Cardiovascular Disease Risk In Humans Research Articles

Lactobacillus plantarum 299v administration prevents high-sodium diet-induced glycocalyx degradation and arterial dysfunction

A central feature of cardiovascular disease (CVD) is arterial dysfunction (i.e., elevated systolic blood pressure [BP], aortic stiffening, and endothelial dysfunction), which may be initiated by a degraded endothelial glycocalyx. The glycocalyx is a negatively charged structure bound to the vascular endothelium that appears to play a critical role in cardiovascular health, particularly by buffering sodium in blood, although excessive sodium degrades the glycocalyx. In the United States, a high-sodium (HS) diet is consumed by ~90% of the population with average sodium intake ~2.3x greater than recommended by the American Heart Association. We have previously shown that HS diet induces glycocalyx degradation and arterial dysfunction in outbred, genetically diverse UM-HET3 mice. Others have shown that HS diet lowers Lactobacillus abundance in mouse gut microbiome. However, it is unknown whether maintaining Lactobacillus would prevent HS diet-induced glycocalyx degradation and arterial dysfunction. To test this concept, male and female UM-HET3 mice (n=21-35/group) were randomized into a low-sodium (LS) diet (1% NaCl), HS diet (4% NaCl), or HS diet with Lactobacillus plantarum 299v (Lp299v) administration (60 million CFU/ml in drinking water) for 12 weeks. Glycocalyx barrier function was determined by assessing perfused boundary region (PBR), which represents red blood cell penetration into the glycocalyx. At week 12, we observed higher PBR in HS mice (2.36±0.04 μm) compared to LS and HS+Lp299v mice (2.09±0.03 and 2.20±0.04 μm, respectively; p<0.05), indicating a worse glycocalyx barrier function in HS mice. PBR was similar between LS and HS+Lp299v mice (P>0.05), indicating a preserved glycocalyx barrier function in HS+Lp299v mice. Systolic BP was higher in HS (127±1 mmHg) compared to LS and HS+Lp299v mice (113±1 and 118±1 mmHg, respectively; p<0.05). Aortic stiffness, determined by aortic pulse wave velocity (PWV), was also higher in HS (345±5 cm/s) compared to LS and HS+Lp299v mice (268±5 and 300±3 cm/s, respectively; p<0.05). However, systolic BP and aortic PWV were higher in HS+Lp299v compared to LS mice (p<0.05). Ex vivo endothelial function, determined by the maximal vasodilatory response to acetylcholine in the carotid artery, was lower in HS (83.9±1.3%) compared to LS and HS+Lp299v mice (89.8±1.3 and 90.1±1.0%, respectively; p<0.05). Endothelial function was similar between LS and HS+Lp299v mice (P>0.05). In summary, Lp299v administration prevents HS diet-induced glycocalyx degradation and endothelial dysfunction, while mitigating HS diet-induced elevations in systolic BP and aortic stiffness. These findings suggest that Lp299v administration may be a novel strategy to lower the risk of CVD in humans that consume a HS diet. This study was funded in part by a grant from the National Institutes of Health (R00 AT010017). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Identification of genetic drivers of plasma lipoprotein size in the Diversity Outbred mouse population

Despite great progress in understanding lipoprotein physiology, there is still much to be learned about the genetic drivers of lipoprotein abundance, composition, and function. We used ion mobility spectrometry to survey 16 plasma lipoprotein subfractions in 500 Diversity Outbred mice maintained on a Western-style diet. We identified 21 quantitative trait loci (QTL) affecting lipoprotein abundance. To refine the QTL and link them to disease risk in humans, we asked if the human homologs of genes located at each QTL were associated with lipid traits in human genome-wide association studies. Integration of mouse QTL with human genome-wide association studies yielded candidate gene drivers for 18 of the 21 QTL. This approach enabled us to nominate the gene encoding the neutral ceramidase, Asah2, as a novel candidate driver at a QTL on chromosome 19 for large HDL particles (HDL-2b). To experimentally validate Asah2, we surveyed lipoproteins in Asah2−/− mice. Compared to wild-type mice, female Asah2−/− mice showed an increase in several lipoproteins, including HDL. Our results provide insights into the genetic regulation of circulating lipoproteins, as well as mechanisms by which lipoprotein subfractions may affect cardiovascular disease risk in humans.

