RESPIRATION DEFECTS LIMIT SERINE SYNTHESIS REQUIRED FOR LUNG CANCER GROWTH AND SURVIVAL

Mitochondrial function is important for both energetic and anabolic metabolism. Pathogenic mitochondrial DNA (mtDNA) mutations directly impact these functions, resulting in the detrimental consequences seen in human mitochondrial diseases. The role of pathogenic mtDNA mutations in human cancers is less clear; while pathogenic mtDNA mutations are observed in some cancer types, they are almost absent in others. We report here that the proofreading mutant DNA polymerase gamma ( PolG D256A ) induced a high mtDNA mutation burden in non-small-cell lung cancer (NSCLC), and promoted the accumulation of defective mitochondria, which is responsible for decreased tumor cell proliferation and viability and increased cancer survival. In NSCLC cells, pathogenic mtDNA mutations increased glycolysis and caused dependence on glucose. The glucose dependency sustained mitochondrial energetics but at the cost of a decreased NAD+/NADH ratio that inhibited de novo serine synthesis. Insufficient serine synthesis, in turn, impaired the downstream synthesis of GSH and nucleotides, leading to impaired tumor growth that increased cancer survival. Unlike tumors with intact mitochondrial function, NSCLC with pathogenic mtDNA mutations were sensitive to dietary serine and glycine deprivation. Thus, mitochondrial function in NSCLC is required specifically to sustain sufficient serine synthesis for nucleotide production and redox homeostasis to support tumor growth, explaining why these cancers preserve functional mtDNA.

In brief

High mtDNA mutation burden in non-small-cell lung cancer (NSCLC) leads to the accumulation of respiration-defective mitochondria and dependency on glucose and glycolytic metabolism. Defective respiratory metabolism causes a massive accumulation of cytosolic nicotinamide adenine dinucleotide + hydrogen (NADH), which impedes serine synthesis and, thereby, glutathione (GSH) and nucleotide synthesis, leading to impaired tumor growth and increased survival.

Highlights

Proofreading mutations in Polymerase gamma led to a high burden of mitochondrial DNA mutations, promoting the accumulation of mitochondria with respiratory defects in NSCLC.Defective respiration led to reduced proliferation and viability of NSCLC cells increasing survival to cancer.Defective respiration caused glucose dependency to fuel elevated glycolysis.Altered glucose metabolism is associated with high NADH that limits serine synthesis, leading to impaired GSH and nucleotide production.Mitochondrial respiration defects sensitize NSCLC to dietary serine/glycine starvation, further increasing survival.

Abstract Figure

Cucurbitacin E Alleviates Colonic Barrier Function Impairment and Inflammation Response and Improves Microbial Composition on Experimental Colitis Models

Purpose

Cucurbitacins, which are found in a variety of medicinal plants, vegetables and fruits, were known for their diverse pharmacological and biological activities, including anticancer, anti-oxidative and anti-inflammatory effects. Cucurbitacin E, one of the major cucurbitacins, was recently proved to inhibit inflammatory response.

Methods

To explore the therapeutic effects of cucurbitacin E on colitis and the underlying mechanisms, male mice drunk water containing 2.5% dextran sulfate sodium (DSS) to establish colitis model and administrated with cucurbitacin E during and after DSS treatment. The disease activity index was scored and colonic histological damage was observed. Intestinal tight junction and inflammatory response were determined. 16S rRNA and transcriptome sequencing were performed to analyze gut microbiota composition and gene expression, respectively.

Results

We found that cucurbitacin E alleviated DSS-induced body weight loss and impaired colonic morphology. Cucurbitacin E decreased the expression of inflammatory cytokines and cell apoptosis, and maintained barrier function. Additionally, cucurbitacin E retrieved DSS-induced alterations in the bacterial community composition. Furthermore, a variety of differentially expressed genes (DEGs) caused by cucurbitacin E were enriched in several pathways including the NFκB and TNF signaling pathways as well as in Th17 cell differentiation. There was a close relationship between DEGs and bacteria such as Escherichia-Shigella and Muribaculaceae.

Conclusion

Our results revealed that cucurbitacin E may exert protective effects on colitis via modulating inflammatory response, microbiota composition and host gene expression. Our study supports the therapeutic potential of cucurbitacin E in colitis and indicates that gut microbes are potentially therapeutic targets.

Biomarkers of bipolar disorder based on metabolomics: A systematic review

Bipolar disorder (BD) is a severe affective disorder characterized by recurrent episodes of depression or mania/hypomania, which significantly impair cognitive function, life skills, and social abilities of patients. There is little understanding of the neurobiological mechanisms of BD. The diagnosis of BD is primarily based on clinical assessment and psychiatric examination, highlighting the urgent need for objective markers to facilitate the diagnosis of BD. Metabolomics can be used as a diagnostic tool for disease identification and evaluation. This study summarized the altered metabolites in BD and analyzed aberrant metabolic pathways, which might contribute to the diagnosis of BD. Search of PubMed and Web of science for human BD studies related to metabolism to identify articles published up to November 19, 2022 yielded 987 articles. After screening and applying the inclusion and exclusion criteria, 16 untargeted and 11 targeted metabolomics studies were included. Pathway analysis of the potential differential biometabolic markers was performed using the Kyoto encyclopedia of genes and genomes (KEGG). There were 72 upregulated and 134 downregulated biomarkers in the untargeted metabolomics studies using blood samples. Untargeted metabolomics studies utilizing urine specimens revealed the presence of 78 upregulated and 54 downregulated metabolites. The targeted metabolomics studies revealed abnormalities in the metabolism of glutamate and tryptophan. Enrichment analysis revealed that the differential metabolic pathways were mainly involved in the metabolism of glucose, amino acid and fatty acid. These findings suggested that certain metabolic biomarkers or metabolic biomarker panels might serve as a reference for the diagnosis of BD.

Image-guided metabolomics and transcriptomics reveal tumour heterogeneity in luminal A and B human breast cancer beyond glucose tracer uptake

BACKGROUND

Breast cancer is a metabolically heterogeneous disease, and although the concept of heterogeneous cancer metabolism is known, its precise role in human breast cancer is yet to be fully elucidated.

METHODS

We investigated in an explorative approach a cohort of 42 primary mamma carcinoma patients with positron emission tomography/magnetic resonance imaging (PET/MR) prior to surgery, followed by histopathology and molecular diagnosis. From a subset of patients, which showed high metabolic heterogeneity based on tracer uptake and pathology classification, tumour centre and periphery specimen tissue samples were further investigated by a targeted breast cancer gene expression panel and quantitative metabolomics by nuclear magnetic resonance (NMR) spectroscopy. All data were analysed in a combinatory approach.

RESULTS

[18 F]FDG (2-deoxy-2-[fluorine-18]fluoro-d-glucose) tracer uptake confirmed dominance of glucose metabolism in the breast tumour centre, with lower levels in the periphery. Additionally, we observed differences in lipid and proliferation related genes between luminal A and B subtypes in the centre and periphery. Tumour periphery showed elevated acetate levels and enrichment in lipid metabolic pathways genes especially in luminal B. Furthermore, serine was increased in the periphery and higher expression of thymidylate synthase (TYMS) indicated one-carbon metabolism increased in tumour periphery. The overall metabolic activity based on [18 F]FDG uptake of luminal B subtype was higher than that of luminal A and the difference between the periphery and centre increased with tumour grade.

CONCLUSION

Our analysis indicates variations in metabolism among different breast cancer subtypes and sampling locations which details the heterogeneity of the breast tumours. Correlation analysis of [18 F]FDG tracer uptake, transcriptome and tumour metabolites like acetate and serine facilitate the search for new candidates for metabolic tracers and permit distinguishing luminal A and B. This knowledge may help to differentiate subtypes preclinically or to provide patients guide for neoadjuvant therapy and optimised surgical protocols based on individual tumour metabolism.

Amino acid derivative of probenecid potentiates apoptosis-inducing effects of vinblastine by increasing oxidative stress in a cancer cell-specific manner

Many chemotherapeutic drugs suffer from multidrug resistance (MDR). Efflux transporters, namely ATP-binding cassettes (ABCs), that pump the drugs out of the cancer cells comprise one major reason behind MDR. Therefore, ABC inhibitors have been under development for ages, but unfortunately, without clinical success. In the present study, an l-type amino acid transporter 1 (LAT1)-utilizing derivative of probenecid (PRB) was developed as a cancer cell-targeted efflux inhibitor for P-glycoprotein (P-gp), breast cancer resistant protein (BCRP) and/or several multidrug resistant proteins (MRPs), and its ability to increase vinblastine (VBL) cellular accumulation and apoptosis-inducing effects were explored. The novel amino acid derivative of PRB (2) increased the VBL exposure in triple-negative human breast cancer cells (MDA-MB-231) and human glioma cells (U-87MG) by 10-68 -times and 2-5-times, respectively, but not in estrogen receptor-positive human breast cancer cells (MCF-7). However, the combination therapy had greater cytotoxic effects in MCF-7 compared to MDA-MB-231 cells due to the increased oxidative stress recorded in MCF-7 cells. The metabolomic study also revealed that compound 2, together with VBL, decreased the transport of those amino acids essential for the biosynthesis of endogenous anti-oxidant glutathione (GSH). Moreover, the metabolic differences between the outcomes of the studied breast cancer cell lines were explained by the distinct expression profiles of solute carriers (SLCs) that can be concomitantly inhibited. Therefore, attacking several SLCs simultaneously to change the nutrient environment of cancer cells can serve as an adjuvant therapy to other chemotherapeutics, offering an alternative to ABC inhibitors.

