Previous studies have shown that ATP-binding cassette transporter 1 (ABCA1) polymorphisms associated with increased ABCA1 expression result in increased small HDL (high density lipoprotein) subclass particle concentration. The present study examines the effect of treatment with fenofibrate, a drug known to bind peroxisome proliferator-activated receptor alpha (PPARα) which increases the expression of ABCA1 gene, on lipoprotein subclass profiles of individuals stratified by ABCA1 genotypes.
Participants of Genetics of Lipid-lowering Drugs and Diet Network (GOLDN) were treated with fenofibrate over a three week period. We analyzed six ABCA1 polymorphisms in 287 GOLDN participants with triglyceride concentrations ≥ 150 mg/dL and studied their associations with HDL subclass particle concentrations, as measured by nuclear magnetic resonance spectroscopy, before and after treatment.
Fenofibrate treatment did not result in significant changes in small HDL subclass particle concentration. When changes in HDL subclasses were stratified by ABCA1 polymorphism genotypes, there were no statistically significant associations between ABCA1 genotypes and small HDL subclasses before fenofibrate treatment. However, after fenofibrate treatment the KK genotype of R1587K (mean 4.40 μmol/L; p = 0.004) and the RK genotype of R219K (mean 1.60 μmol/L; p = 0.02) polymorphisms were associated with significantly increased small HDL. The R1587K KK genotype (mean 4.80 μmol/L; p = 0.0002) and the R219K KK genotype (mean 2.50 μmol/L; p = 0.02) were also associated with increased HDL particle concentrations.
There is a synergistic effect between ABCA1 polymorphisms and fenofibrate. Thus our study indirectly confirms the role of fenofibrate and genotype in increasing cholesterol efflux, as evidenced by increased small HDL particles.
ABCA1; cardiovascular disease; fenofibrate; lipoprotein; lipoprotein particle size
Despite evidence in support of anti-inflammatory and triglyceride-lowering effects of fenofibrate, little is known about genetic determinants of the observed heterogeneity in treatment response. This study provides the first genome-wide examination of fenofibrate effects on systemic inflammation.
Biomarkers of inflammation were measured in participants of the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN, n=1092) before and after a 3-week daily treatment with 160 mg of fenofibrate. Two inflammatory patterns (hsCRP-IL6 and MCP1-TNF-α) were derived using principal component analysis. Associations between single nucleotide polymorphisms on the Affymetrix 6.0 chip and phenotypes were assessed using mixed linear models, adjusted for age, sex, study center, and ancestry as fixed effects and pedigree as a random effect.
Before fenofibrate treatment, the strongest evidence for association was observed for polymorphisms near or within the IL2RA gene with the hsCRP-IL6 pattern (rs7911500, P=5×10−9 and rs12722605, P=5×10−8). Associations of the MCP1-TNF-α pattern with loci in several biologically plausible genes (CYP4F8 (rs3764563), APBB1IP (rs1775246), COL13A1 (rs2683572), and COMMD10 (rs1396485)) approached genome-wide significance (P=3×10−7, 5×10−7, 6×10−7, and 7×10−7 respectively) before fenofibrate treatment. After fenofibrate treatment, the rs12722605 locus in IL2RA was also associated with the MCP1-TNF-α pattern (P=3×10−7). The analyses of individual biomarker response to fenofibrate did not yield genome-wide significant results, but the rs6517147 locus near the immunologically relevant IFNAR2 gene was suggestively associated with IL6 (P=7×10−7).
We have identified several novel biologically relevant loci associated with systemic inflammation before and after fenofibrate treatment.
fenofibrate; inflammation; genome-wide association study
Elevated plasma concentration of total homocysteine (tHcy) has been linked with many diseases. tHcy is associated with a variety of factors, including polymorphisms in genes involved in homocysteine metabolism. It is not clear whether US-mandated fortification of grain products with folic acid has affected the association of genetic variants with tHcy levels. We determined tHcy concentrations in sera from 997 Caucasians and 692 African Americans participants in the Coronary Artery Risk Development in Young Adults (CARDIA) study before and after folic acid fortification. DNA was genotyped for variants present in four genes involved in homocysteine metabolism: cystathionine β-synthase (CBS) 844ins68, methionine synthase (MS) 2756A>G; methionine synthase reductase (MTRR) 66A>G, and methylenetetrahydrofolate reductase (MTHFR) 677C>T and 1298A>C. A greater number of African Americans were homozygous for the MS 2756GG, MTRR 66GG and CBS 844ins68 genotypes compared to Caucasians, while prevalence of MTHFR 677TT and 1298CC genotypes was substantially lower in African Americans compared to Caucasians. The overall variance in tHcy levels at y 0, 7, and 15 that can be explained by the combined presence of all five variants increased slightly over time in Caucasians (17%, y 0; 21%, y 7 and 26%, y 15) and in African Americans (13%, y 0; 17% y 7; 18% y 15) largely due to decrease in tHcy variance.
