Plasma Glutamine Research Articles

A phase 1 study of the amino acid modulator pegcrisantaspase and venetoclax for relapsed or refractory acute myeloid leukemia

AbstractGlutamine dependency has been shown to be a metabolic vulnerability in acute myeloid leukemia (AML). Prior studies using several in vivo AML models showed that depletion of plasma glutamine, induced by long-acting crisantaspase (pegcrisantaspase [PegC]) was synergistic with the BCL-2 inhibitor venetoclax (Ven), resulting in significantly reduced leukemia burden and enhanced survival. Here, we report a phase 1 study of the combination of Ven and PegC (VenPegC) for treating adult patients with relapsed or refractory AML, including patients who had previously received Ven. The primary end points were the incidence of regimen-limiting toxicities (RLTs) and the maximum tolerated dose (MTD). Twenty-five patients received at least 1 PegC dose with Ven, and 18 efficacy-evaluable patients completed at least 1 VenPegC cycle; 12 (67%) had previously received Ven. Hyperbilirubinemia was the RLT and occurred in 60% of patients treated with VenPegC; 20% had grade ≥3 bilirubin elevations. MTD was determined to be Ven 400 mg daily with biweekly PegC 750 IU/m2. The most common treatment-related adverse events of any grade in 25 patients who received VenPegC included antithrombin III decrease (52%), elevated transaminases (36%-48%), fatigue (28%), and hypofibrinogenemia (24%). No thromboembolic or hemorrhagic adverse events or clinical pancreatitis were observed. The overall complete remission rate in efficacy-evaluable patients was 33%. Response correlated with alterations in proteins involved in messenger RNA translation. In patients with RUNX1 mutations, the composite complete rate was 100%. This study was registered at www.ClinicalTrials.gov as #NCT04666649.

Urinary chloride excretion in critical illness and acute kidney injury: a paediatric hypothesis-generating cohort study post cardiopulmonary bypass surgery.

Renal chloride metabolism is currently poorly understood but may serve as both a diagnostic and a treatment approach for acute kidney injury. We investigated whether plasma chloride, ammonia and glutamine as well as urinary chloride, ammonium and glutamine concentrations may serve as markers for acute kidney injury in paediatric patients. We conducted a prospective observational trial in a tertiary care paediatric intensive care unit. Ninety-one patients after cardiopulmonary bypass surgery were enrolled. Plasma glutamine, creatinine, (serum) albumin, urinary electrolytes and glutamine were collected pre-cardiopulmonary bypass surgery, at paediatric intensive care unit admission, and at 6, 12, 24, 48 and 72 h after paediatric intensive care unit admission. The urinary strong ion difference was calculated. The median urinary chloride excretion decreased from 51 mmol/L pre-cardiopulmonary bypass to 25 mmol/L at paediatric intensive care unit admission, and increased from 24 h onwards. Patients with acute kidney injury had lower urinary chloride excretion than those without. The median urinary strong ion difference was 59 mmol/L pre-cardiopulmonary bypass, rose to 131 mmol/L at 24 h and fell to 20 mmol/L at 72 h. The plasma chloride rose from 105 mmol/L pre-cardiopulmonary bypass to a maximum of 109 mmol/L at 24 h. At 24 h the plasma chloride concentration was associated with the presence of acute kidney injury. There was no association between plasma or urinary amino acids and chloride excretion or kidney injury. In conclusion, renal chloride excretion decreased in all patients, although this decrease was more pronounced in patients with acute kidney injury. Our findings may reflect a response of the kidneys to critical illness, and acute kidney injury may make these changes more pronounced. Targeting chloride metabolism may offer treatment approaches to acute kidney injury.

Exploring the causal relationship between glutamine metabolism and leukemia risk: a Mendelian randomization and LC-MS/MS analysis.

This investigation sought to delineate the causal nexus between plasma glutamine concentrations and leukemia susceptibility utilizing bidirectional Mendelian Randomization (MR) analysis and to elucidate the metabolic ramifications of asparaginase therapy on glutamine dynamics in leukemia patients. A bidirectional two-sample MR framework was implemented, leveraging genetic variants as instrumental variables from extensive genome-wide association studies (GWAS) tailored to populations of European descent. Glutamine quantification was executed through a rigorously validated Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) protocol. Comparative analyses of glutamine levels were conducted across leukemia patients versus healthy controls, pre- and post-asparaginase administration. Statistical evaluations employed inverse variance weighted (IVW) models, MR-Egger regression, and sensitivity tests addressing pleiotropy and heterogeneity. The MR findings underscored a significant inverse association between glutamine levels and leukemia risk (IVW p = 0.03558833), positing lower glutamine levels as a contributory factor to heightened leukemia susceptibility. Conversely, the analysis disclosed no substantive causal impact of leukemia on glutamine modulation (IVW p = 0.9694758). Notably, post-asparaginase treatment, a marked decrement in plasma glutamine concentrations was observed in patients (p = 0.0068), underlining the profound metabolic influence of the therapeutic regimen. This study corroborates the hypothesized inverse relationship between plasma glutamine levels and leukemia risk, enhancing our understanding of glutamine's role in leukemia pathophysiology. The pronounced reduction in glutamine levels following asparaginase intervention highlights the critical need for meticulous metabolic monitoring to refine therapeutic efficacy and optimize patient management in clinical oncology. These insights pave the way for more tailored and efficacious treatment modalities in the realm of personalized medicine.

