Gut microbiome and its cofactors are linked to lipoprotein distribution profiles

Increasing evidence indicates that the gut microbiome (GM) plays an important role in the etiology of dyslipidemia. To date, however, no in depth characterization of the associations between GM and its metabolic attributes with deep profiling of lipoproteins distributions (LPD) among healthy individuals has been conducted. To determine associations and contributions of GM composition and its cofactors with distribution profiles of lipoprotein subfractions, we studied blood plasma LPD, fecal short-chain fatty acids (SCFA) and GM of 262 healthy Danish subjects aged 19-89 years. Stratification of LPD segregated subjects into three clusters of profiles that reflected differences in the lipoprotein subclasses, corresponded well with limits of recommended levels of main lipoprotein fractions and were largely explained by host characteristics such as age and body mass index. Higher levels of HDL, particularly driven by large subfractions (HDL2a and HDL2b), were associated with a higher relative abundance of Ruminococcaceae and Christensenellaceae. Increasing levels of total cholesterol and LDL, which were primarily associated with large 1 and 2 subclasses, were positively associated with Lachnospiraceae and Coriobacteriaceae, and negatively with Bacteroidaceae and Bifidobacteriaceae. Metagenome sequencing showed a higher abundance of genes involved in the biosynthesis of multiple B-vitamins and SCFA metabolism among subjects with healthier LPD profiles. Metagenomic assembled genomes (MAGs) affiliated mainly to Eggerthellaceae and Clostridiales were identified as the contributors of these genes and whose relative abundance correlated positively with larger subfractions of HDL. The results of this study demonstrate that remarkable differences in composition and metabolic traits of the GM are associated with variations in LPD among healthy subjects. Findings from this study provide evidence for GM considerations in future research aiming to shade light on mechanisms of the GM - dyslipidemia axis.

Impaired skeletal muscle hypertrophy signaling and amino acid deprivation response in Apoe knockout mice with an unhealthy lipoprotein distribution

This study explores if unhealthy lipoprotein distribution (LPD) impairs the anabolic and amino acid sensing responses to whey-protein feeding. Thus, if impairment of such anabolic response to protein consumption is seen by the LPD this may negatively affect the skeletal muscle mass. Muscle protein synthesis (MPS) was measured by puromycin labeling in Apolipoprotein E knockout (Apoe KO), characterized by an unhealthy LPD, and wild type mice post-absorptive at 10 and 20 weeks, and post-prandial after whey-protein feeding at 20 weeks. Hypertrophy signaling and amino acid sensing mechanisms were studied and gut microbiome diversity explored. Surprisingly, whey-protein feeding did not affect MPS. p-mTOR and p-4E-BP1 was increased 2 h after whey-protein feeding in both genotypes, but with general lower levels in Apoe KO compared to wild type. At 20 weeks of age, Apoe KO had a greater mRNA-expression for SNAT2, CD98, ATF4 and GCN2 compared to wild type. These responses were not associated with gut microbiota compositional differences. Regardless of LPD status, MPS was similar in Apoe KO and wild type. Surprisingly, whey-protein did not stimulate MPS. However, Apoe KO had lower levels of hypertrophy signaling, was amino acid deprived, and had impaired amino acid sensing mechanisms.

Plasma distribution of non-cholesterol sterols precursors of cholesterol synthesis and phytosterols depend on HDL concentration