Investigation of the effects of T-2 toxin in chicken-derived three-dimensional hepatic cell cultures

Despite being one of the most common contaminants of poultry feed, the molecular effects of T-2 toxin on the liver of the exposed animals are still not fully elucidated. To gain more accurate understanding, the effects of T-2 toxin were investigated in the present study in chicken-derived three-dimensional (3D) primary hepatic cell cultures. 3D spheroids were treated with three concentrations (100, 500, 1000 nM) of T-2 toxin for 24 h. Cellular metabolic activity declined in all treated groups as reflected by the Cell Counting Kit-8 assay, while extracellular lactate dehydrogenase activity was increased after 500 nM T-2 toxin exposure. The levels of oxidative stress markers malondialdehyde and protein carbonyl were reduced by the toxin, suggesting effective antioxidant compensatory mechanisms of the liver. Concerning the pro-inflammatory cytokines, IL-6 concentration was decreased, while IL-8 concentration was increased by 100 nM T-2 toxin exposure, indicating the multifaceted immunomodulatory action of the toxin. Further, the metabolic profile of hepatic spheroids was also modulated, confirming the altered lipid and amino acid metabolism of toxin-exposed liver cells. Based on these results, T-2 toxin affected cell viability, hepatocellular metabolism and inflammatory response, likely carried out its toxic effects by affecting the oxidative homeostasis of the cells.

Exploring Metabolic and Gut Microbiome Responses to Paraquat Administration in Male Wistar Rats: Implications for Oxidative Stress

In this study, we examined the metabolic and gut microbiome responses to paraquat (PQ) in male Wistar rats, focusing on oxidative stress effects. Rats received a single intraperitoneal injection of PQ at 15 and 30 mg/kg, and various oxidative stress parameters (i.e., MDA, SOD, ROS, 8-isoprostanes) were assessed after three days. To explore the omic profile, GC-qTOF and UHPLC-qTOF were performed to assess the plasma metabolome; 1H-NMR was used to assess the urine metabolome; and shotgun metagenomics sequencing was performed to study the gut microbiome. Our results revealed reductions in body weight and tissue changes, particularly in the liver, were observed, suggesting a systemic effect of PQ. Elevated lipid peroxidation and reactive oxygen species levels in the liver and plasma indicated the induction of oxidative stress. Metabolic profiling revealed changes in the tricarboxylic acid cycle, accumulation of ketone body, and altered levels of key metabolites, such as 3-hydroxybutyric acid and serine, suggesting intricate links between energy metabolism and redox reactions. Plasma metabolomic analysis revealed alterations in mitochondrial metabolism, nicotinamide metabolism, and tryptophan degradation. The gut microbiome showed shifts, with higher PQ doses influencing microbial populations (e.g., Escherichia coli and Akkermansia muciniphila) and metagenomic functions (pyruvate metabolism, fermentation, nucleotide and amino acid biosynthesis). Overall, this study provides comprehensive insights into the complex interplay between PQ exposure, metabolic responses, and gut microbiome dynamics. These findings enhance our understanding of the mechanisms behind oxidative stress-induced metabolic alterations and underscore the connections between xenobiotic exposure, gut microbiota, and host metabolism.

Colonic phosphocholine is correlated with Candida tropicalis and promotes diarrhea and pathogen clearance

Diarrhea is characterized by alterations in the gut microbiota, metabolites, and host response to these changes. Studies have focused on the role of commensal bacteria in diarrhea; however, the effect of fungi on its pathogenesis remains unexplored. Here, using post-weaned piglets with or without diarrhea, we found an unexpected decrease in the abundance of Candida tropicalis in diarrheal piglets. We also observed increased accumulation of reactive oxygen species (ROS) and the formation of neutrophil extracellular traps (NETs) in the colonic tissues of diarrheal piglets. Using dectin-1-knockout mice, we found that the over-accumulation of ROS killed C. tropicalis by promoting NET formation, which was dependent on dectin-1. The decreased abundance of C. tropicalis resulted in reduced phosphocholine consumption. Then, colonic phosphocholine accumulation drives water efflux by increasing cAMP levels by activating adenylyl cyclase, which promotes the clearance of pathogenic bacteria. Collectively, we demonstrated that phosphocholine is correlated with colonic C. tropicalis and promotes diarrhea and pathogen clearance. Our results suggest that mycobiota colonizing the colon might be involved in maintaining intestinal metabolic homeostasis through the consumption of certain metabolites.

Blidingia sp. extracts improve intestinal health and reduce diarrhoea in weanling piglets

Blidingia sp. is a prominent fouling green macroalga and we previously found that extracts from Blidingia sp. alleviated intestinal inflammation in mice challenged with lipopolysaccharides. However, whether these extracts are effective in weanling piglets remains unknown. In the present study, Blidingia sp. extracts were supplemented in the diet and their effects on growth performance, incidence of diarrhoea and intestinal function in weanling piglets were explored. The results showed that diets supplemented with 0.1% or 0.5% Blidingia sp. extract significantly increased average daily body weight gain and feed intake in weanling piglets. Meanwhile, piglets supplemented with 0.5% Blidingia sp. extract showed decreased incidence of diarrhoea as well as reduced fecal water and Na+ content. Furthermore, the diet supplemented with 0.5% Blidingia sp. extracts improved intestinal morphology, as indicated by the results of hematoxylin and eosin staining. Diet supplemented with 0.5% Blidingia sp. extracts also improved tight junction function, as indicated by increased expression of Occludin, Claudin-1 and Zonula occludens-1, and alleviated the inflammatory response, as indicated by decreased tumor necrosis factor-α and interleukin-6 (IL6) contents and increased IL10 levels. Taken together, our results showed that Blidingia sp. extracts had beneficial effects in weanling piglets and we suggest that Blidingia sp. extracts could be potentially used as an additive for piglets.

Impact of Heavy Metal Exposure on Mytilus galloprovincialis Spermatozoa: A Metabolomic Investigation

Metabolomics is a method that provides an overview of the physiological and cellular state of a specific organism or tissue. This method is particularly useful for studying the influence the environment can have on organisms, especially those used as bio-indicators, e.g., Mytilus galloprovincialis. Nevertheless, a scarcity of data on the complete metabolic baseline of mussel tissues still exists, but more importantly, the effect of mussel exposure to certain heavy metals on spermatozoa is unknown, also considering that, in recent years, the reproductive system has proved to be very sensitive to the effects of environmental pollutants. In order to fill this knowledge gap, the similarities and differences in the metabolic profile of spermatozoa of mussels exposed to metallic chlorides of copper, nickel, and cadmium, and to the mixture to these metals, were studied using a metabolomics approach based on GC-MS analysis, and their physiological role was discussed. A total of 237 endogenous metabolites were identified in the spermatozoa of these mussel. The data underwent preprocessing steps and were analyzed using statistical methods such as PLS-DA. The results showed effective class separation and identified key metabolites through the VIP scores. Heatmaps and cluster analysis further evaluated the metabolites. The metabolite-set enrichment analysis revealed complex interactions within metabolic pathways and metabolites, especially involving glucose and central carbon metabolism and oxidative stress metabolism. Overall, the results of this study are useful to better understand how some pollutants can affect the specific physiological functions of the spermatozoa of this mussel, as well as for further GC-MS-based metabolomic health and safety studies of marine bivalves.

Glutathione: Lights and Shadows in Cancer Patients

In cases of cellular injury, there is an observed increase in the production of reactive oxygen species (ROS). When this production becomes excessive, it can result in various conditions, including cancerogenesis. Glutathione (GSH), the most abundant thiol-containing antioxidant, is fundamental to re-establishing redox homeostasis. In order to evaluate the role of GSH and its antioxi-dant effects in patients affected by cancer, we performed a thorough search on Medline and EMBASE databases for relevant clinical and/or preclinical studies, with particular regard to diet, toxicities, and pharmacological processes. The conjugation of GSH with xenobiotics, including anti-cancer drugs, can result in either of two effects: xenobiotics may lose their harmful effects, or GSH conjugation may enhance their toxicity by inducing bioactivation. While being an interesting weapon against chemotherapy-induced toxicities, GSH may also have a potential protective role for cancer cells. New studies are necessary to better explain the relationship between GSH and cancer. Although self-prescribed glutathione (GSH) implementation is prevalent among cancer patients with the intention of reducing the toxic effects of anticancer treatments and potentially preventing damage to normal tissues, this belief lacks substantial scientific evidence for its efficacy in reducing toxicity, except in the case of cisplatin-related neurotoxicity. Therefore, the use of GSH should only be considered under medical supervision, taking into account the appropriate timing and setting.

