Metabolite Signals Research Articles

Branched-chain α-ketoacids aerobically activate HIF1α signalling in vascular cells.

Hypoxia-inducible factor 1α (HIF1α) is a master regulator of biological processes in hypoxia. Yet, the mechanisms and biological consequences of aerobic HIF1α activation by intrinsic factors, particularly in normal (primary) cells, remain elusive. Here we show that HIF1α signalling is activated in several human primary vascular cells in normoxia and in vascular smooth muscle cells of normal human lungs. Mechanistically, aerobic HIF1α activation is mediated by paracrine secretion of three branched-chain α-ketoacids (BCKAs), which suppress PHD2 activity via direct inhibition and via LDHA-mediated generation of L-2-hydroxyglutarate. BCKA-mediated HIF1α signalling activation stimulated glycolytic activity and governed a phenotypic switch of pulmonary artery smooth muscle cells, which correlated with BCKA metabolic dysregulation and pathophenotypic changes in pulmonary arterial hypertension patients and male rat models. We thus identify BCKAs as previously unrecognized signalling metabolites that aerobically activate HIF1α and that the BCKA-HIF1α pathway modulates vascular smooth muscle cell function, an effect that may be relevant to pulmonary vascular pathobiology.

Ginsenoside Rg1 enriches gut microbial indole-3-acetic acid to alleviate depression-like behavior in mice via oxytocin signaling

Background and purposeAlthough a large collection of data has shown that ginsenosides, the major active ingredients from Ginseng, have neuroprotective and anti-depressant effect, the mechanism of action is incompletely understood. This study aims to elucidate the antidepressant mechanism of ginsenoside Rg1 (Rg1), a poorly absorbed ginsenoside, from the perspective of gut microbe to brain signaling. MethodsA mouse model of depression was induced by unpredictable mild stress (UMS). Behavioral and neurochemical tests were conducted to evaluate the effect and mechanism of Rg1 on depressive behavior. Non-target and target metabolomics were performed to identify the signaling metabolites underlying the antidepressant efficacy of Rg1. Gut microbial structure was analyzed by 16S rRNA sequencing and the potential functional strains associated with Rg1 action were investigated by in vitro bacterial culture. Chemical intervention was used to explore the mechanism of Rg1 and signaling metabolite. ResultsRg1 improved UMS-induced despair, anxiety-like and social avoidance behaviors in mice, which were accompanied by increased hypothalamic oxytocin secretion and restored neural proliferation in the hippocampus. Metabolomic analysis of the gut-brain axis revealed that Rg1 increased the concentration of serum and brain indole-3-acetic acid (IAA), a bacterial metabolite that was partially attributed to the enrichment of Lactobacillus murinus in the gut microbiome. Oral supplementation of IAA mimicked the anti-depressant action of Rg1, while oxytocin receptor antagonist abrogated the anti-depressant effects of both Rg1 and IAA. ConclusionOur work provides a new gut-to-brain signaling mechanism for the antidepressant effects of Rg1. In particular, Rg1 enriches the abundance of Lactobacillus murinus, which in turn increases the level of brain IAA and potentiates hypothalamic oxytocin signal. These findings suggest a promising pathway for producing antidepressant effects through gut-brain crosstalk.

Multiple Omics Analyses Reveal Activation of Nitrogen Metabolism and Flavonoid Glycosylation in Toxicodendron vernicifluum Under High Temperature

Lacquer trees (Toxicodendron vernicifluum), economically vital, face high-temperature stress in summer. Transcriptomic, proteomic, and metabolomic analyses were employed to investigate the mechanisms by which lacquer trees respond to high temperatures. High-temperature treatment led to notable metabolite changes with 224 upregulated and 69 downregulated. Indole-3-acetic acid remained stable while abscisic acid decreased, with increases in jasmonic acid and jasmonoyl-L-isoleucine indicating complex hormonal responses. JAR1 and ABA 8′-hydroxylase encoding genes were upregulated. The rise in JAs boosted the alkaloid content and activated nitrogen transport. High temperatures also increased specific amino acids and upregulated aminotransferase and protease-encoding genes. Metabolomic analysis showed elevated flavonoid glycosides and the upregulation of glycosyltransferase genes. WPCNA found 35 protein modules involved in secondary metabolite biosynthesis, protein phosphorylation, and signal transduction. Protein–protein interaction analysis revealed MYC6’s link with flavonoid biosynthesis, indicating its role in promoting flavonoids.