Pregnane X Receptor Mediates Atherosclerosis Induced by Dicyclohexyl Phthalate in LDL Receptor-Deficient Mice.

Plastic-associated endocrine disrupting chemicals (EDCs) have been implicated in the etiology of cardiovascular disease (CVD) in humans, but the underlying mechanisms remain elusive. Dicyclohexyl phthalate (DCHP) is a widely used phthalate plasticizer; whether and how exposure to DCHP elicits adverse effects in vivo is mostly unknown. We previously reported that DCHP is a potent ligand of the pregnane X receptor (PXR) which acts as a xenobiotic sensor to regulate xenobiotic metabolism. PXR also functions in macrophages to regulate atherosclerosis development in animal models. In the current study, LDL receptor-deficient mice with myeloid-specific PXR deficiency (PXRΔMyeLDLR−/−) and their control littermates (PXRF/FLDLR−/−) were used to determine the impact of DCHP exposure on macrophage function and atherosclerosis. Chronic exposure to DCHP significantly increased atherosclerotic lesion area in the aortic root and brachiocephalic artery of PXRF/FLDLR−/− mice by 65% and 77%, respectively. By contrast, DCHP did not affect atherosclerosis development in PXRΔMyeLDLR−/− mice. Exposure to DCHP led to elevated expression of the scavenger receptor CD36 in macrophages and increased macrophage form cell formation in PXRF/FLDLR−/− mice. Our findings provide potential mechanisms underlying phthalate-associated CVD risk and will ultimately stimulate further investigations and mitigation of the adverse effects of plastic-associated EDCs on CVD risk in humans.

Lymphocyte Activation Gene-3 Regulates Dendritic Cell Metabolic Programing and T Cell Priming Function.

Deficiency of lymphocyte activation gene-3 (LAG3) is significantly associated with increased cardiovascular disease risk with in vitro results demonstrating increased TNF-α and decreased IL-10 secretion from LAG3-deficient human B lymphoblasts. The hypothesis tested in this study was that Lag3 deficiency in dendritic cells (DCs) would significantly affect cytokine expression, alter cellular metabolism, and prime naive T cells to greater effector differentiation. Experimental approaches used included differentiation of murine bone marrow-derived DCs (BMDCs) to measure secreted cytokines, cellular metabolism, RNA sequencing, whole cell proteomics, adoptive OT-II CD4+Lag3 +/+ donor cells into wild-type (WT) C57BL/6 and Lag3 -/- recipient mice, and ex vivo measurements of IFN-γ from cultured splenocytes. Results showed that Lag3 -/- BMDCs secreted more TNF-α, were more glycolytic, used fewer fatty acids for mitochondrial respiration, and glycolysis was significantly reduced by exogenous IL-10 treatment. Under basal conditions, RNA sequencing revealed increased expression of CD40 and CD86 and other cytokine-signaling targets as compared with WT. Whole cell proteomics identified a significant number of proteins up- and downregulated in Lag3 -/- BMDCs, with significant differences noted in exogenous IL-10 responsiveness compared with WT cells. Ex vivo, IFN-γ expression was significantly higher in Lag3 -/- mice as compared with WT. With in vivo adoptive T cell and in vitro BMDC:T coculture experiments, Lag3 -/- BMDCs showed greater T cell effector differentiation and proliferation, respectively, compared with WT BMDCs. In conclusion, Lag3 deficiency in DCs is associated with an inflammatory phenotype that provides a plausible mechanism for increased cardiovascular disease risk in humans with LAG3 deficiency.

An abundant biliary fatty acid metabolite derived from dietary omega-3 polyunsaturated fatty acids regulates triglycerides

Background and Aims: Omega-3 fatty acids from fish oil reduce triglyceride levels in mammals, yet the mechanisms underlying this effect have not been fully clarified despite the clinical use of omega-3 ethyl esters to treat severe hypertriglyceridemia and reduce cardiovascular disease risk in humans. Here we identify in bile a class of hypotriglyceridemic omega-3 fatty acid-derived N-acyl taurines (NATs) that, after dietary omega-3 fatty acid supplementation, increase to concentrations similar to those of steroidal bile acids. We aimed to determine physiological function of this metabolite.

