Branched-chain and aromatic amino acids are predictors of insulin resistance in young adults

Branched-chain amino acid supplementation drives dynamic changes in gut microbiota without impairing glucose and lipid homeostasis at the different stages of insulin resistance in mice on a high-fat diet

OBJECTIVE

The potential role of dietary branched-chain amino acids on circulating branched-chain amino acid levels and their relationship with metabolic health are complex, and the literature is inconsistent. We aimed to explore the dynamic effects of branched-chain amino acid supplementation on glucose and lipid homeostasis at different stages of insulin resistance in high-fat diet-fed mice.

METHODS

Male C57BL/6J mice were fed with a normal chow diet, high-fat diet, or high-fat diet supplemented with 100% branched-chain amino acids for 12 or 24 wk. Metabolic parameters and gut microbiota profiling were performed at these two time points.

RESULTS

High-fat diet feeding caused varying degrees of branched-chain amino acid metabolic disorders in two different stages of insulin resistance. Supplementing with branched-chain amino acids further exacerbated branched-chain amino acid accumulation in the early stage of insulin resistance (12 wk), while adding branched-chain amino acids did not further elevate branched-chain amino acid levels in the hyperglycemia and hyperinsulinemia stage (24 wk). Compared with the high-fat diet group, branched-chain amino acid supplementation did not affect body weight; liver total cholesterol and triacylglycerol levels; and serum glucose, insulin, total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol levels as well as glucose tolerance at these two time points but triggered dynamic changes in the gut bacterial diversity and gut microbiota composition and abundance, especially in the genus associated with obesity and related metabolic disorders.

CONCLUSION

Dietary branched-chain amino acid supplementation drives dynamic changes in circulating branched-chain amino acid levels and gut microbiome without subsequent effects on glucose and lipid homeostasis in high-fat diet-induced obese mice within the parameters of our study.

Association of Nonalcoholic Fatty Liver Disease with Arterial Stiffness and its Metabolomic Profiling in Japanese Community-Dwellers

AIMS

Nonalcoholic fatty liver disease (NAFLD) is known to be associated with atherosclerosis. This study focused on upstream changes in the process by which NAFLD leads to atherosclerosis. The study aimed to confirm the association between NAFLD and the cardio-ankle vascular index (CAVI), an indicator of subclinical atherosclerosis, and explore metabolites involved in both by assessing 94 plasma polar metabolites.

METHODS

A total of 928 Japanese community-dwellers (306 men and 622 women) were included in this study. The association between NAFLD and CAVI was examined using a multivariable regression model adjusted for confounders. Metabolites commonly associated with NAFLD and CAVI were investigated using linear mixed-effects models in which batch numbers of metabolite measurements were used as a random-effects variable, and false discovery rate-adjusted p-values were calculated. To determine the extent to which these metabolites mediated the association between NAFLD and CAVI, mediation analysis was conducted.

RESULTS

NAFLD was positively associated with CAVI (coefficients [95% Confidence intervals (CI)]=0.23 [0.09-0.37]; p=0.001). A total of 10 metabolites were involved in NAFLD and CAVI, namely, branched-chain amino acids (BCAAs; valine, leucine, and isoleucine), aromatic amino acids (AAAs; tyrosine and tryptophan), alanine, proline, glutamic acid, glycerophosphorylcholine, and 4-methyl-2-oxopentanoate. Mediation analysis showed that BCAAs mediated more than 20% of the total effect in the association between NAFLD and CAVI.

CONCLUSIONS

NAFLD was associated with a marker of atherosclerosis, and several metabolites related to insulin resistance, including BCAAs and AAAs, could be involved in the process by which NAFLD leads to atherosclerosis.

Plant foods, healthy plant-based diets, and type 2 diabetes: a review of the evidence

Type 2 diabetes (T2D) is a metabolic chronic disease in which insulin resistance and insufficient insulin production lead to elevated blood glucose levels. The prevalence of T2D is growing worldwide, mainly due to obesity and the adoption of Western diets. Replacing animal foods with healthy plant foods is associated with a lower risk of T2D in prospective studies. In randomized controlled trials, the consumption of healthy plant foods in place of animal foods led to cardiometabolic improvements in patients with T2D or who were at high risk of the disease. Dietary patterns that limit or exclude animal foods and focus on healthy plant foods (eg, fruits, vegetables, whole grains, nuts, legumes), known as healthy, plant-based diets, are consistently associated with a lower risk of T2D in cohort studies. The aim of this review is to examine the differential effects of plant foods and animal foods on T2D risk and to describe the existing literature about the role of healthy, plant-based diets, particularly healthy vegan diets, in T2D prevention and management. The evidence from cohort studies and randomized controlled trials will be reported, in addition to the potential biological mechanisms that seem to be involved.

Global status and trends of metabolomics in diabetes: A literature visualization knowledge graph study

BACKGROUND

Diabetes is a metabolic disease characterized by hyperglycemia, which has increased the global medical burden and is also the main cause of death in most countries.

AIM

To understand the knowledge structure of global development status, research focus, and future trend of the relationship between diabetes and metabolomics in the past 20 years.

METHODS

The articles about the relationship between diabetes and metabolomics in the Web of Science Core Collection were retrieved from 2002 to October 23, 2023, and the relevant information was analyzed using CiteSpace6.2.2R (CiteSpace), VOSviewer6.1.18 (VOSviewer), and Bibliometrix software under R language.

RESULTS

A total of 3123 publications were included from 2002 to 2022. In the past two decades, the number of publications and citations in this field has continued to increase. The United States, China, Germany, the United Kingdom, and other relevant funds, institutions, and authors have significantly contributed to this field. Scientific Reports and PLoS One are the journals with the most publications and the most citations. Through keyword co-occurrence and cluster analysis, the closely related keywords are "insulin resistance", "risk", "obesity", "oxidative stress", "metabolomics", "metabolites" and "biomarkers". Keyword clustering included cardiovascular disease, gut microbiota, metabonomics, diabetic nephropathy, molecular docking, gestational diabetes mellitus, oxidative stress, and insulin resistance. Burst detection analysis of keyword depicted that "Gene", "microbiota", "validation", "kidney disease", "antioxidant activity", "untargeted metabolomics", "management", and "accumulation" are knowledge frontiers in recent years.

CONCLUSION

The relationship between metabolomics and diabetes is receiving extensive attention. Diabetic nephropathy, diabetic cardiovascular disease, and kidney disease are key diseases for future research in this field. Gut microbiota, molecular docking, and untargeted metabolomics are key research directions in the future. Antioxidant activity, gene, validation, mass spectrometry, management, and accumulation are at the forefront of knowledge frontiers in this field.

Metabolomic and genetic architecture of gestational diabetes subtypes

AIMS/HYPOTHESIS

Physiological gestational diabetes mellitus (GDM) subtypes that may confer different risks for adverse pregnancy outcomes have been defined. The aim of this study was to characterise the metabolome and genetic architecture of GDM subtypes to address the hypothesis that they differ between GDM subtypes.

METHODS

This was a cross-sectional study of participants in the Hyperglycemia and Adverse Pregnancy Outcome (HAPO) study who underwent an OGTT at approximately 28 weeks' gestation. GDM was defined retrospectively using International Association of Diabetes and Pregnancy Study Groups/WHO criteria, and classified as insulin-deficient GDM (insulin secretion <25th percentile with preserved insulin sensitivity) or insulin-resistant GDM (insulin sensitivity <25th percentile with preserved insulin secretion). Metabolomic analyses were performed on fasting and 1 h serum samples in 3463 individuals (576 with GDM). Genome-wide genotype data were obtained for 8067 individuals (1323 with GDM).

RESULTS

Regression analyses demonstrated striking differences between the metabolomes for insulin-deficient or insulin-resistant GDM compared to those with normal glucose tolerance. After adjustment for covariates, 33 fasting metabolites, including 22 medium- and long-chain acylcarnitines, were uniquely associated with insulin-deficient GDM; 23 metabolites, including the branched-chain amino acids and their metabolites, were uniquely associated with insulin-resistant GDM; two metabolites (glycerol and 2-hydroxybutyrate) were associated with the same direction of association with both subtypes. Subtype differences were also observed 1 h after a glucose load. In genome-wide association studies, variants within MTNR1B (rs10830963, p=3.43×10-18, OR 1.55) and GCKR (rs1260326, p=5.17×10-13, OR 1.43) were associated with GDM. Variants in GCKR (rs1260326, p=1.36×10-13, OR 1.60) and MTNR1B (rs10830963, p=1.22×10-9, OR 1.49) demonstrated genome-wide significant association with insulin-resistant GDM; there were no significant associations with insulin-deficient GDM. The lead SNP in GCKR, rs1260326, was associated with the levels of eight of the 25 fasting metabolites that were associated with insulin-resistant GDM and ten of 41 1 h metabolites that were associated with insulin-resistant GDM.

CONCLUSIONS/INTERPRETATION

This study demonstrates that physiological GDM subtypes differ in their metabolome and genetic architecture. These findings require replication in additional cohorts, but suggest that these differences may contribute to subtype-related adverse pregnancy outcomes.

Construction and evaluation of a metabolic correlation diagnostic model for diabetes based on machine learning algorithms

BACKGROUND

Diabetes mellitus (DM) is a prevalent chronic disease marked by significant metabolic dysfunctions. Understanding its molecular mechanisms is vital for early diagnosis and treatment strategies.

METHODS

We used datasets GSE7014, GSE25724, and GSE156248 from the GEO database to build a diagnostic model for DM using Random Forest (RF) and LASSO regression models. GSE20966 served as a validation cohort. DM patients were classified into two subtypes for functional enrichment analysis. Expression levels of key diagnostic genes were validated using quantitative real-time PCR (qRT-PCR) on Peripheral Blood Mononuclear Cells (PBMCs) from DM patients and healthy controls, focusing on CXCL12 and PPP1R12B with GAPDH as the internal control.