Cystathionine B-synthase; folic acid; homocysteine; methylenetetrahydrofolate reductase; methionine synthase; methionine synthase reductase
Although numerous candidate gene and genome-wide association studies have been performed on blood pressure, a small number of regulating genetic variants having a limited effect have been identified. This phenomenon can partially be explained by possible gene-gene/epistasis interactions that were little investigated so far.
We performed a pre-planned two-phase investigation: in phase 1, one hundred single nucleotide polymorphisms (SNPs) in 65 candidate genes were genotyped in 1,912 French unrelated adults in order to study their two-locus combined effects on blood pressure (BP) levels. In phase 2, the significant epistatic interactions observed in phase 1 were tested in an independent population gathering 1,755 unrelated European adults.
Among the 9 genetic variants significantly associated with systolic and diastolic BP in phase 1, some may act through altering the corresponding protein levels: SNPs rs5742910 (Padjusted≤0.03) and rs6046 (Padjusted =0.044) in F7 and rs1800469 (Padjusted ≤0.036) in TGFB1; whereas some may be functional through altering the corresponding protein structure: rs1800590 (Padjusted =0.028, SE=0.088) in LPL and rs2228570 (Padjusted ≤9.48×10-4) in VDR. The two epistatic interactions found for systolic and diastolic BP in the discovery phase: VCAM1 (rs1041163) * APOB (rs1367117), and SCGB1A1 (rs3741240) * LPL (rs1800590), were tested in the replication population and we observed significant interactions on DBP. In silico analyses yielded putative functional properties of the SNPs involved in these epistatic interactions trough the alteration of corresponding protein structures.
These findings support the hypothesis that different pathways and then different genes may act synergistically in order to modify BP. This could highlight novel pathophysiologic mechanisms underlying hypertension.
Blood pressure; Epistasis; Single nucleotide polymorphism; Epidemiology
Trans fatty acids (TFA) lower HDL and increase triglyceride concentrations while polyunsaturated fatty acids (PUFA) lower triglycerides and may decrease HDL concentrations. The effect of the interaction between trans fat and PUFA on lipids is uncertain.
Men and women (n = 1032) in the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) study were included. Fatty acids in erythrocyte membranes were measured with gas chromatography while data on potential confounders were obtained from questionnaires. To test the interaction between total erythrocyte PUFA (ePUFA) and TFA (eTFA) on lipid concentrations we distributed eTFA into tertiles and dichotomized ePUFA at the median concentration.
For the 1st, 2nd and 3rd tertiles of eTFA, multivariate-adjusted means±s.e.m for HDL were 46.2±1.1, 46.3±1.1 and 45.5±1.0 mg/dL among those with low ePUFA, respectively, while they were 50.0±1.1, 46.9±1.1 and 44.7±1.1 mg/dL among those with high ePUFA, respectively (P for interaction = 0.01). For the 1st, 2nd and 3rd tertiles of eTFA, multivariate-adjusted means±s.e.m for triglycerides were 178.6±11.3, 144.7±10.9 and 140.8±10.6, respectively, among those with low ePUFA, while they were 133.8±11.3, 145.7±10.9 and 149.3±11.5, respectively, among those with high ePUFA (P for interaction = 0.005). Results for VLDL were similar to those for triglycerides. No significant interactions were observed for LDL or total cholesterol.
The relation between trans fat and HDL, VLDL and triglycerides may depend on PUFA. The benefit of avoiding trans fat may be greater among individuals with higher PUFA intake. Supplementation with PUFA among individuals with relatively high trans fat intake may have limited benefits on lipid profiles.
High levels of lipoprotein-associated phospholipase A2 (Lp-PLA2) are associated with inflammation, atherosclerosis, and CHD events. In addition, Lp-PLA2 has been linked to classical markers of endothelial activation, including soluble vascular cell adhesion molecule-1 (sVCAM-1). Though treatment with fenofibrate reduces Lp-PLA2 mass, it is unclear whether fenofibrate reduces sVCAM-1 levels or whether there is an association between any changes observed in Lp-PLA2 and sVCAM-1.
Concentrations of Lp-PLA2 mass and sVCAM-1 levels were measured in plasma at baseline and after 3 weeks of fenofibrate treatment (160 mg/d) in 96 hypertriglyceridemic participants of the Genetics of Lipid-lowering Drugs and Diet Network (GOLDN) study.
Lp-PLA2 and sVCAM-1 were stratified by tertiles as determined by baseline levels of the respective target. Fenofibrate treatment resulted in increases of 30.1% in Lp-PLA2 mass (p=0.0003) and 14.7% in sVCAM-1 levels (p=0.0096), but only in tertile1 of either target. In contrast, Lp-PLA2 mass was reduced by 35.3 % (p<0.0001) in tertile 3. Soluble VCAM-1 levels were significantly reduced by 7.74% (p=0.0109) and 17.2% (p<0.0001) in tertiles 2 and 3, respectively. No associations were observed between Lp-PLA2 and sVCAM-1 at baseline or post-treatment.
