Histidine Metabolism and Function

Metabolic responses of the marine mussel Mytilus galloprovincialis after exposure to microplastics of different shapes and sizes

Microplastics (MP) are ubiquitous pollutants with diverse shapes, sizes, and characteristics that pose critical risks to marine organisms and the environment. In this study, we used the Mediterranean mussel Mytilus galloprovincialis as a marine benthic organism model to investigate the metabolic consequences of exposure to different polyethylene terephthalate MP sizes and shapes: round (27-32 μm), small fibers (200-400 μm), large fibers (3000 μm), small fragments (20 μm), medium fragments (45-75 μm), and large fragments (>150 μm). After exposure to high concentrations (100 mg L-1) of MP for 14 days, round and small fiber-type MP were highly accumulated in mussels. Metabolomic analysis revealed that exposure to round and small fiber-type MP induced significant changes in 150 metabolites. Partial least squares-discriminate analysis (PLS-DA) showed that the round and small fiber MP treatment groups displayed similar cluster patterns that differed from those of the control group. In addition, only 22 annotated metabolites related to histidine, valine, leucine, and isoleucine degradation/biosynthesis and vitamin B6 and aminoacyl-tRNA biosynthesis were significantly affected by round or small fiber-type MP. Among the histidine metabolites, round and small fiber-type MP upregulated the levels of L-histidine, L-glutamate, carnosine, imidazole-4-acetaldehyde, 4-imidazolone-5-propanoate, and methylimidazole acetaldehyde and downregulated methylimidazole acetic acid and N-formimino-L-glutamate. These results suggest novel insights into the potential pathways through which MP of specific sizes and shapes affect metabolic processes in mussels.

One-carbon metabolism and microbial pathogenicity

One-carbon metabolism (OCM) pathways are responsible for several functions, producing a number of one-carbon unit intermediates (formyl, methylene, methenyl, methyl) that are required for the synthesis of various amino acids and other biomolecules such as purines, thymidylate, redox regulators, and, in most microbes, folate. As humans must acquire folate from the diet, folate production is a target for antimicrobials such as sulfonamides. OCM impacts the regulation of microbial virulence such that in a number of instances, limiting the availability of para-aminobenzoic acid (pABA), an essential OCM precursor, causes a reduction in pathogenicity. Porphyromonas gingivalis, however, displays increased pathogenicity in response to lower pABA levels, and exogenous pABA exerts a calming influence on heterotypic communities of P. gingivalis with pABA-producing partner species. Differential responses to pABA may reflect both the physiology of the organisms and their host microenvironment. OCM plays an integral role in regulating the global rate of protein translation, where the alarmones ZMP and ZTP sense insufficient stores of intracellular folate and coordinate adaptive responses to compensate and restore folate to sufficient levels. The emerging interconnections between OCM, protein synthesis, and context-dependent pathogenicity provide novel insights into the dynamic host-microbe interface.

Mapping small metabolite changes after traumatic brain injury using AP-MALDI MSI

Traumatic brain injury (TBI) is an alteration of brain function caused by a sudden transmission of an external force to the head. The biomechanical impact induces acute and chronic metabolic changes that highly contribute to injury evolution and outcome. TBI heterogeneity calls for approaches allowing the mapping of regional molecular and metabolic changes underpinning disease progression, with mass spectrometry imaging (MSI) as an efficient tool to study the spatial distribution of small metabolites. In this study, we applied an innovative targeted atmospheric pressure-MALDI mass spectrometry imaging (AP-MALDI MSI) approach, starting from an extensive list of metabolites, representative of different metabolic pathways, individually validated on the tissue under analysis with original standards using 2,5-dihydroxybenzoic acid (DHB), to characterize the impact of TBI on regional changes to small metabolites in the brain. Brains from sham and TBI mice obtained 21 days post-injury were analyzed to examine the spatial metabolic profile of small metabolites belonging to different metabolic pathways. By a whole brain analysis, we identified four metabolites (alanine, lysine, histidine, and inosine) with higher abundance in TBI than sham mice. Within the TBI group, lysine, histidine, and inosine were higher in the hemisphere ipsilateral to the biomechanical impact vs. the contralateral one. Images showed a major involvement of the ipsilateral thalamus characterized by the increase of arginine, lysine, histidine, and inosine and a significant reduction of glutamic acid, and N-acetylaspartic acid compared to the contralateral thalamus. These findings indicate high-resolution imaging mass spectrometry as a powerful tool to identify region-specific changes after a TBI to understand the metabolic changes underlying brain injury evolution.

L-Histidine attenuates NEFA-induced inflammatory responses by suppressing Gab2 expression

Non-esterified fatty acids (NEFAs), key to energy metabolism, may become pathogenic at elevated levels, potentially eliciting immune reactions. Our laboratory's findings of reduced L-histidine in ketotic states, induced by heightened NEFA concentrations, suggest an interrelation with NEFA metabolism. This observation necessitates further investigation into the mitigating role of L-histidine on the deleterious effects of NEFAs. Our study unveiled that elevated NEFA concentrations hinder the proliferation of Bovine Mammary Epithelial Cells (BMECs) and provoke inflammation in a dose-responsive manner. Delving into L-histidine's influence on BMECs, RNA sequencing revealed 2124 genes differentially expressed between control and L-histidine-treated cells, with notable enrichment in pathways linked to proliferation and immunity, such as cell cycle and TNF signaling pathways. Further analysis showed that L-histidine treatment positively correlated with an increase in EdU-555-positive cell rate and significantly suppressed IL-6 and IL-8 levels (p < 0.05) compared to controls. Crucially, concurrent treatment with high NEFA and L-histidine normalized the number of EdU-555-positive cells and cytokine expression to control levels. Investigating the underlying mechanisms, Gab2 (Grb2-associated binder 2) emerged as a central player; L-histidine notably reduced Gab2 expression, while NEFA had the opposite effect (p < 0.05). Gab2 overexpression escalated nitric oxide (NO) production and IL6 and IL8 expression. However, L-histidine addition to Gab2-overexpressing cells resulted in NO concentrations indistinguishable from controls. Our findings collectively indicate that L-histidine can counteract NEFA-induced inflammation in BMECs by inhibiting Gab2 expression, highlighting its therapeutic potential against NEFA-related metabolic disturbances.

Cox7a1 controls skeletal muscle physiology and heart regeneration through complex IV dimerization

The oxidative phosphorylation (OXPHOS) system is intricately organized, with respiratory complexes forming super-assembled quaternary structures whose assembly mechanisms and physiological roles remain under investigation. Cox7a2l, also known as Scaf1, facilitates complex III and complex IV (CIII-CIV) super-assembly, enhancing energetic efficiency in various species. We examined the role of Cox7a1, another Cox7a family member, in supercomplex assembly and muscle physiology. Zebrafish lacking Cox7a1 exhibited reduced CIV2 formation, metabolic alterations, and non-pathological muscle performance decline. Additionally, cox7a1-/- hearts displayed a pro-regenerative metabolic profile, impacting cardiac regenerative response. The distinct phenotypic effects of cox7a1-/- and cox7a2l-/- underscore the diverse metabolic and physiological consequences of impaired supercomplex formation, emphasizing the significance of Cox7a1 in muscle maturation within the OXPHOS system.

Iridium(III) solvent complex-based electrogenerated chemiluminescence method for the detection of 3-methylhistidine in urine

3-Methylhistidine (3-MeHis) is increasingly used as an indicator of muscle protein breakdown. The development of a sensitive, simple, and non-invasive method for 3-MeHis assay is important in clinical practice. Herein, a sensitive, simple, and non-invasive electrogenerated chemiluminescence (ECL) method was proposed for the quantitation of 3-MeHis in urine by using an iridium(III) solvent complex ([Ir(dfppy)2(DMSO)Cl], dfppy = 2-(2,4-difluorophenyl)pyridine, Ir-DMSO) as a signal reagent. The photoluminescence (PL) and ECL responses of Ir-DMSO to 3-MeHis were studied. The ECL intensity of Ir-DMSO was enhanced in the presence of 3-MeHis because of the coordination recognition between Ir-DMSO and the imidazole group of 3-MeHis. Based on the enhancement of ECL intensity, 3-MeHis can be sensitively detected in the range of 5 to 25 μM. The detection limit was 0.4 μM. This is the first report of an ECL method for the quantitation of 3-MeHis. Further, to investigate the feasibility of the Ir-DMSO-based ECL method in practical applications, the developed ECL method was applied for 3-MeHis assay in urine samples of 28 healthy volunteers and 2 patients. The urine samples from patients hospitalized with obesity and kidney disease and healthy individuals were distinguished by the ECL responses of Ir-DMSO. The proposed ECL method based on the coordination recognition between iridium(III) solvent complex and the imidazole group of 3-MeHis allows inexpensive, fast, non-invasive, and sensitive detection of 3-MeHis in urine, which is promising for assessing large volumes of patients for routine analysis in clinical practices.

