bims-imicid 2023-07-23 papers

bims-imicid

Biomed News

on Immunometabolism of infection, cancer and immune-mediated disease

Issue of 2023–07–23
35 papers selected by
Dylan Ryan, University of Cambridge

QUAS-R: An SLC1A5-mediated glutamine uptake assay with single-cell resolution reveals metabolic heterogeneity with immune populations.
The metabolic function of pyruvate kinase M2 regulates reactive oxygen species production and microbial killing by neutrophils.
γδ T cell dichotomy with opposing cytotoxic and wound healing functions in human solid tumors.
TNF and type I IFN induction of the IRG1-itaconate pathway restricts Coxiella burnetii replication within mouse macrophages.
Tissue-specific macrophage immunometabolism.
Interplay between metabolic reprogramming and post-translational modifications: from glycolysis to lactylation.
Growth hormone remodels the 3D-structure of the mitochondria of inflammatory macrophages and promotes metabolic reprogramming.
Glucose metabolism and its role in the maturation and migration of human CD1c+ dendritic cells following exposure to BCG.
High-fat diet-disturbed gut microbiota-colonocyte interactions contribute to dysregulating peripheral tryptophan-kynurenine metabolism.
Mitochondrial reactive oxygen species: double agents in Mycobacterium tuberculosis infection.
Oncolytic viruses engineered to enforce cholesterol efflux restore tumor-associated macrophage phagocytosis and anti-tumor immunity in glioblastoma.
NAC1 confines virus-specific memory formation of CD4+ T cells through the ROCK1-mediated pathway.
Immune Response Gene-1 [IRG1]/itaconate protect against multi-organ injury via inhibiting gasdermin D-mediated pyroptosis and inflammatory response.
Glucose metabolic reprogramming in autoimmune diseases.
Differential effects of sugar and fat on adipose tissue inflammation.
The Oxysterol Receptor EBI2 Links Innate and Adaptive Immunity to Limit IFN Response and Systemic Lupus Erythematosus.
How nearby nutrients shape tumor growth.
MicroRNA-22 Regulates the Pro-inflammatory Responses and M1 Polarization of Macrophages by Targeting GLUT1 and 4-1BBL.
Medium-chain fatty acids modify macrophage expression of metabolic and inflammatory genes in a PPAR β/δ-dependent manner.
The XOR-IDH3α axis controls macrophage polarization in hepatocellular carcinoma.
Tricarboxylic acid (TCA) cycle, sphingolipid, and phosphatidylcholine metabolism are dysregulated in T. gondii infection-induced cachexia.
Obesity-induced dysregulation of skin-resident PPARγ+ Treg cells promotes IL-17A-mediated psoriatic inflammation.
PDHA1 hyperacetylation-mediated lactate overproduction promotes sepsis-induced acute kidney injury via Fis1 lactylation.
Dietary restriction to optimize T cell immunity is an ancient survival strategy conserved in vertebrate evolution.
Exogenous butyrate inhibits butyrogenic metabolism and alters expression of virulence genes in Clostridioides difficile.
Sirt3 improves monosodium urate crystal-induced inflammation by suppressing Acod1 expression.
Pregnane X receptor activation remodels glucose metabolism to promote NAFLD development in obese mice.
Vitamin D status modulates innate immune responses and metabolomic profiles following acute prolonged cycling.
Mitochondria during T cell aging.
An enteroendocrine-microbial axis in the large intestine controls host metabolism.
Kynurenine monooxygenase regulates inflammation during critical illness and recovery in experimental acute pancreatitis.
Excessive Mitochondrial Fission Suppresses Mucosal Repair by Impairing Butyrate Metabolism in Colonocytes.
Metformin improves fibroblast metabolism and ameliorates arthrofibrosis in rats.
FDG uptake reflects an immune-enriched subtype of thyroid cancer: Clinical implications of imaging-based molecular characterization.
d-lactate modulates M2 tumor-associated macrophages and remodels immunosuppressive tumor microenvironment for hepatocellular carcinoma.

Cell Rep. 2023 Jul 19. pii: S2211-1247(23)00839-2. [Epub ahead of print]42(8): 112828

QUAS-R: An SLC1A5-mediated glutamine uptake assay with single-cell resolution reveals metabolic heterogeneity with immune populations.

Leonard R Pelgrom, Gavin M Davis, Simon O'Shaughnessy, Emilie J M Wezenberg, Sander I Van Kasteren, David K Finlay, Linda V Sinclair.

  System-level analysis of single-cell data is rapidly transforming the field of immunometabolism. Given the competitive demand for nutrients in immune microenvironments, there is a need to understand how and when immune cells access these nutrients. Here, we describe a new approach for single-cell analysis of nutrient uptake where we use in-cell biorthogonal labeling of a functionalized amino acid after transport into the cell. In this manner, the bona fide active uptake of glutamine via SLC1A5/ASCT2 could be quantified. We used this assay to interrogate the transport capacity of complex immune subpopulations, both in vitro and in vivo. Taken together, our findings provide an easy sensitive single-cell assay to assess which cells support their function via SLC1A5-mediated uptake. This is a significant addition to the single-cell metabolic toolbox required to decode the metabolic landscape of complex immune microenvironments.

Keywords:  CP: Immunology; CP: Metabolism; SLC1A5; amino acid transport; glutamine uptake; lymphocytes

DOI:  https://doi.org/10.1016/j.celrep.2023.112828
Nat Commun. 2023 07 17. 14(1): 4280

The metabolic function of pyruvate kinase M2 regulates reactive oxygen species production and microbial killing by neutrophils.

Juliana Escher Toller-Kawahisa, Carlos Hiroji Hiroki, Camila Meirelles de Souza Silva, Daniele Carvalho Nascimento, Gabriel Azevedo Públio, Timna Varela Martins, Luis Eduardo Alves Damasceno, Flávio Protásio Veras, Paula Ramos Viacava, Fábio Yuji Sukesada, Emily Anne Day, Alessia Zotta, Tristram Alexander Jasper Ryan, Rodrigo Moreira da Silva, Thiago Mattar Cunha, Norberto Peporine Lopes, Fernando de Queiroz Cunha, Luke Anthony John O'Neill, José Carlos Alves-Filho.

Neutrophils rely predominantly on glycolytic metabolism for their biological functions, including reactive oxygen species (ROS) production. Although pyruvate kinase M2 (PKM2) is a glycolytic enzyme known to be involved in metabolic reprogramming and gene transcription in many immune cell types, its role in neutrophils remains poorly understood. Here, we report that PKM2 regulates ROS production and microbial killing by neutrophils. Zymosan-activated neutrophils showed increased cytoplasmic expression of PKM2. Pharmacological inhibition or genetic deficiency of PKM2 in neutrophils reduced ROS production and Staphylococcus aureus killing in vitro. In addition, this also resulted in phosphoenolpyruvate (PEP) accumulation and decreased dihydroxyacetone phosphate (DHAP) production, which is required for de novo synthesis of diacylglycerol (DAG) from glycolysis. In vivo, PKM2 deficiency in myeloid cells impaired the control of infection with Staphylococcus aureus. Our results fill the gap in the current knowledge of the importance of lower glycolysis for ROS production in neutrophils, highlighting the role of PKM2 in regulating the DHAP and DAG synthesis to promote ROS production in neutrophils.

DOI: https://doi.org/10.1038/s41467-023-40021-6
Nat Cancer. 2023 Jul 20.

γδ T cell dichotomy with opposing cytotoxic and wound healing functions in human solid tumors.

Cathal Harmon, Alexandra Zaborowski, Haim Moore, Pamela St Louis, Karen Slattery, Danielle Duquette, John Scanlan, Harry Kane, Britta Kunkemoeller, Claire L McIntyre, Aine Ni Scannail, Bruce Moran, Ana C Anderson, Des Winter, Donal Brennan, Michael A Brehm, Lydia Lynch.

γδ T cells are important tissue-resident, innate T cells that are critical for tissue homeostasis. γδ cells are associated with positive prognosis in most tumors; however, little is known about their heterogeneity in human cancers. Here, we phenotyped innate and adaptive cells in human colorectal (CRC) and endometrial cancer. We found striking differences in γδ subsets and function in tumors compared to normal tissue, and in the γδ subsets present in tumor types. In CRC, an amphiregulin (AREG)-producing subset emerges, while endometrial cancer is infiltrated by cytotoxic cells. In humanized CRC models, tumors induced this AREG phenotype in Vδ1 cells after adoptive transfer. To exploit the beneficial roles of γδ cells for cell therapy, we developed an expansion method that enhanced cytotoxic function and boosted metabolic flexibility, while eliminating AREG production, achieving greater tumor infiltration and tumor clearance. This method has broad applications in cellular therapy as an 'off-the-shelf' treatment option.

