bims-imicid Biomed News
on Immunometabolism of infection, cancer and immune-mediated disease
Issue of 2026–05–24
thirty-six papers selected by
Dylan Gerard Ryan, Trinity College Dublin



  1. Clin Transl Med. 2026 May;16(5): e70665
      Immunotherapy has emerged as a transformative approach to cancer treatment, yet its clinical efficacy in most solid tumours remains limited, largely because of the immunosuppressive tumour microenvironment (TME). In this context, glucose metabolic reprogramming has emerged as a central determinant of tumour progression and immune dysfunction because it not only sustains the proliferative and biosynthetic demands of malignant cells but also profoundly reshapes immune responses within the TME. Effective antitumour immunity depends on the metabolic adaptability of effector immune cells, particularly the coordinated use of glycolysis and oxidative phosphorylation to support activation, expansion and cytotoxic function. Under the nutrient-deprived, hypoxic and acidic conditions that characterize the TME, however, these cells undergo metabolic restriction that progressively drives dysfunction and exhaustion. By contrast, regulatory T cells, tumour-associated macrophages and myeloid-derived suppressor cells exhibit greater metabolic plasticity, enabling their persistence and reinforcing their immunosuppressive activity. In this review, we discuss how glucose metabolic reprogramming drives immune dysfunction through several interconnected processes, including glucose competition, lactate accumulation, reciprocal regulation between glucose metabolism and cytokine signalling, glycosylation remodelling and dynamic crosstalk with immune checkpoint signalling. Collectively, these mechanisms position glucose metabolism as a pivotal immunometabolic axis linking tumour bioenergetics to immune evasion and therapeutic resistance. A deeper understanding of this regulatory network may inform the rational development of combination strategies that integrate metabolic intervention with immunotherapy, ultimately improving therapeutic precision and the durability of clinical benefit. HIGHLIGHT: Glucose metabolic reprogramming is a central driver of immunosuppression in the tumour microenvironment. Glucose competition establishes a selective bioenergetic hierarchy that constrains antitumour immunity. Lactate accumulation and reciprocal regulation with cytokine signalling amplify immunosuppressive signalling and reinforce immune exclusion. Glycosylation remodelling translates altered metabolic flux into sustained changes in receptor stability, ligand recognition and checkpoint responsiveness. Dynamic crosstalk with immune checkpoint signalling entrenches chronic immune dysfunction and therapeutic resistance.
    Keywords:  Warburg effect; glucose metabolic reprogramming; immunometabolism; immunosuppression; immunotherapy; tumour microenvironment
    DOI:  https://doi.org/10.1002/ctm2.70665
  2. Front Immunol. 2026 ;17 1790174
       Background: The TIGIT/CD155 axis is a key immune checkpoint in hepatocellular carcinoma (HCC), but its role in regulating natural killer (NK) cell metabolism and function remains unclear. This study investigates how this axis impairs NK cell anti-tumor immunity via metabolic reprogramming.
    Methods: An HCC mouse model was used for single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing (RNA-seq) to identify dysregulated pathways in TIGIThigh NK cells. A co-culture system consisting of CD155-overexpressing tumor cells and NK cells was established. Molecular interactions were examined by co-immunoprecipitation, western blotting, and immunofluorescence. NK-cell glycolytic activity was assessed by extracellular acidification rate, glucose uptake, and lactate production, and NK-cell function was evaluated by cytokine secretion and cytotoxicity assays. The involvement of the SHP-2/STAT3/GLUT1 axis was further examined using genetic and pharmacological interventions in vitro and in a xenograft model.