Effect of SiHuangQingXinWan on Klebsiella pneumoniae-induced pneumonia: mechanistic insights.

Due to the high mortality rate and increasing severity of antibiotic resistance, there is a growing interest in new treatments for Klebsiella pneumoniae (KP)-induced pneumonia. Research has shown that the single herbs of SiHuangQingXinWan (SHQXW) are effective in treating pneumonia caused by KP. The PI3K/AKT signaling pathway has garnered attention for its potential role in the management of bacterial infections. This study aimed to evaluate the anti-pneumonia effect of SHQXW and to investigate its mechanism of action. The potential plant metabolites and molecular targets of SHQXW in the context of pneumonia were determined through ultra-high performance liquid chromatography-tandem mass-spectrometry (UHPLC-MS/MS) and bioinformatics analysis. The therapeutic effect of SHQXW was evaluated in a KP-induced pneumonia murine model with imipenem/cilastatin as a positive control. Transcriptomics and non-targeted metabolomics were carried out to unveil potential mechanisms and targets for anti-pneumonia effects. Additionally, an in-depth exploration on the PI3K/AKT signaling pathway was conducted in this study. A total of 24 potential plant metabolites and 285 SHQXW-pneumonia-related targets selected by Homo sapiens were identified in this study. The tested doses of SHQXW significantly reduced mortality, improved body weight, decreased the lung index, reduced the bacterial load, and alleviated lung pathological damage in the KP-induced pneumonia murine model (p < 0.05). Notably, 1.3g/kg/day of SHQXW provided the most effective protective outcome. Furthermore, SHQXW demonstrated the ability to suppress the production of inflammatory factors such as IL-1α, IL-1β, IL-3, IL-6, IL-12p70, G-CSF, GM-CSF, MCP-1, KC, and TNF-α. Analysis of transcriptomic and metabolomic data revealed that SHQXW could modulate inflammation-related signaling pathways (TNF, HIF-1, NF-κB, and PI3K/AKT) and metabolites to regulate pulmonary inflammation. Additional experiments using RT-qPCR and western blotting indicated that SHQXW may exert anti-inflammatory effects by activating the PI3K/AKT pathway. The findings indicate that SHQXW effectively reduces inflammation in mice with KP-induced pneumonia by modulating inflammatory signaling pathways and metabolites, rather than by directly inhibiting the growth of KP. This study introduces a novel treatment approach for KP-induced pneumonia and presents a new outlook on drug development.

