Diet in Food Insecurity: A Mediator of Metabolic Health?

Objective

Food insecurity (FI) is associated with poor metabolic health. It is assumed that energy intake and diet quality underlie this association. We tested the hypothesis that dietary factors (quantity and quality) mediate the association of FI with excess weight, waist circumference and glycemic control [glycohemoglobin (A1C)].

Methods

A mediation analysis was performed on data from the National Health And Nutrition Examination Survey using FI as an independent variable; body mass index (BMI), waist circumference, and A1C as metabolic outcome variables and total energy intake, macronutrients, and diet quality measured by the Healthy Eating Index-2015 (HEI-2015) as potential mediators.

Results

Despite a greater prevalence of obesity in participants experiencing FI, daily reported energy intake was similar in food-secure and -insecure subjects. In adjusted analyses of the overall cohort, none of the examined dietary factors mediated associations between FI and metabolic outcomes. In race-stratified analyses, total sugar consumption was a partial mediator of BMI in non-Hispanic Whites, while diet quality measures (HEI-2015 total score and added sugar subscore) were partial mediators of waist circumference and BMI, respectively, for those in the "other" ethnic group.

Conclusion

Dietary factors are not the main factors underlying the association of FI with metabolic health. Future studies should investigate whether other social determinants of health commonly present in the context of FI play a role in this association.

E-value: a superior alternative to P-value and its adjustments in DNA methylation studies

DNA methylation plays a crucial role in transcriptional regulation. Reduced representation bisulfite sequencing (RRBS) is a technique of increasing use for analyzing genome-wide methylation profiles. Many computational tools such as Metilene, MethylKit, BiSeq and DMRfinder have been developed to use RRBS data for the detection of the differentially methylated regions (DMRs) potentially involved in epigenetic regulations of gene expression. For DMR detection tools, as for countless other medical applications, P-values and their adjustments are among the most standard reporting statistics used to assess the statistical significance of biological findings. However, P-values are coming under increasing criticism relating to their questionable accuracy and relatively high levels of false positive or negative indications. Here, we propose a method to calculate E-values, as likelihood ratios falling into the null hypothesis over the entire parameter space, for DMR detection in RRBS data. We also provide the R package 'metevalue' as a user-friendly interface to implement E-value calculations into various DMR detection tools. To evaluate the performance of E-values, we generated various RRBS benchmarking datasets using our simulator 'RRBSsim' with eight samples in each experimental group. Our comprehensive benchmarking analyses showed that using E-values not only significantly improved accuracy, area under ROC curve and power, over that of P-values or adjusted P-values, but also reduced false discovery rates and type I errors. In applications using real RRBS data of CRL rats and a clinical trial on low-salt diet, the use of E-values detected biologically more relevant DMRs and also improved the negative association between DNA methylation and gene expression.

RF12 | PSUN118 Diet Quality and Energy Intake Mediate the Association of Food Insecurity with Adiposity

Food insecurity, the lack of consistent access to sufficient food for an active and healthy life, is associated with lower diet quality, higher BMI and adiposity, and poor metabolic health. Although lower diet quality is assumed to be responsible for the impact of food insecurity on adiposity, this hypothesis has not been previously investigated.

To test the hypothesis that diet quality mediates the association of food insecurity with adiposity, we used data from the 2015-2016 National Health and Nutrition Examination Survey (NHANES, age ≥18 years, n=5821, weighted N=233,636,542). Anthropometrics included BMI, waist circumference and fat mass (measured by dual X-ray absorptiometry and expressed as percentage of total body weight). Food insecurity was assessed with the 10-item NHANES Food Security Survey Module and defined as ≥3 affirmative responses. Nutrition information was derived from 24h food recalls obtained on 2 separate occasions. Diet quality was estimated by the Healthy Eating Index-2015 (HEI), which includes a total score for overall diet quality, and sub-scores for several dietary components. Mediation analysis was conducted with the Baron and Kenny approach. A p-value <0.05 was considered statistically significant.

The cohort included 52% women, 11% non-Hispanic Black and 15% Hispanic participants. Eighteen percent were food insecure. They reported a lower energy intake compared to food secure participants, although the difference was not significant after adjusting for demographics and income (difference [95% confidence interval] -84 [-207.36, 38.91] kcal/day, p=0.15). Total HEI and fruit scores were lower in food insecure individuals, suggesting lower diet quality (adjusted difference -1.70 [-3.09, -0.32], p=0.03; and -0.28 [-0.53, -0.02], p=0.04, respectively). Obesity was 22% more prevalent in food insecure individuals (p<0.01). Fat mass and waist circumference were also higher in individuals with food insecurity (adjusted difference 0.95 [0.19, 1.7] %, p=0.02; and 3.81 [1.3, 6.31] cm, p=0.01, respectively). Mediation analysis revealed that total energy intake mediated the effect of food insecurity on fat mass but not BMI or waist circumference, while total HEI partially mediated the effect of food insecurity on waist circumference but not BMI or percent fat mass. No mediation of total fruit score on BMI or adiposity was observed.

In summary, our results confirm a greater prevalence of obesity and higher adiposity in food insecure individuals, despite a similar reported energy intake compared to food secure individuals. Energy intake and measures of diet quality appear to mediate some of the effect of food insecurity on overall and central adiposity, but not on BMI. This suggests that other factors, including the social determinants of health, may also play a role.

Presentation: Saturday, June 11, 2022 1:18 p.m. - 1:23 p.m., Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m.

Abstract P133: Human Induced Pluripotent Stem Cells-derived Vascular Endothelial And Smooth Muscle Cells And Fractions Of Native Human Arterioles Exhibit Robust Expression Of Marker Genes

Human induced pluripotent stem cells (iPSCs) can be differentiated into vascular endothelial and smooth muscle cells (iEC and iVSMC). The defined genetic makeup and the ease of genetic engineering in multiple cell types on an isogenic background make these cells potentially powerful tools for studying molecular mechanisms underlying vascular function and disease. While several studies have characterized iEC and iVSMC and compared them with other cultured cells, no studies have analyzed these cells in conjunction with native human cells. In this study, we characterized iEC, iVSMC, and fractions of native human arterioles by examining large panels of marker genes. iEC and iVSMC were differentiated (n=4) from a custom-made iPSC line. Differentiated cells were sorted using VE-cadherin ( CDH5 ) to obtain iEC (positive selection) and iVSMC (negative selection). Arterioles were isolated from adipose tissues obtained from 4 humans, and the endothelial and vessel remainder fractions were separated by scraping. RNA-seq was performed on all samples. We focused the analysis on 10 and 15 marker genes for EC and VSMC, respectively, that we curated from the literature. iEC exhibited robust expression of 9 of the 10 EC markers such as CD34 (FPKM, 137±58), PECAM1 (153±32), and VWF (44±7), while iVSMC had negligible expression of EC marker genes. Conversely, iVSMC exhibited robust expression of 11 of the 15 VSMC marker genes, while the expression of these genes in iEC was depleted by several fold. Eight of the 10 EC marker genes were enriched in the endothelial fraction of native arterioles by several fold compared with intact arterioles, while 12 of the 15 VSMC marker genes were substantially depleted in the endothelial fraction. EC marker genes were significantly depleted and VSMC marker genes enriched in the vessel remainder fraction. In summary, iEC and iVSMC, as well as endothelial and vessel remainder factions from native human arterioles, exhibit robust expression of large panels of EC and VSMC marker genes based on agnostic RNA-seq analysis. These novel findings indicate that iEC, iVSMC, and endothelial and vessel remainder factions of native human arterioles are relevant tools for studying molecular regulation in specific vascular cell types.

Wide Variability in Catecholamine Levels From Adrenal Venous Sampling in Primary Aldosteronism

INTRODUCTION

While adrenal venous sampling (AVS) differentiates between the unilateral and bilateral disease in patients with primary aldosteronism (PA), it is unknown if AVS can determine laterality of pheochromocytoma in patients with bilateral adrenal masses. This study analyzes adrenal vein (AV) epinephrine and norepinephrine levels in nonpheochromocytoma patients to determine the "normal" range.