    Results: CD155 expression was increased in HCC tissues. TIGIThigh NK cells showed transcriptional features consistent with impaired glycolytic activity and functional suppression. CD155 engagement was associated with increased SHP-2 recruitment, reduced STAT3 phosphorylation, and lower GLUT1 expression, accompanied by decreased glycolytic activity. TIGIT blockade restored GLUT1 expression, glycolytic flux, and NK-cell effector function, including IFN-γ production, granzyme B expression, and cytotoxic activity. These effects were weakened by STAT3 inhibition or GLUT1 knockdown. In vivo, TIGIT blockade reduced tumor growth and was associated with increased metabolic and functional markers in NK cells, whereas STAT3 inhibition partially attenuated these effects.
    Conclusion: The TIGIT/CD155 axis is associated with NK-cell dysfunction in HCC through SHP-2-dependent suppression of STAT3/GLUT1-related glycolytic metabolism. These findings suggest that metabolic restoration may represent a potential strategy to improve NK-cell-mediated antitumor immunity in HCC.
    Keywords:  TIGIT/CD155; glycolysis; hepatocellular carcinoma; immunometabolism; natural killer cells
    DOI:  https://doi.org/10.3389/fimmu.2026.1790174
  3. bioRxiv. 2026 May 07. pii: 2026.05.05.722986. [Epub ahead of print]
      Neutrophil functions have been linked to tuberculosis (TB)-associated tissue damage; however, the mechanisms driving immunopathology in the human TB lung remain poorly understood, due partly to the scarcity of human tissue for study. Here, we examine the metabolic and bioenergetic reprogramming of human neutrophils in response to Mycobacterium tuberculosis ( Mtb ) infection. In human necrotic TB granulomas, levels of NETosis-associated proteins are increased and co-localize with GLUT3, linking nutrient uptake to tissue damage. In vitro , Mtb elicits an immediate, contact-dependent oxidative burst in human neutrophils, and the magnitude of this response is carbon source-dependent. Glucose enables the most robust responses, indicating that glucose metabolism is a key driver of neutrophil-mediated inflammatory damage during TB. Mtb -induced responses are distinct from those induced by PMA, non-tuberculous mycobacteria, or other pathogenic intracellular bacteria, and are mediated through multiple neutrophil surface receptors. Notably, our data show that while the oxidative burst is carbon source-dependent, cytokine production is not. Further, Mtb infection reprograms neutrophil metabolism from glycolysis to the pentose phosphate pathway (PPP), generating NADPH required for the oxidative burst. Inhibiting G6PD, NADPH oxidase, or PAD4 significantly reduces this response, highlighting the PPP as a promising host target for mitigating TB immunopathology.
    DOI:  https://doi.org/10.64898/2026.05.05.722986
  4. Redox Biol. 2026 May 12. pii: S2213-2317(26)00208-9. [Epub ahead of print]94 104210
      Despite advances in recanalization therapy for ischemic stroke, effective neuroprotection against cerebral ischemia-reperfusion injury (CIRI) remains an unmet need, largely due to persistent microglia-driven neuroinflammation and associated oxidative stress. Vespakinin-M (VK) is a naturally neuroprotective peptide isolated from wasp venom that can cross the blood-brain barrier. Although VK has been shown to improve functional outcomes in preliminary stroke models, its underlying mechanisms remain unclear. Here, we show that administration of VK alleviates neuroinflammation and oxidative damage in a mouse stroke model. This neuroprotection is orchestrated by microglial metabolic reprogramming, which shifts their energy metabolism from aerobic glycolysis toward oxidative phosphorylation (OXPHOS) and their functional phenotype from pro-inflammatory M1 to reparative M2. Integrated multi-omics and isotopic tracing uncover that VK redirects arginine metabolism to generate fumarate. This directly couples amino acid catabolism with the tricarboxylic acid (TCA) cycle, thereby restoring mitochondrial bioenergetics and redox balance. Mechanistically, VK activates the energy sensor AMPK while inhibiting the anabolic regulator mTOR. AMPK knockdown partially abolishes the beneficial effects of VK, establishing the AMPK/mTOR axis as the upstream regulator of this arginine-centric metabolic rewiring. Interestingly, VK retains the ability to stimulate de novo arginine synthesis even under arginine-deprived conditions, and its efficacy is synergistically enhanced with arginine supplementation. Together, these findings define an immunometabolic axis-AMPK/mTOR-arginine-TCA cycle coupling-that dictates microglial fate after stroke, and suggests VK as a therapeutic agent capable of concurrently targeting neuroinflammation, mitochondrial dysfunction, and metabolic imbalance.