7948 Integration Of Epigenomics And Metabolomics Reveals New Signaling In Aggressive Thyroid Cancer

Abstract Disclosure: A. Sanghi: None. S. Wu: None. T. Chou: None. L.A. Orloff: None. M. Kasowski: None. M. Snyder: None. Although genetic mutations are causal in human cancers, the contribution of chromatin changes to cancer onset and progression remains less well understood. Multi-omics profiling of human tumors can provide insight into how alterations in chromatin structure are propagated through the pathway of gene expression to result in cancer signaling. We applied multi-omics profiling of 36 human thyroid cancer primary tumors, metastases, and patient-matched normal tissue. Over 80% of the tumors harbored BRAFV600E mutations, and the remaining tumors mostly had activating mutations in the MAPK pathway. Through quantification of chromatin accessibility associated with active transcription units and global protein expression, we identify local enhancers that are highly correlated with coordinated RNA and protein expression. The enhancers are predicted to be actively bound by MAPK transcription factor, indicating they are under MAPK control. These cancer-specific enhancers associated with upregulation of lysosomal peptidase expression and dipeptide abundance in tumors. We show that upregulated dipeptides stimulate MAPK activity, and BRAF inhibition results in loss of lysosomal function in mutants. Perturbation of lysosomal peptidases and dipeptide abundance decreases MAPK activity only in mutant cells compared to wildtype. These analyses suggest that BRAF thyroid tumors integrate MAPK-driven epigenetic regulation with lysosomal metabolite signaling in a positive feedback circuit. Using local cancer-specific epigenetic features, we isolated key cancer signaling, making way for potential targets for cancer therapeutics. Presentation: 6/3/2024

Extracting Knowledge from MS Clinical Metabolomic Data: Processing and Analysis Strategies.

Assessing potential alterations of metabolic pathways using large-scale approaches plays today a central role in clinical research. Because several thousands of mass features can be measured for each sample with separation techniques hyphenated to mass spectrometry (MS) detection, adapted strategies have to be implemented to detect altered pathways and help to elucidate the mechanisms of pathologies. These procedures include peak detection, sample alignment, normalization, statistical analysis, and metabolite annotation. Interestingly, considerable advances have been made over the last years in terms of analytics, bioinformatics, and chemometrics to help massive and complex metabolomic data to be more adequately handled with automated processing and data analysis workflows. Recent developments and remaining challenges related to MS signal processing, metabolite annotation, and biomarker discovery based on statistical models are illustrated in this chapter in light of their application to clinical research.

Neuropilin-2-expressing breast cancer cells mitigate radiation-induced oxidative stress through nitric oxide signaling.

The high rate of recurrence after radiation therapy in triple-negative breast cancer (TNBC) indicates that novel approaches and targets are needed to enhance radiosensitivity. Here, we report that neuropilin-2 (NRP2), a receptor for vascular endothelial growth factor (VEGF) that is enriched on subpopulations of TNBC cells with stem cell properties, is an effective therapeutic target for sensitizing TNBC to radiotherapy. Specifically, VEGF/NRP2 signaling induces nitric oxide synthase 2 (NOS2) transcription by a mechanism dependent on Gli1. NRP2-expressing tumor cells serve as a hub to produce nitric oxide (NO), an autocrine and paracrine signaling metabolite, which promotes cysteine-nitrosylation of Kelch-like ECH-associated protein 1 (KEAP1) and, consequently, nuclear factor erythroid 2-related factor 2-mediated (NFE2L2-mediated) transcription of antioxidant response genes. Inhibiting VEGF binding to NRP2, using a humanized mAb, results in NFE2L2 degradation via KEAP1, rendering cell lines and organoids vulnerable to irradiation. Importantly, treatment of patient-derived xenografts with the NRP2 mAb and radiation resulted in significant tumor necrosis and regression compared with radiation alone. Together, these findings reveal a targetable mechanism of radioresistance, and they support the use of NRP2 mAb as an effective radiosensitizer in TNBC.

Examination of methods to separate overlapping metabolites at 7T.

Neurochemicals of interest quantified by MRS are often composites of overlapping signals. At higher field strengths (i.e., 7T), there is better separation of these signals. As the availability of higher field strengths is increasing, it is important to re-evaluate the separability of overlapping metabolite signals. This study compares the ability of stimulated echo acquisition mode (STEAM-8; TE = 8 ms), short-TE semi-LASER (sLASER-34; TE = 34 ms), and long-TE semi-LASER (sLASER-105; TE = 105 ms) acquisitions to separate the commonly acquired neurochemicals at 7T (Glx, consisting of glutamate and glutamine; total N-acetyl aspartate, consisting of N-acetyl aspartate and N-acetylaspartylglutamate; total creatine, consisting of creatine and phosphocreatine; and total choline, consisting of choline, phosphocholine, and glycerophosphocholine). sLASER-34 produced the lowest fit errors for most neurochemicals; however, STEAM-8 had better within-subject reproducibility and required fewer subjects to detect a change between groups. However, this is dependent on the neurochemical of interest. We recommend short-TE STEAM for separation of most standard neurochemicals at 7T over short-TE or long-TE sLASER.