Long-acting Erwinia chrysanthemi, Pegcrisantaspase, induces alternate amino acid biosynthetic pathways in a preclinical model of pancreatic ductal adenocarcinoma

BackgroundPancreatic ductal adenocarcinoma (PDAC) is an aggressive disease without meaningful therapeutic options beyond the first salvage therapy. Targeting PDAC metabolism through amino acid restriction has emerged as a promising new strategy, with asparaginases, enzymes that deplete plasma glutamine and asparagine, reaching clinical trials. In this study, we investigated the anti-PDAC activity of the asparaginase formulation Pegcrisantaspase (PegC) alone and in combination with standard-of-care chemotherapeutics.MethodsUsing mouse and human PDAC cell lines, we assessed the impact of PegC on cell proliferation, cell death, and cell cycle progression. We further characterized the in vitro effect of PegC on protein synthesis as well as the generation of reactive oxygen species and levels of glutathione, a major cellular antioxidant. Additional cell line studies examined the effect of the combination of PegC with standard-of-care chemotherapeutics. In vivo, the tolerability and efficacy of PegC, as well as the impact on plasma amino acid levels, was assessed using the C57BL/6-derived KPC syngeneic mouse model.ResultsHere we report that PegC demonstrated potent anti-proliferative activity in a panel of human and murine PDAC cell lines. This decrease in proliferation was accompanied by inhibited protein synthesis and decreased levels of glutathione. In vivo, PegC was tolerable and effectively reduced plasma levels of glutamine and asparagine, leading to a statistically significant inhibition of tumor growth in a syngeneic mouse model of PDAC. There was no observable in vitro or in vivo benefit to combining PegC with standard-of-care chemotherapeutics, including oxaliplatin, irinotecan, 5-fluorouracil, paclitaxel, and gemcitabine. Notably, PegC treatment increased tumor expression of asparagine and serine biosynthetic enzymes.ConclusionsTaken together, our results demonstrate the potential therapeutic use of PegC in PDAC and highlight the importance of identifying candidates for combination regimens that could improve cytotoxicity and/or reduce the induction of resistance pathways.

Associations of Plasma Glutamatergic Metabolites with Alpha Desynchronization during Cognitive Interference and Working Memory Tasks in Asymptomatic Alzheimer's Disease.

Electroencephalogram (EEG) studies have suggested compensatory brain overactivation in cognitively healthy (CH) older adults with pathological beta-amyloid(Aβ42)/tau ratios during working memory and interference processing. However, the association between glutamatergic metabolites and brain activation proxied by EEG signals has not been thoroughly investigated. We aim to determine the involvement of these metabolites in EEG signaling. We focused on CH older adults classified under (1) normal CSF Aβ42/tau ratios (CH-NATs) and (2) pathological Aβ42/tau ratios (CH-PATs). We measured plasma glutamine, glutamate, pyroglutamate, and γ-aminobutyric acid concentrations using tandem mass spectrometry and conducted a correlational analysis with alpha frequency event-related desynchronization (ERD). Under the N-back working memory paradigm, CH-NATs presented negative correlations (r = ~-0.74--0.96, p = 0.0001-0.0414) between pyroglutamate and alpha ERD but positive correlations (r = ~0.82-0.95, p = 0.0003-0.0119) between glutamine and alpha ERD. Under Stroop interference testing, CH-NATs generated negative correlations between glutamine and left temporal alpha ERD (r = -0.96, p = 0.037 and r = -0.97, p = 0.027). Our study demonstrated that glutamine and pyroglutamate levels were associated with EEG activity only in CH-NATs. These results suggest cognitively healthy adults with amyloid/tau pathology experience subtle metabolic dysfunction that may influence EEG signaling during cognitive challenge. A longitudinal follow-up study with a larger sample size is needed to validate these pilot studies.