Metabolic adaptation of human skin fibroblasts to ER stress caused by glycosylation defect in PMM2-CDG

PMM2-CDG is the most prevalent type of congenital disorders of glycosylation (CDG). It is caused by pathogenic variants in the gene encoding phosphomannomutase 2 (PMM2), which converts mannose-6-phosphate to mannose-1-phosphate and thus activates this saccharide for further glycosylation processes. Defective glycosylation can lead to an abnormal accumulation of unfolded proteins in endoplasmic reticulum (ER) and cause its stress. The ER is a key compartment for glycosylation, and its connection and communication with mitochondria has been described extensively in literature. Their crosstalk is important for cell proliferation, calcium homeostasis, apoptosis, mitochondrial fission regulation, bioenergetics, autophagy, lipid metabolism, inflammasome formation and unfolded protein response. Therefore, in the present study we posed a question, whether defective glycosylation leads to bioenergetic disruption. Our data reveal possible chronic stress in ER and activated unfolded protein response via PERK pathway in PMM2-CDG fibroblasts. Presumably, it leads to bioenergetic reorganization and increased assembly of respiratory chain complexes into supercomplexes together with suppressed glycolysis in PMM2-CDG patient cells. These changes cause alterations in Krebs cycle, which is tightly connected to electron transport system in mitochondria. In summary, we present data showing metabolic adaptation of cells to glycosylation defect caused by various pathogenic variants in PMM2.

Homeostasis of serine enantiomers is disrupted in the post-mortem caudate putamen and cerebrospinal fluid of living Parkinson's disease patients

L-serine generated in astrocytes plays a pivotal role in modulating essential neurometabolic processes, while its enantiomer, D-serine, specifically regulates NMDA receptor (NMDAR) signalling. Despite their physiological relevance in modulating cerebral activity, serine enantiomers metabolism in Parkinson's disease (PD) remains elusive. Using High-Performance Liquid Chromatography (HPLC), we measured D- and L-serine levels along with other amino acids known to modulate NMDAR function, such as L-glutamate, L-aspartate, D-aspartate, and glycine, in the post-mortem caudate putamen (CPu) and superior frontal gyrus (SFG) of PD patients. Moreover, we examined these amino acids in the cerebrospinal fluid (CSF) of de novo living PD, Alzheimer's disease (AD), and amyotrophic lateral sclerosis (ALS) patients versus subjects with other neurological disorders (OND), used as control. We found higher D-serine and L-serine levels in the CPu of PD patients but not in the SFG, a cerebral region that, in contrast to the CPu, is not innervated by nigral dopaminergic terminals. We also highlighted a significant elevation of both serine enantiomers in the CSF samples from PD but not in those of AD and ALS patients, compared with control subjects. By contrast, none or only minor changes were found in the amount of other neuroactive amino acids mentioned above. Our findings identify D-serine and L-serine level upregulation as a biochemical signature associated with nigrostriatal dopaminergic degeneration in PD.

Effect of cadmium in the gonads of mussel (Mytilus coruscus): an ionomics and proteomics study

The mussel Mytilus coruscus is an important and very popular seafood in China and widespread along the eastern coast of China. In this study, we investigated the molecular response of mussel gonads to cadmium accumulation at two concentrations (80 and 200 µg/L) for 30 days using ionomics and proteomics techniques. The shrinkage of the cells and moderate hemocytic infiltration were observed in the Cd-treated groups. The strontium, selenium (Se), and zinc contents were significantly altered, and the relationships between iron, copper, Se, manganese, calcium, sodium, and magnesium were also significantly altered. Label-free quantitative proteomics analysis revealed a total of 227 differentially expressed proteins. These proteins were associated with multiple biological processes, including the tricarboxylic acid cycle, structural reorganization of cells, biosynthesis of amino acids, inflammatory response of cells, and tumorigenesis. Nonetheless, our ionomics and proteomics analysis revealed that mussels could partly alleviate the adverse effects of Cd by altering the metal contents and correlations between minerals, thereby enhancing the biosynthesis of some amino acids and activity of antioxidant enzymes. Overall, this study provides an insight into the mechanism underlying Cd toxicity in mussel gonads from a metal and protein perspective.

Serine Administration Improves Selenium Status, Oxidative Stress, and Mitochondrial Function in Longissimus Dorsi Muscle of Piglets with Intrauterine Growth Retardation

Intrauterine growth retardation (IUGR) causes oxidative stress in the skeletal muscle. Serine and selenoproteins are involved in anti-oxidative processes; however, whether IUGR affects selenium status and whether serine has beneficial effects remain elusive. Here, we investigated the effects of serine administration on selenium nutritional status and oxidative stress in the longissimus dorsi muscle of piglets with IUGR. Six newborn Min piglets having normal birth weight were administered saline, and 12 IUGR piglets were either administered saline or 0.8% serine. The results showed a lower selenium content in skeletal muscle in IUGR piglets, which was restored after serine administration. IUGR piglets showed a disturbed expression of genes encoding selenoproteins, with decreased expression of GPX2, GPX4, TXNRD1, and TXNRD3 and increased expression of DIO1, DIO2, SELF, SELM, SELP, and SELW. Notably, serine administration restored the expression levels of these genes. In accordance with the changes in gene expression, the activity of GPX, TXNRD, and DIO and the content of GSH and SELP were also altered, whereas serine administration restored their contents and activities. Moreover, we observed severe oxidative stress in the skeletal muscle of IUGR piglets, as indicated by decreased GSH content and increased MDA and PC content, whereas serine administration alleviated these changes. In conclusion, our results indicate that IUGR piglets showed a disturbed expression of genes encoding selenoproteins, accompanied by severe oxidative stress. Serine administration can improve selenium status, oxidative stress, and mitochondrial function in the longissimus dorsi muscle of piglets with IUGR. These results suggest that serine could potentially be used in the treatment of IUGR in piglets.

Amino Acids Drive the Deterministic Assembly Process of Fungal Community and Affect the Flavor Metabolites in Baijiu Fermentation

Nutrient fluctuation is ubiquitous in fermentation ecosystems. However, the microbial community assembly mechanism and metabolic characteristics in response to nutrient variation are still unclear. Here, we used Baijiu fermentation as a case example to study the responses of microbial community assembly and metabolic characteristics to the variation of amino acids using high-throughput sequencing and metatranscriptomics analyses. We chose two fermentation groups (group A with low amino acid and group B with high amino acid contents). The two groups showed similar succession patterns in the bacterial community, whereas they showed different succession in the fungal community wherein Pichia was dominant in group A and Zygosaccharomyces was dominant in group B. The β-nearest taxon index (βNTI) revealed that bacterial community was randomly formed, whereas fungal community assembly was a deterministic process. Variance partitioning analysis and redundancy analysis revealed that amino acids showed the largest contribution to the fungal community (37.64%, P = 0.005) and were more tightly associated with it in group B. Further study revealed that serine was positively related to Zygosaccharomyces and promoted its growth and ethanol production. Metatranscriptomic analysis revealed that the differential metabolic pathways between the two groups mainly included carbohydrate metabolism and amino acid metabolism, which explained the differences of ethanol production and volatile metabolites (such as isoamylol, isobutanol, and 2-methyl-1-butanol). Then these metabolic pathways were constructed and related gene expression and active microorganisms were listed. Our study provides a systematical understanding of the roles of amino acids in both ecological maintenance and flavor metabolism in fermentation ecosystems. IMPORTANCE In spontaneous fermented foods production, nutrient fluctuation is a critical factor affecting microbial community assembly and metabolic function. Revealing the microbial community assembly mechanism and how it regulates its metabolic characteristics in response to nutrient variation is helpful to the management of the fermentation process. This study provides a systematical understanding of the effect of amino acids on the microbial community assembly and flavor metabolisms using Baijiu fermentation as a case example. The data of this study highlight the importance of the nutrient management in fermentation ecosystems.

Is it really safe to replace decabromodiphenyl ether (BDE209) with decabromodiphenyl ethane (DBDPE)?: A perspective from hepatotoxicity

In this paper, the hepatocytotoxicity and aryl hydrocarbon receptor (AHR) activity of decabromodiphenyl ethane (DBDPE), decabromodiphenyl ether (BDE209) and other 18 analogues were evaluated in vitro using human normal liver cell L02. These dioxin-like compounds showed differential hepatocytotoxicity (EC₅₀  = 0.38-17.87 mg/L) and AHR activity (EROD activity = 4.53-46.35 U/μg). In silico study indicated the distance of π-π bonds between the benzene ring of compounds and residue Phe234 of AHR played a key role in the binding of AHR, and the substituents on the benzene ring also influenced the activity. Combining molecular biology and bioomics, the comprehensive investigations on the hepatotoxic mechanisms have demonstrated the AHR signaling pathway was the key mediation mechanism for the hepatotoxicity of DBDPE/BDE209. The cytochrome P450s (CYP2 family) mediated formation of reactive oxygenated intermediates might be the dominant toxic mechanism, which could produce oxidative stress or cause genotoxicity. Although the experimental toxicity of DBDPE was smaller relative to BDE209, the health risk of DBDPE may be much greater than we expected, due to the high potential to form a variety of dioxin-like intermediates by microbial oxidation of ethyl group. Therefore, whether it is really safe to replace BDE209 with DBDPE is a debatable question, and more ecotoxicological and health data are needed to clarify this issue.

