Plasma Branched-chain Amino Acids Research Articles

Targeted Quantitative Plasma Metabolomics Identifies Metabolite Signatures that Distinguish Heart Failure with Reduced and Preserved Ejection Fraction.

Two general phenotypes of heart failure (HF) are recognized: HF with reduced ejection fraction (HFrEF) and with preserved EF (HFpEF). To develop HF disease phenotype-specific approaches to define and guide treatment, distinguishing biomarkers are needed. The goal of this study was to utilize quantitative metabolomics on a large, diverse population to replicate and extend existing knowledge of the plasma metabolic signatures in human HF. Quantitative, targeted LC/MS plasma metabolomics was conducted on 787 samples collected by the Penn Medicine BioBank from subjects with HFrEF (n=219), HFpEF (n=357), and matched non-failing Controls (n=211). A total of 90 metabolites were analyzed, comprising 28 amino acids, 8 organic acids, and 54 acylcarnitines. 733 of these samples were also processed via an OLINK protein panel for proteomic profiling. Consistent with previous studies, unsaturated forms of medium/long chain acylcarnitines were elevated in the HFrEF group to a greater extent than the HFpEF group compared to Controls. A number of amino acid derivatives, including 1- and 3-methylhistidine, homocitrulline, and symmetric (SDMA) and asymmetric (ADMA) dimethylarginine were elevated in HF, with ADMA elevated uniquely in HFpEF. Plasma branched-chain amino acids (BCAA) were not different across the groups; however, short-chain acylcarnitine species indicative of BCAA catabolism were significantly elevated in both HF groups. The ketone body 3-hydroxybutyrate (3-HBA) and its metabolite C4-OH carnitine were uniquely elevated in the HFrEF group. Linear regression models demonstrated a significant correlation between plasma 3-HBA and NT-proBNP in both forms of HF, stronger in HFrEF. These results identify plasma signatures that are shared as well as potentially distinguish between HFrEF and HFpEF. Metabolite markers for ketogenic metabolic reprogramming in extra-cardiac tissues were identified as unique signatures in the HFrEF group, possibly related to the lipolytic action of increased levels of BNP. Future studies will be necessary to further validate these metabolites as HF biosignatures that may guide phenotype-specific therapeutics and provide insight into the systemic metabolic responses to HFpEF and HFrEF.

Sex differences in the association between plasma branched-chain amino acids and risk of ischemic stroke: A nested case-control study from China

ObjectivesThe aim of this study was to investigate the prospective associations between plasma branched-chain amino acids (BCAAs) and the risk of ischemic stroke in men and women. MethodsWe conducted a nested case-control study within a community-based cohort in China. The cohort consisted of 15,926 participants in 2013-2018. A total of 321 ischemic stroke cases were identified during the follow up and individually matched with 321 controls by date of birth (±1 year) and sex. Females accounted for 55.8% (n = 358, 179 cases vs 179 controls) of the study population. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the association between plasma BCAAs and ischemic stroke risk by conditional logistic regression. ResultsElevated plasma isoleucine was associated with a higher risk of ischemic stroke in women. The OR for the highest compared to the lowest quartile was 2.22 (95% CI: 1.11-4.44, P trend = 0.005) after adjustment for body mass index, education attainment, smoking, hypertension, renal function, menopause and physical activity. A similar association was found for total BCAAs (adjusted OR = 2.03, 95% CI: 1.05-3.95, P trend = 0.04). In contrast, no significant association of plasma BCAAs with ischemic stroke risk was observed in men. ConclusionsPlasma isoleucine and total BCAAs were significantly associated with ischemic stroke risk in women, but not in men, highlighting sex differences in BCAAs metabolism and stroke pathogenesis.

Adverse plasma branched-chain amino acid profile mirrors fatty muscle degeneration in diabetic heart failure patients.

