bims-imicid 2022-07-31 papers

bims-imicid

Biomed News

on Immunometabolism of infection, cancer and immune-mediated disease

Issue of 2022–07–31
twenty papers selected by
Dylan Ryan, University of Cambridge

Rapid GPR183-mediated recruitment of eosinophils to the lung after Mycobacterium tuberculosis infection.
Transcription factor EB coordinates environmental cues to regulate T regulatory cells' mitochondrial fitness and function.
Regulation of immune cell metabolism in health and disease: Special focus on T and B cell subsets.
Impaired ketogenesis ties metabolism to T cell dysfunction in COVID-19.
Pyruvate Supports RET-Dependent Mitochondrial ROS Production to Control Mycobacterium avium Infection in Human Primary Macrophages.
Mitochondrial control of inflammation.
Metabolic reprogramming consequences of sepsis: adaptations and contradictions.
Breathe In, Breathe Out: Metabolic Regulation of Lung Macrophages in Host Defense Against Bacterial Infection.
Pyruvate Metabolism Enables Antitumor Succinate Signaling in CD8+ T Cells.
T cell phenotype switching in autoimmune disorders: Clinical significance of targeting metabolism.
Metabolic impact of adipose tissue macrophages in the early postnatal life.
Reprogramming of glutamine metabolism and its impact on immune response in the tumor microenvironment.
P2 Receptors: Novel Disease Markers and Metabolic Checkpoints in Immune Cells.
Metabolic Reprogramming Induces Macrophage Polarization in the Tumor Microenvironment.
IFN-γ-independent control of M. tuberculosis requires CD4 T cell-derived GM-CSF and activation of HIF-1α.
Microbial short-chain fatty acids: a strategy to tune adoptive T cell therapy.
The metabolic nature of inflammatory bowel diseases.
Downregulation of TCF1 in HIV Infection Impairs T-cell Proliferative Capacity by Disrupting Mitochondrial Function.
An Integrated Transcriptomics and Lipidomics Analysis Reveals That Ergosterol Is Required for Host Defense Against Bacterial Infection in Drosophila.
Ornithine Decarboxylase in Gastric Epithelial Cells Promotes the Immunopathogenesis of Helicobacter pylori Infection.

Cell Rep. 2022 Jul 26. pii: S2211-1247(22)00953-6. [Epub ahead of print]40(4): 111144

Rapid GPR183-mediated recruitment of eosinophils to the lung after Mycobacterium tuberculosis infection.

Tuberculosis Imaging Program

  Influx of eosinophils into the lungs is typically associated with type II responses during allergy and fungal and parasitic infections. However, we previously reported that eosinophils accumulate in lung lesions during type I inflammatory responses to Mycobacterium tuberculosis (Mtb) in humans, macaques, and mice, in which they support host resistance. Here we show eosinophils migrate into the lungs of macaques and mice as early as one week after Mtb exposure. In mice this influx is CCR3 independent and instead requires cell-intrinsic expression of the oxysterol receptor GPR183, which is highly expressed on human and macaque eosinophils. Murine eosinophils interact directly with bacilli-laden alveolar macrophages, which upregulate the oxysterol-synthesizing enzyme Ch25h, and eosinophil recruitment is impaired in Ch25h-deficient mice. Our findings show that eosinophils are among the earliest cells from circulation to sense and respond to Mtb infection of alveolar macrophages and reveal a role for GPR183 in the migration of eosinophils into lung tissue.

Keywords:  CCR3; CP: Immunology; CP: Microbiology; Ch25h; GPR183; Mycobacterium tuberculosis; NHP; alveolar macrophages; bacterial infection; eosinophils; eotaxin; granulocytes; lung; neutrophils; nonhuman primate; oxysterols; rhesus macaque

DOI:  https://doi.org/10.1016/j.celrep.2022.111144
Proc Natl Acad Sci U S A. 2022 Aug 02. 119(31): e2205469119

Transcription factor EB coordinates environmental cues to regulate T regulatory cells' mitochondrial fitness and function.