Intellectual disability and autism in propionic acidemia: a biomarker-behavioral investigation implicating dysregulated mitochondrial biology

Propionic acidemia (PA) is an autosomal recessive condition (OMIM #606054), wherein pathogenic variants in PCCA and PCCB impair the activity of propionyl-CoA carboxylase. PA is associated with neurodevelopmental disorders, including intellectual disability (ID) and autism spectrum disorder (ASD); however, the correlates and mechanisms of these outcomes remain unknown. Using data from a subset of participants with PA enrolled in a dedicated natural history study (n = 33), we explored associations between neurodevelopmental phenotypes and laboratory parameters. Twenty (61%) participants received an ID diagnosis, and 12 of the 31 (39%) who were fully evaluated received the diagnosis of ASD. A diagnosis of ID, lower full-scale IQ (sample mean = 65 ± 26), and lower adaptive behavior composite scores (sample mean = 67 ± 23) were associated with several biomarkers. Higher concentrations of plasma propionylcarnitine, plasma total 2-methylcitrate, serum erythropoietin, and mitochondrial biomarkers plasma FGF21 and GDF15 were associated with a more severe ID profile. Reduced 1-13C-propionate oxidative capacity and decreased levels of plasma and urinary glutamine were also associated with a more severe ID profile. Only two parameters, increased serum erythropoietin and decreased plasma glutamine, were associated with ASD. Plasma glycine, one of the defining features of PA, was not meaningfully associated with either ID or ASD. Thus, while both ID and ASD were commonly observed in our PA cohort, only ID was robustly associated with metabolic parameters. Our results suggest that disease severity and associated mitochondrial dysfunction may play a role in CNS complications of PA and identify potential biomarkers and candidate surrogate endpoints.

Plasma metabolites distinguish dementia with Lewy bodies from Alzheimer's disease: a cross-sectional metabolomic analysis.

In multifactorial diseases, alterations in the concentration of metabolites can identify novel pathological mechanisms at the intersection between genetic and environmental influences. This study aimed to profile the plasma metabolome of patients with dementia with Lewy bodies (DLB) and Alzheimer's disease (AD), two neurodegenerative disorders for which our understanding of the pathophysiology is incomplete. In the clinical setting, DLB is often mistaken for AD, highlighting a need for accurate diagnostic biomarkers. We therefore also aimed to determine the overlapping and differentiating metabolite patterns associated with each and establish whether identification of these patterns could be leveraged as biomarkers to support clinical diagnosis. A panel of 630 metabolites (Biocrates MxP Quant 500) and a further 232 metabolism indicators (biologically informative sums and ratios calculated from measured metabolites, each indicative for a specific pathway or synthesis; MetaboINDICATOR) were analyzed in plasma from patients with probable DLB (n = 15; age 77.6 ± 8.2 years), probable AD (n = 15; 76.1 ± 6.4 years), and age-matched cognitively healthy controls (HC; n = 15; 75.2 ± 6.9 years). Metabolites were quantified using a reversed-phase ultra-performance liquid chromatography column and triple-quadrupole mass spectrometer in multiple reaction monitoring (MRM) mode, or by using flow injection analysis in MRM mode. Data underwent multivariate (PCA analysis), univariate and receiving operator characteristic (ROC) analysis. Metabolite data were also correlated (Spearman r) with the collected clinical neuroimaging and protein biomarker data. The PCA plot separated DLB, AD and HC groups (R2 = 0.518, Q2 = 0.348). Significant alterations in 17 detected metabolite parameters were identified (q ≤ 0.05), including neurotransmitters, amino acids and glycerophospholipids. Glutamine (Glu; q = 0.045) concentrations and indicators of sphingomyelin hydroxylation (q = 0.039) distinguished AD and DLB, and these significantly correlated with semi-quantitative measurement of cardiac sympathetic denervation. The most promising biomarker differentiating AD from DLB was Glu:lysophosphatidylcholine (lysoPC a 24:0) ratio (AUC = 0.92; 95%CI 0.809-0.996; sensitivity = 0.90; specificity = 0.90). Several plasma metabolomic aberrations are shared by both DLB and AD, but a rise in plasma glutamine was specific to DLB. When measured against plasma lysoPC a C24:0, glutamine could differentiate DLB from AD, and the reproducibility of this biomarker should be investigated in larger cohorts.

DOES HIGH-INTENSITY RESISTANCE TRAINING AFFECT AN ATHLETE'S IMMUNE FUNCTIONS?

