bims-imicid Biomed News
on Immunometabolism of infection, cancer and immune-mediated disease
Issue of 2023‒09‒03
thirty-two papers selected by
Dylan Ryan, University of Cambridge

  1. Nat Microbiol. 2023 Aug 28.
      Cell-intrinsic defences constitute the first line of defence against intracellular pathogens. The guanosine triphosphatase RAB32 orchestrates one such defence response against the bacterial pathogen Salmonella, through delivery of antimicrobial itaconate. Here we show that the Parkinson's disease-associated leucine-rich repeat kinase 2 (LRRK2) orchestrates this defence response by scaffolding a complex between RAB32 and aconitate decarboxylase 1, which synthesizes itaconate from mitochondrial precursors. Itaconate delivery to Salmonella-containing vacuoles was impaired and Salmonella replication increased in LRRK2-deficient cells. Loss of LRRK2 also restored virulence of a Salmonella mutant defective in neutralizing this RAB32-dependent host defence pathway in mice. Cryo-electron tomography revealed tether formation between Salmonella-containing vacuoles and host mitochondria upon Salmonella infection, which was significantly impaired in LRRK2-deficient cells. This positions LRRK2 centrally within a host defence mechanism, which may have favoured selection of a common familial Parkinson's disease mutant allele in the human population.
  2. bioRxiv. 2023 Aug 19. pii: 2023.08.17.553736. [Epub ahead of print]
      Aging of the hematopoietic system promotes various blood, immune and systemic disorders and is largely driven by hematopoietic stem cell (HSC) dysfunction ( 1 ). Autophagy is central for the benefits associated with activation of longevity signaling programs ( 2 ), and for HSC function and response to nutrient stress ( 3,4 ). With age, a subset of HSCs increases autophagy flux and preserves some regenerative capacity, while the rest fail to engage autophagy and become metabolically overactivated and dysfunctional ( 4 ). However, the signals that promote autophagy in old HSCs and the mechanisms responsible for the increased regenerative potential of autophagy-activated old HSCs remain unknown. Here, we demonstrate that autophagy activation is an adaptive survival response to chronic inflammation in the aging bone marrow (BM) niche ( 5 ). We find that inflammation impairs glucose metabolism and suppresses glycolysis in aged HSCs through Socs3-mediated impairment of AKT/FoxO-dependent signaling. In this context, we show that inflammation-mediated autophagy engagement preserves functional quiescence by enabling metabolic adaptation to glycolytic impairment. Moreover, we demonstrate that transient autophagy induction via a short-term fasting/refeeding paradigm normalizes glucose uptake and glycolytic flux and significantly improves old HSC regenerative potential. Our results identify inflammation-driven glucose hypometabolism as a key driver of HSC dysfunction with age and establish autophagy as a targetable node to reset old HSC glycolytic and regenerative capacity.One-Sentence Summary: Autophagy compensates for chronic inflammation-induced metabolic deregulation in old HSCs, and its transient modulation can reset old HSC glycolytic and regenerative capacity.
  3. Nature. 2023 Aug 30.
      Tissue resident memory CD8+ T (TRM) cells offer rapid and long-term protection at sites of reinfection1. Tumour-infiltrating lymphocytes with characteristics of TRM cells maintain enhanced effector functions, predict responses to immunotherapy and accompany better prognoses2,3. Thus, an improved understanding of the metabolic strategies that enable tissue residency by T cells could inform new approaches to empower immune responses in tissues and solid tumours. Here, to systematically define the basis for the metabolic reprogramming supporting TRM cell differentiation, survival and function, we leveraged in vivo functional genomics, untargeted metabolomics and transcriptomics of virus-specific memory CD8+ T cell populations. We found that memory CD8+ T cells deployed a range of adaptations to tissue residency, including reliance on non-steroidal products of the mevalonate-cholesterol pathway, such as coenzyme Q, driven by increased activity of the transcription factor SREBP2. This metabolic adaptation was most pronounced in the small intestine, where TRM cells interface with dietary cholesterol and maintain a heightened state of activation4, and was shared by functional tumour-infiltrating lymphocytes in diverse tumour types in mice and humans. Enforcing synthesis of coenzyme Q through deletion of Fdft1 or overexpression of PDSS2 promoted mitochondrial respiration, memory T cell formation following viral infection and enhanced antitumour immunity. In sum, through a systematic exploration of TRM cell metabolism, we reveal how these programs can be leveraged to fuel memory CD8+ T cell formation in the context of acute infections and enhance antitumour immunity.
  4. Methods Mol Biol. 2024 ;2713 363-376
      Functional reprograming of cells is linked to a process of metabolic rewiring that is adapted for such new functions or microenvironment. Macrophages are present in all tissues and exposed to different microenvironments throughout our body. Profiling energetic metabolism of tissue resident and other heterogeneous populations of macrophages in vitro and ex vivo is technologically very challenging. We have recently developed a method to functionally profile energetic metabolism with single-cell resolution, named SCENITH. This method can be performed rapidly ex vivo and does not require specialized equipment. In this book chapter, we will summarize the tissue processing, the procedure and methods, the analysis and example of results, and a series of frequently asked questions.
    Keywords:  Energetic metabolism; FACS; Flow cytometry; Glycolytic capacity; Immunometabolism; Macrophages; Metabolic dependencies; Mitochondrial dependence; Protein synthesis; SCENITH; Single-cell resolution
  5. bioRxiv. 2023 Aug 18. pii: 2023.08.16.553532. [Epub ahead of print]
      Bacterial infection involves a complex interaction between the pathogen and host where the outcome of infection is not solely determined by pathogen eradication. To identify small molecules that promote host survival by altering the host-pathogen dynamic, we conducted an in vivo chemical screen using zebrafish embryos and found that treatment with 3-hydroxy-kynurenine protects from lethal gram-negative bacterial infection. 3-hydroxy-kynurenine, a metabolite produced through host tryptophan metabolism, has no direct antibacterial activity but enhances host survival by restricting bacterial expansion in macrophages by targeting kainate-sensitive glutamate receptors. These findings reveal new mechanisms by which tryptophan metabolism and kainate-sensitive glutamate receptors function and interact to modulate immunity, with significant implications for the coordination between the immune and nervous systems in pathological conditions.