RESULTS

After de-batching the datasets, we identified 131 differentially expressed genes (DEGs) between DM and control groups, with 70 up-regulated and 61 down-regulated. Enrichment analysis revealed significant down-regulation in the IL-12 signaling pathway, JAK signaling post-IL-12 stimulation, and the ferroptosis pathway in DM. Five genes (CXCL12, MXRA5, UCHL1, PPP1R12B, and C7) were identified as having diagnostic value. The diagnostic model showed high accuracy in both the training and validation cohorts. The gene set also enabled the subclassification of DM patients into groups with distinct functional traits. qRT-PCR results confirmed the bioinformatics findings, particularly the up-regulation of CXCL12 and PPP1R12B in DM patients.

CONCLUSION

Our study pinpointed seven energy metabolism-related genes differentially expressed in DM and controls, with five holding diagnostic value. Our model accurately diagnosed DM and facilitated patient subclassification, offering new insights into DM pathogenesis.

Enhanced interactions among gut mycobiomes with the deterioration of glycemic control

BACKGROUND

The gut mycobiome is closely linked to health and disease; however, its role in the progression of type 2 diabetes mellitus (T2DM) remains obscure. Here, a multi-omics approach was employed to explore the role of intestinal fungi in the deterioration of glycemic control.

METHODS

350 participants without hypoglycemic therapies were invited for a standard oral glucose tolerance test to determine their status of glycemic control. The gut mycobiome was identified through internal transcribed spacer sequencing, host genetics were determined by genotyping array, and plasma metabolites were measured with untargeted liquid chromatography mass spectrometry.

FINDINGS

The richness of fungi was higher, whereas its dissimilarity was markedly lower, in participants with T2DM. Moreover, the diversity and composition of fungi were closely associated with insulin sensitivity and pancreatic β-cell functions. With the exacerbation of glycemic control, the co-occurrence network among fungus taxa became increasingly complex, and the complexity of the interaction network was inversely associated with insulin sensitivity. Mendelian randomization analysis further demonstrated that the Archaeorhizomycetes class, Fusarium genus, and Neoascochyta genus were causally linked to impaired glucose metabolism. Furthermore, integrative analysis with metabolomics showed that increased 4-hydroxy-2-oxoglutaric acid, ketoleucine, lysophosphatidylcholine (20:3/0:0), and N-lactoyl-phenylalanine, but decreased lysophosphatidylcholine (O-18:2), functioned as key molecules linking the adverse effect of Fusarium genus on insulin sensitivity.

CONCLUSIONS

Our study uncovers a strong association between disturbance in gut fungi and the progression of T2DM and highlights the potential of targeting the gut mycobiome for the management of T2DM.

FUNDINGS

This study was supported by MOST and NSFC of China.

Association of indoleamine 2,3 dioxygenase, brain derived neurotrophic factor and cellular senescence in type 2 diabetes mellitus with depression: a clinical approach

BACKGROUND AND AIM

Type 2 diabetes mellitus (T2DM) and depression are often linked. Several studies have reported the role of molecular markers either in diabetes or depression. The present study aimed at molecular level profiling of Indoleamine-2,3-dioxygenase (IDO), brain-derived neurotrophic factor (BDNF) and cellular senescence in patients with type 2 diabetes with and without depression compared to individuals with healthy controls.

METHODS

A total of 120 individuals diagnosed with T2DM were enlisted for the study, with a subset of participants with and without exhibiting depression. The gene expression analysis was done using quantitative real-time PCR.

RESULTS

Indoleamine 2,3 dioxygenase (p < 0.001) and senescence genes (p < 0.001) were significantly upregulated, while brain derived neurotrophic factor (p < 0.01) was significantly downregulated in T2DM patients comorbid with and without depression when compared to healthy controls.

CONCLUSION

Indoleamine 2,3 dioxygenase, Brain derived neurotrophic factor and cellular senescence may play a role in the progression of the disease. The aforementioned discoveries offer significant contributions to our understanding of the molecular mechanisms that underlie T2DM with depression, potentially aiding in the advancement of prediction and diagnostic methods for this particular ailment.

β-Thalassemia and Diabetes Mellitus: Current State and Future Directions

β-Thalassemia major is a congenital hemoglobin disorder that requires regular blood transfusion. The disease is often associated with iron overload and diabetes mellitus, among other complications. Pancreatic iron overload in β-thalassemia patients disrupts β-cell function and insulin secretion and induces insulin resistance. Several risk factors, including family history of diabetes, sedentary lifestyle, obesity, gender, and advanced age increase the risk of diabetes in β-thalassemia patients. Precautionary measures such as blood glucose monitoring, anti-diabetic medications, and healthy living in β-thalassemia patients notwithstanding, the prevalence of diabetes in β-thalassemia patients continues to rise. This review aims to address the relationship between β-thalassemia and diabetes in an attempt to understand how the pathology and management of β-thalassemia precipitate diabetes mellitus. The possible employment of surrogate biomarkers for early prediction and intervention is discussed. More work is still needed to better understand the molecular mechanism(s) underlying the link between β-thalassemia and diabetes and to identify novel prognostic and therapeutic targets.

Effects of electroacupuncture on intestinal microflora and plasma metabolites in an insulin-resistant mouse model of type 2 diabetes mellitus

OBJECTIVE

To investigate the effects of electroacupuncture (EA) at ST36 on intestinal microflora and plasma metabolites in a mouse model of type 2 diabetes mellitus (T2DM), to provide a theoretical basis and guidance for the clinical treatment of T2DM by traditional Chinese medicine (TCM).

METHODS

Sixteen T2DM db/db mice were randomly divided into treatment (T, n = 8) and model (M, n = 8) groups, and a further eight normal db/m+ mice reared under the same conditions served as a non-diabetic control group (C, n = 8). The general conditions of mice were observed weekly. After obtaining blood and stool samples, the mice were euthanized. Fasting blood glucose (FBG) was measured using a glucometer and fasting insulin (FINS) was measured in plasma by enzyme-linked immunosorbent assay (ELISA). Liver and colon tissues were embedded in paraffin and subjected to hematoxylin-eosin (HE) staining to observe pathological changes in these tissues. In addition, 16S ribosomal RNA (rRNA) sequencing was performed to analyze changes in the intestinal flora and metabolomics was employed to assess changes in metabolites in the blood.

RESULTS

EA significantly reduced FBG and FINS levels and alleviated pathological damage to the liver and colon. Furthermore, EA increased intestinal community richness and diversity by decreasing the relative abundance of Clostridium and incresasing the relative abundance of Lactobacillus. EA also reduced D-fructose levels in T2DM mice according to plasma metabolomics.

CONCLUSION

EA has a positive regulatory effect on the intestinal flora and can regulate blood glucose and improve insulin resistance in T2DM model mice.

Excessive Tryptophan and Phenylalanine Induced Pancreatic Injury and Glycometabolism Disorder in Grower-finisher Pigs

BACKGROUND

The increase in circulating insulin levels is associated with the onset of type 2 diabetes (T2D), and the levels of branched-chain amino acids and aromatic amino acids (AAAs) are altered in T2D, but whether AAAs play a role in insulin secretion and signaling remains unclear.

OBJECTIVES

This study aimed to investigate the effects of different AAAs on pancreatic function and on the use of insulin in finishing pigs.

METHODS

A total of 18 healthy finishing pigs (Large White) with average body weight of 100 ± 1.15 kg were randomly allocated to 3 dietary treatments: Con, a normal diet supplemented with 0.68% alanine; Phe, a normal diet supplemented with 1.26% phenylalanine; and Trp, a normal diet supplemented with 0.78% tryptophan. The 3 diets were isonitrogenous. There were 6 replicates in each group.

RESULTS

Herein, we investigated the effects of tryptophan and phenylalanine on pancreatic function and the use of insulin in finishing pigs and found that the addition of tryptophan and phenylalanine aggravated pancreatic fat deposition, increased the relative content of saturated fatty acids, especially palmitate (C16:0) and stearate (C18:0), and the resulting lipid toxicity disrupted pancreatic secretory function. We also found that tryptophan and phenylalanine inhibited the growth and secretion of β-cells, downregulated the gene expression of the PI3K/Akt pathway in the pancreas and liver, and reduced glucose utilization in the liver.

CONCLUSIONS

Using fattening pigs as a model, multiorgan combined analysis of the insulin-secreting organ pancreas and the main insulin-acting organ liver, excessive intake of tryptophan and phenylalanine will aggravate pancreatic damage leading to glucose metabolism disorders, providing new evidence for the occurrence and development of T2D.

Branched-chain amino acid catabolic defect promotes α-cell proliferation via activating mTOR signaling

Elevated circulating level of branched-chain amino acids (BCAAs) is closely related to the development of type 2 diabetes. However, the role of BCAA catabolism in various tissues in maintaining glucose homeostasis remains largely unknown. Pancreatic α-cells have been regarded as amino acid sensors in recent years. Therefore, we generated α-cell specific branched-chain alpha-ketoacid dehydrogenase E1α subunit (BCKDHA) knockout (BCKDHA-αKO) mice to decipher the effects of BCAA catabolism in α-cells on whole-body energy metabolism. BCKDHA-αKO mice showed normal body weight, body fat, and energy expenditure. Plasma glucagon level and glucose metabolism also remained unchanged in BCKDHA-αKO mice. Whereas, the deletion of BCKDHA led to increased α-cell number due to elevated cell proliferation in neonatal mice. In vitro, only leucine among BCAAs promoted aTC1-6 cell proliferation, which was blocked by the agonist of BCAA catabolism BT2 and the inhibitor of mTOR Rapamycin. Like Rapamycin, BT2 attenuated leucine-stimulated phosphorylation of S6 in αTC1-6 cells. Elevated phosphorylation level of S6 protein in pancreatic α-cells was also observed in BCKDHA-αKO mice. These results suggest that local accumulated leucine due to defective BCAA catabolism promotes α-cell proliferation through mTOR signaling, which is insufficient to affect glucagon secretion and whole-body glucose homeostasis.