DOI: https://doi.org/10.1038/s43018-023-00589-w
bioRxiv. 2023 Jul 07. pii: 2023.07.07.548079. [Epub ahead of print]

TNF and type I IFN induction of the IRG1-itaconate pathway restricts Coxiella burnetii replication within mouse macrophages.

Mark A Boyer, Natasha Lopes Fischer, Sunny Shin.

The intracellular Gram-negative bacterium Coxiella burnetii replicates within macrophages and causes a zoonotic disease known as Q fever. In murine macrophages, the cytokine tumor necrosis factor (TNF) is critical for restriction of intracellular C. burnetii replication. Here, we show that TNF collaborates with type I interferon (IFN) signaling for maximal control of C. burnetii . We found that TNF and type I IFN upregulate the expression of the metabolic enzyme immune responsive gene 1 (IRG1), also known as cis-aconitate decarboxylase 1 (ACOD1), and that IRG1 is required to restrict C. burnetii T4SS translocation and replication within macrophages. Further, we show that itaconic acid, the metabolic product of IRG1, restricts C. burnetii replication both intracellularly and in axenic culture. These data reveal that TNF and type I IFN upregulate the IRG1-itaconate pathway to restrict intracellular C . burnetii replication within murine macrophages.

DOI: https://doi.org/10.1101/2023.07.07.548079
Curr Opin Immunol. 2023 Jul 18. pii: S0952-7915(23)00088-2. [Epub ahead of print]84 102369

Tissue-specific macrophage immunometabolism.

Hadar Ben-Arosh, Roi Avraham.

Macrophages are phagocytic cells distributed across tissues that sustain homeostasis by constantly probing their local environment. Upon perturbations, macrophages rewire their energy metabolism to execute their immune programs. Intensive research in the field of immunometabolism highlights cell-intrinsic immunometabolites such as succinate and itaconate as immunomodulatory signals. A role for cell-extrinsic stimuli now emerges with evidence for signals that shape macrophages' metabolism in a tissue-specific manner. In this review, we will cover macrophage immunometabolism in the gut, a complex metabolic and immunologically active tissue. During homeostasis, gut macrophages are constantly exposed to pro-inflammatory ligands from the microbiota, and in contrast, are balanced by microbiota-derived anti-inflammatory metabolites. Given their extensive metabolic changes during activation, spatial analyses of the tissue will allow the characterization of metabolic niches of macrophage in the gut. Identifying metabolic perturbations of macrophage subsets during chronic inflammation and infection can direct future tissue-specific metabolotherapies.

DOI: https://doi.org/10.1016/j.coi.2023.102369
Front Immunol. 2023 ;14 1211221

Interplay between metabolic reprogramming and post-translational modifications: from glycolysis to lactylation.

Hengwei Wu, He Huang, Yanmin Zhao.

  Cellular metabolism plays a critical role in determining the fate and function of cells. Metabolic reprogramming and its byproducts have a complex impact on cellular activities. In quiescent T cells, oxidative phosphorylation (OXPHOS) is the primary pathway for survival. However, upon antigen activation, T cells undergo rapid metabolic reprogramming, characterized by an elevation in both glycolysis and OXPHOS. While both pathways are induced, the balance predominantly shifts towards glycolysis, enabling T cells to rapidly proliferate and enhance their functionality, representing the most distinctive signature during activation. Metabolic processes generate various small molecules resulting from enzyme-catalyzed reactions, which also modulate protein function and exert regulatory control. Notably, recent studies have revealed the direct modification of histones, known as lactylation, by lactate derived from glycolysis. This lactylation process influences gene transcription and adds a novel variable to the regulation of gene expression. Protein lactylation has been identified as an essential mechanism by which lactate exerts its diverse functions, contributing to crucial biological processes such as uterine remodeling, tumor proliferation, neural system regulation, and metabolic regulation. This review focuses on the metabolic reprogramming of T cells, explores the interplay between lactate and the immune system, highlights the impact of lactylation on cellular function, and elucidates the intersection of metabolic reprogramming and epigenetics.

Keywords:  epigenetics; glycolysis; lactate; lactylation; metabolic reprogramming

DOI:  https://doi.org/10.3389/fimmu.2023.1211221
Front Immunol. 2023 ;14 1200259

Growth hormone remodels the 3D-structure of the mitochondria of inflammatory macrophages and promotes metabolic reprogramming.

Blanca Soler Palacios, Ricardo Villares, Pilar Lucas, José Miguel Rodríguez-Frade, Ana Cayuela, Jonathan G Piccirillo, Manuel Lombardía, David Delgado Gestoso, Miguel Fernández-García, Cristina Risco, Coral Barbas, Fernando Corrales, Carlos Oscar S Sorzano, Nuria Martínez-Martín, José Javier Conesa, Francisco J Iborra, Mario Mellado.

   Introduction: Macrophages are a heterogeneous population of innate immune cells that support tissue homeostasis through their involvement in tissue development and repair, and pathogen defense. Emerging data reveal that metabolism may control macrophage polarization and function and, conversely, phenotypic polarization may drive metabolic reprogramming.
Methods: Here we use biochemical analysis, correlative cryogenic fluorescence microscopy and cryo-focused ion-beam scanning electron microscopy.
Results: We demonstrate that growth hormone (GH) reprograms inflammatory GM-CSF-primed monocyte-derived macrophages (GM-MØ) by functioning as a metabolic modulator. We found that exogenous treatment of GM-MØ with recombinant human GH reduced glycolysis and lactate production to levels similar to those found in anti-inflammatory M-MØ. Moreover, GH treatment of GM-MØ augmented mitochondrial volume and altered mitochondrial dynamics, including the remodeling of the inner membrane to increase the density of cristae.
Conclusions: Our data demonstrate that GH likely serves a modulatory role in the metabolism of inflammatory macrophages and suggest that metabolic reprogramming of macrophages should be considered as a new target to intervene in inflammatory diseases.

Keywords:  cryo-FIB/SEM; growth hormone; macrophages; metabolism; mitochondria

DOI:  https://doi.org/10.3389/fimmu.2023.1200259
Front Cell Infect Microbiol. 2023 ;13 1113744

Glucose metabolism and its role in the maturation and migration of human CD1c+ dendritic cells following exposure to BCG.

Denise Triglia, Karl M Gogan, Joseph Keane, Mary P O'Sullivan.

   Introduction: Tuberculosis (TB) still kills over 1 million people annually. The only approved vaccine, BCG, prevents disseminated disease in children but shows low efficacy at preventing pulmonary TB. Myeloid dendritic cells (mDCs) are promising targets for vaccines and immunotherapies to combat infectious diseases due to their essential role in linking innate and adaptive immune responses. DCs undergo metabolic reprogramming following exposure to TLR agonists, which is thought to be a prerequisite for a successful host response to infection. We hypothesized that metabolic rewiring also plays a vital role in the maturation and migration of DCs stimulated with BCG. Consequently, we investigated the role of glycolysis in the activation of primary human myeloid CD1c+ DCs in response to BCG.
Methods/results: We show that CD1c+ mDC mature and acquire a more energetic phenotype upon challenge with BCG. Pharmacological inhibition of glycolysis with 2-deoxy-D-glucose (2-DG) decreased cytokine secretion and altered cell surface expression of both CD40 and CCR7 on BCG-challenged, compared to untreated, mDCs. Furthermore, inhibition of glycolysis had differential effects on infected and uninfected bystander mDCs in BCG-challenged cultures. For example, CCR7 expression was increased by 2-DG treatment following challenge with BCG and this increase in expression was seen only in BCG-infected mDCs. Moreover, although 2-DG treatment inhibited CCR7-mediated migration of bystander CD1C+ DCs in a transwell assay, migration of BCG-infected cells proceeded independently of glycolysis.
Discussion: Our results provide the first evidence that glycolysis plays divergent roles in the maturation and migration of human CD1c+ mDC exposed to BCG, segregating with infection status. Further investigation of cellular metabolism in DC subsets will be required to determine whether glycolysis can be targeted to elicit better protective immunity against Mtb.

Keywords:  Bacille Calmette-Guérin vaccine (BCG); Mycobacterium bovis; Mycobacterium tuberculosis; dendritic cell; glycolysis; immunometabolism; tuberculosis; vaccines

DOI:  https://doi.org/10.3389/fcimb.2023.1113744
Microbiome. 2023 Jul 19. 11(1): 154

High-fat diet-disturbed gut microbiota-colonocyte interactions contribute to dysregulating peripheral tryptophan-kynurenine metabolism.

