Three-minute method for amino acid analysis by UHPLC and high-resolution quadrupole orbitrap mass spectrometry

Patient-derived pancreatic tumor bacteria exhibit oncogenic properties and are recognized by MAIT cells in tumor spheroids

Introduction

Tumor-residing microbiota poses a new challenge in cancer progression and therapy; however, the functional behavior of patient tumor-derived microbes remains poorly understood. We previously reported the presence of tumor microbiota in intraductal papillary mucinous neoplasms (IPMNs), which are precursors of pancreatic cancer.

Methods

We examined the metabolic and pathogenic potential of clinical microbiota strains obtained from IPMN tumors using various pancreatic cell lines and 3D spheroid models.

Results

Our findings revealed that several strains from IPMNs with invasive cancer or high-grade dysplasia, such as E. cloacae, E. faecalis, and K. pneumoniae, induced a cancer metabolite signature in human pancreatic cells when infected ex vivo. Bacterial invasiveness was significantly correlated with DNA damage in spheroids derived from normal and tumor-derived pancreatic cells, particularly in strains derived from advanced neoplasia IPMN and under hypoxic conditions. Additionally, microbial metabolites activate human mucosal-associated invariant T (MAIT) cells and restrict the infection, both extra- and intracellularly, in hypoxic tumor conditions and in synergy with antibiotics.

Discussion

Immune sensing of tumor microbiota metabolites may have clinical implications in cancer management.

Macrophages recycle phagocytosed bacteria to fuel immunometabolic responses

Macrophages specialize in phagocytosis, a cellular process that eliminates extracellular matter, including microorganisms, through internalization and degradation1,2. Despite the critical role of phagocytosis during bacterial infection, the fate of phagocytosed microbial cargo and its impact on the host cell are poorly understood. In this study, we show that ingested bacteria constitute an alternative nutrient source that skews immunometabolic host responses. By tracing stable isotope-labelled bacteria, we found that phagolysosomal degradation of bacteria provides carbon atoms and amino acids that are recycled into various metabolic pathways, including glutathione and itaconate biosynthesis, and satisfies the bioenergetic needs of macrophages. Metabolic recycling of microbially derived nutrients is regulated by the nutrient-sensing mechanistic target of rapamycin complex C1 and is intricately tied to microbial viability. Dead bacteria, as opposed to live bacteria, are enriched in cyclic adenosine monophosphate, sustain the cellular adenosine monophosphate pool and subsequently activate adenosine monophosphate protein kinase to inhibit the mechanistic target of rapamycin complex C1. Consequently, killed bacteria strongly fuel metabolic recycling and support macrophage survival but elicit decreased reactive oxygen species production and reduced interleukin-1β secretion compared to viable bacteria. These results provide a new insight into the fate of engulfed microorganisms and highlight a microbial viability-associated metabolite that triggers host metabolic and immune responses. Our findings hold promise for shaping immunometabolic intervention for various immune-related pathologies.

Copper Drives Remodeling of Metabolic State and Progression of Clear Cell Renal Cell Carcinoma

SIGNIFICANCE

The work establishes a requirement for glucose-dependent coordination between energy production and redox homeostasis, which is fundamental for the survival of cancer cells that accumulate Cu and contributes to tumor growth.

Glutamine metabolism is systemically different between primary and induced pluripotent stem cell-derived brain microvascular endothelial cells

Human primary (hpBMEC) and induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial-like cells (hiBMEC) are interchangeably used in blood-brain barrier models to study neurological diseases and drug delivery. Both hpBMEC and hiBMEC use glutamine as a source of carbon and nitrogen to produce metabolites and build proteins essential to cell function and communication. We used metabolomic, transcriptomic, and computational methods to examine how hpBMEC and hiBMEC metabolize glutamine, which may impact their utility in modeling the blood-brain barrier. We found that glutamine metabolism was systemically different between the two cell types. hpBMEC had a higher metabolic rate and produced more glutamate and GABA, while hiBMEC rerouted glutamine to produce more glutathione, fatty acids, and asparagine. Higher glutathione production in hiBMEC correlated with higher oxidative stress compared to hpBMEC. α-ketoglutarate (α-KG) supplementation increased glutamate secretion from hiBMEC to match that of hpBMEC; however, α-KG also decreased hiBMEC glycolytic rate. These fundamental metabolic differences between BMEC types may impact in vitro blood-brain barrier model function, particularly communication between BMEC and surrounding cells, and emphasize the importance of evaluating the metabolic impacts of iPSC-derived cells in disease models.

Instationary metabolic flux analysis reveals that NPC1 inhibition increases glycolysis and decreases mitochondrial metabolism in brain microvascular endothelial cells

Niemann Pick Disease Type C (NP-C), a rare neurogenetic disease with no known cure, is caused by mutations in the cholesterol trafficking protein NPC1. Brain microvascular endothelial cells (BMEC) are thought to play a critical role in the pathogenesis of several neurodegenerative diseases; however, little is known about how these cells are altered in NP-C. In this study, we investigated how NPC1 inhibition perturbs BMEC metabolism in human induced pluripotent stem cell-derived BMEC (hiBMEC). We incorporated extracellular metabolite and isotope labeling data into an instationary metabolic flux analysis (INST-MFA) model to estimate intracellular metabolic fluxes. We found that NPC1 inhibition significantly increased glycolysis and pentose phosphate pathway flux while decreasing mitochondrial metabolism. These changes may have been driven by gene expression changes due to increased cholesterol biosynthesis, in addition to mitochondrial cholesterol accumulation. We corroborated these findings in primary BMEC, an alternative in vitro human brain endothelial model. Finally, we found that co-treatment with hydroxypropyl-β cyclodextrin (HPβCD) partially restored metabolic phenotype in U18666A-treated BMECs, suggesting that this drug may have therapeutic effects on the brain endothelium in NP-C. Together, our data highlight the importance of NPC1 in BMEC metabolism and implicate brain endothelial dysfunction in NP-C pathogenesis.

Impacts of APOE-ε4 and exercise training on brain microvascular endothelial cell barrier function and metabolism

BACKGROUND

The APOE-ε4 genotype is the highest genetic risk factor for Alzheimer's disease (AD), and exercise training can reduce the risk of AD. Two early pathologies of AD are degradation of tight junctions between brain microvascular endothelial cells (BMEC) and brain glucose hypometabolism. Therefore, the objective of this work was to determine how the APOE-ε4 genotype and serum from exercise trained individuals impacts BMEC barrier function and metabolism.

METHODS

iPSC homozygous for the APOE-ε3 and APOE-ε4 alleles were differentiated to BMEC-like cells and used to measure barrier function and metabolism. To investigate exercise effects, serum was collected from older adults pre- and post- 6 months of exercise training (n = 9 participants per genotype). APOE-ε3 and APOE-ε4 BMEC were treated with genotype-matched serum, and then barrier function and metabolism were measured.

FINDINGS

APOE-ε4 genotype impaired BMEC barrier function and metabolism by reducing sirtuin 1 (SIRT1) levels by 27% (p = 0.0188) and baseline insulin signalling by 37% (p = 0.0186) compared to APOE-ε3 BMEC. Exercise-trained serum increased SIRT1 by 33% (p = 0.0043) in APOE-ε3 BMEC but decreased SIRT1 by 22% (p = 0.0004) in APOE ε4 BMEC.

INTERPRETATION

APOE-ε4 directly impairs glucose metabolism and barrier function. Serum from exercise trained individuals alters SIRT1 in a genotype-dependent manner but may require additional cues from exercise to decrease AD pathologies.

FUNDING

Brain and Behaviour Initiative at the University of Maryland through the Seed Grant Program, NSF-GRFP DGE 1840340, Fischell Fellowship in Biomedical Engineering, NSF CBET-2211966 and DGE-1632976, National Niemann-Pick Disease Foundation, University of Maryland ASPIRE Program, NIH R01HL165193, R01HL140239-01, and R01AG057552.

Regulation of volume-regulated anion channels alters sensitivity to platinum chemotherapy

Cisplatin-based chemotherapy is used across many common tumor types, but resistance reduces the likelihood of long-term survival. We previously found the puromycin-sensitive aminopeptidase, NPEPPS, as a druggable driver of cisplatin resistance in vitro and in vivo and in patient-derived organoids. Here, we present a general mechanism where NPEPPS interacts with the volume-regulated anion channels (VRACs) to control cisplatin import into cells and thus regulate cisplatin response across a range of cancer types. We also find the NPEPPS/VRAC gene expression ratio is a predictive measure of cisplatin response in multiple cancer cohorts, showing the broad applicability of this mechanism. Our work describes a specific mechanism of cisplatin resistance, which, given the characteristics of NPEPPS as a drug target, has the potential to improve cancer patient outcomes. In addition, we describe an intracellular mechanism regulating VRAC activity, which is critical for volume regulation in normal cells - a finding with functional implications beyond cancer.