Interactive Effects of Empagliflozin and Hyperglycemia on Urinary Amino Acids in Individuals With Type 1 Diabetes

Optimizing energy use in the kidney is critical for normal kidney function. Here, we investigate the effect of hyperglycemia and sodium-glucose cotransporter 2 (SGLT2) inhibition on urinary amino acid excretion in individuals with type 1 diabetes (T1D). The open-label ATIRMA trial assessed the impact of 8 weeks of 25 mg empagliflozin orally once per day in 40 normotensive normoalbuminuric young adults with T1D. A consecutive 2-day assessment of clamped euglycemia and hyperglycemia was evaluated at baseline and posttreatment visits. Principal component analysis was performed on urinary amino acids grouped into representative metabolic pathways using MetaboAnalyst. At baseline, acute hyperglycemia was associated with changes in 25 of the 33 urinary amino acids or their metabolites. The most significant amino acid metabolites affected by acute hyperglycemia were 3-hydroxykynurenine, serotonin, glycyl-histidine, and nicotinic acid. The changes in amino acid metabolites were reflected by the induction of four biosynthetic pathways: aminoacyl-tRNA; valine, leucine, and isoleucine; arginine; and phenylalanine, tyrosine, and tryptophan. In acute hyperglycemia, empagliflozin significantly attenuated the increases in aminoacyl-tRNA biosynthesis and valine, leucine, and isoleucine biosynthesis. Our findings using amino acid metabolomics indicate that hyperglycemia stimulates biosynthetic pathways in T1D. SGLT2 inhibition may attenuate the increase in biosynthetic pathways to optimize kidney energy metabolism.

ARTICLE HIGHLIGHTS

Genetic risk score for insulin resistance based on gene variants associated to amino acid metabolism in young adults

Circulating concentration of arginine, alanine, aspartate, isoleucine, leucine, phenylalanine, proline, tyrosine, taurine and valine are increased in subjects with insulin resistance, which could in part be attributed to the presence of single nucleotide polymorphisms (SNPs) within genes associated with amino acid metabolism. Thus, the aim of this work was to develop a Genetic Risk Score (GRS) for insulin resistance in young adults based on SNPs present in genes related to amino acid metabolism. We performed a cross-sectional study that included 452 subjects over 18 years of age. Anthropometric, clinical, and biochemical parameters were assessed including measurement of serum amino acids by high performance liquid chromatography. Eighteen SNPs were genotyped by allelic discrimination. Of these, ten were found to be in Hardy-Weinberg equilibrium, and only four were used to construct the GRS through multiple linear regression modeling. The GRS was calculated using the number of risk alleles of the SNPs in HGD, PRODH, DLD and SLC7A9 genes. Subjects with high GRS (≥ 0.836) had higher levels of glucose, insulin, homeostatic model assessment- insulin resistance (HOMA-IR), total cholesterol and triglycerides, and lower levels of arginine than subjects with low GRS (p < 0.05). The application of a GRS based on variants within genes associated to amino acid metabolism may be useful for the early identification of subjects at increased risk of insulin resistance.

Metabolomic signatures of ideal cardiovascular health in black adults

Plasma metabolomics profiling is an emerging methodology to identify metabolic pathways underlying cardiovascular health (CVH). The objective of this study was to define metabolomic profiles underlying CVH in a cohort of Black adults, a population that is understudied but suffers from disparate levels of CVD risk factors. The Morehouse-Emory Cardiovascular (MECA) Center for Health Equity study cohort consisted of 375 Black adults (age 53 ± 10, 39% male) without known CVD. CVH was determined by the AHA Life's Simple 7 (LS7) score, calculated from measured blood pressure, body mass index (BMI), fasting blood glucose and total cholesterol, and self-reported physical activity, diet, and smoking. Plasma metabolites were assessed using untargeted high-resolution metabolomics profiling. A metabolome wide association study (MWAS) identified metabolites associated with LS7 score after adjusting for age and sex. Using Mummichog software, metabolic pathways that were significantly enriched in metabolites associated with LS7 score were identified. Metabolites representative of these pathways were compared across clinical domains of LS7 score and then developed into a metabolomics risk score for prediction of CVH. We identified novel metabolomic signatures and pathways associated with CVH in a cohort of Black adults without known CVD. Representative and highly prevalent metabolites from these pathways included glutamine, glutamate, urate, tyrosine and alanine, the concentrations of which varied with BMI, fasting glucose, and blood pressure levels. When assessed in conjunction, these metabolites were independent predictors of CVH. One SD increase in the novel metabolomics risk score was associated with a 0.88 higher LS7 score, which translates to a 10.4% lower incident CVD risk. We identified novel metabolomic signatures of ideal CVH in a cohort of Black Americans, showing that a core group of metabolites central to nitrogen balance, bioenergetics, gluconeogenesis, and nucleotide synthesis were associated with CVH in this population.

Characterizing the metabolic divide: distinctive metabolites differentiating CAD-T2DM from CAD patients

OBJECTIVE

To delineate the metabolomic differences in plasma samples between patients with coronary artery disease (CAD) and those with concomitant CAD and type 2 diabetes mellitus (T2DM), and to pinpoint distinctive metabolites indicative of T2DM risk.

METHOD

Plasma samples from CAD and CAD-T2DM patients across three centers underwent comprehensive metabolomic and lipidomic analyses. Multivariate logistic regression was employed to discern the relationship between the identified metabolites and T2DM risk. Characteristic metabolites' metabolic impacts were further probed through hepatocyte cellular experiments. Subsequent transcriptomic analyses elucidated the potential target sites explaining the metabolic actions of these metabolites.

RESULTS

Metabolomic analysis revealed 192 and 95 significantly altered profiles in the discovery (FDR < 0.05) and validation (P < 0.05) cohorts, respectively, that were associated with T2DM risk in univariate logistic regression. Further multivariate regression analyses identified 22 characteristic metabolites consistently associated with T2DM risk in both cohorts. Notably, pipecolinic acid and L-pipecolic acid, lysine derivatives, exhibited negative association with CAD-T2DM and influenced cellular glucose metabolism in hepatocytes. Transcriptomic insights shed light on potential metabolic action sites of these metabolites.

CONCLUSIONS

This research underscores the metabolic disparities between CAD and CAD-T2DM patients, spotlighting the protective attributes of pipecolinic acid and L-pipecolic acid. The comprehensive metabolomic and transcriptomic findings provide novel insights into the mechanism research, prophylaxis and treatment of comorbidity of CAD and T2DM.

Antihypertensives associated adverse events: a review of mechanisms and pharmacogenomic biomarkers available evidence in multi-ethnic populations

Hypertension remains a significant health burden worldwide, re-emphasizing the outstanding need for more effective and safer antihypertensive therapeutic approaches. Genetic variation contributes significantly to interindividual variability in treatment response and adverse events, suggesting pharmacogenomics as a major approach to optimize such therapy. This review examines the molecular mechanisms underlying antihypertensives-associated adverse events and surveys existing research on pharmacogenomic biomarkers associated with these events. The current literature revealed limited conclusive evidence supporting the use of genetic variants as reliable indicators of antihypertensive adverse events. However, several noteworthy associations have emerged, such as 1) the role of ACE variants in increasing the risk of multiple adverse events, 2) the bradykinin pathway's involvement in cough induced by ACE inhibitors, and 3) the impact of CYP2D6 variants on metoprolol-induced bradycardia. Nonetheless, challenges persist in identifying biomarkers for adverse events across different antihypertensive classes, sometimes due to the rarity of certain events, such as ACE inhibitors-induced angioedema. We also highlight the main limitations of previous studies that warrant attention, including using a targeted gene approach with a limited number of tested variants, small sample sizes, and design issues such as overlooking doses or the time between starting treatment and the onset of adverse events. Addressing these challenges requires collaborative efforts and the integration of technological advancements, such as next-generation sequencing, which can significantly enhance research outcomes and provide the needed evidence. Furthermore, the potential combination of genomic biomarker identification and machine learning is a promising approach for tailoring antihypertensive therapy to individual patients, thereby mitigating the risk of developing adverse events. In conclusion, a deeper understanding of the mechanisms and the pharmacogenomics of adverse events in antihypertensive therapy will likely pave the way for more personalized treatment strategies to improve patient outcomes.

Association between type 2 diabetes and branched chain amino acids (BCAA); a case-control study

Background

Several amino acids and their derivatives have been implicated in insulin resistance (IR) and Type 2 Diabetes Mellitus (T2DM). This research sought to establish a relationship between the dietary levels of branched-chain amino acids (BCAA) and the risk of T2DM.

Methods

This case-control study was carried out on 4200 participants consisting of 589 people with T2DM and 3611 non-diabetic aged 35 to 70 years residents in Sabzevar, Iran. Data on the economic-social, employment status, medical history, lifestyle, and sleep habits were collected via interview. The food frequency questionnaire (FFQ) was used to check the nutritional status. Participants' dietary BCAA consumption was estimated using Nutritionist IV software.

Results

A significant negative association between the incidence of T2DM and the dietary levels of BCAAs after adjustment for age and sex (OR = 0.972, CI 95%:0.648-0.996, P = 0.022). The negative association remained significant after additional adjustments for body mass index (BMI) and physical activity (OR = 0.967, CI 95%: 0.943-0.992, P = 0.010). Interestingly, a positive association was found between T2DM and total BCAAs (OR = 1.067, CI 95%: 1.017-1.119, P = 0.008), Isoleucine (OR = 1.248, CI 95%: 1.043-1.494, P = 0.016), Leucine (OR = 1.165, CI 95%: 1.046-1.299, P = 0.006) and Valine (OR = 1.274, CI 95%: 1.088-1.492, P = 0.003) after further adjustment for calorie intake.

Conclusions

Our results demonstrate branched-chain amino acids (BCAAs) including isoleucine, leucine, and valine are negatively associated with the incidence of type 2 diabetes (T2DM) after adjusting for age and sex, BMI, and physical activity. However, adjusting for calorie intake reversed the association between T2DM and BCAAs. These findings suggest that the association between BCAAs and T2DM may be influenced by calorie intake. Future longitudinal studies are warranted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01247-9.