Penghao Sun, Mengli Wang, Yong-Xin Liu, Luqi Li, Xuejun Chai, Wei Zheng, Shulin Chen, Xiaoyan Zhu, Shanting Zhao.

   BACKGROUND: Aberrant tryptophan (Trp)-kynurenine (Kyn) metabolism has been implicated in the pathogenesis of human disease. In particular, populations with long-term western-style diets are characterized by an excess of Kyn in the plasma. Host-gut microbiota interactions are dominated by diet and are essential for maintaining host metabolic homeostasis. However, the role of western diet-disturbed gut microbiota-colonocyte interactions in Trp metabolism remains to be elucidated.
RESULTS: Here, 4-week-old mice were fed with a high-fat diet (HFD), representing a typical western diet, for 4 weeks, and multi-omics approaches were adopted to determine the mechanism by which HFD disrupted gut microbiota-colonocyte interplay causing serum Trp-Kyn metabolism dysfunction. Our results showed that colonocyte-microbiota interactions dominated the peripheral Kyn pathway in HFD mice. Mechanistically, persistent HFD-impaired mitochondrial bioenergetics increased colonic epithelial oxygenation and caused metabolic reprogramming in colonites to support the expansion of Proteobacteria in the colon lumen. Phylum Proteobacteria-derived lipopolysaccharide (LPS) stimulated colonic immune responses to upregulate the indoleamine 2,3-dioxygenase 1 (IDO1)-mediated Kyn pathway, leading to Trp depletion and Kyn accumulation in the circulation, which was further confirmed by transplantation of Escherichia coli (E.coli) indicator strains and colonic IDO1 depletion. Butyrate supplementation promoted mitochondrial functions in colonocytes to remodel the gut microbiota in HFD mice, consequently ameliorating serum Kyn accumulation.
CONCLUSIONS: Our results highlighted that HFD disrupted the peripheral Kyn pathway in a gut microbiota-dependent manner and that the continuous homeostasis of gut bacteria-colonocytes interplay played a central role in the regulation of host peripheral Trp metabolism. Meanwhile, this study provided new insights into therapies against western diet-related metabolic disorders. Video Abstract.

Keywords:  Gut microbiota; High-fat diet; Kynurenine; Mitochondrial dysfunction; Tryptophan metabolism

DOI:  https://doi.org/10.1186/s40168-023-01606-x
Curr Opin Immunol. 2023 Jul 12. pii: S0952-7915(23)00085-7. [Epub ahead of print]84 102366

Mitochondrial reactive oxygen species: double agents in Mycobacterium tuberculosis infection.

Lily M Ellzey, Kristin L Patrick, Robert O Watson.

In addition to housing the major energy-producing pathways in cells, mitochondria are active players in innate immune responses. One critical way mitochondria fulfill this role is by releasing damage-associated molecular patterns (mtDAMPs) that are recognized by innate sensors to activate pathways including, but not limited to, cytokine expression, selective autophagy, and cell death. Mitochondrial reactive oxygen species (mtROS) is a multifunctional mtDAMP linked to pro- and antimicrobial immune outcomes. Formed as a by-product of energy generation, mtROS links mitochondrial metabolism with downstream innate immune responses. As a result, altered cellular metabolism can change mtROS levels and impact downstream antimicrobial responses in a variety of ways. MtROS has emerged as a particularly important mediator of pathogenesis during infection with Mycobacterium tuberculosis (Mtb), an intracellular bacterial pathogen that continues to pose a significant threat to global public health. Here, we will summarize how Mtb modulates mtROS levels in infected macrophages and how mtROS dictates Mtb infection outcomes by controlling inflammation, lipid peroxidation, and cell death. We propose that mtROS may serve as a biomarker to predict tuberculosis patient outcomes and/or a target for host-directed therapeutics.

DOI: https://doi.org/10.1016/j.coi.2023.102366
Nat Commun. 2023 Jul 20. 14(1): 4367

Oncolytic viruses engineered to enforce cholesterol efflux restore tumor-associated macrophage phagocytosis and anti-tumor immunity in glioblastoma.

Shiqun Wang, Wei Yan, Lingkai Kong, Shuguang Zuo, Jingyi Wu, Chunxiao Zhu, Huaping Huang, Bohao He, Jie Dong, Jiwu Wei.

The codependency of cholesterol metabolism sustains the malignant progression of glioblastoma (GBM) and effective therapeutics remain scarce. In orthotopic GBM models in male mice, we identify that codependent cholesterol metabolism in tumors induces phagocytic dysfunction in monocyte-derived tumor-associated macrophages (TAMs), resulting in disease progression. Manipulating cholesterol efflux with apolipoprotein A1 (ApoA1), a cholesterol reverse transporter, restores TAM phagocytosis and reactivates TAM-T cell antitumor immunity. Cholesterol metabolomics analysis of in vivo-sorted TAMs further reveals that ApoA1 mediates lipid-related metabolic remodeling and lowers 7-ketocholesterol levels, which directly inhibits tumor necrosis factor signaling in TAMs through mitochondrial translation inhibition. An ApoA1-armed oncolytic adenovirus is also developed, which restores antitumor immunity and elicits long-term tumor-specific immune surveillance. Our findings provide insight into the mechanisms by which cholesterol metabolism impairs antitumor immunity in GBM and offer an immunometabolic approach to target cholesterol disturbances in GBM.

DOI: https://doi.org/10.1038/s41467-023-39683-z
J Med Virol. 2023 Jul;95(7): e28957

NAC1 confines virus-specific memory formation of CD4+ T cells through the ROCK1-mediated pathway.

Liqing Wang, Hao-Yun Peng, Jugal Kishore Das, Anil Kumar, Yijie Ren, Darby J Ballard, Xiaofang Xiong, Wen Yang, Xingcong Ren, Paul de Figueiredo, Jin-Ming Yang, Jianxun Song.

  Nucleus accumbens-associated protein 1 (NAC1), a transcriptional cofactor, has been found to play important roles in regulating regulatory T cells, CD8+ T cells, and antitumor immunity, but little is known about its effects on T-cell memory. In this study, we found that NAC1 expression restricts memory formation of CD4+ T cells during viral infection. Analysis of CD4+ T cells from wild-type (WT) and NAC1-deficient (-/- ) mice showed that NAC1 is essential for T-cell metabolism, including glycolysis and oxidative phosphorylation, and supports CD4+ T-cell survival in vitro. We further demonstrated that a deficiency of NAC1 downregulates glycolysis and correlates with the AMPK-mTOR pathway and causes autophagy defective in CD4+ T cells. Loss of NAC1 reduced the expression of ROCK1 and the phosphorylation and stabilization of BECLIN1. However, a forced expression of ROCK1 in NAC1-/- CD4+ T cells restored autophagy and the activity of the AMPK-mTOR pathway. In animal experiments, adoptively transferred NAC1-/- CD4+ T cells or NAC1-/- mice challenged with VACV showed enhanced formation of VACV-specific CD4+ memory T cells compared to adoptively transferred WT CD4+ T cells or WT mice. This memory T-cell formation enhancement was abrogated by forcing expression of ROCK1. Our study reveals a novel role for NAC1 as a suppressor of CD4+ T-cell memory formation and suggests that targeting NAC1 could be a new approach to promoting memory CD4+ T-cell development, which is critical for an effective immune response against pathogens.

Keywords:  CD4+ T cells; NAC1; ROCK1; cellular metabolism; memory formation

DOI:  https://doi.org/10.1002/jmv.28957
Inflammopharmacology. 2023 Jul 20.

Immune Response Gene-1 [IRG1]/itaconate protect against multi-organ injury via inhibiting gasdermin D-mediated pyroptosis and inflammatory response.

Wenchang Yang, Yaxin Wang, Yongzhou Huang, Tao Wang, Chengguo Li, Peng Zhang, Weizhen Liu, Yuping Yin, Ruidong Li, Kaixiong Tao.

