Plasma Branched-Chain and Aromatic Amino Acids in Relation to Hypertension

Duality of Branched-Chain Amino Acids in Chronic Cardiovascular Disease: Potential Biomarkers versus Active Pathophysiological Promoters

Branched-chain amino acids (BCAAs), comprising leucine (Leu), isoleucine (Ile), and valine (Val), are essential nutrients vital for protein synthesis and metabolic regulation via specialized signaling networks. Their association with cardiovascular diseases (CVDs) has become a focal point of scientific debate, with emerging evidence suggesting both beneficial and detrimental roles. This review aims to dissect the multifaceted relationship between BCAAs and cardiovascular health, exploring the molecular mechanisms and clinical implications. Elevated BCAA levels have also been linked to insulin resistance (IR), type 2 diabetes mellitus (T2DM), inflammation, and dyslipidemia, which are well-established risk factors for CVD. Central to these processes are key pathways such as mammalian target of rapamycin (mTOR) signaling, nuclear factor kappa-light-chain-enhancer of activate B cells (NF-κB)-mediated inflammation, and oxidative stress. Additionally, the interplay between BCAA metabolism and gut microbiota, particularly the production of metabolites like trimethylamine-N-oxide (TMAO), adds another layer of complexity. Contrarily, some studies propose that BCAAs may have cardioprotective effects under certain conditions, contributing to muscle maintenance and metabolic health. This review critically evaluates the evidence, addressing the biological basis and signal transduction mechanism, and also discusses the potential for BCAAs to act as biomarkers versus active mediators of cardiovascular pathology. By presenting a balanced analysis, this review seeks to clarify the contentious roles of BCAAs in CVD, providing a foundation for future research and therapeutic strategies required because of the rising prevalence, incidence, and total burden of CVDs.

Association between Childhood Overweight and Altered Concentrations of Circulating Amino Acids

(1) Background: Dysregulated serum amino acids (AA) are known to be associated with obesity and risk of Type 2 Diabetes (T2D) in adults, and recent studies support the same notion in the pubertal age. It is, however, unknown whether childhood overweight may already display alterations of circulating AA. (2) Methods: We used liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-targeted metabolomics to determine plasma concentrations of AA and AA-related molecules in 36 children aged 7-12 years with normal weight or overweight. Clinical and anthropometric parameters were measured. (3) Results: Overweight in children is associated with an altered AA profile, with increased branched-chain amino acids (BCAA) and decreased glycine levels, with no clinically manifested metabolic conditions. Moreover, z-BMI was positively and negatively correlated with BCAA and glycine levels, respectively, even after adjustment for age and gender. We also found a correlation between the AA profile and clinical parameters such as lipids profile and glycemia. (4) Conclusions: A pattern of low glycine, and increased BCAA is correlated to z-BMI, total cholesterol, and triglycerides in overweight but otherwise healthy children. Our data suggest that, in childhood overweight, AA disturbances may precede other clinical parameters, thus providing an early indicator for the later development of metabolic disease.

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

AIM

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.

MATERIALS AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

Circulating Branched Chain Amino Acids and Cardiometabolic Disease

Branched chain amino acids (BCAAs) are essential for protein homeostasis, energy balance, and signaling pathways. Changes in BCAA homeostasis have emerged as pivotal contributors in the pathophysiology of several cardiometabolic diseases, including type 2 diabetes, obesity, hypertension, atherosclerotic cardiovascular disease, and heart failure. In this review, we provide a detailed overview of BCAA metabolism, focus on molecular mechanisms linking disrupted BCAA homeostasis with cardiometabolic disease, summarize the evidence from observational and interventional studies investigating associations between circulating BCAAs and cardiometabolic disease, and offer valuable insights into the potential for BCAA manipulation as a novel therapeutic strategy for cardiometabolic disease.

Dietary branched-chain amino acids intake and new-onset hypertension: a nationwide prospective cohort study in China

OBJECTIVE

This study aimed to investigate the relationship between dietary branched-chain amino acids (BCAAs) and the risk of developing hypertension.

METHODS

A cohort study of 14,883 Chinese adults without hypertension at baseline with were followed for an average of 8.9 years. Dietary intakes of BCAAs, including Ile, Leu, and Val, were collected using 3-day 24-h meal recall and household condiment weighing. Cox proportional hazards regression, restricted cubic splines, interaction analysis, and sensitivity analysis were used to assess the relationship between dietary BCAAs and risk of developing self-reported hypertension, adjusting for age, gender, region, body mass index (BMI), smoking and drinking status, physical activity, energy intake, salt intake.