  6. Cell Rep. 2023 Aug 24. pii: S2211-1247(23)01024-0. [Epub ahead of print]42(9): 113013
      2-Hydroxyglutarate (2HG) is a byproduct of the tricarboxylic acid (TCA) cycle and is readily detected in the tissues of healthy individuals. 2HG is found in two enantiomeric forms: S-2HG and R-2HG. Here, we investigate the differential roles of these two enantiomers in cluster of differentiation (CD)8+ T cell biology, where we find they have highly divergent effects on proliferation, differentiation, and T cell function. We show here an analysis of structural determinants that likely underlie these differential effects on specific α-ketoglutarate (αKG)-dependent enzymes. Treatment of CD8+ T cells with exogenous S-2HG, but not R-2HG, increased CD8+ T cell fitness in vivo and enhanced anti-tumor activity. These data show that S-2HG and R-2HG should be considered as two distinct and important actors in the regulation of T cell function.
    Keywords:  2-hydroxyglutarate; CD8+ T cell function; CD8+ T cell memory; CP: Immunology; adoptive cell transfer; oncometabolites
  7. Br J Dermatol. 2023 Aug 30. pii: ljad305. [Epub ahead of print]
      BACKGROUND: Targeting immunometabolism has shown promise in treating autoimmune and inflammatory conditions. Hidradenitis suppurativa (HS) is a chronic, inflammatory skin disease involving painful lesions in apocrine gland-bearing skin. Therapeutic options for HS are limited and often ineffective, thus there is a pressing need for improved treatments. To date, metabolic dysregulation has not been investigated in HS. Since HS is highly inflammatory, we hypothesise that energy metabolism is dysregulated in these patients. Metformin, the anti-diabetic drug, which is known to impact cellular metabolic and signalling pathways, has been shown to have anti-inflammatory effects in cancer and arthritis. While metformin is not licenced for use in HS, HS patients taking metformin show improved clinical symptoms.METHODS: To assess the effect of metformin in vivo, we compared the immune and metabolic profiles of peripheral blood mononuclear cells (PBMC) of HS patients taking metformin versus those not taking metformin. To examine the effect of metformin treatment ex vivo, we employed a skin explant model on skin biopsies from HS patients not taking metformin, which we cultured with metformin overnight. We used ELISA, multiplex cytokine assays and quantitative RT-PCR to measure inflammatory markers, and Seahorse flux technology and quantitative RT-PCR to assess glucose metabolism.
    RESULTS: We showed that metabolic pathways are dysregulated in the PBMC of HS patients compared to healthy individuals. In the metformin-treated patients, these metabolic pathways were restored, and their PBMC had reduced inflammatory markers following long-term metformin treatment. In the skin explant model, we found that overnight culture with metformin reduced inflammatory cytokines and chemokines and glycolytic genes in lesions and tracts of HS patients. Using in vitro assays, we found that metformin may be inducing these changes via the NLRP3 inflammasome and the AMPK-mTOR pathway, which is linked to glycolysis and protein synthesis.
    CONCLUSIONS: Our study provides insight into the mechanisms of action of metformin in HS. The anti-inflammatory effects of metformin support its use as a therapeutic agent in HS, while its effects on immunometabolism suggest that targeting metabolism is a promising therapeutic option in inflammatory diseases, including HS.
  8. Microbiol Spectr. 2023 Sep 01. e0168723
      While liver inflammation is associated with AIDS, little is known so far about hepatic CD4+ T cells. By using the simian immunodeficiency virus (SIV)-infected rhesus macaque (RM) model, we aimed to characterize CD4+ T cells. The phenotype of CD4+ T cells was assessed by flow cytometry from uninfected (n = 3) and infected RMs, with either SIVmac251 (n = 6) or SHIVSF162p3 (n = 6). After cell sorting of hepatic CD4+ T cells, viral DNA quantification and RNA sequencing were performed.Thus, we demonstrated that liver CD4+ T cells strongly expressed the SIV coreceptor, CCR5. We showed that viremia was negatively correlated with the percentage of hepatic effector memory CD4+ T cells. Consistent with viral sensing, inflammatory and interferon gene transcripts were increased. We also highlighted the presence of harmful CD4+ T cells expressing GZMA and members of TGFB that could contribute to fuel inflammation and fibrosis. Whereas RNA sequencing demonstrated activated CD4+ T cells displaying higher levels of mitoribosome and membrane lipid synthesis transcripts, few genes were related to glycolysis and oxidative phosphorylation, which are essential to sustain activated T cells. Furthermore, we observed lower levels of mitochondrial DNA and higher levels of genes associated with damaged organelles (reticulophagy and mitophagy). Altogether, our data revealed that activated hepatic CD4+ T cells are reprogrammed to lipid metabolism. Thus, strategies aiming to reprogram T cell metabolism with effector function could be of interest for controlling viral infection and preventing liver disorders.IMPORTANCEHuman immunodeficiency virus (HIV) infection may cause liver diseases, associated with inflammation and tissue injury, contributing to comorbidity in people living with HIV. Paradoxically, the contribution of hepatic CD4+ T cells remains largely underestimated. Herein, we used the model of simian immunodeficiency virus (SIV)-infected rhesus macaques to access liver tissue. Our work demonstrates that hepatic CD4+ T cells express CCR5, the main viral coreceptor, and are infected. Viral infection is associated with the presence of inflamed and activated hepatic CD4+ T cells expressing cytotoxic molecules. Furthermore, hepatic CD4+ T cells are reprogrammed toward lipid metabolism after SIV infection. Altogether, our findings shed new light on hepatic CD4+ T cell profile that could contribute to liver injury following viral infection.