MATERIALS AND METHODS

We reviewed patients who underwent AVS for PA between 2009 and 2019 at a single institution; pheochromocytoma was excluded. Aldosterone, cortisol, epinephrine, and norepinephrine levels were obtained from the inferior vena cava (IVC), left adrenal vein (LAV), and right adrenal vein (RAV). Successful AV cannulation was defined by an AV/IVC cortisol ratio of ≥3:1 or an AV epinephrine level ≥364 pg/mL. Plasma measurements (pg/mL) are median values with interquartile ranges; normal ranges for epinephrine and norepinephrine are 10-200 pg/mL and 80-520 pg/mL, respectively.

RESULTS

AVS was performed in 172 patients in 405 AVs (173 LAV and 232 RAV). Median epinephrine levels were IVC = 19 (14 and 34), LAV = 3811 (1870 and 6915), and RAV = 2897 (1500 and 5288). Median norepinephrine levels were IVC = 325 (186 and 479), LAV = 1450 (896 and 2050), and RAV = 786 (436 and 1582). There was a difference between LAV and RAV epinephrine levels (P = 0.024) and between LAV and RAV norepinephrine (P = 0.002) levels.

CONCLUSIONS

This extensive experience with AVS demonstrated a wide range of "normal" AV catecholamine levels in patients without pheochromocytoma, which suggests that the utility of AVS to determine disease laterality in patients with pheochromocytoma and bilateral adrenal nodules is likely to be limited.

Insulin Prevents Hypercholesterolemia by Suppressing 12a-Hydroxylated Bile Acid Production

Background: The risk of cardiovascular disease in type 1 diabetes remains extremely high, despite marked advances in blood glucose control and even the widespread use of cholesterol synthesis inhibitors. Thus, a deeper understanding of insulin regulation of cholesterol metabolism, and its disruption in type 1 diabetes, could reveal better treatment strategies. Methods: To define the mechanisms by which insulin controls plasma cholesterol levels, we knocked down the insulin receptor, FoxO1, and the key bile acid synthesis enzyme, CYP8B1. We measured bile acid composition, cholesterol absorption, and plasma cholesterol. In parallel, we measured markers of cholesterol absorption and synthesis in humans with type 1 diabetes treated with ezetimibe and statins in a double-blind crossover study. Results: Mice with hepatic deletion of the insulin receptor showed marked increases in 12α-hydroxylated bile acids (12HBAs), cholesterol absorption, and plasma cholesterol. This phenotype was entirely reversed by hepatic deletion of FoxO1. FoxO1 is inhibited by insulin, and required for the production of 12HBAs, which promote intestinal cholesterol absorption and suppress hepatic cholesterol synthesis. Knockdown of Cyp8b1 normalized 12HBA levels and completely prevented hypercholesterolemia in mice with hepatic deletion of the insulin receptor (n=5-30) as well as mouse models of type 1 diabetes (n=5-22). In parallel, the cholesterol absorption inhibitor, ezetimibe, normalized cholesterol absorption and LDL-cholesterol in patients with type 1 diabetes as well as, or better than, the cholesterol synthesis inhibitor, simvastatin (n=20). Conclusions: Insulin, by inhibiting FoxO1 in the liver, reduces 12HBAs, cholesterol absorption, and plasma cholesterol levels. Thus, type 1 diabetes leads to a unique set of derangements in cholesterol metabolism, with increased absorption rather than synthesis. These derangements are reversed by ezetimibe, but not statins, which are currently the first line of lipid-lowering treatment in type 1 diabetes. Taken together, these data suggest that a personalized approach to lipid lowering in type 1 diabetes may be more effective and highlight the need for further studies specifically in this group of patients.

Unique Associations of DNA Methylation Regions With 24-Hour Blood Pressure Phenotypes in Blacks

BACKGROUND

Epigenetic marks (eg, DNA methylation) may capture the effect of gene-environment interactions. DNA methylation is involved in blood pressure (BP) regulation and hypertension development; however, no studies have evaluated its relationship with 24-hour BP phenotypes (daytime, nighttime, and 24-hour average BPs).

METHODS

We examined the association of whole blood DNA methylation with 24-hour BP phenotypes and clinic BPs in a discovery cohort of 281 Blacks using reduced representation bisulfite sequencing. We developed a deep and region-specific methylation sequencing method, Bisulfite ULtrapLEx Targeted Sequencing and utilized it to validate our findings in a separate validation cohort (n=117).

RESULTS

Analysis of 38 215 DNA methylation regions (MRs), derived from 1 549 368 CpG sites across the genome, identified up to 72 regions that were significantly associated with 24-hour BP phenotypes. No MR was significantly associated with clinic BP. Two to 3 MRs were significantly associated with various 24-hour BP phenotypes after adjustment for age, sex, and body mass index. Together, these MRs explained up to 16.5% of the variance of 24-hour average BP, while age, sex, and BMI explained up to 11.0% of the variance. Analysis of one of the MRs in an independent cohort using Bisulfite ULtrapLEx Targeted Sequencing confirmed its association with 24-hour average BP phenotype.

CONCLUSIONS

We identified several MRs that explain a substantial portion of variances in 24-hour BP phenotypes, which might be excellent markers of cumulative effect of factors influencing 24-hour BP levels. The Bisulfite ULtrapLEx Targeted Sequencing workflow has potential to be suitable for clinical testing and population screenings on a large scale.

Utility of Epinephrine Levels in Determining Adrenal Vein Cannulation During Adrenal Venous Sampling for Primary Aldosteronism

OBJECTIVE

In patients with primary aldosteronism, adrenal venous sampling (AVS) is performed to determine the presence of unilateral or bilateral adrenal disease. During AVS, verification of catheter positioning within the left adrenal vein (AV) and the right AV by comparison of AV and inferior vena cava (IVC) cortisol levels can be variable. The objective of this study was to determine the utility of AV epinephrine levels in assessing successful AV cannulation.

METHODS

This was a single institution, retrospective review of patients who underwent AVS with cosyntropin stimulation for primary aldosteronism between 2009 and 2018. Successful cannulation of the AV was defined by an AV/IVC cortisol ratio selectivity index (SI) ≥3:1. Epinephrine thresholds to predict catheter placement in the AV were determined using logistic regression. The calculated epinephrine thresholds were compared with previously published thresholds.

RESULTS

AVS was performed on 101 consecutive patients and, based on the SI, successful cannulation of the left AV and right AV occurred in 98 (97%) and 91(90%) patients, respectively. The calculated optimal epinephrine threshold to predict AV cannulation was 364 pg/mL (sensitivity, 92.1%; specificity, 94.6%) and the calculated optimal AV/IVC epinephrine ratio threshold was 27.4, (sensitivity, 92.1%; specificity, 91.3%). Among the 14 patients with failed AV cannulation, 3 patients would have been considered to have successful AVS using AV epinephrine levels >364 pg/mL and AV/IVC epinephrine ratio >27.4 thresholds.

CONCLUSION

Obtaining 2 right AV samples routinely as well as AV and IVC epinephrine levels during AVS could prevent unnecessary repeat AVS in patients with failed AV cannulation based on cortisol-based SI <3:1.

