bims-imicid 2023-06-25 papers

bims-imicid

Biomed News

on Immunometabolism of infection, cancer and immune-mediated disease

Issue of 2023–06–25
29 papers selected by
Dylan Ryan, University of Cambridge

Differential Effects of Glutamine Inhibition Strategies on Antitumor CD8 T Cells.
13 C metabolite tracing reveals glutamine and acetate as critical in vivo fuels for CD8 + T cells.
Dimethyl itaconate induces long-term innate immune responses and confers protection against infection.
Interleukin-21 Drives a Hypermetabolic State and CD4 + T Cell-associated Pathogenicity in Chronic Intestinal Inflammation.
A multimodal atlas of tumour metabolism reveals the architecture of gene-metabolite covariation.
UBE2M-mediated neddylation of TRIM21 regulates obesity-induced inflammation and metabolic disorders.
NK Cells from Human Cytomegalovirus-Seropositive Individuals Have a Distinct Metabolic Profile That Correlates with Elevated mTOR Signaling.
Butyrate Protects against Clostridium difficile Infection by Regulating Bile Acid Metabolism.
Microglial Metabolic Reprogramming: Emerging Insights and Therapeutic Strategies in Neurodegenerative Diseases.
Real-Time Measurement of the Mitochondrial Bioenergetic Profile of Neutrophils.
Metabolic reprogramming through mitochondrial biogenesis drives adenosine anti-inflammatory effects: new mechanism controlling gingival fibroblast hyper-inflammatory state.
Systemic immunometabolism and responses to vaccines: insights from T and B cell perspectives.
Metabolic reprogramming regulates microglial polarization and its role in cerebral ischemia reperfusion.
Iron Withdrawal with DIBI, a Novel 3-Hydroxypyridin-4-One Chelator Iron-Binding Polymer, Attenuates Macrophage Inflammatory Responses.
Human immunodeficiency virus and antiretroviral therapy-mediated immune cell metabolic dysregulation in children born to HIV-infected women: potential clinical implications.
Selective oxidative protection leads to tissue topological changes orchestrated by macrophage during ulcerative colitis.
Retinoic Acid Signaling Is Required for Dendritic Cell Maturation and the Induction of T Cell Immunity.
Short-Chain Fatty Acids Alleviate Vancomycin-Caused Humoral Immunity Attenuation in Rabies-Vaccinated Mice by Promoting the Generation of Plasma Cells via Akt-mTOR Pathway.
Cell metabolism-based optimization strategy of CAR-T cell function in cancer therapy.
CCL4 participates in the reprogramming of glucose metabolism induced by ALV-J infection in chicken macrophages.
Tryptophan depletion sensitizes the AHR pathway by increasing AHR expression and GCN2/LAT1-mediated kynurenine uptake, and potentiates induction of regulatory T lymphocytes.
HIF1α-dependent hypoxia response in myeloid cells requires IRE1α.
CES1 Releases Oxylipins from Oxidized Triacylglycerol (oxTAG) and Regulates Macrophage oxTAG/TAG Accumulation and PGE2/IL-1β Production.
STE20 kinase TAOK3 regulates type 2 immunity and metabolism in obesity.
Distinct roles of the preparatory and payoff phases of glycolysis in hematopoietic stem cells.
Leishmania donovani Induces Multiple Dynamic Responses in the Metabolome Associated with Amastigote Differentiation and Maturation Inside the Human Macrophage.
NAMPT inhibition relieves intestinal inflammation by regulating macrophage activation in experimental necrotizing enterocolitis.
Loss of Macrophage mTORC2 Drives Atherosclerosis via FoxO1 and IL-1β Signaling.
Exercise ameliorates chronic inflammatory response induced by high-fat diet via Sestrin2 in an Nrf2-dependent manner.

J Immunol. 2023 Jun 21. pii: ji2200715. [Epub ahead of print]

Differential Effects of Glutamine Inhibition Strategies on Antitumor CD8 T Cells.

Matthew Z Madden, Xiang Ye, Channing Chi, Emilie L Fisher, Melissa M Wolf, Gabriel A Needle, Jackie E Bader, Andrew R Patterson, Bradley I Reinfeld, Madelyn D Landis, Emma S Hathaway, Jason E Muka, Richard T O'Neil, John Karijolich, Mary Philip, Jeffrey C Rathmell.

Activated T cells undergo metabolic reprogramming to meet anabolic, differentiation, and functional demands. Glutamine supports many processes in activated T cells, and inhibition of glutamine metabolism alters T cell function in autoimmune disease and cancer. Multiple glutamine-targeting molecules are under investigation, yet the precise mechanisms of glutamine-dependent CD8 T cell differentiation remain unclear. We show that distinct strategies of glutamine inhibition by glutaminase-specific inhibition with small molecule CB-839, pan-glutamine inhibition with 6-diazo-5-oxo-l-norleucine (DON), or by glutamine-depleted conditions (No Q) produce distinct metabolic differentiation trajectories in murine CD8 T cells. T cell activation with CB-839 treatment had a milder effect than did DON or No Q treatment. A key difference was that CB-839-treated cells compensated with increased glycolytic metabolism, whereas DON and No Q-treated cells increased oxidative metabolism. However, all glutamine treatment strategies elevated CD8 T cell dependence on glucose metabolism, and No Q treatment caused adaptation toward reduced glutamine dependence. DON treatment reduced histone modifications and numbers of persisting cells in adoptive transfer studies, but those T cells that remained could expand normally upon secondary Ag encounter. In contrast, No Q-treated cells persisted well yet demonstrated decreased secondary expansion. Consistent with reduced persistence, CD8 T cells activated in the presence of DON had reduced ability to control tumor growth and reduced tumor infiltration in adoptive cell therapy. Overall, each approach to inhibit glutamine metabolism confers distinct effects on CD8 T cells and highlights that targeting the same pathway in different ways can elicit opposing metabolic and functional outcomes.

DOI: https://doi.org/10.4049/jimmunol.2200715
bioRxiv. 2023 Jun 11. pii: 2023.06.09.544407. [Epub ahead of print]

13 C metabolite tracing reveals glutamine and acetate as critical in vivo fuels for CD8 + T cells.

Eric H Ma, Michael S Dahabieh, Lisa M DeCamp, Irem Kaymak, Susan M Kitchen-Goosen, Dominic G Roy, Mark J Verway, Radia M Johnson, Bozena Samborska, Catherine A Scullion, Mya Steadman, Matthew Vos, Thomas P Roddy, Connie M Krawczyk, Kelsey S Williams, Ryan D Sheldon, Russell G Jones.

Infusion of 13C-labeled metabolites provides a gold-standard for understanding the metabolic processes used by T cells during immune responses in vivo . Through infusion of 13C-labeled metabolites (glucose, glutamine, acetate) in Listeria monocytogenes ( Lm )-infected mice, we demonstrate that CD8+ T effector (Teff) cells utilize metabolites for specific pathways during specific phases of activation. Highly proliferative early Teff cells in vivo shunt glucose primarily towards nucleotide synthesis and leverage glutamine anaplerosis in the tricarboxylic acid (TCA) cycle to support ATP and de novo pyrimidine synthesis. Additionally, early Teff cells rely on glutamic-oxaloacetic transaminase 1 (Got1)-which regulates de novo aspartate synthesis-for effector cell expansion in vivo . Importantly, Teff cells change fuel preference over the course of infection, switching from glutamine-to acetate-dependent TCA cycle metabolism late in infection. This study provides insights into the dynamics of Teff metabolism, illuminating distinct pathways of fuel consumption associated with Teff cell function in vivo .
Teaser: Interrogating dynamics of fuel utilization by CD8 + T cells in vivo reveals new metabolic checkpoints for immune function in vivo .