Treatment of minimal residual disease in myeloid malignancies after allo-HSCT with venetoclax-based regimens in patients ineligible for or failed in the immunotherapy

BACKGROUND

Relapse was the major cause of treatment failure in patients with myeloid malignancies after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Patients who still suffer from the disease while cannot be detected by morphological analysis can be identified by the minimal residual disease (MRD) monitoring. The most used first-line regimens for MRD are immunotherapies. However, for patients who were ineligible for or failed in first-line immunotherapies, options were limited.

METHODS

A total of 20 patients with myeloid malignancies with recurrent MRD after allo-HSCT were included in this study. The safety and efficacy of venetoclax-based regimens were analyzed.

RESULTS

There were 13 patients (65%) treated with venetoclax combined with hypomethylating agents concomitantly and seven patients (35%) treated with venetoclax monotherapy. After venetoclax-based regimens, MRD was eliminated in 11 patients (55%) with 6 subsequently developing recurrent MRD and 5 remaining in molecular remission. MRD declined in two patients (10%), and no responses in seven patients (35%). Among the two patients with declined MRD, one patient finally eliminated MRD after two cycles of the venetoclax-based regimen, and the other patient's MRD further declined after the second regimen. The objective response rate (ORR) was 65%. The median duration of response was 103 (12-313) days. The incidences of grades 3-4 neutropenia, anemia, and thrombocytopenia independently of pretreatment status were 30%, 20% and 20%, respectively.

CONCLUSION

Venetoclax-based regimens are efficient and safe for MRD in patients with myeloid malignancies ineligible for or failed in the first-line immunotherapies after allo-HSCT.

Early adipose tissue wasting in a novel preclinical model of human lung cancer cachexia

Cancer cachexia (CC), a syndrome of skeletal muscle and adipose tissue wasting, reduces responsiveness to therapies and increases mortality. There are no approved treatments for CC, which may relate to discordance between pre-clinical models and human CC. To address the need for clinically relevant models, we generated tamoxifen-inducible, epithelial cell specific Kras G12D/+ ( G12D ) mice. G12D mice develop CC over a protracted time course and phenocopy tissue, cellular, mutational, transcriptomic, and metabolic characteristics of human lung CC. CC in G12D mice is characterized by early loss of adipose tissue, a phenotype confirmed in a large cohort of patients with lung cancer. Tumor-released factors promote adipocyte lipolysis, a driver of adipose wasting in human CC, and adipose tissue wasting was inversely related to tumor burden. Thus, G12D mice model key features of human lung CC and suggest a novel role for early adipose tissue wasting in CC.

A distinct metabolic and epigenetic state drives trained immunity in HSC-derived macrophages from autoimmune mice

Here, we investigate the contribution of long-term hematopoietic stem cells (HSCsLT) to trained immunity (TI) in the setting of chronic autoimmune disease. Using a mouse model of systemic lupus erythematosus (SLE), we show that bone marrow-derived macrophages (BMDMs) from autoimmune mice exhibit hallmark features of TI, including increased Mycobacterium avium killing and inflammatory cytokine production, which are mechanistically linked to increased glycolytic metabolism. We show that HSCs from autoimmune mice constitute a transplantable, long-term reservoir for macrophages that exhibit the functional properties of TI. However, these BMDMs exhibit reduced glycolytic activity and chromatin accessibility at metabolic genes while retaining elevated expression of TI-associated transcriptional regulators. Hence, HSC exposed to autoimmune inflammation can give rise to macrophages in which the functional and metabolic properties of TI are decoupled. Our data support a model in which TI is characterized by a spectrum of molecular and metabolic states driving augmented immune function.

METABOLIC AND BIOENERGETIC ALTERATIONS ARE ASSOCIATED WITH INFECTION SUSCEPTIBILITY IN SURVIVORS OF SEVERE TRAUMA: AN EXPLORATORY STUDY

ABSTRACT

Background : Trauma and blood loss are frequently associated with organ failure, immune dysfunction, and a high risk of secondary bacterial lung infections. We aim to test if plasma metabolomic flux and monocyte bioenergetics are altered in association with trauma and related secondary infections. Methods : Plasma samples were collected from trauma patients at three time points: days 0, 3, and 7 postadmission. Metabolites (140) were measured in plasma from trauma survivors ( n = 24) and healthy control individuals (HC, n = 10). Further analysis within the trauma cohort included subsets of trauma/infection-negative (TIneg, n = 12) and trauma/infection-positive patients (TIpos, n = 12). The bioenergetic profile in monocytes was determined using mitochondrial and glycolytic stress tests. Results : In the trauma cohort, significant alterations were observed in 29 metabolites directly affecting 11 major metabolic pathways, while 34 metabolite alterations affected 8 pathways in 9, versus TIneg patients. The most altered metabolic pathways included protein synthesis, the urea cycle/arginine metabolism, phenylalanine, tyrosine, tryptophan biosynthesis, and carnitine compound family. In monocytes from trauma patients, reduced mitochondrial indices and loss of glycolytic plasticity were consistent with an altered profile of plasma metabolites in the tricarboxylic acid cycle and glycolysis. Conclusions : Our study highlights that the metabolic profile is significantly and persistently affected by trauma and related infections. Among trauma survivors, metabolic alterations in plasma were associated with reduced monocyte bioenergetics. These exploratory findings establish a groundwork for future clinical studies aimed at enhancing our understanding of the interplay between metabolic/bioenergetic alterations associated with trauma and secondary bacterial infections.

Blocking Tryptophan Catabolism Reduces Triple-Negative Breast Cancer Invasive Capacity

SIGNIFICANCE

TDO2 is more highly expressed than the nonhomologous TRP-catabolizing enzyme IDO1 in TNBC. We find that TDO2 knockdown can lead to a compensatory increase in IDO1. Therefore, we tested a newly developed TDO2/IDO1 dual inhibitor and found that it decreases TRP catabolism, anchorage-independent survival, and invasive capacity.

An Expedited Qualitative Profiling of Free Amino Acids in Plant Tissues Using Liquid Chromatography-Mass Spectrometry (LC-MS) in Conjunction With MS-DIAL

The estimation of relative levels of amino acids is crucial for understanding various biological processes in plants, including photosynthesis, stress tolerance, and the uptake and translocation of nutrients. A wide range of liquid chromatography (LC; HPLC/UHPLC)-based methods is available for measuring the quantity of amino acids in plants. Additionally, the coupling of LC with mass spectrometry (MS) significantly enhanced the robustness of existing chromatographic methods used for amino acid quantification. However, accurate annotation and integration of mass peaks can be challenging for plant biologists with limited experience in analyzing MS data, especially in studies involving large datasets with multiple treatments and/or replicates. Further, there are instances when the experiment demands an overall view of the amino acids profile rather than focusing on absolute quantification. The present protocol provides a detailed LC-MS method for obtaining a qualitative amino acids profile using MS-DIAL, a versatile and user-friendly program for processing MS data. Free amino acids were extracted from the leaves of control and Tomato leaf curl Palampur virus (ToLCPalV)-infected Nicotiana benthamiana plants. Extracted amino acids were derivatized and separated using UHPLC-QTOF, with each amino acid subsequently identified by aligning mass data with a custom text library created in MS-DIAL. Further, MS-DIAL was employed for internal standard-based normalization to obtain a qualitative profile of 15 amino acids in control and virus-infected plants. The outlined method aims to simplify the processing of MS data to quickly assess any modulation in amino acid levels in plants with a higher degree of confidence.

Maternal Docosahexaenoic Acid Supplementation Alters Maternal and Fetal Docosahexaenoic Acid Status and Placenta Phospholipids in Pregnancies Complicated by High Body Mass Index

INTRODUCTION

An optimal fetal supply of docosahexaenoic acid (DHA) is critical for normal brain development. The relationship between maternal DHA intake and DHA delivery to the fetus is complex and is dependent on placental handling of DHA. Little data exist on placental DHA levels in pregnancies supplemented with the recommended dose of 200 mg/d. Our objective was to determine how prenatal DHA at the recommended 200 mg/d impacts maternal, placental, and fetal DHA status in both normal-weight and high-BMI women compared to women taking no supplements.

METHODS

Maternal blood, placenta, and cord blood were collected from 30 healthy pregnant women (BMI 18.9-43.26 kg/m2) giving birth at term. Red blood cells (RBCs) and villous tissue were isolated, and lipids were extracted to determine DHA content by LC-MS/MS. Data were analyzed by supplement group (0 vs. 200 mg/d) and maternal BMI (normal weight or high BMI) using two-way ANOVA. We measured maternal choline levels in maternal and cord plasma samples.

RESULTS

Supplementation with 200 mg/d DHA significantly increased (p < 0.05) maternal and cord RBC DHA content only in pregnancies complicated by high BMI. We did not find any impact of choline levels on maternal or cord RBC phospholipids. There were no significant differences in total placental DHA content by supplementation or maternal BMI (p > 0.05). Placental levels of phosphatidylinositol (PI) and phosphatidic acid containing DHA species were higher (p < 0.05) in high-BMI women without DHA supplementation compared to both normal-BMI and high-BMI women taking DHA supplements.