This research aims to comprehensively examine the latest literature on the effects of high-intensity resistance training on the immune system's long-term performance. Many athletes and active individuals believe that moderate physical activity can enhance resistance to minor illnesses like upper respiratory tract infections (URTI), while intense exercise may have the opposite effect. The study involved 90 athletes who regularly train at Ahly Sporting Club and were divided into three groups: Group 1 included 30 athletes at rest, Group 2 comprised 30 athletes after normal training, and Group 3 had 30 athletes after intense training. Athletes who undergo intense training have lower total white blood cell counts than those who train at normal or resting levels. However, their neutrophil numbers slightly increase after heavy training, while lymphocyte and natural killer cell levels decrease. Additionally, those who undergo heavy training have higher PHA-induced proliferation levels but show a decline in serum immunoglobulin levels, mucosal immunoglobulin concentrations, and plasma glutamine levels. To prevent upper respiratory tract infections in athletes, it is essential to avoid over training and provide sufficient rest and recovery during and after training and competition. It is currently uncertain whether moderate exercise training can prevent infectious illness among the general population.

Plasma amino acids pecularities and cardiometabolic risk factors in patients with coronary artery disease and atrial fibrillation

Studies targeting small molecule metabolites (amino acids, sugars, nucleotides, lipids) in connections with gut microbiota metabolites that impact the host metabolome give a possibility to define a special metabolic signature of different diseases. Plasma amino acids (AA) profile is known to be a new promising biomarker for the screening of coronary artery disease (CAD) pathogenesis connected with gut dysbiosis. The aim of our study was to estimate the spectrum of plasma amino acids in CAD patients with atrial fibrillation (AF) and to check their connections with the gut microbiota metabolites. 300 patients were divided into three groups: CAD – 149 patients with CAD but without arrhythmias, CAD+AF – 123 patients with CAD and AF paroxysm and control group– 28 patients without CAD and arrhythmias. Plasma AA level was detected by ion exchange liquid column chromatography. Significant changes in the content of plasma Glutamate, Glutamine, Glycine, Alanine, Valine and Tyrosine and combinations Isoleucine+Leucine/Valine, Glycine+Serine, Glycine/Methionine, Phenylalanine/Tyrosine, Glutamine/Glutamate in CAD+AF patients were detected. A strong reliable connection between plasma AA spectrum and gut microbiota metabolites trimethylamine, trimethylamine-N-oxide and total amount of fecal short chain fatty acids was determined. The highly validated plasma AA combinations Isoleucine – Glycine (area under ROC-curve 0.8122) and Phenylalanine – Glycine (area under ROC-curve 0.8061) that can be used as the early markers of AF paroxysm in CAD patients were proposed. Keywords: atrial fibrillation, cardiometabolic risk factors, coronary artery disease, gut microbiota metabolites, plasma amino acids

The effects of a hydrolyzed protein diet on the plasma, fecal and urine metabolome in cats with chronic enteropathy

Hydrolyzed protein diets are extensively used to treat chronic enteropathy (CE) in cats. However, the biochemical effects of such a diet on feline CE have not been characterized. In this study an untargeted 1H nuclear magnetic resonance spectroscopy-based metabolomic approach was used to compare the urinary, plasma, and fecal metabolic phenotypes of cats with CE to control cats with no gastrointestinal signs recruited at the Royal Veterinary College (RVC). In addition, the biomolecular consequences of a hydrolyzed protein diet in cats with CE was also separately determined in cats recruited from the RVC (n = 16) and the University of Bristol (n = 24) and whether these responses differed between dietary responders and non-responders. Here, plasma metabolites related to energy and amino acid metabolism significantly varied between CE and control cats in the RVC cohort. The hydrolyzed protein diet modulated the urinary metabolome of cats with CE (p = 0.005) in both the RVC and Bristol cohort. In the RVC cohort, the urinary excretion of phenylacetylglutamine, p-cresyl-sulfate, creatinine and taurine at diagnosis was predictive of dietary response (p = 0.025) although this was not observed in the Bristol cohort. Conversely, in the Bristol cohort plasma betaine, glycerol, glutamine and alanine at diagnosis was predictive of outcome (p = 0.001), but these same results were not observed in the RVC cohort. The biochemical signature of feline CE in the RVC cohort was consistent with that identified in human and animal models of inflammatory bowel disease. The hydrolyzed protein diet had the same effect on the urinary metabolome of cats with CE at both sites. However, biomarkers that were predictive of dietary response at diagnosis differed between the 2 sites. This may be due to differences in disease severity, disease heterogeneity, factors unrelated to the disease or small sample size at both sites. As such, further studies utilizing larger number of cats are needed to corroborate these findings.