In conclusion, fenofibrate treatment in hypertriglyceridemic subjects reduced levels of LpPLA2 mass and sVCAM-1, but only in those with elevated baseline levels of these biomarkers. The greatest reductions in LpPLA2 levels were observed in individuals with LpPLA2 concentrations indicative of increased CVD risk (>200 ng/mL).
Fenofibrate; atherosclerosis; VCAM; Lp-PLA; triglyceride; GOLDN
Cohort studies typically sample unrelated individuals from a population, although family members of index cases may be also be recruited to investigate shared familial risk factors. Recruitment of family members may be incomplete or ancillary to the main cohort, resulting in a mixed sample of independent family units, including unrelated singletons and multiplex families. Multiple methods are available to perform genome wide association (GWA) analysis of binary or continuous traits in families, but it is unclear whether methods known to perform well on ascertained pedigrees, sib-ships, or trios are appropriate in analysis of a mixed unrelated cohort and family sample.
We present simulation studies based on Multi-Ethnic Study of Atherosclerosis (MESA) pedigree structures to compare the performance of several popular methods of GWA analysis for both quantitative and dichotomous traits in cohort studies. We evaluate approaches suitable for analysis of families, and combined the best performing methods with population-based samples either by meta-analysis, or by pooled analysis of family- and population-based samples (mega-analysis), comparing type 1 error and power. We further assess practical considerations, such as availability of software and ability to incorporate covariates in statistical modeling, and demonstrate our recommended approaches through quantitative and binary trait analysis of HDL cholesterol (HDL-C) in 2,553 MESA family- and population-based African-American samples. Our results suggest linear modeling approaches that accommodate family-induced phenotypic correlation (e.g., variance component model for quantitative traits or generalized estimating equations for dichotomous traits) perform best in the context of combined family- and population-based cohort GWAS.
genome-wide association study (GWAS); cohort study; simulation study; generalized estimating equations (GEE); variance component model; family-based association
Recent cross-sectional studies have reported an association between retinal vessel caliber and chronic kidney disease (CKD), but the direction of the association between these two processes is not clear. In a prospective study with multiple measurements of retinal vessel diameters and serum creatinine, we examined if baseline retinal vessel diameters are associated with future risk of CKD, or vice versa.
Population-based cohort study
Setting and participants
3,199 Wisconsin adults aged 43-84 years who were followed prospectively for 15 years.
Baseline retinal arteriolar and venular diameters for analysis 1, and baseline estimated glomerular filtration rate (eGFR) categories for analysis 2.
Outcomes and measurements
For analysis 1, incident CKD defined as eGFR <60 mL/min/1.73m2 accompanied by a 25% decrease in eGFR during follow up. For analysis 2, incident retinal arteriolar narrowing defined as a central retinal arteriolar equivalent measurement of <144.0μm and incident retinal venular dilation defined as a central retinal venular equivalent measurement of >243.8μm.
Baseline retinal arteriolar and venular diameters were not found to be associated with the 15-year risk of incident CKD. After adjustment for age, sex, diabetes, hypertension and other confounders, the multivariable hazard ratio (HR) (95% confidence interval (CI) of incident CKD comparing the narrowest with the widest quartile was 1.15 (0.74-1.80) for retinal arteriolar and 1.05 (0.67-1.67) for retinal venular diameter. Similarly, there was no significant association between eGFR and 15-year risk of incident retinal arteriolar narrowing or retinal venular widening. Compared to eGFR >90 mL/min/1.73m2 (referent), the multivariable HR (95% CI) among those with eGFR <45 mL/min/1.73m2 was 1.66 (0.93-2.96) for incident retinal arteriolar narrowing and 0.60 (0.17-1.85) for retinal venular widening.
Lack of data on albuminuria and loss to follow-up.
Retinal vessel diameters and CKD may run together through shared mechanisms but are not causally related.
Retinal arteriolar diameter; retinal venular diameter; retinal vessel diameter; chronic kidney disease; eGFR; CKD; glomerular filtration rate
Macronutrient intakes and genetic variants have been shown to interact to alter the risk of insulin resistance, but replication of gene-nutrient interactions across independent populations may be difficult to achieve. Saturated fat and carbohydrate were previously shown to interact with genotype for insulin resistance for a variant of perilipin (PLIN), the major adipocyte-associated protein and a regulator of adipocyte metabolism. We investigated the same interaction for PLIN 11482G>A (rs894160) on insulin resistance in US men(n=462) and women(n=508) (mean ±SD, 49±16 years). In multivariate linear regression models, we found a significant (P<0.05) interaction between the ratio of saturated fat to carbohydrate intake as a continuous variable and PLIN 11482G>A for HOMA-IR (homeostasis model assessment of insulin resistance) in women. For carriers of the minor allele but not for non-carriers, as the ratio of saturated fat to carbohydrate intake increased, predicted HOMA-IR increased significantly (P=0.002). By dichotomizing the ratio of saturated fat to carbohydrate intake into high and low, we found significant interaction terms for insulin and HOMA-IR (P<0.05). When the ratio of saturated fat to carbohydrate was high, insulin and HOMA-IR were higher in minor allele carriers (P=0.004 and P=0.003, respectively), but did not differ when the ratio was low. Similar patterns or trends were observed when saturated fat and carbohydrate were dichotomized into high and low as individual macronutrients. Replication of the previously reported interaction between macronutrient intakes and PLIN genotype for insulin resistance reinforces the potential usefulness of applying genotype information in the dietary management of insulin resistance.