Elevated plasma branched-chain amino acids (BCAAs) are tightly linked to incident diabetes and its complications, while lower BCAAs are associated with adverse outcomes in the elderly and heart failure (HF) patients. The interplay between body compositions and plasma BCAAs, especially under the influence of co-morbid diabetes in HF patients, is not well understood. Here, we examined the impact of diabetes on the prognostic value of plasma BCAA and its association with body compositions in HF patients. We retrospectively examined 301 HF patients (70±15years old; 59% male), among which 36% had diabetes. Blood samples for plasma BCAA measurements were collected in a fasting state after stabilization of HF and analysed using ultraperformance liquid chromatography. A dual-energy X-ray absorptiometry scan assessed regional body compositions, and muscle wasting was defined as appendicular skeletal muscle mass index (ASMI)<7.00 and <5.40kg/m2 for males and females, respectively, according to the criteria of the Asian Working Group for Sarcopenia. Although analyses of covariance revealed that plasma BCAAs were significantly higher in diabetic patients, low valine (<222.1nmol/mL) similarly predicted adverse events defined by HF hospitalization, lethal arrhythmia, or all-cause death in both diabetic and non-diabetic patients independently of age, sex, and NT-proBNP (adjusted hazard ratio [HR] 3.1, 95% confidence interval [CI] of 1.1-8.6 and adjusted HR 2.67, 95% CI 1.1-6.5, respectively; P for interaction 0.88). In multivariate linear regression analyses comprising age, sex, and regional body compositions as explanatory variables, plasma BCAAs were positively correlated with visceral adipose tissue area in non-diabetic patients (standardized β coefficients [β]=0.44, P<0.001). In contrast, in diabetic patients, plasma BCAAs were correlated positively with ASMI (β=0.49, P=0.001) and negatively with appendicular fat mass index (AFMI; β=-0.42, P=0.004). Co-morbid diabetes was independently associated with muscle wasting (adjusted odds ratio 2.1, 95% CI 1.1-4.0) and significantly higher plasma 3-methylhistidine level, a marker of myofibrillar degradation. In diabetic patients, ASMI uniquely showed a J-shaped relationship with AFMI, and in a subgroup of HF patients with muscle wasting, diabetic patients showed 12% higher AFMI than non-diabetic patients despite comparable ASMI reductions. Despite higher plasma BCAA levels in HF patients with diabetes, the prognostic value of low valine remained consistent regardless of diabetes status. However, low BCAAs were distinctly associated with fatty muscle degeneration in the extremities in diabetic patients, suggesting the importance of targeted interventions to prevent such tissue remodelling in this population.

Branched-chain amino acid levels are inversely associated with incident and prevalent chronic kidney disease in people with type 2 diabetes.

To investigate the association of plasma metabolites with incident and prevalent chronic kidney disease (CKD) in people with type 2 diabetes and establish whether this association is causal. The Hoorn Diabetes Care System cohort is a large prospective cohort consisting of individuals with type 2 diabetes from the northwest part of the Netherlands. In this cohort we assessed the association of baseline plasma levels of 172 metabolites with incident (Ntotal = 462/Ncase = 81) and prevalent (Ntotal = 1247/Ncase = 120) CKD using logistic regression. Additionally, replication in the UK Biobank, body mass index (BMI) mediation and causality of the association with Mendelian randomization was performed. Elevated levels of total and individual branched-chain amino acids (BCAAs)-valine, leucine and isoleucine-were associated with an increased risk of incident CKD, but with reduced odds of prevalent CKD, where BMI was identified as an effect modifier. The observed inverse effects were replicated in the UK Biobank. Mendelian randomization analysis did not provide evidence for a causal relationship between BCAAs and prevalent CKD. Our study shows the intricate relationship between plasma BCAA levels and CKD in individuals with type 2 diabetes. While an association exists, its manifestation varies based on disease status and BMI, with no definitive evidence supporting a causal link between BCAAs and prevalent CKD.

PNPLA3 Genotype and Dietary Fat Modify Concentrations of Plasma and Fecal Short Chain Fatty Acids and Plasma Branched-Chain Amino Acids.

The GG genotype of the Patatin-like phosphatase domain-containing 3 (PNPLA3), dietary fat, short-chain fatty acids (SCFA) and branched-chain amino acids (BCAA) are linked with non-alcoholic fatty liver disease. We studied the impact of the quality of dietary fat on plasma (p) and fecal (f) SCFA and p-BCAA in men homozygous for the PNPLA3 rs738409 variant (I148M). Eighty-eight randomly assigned men (age 67.8 ± 4.3 years, body mass index 27.1 ± 2.5 kg/m2) participated in a 12-week diet intervention. The recommended diet (RD) group followed the National and Nordic nutrition recommendations for fat intake. The average diet (AD) group followed the average fat intake in Finland. The intervention resulted in a decrease in total p-SCFAs and iso-butyric acid in the RD group (p = 0.041 and p = 0.002). Valeric acid (p-VA) increased in participants with the GG genotype regardless of the diet (RD, 3.6 ± 0.6 to 7.0 ± 0.6 µmol/g, p = 0.005 and AD, 3.8 ± 0.3 to 9.7 ± 8.5 µmol/g, p = 0.015). Also, genotype relation to p-VA was seen statistically significantly in the RD group (CC: 3.7 ± 0.4 to 4.2 ± 1.7 µmol/g and GG: 3.6 ± 0.6 to 7.0 ± 0.6 µmol/g, p = 0.0026 for time and p = 0.004 for time and genotype). P-VA, unlike any other SCFA, correlated positively with plasma gamma-glutamyl transferase (r = 0.240, p = 0.025). Total p-BCAAs concentration changed in the AD group comparing PNPLA3 CC and GG genotypes (CC: 612 ± 184 to 532 ± 149 µmol/g and GG: 587 ± 182 to 590 ± 130 µmol/g, p = 0.015 for time). Valine decreased in the RD group (p = 0.009), and leucine decreased in the AD group (p = 0.043). RD decreased total fecal SCFA, acetic acid (f-AA), and butyric acid (f-BA) in those with CC genotype (p = 0.006, 0.013 and 0.005, respectively). Our results suggest that the PNPLA3 genotype modifies the effect of dietary fat modification for p-VA, total f-SCFA, f-AA and f-BA, and total p-BCAA.