Age-related carotid extra-media thickening is associated with increased blood pressure and arterial stiffness.

Ageing results in higher blood pressure and arterial stiffening leading to increased cardiovascular disease (CVD) risk. The extra-media thickness (EMT) is a composite measure of the arterial adventitia, perivascular adipose tissue (PVAT) and the jugular vein, but the association among EMT and ageing, blood pressure and arterial stiffness is largely unknown. We hypothesized that EMT is associated with ageing, blood pressure and arterial stiffness. Fifty (18M/32F, age range 20-79years.) individuals underwent measures of EMT (media-adventitia border to jugular lumen interface) via ultrasonography, blood pressure (brachial; carotid), arterial stiffness (carotid beta-stiffness, distensibility and Young's modulus) and body composition (dual X-ray absorptiometry). Independent two-tailed t-tests compared characteristics between young and middle-aged/older adults (MA/O). Bivariate correlations assessed the relation between EMT, ageing, blood pressure and arterial stiffness endpoints. Partial correlations were used to adjust for age, sex, body mass index (BMI) and body fat percentage. Compared to young, MA/O adults had higher EMT, blood pressure, arterial stiffness, BMI and BF% (all, p≤0.05). Carotid EMT was positively correlated with age (r=0.46), brachial SBP (r=0.32), carotid SBP (r=0.42), PP (r=0.42), beta-stiffness (r=0.37) and Young's elastic modulus (r=0.43) (all, p≤0.05), and negatively correlated with carotid distensibility (r=-0.34, p≤0.05). All endpoints correlated with EMT remained after adjusting for BMI, BF% and sex (p≤0.05). These data suggest EMT is a clinically relevant target that may be associated with age-related CVD risk in humans, yet further investigation is required to elucidate the role of EMT in age-related increases in blood pressure and arterial stiffness.

The role of triglycerides in the origin and progression of atherosclerosis

Hypertriglyceridaemia has been associated with cardiovascular disease risk in humans for several decades. However, only recently, data from basic research, as well as from genetic and observational studies, have suggested triglyceride-rich lipoproteins (TRLs) as causal factors for atherosclerotic cardiovascular disease. Novel findings highlighting the relevance of TRL-derived lipolytic products (remnant lipoprotein particles “RLPs”), rather than plasma triglycerides or TRL themselves, as the true mediators in atherosclerosis, have contributed to explain a causal relationship through a number of direct and indirect mechanisms. Thus, experimental studies in animal models and in vitro cell culture methods reveal that RLPs, having sizes below 70–80nm, enter the arterial wall and accumulate within the sub-endothelial space. They then become involved in the cholesterol deposition of cholesterol in the intima in addition to several pro-inflammatory and pro-apoptotic pathways. In this review, a summary is presented of current understanding of the pathophysiological mechanisms by which TRLs and their lipolytic derived RLP induce the formation and progression of atherosclerotic lesions, and actively contribute to cardiovascular disease.

An abundant biliary metabolite derived from dietary omega-3 polyunsaturated fatty acids regulates triglycerides.

Omega-3 fatty acids from fish oil reduce triglyceride levels in mammals, yet the mechanisms underlying this effect have not been fully clarified, despite the clinical use of omega-3 ethyl esters to treat severe hypertriglyceridemia and reduce cardiovascular disease risk in humans. Here, we identified in bile a class of hypotriglyceridemic omega-3 fatty acid-derived N-acyl taurines (NATs) that, after dietary omega-3 fatty acid supplementation, increased to concentrations similar to those of steroidal bile acids. The biliary docosahexaenoic acid-containing (DHA-containing) NAT C22:6 NAT was increased in human and mouse plasma after dietary omega-3 fatty acid supplementation and potently inhibited intestinal triacylglycerol hydrolysis and lipid absorption. Supporting this observation, genetic elevation of endogenous NAT levels in mice impaired lipid absorption, whereas selective augmentation of C22:6 NAT levels protected against hypertriglyceridemia and fatty liver. When administered pharmacologically, C22:6 NAT accumulated in bile and reduced high-fat diet-induced, but not sucrose-induced, hepatic lipid accumulation in mice, suggesting that C22:6 NAT is a negative feedback mediator that limits excess intestinal lipid absorption. Thus, biliary omega-3 NATs may contribute to the hypotriglyceridemic mechanism of action of fish oil and could influence the design of more potent omega-3 fatty acid-based therapeutics.