Reduction of lead toxicity effects and enhancing the glutathione reservoir in green beans through spraying sulfur and serine and glutamine amino acids

Acid rain is one of the influential environmental factors in transport of heavy metals, including lead from the atmosphere to the surface of the earth and growing plants. Such situation can not only damage the growing plants but can also toxify the food chain, and endanger human life. In order to reduce stress damage due to lead, on green bean plant, the effect of spraying the plants by sulfur, also amino acids including serine and glutamine, was evaluated. A factorial experiment based on randomized complete block design with three replications was carried out using the green bean Sunray cultivar in 2020. Treatments include foliar application of lead at two levels (0.0 and 1 mmol) as lead acetate, foliar application of liquid sulfur at two levels (0.0 and 2 per thousand), and foliar application of amino acids at four levels (0.0, serine at 200 mg/L, glutamine at 200 mg/L, and co-application of serine and glutamine at the same concentrations) at pre-flowering stage. The results showed that leaf foliar uptake of most of the employed treatments resulted in reduction of leaf area index, leaf, stem and pods dry weight, stem diameter and height, pod yield, photosynthetic pigments such as chlorophyll a, chlorophyll b, and carotenoids, and relative leaf water content. However, grain protein content, hydrogen peroxide, and glutathione antioxidant activity significantly increased. Spraying of sulfur solution and serine and glutamine were effective in reducing the negative effects of lead stress, as it reduced the amount of hydrogen peroxide and grain protein and increased the reservoir of glutathione. These treatments also, compared to the pure lead treatment, significantly reduced lead accumulation in the pod, as the edible organ of green beans. This study results showed that foliar application of sulfur along with amino acids serine and glutamine reduced the lead toxicity effects through improving the physiological functions, and thus can increase the final yield and consequently human access to healthier food (Fig. 1). Fig. 1 Graphical abstract.

Effect of L-serine on circadian variation of cloacal and body surface temperatures in broiler chickens subjected to feed restriction during the hot-dry season

The study aimed to evaluate the effects of L-serine on circadian variation of body temperatures in feed-restricted broiler chickens during the hot-dry season. Day-old broiler chicks of both sexes served as subjects; comprising four groups of 30 chicks each: Group A: water ad libitum + 20% feed restriction (FR); Group B: feed and water ad libitum (AL); Group C: water ad libitum + 20% feed restriction + L-serine (200 mg/kg) (FR + L-serine); Group D feed and water ad libitum + L-serine (200 mg/kg) (AL + L-serine). Feed restriction was performed on days 7-14 and L-serine was administered on days 1-14. Cloacal and body surface temperatures, recorded by digital clinical and infra-red thermometers, respectively, and temperature-humidity index were obtained over 26 h on days 21, 28 and 35. Temperature-humidity index (28.07-34.03) indicated broiler chickens were subjected to heat stress. L-serine decreased (P < 0.05) cloacal temperature in FR + L-serine (40.86 ± 0.07 °C), compared to FR (41.26 ± 0.05 °C) and AL (41.42 ± 0.08 °C) broiler chickens. Peak cloacal temperature occurred at 15:00 h in FR (41.74 ± 0.21 °C), FR + L-serine (41.30 ± 0.41 °C) and AL (41.87 ± 0.16 °C) broiler chickens. Fluctuations in thermal environmental parameters influenced circadian rhythmicity of cloacal temperature; especially the body surface temperatures, positively correlated with CT, and wing temperature recorded the closest mesor. In conclusion, L-serine and feed restriction decreased cloacal and body surface temperatures in broiler chickens during the hot-dry season.

Changes of lysosome by L-serine in rotenone-treated hippocampal neurons

Oxidative stress destroys cellular organelles and damages DNA, eventually leading to degenerative brain disorders. Persistent mitochondrial damage by oxidative stress eventually causes cells to inhibit the function of lysosomes. Rotenone used in this study inhibits complex 1 of the mitochondrial electron transport chain. Due to this inhibition, the production of free radicals is promoted, and oxidative stress can occur. To test as a role of antioxidant, L-serine was treated before treatment of rotenone to HT22 hippocampal cells. Then, changes in the activity and structure of lysosomes were analyzed. As a result, the oxidative stress caused by rotenone in HT22 cells was protected by L-serine. L-serine reduced free radicals in cells, and the damaged lysosomal structure and lysosome activity were also protected.

Acute toxicity, biochemical and transcriptomic analysis of Procambarus clarkii exposed to avermectin

BACKGROUND

Pesticides are extensively applied globally. Pesticide residues induce calamitous effects on the environment and untargeted organisms. Public concerns for the safety of freshwater organisms and the challenges posed by aquatic contaminants remain high. In the present study, the acute toxicity of avermectins (AVMs) to the crayfish, Procambarus clarkii was evaluated. We also evaluated the potential effects of AVM on the biochemical and transcriptomic status of the hepatopancreas and gastrointestinal tract in P. clarkii.

RESULTS

The 24, 48, 72, 96 h median lethal concentrations (LC₅₀ ) of AVM on crayfish were 2.626, 1.162, 0.723, 0.566 mg L^-1 , respectively. The crayfish were then exposed to 0.65 mg L^-1 of AVM for 96 h. AVM significantly altered biochemical parameters including AChE and CAT activities in the hepatopancreas, and AChE, SOD and Na + -K + -ATPase activities in the gastrointestinal tract at several time points. Furthermore, transcriptomic analysis identified 953 and 1851 differentially-expressed genes (DEGs) in the hepatopancreas and gastrointestinal tract, respectively. KEGG enrichment showed that the gene expression profiles of the hepatopancreas and gastrointestinal tract were distinct from each other. The DEGs in the hepatopancreas were mostly enriched with stress-response pathways, while the majority of the DEGs in the gastrointestinal tract belonged to metabolism-related pathways.

CONCLUSION

We demonstrated that the AVM induced acute toxicity, oxidative stress, osmoregulation disturbance, neurotoxicity and transcriptome imbalance in crayfish. These findings unraveled the detrimental effects of AVMs exposure on crayfish. © 2022 Society of Chemical Industry.

Acute and chronic inflammation alter immunometabolism in a cutaneous delayed-type hypersensitivity reaction (DTHR) mouse model

T-cell-driven immune responses are responsible for several autoimmune disorders, such as psoriasis vulgaris and rheumatoid arthritis. Identification of metabolic signatures in inflamed tissues is needed to facilitate novel and individualised therapeutic developments. Here we show the temporal metabolic dynamics of T-cell-driven inflammation characterised by nuclear magnetic resonance spectroscopy-based metabolomics, histopathology and immunohistochemistry in acute and chronic cutaneous delayed-type hypersensitivity reaction (DTHR). During acute DTHR, an increase in glutathione and glutathione disulfide is consistent with the ear swelling response and degree of neutrophilic infiltration, while taurine and ascorbate dominate the chronic phase, suggesting a switch in redox metabolism. Lowered amino acids, an increase in cell membrane repair-related metabolites and infiltration of T cells and macrophages further characterise chronic DTHR. Acute and chronic cutaneous DTHR can be distinguished by characteristic metabolic patterns associated with individual inflammatory pathways providing knowledge that will aid target discovery of specialised therapeutics.

Nuclear magnetic resonance spectroscopy-based tissue metabolomics is used to define detailed temporal signatures of acute and chronic inflammation in cutaneous delayed-type hypersensitivity reaction.

Metabolic Regulation Effect and Potential Metabolic Biomarkers of Pre-Treated Delphinidin on Oxidative Damage Induced by Paraquat in A549 Cells

Delphinidin (Del) is an anthocyanin component with high in vitro antioxidant capacity. In this study, based on the screening of a cell model, gas chromatography-time of flight mass spectrometry (GC-TOF/MS) was used to evaluate the effect of Del pre-protection on the metabolite levels of intracellular oxidative stress induced by paraquat (PQ). According to the cytotoxicity and reactive oxygen species (ROS) responses of four lung cell lines to PQ induction, A549 cell was selected and treated with 100 μM PQ for 12 h to develop a cellular oxidative stress model. Compared with the PQ-induced group, the principal components of the Del pretreatment group had significant differences, but not significant with the control group, indicating that the antioxidant activity of Del can be correlated to the maintenance of metabolite levels. Del preconditioning protects lipid-related metabolic pathways from the disturbance induced by PQ. In addition, the levels of amino acid- and energy-related metabolites were significantly recovered. Del may also exert an antioxidant effect by regulating glucose metabolism. The optimal combinations of biomarkers in the PQ-treatment group and Del-pretreatment group were alanine-valine-urea and alanine-galactose-glucose. Cell metabolome data provided characteristic fingerprints associated with the antioxidant activity of Del.

Profiling subcellular localization of nuclear-encoded mitochondrial gene products in zebrafish

Most mitochondrial proteins are encoded by nuclear genes, synthetized in the cytosol and targeted into the organelle. To characterize the spatial organization of mitochondrial gene products in zebrafish (Danio rerio), we sequenced RNA from different cellular fractions. Our results confirmed the presence of nuclear-encoded mRNAs in the mitochondrial fraction, which in unperturbed conditions, are mainly transcripts encoding large proteins with specific properties, like transmembrane domains. To further explore the principles of mitochondrial protein compartmentalization in zebrafish, we quantified the transcriptomic changes for each subcellular fraction triggered by the chchd4a ^-/- mutation, causing the disorders in the mitochondrial protein import. Our results indicate that the proteostatic stress further restricts the population of transcripts on the mitochondrial surface, allowing only the largest and the most evolutionary conserved proteins to be synthetized there. We also show that many nuclear-encoded mitochondrial transcripts translated by the cytosolic ribosomes stay resistant to the global translation shutdown. Thus, vertebrates, in contrast to yeast, are not likely to use localized translation to facilitate synthesis of mitochondrial proteins under proteostatic stress conditions.