Fenofibrate significantly reduces circulating triglyceride (TG) concentrations, particularly in individuals with elevated levels. The purpose of the current study was to determine whether fenofibrate treatment reduces markers of oxidative stress, oxidized low density lipoprotein (ox-LDL) and 8-isoprostane (8-isoP), in a manner similar to TG where those with the highest levels show the greatest reductions.
The concentrations of TG, 8-isoP, and ox-LDL were measured in plasma before and after 3 weeks of fenofibrate treatment (160 mg/d) in a sub-cohort (n=187) of the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study.
Data were divided into tertiles as determined by pre-treatment values of the respective target. Fenofibrate treatment resulted in significant reductions in TG concentrations by 24.2% (p<0.0001), 41.9% (p<0.0001), and 46.6% (p<0.0001) in tertiles 1, 2, and 3, respectively. Significant reductions were also observed in ox-LDL of 7.2% (p=0.0096), 8.5% (p=0.0019) and 12.1% (p<0.0001) in tertiles 1, 2, and 3, respectively. Finally, fenofibrate treatment resulted in a 32.7% increase (p=0.0201) in 8-isoP levels in tertile 1, but a significant decrease of 34.4% (p<0.0001) in tertile 3.
This study is the largest to date to demonstrate that fenofibrate reduces oxidative stress and the first to show a suppressive effect on 8-isoP levels in individuals with a high oxidative burden following short term (3 wk) drug therapy. Those with the highest baseline levels of ox-LDL and 8-isoP showed the greatest reductions following fenofibrate treatment. Given the role of oxidative stress in atherosclerosis and coronary heart disease, our observations may partially explain the efficacy of fenofibrate in reducing cardiovascular events in select patients.
Fenofibrate; atherosclerosis; isoprostane; ox-LDL; triglyceride; GOLDN
In animal models, inflammatory processes have been shown to have an important role in the development of kidney disease. In humans, however, the independent relation between markers of inflammation and the risk of chronic kidney disease (CKD) is not known. To clarify this, we examined the relationship of several inflammatory biomarker levels (high-sensitivity C-reactive protein, tumor necrosis factor-α receptor 2, white blood cell count, and interleukin-6) with the risk of developing CKD in a population-based cohort of up to 4926 patients with 15 years of follow-up. In cross-sectional analyses, we found that all these inflammation markers were positively associated with the outcome of interest, prevalent CKD. However, in longitudinal analyses examining the risk of developing incident CKD among those who were CKD-free at baseline, only tumor necrosis factor-α receptor 2, white blood cell count, and interleukin-6 levels (hazard ratios comparing highest with the lowest tertile of 2.10, 1.90, and 1.45, respectively), and not C-reactive protein (hazard ratio 1.09), were positively associated with incident CKD. Thus, elevations of most markers of inflammation predict the risk of developing CKD. Each marker should be independently verified.
chronic kidney disease; CRP; inflammation; tumor necrosis factor-alpha
The presence of smaller low-density lipoproteins (LDL) has been associated with atherosclerosis risk, and the insulin resistance (IR) underlying the metabolic syndrome (MetS). In addition, some research has supported the association of very low-, low- and high-density lipoprotein (VLDL HDL) particle diameters with components of the metabolic syndrome (MetS), although this has been the focus of less research. We aimed to explore the relationship of VLDL, LDL and HDL diameters to MetS and its features, and by clustering individuals by their diameters of VLDL, LDL and HDL particles, to capture information across all three fractions of lipoprotein into a unified phenotype.
We used nuclear magnetic resonance spectroscopy measurements on fasting plasma samples from a general population sample of 1,036 adults (mean ± SD, 48.8 ± 16.2 y of age). Using latent class analysis, the sample was grouped by the diameter of their fasting lipoproteins, and mixed effects models tested whether the distribution of MetS components varied across the groups.
Eight discrete groups were identified. Two groups (N = 251) were enriched with individuals meeting criteria for the MetS, and were characterized by the smallest LDL/HDL diameters. One of those two groups, one was additionally distinguished by large VLDL, and had significantly higher blood pressure, fasting glucose, triglycerides, and waist circumference (WC; P < .001). However, large VLDL, in the absence of small LDL and HDL particles, did not associate with MetS features. These associations held after additionally controlling for VLDL, LDL and HDL particle concentrations.