Metabolomics Combined with Physiology and Transcriptomics Reveal the Response of Samsoniella hepiali to Key Metabolic Pathways and Its Degradation Mechanism during Subculture

During the subculture of filamentous fungi, obvious signs of degradation occur which affect the growth and development of the strain, change the content of metabolites, and interfere with gene expression. However, the specific molecular mechanism of filamentous fungi degradation is still unclear. In this study, a filamentous fungus Samsoniella hepiali was used as the research object, and it was continuously subcultured. The results showed that when the strain was subcultured to the F8 generation, the strain began to show signs of degradation, which was manifested by affecting the apparent morphology, reducing the growth rate and sporulation, and destroying the antioxidant system. Further transcriptome and metabolomics analyses were performed, and the results showed differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs) that were mainly enriched in four metabolic pathways: ABC transporters; fatty acid degradation; alanine, aspartate, and glutamate metabolism; and purine metabolism. Many of the metabolites that were significantly enriched in different pathways may mainly be regulated by genes belonging to proteins and enzymes, such as Abcd3, Ass1, and Pgm1. At the same time, in the process of subculture, many genes and metabolites that can induce apoptosis and senescence continue to accumulate, causing cell damage and consuming a lot of energy, which ultimately leads to the inhibition of mycelial growth. In summary, this study clarified the response of S. hepiali strains to key metabolic pathways during subculture and some reasons for the degradation of strains.

Investigating the Impact of SN-38 on Mouse Brain Metabolism Based on Metabolomics

Purpose

SN-38 (7-ethyl-10-hydroxycamptothecin), the active metabolite of irinotecan, has been extensively studied in drug delivery systems. However, its impact on neural metabolism remains unclear. This study aims to investigate the toxic effects of SN-38 on mouse brain metabolism.

Methods

Male mice were divided into an SN-38 group and a control group. The SN-38 group received SN-38 (20 mg/kg/day) via intraperitoneal injection, while the control group was given an equal volume of a blank solvent mixture (DMSO and saline, ratio 1:9). Gas chromatography-mass spectrometry (GC-MS) was employed to analyze differential metabolites in the cortical and hippocampal regions of the SN-38-treated mice.

Results

SN-38 induced metabolic disturbances in the central nervous system. Eighteen differential metabolites were identified in the hippocampus and twenty-four in the cortex, with six common to both regions. KEGG pathway enrichment analysis revealed statistically significant alterations in six metabolic pathways in the hippocampus and ten in the cortex (P<0.05).

Conclusion

This study is the first to demonstrate the neurotoxicity of SN-38 in male mice through metabolomics. Differential metabolites in the hippocampal and cortical regions were closely linked to purine metabolism, pyrimidine metabolism, amino acid metabolism, and glyceride metabolism, indicating disruptions in the blood-brain barrier, energy metabolism, and central signaling pathways.

Understanding the Specific Implications of Amino Acids in the Antibody Development

As the demand for immunotherapy to treat and manage cancers, infectious diseases and other disorders grows, a comprehensive understanding of amino acids and their intricate role in antibody engineering has become a prime requirement. Naturally produced antibodies may not have the most suitable amino acids at the complementarity determining regions (CDR) and framework regions, for therapeutic purposes. Therefore, to enhance the binding affinity and therapeutic properties of an antibody, the specific impact of certain amino acids on the antibody's architecture must be thoroughly studied. In antibody engineering, it is crucial to identify the key amino acid residues that significantly contribute to improving antibody properties. Therapeutic antibodies with higher binding affinity and improved functionality can be achieved through modifications or substitutions with highly suitable amino acid residues. Here, we have indicated the frequency of amino acids and their association with the binding free energy in CDRs. The review also analyzes the experimental outcome of two studies that reveal the frequency of amino acids in CDRs and provides their significant correlation between the outcomes. Additionally, it discusses the various bond interactions within the antibody structure and antigen binding. A detailed understanding of these amino acid properties should assist in the analysis of antibody sequences and structures needed for designing and enhancing the overall performance of therapeutic antibodies.

Mesenchymal stem cell-derived exosomes promote tissue repair injury in rats with liver trauma by regulating gut microbiota and metabolism

OBJECTIVE

The effects of mesenchymal stem cells (MSCs) and MSC-derived exosomes (MSC-exos) on serum metabolites and intestinal microbiota in rats after liver trauma were discussed.

METHODS

Adult Wistar Albino rats were assigned into control, model (liver trauma), MSCs, and MSC-exos groups (n = 6). The study examined changes in the inflammatory environment in liver tissues were analyzed by histological examination and analysis of macrophage phenotypes. Alterations in serum metabolites were determined by untargeted metabonomics, and gut microbiota composition was characterized by 16S rDNA sequencing. Correlations between specific gut microbiota, metabolites, and inflammatory response were calculated using Spearman correlation analysis.

RESULTS

Rats with liver trauma after MSCs and MSC-exos treatment exhibited attenuated inflammatory infiltration and necrosis in liver tissues. MSCs and MSC-exos treatment reduced the proportion of M1 macrophages, accompanied by a decrease in inducible nitric oxide synthase (iNOS) and tumor necrosis factor-alpha (TNF-α) levels. Furthermore, MSCs and MSC-exos treatment expanded the proportion of M2 macrophages, accompanied by an increase in arginase-1 (Arg-1) and interleukin-10 (IL-10) levels. The beneficial effects of MSC-exo treatment on rats with liver trauma were superior to those of MSC treatment. The composition and abundance of the gut microbiota and metabolites were altered in pathological rats, whereas MSC and MSC-exo intervention partially restored specific gut microbiota and metabolite alterations. At the phylum level, alterations in Bacteroidota, Proteobacteria, and Verrucomicrobiota were observed after MSC and MSC-exo intervention. At the genus level, Intestinimonas, Alistipes, Aerococcus, Faecalibaculum, and Lachnospiraceae_ND3007_group were the main differential microbiota. 6-Methylnicotinamide, N-Methylnicotinamide, Glutathione, oxidized, ISOBUTYRATE, ASCORBATE, EICOSAPENTAENOATE, GLYCEROL 3-PHOSPHATE, and Ascorbate radical were selected as important differential metabolites. There was a clear correlation between Ascorbate, Intestinimonas/Faecalibaculum and inflammatory cytokines.

CONCLUSION

MSC-exos promoted the repair of tissue damage in rats with liver trauma by regulating serum metabolites and intestinal microbiota, providing new insights into how MSC-exos reduced inflammation in rats with liver trauma.

Roles of blood metabolites in mediating the relationship between vitiligo and autoimmune diseases: Evidence from a Mendelian randomization study

OBJECTIVE

This study employed Mendelian Randomization (MR) to investigate the causal relationship between genetic susceptibility to vitiligo and the risk of various autoimmune diseases, along with the mediating role of blood metabolites.

METHODS

We performed two-sample MR analyses using aggregated genome-wide association studies (GWAS) data on 486 blood metabolites, vitiligo, and nine autoimmune diseases to investigate blood metabolites' causal effects on the susceptibility of vitiligo and the associations of vitiligo with nine autoimmune comorbidities. We also applied multivariable MR to unravel metabolites by which vitiligo influences the pathogenesis of autoimmune diseases.

RESULTS

Our findings indicate that vitiligo amplified the risk of several autoimmune diseases, including rheumatoid arthritis (OR 1.17; 95 % CI 1.08-1.27), psoriasis (OR 1.10; 95 % CI 1.04-1.17), type 1 diabetes (OR 1.41; 95 % CI 1.23-1.63), pernicious anemia (OR 1.23; 95 % CI 1.12-1.36), autoimmune hypothyroidism (OR 1.19; 95 % CI 1.11-1.26), alopecia areata (OR 1.22; 95 % CI 1.10-1.35), and autoimmune Addison's disease (OR 1.22; 95 % CI 1.12-1.33). Additionally, our analysis identified correlations with vitiligo for 14 known (nine risk, five protective) and seven uncharacterized serum metabolites. After adjusting for genetically predicted levels of histidine and pyruvate, the associations between vitiligo and these diseases were attenuated.

CONCLUSIONS

We substantiated vitiligo's influence on susceptibility to seven autoimmune diseases and conducted a thorough investigation of serum metabolites correlated with vitiligo. Histidine and pyruvate are potential mediators of vitiligo associated with autoimmune diseases.By combining metabolomics with genomics, we provide new perspectives on the etiology of vitiligo and its immune comorbidities.