RESULTS

Among 14,883 study subjects, 6386(42.9%) subjects aged ≥ 45 years at baseline, 2692 (18.1%) had new-onset hypertension during the study period, with a median age of 56 years. High levels of dietary BCAAs were associated with an increased risk of new-onset hypertension. Compared with the 41st-60th percentile, multivariable adjusted hazard ratio (HR) for new-onset hypertension was 1.16 (95% CI 1.01-1.32) for dietary BCAAs 61st-80th percentiles, 1.30 (1.13-1.50) for 81st-95th, 1.60 (1.32-1.95) for 96th-100th. The cut-off value of new-onset hypertension risk, total BCAAs, Ile, Leu, and Val were 15.7 g/day, 4.1 g/day, 6.9 g/day, 4.6 g/day, respectively, and the proportion of the population above these intake values were 13.9%, 13.1%, 15.4%, and 14.4%, respectively. Age, BMI, and salt intake had an interactive effect on this relationship (P < 0.001).

CONCLUSION

There was a significant positive association between total dietary BCAAs, Ile, Leu, Val intake and the risk of developing hypertension, after adjustment for confounders. This relationship was influenced by age, BMI, and salt intake. Further research is needed to clarify the mechanism and potential role of BCAAs in the pathogenesis of hypertension.

Causal Relationship Between Branched-Chain Amino Acids and Hypertension: A Mendelian Randomization Study

BACKGROUND

This study aimed to investigate the causal relationships between branched-chain amino acids (BCAAs) and the risks of hypertension via meta-analysis and Mendelian randomization analysis.

METHODS AND RESULTS

A meta-analysis of 32 845 subjects was conducted to evaluate the relationships between BCAAs and hypertension. In Mendelian randomization analysis, independent single-nucleotide polymorphisms associated with BCAAs at the genome-wide significance level were selected as the instrumental variables. Meanwhile, the summary-level data for essential hypertension and secondary hypertension end points were obtained from the FinnGen study. As suggested by the meta-analysis results, elevated BCAA levels were associated with a higher risk of hypertension (isoleucine: summary odds ratio, 1.26 [95% CI, 1.08-1.47]; leucine: summary odds ratio, 1.28 [95% CI, 1.07-1.52]; valine: summary odds ratio, 1.32 [95% CI, 1.12-1.57]). Moreover, the inverse variance-weighted method demonstrated that an elevated circulating isoleucine level might be the causal risk factor for essential hypertension but not secondary hypertension (essential hypertension: odds ratio, 1.22 [95% CI, 1.12-1.34]; secondary hypertension: odds ratio, 0.96 [95% CI, 0.54-1.68]).

CONCLUSIONS

The increased levels of 3 BCAAs positively correlated with an increased risk of hypertension. Particularly, elevated isoleucine level is a causal risk factor for essential hypertension. Increased levels of leucine and valine also tend to increase the risk of essential hypertension, but further verification is still warranted.

The Role of Branched-chain Amino Acids and Their Metabolism in Cardiovascular Diseases

Branched-chain amino acids (BCAAs), including leucine, isoleucine, and valine, are essential amino acids for protein synthesis. Recent studies have yielded new insights into their diverse physiological and pathological roles in health and disease. Cardiovascular diseases (CVDs) are the leading cause of morbidity and mortality globally. An increasing number of clinical studies have demonstrated that high levels of circulating BCAAs are associated with an increased risk of CVDs. Animal studies have provided preliminary evidence linking BCAA intake and metabolism with cardiovascular diseases. Despite these insights, the causal relationship between BCAA metabolism and CVD remains poorly established, and the underlying mechanisms remain incompletely understood. Here, we aim to provide an update on the current understanding of the roles of BCAAs and their metabolism in the development and progression of various CVDs. We also discuss the potential strategies targeting BCAA nutrition and metabolism for the prevention and treatment of CVDs.

