Dietary fat and carbohydrate affect the metabolism of protein-based high-density lipoprotein subspecies

New light on ω-3 polyunsaturated fatty acids and diabetes debate: a population pharmacokinetic-pharmacodynamic modelling and intake threshold study

OBJECTIVE

ω-3 polyunsaturated fatty acids (PUFA) are a key modifiable factor in the intervention of type 2 diabetes, yet recommendations for dietary consumption of ω-3 PUFA in type 2 diabetes remain ambiguous and controversial. Here, we revisit the subject in the light of population pharmacokinetic-pharmacodynamic (PPK-PD) modeling and propose a threshold for intake.

RESEARCH DESIGN AND METHODS

Plasma levels of ω-3 PUFA and glycosylated hemoglobin (HbA1c) were measured as pharmacokinetic and pharmacodynamic indicator, respectively. The nonlinear mixed effect analysis was used to construct a PPK-PD model for ω-3 PUFA and to quantify the effects of FADS gene polymorphism, age, liver and kidney function, and other covariables.

RESULTS

Data from 161 patients with type 2 diabetes in the community were modeled in a two-compartment model with primary elimination, and HDL was a statistically significant covariate. The simulation results showed that HbA1c showed a dose-dependent decrease of ω-3 PUFA plasma level. A daily intake of ω-3 PUFA at 0.4 g was sufficient to achieve an HbA1c level of 7% in more than 95% of patients.

CONCLUSIONS

PPK/PD modeling was proposed as a multilevel analytical framework to quantitatively investigate finer aspects of the complex relationship between ω-3 PUFA and type 2 diabetes on genetic and non-genetic influence factors. The results support a beneficial role for ω-3 PUFA in type 2 diabetes and suggested the intake threshold. This new approach may provide insights into the interaction of the two and an understanding of the context in which changes occur.

Understanding HDL Metabolism and Biology Through In Vivo Tracer Kinetics

HDL (high-density lipoprotein), owing to its high protein content and small size, is the densest circulating lipoprotein. In contrast to lipid-laden VLDL (very-low-density lipoprotein) and LDL (low-density lipoprotein) that promote atherosclerosis, HDL is hypothesized to mitigate atherosclerosis via reverse cholesterol transport, a process that entails the uptake and clearance of excess cholesterol from peripheral tissues. This process is mediated by APOA1 (apolipoprotein A-I), the primary structural protein of HDL, as well as by the activities of additional HDL proteins. Tracer-dependent kinetic studies are an invaluable tool to study HDL-mediated reverse cholesterol transport and overall HDL metabolism in humans when a cardiovascular disease therapy is investigated. Unfortunately, HDL cholesterol-raising therapies have not been successful at reducing cardiovascular events suggesting an incomplete picture of HDL biology. However, as HDL tracer studies have evolved from radioactive isotope- to stable isotope-based strategies that in turn are reliant on mass spectrometry technologies, the complexity of the HDL proteome and its metabolism can be more readily addressed. In this review, we outline the motivations, timelines, advantages, and disadvantages of the various tracer kinetics strategies. We also feature the metabolic properties of select HDL proteins known to regulate reverse cholesterol transport, which in turn underscore that HDL lipoproteins comprise a heterogeneous particle population whose distinct protein constituents and kinetics likely determine its function and potential contribution to cholesterol clearance.

Comparative Evaluation of a Low-Carbohydrate Diet and a Mediterranean Diet in Overweight/Obese Patients with Type 2 Diabetes Mellitus: A 16-Week Intervention Study

INTRODUCTION

The worldwide prevalence of type 2 diabetes mellitus (T2DM) and obesity has been steadily increasing over the past four decades, with projections indicating a significant rise in the number of affected individuals by 2045. Therapeutic interventions in T2DM aim to control blood glucose levels and reduce the risk of complications. Dietary and lifestyle modifications play a crucial role in the management of T2DM and obesity. While conventional medical nutritional therapy (MNT) often promotes a high-carbohydrate, low-fat Mediterranean diet as an elective treatment, low-carbohydrate diets (LCDs), specifically those restricting carbohydrate intake to less than 130 g/day, have gained popularity due to their multifaceted benefits. Scientific research supports the efficacy of LCDs in improving glycemic control, weight loss, blood pressure, lipid profiles, and overall quality of life. However, sustaining these benefits over the long term remains challenging. This trial aimed to compare the effects of a Mediterranean diet vs. a low-carbohydrate diet (carbohydrate intake < 130 g/day) on overweight/obese patients with T2DM over a 16-week period. The study will evaluate the differential effects of these diets on glycemic regulation, weight reduction, lipid profile, and cardiovascular risk factors.