    Keywords:  AIDS; CCR5; CD4; PD-1; SIV; autophagy; cytotoxic; ferroptosis; granzyme; lipid; liver; metabolism; viral reservoir
  9. Immunology. 2023 Aug 31.
      Bronchial asthma is a heterogeneous disease characterised by chronic airway inflammation. A variety of immune cells such as eosinophils, mast cells, T lymphocytes, neutrophils and airway epithelial cells are involved in the airway inflammation and airway hyperresponsiveness in asthma pathogenesis, resulting in extensive and variable reversible expiratory airflow limitation. However, the precise molecular mechanisms underlying the allergic immune responses, particularly immunometabolism, remains unclear. Studies have detected enhanced oxidative stress, and abnormal metabolic progresses of glycolysis, fatty acid and amino acid in various immune cells, inducing dysregulation of innate and adaptive immune responses in asthma pathogenesis. Immunometabolism mechanisms contain multiple signalling pathways, providing novel therapy targets for asthma. This review summarises the current knowledge on immunometabolism reprogramming in asthma pathogenesis, as well as potential therapy strategies.
    Keywords:  airway hyperresponsiveness; airway inflammation; airway remodelling; asthma; immune cell; immune response; immunometabolism; metabolic reprogramming
  10. Immunology. 2023 Aug 27.
      Under perturbing conditions such as infection with Leishmania, a protozoan parasite living within the phagosomes in mammalian macrophages, cellular and organellar structures, and metabolism are dynamically regulated for neutralizing the pressure of parasitism. However, how modulations of the host cell metabolic pathways support Leishmania infection remains unknown. Herein, we report that lipid accumulation heightens the susceptibility of mice to L. donovani infection and promotes resistance to first-line anti-leishmanial drugs. Despite being pro-inflammatory, the in vitro generated uninfected lipid-laden macrophages (LLMs) or adipose-tissue macrophages (ATMs) display lower levels of reactive oxygen and nitrogen species. Upon infection, LLMs secrete higher IL-10 and lower IL-12p70 cytokines, inhibiting CD4+ T cell activation and Th1 response suggesting a key modulatory role for intramacrophage lipid accumulation in anti-leishmanial host defence. We, therefore, examined this causal relationship between lipids and immunomodulation using an in vivo high-fat diet (HFD) mouse model. HFD increased the susceptibility to L. donovani infection accompanied by a defective CD4+ Th1 and CD8+ T cell response. The white adipose tissue of HFD mice displays increased susceptibility to L. donovani infection with the preferential infection of F4/80+ CD11b+ CD11c+ macrophages with higher levels of neutral lipids reserve. The HFD increased resistance to a first-line anti-leishmanial drug associated with a defective adaptive immune response. These data demonstrate that the accumulation of neutral lipids contributes to susceptibility to visceral leishmaniasis hindering host-protective immune response and reducing the efficacy of antiparasitic drug therapies.
    Keywords:  T cell; macrophage; parasitic-protozoan
  11. Am J Transplant. 2023 Aug 24. pii: S1600-6135(23)00655-X. [Epub ahead of print]
      Although myeloid-derived suppressor cells (MDSCs) are critical for allograft survival, its regulatory mechanism remains unclear. Herein, our results showed that metabolism sensor SIRT2 negatively regulates the functions of MDSCs in inducing allogeneic skin graft rejection. Genetic deletion of SIRT2 in myeloid cells (Sirt2Δmye) increased the number of CD11b+Gr1+ MDSCs in bone marrow, spleens, draining lymph nodes (dLNs) and allograft, inhibited the production of proinflammatory cytokine TNFα and enhanced the production of anti-inflammatory cytokine IL-10 and potentiated the suppressive activation of MDSCs in prolonging allograft skin survival. CXCR2 is critically for mediating the recruitment, cytokine production of MDSCs induced by SIRT2. Mechanistically, Sirt2Δmye enhanced NAD+ level, succinate dehydrogenase (SDHA) activities and oxidative phosphorylation (OXPHOS) level in MDSCs after transplantation. Pharmacologically blocking NAMPT effectively reverse the production of cytokine and suppressive activities of MDSC induced by Sirt2Δmye. Blocking OXPHOS with knockdown of SDHA or pharmacological blocking of SDHA significantly restore Sirt2Δmye-mediated stronger MDSC suppressive activity and inflammatory factor productions. Thus, our findings identify a previously unrecognized interplay between NAD+ and SDH-mediated OXPHOS metabolic pathway in regulating MDSC functions induced by metabolic sensor SIRT2 in allogeneic transplantation.
    Keywords:  NAD(+); allograft transplantation; glucose metabolism; glycolysis; inflammation; myeloid-derived suppressor cells; oxidative phosphorylation
  12. Biomaterials. 2023 Aug 26. pii: S0142-9612(23)00300-9. [Epub ahead of print]301 122292
      Succinate is an important metabolite that modulates metabolism of immune cells and cancer cells in the tumor microenvironment (TME). Herein, we report that polyethylene succinate (PES) microparticles (MPs) biomaterial mediated controlled delivery of succinate in the TME modulates macrophage responses. Administering PES MPs locally with or without a BRAF inhibitor systemically in an immune-defective aging mice with clinically relevant BRAFV600E mutated YUMM1.1 melanoma decreased tumor volume three-fold. PES MPs in the TME also led to maintenance of M1 macrophages with up-regulation of TSLP and type 1 interferon pathway. Impressively, this led to generation of pro-inflammatory adaptive immune responses in the form of increased T helper type 1 and T helper type 17 cells in the TME. Overall, our findings from this challenging tumor model suggest that immunometabolism-modifying PES MP strategies provide an approach for developing robust cancer immunotherapies.