Amino acid profiles: exploring their diagnostic and pathophysiological significance in hypertension

Hypertension, a major contributor to cardiovascular morbidity, is closely linked to amino acid metabolism. Amino acids, particularly branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs), may play pivotal roles in the pathogenesis and potential management of hypertension. This review investigated the relationships between amino acid profiles, specifically BCAAs and AAAs, and hypertension, and examined their potential as diagnostic and therapeutic targets. An in-depth analysis was conducted on studies highlighting the associations of specific amino acids such as arginine, glycine, proline, glutamine, and the BCAAs and AAAs with hypertension. BCAAs and AAAs, alongside other amino acids like arginine, glycine, and proline, showed significant correlations with hypertension. These amino acids influence multiple pathways including nitric oxide synthesis, vascular remodeling, and neurotransmitter production, among others. Distinct amino acid profiles were discerned between hypertensive and non-hypertensive individuals. Amino acid profiling, particularly the levels of BCAAs and AAAs, offers promising avenues in the diagnostic and therapeutic strategies for hypertension. Future studies are crucial to confirm these findings and to delineate amino acid-based interventions for hypertension treatment.

Composition Analysis and Nutritional Value Evaluation of Amino Acids in the Fruit of 161 Jujube Cultivars

Amino acids are an essential group of compounds involved in protein synthesis and various metabolic and immune reactions in the human body. Chinese jujubes (Ziziphus jujuba Mill.) are an important fruit and medicinal plant which are native to China and have been introduced into around 50 countries. However, systematic research on the composition and content diversity of amino acids in the jujube is still lacking. In this experiment, the amino acid composition and the contents of the dominant amino acids in the fruit of 161 cultivars of jujube were determined by HPLC. Of the twenty-one kinds of amino acids detected, a total of fourteen kinds of amino acids were detected, of which eight kinds of amino acids were relatively high, including five essential amino acids (threonine, valine, isoleucine, leucine, and phenylalanine) and three nonessential amino acids (glycine, alanine, and proline). However, the contents of the remaining six amino acids were relatively low (aspartic acid, glutamic acid, histidine, serine, arginine, and tryptophan). Therefore, the eight primary amino acids were used as the index to evaluate the amino acids of 161 jujube varieties. Proline accounts for 56.8% of the total amino acid content among the eight amino acids. The total content of the eight primary amino acids in most jujube varieties was 1-1.5 g/100 g, and the highest content of 'Zaoqiangmalianzao' was 2.356 g/100 g. The average content of proline was 6.01-14.84 times that of the other seven amino acids. According to the WHO/FAO revised model spectrum of ideal essential amino acids for humans, 19 cultivars met the E/T (essential amino acids/total amino acids) standard, and their values ranged from 35% to 45%; 12 cultivars meet E/NE (non-essential amino acids) ≥ 60%. All cultivars reached the requirement of BC (branched-chain amino acids)/E ≥ 40% with 15 cultivars over 68%. One hundred and fifty-seven cultivars reach the standard of BC/A (aromatic amino acids) ≈ 3.0~3.5. The amino acid ratio coefficient analysis showed that phenylalanine was the first limiting amino acid of all the jujube cultivars. The SRC (the score of amino acid ratio coefficient) values of 134 cultivars were between 50% and 70%, with 12 cultivars over 70%, indicating that jujube fruits are of high nutritional value in terms of amino acids. Based on the principal component analysis and comprehensive ranking of amino acid nutritional value, the top five cultivars were screened from the 161 ones tested, i.e., 'Tengzhouchanghongzao', 'Xinzhengxiaoyuanzao', 'Hanguowudeng', 'Xuputiansuanzao', and 'Lichengxiaozao'. This study established, firstly, a complete basic data analysis of amino acid content in jujube fruit which could be used to select germplasm resources suitable for developing functional amino acid food, and provide theoretical support for the high value utilization of amino acids in jujubes.

Extra-cardiac BCAA catabolism lowers blood pressure and protects from heart failure

Pharmacologic activation of branched-chain amino acid (BCAA) catabolism is protective in models of heart failure (HF). How protection occurs remains unclear, although a causative block in cardiac BCAA oxidation is widely assumed. Here, we use in vivo isotope infusions to show that cardiac BCAA oxidation in fact increases, rather than decreases, in HF. Moreover, cardiac-specific activation of BCAA oxidation does not protect from HF even though systemic activation does. Lowering plasma and cardiac BCAAs also fails to confer significant protection, suggesting alternative mechanisms of protection. Surprisingly, activation of BCAA catabolism lowers blood pressure (BP), a known cardioprotective mechanism. BP lowering occurred independently of nitric oxide and reflected vascular resistance to adrenergic constriction. Mendelian randomization studies revealed that elevated plasma BCAAs portend higher BP in humans. Together, these data indicate that BCAA oxidation lowers vascular resistance, perhaps in part explaining cardioprotection in HF that is not mediated directly in cardiomyocytes.