Abstract P175: Discovery And Validation Of Unique Associations Of DNA Methylation Regions With 24-hour Blood Pressure Phenotypes In African Americans

DNA methylation, an epigenetic mark, may reflect the interactions between DNA, environment, and lifestyle. It has been implicated in the development and progression of hypertension, a risk factor for cardiovascular disease. We hypothesize that regions of DNA methylation in blood cells can explain 24h BP phenotypes in African Americans. We performed Reduced Representation Bisulfite Sequencing (RRBS) in a discovery cohort of 281 African Americans. Several DNA methylation regions (MRs) were significantly associated with continuously monitored 24-h, daytime, or nighttime SBP, DBP, PP, and MAP after adjustments for covariates age, sex, and body mass index (False Discovery Rate (FDR) = 0.013 - 0.050). Each of these MRs explained a substantial portion of 24h BP variance, ranging from 6.5% - 9.4%. After FDR adjustment, there were no MRs significantly associated with clinic BPs (FDR > 0.1374), calculated by the average of 4 resting measurements (2 per arm) by sphygmomanometer. To interrogate specific regions of DNA methylation, our lab developed a potentially clinically applicable, deep, and targeted methylation sequencing method called Bisulfite-Specific PCR ULtrapLEx Targeted Sequencing (BULLET-Seq), and tested it in two reference samples for three MRs of interest. BULLET-Seq is able to accurately quantify the 10% changes in the dilution series when methylation rates ranged from ~40% to 90% (a chr19 methylation region; R 2 = 0.95 - 0.97) and can modestly measure these changes when rates range from ~2% to 4% (a chr5 region, R 2 = 0.82), and is questionable when methylation rates are below 2% (a chr13 region, R 2 = 0.03 - 0.27). Validation of the chr19 MR in an independent cohort (n=117) was performed in a single BULLET-Seq run. After covariate adjustment, the chr19 region was significantly associated with 24h BPs (SBP, DBP, and MAP; FDR < 0.05), confirming the findings from the discovery cohort. The MR accounted for up to 1.75% of BP variance in the 24h phenotypes. In conclusion, the reported DNA MRs have potential to be excellent markers for the cumulative effect of factors that influence 24h BPs and the BULLET-Seq workflow can be applied in clinical and population settings to screen up to thousands of patients.

Dietary supplements and alternative therapies for obesity: A Perspective from The Obesity Society's Clinical Committee

In this Perspective Statement from The Obesity Society, the Clinical Committee discusses the use of weight loss supplements in the United States and the lack of regulatory oversight and rigorous testing of their efficacy and safety. A number of products and services claiming to promote weight loss are directly marketed to individuals with obesity and those wanting to lose weight. These products are not regulated as "drugs" by the Federal Drug Administration but, rather, are treated as dietary supplements if ingredients are "generally regarded as safe," requiring little or no testing to show efficacy or safety. Health care providers should be aware of the lack of evidence and deficiencies in regulatory oversight of dietary supplements marketed for weight loss. Regulatory authorities should protect consumers by ensuring accurate and safe marketing claims and preventing promotion of unproven and potentially unsafe products and claims.

A Systematic Review of Dietary Supplements and Alternative Therapies for Weight Loss

OBJECTIVE

Dietary supplements and alternative therapies are commercialized as a panacea for obesity/weight gain as a result of the minimal regulatory requirements in demonstrating efficacy. These products may indirectly undermine the value of guideline-driven obesity treatments. Included in this study is a systematic review of the literature of purported dietary supplements and alternative therapies for weight loss.

METHODS

A systematic review was conducted to evaluate the efficacy of dietary supplements and alternative therapies for weight loss in participants aged ≥18 years. Searches of Medline (PubMed), Cochrane Library, Web of Science, CINAHL, and Embase (Ovid) were conducted. Risk of bias and results were summarized qualitatively.

RESULTS

Of the 20,504 citations retrieved in the database search, 1,743 full-text articles were reviewed, 315 of which were randomized controlled trials evaluating the efficacy of 14 purported dietary supplements, therapies, or a combination thereof. Risk of bias and sufficiency of data varied widely. Few studies (n = 52 [16.5%]) were classified as low risk and sufficient to support efficacy. Of these, only 16 (31%) noted significant pre/post intergroup differences in weight (range: 0.3-4.93 kg).

CONCLUSIONS

Dietary supplements and alternative therapies for weight loss have a limited high-quality evidence base of efficacy. Practitioners and patients should be aware of the scientific evidence of claims before recommending use.

Dietary Sodium Restriction Results in Tissue-Specific Changes in DNA Methylation in Humans

[Figure: see text].

Team Science: American Heart Association's Hypertension Strategically Focused Research Network Experience

In 2015, the American Heart Association awarded 4-year funding for a Strategically Focused Research Network focused on hypertension composed of 4 Centers: Cincinnati Children's Hospital, Medical College of Wisconsin, University of Alabama at Birmingham, and University of Iowa. Each center proposed 3 integrated (basic, clinical, and population science) projects around a single area of focus relevant to hypertension. Along with scientific progress, the American Heart Association put a significant emphasis on training of next-generation hypertension researchers by sponsoring 3 postdoctoral fellows per center over 4 years. With the center projects being spread across the continuum of basic, clinical, and population sciences, postdoctoral fellows were expected to garner experience in various types of research methodologies. The American Heart Association also provided a number of leadership development opportunities for fellows and investigators in these centers. In addition, collaboration was highly encouraged among the centers (both within and outside the network) with the American Heart Association providing multiple opportunities for meeting and expanding associations. The area of focus for the Cincinnati Children's Hospital Center was hypertension and target organ damage in children utilizing ambulatory blood pressure measurements. The Medical College of Wisconsin Center focused on epigenetic modifications and their role in pathogenesis of hypertension using human and animal studies. The University of Alabama at Birmingham Center's areas of research were diurnal blood pressure patterns and clock genes. The University of Iowa Center evaluated copeptin as a possible early biomarker for preeclampsia and vascular endothelial function during pregnancy. In this review, challenges faced and successes achieved by the investigators of each of the centers are presented.

A Case of Silent Corticotroph Adenoma

Background: Silent Corticotroph Adenomas (SCAs) are tumors with no biochemical or clinical features consistent with hypercortisolism but have positive immunostaining for ACTH. They account for approximately 1.1-6% of all pituitary adenomas and 5.5% of nonfunctioning adenomas. Clinical Case: A 49-year-old woman presented to clinic with a 6-month history of headache, vision changes, fatigue, hair thinning, brittle nails, lightheadedness, polydipsia, easy bruising, increased appetite, and weight gain of 178 pounds in 2 years. Labs obtained: morning cortisol 10 mcg/dl(7-25 mcg/dl), ACTH 59 pg/ml(7.2-63 pg/ml), IGF-1 96 ng/ml(52-328 ng/ml), LH 0.2 mIU/ml(1.9-12.5 mIU/ml), FSH 0.8 mIU/ml(2.5-10.2mIU/ml), alpha subunit <0.1 ng/ml(52-328 ng/ml), TSH 0.991 uIU/ml(0.358-3.74 uIU/ml), free T4 1.12 ng/dl(0.76-1.46 ng/dl), salivary cortisol 66 ng/dl(<100 ng/dl), 24-hour urine cortisol 10 mcg/24hr(3.5-45 mcg/24hr) and prolactin 64.3 ng/ml(2.8-29.2 ng/ml). No hook effect noted with serial dilution. MRI brain showed a 22 x 29 x 26 mm sellar mass extending into the suprasellar cistern displacing and compressing the optic nerves and chiasm superiorly with partial invasion into the right cavernous sinus. She had an endoscopic resection of the sellar mass. She developed diabetes insipidus post-operatively and required desmopressin transiently. In the immediate post-operative period, morning cortisol and ACTH were 16.9 ug/dl(6.2-19.4 ug/dL) 24.8 pg/ml(7.2-63.3 pg/ml) respectively. She was sent home without steroids. Pathology showed a staining pattern consistent with pituitary adenoma with positive staining for ACTH. One month after her surgery she was admitted with symptoms of orthostatic hypotension. Cortisol at 5pm was 3 ug/dl(2.3-11.9 ug/dl), ACTH 31.7 pg/ml(7.2-63.3pg/ml). She had a cosyntropin stimulation test done with peak cortisol of 19.3 ug/dl at 60 minutes. Due to her symptoms, she was started on oral hydrocortisone (HC) for secondary adrenal insufficiency (AI), but was eventually tapered off the steroids. Six months after her surgery, she developed worsening headaches. Repeat MRI obtained showed significant growth of the residual adenoma on the right side of the sella, invading the cavernous sinus. Morning cortisol level of 5.3 mcg/dl(4.3-22.4 mcg/dl) and ACTH level was 11 pg/ml(6-50 pg/ml). She had a repeat endoscopic resection of the pituitary tumor. Her post-surgery cortisol at 2 PM was 3 mcg/dl at which time patient reported symptoms of AI. She was discharged on HC. Pathology again showed a staining pattern consistent with pituitary adenoma with positive staining for ACTH. MIB-1 proliferative index was 5.6%. P53 immunostaining showed a moderate density of moderately intense nuclei in the adenoma. Conclusion: This case illustrates aggressive nature of SCAs with higher risk of recurrence compared to other non-functioning adenomas and therefore requires close follow up.