    Keywords:  Cancer; Immunometabolism; Macrophages; Melanoma; Succinate
  13. Cell Death Dis. 2023 08 29. 14(8): 574
    TOR Centre
      Liver regeneration is a dynamic and regulated process that involves inflammation, granulation, and tissue remodeling. Hepatic macrophages, abundantly distributed in the liver, are essential components that actively participate in each step to orchestrate liver regeneration. In the homeostatic liver, resident macrophages (Kupffer cells) acquire a tolerogenic phenotype and contribute to immunological tolerance. Following toxicity-induced damage or physical resection, Kupffer cells as well as monocyte-derived macrophages can be activated and promote an inflammatory process that supports the survival and activation of hepatic myofibroblasts and thus promotes scar tissue formation. Subsequently, these macrophages, in turn, exhibit the anti-inflammatory effects critical to extracellular matrix remodeling during the resolution stage. However, continuous damage-induced chronic inflammation generally leads to hepatic macrophage dysfunction, which exacerbates hepatocellular injury and triggers further liver fibrosis and even cirrhosis. Emerging macrophage-targeting strategies have shown efficacy in both preclinical and clinical studies. Increasing evidence indicates that metabolic rewiring provides substrates for epigenetic modification, which endows monocytes/macrophages with prolonged "innate immune memory". Therefore, it is reasonable to conceive novel therapeutic strategies for metabolically reprogramming macrophages and thus mediate a homeostatic or reparative process for hepatic inflammation management and liver regeneration.
  14. Nat Aging. 2023 Aug 31.
      Aging compromises hematopoietic and immune system functions, making older adults especially susceptible to hematopoietic failure, infections and tumor development, and thus representing an important medical target for a broad range of diseases. During aging, hematopoietic stem cells (HSCs) lose their blood reconstitution capability and commit preferentially toward the myeloid lineage (myeloid bias)1,2. These processes are accompanied by an aberrant accumulation of mitochondria in HSCs3. The administration of the mitochondrial modulator urolithin A corrects mitochondrial function in HSCs and completely restores the blood reconstitution capability of 'old' HSCs. Moreover, urolithin A-supplemented food restores lymphoid compartments, boosts HSC function and improves the immune response against viral infection in old mice. Altogether our results demonstrate that boosting mitochondrial recycling reverts the aging phenotype in the hematopoietic and immune systems.
  15. Mol Nutr Food Res. 2023 Sep 01. e2300155
      SCOPE: Zinc and glutamine are well known to be essential for the function and polarization of immune cells. TH 17 cells are more frequently induced during zinc deficiency and cover their energy requirement mainly through glutaminolysis. A dysregulation of TH 17 cells can contribute to the development of autoimmune diseases. Both inhibition of glutaminolysis and zinc supplementation suppress experimental autoimmune encephalomyelitis in mice. Therefore, the aim of this study is to investigate whether zinc modulates glutaminolysis in T cells.METHODS AND RESULTS: CD3/CD28 stimulation and mixed lymphocytes culture are used as in vitro models for T cell activation. Then, the glutaminolysis is investigated on mRNA, protein, and functional level. Zinc deficiency and glutaminase (GLS) inhibition decrease immune responses in vitro. Furthermore, extracellular zinc and glutamine levels both modulate glutaminolysis by changing the expression of glutamine transporters and key enzymes. Intriguingly, zinc directly interferes with the activity of GLS both in a cell free system and in the cytosol.
    CONCLUSION: Besides T cell subset differentiation, zinc also impacts on the cellular metabolism by inhibiting glutaminolysis. This suggests that zinc deficiency can contribute to the development of autoimmune diseases whereas zinc supplementation can support their therapy.
    Keywords:  T cell; glutamine; glutaminolysis; immunology; zinc
  16. Front Microbiol. 2023 ;14 1223113
      Background: Klebsiella pneumoniae (KP) is a major cause of hospital-acquired infections, such as pneumonia. Moreover, it is classified as a pathogen of concern due to sprawling anti-microbial resistance. During infection, the gram-negative pathogen is capable of establishing an intracellular niche in macrophages by altering cellular metabolism. One factor critically affecting the host-pathogen interaction is the availability of essential nutrients, like iron, which is required for KP to proliferate but which also modulates anti-microbial immune effector pathways. We hypothesized, that KP manipulates macrophage iron homeostasis to acquire this crucial nutrient for sustained proliferation.Methods: We applied an in-vitro infection model, in which human macrophage-like PMA-differentiated THP1 cells were infected with KP (strain ATCC 43816). During a 24-h course of infection, we quantified the number of intracellular bacteria via serial plating of cell lysates and evaluated the effects of different stimuli on intracellular bacterial numbers and iron acquisition. Furthermore, we analyzed host and pathogen specific gene and protein expression of key iron metabolism molecules.
    Results: Viable bacteria are recovered from macrophage cell lysates during the course of infection, indicative of persistence of bacteria within host cells and inefficient pathogen clearing by macrophages. Strikingly, following KP infection macrophages strongly induce the expression of the main cellular iron importer transferrin-receptor-1 (TFR1). Accordingly, intracellular KP proliferation is further augmented by the addition of iron loaded transferrin. The induction of TFR1 is mediated via the STAT-6-IL-10 axis, and pharmacological inhibition of this pathway reduces macrophage iron uptake, elicits bacterial iron starvation, and decreases bacterial survival.