The causal associations of circulating amino acids with blood pressure: a Mendelian randomization study

BACKGROUND

Circulating levels of amino acids were associated with blood pressure (BP) in observational studies. However, the causation of such associations has been hypothesized but is difficult to prove in human studies. Here, we aimed to use two-sample Mendelian randomization analyses to evaluate the potential causal associations of circulating levels of amino acids with BP and risk of hypertension.

METHODS

We generated genetic instruments for circulating levels of nine amino acids by conducting meta-analyses of genome-wide association study (GWAS) in UK Biobank participants with metabolomic data (n = 98,317) and another published metabolomics GWAS (n = 24,925). Data on the associations of the genetic variants with BP and hypertension were obtained in the UK Biobank participants without metabolomic data (n = 286,390). The causal effects were estimated using inverse-variance weighted method.

RESULTS

Significant evidence consistently supported the causal effects of increased branched-chain amino acids (BCAAs, i.e., leucine, isoleucine, and valine) levels on higher BP and risk of hypertension (all P < 0.006 after Bonferroni correction except for P_{leucine-on-diastolicBP} = 0.008). For example, per standard deviation higher of genetically predicted isoleucine levels were associated with 2.71 ± 0.78 mmHg higher systolic BP and 1.24 ± 0.34 mmHg higher diastolic BP, as well as with 7% higher risk of hypertension (odds ratio: 1.07, [95% CI: 1.04-1.10]). In addition, per standard deviation higher of genetically predicted glycine level was associated with lower systolic BP (- 0.70 ± 0.17 mmHg, P = 4.04 × 10^-5) and a lower risk of hypertension (0.99 [0.98-0.99], P = 6.46 × 10^-5). In the reverse direction, genetically predicted higher systolic BP was associated with lower circulating levels of glycine (- 0.025±0.008, P = 0.001).

CONCLUSIONS

This study provides evidence for causal impacts of genetically predicted circulating BCAAs and glycine levels on BP. Meanwhile, genetically predicted higher BP was associated with lower glycine levels. Further investigations are warranted to clarify the underlying mechanisms.

Normalization of Vitamin D Serum Levels in Patients with Type Two Diabetes Mellitus Reduces Levels of Branched Chain Amino Acids

Background and Objectives: Vitamin D is involved in pancreatic beta-cell function, insulin sensitivity, and inflammation. Further, elevation in branched-chain amino acids (BCAAs) has been implicated in type 2 diabetes (T2DM) pathology. However, the relationship between vitamin D and BCAAs in T2DM remains unclear. The current study aimed to investigate the relationship between vitamin D and BCAAs in T2DM. Materials and Methods: In total, 230 participants (137 with T2DM and 93 healthy controls) were recruited in a cross-sectional study. Furthermore, an additional follow-up study was performed, including 20 T2DM patients with vitamin D deficiency. These patients were prescribed weekly vitamin D tablets (50,000 IU) for three months. The levels of several biochemical parameters were examined at the end of the vitamin D supplementation. Results: The results showed that patients with T2DM had higher serum levels of BCAAs and lower serum levels of 25-hydroxyvitamin D (25(OH)D) compared with those of the healthy controls (p < 0.01). The serum levels of vitamin D were negatively correlated with BCAA levels in T2DM patients (r = −0.1731, p < 0.05). In the follow-up study, 25(OH)D levels were significantly improved (p < 0.001) following vitamin D supplementation. Vitamin D supplementation significantly reduced the levels of BCAAs, HbA1c, total cholesterol, triglycerides, and fasting glucose (p < 0.01). Conclusion: Overall, these results suggest a role for BCAAs and vitamin D in the etiology and progression of T2DM. Thus, managing vitamin D deficiency in patients with T2DM may improve glycemic control and lower BCAA levels.