Administration of selenomethionine in combination with serine benefits diabetes via gut microbiota

Either selenium or serine could modulate glucose homeostasis, however, whether there are synergistic effects of selenium with serine on diabetes remains to be unknown. In the present study, eight male db/m mice were used as a control, and 24 male diabetic db/db mice were either orally gavaged with PBS, or with selenomethionine alone, or with both selenomethionine and serine, to investigate the effects of selenomethionine and serine on body weight and glucose level. Furthermore, intestinal microbiota composition was analyzed and fecal microbiota transplantation (FMT) was performed to explore whether microbes mediate the beneficial effects of selenomethionine and serine. The results showed that administration of selenomethionine decreased body weight, adipose tissue weight and serum glucose level in db/db diabetic mice. Importantly, administration of selenomethionine in combination with serine exerted better effects than selenomethionine alone did. Furthermore, a combined administration of selenomethionine and serine restored the microbial composition in diabetic mice. Corynebacterium glutamicum, Bifidobacterium pseudolongum, and Aerococcus urinaeequi were significantly decreased, whereas Lactobacillus murinus was increased in mice in the selenomethionine group and selenomethionine in combination with serine group, when compared with those in the db/db group. FMT decreased body weight and glucose level in db/db mice, further indicating that microbes play critical roles in the beneficial effects of selenomethionine and serine. Thus, we concluded that administration of selenomethionine in combination with serine benefits diabetes via gut microbes. Our results suggested that the synergic application of selenomethionine and serine could be potentially used for the treatment of diabetes.

Glutathione: pharmacological aspects and implications for clinical use

Glutathione is a tripeptide found in many tissues which plays a pivotal role in critical physiological processes such as maintenance of redox balance, reduction of oxidative stress by enhancement of metabolic detoxification of both xenobiotic and endogenous compounds, and regulation of immune system function. Glutathione depletion is associated with many chronic degenerative diseases and loss of function with aging and altered glutathione metabolism has been implicated in central nervous system diseases, frailty and sarcopenia, infected state, chronic liver diseases, metabolic diseases, pulmonary and cardiovascular diseases. Therefore, the glutathione status may be an important biomarker and treatment target in various chronic, age-related diseases. Here we describe the main pharmacological aspects of glutathione, focusing on its synthesis and role in several vital functions including antioxidant defense, detoxification of xenobiotics and modulation of immune function and fibrogenesis and the clinical implications of its depletion and we discuss the different strategies for increasing glutathione cellular levels either by providing specific precursors and cofactors or directly administering the tripeptide.

Metabolomics analysis identifies glutamic acid and cystine imbalances in COVID-19 patients without comorbid conditions. Implications on redox homeostasis and COVID-19 pathophysiology

It is well known that the presence of comorbidities and age-related health issues may hide biochemical and metabolic features triggered by SARS-CoV-2 infection and other diseases associated to hypoxia, as they are by themselves chronic inflammatory conditions that may potentially disturb metabolic homeostasis and thereby negatively impact on COVID-19 progression. To unveil the metabolic abnormalities inherent to hypoxemia caused by COVID-19, we here applied gas chromatography coupled to mass spectrometry to analyze the main metabolic changes exhibited by a population of male patients less than 50 years of age with mild/moderate and severe COVID-19 without pre-existing comorbidities known to predispose to life-threatening complications from this infection. Several differences in serum levels of particular metabolites between normal controls and patients with COVID-19 as well as between mild/moderate and severe COVID-19 were identified. These included increased glutamic acid and reduced glutamine, cystine, threonic acid, and proline levels. In particular, using the entire metabolomic fingerprint obtained, we observed that glutamine/glutamate metabolism was associated with disease severity as patients in the severe COVID-19 group presented the lowest and higher serum levels of these amino acids, respectively. These data highlight the hypoxia-derived metabolic alterations provoked by SARS-CoV-2 infection in the absence of pre-existing co-morbidities as well as the value of amino acid metabolism in determining reactive oxygen species recycling pathways, which when impaired may lead to increased oxidation of proteins and cell damage. They also provide insights on new supportive therapies for COVID-19 and other disorders that involve altered redox homeostasis and lower oxygen levels that may lead to better outcomes of disease severity.

Effects of insufficient serine on health and selenoprotein expression in rats and their offspring

Objective

To observe the impact of insufficient exogenous and/or endogenous serine on selenoprotein expression and health of pregnant rats and their offspring.

Method

Experiment 1 was conducted in male rats, in which the dose-dependent effects of serine on selenoprotein expression and thyroid hormones (T3, T4 and TSH) were investigated by feeding either a serine adequate diet (20C), serine-deprived diet (20CSD) or 20CSD with different serine levels (0.5, 1.0, and 2.0 times the amount of serine in 20C). In experiment 2, a PHGDH inhibitor was administrated to pregnant rats fed either 20C or 20CSD. Blood and organ tissues of pregnant rats and offspring were subjected to the analyses of thyroid hormone, serine and homocysteine and GPx3 and SELENOP in plasma and expression of GPx1 and DIO1, 2 in tissues respectively.

Result

In experiment 1, plasma SELENOP and GPx3 levels in adult male rats increased with the increasing dose of serine. Immunohistochemical results showed that GPx1 expression in liver and kidney of male rats also increased with increasing serine supplementation. Amongst all diet groups, only male rats fed 20CSD had significantly lower plasma TSH and T4 levels (P < 0.05). In experiment 2, GPx1 and DIO2 expression in the liver and kidney were suppressed in pregnant rats administered with a PHGDH compared to those who were not (P < 0.05). There were no significant differences in plasma T4 and T3 amongst all diet groups (P > 0.05). Also, offspring born to pregnant rats administered with a PHGDH inhibitor exhibited slower growth rates and hyperhomocysteinemia compared to offspring from mothers not administered with the inhibitor (P < 0.05). Conclusions: Insufficient exogenous serine through the diet decreased selenoprotein synthesis in adult male rats. However, this was not observed in pregnant rats, whereby exogenous or endogenous serine deficiency had no effect on the selenoprotein levels. A possible explanation is that dams may have an adaptive mechanism to limit maternal serine utilization and ensure adequate supply to the fetus.

Coevolution of Rumen Epithelial circRNAs with Their Microbiota and Metabolites in Response to Cold-Season Nutritional Stress in Tibetan Sheep

This study explores the effects of the coevolution of the host genome (the first genome) and gut microbiome (the second genome) on nutrition stress in Tibetan sheep during the cold season. The rumen epithelial tissue of six Tibetan sheep (Oula-type) was collected as experimental samples during the cold and warm seasons and the study lasted for half a year. The cDNA library was constructed and subjected to high-throughput sequencing. The circRNAs with significant differential expression were identified through bioinformatics analysis and functional prediction, and verified by real-time quantitative PCR (qRT-PCR). The results showed that a total of 56 differentially expressed (DE) circRNAs of rumen epithelial tissue were identified using RNA-seq technology, among which 29 were significantly upregulated in the cold season. The circRNA-miRNA regulatory network showed that DE circRNAs promoted the adaptation of Tibetan sheep in the cold season by targeting miR-150 and oar-miR-370-3p. The results of correlation analysis among circRNAs, microbiota, and metabolites showed that the circRNA NC_040275.1:28680890|28683112 had a very significant positive correlation with acetate, propionate, butyrate, and total volatile fatty acid (VFA) (p < 0.01), and had a significant positive correlation with Ruminococcus-1 (p < 0.05). In addition, circRNA NC_040256.1:78451819|78454934 and metabolites were enriched in the same KEGG pathway biosynthesis of amino acids (ko01230). In conclusion, the host genome and rumen microbiome of Tibetan sheep co-encoded a certain glycoside hydrolase (β-glucosidase) and coevolved efficient VFA transport functions and amino acid anabolic processes; thus, helping Tibetan sheep adapt to nutrient stress in the cold season in high-altitude areas.

Serum metabolomics reveals an innovative diagnostic model for salivary gland tumors

An early diagnosis of salivary gland tumors (SGTs) and determination of their malignancy are conducive to developing individualized therapeutic strategies and thus improving prognosis. The aim of this study was to investigate the difference of serum metabolic profiles in patients with SGTs to better understand the mechanism of this disease and disease risk stratification. We used ultrahigh-performance liquid chromatography Q Exactive mass spectrometry and multivariate statistical analyses to conduct a comprehensive analysis of serum metabolites in a population with normal control and SGTs. 32 differentially expressed metabolites were identified, while the level of serine and lactic acid were investigated to gradually upregulate in benign SGTs and malignant SGTs. Then, the expression of serine and lactic acid were assessed in validation cohort using multiple reaction monitoring (MRM) based targeted metabolite analysis. A risk score formula based on the amount of serine and lactic acid was developed and explored to be significantly related to benign SGTs and malignant SGTs in discovery and validation cohort. Our work highlights the possible use of the risk score assessment based on the serum metabolites not only reveal in the early diagnosis of SGTs but also assist in enhancing current therapeutic strategies in the clinic.