  Sepsis is a multiple organ dysfunction syndrome due to a dysregulated response to infection with unacceptably high mortality. Currently, no effective treatment exists for sepsis. IRG1/itaconate has been considered to play a protective role for various inflammatory diseases. In the present study, we explored the protective role and mechanisms of IRG1/itaconate on lipopolysaccharide (LPS)-induced multi-organ injury. The LPS-induced sepsis model was used. IRG1-/- and wild type mice were used to explore the protective role of IRG1/itaconate on multi-organ injury. GSDMD-/- mice were used to explore the effect of GSDMD-mediated pyroptosis on LPS-induced model. RAW264.7 cells and bone-marrow-derived macrophages (BMDMs) were used for in vitro studies. In vivo experiments, we found IRG1 deficiency aggravated LPS-induced multi-organ injury especially lung injury. 4-Octyl itaconate (4-OI), a derivative of itaconate, significantly ameliorated LPS-induced acute lung, liver, and kidney injury. Furthermore, IRG1/4-OI decreased serum interleukin-1β (IL-1β), IL-6, tumor necrosis factor-α (TNF-α) level, macrophage infiltration, and TUNEL-positive cells in lung and liver tissue. Western blot showed IRG1/itaconate decreased the expressions of p-ERK, p-P38, p-JNK, and p-P65 and increased the expression of Nrf2/HO-1 in lung tissue. Meanwhile, 4-OI inhibited the expression of GSDMD-N. In vitro experiments, 4-OI inhibited ROS production and promoted apoptosis under LPS stimulation in RAW264.7 cells. Furthermore, 4-OI inhibited nuclear factor-kappaB/mitogen-activated protein kinase pathways and GSDMD-medicated pyroptosis in BMDMs. Finally, we used GSDMD-/- mice to explore the effect of pyroptosis on LPS-induced multi-organ injury. The results showed that GSDMD deficiency significantly ameliorated lung injury. In conclusion, our data demonstrated that IRG1/itaconate protect against multi-organ injury via inhibiting inflammation response and GSDMD-indicated pyroptosis, which may be a promising agent for protecting against sepsis.

Keywords:  Inflammation; LPS; Multi-organ injury; Pyroptosis; Sepsis

DOI:  https://doi.org/10.1007/s10787-023-01278-x
Anim Cells Syst (Seoul). 2023 ;27(1): 149-158

Glucose metabolic reprogramming in autoimmune diseases.

Hoim Jeong, Beomgu Lee, Seung Jin Han, Dong Hyun Sohn.

  Autoimmune diseases are conditions in which the immune system mistakenly targets and damages healthy tissue in the body. In recent decades, the incidence of autoimmune diseases has increased, resulting in a significant disease burden. The current autoimmune therapies focus on targeting inflammation or inducing immunosuppression rather than addressing the underlying cause of the diseases. The activity of metabolic pathways is elevated in autoimmune diseases, and metabolic changes are increasingly recognized as important pathogenic processes underlying these. Therefore, metabolically targeted therapies may represent an important strategy for treating autoimmune diseases. This review provides a comprehensive overview of the evidence surrounding glucose metabolic reprogramming and its potential applications in drug discovery and development for autoimmune diseases, such as type 1 diabetes, multiple sclerosis, systemic lupus erythematosus, rheumatoid arthritis, and systemic sclerosis.

Keywords:  Glucose metabolic reprogramming; autoimmune diseases; glucose transporter; glycolysis; metformin

DOI:  https://doi.org/10.1080/19768354.2023.2234986
iScience. 2023 Jul 21. 26(7): 107163

Differential effects of sugar and fat on adipose tissue inflammation.

Tracey Avequin, Kin H Lau, Althea N Waldhart, Hannah Guak, Holly Dykstra, Connie Krawczyk, Ning Wu.

  Obese individuals experience low grade inflammation initiated within their adipose tissue. However, the early events that lead to the release of these inflammatory factors from adipose tissue are poorly characterized. To separate glucose effects from lipid effects on adipose tissue, we used an adipose-specific TXNIP knockout model where excess basal glucose influx into adipocytes led to modest increase in adiposity without using high fat diet. We found an uncoupling of two events that are generally presumed to be coregulated: (1) an increase of adipose tissue macrophage (ATM) number; and (2) pro-inflammatory activation of ATMs. These two events are associated with different triggering signals: elevated free fatty acids output and extracellular matrix remodeling with increased ATM number, whereas decreased adiponectin level with activated ATM. This separation reflects non-overlapping pathways regulated by glucose and lipids in adipocytes, and neither group alone is sufficient to elicit the full inflammatory response in adipose tissue.

Keywords:  Cell biology; Endocrinology; Immunology

DOI:  https://doi.org/10.1016/j.isci.2023.107163
Adv Sci (Weinh). 2023 Jul 19. e2207108

The Oxysterol Receptor EBI2 Links Innate and Adaptive Immunity to Limit IFN Response and Systemic Lupus Erythematosus.

Fang Zhang, Baokai Zhang, Huihua Ding, Xiangyue Li, Xilin Wang, Xiaomin Zhang, Qiaojie Liu, Qiuyun Feng, Mingshun Han, Longlong Chen, Linlin Qi, Dan Yang, Xiaojing Li, Xingguo Zhu, Qi Zhao, Jiaqian Qiu, Zhengjiang Zhu, Huiru Tang, Nan Shen, Hongyan Wang, Bin Wei.

  Systemic lupus erythematosus (SLE) is a complex autoimmune disease with abnormal activation of the immune system. Recent attention is increasing about how aberrant lipid and cholesterol metabolism is linked together with type I interferon (IFN-I) signaling in the regulation of the pathogenesis of SLE. Here, a metabonomic analysis is performed and increased plasma concentrations of oxysterols, especially 7α, 25-dihydroxycholesterol (7α, 25-OHC), are identified in SLE patients. The authors find that 7α, 25-OHC binding to its receptor Epstein-Barr virus-induced gene 2 (EBI2) in macrophages can suppress STAT activation and the production of IFN-β, chemokines, and cytokines. Importantly, monocytes/macrophages from SLE patients and mice show significantly reduced EBI2 expression, which can be triggered by IFN-γ produced in activated T cells. Previous findings suggest that EBI2 enhances immune cell migration. Opposite to this effect, the authors demonstrate that EBI2-deficient macrophages produce higher levels of chemokines and cytokines, which recruits and activates myeloid cells,T and B lymphocytes to exacerbate tetramethylpentadecane-induced SLE. Together, via sensing the oxysterol 7α, 25-OHC, EBI2 in macrophages can modulate innate and adaptive immune responses, which may be used as a potential diagnostic marker and therapeutic target for SLE.

Keywords:  Epstein-Barr virus-induced gene 2; interferon; macrophages; oxysterols; systemic lupus erythematosus

DOI:  https://doi.org/10.1002/advs.202207108
Elife. 2023 07 17. pii: e89825. [Epub ahead of print]12

How nearby nutrients shape tumor growth.

Nada Kalaany.

  Studying the nutrient composition immediately surrounding pancreatic cancer cells provides new insights into their metabolic properties and how they can evade the immune system to promote disease progression.

Keywords:  amino acid homeostasis; biochemistry; cancer; cancer biology; chemical biology; human; immunotherapy; metabolism; mouse; nutrient stress; tumor microenvironment

DOI:  https://doi.org/10.7554/eLife.89825
J Immunol Res. 2023 ;2023 2457006

MicroRNA-22 Regulates the Pro-inflammatory Responses and M1 Polarization of Macrophages by Targeting GLUT1 and 4-1BBL.

Young Jun Kang.

Many microRNAs (miRNAs) are selectively expressed in mammalian immune cells and have been linked to immune responses in host defense and autoimmune disease. In macrophages, miRNAs regulate cell metabolism by repressing the expression of genes such as transcription factors, enzymes, and metabolism-related molecules, as well as the expression of genes that impact inflammatory responses and phenotype determination. Previous studies showed that miR-22 plays a role in a variety of biological processes, such as cancer cell growth, cell survival, and cell expansion. In CD4 + T cells of inflammatory bowel disease patients, miR-22 is upregulated and regulates inflammasome-mediated responses. However, it has not yet been determined how miR-22 contributes to the activation of innate immune cells. In this study, we identified a mechanism of toll-like receptors- (TLR-) dependent miR-22 induction that regulates the downstream signaling pathway linking inflammatory responses and macrophage polarization. MiR-22 is induced via TLR-signaling, which regulates the induction of Slc2a1 (glucose transporter 1 and Glut1) and Tnfsf9 (tumor necrosis factor 9, 4-1BB ligand, and 4-1BBL) mRNAs that contribute to sustained inflammatory responses and the polarization of macrophages. Our observations support further efforts to explore a potential therapeutic strategy using miR-22 for the modulation of excessive macrophage activation for the treatment of inflammatory diseases.

DOI: https://doi.org/10.1155/2023/2457006
Sci Rep. 2023 07 18. 13(1): 11573

Medium-chain fatty acids modify macrophage expression of metabolic and inflammatory genes in a PPAR β/δ-dependent manner.