Tryptophan Promotes the Production of Xanthophyll Compounds in Yellow Abdominal Fat through HAAO

Abdominal fat, which in the past was often regarded as waste and discarded, has in recent years been used as a fat source to produce meat by-products. Yellow abdominal fat has higher economic value. Therefore, improving the color of abdominal fat plays an important role in improving the appearance of meat products. This study aimed to identify the contributors and the regulatory network involved in the formation of yellow and white color in abdominal fat. We found that four xanthophyll compounds were significantly different in yellow and white abdominal fat chicken, including zeaxanthin, lutein, canthaxanthin, and β-cryptoxanthin. There were 551 different and 8 common metabolites significantly correlated with these 4 xanthophyll compounds. Similarly, a total of 54 common genes were identified in 4 common related pathways (Complement and coagulation cascades, Metabolic pathways, PPAR signaling pathway, Carbon metabolism) of the 8 common metabolites. The high expression of HAAO in the yellow abdominal fat group leads to the degradation of tryptophan and its intermediate 5-hydroxyindole, and subsequently to the formation of the four xanthophyll compounds. This process is also regulated by tyrosine, kynurenine 3-monooxygenase (KMO), homogentisate 1, 2-dioxygenase (HGD), etc. Together, these findings show the effect of tryptophan on abdominal fat color, as well as a negative regulatory effect of HAAO and 5-hydroxyindole on the production of xanthophyll compounds involved in abdominal fat coloration.

Metabolic profiling of murine radiation-induced lung injury with Raman spectroscopy and comparative machine learning

Radiation-induced lung injury (RILI) is a dose-limiting toxicity for cancer patients receiving thoracic radiotherapy. As such, it is important to characterize metabolic associations with the early and late stages of RILI, namely pneumonitis and pulmonary fibrosis. Recently, Raman spectroscopy has shown utility for the differentiation of pneumonitic and fibrotic tissue states in a mouse model; however, the specific metabolite-disease associations remain relatively unexplored from a Raman perspective. This work harnesses Raman spectroscopy and supervised machine learning to investigate metabolic associations with radiation pneumonitis and pulmonary fibrosis in a mouse model. To this end, Raman spectra were collected from lung tissues of irradiated/non-irradiated C3H/HeJ and C57BL/6J mice and labelled as normal, pneumonitis, or fibrosis, based on histological assessment. Spectra were decomposed into metabolic scores via group and basis restricted non-negative matrix factorization, classified with random forest (GBR-NMF-RF), and metabolites predictive of RILI were identified. To provide comparative context, spectra were decomposed and classified via principal component analysis with random forest (PCA-RF), and full spectra were classified with a convolutional neural network (CNN), as well as logistic regression (LR). Through leave-one-mouse-out cross-validation, we observed that GBR-NMF-RF was comparable to other methods by measure of accuracy and log-loss (p > 0.10 by Mann-Whitney U test), and no methodology was dominant across all classification tasks by measure of area under the receiver operating characteristic curve. Moreover, GBR-NMF-RF results were directly interpretable and identified collagen and specific collagen precursors as top fibrosis predictors, while metabolites with immune and inflammatory functions, such as serine and histidine, were top pneumonitis predictors. Further support for GBR-NMF-RF and the identified metabolite associations with RILI was found as CNN interpretation heatmaps revealed spectral regions consistent with these metabolites.

Genome-wide association studies of anserine and carnosine contents in the breast meat of Korean native chickens

Histidine-containing dipeptides (HCDs), such as anserine and carnosine, are enormously beneficial to human health and contribute to the meat flavor in chickens. Meat quality traits, including flavor, are polygenic traits with medium to high heritability. Polygenic traits can be improved through a better understanding of their genetic mechanisms. Genome-wide association studies (GWAS) constitute an effective genomic tool to identify the significant single-nucleotide polymorphisms (SNPs) and potential candidate genes related to various traits of interest in chickens. This study identified potential candidate genes influencing the anserine and carnosine contents in chicken meat through GWAS. We performed GWAS of anserine and carnosine using the Illumina chicken 60K SNP chip (Illumina Inc., San Diego, CA) in 637 Korean native chicken-red-brown line (KNC-R) birds consisting of 228 males and 409 females. The contents of anserine and carnosine in breast meat of KNC-R chickens were investigated. The mean value of the anserine and carnosine are 29.12 mM/g and 10.69 mM/g respectively. The genomic heritabilities were moderate (0.24) for anserine and high (0.43) for carnosine contents. Four and nine SNPs were significantly (P < 0.05) associated with anserine and carnosine, respectively. Based on the GWAS result, the 30.6 to 31.9 Mb region on chicken chromosome 7 was commonly associated with both anserine and carnosine. Through the functional annotation analysis, we identified HNMT and HNMT-like genes as potential candidate genes associated with both anserine and carnosine. The results presented here will contribute to the ongoing improvement of meat quality to satisfy current consumer demands, which are based on healthier, better-flavored, and higher-quality chicken meat.

Metabolomic response to acute resistance exercise in healthy older adults by 1H-NMR

BACKGROUND

The favorable health-promoting adaptations to exercise result from cumulative responses to individual bouts of physical activity. Older adults often exhibit anabolic resistance; a phenomenon whereby the anabolic responses to exercise and nutrition are attenuated in skeletal muscle. The mechanisms contributing to age-related anabolic resistance are emerging, but our understanding of how chronological age influences responsiveness to exercise is incomplete. The objective was to determine the effects of healthy aging on peripheral blood metabolomic response to a single bout of resistance exercise and whether any metabolites in circulation are predictive of anabolic response in skeletal muscle.

METHODS

Thirty young (20-35 years) and 49 older (65-85 years) men and women were studied in a cross-sectional manner. Participants completed a single bout of resistance exercise consisting of eight sets of 10 repetitions of unilateral knee extension at 70% of one-repetition maximum. Blood samples were collected before exercise, immediately post exercise, and 30-, 90-, and 180-minutes into recovery. Proton nuclear magnetic resonance spectroscopy was used to profile circulating metabolites at all timepoints. Serial muscle biopsies were collected for measuring muscle protein synthesis rates.

RESULTS

Our analysis revealed that one bout of resistance exercise elicits significant changes in 26 of 33 measured plasma metabolites, reflecting alterations in several biological processes. Furthermore, 12 metabolites demonstrated significant interactions between exercise and age, including organic acids, amino acids, ketones, and keto-acids, which exhibited distinct responses to exercise in young and older adults. Pre-exercise histidine and sarcosine were negatively associated with muscle protein synthesis, as was the pre/post-exercise fold change in plasma histidine.

CONCLUSIONS

This study demonstrates that while many exercise-responsive metabolites change similarly in young and older adults, several demonstrate age-dependent changes even in the absence of evidence of sarcopenia or frailty.

TRIAL REGISTRATION

Clinical trial registry: ClinicalTrials.gov NCT03350906.

Cluster-specific associations between the gut microbiota and behavioral outcomes in preschool-aged children

BACKGROUND

The gut microbiota is recognized as a regulator of brain development and behavioral outcomes during childhood. Nonetheless, associations between the gut microbiota and behavior are often inconsistent among studies in humans, perhaps because many host-microbe relationships vary widely between individuals. This study aims to stratify children based on their gut microbiota composition (i.e., clusters) and to identify novel gut microbiome cluster-specific associations between the stool metabolomic pathways and child behavioral outcomes.

METHODS

Stool samples were collected from a community sample of 248 typically developing children (3-5 years). The gut microbiota was analyzed using 16S sequencing while LC-MS/MS was used for untargeted metabolomics. Parent-reported behavioral outcomes (i.e., Adaptive Skills, Internalizing, Externalizing, Behavioral Symptoms, Developmental Social Disorders) were assessed using the Behavior Assessment System for Children (BASC-2). Children were grouped based on their gut microbiota composition using the Dirichlet multinomial method, after which differences in the metabolome and behavioral outcomes were investigated.

RESULTS

Four different gut microbiota clusters were identified, where the cluster enriched in both Bacteroides and Bifidobacterium (Ba2) had the most distinct stool metabolome. The cluster characterized by high Bifidobacterium abundance (Bif), as well as cluster Ba2, were associated with lower Adaptive Skill scores and its subcomponent Social Skills. Cluster Ba2 also had significantly lower stool histidine to urocanate turnover, which in turn was associated with lower Social Skill scores in a cluster-dependent manner. Finally, cluster Ba2 had increased levels of compounds involved in Galactose metabolism (i.e., stachyose, raffinose, alpha-D-glucose), where alpha-D-glucose was associated with the Adaptive Skill subcomponent Daily Living scores (i.e., ability to perform basic everyday tasks) in a cluster-dependent manner.