While small LDL diameters remain associated with IR and the MetS, the occurrence of these in conjunction with a shift to overall larger VLDL diameter may identify those with the highest fasting glucose, TG and WC within the MetS. If replicated, the association of this phenotype with more severe IR-features indicated that it may contribute to identifying of those most at risk for incident type II diabetes and cardiometabolic disease.
lipoprotein particle diameter; insulin resistance; nuclear resonance spectroscopy; Metabolic Syndrome; latent class analysis; GOLDN; waist circumference; hypertension; hypertriglyceridemia; fasting glucose
Postprandial lipemia (PPL) is likely a risk factor for cardiovascular disease but these changes have not been well described and characterized in a large cohort. We assessed acute changes in the size and concentration of total and subclasses of LDL, HDL, and VLDL particles in response to a high-fat meal. Participants (n = 1048) from the Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) Study who ingested a high-fat meal were included in this analysis. Lipids were measured at 0 hr (fasting), 3.5 hr, and 6 hr after a standardized fat meal. Particle size distributions were determined using nuclear magnetic resonance spectroscopy. Analyses were stratified by baseline triglycerides (normal vs. elevated) and gender. The effect of PPL on changes in lipoprotein subclasses was assessed using repeated measures ANOVA.
Postprandially, LDL-C, HDL-C, VLDL-C, and triglycerides increased regardless of baseline triglyceride status, with the largest increases in VLDL-C and TG; however, those with elevated triglycerides demonstrated larger magnitude of response. Total LDL particle number decreased over the 6-hour time interval, mostly from a decrease in the number of small LDL particles. Similarly, total VLDL particle number decreased due to reductions in medium and small VLDL particles. Large VLDL particles and chylomicrons demonstrated the largest increase in concentration. HDL particles demonstrated minimal overall changes in total particle number.
We have characterized the changes in LDL and VLDL particle number, and their subclass patterns following a high-fat meal.
postprandial lipemia; lipoprotein particles; NMR; high-fat meal
Background. The association between plasma omega-6 fatty acids and cardiovascular disease (CVD) is unclear, and discrepancy remains concerning the cardiovascular benefit of the omega-3 fatty acid alpha-linolenic acid. Methods. Associations of plasma phospholipid fatty acid levels (arachidonic acid, linoleic acid, eicosapentaenoic acid, docosahexaenoic acid (DHA), and alpha-linolenic acid) with cardiac magnetic resonance imaging measures of left ventricular (LV) mass, LV volume, ejection fraction, stroke volume, and aortic distensibility were investigated in 1,274 adults. Results. Results of multivariate analysis showed no statistically significant associations of plasma omega-6 or omega-3 levels with cardiac magnetic resonance imaging measures. Stratification by gender revealed a positive association between DHA and LV mass in women (β = 1.89, P = 0.02; P interaction = 0.003) and a trend for a positive association between DHA and ejection fraction in men (β = 0.009, P = 0.05; P interaction = 0.03). Conclusion. Additional research is warranted to clarify the effects of plasma DHA on cardiac structure and function in women versus men.
Data from longitudinal studies suggest that biomarkers of inflammation and endothelial dysfunction are associated with development of hypertension. None of these studies have examined the association of these markers with hypertension risk in persons with diabetes. We examined the associations of inflammatory and endothelial dysfunction markers with long-term hypertension incidence in persons with type 1 diabetes mellitus.
The 15-year cumulative incidence of hypertension was measured in Wisconsin Epidemiologic Study of Diabetic Retinopathy (WESDR) participants (n=795). Hypertension was defined by a systolic BP of ≥140 mmHg and/or a diastolic BP of ≥90 mmHg and/or history of current antihypertensive treatment. We measured serum high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular adhesion molecule-1 (sICAM-1), and serum total homocysteine as “novel” markers of hypertension development. The relation of risk factors to hypertension incidence was determined using a proportional hazards approach with discrete linear logistic regression modeling.
After controlling for age, gender, diabetes duration, body mass index, glycosylated hemoglobin, baseline systolic and diastolic blood pressure, proteinuria, and chronic kidney disease status, sVCAM-1 was significantly related to higher odds of developing incident hypertension (OR per log sVCAM-1 1.95; 95% CI 1.01–3.74). None of the other markers of inflammation and endothelial dysfunction were related to incident hypertension in the cohort.
Our data showed that sVCAM-1 as a marker of endothelial dysfunction was the strongest predictor of hypertension risk in individuals with type 1 diabetes. This association was independent of the presence of diabetic nephropathy.
We examined the relationship of inflammatory and endothelial dysfunction markers with the prevalence and incidence of gross proteinuria in persons with type 1 diabetes.
A longitudinal population based cohort of persons with type 1 diabetes was followed from 1990–1992 through 2005–2007.
Prevalence and 15-year cumulative incidence of gross proteinuria were defined as outcome variables. Serum high sensitivity C-reactive protein (hsCRP), interleukin-6 (IL-6), tumor necrosis factor-α (TNF- α), soluble vascular cell adhesion molecule-1 (VCAM-1), soluble intercellular adhesion molecule-1 (ICAM-1), and serum total homocysteine were measured. Multivariate logistic and discrete linear logistic regression modeling was used for data analysis.