PSV-29 Plasma Citrulline Is Strongly Correlated with Jejunum and Ileum Citrulline Concentrations in Pigs at Weaning

Abstract Pigs at weaning are abruptly exposed to numerous stressors that negatively affect gut health. While the term gut health lacks a clear definition, it is best measured by its key functions, including nutrient digestion, absorption, and metabolism, mucosal immunity, and barrier function. The gut is the main endogenous source of citrulline, a potential biomarker of gut function. The objective of this study was to determine the relationship between plasma and intestinal concentrations of citrulline and citrulline precursors in pigs. Pigs (initial BW = 7,233 ± 683 g) were either weaned at 21 d age and euthanized at 23 d age (W; n = 9) or were not weaned, remained with the sow, and euthanized at 23 d age (NW; n = 9). At euthanasia, blood, jejunum, and ileum tissue was collected and snap-frozen in liquid nitrogen; segments of mid jejunum and distal ileum were collected for morphological analysis. Plasma and tissue glutamine (Gln), glutamate (Glu), proline (Pro), ornithine (Orn), and citrulline (Cit) concentrations were determined by reverse-phase HPLC following pre-column derivatization with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate. Data were analyzed with the generalized linear mixed model and correlation procedures of SAS (version 9.4). Pearson correlation coefficients between 0.50 and 0.69 were considered as moderate, between 0.70 and 0.89 as strong, and between 0.90 to 1 as very strong. Jejunum villus height was reduced in W compared with NW pigs (370 versus 246 ± 18 µm; P < 0.001), whereas ileum villus height was not different between NW and W pigs (257 versus 215 ± 27 µm; P = 0.27). Among precursors for gut Cit synthesis, plasma Pro was strongly correlated with jejunum Pro (r = 0.83; P < 0.001) and very strongly correlated with ileum Pro (r = 0.91; P < 0.001). Plasma Glu was moderately correlated with ileum Glu (r = 0.58; P = 0.014), but not with jejunum Glu (r = 0.18, P = 0.48), whereas plasma Gln was moderately correlated with ileum Gln (r = 0.57; P = 0.016) and strongly correlated with jejunum Gln (r = 0.80; P < 0.001). Plasma Orn was strongly correlated with both jejunum Orn (r = 0.73; P < 0.001) and ileum Orn (r = 0.78; P < 0.001). Plasma Cit was strongly correlated with jejunum Cit (r = 0.77; P < 0.001) and very strongly correlated with ileum Cit (r = 0.95; P < 0.001). Plasma Cit can be used to estimate gut Cit content and may be predictive of gut function in nursery pigs undergoing weaning stress.

272 The Effect of Increasing Standardized Ileal Digestible Methionine Intake on Whole-Body Nitrogen Retention and Plasma Amino Acids, Homocysteine, and Glutathione of Gilts in Late Gestation

Abstract Gestating gilts (n = 70; 166 ± 13 kg initial body weight at d 31 of gestation) were used to determine the dietary standardized ileal digestible (SID) Methionine (Met) content required to optimize whole-body nitrogen (N) retention versus the appearance of biomolecules derived via Met metabolism. On d 102 of gestation, gilts were randomly assigned to one of seven dietary treatments that provided between 50 and 150% of estimated SID Met requirements for late gestation gilts (0.10 to 0.30% SID Met). All other indispensable amino acids were supplied at least 20% above estimated requirements (NRC, 2012). A N balance (total urine collection and fecal grab sampling) was conducted for each gilt between days 109 and 112 of gestation, blood samples were collected on day 109 after a 24-h fasting period for analyses of plasma amino acids, homocysteine (Hcys), and reduced glutathione (GSH). Contrast statements were used to determine linear and quadratic effects of dietary SID Met levels. Linear and quadratic broken-line and polynomial quadratic models were used to determine the optimum level of SID Met for whole-body N retention and plasma concentrations of Hcys and GSH. Whole-body N retention increased with increasing dietary Met (linear and quadratic; P < 0.001; Table 1). Plasma concentrations of Hcys increased with increasing dietary Met (linear; P < 0.05). Glutathione tended to decrease and then increase at dietary SID Met greater than 0.20% (quadratic; P = 0.061; Table 2). Plasma glutamine increased with increasing dietary SID Met (linear; P < 0.01). Histidine increased then decreased at dietary SID Met greater than 0.20% (quadratic; P < 0.05), other amino acids were not influenced by dietary treatment. Linear and quadratic broken-line models described a lower breaking point for whole-body N retention, plasma Hcys, and plasma GSH compared with the quadratic polynomial model (0.154% and 0.155% vs. 0.226%, 0.185% and 0.188% vs. 0.328%, and 0.114% and 0.124% vs. 0.224% SID Met, respectively). The Bayesian information criterion (BIC) indicated that the quadratic polynomial model best fit the data versus the linear and quadratic broken-line models for plasma GSH (BIC 317.9 vs. 320.3 and 322.6, respectively; Graphic 1). However, the fits were similar among models for whole-body N retention (BIC 385.2 vs. 384.6 and 386.9, respectively; Graphic 2) and Hcys (BIC 465.5 vs. 465.6 and 467.9, respectively; Graphic 3). Based on the best fit (quadratic polynomial) model 0.226% SID Met is required to optimize whole-body N retention for late gestation gilts which is greater than that recommended by the NRC (2012; 0.20% SID Met). It appears that gilts have further capacity for Met transmethylation since the plasma Hcys breakpoint occurred at a greater dietary SID Met level than for whole-body N retention, though the impact on transsulfuration and remethylation pathways cannot be discounted. Therefore, greater feeding levels of SID Met might be required to maximize both protein and non-protein utilization of Met.