    Keywords:  Arginine metabolism; Immunometabolism; Ischemic stroke; Microglia; Mitochondrial dysfunction; Vespakinin-M
    DOI:  https://doi.org/10.1016/j.redox.2026.104210
  5. Int Immunopharmacol. 2026 Aug 01. pii: S1567-5769(26)00699-5. [Epub ahead of print]182 116853
      Sepsis is a dysregulated host immune response to pathogen infection, characterized by an initial acute hyperinflammatory response followed by persistent immunosuppression. The immunosuppressive phase of sepsis is characterized by a marked impairment in the capacity of monocytes/macrophages to produce pro-inflammatory cytokines, a dysfunction linked to severe mitochondrial metabolic defects. Mitophagy is a crucial cellular process that regulates macrophage inflammation by maintaining mitochondrial homeostasis. FUN14domain- containing 1 (FUNDC1) is a known mitophagy receptor, but its role in macrophages during sepsis-induced immunosuppression remains unclear. In this study, we found that FUNDC1-mediated mitophagy is suppressed in immunosuppressive macrophages. Furthermore, both FUNDC1 knockdown and a cell-penetrating FUNDC1-inhibitory peptide P (CPP-P) further suppressed pro-inflammatory cytokines production in immunosuppressive macrophages. Mechanistic studies demonstrated that suppressing FUNDC1-dependent mitophagy exacerbates metabolic dysfunction of immunosuppressive macrophages. Additionally, CPP-P-treated mice exhibit reduced pro-inflammatory cytokines release and impaired bacterial clearance, resulting in exacerbated lung tissue damage and elevated mortality during the immunosuppressive phase of sepsis. Collectively, our study demonstrates that suppression of FUNDC1-mediated mitophagy in macrophages contributes to the immunocompromised state in sepsis and reveals potential therapeutic targets.
    Keywords:  FUNDC1-mediated mitophagy; Immunometabolism; Macrophages; Sepsis-induced immunosuppression
    DOI:  https://doi.org/10.1016/j.intimp.2026.116853
  6. Elife. 2026 May 21. pii: RP109093. [Epub ahead of print]14
      Naive B cells exit quiescence and enter a proliferative state upon activation, ultimately differentiating into antibody-secreting or memory B cells. Toll-like receptor (TLR) ligands, such as lipopolysaccharide (LPS), can serve as physiological stimuli to initiate this transition. Using quantitative proteomics, we show that TLR4 engagement induces metabolic reprogramming in murine B cells, increasing the expression of amino acid transporters and cholesterol biosynthetic enzymes. The amino acid transporter SLC7A5 is markedly upregulated following LPS stimulation, and conditional deletion of Slc7a5 impairs B cell proliferation, underscoring its essential role in B cell activation. LPS also elevates intracellular cholesterol levels, and inhibition of the rate-limiting enzyme HMG-CoA reductase blocks proliferation. This effect was mediated by a dual requirement for cholesterol metabolism and protein prenylation downstream of HMG-CoA reductase. Notably, this was not unique to TLR4 signalling but is also observed in B cells activated via TLR7, TLR9, CD40, or the B cell receptor. Together, these findings reveal that metabolic rewiring, including amino acid uptake and cholesterol metabolism, is an essential feature of B cell activation and proliferation.