Paula V Gaete, Luz D Nieves-Barreto, Valentina Guatibonza-García, Mónica Losada-Barragán, Karina Vargas-Sánchez, Carlos O Mendivil.

There is great interest on medium chain fatty acids (MCFA) for cardiovascular health. We explored the effects of MCFA on the expression of lipid metabolism and inflammatory genes in macrophages, and the extent to which they were mediated by the nuclear receptor peroxisome proliferator-activated receptor beta/delta (PPAR β/δ). J774A.1 murine macrophages were exposed to octanoate or decanoate as MCFA, a long-chain fatty acid control (palmitate), or the PPAR β/δ agonist GW501516, with or without lipopolysaccharide (LPS) stimulation, and with or without an siRNA-induced knockdown of PPAR β/δ. MCFA increased the expression of Plin2, encoding a lipid-droplet associated protein with anti-inflammatory effects in macrophages, in a partially PPAR β/δ-dependent manner. Both MCFA stimulated expression of the cholesterol efflux pump ABCA1, more pronouncedly under LPS stimulation and in the absence of PPAR β/δ. Octanoate stimulated the expression of Pltp, encoding a phospholipid transfer protein that aids ABCA1 in cellular lipid efflux. Only palmitate increased expression of the proinflammatory genes Il6, Tnf, Nos2 and Mmp9. Non-stimulated macrophages exposed to MCFA showed less internalization of fluorescently labeled lipoproteins. MCFA influenced the transcriptional responses of macrophages favoring cholesterol efflux and a less inflammatory response compared to palmitate. These effects were partially mediated by PPAR β/δ.

DOI: https://doi.org/10.1038/s41598-023-38700-x
J Hepatol. 2023 Jul 18. pii: S0168-8278(23)04984-X. [Epub ahead of print]

The XOR-IDH3α axis controls macrophage polarization in hepatocellular carcinoma.

Yijun Lu, Qikai Sun, Qifei Guan, Zechuan Zhang, Qifeng He, Jianbo He, Zetao Ji, Wenfang Tian, Xiaoliang Xu, Yang Liu, Yin Yin, Chang Zheng, Senlin Lian, Bing Xu, Pin Wang, Runqiu Jiang, Beicheng Sun.

   BACKGROUND & AIMS: Tumor-associated macrophages (TAMs) are indispensable in the hepatocellular carcinoma (HCC) tumor microenvironment. Xanthine oxidoreductase (XOR), also known as xanthine dehydrogenase (XDH), participates in purine metabolism, uric acid production, and macrophage polarization to a pro-inflammatory phenotype. However, the role of XOR in HCC-associated TAMs is unclear.
METHODS: We evaluated the XOR level in macrophages isolated from HCC tissues and paired adjacent tissues. We established DEN/carbon tetrachloride (CCl4)-induced and orthotopically implanted HCC mouse models using mice with Xdh-specific depletion in the myeloid cell lineage (Xdhf/fLyz2cre) or Kupffer cells (Xdhf/fClec4fcre). We determined metabolic differences using specific methodologies, including metabolomics and metabolic flux.
RESULTS: We found that XOR expression was downregulated in HCC TAMs and positively correlated with patient survival, which was strongly related to the characteristics of the tumor microenvironment (TME), especially hypoxia. Using HCC-inflicted mice (Xdhf/fLyz2cre and Xdhf/fClec4fcre), we revealed that XOR loss in monocyte-derived TAMs rather than Kupffer cells promoted their M2 polarization and CD8+ T-cell exhaustion, which exacerbated HCC progression. In addition, the tricarboxylic acid cycle was disturbed, and the generation of α-ketoglutarate (α-KG) was enhanced within XOR-depleted macrophages. XOR inhibited α-KG production by interacting with IDH3α catalytic sites (K142 and Q139). The increased IDH3α activity caused increased adenosine and kynurenic acid production in the TAMs, which enhanced the immunosuppressive effects of the TAMs and CD8+ T cells.
CONCLUSIONS: The XOR-IDH3α axis mediates TAM polarization and HCC progression and may be a small-molecule therapeutic or immunotherapeutic target against suppressive HCC TAMs.
IMPACT AND IMPLICATIONS: HCC is one of the cancers with the highest morbidity in the world, and its 5-year survival rate is low. Currently, lots of immunotherapies have been applied to the treatment of HCC, but the curative effects are not satisfactory. TME of HCC is full of different infiltrating immune cells. TAMs are vital components in TME and involved in HCC progression. Herein, we confirm the downregulation of XOR expression in TAMs isolated from human HCC tissues. The loss of XOR in monocyte-derived macrophages increases IDH3 activity and results in an increase in α-KG production, which can promote M2-like polarization. Additionally, XOR-null TAMs derived from monocytes promote CD8+ T-cell exhaustion via the upregulation of immunosuppressive metabolites, including adenosine and KYNA. Given the prevalence and high rate of incidence of HCC and the need for improved therapeutic options for patients, our findings identify potential therapeutic targets that may be further studied to develop improved therapies.

Keywords:  Tumor-associated macrophages; hepatocellular carcinoma; immunotherapy; isocitrate dehydrogenase 3α; xanthine oxidoreductase

DOI:  https://doi.org/10.1016/j.jhep.2023.06.022
Heliyon. 2023 Jul;9(7): e17411

Tricarboxylic acid (TCA) cycle, sphingolipid, and phosphatidylcholine metabolism are dysregulated in T. gondii infection-induced cachexia.

Tzu-Yu Feng, Stephanie J Melchor, Xiao-Yu Zhao, Haider Ghumman, Mark Kester, Todd E Fox, Sarah E Ewald.

  Cachexia is a life-threatening disease characterized by chronic, inflammatory muscle wasting and systemic metabolic impairment. Despite its high prevalence, there are no efficacious therapies for cachexia. Mice chronically infected with the protozoan parasite Toxoplasma gondii represent a novel animal model recapitulating the chronic kinetics of cachexia. To understand how perturbations to metabolic tissue homeostasis influence circulating metabolite availability we used mass spectrometry analysis. Despite the significant reduction in circulating triacylglycerides, non-esterified fatty acids, and glycerol, sphingolipid long-chain bases and a subset of phosphatidylcholines (PCs) were significantly increased in the sera of mice with T. gondii infection-induced cachexia. In addition, the TCA cycle intermediates α-ketoglutarate, 2-hydroxyglutarate, succinate, fumarate, and malate were highly depleted in cachectic mouse sera. Sphingolipids and their de novo synthesis precursors PCs are the major components of the mitochondrial membrane and regulate mitochondrial function consistent with a causal relationship in the energy imbalance driving T. gondii-induced chronic cachexia.

Keywords:  Cachexia; Ceramides; Lipid rebound; Liver atrophy; Sphingolipids; TCA cycle; Toxoplasma gondii

DOI:  https://doi.org/10.1016/j.heliyon.2023.e17411
Immunity. 2023 Jul 14. pii: S1074-7613(23)00278-9. [Epub ahead of print]

Obesity-induced dysregulation of skin-resident PPARγ+ Treg cells promotes IL-17A-mediated psoriatic inflammation.

Pulavendran Sivasami, Cody Elkins, Pamela P Diaz-Saldana, Kyndal Goss, Amy Peng, Michael Hamersky, Jennifer Bae, Miaoer Xu, Brian P Pollack, Edwin M Horwitz, Christopher D Scharer, Lindsey Seldin, Chaoran Li.

  Obesity is a major risk factor for psoriasis, but how obesity disrupts the regulatory mechanisms that keep skin inflammation in check is unclear. Here, we found that skin was enriched with a unique population of CD4+Foxp3+ regulatory T (Treg) cells expressing the nuclear receptor peroxisome proliferation-activated receptor gamma (PPARγ). PPARγ drove a distinctive transcriptional program and functional suppression of IL-17A+ γδ T cell-mediated psoriatic inflammation. Diet-induced obesity, however, resulted in a reduction of PPARγ+ skin Treg cells and a corresponding loss of control over IL-17A+ γδ T cell-mediated inflammation. Mechanistically, PPARγ+ skin Treg cells preferentially took up elevated levels of long-chain free fatty acids in obese mice, which led to cellular lipotoxicity, oxidative stress, and mitochondrial dysfunction. Harnessing the anti-inflammatory properties of these PPARγ+ skin Treg cells could have therapeutic potential for obesity-associated inflammatory skin diseases.