Aromatic Amino Acids: Phenylalanine and Tyrosine in Patients with Hypertension and Coronary Artery Disease

Aim. To evaluate changes in the profile of aromatic amino acids (AAA) in patients with cardiovascular diseases (CVD): hypertension and coronary artery disease (CАD) in comparison with healthy study participants.

Material and methods. One hundred and thirty-one participants were included in the study: 58 participants were included in the hypertension group, 46 in the CАD group, and 27 participants without signs of CVD in the control group. We used ultrahigh-performance liquid chromatography in combination with a triple quadrupole analyzer to measure plasma AAA: phenylalanine and tyrosine (Phe, Tyr) in all study participants. The association of AAA with biochemical blood test parameters, echocardiography (EchoCG) parameters, blood pressure level and clinical characteristics was analyzed.

Results. A statistically significant difference in the level of concentration of Phe and Tyr was revealed (p=0,002 and p=0,024, respectively), comparing the three groups. Post-hoc analysis showed differences in the circulating level of both amino acids in patients with CAD vs the control group (Phe p=0,008 and Tyr p=0,020). Also a statistically significant difference in the level of Phe of the hypertension and CАD groups (p=0,017) was found. A negative correlation of low-density lipoproteins (LDL) with the level of Phe (r=-0,685, p<0,05) and Tyr (r=-0,583, p<0,05), as well as the level of Phe with total cholesterol (r=-0,461, p<0,05) was found in the group without CVD. In the hypertension group, only a weak positive correlation was found between very low-density lipoproteins and AAA levels (Phe r=0,326 and Tyr r=0,365, p<0,05), while in patients with CAD, the level of Phe and Tyr was negative correlated with high-density lipoprotein (r=-0,378 and r=-0,543, respectively, p<0,05), and the level of Tyr with LDL (r=0,349, p<0,05). When isolating the group with proven atherosclerosis of peripheral and/or coronary arteries, a statistically significant difference was revealed between the group of patients with CVD and clinical and instrumental signs of atherosclerosis and the group of patients with CVD without proven atherosclerosis in Phe level (p=0,019).

Conclusion. Concentrations of AAA were higher in patients with CVD, comparing with the control group. At the same time, an increase of the Phe level was associated with the presence of peripheral or coronary atherosclerosis. The revealed correlations of AAA with EchoCG parameters and lipid spectrum parameters require further study to understand the involvement of AAA in pathogenesis of CVD and its potential role as treatment target.

Association between Excessive Dietary Branched-Chain Amino Acids Intake and Hypertension Risk in Chinese Population

The dietary intake of branched-chain amino acids (BCAAs) has been reported to be associated with both elevated blood pressure (BP) and hypertension risk, while published findings were inconsistent, and the causality has never been well disclosed. We performed this prospective study aiming to find out the relationship between dietary BCAAs intake and hypertension risk in the Chinese population. A total of 8491 participants (40,285 person-years) were selected. The levels of dietary BCAAs intake were estimated using the 24-h Food Frequency Questionnaire. Associations of both BP values and hypertension risk with per standard deviation increase of BCAAs were estimated using linear and COX regression analysis, respectively. The hazard ratios and 95% confidence interval were given. Restricted cubic spline analysis (RCS) was used to estimate the nonlinearity. Both systolic and diastolic BP values at the end points of follow-up were positively associated with dietary BCAAs intake. Positive associations between BCAAs intake and hypertension risk were shown in both men and women. By performing a RCS analysis, the nonlinear relationship between BCAAs intake and hypertension was shown. As the intake levels of Ile, Leu, and Val, respectively, exceeded 2.49 g/day, 4.91 g/day, and 2.88 g/day in men (2.16 g/day, 3.84 g/day, and 2.56 g/day in women), the hypertension risk increased. Our findings could provide some concrete evidence in the primary prevention of hypertension based on dietary interventions.