Itaconate induces tolerance of Staphylococcus aureus to aminoglycoside antibiotics.

Staphylococcus aureus is one of the chief pathogens that cause chronic and recurrent infections. Failure of the antibiotics to curb the infections contributes to relapse and is an important reason for the high mortality rate. Treatment failure may also be due to antibiotic tolerance. Accumulating evidence suggests that t the host immune environment plays an important role in inducing antibiotic tolerance of S. aureus, but research in this area has been limited. In this study,the minimum inhibitory concentration (MIC) of the antibiotics against S. aureus was determined using the standard broth microdilution method.The study evaluated whether itaconate induces antibiotic tolerance in S. aureus through an antibiotic bactericidal activity assay.The effect of itaconate on the growth of S. aureus was evaluated by monitoring the growth of S. aureus in medium supplemented with itaconate. Additionally, RNA sequencing and metabolomics analyses were used to determine transcriptional and metabolic changes in S. aureus when exposed to itaconate. According to the study,we found that the immune metabolite itaconate can induce tolerance in both methicillin-resistant and -susceptible S. aureus to aminoglycosides. When S. aureus was exposed to itaconate, its growth slowed down and transcriptomic and metabolomic alterations associated with decreased energy metabolism, including the tricarboxylate cycle, glycolysis, pyruvate metabolism, and arginine biosynthesis, were observed. These changes are associated with aminoglycoside tolerance. This study highlights the role of immune signaling metabolites in bacterial antibiotic tolerance and suggests new strategies to improve antibiotic treatment by modulating the host immune response and stimulating the metabolism of bacteria.

Metabolism at the crossroads of inflammation and fibrosis in chronic kidney disease.

Chronic kidney disease (CKD), defined as persistent (>3 months) kidney functional loss, has a growing prevalence (>10% worldwide population) and limited treatment options. Fibrosis driven by the aberrant accumulation of extracellular matrix is the final common pathway of nearly all types of chronic repetitive injury in the kidney and is considered a hallmark of CKD. Myofibroblasts are key extracellular matrix-producing cells that are activated by crosstalk between damaged tubules and immune cells. Emerging evidence indicates that metabolic alterations are crucial contributors to the pathogenesis of kidney fibrosis by affecting cellular bioenergetics and metabolite signalling. Immune cell functions are intricately connected to their metabolic characteristics, and kidney cells seem to undergo cell-type-specific metabolic shifts in response to damage, all of which can determine injury and repair responses in CKD. A detailed understanding of the heterogeneity in metabolic reprogramming of different kidney cellular subsets is essential to elucidating communication processes between cell types and to enabling the development of metabolism-based innovative therapeutic strategies against CKD.

Sarcosine, Trigonelline and Phenylalanine as Urinary Metabolites Related to Visceral Fat in Overweight and Obesity.