Twenty-four-hour versus clinic blood pressure levels as predictors of long-term cardiovascular and renal disease outcomes among African Americans

In Caucasian and Asian populations, evidence suggests that 24-h blood pressures (BP) are more predictive of long-term cardiovascular events than clinic BP. However, few long-term studies have evaluated the predictive value of 24-h BP phenotypes (24-h, daytime, nighttime) among African Americans (AA). The purpose of this study is to evaluate the added value of 24-h BP phenotypes compared to clinic BP in predicting the subsequent fatal and non-fatal cardiovascular/renal disease events in AA subjects. AA subjects (n = 270) were initially studied between 1994 and 2006 and standardized clinic BP measurements were obtained during screening procedures for a 3-day inpatient clinical study during which 24-h BP measurements were obtained. To assess the subsequent incidence of cardiovascular and renal disease events, follow-up information was obtained and confirmed by review of paper and electronic medical records between 2015 and 2017. During a mean follow-up of 14 ± 4 years, 50 subjects had one or more fatal or non-fatal cardiovascular/renal disease events. After adjustment for covariates, clinic systolic and diastolic BP were strongly associated with cardiovascular/renal disease events and all-cause mortality (p < 0.0001). Twenty-four-hour BP phenotypes conferred a small incremental advantage over clinic BP in predicting cardiovascular/renal events, which was limited to making a difference of one predicted event in 250-1,000 predictions depending on the 24-h BP phenotype. Nocturnal BP was no more predictive than the other 24-h BP phenotypes. In AA, 24-h BP monitoring provides limited added value as a predictor of cardiovascular/renal disease events. Larger studies are needed in AA to confirm these findings.

Weight History in Clinical Practice: The State of the Science and Future Directions

Eliciting a weight history can provide clinically important information to aid in treatment decision-making. This view is consistent with the life course perspective of obesity and the aim of patient-centered care, one of six domains of health care quality. However, thus far, the value and practicality of including a weight history in the clinical assessment and treatment of patients with obesity have not been systematically explored. For these reasons, the Clinical Committee of The Obesity Society established a task force to review and assess the available evidence to address five key questions. It is concluded that weight history is an essential component of the medical history for patients presenting with overweight or obesity, and there are strong and emerging data that demonstrate the importance of life stage, duration of exposure to obesity, maximum BMI, and group-based trajectory modeling in predicting risk for increased morbidity and mortality. Consideration of these and other patient-specific factors may improve risk stratification and clinical decision-making for screening, counseling, and management. Recommendations are provided for the key elements that should be included in a weight history, and several needs for future clinical research are outlined.

Epigenetic Modifications in T Cells: The Role of DNA Methylation in Salt-Sensitive Hypertension

The SS (Dahl salt sensitive) rat is an established model of hypertension and renal damage that is accompanied with immune system activation in response to a high-salt diet. Investigations into the effects of sodium-independent and dependent components of the diet were shown to affect the disease phenotype with SS/MCW (JrHsdMcwi) rats maintained on a purified diet (AIN-76A) presenting with a more severe phenotype relative to grain-fed SS/CRL (JrHsdMcwiCrl) rats. Since contributions of the immune system, environment, and diet are documented to alter this phenotype, this present study examined the epigenetic profile of T cells isolated from the periphery and the kidney from these colonies. T cells isolated from kidneys of the 2 colonies revealed that transcriptomic and functional differences may contribute to the susceptibility of hypertension and renal damage. In response to high-salt challenge, the methylome of T cells isolated from the kidney of SS/MCW exhibit a significant increase in differentially methylated regions with a preference for hypermethylation compared with the SS/CRL kidney T cells. Circulating T cells exhibited similar methylation profiles between colonies. Utilizing transcriptomic data from T cells isolated from the same animals upon which the DNA methylation analysis was performed, a predominant negative correlation was observed between gene expression and DNA methylation in all groups. Lastly, inhibition of DNA methyltransferases blunted salt-induced hypertension and renal damage in the SS/MCW rats providing a functional role for methylation. This study demonstrated the influence of epigenetic modifications to immune cell function, highlighting the need for further investigations.

Dietary Effects on Dahl Salt-Sensitive Hypertension, Renal Damage, and the T Lymphocyte Transcriptome

The Dahl salt-sensitive (SS) rat is an established model of SS hypertension and renal damage. In addition to salt, other dietary components were shown to be important determinants of hypertension in SS rats. With previous work eliminating the involvement of genetic differences, grain-fed SS rats from Charles River Laboratories (SS/CRL; 5L2F/5L79) were less susceptible to salt-induced hypertension and renal damage compared with purified diet-fed SS rats bred at the Medical College of Wisconsin (SS/MCW; 0.4% NaCl, AIN-76A). With the known role of immunity in hypertension, the present study characterized the immune cells infiltrating SS/MCW and SS/CRL kidneys via flow cytometry and RNA sequencing in T-cells isolated from the blood and kidneys of rats maintained on their respective parental diet or on 3 weeks of high salt (4.0% NaCl, AIN-76A). SS/CRL rats were protected from salt-induced hypertension (116.5±1.2 versus 141.9±14.4 mm Hg), albuminuria (21.7±3.5 versus 162.9±22.2 mg/d), and renal immune cell infiltration compared with SS/MCW. RNA-seq revealed >50% of all annotated genes in the entire transcriptome to be significantly differentially expressed in T-cells isolated from blood versus kidney, regardless of colony or chow. Pathway analysis of significantly differentially expressed genes between low and high salt conditions demonstrated changes related to inflammation in SS/MCW renal T-cells compared with metabolism-related pathways in SS/CRL renal T-cells. These functional and transcriptomic T-cell differences between SS/MCW and SS/CRL show that dietary components in addition to salt may influence immunity and the infiltration of immune cells into the kidney, ultimately impacting susceptibility to salt-induced hypertension and renal damage.

Abstract 035: Unique Associations of DNA Methylation With 24-Hour Blood Pressure Phenotypes in African Americans

Blood pressure (BP) levels are influenced by genetic and environmental factors. Epigenome is the result of interactions between the DNA and the environment. Methylation is a naturally occurring epigenetic modification of genomic DNA and may influence BP levels. We examined the association of DNA methylation in whole blood with 24-hour and clinic BP phenotypes in 281 African Americans; fifty percent were women and fifty percent were hypertensive. Mean age of the participants was 44±7 years and mean body mass index (BMI) was 28±5 kg/m 2 . Clinic BP was obtained in duplicate from both arms and averaged using a standardized protocol as part of screening procedures for a 3-day inpatient clinical study. Blood was obtained for DNA at the time of screening visit. BP medications were discontinued for 1-week after the screening visit and prior to inpatient study. Detailed phenotyping and 24-hour BP measurements were performed during the in-patient study. DNA methylation profiles of these 281 subjects with 24-hour BP measurements were analyzed at single-base resolution with a modified reduced representation bisulfite sequencing (RRBS) method. Analysis of 38,216 DNA methylation regions, representing 1,549,368 CpG sites across the genome, identified up to 72 regions that were significantly associated with 24-hour, daytime or nighttime BPs. Considered jointly, these methylation regions explained up to 66.6% of the BP variance. Methylation regions associated with 24-hour, daytime or nighttime BPs or systolic, diastolic or mean arterial pressure or pulse pressure overlapped partially. No methylation region was significantly associated with clinic BP. Two to three methylation regions were significantly associated with 24-hour BP after adjustment for age, sex, and body mass index. These methylation regions, jointly, explained up to 16.5% of the variance of 24-hour BP, while age, sex and body mass index explained up to 11.0% of the variance. In summary, we have identified several DNA methylation regions in the whole blood that are associated with 24-hour, daytime or nighttime BPs, but not with clinic BP measured at a single point in time. DNA methylation appears to be an excellent marker for the cumulative effect of factors that influence 24-hour, daytime or nighttime BPs