CONCLUSION

Maternal DHA supplementation at recommended doses cord increased RBC DHA content only in pregnancies complicated by higher BMI. Surprisingly, we found that obesity was related to an increase in placental PI and phosphatidic acid species, which was ameliorated by DHA supplementation. Phosphatidic acid activates placental mTOR, which regulates amino acid transport and may explain previous findings of the impact of DHA on placental function. Current recommendations for DHA supplementation may not be achieving the goal of improving fetal DHA levels in normal-weight women.

3,3-Dimethyl-1-Butanol and its Metabolite 3,3-Dimethylbutyrate Ameliorate Collagen-induced Arthritis Independent of Choline Trimethylamine Lyase Activity

Conflicting data exist in rheumatoid arthritis and the collagen-induced arthritis (CIA) murine model of autoimmune arthritis regarding the role of bacterial carnitine and choline metabolism into the inflammatory product trimethylamine (TMA), which is oxidized in the liver to trimethylamine-N-oxide (TMAO). Using two published inhibitors of bacterial TMA lyase, 3,3-dimethyl-1-butanol (DMB) and fluoromethylcholine (FMC), we tested if TMA/TMAO were relevant to inflammation in the development of CIA. Surprisingly, DMB-treated mice demonstrated > 50% reduction in arthritis severity compared to FMC and vehicle-treated mice, but amelioration of disease was independent of TMA/TMAO production. Given the apparent contradiction that DMB did not inhibit TMA, we then investigated the mechanism of protection by DMB. After verifying that DMB acted independently of the intestinal microbiome, we traced the metabolism of DMB within the host and identified a novel host-derived metabolite of DMB, 3,3-dimethyl-1-butyric acid (DMBut). In vivo studies of mice treated with DMB or DMBut demonstrated efficacy of both molecules in significantly reducing disease and proinflammatory cytokines in CIA, while in vitro studies suggest these molecules may act by modulating secretion of proinflammatory cytokines from macrophages. Altogether, our study suggests that DMB and/or its metabolites are protective in CIA through direct immunomodulatory effects rather than inhibition of bacterial TMA lyases.

Mitochondrial complex I activity in microglia sustains neuroinflammation

Sustained smouldering, or low-grade activation, of myeloid cells is a common hallmark of several chronic neurological diseases, including multiple sclerosis1. Distinct metabolic and mitochondrial features guide the activation and the diverse functional states of myeloid cells2. However, how these metabolic features act to perpetuate inflammation of the central nervous system is unclear. Here, using a multiomics approach, we identify a molecular signature that sustains the activation of microglia through mitochondrial complex I activity driving reverse electron transport and the production of reactive oxygen species. Mechanistically, blocking complex I in pro-inflammatory microglia protects the central nervous system against neurotoxic damage and improves functional outcomes in an animal disease model in vivo. Complex I activity in microglia is a potential therapeutic target to foster neuroprotection in chronic inflammatory disorders of the central nervous system3.

PTPN2 Regulates Metabolic Flux to Affect β-Cell Susceptibility to Inflammatory Stress

Protein tyrosine phosphatase N2 (PTPN2) is a type 1 diabetes (T1D) candidate gene identified from human genome-wide association studies. PTPN2 is highly expressed in human and murine islets and becomes elevated upon inflammation and models of T1D, suggesting that PTPN2 may be important for β-cell survival in the context of T1D. To test whether PTPN2 contributed to β-cell dysfunction in an inflammatory environment, we generated a β-cell-specific deletion of Ptpn2 in mice (PTPN2-β knockout [βKO]). Whereas unstressed animals exhibited normal metabolic profiles, low- and high-dose streptozotocin-treated PTPN2-βKO mice displayed hyperglycemia and accelerated death, respectively. Furthermore, cytokine-treated Ptpn2-KO islets resulted in impaired glucose-stimulated insulin secretion, mitochondrial defects, and reduced glucose-induced metabolic flux, suggesting β-cells lacking Ptpn2 are more susceptible to inflammatory stress associated with T1D due to maladaptive metabolic fitness. Consistent with the phenotype, proteomic analysis identified an important metabolic enzyme, ATP-citrate lyase, as a novel PTPN2 substrate.

ARTICLE HIGHLIGHTS

ACOD1 deficiency offers protection in a mouse model of diet-induced obesity by maintaining a healthy gut microbiota

Aconitate decarboxylase 1 (ACOD1) is the enzyme synthesizing itaconate, an immuno-regulatory metabolite tuning host-pathogen interactions. Such functions are achieved by affecting metabolic pathways regulating inflammation and microbe survival. However, at the whole-body level, metabolic roles of itaconate remain largely unresolved. By using multiomics-integrated approaches, here we show that ACOD1 responds to high-fat diet consumption in mice by promoting gut microbiota alterations supporting metabolic disease. Genetic disruption of itaconate biosynthesis protects mice against obesity, alterations in glucose homeostasis and liver metabolic dysfunctions by decreasing meta-inflammatory responses to dietary lipid overload. Mechanistically, fecal metagenomics and microbiota transplantation experiments demonstrate such effects are dependent on an amelioration of the intestinal ecosystem composition, skewed by high-fat diet feeding towards obesogenic phenotype. In particular, unbiased fecal microbiota profiling and axenic culture experiments point towards a primary role for itaconate in inhibiting growth of Bacteroidaceae and Bacteroides, family and genus of Bacteroidetes phylum, the major gut microbial taxon associated with metabolic health. Specularly to the effects imposed by Acod1 deficiency on fecal microbiota, oral itaconate consumption enhances diet-induced gut dysbiosis and associated obesogenic responses in mice. Unveiling an unrecognized role of itaconate, either endogenously produced or exogenously administered, in supporting microbiota alterations underlying diet-induced obesity in mice, our study points ACOD1 as a target against inflammatory consequences of overnutrition.

Copper drives remodeling of metabolic state and progression of clear cell renal cell carcinoma

Copper (Cu) is an essential trace element required for mitochondrial respiration. Late-stage clear cell renal cell carcinoma (ccRCC) accumulates Cu and allocates it to mitochondrial cytochrome c oxidase. We show that Cu drives coordinated metabolic remodeling of bioenergy, biosynthesis and redox homeostasis, promoting tumor growth and progression of ccRCC. Specifically, Cu induces TCA cycle-dependent oxidation of glucose and its utilization for glutathione biosynthesis to protect against H 2 O 2 generated during mitochondrial respiration, therefore coordinating bioenergy production with redox protection. scRNA-seq determined that ccRCC progression involves increased expression of subunits of respiratory complexes, genes in glutathione and Cu metabolism, and NRF2 targets, alongside a decrease in HIF activity, a hallmark of ccRCC. Spatial transcriptomics identified that proliferating cancer cells are embedded in clusters of cells with oxidative metabolism supporting effects of metabolic states on ccRCC progression. Our work establishes novel vulnerabilities with potential for therapeutic interventions in ccRCC. Accumulation of copper is associated with progression and relapse of ccRCC and drives tumor growth.Cu accumulation and allocation to cytochrome c oxidase (CuCOX) remodels metabolism coupling energy production and nucleotide biosynthesis with maintenance of redox homeostasis.Cu induces oxidative phosphorylation via alterations in the mitochondrial proteome and lipidome necessary for the formation of the respiratory supercomplexes. Cu stimulates glutathione biosynthesis and glutathione derived specifically from glucose is necessary for survival of Cu Hi cells. Biosynthesis of glucose-derived glutathione requires activity of glutamyl pyruvate transaminase 2, entry of glucose-derived pyruvate to mitochondria via alanine, and the glutamate exporter, SLC25A22. Glutathione derived from glucose maintains redox homeostasis in Cu-treated cells, reducing Cu-H 2 O 2 Fenton-like reaction mediated cell death. Progression of human ccRCC is associated with gene expression signature characterized by induction of ETC/OxPhos/GSH/Cu-related genes and decrease in HIF/glycolytic genes in subpopulations of cancer cells. Enhanced, concordant expression of genes related to ETC/OxPhos, GSH, and Cu characterizes metabolically active subpopulations of ccRCC cells in regions adjacent to proliferative subpopulations of ccRCC cells, implicating oxidative metabolism in supporting tumor growth.

Light-Driven Metabolic Pathways in Non-Photosynthetic Biohybrid Bacteria

Biomanufacturing via microorganisms relies on carbon substrates for molecular feedstocks and a source of energy to carry out enzymatic reactions. This creates metabolic bottlenecks and lowers the efficiency for substrate conversion. Nanoparticle biohybridization with proteins and whole cell surfaces can bypass the need for redox cofactor regeneration for improved secondary metabolite production in a non-specific manner. Here we propose using nanobiohybrid organisms (Nanorgs), intracellular protein-nanoparticle hybrids formed through the spontaneous coupling of core-shell quantum dots (QDs) with histidine-tagged enzymes in non-photosynthetic bacteria, for light-mediated control of bacterial metabolism. This proved to eliminate metabolic constrictions and replace glucose with light as the source of energy in Escherichia coli, with an increase in growth by 1.7-fold in 75 % reduced nutrient media. Metabolomic tracking through carbon isotope labeling confirmed flux shunting through targeted pathways, with accumulation of metabolites downstream of respective targets. Finally, application of Nanorgs with the Ehrlich pathway improved isobutanol titers/yield by 3.9-fold in 75 % less sugar from E. coli strains with no genetic alterations. These results demonstrate the promise of Nanorgs for metabolic engineering and low-cost biomanufacturing.