The objective of the present study is to analyze the urinary metabolome profile of patients with obesity and overweight and relate it to different obesity profiles. This is a prospective, cross-sectional study in which patients with a body mass index (BMI) ≥25 kg/m were selected. Anthropometric data were assessed by physical examination and body composition was obtained by bioimpedance (basal metabolic rate, body fat percentile, skeletal muscle mass, gross fat mass and visceral fat). Urine was collected for metabolomic analysis. Patients were classified according to abdominal circumference measurements between 81 and 93, 94 and 104, and >104 cm; visceral fat up to 16 kilos and less than; and fat percentiles of <36%, 36-46% and >46%. Spectral alignment of urinary metabolite signals and bioinformatic analysis were carried out to select the metabolites that stood out. NMR spectrometry was used to detect and quantify the main urinary metabolites and to compare the groups. Seventy-five patients were included, with a mean age of 38.3 years, and 72% females. The urinary metabolomic profile showed no differences in BMI, abdominal circumference and percentage of body fat. Higher concentrations of trigonelline (p = 0.0488), sarcosine (p = 0.0350) and phenylalanine (p = 0.0488) were associated with patients with visceral fat over 16 kg. The cutoff points obtained by the ROC curves were able to accurately differentiate between patients according to the amount of visceral fat: sarcosine 0.043 mg/mL; trigonelline 0.068 mg/mL and phenylalanine 0.204 mg/mL. In conclusion, higher visceral fat was associated with urinary levels of metabolites such as sarcosine, related to insulin resistance; trigonelline, related to muscle mass and strength; and phenylalanine, related to glucose metabolism and abdominal fat. Trigonelline, sarcosine and phenylalanine play significant roles in regulating energy balance and metabolic pathways essential for controlling obesity. Our findings could represent an interesting option for the non-invasive estimation of visceral fat through biomarkers related to alterations in metabolic pathways involved in the pathophysiology of obesity.

Hyperpolarized [1-13C]pyruvate Magnetic Resonance Imaging Identifies Metabolic Phenotypes in Patients with Heart Failure

BackgroundHyperpolarized [1-13C]pyruvate magnetic resonance imaging (HP MRI) visualizes key steps in myocardial metabolism. The present study aimed to examine patients with heart (HF) using HP MRI. MethodsA cross-sectional study of patients with HF and healthy controls using HP MRI. Metabolic imaging was obtained using a cardiac-gated spectral-spatial excitation with spiral read-out acquisition. The metabolite signal was analyzed for lactate, bicarbonate, and the alanine signal. Metabolite signal was normalized to the total carbon signal (TC). At the one-year follow-up, echocardiography was performed in all patients and HP MRI in two patients. ResultsWe included six patients with ischemic heart disease (IHD), six with dilated cardiomyopathy and six healthy controls. In patients, left ventricular ejection fraction (LVEF) correlated with lactate/bicarbonate (r = -0.6, p = 0.03) and lactate/TC (r = -0.7, p = 0.01). In patients with LVEF < 30%, lactate/TC was increased (p = 0.01) and bicarbonate/TC reduced (p = 0.03). Circumferential strain correlated with metabolite ratios: lactate/bicarbonate, r = 0.87 (p = 0.0002); lactate/TC, r = 0.85 (p = 0.0005); bicarbonate/TC, r = -0.82 (p = 0.001). In patients with IHD, a strong correlation was found between baseline metabolite ratios and the change in LVEF at follow-up: lactate/bicarbonate (p = 0.001); lactate/TC (p = 0.011); and bicarbonate/TC (p = 0.012). ConclusionsThis study highlighted the ability of HP MRI to detect changes in metabolism in HF. HP MRI has potential for metabolic phenotyping of patients with HF and for predicting treatment response. Trial registrationEUDRACT, 2018-003533-15. Registered 4 December 2018, https://www.clinicaltrialsregister.eu/ctr-search/search?query=2018-003533-15.

Integrated Dual-Channel Retrograde Signaling Directs Stress Responses by Degrading the HAT1/TPL/IMPα-9 Suppressor Complex and Activating CAMTA3.

This study uncovers how the stress-induced signaling metabolite MEcPP disrupts the HAT1/TPL/IMPα-9 suppressor complex, liberating the activator CAMTA3 and enabling Ca 2+ influx essential for CAMTA3 activation, thus orchestrating stress responses via repressor degradation and activator induction.

