Prolonged Fasting Alters the Size, Function, and Glycoproteomic Profile of HDL Particles

Objectives

To investigate the effects of a single 36-hour fast on HDL glycoproteomic composition on isolated HDL particles.

Methods

We obtained plasma from a previous study where 20 healthy subjects, age 20–40, fasted for 36 hours. HDL was isolated using density-based ultracentrifugation steps, followed by size-exclusion chromatography. Glycoproteomic was analyzed using a targeted LC-MS/MS method, and lipoprotein particle size distribution analysis using nuclear magnetic resonance (NMR) spectroscopy.

Results

HDL-associated apolipoprotein A-IV (ApoA-IV) content was significantly reduced (8918.39 +/− 3823.39 normalized ion counts vs 3690.82 +/− 2147.29 normalized ion count, p adjusted < 0.0001), suggesting a reduction in intestinally-derived HDL after a 36-hour fast. HDL associated apolipoprotein C-III (ApoC-III) di-sialylated glycopeptides decreased in HDL following a 36-hour fast compared to an overnight 12-hour fast (0.1680 +/− 0.0342 normalized ion counts vs 0.1315 +/− 0.0373 normalized ion counts, p adjusted = 0.041). Additionally, particle size distribution analysis showed an increase in abundance of calibrated large HDL of size 9.6–13nm (3.42 +/− 2.218 μmol/L vs 3.885 +/− 2.134 μmol/L, p adjusted = 0.011) and a decrease in abundance of medium HDL of size 8.1–9.5nm (6.88 +/− 1.86 μmol/L vs 5.82 +/− 2.048 μmol/L, p adjusted = 0.019) after a 36-hour fast. There were no significant changes in LDL particle size (21.115 +/− nm s 21.205 +/− 0.458 nm, p adjusted = 0.655) but there was a significant increase in overall calibrated LDL particle concentration (1138.05 +/− 357.94 μmol/L vs 1262.3 +/− 313.33 μmol/L, p adjusted = 0.011) and calibrated small LDL particle concentration (454.85 +/− 187.76 μmol/L vs 598.8 +/− 190.84 μmol/L, p adjusted = 0.025).

Conclusions

Our findings indicate that prolonged fasting alters lipoprotein profiles by affecting the proportions of large and small HDL and LDL particles, as well as altering the protein composition of HDL particles, specifically by reducing the abundance of ApoA-IV, which suggests a reduction in the contribution of intestinally-derived HDL particles to the circulating HDL pool. Future studies are needed to determine the long-term effects of multiple bouts of prolonged fasting.

Funding Sources

University of California Davis, National Institute on Aging.

Plasma Lecithin-Cholesterol Acyltransferase Activity in Pregnant Women Enrolled in the iLiNS-DYAD Trial in Ghana

Objectives

The International Lipid-Based Nutrient Supplement (iLiNS) Project developed small-quantity lipid-based nutrient supplements (SQ-LNS) for mothers and their children with the goal of reducing malnutrition. The aim of this secondary outcome analysis is to investigate the effects of SQ-LNS on the activity of plasma lecithin-cholesterol acyltransferase (LCAT), a key enzyme involved in the remodeling of high-density lipoprotein (HDL) particles, which increases their cholesterol carrying capacity.

Methods

Plasma samples from a subset of 197 out of 1320 women at 36-wk gestation enrolled in the iLiNS-DYAD trial in Ghana were analyzed. In the main cohort, women were enrolled during the second trimester (≤ 20 wk gestation) and randomly assigned to receive SQ-LNS, iron and folic acid (IFA), or a multiple micronutrient supplement. Women in this subset received either SQ-LNS or IFA. Plasma LCAT activity was measured using a commercial fluorometric kit and the non-transformed data was compared by Wilcoxon test (mean ± SD). LCAT activity is expressed as a ratio (390 nm/470 nm), where greater ratio indicates higher enzyme activity. We also explored whether LCAT activity differed by enrollment season (Dry, November–April; Wet, May-October) or was associated with biomarkers of inflammation.

Results

There was no significant difference in LCAT activity between the SQ-LNS and IFA groups (1.44 ± 0.17 vs. 1.41 ± 0.14, P = 0.24). Women enrolled during the wet season had higher LCAT activity than women enrolled during the dry season (1.47 ± 0.15 vs. 1.37 ± 0.14, P < 0.001), with no differences between intervention groups stratified by season (P > 0.05). LCAT activity was negatively correlated with inflammatory biomarkers α1-acid glycoprotein (R = −0.19, P = 0.007) and C-reactive protein (R = −0.28, P < 0.001) measured at 36-wk gestation.