Mitochondrial reverse electron transport in myeloid cells perpetuates neuroinflammation

Sustained smouldering, or low grade, activation of myeloid cells is a common hallmark of several chronic neurological diseases, including multiple sclerosis (MS) 1 . Distinct metabolic and mitochondrial features guide the activation and the diverse functional states of myeloid cells 2 . However, how these metabolic features act to perpetuate neuroinflammation is currently unknown. Using a multiomics approach, we identified a new molecular signature that perpetuates the activation of myeloid cells through mitochondrial complex II (CII) and I (CI) activity driving reverse electron transport (RET) and the production of reactive oxygen species (ROS). Blocking RET in pro-inflammatory myeloid cells protected the central nervous system (CNS) against neurotoxic damage and improved functional outcomes in animal disease models in vivo . Our data show that RET in myeloid cells is a potential new therapeutic target to foster neuroprotection in smouldering inflammatory CNS disorders 3 .

Glutaredoxin attenuates glutathione levels via deglutathionylation of Otub1 and subsequent destabilization of system xC. SCIENCE ADVANCES 2023;9:eadi5192. [PMID: 37703360 PMCID: PMC10499329 DOI: 10.1126/sciadv.adi5192]

Glutathione (GSH) is a critical component of the cellular redox system that combats oxidative stress. The glutamate-cystine antiporter, system xC-, is a key player in GSH synthesis that allows for the uptake of cystine, the rate-limiting building block of GSH. It is unclear whether GSH or GSH-dependent protein oxidation [protein S-glutathionylation (PSSG)] regulates the activity of system xC-. We demonstrate that an environment of enhanced PSSG promotes GSH increases via a system xC--dependent mechanism. Absence of the deglutathionylase, glutaredoxin (GLRX), augmented SLC7A11 protein and led to significant increases of GSH content. S-glutathionylation of C23 or C204 of the deubiquitinase OTUB1 promoted interaction with the E2-conjugating enzyme UBCH5A, leading to diminished ubiquitination and proteasomal degradation of SLC7A11 and augmentation of GSH, effects that were reversed by GLRX. These findings demonstrate an intricate link between GLRX and GSH via S-glutathionylation of OTUB1 and system xC- and illuminate a previously unknown feed-forward regulatory mechanism whereby enhanced GSH protein oxidation augments cellular GSH.

3,3-dimethyl-1-butanol and its metabolite 3,3-dimethylbutyrate ameliorate collagen-induced arthritis independent of choline trimethylamine lyase activity

Previous studies have identified significant alterations in intestinal carnitine metabolism in mice with collagen-induced arthritis (CIA), potentially linking bacterial dysbiosis with autoimmunity. Bacterial trimethylamine (TMA) lyases metabolize dietary carnitine to TMA, which is oxidized in the liver to trimethylamine-N-oxide (TMAO). TMAO is associated with inflammatory diseases, such as atherosclerosis, whose immunologic processes mirror that of rheumatoid arthritis (RA). Therefore, we investigated the possibility of ameliorating CIA by inhibiting TMA lyase activity using 3,3-dimethyl-1-butanol (DMB) or fluoromethylcholine (FMC). During CIA, mice were treated with 1% vol/vol DMB, 100mg/kg FMC, or vehicle. DMB-treated mice demonstrated significant (>50%) reduction in arthritis severity compared to FMC and vehicle-treated mice. However, in contrast to FMC, DMB treatment did not reduce cecal TMA nor circulating TMAO concentrations. Using gas chromatography, we confirmed the effect of DMB is independent of TMA lyase inhibition. Further, we identified a novel host-derived metabolite of DMB, 3,3-dimethyl-1-butyric acid (DMBut), which also significantly reduced disease and proinflammatory cytokines in CIA mice. Altogether, our study suggests that DMB the immunomodulatory activity of DMB and/or its metabolites are protective in CIA. Elucidating its target and mechanism of action may provide new directions for RA therapeutic development.

Sugarcane ash and sugarcane ash-derived silica nanoparticles alter cellular metabolism in human proximal tubular kidney cells

Multiple epidemics of chronic kidney disease of an unknown etiology (CKDu) have emerged in agricultural communities around the world. Many factors have been posited as potential contributors, but a primary cause has yet to be identified and the disease is considered likely multifactorial. Sugarcane workers are largely impacted by disease leading to the hypothesis that exposure to sugarcane ash produced during the burning and harvest of sugarcane could contribute to CKDu. Estimated exposure levels of particles under 10 μm (PM10) have been found to be exceptionally high during this process, exceeding 100 μg/m3 during sugarcane cutting and averaging ∼1800 μg/m3 during pre-harvest burns. Sugarcane stalks consist of ∼80% amorphous silica and generate nano-sized silica particles (∼200 nm) following burning. A human proximal convoluted tubule (PCT) cell line was subjected to treatments ranging in concentration from 0.025 μg/mL to 25 μg/mL of sugarcane ash, desilicated sugarcane ash, sugarcane ash-derived silica nanoparticles (SAD SiNPs) or manufactured pristine 200 nm silica nanoparticles. The combination of heat stress and sugarcane ash exposure on PCT cell responses was also assessed. Following 6-48 h of exposure, mitochondrial activity and viability were found to be significantly reduced when exposed to SAD SiNPs at concentrations 2.5 μg/mL or higher. Oxygen consumption rate (OCR) and pH changes suggested significant alteration to cellular metabolism across treatments as early as 6 h following exposure. SAD SiNPs were found to inhibit mitochondrial function, reduce ATP generation, increase reliance on glycolysis, and reduce glycolytic reserve. Metabolomic analysis revealed several cellular energetics pathways (e.g., fatty acid metabolism, glycolysis, and TCA cycle) are significantly altered across ash-based treatments. Heat stress did not influence these responses. Such changes indicate that exposure to sugarcane ash and its derivatives can promote mitochondrial dysfunction and disrupt metabolic activity of human PCT cells.

Deoxysphingolipids: Atypical Skeletal Muscle Lipids Related to Insulin Resistance in Humans That Decrease Insulin Sensitivity In Vitro

Sphingolipids are thought to promote skeletal muscle insulin resistance. Deoxysphingolipids (dSLs) are atypical sphingolipids that are increased in the plasma of individuals with type 2 diabetes and cause β-cell dysfunction in vitro. However, their role in human skeletal muscle is unknown. We found that dSL species are significantly elevated in muscle of individuals with obesity and type 2 diabetes compared with athletes and lean individuals and are inversely related to insulin sensitivity. Furthermore, we observed a significant reduction in muscle dSL content in individuals with obesity who completed a combined weight loss and exercise intervention. Increased dSL content in primary human myotubes caused a decrease in insulin sensitivity associated with increased inflammation, decreased AMPK phosphorylation, and altered insulin signaling. Our findings reveal a central role for dSL in human muscle insulin resistance and suggest dSLs as therapeutic targets for the treatment and prevention of type 2 diabetes.

ARTICLE HIGHLIGHTS

Deoxysphingolipids (dSLs) are atypical sphingolipids elevated in the plasma of individuals with type 2 diabetes, and their role in muscle insulin resistance has not been investigated. We evaluated dSL in vivo in skeletal muscle from cross-sectional and longitudinal insulin-sensitizing intervention studies and in vitro in myotubes manipulated to synthesize higher dSLs. dSLs were increased in the muscle of people with insulin resistance, inversely correlated to insulin sensitivity, and significantly decreased after an insulin-sensitizing intervention; increased intracellular dSL concentrations cause myotubes to become more insulin resistant. Reduction of muscle dSL levels is a potential novel therapeutic target to prevent/treat skeletal muscle insulin resistance.

Elicitor-induced plant immunity relies on amino acids accumulation to delay the onset of bacterial virulence

Plant immunity relies on the perception of microbe-associated molecular patterns (MAMPs) from invading microbes to induce defense responses that suppress attempted infections. It has been proposed that MAMP-triggered immunity (MTI) suppresses bacterial infections by suppressing the onset of bacterial virulence. However, the mechanisms by which plants exert this action are poorly understood. Here, we showed that MAMP perception in Arabidopsis (Arabidopsis thaliana) induces the accumulation of free amino acids in a salicylic acid (SA)-dependent manner. When co-infiltrated with Glutamine and Serine, two of the MAMP-induced highly accumulating amino acids, Pseudomonas syringae pv. tomato DC3000 expressed low levels of virulence genes and failed to produce robust infections in otherwise susceptible plants. When applied exogenously, Glutamine and Serine directly suppressed bacterial virulence and growth, bypassing MAMP perception and SA signaling. In addition, an increased level of endogenous Glutamine in the leaf apoplast of a gain-of-function mutant of Glutamine Dumper-1 rescued the partially compromised bacterial virulence- and growth-suppressing phenotype of the SA-induced deficient-2 (sid2) mutant. Our data suggest that MTI suppresses bacterial infections by delaying the onset of virulence with an excess of amino acids at the early stages of infection.