Studying temperature’s impact on Brassica napus resistance to identify key regulatory mechanisms using comparative metabolomics

To investigate the effects of temperature on Brassica napus (canola) resistance to Leptosphaeria maculans (LM), the causal agent of blackleg disease, metabolic profiles of LM infected resistant (R) and susceptible (S) canola cultivars at 21 °C and 28 °C were analyzed. Metabolites were detected in cotyledons of R and S plants at 48- and 120-h post-inoculation with LM using UPLC-QTOF/MS. The mock-inoculated plants were used as controls. Some of the resistance-related specific pathways, including lipid metabolism, amino acid metabolism, carbohydrate metabolism, and aminoacyl-tRNA biosynthesis, were down-regulated in S plants but up-regulated in R plants at 21 °C. However, some of these pathways were down-regulated in R plants at 28 °C. Amino acid metabolism, lipid metabolism, alkaloid biosynthesis, phenylpropanoid biosynthesis, and flavonoid biosynthesis were the pathways linked to combined heat and pathogen stresses. By using network analysis and enrichment analysis, these pathways were identified as important. The pathways of carotenoid biosynthesis, pyrimidine metabolism, and lysine biosynthesis were identified as unique mechanisms related to heat stress and may be associated with the breakdown of resistance against the pathogen. The increased susceptibility of R plants at 28 °C resulted in the down-regulation of signal transduction pathway components and compromised signaling, particularly during the later stages of infection. Deactivating LM-specific signaling networks in R plants under heat stress may result in compatible responses and deduction in signaling metabolites, highlighting global warming challenges in crop disease control.

Unraveling phytoremediation mechanisms of the common reed (Phragmites australis) suspension cells towards ciprofloxacin: Xenobiotic transformation and metabolic reprogramming

Phytoremediation is an effective solution to treat pollution with antibiotic compounds in aquatic environments; however, the underlying mechanisms for plants to cope with antibiotic pollutants are obscure. Here we used cell suspension culture to investigate the distribution and transformation of ciprofloxacin (CIP) in common reed (Phragmites australis) plants, as well as the accompanying phenotypic and metabolic responses of plants. By means of radioactive isotope labelling, we found that in total 68 % of CIP was transformed via intracellular Phase I transformation (reduction and methylation), Phase Ⅱ conjugation (glycosylation), and Phase Ⅲ compartmentalization (cell-bound residue formation mainly in cell walls, 23 %). The reduction and glycosylation products were secreted by the cells. To mitigate stress induced by CIP and its transformation products, the cells activated the defense system by up-regulating both intra- and extra-cellular antioxidant metabolites (e.g., catechin, l-cystine, and dehydroascorbic acid), anti-C/N metabolism disorder metabolites (e.g., succinic acid), secreting signaling (e.g., nicotinic acid), and anti-stress (e.g., allantoin) metabolites. Notably, the metabolic reprogramming could be involved in the CIP transformation process (e.g., glycosylation). Our findings reveal the strategy of wetland plants to cope with the stress from CIP by transforming the xenobiotic compound and reprogramming metabolism, and provide novel insights into the fate of antibiotics and plant defense mechanisms during phytoremediation.

Strigolactone signalling inhibits trehalose 6-phosphate signalling independently of BRC1 to suppress shoot branching.

The phytohormone strigolactone (SL) inhibits shoot branching, whereas the signalling metabolite trehalose 6-phosphate (Tre6P) promotes branching. How Tre6P and SL signalling may interact and which molecular mechanisms might be involved remains largely unknown. Transcript profiling of Arabidopsis SL mutants revealed a cluster of differentially expressed genes highly enriched in the Tre6P pathway compared with wild-type (WT) plants or brc1 mutants. Tre6P-related genes were also differentially expressed in axillary buds of garden pea (Pisum sativum) SL mutants. Tre6P levels were elevated in the SL signalling mutant more axillary (max) growth 2 compared with other SL mutants or WT plants indicating a role of MAX2-dependent SL signalling in regulating Tre6P levels. A transgenic approach to increase Tre6P levels demonstrated that all SL mutant lines and brc1 flowered earlier, showing all of these mutants were responsive to Tre6P. Elevated Tre6P led to increased branching in WT plants but not in max2 and max4 mutants, indicating some dependency between the SL pathway and Tre6P regulation of shoot branching. By contrast, elevated Tre6P led to an enhanced branching phenotype in brc1 mutants indicating independence between BRC1 and Tre6P. A model is proposed whereby SL signalling represses branching via Tre6P and independently of the BRC1 pathway.