Jellyfish Collagen Hydrolysate Alleviates Inflammation and Oxidative Stress and Improves Gut Microbe Composition in High-Fat Diet-Fed Mice

The collagen from jellyfish has many beneficial effects, including antioxidant, anti-inflammatory and immune-modulatory activities. However, whether jellyfish collagen hydrolysate (JCH) has any effects on high-fat diet-induced obesity remains unknown. Consequently, we in the present study orally administrated JCH in high-fat diet-fed mice to explore its effects on body weight gain, inflammatory and oxidative status, and cecum microbe composition. The results showed that oral administration of JCH prevented the body weight gain in high-fat diet-treated mice. Meanwhile, glucose, triglycerides, and total cholesterol level in serum were maintained by JCH administration. Furthermore, JCH administration alleviated oxidative stress by increasing the GSH content and decreasing the level reactive oxygen species in the liver and improved inflammatory response by decreasing the expression of TNF-α, IL-1β, and IL-8 gene in the liver and ileum. Importantly, JCH administration helps recover the alteration of microbiota composition induced by high-fat diet, and the genus Romboutsia may critically involve in the beneficial effects of JCH administration. In conclusion, our results indicated that JCH could be potentially used for the prevention and treatment of diet-induced obesity.

Effects of l-Serine on Macrolide Resistance in Streptococcus suis

Streptococcus suis is an important zoonotic pathogen. Due to the indiscriminate use of macrolides, S. suis has developed a high level of drug resistance, which has led to a serious threat to human and animal health. However, it takes a long time to develop new antibacterial drugs. Therefore, we consider the perspective of bacterial physiological metabolism to ensure that the development of bacterial resistance to existing drugs is alleviated and bacterial susceptibility to drugs is restored. In the present study, an untargeted metabolomics analysis showed that the serine catabolic pathway was inhibited in drug-resistant S. suis. The addition of l-serine restored the fungicidal effect of macrolides on S. suisin vivo and in vitro by enhancing the serine metabolic pathway. Further studies showed that l-serine, stimulated by its serine catabolic pathway, inhibited intracellular H₂S production, reduced Fe-S cluster production, and restored the normal occurrence of the Fenton reaction in cells. It also attenuated the production of glutathione, an important marker of the intracellular oxidation-reduction reaction. All these phenomena eventually contribute to an increase in the level of reactive oxygen species, which leads to intracellular DNA damage and bacterial death. Our study provides a potential new approach for the treatment of diseases caused by drug-resistant S. suis.

IMPORTANCE The emergence of antimicrobial resistance is a global challenge. However, new drug development efforts consume considerable resources and time, and alleviating the pressure on existing drugs is the focus of our work. We investigated the mechanism of action of l-serine supplementation in restoring the use of macrolides in S. suis, based on the role of the serine catabolic pathway on reactive oxygen species levels and oxidative stress in S. suis. This pathway provides a theoretical basis for the rational use of macrolides in clinical practice and also identifies a possible target for restoring drug sensitivity in S. suis.

Intestinal accumulation of microbiota-produced succinate caused by loss of microRNAs leads to diarrhea in weanling piglets

Diarrheal disease is a common health problem with complex causality. Although diarrhea is accompanied by disturbances in microbial diversity, how gut microbes are involved in the occurrence of diarrhea remains largely unknown. Here, using a pig model of post-weaning stress-induced diarrhea, we aim to elucidate and enrich the mechanistic basis of diarrhea. We found significant alterations in fecal microbiome, their metabolites, and microRNAs levels in piglets with diarrhea. Specifically, loss of ssc-miRNA-425-5p and ssc-miRNA-423-3p, which inhibit the gene expression of fumarate reductase (frd) in Prevotella genus, caused succinate accumulation in piglets, which resulted in diarrhea. Single-cell RNA sequencing indicated impaired epithelial function and increased immune response in the colon of piglet with diarrhea. Notably, the accumulated succinate increased colonic fluid secretion by regulating transepithelial Cl-secretion in the epithelial cells. Meanwhile, succinate promoted colonic inflammatory responses by activating MyD88-dependent TLR4 signaling in the macrophages. Overall, our findings expand the mechanistic basis of diarrhea and suggest that colonic accumulation of microbiota-produced succinate caused by loss of miRNAs leads to diarrhea in weanling piglets.

Atrazine exposure and recovery alter the intestinal structure, bacterial composition and intestinal metabolites of male Pelophylax nigromaculatus

The pesticide atrazine poses a potential threat to the health of frogs living in farmland areas. The exposure concentration in traditional pesticide experiments is usually constant, while pesticide pollution in actual water may fluctuate due to periodic or seasonal application. We examined the effects of different concentrations of atrazine (50, 100 and 500 μg/L) over a 14-day exposure and a 7-day recovery on intestinal histology, bacterial composition and intestinal metabolites of male Pelophylax nigromaculatus. HE staining revealed that after a 14-day atrazine exposure, the 100 μg/L and 500 μg/L groups showed obvious cysts and significantly decreased intestinal crypt depth and villus height. After a 7-day recovery, the damaged intestine in the 100 μg/L group was partially recovered, while in the 500 μg/L exposure group there was no improvement. 16S rRNA gene analysis of intestinal bacteria showed that 500 μg/L atrazine exposure significantly caused a persistent decrease in bacterial α diversity. Compared to the control and other atrazine exposure groups, the 500 μg/L group showed significant changes in the relative abundance of predominant bacteria. In addition, most dominant bacteria in the 500 μg/L recovery group showed significant differences with the 50 μg/L and 100 μg/L recovery groups. Nontargeted metabolomics profiling based on UPLC/MS analysis showed that atrazine exposure and recovery induced changes in the intestinal metabolic profile. The changes in metabolites were mainly related to purine/pyrimidine metabolism, glycine, serine and threonine metabolism, and arginine and proline metabolism. In general, these pathways were closely related to energy metabolism and amino acid metabolism. These results suggest that the short-term exposure to 500 μg/L atrazine causes persistent harm to intestinal health. This study is an important step toward a better understanding of the toxic effects of atrazine exposure and recovery in frog intestines.

miR-2a and miR-279 are functionally associated with cold tolerance in Dermacentor silvarum (Acari: Ixodidae)

Ticks are obligate blood-sucking ectoparasites that can attack mammals, birds, reptiles as well as amphibians. Dermacentor silvarum, an important vector of various pathogenic bacteria, viruses, and protozoans, is widely distributed in China. MicroRNAs (miRNAs) are ~22 nucleotide non-coding small RNA molecules, involved in the regulation of various physiological and cellular processes. Previous studies demonstrated the vital roles of miRNAs during the reproduction and development of ticks, whereas, the regulatory/functional roles of microRNAs during the cold response of ticks remain unexplored. Here, we identified and functionally explored D. silvarum miRNAs involved in cold response to gain further understanding of the molecular regulatory mechanisms underlying cold stress in ticks. The microRNA libraries of D. silvarum were established via high-throughput sequencing after exposure to different cold treatments. A total of 147 miRNAs, including 44 known miRNAs and 103 new miRNAs, were identified. The verification of six highly differentially expressed miRNAs (miR-2a, miR-5305, miR-7, miR-279, miR-993, and novel-3) via RT-qPCR were consistent with the high-throughput sequence results. miR-2a peaked by day 6 and miR-279 expression was lowest by day 3 after cold treatment. The potential target genes of miR-2a and miR-279 were the glycogen phosphorylase (GPase) gene and serine gene, respectively. After injecting D. silvarum ticks with miR-2a and miR-279 antagonists, their respective target genes were up-regulated and vice-versa after injection with the agonists. These results indicated that these two miRNAs and their target genes may be involved in the cold response of D. silvarum ticks.

Fecal miR-142a-3p from dextran sulfate sodium-challenge recovered mice prevents colitis by promoting the growth of Lactobacillus reuteri

Feces are enriched with microRNAs (miRNAs) that shape the gut microbiota. These miRNAs are differentially expressed in the feces of healthy and diseased subjects. However, whether fecal miRNAs in subjects with inflammatory bowel diseases are involved in regulating microbiota composition and whether they have any beneficial effects remains unknown. Here, we studied the fecal microbiome composition and miRNA abundance in mice with dextran sulfate sodium (DSS)-induced colitis and mice at the recovery phase to explore different miRNAs expressed, their relations with microbial abundance, and their effects on colitis. We found that miR-142a-3p expression was significantly increased in the feces of mice recovered from colitis and that it could alleviate disease symptoms in mice treated with DSS in a microbiome-dependent manner. Specifically, miR-142a-3p promoted the growth of Lactobacillus reuteri, which had a high abundance in the feces of mice recovered from colitis, by regulating transcripts of polA and locus tag LREU_RS03575. Moreover, L. reuteri, as well as its metabolite reuterin, could alleviate DSS-induced disease symptoms. These results highlight the role of fecal miR-142a-3p in the prevention of colitis. We propose that the feces of subjects who have recovered from diseases might be enriched with miRNAs with preventive effects against those diseases.