CONCLUSIONS

These data show novel associations between the gut microbiota, its metabolites, and behavioral outcomes in typically developing preschool-aged children. Our results support the concept that cluster-based groupings could be used to develop more personalized interventions to support child behavioral outcomes. Video Abstract.

Tris(1,3-dichloro-2-propyl) phosphate disrupts cellular metabolism within human embryonic kidney (HEK293) cells

Tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used, additive flame retardant that migrates from end-use products, leading to ubiquitous exposure of humans around the world. However, little is known about whether TDCIPP disrupts the physiology of human embryonic cells. Therefore, the objective of this study was to determine whether TDCIPP alters cell viability, cellular metabolism, cytosine methylation, and reactive oxygen species (ROS) levels within human embryonic kidney (HEK293) cells. Relative to vehicle controls, TDCIPP (0.015-0.1225 µM) resulted in a concentration-dependent increase in cell viability, a finding that was driven by an increase in relative ATP abundance. Interestingly, TDCIPP (0.061-0.98 µM) increased the rate of glycolysis - an adaptive mechanism consistent with the Warburg effect exhibited by tumorigenic cells. Moreover, relative to vehicle-treated cells, TDCIPP (0.245-15.63 µM) exposure for 48 h (but not 24 h) resulted in a significant, concentration-dependent decrease in ROS in situ, and TDCIPP (0.245 µM) exposure significantly increased carnosine within the histidine metabolism pathway. However, TDCIPP did not affect global 5-methylcytosine (5-mC) methylation (0.015-15.63 µM), cell membrane integrity (0.061-0.98 µM), nor the abundance of mitochondria (0.061-1.95 µM). Overall, our findings with TDCIPP point to a novel mechanism of action that may be relevant to human embryonic stem cells.

Targeted metabolomic analysis of serum amino acids in heart failure patients

Heart failure (HF) has been recognized as a global epidemic with high rates of morbidity, hospitalization, and mortality. The role of amino acids, which provide the body with energy, in the development of HF is still unclear. The aim of this study was to explore changes in serum amino acids in patients with HF and identify potential biomarkers. First, the serum amino acid metabolism profiles of 44 patients with HF and 30 healthy controls (Con) were quantitatively measured. Then, candidate markers were identified through the utilization of T test, multivariate statistical analysis, and receiver operating characteristic (ROC) curve analysis. The results found that there were 11 amino acid levels that were significantly different between patients with HF and Con. Based on ROC curve analysis, the biomarkers of eight amino acids (Glutamic acid, Taurine, L-aspartic acid, L-ornithine, Ethanolamine, L-Serine, L-Sarcosine, and Cysteine) showed high sensitivity and specificity (AUC > 0.90), and binary logistic regression analysis was used in MetaboAnalyst 5.0. Among the amino acids examined, six exhibited notable alterations in accordance with the severity of HF. In conclusion, this study cannot only provide clinicians with an objective diagnostic approach for the early identification of HF, but also enhances comprehension of the underlying mechanisms involved in the pathogenesis of HF.

CLPP-Null Eukaryotes with Excess Heme Biosynthesis Show Reduced L-arginine Levels, Probably via CLPX-Mediated OAT Activation

The serine peptidase CLPP is conserved among bacteria, chloroplasts, and mitochondria. In humans and mice, its loss causes Perrault syndrome, which presents with growth deficits, infertility, deafness, and ataxia. In the filamentous fungus Podospora anserina, CLPP loss leads to longevity. CLPP substrates are selected by CLPX, an AAA+ unfoldase. CLPX is known to target delta-aminolevulinic acid synthase (ALAS) to promote pyridoxal phosphate (PLP) binding. CLPX may also influence cofactor association with other enzymes. Here, the evaluation of P. anserina metabolomics highlighted a reduction in arginine/histidine levels. In Mus musculus cerebellum, reductions in arginine/histidine and citrulline occurred with a concomitant accumulation of the heme precursor protoporphyrin IX. This suggests that the increased biosynthesis of 5-carbon (C5) chain deltaALA consumes not only C4 succinyl-CoA and C1 glycine but also specific C5 delta amino acids. As enzymes responsible for these effects, the elevated abundance of CLPX and ALAS is paralleled by increased OAT (PLP-dependent, ornithine delta-aminotransferase) levels. Possibly as a consequence of altered C1 metabolism, the proteome profiles of P. anserina CLPP-null cells showed strong accumulation of a methyltransferase and two mitoribosomal large subunit factors. The reduced histidine levels may explain the previously observed metal interaction problems. As the main nitrogen-storing metabolite, a deficiency in arginine would affect the urea cycle and polyamine synthesis. Supplementation of arginine and histidine might rescue the growth deficits of CLPP-mutant patients.

Revealing Medicinal Constituents of Bistorta vivipara Based on Non-Targeted Metabolomics and 16S rDNA Gene Sequencing Technology

Bistorta vivipara is a medicinal plant with a long history, but there are few studies on the effects of its medicinal components and endophytic bacteria on the accumulation of secondary metabolites. Therefore, in this study, non-targeted metabolomics techniques and 16s rDNA techniques were used to study B. vivipara from different regions. A total of 1290 metabolites and 437 differential metabolites were identified from all samples. Among them, flavonoids, isoflavonoids, and benzopyrans are the main medicinal components of B. vivipara; these have potential anticancer, antiviral, and antioxidant properties, as well as potential applications for the treatment of atrial fibrillation. In addition, irigenin, an important medicinal component, was identified for the first time. The endophytic bacterial communities in the root tissues of B. vivipara from different regions were also different in composition and richness. Hierarchical clustering heat map analysis showed that Proteobacteria and Actinobacteriota bacteria significantly affected the accumulation of many medicinal components in the roots of B. vivipara.

Baselining physiological parameters in three muscles across three equine breeds. What can we learn from the horse?

Mapping-out baseline physiological muscle parameters with their metabolic blueprint across multiple archetype equine breeds, will contribute to better understanding their functionality, even across species. Aims: 1) to map out and compare the baseline fiber type composition, fiber type and mean fiber cross-sectional area (fCSA, mfCSA) and metabolic blueprint of three muscles in 3 different breeds 2) to study possible associations between differences in histomorphological parameters and baseline metabolism. Methods: Muscle biopsies [m. pectoralis (PM), m. vastus lateralis (VL) and m. semitendinosus (ST)] were harvested of 7 untrained Friesians, 12 Standardbred and 4 Warmblood mares. Untargeted metabolomics was performed on the VL and PM of Friesian and Warmblood horses and the VL of Standardbreds using UHPLC/MS/MS and GC/MS. Breed effect on fiber type percentage and fCSA and mfCSA was tested with Kruskal-Wallis. Breeds were compared with Wilcoxon rank-sum test, with Bonferroni correction. Spearman correlation explored the association between the metabolic blueprint and morphometric parameters. Results: The ST was least and the VL most discriminative across breeds. In Standardbreds, a significantly higher proportion of type IIA fibers was represented in PM and VL. Friesians showed a significantly higher representation of type IIX fibers in the PM. No significant differences in fCSA were present across breeds. A significantly larger mfCSA was seen in the VL of Standardbreds. Lipid and nucleotide super pathways were significantly more upregulated in Friesians, with increased activity of short and medium-chain acylcarnitines together with increased abundance of long chain and polyunsaturated fatty acids. Standardbreds showed highly active xenobiotic pathways and high activity of long and very long chain acylcarnitines. Amino acid metabolism was similar across breeds, with branched and aromatic amino acid sub-pathways being highly active in Friesians. Carbohydrate, amino acid and nucleotide super pathways and carnitine metabolism showed higher activity in Warmbloods compared to Standardbreds. Conclusion: Results show important metabolic differences between equine breeds for lipid, amino acid, nucleotide and carbohydrate metabolism and in that order. Mapping the metabolic profile together with morphometric parameters provides trainers, owners and researchers with crucial information to develop future strategies with respect to customized training and dietary regimens to reach full potential in optimal welfare.

Salivary microbiota and metabolic phenotype of patients with recurrent aphthous ulcers

OBJECTIVES

Recurrent aphthous ulcer (RAU) is a prevalent oral mucosal disease, affecting around 20% of the global population. It can greatly impair the quality of life for affected individuals. However, the exact etiology of RAU remains unknown.

SUBJECTS AND METHODS

16S rRNA sequencing (16S rRNA-seq) and non-targeted liquid chromatography-mass spectrometry (LC-MS) were employed to investigate the salivary microbiota and metabolic phenotype between RAU patients (N = 61) and healthy controls (HCs) (N = 105).