Background Because several sterols are carried by serum lipoproteins that are pivotal in cholesterol metabolism and atherosclerosis this study aimed at investigating their lipoprotein distribution in individuals differing according to HDL-C plasma levels. Methods Healthy participants were selected with plasma HDL-C concentrations < 40 mg/dL (Low HDL, n = 12), above 40 mg/dL and below 60 mg/dL (Controls, n = 10), or above 60 mg/dL (High HDL, n = 15). Plasma lipoproteins were separated by sequential ultracentrifugation. [27-OHC]), noncholesterol sterols precursors of cholesterol synthesis (NCSPCS: desmosterol and lathosterol) and phytosterols (campesterol and sitosterol) were measured by GC-MS analysis. Diferences between groups were compared by Kruskall-walys and Dunn's post-test with correction by Bonferroni. Results The groups were similar in about BMI, age, gender distribution and blood glucose, total cholesterol and LDL-C. The High HDL group had lower concentrations of triglycerides and VLDL-C compared to others. Percentage distribution of plasma 24-OHC and 27-OHC in lipoproteins did not differ among investigated groups, but plasma concentration of 24-OHC was lower in High HDL than in Low HDL (27- OHC significance difference was borderline). NCSPCS and phytosterols predominate in LDL, which carries approximately 50% of these molecules. Approximately 30% of desmosterol and lathosterol are present in HDL, the High HDL group carrying higher percent of both sterols than the Low HDL and Control groups. Less than 20% of NCSPCS are transported in VLDL. Concentration of plasma campesterol and sitosterol did not differ among groups. However, LDL sitosterol percent distribution is lower in High HDL than in Low HDL and Controls. Campesterol and sitosterol percent distributions are higher in High HDL than in the Low HDL group. Conclusions Elevated NCSPCS in the High HDL group suggests HDL facilitates the export of these sterols from cells but not the export of the cholesterol metabolite 24-OHC which is lower in the High HDL than in the Low HDL group. Percent campesterol and sitosterol elevated in HDL suggests phytosterols absorbed in the enterocytes are incorporated mostly into the nascent HDL.

Breast Milk Content of Vitamin A and E from Early- to Mid-Lactation Is Affected by Inadequate Dietary Intake in Brazilian Adult Women

Our aims were to investigate vitamin A and E status during lactation and the determinants of breast milk content for the appropriate nutrition of the infant in a study with nursing Brazilian women. We hypothesized that both inadequate intake and the lipoprotein distribution of vitamin A and E during lactation could have an impact on their breast milk levels from early- to mid-lactation. Nineteen adult lactating women participated in this longitudinal observational study, in which dietary records, blood and mature breast milk samples were collected for the analysis of vitamin A and E, and carotenoids in early- (2nd to 4th week) and mid-lactation (12th to 14th week). Nutrient intake was balanced by the Multiple Source Method (MSM), and the intake of vitamin A and E was inadequate in 74 and 100% of the women, respectively. However, these results were not reflected in low serum concentrations of retinol and only 37% of the volunteers were vitamin E deficient according to the blood biomarker. As lactation progressed, vitamin A and E status worsened, and this was clearly observed by the decrease in their content in breast milk. The reduced content of vitamin A and E in the breast milk was not related to their distribution in lipoproteins. Taken together, the contents of vitamin A and E in breast milk seemed to be more sensitive markers of maternal nutrition status than respective blood concentrations, and dietary assessment by the MSM in early lactation was sensitive to indicate later risks of deficiency and should support maternal dietary guidance to improve the infant’s nutrition.

Short-Term Cooling Increases Plasma ANGPTL3 and ANGPTL8 in Young Healthy Lean Men but Not in Middle-Aged Men with Overweight and Prediabetes

Angiopoietin-like proteins (ANGPTLs) regulate triglyceride (TG)-rich lipoprotein distribution via inhibiting TG hydrolysis by lipoprotein lipase in metabolic tissues. Brown adipose tissue combusts TG-derived fatty acids to enhance thermogenesis during cold exposure. It has been shown that cold exposure regulates ANGPTL4, but its effects on ANGPTL3 and ANGPTL8 in humans have not been elucidated. We therefore investigated the effect of short-term cooling on plasma ANGPTL3 and ANGPTL8, besides ANGPTL4. Twenty-four young, healthy, lean men and 20 middle-aged men with overweight and prediabetes were subjected to 2 h of mild cooling just above their individual shivering threshold. Before and after short-term cooling, plasma ANGPTL3, ANGPTL4, and ANGPTL8 were determined by ELISA. In young, healthy, lean men, short-term cooling increased plasma ANGPTL3 (+16%, p < 0.05), ANGPTL4 (+15%, p < 0.05), and ANGPTL8 levels (+28%, p < 0.001). In middle-aged men with overweight and prediabetes, short-term cooling only significantly increased plasma ANGPTL4 levels (+15%, p < 0.05), but not ANGPTL3 (230 ± 9 vs. 251 ± 13 ng/mL, p = 0.051) or ANGPTL8 (2.2 ± 0.5 vs. 2.3 ± 0.5 μg/mL, p = 0.46). We show that short-term cooling increases plasma ANGPTL4 levels in men, regardless of age and metabolic status, but only overtly increases ANGPTL3 and ANGPTL8 levels in young, healthy, lean men.