    Conclusion: Our results suggest, that KP manipulates macrophage iron metabolism to acquire iron once confined inside the host cell and enforces intracellular bacterial persistence. This is facilitated by microbial mediated induction of TFR1 via the STAT-6-IL-10 axis. Mechanistic insights into immune metabolism will provide opportunities for the development of novel antimicrobial therapies.
    Keywords:  Klebsiella pneumoniae; immune metabolism; interleukin-10; iron; macrophages; transferrin; transferrin receptor
  17. Shock. 2023 Aug 22.
      ABSTRACT: Sepsis-induced acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) is characterized by widespread pulmonary inflammation and immune response, in which pro-inflammatory polarization of alveolar macrophages (AMs) plays an important role. Mitochondria are the key intracellular signaling platforms regulating immune cell responses. Moreover, accumulating evidence suggests that the mitochondrial dynamics of macrophages are imbalanced in sepsis and severe ALI/ARDS. However, the functional significance of mitochondrial dynamics of AMs in septic ALI/ARDS remains largely unknown, and whether it regulates the polarized phenotype of AMs is also unclear. Here, we demonstrated that the mitochondrial dynamics of AMs are imbalanced, manifested by impaired mitochondrial fusion, increased fission and mitochondrial cristae remodeling, both in septic models and ARDS patients. However, suppressing excessive mitochondrial fission with Mdivi-1 or promoting mitochondrial fusion with PM1 to maintain mitochondrial dynamic equilibrium in AMs could inhibit the polarization of AMs into pro-inflammatory phenotype and attenuate sepsis-induced ALI. These data suggest that mitochondrial dynamic imbalance mediates altered polarization of AMs and exacerbates sepsis-induced ALI. This study provides new insights into the underlying mechanisms of sepsis-induced ALI, suggesting the possibility of identifying future drug targets from the perspective of mitochondrial dynamics in AMs.
  18. Adv Microbiol. 2023 Aug;13(8): 399-419
      The Helicobacter pylori vacuolating cytotoxin (VacA) is an intracellular, mitochondrial-targeting exotoxin that rapidly causes mitochondrial dysfunction and fragmentation. Although VacA targeting of mitochondria has been reported to alter overall cellular metabolism, there is little known about the consequences of extended exposure to the toxin. Here, we describe studies to address this gap in knowledge, which have revealed that mitochondrial dysfunction and fragmentation are followed by a time-dependent recovery of mitochondrial structure, mitochondrial transmembrane potential, and cellular ATP levels. Cells exposed to VacA also initially demonstrated a reduction in oxidative phosphorylation, as well as increase in compensatory aerobic glycolysis. These metabolic alterations were reversed in cells with limited toxin exposure, congruent with the recovery of mitochondrial transmembrane potential and the absence of cytochrome c release from the mitochondria. Taken together, these results are consistent with a model that mitochondrial structure and function are restored in VacA-intoxicated cells.
    Keywords:  ATP; Helicobacter pylori; VacA; mitochondria; mitochondrial dynamics; mitochondrial dysfunction; mitochondrial fission; mitochondrial transmembrane potential; oxidative phosphorylation; vacuolating cytotoxin
  19. J Cell Physiol. 2023 Aug 29.
      Alcoholic liver disease (ALD) is a global concern affecting most of the population and leading to the development of end-stage liver disease. Metabolic alterations due to increased alcohol consumption surge the hepatic accumulation of lipids and develop into a severe form of alcoholic steatohepatitis (ASH), depending on age and the consumption rate. The mitochondria in the hepatocyte actively regulate metabolic homeostasis and are disrupted in ALD pathogenesis. The increased NADH upon ethanol metabolism inhibits the mitochondrial oxidation of fatty acids, alters oxidative phosphorylation, and favors de novo lipogenesis. The higher mitochondrial respiration in early ALD increases free radical generation, whereas mitochondrial respiration is uncoupled in chronic ALD, affecting the cellular energy status. The defective glutathione importer due to excessive cholesterol loading and low adenosine triphosphate accounts for additional oxidative stress leading to hepatocyte apoptosis. The defective mitochondrial transcription machinery and sirtuins function in ALD affect mitochondrial function and biogenesis. The metabolites of ethanol metabolism epigenetically alter the gene expression profile of hepatic cell populations by modulating the promoters and sirtuins, aiding hepatic fibrosis and inflammation. The defect in mitophagy increases the accumulation of megamitochondria in hepatocytes and attracts immune cells by releasing mitochondrial damage-associated molecular patterns to initiate hepatic inflammation and ASH progression. Thus, maintaining mitochondrial lipid homeostasis and antioxidant capacity pharmacologically could provide a better outcome for ALD management.
    Keywords:  alcoholic liver disease; mitochondrial biogenesis; mitochondrial damage; mitochondrial damage-associated molecular patterns; mitochondrial quality control; oxidative stress
  20. iScience. 2023 Sep 15. 26(9): 107487
      Aberrant metabolic demand is observed in immune/inflammatory disorders, yet the role in pathogenesis remains unclear. Here, we discover that in lupus, activated B cells, including germinal center B (GCB) cells, have remarkably high glycolytic requirement for survival over T cell populations, as demonstrated by increased metabolic activity in lupus-activated B cells compared to immunization-induced cells. The augmented reliance on glucose oxidation makes GCB cells vulnerable to mitochondrial ROS-induced oxidative stress and apoptosis. Short-term glycolysis inhibition selectively reduces pathogenic activated B in lupus-prone mice, extending their lifespan, without affecting T follicular helper cells. Particularly, BCMA-expressing GCB cells rely heavily on glucose oxidation. Depleting BCMA-expressing activated B cells with APRIL-based CAR-T cells significantly prolongs the lifespan of mice with severe autoimmune disease. These results reveal that glycolysis-dependent activated B and GCB cells, especially those expressing BCMA, are potentially key lupus mediators, and could be targeted to improve disease outcomes.