DOI: https://doi.org/10.1101/2023.06.09.544407
Cell Rep. 2023 Jun 16. pii: S2211-1247(23)00669-1. [Epub ahead of print]42(6): 112658

Dimethyl itaconate induces long-term innate immune responses and confers protection against infection.

Anaísa V Ferreira, Sarantos Kostidis, Laszlo A Groh, Valerie A C M Koeken, Mariolina Bruno, Ilayda Baydemir, Gizem Kilic, Özlem Bulut, Theano Andriopoulou, Victoria Spanou, Kalliopi D Synodinou, Theologia Gkavogianni, Simone J C F M Moorlag, L Charlotte de Bree, Vera P Mourits, Vasiliki Matzaraki, Werner J H Koopman, Frank L van de Veerdonk, Georgios Renieris, Martin Giera, Evangelos J Giamarellos-Bourboulis, Boris Novakovic, Jorge Domínguez-Andrés.

  Itaconate is an immunomodulatory metabolite produced by immune cells under microbial stimulation and certain pro-inflammatory conditions and triggers antioxidant and anti-inflammatory responses. We show that dimethyl itaconate, a derivative of itaconate previously linked to suppression of inflammation and widely employed as an alternative to the endogenous metabolite, can induce long-term transcriptional, epigenomic, and metabolic changes, characteristic of trained immunity. Dimethyl itaconate alters glycolytic and mitochondrial energetic metabolism, ultimately leading to increased responsiveness to microbial ligand stimulation. Subsequently, mice treated with dimethyl itaconate present increased survival to infection with Staphylococcus aureus. Additionally, itaconate levels in human plasma correlate with enhanced ex vivo pro-inflammatory cytokine production. Collectively, these findings demonstrate that dimethyl itaconate displays short-term anti-inflammatory characteristics and the capacity to induce long-term trained immunity. This pro-and anti-inflammatory dichotomy of dimethyl itaconate is likely to induce complex immune responses and should be contemplated when considering itaconate derivatives in a therapeutic context.

Keywords:  CP: Immunology; glutathione; infection; innate immunity; itaconate; metabolism; monocytes; trained immunity

DOI:  https://doi.org/10.1016/j.celrep.2023.112658
bioRxiv. 2023 Jun 06. pii: 2023.06.02.543518. [Epub ahead of print]

Interleukin-21 Drives a Hypermetabolic State and CD4 + T Cell-associated Pathogenicity in Chronic Intestinal Inflammation.

Adebowale O Bamidele, Shravan K Mishra, Petra Hirsova, Patrick J Fehrenbach, Lucia Valenzuela-Pérez, Hyun Se Kim Lee.

BACKGROUND & AIMS: Incapacitated regulatory T cells (Tregs) contribute to immune-mediated diseases. Inflammatory Tregs are evident during human inflammatory bowel disease (IBD); however, mechanisms driving the development of these cells and their function are not well understood. Therefore, we investigated the role of cellular metabolism in Tregs relevant to gut homeostasis.
METHODS: Using human Tregs, we performed mitochondrial ultrastructural studies via electron microscopy and confocal imaging, biochemical and protein analyses using proximity ligation assay, immunoblotting, mass cytometry and fluorescence-activated cell sorting, metabolomics, gene expression analysis, and real-time metabolic profiling utilizing Seahorse XF analyzer. We utilized Crohn's disease single-cell RNA sequencing dataset to infer therapeutic relevance of targeting metabolic pathways in inflammatory Tregs. We examined the superior functionality of genetically-modified Tregs in CD4 + T cell-induced murine colitis models.
RESULTS: Mitochondria-endoplasmic reticulum (ER) appositions, known to mediate pyruvate entry into mitochondria via VDAC1, are abundant in Tregs. VDAC1 inhibition perturbed pyruvate metabolism, eliciting sensitization to other inflammatory signals reversible by membrane-permeable methyl pyruvate (MePyr) supplementation. Notably, IL-21 diminished mitochondria-ER appositions, resulting in enhanced enzymatic function of glycogen synthase kinase 3 β (GSK3β), a putative negative regulator of VDAC1, and a hypermetabolic state that amplified Treg inflammatory response. MePyr and GSK3β pharmacologic inhibitor (LY2090314) reversed IL-21-induced metabolic rewiring and inflammatory state. Moreover, IL-21-induced metabolic genes in Tregs in vitro were enriched in human Crohn's disease intestinal Tregs. Adoptively transferred Il21r -/- Tregs efficiently rescued murine colitis in contrast to wild-type Tregs.
CONCLUSIONS: IL-21 triggers metabolic dysfunction associated with Treg inflammatory response. Inhibiting IL-21-induced metabolism in Tregs may mitigate CD4 + T cell-driven chronic intestinal inflammation.

DOI: https://doi.org/10.1101/2023.06.02.543518
Nat Metab. 2023 Jun 19.

A multimodal atlas of tumour metabolism reveals the architecture of gene-metabolite covariation.

Elisa Benedetti, Eric Minwei Liu, Cerise Tang, Fengshen Kuo, Mustafa Buyukozkan, Tricia Park, Jinsung Park, Fabian Correa, A Ari Hakimi, Andrew M Intlekofer, Jan Krumsiek, Ed Reznik.

Tumour metabolism is controlled by coordinated changes in metabolite abundance and gene expression, but simultaneous quantification of metabolites and transcripts in primary tissue is rare. To overcome this limitation and to study gene-metabolite covariation in cancer, we assemble the Cancer Atlas of Metabolic Profiles of metabolomic and transcriptomic data from 988 tumour and control specimens spanning 11 cancer types in published and newly generated datasets. Meta-analysis of the Cancer Atlas of Metabolic Profiles reveals two classes of gene-metabolite covariation that transcend cancer types. The first corresponds to gene-metabolite pairs engaged in direct enzyme-substrate interactions, identifying putative genes controlling metabolite pool sizes. A second class of gene-metabolite covariation represents a small number of hub metabolites, including quinolinate and nicotinamide adenine dinucleotide, which correlate to many genes specifically expressed in immune cell populations. These results provide evidence that gene-metabolite covariation in cellularly heterogeneous tissue arises, in part, from both mechanistic interactions between genes and metabolites, and from remodelling of the bulk metabolome in specific immune microenvironments.

DOI: https://doi.org/10.1038/s42255-023-00817-8
Cell Metab. 2023 Jun 14. pii: S1550-4131(23)00209-7. [Epub ahead of print]

UBE2M-mediated neddylation of TRIM21 regulates obesity-induced inflammation and metabolic disorders.

Xinliang Lu, Xianghui Kong, Hao Wu, Jiayue Hao, Sirui Li, Zichun Gu, Xianchang Zeng, Yingying Shen, Shibo Wang, Jiming Chen, Xuefeng Fei, Yi Sun, Xu Li, Lingling Jiang, Fei Yang, Jianli Wang, Zhijian Cai.

  Inflammation is closely associated with obesity and related metabolic disorders. However, its origin during obesity is largely unknown. Here, we report that ubiquitin-conjugating enzyme E2M (UBE2M) is critical to obesity-related inflammation induced by macrophages. In mice with UBE2M-deficient macrophages, obesity, insulin resistance, and hepatic steatosis induced by a high-fat diet are greatly alleviated, an effect related to the decreased proinflammatory activity of macrophages due to reduced IL-1β production. Mechanistically, UBE2M deficiency inhibits the neddylation of E3 ubiquitin ligase TRIM21 on K129/134, leading to reduced recruitment and ubiquitination-mediated degradation of E3 ubiquitin ligase VHL. Subsequently, VHL reduces HIF-1α-induced IL-1β production by degrading HIF-1α. Targeting macrophage TRIM21 with Trim21 antisense oligonucleotide-loaded red blood cell extracellular vesicles effectively inhibits obesity-induced inflammation and related metabolic disorders. Thus, our results demonstrate that macrophage UBE2M is essential for obesity-induced inflammation and that TRIM21 is a proof-of-concept target for treating obesity and associated metabolic diseases.