Sijunzi Tang improves gefitinib resistance by regulating glutamine metabolism

Lung cancer is a major health concern and significant barrier to human well-being and social development. Although targeted therapy has shown remarkable progress in the treatment of lung cancer, the emergence of drug resistance has limited its clinical efficacy. Sijunzi Tang (SJZ) is a classical Chinese herbal formula known for tonifying qi and nourishing the lungs, has been recognized for its potential in lung cancer management. However, the underlying mechanism of its combined use with anti-cancer drugs remains unclear. Here, we investigated the anti-lung cancer efficacy and underlying mechanisms of the combination of gefitinib and SJZ in gefitinib-resistant human lung adenocarcinoma cells (PC-9/GR). We conducted in vitro and in vivo experiments using histopathology and targeted metabolomics approaches. Our results demonstrated that the combination of SJZ and gefitinib exhibited synergistic effects on tumor growth inhibition in PC-9/GR-bearing nude mice. Notably, the co-administration of SJZ and gefitinib synergistically promoted tumor cell apoptosis, potentially through the regulation of BAX and BCL-2 expression. Immunohistochemistry and western blot analysis found down-regulation of GLS, GS, and SLC1A5 expression in the co-administration group compared to the control and the individual treatment groups. Targeted metabolomics revealed significant alterations in the plasma glutamine metabolic markers glutamine, alanine, succinate, glutamate, and pyruvate. Of the glutamine metabolism markers measured in tumor tissues, glutamine and pyruvate demonstrated significant differences across the treatment groups. These findings suggest that administration of SJZ improves gefitinib resistance in the treatment of lung cancer without toxic effects. Moreover, SJZ may affect glutamine metabolism by regulating key targets involved in glutamine metabolism (SLC1A5, GLS, and GS) and modulating the levels of related metabolic markers, ultimately reducing gefitinib resistance.

Monitoring the treatment of urea cycle disorders using phenylbutyrate metabolite analyses: Still many lessons to learn

Medications that elicit an alternate pathway for nitrogen excretion such as oral sodium phenylbutyrate (NaPBA) and glycerol phenylbutyrate (GPB) and intravenous sodium phenylacetate (NaPAA) are important for the management of urea cycle disorders (UCDs). Plasma concentrations of their primary metabolite, phenylacetate (PAA), as well as the ratio of PAA to phenylacetylglutamine (PAGN) are useful for guiding dosing and detecting toxicity. However, the frequency of toxic elevations of metabolites and associated clinical covariates is relatively unknown. A retrospective analysis was conducted on 1255 plasma phenylbutyrate metabolite measurements from 387 individuals. An additional analysis was also conducted on a subset of 68 individuals in whom detailed clinical information was available. In the course of these analyses, abnormally elevated plasma PAA and PAA:PAGN were identified in 39 individuals (4.15% of samples) and 42 individuals (4.30% of samples), respectively. Abnormally elevated PAA and PAA:PAGN values were more likely to occur in younger individuals and associate positively with dose of NAPBA and negatively with plasma glutamine and glycine levels. These results demonstrate that during routine clinical management, the majority of patients have PAA levels that are deemed safe. As age is negatively associated with PAA levels however, children undergoing treatment with NaPBA may need close monitoring of their phenylbutyrate metabolite levels.

Association between Neuroligin-1 polymorphism and plasma glutamine levels in individuals with autism spectrum disorder