METHODS

The study population comprises 100 overweight/obese patients with poorly controlled T2DM. Anthropometric measurements, bioimpedance analysis, and blood chemistry assessments will be conducted at baseline and after the 16-week intervention period. Both dietary interventions were hypocaloric, with a focus on maintaining a 500 kcal/day energy deficit.

RESULTS

After 16 weeks, both diets had positive effects on various parameters, including weight loss, blood pressure, glucose control, lipid profile, and renal function. However, the low-carbohydrate diet appears to result in a greater reduction in BMI, blood pressure, waist circumference, glucose levels, lipid profiles, cardiovascular risk, renal markers, and overall metabolic parameters compared to the Mediterranean diet at the 16-week follow up.

CONCLUSIONS

These findings suggest that a low-carbohydrate diet may be more effective than a Mediterranean diet in promoting weight loss and improving various metabolic and cardiovascular risk factors in overweight/obese patients with T2DM. However, it is important to note that further research is needed to understand the clinical implications and long-term sustainability of these findings.

Sweet swell of burning fat: emerging role of high-density lipoprotein in energy homeostasis

PURPOSE OF REVIEW

Metabolism of lipids and lipoproteins, including high-density lipoprotein (HDL), plays a central role in energy homeostasis. Mechanisms underlying the relationship between energy homeostasis and HDL however remain poorly studied.

RECENT FINDINGS

Available evidence reveals that HDL is implicated in energy homeostasis. Circulating high-density lipoprotein-cholesterol (HDL-C) levels are affected by energy production, raising with increasing resting metabolic rate. Lipolysis of triglycerides as a source of energy decreases plasma levels of remnant cholesterol, increases levels of HDL-C, and can be cardioprotective. Switch to preferential energy production from carbohydrates exerts opposite effects.

SUMMARY

Low HDL-C may represent a biomarker of inefficient energy production from fats. HDL-C-raising can be beneficial when it reflects enhanced energy production from burning fat.

Benzo[a]pyrene and a high-fat diet induce aortic injury and promote

Benzo[a]pyrene (BaP) is a ubiquitous environmental pollutant which mainly exposed though diet. High-fat diet (HFD) can induce atherosclerosis, as can BaP. Unhealthy dietary habits lead to high intake of both BaP and lipids. However, the combined effect of BaP and HFD on atherosclerosis and lipid accumulation in the arterial wall, the initial stage of atherosclerosis, is unclear. In this study, C57BL/6 J mice were subchronically exposed to BaP and a HFD, and the mechanism of lipid accumulation was investigated in EA.hy926 and HEK293 cells. Results showed that BaP and HFD increased blood lipids and damaged aortic wall synergistically. Meanwhile, LDL enhanced the toxicity of BaP, and BaP promoted the production of reactive oxygen species and malonaldehyde in EA.hy926 cells, which aggravated LDL-induced cell injury. Moreover, BaP and HFD/LDL induced LDL accumulation in the aortic wall of C57BL/6 J mice/EA.hy926, and the mechanism was by activating AHR/ARNT heterodimer to combine with the scavenger receptor BⅠ (SR-BⅠ) and activin receptor-like kinase 1 (ALK1) promoter regions to transcriptional upregulate its expression, which enhanced the uptake of LDL, and promoting the production of AGEs to inhibit reverse cholesterol transport by SR-BI. BaP and lipid synergistically promoted aortic and endothelial damage, and the health risk of their combined intake should be paid attention to.

Bulk RNA-seq and scRNA-seq analysis reveal an activation of immune response and compromise of secretory function in major salivary glands of obese mice

Obesity affects the function of multiple organs/tissues including the exocrine organ salivary glands. However, the effects of obesity on transcriptomes and cell compositions in the salivary glands have yet been studied by bulk RNA-sequencing and single-cell RNA-sequencing. Besides, the cell types in the sublingual gland, one of the three major salivary glands, have yet been characterized by the approach of single-cell RNA-sequencing. In this report, we find that the histological structure of the three major salivary glands are not obviously affected in the obese mice. Bulk RNA-sequencing analysis shows that the most prominent changes observed in the three major salivary glands of the obese mice are the mobilization of transcriptomes related to the immune response and down-regulation of genes related to the secretory function of the salivary glands. Based on single-cell RNA-sequencing analysis, we identify and annotate 17 cell clusters in the sublingual gland for the first time, and find that obesity alters the relative compositions of immune cells and secretory cells in the major glands of obese mice. Integrative analysis of the bulk RNA-sequencing and single-cell RNA-sequencing data confirms the activation of immune response genes and compromise of secretory function in the three major salivary glands of obese mice. Consequently, the secretion of extracellular matrix proteins is significantly reduced in the three major salivary glands of obese mice. These results provide new molecular insights into understanding the effect of obesity on salivary glands.