Keywords:  TRIM21; UBE2M; inflammation; neddylation; obesity

DOI:  https://doi.org/10.1016/j.cmet.2023.05.011
J Immunol. 2023 Jun 21. pii: ji2200851. [Epub ahead of print]

NK Cells from Human Cytomegalovirus-Seropositive Individuals Have a Distinct Metabolic Profile That Correlates with Elevated mTOR Signaling.

John R Lozada, Bin Zhang, Jeffrey S Miller, Frank Cichocki.

CMV can elicit adaptive immune features in both mouse and human NK cells. Mouse Ly49H+ NK cells expand 100- to 1000-fold in response to mouse CMV infection and persist for months after exposure. Human NKG2C+ NK cells also expand after human CMV (HCMV) infection and persist for months. The clonal expansion of adaptive NK cells is likely an energy-intensive process, and the metabolic requirements that support adaptive NK cell expansion and persistence remain largely uncharacterized. We previously reported that NK cells from HCMV-seropositive donors had increased maximum capacity for both glycolysis and mitochondrial oxidative phosphorylation relative to NK cells from HCMV-seronegative donors. In this article, we report an extension of this work in which we analyzed the metabolomes of NK cells from HCMV-seropositive donors with NKG2C+ expansions and NK cells from HCMV seronegative donors without such expansions. NK cells from HCMV+ donors exhibited striking elevations in purine and pyrimidine deoxyribonucleotides, along with moderate increases in plasma membrane components. Mechanistic target of rapamycin (mTOR) is a serine/threonine protein kinase that, as a part of mTOR complex 1 (mTORC1), bridges nutrient signaling to metabolic processes necessary for cell growth. Signaling through mTORC1 induces both nucleotide and lipid synthesis. We observed elevated mTORC1 signaling on activation in both NKG2C- and NKG2C+ NK cells from HCMV+ donors relative to those from HCMV- donors, demonstrating a correlation between higher mTORC1 activity and synthesis of key metabolites for cell growth and division.

DOI: https://doi.org/10.4049/jimmunol.2200851
Microbiol Spectr. 2023 Jun 23. e0447922

Butyrate Protects against Clostridium difficile Infection by Regulating Bile Acid Metabolism.

Siqi Wang, Leyang Xiang, Fang Li, Wenlin Deng, Pinjing Lv, Ye Chen.

  Clostridium difficile infection (CDI) is caused by a prevalent nosocomial enteric pathogen, leading to high morbidity and mortality. CDI recurrence after antibiotic treatment is high; therefore, it is necessary to develop novel therapeutics against this enteric pathogen. Butyrate is used to treat many diseases because it provides energy, has anti-inflammatory properties, and maintains intestinal barrier function. An anti-CDI effect for butyrate has been reported; however, the specific mechanism remains elusive. This study aimed to explore the potential role and mechanism of butyrate in the treatment of CDI. Using a CDI mouse model, we found that butyrate significantly inhibited CDI development by regulating bile acid metabolism. Dysregulation of fecal bile acid was significantly higher, and levels of short-chain fatty acids were significantly lower in patients with CDI than those in controls. In CDI mice, butyrate exhibited a protective role by enhancing barrier protection, exerting anti-inflammatory effects, and regulating bile acid metabolism. Butyrate treatment also regulated the production of bile salt hydrolase (BSH) flora and activated farnesoid X receptor (FXR), and its therapeutic effects were reduced in CDI mice treated with BSH or FXR inhibitors. Thus, butyrate treatment may serve as a novel therapeutic approach for patients with CDI. IMPORTANCE Here, we show that levels of fecal short-chain fatty acids (SCFAs), particularly butyrate, are reduced, and normal colon structure is damaged in patients with CDI compared with those in healthy individuals. Bile acid (BA) metabolic disorder in patients with CDI is characterized by increased primary BA levels and decreased secondary BAs. In mice, butyrate alters BA metabolism in CDI and may play a vital role in CDI treatment by promoting secondary BA metabolism. Lastly, butyrate-mediated therapeutic effects in CDI require FXR. Our findings demonstrate that butyrate treatment significantly decreases the severity of CDI-induced colitis in mice and affects BA metabolism and FXR activation, which provides a potential alternative treatment for CDI.

Keywords:  Clostridium difficile infection; bile acid metabolism; butyrate; inflammation; intestinal barrier function

DOI:  https://doi.org/10.1128/spectrum.04479-22
Cell Mol Neurobiol. 2023 Jun 21.

Microglial Metabolic Reprogramming: Emerging Insights and Therapeutic Strategies in Neurodegenerative Diseases.

Jifei Miao, Lihua Chen, Xiaojin Pan, Liqing Li, Beibei Zhao, Jiao Lan.

  Microglia, the resident immune cells of the central nervous system, play a critical role in maintaining brain homeostasis. However, in neurodegenerative conditions, microglial cells undergo metabolic reprogramming in response to pathological stimuli, including Aβ plaques, Tau tangles, and α-synuclein aggregates. This metabolic shift is characterized by a transition from oxidative phosphorylation (OXPHOS) to glycolysis, increased glucose uptake, enhanced production of lactate, lipids, and succinate, and upregulation of glycolytic enzymes. These metabolic adaptations result in altered microglial functions, such as amplified inflammatory responses and diminished phagocytic capacity, which exacerbate neurodegeneration. This review highlights recent advances in understanding the molecular mechanisms underlying microglial metabolic reprogramming in neurodegenerative diseases and discusses potential therapeutic strategies targeting microglial metabolism to mitigate neuroinflammation and promote brain health. Microglial Metabolic Reprogramming in Neurodegenerative Diseases This graphical abstract illustrates the metabolic shift in microglial cells in response to pathological stimuli and highlights potential therapeutic strategies targeting microglial metabolism for improved brain health.

Keywords:  Alzheimer's disease; Metabolic reprogramming; Microglia; Multiple sclerosis; Parkinson's disease

DOI:  https://doi.org/10.1007/s10571-023-01376-y
J Vis Exp. 2023 Jun 02.

Real-Time Measurement of the Mitochondrial Bioenergetic Profile of Neutrophils.

Sunitha Pulikkot, Meng Zhao, Zhichao Fan.

Neutrophils are the first line of defense and the most abundant leukocytes in humans. These effector cells perform functions such as phagocytosis and oxidative burst, and create neutrophil extracellular traps (NETs) for microbial clearance. New insights into the metabolic activities of neutrophils challenge the early concept that they primarily rely on glycolysis. Precise measurement of metabolic activities can unfold different metabolic requirements of neutrophils, including the tricarboxylic acid (TCA) cycle (also known as the Krebs cycle), oxidative phosphorylation (OXPHOS), pentose phosphate pathway (PPP), and fatty acid oxidation (FAO) under physiological conditions and in disease states. This paper describes a step-by-step protocol and prerequirements to measure oxygen consumption rate (OCR) as an indicator of mitochondrial respiration on mouse bone marrow-derived neutrophils, human blood-derived neutrophils, and the neutrophil-like HL60 cell line, using metabolic flux analysis on a metabolic extracellular flux analyzer. This method can be used for quantifying the mitochondrial functions of neutrophils under normal and disease conditions.

DOI: https://doi.org/10.3791/64971
Front Immunol. 2023 ;14 1148216

Metabolic reprogramming through mitochondrial biogenesis drives adenosine anti-inflammatory effects: new mechanism controlling gingival fibroblast hyper-inflammatory state.

Nathalie Paladines, Shantiece Dawson, Weston Ryan, Rogelio Serrano-Lopez, Regina Messer, Yuqing Huo, Christopher W Cutler, Erivan S Ramos-Junior, Ana Carolina Morandini.