The effects of endurance physical exercise with fat-free milk intake as a therapy for metabolic syndrome and/or sarcopenia

Background: Nutrition and exercise are important factors for addressing metabolic syndrome and sarcopenia as they are related to insulin secretion. Proteins, particularly branched-chain amino acids (BCAAs), have insulinotropic effects, while exercise reduces insulin secretion. It is thus important to investigate the effects of protein intake and exercise alone and in combination to determine suitable dietary and exercise therapies for treating metabolic syndrome and sarcopenia. Methods: Eight healthy young adult female volunteers participated in a crossover trial consisting of two 5-day experiments. Days 1 and 2 comprised a body-weight-maintained adjustment period during which the participants consumed control diets (energy, 2,010 kcal; protein, 51.9 g). Days 3 to 5 comprised the treatment period during which the participants consumed experimental diets (energy, 2,010 kcal; protein 82.3 g) containing 402 kcal of fat-free milk, and either performed only normal daily activities (non-Ex) or performed normal daily activities and exercised on a bicycle with an ergometer at a target intensity of about 50% of the maximal oxygen intake, expending 402 kcal of additional energy (Ex). Total urine samples were collected during the daytime (6:45 to 18:45) and nighttime (18:45 to 6:45 the next morning). Fasting blood samples were collected early in the morning before and after the treatment period. Results: Plasma valine, leucine, and BCAA levels were significantly elevated after both the non-Ex and Ex periods. Serum insulin levels were significantly elevated only after the non-Ex period. Urinary C-peptide immunoreactivity excretion levels increased significantly during the non-Ex period, but they decreased significantly during the Ex period. After the Ex period, the serum triglyceride and remnant lipoprotein-cholesterol (RLP-C) levels were significantly decreased. Homeostatic model assessment for insulin resistance (HOMA-IR) and atherosclerosis index (AI) values were slightly, yet significantly, increased after the non-Ex period, but were unchanged after the Ex period. The degree of change (Δ) in the RLP-C level significantly and positively correlated with the Δ HOMA-IR and Δ AI.

Sex Differences in Branched-chain Amino Acid and Tryptophan Metabolism and Pathogenesis of Youth-onset Type 2 Diabetes.

Insulin resistance is associated with elevations in plasma branched-chain amino acids (BCAAs). BCAAs compete with aromatic amino acids including tryptophan for uptake into β cells. To explore relationships between BCAAs and tryptophan metabolism, adiposity, and glucose tolerance, we compared urine metabolites in overweight/obese youth with type 2 diabetes (T2D) with those in nondiabetic overweight/obese and lean youth. Metabolites were measured in 24-hour and first-morning urine samples of 56 nondiabetic adolescents with overweight/obesity, 42 adolescents with T2D, and 43 lean controls, aged 12 to 21 years. Group differences were assessed by Kruskal Wallis or ANOVA. Groups were comparable for age, pubertal status, and ethnicity. Youth with T2D were predominantly female and had highest percent body fat. BCAAs, branched-chain ketoacids (BCKAs), tryptophan, and kynurenine were higher in urine of subjects with T2D. There were no differences between lean controls and nondiabetic youth with overweight/obesity. T2D was associated with diversion of tryptophan from the serotonin to the kynurenine pathway, with higher urinary kynurenine/serotonin ratio and lower serotonin/tryptophan and 5-HIAA/kynurenine ratios. Urinary BCAAs, BCKAs, tryptophan, and ratios reflecting diversion to the kynurenine pathway correlated positively with metrics of body fat and hemoglobin A1c. Increases in these metabolites in the obese T2D group were more pronounced and statistically significant only in adolescent girls. Increases in urinary BCAAs and BCKAs in adolescent females with T2D are accompanied by diversion of tryptophan metabolism from the serotonin to the kynurenine pathway. These adaptations associate with higher risks of T2D in obese adolescent females than adolescent males.