Therapy-Resistant Acute Myeloid Leukemia Stem Cells Are Resensitized to Venetoclax + Azacitidine by Targeting Fatty Acid Desaturases 1 and 2

Recent advances in targeting leukemic stem cells (LSCs) using venetoclax with azacitidine (ven + aza) has significantly improved outcomes for de novo acute myeloid leukemia (AML) patients. However, patients who relapse after traditional chemotherapy are often venetoclax-resistant and exhibit poor clinical outcomes. We previously described that fatty acid metabolism drives oxidative phosphorylation (OXPHOS) and acts as a mechanism of LSC survival in relapsed/refractory AML. Here, we report that chemotherapy-relapsed primary AML displays aberrant fatty acid and lipid metabolism, as well as increased fatty acid desaturation through the activity of fatty acid desaturases 1 and 2, and that fatty acid desaturases function as a mechanism of recycling NAD+ to drive relapsed LSC survival. When combined with ven + aza, the genetic and pharmacologic inhibition of fatty acid desaturation results in decreased primary AML viability in relapsed AML. This study includes the largest lipidomic profile of LSC-enriched primary AML patient cells to date and indicates that inhibition of fatty acid desaturation is a promising therapeutic target for relapsed AML.

The Arabidopsis LHT1 Amino Acid Transporter Contributes to Pseudomonas simiae-Mediated Plant Growth Promotion by Modulating Bacterial Metabolism in the Rhizosphere

The root microbiome structure ensures optimal plant host health and fitness, and it is, at least in part, defined by the plant genotype. It is well documented that root-secreted amino acids promote microbial chemotaxis and growth in the rhizosphere. However, whether the plant-mediated re-uptake of amino acids contributes to maintaining optimal levels of amino acids in the root exudates, and, in turn, microbial growth and metabolism, remains to be established. Here, we show that Lysine-Histidine Transporter-1 (LHT1), an amino acid inward transporter expressed in Arabidopsis thaliana roots, limits the growth of the plant-growth-promoting bacteria Pseudomonas simiae WCS417r (Ps WCS417r). The amino acid profiling of the lht1 mutant root exudates showed increased levels of glutamine, among other amino acids. Interestingly, lht1 exudates or Gln-supplemented wild-type exudates enhance Ps WCS417r growth. However, despite promoting bacterial growth and robust root colonization, lht1 exudates and Gln-supplemented wild-type exudates inhibited plant growth in a Ps WCS417r-dependent manner. The transcriptional analysis of defense and growth marker genes revealed that plant growth inhibition was not linked to the elicitation of plant defense but likely to the impact of Ps WCS417r amino acids metabolism on auxin signaling. These data suggest that an excess of amino acids in the rhizosphere impacts Ps WCS417r metabolism, which, in turn, inhibits plant growth. Together, these results show that LHT1 regulates the amino-acid-mediated interaction between plants and Ps WCS417r and suggest a complex relationship between root-exuded amino acids, root colonization by beneficial bacteria, bacterial metabolism, and plant growth promotion.

A hydroalcoholic extract of Senecio nutans SCh. Bip (Asteraceae); its effects on cardiac function and chemical characterization

ETHNOPHARMACOLOGY RELEVANCE

The plant Senecio nutans SCh. Bip. is used by Andean communities to treat altitude sickness. Recent evidence suggests it may produce vasodilation and negative cardiac inotropy, though the cellular mechanisms have not been elucidated.

PURPOSE

To determinate the mechanisms action of S. nutans on cardiovascular function in normotensive animals.

METHODS

The effect of the extract on rat blood pressure was measured with a transducer in the carotid artery and intraventricular pressure by a Langendorff system. The effects on sheep ventricular intracellular calcium handling and contractility were evaluated using photometry. Ultra-high-performance liquid-chromatography with diode array detection coupled with heated electrospray-ionization quadrupole-orbitrap mass spectrometric detection (UHPLC-DAD-ESI-Q-OT-MSn) was used for extract chemical characterization.

RESULTS

In normotensive rats, S. nutans (10 mg/kg) reduced mean arterial pressure (MAP) by 40% (p < 0.05), causing a dose-dependent coronary artery dilation and decreased left ventricular pressure. In isolated cells, S. nutans extract (1 μg/ml) rapidly reduced the [Ca²⁺]_i transient amplitude and sarcomere shorting by 40 and 49% (p < 0.001), respectively. The amplitude of the caffeine evoked [Ca²⁺]_i transient was reduced by 24% (p < 0.001), indicating reduced sarcoplasmic reticulum (SR) Ca²⁺ content. Sodium-calcium exchanger (NCX) activity increased by 17% (p < 0.05), while sarcoendoplasmic reticulum Ca²⁺-ATPase (SERCA) activity was decreased by 21% (p < 0.05). LC-MS results showed the presence of vitamin C, malic acid, and several antioxidant phenolic acids reported for the first time. Dihydroeuparin and 4-hydroxy-3-(3-methylbut-2-enyl) acetophenone were abundant in the extract.

CONCLUSION

In normotensive animals, S. nutans partially reduces MAP by decreasing heart rate and cardiac contractility. This negative inotropy is accounted for by decreased SERCA activity and increased NCX activity which reduces SR Ca²⁺ content. These results highlight the plant's potential as a source of novel cardio-active phytopharmaceuticals or nutraceuticals.

Plasma levels of carboxylic acids are markers of early kidney dysfunction in young people with type 1 diabetes

BACKGROUND

We compared plasma metabolites of amino acid oxidation and the tricarboxylic acid (TCA) cycle in youth with and without type 1 diabetes mellitus (T1DM) and related the metabolites to glomerular filtration rate (GFR), renal plasma flow (RPF), and albuminuria. Metabolites associated with impaired kidney function may warrant future study as potential biomarkers or even future interventions to improve kidney bioenergetics.

METHODS

Metabolomic profiling of fasting plasma samples using a targeted panel of 644 metabolites and an untargeted panel of 19,777 metabolites was performed in 50 youth with T1DM ≤ 10 years and 20 controls. GFR and RPF were ascertained by iohexol and p-aminohippurate clearance, and albuminuria calculated as urine albumin to creatinine ratio. Sparse partial least squares discriminant analysis and moderated t tests were used to identify metabolites associated with GFR and RPF.

RESULTS

Adolescents with and without T1DM were similar in age (16.1 ± 3.0 vs. 16.1 ± 2.9 years) and BMI (23.4 ± 5.1 vs. 22.7 ± 3.7 kg/m2), but those with T1DM had higher GFR (189 ± 40 vs. 136 ± 22 ml/min) and RPF (820 ± 125 vs. 615 ± 65 ml/min). Metabolites of amino acid oxidation and the TCA cycle were significantly lower in adolescents with T1DM vs. controls, and the measured metabolites were able to discriminate diabetes status with an AUC of 0.82 (95% CI: 0.71, 0.93) and error rate of 0.21. Lower glycine (r:-0.33, q = 0.01), histidine (r:-0.45, q < 0.001), methionine (r: -0.29, q = 0.02), phenylalanine (r: -0.29, q = 0.01), serine (r: -0.42, q < 0.001), threonine (r: -0.28, q = 0.02), citrate (r: -0.35, q = 0.003), fumarate (r: -0.24, q = 0.04), and malate (r: -0.29, q = 0.02) correlated with higher GFR. Lower glycine (r: -0.28, q = 0.04), phenylalanine (r:-0.3, q = 0.03), fumarate (r: -0.29, q = 0.04), and malate (r: -0.5, q < 0.001) correlated with higher RPF. Lower histidine (r: -0.28, q = 0.02) was correlated with higher mean ACR.

CONCLUSIONS

In conclusion, adolescents with relatively short T1DM duration exhibited lower plasma levels of carboxylic acids that associated with hyperfiltration and hyperperfusion.

TRIAL REGISTRATION

ClinicalTrials.gov NCT03618420 and NCT03584217 A higher resolution version of the Graphical abstract is available as Supplementary information.