Minghui Xia, Cai Zhang, Yufei Chen, Xiujuan Zhao, Si Zhang, Yang Liu, You Cai, Zhengping Wei, Qiuyang Du, Wenting Yu, Chun Zhou, Hongjun Xiao, Guihua Wang, Xiang Cheng, Heng Mei, Arian Laurence, Jing Wang, Yu Hu, Huabin Li, Xiang-Ping Yang.

  T regulatory (Treg) cells are essential for self-tolerance whereas they are detrimental for dampening the host anti-tumor immunity. How Treg cells adapt to environmental signals to orchestrate their homeostasis and functions remains poorly understood. Here, we identified that transcription factor EB (TFEB) is induced by host nutrition deprivation or interleukin (IL)-2 in CD4+ T cells. The loss of TFEB in Treg cells leads to reduced Treg accumulation and impaired Treg function in mouse models of cancer and autoimmune disease. TFEB intrinsically regulates genes involved in Treg cell differentiation and mitochondria function while it suppresses expression of proinflammatory cytokines independently of its established roles in autophagy. This coordinated action is required for mitochondria integrity and appropriate lipid metabolism in Treg cells. These findings identify TFEB as a critical regulator for orchestrating Treg generation and function, which may contribute to the adaptive responses of T cells to local environmental cues.

Keywords:  Myc; TFEB; Treg; mTORC1; mitochondrial

DOI:  https://doi.org/10.1073/pnas.2205469119
Cell Biol Int. 2022 Jul 28.

Regulation of immune cell metabolism in health and disease: Special focus on T and B cell subsets.

Sayan Chakraborty, Poulomi Khamaru, Arindam Bhattacharyya.

  Metabolism is a dynamic process and keeps changing from time to time according to the demand of a particular cell to meet its bio-energetic requirement. Different immune cells rely on distinct metabolic programs which allow the cell to balance its requirements for energy, molecular biosynthesis, and effector activity. In the aspect of infection and cancer immunology, effector T and B cells get exhausted and help tumor cells to evade immunosurveillance. On the other hand, T cells become hyperresponsive in the scenario of autoimmune diseases. In this article, we have explored the uniqueness and distinct metabolic features of key CD4+ T and B helper cell subsets, CD4+ T, B regulatory cell subsets and CD8+ T cells regarding health and disease. Th1 cells rely on glycolysis and glutaminolysis; inhibition of these metabolic pathways promotes Th1 cells in Treg population. However, Th2 cells are also dependent on glycolysis but an abundance of lactate within TME shifts their metabolic dependency to fatty acid metabolism. Th17 cells depend on HIF-1α mediated glycolysis, ablation of HIF-1α reduces Th17 cells but enhance Treg population. In contrast to effector T cells which are largely dependent on glycolysis for their differentiation and function, Treg cells mainly rely on FAO for their function. Therefore, it is of utmost importance to understand the metabolic fates of immune cells and how it facilitates their differentiation and function for different disease models. Targeting metabolic pathways to restore the functionality of immune cells in diseased conditions can lead to potent therapeutic measures.

Keywords:  autoimmune disorders; cancer; germinal center; immune cell regulation; infectious diseases; metabolic reprogramming

DOI:  https://doi.org/10.1002/cbin.11867
Nature. 2022 Jul 28.

Impaired ketogenesis ties metabolism to T cell dysfunction in COVID-19.