   Introduction: Fibroblasts are the dominant stromal cells in the gingival lamina propria with a well-established relevance in regulation of inflammation, and in innate immunity. This is exemplified by their hypersecretion of CXCL8, enhancing leukocyte infiltration in chronic and sustained inflammatory conditions. We have previously shown adenosine to be a key metabolic nucleoside that regulates stromal inflammation, but the underlying mechanisms linking adenosine to the metabolic status of fibroblasts and to the resultant inflammatory response are unclear. This study examined, by seahorse real-time cell metabolic analysis, the bioenergetics of the stromal fibroblast response to extracellular adenosine and IL-1β, focusing on CXCL8 secretion by primary human gingival fibroblasts (HGF).
Methods: Markers of the glycolytic pathway and mitochondrial biogenesis were tracked through immunoblot. Further, the influence of adenosine on mitochondrial accumulation was measured by uptake of MitoTracker Red fluorescent probe and assessment of the role of FCCP (a mitochondrial uncoupler) in CXCL8 secretion and mitochondrial accumulation.
Results: Our results show that the anti-inflammatory response of HGF to extracellular adenosine, typified by reduced CXCL8 secretion, is mediated by mitochondrial oxidative phosphorylation, reflected in higher oxygen consumption rate (OCR). In the presence of IL-1β, adenosine-treated cells induced higher ATP production, basal respiration and proton leak compared to IL-1β without adenosine. Surprisingly, adenosine had no additional effect on the IL-1β-induced higher glycolysis rate demonstrated by the extracellular acidification rate (ECAR). In addition, the higher OCR in adenosine-stimulated cells was not due to the mitochondrial fuel dependency or capacity, but due to an increase in mitochondrial biogenesis and accumulation in the cells with concomitant decrease in mitophagy-required p-PINK1 marker. We detected the accumulation of functional mitochondria with increased activation of the AMPK/SIRT1/PGC-1α pathway. The adenosine-induced uptake of MitoTracker was abrogated by PGC-1α inhibition with SR-12898. In addition, the adenosine effects on reduced CXCL8 were ablated by treatment with FCCP, a potent uncoupler of mitochondrial oxidative phosphorylation.
Conclusion: Our findings reveal a key role for mitochondrial bioenergetics in regulation of CXCL8-mediated inflammation by HGF through the adenosine/AMPK/SIRT1/PGC-1α axis. Therapeutically targeting this pathway in gingival fibroblasts might be a promising future strategy to modulate stromal-mediated sustained hyper-inflammatory responses.

Keywords:  adenosine; fibroblasts; inflammation; metabolism; mitochondrial biogenesis

DOI:  https://doi.org/10.3389/fimmu.2023.1148216
Int Immunol. 2023 Jun 18. pii: dxad021. [Epub ahead of print]

Systemic immunometabolism and responses to vaccines: insights from T and B cell perspectives.

Sam Nettelfield, Di Yu, Pablo F Cañete.

  Vaccination stands as the cornerstone in the battle against infectious diseases, and its efficacy hinges upon multifaceted host-related factors encompassing genetics, age, and metabolic status. Remarkably, suboptimal immune responses triggered by metabolic dysregulation is frequently observed in susceptible populations - ranging from malnourished individuals to the obese and elderly - pose a formidable threat to vaccine efficacy. The emerging field of immunometabolism aims to unravel the intricate interplay between immune regulation and metabolic pathways, and recent research has revealed diverse metabolic signatures linked to various vaccine responses and outcomes. In this review, we summarise the major metabolic pathways utilised by B and T cells during vaccine responses, their complex and varied metabolic requirements, and the impact of micronutrients and metabolic hormones on vaccine outcomes. Furthermore, we examine how systemic metabolism influences vaccine responses and the evidence suggesting that metabolic dysregulation in vulnerable populations can lead to impaired vaccine responses. Lastly, we reflect on the challenge of proving causality with respect to the contribution of metabolic dysregulation to poor vaccine outcomes, and highlight the need for a systems biology approach that combines multimodal profiling and mathematical modelling to reveal the underlying mechanisms of such complex interactions.

Keywords:  T cells; elderly; malnutrition; metabolic hormones; obesity

DOI:  https://doi.org/10.1093/intimm/dxad021
Fundam Clin Pharmacol. 2023 Jun 20.

Metabolic reprogramming regulates microglial polarization and its role in cerebral ischemia reperfusion.

Xiao-Rong Sun, Zi-Meng Yao, Lei Chen, Jie Huang, Shu-Ying Dong.

  The brain is quite sensitive to changes in energy supply because of its high energetic demand. Even small changes in energy metabolism may be the basis of impaired brain function, leading to the occurrence and development of cerebral ischemia/reperfusion (I/R) injury. Abundant evidence supports that metabolic defects of brain energy during the post-reperfusion period, especially low glucose oxidative metabolism and elevated glycolysis levels, which play a crucial role in cerebral I/R pathophysiology. Whereas research on brain energy metabolism dysfunction under the background of cerebral I/R mainly focuses on neurons, the research on the complexity of microglia energy metabolism in cerebral I/R is just emerging. As resident immune cells of the central nervous system, microglia activate rapidly and then transform into an M1 or M2 phenotype to correspond to changes in brain homeostasis during cerebral I/R injury. M1 microglia release proinflammatory factors to promote neuroinflammation, while M2 microglia play a neuroprotective role by secreting anti-inflammatory factors. The abnormal brain microenvironment promotes the metabolic reprogramming of microglia, which further affects the polarization state of microglia and disrupts the dynamic equilibrium of M1/M2, resulting in the aggravation of cerebral I/R injury. Increasing evidence suggests that metabolic reprogramming is a key driver of microglial inflammation. For example, M1 microglia preferentially produce energy through glycolysis, while M2 microglia provide energy primarily through oxidative phosphorylation. In this review, we highlight the emerging significance of regulating microglial energy metabolism in cerebral I/R injury.

Keywords:  cerebral ischemia/reperfusion; metabolic reprogramming; microglia; polarization

DOI:  https://doi.org/10.1111/fcp.12928
Adv Pharm Bull. 2023 Mar;13(2): 368-377

Iron Withdrawal with DIBI, a Novel 3-Hydroxypyridin-4-One Chelator Iron-Binding Polymer, Attenuates Macrophage Inflammatory Responses.

Javad Ghassemi-Rad, Wasundara Fernando, Bruce E Holbein, David W Hoskin.

  Purpose: Iron is an essential trace element for the inflammatory response to infection. In this study, we determined the effect of the recently developed iron-binding polymer DIBI on the synthesis of inflammatory mediators by RAW 264.7 macrophages and bone marrow-derived macrophages (BMDMs) in response to lipopolysaccharide (LPS) stimulation. Methods: Flow cytometry was used to determine the intracellular labile iron pool, reactive oxygen species production, and cell viability. Cytokine production was measured by quantitative reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay. Nitric oxide synthesis was determined by the Griess assay. Western blotting was used to assess signal transducer and activator of transcription (STAT) phosphorylation. Results: Macrophages cultured in the presence of DIBI exhibited a rapid and significant reduction in their intracellular labile iron pool. DIBI-treated macrophages showed reduced expression of proinflammatory cytokines interferon-β, interleukin (IL)-1β, and IL-6 in response to LPS. In contrast, exposure to DIBI did not affect LPS-induced expression of tumor necrosis factor-α (TNF-α). The inhibitory effect of DIBI on IL-6 synthesis by LPS-stimulated macrophages was lost when exogenous iron in the form of ferric citrate was added to culture, confirming the selectivity of DIBI for iron. DIBI-treated macrophages showed reduced production of reactive oxygen species and nitric oxide following LPS stimulation. DIBI-treated macrophages also showed a reduction in cytokine-induced activation of STAT 1 and 3, which potentiate LPS-induced inflammatory responses. Conclusion: DIBI-mediated iron withdrawal may be able to blunt the excessive inflammatory response by macrophages in conditions such as systemic inflammatory syndrome.

