Effects of Amino Acids Supplementation on Lipid and Glucose Metabolism in HepG2 Cells

Bambara Bean Substitution Improves the Nutritional Content and Increases the Satiety Index of Purple Sweet Potato Bread

This study aimed to develop tuber bread from purple sweet potato and bambara beans with high satiety and low glycemic index (GI). Different ratios of purple sweet potato to bambara bean were used: 100:0 (F0), 80:20 (F1), 60:40 (F2), and 40:60 (F3). The satiety index (SI) was determined by assessing the consumption of a 240 kcal isocaloric food and collecting data through a visual analog scale. Blood samples were collected from 11 subjects to determine the GI of the test food. This was achieved using the finger-prick capillary blood sampling method or an EasyTouch glucometer. The results showed that tuber-bread F1 was categorized as high-fiber sources (6.92±0.03 g), whereas F2 and F3 were classified as fiber sources (5.50±0.07 and 5.14±0.11 g, respectively). Significant differences were observed among all formulas. Additionally, formula F3 showed a high SI (160.12%±18.38%) and GI (81.94±2.13), suggesting that the consumption of fiber-rich food may promote feelings of fullness and reduce food cravings. The satiety score analysis of the selected products against standard food yielded a regression equation (y=-0.257x+66.648), showing that tuber-bread F3 extended satiety by up to 95 min compared with white bread. As a result, tuber-bread F3 may help to reduce the consumption of additional food, which is frequently a significant contributor to excessive calorie intake.

Regulating role of Pleurotus ostreatus insoluble dietary fiber in high fat diet induced obesity in rats based on proteomics and metabolomics analyses

This study aims to reveal the effects of Pleurotus ostreatus insoluble dietary fiber (POIDF) on liver protein and cecal metabolites in obese rats and its potential mechanism by intestinal microbes. It was found that POIDF contained the structural characteristics of cellulose and hemicellulose, as well as amorphous diffraction peaks. POIDF could reduce the body weight and organ index of obese rats, regulate dyslipidemia, and improve the pathological changes of liver and epididymis fat. Further experimental results showed that POIDF could regulate the abundance of bacteria related to lipid metabolism, and maintain intestinal homeostasis. The metabolomics results showed that the fatty acyls pathway in the cecum contents was the pathway with the highest concentration of small molecule metabolites. POIDF supplementation regulated the expression of liver key proteins, as well as biosynthesis of amino acids, steroid biosynthesis, arachidonic acid metabolism and PPAR signaling pathway. Omics association analysis found that POIDF could further regulate liver proteins and their signaling pathways, regulate the levels of fatty acyls and amino acid metabolites in the gut and the enrichment of related pathways, and play a therapeutic or preventive role in obesity after degradation by intestinal microbiota.

Associations of Amino Acids with the Risk of Prediabetes: A Case-Control Study from Kazakhstan

BACKGROUND

The high global prevalence of prediabetes requires its early identification. Amino acids (AAs) have emerged as potential predictors of prediabetes. This study investigates the association between amino acids and prediabetes in the Kazakh population.

MATERIALS AND METHODS

In this case-control study, serum AAs levels were measured using the Trace GC 1310 gas chromatography system coupled with the TSQ 8000 triple quadrupole mass spectrometer (Thermo Scientific, Austin, TX, USA) followed by silylation with the BSTFA + 1% TMCS derivatization method. Biochemical parameters, including total cholesterol, HDL-C, LDL-C, triglycerides, fasting glucose, HbA1c, and Creatinine, were assessed for each participant. Trained professionals conducted anthropometric and physical examinations (which included taking blood pressure and heart rate measurements) and family history collection.

RESULTS

A total of 112 Kazakh individuals with prediabetes and 55 without prediabetes, aged 36-65 years, were included in the study. Only Alanine and valine showed a significant association with prediabetes risk among the 13 AAs analyzed. Our findings revealed an inverse relationship between Alanine and Valine and prediabetes in individuals of Kazakh ethnicity.

CONCLUSION

A lower serum level of Alanine and Valine may serve as a predictive biomarker for prediabetes in the Kazakh population.