After controlling for duration of diabetes and other confounding factors, TNF-α (Odds Ratio [OR] 3.64; 95% Confidence Interval [CI] 2.33, 5.70), IL-6 (OR 1.41; 95% CI 1.06, 1.88), VCAM-1 (OR 15.82; 95% CI 1.71, 33.30) and homocysteine (OR 5.25; 95% CI 3.40, 8.13) were associated with prevalent proteinuria. Only hsCRP (OR 1.47; 95% CI 1.02, 2.11) was associated with incident proteinuria.
These findings suggest a role of inflammation and endothelial dysfunction as markers and contributors of the development of diabetic nephropathy in persons with type 1 diabetes mellitus.
Markers of inflammation; markers of endothelial dysfunction; diabetic nephropathy; gross proteinuria
Despite the importance of total energy intake in circadian system regulation, no study has related human CLOCK gene polymorphisms and food-intake measures. The aim of this study was to analyze the associations of CLOCK single-nucleotide polymorphisms (SNPs) with food intake and to explore the specific role of the cytokine system. A total of 1100 individual participants in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study were included. Dietary intake was estimated with a validated questionnaire. Interleukin-6 (IL-6), monocyte chemotactic protein 1 (MCP1), tumor necrosis factor-α (TNF-α), IL-2 soluble receptor-α (IL-2sR-α) and adiponectin plasma concentrations were measured. Our results showed that four of five CLOCK SNPs selected were significantly associated with total energy intake (P<0.05). For SNP rs3749474, the energy intake and total fat, protein and carbohydrate intakes were significantly higher in minor allele carriers than in non-carriers. Frequency of the minor allele was greater in subjects with high energy intake than in those with low intake. Subjects with the minor allele were 1.33 times more likely to have high energy intake than non-carriers (95% CI 1.09–1.72, P=0.0350). All CLOCK SNPs were associated with plasma cytokine values, in particular with those that were highly correlated with energy intake: MCP1, IL-6 and adiponectin. Interestingly, minor allele carriers with high energy intake showed decreased cytokine values, which could be related with a lower anorectic effect and decreased sleep in these subjects. In conclusion, we show a novel association of genetic variation at CLOCK with total energy intake, which was particularly relevant for SNP rs3749474. Associations could be mediated through the alteration of cytokine levels that may influence energy intake and sleep pattern.
CLOCK; circadian; obesity; energy intake; metabolic syndrome; interleukin-6
Background and aims
Several genes have been shown to individually affect plasma lipoprotein metabolism in humans. Studies on gene-gene interactions could offer more insight into how genes affect lipid metabolism and may be useful in predicting lipid concentrations. We tested for gene-gene interactions between TaqIB SNP in the cholesterol ester transfer protein (CETP) and three novel single nucleotide polymorphisms (SNPs), namely rs11774572, rs7819412 and rs6995374 for their effect on metabolic syndrome (MetS) components and related traits.
Methods and results
The aforementioned SNPs were genotyped in 1002 subjects who participated in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study. Lipids were measured by standard procedures and lipoprotein subfractions, by proton nuclear magnetic resonance spectroscopy. Polymorphism rs11774572 was significantly associated with MetS (P=0.020), mainly driven by the association of the C allele with lower HDL-C (P=0.043) and higher triglycerides (P=0.049) and insulin (P=0.040) concentrations than TT subjects. A significant interaction between SNPs rs11774572 and CETP-TaqIB SNPs was found for HDL-C concentrations (P=0.006) and for HDL (P=0.008) and LDL particle sizes (P=0.009), small LDL (P=0.004), and VLDL concentrations (P=0.021), in which TT homozygotes displayed higher HDL-C concentrations and for HDL and LDL particle sizes, and lower small LDL and VLDL concentrations than C carriers, if they were CETP B2 allele carriers (P values ranging from <0.001 to 0.001).
The rs11774572 polymorphism may play a role in the dyslipidemia that characterizes MetS. The interaction between rs11774572 and CETP-TaqIB SNPs on HDL-C concentrations provides some insights into the underlying mechanisms.
HDL-cholesterol; metabolic syndrome; polymorphism-polymorphism interaction; CETP gene; pathway
Systemic inflammation is linked to cardiovascular risk, but the influence of persistent pathogens, which are conventionally dichotomously categorized, on circulating levels of inflammatory markers is not clear. Antibody levels of pathogens have not been examined in relation to inflammation.
Using data from a subsample of the Multi-Ethnic Study of Atherosclerosis, we examined circulating levels of interleukin-6 (IL-6), C-reactive protein (CRP) and fibrinogen in relation to five common persistent pathogens: cytomegalovirus, herpes simplex virus-1, Hepatitis A virus, Helicobacter pylori and Chlamydia pneumoniae. We tested the hypothesis that the number of seropositive pathogens (based on conventional cut-off points) would not be as sensitive a marker of inflammation as immune response measured by antibody levels to pathogens.