Unravelling the relationships between candidate genes and autism spectrum disorder (ASD) phenotypes remains an outstanding challenge. Endophenotypes, defined as inheritable, measurable quantitative traits, might provide intermediary links between genetic risk factors and multifaceted ASD phenotypes. In this study, we sought to determine whether plasma metabolite levels could serve as endophenotypes in individuals with ASD and their family members. We employed an untargeted, high-resolution metabolomics platform to analyse 14,342 features across 1099 plasma samples. These samples were collected from probands and their family members participating in the Autism Genetic Resource Exchange (AGRE) (N=658), compared with neurotypical individuals enrolled in the PrecisionLink Health Discovery (PLHD) program at Boston Children's Hospital (N=441). We conducted a metabolite quantitative trait loci (mQTL) analysis using whole-genome genotyping data from each cohort in AGRE and PLHD, aiming to prioritize significant mQTL and metabolite pairs that were exclusively observed in AGRE. Within the AGRE group, we identified 54 significant associations between genotypes and metabolite levels (P<5.27×10-11), 44 of which were not observed in the PLHD group. Plasma glutamine levels were found to be associated with variants in the NLGN1 gene, a gene that encodes post-synaptic cell-adhesion molecules in excitatory neurons. This association was not detected in the PLHD group. Notably, a significant negative correlation between plasma glutamine and glutamate levels was observed in the AGRE group, but not in the PLHD group. Furthermore, plasma glutamine levels showed a negative correlation with the severity of restrictive and repetitive behaviours (RRB) in ASD, although no direct association was observed between RRB severity and the NLGN1 genotype. Our findings suggest that plasma glutamine levels could potentially serve as an endophenotype, thus establishing a link between the genetic risk associated with NLGN1 and the severity of RRB in ASD. This identified association could facilitate the development of novel therapeutic targets, assist in selecting specific cohorts for clinical trials, and provide insights into target symptoms for future ASD treatment strategies. This work was supported by the National Institute of Health (grant numbers: R01MH107205, U01TR002623, R24OD024622, OT2OD032720, and R01NS129188) and the PrecisionLink Biobank for Health Discovery at Boston Children's Hospital.

1581-P: Systemic Alteration of Amino Acids Metabolism in Glutamate Dehydrogenase Gain-of-Function Mutation Knockin Mice

Patients with gain-of-function (GoF) mutations of glutamate dehydrogenase (GDH) have protein-sensitive hypoglycemia, hyperammonemia, epilepsy, and intellectual disability (HI/HA syndrome). Studies of mouse models with a beta-cell specific expression of H454Y hGDH suggest that the mechanisms of HI are caused by increased glutaminolysis induced by GDH GoF in islets. However, the mechanism of hyperammonemia is still unknown. In order to study the systemic effects of GDH GoF, H454Y GDH knockin mice (H454Y-GDH-KI) were created. Enzyme kinetic of GDH in the brain, kidney and liver confirmed that H454Y was successfully expressed with impaired GTP inhibition. H454Y-GDH-KI mice have a ~2.5-fold elevation of plasma ammonia and fasting hypoglycemia, similar to HI/HA patients. Tissues (brain, liver and kidney) and plasma amino acids profiles were determined by LC-MS. Compared to wildtype, the amino acids profile in the kidney was unaltered in KI mice. In contrast, KI liver had 60% lower glutamine, unchanged glutamate and aspartate, increased branch chain amino acids, etc. The glutamine of KI brain was 40% lower than the wildtype, glutamate and GABA was unchanged. Interestingly, plasma glutamine in KI mice was 30% higher compared to controls. A similar phenomenon has also been observed in HI/HA patients. We hypothesize that hyperammonemia is mainly caused by the increased glutaminolysis in KI liver. Higher plasma glutamine can be explained by the increased activity of tissue glutamine synthetase (GS). GS and glutamine serve as an ammonia sink, which is the main mechanism for the removal of increased ammonia in KI mice. We therefore applied the GS inhibitor, methionine sulfoximine (MSO) to KI mice. MSO significantly increased ammonia levels in KI mice after a single dose of injection. These studies in H454Y-GDH-KI mice suggest that GDH GoF in the liver is the main cause of hyperammonemia. GS plays an important role in ammonia removal. Disclosure C.Su: None. D.Han: Employee; Nanjing AscendRare Pharmaceutical Technology. S.Meng: Employee; Nanjing AscendRare Pharmaceutical Technology. Q.Zhu: Employee; Nanjing AscendRare Pharmaceutical Technology. X.Zhou: Employee; Nanjing AscendRare Pharmaceutical Technology. H.Jiang: None. J.Li: None. C.Gong: None. C.Li: Employee; Hua Medicine, Nanjing AscendRare Pharmaceutical Technology. Funding Beijing Natural Science Foundation (L212037)

1601-P: Childhood Plasma Amino Acid Profiles Predict the 10-Year Risk of Nonalcoholic Fatty Liver Disease—The BCAMS Study