Atherosclerosis Regression and Cholesterol Efflux in Hypertriglyceridemic Mice.

[Figure: see text].

The Molecular Basis of Predicting Atherosclerotic Cardiovascular Disease Risk.

Atherosclerotic cardiovascular disease (ASCVD) proceeds through a series of stages: initiation, progression (or regression), and complications. By integrating known biology regarding molecular signatures of each stage with recent advances in high-dimensional molecular data acquisition platforms (to assay the genome, epigenome, transcriptome, proteome, metabolome, and gut microbiome), snapshots of each phase of atherosclerotic cardiovascular disease development can be captured. In this review, we will summarize emerging approaches for assessment of atherosclerotic cardiovascular disease risk in humans using peripheral blood molecular signatures and molecular imaging approaches. We will then discuss the potential (and challenges) for these snapshots to be integrated into a personalized movie providing dynamic readouts of an individual's atherosclerotic cardiovascular disease risk status throughout the life course.

Understanding connections and roles of gut microbiome in cardiovascular diseases.

The gut microbiome encompasses trillions of residing microbes, mainly bacteria, which play a crucial role in maintaining the physiological and metabolic health of the host. The gut microbiome has been associated with several diseases, including cardiovascular disease (CVD). A growing body of evidence suggests that an altered gut environment and gut-microbiome-derived metabolites are associated with CVD events. The gut microbiome communicates with host physiology through different mechanisms, including trimethylamine N-oxide generation, primary and secondary bile acid metabolism pathways, and short-chain fatty acids production. The main focus of this review is to understand the association of the gut microbiome with CVD and its implications on the interactions between the gut microbiome and the host. Manipulation of the gut microbiome through specific dietary intervention is a simple approach to identifying novel targets for therapy or better dietary recommendations, and new preventive measures for screening biomarkers to reduce CVD risk in humans.

Naive CD8+ T Cells Expressing CD95 Increase Human Cardiovascular Disease Severity.

Cardiovascular disease (CVD) remains a significant global health concern with a high degree of mortality. While CD4+ T cells have been extensively studied in CVD, the importance of CD8+ T cells in this disease, despite their abundance and increased activation in human atherosclerotic plaques, remains largely unknown. Thus, the objective of this study was to compare peripheral T-cell signatures between humans with a high (severe) risk of CVD (including myocardial infarction or stroke) and those with a low risk of CVD. Approach and Results: Using mass cytometry, we uncovered a naive CD8+ T (TN) cell population expressing CD95 (termed CD95+CD8+ stem cell memory T [CD8 TSCM] cells) that was enriched in patients with high compared with low CVD. This T-cell subset enrichment within individuals with high CVD was a relative increase and resulted from the loss of CD95lo cells within the TN compartment. We found that CD8 TSCM cells positively correlated with CVD risk in humans, while CD8+ TN cells were inversely correlated. Atherosclerotic apolipoprotein E-deficient (ApoE-/-) mice also displayed respective 7- and 2-fold increases in CD8+ TSCM frequencies within the peripheral blood and aorta-draining paraaortic lymph nodes compared with C57BL/6J mice. CD8+ TSCM cells were 1.7-fold increased in aortas from western diet fed ApoE-/- mice compared with normal laboratory diet-fed ApoE-/- mice. Importantly, transfer of TSCM cells into immune-deficient Rag.Ldlr recipient mice that lacked T cells increased atherosclerosis, illustrating the importance of these cells in atherogenesis. CD8+ TSCM cells are increased in humans with high CVD. As these TSCM cells promote atherosclerosis, targeting them may attenuate atherosclerotic plaque progression.

Continuous Light Does Not Affect Atherosclerosis in APOE*3-Leiden.CETP Mice.