Keywords:  Cytokines; Inflammation; Iron; Macrophages; Reactive oxygen species; Signal transduction

DOI:  https://doi.org/10.34172/apb.2023.040
Front Immunol. 2023 ;14 1182217

Human immunodeficiency virus and antiretroviral therapy-mediated immune cell metabolic dysregulation in children born to HIV-infected women: potential clinical implications.

Hope Mataramvura, Madeleine J Bunders, Kerina Duri.

  Commencing lifelong antiretroviral therapy (ART) immediately following HIV diagnosis (Option B+) has dramatically improved the health of HIV-infected women and their children, with the majority being of HIV-exposed children born uninfected (HEU). This success has led to an increasing population of HIV-infected women receiving ART during pregnancy and children exposed to ART in utero. Nonetheless, a small proportion of children are still infected with HIV (HEI) each year. HEI children suffer from reduced immunocompetence and host-defence, due to CD4+ T lymphocyte depletion, but also dysregulation of other immune cells including CD8+ T lymphocytes, natural killer (NK) cells, macrophages including B lymphocytes. Furthermore, although HEU children are uninfected, altered immune responses are observed and associated with increased vulnerability to infections. The mechanisms underlying immune dysregulation in HEU children remain poorly described. Building on early studies, emerging data suggests that HIV/ART exposure early in life affects cell metabolic function of HEU children. Prenatal HIV/ART exposure has been associated with dysregulation of mitochondria, including impaired DNA polymerase activity. Furthermore, dysregulation of oxidative phosphorylation (OXPHOS) causes a decreased generation of adenosine triphosphate (ATP) and increased production of reactive oxygen species (ROS), resulting in oxidative stress. These altered metabolic processes can affect immune cell viability and immune responses. Recent studies have indicated that immune-metabolic dysregulation may contribute to HIV-associated pathogenesis and clinical observations associated with HIV and ART exposure in HEU/HEI children. Given the critical role metabolic processes in immune cell functioning, immune-metabolic dysregulation in HEU and HEI children may have implications in effective host-defence responses against pathogens, as well as efficacy of standard ART regimens and future novel HIV cure approaches in HEI children. At the same time, targeting metabolic pathways of immune cells may provide safer and novel approaches for HIV cure strategies. Here, we review the current literature investigating immune-metabolic dysregulation in paediatric HIV pathogenesis.

Keywords:  early life antiretroviral therapy exposure; immune-metabolic dysregulation; immunity; mitochondrial toxicity; mother to child transmission of HIV

DOI:  https://doi.org/10.3389/fimmu.2023.1182217
Nat Commun. 2023 Jun 21. 14(1): 3675

Selective oxidative protection leads to tissue topological changes orchestrated by macrophage during ulcerative colitis.

Juan Du, Junlei Zhang, Lin Wang, Xun Wang, Yaxing Zhao, Jiaoying Lu, Tingmin Fan, Meng Niu, Jie Zhang, Fei Cheng, Jun Li, Qi Zhu, Daoqiang Zhang, Hao Pei, Guang Li, Xingguang Liang, He Huang, Xiaocang Cao, Xinjuan Liu, Wei Shao, Jianpeng Sheng.

Ulcerative colitis is a chronic inflammatory bowel disorder with cellular heterogeneity. To understand the composition and spatial changes of the ulcerative colitis ecosystem, here we use imaging mass cytometry and single-cell RNA sequencing to depict the single-cell landscape of the human colon ecosystem. We find tissue topological changes featured with macrophage disappearance reaction in the ulcerative colitis region, occurring only for tissue-resident macrophages. Reactive oxygen species levels are higher in the ulcerative colitis region, but reactive oxygen species scavenging enzyme SOD2 is barely detected in resident macrophages, resulting in distinct reactive oxygen species vulnerability for inflammatory macrophages and resident macrophages. Inflammatory macrophages replace resident macrophages and cause a spatial shift of TNF production during ulcerative colitis via a cytokine production network formed with T and B cells. Our study suggests components of a mechanism for the observed macrophage disappearance reaction of resident macrophages, providing mechanistic hints for macrophage disappearance reaction in other inflammation or infection situations.

DOI: https://doi.org/10.1038/s41467-023-39173-2
Immunohorizons. 2023 06 01. 7(6): 480-492

Retinoic Acid Signaling Is Required for Dendritic Cell Maturation and the Induction of T Cell Immunity.

Mohammad Farazuddin, Nicholas Ludka, Leon Friesen, Jeffrey J Landers, Jessica J O'Konek, Chang H Kim, James R Baker.

Vitamin A and its biologically active metabolites, all-trans and 9-cis retinoic acid (RA), are thought to be important in generating and modulating immune function. However, RA modulates the function of many types of immune cells, and its specific role in dendritic cell (DC) activation, Ag presentation, and T cell effector function has not been fully characterized. Because RA works primarily through RA receptor (RAR)α, we examined mice with a myeloid cell-specific defect in RA signaling. These transgenic mice have a CD11c-cre-driven expression of a truncated form of RARα that specifically blocks the signaling of all forms of RARs in myeloid cells. This defect results in abnormal DC function, with impaired DC maturation and activation, and reduced Ag uptake and processing. These DC abnormalities were associated with a reduced ability to mount Ag-specific T cell responses to immunization despite having normally functioning T cells. In contrast, the loss of DC-specific RA signaling did not significantly alter levels of Ag-specific Abs postimmunization and resulted in an increase in bronchial IgA. Our findings indicate that RA signaling in DCs is crucial for immune activation, and its absence impairs the development of Ag-specific effector functions of T cell immunity.

DOI: https://doi.org/10.4049/immunohorizons.2300022
J Virol. 2023 Jun 20. e0065623

Short-Chain Fatty Acids Alleviate Vancomycin-Caused Humoral Immunity Attenuation in Rabies-Vaccinated Mice by Promoting the Generation of Plasma Cells via Akt-mTOR Pathway.

Qiong Wu, Yachun Zhang, Caiqian Wang, Yarong Hou, Wenna He, Lingli Wang, Jingyi Xiong, Zeheng Ren, Haoran Wang, Baokun Sui, Danna Zhou, Ming Zhou, Zhen F Fu, Ling Zhao.

  Mounting evidence suggests that gut microbial composition and its metabolites, including short-chain fatty acids (SCFAs), have beneficial effects in regulating host immunogenicity to vaccines. However, it remains unknown whether and how SCFAs improve the immunogenicity of the rabies vaccine. In this study, we investigated the effect of SCFAs on the immune response to rabies vaccine in vancomycin (Vanco)-treated mice and found that oral gavage with butyrate-producing bacteria (C. butyricum) and butyrate supplementation elevated RABV-specific IgM, IgG, and virus-neutralizing antibodies (VNAs) in Vanco-treated mice. Supplementation with butyrate expanded antigen-specific CD4+ T cells and IFN-γ-secreting cells, augmented germinal center (GC) B cell recruitment, promoted plasma cells (PCs) and RABV-specific antibody-secreting cells (ASCs) generation in Vanco-treated mice. Mechanistically, butyrate enhanced mitochondrial function and activated the Akt-mTOR pathway in primary B cells isolated from Vanco-treated mice, ultimately promoting B lymphocyte-induced maturation protein-1 (Blimp-1) expression and CD138+ PCs generation. These results highlight the important role of butyrate in alleviating Vanco-caused humoral immunity attenuation in rabies-vaccinated mice and maintaining host immune homeostasis. IMPORTANCE The gut microbiome plays many crucial roles in the maintenance of immune homeostasis. Alteration of the gut microbiome and metabolites has been shown to impact vaccine efficacy. SCFAs can act as an energy source for B-cells, thereby promoting both mucosal and systemic immunity in the host by inhibiting HDACs and activation of GPR receptors. This study investigates the impact of orally administered butyrate, an SCFA, on the immunogenicity of rabies vaccines in Vanco-treated mice. The results showed that butyrate ameliorated humoral immunity by facilitating the generation of plasma cells via the Akt-mTOR in Vanco-treated mice. These findings unveil the impact of SCFAs on the immune response of the rabies vaccine and confirm the crucial role of butyrate in regulating immunogenicity to rabies vaccines in antibiotic-treated mice. This study provides a fresh insight into the relationship of microbial metabolites and rabies vaccination.