    Keywords:  Biological sciences; Cell biology; Immunology; Model organism; Transcriptomics
  21. Cell Rep. 2023 Aug 31. pii: S2211-1247(23)01065-3. [Epub ahead of print]42(9): 113054
      Most mutations in retinitis pigmentosa (RP) arise in rod photoreceptors, but cone photoreceptors, responsible for high-resolution daylight and color vision, are subsequently affected, causing the most debilitating features of the disease. We used mass spectroscopy to follow 13C metabolites delivered to the outer retina and single-cell RNA sequencing to assess photoreceptor transcriptomes. The S cone metabolic transcriptome suggests engagement of the TCA cycle and ongoing response to ROS characteristic of oxidative phosphorylation, which we link to their histone modification transcriptome. Tumor necrosis factor (TNF) and its downstream effector RIP3, which drive ROS generation via mitochondrial dysfunction, are induced and activated as S cones undergo early apoptosis in RP. The long/medium-wavelength (L/M) cone transcriptome shows enhanced glycolytic capacity, which maintains their function as RP progresses. Then, as extracellular glucose eventually diminishes, L/M cones are sustained in long-term dormancy by lactate metabolism.
    Keywords:  CP: Neuroscience; cone metabolism; glucose transport; lactate metabolism; photoreceptor metabolic and epigenetic transcriptomes; retinitis pigmentosa; rod metabolism; single cell RNA sequencing
  22. Am J Reprod Immunol. 2023 09;90(3): e13768
      PROBLEM: Pregnancy markedly modifies women's metabolism and immune functions. We hypothesized that pregnancy might alter the immune and metabolic responses to chronic Toxoplasma gondii infection in pregnancy.METHOD OF STUDY: A population of 690 pregnant Hispanic women were screened for antibodies to T. gondii and 158 women were positive (23% positivity) with 83% showing high avidity indices. These seropositive women were followed through their pregnancies with four data collection time points and a postpartum collection at two clinics in Tampa, Florida. A T. gondii seronegative group (N = 128) was randomly selected to serve as a control group and measured along pregnancy in the same way. Serum levels of tryptophan, kynurenine, and their ratio, phenylalanine, tyrosine and their ratio, neopterin, and nitrite were measured through pregnancy and the postpartum. A plasma cytokine panel (IFN-γ, TNFα, IL-2, IL-10, IL-12, IL-6, IL-17) was analyzed in parallel.
    RESULTS: The major findings suggest that indoleamine 2,3-dioxygenase (IDO-1) was less activated in T. gondii seropositive pregnant Hispanic women with chronic infection. Evidence for IDO-1 suppression was that tryptophan catabolism was less pronounced and there were lower levels of multiple inflammatory cytokines including IFN-γ, which is the major inducer of IDO-1, and higher nitrite concentration, a surrogate marker for nitric oxide, an inhibitor of IDO.
    CONCLUSIONS: Latent T. gondii infection was associated with higher plasma tryptophan levels, and lower inflammatory cytokines across pregnancy, suggesting suppression of the IDO-1 enzyme, and possible T cell exhaustion during pregnancy.
    Keywords:  Toxoplasma gondii; immunity; pregnancy pathway chronic infection; tryptophan pathway
  23. J Gastroenterol Hepatol. 2023 Sep 01.
      Hepatitis B virus (HBV) infection is closely related to viral hepatitis, liver cirrhosis, and hepatocellular carcinoma. HBV infection can reprogram metabolism processes of the host cells including glucose metabolism. The aberrant glucose metabolism may aid in viral infection and immune escape and may contribute to liver associated pathology. In this review, we discussed the interplay between HBV infection and glucose metabolism, which may provide new insights into HBV infection and pathology, novel intervention targets for HBV-related diseases.
    Keywords:  Cirrhosis; Glucose metabolism; Hepatitis B virus; Hepatocellular carcinoma; Immune escape
  24. Immun Inflamm Dis. 2023 08;11(8): e965
      INTRODUCTION: This study endeavored to investigate the role of DOCK8 in modulating the immune function triggered by sepsis.METHODS: Expression of DOCK8 in the whole blood of sepsis patients and its enrichment pathways were assayed by bioinformatics. Pearson analysis was used to predict the relationship between glycolytic signaling pathway and its relevance to neutrophil function in sepsis. A sepsis mouse model was then built by performing cecal ligation and puncture treatment on male mice. Neutrophils were isolated, and their purity was tested by flow cytometry. Neutrophils were then stimulated by lipopolysaccharide to build a sepsis cell model. Next, quantitative reverse transcription polymerase chain reaction and CCK-8 were applied to test the expression of DOCK8 and cell viability, western blot to assay the expression of HK-2, PKM2, and LDHA proteins, ELISA to measure the concentrations of TNF-α, IL-1β, and IL-6, Transwell to detect the chemotaxis of neutrophils and flow cytometry to detect the phagocytic activity of neutrophils. Finally, in different treatment groups, we used Seahorse XF 96 to analyze the extracellular acidification rate (ECAR) of sepsis cells and used enzyme-linked immunosorbent assay to detect the contents of pyruvic acid, lactic acid, and ATP in sepsis cells.