Exploring the role of genetic variations in NAFLD: implications for disease pathogenesis and precision medicine approaches

Non-alcoholic fatty liver disease (NAFLD) is one of the leading causes of chronic liver diseases, affecting more than one-quarter of people worldwide. Hepatic steatosis can progress to more severe forms of NAFLD, including NASH and cirrhosis. It also may develop secondary diseases such as diabetes and cardiovascular disease. Genetic and environmental factors regulate NAFLD incidence and progression, making it a complex disease. The contribution of various environmental risk factors, such as type 2 diabetes, obesity, hyperlipidemia, diet, and sedentary lifestyle, to the exacerbation of liver injury is highly understood. Nevertheless, the underlying mechanisms of genetic variations in the NAFLD occurrence or its deterioration still need to be clarified. Hence, understanding the genetic susceptibility to NAFLD is essential for controlling the course of the disease. The current review discusses genetics' role in the pathological pathways of NAFLD, including lipid and glucose metabolism, insulin resistance, cellular stresses, and immune responses. Additionally, it explains the role of the genetic components in the induction and progression of NAFLD in lean individuals. Finally, it highlights the utility of genetic knowledge in precision medicine for the early diagnosis and treatment of NAFLD patients.

NAD metabolic therapy in metabolic dysfunction-associated steatotic liver disease: Possible roles of gut microbiota

Metabolic dysfunction-associated steatotic liver disease (MASLD), formerly named non-alcoholic fatty liver disease (NAFLD), is induced by alterations of hepatic metabolism. As a critical metabolites function regulator, nicotinamide adenine dinucleotide (NAD) nowadays has been validated to be effective in the treatment of diet-induced murine model of MASLD. Additionally, gut microbiota has been reported to have the potential to prevent MASLD by dietary NAD precursors metabolizing together with mammals. However, the underlying mechanism remains unclear. In this review, we hypothesized that NAD enhancing mitochondrial activity might reshape a specific microbiota signature, and improve MASLD progression demonstrated by fecal microbiota transplantation. Here, this review especially focused on the mechanism of Microbiota-Gut-Liver Axis together with NAD metabolism for the MASLD progress. Notably, we found significant changes in Prevotella associated with NAD in a gut microbiome signature of certain MASLD patients. With the recent researches, we also inferred that Prevotella can not only regulate the level of NAD pool by boosting the carbon metabolism, but also play a vital part in regulating the branched-chain amino acid (BCAA)-related fatty acid metabolism pathway. Altogether, our results support the notion that the gut microbiota contribute to the dietary NAD precursors metabolism in MASLD development and the dietary NAD precursors together with certain gut microbiota may be a preventive or therapeutic strategy in MASLD management.

Metabolite profiles and DNA methylation in metabolic syndrome: a two-sample, bidirectional Mendelian randomization

Introduction: Metabolic syndrome (MetS) increases the risk of cardiovascular disease and death. Previous '-omics' studies have identified dysregulated serum metabolites and aberrant DNA methylation in the setting of MetS. However, the relationship between the metabolome and epigenome have not been elucidated. In this study, we identified serum metabolites associated with MetS and DNA methylation, and we conducted bidirectional Mendelian randomization (MR) to assess causal relationships between metabolites and methylation. Methods: We leveraged metabolomic and genomic data from a national United States cohort of older adults (REGARDS), as well as metabolomic, epigenomic, and genomic data from a family-based study of hypertension (HyperGEN). We conducted metabolite profiling for MetS in REGARDS using weighted logistic regression models and validated them in HyperGEN. Validated metabolites were selected for methylation studies which fit linear mixed models between metabolites and six CpG sites previously linked to MetS. Statistically significant metabolite-CpG pairs were selected for two-sample, bidirectional MR. Results: Forward MR indicated that glucose and serine metabolites were causal on CpG methylation near CPT1A [B(SE): -0.003 (0.002), p = 0.028 and B(SE): 0.029 (0.011), p = 0.030, respectively] and that serine metabolites were causal on ABCG1 [B(SE): -0.008(0.003), p = 0.006] and SREBF1 [B(SE): -0.009(0.004), p = 0.018] methylation, which suggested a protective effect of serine. Reverse MR showed a bidirectional relationship between cg06500161 (ABCG1) and serine [B(SE): -1.534 (0.668), p = 0.023]. Discussion: The metabolome may contribute to the relationship between MetS and epigenetic modifications.