Regulation of Macronutrients in Insulin Resistance and Glucose Homeostasis during Type 2 Diabetes Mellitus

Insulin resistance is an important feature of metabolic syndrome and a precursor of type 2 diabetes mellitus (T2DM). Overnutrition-induced obesity is a major risk factor for the development of insulin resistance and T2DM. The intake of macronutrients plays a key role in maintaining energy balance. The components of macronutrients distinctly regulate insulin sensitivity and glucose homeostasis. Precisely adjusting the beneficial food compound intake is important for the prevention of insulin resistance and T2DM. Here, we reviewed the effects of different components of macronutrients on insulin sensitivity and their underlying mechanisms, including fructose, dietary fiber, saturated and unsaturated fatty acids, and amino acids. Understanding the diet-gene interaction will help us to better uncover the molecular mechanisms of T2DM and promote the application of precision nutrition in practice by integrating multi-omics analysis.

Metabolite profiles of diabetes mellitus and response to intervention in anti-hyperglycemic drugs

Type 2 diabetes mellitus (T2DM) has become a major health problem, threatening the quality of life of nearly 500 million patients worldwide. As a typical multifactorial metabolic disease, T2DM involves the changes and interactions of various metabolic pathways such as carbohydrates, amino acid, and lipids. It has been suggested that metabolites are not only the endpoints of upstream biochemical processes, but also play a critical role as regulators of disease progression. For example, excess free fatty acids can lead to reduced glucose utilization in skeletal muscle and induce insulin resistance; metabolism disorder of branched-chain amino acids contributes to the accumulation of toxic metabolic intermediates, and promotes the dysfunction of β-cell mitochondria, stress signal transduction, and apoptosis. In this paper, we discuss the role of metabolites in the pathogenesis of T2DM and their potential as biomarkers. Finally, we list the effects of anti-hyperglycemic drugs on serum/plasma metabolic profiles.

A specific plasma amino acid profile in the Insulin2Q104del Kuma mice at the diabetic state and reversal from hyperglycemia

The metabolites in the plasma serve as potential biomarkers of disease. We previously established an early-onset diabetes mouse model, Ins2+/Q104del Kuma mice, under a severe immune-deficient (Rag-2/Jak3 double-deficient in BALB/c) background. Here, we revealed the differences in plasma amino acid profiles between Kuma and the wild-type mice. We observed an early reduction in glucogenic and ketogenic amino acids, a late increase in branched-chain amino acids (BCAAs) and succinyl CoA-related amino acids, and a trend of increasing ketogenic amino acids in Kuma mice than in the wild-type mice. Kuma mice exhibited hyperglucagonemia at high blood glucose, leading to perturbations in plasma amino acid profiles. The reversal of blood glucose by islet transplantation normalized the increases of the BCAAs and several aspects of the altered metabolic profiles in Kuma mice. Our results indicate that the Kuma mice are a unique animal model to study the link between plasma amino acid profile and the progression of diabetes for monitoring the therapeutic effects.

Metabolomic Profiles of Nonobese and Obese Women With Gestational Diabetes

CONTEXT

In non-pregnant population, nonobese individuals with obesity-related metabolome have increased risk for type 2 diabetes and cardiovascular diseases. The risk of these diseases is also increased after gestational diabetes.

OBJECTIVE

This work aimed to examine whether nonobese (body mass index [BMI] < 30) and obese (BMI ≥ 30) women with gestational diabetes mellitus (GDM) and obese non-GDM women differ in metabolomic profiles from nonobese non-GDM controls.

METHODS

Levels of 66 metabolic measures were assessed in early (median 13, IQR 12.4-13.7 gestation weeks), and across early, mid (20, 19.3-23.0), and late (28, 27.0-35.0) pregnancy blood samples in 755 pregnant women from the PREDO and RADIEL studies. The independent replication cohort comprised 490 pregnant women.

RESULTS

Nonobese and obese GDM, and obese non-GDM women differed similarly from the controls across early, mid, and late pregnancy in 13 measures, including very low-density lipoprotein-related measures, and fatty acids. In 6 measures, including fatty acid (FA) ratios, glycolysis-related measures, valine, and 3-hydroxybutyrate, the differences between obese GDM women and controls were more pronounced than the differences between nonobese GDM or obese non-GDM women and controls. In 16 measures, including HDL-related measures, FA ratios, amino acids, and inflammation, differences between obese GDM or obese non-GDM women and controls were more pronounced than the differences between nonobese GDM women and controls. Most differences were evident in early pregnancy, and in the replication cohort were more often in the same direction than would be expected by chance alone.

CONCLUSION

Differences between nonobese and obese GDM, or obese non-GDM women and controls in metabolomic profiles may allow detection of high-risk women for timely targeted preventive interventions.

Alteration of Branched-Chain and Aromatic Amino Acid Profile as a Novel Approach in Studying Polycystic Ovary Syndrome Pathogenesis

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that affects reproductive-age women and predisposes them to the development of metabolic disturbances. Recent research has shown that several metabolic factors may play a role in PCOS pathogenesis, and it has been suggested that an alteration in the amino acid profile might be a predictive sign of metabolic disorders. Metabolically healthy obesity (MHO) and metabolically unhealthy obesity (MUO) are concepts that have attracted scientific attention; however, a universal definition has not been established yet for these terms. Already existing definitions of MHO involve the coexistence of obesity with the absence or minimal presence of other metabolic syndrome parameters. A group of 326 women, 209 diagnosed with PCOS and 117 healthy individuals, participated in this study. Multiple parameters were assessed, including anthropometrical, biochemical, and hormonal ones, and gas-liquid chromatography, combined with tandem mass spectrometry, was used to investigate the amino acid profile. Statistical analysis revealed noticeably higher levels of all aromatic amino acids in PCOS women compared to the control group: phenylalanine 47.37 ± 7.0 vs. 45.4 ± 6.09 nmol/mL (p = 0.01), tyrosine 61.69 ± 9.56 vs. 58.08 ± 8.89 nmol/mL (p < 0.01), and tryptophan 53.66 ± 11.42 vs. 49.81 ± 11.18 nmol/mL (p < 0.01); however, there was no significant difference in the "tryptophan ratio" between the PCOS and control group (p = 0.88). A comparison of MHO and MUO PCOS women revealed that LAP, leucine, and isoleucine concentrations were significantly higher among the MUO subgroup: respectively, 101.98 ± 34.74 vs. 55.80 ± 24.33 (p < 0.001); 153.26 ± 22.26 vs. 137.25 ± 25.76 nmol/mL (p = 0.04); and 92.92 ± 16.09 vs. 82.60 ± 18.70 nmol/mL (p = 0.02). No significant differences in BMI, fasting glucose, and HOMA-IR between MHO and MUO were found: respectively, 35.0 ± 4.8 vs. 36.1 ± 4.6 kg/m2 (p = 0.59); 88.0 ± 6.0 vs. 87.73 ± 6.28 mg/dL (p = 0.67); and 3.36 ± 1.70 vs. 4.17 ± 1.77 (p = 0.1). The identification of altered amino acid profiles in PCOS holds potential clinical implications. Amino acids may serve as biomarkers for diagnosing and monitoring the metabolic status of individuals with PCOS. The alteration of BCAAs and AAAs may be involved in PCOS pathogenesis, but the underlying mechanism should be further investigated.

Dietary branched-chain amino acids intake, glycemic markers, metabolic profile, and anthropometric features in a community-based sample of overweight and obese adults

BACKGROUND

Existing research provides conflicting evidence regarding the relationship between estimated branched-chain amino acid (BCAA) intake and metabolic, glycemic markers, and anthropometric characteristics. This research seeks to examine the association between estimated dietary BCAA consumption and glycemic, and metabolic markers, as well as anthropometric parameters in adults classified as overweight or obese.

METHODS

In this cross-sectional analysis, we gathered data from 465 overweight and obese individuals aged between 18 and 37 years. To evaluate dietary data, we employed the food frequency questionnaire, and the BCAA content in foods was determined via the United States Department of Agriculture website. We utilized ELISA kits to measure fasting blood glucose (FBS) and lipid profile markers, and additionally calculated low-density lipoprotein (LDL) and insulin sensitivity markers. We assessed sociodemographic status, physical activity (PA), and anthropometric attributes through a method recognized as both valid and reliable. For statistical analysis, we conducted analyses of covariance (ANCOVA), making adjustments for variables including sex, PA, age, energy, and body mass index (BMI).

RESULTS

Upon adjusting for confounders, those in the highest tertiles of BCAA intake exhibited an increase in weight, BMI, waist circumference (WC), waist-to-hip ratio (WHR), and fat-free mass (FFM). Conversely, they demonstrated reduced fat mass (FM) (%) and FM (kg) compared to their counterparts in the lowest tertiles (P < 0.05). Additionally, there was a noted association between greater estimated BCAA intake and reduced LDL levels. Nonetheless, our findings did not reveal a significant relationship between dietary BCAA and glycemic indices.

CONCLUSIONS

From our findings, an increased estimated intake of BCAA seems to correlate with diminished serum LDL concentrations. To gain a more comprehensive understanding of this association, it is imperative that further experimental and longitudinal studies be conducted.

Unlocking the Potential: Amino Acids' Role in Predicting and Exploring Therapeutic Avenues for Type 2 Diabetes Mellitus

Diabetes mellitus, particularly type 2 diabetes mellitus (T2DM), imposes a significant global burden with adverse clinical outcomes and escalating healthcare expenditures. Early identification of biomarkers can facilitate better screening, earlier diagnosis, and the prevention of diabetes. However, current clinical predictors often fail to detect abnormalities during the prediabetic state. Emerging studies have identified specific amino acids as potential biomarkers for predicting the onset and progression of diabetes. Understanding the underlying pathophysiological mechanisms can offer valuable insights into disease prevention and therapeutic interventions. This review provides a comprehensive summary of evidence supporting the use of amino acids and metabolites as clinical biomarkers for insulin resistance and diabetes. We discuss promising combinations of amino acids, including branched-chain amino acids, aromatic amino acids, glycine, asparagine and aspartate, in the prediction of T2DM. Furthermore, we delve into the mechanisms involving various signaling pathways and the metabolism underlying the role of amino acids in disease development. Finally, we highlight the potential of targeting predictive amino acids for preventive and therapeutic interventions, aiming to inspire further clinical investigations and mitigate the progression of T2DM, particularly in the prediabetic stage.