Abstract 116: BMI is Not a Risk Factor for All-Cause Mortality and Cardiovascular Disease Among African American Women

Background: Across the age spectrum, obesity rates are higher among African Americans (AA) than Whites, particularly women. Previous findings from a large cohort study indicated that risk of all-cause mortality is only moderately elevated with increased weight among AA, but this relationship is a much stronger finding in Whites. In this study, we examined the relationship of baseline body mass index (BMI) to incident all-cause mortality and fatal and non-fatal cardiovascular and renal disease (CVRD) events.

Methods: Between 1994 - 2006, 1723 AA (52% women, age: 44±7 yrs., BMI: 29 ± 6 kg/m 2 , 51% hypertensive) were recruited for genetic studies of hypertension. Height and weight were obtained at baseline in a standardized manner. Mortality data were obtained from the National Death Index in 2018 on all subjects. Incidence of fatal/non-fatal CVRD events was obtained and confirmed by review of paper and electronic medical records between 2015-2019 in a sub-sample. Subjects who had either a CVRD event or at least 10 years of follow-up data available with no event were included (n=788). Logistic regression (LR) was performed to determine if BMI predicted mortality or a CVRD event.

Results: There were 325 deaths (19%, time-to-death: 12±3 yrs.) from all causes. During a follow-up of 14±4 yrs., 154 subjects had a CVRD (20%) event/death. There was no difference in age between sexes, but women had a higher BMI compared to men (30±7 vs. 27±5 kg/m 2 , p<0.0001). Men had a higher mortality (23% vs. 15%, p<0.0001) and more CVRD events (24% vs. 16%, p = 0.008). The odds ratio (OR) for death was 1.62 (CI: 1.3-2.1, p=0.0002) in men compared to women. Baseline BMI was not predictive of all-cause mortality in the total sample or in men or women separately. BMI predicted CVRD events in men with an OR of 1.08 (CI: 1.03-1.13), i.e. one-unit increase in BMI in men led to 8% increase in odds for CVRD events. However, BMI was not predictive of CVDR events in women (OR: 1.01 [0.98-1.05]).

Conclusion: This is the first study to evaluate the effect of BMI longitudinally on incident CVRD events among AA. Although BMI is the most common metric to define obesity, it is not predictive of CVRD and/or mortality risk among AA women. This factor should be considered while determining cardiovascular disease risk status among AA.

Stability of global methylation profiles of whole blood and extracted DNA under different storage durations and conditions

AIM

To test whether DNA samples stored for a prolonged period (20 years) under various storage conditions could be used for comparative methylation studies using reduced representation bisulfite sequencing.

PATIENTS & METHODS

Five groups of human blood DNA samples (n = 5-6/group) were compared. The groupings were based on the anticoagulant used and storage temperature and duration.

RESULTS

Methylation profiles of defined genomic regions in the DNA or blood samples archived for 20 years were similar across all storage temperatures, including 4°C. The level of intersample similarity in archived samples was not significantly different than that in recently collected samples.

CONCLUSION

Archived samples, including DNA stored at 4°C for 20 years, are suitable for comparative studies of DNA methylation.

Abstract P330: Customization of Low-sodium Diet and Its Efficacy

Introduction: Lack of adherence with a low-sodium (Na) diet remains a challenge for many patients. Most research studies use standardized diets for subjects which may decrease adherence and hence result in sub-optimal lowering of blood pressure (BP). We hypothesized that adoption of a customized low-Na diet will result in high rates of adherence, lower BP, and improve vascular function.

Methods: Post-menopausal women (50-65 years) and men (30-65 years) with baseline BP ≥ 130/80 mm Hg or history of HTN were recruited. Subjects were placed on a 2-week 1200mg Na/day diet (after a 3-day run-in period during which subjects were given 2400 mg of Na/day in addition to their regular diet). Subjects were off all BP medications 1 week prior to the start of the diet and during 2 weeks of study diet. All food was prepared by a bio-nutritionist with a customized menu according to food logs kept by the subjects. Two 24h urine Na measurements were taken to ensure compliance with the diet. In addition to BPs, conduit (brachial artery flow-mediated dilation (FMD)) and micro (~ 200 μm extracted from gluteal adipose tissue biopsies) vessel functions were evaluated before and after the diet period to assess in vivo and in vitro vascular function respectively.

Results: Seventeen subjects (9 African-American, 7 Caucasian, and 1 Hispanic) with mean BPs of 145 ± 14/87 ± 6 mm Hg (± SD) before starting the low-Na diet were recruited. During the diet period, subjects consumed an average of 1000 mg of Na/day (66% reduction from baseline Na intake). Excluding 2 subjects in whom the 24h urine Na did not drop (instead increased) after 2-weeks indicating non-adherence, the average SBP/DBP reductions were -11 ± 14 (-7%, p=0.06)/-8 ± 10 mm Hg (-9%, p=0.04). Average urine Na levels were 230 ± 83 (before) and 71 ± 82 (after) mmol/24hr. Brachial artery FMD improved from 7.3 ± 3.2 to 9.6 ± 2.3 % (p=0.04) after 2 weeks. Maximal Arteriolar FMD (endothelial dependent) trended toward an increase from 54 ± 18 to 77 ± 13 % and smooth muscle dependent dilation to papaverine was not effected.

Conclusions: The adoption of a customized low-Na diet can result in high rates of dietary adherence (88% in the current study) and lower BPs. In addition, vascular function improves within 2 weeks on a low-Na diet.

Abstract 129: In Defense of Clinic Blood Pressure

For genetic studies of hypertension, between 1994 and 2006, we established a cohort of 2,639 African Americans (53% female), 51% of whom were hypertensive (H). The purpose of this report is twofold: a) to evaluate the relationship of baseline hypertension status and blood pressure (BP) level with subsequent mortality in this cohort; and b) to compare the relationship of clinic and 24-hour BPs with the subsequent incidence of fatal and non-fatal cardiovascular (CV) events in a subset of the original cohort. Clinic BP was obtained in triplicate in all 2,369 subjects as part of screening procedures for a 3-day inpatient clinical study of a sub-sample (n=266). BP medications were discontinued for 1-week after the screening visit and prior to inpatient study. Detailed phenotyping along with 24-hour BPs were obtained during the 3-day study. Compared to normotensives (N) at baseline, H had higher standardized clinic BP (145 ± 20 [SD] / 94 ± 13 vs 118 ± 10/ 76 ± 8 mm Hg), were slightly older (45 ± 7 vs 42 ± 7 years; p<0.0001), and had higher BMI (29 ± 6 vs 27 ± 5 kg/m 2 ; p<0.0001) in the overall cohort. Mortality data were obtained from the National Death Index. Average time from baseline to mortality was 12 ± 3 years. All-cause mortality was related to clinic systolic BP (p<0.03) and was greater in H than N (176 vs 70 deaths; p< 0.0002) after adjustment for age, sex, BMI, and duration of follow-up. CV mortality was also greater in H than N (52 vs 19 deaths; p<0.01). During a follow-up of 14 ± 4 years of the in-patient cohort, 49 subjects had a fatal (n=11) or non-fatal (n=38) CV event. After adjustment for covariates, clinic systolic and diastolic BPs were strongly associated with CV events (p<0.0001). The association of clinic BPs with CV events was as robust as the associations with overall 24-hour BP, day BP, and night BP. Average difference between day and night BP was 7 ± 8/5 ± 6 mm Hg (p< 0.0001), but day-night BP difference was not associated with CV events (p=0.45). In conclusion, in middle-aged African Americans, 24-hour BPs were no more predictive of CV events than BPs measured during a single outpatient visit. In addition, both all-cause mortality and CV mortality were related to the clinic BP. These results will require confirmation with larger sample sizes.