Bonn COVIMMUNE Consortium

Anorexia and fasting are host adaptations to acute infection, inducing a metabolic switch towards ketogenesis and the production of ketone bodies, including β-hydroxybutyrate (BHB) 1-6. However, whether ketogenesis metabolically influences the immune response in pulmonary infections remains unclear. Here we report impaired production of BHB in humans with SARS-CoV-2-induced but not influenza-induced acute respiratory distress syndrome (ARDS). CD4+ T cell function is impaired in COVID-19 and BHB promotes both survival and production of Interferon-γ from CD4+ T cells. Using metabolic tracing analysis, we uncovered that BHB provides an alternative carbon source to fuel oxidative phosphorylation (OXPHOS) and the production of bioenergetic amino acids and glutathione, which is important for maintaining the redox balance. T cells from patients with SARS-CoV-2-induced ARDS were exhausted and skewed towards glycolysis, but can be metabolically reprogrammed by BHB to perform OXPHOS, thereby increasing their functionality. Finally, we demonstrate that ketogenic diet (KD) and delivery of BHB as ketone ester drink restores CD4+ T cell metabolism and function in respiratory infections, ultimately reducing the mortality of SARS-CoV-2 infected mice. Altogether, our data reveal BHB as alternative carbon source promoting T cell responses in pulmonary viral infections, highlighting impaired ketogenesis as a potential confounder of severe COVID-19.

DOI: https://doi.org/10.1038/s41586-022-05128-8
Front Immunol. 2022 ;13 891475

Pyruvate Supports RET-Dependent Mitochondrial ROS Production to Control Mycobacterium avium Infection in Human Primary Macrophages.

Lisa Marie Røst, Claire Louet, Per Bruheim, Trude Helen Flo, Alexandre Gidon.

  Macrophages deploy a variety of antimicrobial programs to contain mycobacterial infection. Upon activation, they undergo extensive metabolic reprogramming to meet an increase in energy demand, but also to support immune effector functions such as secretion of cytokines and antimicrobial activities. Here, we report that mitochondrial import of pyruvate is linked to production of mitochondrial ROS and control of Mycobacterium avium (M. avium) infection in human primary macrophages. Using chemical inhibition, targeted mass spectrometry and single cell image analysis, we showed that macrophages infected with M. avium switch to aerobic glycolysis without any major imbalances in the tricarboxylic acid cycle volume or changes in the energy charge. Instead, we found that pyruvate import contributes to hyperpolarization of mitochondria in infected cells and increases production of mitochondrial reactive oxygen species by the complex I via reverse electron transport, which reduces the macrophage burden of M. avium. While mycobacterial infections are extremely difficult to treat and notoriously resistant to antibiotics, this work stresses out that compounds specifically inducing mitochondrial reactive oxygen species could present themself as valuable adjunct treatments.

Keywords:  Mycobacterium avium infection; glycolysis; human primary macrophages; innate immunity; mitochondrial ROS; mitochondrial pyruvate; pyruvate; reverse electron transport

DOI:  https://doi.org/10.3389/fimmu.2022.891475
Nat Rev Immunol. 2022 Jul 25.

Mitochondrial control of inflammation.

Saverio Marchi, Emma Guilbaud, Stephen W G Tait, Takahiro Yamazaki, Lorenzo Galluzzi.

Numerous mitochondrial constituents and metabolic products can function as damage-associated molecular patterns (DAMPs) and promote inflammation when released into the cytosol or extracellular milieu. Several safeguards are normally in place to prevent mitochondria from eliciting detrimental inflammatory reactions, including the autophagic disposal of permeabilized mitochondria. However, when the homeostatic capacity of such systems is exceeded or when such systems are defective, inflammatory reactions elicited by mitochondria can become pathogenic and contribute to the aetiology of human disorders linked to autoreactivity. In addition, inefficient inflammatory pathways induced by mitochondrial DAMPs can be pathogenic as they enable the establishment or progression of infectious and neoplastic disorders. Here we discuss the molecular mechanisms through which mitochondria control inflammatory responses, the cellular pathways that are in place to control mitochondria-driven inflammation and the pathological consequences of dysregulated inflammatory reactions elicited by mitochondrial DAMPs.

DOI: https://doi.org/10.1038/s41577-022-00760-x
Cell Mol Life Sci. 2022 Jul 29. 79(8): 456

Metabolic reprogramming consequences of sepsis: adaptations and contradictions.

Jingjing Liu, Gaosheng Zhou, Xiaoting Wang, Dawei Liu.