Murine endothelial serine palmitoyltransferase 1 (SPTLC1) is required for vascular development and systemic sphingolipid homeostasis

Serine palmitoyl transferase (SPT), the rate-limiting enzyme in the de novo synthesis of sphingolipids (SL), is needed for embryonic development, physiological homeostasis, and response to stress. The functions of de novo SL synthesis in vascular endothelial cells (EC), which line the entire circulatory system, are not well understood. Here, we show that the de novo SL synthesis in EC not only regulates vascular development but also maintains circulatory and peripheral organ SL levels. Mice with an endothelial-specific gene knockout of SPTLC1 (Sptlc1 ECKO), an essential subunit of the SPT complex, exhibited reduced EC proliferation and tip/stalk cell differentiation, resulting in delayed retinal vascular development. In addition, Sptlc1 ECKO mice had reduced retinal neovascularization in the oxygen-induced retinopathy model. Mechanistic studies suggest that EC SL produced from the de novo pathway are needed for lipid raft formation and efficient VEGF signaling. Post-natal deletion of the EC Sptlc1 also showed rapid reduction of several SL metabolites in plasma, red blood cells, and peripheral organs (lung and liver) but not in the retina, part of the central nervous system (CNS). In the liver, EC de novo SL synthesis was important for acetaminophen-induced rapid ceramide elevation and hepatotoxicity. These results suggest that EC-derived SL metabolites are in constant flux between the vasculature, circulatory elements, and parenchymal cells of non-CNS organs. Taken together, our data point to the central role of the endothelial SL biosynthesis in maintaining vascular development, neovascular proliferation, non-CNS tissue metabolic homeostasis, and hepatocyte response to stress.

Chlorogenic acid improves glucose tolerance, lipid metabolism, inflammation and microbiota composition in diabetic db/db mice

INTRODUCTION

Chronic and acute chlorogenic acid (CGA) can improve glucose tolerance (GT) and insulin sensitivity (IS). However, whether acute administration of CGA has beneficial effects on hepatic lipid metabolism and cecal microbiota composition remains unclear.

METHODS

In the current study, diabetic db/db mice were administered CGA or metformin, and db/m mice were used as controls to explore the effects of CGA on hepatic lipid metabolism, including fatty acid oxidation and transportation and triglyceride (TG) lipolysis and synthesis. Moreover, alterations in the inflammatory response and oxidative stress in the liver and gut microbe composition were evaluated.

RESULTS

The results showed that CGA decreased body weight and improved glucose tolerance and insulin resistance, and these effects were similar to those of metformin. CGA decreased hepatic lipid content by increasing the expression of CPT1a (carnitine palmitoyltransferase 1a), ACOX1 (Acyl-CoA oxidase 1), ATGL (adipose triglyceride lipase), and HSL (hormone-sensitive lipase) and decreasing that of MGAT1 (monoacylglycerol O-acyltransferase 1), DGAT1 (diacylglycerol O-acyltransferase), DGAT2, CD36, and FATP4 (fatty acid transport protein 4). Additionally, CGA restored the expression of inflammatory genes, including TNF-α (tumor necrosis factor-alpha), IL-1β (interleukin-1beta), IL-6, and IL-10, and genes encoding antioxidant enzymes, including SOD1 (superoxide dismutases 1), SOD2 (superoxide dismutases 2), and GPX1 (glutathione peroxidase 1). Furthermore, CGA improved the bacterial alpha and beta diversity in the cecum. Moreover, CGA recovered the abundance of the phylum Bacteroidetes and the genera Lactobacillus, Blautia, and Enterococcus.

DISCUSSION

CGA can improve the antidiabetic effects, and microbes may critically mediate these beneficial effects.

Serine and one-carbon metabolisms bring new therapeutic venues in prostate cancer

Serine and one-carbon unit metabolisms are essential biochemical pathways implicated in fundamental cellular functions such as proliferation, biosynthesis of important anabolic precursors and in general for the availability of methyl groups. These two distinct but interacting pathways are now becoming crucial in cancer, the de novo cytosolic serine pathway and the mitochondrial one-carbon metabolism. Apart from their role in physiological conditions, such as epithelial proliferation, the serine metabolism alterations are associated to several highly neoplastic proliferative pathologies. Accordingly, prostate cancer shows a deep rearrangement of its metabolism, driven by the dependency from the androgenic stimulus. Several new experimental evidence describes the role of a few of the enzymes involved in the serine metabolism in prostate cancer pathogenesis. The aim of this study is to analyze gene and protein expression data publicly available from large cancer specimens dataset, in order to further dissect the potential role of the abovementioned metabolism in the complex reshaping of the anabolic environment in this kind of neoplasm. The data suggest a potential role as biomarkers as well as in cancer therapy for the genes (and enzymes) belonging to the one-carbon metabolism in the context of prostatic cancer.

Serine Supplementation Alleviates Doxorubicin-Induced Oxidative Damage in Skeletal Muscle of Mice

Muscle weakness affects physical activity and quality of life of patients. Serine, a nutritionally non-essential amino acid has been reported to enhance protein synthesis and implicate in biosynthesis of multiple bioactive molecules. It remains unknown whether it can protect mice against oxidative stress-induced muscles weakness. This study was conducted to test the hypothesis that serine administration alleviates doxorubicin-induced oxidative damage in skeletal muscle of mice. Mice pre-treated with or without serine were intraperitoneally injected with either doxorubicin or equal volume of saline. Reactive oxygen species (ROS) accumulation, activity of antioxidant enzymes, oxidation product of protein, DNA, and lipid, activity of mitochondrial complex, and protein level of nuclear-factor-erythroid-2-related factor 2 (NRF2)/constitutive-androstane-receptor (CAR) signaling in skeletal muscle of mice were determined. Compared with the control, doxorubicin exposure led to oxidative damage as shown by increased ROS accumulation, decreased activity of antioxidant enzymes, and enhanced oxidative product of protein, DNA, and lipid in the skeletal muscle of mice. These effects of doxorubicin were associated with increased activity of complex I and reduced glutathione. Interestingly, doxorubicin-induced oxidative damage was alleviated by serine administration. Further study showed that the beneficial effect of serine was associated with enhanced NRF2/CAR signaling. Our result showed that serine attenuated doxorubicin-induced muscle weakness in mice. Serine supplementation might be a nutritional strategy to improve the function of skeletal muscle in patients exposed to doxorubicin.

Dietary serine supplementation: Friend or foe?

Serine lies at a critical node in biological processes involved in supplying intermediates for redox homeostasis, nucleotide, or lipid biosynthesis and one-carbon metabolism-coupled methyl donor production. Recently, dietary serine supplementation has been reported to modulate cellular serine levels and ameliorate neurological abnormalities induced by serine deficiency. Moreover, growing evidence showed that serine supplementation also alleviates fatty liver, encephalopathy, diabetes mellitus, and related complications, indicating the possibility of serine supplementation as a complementary therapeutic option. However, considering the serine addiction observed in tumorigenesis and tumor development, limitations may exist regarding the application of dietary serine supplementation in patients with cancer. Here, we assess recent research toward the mechanistic understanding of serine supplementation in various diseases to improve our cognition on modulating serine levels in different patients.

Toxic effects of fipronil and its metabolites on PC12 cell metabolism

Fipronil and its metabolites (fipronil sulfone, fipronil sulfide and fipronil desulfinyl) adversely affect the environment and human health. Targeted metabolomics and lipidomics based on ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was used to analyse the alterations of glycerophospholipids and amino acids after exposure to fipronil and its metabolites at dosages of 0.5, 12.5 and 50 μM for 72 h and to evaluate their different toxic effects. Results showed that fipronil sulfone and fipronil desulfinyl are more toxic than their parent compound, with fipronil desulfinyl as the most toxic and fipronil sulfide as the least toxic. Fipronil and its metabolites affected the metabolism of PC18:1/16:0, PI18:0/20:4, arginine, leucine and tyrosine and the "phenylalanine, tyrosine and tryptophan biosynthesis" pathway, indicating their possible inducing role in cellular macromolecule damage, nerve signal transmission disturbance and energy metabolism disruption caused by oxidative stress. Importantly, fipronil sulfone and fipronil desulfinyl more strongly influenced lipid and amino acid metabolism, mainly reflected in the number of changed glycerophospholipids and differential metabolites associated with oxidative stress, including PS18:0/20:4, glutamate, phenylalanine and histidine for fipronil sulfone and PS18:0/20:4, glutamate, phenylalanine, serine and aspartic acid for fipronil desulfinyl. Therefore, the higher toxicity of fipronil desulfinyl and fipronil sulfone may be also related to oxidative stress. This study provides implications for risk assessment and toxic mechanism research on fipronil and its metabolites.

MiADMSA abrogates sodium tungstate-induced oxidative stress in rats

Tungsten (W) and its compounds have emerged as a relatively new area of environmental health concern in the last decade. Tungsten is environmentally benign due to its increasing use in armour-piercing munitions and as a replacement for lead in other ammunition. It has also been identified in various hazardous waste sites and therefore been proposed for inclusion in the Environmental Protection Agency National Priorities List. The major objective of this study was to evaluate the therapeutic efficacy of orally administered monoisoamyl 2, 3-dimercaptosuccinic acid (MiADMSA) against tungstate induced oxidative injury in blood, liver and kidneys of male Wistar rats. MiADMSA, a thiol chelator has gained wide recognition recently as a future chelating drug of choice specifically for arsenic and was chosen for this study as tungstate ions too have an affinity toward the -SH group thus, being less bioavailable in the body. We determined the effects of MiADMSA (50 mg/kg, p.o.) against sodium tungstate (500 ppm in drinking water, daily for 28 days) induced biochemical changes indicative of oxidative stress in blood, and other soft tissues of of male Wistar rats. Tungsten exposure led to an increased levels of Reactive Oxygen Species (ROS) in liver, kidney, spleen and blood accompanied also by an increase in TBARS levels. The GSH: GSSG ratio also showed a decrease on sodium tungstate intoxication. Treatment with MiADMSA restored most of the sodium tungstate-induced alterations in the biomarkers suggestive of oxidative stress. These preliminary results led us to conclude that sub-acute exposure to tungstate-induced oxidative stress could be effectively reduced by the administration of MiADMSA and thus might be a promising antidote for studying in detail its efficacy in reducing body tungstate burden and its excretion post tungstate exposure.