Serum branch-chained amino acids are increased in type 2 diabetes and associated with atherosclerotic cardiovascular disease

BACKGROUND AND AIM

Circulating biomarkers of metabolic and cardiovascular diseases can help in the early detection and prevention of those diseases. Using proton nuclear magnetic resonance (1H-NMR), we aimed to study the plasma levels of low-molecular-weight metabolites (LMWMs) in a cohort of 307 patients with metabolic diseases to assess their relationships with type-2 diabetes (T2D) and incident atherosclerotic cardiovascular disease (ASCVD).

METHODS

We conducted a cross-sectional and prospective study. We included 307 patients attending the Lipid Unit of our University Hospital for the treatment of the following metabolic disturbances and associated disorders: T2D (73.9%), obesity (58.7%), and hypertension (55.1%). 1H-NMR was used to study the plasma levels of 13 LMWMs. LMWM serum concentrations were evaluated in patients with and without T2D. and the correlations with several parameters and their associations with T2D were analyzed. The association between LMWM levels at baseline and the development of ASCVD in patients with T2D after 10 years of follow-up was also evaluated.

RESULTS

Among the LMWMs measured, the branched-chain amino acids (BCAAs) valine, leucine and isoleucine showed a positive association with several clinical and lipid-related biochemical parameters and inflammatory markers (p < 0.05). Likewise, these three BCAAS were associated with diabetes even after adjusting for covariates (p < 0.05). During the follow-up period of 10 years, 29 of the 185 patients with diabetes at baseline (15.68%) developed ASCVD. After adjusting for clinical covariates, baseline levels of valine and alanine were associated with the development of ASCVD (p < 0.05).

CONCLUSION

Overall, our results indicated that plasma levels of LMWMs measured by 1H-NMR could be potential biomarkers associated with T2D. Moreover, alanine and valine can help in the early detection of the cardiovascular risk associated with this metabolic disease.

Active role of amino acid metabolism in early diagnosis and treatment of diabetic kidney disease

Diabetic Kidney Disease (DKD) is one of the significant microvascular consequences of type 2 diabetes mellitus with a complex etiology and protracted course. In the early stages of DKD, the majority of patients experience an insidious onset and few overt clinical symptoms and indicators, but they are prone to develop end-stage renal disease in the later stage, which is life-threatening. The abnormal amino acid metabolism is tightly associated with the development of DKD, which involves several pathological processes such as oxidative stress, inflammatory response, and immune response and is also closely related to autophagy, mitochondrial dysfunction, and iron death. With a focus on taurine, branched-chain amino acids (BCAAs) and glutamine, we explored the biological effects of various amino acid mechanisms linked to DKD, the impact of amino acid metabolism in the early diagnosis of DKD, and the role of amino acid metabolism in treating DKD, to offer fresh objectives and guidelines for later early detection and DKD therapy.

The Association between Circulating 25-Hydroxyvitamin D and Carotid Intima-Media Thickness Is Mediated by Gut Microbiota and Fecal and Serum Metabolites in Adults

SCOPE

Vitamin D is vital to cardiovascular health. This study examines the association between plasma 25-hydroxyvitamin D (25[OH]D) and the progression of carotid intima-media thickness (cIMT) and identifies the potential mediating biomarkers of gut microbiota and metabolites in adults.

METHODS AND RESULTS

This 9-year prospective study includes 2975 subjects with plasma 25(OH)D at baseline and determined cIMT every 3 years. Higher circulating 25(OH)D is associated with decreased odds of higher (≥median) 9-year cIMT changes at the common carotid artery (hΔCCA-cIMT) (p-trend < 0.001). Multivariable-adjusted OR (95%CI) of hΔCCA-cIMT for tertiles 2 and 3 (vs. 1) of 25(OH)D is 0.87 (0.73-1.04) and 0.68 (0.57-0.82). Gut microbiome and metabolome analysis identify 18 biomarkers significantly associated with both 25(OH)D and hΔCCA-cIMT, including three microbial genera, seven fecal metabolites, eight serum metabolites, and pathway of synthesis and degradation of ketone bodies. Mediation/path analyses show the scores generated from the overlapped differential gut microbiota, fecal and serum metabolites, and serum acetoacetic acid alone could mediate the beneficial association between 25(OH)D and hΔCCA-cIMT by 10.8%, 23.1%, 59.2%, and 62.0% (all p < 0.05), respectively.

CONCLUSIONS

These findings show a beneficial association between plasma 25(OH)D and the CCA-cIMT progression. The identified multi-omics biomarkers provide novel mechanistic insights for the epidemiological association.

Changes in Branched-Chain Amino Acids One Year after Sleeve Gastrectomy in Youth with Obesity and Their Association with Changes in Insulin Resistance

Adults with obesity have a reduction in branched-chain amino acid (BCAA) levels following metabolic and bariatric surgery (MBS), which is hypothesized to contribute to the metabolic advantages of MBS. We examined this relationship in 62 youth 13-24 years old with severe obesity (47 female) over 12 months. Thirty had sleeve gastrectomy (SG) and 32 were non-surgical controls (NS). We measured fasting insulin, glucose, glycated hemoglobin (HbA1c), isoleucine, leucine, and valine concentrations, and post-prandial insulin and glucose, following a mixed meal tolerance test. Twenty-four-hour food recalls were collected. At baseline, groups did not differ in the intake or the serum levels of BCAAs, HbA1C, HOMA-IR, Matsuda index, insulinogenic index, or oral Disposition index (oDI). Over 12 months, SG vs. NS had greater reductions in serum BCAAs, and SG had significant reductions in BCAA intake. SG vs. NS had greater reductions in HbA1c and HOMA-IR, with increases in the Matsuda index and oDI. In SG, baseline leucine and total BCAA concentrations were negatively correlated with the baseline Matsuda index. Reductions in serum leucine were positively associated with the reductions in HOMA-IR over 12 months. These associations suggest a potential role of BCAA in regulating metabolic health. Reducing dietary intake and serum BCAA concentrations may reduce insulin resistance.

Impaired Adipocyte SLC7A10 Promotes Lipid Storage in Association With Insulin Resistance and Altered BCAA Metabolism

CONTEXT

The neutral amino acid transporter SLC7A10/ASC-1 is an adipocyte-expressed gene with reduced expression in insulin resistance and obesity. Inhibition of SLC7A10 in adipocytes was shown to increase lipid accumulation despite decreasing insulin-stimulated uptake of glucose, a key substrate for de novo lipogenesis. These data imply that alternative lipogenic substrates to glucose fuel continued lipid accumulation during insulin resistance in obesity.

OBJECTIVE

We examined whether increased lipid accumulation during insulin resistance in adipocytes may involve alter flux of lipogenic amino acids dependent on SLC7A10 expression and activity, and whether this is reflected by extracellular and circulating concentrations of marker metabolites.

METHODS

In adipocyte cultures with impaired SLC7A10, we performed RNA sequencing and relevant functional assays. By targeted metabolite analyses (GC-MS/MS), flux of all amino acids and selected metabolites were measured in human and mouse adipose cultures. Additionally, SLC7A10 mRNA levels in human subcutaneous adipose tissue (SAT) were correlated to candidate metabolites and adiposity phenotypes in 2 independent cohorts.

RESULTS

SLC7A10 impairment altered expression of genes related to metabolic processes, including branched-chain amino acid (BCAA) catabolism, lipogenesis, and glyceroneogenesis. In 3T3-L1 adipocytes, SLC7A10 inhibition increased fatty acid uptake and cellular content of glycerol and cholesterol. SLC7A10 impairment in SAT cultures altered uptake of aspartate and glutamate, and increased net uptake of BCAAs, while increasing the net release of the valine catabolite 3- hydroxyisobutyrate (3-HIB). In human cohorts, SLC7A10 mRNA correlated inversely with total fat mass, circulating triacylglycerols, BCAAs, and 3-HIB.

CONCLUSION

Reduced SLC7A10 activity strongly affects flux of BCAAs in adipocytes, which may fuel continued lipogenesis during insulin resistance, and be reflected in increased circulating levels of the valine-derived catabolite 3-HIB.

Metabolomics of Type 2 Diabetes Mellitus in Sprague Dawley Rats-In Search of Potential Metabolic Biomarkers

Type 2 diabetes mellitus (T2DM) is an expanding global health concern, closely associated with the epidemic of obesity. Individuals with diabetes are at high risk for microvascular and macrovascular complications, which include retinopathy, neuropathy, and cardiovascular comorbidities. Despite the availability of diagnostic tools for T2DM, approximately 30-60% of people with T2DM in developed countries are never diagnosed or detected. Therefore, there is a strong need for a simpler and more reliable technique for the early detection of T2DM. This study aimed to use a non-targeted metabolomic approach to systematically identify novel biomarkers from the serum samples of T2DM-induced Sprague Dawley (SD) rats using a comprehensive two-dimensional gas chromatography coupled with a time-of-flight mass spectrometry (GCxGC-TOF/MS). Fifty-four male Sprague Dawley rats weighing between 160-180 g were randomly assigned into two experimental groups, namely the type 2 diabetes mellitus group (T2DM) (n = 36) and the non-diabetic control group (n = 18). Results from this study showed that the metabolite signature of the diabetic rats was different from that of the non-diabetic control group. The most significantly upregulated metabolic pathway was aminoacyl-t-RNA biosynthesis. Metabolite changes observed between the diabetic and non-diabetic control group was attributed to the increase in amino acids, such as glycine, L-asparagine, and L-serine. Aromatic amino acids, including L-tyrosine, were associated with the risk of future hyperglycemia and overt diabetes. The identified potential biomarkers depicted a good predictive value of more than 0.8. It was concluded from the results that amino acids that were associated with impaired insulin secretion were prospectively related to an increase in glucose levels. Moreover, amino acids that were associated with impaired insulin secretion were prospectively related to an increase in glucose levels.