RESULTS

Findings from 16S rRNA -seq indicated reduced oral microbial diversity in RAU patients compared to HCs, but increased interactions. Clinical variables did not show any significant association with the overall diversity of oral microbiota in RAU patients. However, significant correlations were observed between specific microorganisms and clinical variables. LC-MS results revealed dysregulation of amino acid, lipid, nucleotide, and caffeine metabolism in RAU patients. Furthermore, correlation analysis of 16S rRNA-seq and LC-MS data revealed a significant association between salivary microbiota and metabolites in RAU patients.

CONCLUSIONS

Our study revealed notable differences in salivary microbiota and metabolic profiles between RAU patients and HCs, indicating a strong link between oral microbiota dysbiosis, metabolic disturbances, and the onset and progression of RAU.

Amino acid kinetics in the critically ill

PURPOSE OF REVIEW

Stable isotope methods have been used for many years to assess whole body protein and amino acid kinetics in critically ill patients. In recent years, new isotope approaches and tracer insights have been developed. The tracer pulse approach has some advantages above the established primed-continuous tracer infusion approach because of the high amount of metabolic information obtained, easy applicability, and low tracer costs. Effects of disease severity and sex on amino acid kinetics in ICU patients will also be addressed.

RECENT FINDINGS

Current knowledge was synthesized on specific perturbations in amino acid metabolism in critically ill patients, employing novel methodologies such as the pulse tracer approach and computational modeling. Variations were evaluated in amino acid production and linked to severity of critical illness, as measured by SOFA score, and sex. Production of the branched-chain amino acids (BCAAs), glutamine, tau-methylhistidine and hydroxyproline were elevated in critical illness, likely related to increased transamination of the individual BCAAs or increased breakdown of proteins. Citrulline production was reduced, indicative of impaired gut mucosa function. Sex and disease severity independently influenced amino acid kinetics in ICU patients.

SUMMARY

Novel tracer and computational approaches have been developed to simultaneously measure postabsorptive kinetics of multiple amino acids that can be used in critical illness. The collective findings lay the groundwork for targeted individualized nutritional strategies in ICU settings aimed at enhancing patient outcomes taking into account disease severity and sex.

Effect of Air Drying on the Metabolic Profile of Fresh Wild and Artificial Cordyceps sinensis

Fresh and dried Cordyceps sinensis are widely used by the public for medicinal and health purposes. However, the differences between them have not been examined. In this study, fresh wild and artificial C. sinensis (WFC and AFC) were dried to obtain dried wild and artificial C. sinensis (WDC and ADC). Non-targeted GC-MS was used to analyze the metabolic profile characteristics of the four groups of samples. The results showed that air drying significantly altered the composition and content of C. sinensis, mainly in the form of higher abundance of organic acids and derivatives and lower abundance of lipids and lipid-like molecules in fresh C. sinensis. Hierarchical cluster analysis (HCA) and quantitative analyses showed that air drying increased the abundance of Valine, Zinniol, Urocanate, Vulpinic acid, and Uridine 5'-diphosphate, and decreased Xanthotoxol, Vitexin-4-o-glucoside, Val-trp, and Wogonin. These differentially accumulated metabolites (DAMs) were also shown to be potential biomarkers for C. sinensis. KEGG enrichment analysis identified lysine biosynthesis as the most significantly enriched pathway. Annotation of these DAMs to lysine biosynthesis revealed that citrate cycle and pyruvate metabolism entered lysine biosynthesis via 2-oxohlutarate and Homocitrate, respectively, resulting in significant enrichment of L-saccharopine and L-lysine content was significantly higher. Alanine, aspartate, and Glutamate metabolism synthesized more L-aspartate to promote L-lysine synthesis. Thus, high levels of L-lysine result in lysine degradation and pymolysine, which are the most active metabolic pathways during the drying of fresh C. sinensis and indirectly lead to differences in metabolic profiles.

Essential amino acid supplements ingestion has a positive effect on executive function after moderate-intensity aerobic exercise

Aerobic exercise acutely improves cognitive function (e.g., executive function (EF); memory recognition (MR)) and increases circulating brain-derived neurotrophic factor (BDNF). In addition, branched-chain amino acids (BCAA) ingestion acutely shortens the choice reaction time and increases brain BDNF. We examined whether the ingestion of essential amino acid (EAA) supplements (mainly composed of BCAA) would positively impact on cognitive function and circulating BDNF after moderate-intensity aerobic exercise. Twenty-two healthy young men received either an EAA supplements or the placebo (PL) 30 min before undergoing aerobic exercise. The participants performed a cycling exercise at 60% of peak oxygen uptake for 30 min. EF after aerobic exercise was better after the EAA treatment than after the PL treatment (P = 0.02). MR (P = 0.38 for response accuracy; P = 0.15 for reaction time) and circulating BDNF (P = 0.59) were not altered by EAA supplements. EF improvement was correlated with increases in some amino acids (leucine, isoleucine, valine, lysine, phenylalanine; all Ps < 0.05) that are potential substrates for synthesizing neurotransmitters in the brain. These results suggest that EAA supplements ingestion had a positive effect on EF after moderate-intensity aerobic exercise, while MR and BDNF were not altered.

Impact of cooking on the protein quality of Russet potatoes

Despite being low in crude protein, on a fresh weight basis, given their overall contribution to the North American diet, potatoes contribute approximately 2%-4% of the population's protein intake. However, the quality of the protein remains ill-defined. To that end, Russet potatoes were secured and subjected to various cooking conditions (raw [control], boiled, baked, microwaved, and fried [3, 6, and 9 min]) to determine the impact of cooking method on protein quality, as determined by amino acid score (AAS) and indices of in vivo true fecal protein digestibility (TFPD%; rodent bioassay) and in vitro protein digestibility (pH-drop, pH-Stat, and simulated gastrointestinal digestion both static and dynamic). The AAS of raw Russet potatoes was 0.67 ± 0.01, with histidine being the limiting AA. Frying led to a significant reduction in the AAS, however, other cooking methods yielded similar results to the raw control. The TFPD% of raw potato was low (40.5% ± 3.9%) and was significantly enhanced to over 80% with all cooking methods. Similar patterns were observed with all in vitro measures, however, all methods yielded higher values for the raw control samples. Final protein digestibility-corrected AAS (PDCAAS; product of AAS and TFPD%) values ranged from 0.27 (raw) to a high of 0.57 (boiled), with cooked values being comparable to other plant-based protein sources, including grains, and some nuts and pulses. In vitro PDCAAS values followed similar trends. This study defined the protein quality of cooked Russet potatoes and provides data for use in defining the quality of total protein consumed in the North American diet.

Differentiation of patients with and without prostate cancer using urine 1 H NMR metabolomics

Prostate cancer (PCa) is one of the most prevalent cancers in men worldwide. For its detection, serum prostate-specific antigen (PSA) screening is commonly used, despite its lack of specificity, high false positive rate, and inability to discriminate indolent from aggressive PCa. Following increases in serum PSA levels, clinicians often conduct prostate biopsies with or without advanced imaging. Nuclear magnetic resonance (NMR)-based metabolomics has proven to be promising for advancing early-detection and elucidation of disease progression, through the discovery and characterization of novel biomarkers. This retrospective study of urine-NMR samples, from prostate biopsy patients with and without PCa, identified several metabolites involved in energy metabolism, amino acid metabolism, and the hippuric acid pathway. Of note, lactate and hippurate-key metabolites involved in cellular proliferation and microbiome effects, respectively-were significantly altered, unveiling widespread metabolomic modifications associated with PCa development. These findings support urine metabolomics profiling as a promising strategy to identify new clinical biomarkers for PCa detection and diagnosis.