    Keywords:  B cell; cholesterol; immunology; inflammation; mouse; statin; toll-like receptor
    DOI:  https://doi.org/10.7554/eLife.109093
  7. Nat Commun. 2026 May 19.
      Group 3 innate lymphoid cells (ILC3) are crucial in neonatal necrotizing enterocolitis (NEC); however, the underlying mechanisms remain elusive. Here, we identify NKp46⁻CCR6⁻ (double-negative, DN) ILC3s as the dominant pathogenic subset driving NEC via IL-17 A secretion, which disrupts intestinal barrier integrity. Mechanistically, Atg5 activates autophagy in DN ILC3s during NEC. Atg5 conditional knockout in RORγt⁺ cells mitigates NEC, reduces DN ILC3 accumulation and IL-17 A production. Atg5 deficiency also decreases HIF-1α chromatin accessibility and transcriptional activity, shifting DN ILC3 metabolism from glycolysis to fatty acid oxidation. Lipidomics reveals phosphatidylcholine as a key downstream metabolite of Atg5-mediated autophagy. Phosphatidylcholine supplementation suppresses DN ILC3-driven inflammation, restores metabolic homeostasis, elevates Clostridium abundance, and ameliorates NEC in mice. Importantly, human NEC tissues exhibit increased ILC3 proportions, autophagic activity, and IL-17 A/IL-22 secretion. Thus, we uncover an Atg5-autophagy-glycolipid metabolic axis in DN ILC3s that drives NEC pathogenesis, providing a promising therapeutic target for neonatal NEC.
    DOI:  https://doi.org/10.1038/s41467-026-73356-x
  8. Front Immunol. 2026 ;17 1781797
      Micronutrients serve as critical metabolic sensors and epigenetic regulators that orchestrate cytokine production through multiple overlapping signalling cascades, transcriptional networks, and cellular metabolic states. This comprehensive review synthesizes recent research demonstrating that micronutrient status regulates cytokine biology at five hierarchical levels: (i) nutrient sensing via mTORC1/GCN2 and amino acid sensor networks; (ii) transcriptional control through VDR/RARα-mediated epigenetic remodelling and histone deacetylase inhibition; (iii) redox signalling via SELENOK/selenoprotein-stabilized calcium homeostasis and Nrf2/ARE pathway activation; (iv) Pyroptosis/ferroptosis execution via metallothionein-zinc-caspase axes and NLRP3/GSDMD regulation; and (v) metabolic bioenergetics through NAD+/CD38/SIRT-mediated immune cell differentiation and aging. Recent discoveries establish that vitamin D directly suppresses IL-22 through repressive VDREs independent aryl-hydrocarbon receptor (AhR) signalling, zinc-metallothionein-3 that suppresses non-canonical inflammasome activation via TRIF-IRF3-STAT1 modulation, selenium-dependent SELENOK which stabilizes IP3 receptor-mediated store-operated calcium entry in immune cells, and folate-dependent one-carbon metabolism generating S-adenosyl methionine (SAM) that tunes epigenetic landscapes of cytokine genes. This review compiles the integrated mechanistic frameworks linking micronutrient availability to immunometabolic checkpoints, with implications for nutritional immunotherapy in chronic inflammatory diseases and immune-senescence.
    Keywords:  calcium signalling; cytokines; epigenetics; ferroptosis; immunometabolism; inflammaging; metabolic sensing; micronutrients
    DOI:  https://doi.org/10.3389/fimmu.2026.1781797
  9. Int Immunopharmacol. 2026 May 19. pii: S1567-5769(26)00722-8. [Epub ahead of print]183 116876
      Macrophages exhibit remarkable plasticity, polarizing into distinct phenotypes upon sensing microenvironmental cues. Long-chain fatty acids (LCFAs) function as both crucial metabolic substrates and key signaling molecules that dictate macrophage metabolic reprogramming and polarization. This review systematically delineates the mechanisms of LCFAs uptake via transporters (e.g., CD36, FATP1) and the molecular pathways by which LCFAs reshape macrophage lipid metabolism by modulating core metabolic nodes (e.g., FASN, SCD1, AMPK, PPARs). Distinct LCFAs exert differential regulatory functions: saturated fatty acids promote M1 pro-inflammatory polarization, whereas ω-3 polyunsaturated fatty acids and their specialized pro-resolving mediators (SPMs), such as MaR1 and RvD1, drive M2 anti-inflammatory polarization. These mechanisms play pivotal roles in metabolic diseases and cancer progression. This review offer novel perspectives on the intricate crosstalk between immunity and metabolism, and establish a theoretical foundation for developing therapeutic strategies targeting macrophage metabolism.