Artificial light exposure is associated with dyslipidemia in humans, which is a major risk factor for the development of atherosclerotic cardiovascular disease. However, it remains unclear whether artificial light at night can exacerbate atherosclerosis. In this study, we exposed female APOE*3-Leiden.CETP mice, a well-established model for human-like lipid metabolism and atherosclerosis, to either a regular light-dark cycle or to constant bright light for 14 weeks. Mice exposed to constant light demonstrated a minor reduction in food intake, without any effect on body weight, body composition, or the weight of metabolic organs. Constant light increased the plasma levels of proatherogenic non–high-density lipoprotein (HDL) cholesterol but did not increase the size or severity of atherosclerotic lesions in the aortic root. Mice exposed to constant light did show lower immune cell counts, which could explain the absence of an effect of atherosclerosis despite increased non–HDL cholesterol levels. Behavioral analysis demonstrated variability in the response of mice to the light intervention. Constant light completely blunted behavioral rhythms in some mice, while others extended their behavioral period. However, rhythm strength was not an important determinant of atherosclerosis. Altogether, these results demonstrate that constant bright light does not affect atherosclerosis in APOE*3-Leiden.CETP mice. Whether artificial light exposure contributes to cardiovascular disease risk in humans remains to be investigated.

Dietary lipids and cardiometabolic health: a new vision of structure-activity relationship.

The impact of dietary lipids on cardiometabolic health was mainly studied considering their fatty acid composition. This review aims to present the recent change in paradigm whereby the food matrix, the molecular and supramolecular structures of dietary lipids modulate their digestive fate and cardiometabolic impact. Epidemiological studies have reported that the metabolic impact of full-fat dairy products is better than predictable upon saturated fatty acid richness. Milk polar lipid supplementation reduced adiposity and inflammation in rodents by modulating gut microbiota and barrier, and decreased lipid markers of cardiovascular disease risk in humans by lowering cholesterol absorption. The metabolic importance of the structure of lipid molecules carrying omega-3 (molecular carrier) has also been documented. Plant lipids exhibit specific assemblies, membrane and molecular structures with potential health benefits. Lipid emulsifiers used to stabilize fats in processed foods are not mere bystanders of lipid effects and can induce both beneficial and adverse health effects. These findings open new clinical research questions aiming to further characterize the cardiometabolic fate of lipids, from digestion to bioactive metabolites, according to the food source or molecular carrier. This should be useful to elaborate food formulations for target populations and personalized dietary recommendations.

ApoER2 (Apolipoprotein E Receptor-2) Deficiency Accelerates Smooth Muscle Cell Senescence via Cytokinesis Impairment and Promotes Fibrotic Neointima After Vascular Injury.

Genome-wide studies showed that mutation in apoER2 (apolipoprotein E receptor-2) is additive with ε4 polymorphism in the APOE gene on cardiovascular disease risk in humans. ApoE or apoER2 deficiency also accelerates atherosclerosis lesion necrosis in hypercholesterolemic mice and promotes neointima formation after vascular injury. This study tests the hypothesis that apoE and apoER2 modulate vascular occlusive diseases through distinct mechanisms. Approach and Results: Carotid endothelial denudation induced robust neointima formation in both apoE-/- and apoER2-deficient Lrp8-/- mice. The intima in apoE-/- mice was rich in smooth muscle cells, but the intima in Lrp8-/- mice was cell-poor and rich in extracellular matrix. Vascular smooth muscle cells isolated from apoE-/- mice were hyperplastic whereas Lrp8-/- smooth muscle cells showed reduced proliferation but responded robustly to TGF (transforming growth factor)-β-induced fibronectin synthesis indicative of a senescence-associated secretory phenotype, which was confirmed by increased β-galactosidase activity, p16INK4a immunofluorescence, and number of multinucleated cells. Western blot analysis of cell cycle-associated proteins showed that apoER2 deficiency promotes cell cycle arrest at the metaphase/anaphase. Coimmunoprecipitation experiments revealed that apoER2 interacts with the catalytic subunit of protein phosphatase 2A. In the absence of apoER2, PP2A-C (protein phosphatase 2A catalytic subunit) failed to interact with CDC20 (cell-division cycle protein 20) thus resulting in inactive anaphase-promoting complex and impaired cell cycle exit. This study showed that apoER2 participates in APC (anaphase-promoting complex)/CDC20 complex formation during mitosis, and its absence impedes cytokinesis abscission thereby accelerating premature cell senescence and vascular disease. This mechanism is distinct from apoE deficiency, which causes smooth muscle cell hyperplasia to accelerate vascular disease.