Multi-omic longitudinal study reveals immune correlates of clinical course among hospitalized COVID-19 patients

The IMPACC cohort, composed of >1,000 hospitalized COVID-19 participants, contains five illness trajectory groups (TGs) during acute infection (first 28 days), ranging from milder (TG1-3) to more severe disease course (TG4) and death (TG5). Here, we report deep immunophenotyping, profiling of >15,000 longitudinal blood and nasal samples from 540 participants of the IMPACC cohort, using 14 distinct assays. These unbiased analyses identify cellular and molecular signatures present within 72 h of hospital admission that distinguish moderate from severe and fatal COVID-19 disease. Importantly, cellular and molecular states also distinguish participants with more severe disease that recover or stabilize within 28 days from those that progress to fatal outcomes (TG4 vs. TG5). Furthermore, our longitudinal design reveals that these biologic states display distinct temporal patterns associated with clinical outcomes. Characterizing host immune responses in relation to heterogeneity in disease course may inform clinical prognosis and opportunities for intervention.

Aromatic Amino Acids and Their Interactions with Gut Microbiota-Related Metabolites for Risk of Gestational Diabetes: A Prospective Nested Case-Control Study in a Chinese Cohort

INTRODUCTION

The aim of this study was to explore associations of aromatic amino acids (AAA) in early pregnancy with gestational diabetes mellitus (GDM), and whether high AAA and gut microbiota-related metabolites had interactive effects on GDM risk.

METHODS

We conducted a 1:1 case-control study (n = 486) nested in a prospective cohort of pregnant women from 2010 to 2012. According to the International Association of Diabetes and Pregnancy Study Group's criteria, 243 women were diagnosed with GDM. Binary conditional logistic regression was performed to examine associations of AAA with GDM risk. Interactions between AAA and gut microbiota-related metabolites for GDM were examined using additive interaction measures.

RESULTS

High phenylalanine and tryptophan were associated with increased GDM risk (OR: 1.72, 95% CI: 1.07-2.78 and 1.66, 1.02-2.71). The presence of high trimethylamine (TMA) markedly increased the OR of high phenylalanine alone up to 7.95 (2.79-22.71), while the presence of low glycoursodeoxycholic acid (GUDCA) markedly increased the OR of high tryptophan alone up to 22.88 (5.28-99.26), both with significant additive interactions. Furthermore, high lysophosphatidylcholines (LPC18:0) mediated both interactive effects.

CONCLUSIONS

High phenylalanine may have an additive interaction with high TMA, while high tryptophan may have an additive interaction with low GUDCA toward increased risk of GDM, both being mediated via LPC18:0.

Uncoupling hepatic insulin resistance - hepatic inflammation to improve insulin sensitivity and to prevent impaired metabolism-associated fatty liver disease in type 2 diabetes

Diabetes mellitus is a metabolic disease clinically-characterized as acute and chronic hyperglycemia. It is emerging as one of the common conditions associated with incident liver disease in the US. The mechanism by which diabetes drives liver disease has become an intense topic of discussion and a highly sought-after therapeutic target. Insulin resistance (IR) appears early in the progression of type 2 diabetes (T2D), particularly in obese individuals. One of the co-morbid conditions of obesity-associated diabetes that is on the rise globally is referred to as non-alcoholic fatty liver disease (NAFLD). IR is one of a number of known and suspected mechanism that underlie the progression of NAFLD which concurrently exhibits hepatic inflammation, particularly enriched in cells of the innate arm of the immune system. In this review we focus on the known mechanisms that are suspected to play a role in the cause-effect relationship between hepatic IR and hepatic inflammation and its role in the progression of T2D-associated NAFLD. Uncoupling hepatic IR/hepatic inflammation may break an intra-hepatic vicious cycle, facilitating the attenuation or prevention of NAFLD with a concurrent restoration of physiologic glycemic control. As part of this review, we therefore also assess the potential of a number of existing and emerging therapeutic interventions that can target both conditions simultaneously as treatment options to break this cycle.

Effects of ranolazine on right ventricular function, fluid dynamics, and metabolism in patients with precapillary pulmonary hypertension: insights from a longitudinal, randomized, double-blinded, placebo controlled, multicenter study

Introduction

Right ventricular (RV) function is a major determinant of outcome in patients with precapillary pulmonary hypertension (PH). We studied the effect of ranolazine on RV function over 6 months using multi-modality imaging and biochemical markers in patients with precapillary PH (groups I, III, and IV) and RV dysfunction [CMR imaging ejection fraction (EF) < 45%] in a longitudinal, randomized, double-blinded, placebo-controlled, multicenter study of ranolazine treatment.

Methods

Enrolled patients were assessed using cardiac magnetic resonance (CMR) imaging, 11C-acetate and 18-F-FDG positron emission tomography (PET), and plasma metabolomic profiling, at baseline and at the end of treatment.

Results

Twenty-two patients were enrolled, and 15 patients completed all follow-up studies with 9 in the ranolazine arm and 6 in the placebo arm. RVEF and RV/Left ventricle (LV) mean glucose uptake were significantly improved after 6 months of treatment in the ranolazine arm. Metabolomic changes in aromatic amino acid metabolism, redox homeostasis, and bile acid metabolism were observed after ranolazine treatment, and several changes significantly correlated with changes in PET and CMR-derived fluid dynamic measurements.

Discussion

Ranolazine may improve RV function by altering RV metabolism in patients with precapillary PH. Larger studies are needed to confirm the beneficial effects of ranolazine.

Metabolomics signatures of depression: the role of symptom profiles

Depression shows a metabolomic signature overlapping with that of cardiometabolic conditions. Whether this signature is linked to specific depression profiles remains undetermined. Previous research suggested that metabolic alterations cluster more consistently with depressive symptoms of the atypical spectrum related to energy alterations, such as hyperphagia, weight gain, hypersomnia, fatigue and leaden paralysis. We characterized the metabolomic signature of an "atypical/energy-related" symptom (AES) profile and evaluated its specificity and consistency. Fifty-one metabolites measured using the Nightingale platform in 2876 participants from the Netherlands Study of Depression and Anxiety were analyzed. An 'AES profile' score was based on five items of the Inventory of Depressive Symptomatology (IDS) questionnaire. The AES profile was significantly associated with 31 metabolites including higher glycoprotein acetyls (β = 0.13, p = 1.35*10^-12), isoleucine (β = 0.13, p = 1.45*10^-10), very-low-density lipoproteins cholesterol (β = 0.11, p = 6.19*10^-9) and saturated fatty acid levels (β = 0.09, p = 3.68*10^-10), and lower high-density lipoproteins cholesterol (β = -0.07, p = 1.14*10^-4). The metabolites were not significantly associated with a summary score of all other IDS items not included in the AES profile. Twenty-five AES-metabolites associations were internally replicated using data from the same subjects (N = 2015) collected at 6-year follow-up. We identified a specific metabolomic signature-commonly linked to cardiometabolic disorders-associated with a depression profile characterized by atypical, energy-related symptoms. The specific clustering of a metabolomic signature with a clinical profile identifies a more homogenous subgroup of depressed patients at higher cardiometabolic risk, and may represent a valuable target for interventions aiming at reducing depression's detrimental impact on health.

NMR-based metabolomic profiling identifies inflammation and muscle-related metabolites as predictors of incident type 2 diabetes mellitus beyond glucose: the Di@bet.es study

AIMS

The aim of this study was to combine nuclear magnetic resonance-based metabolomics and machine learning to find a glucose-independent molecular signature associated with future type 2 diabetes mellitus development in a subgroup of individuals from the Di@bet.es study.

METHODS

The study group included 145 individuals developing type 2 diabetes mellitus during the 8-year follow-up, 145 individuals matched by age, sex and BMI who did not develop diabetes during the follow-up but had equal glucose concentrations to those who did and 145 controls matched by age and sex. A metabolomic analysis of serum was performed to obtain the lipoprotein and glycoprotein profiles and 15 low molecular weight metabolites. Several machine learning-based models were trained.

RESULTS

Logistic regression performed the best classification between individuals developing type 2 diabetes during the follow-up and glucose-matched individuals. The area under the curve was 0.628, and its 95% confidence interval was 0.510-0.746. Glycoprotein-related variables, creatinine, creatine, small HDL particles and the Johnson-Neyman intervals of the interaction of Glyc A and Glyc B were statistically significant.

CONCLUSIONS

The model highlighted a relevant contribution of inflammation (glycosylation pattern and HDL) and muscle (creatinine and creatine) in the development of type 2 diabetes as independent factors of hyperglycemia.

Age-related metabolite profiles and their relation to clinical outcomes in young adults, middle-aged individuals, and older people

Age is a significant risk factor for common noncommunicable diseases, yet the physiological alterations of aging are poorly understood. We were interested in metabolic patterns between cross-sectional cohorts of different age ranges with particular emphasis on waist circumference. We recruited three cohorts of healthy subjects with different age ranges (adolescents 18-25 years, adults 40-65 years, and older citizens 75-85 years) and stratified these based on waist circumference. Using targeted LC-MS/MS metabolite profiling, we analyzed 112 analytes in plasma (amino acids, acylcarnitines, and derivatives). We associated age-related alterations with various anthropometric and functional parameters such as insulin sensitivity and handgrip strength. Strongest age-dependent increases were found for fatty acid-derived acylcarnitines. Amino acid-derived acylcarnitines displayed increased associations with BMI and adiposity. Some essential amino acids changed in opposite directions, being lower at increased age and higher with increasing adiposity. τ-methylhistidine was elevated in older subjects, especially on an adiposity background, suggesting an increased protein turnover. Both aging and adiposity are associated with impaired insulin sensitivity. Skeletal muscle mass decreased with age and increased with adiposity. Profound differences in the metabolite signatures during healthy aging and elevated waist circumference/body weight were found. Opposite changes in skeletal muscle mass as well as possible differences in insulin signaling (relative insulin deficiency in older subjects versus hyperinsulinemia associated with adiposity), might be underlying origins for the observed metabolite signatures. We describe novel associations between metabolites and anthropometric factors during aging which underlines the complex interplay of aging, insulin resistance, and metabolic health.