    RESULTS: DOCK8 was downregulated in sepsis blood and activated neutrophils. Aerobic glycolysis was positively correlated with sepsis. Activated neutrophils promoted the expression of inflammatory factors TNF-α, IL-1β, and IL-6. Low expression of DOCK8 facilitated the proliferation, chemotaxis, and phagocytic activity of sepsis cells and promoted the expression of inflammatory factors. Bioinformatics analysis revealed that DOCK8 was enriched in the glycolytic signaling pathway. Low expression of DOCK8 induced ECAR, promoted the protein expression of HK-2, PKM2 and LDHA, and favored the increase of pyruvate, lactate, and ATP contents. While 2-DG treatment could restore these effects.
    CONCLUSION: DOCK8 may inhibit sepsis-induced neutrophil immune function by regulating aerobic glycolysis and causing excessive inflammation, which helps to explore potential therapeutic targets.
    Keywords:  DOCK8; aerobic glycolysis; immune function; neutrophils; sepsis
  25. J Biochem Mol Toxicol. 2023 Aug 28. e23518
      Aldehyde dehydrogenase 2 (ALDH2) deficiency caused by   genetic variant is present in more than 560 million people of East Asian descent, which can be identified by apparent facial flushing from acetaldehyde accumulation after consuming alcohol. Recent findings indicated that ALDH2 also played a critical role in detoxification of formaldehyde (FA). Our previous studies showed that FA could enhance macrophagic inflammatory responses through the induction of HIF-1α-dependent glycolysis. In the present study, pro-inflammatory responses and glycolysis promoted by 0.5 mg/m3 FA were found in mice with Aldh2 gene knockout, which was confirmed in the primary macrophages isolated from Aldh2 gene knockout mice treated with 50 μM FA. FA at 50 and 100 μM also induced stronger dose-dependent increases of pro-inflammatory responses and glycolysis in RAW264.7 murine macrophages with knock-down of ALDH2, and the enhanced effects induced by 50 μM FA was alleviated by inhibition of HIF-1α in RAW264.7 macrophages with ALDH2 knock-down. Collectively, these results clearly demonstrated that ALDH2 deficiency reinforced pro-inflammatory responses and glycolysis in macrophages potentiated by environmentally relevant concentration of FA, which may increase the susceptibility to inflammation and immunotoxicity induced by environmental FA exposure.
    Keywords:  ALDH2; HIF-1α; glycolysis; inflammatory cytokines; macrophages
  26. Cell Biosci. 2023 Aug 30. 13(1): 158
      BACKGROUND: Mitophagy, mitochondrial selective autophagy, plays a pivotal role in the maintenance of cellular homeostasis in response to cellular stress. However, the role of mitophagy in macrophages during infection has not been elucidated. To determine whether mitophagy regulates intracellular pathogen survival, macrophages were infected with Mycobacterium tuberculosis (Mtb), an intracellular bacterium.RESULTS: We showed that Mtb-infected macrophages induced mitophagy through BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) activation. In contrast, BNIP3-deficient macrophages failed to induce mitophagy, resulting in reduced mitochondrial membrane potential in response to Mtb infection. Moreover, the accumulation of damaged mitochondria due to BNIP3 deficiency generated higher levels of mitochondrial reactive oxygen species (mROS) compared to the control, suppressing the intracellular survival of Mtb. We observed that siBNIP3 suppressed intracellular Mtb in mice lungs.
    CONCLUSION: We found that BNIP3 plays a critical role in the regulation of mitophagy during Mtb infection. The inhibition of mitophagy suppresses Mtb growth in macrophages through increased mROS production. Therefore, BNIP3 might be a novel therapeutic target for tuberculosis treatment.
    Keywords:  BNIP3; Macrophage; Mitophagy; Mycobacterium tuberculosis; mROS
  27. Front Pharmacol. 2023 ;14 1215861
      Background: Psoriasis is a common chronic inflammatory skin disease characterized by an external red rash that is caused by abnormal proliferation and differentiation of keratinocytes and immune T cells. This study aimed to elucidate the role of aminooxy acetic acid (AOA) in alleviating psoriasis from the perspective of immunology and metabolomics. Therefore, contributing to the development of new drugs as candidates for psoriasis treatment. Methods: To investigate the symptom-alleviating effects and the related mechanisms of AOA on the treatment of psoriasis, we used a 12-O-tetradecanoylphorbol-13-acetate-induced psoriasis-like skin mouse model and interleukin (IL)-17-stimulated human keratinocytes. Results: The results showed that AOA ameliorated psoriasis-related symptoms and decreased inflammation-associated antimicrobial peptides and T-helper 17 (Th17)-associated cytokines in a mouse model of psoriasis. Furthermore, AOA inhibited the activation of mechanistic target of rapamycin (mTOR) by suppressing serine metabolism-related genes. Importantly, mTOR inhibition ameliorated psoriatic disease by affecting the differentiation of various T cells and normalizing the Th17/regulatory T (Treg) cell balance. In addition, IL-17-stimulated human keratinocytes showed the same results as in the in vivo experiments. Conclusion: Taken together, these results suggest that targeting the serine metabolism pathway in the treatment of psoriasis is a novel strategy, and that AOA could be utilized as a novel biologic to treat psoriasis.
    Keywords:  Th17; Treg; aminooxy acetic acid; mTOR; psoriasis; serine metabolism
  28. JCI Insight. 2023 Aug 31. pii: e171701. [Epub ahead of print]
      Adipose tissue macrophage (ATM) infiltration is associated with adipose tissue dysfunction and insulin resistance in mice and humans. Recent single cell data highlight increased ATM heterogeneity in obesity, but do not provide a spatial context for ATM phenotype dynamics. We integrated single cell RNA-sequencing, spatial transcriptomics, and imaging of murine adipose tissue in a time course of diet-induced obesity. Overall, proinflammatory immune cells were predominant in early obesity, while non-resident antiinflammatory ATMs predominated in chronic obesity. A subset of these antiinflammatory ATMs were transcriptomically intermediate between monocytes and mature lipid-associated macrophages (LAM) and were consistent with a LAM precursor (pre-LAM). Pre-LAMs were spatially associated with early obesity crown-like structures (CLS), which indicate adipose tissue dysfunction. Spatial data showed colocalization of ligand-receptor transcripts related to lipid signaling among monocytes, pre-LAMs, and LAMs, including Apoe, Lrp1, Lpl and App. Pre-LAM expression of these ligands in early obesity suggested signaling to LAMs in the CLS microenvironment. Our results refine understanding of ATM diversity and provide insight into the dynamics of the LAM lineage during development of metabolic disease.