Perinatal Bisphenol A Exposure Increases Atherosclerosis in Adult Male PXR-Humanized Mice.

Bisphenol A (BPA) is a base chemical used extensively in numerous consumer products, and human exposure to BPA is ubiquitous. Higher BPA exposure has been associated with an increased risk of atherosclerosis and cardiovascular disease (CVD) in multiple human population-based studies. However, the underlying mechanisms responsible for the associations remain elusive. We previously reported that BPA activates the xenobiotic receptor pregnane X receptor (PXR), which has proatherogenic effects in animal models. Because BPA is a potent agonist for human PXR but does not affect rodent PXR activity, a suitable PXR-humanized apolipoprotein E-deficient (huPXR•ApoE-/-) mouse model was developed to study BPA's atherogenic effects. Chronic BPA exposure increased atherosclerosis in the huPXR•ApoE-/- mice. We report that BPA exposure can also activate human PXR signaling in the heart tubes of huPXR•ApoE-/- embryos, and perinatal BPA exposure exacerbated atherosclerosis in adult male huPXR•ApoE-/- offspring. However, atherosclerosis development in female offspring was not affected by perinatal BPA exposure. Perinatal BPA exposure did not affect plasma lipid levels but increased aortic and atherosclerotic lesional fatty acid transporter CD36 expression in male huPXR•ApoE-/- offspring. Mechanistically, PXR epigenetically regulated CD36 expression by increasing H3K4me3 levels and decreasing H3K27me3 levels in the CD36 promoter in response to perinatal BPA exposure. The findings from the present study contribute to our understanding of the association between BPA exposure and increased atherosclerosis or CVD risk in humans, and activation of human PXR should be considered for future BPA risk assessment.

Pressing the trimethylamine N-oxide narrative

We read with interest the correspondence titled “Gut Microbe-Generated Trimethylamine N-Oxide from Dietary Choline is Prothrombotic in Subjects”, published by Zhu et al . in the journal Circulation (1). This work builds on an emerging body of evidence which has suggested a role for the gut-derived metabolite, trimethylamine N -oxide (TMAO), in the development of cardiovascular disease (CVD). This current study is an important clinical test of hypotheses generated from innovative preclinical and observational evidence, and seeks to build upon the nature of TMAO’s relationship with CVD risk in humans. To assess this relationship, Zhu et al . enrolled 18 subjects (10 omnivores and 8 vegetarians) and provided choline bitartrate as a supplement (450 mg choline/day) for 2 months. Following choline supplementation, fasting plasma TMAO concentrations increased and were associated with increased ADP-induced platelet aggregation, an effect that was partially blunted by aspirin.

Circadian misalignment increases cardiovascular disease risk factors in humans

Shift work is a risk factor for hypertension, inflammation, and cardiovascular disease. This increased risk cannot be fully explained by classic risk factors. One of the key features of shift workers is that their behavioral and environmental cycles are typically misaligned relative to their endogenous circadian system. However, there is little information on the impact of acute circadian misalignment on cardiovascular disease risk in humans. Here we show-by using two 8-d laboratory protocols-that short-term circadian misalignment (12-h inverted behavioral and environmental cycles for three days) adversely affects cardiovascular risk factors in healthy adults. Circadian misalignment increased 24-h systolic blood pressure (SBP) and diastolic blood pressure (DBP) by 3.0 mmHg and 1.5 mmHg, respectively. These results were primarily explained by an increase in blood pressure during sleep opportunities (SBP, +5.6 mmHg; DBP, +1.9 mmHg) and, to a lesser extent, by raised blood pressure during wake periods (SBP, +1.6 mmHg; DBP, +1.4 mmHg). Circadian misalignment decreased wake cardiac vagal modulation by 8-15%, as determined by heart rate variability analysis, and decreased 24-h urinary epinephrine excretion rate by 7%, without a significant effect on 24-h urinary norepinephrine excretion rate. Circadian misalignment increased 24-h serum interleukin-6, C-reactive protein, resistin, and tumor necrosis factor-α levels by 3-29%. We demonstrate that circadian misalignment per se increases blood pressure and inflammatory markers. Our findings may help explain why shift work increases hypertension, inflammation, and cardiovascular disease risk.