  During sepsis, the importance of alterations in cell metabolism is underappreciated. The cellular metabolism, which has a variable metabolic profile in different cells and disease stages, is largely responsible for the immune imbalance and organ failure associated with sepsis. Metabolic reprogramming, in which glycolysis replaces OXPHOS as the main energy-producing pathway, is both a requirement for immune cell activation and a cause of immunosuppression. Meanwhile, the metabolites produced by OXPHOS and glycolysis can act as signaling molecules to control the immune response during sepsis. Sepsis-induced "energy shortage" leads to stagnated cell function and even organ dysfunction. Metabolic reprogramming can alleviate the energy crisis to some extent, enhance host tolerance to maintain cell survival functions, and ultimately increase the adaptation of cells during sepsis. However, a switch from glycolysis to OXPHOS is essential for restoring cell function. This review summarized the crosstalk between metabolic reprogramming and immune cell activity as well as organ function during sepsis, discussed the benefits and drawbacks of metabolic reprogramming to show the contradictions of metabolic reprogramming during sepsis, and assessed the feasibility of treating sepsis through targeted metabolism. Using metabolic reprogramming to achieve metabolic homeostasis could be a viable therapy option for sepsis.

Keywords:  Glycolysis; Immunosuppression; MODS; Metabolic reprogramming; OXPHOS; Sepsis; Tolerance

DOI:  https://doi.org/10.1007/s00018-022-04490-0
Front Cell Infect Microbiol. 2022 ;12 934460

Breathe In, Breathe Out: Metabolic Regulation of Lung Macrophages in Host Defense Against Bacterial Infection.

J Tucker Andrews, Daniel E Voth, Stanley Ching-Cheng Huang, Lu Huang.

  Lung macrophages are substantially distinct from other tissue-resident macrophages. They act as frontier sentinels of the alveolar-blood interface and are constantly exposed to various pathogens. Additionally, they precisely regulate immune responses under homeostatic and pathological conditions to curtail tissue damage while containing respiratory infections. As a highly heterogeneous population, the phenotypes and functions of lung macrophages with differing developmental ontogenies are linked to both intrinsic and extrinsic metabolic processes. Importantly, targeting these metabolic pathways greatly impacts macrophage functions, which in turn leads to different disease outcomes in the lung. In this review, we will discuss underlying metabolic regulation of lung macrophage subsets and how metabolic circuits, together with epigenetic modifications, dictate lung macrophage function during bacterial infection.

Keywords:  bacterial infection; immunometabolism; inflammation; lung macrophages; trained immunity

DOI:  https://doi.org/10.3389/fcimb.2022.934460
Cancer Discov. 2022 Jul 29. OF1

Pyruvate Metabolism Enables Antitumor Succinate Signaling in CD8+ T Cells.

Tumor-derived lactate disrupts pyruvate metabolism and cytotoxic function of antitumor CD8+ T cells.

DOI: https://doi.org/10.1158/2159-8290.CD-RW2022-133
Clin Transl Med. 2022 Jul;12(7): e898

T cell phenotype switching in autoimmune disorders: Clinical significance of targeting metabolism.

Matteo Barberis, Alejandra Rojas López.

  Increasing efforts points to the understanding of how to maximize the capabilities of the adaptive immune system to fight against the development of immune and inflammatory disorders. Here we focus on the role of T cells as immune cells which subtype imbalance may lead to disease onset. Specifically, we propose that autoimmune disorders may develop as a consequence of a metabolic imbalance that modulates switching between T cell phenotypes. We highlight a Systems Biology strategy that integrates computational metabolic modelling with experimental data to investigate the metabolic requirements of T cell phenotypes, and to predict metabolic genes that may be targeted in autoimmune inflammatory diseases. Thus, we propose a new perspective of targeting T cell metabolism to modulate the immune response and prevent T cell phenotype imbalance, which may help to repurpose already existing drugs targeting metabolism for therapeutic treatment.

Keywords:  Systems Biology; T cell phenotypes; autoimmune disorders; computational modelling; metabolism; multi-scale modelling; phenotype switching

DOI:  https://doi.org/10.1002/ctm2.898
J Leukoc Biol. 2022 Jul 28.