Renal L-2-hydroxyglutarate dehydrogenase activity promotes hypoxia tolerance and mitochondrial metabolism in Drosophila melanogaster

ObjectivesThe mitochondrial enzyme L-2-hydroxyglutarate dehydrogenase (L2HGDH) regulates the abundance of L-2-hydroxyglutarate (L-2HG), a potent signaling metabolite capable of influencing chromatin architecture, mitochondrial metabolism, and cell fate decisions. Loss of L2hgdh activity in humans induces ectopic L-2HG accumulation, resulting in neurodevelopmental defects, altered immune cell function, and enhanced growth of clear cell renal cell carcinomas. To better understand the molecular mechanisms that underlie these disease pathologies, we used the fruit fly Drosophila melanogaster to investigate the endogenous functions of L2hgdh. MethodsL2hgdh mutant adult male flies were analyzed under normoxic and hypoxic conditions using a combination of semi-targeted metabolomics and RNA-seq. These multi-omic analyses were complemented by tissue-specific genetic studies that examined the effects of L2hgdh mutations on the Drosophila renal system (Malpighian tubules; MTs). ResultsOur studies revealed that while L2hgdh is not essential for growth or viability under standard culture conditions, L2hgdh mutants are hypersensitive to hypoxia and expire during the reoxygenation phase with severe disruptions of mitochondrial metabolism. Moreover, we find that the fly renal system is a key site of L2hgdh activity, as L2hgdh mutants that express a rescuing transgene within the MTs survive hypoxia treatment and exhibit normal levels of mitochondrial metabolites. We also demonstrate that even under normoxic conditions, L2hgdh mutant MTs experience significant metabolic stress and are sensitized to aberrant growth upon Egfr activation. ConclusionsThese findings present a model in which renal L2hgdh activity limits systemic L-2HG accumulation, thus indirectly regulating the balance between glycolytic and mitochondrial metabolism, enabling successful recovery from hypoxia exposure, and ensuring renal tissue integrity.

A Narrative Review: Immunometabolic Interactions of Host-Gut Microbiota and Botanical Active Ingredients in Gastrointestinal Cancers.

The gastrointestinal tract is where the majority of gut microbiota settles; therefore, the composition of the gut microbiota and the changes in metabolites, as well as their modulatory effects on the immune system, have a very important impact on the development of gastrointestinal diseases. The purpose of this article was to review the role of the gut microbiota in the host environment and immunometabolic system and to summarize the beneficial effects of botanical active ingredients on gastrointestinal cancer, so as to provide prospective insights for the prevention and treatment of gastrointestinal diseases. A literature search was performed on the PubMed database with the keywords "gastrointestinal cancer", "gut microbiota", "immunometabolism", "SCFAs", "bile acids", "polyamines", "tryptophan", "bacteriocins", "immune cells", "energy metabolism", "polyphenols", "polysaccharides", "alkaloids", and "triterpenes". The changes in the composition of the gut microbiota influenced gastrointestinal disorders, whereas their metabolites, such as SCFAs, bacteriocins, and botanical metabolites, could impede gastrointestinal cancers and polyamine-, tryptophan-, and bile acid-induced carcinogenic mechanisms. GPRCs, HDACs, FXRs, and AHRs were important receptor signals for the gut microbial metabolites in influencing the development of gastrointestinal cancer. Botanical active ingredients exerted positive effects on gastrointestinal cancer by influencing the composition of gut microbes and modulating immune metabolism. Gastrointestinal cancer could be ameliorated by altering the gut microbial environment, administering botanical active ingredients for treatment, and stimulating or blocking the immune metabolism signaling molecules. Despite extensive and growing research on the microbiota, it appeared to represent more of an indicator of the gut health status associated with adequate fiber intake than an autonomous causative factor in the prevention of gastrointestinal diseases. This study detailed the pathogenesis of gastrointestinal cancers and the botanical active ingredients used for their treatment in the hope of providing inspiration for research into simpler, safer, and more effective treatment pathways or therapeutic agents in the field.