Mediterranean versus Western diet and the gut‐brain axis: Diet‐induced links between gut Oscillospira abundance, plasma branched‐chain amino acid concentrations and insulin resistance, and change in white matter volumes in nonhuman primates

AbstractBackgroundWestern vs. Mediterranean patterned diets have been associated with divergent effects on neurodegenerative diseases including Alzheimer’s Disease (AD). Such effects may be mediated through the gut microbiome, although the exact mechanisms linking diet, microbiome, and brain outcomes remain unclear. Oscillospira, a genus of gut‐dwelling bacteria, appears to be a good candidate which may help explain the mechanistic underpinnings of this relationship. Previous studies have shown associations between Oscillospira abundance, blood biomarkers, and brain physiology in rodents, and patients with neurodegenerative diseases including AD exhibit decreased gut Oscillospira abundances. Notably, Oscillospira may alter myelination by modifying branched‐chain amino acid (BCAA) concentrations in blood and preventing or minimizing insulin resistance.MethodIn the present study, we test a mechanistic role for Oscillospira on white matter volumes in cynomolgus monkeys (Macaca fascicularis) experimentally fed either a Mediterranean or Western‐type diet. We analyzed associations between gut Oscillospira abundances, plasma BCAA concentrations (i.e., leucine, isoleucine, and valine), plasma insulin, beta‐amyloid (Aβ) 42 to 40 ratio in cerebrospinal fluid (CSF), and magnetic resonance imaging‐derived white matter volumes.ResultWe found that Oscillospira abundance was significantly higher in the Mediterranean diet cohort than in the Western cohort (β = 0.258, SE = 0.084, p = 0.004). Oscillospira abundance was significantly negatively associated with plasma leucine (β = ‐0.169, SE = 0.059, p = 0.007) and valine concentrations (β = ‐0.206, SE = 0.069, p = 0.005); a similar, non‐significant (p = 0.066) trend was observed for isoleucine. Similarly, Oscillospira abundance was negatively associated with insulin area under the curve (AUC) at 26 months (β = ‐0.282, SE = 0.125, p = 0.031) and change in insulin AUC from baseline to 26 months (β = ‐14.6, SE = 6.97, p = 0.044), suggesting better insulin sensitivity in individuals with higher Oscillospira abundance. Oscillospira abundance was also positively associated with CSF Aβ42:40 ratio (β = 0.013, SE = 0.004, p = 0.007). Furthermore, the percent change in white matter volume over the study period was positively associated with Oscillospira abundance (β = 2.45, SE = 0.915, p = 0.012) and negatively associated with leucine (β = ‐2.39, SE = 0.920, p = 0.014), isoleucine (β = ‐2.67, SE = 0.895, p = 0.005), and valine concentrations (β = ‐2.28, SE = 0.929, p = 0.020) as well as change in insulin AUC (β = ‐2.04, SE = 0.947, p = 0.039).ConclusionThese results suggest that diet impacts the central nervous system by altering gut microbiome composition and highlight the complexity of relationships between BCAAs and brain health.

Amino acid profile in overweight and obese prepubertal children - can simple biochemical tests help in the early prevention of associated comorbidities?

It is accepted that plasma branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) are closely related to metabolic risk. Arterial hypertension, metabolic syndrome, endothelial dysfunction, inflammation, and metabolic dysfunction-associated fatty liver disease (MAFLD) are frequently seen in obese patients. Many attempts have been made to find biochemical indicators for the early detection of metabolic complications in children. It is not known if different amino acid profiles and BCAA and AA concentrations in overweight and obese children correlate with chemerin, proinflammatory, and simple biochemical markers. Thus, the study aimed to find out the early markers of cardiovascular disease and MAFLD in overweight and obese children. The study included 20 overweight and obese children (M/F 12/8; mean age 7.7 ± 2.3 years; BMI 26.8 ± 5.0 kg/m2) and 12 non-obese children (control group) (M/F 4/8; mean age 6.5 ± 2.2 years; BMI 14.8 ± 1.5 kg/m2). The following plasma amino acids were measured: aspartic acid, glutamic acid, serine, asparagine, glycine, glutamine, taurine, histidine, citrulline, threonine, alanine, arginine, proline, tyrosine, methionine, valine, isoleucine, leucine, phenylalanine, tryptophan, ornithine, and lysine. Chemerin, high-sensitivity C-reactive protein (hs-CRP), interleukin-6 (IL-6), and basic biochemistry parameters were measured. The mean plasma levels of leucine, isoleucine, valine, phenylalanine, tyrosine, glutamic acid, and alanine were significantly higher in overweight and obese children than in the control group (p<0.03-p<0.0004). Conversely, the mean values of serine, asparagine, glutamine, and citrulline were significantly lower in overweight and obese children than in the control group (p<0.03-p<0.0007). Isoleucine, leucine, valine (BCAAs) tyrosine, and phenylalanine (AAAs) levels showed a positive correlation with uric acid, ALT, hs-CRP, and chemerin (r=0.80-0.36; p<0.05-p<0.00001), but not with IL-6. The mean values of glucose, IL-6, hs-CRP, chemerin, uric acid, and ALT were significantly higher in overweight and obese children than in the control group (p<0.03-p<0.00002). In contrast, the lipid profile did not differ between groups. An abnormal amino acid profile in overweight and obese pre-pubertal children, accompanied by elevated ALT and UA observed in the studied cohort, may suggest early metabolic disturbances that can potentially lead to metabolic syndrome, or MAFLD, and increased cardiovascular risk.