Multi-Omics Integration in a Twin Cohort and Predictive Modeling of Blood Pressure Values

Abnormal blood pressure is strongly associated with risk of high-prevalence diseases, making the study of blood pressure a major public health challenge. Although biological mechanisms underlying hypertension at the single omic level have been discovered, multi-omics integrative analyses using continuous variations in blood pressure values remain limited. We used a multi-omics regression-based method, called sparse multi-block partial least square, for integrative, explanatory, and predictive interests in study of systolic and diastolic blood pressure values. Various datasets were obtained from the Finnish Twin Cohort for up to 444 twins. Blocks of omics-including transcriptomic, methylation, metabolomic-data as well as polygenic risk scores and clinical data were integrated into the modeling and supported by cross-validation. The predictive contribution of each omics block when predicting blood pressure values was investigated using external participants from the Young Finns Study. In addition to revealing interesting inter-omics associations, we found that each block of omics heterogeneously improved the predictions of blood pressure values once the multi-omics data were integrated. The modeling revealed a plurality of clinical, transcriptomic, and metabolomic factors consistent with the literature and that play a leading role in explaining unit variations in blood pressure. These findings demonstrate (1) the robustness of our integrative method to harness results obtained by single omics discriminant analyses, and (2) the added value of predictive and exploratory gains of a multi-omics approach in studies of complex phenotypes such as blood pressure.

Obesity Is Associated with Sustained Symptomatology and Unique Inflammatory Features in Children with Asthma

BACKGROUND

Obesity complicates the clinical manifestations of asthma in children. However, few studies have examined longitudinal outcomes or markers of systemic inflammation in obese asthmatic children.

OBJECTIVE

We hypothesized that obese children with asthma would have: (1) poorer clinical outcomes over 12 months, (2) decreased responsiveness to systemic corticosteroid administration, (3) greater markers of systemic inflammation, and (4) unique amino acid metabolites associated with oxidative stress.

METHODS

Children 6 to 17 years of age (lean, N = 257; overweight, N = 99; obese, N = 138) completed a baseline visit and follow-up visit at 12 months. Outcome measures included asthma control, quality of life, lung function, and exacerbations. A subset received intramuscular triamcinolone and were re-evaluated at 7(+7) days. Leptin, adiponectin, C-reactive protein, total cholesterol, interleukin (IL)-1β, IL-6, IL-17, interferon gamma, tumor necrosis factor alpha, monocyte-chemoattractant protein-1, and amino acid metabolites were also quantified in plasma as potential biomarkers of outcomes in obese children.

RESULTS

Obesity was associated with more symptoms, poorer quality life, and more exacerbations that persisted over 1 year despite greater medication requirements. Obese children also had minimal clinical improvement in asthma control and lung function after intramuscular triamcinolone. Leptin, C-reactive protein, and amino acid metabolites associated with glutathione synthesis and oxidative stress differed in obese children. Within the obese group, lower concentrations of arginine-related metabolites also distinguished uncontrolled from controlled asthma at 12 months.

CONCLUSION

Obesity is associated with poorer asthma outcomes and unique systemic inflammatory features that may not be adequately modified with conventional asthma therapies. Novel approaches may be needed given increased symptoms and unique inflammation and oxidative stress in obese children with asthma.

Lipidomic and Metabolomic Signature of Progression of Chronic Kidney Disease in Patients with Severe Obesity

Severe obesity is a major risk for chronic kidney disease (CKD). Early detection and careful monitoring of renal function are critical for the prevention of CKD during obesity, since biopsies are not performed in patients with CKD and diagnosis is dependent on the assessment of clinical parameters. To explore whether distinct lipid and metabolic signatures in obesity may signify early stages of pathogenesis toward CKD, liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-high resolution accurate mass-mass spectrometry (GC-HRAM-MS) analyses were performed in the serum and the urine of severely obese patients with and without CKD. Moreover, the impact of bariatric surgery (BS) in lipid and metabolic signature was also studied, through LC-MS and GC-HRAM-MS analyses in the serum and urine of patients with severe obesity and CKD before and after undergoing BS. Regarding patients with severe obesity and CKD compared to severely obese patients without CKD, serum lipidome analysis revealed significant differences in lipid signature. Furthermore, serum metabolomics profile revealed significant changes in specific amino acids, with isoleucine and tyrosine, increased in CKD patients compared with patients without CKD. LC-MS and GC-HRAM-MS analysis in serum of patients with severe obesity and CKD after BS showed downregulation of levels of triglycerides (TGs) and diglycerides (DGs) as well as a decrease in branched-chain amino acid (BCAA), lysine, threonine, proline, and serine. In addition, BS removed most of the correlations in CKD patients against biochemical parameters related to kidney dysfunction. Concerning urine analysis, hippuric acid, valine and glutamine were significantly decreased in urine from CKD patients after surgery. Interestingly, bariatric surgery did not restore all the lipid species, some of them decreased, hence drawing attention to them as potential targets for early diagnosis or therapeutic intervention. Results obtained in this study would justify the use of comprehensive mass spectrometry-based lipidomics to measure other lipids aside from conventional lipid profiles and to validate possible early markers of risk of CKD in patients with severe obesity.

