogenesis, and provided some evidence suggesting protective roles of Th2 and T regulatory cells. Observations that certain inbred mouse strains have an inherent T helper bias suggests a genetic predisposition toward developing a particular T helper phenotype. This review summarizes our current understanding of mechanisms of antigen processing for major histocompatibility complex (MHC) molecules, describes the different T helper cell subsets and their roles in atherosclerosis, and discusses mechanisms of genetic predisposition toward Th1/Th2 bias in mice. We also present data from our laboratory demonstrating inherent Th1/Th2 phenotypes in apparently healthy human volunteers that are stable over time, and discuss the potential implications for cardiovascular disease.
doi:10.1007/s12265-013-9496-6
PMCID: PMC3806306  PMID: 23921946
Atherosclerosis; cardiovascular disease; CD4+ lymphocyte; T helper cell; immunology; inflammation; immunoglobulin
25.  HIV Infection and Cardiovascular Disease in Women 
Background
HIV infection is associated with increased risk of cardiovascular disease (CVD) in men. Whether HIV is an independent risk factor for CVD in women has not yet been established.
Methods and Results
We analyzed data from the Veterans Aging Cohort Study on 2187 women (32% HIV infected [HIV+]) who were free of CVD at baseline. Participants were followed from their first clinical encounter on or after April 01, 2003 until a CVD event, death, or the last follow‐up date (December 31, 2009). The primary outcome was CVD (acute myocardial infarction [AMI], unstable angina, ischemic stroke, and heart failure). CVD events were defined using clinical data, International Classification of Diseases, Ninth Revision, Clinical Modification codes, and/or death certificate data. We used Cox proportional hazards models to assess the association between HIV and incident CVD, adjusting for age, race/ethnicity, lipids, smoking, blood pressure, diabetes, renal disease, obesity, hepatitis C, and substance use/abuse. Median follow‐up time was 6.0 years. Mean age at baseline of HIV+ and HIV uninfected (HIV−) women was 44.0 versus 43.2 years (P<0.05). Median time to CVD event was 3.1 versus 3.7 years (P=0.11). There were 86 incident CVD events (53%, HIV+): AMI, 13%; unstable angina, 8%; ischemic stroke, 22%; and heart failure, 57%. Incident CVD/1000 person‐years was significantly higher among HIV+ (13.5; 95% confidence interval [CI]=10.1, 18.1) than HIV− women (5.3; 95% CI=3.9, 7.3; P<0.001). HIV+ women had an increased risk of CVD, compared to HIV− (hazard ratio=2.8; 95% CI=1.7, 4.6; P<0.001).
Conclusions
HIV is associated with an increased risk of CVD in women.
doi:10.1161/JAHA.114.001035
PMCID: PMC4323817  PMID: 25324353
AIDS; CVD risk factors; Women

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