Association of plasma branched-chain amino acid with multiple cancers: A mendelian randomization analysis

Studies have suggested a possible relevance between branched-chain amino acid (BCAA) catabolic enzymes and cancers. However, few studies have explored the variation in circulating concentrations of BCAAs. Our study used bi-directional, two-sample Mendelian randomization (MR) analysis for predicting the causality between the BCAA levels and 9 types of cancers. The largest genome-wide association studies (GWAS) provided data for total BCAAs, valine, leucine, and isoleucine from the UK Biobank. Data on multiple cancer endpoints were collected from various sources, such as the International Lung Cancer Consortium (ILCCO), the Pancreatic Cancer Cohort Consortium 1 (PanScan1), the Breast Cancer Association Consortium (BCAC), the FinnGen Biobank, and the Ovarian Cancer National Alliance (OCAC). The mainly analysis method was the inverse-variance-weighted (IVW). For assessing horizontal pleiotropy, the researchers performed MR-Egger regression and MR-PRESSO global test. Finally, the Cochran's Q test served for evaluating the heterogeneity. Circulating total BCAAs levels (OR 1.708, 95%CI 1.168, 2.498; p=0.006), valine levels (OR 1.747, 95%CI 1.217, 2.402; p<0.001), leucine levels (OR 1.923, 95%CI 1.279, 2.890; p=0.002) as well as isoleucine levels (OR 1.898, 95%CI 1.164, 3.094; p=0.010) positively correlated with the squamous cell lung cancer risk. Nevertheless, no compelling evidence was found to support a causal link between BCAAs and any other examined cancers. Increased circulating total-BCAAs levels, leucine levels, isoleucine levels and valine levels had higher hazard of squamous cell lung cancer. No such associations were found for BCAAs with other cancers.

Biochemical characterization of patients with dihydrolipoamide dehydrogenase deficiency.

Dihydrolipoamide dehydrogenase (DLD; E3) oxidizes lipoic acid. Restoring the oxidized state allows lipoic acid to act as a necessary electron sink for the four mitochondrial keto-acid dehydrogenases: pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase, branched-chain α-keto-acid dehydrogenase, and 2-oxoadipate dehydrogenase. DLD deficiency (DLDD) is caused by biallelic pathogenic variants in DLD. Three major forms have been described: encephalopathic, hepatic, and myopathic, although DLDD patients exhibit overlapping phenotypes. Hyperlactatemia, hyperexcretion of tricarboxylic acid cycle (TCA) metabolites and branched-chain keto acids, increased plasma branched-chain amino acids and allo-isoleucine are intermittent metabolic abnormalities reported in patients with DLDD. However, the diagnostic performance of these metabolites has never been studied. Therefore, we sought to systematically evaluate the diagnostic utility of these biomarkers for DLDD. We retrospectively analyzed the results of biochemical testing of six unrelated DLDD patients, including values obtained during both well visits and acute decompensation episodes. Elevation of branched-chain amino acid concentrations was not consistently observed. We found that five of six patients in our cohort had a maximum lifetime value of allo-isoleucine of 6 μmol/L, showing that alloisoleucine elevations even during illness may be subtle. Urine organic acid analysis (UOA) during acute decompensation episodes was abnormal in all cases; however, the pattern of abnormalities had high intersubject variability. No single biomarker was universally present, even in patients experiencing metabolic decompensation. We also observed novel biochemical associations: three patients had hyperexcretion of TCA cycle metabolites during crisis; in two patients, 2-ketoadipic and 2-hydroxyadipic acids, by products of lysine degradation, were detected. We propose that these result from 2-oxoadipate dehydrogenase deficiency, an underappreciated biochemical abnormality in DLD. Given the diversity of biochemical profiles among the patients with DLDD, we conclude that accurate biochemical diagnosis relies on a high index of suspicion and multipronged biochemical analysis, including both plasma amino acid and urine organic acid quantitation during decompensation. Biochemical diagnosis during the well state is challenging. We emphasize the critical importance of multiple simultaneous biochemical tests for diagnosis and monitoring of DLDD. We also highlight the under-recognized role of DLD in the lysine degradation pathway. Larger cohorts of patients are needed to establish a correlation between the biochemical pattern and clinical outcomes, as well as a genotype-phenotype correlation.