Metabolic impact of adipose tissue macrophages in the early postnatal life.

Tamás Röszer.

  Adipose tissue macrophages (ATMs) play key roles in metabolic inflammation, insulin resistance, adipose tissue fibrosis, and immune disorders associated with obesity. Research on ATM biology has mostly been conducted in the setting of adult obesity, since adipocyte hypertrophy is associated with a significant increase in ATM number. Signals that control ATM activation toward a proinflammatory or a proresolving phenotype also determine the developmental program and lipid metabolism of adipocytes after birth. ATMs are present at birth and actively participate in the synthesis of mediators, which induce lipolysis, mitobiogenesis, and mitochondrial uncoupling in adipocytes. ATMs in the newborn and the infant promote a lipolytic and fatty acid oxidizing adipocyte phenotype, which is essential to support the lipid-fueled metabolism, to maintain nonshivering thermogenesis and counteract an excessive adipose tissue expansion. Since adipose tissue metabolism in the early postnatal life determines obesity status in adulthood, early-life ATM functions may have a life-long impact.

Keywords:  inflammation; macrophage; obesity; pediatric adiposity

DOI:  https://doi.org/10.1002/JLB.3MR0722-201R
Cell Commun Signal. 2022 Jul 27. 20(1): 114

Reprogramming of glutamine metabolism and its impact on immune response in the tumor microenvironment.

Guofeng Ma, Zhilei Zhang, Peng Li, Zhao Zhang, Manqin Zeng, Zhijuan Liang, Dan Li, Liping Wang, Yuanbin Chen, Ye Liang, Haitao Niu.

  Metabolic reprogramming and immune escape play a major role in tumorigenesis. Increasing number of studies have shown that reprogramming of glutamine metabolism is a putative determinant of the anti-tumor immune response in the tumor microenvironment (TME). Usually, the predatory uptake of glutamine by tumor cells in the TME results in the limited utilization of glutamine by immune cells and affects the anti-tumor immune response. The cell-programmed glutamine partitioning also affects the anti-tumor immune response. However, the reprogramming of glutamine metabolism in tumors modulates immune escape by regulating tumor PD-L1 expression. Likewise, the reprogramming of glutamine metabolism in the immune cells also affects their immune function. Additionally, different types of glutamine metabolism inhibitors extensively regulate the immune cells in the TME while suppressing tumor cell proliferation. Herein, we discuss how metabolic reprogramming of tumor and immune cells regulates anti-tumor immune responses, as well as functional changes in different immune cells in the context of targeting tumor glutamine metabolism, which can better explain the potential of targeting glutamine metabolism in combination with immunotherapy for cancer. Video abstract.

Keywords:  Glutamine metabolism; Glutamine metabolism inhibitors; Immune response; Immunity; Reprogramming; Tumor microenvironment

DOI:  https://doi.org/10.1186/s12964-022-00909-0
Biomolecules. 2022 Jul 14. pii: 983. [Epub ahead of print]12(7):

P2 Receptors: Novel Disease Markers and Metabolic Checkpoints in Immune Cells.

Valentina Vultaggio-Poma, Francesco Di Virgilio.

  Extracellular ATP (eATP) and P2 receptors are novel emerging regulators of T-lymphocyte responses. Cellular ATP is released via multiple pathways and accumulates at sites of tissue damage and inflammation. P2 receptor expression and function are affected by numerous single nucleotide polymorphisms (SNPs) associated with diverse disease conditions. Stimulation by released nucleotides (purinergic signalling) modulates several T-lymphocyte functions, among which energy metabolism. Energy metabolism, whether oxidative or glycolytic, in turn deeply affects T-cell activation, differentiation and effector responses. Specific P2R subtypes, among which the P2X7 receptor (P2X7R), are either up- or down-regulated during T-cell activation and differentiation; thus, they can be considered indexes of activation/quiescence, reporters of T-cell metabolic status and, in principle, markers of immune-mediated disease conditions.