High glucose dialysate-induced peritoneal fibrosis: Pathophysiology, underlying mechanisms and potential therapeutic strategies

Peritoneal dialysis is an efficient renal replacement therapy for patients with end-stage kidney disease. However, continuous exposure of the peritoneal membrane to dialysate frequently leads to peritoneal fibrosis, which alters the function of the peritoneal membrane and results in withdrawal from peritoneal dialysis in patients. Among others, high glucose dialysate is considered as a predisposing factor for peritoneal fibrosis in patients on peritoneal dialysis. Glucose-induced inflammation, metabolism disturbance, activation of the renin-angiotensin-aldosterone system, angiogenesis and noninflammation-induced reactive oxygen species are implicated in the pathogenesis of high glucose dialysate-induced peritoneal fibrosis. Specifically, high glucose causes chronic inflammation and recurrent peritonitis, which could cause migration and polarization of inflammatory cells, as well as release of cytokines and fibrosis. High glucose also interferes with lipid metabolism and glycolysis by activating the sterol-regulatory element-binding protein-2/cleavage-activating protein pathway and increasing hypoxia inducible factor-1α expression, leading to angiogenesis and peritoneal fibrosis. Activation of the renin-angiotensin-aldosterone system and Ras-mitogen activated protein kinase signaling pathway is another contributing factor in high glucose dialysate-induced fibrosis. Ultimately, activation of the transforming growth factor-β1/Smad pathway is involved in mesothelial-mesenchymal transition or epithelial-mesenchymal transition, which leads to the development of fibrosis. Although possible intervention strategies for peritoneal dialysate-induced fibrosis by targeting the transforming growth factor-β1/Smad pathway have occasionally been proposed, lack of laboratory evidence renders clinical decision-making difficult. We therefore aim to revisit the upstream pathways of transforming growth factor-beta1/Smad and propose potential therapeutic targets for high glucose-induced peritoneal fibrosis.

Experimental model and novel therapeutic targets for non-alcoholic fatty liver disease development

Non-alcoholic fatty liver disease (NAFLD) is a complex disorder characterized by the accumulation of fat in the liver in the absence of excessive alcohol consumption. It is one of the most common liver diseases worldwide, affecting approximately 25% of the global population. It is closely associated with obesity, type 2 diabetes, and metabolic syndrome. Moreover, NAFLD can progress to non-alcoholic steatohepatitis, which can cause liver cirrhosis, liver failure, and hepatocellular carcinoma. Currently, there are no approved drugs for the treatment of NAFLD. Therefore, the development of effective drugs is essential for NAFLD treatment. In this article, we discuss the experimental models and novel therapeutic targets for NAFLD. Additionally, we propose new strategies for the development of drugs for NAFLD.

Behind Protein Synthesis: Amino Acids-Metabokine Regulators of Both Systemic and Cellular Metabolism

Recent scientific research suggests that amino acids (AA) are not only the "building bricks" of protein synthesis but may also be considered "metabokines" [...].

Serum neuregulin 4 is negatively correlated with insulin sensitivity in humans and impairs mitochondrial respiration in HepG2 cells

Neuregulin 4 (NRG4) has been described to improve metabolic disturbances linked to obesity status in rodent models. The findings in humans are controversial. We aimed to investigate circulating NRG4 in association with insulin action in humans and the possible mechanisms involved. Insulin sensitivity (euglycemic hyperinsulinemic clamp) and serum NRG4 concentration (ELISA) were analysed in subjects with a wide range of adiposity (n = 89). In vitro experiments with human HepG2 cell line were also performed. Serum NRG4 was negatively correlated with insulin sensitivity (r = −0.25, p = 0.02) and positively with the inflammatory marker high-sensitivity C reative protein (hsCRP). In fact, multivariant linear regression analyses showed that insulin sensitivity contributed to BMI-, age-, sex-, and hsCRP-adjusted 7.2% of the variance in serum NRG4 (p = 0.01). No significant associations were found with adiposity measures (BMI, waist circumference or fat mass), plasma lipids (HDL-, LDL-cholesterol, or fasting triglycerides) or markers of liver injury. Cultured hepatocyte HepG2 treated with human recombinant NRG4 had an impact on hepatocyte metabolism, leading to decreased gluconeogenic- and mitochondrial biogenesis-related gene expression, and reduced mitochondrial respiration, without effects on expression of lipid metabolism-related genes. Similar but more pronounced effects were found after neuregulin 1 administration. In conclusion, sustained higher serum levels of neuregulin-4, observed in insulin resistant patients may have deleterious effects on metabolic and mitochondrial function in hepatocytes. However, findings from in vitro experiments should be confirmed in human primary hepatocytes.