Keywords:  Akt-mTOR pathway; B cells; SCFA; gut microbiome; rabies vaccine; vancomycin

DOI:  https://doi.org/10.1128/jvi.00656-23
Front Immunol. 2023 ;14 1186383

Cell metabolism-based optimization strategy of CAR-T cell function in cancer therapy.

Wenshuai Li, Xuanxuan Pan, Lirong Chen, Haoshu Cui, Shaocong Mo, Yida Pan, Yuru Shen, Menglin Shi, Jianlin Wu, Feifei Luo, Jie Liu, Na Li.

  Adoptive cell therapy (ACT) using chimeric antigen receptor (CAR)-modified T cells has revolutionized the field of immune-oncology, showing remarkable efficacy against hematological malignancies. However, its success in solid tumors is limited by factors such as easy recurrence and poor efficacy. The effector function and persistence of CAR-T cells are critical to the success of therapy and are modulated by metabolic and nutrient-sensing mechanisms. Moreover, the immunosuppressive tumor microenvironment (TME), characterized by acidity, hypoxia, nutrient depletion, and metabolite accumulation caused by the high metabolic demands of tumor cells, can lead to T cell "exhaustion" and compromise the efficacy of CAR-T cells. In this review, we outline the metabolic characteristics of T cells at different stages of differentiation and summarize how these metabolic programs may be disrupted in the TME. We also discuss potential metabolic approaches to improve the efficacy and persistence of CAR-T cells, providing a new strategy for the clinical application of CAR-T cell therapy.

Keywords:  CAR (chimeric antigen receptor) T cells; cancer therapy; cell metabolism; immunity therapy; optimization strategy

DOI:  https://doi.org/10.3389/fimmu.2023.1186383
Front Microbiol. 2023 ;14 1205143

CCL4 participates in the reprogramming of glucose metabolism induced by ALV-J infection in chicken macrophages.

Huixian Wu, Gul Zaib, Huan Luo, Wang Guo, Ting Wu, Shutong Zhu, Chenjun Wang, Wenxian Chai, Qi Xu, Hengmi Cui, Xuming Hu.

  Interferon and chemokine-mediated immune responses are two general antiviral programs of the innate immune system in response to viral infections and have recently emerged as important players in systemic metabolism. This study found that the chemokine CCL4 is negatively regulated by glucose metabolism and avian leukosis virus subgroup J (ALV-J) infection in chicken macrophages. Low expression levels of CCL4 define this immune response to high glucose treatment or ALV-J infection. Moreover, the ALV-J envelope protein is responsible for CCL4 inhibition. We confirmed that CCL4 could inhibit glucose metabolism and ALV-J replication in chicken macrophages. The present study provides novel insights into the antiviral defense mechanism and metabolic regulation of the chemokine CCL4 in chicken macrophages.

Keywords:  CCl4; avian leukosis virus; glucose metabolism; immunity; macrophages

DOI:  https://doi.org/10.3389/fmicb.2023.1205143
J Immunother Cancer. 2023 Jun;pii: e006728. [Epub ahead of print]11(6):

Tryptophan depletion sensitizes the AHR pathway by increasing AHR expression and GCN2/LAT1-mediated kynurenine uptake, and potentiates induction of regulatory T lymphocytes.

Marie Solvay, Pauline Holfelder, Simon Klaessens, Luc Pilotte, Vincent Stroobant, Juliette Lamy, Stefan Naulaerts, Quentin Spillier, Raphaël Frédérick, Etienne De Plaen, Christine Sers, Christiane A Opitz, Benoit J Van den Eynde, Jingjing Zhu.

   BACKGROUND: Indoleamine 2,3-dioxygenase 1 (IDO1) and tryptophan-dioxygenase (TDO) are enzymes catabolizing the essential amino acid tryptophan into kynurenine. Expression of these enzymes is frequently observed in advanced-stage cancers and is associated with poor disease prognosis and immune suppression. Mechanistically, the respective roles of tryptophan shortage and kynurenine production in suppressing immunity remain unclear. Kynurenine was proposed as an endogenous ligand for the aryl hydrocarbon receptor (AHR), which can regulate inflammation and immunity. However, controversy remains regarding the role of AHR in IDO1/TDO-mediated immune suppression, as well as the involvement of kynurenine. In this study, we aimed to clarify the link between IDO1/TDO expression, AHR pathway activation and immune suppression.
METHODS: AHR expression and activation was analyzed by RT-qPCR and western blot analysis in cells engineered to express IDO1/TDO, or cultured in medium mimicking tryptophan catabolism by IDO1/TDO. In vitro differentiation of naïve CD4+ T cells into regulatory T cells (Tregs) was compared in T cells isolated from mice bearing different Ahr alleles or a knockout of Ahr, and cultured in medium with or without tryptophan and kynurenine.
RESULTS: We confirmed that IDO1/TDO expression activated AHR in HEK-293-E cells, as measured by the induction of AHR target genes. Unexpectedly, AHR was also overexpressed on IDO1/TDO expression. AHR overexpression did not depend on kynurenine but was triggered by tryptophan deprivation. Multiple human tumor cell lines overexpressed AHR on tryptophan deprivation. AHR overexpression was not dependent on general control non-derepressible 2 (GCN2), and strongly sensitized the AHR pathway. As a result, kynurenine and other tryptophan catabolites, which are weak AHR agonists in normal conditions, strongly induced AHR target genes in tryptophan-depleted conditions. Tryptophan depletion also increased kynurenine uptake by increasing SLC7A5 (LAT1) expression in a GCN2-dependent manner. Tryptophan deprivation potentiated Treg differentiation from naïve CD4+ T cells isolated from mice bearing an AHR allele of weak affinity similar to the human AHR.
CONCLUSIONS: Tryptophan deprivation sensitizes the AHR pathway by inducing AHR overexpression and increasing cellular kynurenine uptake. As a result, tryptophan catabolites such as kynurenine more potently activate AHR, and Treg differentiation is promoted. Our results propose a molecular explanation for the combined roles of tryptophan deprivation and kynurenine production in mediating IDO1/TDO-induced immune suppression.

Keywords:  Immune Tolerance; Immunomodulation; Indoleamine-Pyrrole 2,3,-Dioxygenase

DOI:  https://doi.org/10.1136/jitc-2023-006728
J Neuroinflammation. 2023 Jun 21. 20(1): 145

HIF1α-dependent hypoxia response in myeloid cells requires IRE1α.

Gaëlle Mawambo, Malika Oubaha, Yusuke Ichiyama, Guillaume Blot, Sergio Crespo-Garcia, Agnieszka Dejda, François Binet, Roberto Diaz-Marin, Christina Sawchyn, Mikhail Sergeev, Rachel Juneau, Randal J Kaufman, El Bachir Affar, Frédérick A Mallette, Ariel M Wilson, Przemyslaw Sapieha.

  Cellular adaptation to low oxygen tension triggers primitive pathways that ensure proper cell function. Conditions of hypoxia and low glucose are characteristic of injured tissues and hence successive waves of inflammatory cells must be suited to function under low oxygen tension and metabolic stress. While Hypoxia-Inducible Factor (HIF)-1α has been shown to be essential for the inflammatory response of myeloid cells by regulating the metabolic switch to glycolysis, less is known about how HIF1α is triggered in inflammation. Here, we demonstrate that cells of the innate immune system require activity of the inositol-requiring enzyme 1α (IRE1α/XBP1) axis in order to initiate HIF1α-dependent production of cytokines such as IL1β, IL6 and VEGF-A. Knockout of either HIF1α or IRE1α in myeloid cells ameliorates vascular phenotypes in a model of retinal pathological angiogenesis driven by sterile inflammation. Thus, pathways associated with ER stress, in partnership with HIF1α, may co-regulate immune adaptation to low oxygen.