Muscle growth affects the metabolome of the pectoralis major muscle in red-winged tinamou (Rhynchotus rufescens)

The aim of the present study was to identify and quantify the metabolites (metabolome analysis) of the pectoralis major muscle in male red-winged tinamou (Rhynchotus rufescens) selected for growth traits. A selection index was developed for females [body weight (BW), chest circumference (CC), and thigh circumference (TC)] and males [BW, CC, TC, semen volume, and sperm concentration] in order to divide the animals into 2 experimental groups: selection group with a higher index (TinamouS) and commercial group with a lower index (TinamouC). Twenty male offspring of the 2 groups (TinamouS, n = 10; TinamouC, n = 10) were confined for 350 d. The birds were slaughtered and pectoralis major muscle samples were collected, subjected to polar and apolar metabolites extractions and analyzed by proton nuclear magnetic resonance (1H NMR) spectroscopy. Analysis of the polar metabolomic profile identified 65 metabolites; 29 of them were differentially expressed between the experimental groups (P < 0.05). The TinamouS groups exhibited significantly higher concentrations (P < 0.05) of 25 metabolites, including anserine, aspartate, betaine, carnosine, creatine, glutamate, threonine, 3-methylhistidine, NAD+, pyruvate, and taurine. Significantly higher concentrations of cysteine, beta-alanine, lactose, and choline were observed in the TinamouC group (P < 0.05). The metabolites identified in the muscle provided information about the main metabolic pathways (higher impact value and P < 0.05), for example, phenylalanine, tyrosine and tryptophan biosynthesis; alanine, aspartate and glutamate metabolism; D-glutamine and D-glutamate metabolism; β-alanine metabolism; glycine, serine and threonine metabolism; taurine and hypotaurine metabolism; histidine metabolism; phenylalanine metabolism. The NMR spectra of apolar fraction showed 8 classes of chemical compounds. The metabolome analysis shows that the selection index resulted in the upregulation of polyunsaturated fatty acids, unsaturated fatty acids, phosphocholines, phosphoethanolamines, triacylglycerols, and glycerophospholipids. The present study suggests that, despite few generations, the selection based on muscle growth traits promoted changes in metabolite concentrations in red-winged tinamou.

Changes in metabolite content in the kidneys and skeletal muscles of rats fed magnesium-restricted diets

A metabolomic study was performed on the kidneys and skeletal muscles of rats fed diets containing varying contents of Mg for 4 weeks. The kidneys are divided into two parts, the aerobic cortex and the anaerobic medulla, that differ in metabolism. The relative contents of 3-phosphoglyceric acid, 2-phosphoglyceric acid, and phosphoenolpyruvic acid increased with Mg restriction in both renal regions. In contrast, pyruvic acid content decreased with Mg restriction in the diets, suggesting an inhibitory conversion of phosphoenolpyruvic acid to pyruvic acid. The lactic acid content increased in both regions of the kidneys of Mg-restricted rats, implying changes towards a more glycolytic metabolism, possibly resulting from the impairment of mitochondrial function. There are two types of muscle fibers: glycolytic fast and oxidative slow muscle fibers. The soleus muscle consists of slow muscle fibers, whereas the gastrocnemius muscle consists of a combination of fast and slow muscle fibers. Similar to the changes in the kidneys, the contents of 3-phosphoglyceric acid, 2-phosphoglyceric acid, phosphoenolpyruvic acid, and lactic acid increased in the soleus and gastrocnemius muscles with dietary Mg restriction. Unlike in the kidney, pyruvic acid content increased in the soleus muscle in response to Mg restriction. Severe Mg restriction decreased contents of carnosine and its constituent β-alanine and increased the levels of purine derivatives such as xanthine and uric acid in the gastrocnemius muscle. The present study suggests a region-dependent sensitivity to dietary restriction of Mg, which may lead to the onset of various metabolic disorders.

Identification and validation of diagnostic biomarkers for intrahepatic cholestasis of pregnancy based on untargeted and targeted metabolomics analyses of urine metabolite profiles

BACKGROUND

Intrahepatic cholestasis of pregnancy (ICP) is a prevalent pregnancy-specific complication that presents with maternal itching and elevated serum bile acid levels. ICP is associated with unfavorable pregnancy outcomes, severely decreasing the pregnant woman's quality of life. Timely identification of ICP is crucial for effective management and improved outcomes.

METHODS

We collected urine samples from 8 patients with ICP and 8 healthy individuals. We used Liquid Chromatography-Mass Spectrometry (LC-MS) to detect metabolite expression levels, then conducted a series of bioinformatic analyses to explore the potential biological meanings of differentially expressed metabolites, and preliminarily discovered several candidate biomarkers. To validate these candidate biomarkers, we performed Gas Chromatography-Mass Spectrometry (GC-MS) detection and analyzed their diagnostic values using receiver operating characteristic (ROC) curve.

RESULTS

Untargeted metabolomics data showed that 6129 positive peaks and 6218 negative peaks were extracted from each specimen. OPLS-DA analysis and the heat map for cluster analysis showed satisfactory capability in discriminating ICP specimens from controls. Subsequent analysis extracted 64 significantly differentially expressed metabolites, which could be potential biomarkers for diagnosis of ICP. Based on the KEGG enrichment analyses, six candidate biomarkers were preliminarily identified. Two most promising biomarkers (3-hydroxypropionic acid and uracil) were validated by targeted metabolomics analyses with the area under the curve (AUC) of 0.920 and 0.850 respectively.

CONCLUSION

Based on preliminary screening from untargeted metabolomics and subsequent validation through targeted metabolomics, 3-hydroxypropionic acid and uracil were identified as promising diagnostic biomarkers for ICP.

A network analysis of depressive symptoms and metabolomics

BACKGROUND

Depression is associated with metabolic alterations including lipid dysregulation, whereby associations may vary across individual symptoms. Evaluating these associations using a network perspective yields a more complete insight than single outcome-single predictor models.

METHODS

We used data from the Netherlands Study of Depression and Anxiety (N = 2498) and leveraged networks capturing associations between 30 depressive symptoms (Inventory of Depressive Symptomatology) and 46 metabolites. Analyses involved 4 steps: creating a network with Mixed Graphical Models; calculating centrality measures; bootstrapping for stability testing; validating central, stable associations by extra covariate-adjustment; and validation using another data wave collected 6 years later.

RESULTS

The network yielded 28 symptom-metabolite associations. There were 15 highly-central variables (8 symptoms, 7 metabolites), and 3 stable links involving the symptoms Low energy (fatigue), and Hypersomnia. Specifically, fatigue showed consistent associations with higher mean diameter for VLDL particles and lower estimated degree of (fatty acid) unsaturation. These remained present after adjustment for lifestyle and health-related factors and using another data wave.

CONCLUSIONS

The somatic symptoms Fatigue and Hypersomnia and cholesterol and fatty acid measures showed central, stable, and consistent relationships in our network. The present analyses showed how metabolic alterations are more consistently linked to specific symptom profiles.

Glyphosate-based herbicide (GBH) challenged thermoregulation in lizards (Eremias argus), compensatory warming could mitigate this effect

Chemical pollution and global warming are two major threats to reptiles, and these two factors can interact with each other. Glyphosate have attracted worldwide attention due to their ubiquitous occurrence, yet their impact on reptiles remains unknown. We designed a crossover experiment with different external GBH exposures (control/GBH) x different environmental temperatures (current climate treatment/warmer climate treatment) over 60 days to simulate environmental exposure in the Mongolian Racerunner lizard (Eremias argus). Preferred body temperature and active body temperature data were collected to calculate the accuracy of thermoregulation, while liver detoxification metabolic enzymes, oxidative stress system function, and the non-targeted metabolome of the brain tissue were assessed. Warmer-treated lizards adjusted their physiological levels and behavioral strategies in response to increased ambient temperatures and maintained body temperature homeostasis at moderate thermal perturbations. GBH-treated lizards suffered from oxidative damage to the brain tissue and abnormal histidine metabolism, thus their thermoregulatory accuracy reduced. Interestingly, at elevated ambient temperatures, GBH treatment did not affect on their thermoregulatory, possibly through several temperature-dependent detoxification mechanisms. Importantly, this data suggested that the subtle toxicological effects of GBH may threaten increasingly thermoregulation behavior of E. argus with species-wide repercussions, as climate change and exposure time extension.

Causal associations of histidine and 12 site-specific cancers: a bidirectional Mendelian randomization study

An increasing number of studies indicate that cancer patients' histidine (HIS) circulating levels have changed. However, the causality between HIS and cancer is still not well established. Thus, to ascertain the causal link between HIS and cancers, we performed a bidirectional Mendelian randomization (MR) analysis. Summary-level data are derived from publicly available genome-wide association studies (GWAS). The causal effects were mainly estimated using the inverse-variance weighted method (IVW). The weighted-median (WM) method and MR-Egger regression were conducted as sensitivity analyses. In the forward-MR, we found malignant neoplasm of respiratory system and intrathoracic organs (OR: 1.020; 95% CI: 1.006-1.035; pIVW = 0.007) genetically associated with circulating HIS. And there was no significant genetic correlation between HIS and another 11 site-specific cancers using IVW method. In the reversed-MR, we did not observe the causal relationship between HIS and 12 site-specific cancers. Our findings help clarify that HIS, as a biomarker for malignant neoplasms of respiratory system and intrathoracic organs, is causal rather than a secondary biomarker of the cancerous progression. The mechanism between histidine and cancer progression deserves further investigation.