High antibody response to multiple pathogens showed graded and significant associations with IL-6 (p < 0.001), CRP (p = 0.04) and fibrinogen (p = 0.001), whereas seropositive pathogen burden did not. In multiple linear regression models, high antibody response to multiple pathogens maintained a positive association only with IL-6 (4.4% per pathogen exhibiting high antibody response, 95% CI 0.0-8.9).
High antibody response to pathogens was a more consistent marker of inflammatory outcomes compared to seropositivity alone and high antibody response to multiple pathogens was a stronger marker compared to any single pathogen.
We examined the cross-sectional relationships of subclinical atherosclerosis – expressed by carotid intimal–medial thickness and coronary calcification – with antibodies to Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, herpes simplex virus, hepatitis A virus, and pathogen burden (number of positive pathogens). A random sample of 1056 individuals chosen from 5030 Multi-Ethnic Study of Atherosclerosis cohort participants were included. After multiple adjustment, no associations were found between atherosclerosis measures and either individual pathogens or pathogen burden. Interactions with inflammatory and endothelial function markers, demographic factors, BMI, high-density lipoprotein, diabetes, and smoking were also explored. The only interaction that was large, qualitative, statistically significant (P < 0.05) and in the expected direction was that between hepatitis A virus and soluble intercellular adhesion molecule-1 with regard to Agatston calcium score: the difference between hepatitis A virus-positive and hepatitis A virus-negative participants was −86 units in participants with soluble intercellular adhesion molecule-1 below the median, and +162 units in those with soluble intercellular adhesion molecule-1 equal or above the median. However, given the number of interactions that were explored, these results must be interpreted cautiously.
Findings from the present analyses do not provide support for an infectious etiology for subclinical atherosclerosis. However, the study’s limitations, which include its cross-sectional design and insufficient statistical power, suggest that inferences from its findings should be made cautiously.
atherosclerosis; infections; pathogens
Levels of glycemia, blood pressure, and serum total cholesterol are associated with prevalence and incidence of diabetic retinopathy. It has been reported the markers of systemic inflammation and endothelial dysfunction may be important additional risk factors.
To determine the association of several systemic markers of inflammation and endothelial dysfunction to prevalence and incidence of diabetic retinal outcomes in persons with long duration type 1 diabetes.
Longitudinal population based study of persons with type 1 diabetes who were receiving care for their diabetes in south central Wisconsin in 1978-1979. Data for this investigation were from 1990-1992 through 2005-2007.
Main Outcome Measures
Severity of diabetic retinopathy and macular edema.
In prevalence data from 1990-1992, soluble vascular cell adhesion molecule (sVCAM-1), tumor necrosis factor alpha (TNF-α) and homocysteine (Hcy) were associated with increased odds of more severe retinopathy (Odds ratios [highest versus lowest quartile] 2.43, 95% Confidence Interval 1.56, 3.78; 3.14 [1.98, 4.99]; 3.79 [2.33, 6.15], respectively) in those with kidney disease while controlling for relevant confounders. Similar odds were found for proliferative diabetic retinopathy. Only homocysteine was associated with increased odds of macular edema (4.68; 1.25-17.57) irrespective of kidney disease. None of the markers were associated with incidence of proliferative retinopathy, macular edema, or progression of retinopathy 15 years later.
A limited number of markers was associated with increased odds of prevalent retinal outcomes in persons with type 1 diabetes and kidney disease. Only Hcy was associated with macular edema in those with and without kidney disease. In the absence of kidney disease the markers do not add to the more conventional descriptors and predictors of diabetic retinopathy in persons with type 1 diabetes. This may reflect the close association of diabetic retinopathy and diabetic kidney disease.
Glomerular filtration rate (GFR)-estimating equations are used to determine the prevalence of chronic kidney disease (CKD) in population-based studies. However, it has been suggested that since the commonly used GFR equations were originally developed from samples of patients with CKD, they underestimate GFR in healthy populations. Few studies have made side-by-side comparisons of the effect of various estimating equations on the prevalence estimates of CKD in a general population sample.
Patients and methods:
We examined a population-based sample comprising adults from Wisconsin (age, 43–86 years; 56% women). We compared the prevalence of CKD, defined as a GFR of <60 mL/min per 1.73 m2 estimated from serum creatinine, by applying various commonly used equations including the modification of diet in renal disease (MDRD) equation, Cockcroft–Gault (CG) equation, and the Mayo equation. We compared the performance of these equations against the CKD definition of cystatin C >1.23 mg/L.
We found that the prevalence of CKD varied widely among different GFR equations. Although the prevalence of CKD was 17.2% with the MDRD equation and 16.5% with the CG equation, it was only 4.8% with the Mayo equation. Only 24% of those identified to have GFR in the range of 50–59 mL/min per 1.73 m2 by the MDRD equation had cystatin C levels >1.23 mg/L; their mean cystatin C level was only 1 mg/L (interquartile range, 0.9–1.2 mg/L). This finding was similar for the CG equation. For the Mayo equation, 62.8% of those patients with GFR in the range of 50–59 mL/min per 1.73 m2 had cystatin C levels >1.23 mg/L; their mean cystatin C level was 1.3 mg/L (interquartile range, 1.2–1.5 mg/L). The MDRD and CG equations showed a false-positive rate of >10%.