Keywords:  Angiogenesis; ER stress; HIF1α; Hypoxia; IRE1α; Inflammation; Microglia; Mononuclear phagocytes; Myeloid; Retina

DOI:  https://doi.org/10.1186/s12974-023-02793-y
ACS Chem Biol. 2023 Jun 22.

CES1 Releases Oxylipins from Oxidized Triacylglycerol (oxTAG) and Regulates Macrophage oxTAG/TAG Accumulation and PGE2/IL-1β Production.

Maggie E Phillips, Oluwabori Adekanye, Abdolsamad Borazjani, J Allen Crow, Matthew K Ross.

Triacylglycerols (TAGs) are storage forms of fat, primarily found in cytoplasmic lipid droplets in cells. TAGs are broken down to their component free fatty acids by lipolytic enzymes when fuel reserves are required. However, polyunsaturated fatty acid (PUFA)-containing TAGs are susceptible to nonenzymatic oxidation reactions, leading to the formation of oxylipins that are esterified to the glycerol backbone (termed oxTAGs). Human carboxylesterase 1 (CES1) is a member of the serine hydrolase superfamily and defined by its ability to catalyze the hydrolysis of carboxyl ester bonds in both toxicants and lipids. CES1 is a bona fide TAG hydrolase, but it is unclear which specific fatty acids are preferentially released during lipolysis. To better understand the biochemical function of CES1 in immune cells, such as macrophages, its substrate selectivity when it encounters oxidized PUFAs in TAG lipid droplets requires study. We sought to identify those esterified oxidized fatty acids liberated from oxTAGs by CES1 because their release can activate signaling pathways that enforce the development of lipid-driven inflammation. Gaining this knowledge will help fill data gaps that exist between CES1 and the lipid-sensing nuclear receptors, PPARγ and LXRα, which are important drivers of lipid metabolism and inflammation in macrophages. Oxidized forms of triarachidonoylglycerol (oxTAG20:4) or trilinoleoylglycerol (oxTAG18:2), which contain physiologically relevant levels of oxidized PUFAs (<5 mol %), were incubated with recombinant CES1 to release oxylipins and nonoxidized arachidonic acid (AA) or linoleic acid (LA). CES1 hydrolyzed each oxTAG, yielding regioisomers of hydroxyeicosatetraenoic acids (5-, 11-, 12-, and 15-HETE) and hydroxyoctadecadienoic acids (9- and 13-HODE). Furthermore, human THP-1 macrophages with deficient CES1 levels exhibited a differential response to extracellular stimuli (oxTAGs, lipopolysaccharide, and 15-HETE) as compared to those with normal CES1 levels, including enhanced oxTAG/TAG lipid accumulation and altered cytokine and prostaglandin E2 profiles. This study suggests that CES1 can metabolize oxTAG lipids to release oxylipins and PUFAs, and it further specifies the substrate selectivity of CES1 in the metabolism of bioactive lipid mediators. We suggest that the accumulation of oxTAGs/TAGs within lipid droplets that arise due to CES1 deficiency enforces an inflammatory phenotype in macrophages.

DOI: https://doi.org/10.1021/acschembio.3c00194
J Exp Med. 2023 Sep 04. pii: e20210788. [Epub ahead of print]220(9):

STE20 kinase TAOK3 regulates type 2 immunity and metabolism in obesity.

Bastiaan Maes, Farzaneh Fayazpour, Leen Catrysse, Guillaume Lornet, Evelien Van De Velde, Caroline De Wolf, Sofie De Prijck, Justine Van Moorleghem, Manon Vanheerswynghels, Kim Deswarte, Benedicte Descamps, Christian Vanhove, Bart Van der Schueren, Roman Vangoitsenhoven, Hamida Hammad, Sophie Janssens, Bart N Lambrecht.

Healthy adipose tissue (AT) contains ST2+ Tregs, ILC2s, and alternatively activated macrophages that are lost in mice or humans on high caloric diet. Understanding how this form of type 2 immunity is regulated could improve treatment of obesity. The STE20 kinase Thousand And One amino acid Kinase-3 (TAOK3) has been linked to obesity in mice and humans, but its precise function is unknown. We found that ST2+ Tregs are upregulated in visceral epididymal white AT (eWAT) of Taok3-/- mice, dependent on IL-33 and the kinase activity of TAOK3. Upon high fat diet feeding, metabolic dysfunction was attenuated in Taok3-/- mice. ST2+ Tregs disappeared from eWAT in obese wild-type mice, but this was not the case in Taok3-/- mice. Mechanistically, AT Taok3-/- Tregs were intrinsically more responsive to IL-33, through higher expression of ST2, and expressed more PPARγ and type 2 cytokines. Thus, TAOK3 inhibits adipose tissue Tregs and regulates immunometabolism under excessive caloric intake.

DOI: https://doi.org/10.1084/jem.20210788
Exp Hematol. 2023 Jun 18. pii: S0301-472X(23)00255-2. [Epub ahead of print]

Distinct roles of the preparatory and payoff phases of glycolysis in hematopoietic stem cells.

Kohei Shiroshita, Hiroshi Kobayashi, Shintaro Watanuki, Daiki Karigane, Yuriko Sorimachi, Shinpei Tamaki, Miho Haraguchi, Masamichi Yamamoto, Ayako Nakamura-Ishizu, Shinichiro Okamoto, Keisuke Kataoka, Keiyo Takubo.

  In physiological conditions, most adult hematopoietic stem cells (HSCs) maintain a quiescent state. Glycolysis is a metabolic process that can be divided into preparatory and payoff phases. While the payoff phase maintains HSC function and properties, the role of the preparatory phase remains unknown. In the present study, we aimed to investigate whether the preparatory or payoff phases of glycolysis were required for maintenance of quiescent and proliferative HSCs. We used glucose-6-phosphate isomerase (Gpi1) as a representative gene for the preparatory phase and glyceraldehyde-3-phosphate dehydrogenase (Gapdh) as a representative gene for the payoff phase of glycolysis. First, we identified that stem cell function and survival were impaired in Gapdh-edited proliferative HSCs. Contrastingly, cell survival was maintained in quiescent Gapdh- and Gpi1-edited HSCs. Gapdh- and Gpi1-defective quiescent HSCs maintained ATP levels by increasing mitochondrial oxidative phosphorylation (OXPHOS), while ATP levels were decreased in Gapdh-edited proliferative HSCs. Interestingly, Gpi1-edited proliferative HSCs maintained ATP levels independent of increased OXPHOS. Oxythiamine, a transketolase inhibitor, impaired proliferation of Gpi1-edited HSCs, suggesting that the nonoxidative pentose phosphate pathway (PPP) is an alternative means to maintain glycolytic flux in Gpi1-defective HSCs. Our findings suggest that OXPHOS compensated for glycolytic deficiencies in quiescent HSCs, and that in proliferative HSCs, nonoxidative PPP compensated for defects in the preparatory phase of glycolysis but not for defects in the payoff phase. These findings provide new insights into regulation of HSC metabolism, which could have implications for development of novel therapies for hematologic disorders. (242/250 words).

Keywords:  CRISPR-Cas9; glycolysis; hematopoietic stem cells; metabolism; mitochondria; quiescence

DOI:  https://doi.org/10.1016/j.exphem.2023.06.003
J Proteome Res. 2023 Jun 20.

Leishmania donovani Induces Multiple Dynamic Responses in the Metabolome Associated with Amastigote Differentiation and Maturation Inside the Human Macrophage.

Miguel Fernández-García, Inês Mesquita, Carolina Ferreira, Marta Araújo, Bhaskar Saha, Ma Fernanda Rey-Stolle, Antonia García, Ricardo Silvestre, Coral Barbas.