Multifaceted synergistic facilitation mechanism of conductive polymers in promoting selenite bioreduction and biological detoxification

Here, polypyrrole (PPY) was first used to the bioreduction of toxic selenite, while the acceleration effect and mechanism were explored. Experiment results suggested that PPY could enhance the selenite bioreduction from 0.42 to 1.04 mg/(L·h). The tests of electrochemical analysis and cytochrome c (cyt-c) content confirmed that PPY promoted the intracellular/intracellular electron transfer of Shewanella oneidensis·MR-1 in selenite bioreduction process. The enhancement of metabolic activity by PPY contributed to biological detoxification, which was manifested in the increased extracellular polymeric substances (EPS), adenosine triphosphate (ATP), electron transfer system activity (ETSA), membrane permeability and enzyme activity. Transcriptome analysis of DEGs, KEGG pathway enrichment and GO functional classification verified that the environmental adaptability of Shewanella oneidensis·MR-1 was enhanced with the addition of PPY. The transmission electron microscopy (TEM) images indicated that PPY promoted the biosynthesis of selenium nanoparticles (SeNPs), which was beneficial to reduce cell damage. Combined with the above results, a multifaceted synergistic facilitation mechanism based on "conductive cross-linking network" was elaborated from electron transfer, microbial metabolism and environmental adaptability. This study shed light the effect of conductive polymers (CPs) on selenite bioreduction and provided new insights into the bioremediation of toxic pollutants.

Systematic review on gene-sun exposure interactions in skin cancer

BACKGROUND

The risk of skin cancer is determined by environmental factors like ultraviolet radiation (UVR), personal habits like time spent outdoors and genetic factors. This review aimed to survey existing studies in gene-environment (GxE) interaction on skin cancer risk, and report on GxE effect estimates.

METHODS

We searched Embase, Medline (Ovid) and Web of Science (Core Collection) and included only primary research that reported on GxE on the risk of the three most common types of skin cancer: basal cell carcinoma (BCC), squamous cell carcinoma (SCC) and melanoma. Quality assessment followed the Newcastle-Ottawa Scale. Meta-analysis was not possible because no two studies examined the same interaction. This review was registered on PROSPERO (CRD42021238064).

RESULTS

In total 260 records were identified after exclusion of duplicates. Fifteen studies were included in the final synthesis-12 used candidate gene approach. We found some evidence of GxE interactions with sun exposure, notably, with MC1R, CAT and NOS1 genes in melanoma, HAL and IL23A in BCC and HAL and XRCC1 in SCC.

CONCLUSION

Sun exposure seems to interact with genes involved in pigmentation, oxidative stress and immunosuppression, indicating that excessive UV exposure might exhaust oxidative defence and repair systems differentially, dependent on genetic make-up. Further research is warranted to better understand skin cancer epidemiology and develop sun exposure recommendations. A genome-wide approach is recommended as it might uncover unknown disease pathways dependent on UV radiation.

Smartphone-Based High-Throughput Fluorimetric Assay for Histidine Quantification in Human Urine Using 96-Well Plates

A high-throughput fluorimetric assay for histidine was developed, using a 96-well plates platform. The analyte reacts selectively with o-phthalaldehyde under mild alkaline conditions to form a stable derivative. Instrumental-free detection was carried out using a smartphone after illumination under UV light (365 nm). The method was proved to be linear up to 100 μM histidine, with an LLOQ (lower limit of quantification) of 10 μM. The assay was only prone to interference from glutathione and histamine that exist in the urine samples at levels that are orders of magnitude lower compared to histidine. Human urine samples were analyzed following minimum treatment and were found to contain histidine in the range of 280 to 1540 μM. The results were in good agreement with an HPLC corroborative method.

Perspective: Developing a Nutrient-Based Framework for Protein Quality

The future of precision nutrition requires treating amino acids as essential nutrients. Currently, recognition of essential amino acid requirements is embedded within a generalized measure of protein quality known as the PDCAAS (Protein Digestibility-Corrected Amino Acid Score). Calculating the PDCAAS includes the FAO/WHO/UNU amino acid score, which is based on the limiting amino acid in a food, that is, the single amino acid with the lowest concentration compared to the reference standard. That "limiting" amino acid score is then multiplied by a bioavailability factor to obtain the PDCAAS, which ranks proteins from 0.0 (poor quality) to 1.0 (high quality). However, the PDCAAS has multiple limitations: it only allows for direct protein quality comparison between 2 proteins, and it is not scalable, transparent, or additive. We therefore propose that shifting the protein quality evaluation paradigm from the current generalized perspective to a precision nutrition focus treating amino acids as unique, metabolically active nutrients will be valuable for multiple areas of science and public health. We report the development and validation of the Essential Amino Acid 9 (EAA-9) score, an innovative, nutrient-based protein quality scoring framework. EAA-9 scores can be used to ensure that dietary recommendations for each essential amino acid are met. The EAA-9 scoring framework also offers the advantages of being additive and, perhaps most importantly, allows for personalization of essential amino acid needs based on age or metabolic conditions. Comparisons of the EAA-9 score with PDCAAS demonstrated the validity of the EAA-9 framework, and practical applications demonstrated that the EAA-9 framework is a powerful tool for precision nutrition applications.

Proteomic analysis of fatty liver induced by starvation of medaka fish larvae

When medaka fish (Oryzias latipes) larvae are grown in the absence of exogenous nutrition, the liver becomes dark and positive to Oil Red O staining from 7 days post-hatch (dph). We determined the mechanism of this starvation-induced development of fatty liver by proteomic analysis using livers obtained from larvae grown in the presence or absence of 2% glucose at 5 dph. Results showed that changes in the expression levels of enzymes involved in glycolysis or the tricarboxylic acid cycle were modest, whereas the expression levels of enzymes involved in amino acid catabolism or β-oxidation of fatty acids were significantly elevated, suggesting that they become major energy sources under starvation conditions. Expression levels of enzymes for the uptake and β-oxidation of fatty acids as well as synthesis of triacylglycerol were elevated, whereas those for the synthesis of cholesterol as well as export of cholesterol and triacylglycerol were decreased under starvation conditions, which explains the accumulation of triacylglycerol in the liver. Our results provide the basis for future research to understand how gene malfunction(s) affects the development of fatty liver, which can lead to nonalcoholic steatohepatitis and then to liver cirrhosis.Key words: amino acid catabolism, β-oxidation, triacylglycerol, cholesterol, export.

Tolerable Upper Intake Level for Individual Amino Acids in Humans: A Narrative Review of Recent Clinical Studies

Individual amino acids are widely popular as supplements because of various perceived and real health benefits. However, currently, there are no recommendations set by national health agencies for tolerable upper intake levels (UL) for amino acids because of a lack of well-conducted human dose-response trials. In the past decade, under the initiative of the International Council on Amino Acid Science, a nonprofit organization, a series of UL human clinical studies were conducted. The goal of this narrative review is to summarize the studies on 6 essential amino acids (leucine, tryptophan, methionine, lysine, histidine, and phenylalanine), 2 nonessential amino acids (arginine and serine), and 2 nonproteinogenic amino acids (ornithine and citrulline) and provide the first set of ULs. A brief background of the concept of the DRI framework of UL, the concept of UL for amino acids, and a perspective of the results are also provided. The data suggest that in relatively healthy adult individuals, the tested amino acids are well tolerated, and ULs, or the no-observed-adverse-effect-level (NOAEL), lowest-observed-adverse-effect-level (LOAEL), can be determined. The ULs were for leucine-young (35 g/d), tryptophan (4.5 g/d), and leucine-elderly (30 g/d); NOAEL and LOAEL for methionine at 3.2 and 6.4 g/d, respectively; NOAEL for arginine (30 g/d); NOAEL and LOAEL for lysine at 6 and 7.5 g/d, respectively; NOAEL and LOAEL for histidine at 8 and 12 g/d, respectively; and NOAEL for phenylalanine (12 g/d), serine (12 g/d), ornithine (12 g/d) and citrulline (24 g/d). This first set of human UL data are hoped to help national and international agencies set safety standards for supplemental amino acids.

Dietary Manipulation of Amino Acids for Cancer Therapy

Cancer cells cannot proliferate and survive unless they obtain sufficient levels of the 20 proteinogenic amino acids (AAs). Unlike normal cells, cancer cells have genetic and metabolic alterations that may limit their capacity to obtain adequate levels of the 20 AAs in challenging metabolic environments. However, since normal diets provide all AAs at relatively constant levels and ratios, these potentially lethal genetic and metabolic defects are eventually harmless to cancer cells. If we temporarily replace the normal diet of cancer patients with artificial diets in which the levels of specific AAs are manipulated, cancer cells may be unable to proliferate and survive. This article reviews in vivo studies that have evaluated the antitumor activity of diets restricted in or supplemented with the 20 proteinogenic AAs, individually and in combination. It also reviews our recent studies that show that manipulating the levels of several AAs simultaneously can lead to marked survival improvements in mice with metastatic cancers.