Induced pluripotent stem cell-derived cells model brain microvascular endothelial cell glucose metabolism

Glucose transport from the blood into the brain is tightly regulated by brain microvascular endothelial cells (BMEC), which also use glucose as their primary energy source. To study how BMEC glucose transport contributes to cerebral glucose hypometabolism in diseases such as Alzheimer's disease, it is essential to understand how these cells metabolize glucose. Human primary BMEC (hpBMEC) can be used for BMEC metabolism studies; however, they have poor barrier function and may not recapitulate in vivo BMEC function. iPSC-derived BMEC-like cells (hiBMEC) are readily available and have good barrier function but may have an underlying epithelial signature. In this study, we examined differences between hpBMEC and hiBMEC glucose metabolism using a combination of dynamic metabolic measurements, metabolic mass spectrometry, RNA sequencing, and Western blots. hiBMEC had decreased glycolytic flux relative to hpBMEC, and the overall metabolomes and metabolic enzyme levels were different between the two cell types. However, hpBMEC and hiBMEC had similar glucose metabolism, including nearly identical glucose labeled fractions of glycolytic and TCA cycle metabolites. Treatment with astrocyte conditioned media and high glucose increased glycolysis in both hpBMEC and hiBMEC, though hpBMEC decreased glycolysis in response to fluvastatin while hiBMEC did not. Together, these results suggest that hiBMEC can be used to model cerebral vascular glucose metabolism, which expands their use beyond barrier models.

Rapid and Nondestructive Detection of Proline in Serum Using Near-Infrared Spectroscopy and Partial Least Squares

Proline is an important amino acid that widely affects life activities. It plays an important role in the occurrence and development of diseases. It is of great significance to monitor the metabolism of the machine. With the great advantages of deep learning in feature extraction, near-infrared analysis technology has great potential and has been widely used in various fields. This study explored the potential application of near-infrared spectroscopy in the detection of serum proline. We collected blood samples from clinical sources, separated the serum, established a quantitative model, and determined the changes in proline. Four algorithms of SMLR, PLS, iPLS, and SA were used to model proline in serum. The root mean square errors of prediction were 0.00111, 0.00150, 0.000770, and 0.000449, and the correlation coefficients (Rp) were 0.84, 0.67, 0.91, and 0.97, respectively. The experimental results show that the model is relatively robust and has certain guiding significance for the clinical monitoring of proline. This method is expected to replace the current mainstream but time-consuming HPLC, or it can be applied to rapid online monitoring at the bedside.

Mechanisms and significance of tissue-specific MICU regulation of the mitochondrial calcium uniporter complex

Mitochondrial Ca2+ uptake, mediated by the mitochondrial Ca2+ uniporter, regulates oxidative phosphorylation, apoptosis, and intracellular Ca2+ signaling. Previous studies suggest that non-neuronal uniporters are exclusively regulated by a MICU1-MICU2 heterodimer. Here, we show that skeletal-muscle and kidney uniporters also complex with a MICU1-MICU1 homodimer and that human/mouse cardiac uniporters are largely devoid of MICUs. Cells employ protein-importation machineries to fine-tune the relative abundance of MICU1 homo- and heterodimers and utilize a conserved MICU intersubunit disulfide to protect properly assembled dimers from proteolysis by YME1L1. Using the MICU1 homodimer or removing MICU1 allows mitochondria to more readily take up Ca2+ so that cells can produce more ATP in response to intracellular Ca2+ transients. However, the trade-off is elevated ROS, impaired basal metabolism, and higher susceptibility to death. These results provide mechanistic insights into how tissues can manipulate mitochondrial Ca2+ uptake properties to support their unique physiological functions.

Metabolomic Evaluation of N-Acetyl-p-Benzoquinone Imine Protein Adduct Formation with Therapeutic Acetaminophen Administration: Sex-based Physiologic Differences

BACKGROUND

Acetaminophen (APAP)-associated transaminase elevation, induced by N-acetyl-p-benzoquinone imine (NAPQI) protein adduction, remains an area of research interest. Distinct from known genetic, physiologic, and dosage associations dictating severity of hepatic injury, no known factors predict an absence of protein adduct formation at therapeutic APAP dosing.

HYPOTHESIS

Sex-based physiology is predictive of APAP-induced protein adduct formation and differential metabolite expression at therapeutic doses.

METHODS

This retrospective study interrogated serum samples collected for a prior study investigating fluctuations of alanine aminotransferase (ALT) over time with 4G daily APAP dosing for ≥ 16 days in subjects from Denver, Colorado. Subjects were grouped by adduct formation (n = 184) vs no adducts (n = 20). Samples were run on ultra-high-performance liquid chromatography mass spectrometry from study days 0, 7, 16, and 31. Significant metabolite expressions were identified using t-tests with false discovery rate correction (FDR), partial least squares discriminant, and ANOVA simultaneous comparison analyses. Demographic and clinical data were explored using t-tests with FDR (age, weight, BMI, ALT) and Chi-square (sex, ethnicity, race) analyses.

RESULTS

In pre-treatment samples, relative quantitation caprylic acid was expressed ninefold higher and 6-carboxyhexanoate was expressed threefold lower in subjects who did not develop adducts. Lactate had greater expression in the no adducts group (p = 0.001). Using absolute quantitation, glutathione was expressed 2.6-fold greater among no adduct subjects. Odds of males developing NAPQI protein adducts at therapeutic APAP dosing were 5.91 times lower than females (95% CI = 2.3-14.9; p = 0.0001).

CONCLUSION

Multiple metabolites were differentially expressed based on adduct group and sex. Metabolites were identified unique to adduct development independent of sex. At therapeutic APAP dosing, males were less likely to develop APAP protein adducts. Further research into lipid biosynthesis and metabolism may provide further insight into physiology associated with adduct production.

Effect of the variation in the extracellular concentration of l-arginine in the physiology of Leishmania (Viannia) braziliensis and its susceptibility to some antileishmanial drugs

The knowledge about amino acid metabolism in trypanosomatids is a valuable source of new therapeutic targets. l-arginine is an essential amino acid for Leishmania parasites, and it participates in the synthesis of polyamines, a group of essential nutrients used for nucleic acids, proteins biosynthesis, and redox modulation necessary for proliferation. In the present study, we evaluated the effect of changes in the availability of this amino acid on promastigotes and intracellular amastigotes on U937 macrophages and showed that the absence of l-arginine in culture medium negatively influences the growth and infectivity of Leishmania (Viannia) braziliensis, causing a decrease in the percentage of the infected cells and parasite load tested through light microscopy. In addition, the absence of l-arginine resulted in the parasite's inability to regulate its reactive oxygen species (ROS) production, which persisted for up to 24 h by flow cytometry following the probe H2DCF-DA dye. Moreover, the differentiation of promastigote to amastigote in axenic culture was more significant at low concentrations of l-arginine suggesting that this depletion induces a stress environment to increase this transformation under axenic conditions. No association was established between the availability of l-arginine and the effectiveness of antileishmanial drugs. All these results confirm the importance of l-arginine in L. braziliensis life cycle vital processes, such as its replication and infectivity, as documented in other Leishmania species. Based on these results, we proposed that the l-arginine uptake/metabolism route is possible in exploring new antileishmanial drugs.

Mitochondrial uncoupling protein-2 reprograms metabolism to induce oxidative stress and myofibroblast senescence in age-associated lung fibrosis

Mitochondrial dysfunction has been associated with age-related diseases, including idiopathic pulmonary fibrosis (IPF). We provide evidence that implicates chronic elevation of the mitochondrial anion carrier protein, uncoupling protein-2 (UCP2), in increased generation of reactive oxygen species, altered redox state and cellular bioenergetics, impaired fatty acid oxidation, and induction of myofibroblast senescence. This pro-oxidant senescence reprogramming occurs in concert with conventional actions of UCP2 as an uncoupler of oxidative phosphorylation with dissipation of the mitochondrial membrane potential. UCP2 is highly expressed in human IPF lung myofibroblasts and in aged fibroblasts. In an aging murine model of lung fibrosis, the in vivo silencing of UCP2 induces fibrosis regression. These studies indicate a pro-fibrotic function of UCP2 in chronic lung disease and support its therapeutic targeting in age-related diseases associated with impaired tissue regeneration and organ fibrosis.

Inspiratory muscle strength training for lowering blood pressure and improving endothelial function in postmenopausal women: comparison with “standard of care” aerobic exercise

Background: High blood pressure (BP), particularly systolic BP (SBP), is the major modifiable risk factor for cardiovascular diseases and related disorders of aging. SBP increases markedly with aging in women such that the prevalence of above-normal SBP (i.e., ≥120 mmHg) in postmenopausal women exceeds rates in age-matched men. This increase in SBP is associated with vascular endothelial dysfunction, mediated by excessive reactive oxygen species-induced oxidative stress and consequent reductions in nitric oxide bioavailability. Moderate-intensity aerobic exercise is a recommended lifestyle strategy for reducing SBP. However, adherence to aerobic exercise guidelines among postmenopausal women is low (<30%) and aerobic exercise does not consistently enhance endothelial function in estrogen-deficient postmenopausal women. High-resistance inspiratory muscle strength training (IMST) is a time-efficient, adherable lifestyle intervention that involves inhaling against resistance through a handheld device (30 breaths/day). Here, we present the protocol for a randomized controlled trial investigating the efficacy of 3 months of high-resistance IMST compared to guideline-based, “standard-of-care” aerobic exercise training for decreasing SBP and improving endothelial function in estrogen-deficient postmenopausal women with above-normal SBP (120–159 mmHg) at baseline (ClinicalTrials.gov Identifier: NCT05000515).