Effect of L-serine on oxidative stress markers in the kidney of streptozotocin-induced diabetic mice

Oxidative stress is critical in the occurrence and development of diabetes and its related complications. L-serine has recently been shown to reduce oxidative stress, the incidence of autoimmune diabetes and improve glucose homeostasis. The aim of this study was to investigate the effects of daily L-serine administration on blood glucose, renal function and oxidative stress markers in the kidney of streptozotocin-induced diabetic mice. Eighteen C57BL/6 male mice were randomly divided into three groups (n = 6 per group). Streptozotocin was used to induce diabetes and a group of diabetic mice was treated with 280 mg/day of L-serine dissolved in drinking water for 4 weeks. The level of blood glucose, biochemical markers of renal function (total protein, urea, creatinine and albumin) and oxidative stress markers (protein carbonyls, malondialdehyde, glutathione peroxidase, superoxide dismutase and catalase) were measured using spectrophotometry. The results indicated that L-serine significantly decreased the glucose level in diabetic mice (188.6 ± 22.69 mg/dL, P = 0.02). Moreover, treatment of diabetic mice with L-serine reduced protein carbonyls (3.249 ± 0.9165 nmol/mg protein, P < 0.05) and malondialdehyde levels (1.891 ± 0.7696 μM/mg protein, P = 0.051). However, L-serine showed no significant effects on renal function, and a slight reduction in histopathological changes was observed in mice receiving L-serine. This study revealed that L-serine effectively ameliorates oxidative stress in kidney tissue and reduces the blood glucose concentration in diabetic mice.

Serum, Urine, and Fecal Metabolome Alterations in the Gut Microbiota in Response to Lifestyle Interventions in Pediatric Obesity: A Non-Randomized Clinical Trial

Pediatric obesity is associated with alterations in the gut microbiota and its metabolites. However, how they influence obesity and the effect of lifestyle interventions remains unknown.. In this non-randomized clinical trial, we analyzed metabolomes and microbial features to understand the associated metabolic pathways and the effect of lifestyle interventions on pediatric obesity. Anthropometric/biochemical data and fasting serum, urine, and fecal samples were collected at baseline and after an eight-week, weight-reduction lifestyle modification program. Post-intervention, children with obesity were classified into responder and non-responder groups based on changes in total body fat. At baseline, serum L-isoleucine and uric acid levels were significantly higher in children with obesity compared with those in normal-weight children and were positively correlated with obesogenic genera. Taurodeoxycholic and tauromuricholic α + β acid levels decreased significantly with obesity and were negatively correlated with obesogenic genera. Branched-chain amino acid and purine metabolisms were distinguished metabolic pathways in the obese group. Post-intervention, urinary myristic acid levels decreased significantly in the responder group, showing a significant positive correlation with Bacteroides. Fatty acid biosynthesis decreased significantly in the responder group. Thus, lifestyle intervention with weight loss is associated with changes in fatty acid biosynthesis, and myristic acid is a possible therapeutic target for pediatric obesity.

Longitudinal trajectories of branched chain amino acids through young adulthood and diabetes in later life

BACKGROUNDElevated circulating branched chain amino acids (BCAAs), measured at a single time point in middle life, are strongly associated with an increased risk of developing type 2 diabetes mellitus (DM). However, the longitudinal patterns of change in BCAAs through young adulthood and their association with DM in later life are unknown.METHODSWe serially measured BCAAs over 28 years in the Coronary Artery Risk Development in Young Adults (CARDIA) study, a prospective cohort of apparently healthy Black and White young adults at baseline. Trajectories of circulating BCAA concentrations from years 2-30 (for prevalent DM) or years 2-20 (for incident DM) were determined by latent class modeling.RESULTSAmong 3,081 apparently healthy young adults, trajectory analysis from years 2-30 revealed 3 distinct BCAA trajectory groups: low-stable (n = 1,427), moderate-stable (n = 1,384), and high-increasing (n = 270) groups. Male sex, higher body mass index, and higher atherogenic lipid fractions were more common in the moderate-stable and high-increasing groups. Higher risk of prevalent DM was associated with the moderate-stable (OR = 2.59, 95% CI: 1.90-3.55) and high-increasing (OR = 6.03, 95% CI: 3.86-9.43) BCAA trajectory groups in adjusted models. A separate trajectory group analysis from years 2-20 for incident DM after year 20 showed that moderate-stable and high-increasing trajectory groups were also significantly associated with higher risk of incident DM, after adjustment for clinical variables and glucose levels.CONCLUSIONBCAA levels track over a 28-year span in most young adults, but serial clinical metabolomic measurements identify subpopulations with rising levels associated with high risk of DM in later life.FUNDINGThis research was supported by the NIH, under grants R01 HL146844 (JTW) and T32 HL069771 (MRC). The CARDIA study is conducted and supported by the NIH National Heart, Lung, and Blood Institute in collaboration with the University of Alabama at Birmingham (HHSN268201800005I and HHSN268201800007I), Northwestern University (HHSN268201800003I), the University of Minnesota (HHSN268201800006I), and Kaiser Foundation Research Institute (HHSN268201800004I).

Insulin Resistance and Impaired Branched-Chain Amino Acid Metabolism in Alzheimer's Disease

The pathogenesis of Alzheimer's disease (AD) is complicated and involves multiple contributing factors. Mounting evidence supports the concept that AD is an age-related metabolic neurodegenerative disease mediated in part by brain insulin resistance, and sharing similar metabolic dysfunctions and brain pathological characteristics that occur in type 2 diabetes mellitus (T2DM) and other insulin resistance disorders. Brain insulin signal pathway is a major regulator of branched-chain amino acid (BCAA) metabolism. In the past several years, impaired BCAA metabolism has been described in several insulin resistant states such as obesity, T2DM and cardiovascular disease. Disrupted BCAA metabolism leading to elevation in circulating BCAAs and related metabolites is an early metabolic phenotype of insulin resistance and correlated with future onset of T2DM. Brain is a major site for BCAA metabolism. BCAAs play pivotal roles in normal brain function, especially in signal transduction, nitrogen homeostasis, and neurotransmitter cycling. Evidence from animal models and patients support the involvement of BCAA dysmetabolism in neurodegenerative diseases including Huntington's disease, Parkinson's disease, and maple syrup urine disease. More recently, growing studies have revealed altered BCAA metabolism in AD, but the relationship between them is poorly understood. This review is focused on the recent findings regarding BCAA metabolism and its role in AD. Moreover, we will explore how impaired BCAA metabolism influences brain function and participates in the pathogenesis of AD.

The effects of vitamin B6 on the nutritional support of BCAAs-enriched amino acids formula in rats with partial gastrectomy

BACKGROUND

Total parenteral nutrition with the formula of amino acids enriched branched-chain amino acids (BCAAs) could promote patients' recovery after gastrointestinal surgery. Previous studies reported that vitamin B6 could promote amino acid metabolism and enhance protein synthesis. The aim of this study was to determine if the addition of vitamin B6 to BCAAs-enriched formula can enhance postoperative nutritional status and intestinal function in rats undergoing partial gastrectomy, and the appropriate compatibility concentration of vitamin B6.

METHODS

Fifty-six male rats were randomly divided into seven groups (n = 8 per group): (I) Control, (II) BCAAs-enriched formula group (BCAA), (III) BCAA plus vitamin B6 (50 mg/L), (IV) BCAA plus vitamin B6 (100 mg/L), (V) BCAA plus vitamin B6 (200 mg/L), (VI) BCAA plus vitamin B6 (500 mg/L), and (VII) BCAA plus vitamin B6 (1000 mg/L). All animals were performed partial gastrectomy and placed a jugular vein catheter. During enteral nutrition, blood and urine samples were repeatedly collected. Gastrocnemius muscle and small intestine were also collected at the end of experiment.

RESULTS

The addition of vitamin B6 to BCAAs-enriched formula improved negative nitrogen balance after gastrectomy compared to the BCAAs-enriched formula group at POD1 (first postoperative day) and POD3 (third postoperative day), and 100 mg/L was an appropriate concentration of vitamin B6 to enhance the effects of BCAAs-enriched formula. The 3-methylhistidine/creatinine in BCAA plus vitamin B6 groups were significantly lower than that in the BCAA group at POD3. Moreover, BCAA plus vitamin B6 group significantly increased the cross-sectional area of the muscle fibers compared to the BCAA group. Transcriptome sequencing, GO and KEGG enhancement analysis also showed that BCAA plus vitamin B6 group showed muscle organ development and PI3K/AKT pathway enhancement compared to BCAA group. Moreover, AKT/mTOR/4EBP1 pathway was activated in BCAA plus vitamin B6 group. In addition, the results also showed that BCAA plus vitamin B6 decreased D-lactate, and exerted synergistic effects on intestinal morphology.

CONCLUSION

The addition of vitamin B6 to BCAAs-enriched formula could improve nitrogen balance, promote muscle protein synthesis through AKT/mTOR/4EBP1 pathway, and alleviate intestinal mucosa damage after partial gastrectomy in rats. Overall, the results from this pre-clinical study support the use of vitamin B6 as an ingredient to BCAAs-enriched formula, and 100 mg/L may be an optimal concentration for rats.

Cardiovascular risk of metabolically healthy obesity in two european populations: Prevention potential from a metabolomic study

BACKGROUND

A new definition of metabolically healthy obesity (MHO) has recently been proposed to stratify the heterogeneous mortality risk of obesity. Metabolomic profiling provides clues to metabolic alterations beyond clinical definition. We aimed to evaluate the association between MHO and cardiovascular events and assess its metabolomic pattern.

METHODS

This prospective study included Europeans from two population-based studies, the FLEMENGHO and the Hortega study. A total of 2339 participants with follow-up were analyzed, including 2218 with metabolomic profiling. Metabolic health was developed from the third National Health and Nutrition Examination Survey and the UK biobank cohorts and defined as systolic blood pressure < 130 mmHg, no antihypertensive drugs, waist-to-hip ratio < 0.95 for women or 1.03 for men, and the absence of diabetes. BMI categories included normal weight, overweight, and obesity (BMI < 25, 25-30, ≥ 30 kg/m²). Participants were classified into six subgroups according to BMI category and metabolic healthy status. Outcomes were fatal and nonfatal composited cardiovascular events.