ASC-1 transporter-dependent amino acid uptake is required for the efficient thermogenic response of human adipocytes to adrenergic stimulation

Brown and beige adipocytes dissipate energy by uncoupling protein 1 (UCP1)-dependent and UCP1-independent thermogenesis, which may be utilized to develop treatments against obesity. We have found that mRNA and protein expression of the alanine/serine/cysteine transporter-1 (ASC-1) was induced during adipocyte differentiation of human brown-prone deep neck and beige-competent subcutaneous neck progenitors, and SGBS preadipocytes. cAMP stimulation of differentiated adipocytes led to elevated uptake of serine, cysteine, and glycine, in parallel with increased oxygen consumption, augmented UCP1-dependent proton leak, increased creatine-driven substrate cycle-coupled respiration, and upregulation of thermogenesis marker genes and several respiratory complex subunits; these outcomes were impeded in the presence of the specific ASC-1 inhibitor, BMS-466442. Our data suggest that ASC-1-dependent consumption of serine, cysteine, and glycine is required for efficient thermogenic stimulation of human adipocytes.

GC-MS-Based Serum Metabolomic Investigations on the Ameliorative Effects of Polysaccharide from Turpiniae folium in Hyperlipidemia Rats

Hyperlipidemia, a typical metabolic disorder syndrome, can cause various cardiovascular diseases. The polysaccharides were found to have enormous potential in the therapy of hyperlipidemia. This study was aimed at evaluating the ameliorative effects of polysaccharide from Turpiniae folium (TFP) in rats with hyperlipidemia. A serum metabolomic method based on gas chromatography-mass spectrometry (GC-MS) was used to explore the detailed mechanism of TFP in rats with hyperlipidemia. The oxidative stress indicators, biochemical indexes, and inflammatory factors in serum and histopathological changes in the liver were also evaluated after 10-week oral administration of TFP in rats with high-fat diet-induced hyperlipidemia. TFP significantly relieved oxidative stress, inflammation, and liver histopathology and reduced blood lipid levels. Multivariate statistical approaches such as principal component analysis and orthogonal projection to latent structure square-discriminant analysis revealed clear separations of metabolic profiles among the control, HFD, and HFD+TFP groups, indicating a moderating effect of TFP on the metabolic disorders in rats with hyperlipidemia. Seven metabolites in serum, involved in glycine, serine, and threonine metabolism and aminoacyl-tRNA biosynthesis, were selected as potential biomarkers in rats with hyperlipidemia and regulated by TFP administration. It was concluded that TFP had remarkable potential for treating hyperlipidemia. These findings provided evidence for further understanding of the mechanism of action of TFP on hyperlipidemia.

Dietary Supplementation with Glycine Enhances Intestinal Mucosal Integrity and Ameliorates Inflammation in C57BL/6J Mice with High-Fat Diet-Induced Obesity

BACKGROUND

Obesity, a major public health problem worldwide, is associated with dysfunction of the intestinal barrier. Glycine (Gly) has been reported to enhance the expression of tight-junction proteins in porcine enterocytes. It is unknown whether Gly can improve intestinal barrier integrity in obese mice.

OBJECTIVES

This study tested the hypothesis that Gly enhances the intestinal epithelial barrier by regulating endoplasmic reticulum (ER) stress-related signaling and mitigating inflammation in high-fat diet (HFD)-induced obese mice.

METHODS

Five-week-old male C57BL/6J mice were fed a normal-fat diet (ND; fat = 10% energy) or an HFD (fat = 60% energy) and received drinking water supplemented with 2% Gly or 2.37% l-alanine (Ala; isonitrogenous control) daily for 12 wk. Body weight gain and tissue weights, glucose tolerance and the activation of immune cells, as well as the abundances of tight-junction proteins, ER stress proteins, and apoptosis-related proteins in the jejunum and colon were determined. In addition, the body weights of naïve ND and HFD groups (nND and nHFD, respectively) were also recorded for comparison. Differences were analyzed statistically by ANOVA followed by the Duncan multiple-comparison test using SAS software.

RESULTS

Compared with ND-Ala, HFD-feeding resulted in enhanced macrophage (CD11b+ and F4/80+) infiltration and immune cell activation by 1.9- to 5.4-fold (P < 0.05), as well as the upregulation of ER stress sensor proteins (including phospho-inositol-requiring enzyme 1α and binding immunoglobulin protein) by 2.5- to 4.5-fold, the induction of apoptotic proteins by 1.5- to 3.2-fold, and decreased abundances of tight-junction proteins by 35%-65% (P < 0.05) in the intestine. These HFD-induced abnormalities were significantly ameliorated by Gly supplementation in the HFD-Gly group (P < 0.05). Importantly, Gly supplementation also significantly enhanced glucose tolerance (P < 0.05) by 1.5-fold without affecting the fat accumulation of HFD-induced obese mice.

CONCLUSIONS

Gly supplementation enhanced the intestinal barrier and ameliorated inflammation and insulin resistance in HFD-fed mice. These effects of Gly were associated with reduced ER stress-related apoptosis in the intestine of obese mice.

Effects of Glucose Oxidase Supplementation on the Growth Performance, Antioxidative and Inflammatory Status, Gut Function, and Microbiota Composition of Broilers Fed Moldy Corn

Background

Glucose oxidase is widely used as a livestock feed additive owing to its beneficial effects on growth performance and antioxidant activity. However, little is known about the effects of the enzyme on intestinal health.

Methods

To investigate the effects of glucose oxidase supplementation on the growth performance, intestinal function, and microbiota composition of broilers fed moldy corn, newly hatched Arbor Acres broilers were each randomly assigned to one of four groups, which were fed a basal diet (CON), a contaminated diet (10% moldy corn) (MC), a basal diet supplemented with 0.01% glucose oxidase (GOD), or a contaminated diet supplemented with 0.01% glucose oxidase (MCG).

Results

We found that the average weight gain (ADG) of the MC group was significantly lower than those of the CON and GOD groups, and there were no significant differences in ADG between the MCG group and the CON and GOD groups. Intestinal morphology results revealed irregularly arranged villi and microvilli in the ilea from the MC group, whereas those from the other three groups were aligned regularly. Tight-junction protein analysis showed that both ZO-1 expression and claudin-4 expression in the MC group were significantly lower than those in the other groups. Inflammation cytokines analysis showed lower serum concentration of interleukin-10, as well as its mRNA expression in the ileum of the MC group, when compared with those of the other groups. Additionally, we observed lower glutathione peroxidase and total superoxide dismutase activity and higher malonaldehyde concentration in the MC group than those in the MCG group. The α and β diversity of microbiota profiling indicated that the cecal microbiota in the MC group differed from those in the other three groups.

Conclusion

The results indicated that glucose oxidase supplementation was able to prevent the adverse effects from mycotoxin exposure on growth performance, antioxidant activity, inflammatory response, intestinal function, and microbiota composition in broilers. We suggested that glucose oxidase supplementation can be used in broilers to mitigate the adverse effects of moldy feed, and its benefits are due to its effect on intestinal microbiota composition.

Lung Metabolomics Profiling of Congenital Diaphragmatic Hernia in Fetal Rats

Congenital diaphragmatic hernia (CDH) is characterized by the herniation of abdominal contents into the thoracic cavity during the fetal period. This competition for fetal thoracic space results in lung hypoplasia and vascular maldevelopment that can generate severe pulmonary hypertension (PH). The detailed mechanisms of CDH pathogenesis are yet to be understood. Acknowledgment of the lung metabolism during the in-utero CDH development can help to discern the CDH pathophysiology changes. Timed-pregnant dams received nitrofen or vehicle (olive oil) on E9.5 day of gestation. All fetal lungs exposed to nitrofen or vehicle control were harvested at day E21.5 by C-section and processed for metabolomics analysis using nuclear magnetic resonance (NMR) spectroscopy. The three groups analyzed were nitrofen-CDH (NCDH), nitrofen-control (NC), and vehicle control (VC). A total of 64 metabolites were quantified and subjected to statistical analysis. The multivariate analysis identified forty-four metabolites that were statistically different between the three groups. The highest Variable importance in projection (VIP) score (>2) metabolites were lactate, glutamate, and adenosine 5'-triphosphate (ATP). Fetal CDH lungs have changes related to oxidative stress, nucleotide synthesis, amino acid metabolism, glycerophospholipid metabolism, and glucose metabolism. This work provides new insights into the molecular mechanisms behind the CDH pathophysiology and can explore potential novel treatment targets for CDH patients.