Conclusions

Plasma LCAT activity, as a measure of HDL maturation and cholesterol carrying capacity, is more sensitive to factors mediated by seasonal variation (e.g., infection, inflammation) than by nutrient supplementation in this cohort of women in Ghana. These findings confirm a previously established link between HDL and inflammation.

Funding Sources

This project was supported by Bill & Melinda Gates Foundation grant (OPP124589) to the University of California, Davis.

Maternal and Child Supplementation With Small-Quantity Lipid-Based Nutrient Supplements Increases Child HDL Cholesterol Efflux Capacity

Objectives

The purpose of this secondary outcome analysis is to investigate whether small-quantity lipid-based nutrient supplements (SQ-LNS) alters lipid, protein or glycan composition, or the cholesterol efflux capacity (CEC), of high-density lipoprotein (HDL) particles in children in the International Lipid-Based Nutrient Supplements (iLiNS) DYAD trial in Ghana.

Methods

Plasma samples were obtained from a subcohort of 80 children at 18 months of age from the iLiNS-DYAD-Ghana trial. Mothers were randomized to either iron and folic acid (IFA) in pregnancy and 200 mg/d calcium for 6 months postpartum or SQ-LNS (pregnancy and 6 months postpartum). Children in the SQ-LNS group received SQ-LNS from 6 to 18 months while children in the IFA group did not receive supplements. HDL was isolated from plasma by sequential ultracentrifugation followed by size-exclusion chromatography. Assay of cholesterol efflux was performed in vitro, and glycoproteomic and lipidomic composition were analyzed by mass spectrometry. The primary analysis was a comparison of the effects of intervention groups on HDL lipidome, proteome, and CEC. In the exploratory analysis, we compared the enrichment of glycopeptides in measured HDL-associated proteins between groups.

Results

Mean (±SD) HDL CEC was higher among children in the SQ-LNS vs. IFA group (20.9 ± 4.1% vs. 19.4 ± 3.3%; one-tailed p = 0.038). We found no differences in HDL lipidomic or proteomic composition between groups.

Conclusions

Prenatal and postnatal SQ-LNS may improve the CEC of child HDL particles. These improvements may have a potential impact on child health outcomes.

Funding Sources

Supported by Bill & Melinda Gates Foundation grant to the University of California, Davis.

A Novel Prebiotic Supplement Increases Bifidobacteria Abundance in Participants Consuming Low-Fiber Diets

Objectives

The objective of this study was to determine whether a novel fiber supplement consumed by healthy individuals with a habitual diet low in fiber (&lt;15 g/day) increases the proportion of saccharolytic gut microbiota which is associated with the increase in the production of SCFA and their related genes in stool without changing their usual diet.

Methods

Twenty individuals were enrolled in this double-blinded, randomized order, placebo-controlled, cross-over study. Participants were young, healthy, normal to overweight (BMI 23.0–32.0) and consumed &lt; 15 g/day of fiber. All participants consumed a fiber and placebo supplement for a period of 4 weeks each, with a 4-week washout between intervention arms in random order. Participants recorded their diet for 3 days using 24-hour diet record at each 2-week segment. The diet was patternized each week (i.e., participants were asked to consume the same meals and foods for the 3 days prior to each test day) without significantly changing the participants’ usual diet. The fiber packets contained 12 g/serving per day as a powder containing resistant starch, fructooligosaccharide, sugarcane fiber, and inulin while the placebo packets contained 12 g/serving per day of a powder that matched the fiber supplement in taste and appearance. The powder packet was mixed with water for consumption. Stool samples were collected every 2 weeks throughout the study, and metagenomic sequencing and SCFA analysis was performed.

Results

The concentration of SCFA measured in the stool sample did not change after the intervention. However, the relative abundance of one of the well known saccharolytic bacteria, Bifidobacterium, increased after the fiber supplementation. Genes related to acetate and lactate production, poxB (P = 0.04) and ldh (P = 0.07) respectively, showed tendency to increase which aligns with the increase in the relative abundance of Bifidobacterium in stool samples. No significant changes and correlations were found with anthropometrics and diet records.

Conclusions

A small amount of fiber supplemented on a daily basis to individuals consuming low fiber diets resulted in an increase in the relative abundance of the beneficial gut microbial genus, Bifidobacterium.