Uncovering the Nutritive Profiles of Adult Male Chinese Mitten Crab (E. sinensis) Harvested from the Pond and Natural Water Area of Qin Lake Based on Metabolomics

E. sinensis, normally harvested in October and November, is an economic aquatic product in China. Pond culture has been widely applied for the production of E. sinensis, wherein a stable food supply for crabs is provided. In order to improve the nutritional quality of E. sinensis products, this study evaluated the effect of the local pond culture on the nutritive profiles of E. sinensis and screened out the best harvest time for the nutrient-rich crabs, thereby guiding the local crab industry to improve its aquaculture mode and harvest strategy. The results indicated that pond culture enhanced the levels of protein, amino acids, and specific organic acid derivatives, and reduced the levels of peptides and polyunsaturated fatty acids (PUFAs). Compared with E. sinensis harvested in October, peptide levels were significantly increased, whereas sugar, phenolic acid, and nucleotide levels were decreased in those harvested in November. Overall, the study revealed that the nutritive profile of the pond-reared E. sinensis was significantly modulated by a high-protein diet, thus lacking the diversity of metabolites. Additionally, October could be more appropriate for harvesting E. sinensis than November.

Combined Transcriptome and Metabolome Analysis of Smooth Muscle of Myostatin Knockout Cattle

Myostatin (MSTN), a growth and differentiation factor, plays an important role in regulating skeletal muscle growth and development. MSTN knockout (MSTN-KO) leads to skeletal muscle hypertrophy and regulates metabolic homeostasis. Moreover, MSTN is also detected in smooth muscle. However, the effect of MSTN-KO on smooth muscle has not yet been reported. In this study, combined metabolome and transcriptome analyses were performed to investigate the metabolic and transcriptional profiling in esophageal smooth muscles of MSTN-KO Chinese Luxi Yellow cattle (n = 5, 24 months, average body weight 608.5 ± 17.62 kg) and wild-type (WT) Chinese Luxi Yellow cattle (n = 5, 24 months, average body weight 528.25 ± 11.03 kg). The transcriptome was sequenced using the Illumina Novaseq™ 6000 sequence platform. In total, 337 significantly up- and 129 significantly down-regulated genes were detected in the MSTN-KO cattle compared with the WT Chinese Luxi Yellow cattle. Functional enrichment analysis indicated that the DEGs were mainly enriched in 67 signaling pathways, including cell adhesion molecules, tight junction, and the cGMP-PKG signaling pathway. Metabolomics analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS) identified 130 differential metabolites between the groups, with 56 up-regulated and 74 down-regulated in MSTN knockout cattle compared with WT cattle. Differential metabolites were significantly enriched in 31 pathways, including glycerophospholipid metabolism, histidine metabolism, glutathione metabolism, and purine metabolism. Transcriptome and metabolome were combined to analyze the significant enrichment pathways, and there were three metabolically related pathways, including histidine metabolism, purine metabolism, and arginine and proline metabolism. These results provide important references for in-depth research on the effect of MSTN knockout on smooth muscle.

An Exploratory Study of the Metabolite Profiling from Pesticides Exposed Workers

Pesticides constitute a category of chemical products intended specifically for the control and mitigation of pests. With their constant increase in use, the risk to human health and the environment has increased proportionally due to occupational and environmental exposure to these compounds. The use of these chemicals is associated with several toxic effects related to acute and chronic toxicity, such as infertility, hormonal disorders and cancer. The present work aimed to study the metabolic profile of individuals occupationally exposed to pesticides, using a metabolomics tool to identify potential new biomarkers. Metabolomics analysis was carried out on plasma and urine samples from individuals exposed and non-exposed occupationally, using liquid chromatography coupled with mass spectrometry (UPLC-MS). Non-targeted metabolomics analysis, using principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) or partial least squares discriminant orthogonal analysis (OPLS-DA), demonstrated good separation of the samples and identified 21 discriminating metabolites in plasma and 17 in urine. The analysis of the ROC curve indicated the compounds with the greatest potential for biomarkers. Comprehensive analysis of the metabolic pathways influenced by exposure to pesticides revealed alterations, mainly in lipid and amino acid metabolism. This study indicates that the use of metabolomics provides important information about complex biological responses.

Development of a fast and robust liquid chromatography-mass spectrometry-based metabolomics analysis method for neonatal dried blood spots

Dried blood spot (DBS) samples have been widely used in many fields including newborn screening, with the advantages in transportation, storage and non-invasiveness. The DBS metabolomics research of neonatal congenital diseases will greatly expand the understanding of the disease. In this study, we developed a liquid chromatography-mass spectrometry-based method for neonatal metabolomics analysis of DBS. The influences of blood volume and chromatographic effects on the filter paper on metabolite levels were studied. The levels of 11.11 % metabolites were different between 75 μL and 35 μL of blood volumes used for DBS preparation. Chromatographic effects on the filter paper occurred in DBS prepared with 75 μL whole blood and 6.67 % metabolites had different MS responses when central disks were compared with outer disks. The DBS storage stability study showed that compared with - 80 °C storage, storing at 4 °C for 1 year had obvious influences on more than half metabolites. Storing at 4 °C and - 20 °C for short term (< 14 days) and - 20 °C for longer term (1 year) had less influences on amino acids, acyl-carnitines and sphingomyelins, but greater influences on partial phospholipids. Method validation showed that this method has a good repeatability, intra-day and inter-day precision and linearity. Finally, this method was applied to investigate metabolic disruptions of congenital hypothyroidism (CH), metabolic changes of CH newborns were mainly involved in amino acid metabolism and lipid metabolism.

Altered DNA methylation and gene expression predict disease severity in patients with Aicardi-Goutières syndrome

Aicardi-Goutières Syndrome (AGS) is a rare neuro-inflammatory disease characterized by increased expression of interferon-stimulated genes (ISGs). Disease-causing mutations are present in genes associated with innate antiviral responses. Disease presentation and severity vary, even between patients with identical mutations from the same family. This study investigated DNA methylation signatures in PBMCs to understand phenotypic heterogeneity in AGS patients with mutations in RNASEH2B. AGS patients presented hypomethylation of ISGs and differential methylation patterns (DMPs) in genes involved in "neutrophil and platelet activation". Patients with "mild" phenotypes exhibited DMPs in genes involved in "DNA damage and repair", whereas patients with "severe" phenotypes had DMPs in "cell fate commitment" and "organ development" associated genes. DMPs in two ISGs (IFI44L, RSAD2) associated with increased gene expression in patients with "severe" when compared to "mild" phenotypes. In conclusion, altered DNA methylation and ISG expression as biomarkers and potential future treatment targets in AGS.

Systems-level transcriptional regulation of Caenorhabditis elegans metabolism

Metabolism is controlled to ensure organismal development and homeostasis. Several mechanisms regulate metabolism, including allosteric control and transcriptional regulation of metabolic enzymes and transporters. So far, metabolism regulation has mostly been described for individual genes and pathways, and the extent of transcriptional regulation of the entire metabolic network remains largely unknown. Here, we find that three-quarters of all metabolic genes are transcriptionally regulated in the nematode Caenorhabditis elegans. We find that many annotated metabolic pathways are coexpressed, and we use gene expression data and the iCEL1314 metabolic network model to define coregulated subpathways in an unbiased manner. Using a large gene expression compendium, we determine the conditions where subpathways exhibit strong coexpression. Finally, we develop "WormClust," a web application that enables a gene-by-gene query of genes to view their association with metabolic (sub)-pathways. Overall, this study sheds light on the ubiquity of transcriptional regulation of metabolism and provides a blueprint for similar studies in other organisms, including humans.

One Molecular Probe with Opposite Enantioselective Fluorescence Enhancement at Two Distinct Emissions

It is discovered that one enantiomer of a chiral substrate can greatly enhance the fluorescence of one molecular probe at one emitting signal (λ₁ = 517 nm), while the opposite enantiomer of the substrate greatly enhances the fluorescence of the same probe at a distinctively different emission (λ₂ = 575 nm). This probe is made of a 1,1'-binaphthyl-based chiral dialdehyde that in combination with Zn²⁺ under slightly acidic conditions shows a chemoselective and enantioselective fluorescent response to histidine. The opposite enantioselective fluorescent responses of the probe at two emissions allow it to be used to determine both the concentration and the enantiomeric composition of the substrate using a single probe. The mechanistic study has revealed two very different reaction pathways when the two enantiomers of the substrate are treated with the probe. These reaction pathways generate two different products, one dimeric and another polymeric, with very different emissions.