  Leishmania donovani infection of macrophages drives profound changes in the metabolism of both the host macrophage and the parasite, which undergoes different phases of development culminating in replication and propagation. However, the dynamics of this parasite-macrophage cometabolome are poorly understood. In this study, a multiplatform metabolomics pipeline combining untargeted, high-resolution CE-TOF/MS and LC-QTOF/MS with targeted LC-QqQ/MS was followed to characterize the metabolome alterations induced in L. donovani-infected human monocyte-derived macrophages from different donors at 12, 36, and 72 h post-infection. The set of alterations known to occur during Leishmania infection of macrophages, substantially expanded in this investigation, characterized the dynamics of the glycerophospholipid, sphingolipid, purine, pentose phosphate, glycolytic, TCA, and amino acid metabolism. Our results showed that only citrulline, arginine, and glutamine exhibited constant trends across all studied infection time points, while most metabolite alterations underwent a partial recovery during amastigote maturation. We determined a major metabolite response pointing to an early induction of sphingomyelinase and phospholipase activities and correlated with amino acid depletion. These data represent a comprehensive overview of the metabolome alterations occurring during promastigote-to-amastigote differentiation and maturation of L. donovani inside macrophages that contributes to our understanding of the relationship between L. donovani pathogenesis and metabolic dysregulation.

Keywords:  Leishmania; host−pathogen interactions; leishmaniasis; metabolic interactions; metabolomics

DOI:  https://doi.org/10.1021/acs.jproteome.2c00845
Biomed Pharmacother. 2023 Jun 15. pii: S0753-3322(23)00802-8. [Epub ahead of print]165 115012

NAMPT inhibition relieves intestinal inflammation by regulating macrophage activation in experimental necrotizing enterocolitis.

Qianyang Liu, Kai Gao, Xionghui Ding, Dandan Mo, Hongjie Guo, Bailin Chen, Bingshan Xia, Cuilian Ye, Gongli Chen, Chunbao Guo.

  Nicotinamide phosphoribosyl transferase (NAMPT) is associated with various NAD+ -consuming enzymatic reactions. The precise role in intestinal mucosal immunity in necrotizing enterocolitis (NEC) is not well defined. Here, we examined whether NAMPT inhibition by the highly specific inhibitor FK866 could alleviate intestinal inflammation during the pathogenesis of NEC. In the present study, we showed that NAMPT expression was upregulated in the human terminal ileum of human infants with NEC. FK866 administration attenuated M1 macrophage polarization and relieved the symptoms of experimental NEC pups. FK866 inhibited intercellular NAD+ levels, macrophage M1 polarization, and the expression of NAD+ -dependent enzymes, such as poly (ADP ribose) polymerase 1 (PARP1) and Sirt6. Consistently, the capacity of macrophages to phagocytose zymosan particles, as well as antibacterial activity, were impaired by FK866, whereas NMN supplementation to restore NAD+ levels reversed the changes in phagocytosis and antibacterial activity. In conclusion, FK866 reduced intestinal macrophage infiltration and skewed macrophage polarization, which is implicated in intestinal mucosal immunity, thereby promoting the survival of NEC pups.

Keywords:  FK866; Macrophage; NAD+; NAMPT; NEC

DOI:  https://doi.org/10.1016/j.biopha.2023.115012
Circ Res. 2023 Jun 23.

Loss of Macrophage mTORC2 Drives Atherosclerosis via FoxO1 and IL-1β Signaling.

Xiangyu Zhang, Trent D Evans, Sunny Chen, Ismail Sergin, Jeremiah Stitham, Se-Jin Jeong, Astrid Rodriguez-Velez, Yu-Sheng Yeh, Arick Park, In-Hyuk Jung, Abhinav Diwan, Joel D Schilling, Oren Rom, Arif Yurdagul, Slava Epelman, Jaehyung Cho, Irfan J Lodhi, Bettina Mittendorfer, Babak Razani.

   BACKGROUND: The mTOR (mechanistic target of rapamycin) pathway is a complex signaling cascade that regulates cellular growth, proliferation, metabolism, and survival. Although activation of mTOR signaling has been linked to atherosclerosis, its direct role in lesion progression and in plaque macrophages remains poorly understood. We previously demonstrated that mTORC1 (mTOR complex 1) activation promotes atherogenesis through inhibition of autophagy and increased apoptosis in macrophages.
METHODS: Using macrophage-specific Rictor- and mTOR-deficient mice, we now dissect the distinct functions of mTORC2 pathways in atherogenesis.
RESULTS: In contrast to the atheroprotective effect seen with blockade of macrophage mTORC1, macrophage-specific mTORC2-deficient mice exhibit an atherogenic phenotype, with larger, more complex lesions and increased cell death. In cultured macrophages, we show that mTORC2 signaling inhibits the FoxO1 (forkhead box protein O1) transcription factor, leading to suppression of proinflammatory pathways, especially the inflammasome/IL (interleukin)-1β response, a key mediator of vascular inflammation and atherosclerosis. In addition, administration of FoxO1 inhibitors efficiently rescued the proinflammatory response caused by mTORC2 deficiency both in vitro and in vivo. Interestingly, collective deletion of macrophage mTOR, which ablates mTORC1- and mTORC2-dependent pathways, leads to minimal change in plaque size or complexity, reflecting the balanced yet opposing roles of these signaling arms.
CONCLUSIONS: Our data provide the first mechanistic details of macrophage mTOR signaling in atherosclerosis and suggest that therapeutic measures aimed at modulating mTOR need to account for its dichotomous functions.

Keywords:  atherosclerosis; inflammation; interleukin; macrophage

DOI:  https://doi.org/10.1161/CIRCRESAHA.122.321542
Biochim Biophys Acta Mol Basis Dis. 2023 Jun 17. pii: S0925-4439(23)00158-8. [Epub ahead of print]1869(7): 166792

Exercise ameliorates chronic inflammatory response induced by high-fat diet via Sestrin2 in an Nrf2-dependent manner.

Sujuan Liu, Huige Li, Yukun Zhang, Hualong Song, Li Fu.

  Chronic inflammation is a major contributor to the development of metabolic disorders and is commonly seen in studies of diet-induced obesity in humans and rodents. Exercise has been shown to have anti-inflammatory properties, though the exact mechanisms are still not fully understood. Sestrins and Nrf2 are of interest to researchers as they are known to protect against inflammation and oxidative stress. In this study, we aim to explore the interconnection between Sestrin2 (SESN2) and Nrf2 and their roles in exercise benefits on chronic inflammation. Our data showed that SESN2 knockout aggravated the abnormalities of body weight, fat mass, and serum lipid that were induced by a high-fat diet (HFD), and a concomitant increase of TNF-α, IL-1β and IL-6 in both serum and skeletal muscle. Notably, exercise was found to reverse these changes, and SESN2 was found to be necessary for exercise to reduce the inflammatory response in skeletal muscles, though not in serum. Immunoprecipitation and bioinformatics prediction experiments further revealed that SESN2 directly binds to Nrf2, indicating a protein-protein interaction between the two. Furthermore, our data demonstrated that SESN2 protein is necessary for exercise-induced effects on Nrf2 pathway in HFD-fed mice, and Nrf2 protein is necessary to enable SESN2 to reduce the inflammation caused by palmitic acid (PA)+ oleic acid (OA) treatment in vitro. Our findings indicate that exercise mitigates chronic inflammation induced by HFD through SESN2 in an Nrf2-dependent manner. Our study reveals a novel molecular mechanism whereby the SESN2/Nrf2 pathway mediates the positive impact of exercise on chronic inflammation.

Keywords:  Chronic inflammation; Exercise; High-fat diet; Nrf2; Sestrin2

DOI:  https://doi.org/10.1016/j.bbadis.2023.166792