We found that the MDRD and CG equations, the current standard to estimate GFR, appeared to overestimate the prevalence of CKD in a general population sample.
chronic kidney disease; glomerular filtration rate; MDRD equation; Cockcroft–Gault equation; Mayo equation
The biologic mechanisms linking socioeconomic position and psychosocial factors to cardiovascular disease (CVD) are not well understood. Immune response to persistent pathogens may be one of these mechanisms.
We analyzed cross-sectional data from the Multi-Ethnic Study of Atherosclerosis (N=999) composed of adults age 45–84. Log-binomial regression and ordinal logistic regression models were used to examine associations of socioeconomic factors and psychosocial factors with pathogen burden and immune response among those infected. Pathogen burden was assessed based on seroprevalence of Helicobacter pylori, cytomegalovirus, herpes simplex virus-1, and Chlamydia pneumoniae and antibody levels were used to characterize high immune response to all four pathogens.
Low education was a strong and significant independent predictor of higher pathogen burden after adjustment for covariates (adjusted odds ratio (OR) 95% confidence interval (CI) 1.37, 1.19–1.57). Among subjects seropositive for all four pathogens, low education and a higher level of chronic psychosocial stress showed a positive association with higher antibody response, although associations were no longer significant in models with all covariates included (OR = 1.64, 95%CI 0.82–3.31 for lowest vs. highest educational category and OR= 1.29, 95%CI 0.96–1.73 for a one level increase in chronic stress).
Pathogen burden and heightened immune response may represent a biological pathway by which low socioeconomic position and chronic stress are related to increased rates of cardiovascular disease.
Infection; inflammation; epidemiology; cardiovascular diseases
Adipose (adp) is an obesity gene in Drosophila and mice with crucial functions in fat metabolism. We investigated the correlation between genetic variation of the WDTC1 locus, the ortholog of adp, and human obesity. Five WDTC1 single nucleotide polymorphisms (SNPs) were genotyped in 935 and 1115 adults of two ethnically diverse US populations. In the Boston Puerto Rican population, we demonstrated that two WDTC1 SNPs strongly associated with obesity. Homozygote and heterozygote carriers of the major allele i22835A, representing about 96% of the population, had significantly higher mean BMI (31.5 and 31.0 kg/m2, respectively) than non-carriers (28.6 kg/m2). Conversely, homozygotes of the minor allele i22835G were leaner and were 74% less likely to be overweight or obese (OR=0.26, P=0.003) compared to homozygote carriers of the major allele. Haplotype analyses based on two SNPs further supported these findings. In addition, we found a strong interaction of monounsaturated fatty acid (MUFA) intake by genotype in this population. As dietary MUFA intake increased, minor allele carriers of SNPs i22835A>G had higher BMIs, whereas major allele carriers had lower BMIs. A White population also exhibited a pattern of association between WDTC1 genotypes and obesity although of a different nature. Those WDTC1 variants associated with obesity likely have experienced strong positive selection in human history, when food supply was unpredictable. Given the high frequency of the major alleles in both populations, we suggest that WDTC1 variation may be an important risk factor contributing to obesity in these populations.
WDTC1; adipose; obesity; overweight; BMI
We have asked whether the prevalence of combined hyperlipidemia (CHL) differs by race/ethnicity, obesity, and insulin resistance in a contemporary, multi-ethnic, US cohort.
Methods & Results
We determined the prevalence and adjusted odds of CHL in a cohort of 5,923 men and women free of clinically-recognized cardiovascular disease and diabetes, according to race/ethnicity (White, Chinese, African-American, and Hispanic), obesity, and insulin resistance. Untreated lipid values were imputed for those on lipid lowering therapy. CHL was defined using age and gender-specific ≥75th percentile cut points for LDL-C and triglycerides obtained from a predominantly Caucasian North American population study. Compared to Whites, adjusted odds ratios (OR) for CHL were 0.48 in African Americans (95% confidence interval (CI): 0.30, 0.75), 1.33 in Hispanics (95% CI 0.93, 1.91), and 1.06 in Asians (95% CI 0.62, 1.82). Within the entire population, the adjusted odds of CHL was over 2-fold higher in overweight and obese participants compared with normal weight and more than 4-fold higher in quartiles 2 through 4 of insulin resistance, compared with quartile 1.
African-Americans had lower odds for CHL than Whites despite higher BMI and abdominal adiposity. Hispanics had a non-significantly higher trend and Asians had no significantly different odds than Whites. Modest increases in weight and insulin resistance were associated with significantly higher odds of CHL in a multi-ethnic US population. Further research is needed to determine the most efficacious diet, exercise and drug management to decrease the risk of CHL and CHD among racial/ethnic groups in the United States.