Abstract P528: Modifiable Factors Affecting BP in Identical Twins

Background: Genetic factors determining blood pressure (BP) are largely unmodifiable. Understanding the effects of physiologic, environmental, and epigenetic (modifiable) factors on BP levels can improve strategies for hypertension (HTN) control. Monozygotic (MZ) twins with identical genetic background are a good model to study the effect of these factors on BP.

Methods: Seventy pairs of MZ twins were from Milwaukee, WI and Michigan State University Twin Registry, East Lansing, MI (62% women; age of 44 ± 10 years). BPs (measured in triplicate and averaged), anthropometrics, physical activity (Rapid Assessment of Physical Activity), and sodium intake measurements (Block Sodium Screener) were obtained. DNA was obtained from T-lymphocytes for methylation (epigenetic) sequencing analysis. Differences in systolic (SBP) and diastolic (DBP) BPs between co-twins were used as continuous variables for these analyses.

Results: Mean SBP was 124 ± 15 mm Hg (mean ± SD) and DBP was 78 ± 11 mm Hg. Average differences in SBP and DBP among co-twins were 8 ± 9 and 7 ± 6 mm Hg respectively. Twin pairs were considered concordant or discordant based on BP difference of 10 mm Hg between co-twins or one twin being hypertensive. Discordant twins as a group had higher BMI and waist circumference (WC) compared to concordant twins (p<0.05). Among discordant twins, the co-twin with higher BPs tended to have higher waist circumference (WC) (105 ± 15 vs. 98 ± 18 cm) and dietary salt intake (3900 ± 1437 vs. 3261 ± 1058 mg/d) even though they did not reach statistical significance. There were no differences in physical activity or education levels. Genome-wide methylation analyses revealed that 3 loci were associated with SBP difference and 2 were associated with DBP difference at an unadjusted significance level of p < 10 -4 . Two sites reached an adjusted significance level of 0.08 with SBP difference.

Conclusions: In this study, we identified several differentially methylated sites of interest in relation to BP among MZ twins. In addition, higher central adiposity and sodium intake may contribute to BP levels among MZ twins. Understanding the relationship of modifiable risk factors such as WC and sodium intake with methylation changes may shed light into novel pathogenic pathways for HTN.

Effect of gender and adiposity on in vivo vascular function in young African Americans

The relationship between obesity and high blood pressure is not as strong among African Americans (AA) as compared to Caucasians. We designed the current study to determine the effect of adiposity on vascular endothelial function (a harbinger of hypertension) among young healthy AA without additional cardiovascular disease risk factors. A total of 108 AA subjects (46 women) between the ages of 18 and 45 years were recruited. All the subjects were normotensive, nonsmokers, and normoglycemic. Anthropometric and cardiovascular disease risk factor measurements (lipid, insulin resistance, and inflammatory markers) were obtained. Vascular endothelial function was measured by brachial artery flow-mediated dilation (FMD). Adiposity distribution was measured by using magnetic resonance imaging scan. There were no gender differences in age and levels of blood pressure, lipids, insulin resistance, and inflammatory markers. Women had higher total body fat percentage and higher peripheral adiposity compared to men. We observed that total and central adiposity did not correlate significantly with brachial artery FMD in women (r = -0.12 and r = 0.23, respectively; P = NS). However, in men, waist circumference was positively associated with FMD (r = 0.3, P ≤ .05). Hyperemic flow was negatively correlated significantly with total and central adiposity in men (r = -0.34 and r = -0.48, respectively; P < .05), but not in women (r = -0.26 and r = 0.03, respectively; P = NS). Our study suggests that increased adiposity may pose greater risk to AA men compared to AA women by adversely affecting resistance vessel function (as measured by hyperemic flow). Larger studies are necessary to validate these findings.

Clinic and ambulatory blood pressure in a population-based sample of African Americans: the Jackson Heart Study

Blood pressure (BP) can differ substantially when measured in the clinic versus outside of the clinic setting. Few population-based studies with ambulatory blood pressure monitoring (ABPM) include African Americans. We calculated the prevalence of clinic hypertension and ABPM phenotypes among 1016 participants in the population-based Jackson Heart Study, an exclusively African-American cohort. Mean daytime systolic BP was higher than mean clinic systolic BP among participants not taking antihypertensive medication (127.1[standard deviation 12.8] vs. 124.5[15.7] mm Hg, respectively) and taking antihypertensive medication (131.2[13.6] vs. 130.0[15.6] mm Hg, respectively). Mean daytime diastolic BP was higher than clinic diastolic BP among participants not taking antihypertensive medication (78.2[standard deviation 8.9] vs. 74.6[8.4] mm Hg, respectively) and taking antihypertensive medication (77.6[9.4] vs. 74.3[8.5] mm Hg, respectively). The prevalence of daytime hypertension was higher than clinic hypertension for participants not taking antihypertensive medication (31.8% vs. 14.3%) and taking antihypertensive medication (43.0% vs. 23.1%). A high percentage of participants not taking and taking antihypertensive medication had nocturnal hypertension (49.4% and 61.7%, respectively), white-coat hypertension (30.2% and 29.3%, respectively), masked hypertension (25.4% and 34.6%, respectively), and a nondipping BP pattern (62.4% and 69.6%, respectively). In conclusion, these data suggest hypertension may be misdiagnosed among African Americans without using ABPM.

Abstract P139: Stability of DNA Methylation Profiles in Human DNA Samples in Long Term Storage

Introductions: Historic DNA samples represent a potentially highly valuable resource for epigenetic analysis. Reduced representation bisulfite sequencing (RRBS) is a cost-effective, near genome-wide method for quantifying DNA methylation levels at single base resolution. It is unknown whether historic DNA samples stored for a long time (15-20 years) under various conditions could maintain stable methylation profiles as determined by RRBS.

Methods: We used 5 groups of DNA samples (n=4 in each group) to compare and evaluate the stability of DNA methylation profiles under standard storage conditions of 4°C since 1996. Group 1 had been extracted from EDTA-anticoagulated blood and stored at 4°C since 1996; Group 2 had been diluted from group 1 to 10ng/μl and stored at -20°C since 2009; Group 3 were extracted from citrate-anticoagulated blood stored at -80°C since 1996; Group 4 were extracted from fresh EDTA-anticoagulated blood; Group 5 were extracted from fresh citrate-anticoagulated blood. The samples in groups 1, 2 and 3 were from the same subjects. All DNA samples were processed for RRBS libraries and then sequenced.

Results: The global methylation level of group 1 was lower than group 2 (36.88±4.12% vs 43.66±1.29%, p=0.04), but was not statistically different from group 3 (44.31±1.46%, p=0.07). The methylation level of groups 4 and 5 (40.34±3.73% and 38.64±1.94%) was not significantly different. In addition, group 4 and 5 were not significantly different from group 1. The correlation of methylation levels for all CpG sites between individual samples in group 1 (0.987±0.001) was higher than that in group 2 and group 3 (0.984±0.002, p=0.01, and 0.969±0.015, p=0.01) and not significantly different from group 4 or 5. For CpG sites within CpG islands (CGI), the correlation between individual samples was not significantly different between any of the 5 groups. Moreover, the samples from the same subject show high correlation levels between groups 1, 2, and 3 for all CpG sites (0.987±0.006) and CpG sites within CGI (0.983±0.009).