Keywords:  P2 receptors; T cells; T-cell metabolism; extracellular ATP; inflammatory disease; tumour microenvironment

DOI:  https://doi.org/10.3390/biom12070983
Front Immunol. 2022 ;13 840029

Metabolic Reprogramming Induces Macrophage Polarization in the Tumor Microenvironment.

Shilin Wang, Guohong Liu, Yirong Li, Yunbao Pan.

  Macrophages are one of the most important cells in the innate immune system, they are converted into two distinct subtypes with completely different molecular phenotypes and functional features under different stimuli of the microenvironment: M1 macrophages induced by IFN-γ/lipopolysaccharides(LPS) and M2 macrophages induced by IL-4/IL-10/IL-13. Tumor-associated macrophages (TAMs) differentiate from macrophages through various factors in the tumor microenvironment (TME). TAMs have the phenotype and function of M2 macrophages and are capable of secreting multiple cytokines to promote tumor progression. Both tumor cells and macrophages can meet the energy needs for rapid cell growth and proliferation through metabolic reprogramming, so a comprehensive understanding of pro-tumor and antitumor metabolic switches in TAM is essential to understanding immune escape mechanisms. This paper focuses on the functions of relevant signaling pathways and cytokines during macrophage polarization and metabolic reprogramming, and briefly discusses the effects of different microenvironments and macrophage pathogenicity, in addition to describing the research progress of inhibitory drugs for certain metabolic and polarized signaling pathways.

Keywords:  immune escape; macrophage polarization; metabolic reprogramming; tumor microenvironment; tumor-associated macrophages

DOI:  https://doi.org/10.3389/fimmu.2022.840029
PLoS Pathog. 2022 Jul 25. 18(7): e1010721

IFN-γ-independent control of M. tuberculosis requires CD4 T cell-derived GM-CSF and activation of HIF-1α.

Erik Van Dis, Douglas M Fox, Huntly M Morrison, Daniel M Fines, Janet Peace Babirye, Lily H McCann, Sagar Rawal, Jeffery S Cox, Sarah A Stanley.

The prevailing model of protective immunity to tuberculosis is that CD4 T cells produce the cytokine IFN-γ to activate bactericidal mechanisms in infected macrophages. Although IFN-γ-independent CD4 T cell based control of M. tuberculosis infection has been demonstrated in vivo it is unclear whether CD4 T cells are capable of directly activating macrophages to control infection in the absence of IFN-γ. We developed a co-culture model using CD4 T cells isolated from the lungs of infected mice and M. tuberculosis-infected murine bone marrow-derived macrophages (BMDMs) to investigate mechanisms of CD4 dependent control of infection. We found that even in the absence of IFN-γ signaling, CD4 T cells drive macrophage activation, M1 polarization, and control of infection. This IFN-γ-independent control of infection requires activation of the transcription factor HIF-1α and a shift to aerobic glycolysis in infected macrophages. While HIF-1α activation following IFN-γ stimulation requires nitric oxide, HIF-1α-mediated control in the absence of IFN-γ is nitric oxide-independent, indicating that distinct pathways can activate HIF-1α during infection. We show that CD4 T cell-derived GM-CSF is required for IFN-γ-independent control in BMDMs, but that recombinant GM-CSF is insufficient to control infection in BMDMs or alveolar macrophages and does not rescue the absence of control by GM-CSF-deficient T cells. In contrast, recombinant GM-CSF controls infection in peritoneal macrophages, induces lipid droplet biogenesis, and also requires HIF-1α for control. These results advance our understanding of CD4 T cell-mediated immunity to M. tuberculosis, reveal important differences in immune activation of distinct macrophage types, and outline a novel mechanism for the activation of HIF-1α. We establish a previously unknown functional link between GM-CSF and HIF-1α and provide evidence that CD4 T cell-derived GM-CSF is a potent bactericidal effector.

DOI: https://doi.org/10.1371/journal.ppat.1010721
J Immunother Cancer. 2022 Jul;pii: e004147. [Epub ahead of print]10(7):

Microbial short-chain fatty acids: a strategy to tune adoptive T cell therapy.