Keywords:  IL-17A; PPARγ; Treg; free fatty acid; high-fat diet; immunometabolism; obesity; psoriasis; skin; γδ T cell

DOI:  https://doi.org/10.1016/j.immuni.2023.06.021
Cell Death Dis. 2023 Jul 21. 14(7): 457

PDHA1 hyperacetylation-mediated lactate overproduction promotes sepsis-induced acute kidney injury via Fis1 lactylation.

Sheng An, Yi Yao, Hongbin Hu, Junjie Wu, Jiaxin Li, Lulan Li, Jie Wu, Maomao Sun, Zhiya Deng, Yaoyuan Zhang, Shenhai Gong, Qiaobing Huang, Zhongqing Chen, Zhenhua Zeng.

The increase of lactate is an independent risk factor for patients with sepsis-induced acute kidney injury (SAKI). However, whether elevated lactate directly promotes SAKI and its mechanism remain unclear. Here we revealed that downregulation of the deacetylase Sirtuin 3 (SIRT3) mediated the hyperacetylation and inactivation of pyruvate dehydrogenase E1 component subunit alpha (PDHA1), resulting in lactate overproduction in renal tubular epithelial cells. We then found that the incidence of SAKI and renal replacement therapy (RRT) in septic patients with blood lactate ≥ 4 mmol/L was increased significantly, compared with those in septic patients with blood lactate < 2 mmol/L. Further in vitro and in vivo experiments showed that additional lactate administration could directly promote SAKI. Mechanistically, lactate mediated the lactylation of mitochondrial fission 1 protein (Fis1) lysine 20 (Fis1 K20la). The increase in Fis1 K20la promoted excessive mitochondrial fission and subsequently induced ATP depletion, mitochondrial reactive oxygen species (mtROS) overproduction, and mitochondrial apoptosis. In contrast, PDHA1 activation with sodium dichloroacetate (DCA) or SIRT3 overexpression decreased lactate levels and Fis1 K20la, thereby alleviating SAKI. In conclusion, our results show that PDHA1 hyperacetylation and inactivation enhance lactate overproduction, which mediates Fis1 lactylation and exacerbates SAKI. Reducing lactate levels and Fis1 lactylation attenuate SAKI.

DOI: https://doi.org/10.1038/s41419-023-05952-4
Cell Mol Life Sci. 2023 Jul 20. 80(8): 219

Dietary restriction to optimize T cell immunity is an ancient survival strategy conserved in vertebrate evolution.

Kunming Li, Xiumei Wei, Kang Li, Qian Zhang, Jiansong Zhang, Ding Wang, Jialong Yang.

  Recent advances highlight a key role of transient fasting in optimizing immunity of human and mouse. However, it remains unknown whether this strategy is independently acquired by mammals during evolution or instead represents gradually evolved functions common to vertebrates. Using a tilapia model, we report that T cells are the main executors of the response of the immune system to fasting and that dietary restriction bidirectionally modulates T cell immunity. Long-term fasting impaired T cell immunity by inducing intense autophagy, apoptosis, and aberrant inflammation. However, transient dietary restriction triggered moderate autophagy to optimize T cell response by maintaining homeostasis, alleviating inflammation and tissue damage, as well as enhancing T cell activation, proliferation and function. Furthermore, AMPK is the central hub linking fasting and autophagy-controlled T cell immunity in tilapia. Our findings demonstrate that dietary restriction to optimize immunity is an ancient strategy conserved in vertebrate evolution, providing novel perspectives for understanding the adaptive evolution of T cell response.

Keywords:  Autophagy; Dietary restriction; Evolution; T cells; Tilapia

DOI:  https://doi.org/10.1007/s00018-023-04865-x
bioRxiv. 2023 Jul 06. pii: 2023.07.06.548018. [Epub ahead of print]

Exogenous butyrate inhibits butyrogenic metabolism and alters expression of virulence genes in Clostridioides difficile.

Daniel A Pensinger, Horia A Dobrila, David M Stevenson, Nicole M Davis, Daniel Amador-Noguez, Andrew J Hryckowian.

The gut microbiome engenders colonization resistance against the diarrheal pathogen Clostridioides difficile but the molecular basis of this colonization resistance is incompletely understood. A prominent class of gut microbiome-produced metabolites important for colonization resistance against C. difficile is short chain fatty acids (SCFAs). In particular, one SCFA (butyrate) decreases the fitness of C. difficile in vitro and is correlated with C. difficile - inhospitable gut environments, both in mice and in humans. Here, we demonstrate that butyrate-dependent growth inhibition in C. difficile occurs under conditions where C. difficile also produces butyrate as a metabolic end product. Furthermore, we show that exogenous butyrate is internalized into C. difficile cells, is incorporated into intracellular CoA pools where it is metabolized in a reverse (energetically unfavorable) direction to crotonyl-CoA and ( S )-3-hydroxybutyryl-CoA and/or 4-hydroxybutyryl-CoA. This internalization of butyrate and reverse metabolic flow of butyrogenic pathway(s) in C. difficile coincides with alterations in toxin production and sporulation. Together, this work highlights butyrate as a signal of a C. difficile inhospitable environment to which C. difficile responds by producing its diarrheagenic toxins and producing environmentally-resistant spores necessary for transmission between hosts. These findings provide foundational data for understanding the molecular and genetic basis of how C. difficile growth is inhibited by butyrate and how butyrate serves as a signal to alter C. difficile virulence in the face of a highly competitive and dynamic gut environment.
IMPORTANCE: The gut microbiome engenders colonization resistance against the diarrheal pathogen Clostridioides difficile but the molecular basis of this colonization resistance is incompletely understood, which hinders the development of novel therapeutic interventions for C. difficile infection (CDI). We investigated how C. difficile responds to butyrate, an end-product of gut microbiome community metabolism which inhibits C. difficile growth. We show that exogenously-produced butyrate is internalized into C. difficile , which inhibits C. difficile growth by interfering with its own butyrate production. This growth inhibition coincides with the expression of virulence-related genes. Future work to disentangle the molecular mechanisms underlying these growth and virulence phenotypes will likely lead to new strategies to restrict C. difficile growth in the gut and minimize its pathogenesis during CDI.

DOI: https://doi.org/10.1101/2023.07.06.548018
Arthritis Res Ther. 2023 Jul 19. 25(1): 121

Sirt3 improves monosodium urate crystal-induced inflammation by suppressing Acod1 expression.

Linxi Lv, Hui Jiang, Dianze Song, Xiaoqin Zhou, Feng Chen, Long Ren, Yongen Xie, Mei Zeng.

   BACKGROUND: Previous studies have revealed that Sirt3 deficiency is associated with several inflammatory responses. The purpose of this study is to investigate the role and potential molecular mechanisms of Sirt3 in the inflammation induced by monosodium urate (MSU) crystals.
METHODS: The Sirt3 expression level in the peripheral blood mononuclear cells (PBMCs) of patients with gout was measured. Function and molecular mechanism of Sirt3 in MSU crystal-induced inflammation were investigated in bone marrow-derived macrophages (BMDMs), C57BL/6 mouse, and Sirt3-/- mouse.
RESULTS: Sirt3 expression was decreased in the PBMCs of patients with gout. Sirt3 agonist (Viniferin) inhibited the acetylation levels of mitochondrial proteins including the SOD2 protein. RNA sequencing, bio-informatics analysis, RT-PCR, and Western blot demonstrated that Sirt3 could suppress the expression of Acod1 (Irg1), which plays an important role in gout. In BMDMs treated with palmitic acid (C16:0) plus MSU crystals, Acod1 knockdown repressed mitochondrial reactive oxygen species (mtROS) over-production, macrophage migration, and mitochondrial fragmentation, and Acod1 improved AMPK activity. The over-expression of Acod1 did not significantly affect the level of itaconic acid, but greatly decreased the levels of some important intermediate metabolites of the tricarboxylic acid (TCA) cycle. These data indicate that Acod1 exerts a pro-inflammatory role in MSU crystal-induced inflammation and is independent of the metabolic level of itaconic acid. Sirt3 deficiency exacerbates inflammatory response induced by MSU crystals in vitro and in vivo.
CONCLUSION: The current study has shown that Sirt3 can alleviate the MSU crystal-induced inflammation by inhibiting the expression of Acod1.

Keywords:  Acod1; MSU crystals; SOD2 acetylation level; Sirt3; TCA cycle

DOI:  https://doi.org/10.1186/s13075-023-03107-6
Mol Metab. 2023 Jul 17. pii: S2212-8778(23)00113-8. [Epub ahead of print] 101779

Pregnane X receptor activation remodels glucose metabolism to promote NAFLD development in obese mice.