Plasma branched-chain amino acid concentrations in individuals without cardiovascular diseases versus patients diagnosed with hypertension and coronary artery disease

Aim. Branched-chain amino acids (BCAAs) have been postulated as potential indicators of cardiovascular risk. The objective of this study was to explore the relationship between plasma BCAAs and different stages of cardiovascular disorders.Material and methods. In our cross-sectional study, plasma BCAAs (valine, leucine and isoleucine) in individuals without cardiovascular diseases (CVDs) (nonCVD group, total n=27, with n=16 healthy, but with metabolic disorders) were compared to patients diagnosed with CVDs [CVD group, total n=109, being n=61 hypertension (n=31 with signs of beginning of myocardial remodeling) and n=48 patients with coronary artery disease (CAD)].Results. The plasma concentration of BCAAs was significantly higher in the group of patients with cardiovascular disease compared with the healthy group (p&lt;0.05 for all amino acids tested): valine concentration was 238.7 [219.6; 267.0] μM in the non-CVD group and 261.2 [233.8; 298.7] μM in the CVD group; leucine concentration was 134.8 [122.4; 153.2] μM and 146.8 [129.0; 166.6] μM, respectively; and isoleucine 72.7 [65.3; 84.4] μM and 81.7 [68.0; 96.2] μM, respectively. Leucine and isoleucine concentration levels were minimal in the healthy participant subgroup and maximal in the IBS patient subgroup. No statistically significant differences in BCAAs concentrations were found in the subgroups without CAD. Significant increases in concentrations were observed in the subgroups of patients with CAD as follows: valine concentration was 256.3 [219.0; 297.9] μM in hypertension group and 261.7 [236.5; 307.5] μM in CAD group; leucine concentration was 141.8 [123.5; 166.6] μM and 154.1 [134.7; 172.7] μM, respectively, and isoleucine 72.8 [65.7; 94.0] μM and 85.7 [74.9; 101.7] μM, respectively. BCAAs profiles in all participants with metabolic disorders had “good” diagnostic accuracy with area under the receiver operating characteristics curve being 0.72, 0.70 and 0.70 for valine, leucine and isoleucine, respectively.Conclusion. BCAAs concentrations are elevated with higher severity of the cardiovascular disorder and exhibit potential as early independent indicators of coronary artery disease.

Sex-Specific Correlation Analysis of Branched-Chain Amino Acids in Dietary Intakes and Plasma among Chinese Adults

BackgroundPrevious findings about the influence of dietary intakes of the branched-chain amino acid (BCAA) on their plasma concentrations have been limited and inconsistent, and evidence from the Chinese population was lacking. ObjectivesThis study aimed to investigate the diet-plasma BCAA correlations in Chinese male and female adults. MethodsThis cross-sectional study was based on a nested case-control study within 2 prospective population-based cohorts in Shanghai, China. Diet information was collected by the food frequency questionnaires. Plasma BCAA concentrations were measured by ultraperformance liquid chromatography coupled with tandem mass spectrometry. Spearman correlations and linear regression models were conducted to examine the relationships between dietary BCAA intakes and plasma BCAA. The multivariable model was adjusted for age at the interview, total energy intake, time of blood collection from last meal, dietary patterns, body mass index (in kg/m2), type 2 diabetes, and physical activity. ResultsA total of 322 males (median age of 57.0 y) and 187 females (median age of 60.0 y) were included in this cross-sectional study. The geometric means of dietary intake of leucine, isoleucine, valine, and BCAA were 4937.7, 3029.6, 3268.5, and 11237.4 mg/d in males, and 4125.7, 2567.8, 2754.3, and 9449.4 mg/d in females. The geometric means of plasma concentrations of leucine, isoleucine, valine, and BCAA were 181.9, 65.0, 219.8, and 469.4 μM/L in males and 161.6, 61.1, 206.5, and 431.6 μM/L in females. Only leucine (r = 0.1660, P = 0.0028) and total BCAA (r = 0.1348, P = 0.0155) in males exhibited weak positive correlation coefficients. After adjustment for the covariates, leucine, isoleucine, valine, and total BCAA in dietary intakes and plasma were not correlated in both males and females. ConclusionsIn Chinese male and female adults, dietary intakes are not major determinants of plasma concentrations of BCAA, and plasma concentrations might not be reflected by usual dietary intakes of BCAA.