Conclusion: DNA samples stored at 4°C for prolonged periods of time are amenable to RRBS analysis. In addition, there were no significant differences in the DNA methylation profiles between citrate- and EDTA-anticoagulated blood.

Abstract P264: DNA Methylation and Differences in Blood Pressure Levels in Monozygotic Twins

Background: The development of common forms of hypertension (HTN) involves both genetic and environmental factors. Methylation changes (one of the epigenetic modifications) of DNA may play a role in the regulation of BP and development of HTN, and may result from interaction of specific genes with the environment. The current study investigates the relationship between genome-wide changes in DNA methylation in T-lymphocytes and BP level differences among monozygotic twins, who have identical DNA sequences.

Methods: In a preliminary study, we recruited 24 pairs of monozygotic twins (60% women) with a mean age of 44 ± 10 years. Zygosity was determined via self-report or participants’ responses to a standard zygosity questionnaire. BPs were measured in triplicate after 5 minutes of rest at one minute intervals and averaged. Anthropometrics measurements were obtained along with blood for isolation of T-lymphocytes. DNA from T-lymphocytes was used to perform reduced representation bisulfite sequencing (RRBS) to measure methylation levels at single-base resolution in these subjects. Average differences in systolic (SBP) and diastolic (DBP) BPs were used as continuous variables for these analyses.

Results: Mean SBP was 124 ± 15 (range (r): 97-174) mm Hg and mean DBP was 78 ± 11 (r: 49-106) mm Hg. Average differences in SBP and DBP among the co-twins (members of a twin pair) were 9 ± 10 (r: 0-40) mm Hg and 8 ± 6 (r: 0-26) mm Hg respectively. Average BMI was 29 ± 8 kg/m 2 . We observed that an average of 3063 (r: 757-7250) CpG islands were differentially methylated (DMRs) between co-twins. Among these DMRs, 10 were associated with average SBP difference and 5 were associated with average DBP difference at a significance level of p < 0.001. DMRs showing the strongest association (unadjusted p < 10 -4 ) between the co-twins were located in the transcriptional start site (TSS) of genes: CDC26 (cell division cycle protein) and NR2F6 (nuclear receptor) for average SBP difference and LEPRE1 (propyl 3 hydroxylase protein) for average DBP difference.

Conclusions: BP differences between monozygotic co-twins, which most likely result from environmental factors, appear to be associated with differences in DNA methylation in T lymphocytes.

Abstract P136: Dietary Salt and Non-Salt Components Have Substantial Effects on Genome-Wide DNA Methylation Patterns in Dahl SS Rats

Epigenetic modifications of the genome play a key role in the regulation of gene expression. It has been reported that epigenetic modifications of several genes are associated with hypertension. To investigate the potential role of genome-wide changes in DNA methylation in salt-induced hypertension, experiments were performed on inbred Dahl SS rats obtained from two colonies maintained at the Medical College of Wisconsin (i.e. MCWSS) and Charles River Laboratory (CRLSS). The colonies are genetically identical, but CRLSS rats were maintained on a whole grain diet containing 1% NaCl (CRLSS_LS) while MCWSS rats were fed casein-based AIN-76A chow containing 0.4% NaCl (MCWSS_LS) until both colonies were switched to an AIN-76A chow containing 4% NaCl for 14 days starting at 6 weeks of age (CRLSS_HS and MCWSS_HS, respectively). Mean arterial pressure and albumin excretion rate in MCWSS_HS rats were significantly greater (142±14 mmHg and 100±16 mg/day, n=6) than in CRLSS_HS rats (118±2 mmHg and 20±2 mg/day, n=7). Reduced representation bisulfite genome sequencing (RRBS) measured 5-Methylcytosine levels at single-base resolution in the renal outer medulla in the above groups, each with four biological replicates. For genomic regions located within CpG islands (CGI’s) and exhibiting differential methylation between LS and HS in each colony, HS diet increased median methylation levels several-fold in both MCWSS (7.45% vs. 0.35% for MCWSS_HS vs. MCWSS_LS, respectively, p = 2.84E-31) and CRLSS rats (7.62% vs. 1.21% for CRLSS_HS vs. CRLSS_LS, respectively, p = 1.65E-32). For genomic regions exhibiting differential methylation between MCWSS and CRLSS, MCWSS_HS rats (which exhibited higher blood pressure) had higher median methylation levels than CRLSS_HS rats (7.56% vs. 2.75%, p = 2.12E-9). We observed 156 hypermethylated and 241 hypomethylated regions within CGI’s of MCWSS_LS compared to CRLSS_LS. Examples of differentially methylated genes include the serine protease Prss2 , the transcription factor E2f1 , and the matrix protein Spock2 . These results suggest that sodium-dependent and independent dietary components could induce changes in DNA methylation that may predispose and participate in the development of hypertension and renal damage.

Adiponectin Levels Differentiate Metabolically Healthy vs Unhealthy Among Obese and Nonobese White Individuals

CONTEXT

Adiponectin levels (ADPN) are lower in individuals with central obesity and cardiometabolic diseases. Conversely, studies have shown paradoxical hyperadiponectinemia (HA) in metabolically healthy obese (MHO) individuals of non-European descent. Moreover, individuals with higher sc to visceral adipose tissue (ie, higher peripheral adiposity) distribution have higher ADPNs. However, it is not known whether metabolically healthy individuals have predominantly peripheral adiposity along with higher ADPNs.

OBJECTIVE

This study aimed to evaluate the association of ADPN and adiposity distribution with metabolic health in white individuals.

DESIGN AND SETTING

This was a cross-sectional study of members of "Take Off Pounds Sensibly" weight loss club and their relatives.

PARTICIPANTS

We recruited 2486 (72% women, 61% obese) individuals. They were defined as metabolically healthy by absence of hypertension, diabetes, and dyslipidemia; and they were further classified into metabolically healthy nonobese (MHNO), metabolically unhealthy nonobese (MUNO), metabolically healthy obese (MHO), and metabolically unhealthy obese (MUO). Waist-to-hip ratios (WHRs) were used as markers of adiposity distribution. Insulin resistance was measured using homeostasis model assessment.

RESULTS

Among the four groups, MHNO had the lowest WHRs (higher peripheral adiposity) and highest ADPN, and MUO had highest WHRs (higher central adiposity) and lowest ADPN (P < .001). Among both nonobese and obese, metabolically healthy individuals had higher ADPN than metabolically unhealthy individuals (P < .05) after adjustment for age, sex, and body mass index. MHNO also had lower WHRs compared with MUNO (P < .01). Although WHRs were lower among MHO compared with MUO, the difference was not significant. In addition, nonobese and obese individuals with HA (defined using sex-specific cutoffs) had lower homeostasis model assessment and dyslipidemia compared with individuals without HA.

CONCLUSIONS

Higher ADPN and lower WHRs (higher peripheral adiposity) are associated with better metabolic health in both nonobese and obese white individuals. These results suggest that ADPN and peripheral adiposity play a key role in determining the metabolic health independent of body mass index.

Effects of simvastatin and ezetimibe in lowering low-density lipoprotein cholesterol in subjects with type 1 and type 2 diabetes mellitus

OBJECTIVE

Statins are used to lower total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) levels among patients with type 1 (T1DM) and type 2 diabetes mellitus (T2DM). However, there are no studies of statin efficacy among T1DM patients. T1DM patients have higher gut cholesterol absorption than synthesis; hence cholesterol absorption inhibitors such as ezetimibe may also be effective in T1DM. Here, we compare the effects of simvastatin and ezetimibe among subjects with T1DM and T2DM.

RESEARCH DESIGN AND METHODS

Subjects with T1DM (n=20, 45% female) or T2DM (n=27, 56% female) were assigned to alternating therapy with simvastatin (40 mg) or ezetimibe (10 mg) for 6 weeks in a crossover design.