Priya Rangan, Anna Mondino.

  The gut microbiota and its metabolites have been shown to play a pivotal role in the regulation of metabolic, endocrine and immune functions. Though the exact mechanism of action remains to be fully elucidated, available knowledge supports the ability of microbiota-fermented short-chain fatty acids (SCFAs), such as acetate, propionate, and butyrate, to influence epigenetic and metabolic cascades controlling gene expression, chemotaxis, differentiation, proliferation, and apoptosis in several non-immune and immune cell subsets. While used as preferred metabolic substrates and sources of energy by colonic gut epithelial cells, most recent evidence indicates that these metabolites regulate immune functions, and in particular fine-tune T cell effector, regulatory and memory phenotypes, with direct in vivo consequences on the efficacy of chemotherapy, radiotherapy and immunotherapy. Most recent data also support the use of these metabolites over the course of T cell manufacturing, paving the way for refined adoptive T cell therapy engineering. Here, we review the most recent advances in the field, highlighting in vitro and in vivo evidence for the ability of SCFAs to shape T cell phenotypes and functions.

Keywords:  T-lymphocytes; immunotherapy, adoptive; lymphocyte activation; review

DOI:  https://doi.org/10.1136/jitc-2021-004147
Nat Rev Gastroenterol Hepatol. 2022 Jul 29.

The metabolic nature of inflammatory bowel diseases.

Timon E Adolph, Moritz Meyer, Julian Schwärzler, Lisa Mayr, Felix Grabherr, Herbert Tilg.

Crohn's disease and ulcerative colitis, phenotypically comprising a spectrum of inflammatory bowel diseases (IBDs), spread globally during the westernization of lifestyle and dietary habits over the past few decades. Here, we review experimental and clinical evidence for the metabolic nature of gut inflammation in IBD and delineate distinct parallels to the inflammatory state in metabolic diseases. Experimental evidence indicates that excessive intake of specific macronutrients in a Western diet fuels an inflammatory response in the gut by exploiting sensors of innate immunity and perturbation of gut microbial metabolism. Genetic IBD risk partly affects metabolism and stress signalling of innate immunity, and immunometabolism controls susceptibility to gut inflammation. Epidemiological and clinical studies indicate that specific nutrients in the Western diet pose a risk for the development of IBD and a poor disease course. Translational studies in IBD indicate perturbation of energy metabolism in immune cells and perturbation of gut microbial metabolism, which can be shaped by diet. In turn, dietary restriction by exclusive enteral nutrition induces remission in patients with IBD. Collectively, these studies support a metabolic underpinning of gut inflammation in IBD as described for metabolic inflammation in obesity and related disorders.

DOI: https://doi.org/10.1038/s41575-022-00658-y
Front Microbiol. 2022 ;13 880873

Downregulation of TCF1 in HIV Infection Impairs T-cell Proliferative Capacity by Disrupting Mitochondrial Function.

Hong-Jiao Cai, Jue Shi, Lin-Bo Yin, Jie-Fu Zheng, Ya-Jing Fu, Yong-Jun Jiang, Hong Shang, Zi-Ning Zhang.

   Background: Despite the benefits of antiretroviral therapy (ART) for people with HIV, T-cell dysfunction cannot be fully restored. Metabolic dysregulation is associated with dysfunction of HIV-1-specific T-cells. Exploration of the factors regulating metabolic fitness can help reverse T-cell dysfunction and provide new insights into the underlying mechanism.
Methods: In this study, HIV-infected individuals and HIV-negative control individuals (NCs) were enrolled. T-cell factor (TCF)1 expression in cells was determined by quantitative reverse-transcriptase polymerase chain reaction and flow cytometry. Relevant microarray data from the GEO database were analyzed to explore the underlying mechanism. The effects of TCF1 on T-cell function and metabolic function were assessed in vitro.
Results: TCF7 mRNA expression in peripheral blood mononuclear cells was downregulated in rapid progressors compared with long-term non-progressors individuals and NCs. TCF1 expression on CD4+ and CD8+ T-cells was downregulated in treatment-naïve HIV-infected individuals compared with NCs. Interleukin (IL)2 production and proliferative capacity were impaired in TCF1 knockdown T-cells. Moreover, glycolytic capacity and mitochondrial respiratory function were decreased in TCF1 knockdown T-cells, and depolarized mitochondria were increased in TCF1 knockdown T-cells.
Conclusion: Downregulation of TCF1 in HIV infection impairs T-cell proliferative capacity by disrupting mitochondrial function. These findings highlight the metabolic regulation as a pivotal mechanism of TCF1 in the regulation of T-cell dysfunction.