Dietary weight loss-induced improvements in metabolic function are enhanced by exercise in people with obesity and prediabetes.

The additional therapeutic effects of regular exercise during a dietary weight loss program in people with obesity and prediabetes are unclear. Here, we show that whole-body (primarily muscle) insulin sensitivity (primary outcome) was 2-fold greater (P = 0.006) after 10% weight loss induced by calorie restriction plus exercise training (Diet+EX; n = 8, 6 women) than 10% weight loss induced by calorie restriction alone (Diet-ONLY; n = 8, 4 women) in participants in two concurrent studies. The greater improvement in insulin sensitivity was accompanied by increased muscle expression of genes involved in mitochondrial biogenesis, energy metabolism and angiogenesis (secondary outcomes) in the Diet+EX group. There were no differences between groups in plasma branched-chain amino acids or markers of inflammation, and both interventions caused similar changes in the gut microbiome. Few adverse events were reported. These results demonstrate that regular exercise during a diet-induced weight loss program has profound additional metabolic benefits in people with obesity and prediabetes.Trial Registration: ClinicalTrials.gov (NCT02706262 and NCT02706288).

Amino acid homeostasis is a target of metformin therapy

ObjectiveUnexplained changes in regulation of branched chain amino acids (BCAA) during diabetes therapy with metformin have been known for years. Here we have investigated mechanisms underlying this effect. MethodsWe used cellular approaches, including single gene/protein measurements, as well as systems-level proteomics. Findings were then cross-validated with electronic health records and other data from human material. ResultsIn cell studies, we observed diminished uptake/incorporation of amino acids following metformin treatment of liver cells and cardiac myocytes. Supplementation of media with amino acids attenuated known effects of the drug, including on glucose production, providing a possible explanation for discrepancies between effective doses in vivo and in vitro observed in most studies. Data-Independent Acquisition proteomics identified that SNAT2, which mediates tertiary control of BCAA uptake, was the most strongly suppressed amino acid transporter in liver cells following metformin treatment. Other transporters were affected to a lesser extent. In humans, metformin attenuated increased risk of left ventricular hypertrophy due to the AA allele of KLF15, which is an inducer of BCAA catabolism. In plasma from a double-blind placebo-controlled trial in nondiabetic heart failure (trial registration: NCT00473876), metformin caused selective accumulation of plasma BCAA and glutamine, consistent with the effects in cells. ConclusionsMetformin restricts tertiary control of BCAA cellular uptake. We conclude that modulation of amino acid homeostasis contributes to therapeutic actions of the drug.

Loss of BCAA catabolism enhances Rab1A-mTORC1 signaling activity and promotes tumor proliferation in NSCLC

BackgroundNon-small cell lung cancer (NSCLC) is a leading cause of cancer death. Branched-chain amino acid (BCAA) homeostasis is important for normal physiological metabolism. Branched-chain keto acid dehydrogenase kinase (BCKDK) is a rate-limiting enzyme involved in BCAA degradation. BCAA metabolism has been highlighted in human cancers. The aberrant activation of mTORC1 has been implicated in tumor progression. Rab1A is a small GTPase, an activator of mTORC1, and an oncogene. This study aimed to reveal the specific role of BCKDK-BCAA-Rab1A-mTORC1 signaling in NSCLC. MethodsWe analyzed a cohort of 79 patients with NSCLC and 79 healthy controls. Plasma BCAA assays, immunohistochemistry, and network and pathway analyses were performed. The stable cell lines BCKDK-KD, BCKDK-OV A549, and H1299 were constructed. BCKDK, Rab1A, p-S6 and S6 were detected using western blotting to explore their molecular mechanisms of action in NSCLC. The effects of BCAA and BCKDK on the apoptosis and proliferation of H1299 cells were detected by cell function assays. ResultsWe demonstrated that NSCLC was primarily involved in BCAA degradation. Therefore, combining BCAA, CEA, and Cyfra21-1 is clinically useful for treating NSCLC. We observed a significant increase in BCAA levels, downregulation of BCKDHA expression, and upregulation of BCKDK expression in NSCLC cells. BCKDK promotes proliferation and inhibits apoptosis in NSCLC cells, and we observed that BCKDK affected Rab1A and p-S6 in A549 and H1299 cells via BCAA modulation. Leucine affected Rab1A and p-S6 in A549 and H1299 cells and affected the apoptosis rate of H1299 cells.In conclusion, BCKDK enhances Rab1A-mTORC1 signaling and promotes tumor proliferation by suppressing BCAA catabolism in NSCLC, suggesting a new biomarker for the early diagnosis and identification of metabolism-based targeted approaches for patients with NSCLC.