Mikko Karpale, Outi Kummu, Olli Kärkkäinen, Marko Lehtonen, Juha Näpänkangas, Uta M Herfurth, Albert Braeuning, Jaana Rysä, Jukka Hakkola.

   OBJECTIVE: Both obesity and exposure to chemicals may induce non-alcoholic fatty liver disease (NAFLD). Pregnane X Receptor (PXR) is a central target of metabolism disrupting chemicals and disturbs hepatic glucose and lipid metabolism. We hypothesized that the metabolic consequences of PXR activation may be modified by existing obesity and associated metabolic dysfunction.
METHODS: Wildtype and PXR knockout male mice were fed high-fat diet to induce obesity and metabolic dysfunction. PXR was activated with pregnenolone-16α-carbonitrile. Glucose metabolism, hepatosteatosis, insulin signaling, glucose uptake, liver glycogen, plasma and liver metabolomics, and liver, white adipose tissue, and muscle transcriptomics were investigated.
RESULTS: PXR activation aggravated obesity-induced liver steatosis by promoting lipogenesis and inhibiting fatty acid disposal. Accordingly, hepatic insulin sensitivity was impaired and circulating alanine aminotransferase level increased. Lipid synthesis was facilitated by increased liver glucose uptake and utilization of glycogen reserves resulting in dissociation of hepatosteatosis and hepatic insulin resistance from the systemic glucose tolerance and insulin sensitivity. Furthermore, glucagon-induced hepatic glucose production was impaired. PXR deficiency did not protect from the metabolic manifestations of obesity, but the liver transcriptomics and metabolomics profiling suggest diminished activation of inflammation and less prominent changes in the overall metabolite profile.
CONCLUSIONS: Obesity and PXR activation by chemical exposure have a synergistic effect on NAFLD development. To support liver fat accumulation the PXR activation reorganizes glucose metabolism that seemingly improves systemic glucose metabolism. This implies that obese individuals, already predisposed to metabolic diseases, may be more susceptible to harmful metabolic effects of PXR-activating drugs and environmental chemicals.

Keywords:  PXR; endocrine disrupting chemicals; glycogen; insulin resistance; steatosis

DOI:  https://doi.org/10.1016/j.molmet.2023.101779
Eur J Nutr. 2023 Jul 17.

Vitamin D status modulates innate immune responses and metabolomic profiles following acute prolonged cycling.

Arwel W Jones, Adrian Mironas, Luis A J Mur, Manfred Beckmann, Rhys Thatcher, Glen Davison.

   PURPOSE: The influence of vitamin D status on exercise-induced immune dysfunction remains unclear. The aim of this study was to investigate the effects of vitamin D status (circulating 25(OH)D) on innate immune responses and metabolomic profiles to prolonged exercise.
METHODS: Twenty three healthy, recreationally active males (age 25 ± 7 years; maximal oxygen uptake [[Formula: see text]max] 56 ± 9 mL·kg-1·min-1), classified as being deficient (n = 7) or non-deficient n = 16) according to plasma concentrations of 25(OH)D, completed 2.5 h of cycling at 15% Δ (~ 55-60% [Formula: see text]max). Venous blood and unstimulated saliva samples were obtained before and after exercise.
RESULTS: Participants with deficient plasma 25(OH)D on average had lower total lymphocyte count (mean difference [95% confidence interval], 0.5 cells × 109 L [0.1, 0.9]), p = 0.013) and greater neutrophil:lymphocyte ratio (1.3 cells × 109 L, [0.1, 2.5], p = 0.033). The deficient group experienced reductions from pre-exercise to 1 h post-exercise (- 43% [- 70, - 15], p = 0.003) in bacterial stimulated elastase in blood neutrophils compared to non-deficient participants (1% [- 20, 21], p = 1.000) Multivariate analyses of plasma metabolomic profiles showed a clear separation of participants according to vitamin D status. Prominent sources of variation between groups were purine/pyrimidine catabolites, inflammatory markers (linoleic acid pathway), lactate and tyrosine/adrenaline.
CONCLUSION: These findings provide evidence of the influence of vitamin D status on exercise-induced changes in parameters of innate immune defence and metabolomic signatures such as markers of inflammation and metabolic stress.

Keywords:  25-Hydroxyvitamin D; Immunity; Inflammation; Metabolomics; Neutrophil; Stress

DOI:  https://doi.org/10.1007/s00394-023-03181-1
Semin Immunol. 2023 Jul 18. pii: S1044-5323(23)00099-4. [Epub ahead of print]69 101808

Mitochondria during T cell aging.

Jose Ignacio Escrig-Larena, Sandra Delgado-Pulido, María Mittelbrunn.

  Mitochondrial dysfunction is a hallmark of aging that contributes to inflammaging. It is characterized by alterations of the mitochondrial DNA, reduced respiratory capacity, decreased mitochondrial membrane potential and increased reactive oxygen species production. These primary alterations disrupt other interconnected and important mitochondrial-related processes such as metabolism, mitochondrial dynamics and biogenesis, mitophagy, calcium homeostasis or apoptosis. In this review, we gather the current knowledge about the different mitochondrial processes which are altered during aging, with special focus on their contribution to age-associated T cell dysfunction and inflammaging.

Keywords:  Aging; Apoptosis; Calcium homeostasis; Inflammaging; Lymphocyte; Mitochondria; Mitochondrial dynamics; Mitokines; Mitophagy; MtDNA; ROS; T cells

DOI:  https://doi.org/10.1016/j.smim.2023.101808
Res Sq. 2023 Jul 06. pii: rs.3.rs-3112286. [Epub ahead of print]

An enteroendocrine-microbial axis in the large intestine controls host metabolism.

Ezra Burstein, Shuai Tan, Jacobo Santolaya, Tiffany Wright, Qi Liu, Teppei Fujikawa, Sensen Chi, Colin Bergstrom, Adam Lopez, Qing Chen, Goncalo Vale, Jeffrey McDonald, Da Jia, Joel Elmquist, Luis Sifuentes-Dominguez.

Nutrient handling is an essential function of the gastrointestinal tract. Most nutrient absorption occurs in the small intestine and is coordinated by hormone-producing intestinal epithelial cells known as enteroendocrine cells (EECs). In contrast, the colon mostly reclaims water and electrolytes, and handles the influx of microbially-derived metabolites, including short chain fatty acids (SCFA). Hormonal responses of small intestinal EECs have been extensively studied but much less in known about the role of colonic EECs in metabolic regulation. To address this core question, we investigated a mouse model deficient in colonic EECs. We found that colonic EEC deficiency leads to hyperphagia and obesity. Surprisingly, colonic EEC deficiency results in altered microbiota composition and metabolism, which we found through antibiotic treatment and transfer to germ free recipients, to be both necessary and sufficient for the development of obesity. Moreover, studying stool and blood metabolomes, we found that differential glutamate production by intestinal microbiota corresponds to increase appetite due to EEC loss. Finally, we show that colonic glutamate administration can directly increase food intake and activate appetite centers in the central nervous system. These observations shed light on an unanticipated host-microbiota axis in the colon, part of a larger gut-brain axis, that regulates host metabolism and body weight.

DOI: https://doi.org/10.21203/rs.3.rs-3112286/v1
Cell Rep. 2023 Jul 19. pii: S2211-1247(23)00774-X. [Epub ahead of print]42(8): 112763

Kynurenine monooxygenase regulates inflammation during critical illness and recovery in experimental acute pancreatitis.

Alastair J Hayes, Xiaozhong Zheng, James O'Kelly, Lucile P A Neyton, Natalia A Bochkina, Iain Uings, John Liddle, J Kenneth Baillie, George Just, Margaret Binnie, Natalie Z M Homer, Toby B J Murray, James Baily, Kris McGuire, Christos Skouras, O James Garden, Scott P Webster, John P Iredale, Sarah E M Howie, Damian J Mole.

  Kynurenine monooxygenase (KMO) blockade protects against multiple organ failure caused by acute pancreatitis (AP), but the link between KMO and systemic inflammation has eluded discovery until now. Here, we show that the KMO product 3-hydroxykynurenine primes innate immune signaling to exacerbate systemic inflammation during experimental AP. We find a tissue-specific role for KMO, where mice lacking Kmo solely in hepatocytes have elevated plasma 3-hydroxykynurenine levels that prime inflammatory gene transcription. 3-Hydroxykynurenine synergizes with interleukin-1β to cause cellular apoptosis. Critically, mice with elevated 3-hydroxykynurenine succumb fatally earlier and more readily to experimental AP. Therapeutically, blockade with the highly selective KMO inhibitor GSK898 rescues the phenotype, reducing 3-hydroxykynurenine and protecting against critical illness and death. Together, our findings establish KMO and 3-hydroxykynurenine as regulators of inflammation and the innate immune response to sterile inflammation. During critical illness, excess morbidity and death from multiple organ failure can be rescued by systemic KMO blockade.