Keywords:  HIV infection; T-cell factor 1; metabolism; mitochondrial function; proliferative capacity

DOI:  https://doi.org/10.3389/fmicb.2022.880873
Front Immunol. 2022 ;13 933137

An Integrated Transcriptomics and Lipidomics Analysis Reveals That Ergosterol Is Required for Host Defense Against Bacterial Infection in Drosophila.

Zihao Deng, Yanyang Yang, Jiazhen Luo, Biling Zhang, Jiyong Liu, Guanghou Shui, Renjie Jiao, Chuanxian Wei.

  Animals adjust their lipid metabolism states in response to pathogens infection. However, the underlying molecular mechanisms for how lipid metabolism responds to infection remain to be elusive. In this study, we assessed the temporal changes of lipid metabolism profiles during infection by an integrated transcriptomics and lipidomics analysis. Ergosterol is identified to be required for proper host defense to pathogens. Notably, ergosterol level is increased in the hemolymph upon bacterial infection. We show that the increase of ergosterol level by food supplement or genetic depletion of Acsl, a long-chain fatty acid-CoA synthetase, promotes host survival against bacterial challenges. Together, our results suggest a critical role of lipid metabolism adaption in the process of host defense against invading pathogens.

Keywords:  ACSL; Drosophila; ergosterol; innate immunity; lipid metabolism; lipidomics; transcriptomics

DOI:  https://doi.org/10.3389/fimmu.2022.933137
J Immunol. 2022 Jul 27. pii: ji2100795. [Epub ahead of print]

Ornithine Decarboxylase in Gastric Epithelial Cells Promotes the Immunopathogenesis of Helicobacter pylori Infection.

Yvonne L Latour, Johanna C Sierra, Kara M McNamara, Thaddeus M Smith, Paula B Luis, Claus Schneider, Alberto G Delgado, Daniel P Barry, Margaret M Allaman, M Wade Calcutt, Kevin L Schey, M Blanca Piazuelo, Alain P Gobert, Keith T Wilson.

Colonization by Helicobacter pylori is associated with gastric diseases, ranging from superficial gastritis to more severe pathologies, including intestinal metaplasia and adenocarcinoma. The interplay of the host response and the pathogen affect the outcome of disease. One major component of the mucosal response to H. pylori is the activation of a strong but inefficient immune response that fails to control the infection and frequently causes tissue damage. We have shown that polyamines can regulate H. pylori-induced inflammation. Chemical inhibition of ornithine decarboxylase (ODC), which generates the polyamine putrescine from l-ornithine, reduces gastritis in mice and adenocarcinoma incidence in gerbils infected with H. pylori However, we have also demonstrated that Odc deletion in myeloid cells enhances M1 macrophage activation and gastritis. Here we used a genetic approach to assess the specific role of gastric epithelial ODC during H. pylori infection. Specific deletion of the gene encoding for ODC in gastric epithelial cells reduces gastritis, attenuates epithelial proliferation, alters the metabolome, and downregulates the expression of immune mediators induced by H. pylori Inhibition of ODC activity or ODC knockdown in human gastric epithelial cells dampens H. pylori-induced NF-κB activation, CXCL8 mRNA expression, and IL-8 production. Chronic inflammation is a major risk factor for the progression to more severe pathologies associated with H. pylori infection, and we now show that epithelial ODC plays an important role in mediating this inflammatory response.

DOI: https://doi.org/10.4049/jimmunol.2100795