Association of Plasma Branched-Chain and Aromatic Amino Acids with Reduction in Kidney Function Evaluated in Apparently Healthy Adults

The published literature on the association of circulatory branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs) with reduced kidney function is inconsistent or conflicting. Clarification of it might help to better understand the underlying pathophysiology and to determine potential biomarkers for early detection and evaluation of kidney function decline. Our main purpose was to explore and clarify the potential relationships of individual BCAAs and AAAs with estimated glomerular filtration rate (eGFR) decline. We included the data from 2804 healthy subjects and categorized them into three groups based on eGFR tertiles. The associations between individual amino acids and eGFR were explored by covariate-adjusted logistic regression models. There was a progressive increase in the concentrations of BCAAs and AAAs from the upper to the lower tertiles. We revealed significant positive associations of isoleucine, leucine, and phenylalanine with lower tertiles of eGFR in the adjusted models (p < 0.01-0.001). The findings hold a promising potential of using plasma isoleucine, leucine, and phenylalanine levels for evaluation of kidney function decline. Future longitudinal studies should investigate the causal association between altered levels of these amino acids and impaired kidney function and also the utility of the former as potential biomarkers for evaluating the risk and early detection of the latter.

Potential Antihypertensive Mechanisms of the Egg White-Derived Peptide QIGLF in Spontaneously Hypertensive Rats Revealed Using Untargeted Serum Metabolomics

The angiotensin-converting enzyme (ACE) inhibitory peptide QIGLF derived from egg white was shown to have significant in vivo antihypertensive effects in our previous study, but the intervention mechanisms at the metabolic level are still unclear. The UPLC-QTOF/MS-based untargeted metabolomics approach was used to clarify the potential antihypertensive mechanisms of QIGLF in the serum of spontaneously hypertensive rats (SHRs). Multivariate statistical analysis showed a clear difference in the metabolite profiles between the QIGLF and model groups. The results suggested that eight potential biomarkers were identified, that is, adrenic acid, ursodeoxycholic acid, glycocholic acid, taurocholic acid, tryptophan, acetylindoxyl, tyrosine, and 2-phenylethanol, which were mainly involved in aromatic amino acid biosynthesis and metabolism, biosynthesis of bile acid, and biosynthesis of unsaturated fatty acids. QIGLF might exert antihypertensive effects by improving endothelial dysfunction. This study provides a theoretical basis for future research and application of ACE inhibitory peptides in the prevention and improvement of hypertension.

Association Between Blood Pressure and Branched-Chain/Aromatic Amino Acid Excretion Rate in 24-Hour Urine Samples from Elderly Hypertension Patients

BACKGROUND

Recently, the association between lifestyle-related diseases and free amino acids in the blood plasma-especially branched-chain amino acids (BCAAs) and aromatic amino acids (AAAs)-has been highlighted. However, few studies have been carried out on 24-hour urine samples. Therefore, we aimed to explore the relationships between 24-hour urinary BCAAs and AAAs excretion rate and blood pressure (BP) in elderly patients with hypertension.

METHODS AND RESULTS

Each of the 322 elderly patients with hypertension completed an in-person questionnaire interview, underwent a physical examination, and provided a 24-hour urine specimen. We measured their BCAAs and AAAs excretion rate, and used multiple linear regression analysis with variable selection to construct models describing the relationships between their BCAAs and AAAs excretion rate and BP. After adjusted for age, gender, height, and weight, valine was inversely associated with both systolic blood pressure (SBP) (β: -0.232, 95% CI: -0.16, -0.006) and diastolic blood pressure (DBP) (β: -0.144, 95% CI: -0.089, -0.005). These findings were invariant even following adjustment for urine volume and drugs history, and Ile was positively associated with DBP (β: 0.170, 95% CI: 0.001, 0.066).

CONCLUSION

The data revealed that the excretion rate of 24-hour urinary BCAAs was closely related to BP in elderly hypertension patients, and these findings will provide new insights into the association between BACC metabolism and BP.