Keywords:  3-hydroxykynurenine; CP: Metabolism; acute pancreatitis; critical illness; kynurenine 3-monooxygenase; metabolomics; multiple organ failure; transcriptome

DOI:  https://doi.org/10.1016/j.celrep.2023.112763
Inflamm Bowel Dis. 2023 Jul 15. pii: izad132. [Epub ahead of print]

Excessive Mitochondrial Fission Suppresses Mucosal Repair by Impairing Butyrate Metabolism in Colonocytes.

Shi-Chen Fu, Jun-Yan Qu, Li-Xiang Li, Xiao-Xiao Yang, Yan-Qing Li, Xiu-Li Zuo.

   BACKGROUND: Mucosal healing is one of the principal therapeutic targets for ulcerative colitis (UC). Mitochondria are dynamic organelles that undergo constant fusion and fission; however, the process that is most conducive to mucosal healing remains unclear. This study investigated the role of mitochondrial fission in mucosal healing in UC patients.
METHODS: Quantitative polymerase chain reaction, Western blotting, and immunostaining were used to detect mitochondrial fission in UC patients and a dextran sulfate sodium-induced colitis model. Colonic organoids were used to investigate the role of mitochondrial fission in butyrate metabolism. Enzyme activity assays were performed to identify the key proteins involved in this mechanism.
RESULTS: It was found that inhibition of mitochondrial fission promoted mucosal healing in mice and that there was an increase in mitochondrial fission in colonic epithelial cells of UC patients. Excessive fission inhibits stem cell proliferation by impairing butyrate metabolism in colonic organoids. The mitochondrial fission antagonist P110 failed to promote mucosal healing in antibiotic-treated mice, and the addition of exogenous butyrate reversed this effect. Increased butyrate exposure in the colonic stem cell niche has also been observed in UC patients. Mechanistically, enzyme activity assays on colonic organoids revealed that excessive fission inhibits mitochondrial acetoacetyl-CoA thiolase activity via reactive oxygen species.
CONCLUSIONS: Collectively, these data indicate that excessive mitochondrial fission suppresses mucosal repair by inhibiting butyrate metabolism and provides a potential target for mucosal healing in patients with ulcerative colitis.

Keywords:  butyrate metabolism; mitochondrial fission; mucosal healing; ulcerative colitis

DOI:  https://doi.org/10.1093/ibd/izad132
J Orthop Translat. 2023 May;40 92-103

Metformin improves fibroblast metabolism and ameliorates arthrofibrosis in rats.

Zhenglin Zhu, Shengqiang Gao, Hui Zhu, Yi Chen, Dandong Wu, Zhiyu Chen, Yanran Huang, Xiangdong Wu, Ning Hu, Di Chen, Wei Huang, Hong Chen.

   Background: Emerging studies have suggested an essential role of fibroblast metabolic reprogramming in the pathogenesis of arthrofibrosis. The metabolic modulator metformin appears to be a therapeutic candidate for fibrotic disorders. However, whether metformin could alleviate arthrofibrosis has not been defined. In this study we have determined if treatment with metformin has beneficial effect on arthrofibrosis and its underlying mechanism.
Methods: Articular capsule samples were collected from patients with/without arthrofibrosis to perform gene and protein expression analysis. Arthrofibrosis animal model was established to examine the anti-fibrotic effect of metformin. Cell culture experiments were conducted to determine the mechanism by which metformin inhibits fibroblast activation.
Results: We found that glycolysis was upregulated in human fibrotic articular capsules. In an arthrofibrosis animal model, intra-articular injection of metformin mitigated inflammatory reactions, downregulated expression of both fibrotic and glycolytic markers, improved range of motion (ROM) of the joint, and reduced capsular fibrosis and thickening. At the cellular level, metformin inhibited the activation of fibroblasts and mitigated the abundant influx of glucose into activated fibroblasts. Interestingly, metformin prompted a metabolic shift from oxidative phosphorylation to aerobic glycolysis in activated fibroblasts, resulting in the anti-fibrotic effect of metformin.
Conclusion: Metformin decreased glycolysis, causing a metabolic shift toward aerobic glycolysis in activated fibroblasts and has beneficial effect on the treatment of arthrofibrosis.The translational potential of this article: The findings of this study demonstrated the therapeutic effect of metformin on arthrofibrosis and defined novel targets for the treatment of articular fibrotic disorders.

Keywords:  Arthrofibrosis; Fibroblast; Glycolysis; Metabolic reprogramming; Metformin

DOI:  https://doi.org/10.1016/j.jot.2023.05.011
Cancer Med. 2023 Jul 19.

FDG uptake reflects an immune-enriched subtype of thyroid cancer: Clinical implications of imaging-based molecular characterization.

Hoon Young Suh, Hongyoon Choi, Sun Wook Cho, Jin Chul Paeng, Gi Jeong Cheon, Young Joo Park, Keon Wook Kang.

   INTRODUCTION: Iodine and FDG uptakes have been established as methods to define the biological properties of thyroid cancer. As various cells in the tumor microenvironment (TME) affect tumor metabolism, we investigated the association between glucose metabolism in thyroid cancer and the TME using transcriptomic analyses.
METHODS: We used F-18 FDG PET and RNA sequencing data of thyroid cancer to find associations between TME cell types and glucose metabolism. In addition, publicly available single-cell RNA sequencing data of papillary thyroid cancer was used to investigate glucose metabolism in cell types of the TME. The correlations between the FDG uptake and biological properties of the TME, including glucose metabolism and tumor differentiation score (TDS) were evaluated. Estimation of the proportions of immune and cancer cells (EPIC) was performed. The biological properties of each cell type were also assessed in the single-cell RNA sequencing data.
RESULTS: FDG uptake showed a positive correlation with the enrichment score of macrophages and glycolysis activity. In single-cell RNA sequencing, immune cells had both high glucose transporters (GLUTs) and glycolysis signatures, while thyrocytes including cancer cells showed relatively low GLUTs and glycolysis signatures, suggesting that FDG uptake mainly occurred in immune cells of the TME. Moreover, the high GLUTs of myeloid cells were negatively associated with TDS.
CONCLUSIONS: Our findings suggest that thyroid cancer with high FDG uptake can be mediated by enriched immune cells of the TME. We suggest that FDG uptake in thyroid cancer could be a marker for the immune-rich type and provide clinical implications for treatment stratification.

Keywords:  2-deoxy-2-fluoro-D-glucose; glucose transport proteins; glycolysis; thyroid neoplasms; tumor microenvironment

DOI:  https://doi.org/10.1002/cam4.6350
Sci Adv. 2023 Jul 21. 9(29): eadg2697

d-lactate modulates M2 tumor-associated macrophages and remodels immunosuppressive tumor microenvironment for hepatocellular carcinoma.

Shulan Han, Xueying Bao, Yifang Zou, Lingzhi Wang, Yutong Li, Leilei Yang, Anqi Liao, Xuemei Zhang, Xin Jiang, Di Liang, Yun Dai, Qing-Chuan Zheng, Zhuo Yu, Jianfeng Guo.

The polarization of tumor-associated macrophages (TAMs) from M2 to M1 phenotype demonstrates great potential for remodeling the immunosuppressive tumor microenvironment (TME) of hepatocellular carcinoma (HCC). d-lactate (DL; a gut microbiome metabolite) acts as an endogenous immunomodulatory agent that enhances Kupffer cells for clearance of pathogens. In this study, the potential of DL for transformation of M2 TAMs to M1 was confirmed, and the mechanisms underlying such polarization were mainly due to the modulation of phosphatidylinositol 3-kinase/protein kinase B pathway. A poly(lactide-co-glycolide) nanoparticle (NP) was used to load DL, and the DL-loaded NP was modified with HCC membrane and M2 macrophage-binding peptide (M2pep), forming a nanoformulation (DL@NP-M-M2pep). DL@NP-M-M2pep transformed M2 TAMs to M1 and remodeled the immunosuppressive TME in HCC mice, promoting the efficacy of anti-CD47 antibody for long-term animal survival. These findings reveal a potential TAM modulatory function of DL and provide a combinatorial strategy for HCC immunotherapy.

DOI: https://doi.org/10.1126/sciadv.adg2697