Branched Chain Amino Acids Are Associated with Physical Performance in Patients with End-Stage Liver Disease.

Decreased circulating branched chain amino acids (BCAA) represent a prominent change in amino acid profiles in patients with end-stage liver disease (ESLD). These alterations are considered to contribute to sarcopenia and hepatic encephalopathy and may relate to poor prognosis. Here, we cross-sectionally analyzed the association between plasma BCAA levels and the severity of ESLD and muscle function in participants of the liver transplant subgroup of TransplantLines, enrolled between January 2017 and January 2020. Plasma BCAA levels were measured by nuclear magnetic resonance spectroscopy. Physical performance was analyzed with a hand grip strength test, 4 m walking test, sit-to-stand test, timed up and go test, standing balance test and clinical frailty scale. We included 92 patients (65% men). The Child Pugh Turcotte classification was significantly higher in the lowest sex-stratified BCAA tertile compared to the highest tertile (p = 0.015). The times for the sit-to-stand (r = -0.352, p < 0.05) and timed up and go tests (r = -0.472, p < 0.01) were inversely correlated with total BCAA levels. In conclusion, lower circulating BCAA are associated with the severity of liver disease and impaired muscle function. This suggests that BCAA may represent a useful prognostic marker in the staging of liver disease severity.

Dietary Folic Acid Supplementation Inhibits HighFat DietInduced Body Weight Gain through Gut Microbiota-Associated Branched-Chain Amino Acids and Mitochondria in Mice.

The effects of folic acid on body weight gain in obesity and gut microbiota-associated branched-chain amino acids (BCAAs) and mitochondrial function were investigated. Three- to four-wk-old male C57BL/6J conventional (CV) and germ-free (GF) mice were fed a high-fat diet (HD), folic acid-supplemented HD (FSHD) and a normal-fat diet (ND) for 25 wk. In CV mice, the HD-induced increases in body weight and plasma BCAA concentrations, downregulated expression of genes related to BCAA catabolism (Bcat2, Bckdha, or Ppm1k), mitochondrial biogenesis (Pgc-1α, Cox1, Nd1 or Nd6), fusion (Mfn1, Mfn2 or Opa1) and mitophagy (Pink1 or Park2), and upregulated expression of the fission-associated gene Drp1 in epididymal fat were reversely corrected with FSHD feeding. In contrast, the expression of these genes in the liver was the opposite under HD feeding or folic acid supplementation. In GF mice, plasma BCAA concentrations were much less affected by HD feeding and were reduced by FSHD feeding, with almost no alterations in the expression of genes associated with BCAA catabolism and mitochondrial function. Further analysis indicated a correlation between adipose and hepatic Mt C/N and plasma BCAA concentrations, and the latter had a close association with specific gut bacteria. Therefore, dietary folic acid supplementation differentially affected body weight gain, BCAA catabolism, and mitochondrial dynamics and metabolism under HD feeding between CV and GF mice, suggesting that gut bacteria-altered BCAAs and mitochondria might partially share the responsibility for the beneficial effects of dietary folic acid on obesity.

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.

Potential role of plasma branched-chain amino acids in the differential diagnosis of acute cerebral venous thrombosis

Cerebral venous thrombosis (CVT) is a special and easily misdiagnosed or undiagnosed subtype of stroke. To identify specific biomarkers with a high predictive ability for the diagnosis of acute CVT, we performed metabolomic analysis in plasma samples from acute CVT patients and healthy controls and confirmed the results in validation cohorts. In the discovery stage, there were 343 differential metabolites, and the caffeine metabolism pathway and the biosynthesis pathway for the branched chain amino acids (BCAAs) valine, leucine, and isoleucine were two significant pathways between the CVT and healthy cohorts. The area under the curve (AUC) for metabolites associated with valine, leucine, and isoleucine biosynthesis was 0.934. In the validation stage, the BCAA concentrations demonstrated an AUC of 0.935 to differentiate patients with acute CVT from the control cohort. In addition, BCAAs combined with D-dimer levels were used to establish a diagnostic model for CVT, and the AUC was 0.951, showing good diagnostic efficacy of separating CVT patients from the control cohort. BCAAs as plasma biomarkers deserve to be further studied and even developed in clinical CVT management.