ATP, the 31P Spectral Modulus, and Metabolism.

Adenosine triphosphate (ATP) has a high intracellular millimolar concentration (ca. 2.4 mM) throughout the phylogenetic spectrum of eukaryotes, archaea, and prokaryotes. In addition, the function of ATP as a hydrotrope in the prevention of protein aggregation and maintenance of protein solubilization is essential to cellular, tissue, and organ homeostasis. The 31P spectral modulus (PSM) is a measure of the health status of cell, tissue, and organ systems, as well as of ATP, and it is based on in vivo 31P nuclear magnetic resonance (31P NMR) spectra. The PSM is calculated by dividing the area of the 31P NMR integral curve representing the high-energy phosphates by that of the low-energy phosphates. Unlike the difficulties encountered in measuring organophosphates such as ATP or any other phosphorylated metabolites in a conventional 31P NMR spectrum or in processed tissue samples, in vivo PSM measurements are possible with NMR surface-coil technology. The PSM does not rely on the resolution of individual metabolite signals but uses the total area derived from each of the NMR integral curves of the above-described spectral regions. Calculation is based on a simple ratio of the high- and low-energy phosphate bands, which are conveniently arranged in the high- and low-field portions of the 31P NMR spectrum. In practice, there is essentially no signal overlap between these two regions, with the dividing point being ca. -3 δ. ATP is the principal contributor to the maintenance of an elevated PSM that is typically observed in healthy systems. The purpose of this study is to demonstrate that (1) in general, the higher the metabolic activity, the higher the 31P spectral modulus, and (2) the modulus calculation does not require highly resolved 31P spectral signals and thus can even be used with reduced signal-to-noise spectra such as those detected as a result of in vivo analyses or those that may be obtained during a clinical MRI examination. With increasing metabolic stress or maturation of metabolic disease in cells, tissues, or organ systems, the PSM index declines; alternatively, with decreasing stress or resolution of disease states, the PSM increases. The PSM can serve to monitor normal homeostasis as a diagnostic tool and may be used to monitor disease processes with and without interventional treatment.

SLC17A1/3 transporters mediate renal excretion of Lac-Phe in mice and humans

N-lactoyl-phenylalanine (Lac-Phe) is a lactate-derived metabolite that suppresses food intake and body weight. Little is known about the mechanisms that mediate Lac-Phe transport across cell membranes. Here we identify SLC17A1 and SLC17A3, two kidney-restricted plasma membrane-localized solute carriers, as physiologic urine Lac-Phe transporters. In cell culture, SLC17A1/3 exhibit high Lac-Phe efflux activity. In humans, levels of Lac-Phe in urine exhibit a strong genetic association with the SLC17A1-4 locus. Urine Lac-Phe levels are increased following a Wingate sprint test. In mice, genetic ablation of either SLC17A1 or SLC17A3 reduces urine Lac-Phe levels. Despite these differences, both knockout strains have normal blood Lac-Phe and body weights, demonstrating SLC17A1/3-dependent de-coupling of urine and plasma Lac-Phe pools. Together, these data establish SLC17A1/3 family members as the physiologic urine Lac-Phe transporters and uncover a biochemical pathway for the renal excretion of this signaling metabolite.