Background and Aims: Amino acid profiles have been proved a promising tool to identify novel biomarkers and insight of the mechanisms of metabolic diseases; however, date on youth was still limited, particularly nonalcoholic fatty liver disease (NAFLD). We aimed to prospectively investigate if there exist any association between childhood plasma amino acid profiles and adulthood NAFLD, and explore the early predictor and the underlying mechanism for the development of hepatic steatosis. Methods: A total of 307 subjects aged 12.1±3.0 years at baseline were enrolled in this study at 10-year follow-up, recruited from the Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study cohort, including 99 NAFLD patients and 208 normal controls. Thirty-two amino acids (AAs) in fasting plasma at baseline were evaluated by liquid chromatograph-mass spectrometry. NAFLD was diagnosed by abdominal ultrasonography at follow-up. Results: Among the 32 qualified AAs, 14 AAs showed significant differences (p&amp;lt;0.05) between NAFLD and normal controls, including four AAs survived Bonferroni correction (p&amp;lt;0.0016). Adjustment for age, gender and lifestyle factors, there were 10 AAs remain significant, including alanine, asparagine, glutamine, glycine, isoleucine, tyrosine, serine and threonine etc. Further adjustment for BMI, lower levels of asparagine (OR: 0.62, 95% CI: 0.44-0.87), glutamine (OR: 0.73, 95% CI: 0.53-0.99) and serine (OR: 0.71, 95% CI: 0.51-0.98) remain significant predictors of NAFLD at the 10-year follow-up. Conclusion: Plasma amino acid profiles in childhood can predict risk of NAFLD in young adults. Plasma asparagine, glutamine and serine are likely to be early predictors of NAFLD independently of adiposity. Disclosure M.Li: None. S.Gao: None. Bcams group: n/a. Funding National High Level Hospital Clinical Research Funding (2022-PUMCH-C-014); National Natural Science Foundation of China (81970732, 82270924); Capital's Funds for Health Improvement and Research (2020-2Z-40117); CAMS Innovation Fund for Medical Sciences (C

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.

Low Plasma Citrulline Guiding the Diagnosis of a Mitochondrial Disorder.

A 3-month-old male presented with generalized seizures in the setting of a viral upper respiratory tract infection. The newborn screen (NBS) collected at 27 hours of life was normal. Initial evaluation was notable for lactic acidosis (lactate 4.1 mmol/L, reference interval [RI] 0.5–2.2 mmol/L; bicarbonate 12 mmol/L, RI 18–28 mmol/L). Cerebrospinal fluid analysis was normal. Brain magnetic resonance imaging (MRI) revealed T2 hyperintensities involving bilateral deep gray nuclei and upper brainstem regions suggestive of genetic or metabolic etiologies. Diffuse lactate elevation was also observed by magnetic resonance spectroscopy, consistent with a diagnosis of Leigh syndrome (LS, OMIM# 256000). Due to concerns for LS, a metabolic evaluation was obtained. The plasma amino acid (PAA) profile was notable for reduced citrulline (3 µmol/L, RI 7–47 µmol/L) in the context of normal glutamine (444 µmol/L, RI 285–832 µmol/L), leading to an abnormal plasma glutamine/citrulline ratio (148, RI <25). Given normal plasma ammonia and glutamine, a proximal urea cycle defect was unlikely. Low citrulline is also observed with short intestinal length and impaired intestinal absorption; however, the patient did not exhibit abnormal bowel function. Urine organic acid (UOA) analysis revealed elevated propionate metabolites (i.e., propionylglycine and methylcitrate) along with lactate, ketones, and tricarboxylic acid cycle metabolites (Fig.1). 3-Hydroxyisovaleric acid was normal, while 3-hydroxypropionic acid and 3-methylcrotonylglycine were not detected. The plasma acylcarnitine (PAC) profile was notably normal. Given the clinical and biochemical presentation, mitochondrial complex V deficiency mitochondrial type 1 (MC5DM1) caused by variants in MT-ATP6 (OMIM# 500015) was highly suspected (1, 2). Subsequent mitochondrial genome analysis of the proband’s blood revealed a pathogenic variant (m.8993T>G) in MT-ATP6 at 96% heteroplasmy, confirming a diagnosis of MC5DM1.

Arginine Dysregulation and Myocardial Dysfunction in a Mouse Model and Children with Chronic Kidney Disease.

Cardiovascular disease is the leading cause of death in chronic kidney disease (CKD). Arginine, the endogenous precursor for nitric oxide synthesis, is produced in the kidneys. Arginine bioavailability contributes to endothelial and myocardial dysfunction in CKD. Plasma from 129X1/SvJ mice with and without CKD (5/6th nephrectomy), and banked plasma from children with and without CKD were analyzed for amino acids involved in arginine metabolism, ADMA, and arginase activity. Echocardiographic measures of myocardial function were compared with plasma analytes. In a separate experiment, a non-specific arginase inhibitor was administered to mice with and without CKD. Plasma citrulline and glutamine concentrations correlated with multiple measures of myocardial dysfunction. Plasma arginase activity was significantly increased in CKD mice at 16 weeks vs. 8 weeks (p = 0.002) and ventricular strain improved after arginase inhibition in mice with CKD (p = 0.03). In children on dialysis, arginase activity was significantly increased vs. healthy controls (p = 0.04). Increasing ADMA correlated with increasing RWT in children with CKD (r = 0.54; p = 0.003). In a mouse model, and children, with CKD, arginine dysregulation correlates with myocardial dysfunction.