RESULTS

Of 2339 participants, the mean age was 51 years, 1161 (49.6%) were women, 434 (18.6%) had obesity, 117 (5.0%) were classified as MHO, and both cohorts had similar characteristics. Over a median of 9.2-year (3.7-13.0) follow-up, 245 cardiovascular events occurred. Compared to those with metabolically healthy normal weight, individuals with metabolic unhealthy status had a higher risk of cardiovascular events, regardless of BMI category (adjusted HR: 3.30 [95% CI: 1.73-6.28] for normal weight, 2.50 [95% CI: 1.34-4.66] for overweight, and 3.42 [95% CI: 1.81-6.44] for obesity), whereas those with MHO were not at increased risk of cardiovascular events (HR: 1.11 [95% CI: 0.36-3.45]). Factor analysis identified a metabolomic factor mainly associated with glucose regulation, which was associated with cardiovascular events (HR: 1.22 [95% CI: 1.10-1.36]). Individuals with MHO tended to present a higher metabolomic factor score than those with metabolically healthy normal weight (0.175 vs. -0.057, P = 0.019), and the score was comparable to metabolically unhealthy obesity (0.175 vs. -0.080, P = 0.91).

CONCLUSIONS

Individuals with MHO may not present higher short-term cardiovascular risk but tend to have a metabolomic pattern associated with higher cardiovascular risk, emphasizing a need for early intervention.

Metabolomic profiling of glucose homeostasis in African Americans: the Insulin Resistance Atherosclerosis Family Study (IRAS-FS)

INTRODUCTION

African Americans are at increased risk for type 2 diabetes.

OBJECTIVES

This work aimed to examine metabolomic signature of glucose homeostasis in African Americans.

METHODS

We used an untargeted liquid chromatography-mass spectrometry metabolomic approach to comprehensively profile 727 plasma metabolites among 571 African Americans from the Insulin Resistance Atherosclerosis Family Study (IRAS-FS) and investigate the associations between these metabolites and both the dynamic (S_I, insulin sensitivity; AIR, acute insulin response; DI, disposition index; and S_G, glucose effectiveness) and basal (HOMA-IR and HOMA-B) measures of glucose homeostasis using univariate and regularized regression models. We also compared the results with our previous findings in the IRAS-FS Mexican Americans.

RESULTS

We confirmed increased plasma metabolite levels of branched-chain amino acids and their metabolic derivatives, 2-aminoadipate, 2-hydroxybutyrate, glutamate, arginine and its metabolic derivatives, carbohydrate metabolites, and medium- and long-chain fatty acids were associated with insulin resistance, while increased plasma metabolite levels in the glycine, serine and threonine metabolic pathway were associated with insulin sensitivity. We also observed a differential ancestral effect of glutamate on glucose homeostasis with significantly stronger effects observed in African Americans than those previously observed in Mexican Americans.

CONCLUSION

We extended the observations that metabolites are useful biomarkers in the identification of prediabetes in individuals at risk of type 2 diabetes in African Americans. We revealed, for the first time, differential ancestral effect of certain metabolites (i.e., glutamate) on glucose homeostasis traits. Our study highlights the need for additional comprehensive metabolomic studies in well-characterized multiethnic cohorts.

Branched-chain amino acid catabolism in muscle affects systemic BCAA levels but not insulin resistance

Elevated levels of plasma branched-chain amino acids (BCAAs) have been associated with insulin resistance and type 2 diabetes since the 1960s. Pharmacological activation of branched-chain α-ketoacid dehydrogenase (BCKDH), the rate-limiting enzyme of BCAA oxidation, lowers plasma BCAAs and improves insulin sensitivity. Here we show that modulation of BCKDH in skeletal muscle, but not liver, affects fasting plasma BCAAs in male mice. However, despite lowering BCAAs, increased BCAA oxidation in skeletal muscle does not improve insulin sensitivity. Our data indicate that skeletal muscle controls plasma BCAAs, that lowering fasting plasma BCAAs is insufficient to improve insulin sensitivity and that neither skeletal muscle nor liver account for the improved insulin sensitivity seen with pharmacological activation of BCKDH. These findings suggest potential concerted contributions of multiple tissues in the modulation of BCAA metabolism to alter insulin sensitivity.

Association of branched-chain amino acids with mortality-the Ludwigshafen Risk and Cardiovascular Health (LURIC) study

Branched-chain amino acids (BCAAs) are effectors of metabolic diseases, but their impact on mortality is largely unknown. We investigated the association of BCAA with risk factors and mortality in 2,236 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) study using linear and Cox regression. Adiponectin, hemoglobin, C-peptide, hemoglobin A_1c, and homoarginine showed the strongest association with BCAA concentration (all p < 0.001). During a median follow-up of 10.5 years, 715 participants died, including 450 cardiovascular-related deaths. BCAA concentrations were inversely associated with the risk of all-cause and cardiovascular mortality (HR [95% CI] per 1-SD increase in log-BCAA: 0.75 [0.69-0.82] and 0.72 [0.65-0.80], respectively) after adjustment for potential confounders. BCAAs are directly associated with metabolic risk but inversely with mortality in persons with intermediate-to-high cardiovascular risk. Further studies are warranted to evaluate the diagnostic and therapeutic utility of BCAA in the context of cardiovascular diseases.

Gut Microbial Genes and Metabolism for Methionine and Branched-Chain Amino Acids in Diabetic Nephropathy

Diabetic mellitus nephropathy (DMN) is a serious complication of diabetes and a major health concern. Although the pathophysiology of diabetes mellitus (DM) leading to DMN is uncertain, recent evidence suggests the involvement of the gut microbiome. This study aimed to determine the relationships among gut microbial species, genes, and metabolites in DMN through an integrated clinical, taxonomic, genomic, and metabolomic analysis. Whole-metagenome shotgun sequencing and nuclear magnetic resonance metabolomic analyses were performed on stool samples from 15 patients with DMN and 22 healthy controls. Six bacterial species were identified to be significantly elevated in the DMN patients after adjusting for age, sex, body mass index, and estimated glomerular filtration rate (eGFR). Multivariate analysis found 216 microbial genes and 6 metabolites (higher valine, isoleucine, methionine, valerate, and phenylacetate levels in the DMN group and higher acetate levels in the control group) that were differentially present between the DMN and control groups. Integrated analysis of all of these parameters and clinical data using the random-forest model showed that methionine and branched-chain amino acids (BCAAs) were among the most significant features, next to the eGFR and proteinuria, in differentiating the DMN group from the control group. Metabolic pathway gene analysis of BCAAs and methionine also revealed that many genes involved in the biosynthesis of these metabolites were elevated in the six species that were more abundant in the DMN group. The suggested correlation among taxonomic, genetic, and metabolic features of the gut microbiome would expand our understanding of gut microbial involvement in the pathogenesis of DMN and may provide potential therapeutic targets for DMN. IMPORTANCE Whole metagenomic sequencing uncovered specific members of the gut microbiota associated with DMN. The gene families derived from the discovered species are involved in the metabolic pathways of methionine and branched-chain amino acids. Metabolomic analysis using stool samples showed increased methionine and branched-chain amino acids in DMN. These integrative omics results provide evidence of the gut microbiota-associated pathophysiology of DMN, which can be further studied for disease-modulating effects via prebiotics or probiotics.

Dietary Strawberries Improve Serum Metabolites of Cardiometabolic Risks in Adults with Features of the Metabolic Syndrome in a Randomized Controlled Crossover Trial

Dietary strawberries have been shown to improve cardiometabolic risks in multiple clinical trials. However, no studies have reported effects on serum metabolomic profiles that may identify the target pathways affected by strawberries as underlying mechanisms. We conducted a 14-week randomized, controlled crossover study in which participants with features of metabolic syndrome were assigned to one of the three arms for four weeks separated by a one-week washout period: control powder, 1 serving (low dose: 13 g strawberry powder/day), or 2.5 servings (high dose: 32 g strawberry powder/day). Blood samples, anthropometric measures, blood pressure, and dietary and physical activity data were collected at baseline and at the end of each four-week phase of intervention. Serum samples were analyzed for primary metabolites and complex lipids using different mass spectrometry methods. Mixed-model ANOVA was used to examine differences in the targeted metabolites between treatment phases, and LASSO logistic regression was used to examine differences in the untargeted metabolites at end of the strawberry intervention vs. the baseline. The findings revealed significant differences in the serum branched-chain amino acids valine and leucine following strawberry intervention (high dose) compared with the low-dose and control phases. Untargeted metabolomic profiles revealed several metabolites, including serum phosphate, benzoic acid, and hydroxyphenyl propionic acid, that represented improved energy-metabolism pathways, compliance measures, and microbial metabolism of strawberry polyphenols, respectively. Thus, dietary supplementation of strawberries significantly improves the serum metabolic profiles of cardiometabolic risks in adults.

Role of Impaired Glycolysis in Perturbations of Amino Acid Metabolism in Diabetes Mellitus

The most frequent alterations in plasma amino acid concentrations in type 1 and type 2 diabetes are decreased L-serine and increased branched-chain amino acid (BCAA; valine, leucine, and isoleucine) levels. The likely cause of L-serine deficiency is decreased synthesis of 3-phosphoglycerate, the main endogenous precursor of L-serine, due to impaired glycolysis. The BCAA levels increase due to decreased supply of pyruvate and oxaloacetate from glycolysis, enhanced supply of NADH + H⁺ from beta-oxidation, and subsequent decrease in the flux through the citric acid cycle in muscles. These alterations decrease the supply of α-ketoglutarate for BCAA transamination and the activity of branched-chain keto acid dehydrogenase, the rate-limiting enzyme in BCAA catabolism. L-serine deficiency contributes to decreased synthesis of phospholipids and increased synthesis of deoxysphinganines, which play a role in diabetic neuropathy, impaired homocysteine disposal, and glycine deficiency. Enhanced BCAA levels contribute to increased levels of aromatic amino acids (phenylalanine, tyrosine, and tryptophan), insulin resistance, and accumulation of various metabolites, whose influence on diabetes progression is not clear. It is concluded that amino acid concentrations should be monitored in patients with diabetes, and systematic investigation is needed to examine the effects of L-serine and glycine supplementation on diabetes progression when these amino acids are decreased.