RESULTS

Among T2DM subjects, simvastatin lowered TC and LDL-C from the baseline (-25±4% and -40±5%, respectively, P<0.001), whereas ezetimibe was not as effective (-2±4% and -3±5%, respectively). Among T1DM subjects, both statin and ezetimibe showed significant decreases in TC and LDL-C from baseline, although ezetimibe lowered LDL-C much more than simvastatin (-32±12 (P<0.001) and -19±5% (P<0.01), respectively). Effect of simvastatin on LDL-C was much lower among T1DM subjects compared to T2DM subjects (P=0.02).

CONCLUSIONS

This study shows that the cholesterol synthesis inhibitor simvastatin was less effective in lowering LDL-C in T1DM than T2DM subjects, whereas the cholesterol absorption inhibitor ezetimibe was at least as effective in lowering LDL-C as simvastatin among T1DM subjects.

Adiposity distribution influences circulating adiponectin levels

Thirty percent of obese individuals are metabolically healthy and were noted to have increased peripheral obesity. Adipose tissue is the primary source of adiponectin, an adipokine with insulin-sensitizing and anti-inflammatory properties. Lower adiponectin levels are observed in individuals with obesity and those at risk for cardiovascular disease. Conversely, higher levels are noted in some obese individuals who are metabolically healthy. Our objective was to determine whether abdominal adiposity distribution, rather than body mass index (BMI) status, influences plasma adiponectin level. A total of 424 subjects (female, 255) of Northern European ancestry were recruited from "Take Off Pounds Sensibly" weight loss club members. Demographics, anthropometrics, and dual-emission x-ray absorptiometry of the whole body, and computed tomography scan of the abdomen were performed to obtain total body fat content and to quantify subcutaneous adipose tissue (SAT) and visceral adipose tissue (VAT), respectively. Laboratory measurements included fasting plasma glucose, insulin, lipid panel, and adiponectin. Age- and gender-adjusted correlation analyses showed that adiponectin levels were negatively correlated with BMI, waist circumference, triglycerides, total fat mass, and VAT. A positive correlation was noted with high-density lipoprotein cholesterol and fat-free mass (P < 0.05). SAT-to-VAT ratios were also significantly associated with adiponectin (r = 0.13, P = 0.001). Further, the best positive predictors for plasma adiponectin were found to be SAT-to-VAT ratios and gender by regression analyses (P < 0.01). Abdominal adiposity distribution is an important predictor of plasma adiponectin and obese individuals with higher SAT-to-VAT ratios may have higher adiponectin levels.

Non-replication study of a genome-wide association study for hypertension and blood pressure in African Americans

Background

A recent genome wide association study in 1017 African Americans identified several single nucleotide polymorphisms that reached genome-wide significance for systolic blood pressure. We attempted to replicate these findings in an independent sample of 2474 unrelated African Americans in the Milwaukee metropolitan area; 53% were women and 47% were hypertensives.

Methods

We evaluated sixteen top associated SNPs from the above genome wide association study for hypertension as a binary trait or blood pressure as a continuous trait. In addition, we evaluated eight single nucleotide polymorphisms located in two genes (STK-39 and CDH-13) found to be associated with systolic and diastolic blood pressures by other genome wide association studies in European and Amish populations. TaqMan MGB-based chemistry with fluorescent probes was used for genotyping. We had an adequate sample size (80% power) to detect an effect size of 1.2-2.0 for all the single nucleotide polymorphisms for hypertension as a binary trait, and 1% variance in blood pressure as a continuous trait. Quantitative trait analyses were performed both by excluding and also by including subjects on anti-hypertensive therapy (after adjustments were made for anti-hypertensive medications).

Results

For all 24 SNPs, no statistically significant differences were noted in the minor allele frequencies between cases and controls. One SNP (rs2146204) showed borderline association (p = 0.006) with hypertension status using recessive model and systolic blood pressure (p = 0.02), but was not significant after adjusting for multiple comparisons. In quantitative trait analyses, among normotensives only, rs12748299 was associated with SBP (p = 0.002). In addition, several nominally significant associations were noted with SBP and DBP among normotensives but none were statistically significant.

Conclusions

This study highlights the importance of replication to confirm the validity of genome wide association study results.

Cardiovascular correlates of insulin resistance in normotensive and hypertensive African Americans

Insulin resistance (IR) is associated with obesity and predisposes to diabetes mellitus (DM) and cardiovascular disease. The purpose of this study is to determine if IR is related to cardiovascular function independent of DM or hypertension among African Americans (AA). Four hundred sixty-two nondiabetic AA (50% hypertensive and 51% women) were studied on an inpatient General Clinical Research Center. Measurements included anthropometrics and 24-hour blood pressure (BP), heart rate (HR), fasting blood glucose, plasma aldosterone, and insulin. Stroke volume (SV) and cardiac output (CO) were measured by impedance plethysmography; peripheral vascular resistance (PVRI) and vascular compliance indices (VCI) were computed. These measurements were also obtained in response to mental (computerized math testing) and pharmacologic (graded norepinephrine infusion) stress. Insulin resistance was calculated using the homeostasis model assessment (HOMA-IR). SV, CO, and VCI decreased with increasing HOMA-IR, whereas HR and PVRI increased. Overall, BP, HR, and PVRI were positively correlated with HOMA-IR (P < .01); and SV index, cardiac index, and VCI were negatively correlated with HOMA-IR (P < .0001). The correlations persisted after adjustment for BP, age, sex, plasma aldosterone, total cholesterol, or low-density lipoprotein and high-density lipoprotein cholesterol. In addition, multiple linear regression analyses showed that HOMA-IR contributes to the maximum variability of all the hemodynamic variables. Blood pressure responses to math stress and norepinephrine infusion did not correlate with HOMA-IR. Unrelated to DM and BP, IR is associated with increased PVRI and decreased CO in AA. These observations suggest that an exclusive focus on effects of IR on DM or BP may ignore independent pathophysiologic contributions of IR to cardiovascular disease.

Cholesterol and non-cholesterol sterol transporters: ABCG5, ABCG8 and NPC1L1: a review

1. Whole-body sterol (cholesterol and xenosterol) balance is delicately regulated by the gastrointestinal tract and liver, which control sterol absorption and excretion, respectively, in addition to the contribution to the cholesterol pool by whole-body cholesterol synthesis. In the past ten years enormous strides have been made not only in establishing that specific transporters mediate the entry and exit of sterols and how these may regulate selective sterol access to the body pools, but also in how these pathways operate to integrate these physiological pathways. 2. The entry of sterols from the gastrointestinal and biliary canalicular lumen into the body is mediated by NPC1L1, which was discovered by a novel method, via a genomics-bioinformatics approach. 3. Identification of the genetic basis responsible for causing sitosterolaemia, characterized by plant sterol accumulation, led to the identification of two half-transporters (ABCG5 and ABCG8) that normally efflux plant sterols (and cholesterol) into the intestinal and biliary lumen for faecal excretion. 4. The objective of this review is to provide up-to-date knowledge on genomics, proteomics and function of these two transporter systems.

Sitosterolaemia: pathophysiology, clinical presentation and laboratory diagnosis

Sitosterolaemia is an extremely rare autosomal recessive disease, the key feature of which is the impairment of pathways that normally prevent absorption and retention of non-cholesterol sterols, for example plant sterols and shellfish sterols. The clinical manifestations are akin to familial hypercholesterolaemia (such as presence of tendon xanthomas and premature atherosclerosis), but with "normal to moderately elevated" cholesterol levels. The gene(s) causing sitosterolaemia was mapped to the STSL locus on human chromosome 2p21, and mutations in either of the two genes that comprise this locus, ABCG5 or ABCG8, cause this disease. Exact prevalence is unknown, but there are estimated to be 80-100 cases around the world. This rare disease has shed light into the molecular mechanisms that control sterol trafficking in the enterocyte and hepatocyte; ABCG5 and ABCG8 heterodimerise to form a sterol efflux transporter in the liver and intestine. In this review the pathophysiology, clinical manifestations and approach to clinical and laboratory diagnosis of this disease are described.