Methods: A randomized, single-blind, parallel-group design clinical trial will be conducted in 72 (36/group) estrogen-deficient postmenopausal women with above-normal SBP. Participants will complete baseline testing and then be randomized to either 3 months of high-resistance IMST (30 breaths/day, 6 days/week, 75% maximal inspiratory pressure) or moderate-intensity aerobic exercise training (brisk walking 25 min/day, 6 days/week, 40–60% heart rate reserve). Outcome measures will be assessed after 3 months of either intervention. Following end-intervention testing, participants will abstain from their assigned intervention for 6 weeks, after which BP and endothelial function will be assessed to evaluate the potential persistent effects of the intervention on the primary and secondary outcomes.

Discussion: This study is designed to compare the effectiveness of time-efficient, high-resistance IMST to guideline-based aerobic exercise training for lowering SBP and improving endothelial function, and interrogating potential mechanisms of action, in estrogen-deficient postmenopausal women.

Clinical Trial Registration:ClinicalTrials.gov, Identifier: NCT05000515.

Plasma microRNA and metabolic changes associated with pediatric acute respiratory distress syndrome: a prospective cohort study

Acute respiratory distress syndrome is a heterogeneous pathophysiological process responsible for significant morbidity and mortality in pediatric intensive care patients. Diagnosis is defined by clinical characteristics that identify the syndrome after development. Subphenotyping patients at risk of progression to ARDS could provide the opportunity for therapeutic intervention. microRNAs, non-coding RNAs stable in circulation, are a promising biomarker candidate. We conducted a single-center prospective cohort study to evaluate random forest classification of microarray-quantified circulating microRNAs in critically ill pediatric patients. We additionally selected a sub-cohort for parallel metabolomics profiling as a pilot study for concurrent use of miRNAs and metabolites as circulating biomarkers. In 35 patients (n = 21 acute respiratory distress, n = 14 control) 15 microRNAs were differentially expressed. Unsupervised random forest classification accurately grouped ARDS and control patients with an area under the curve of 0.762, which was improved to 0.839 when subset to only patients with bacterial infection. Nine metabolites were differentially abundant between acute respiratory distress and control patients (n = 4, both groups) and abundance was highly correlated with miRNA expression. Random forest classification of microRNAs differentiated critically ill pediatric patients who developed acute respiratory distress relative to those who do not. The differential expression of microRNAs and metabolites provides a strong foundation for further work to validate their use as a prognostic biomarker.

MAMP-elicited changes in amino acid transport activity contribute to restricting bacterial growth

Plants live under the constant challenge of microbes that probe the environment in search of potential hosts. Plant cells perceive microbe-associated molecular patterns (MAMPs) from incoming microbes and activate defense responses that suppress attempted infections. Despite the substantial progress made in understanding MAMP-triggered signaling pathways, the downstream mechanisms that suppress bacterial growth and disease remain poorly understood. Here, we uncover how MAMP perception in Arabidopsis (Arabidopsis thaliana) elicits dynamic changes in extracellular concentrations of free L-amino acids (AA). Within the first 3 h of MAMP perception, a fast and transient inhibition of AA uptake produces a transient increase in extracellular AA concentrations. Within 4 and 12 h of MAMP perception, a sustained enhanced uptake activity decreases the extracellular concentrations of AA. Gene expression analysis showed that salicylic acid-mediated signaling contributes to inducing the expression of AA/H+ symporters responsible for the MAMP-induced enhanced uptake. A screening of loss-of-function mutants identified the AA/H+ symporter lysin/histidine transporter-1 as an important contributor to MAMP-induced enhanced uptake of AA. Infection assays in lht1-1 seedlings revealed that high concentrations of extracellular AA promote bacterial growth in the absence of induced defense elicitation but contribute to suppressing bacterial growth upon MAMP perception. Overall, the data presented in this study reveal a mechanistic connection between MAMP-induced plant defense and suppression of bacterial growth through the modulation of AA transport activity.

Adenosine Awakens Metabolism to Enhance Growth-Independent Killing of Tolerant and Persister Bacteria across Multiple Classes of Antibiotics

Metabolic and growth arrest are primary drivers of antibiotic tolerance and persistence in clinically diverse bacterial pathogens. We recently showed that adenosine (ADO) suppresses bacterial growth under nutrient-limiting conditions. In the current study, we show that despite the growth-suppressive effect of ADO, extracellular ADO enhances antibiotic killing in both Gram-negative and Gram-positive bacteria by up to 5 orders of magnitude. The ADO-potentiated antibiotic activity is dependent on purine salvage and is paralleled with a suppression of guanosine tetraphosphate synthesis and the massive accumulation of ATP and GTP. These changes in nucleoside phosphates coincide with transient increases in rRNA transcription and proton motive force. The potentiation of antibiotic killing by ADO is manifested against bacteria grown under both aerobic and anaerobic conditions, and it is exhibited even in the absence of alternative electron acceptors such as nitrate. ADO potentiates antibiotic killing by generating proton motive force and can occur independently of an ATP synthase. Bacteria treated with an uncoupler of oxidative phosphorylation and NADH dehydrogenase-deficient bacteria are refractory to the ADO-potentiated killing, suggesting that the metabolic awakening induced by this nucleoside is intrinsically dependent on an energized membrane. In conclusion, ADO represents a novel example of metabolite-driven but growth-independent means to reverse antibiotic tolerance. Our investigations identify the purine salvage pathway as a potential target for the development of therapeutics that may improve infection clearance while reducing the emergence of antibiotic resistance. IMPORTANCE Antibiotic tolerance, which is a hallmark of persister bacteria, contributes to treatment-refractory infections and the emergence of heritable antimicrobial resistance. Drugs that reverse tolerance and persistence may become part of the arsenal to combat antimicrobial resistance. Here, we demonstrate that salvage of extracellular ADO reduces antibiotic tolerance in nutritionally stressed Escherichia coli, Salmonella enterica, and Staphylococcus aureus. ADO potentiates bacterial killing under aerobic and anaerobic conditions and takes place in bacteria lacking the ATP synthase. However, the sensitization to antibiotic killing elicited by ADO requires an intact NADH dehydrogenase, suggesting a requirement for an energized electron transport chain. ADO antagonizes antibiotic tolerance by activating ATP and GTP synthesis, promoting proton motive force and cellular respiration while simultaneously suppressing the stringent response. These investigations reveal an unprecedented role for purine salvage stimulation as a countermeasure of antibiotic tolerance and the emergence of antimicrobial resistance.

The STAT3-MYC axis promotes survival of leukemia stem cells by regulating SLC1A5 and oxidative phosphorylation

Acute myeloid leukemia (AML) is characterized by the presence of leukemia stem cells (LSCs), and failure to fully eradicate this population contributes to disease persistence/relapse. Prior studies have characterized metabolic vulnerabilities of LSCs, which demonstrate preferential reliance on oxidative phosphorylation (OXPHOS) for energy metabolism and survival. In the present study, using both genetic and pharmacologic strategies in primary human AML specimens, we show that signal transducer and activator of transcription 3 (STAT3) mediates OXPHOS in LSCs. STAT3 regulates AML-specific expression of MYC, which in turn controls transcription of the neutral amino acid transporter gene SLC1A5. We show that genetic inhibition of MYC or SLC1A5 acts to phenocopy the impairment of OXPHOS observed with STAT3 inhibition, thereby establishing this axis as a regulatory mechanism linking STAT3 to energy metabolism. Inhibition of SLC1A5 reduces intracellular levels of glutamine, glutathione, and multiple tricarboxylic acid (TCA) cycle metabolites, leading to reduced TCA cycle activity and inhibition of OXPHOS. Based on these findings, we used a novel small molecule STAT3 inhibitor, which binds STAT3 and disrupts STAT3-DNA, to evaluate the biological role of STAT3. We show that STAT3 inhibition selectively leads to cell death in AML stem and progenitor cells derived from newly diagnosed patients and patients who have experienced relapse while sparing normal hematopoietic cells. Together, these findings establish a STAT3-mediated mechanism that controls energy metabolism and survival in primitive AML cells.

Polyamine import and accumulation causes immunomodulation in macrophages engulfing apoptotic cells

Phagocytosis of apoptotic cells, termed efferocytosis, is critical for tissue homeostasis and drives anti-inflammatory programming in engulfing macrophages. Here, we assess metabolites in naive and inflammatory macrophages following engulfment of multiple cellular and non-cellular targets. Efferocytosis leads to increases in the arginine-derived polyamines, spermidine and spermine, in vitro and in vivo. Surprisingly, polyamine accumulation after efferocytosis does not arise from retention of apoptotic cell metabolites or de novo synthesis but from enhanced polyamine import that is dependent on Rac1, actin, and PI3 kinase. Blocking polyamine import prevents efferocytosis from suppressing macrophage interleukin (IL)-1β or IL-6. This identifies efferocytosis as a trigger for polyamine import and accumulation, and imported polyamines as mediators of efferocytosis-induced immune reprogramming.