Effect of consuming novel foods consisting high oleic canola oil, barley β-glucan, and DHA on cardiovascular disease risk in humans: the CONFIDENCE (Canola Oil and Fibre with DHA Enhanced) study – protocol for a randomized controlled trial

BackgroundMetabolic syndrome (MetS) has been identified as a major contributor to the development of cardiovascular disease (CVD). Current recommendations for dietary management of people with MetS involve quantitative and qualitative modifications of food intake, such as high consumption of vegetables, fruits, and whole grain foods. The results from our previous human trials revealed the potential of the dietary components high-oleic acid canola oil (HOCO)-docosahexaenoic acid (DHA) and high molecular weight barley β-glucan individually in managing CVD risk factors. Foods with a combination of HOCO-DHA and barley β-glucan have never been tested for their effects on CVD risk. The objective is to determine the effects of consuming novel foods HOCO-DHA, and barley β-glucan on managing CVD risk factors in people with MetS.Methods/DesignWe are conducting a randomized, single-blind crossover trial with four treatment phases of 28 days each separated by a 4-week washout interval. Participants (n=35) will be provided with weight-maintaining, healthy balanced diet recommendations according to their energy requirements during the intervention periods. Participants will receive muffins and cookies as treatment foods in a random order and will consume at least one meal per day at the research center under supervision. The four treatments include muffins and cookies consisting of (1) all-purpose flour and HOCO-DHA (50 g/day); (2) barley flour (4.36 g/day of β-glucan) and a blend of sunflower oil, safflower oil, and butter as control oil (50 g/day); (3) barley flour (4.36 g/day of β-glucan) and HOCO-DHA (50 g/day; dosage of DHA would be 3 g/day); and (4) all-purpose flour and control oil (50 g/day). At the beginning and end of each phase, we will evaluate anthropometrics; systolic and diastolic blood pressure; blood lipid profile; low-density lipoprotein subfractions and particle size; 10-year Framingham CVD risk score; inflammatory status; and plasma and red blood cell fatty acid profiles, fecal microbiome, and body composition by dual-energy X-ray absorptiometry.ConclusionCholesterol synthesis will also be studied, using a stable isotope approach. The proposed study will lead to innovation of novel food products, which may result in improvement in the overall cardiovascular health of humans.Trial registrationClinical trials.gov identifier: NCT02091583. Date of registration: 12 March 2014.

Abstract 531: Intestinal Pregnane X Receptor Links Xenobiotic Exposure and Hypercholesterolemia

Objective: Recent studies have associated endocrine disrupting chemical (EDC) exposure with the increased risk of cardiovascular disease (CVD) in humans, but the underlying mechanisms responsible for these associations remain elusive. Many EDCs have been implicated in activating the nuclear receptor pregnane X receptor (PXR) which acts as a xenobiotic sensor to regulate xenobiotic metabolism in the liver and intestine. This study aims to investigate the potential role of PXR in lipid homeostasis. Approach and Results: We identified tributyl citrate (TBC), one of a large group of FDA-approved plasticizers for pharmaceutical or food applications, as a potent and selective PXR agonist. TBC efficiently activated PXR and induced PXR target gene expression in vitro and in vivo . Interestingly, TBC was an intestine-specific PXR ligand but did not affect hepatic PXR activity. Exposure to TBC increased plasma total cholesterol and atherogenic low-density lipoprotein cholesterol levels in wild-type mice, but not in PXR-deficient mice. TBC-mediated PXR activation stimulated the expression of the cholesterol transporter Ni emann-Pick C1-Like 1 (NPC1L1) in the intestine. Promoter analysis revealed a DR-4-type of PXR-response element in the human NPC1L1 promoter and TBC promoted PXR recruitment onto the NPC1L1 promoter. Consistently, TBC treatment significantly increased cholesterol uptake by human and murine intestinal cells and deficiency of PXR blocked TBC-elicited cholesterol uptake. Conclusions: Our results established an important role of intestinal PXR in linking EDC exposure and hyperlipidemia. These findings provide critical mechanistic insight for understanding the adverse effects of EDCs on lipid homeostasis and CVD risk in humans.