Funding Sources

I would like to acknowledge Usana Health Sciences, Inc. for the support in this research.

Metabolic flux analysis of the neural cell glycocalyx reveals differential utilization of monosaccharides

Saccharides in our diet are major sources of carbon for the formation of biomass such as proteins, lipids, nucleic acids and glycans. Among the dietary monosaccharides, glucose occupies a central role in metabolism, but human blood contains regulated levels of other monosaccharides as well. Their influence on metabolism and how they are utilized have not been explored thoroughly. Applying metabolic flux analysis on glycan synthesis can reveal the pathways that supply glycosylation precursors and provide a snapshot of the metabolic state of the cell. In this study, we traced the incorporation of six 13C uniformly labeled monosaccharides in the N-glycans, O-glycans and glycosphingolipids of both pluripotent and neural NTERA-2 cells. We gathered detailed isotopologue data for hundreds of glycoconjugates using mass spectrometry methods. The contributions of de novo synthesis and direct incorporation pathways for glucose, mannose, fructose, galactose, N-acetylglucosamine and fucose were determined based on their isotope incorporation. Co-feeding studies revealed that fructose incorporation is drastically decreased by the presence of glucose, while mannose and galactose were much less affected. Furthermore, increased sialylation slowed down the turnover of glycans, but fucosylation attenuated this effect. Our results demonstrated that exogenous monosaccharide utilization can vary markedly depending on the cell differentiation state and monosaccharide availability, and that the incorporation of carbons can also differ among different glycan structures. We contend that the analysis of metabolic isotope labeling of glycans can yield new insights about cell metabolism.

Novel Fiber Formulation Does Not Alter Cardiometabolic Profiles in Overweight Participants Consuming Low-Fiber Diets

Objectives

The objective of this study was to determine whether a novel fiber formulation improves glucose, insulin, and lipid profiles in overweight men and women consuming a low fiber diet.

Methods

Twenty individuals were enrolled in this randomized order, placebo-controlled, cross-over study. Participants were young, healthy, overweight (BMI 23.0–32.0) and consumed &lt;15 g/day of fiber. All participants consumed the fiber and placebo supplement for a period of 4 weeks each, with a 4-week washout between intervention arms. Participants recorded their diet for 3 days using dietary records twice during each 4-week segment. They consumed either fiber and/or placebo packet containing a total of 12 g/serving per day. The Fiber and/or Placebo was given out as powder form which include mostly dietary fiber (resistant starch, fructooligosaccharide, sugarcane fiber, and inulin), rice flour, xanthan gum, and fruit powders that was mixed with water for consumption. Questionnaires, anthropometric measurements, blood draws, and stool samples were collected at each study visit. Changes in glucose, insulin, and lipid profile (total cholesterol (TC), triacylglycerols (TG), HDL-C and calculated LDL-C) were assessed using a linear mixed model.

Results

The mean change in fasted glucose, insulin, and lipid profiles showed a tendency to decrease in response to fiber consumption compared with the placebo but did not meet statistical significance (P = 0.29, 0.42, and 0.61) due to high interindividual variability. This clinical trial was registered at clinicaltrials.gov as NCT03785860.

Conclusions

Cardiometabolic profiles did not change in response to the fiber supplement.

Funding Sources

I would like to acknowledge Usana Health Sciences, Inc. for the support in this research.

21st century toolkit for optimizing population health through precision nutrition

Scientific, technological, and economic progress over the last 100 years all but eradicated problems of widespread food shortage and nutrient deficiency in developed nations. But now society is faced with a new set of nutrition problems related to energy imbalance and metabolic disease, which require new kinds of solutions. Recent developments in the area of new analytical tools enable us to systematically study large quantities of detailed and multidimensional metabolic and health data, providing the opportunity to address current nutrition problems through an approach called Precision Nutrition. This approach integrates different kinds of "big data" to expand our understanding of the complexity and diversity of human metabolism in response to diet. With these tools, we can more fully elucidate each individual's unique phenotype, or the current state of health, as determined by the interactions among biology, environment, and behavior. The tools of precision nutrition include genomics, metabolomics, microbiomics, phenotyping, high-throughput analytical chemistry techniques, longitudinal tracking with body sensors, informatics, data science, and sophisticated educational and behavioral interventions. These tools are enabling the development of more personalized and predictive dietary guidance and interventions that have the potential to transform how the public makes food choices and greatly improve population health.