Corynebacterium Species Inhibit Streptococcus pneumoniae Colonization and Infection of the Mouse Airway

The stability and composition of the airway microbiome is an important determinant of respiratory health. Some airway bacteria are considered to be beneficial due to their potential to impede the acquisition and persistence of opportunistic bacterial pathogens such as Streptococcus pneumoniae. Among such organisms, the presence of Corynebacterium species correlates with reduced S. pneumoniae in both adults and children, in whom Corynebacterium abundance is predictive of S. pneumoniae infection risk. Previously, Corynebacterium accolens was shown to express a lipase which cleaves host lipids, resulting in the production of fatty acids that inhibit growth of S. pneumoniae in vitro. However, it was unclear whether this mechanism contributes to Corynebacterium-S. pneumoniae interactions in vivo. To address this question, we developed a mouse model for Corynebacterium colonization in which colonization with either C. accolens or another species, Corynebacterium amycolatum, significantly reduced S. pneumoniae acquisition in the upper airway and infection in the lung. Moreover, the lungs of co-infected mice had reduced pro-inflammatory cytokines and inflammatory myeloid cells, indicating resolution of infection-associated inflammation. The inhibitory effect of C. accolens on S. pneumoniae in vivo was mediated by lipase-dependent and independent effects, indicating that both this and other bacterial factors contribute to Corynebacterium-mediated protection in the airway. We also identified a previously uncharacterized bacterial lipase in C. amycolatum that is required for inhibition of S. pneumoniae growth in vitro. Together, these findings demonstrate the protective potential of airway Corynebacterium species and establish a new model for investigating the impact of commensal microbiota, such as Corynebacterium, on maintaining respiratory health.

Determination of cell volume as part of metabolomics experiments

Cells regulate their cell volume, but cell volumes may change in response to metabolic and other perturbations. Many metabolomics experiments use cultured cells to measure changes in metabolites in response to physiological and other experimental perturbations, but the metabolomics workflow by mass spectrometry only determines total metabolite amounts in cell culture extracts. To convert metabolite amount to metabolite concentration requires knowledge of the number and volume of the cells. Measuring only metabolite amount can lead to incorrect or skewed results in cell culture experiments because cell size may change due to experimental conditions independent of change in metabolite concentration. We have developed a novel method to determine cell volume in cell culture experiments using a pair of stable isotopically labeled phenylalanine internal standards incorporated within the normal liquid chromatography-tandem mass spectrometry (LC-MS/MS) metabolomics workflow. This method relies on the flooding-dose technique where the intracellular concentration of a particular compound (in this case phenylalanine) is forced to equal its extracellular concentration. We illustrate the LC-MS/MS technique for two different mammalian cell lines. Although the method is applicable in general for determining cell volume, the major advantage of the method is its seamless incorporation within the normal metabolomics workflow.

NF-κB Regulation of LRH-1 and ABCG5/8 Potentiates Phytosterol Role in the Pathogenesis of Parenteral Nutrition-Associated Cholestasis

BACKGROUND AND AIMS

Chronically administered parenteral nutrition (PN) in patients with intestinal failure carries the risk for developing PN-associated cholestasis (PNAC). We have demonstrated that farnesoid X receptor (FXR) and liver X receptor (LXR), proinflammatory interleukin-1 beta (IL-1β), and infused phytosterols are important in murine PNAC pathogenesis. In this study we examined the role of nuclear receptor liver receptor homolog 1 (LRH-1) and phytosterols in PNAC.

APPROACH AND RESULTS

In a C57BL/6 PNAC mouse model (dextran sulfate sodium [DSS] pretreatment followed by 14 days of PN; DSS-PN), hepatic nuclear receptor subfamily 5, group A, member 2/LRH-1 mRNA, LRH-1 protein expression, and binding of LRH-1 at the Abcg5/8 and Cyp7a1 promoter was reduced. Interleukin-1 receptor-deficient mice (Il-1r^-/- /DSS-PN) were protected from PNAC and had significantly increased hepatic mRNA and protein expression of LRH-1. NF-κB activation and binding to the LRH-1 promoter were increased in DSS-PN PNAC mice and normalized in Il-1r^-/- /DSS-PN mice. Knockdown of NF-κB in IL-1β-exposed HepG2 cells increased expression of LRH-1 and ABCG5. Treatment of HepG2 cells and primary mouse hepatocytes with an LRH-1 inverse agonist, ML179, significantly reduced mRNA expression of FXR targets ATP binding cassette subfamily C member 2/multidrug resistance associated protein 2 (ABCC2/MRP2), nuclear receptor subfamily 0, groupB, member 2/small heterodimer partner (NR0B2/SHP), and ATP binding cassette subfamily B member 11/bile salt export pump (ABCB11/BSEP). Co-incubation with phytosterols further reduced expression of these genes. Similar results were obtained by suppressing the LRH-1 targets ABCG5/8 by treatment with small interfering RNA, IL-1β, or LXR antagonist GSK2033. Liquid chromatography-mass spectrometry and chromatin immunoprecipitation experiments in HepG2 cells showed that ATP binding cassette subfamily G member 5/8 (ABCG5/8) suppression by GSK2033 increased the accumulation of phytosterols and reduced binding of FXR to the SHP promoter. Finally, treatment with LRH-1 agonist, dilauroyl phosphatidylcholine (DLPC) protected DSS-PN mice from PNAC.

CONCLUSIONS

This study suggests that NF-κB regulation of LRH-1 and downstream genes may affect phytosterol-mediated antagonism of FXR signaling in the pathogenesis of PNAC. LRH-1 could be a potential therapeutic target for PNAC.

Targeting Host Glycolysis as a Strategy for Antimalarial Development

Glycolysis controls cellular energy, redox balance, and biosynthesis. Antiglycolytic therapies are under investigation for treatment of obesity, cancer, aging, autoimmunity, and microbial diseases. Interrupting glycolysis is highly valued as a therapeutic strategy, because glycolytic disruption is generally tolerated in mammals. Unfortunately, anemia is a known dose-limiting side effect of these inhibitors and presents a major caveat to development of antiglycolytic therapies. We developed specific inhibitors of enolase – a critical enzyme in glycolysis – and validated their metabolic and cellular effects on human erythrocytes. Enolase inhibition increases erythrocyte susceptibility to oxidative damage and induces rapid and premature erythrocyte senescence, rather than direct hemolysis. We apply our model of red cell toxicity to address questions regarding erythrocyte glycolytic disruption in the context of Plasmodium falciparum malaria pathogenesis. Our study provides a framework for understanding red blood cell homeostasis under normal and disease states and clarifies the importance of erythrocyte reductive capacity in malaria parasite growth.

Venetoclax plus azacitidine and donor lymphocyte infusion in treating acute myeloid leukemia patients who relapse after allogeneic hematopoietic stem cell transplantation

This study aimed to evaluate the efficacy and safety of venetoclax plus azacitidine and donor lymphocyte infusion (DLI) in treating patients with relapsed acute myeloid leukemia (AML) after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Twenty-six AML patients who relapsed after allo-HSCT were enrolled and treated with venetoclax plus azacitidine and DLI. Complete remission with incomplete recovery (CRi), partial remission (PR), and objective remission rate (ORR) were assessed, and then event-free survival (EFS) and overall survival (OS) were evaluated. Besides, adverse events were documented. Additionally, whole exome sequencing was performed in bone marrow samples. The CRi, PR, and ORR rates were 26.9%, 34.6%, and 61.5%, respectively. The median time of EFS and OS was 120 (95% CI: 71–610) days and 284.5 (95% CI: 81–610) days, respectively. The most common adverse events were hematologic system adverse events including agranulocytosis, anemia, and thrombocytopenia, while the adverse events of other systems were relatively less and milder. In addition, no serious adverse events existed. Of note, there were 6 (23.1%) patients who developed GVHD. As for gene mutation, 49 mutated genes were found, which were categorized as first-, second-, and third-class mutations, and then further analysis revealed that the first-class mutations were not correlated with EFS or OS. Additionally, the most frequent mutated genes were FLT3, CEBPA, DNMT3A, KIT, KRAS, and NRAS. Venetoclax plus azacitidine and DLI is efficient and tolerant in treating patients with relapsed AML after allo-HSCT, implying this combined therapy as a potential treatment option in the studied patients.

Mass spectrometry based high-throughput bioanalysis of low molecular weight compounds: are we ready to support personalized medicine?

Liquid chromatography coupled to mass spectrometry (LC-MS) is the gold standard in bioanalysis for the development of quantitative assays to support drug development or therapeutic drug monitoring. High-throughput and low-cost gene sequencing have enabled a paradigm shift from one treatment fits all to personalized medicine (PM). However, gene monitoring provides only partial information about the health state. The full picture requires the combination of gene monitoring with the screening of exogenous compounds, metabolites, lipids, and proteins. This critical review discusses how mass spectrometry–based technologies and approaches including separation sciences, ambient ionization, and ion mobility are/could be used to support high-throughput bioanalysis of endogenous end exogenous low molecular weight compounds. It includes also various biological sample types (from blood to expired air), and various sample preparation techniques.