    Keywords:  Adipose tissue; Macrophages; Metabolism; Obesity
  29. EBioMedicine. 2023 Aug 30. pii: S2352-3964(23)00344-4. [Epub ahead of print]95 104778
      BACKGROUND: Dysregulated inflammatory responses and oxidative stress are key pathogenic drivers of chronic inflammatory diseases such as liver cirrhosis (LC). Regulatory T cells (Tregs) are essential to prevent excessive immune activation and maintain tissue homeostasis. While inflammatory cues are well known to modulate the function and stability of Tregs, the extent to which Tregs are influenced by oxidative stress has not been fully explored.METHODS: The phenotypic and functional properties of CD4+CD25+CD127lo/- Tregs isolated from patients with LC were compared to healthy controls (HC). Treg redox state was investigated by characterizing intracellular reactive oxygen species (ROS), NADPH oxidase-2 (Nox2) activity, mitochondrial function, morphology, and nuclear factor-erythroid 2-related factor (Nrf2) antioxidant signalling. The relevance of Nrf2 and its downstream target, Heme-oxygenase-1 (HO-1), in Treg function, stability, and survival, was further assessed using mouse models and CRISPR/Cas9-mediated HO-1 knock-out.
    FINDINGS: Circulating Tregs from LC patients displayed a reduced suppressive function, correlating with liver disease severity, associated with phenotypic abnormalities and increased apoptosis. Mechanistically, this was linked to a dysregulated Nrf2 signalling with resultant lower levels of HO-1, enhanced Nox2 activation, and impaired mitochondrial respiration and integrity. The functional deficit in LC Tregs could be partially recapitulated by culturing control Tregs in patient sera.
    INTERPRETATION: Our findings reveal that Tregs rely on functional redox homeostasis for their function, stability, and survival. Targeting Treg specific anti-oxidant pathways may have therapeutic potential to reverse the Treg impairment in conditions of oxidative damage such as advanced liver disease.
    FUNDING: This study was funded by the Wellcome Trust (211113/A/18/Z).
    Keywords:  Liver cirrhosis; Mitochondria; Nrf2/heme oxygenase-1; Oxidative stress; Redox homeostasis; Regulatory T cells
  30. Proc Natl Acad Sci U S A. 2023 Sep 05. 120(36): e2215941120
      Group 2 innate lymphoid cells (ILC2s) are critical for the immune response against parasite infection and tissue homeostasis and involved in the pathogenesis of allergy and inflammatory diseases. Although multiple molecules positively regulating ILC2 development and activation have been extensively investigated, the factors limiting their population size and response remain poorly studied. Here, we found that CD45, a membrane-bound tyrosine phosphatase essential for T cell development, negatively regulated ILC2s in a cell-intrinsic manner. ILC2s in CD45-deficient mice exhibited enhanced proliferation and maturation in the bone marrow and hyperactivated phenotypes in the lung with high glycolytic capacity. Furthermore, CD45 signaling suppressed the type 2 inflammatory response by lung ILC2s and alleviated airway inflammation and pulmonary fibrosis. Finally, the interaction with galectin-9 influenced CD45 signaling in ILC2s. These results demonstrate that CD45 is a cell-intrinsic negative regulator of ILC2s and prevents lung inflammation and fibrosis via ILC2s.
    Keywords:  CD45; airway inflammation; fibrosis; innate lymphoid cell; metabolism
  31. STAR Protoc. 2023 Aug 25. pii: S2666-1667(23)00499-9. [Epub ahead of print]4(3): 102532
      Intracellular ATP supports the function of γδT17 cells in mice. Here, we present a protocol for intracellular ATP delivery to in vitro expanded mouse CD27- γδ T cells. We describe steps for pre-coating well plates, preparing lymphocytes, culturing CD27- γδ T cells, and ATP delivery. We then detail functional evaluation of γδ T cells by flow cytometry. Appropriate concentrations of control and ATP vesicles are detailed for intracellular ATP delivery, which can also be applied to other immune cells. For complete details on the use and execution of this protocol, please refer to Wang et al. (2023).1.
    Keywords:  Cell Culture; Cell Isolation; Flow Cytometry/Mass Cytometry; Health Sciences; Immunology; Metabolism
  32. Prog Lipid Res. 2023 Aug 24. pii: S0163-7827(23)00041-3. [Epub ahead of print]92 101251
      Sphingolipids are essential components of all eukaryotic membranes. The bioactive sphingolipid molecule, Sphingosine 1-Phosphate (S1P), regulates various important biological functions. This review aims to provide a comprehensive overview of the role of S1P signaling pathway in various immune cell functions under different pathophysiological conditions including bacterial and viral infections, autoimmune disorders, inflammation, and cancer. We covered the aspects of S1P pathways in NOD/TLR pathways, bacterial and viral infections, autoimmune disorders, and tumor immunology. This implies that targeting S1P signaling can be used as a strategy to block these pathologies. Our current understanding of targeting various components of S1P signaling for therapeutic purposes and the present status of S1P pathway inhibitors or modulators in disease conditions where the host immune system plays a pivotal role is the primary focus of this review.