    Keywords:  Disease; Long-chain fatty acids; Macrophages; Metabolic reprogramming; Polarization
    DOI:  https://doi.org/10.1016/j.intimp.2026.116876
  10. Cancer Immunol Immunother. 2026 May 20.
      Ketogenic diets (KDs) have been reported to influence tumor progression through metabolic and immunological modulation of the tumor microenvironment. β-hydroxybutyrate (βOHB), the predominant ketone body elevated by KD, functions not only as an energy substrate but also as a potent signaling metabolite. Despite its role in modulating the tumor microenvironment, the direct impact of βOHB on the function of CD8+ T cell, a key mediator of anti-tumor immunity, remains incompletely understood. Here, we demonstrate that βOHB suppresses tumor growth in multiple mouse tumor models by enhancing the accumulation, survival, and effector function of tumor-infiltrating CD8+ T cells. In contrast, acetoacetate does not exert comparable immunomodulatory effects. Mechanistically, βOHB upregulates the Tcf7-Lck signaling pathway by engaging with the cell surface receptor Hcar2, an effect potentially working in parallel with its role as an HDAC inhibitor. Knockdown of either Tcf7 or Hcar2 in CD8+ T cells abolishes the promoting effect of βOHB on CD8+ T function. Our findings elucidate a metabolite-immune axis that directly regulates the functional state of tumor-infiltrating CD8⁺ T cells and provide experimental evidence linking ketone metabolism to anti-tumor immune regulation.
    Keywords:  Anti-tumor therapy; CD8+ T cell; Lck; Tcf7; β-hydroxybutyrate
    DOI:  https://doi.org/10.1007/s00262-026-04420-0
  11. Front Physiol. 2026 ;17 1721230
      Macrophage functional plasticity is intrinsically linked to metabolic reprogramming, including mitochondrial function, substrate utilization, and redox signaling. In response to hypoxia, infection, or tissue injury, macrophages rely on mitochondria not only for energy provision but, critically, for metabolic intermediates and reactive oxygen species (ROS) that serve as signaling molecules to guide gene expression reprogramming. While macrophage activation exists along a continuous spectrum, this review summarizes the distinct metabolic paradigms characterizing the classical M1-like (glycolysis-dominant) and M2-like (oxidative phosphorylation, OXPHOS-dominant) extremes, highlighting the molecular mechanisms where metabolic events-specifically tricarboxylic acid (TCA) cycle truncation and succinate accumulation-drive inflammatory polarization. Furthermore, we discuss the role of mitochondrial quality control, particularly dynamics and mitophagy, in maintaining macrophage homeostasis. Notably, recent evidence identifies "intercellular mitochondrial transfer" as a novel mode of immune microenvironment regulation, enabling damaged macrophages to restore function by acquiring exogenous mitochondria. A deeper understanding of these mechanisms offers new intervention targets for metabolic immunotherapy in sepsis, cancer, and chronic inflammatory diseases. Importantly, we emphasize that many of these metabolic and mitochondrial regulatory mechanisms are highly context-dependent, varying significantly across different tissues and disease microenvironments.
    Keywords:  intercellular mitochondrial transfer; macrophage polarization; metabolic reprogramming; mitochondria; mitophagy
    DOI:  https://doi.org/10.3389/fphys.2026.1721230
  12. J Immunol. 2026 May 14. pii: vkag090. [Epub ahead of print]215(5):
      Alveolar macrophages (AMs) are key mediators of lung function and are potential targets for therapies during respiratory infections. TGFβ is an important regulator of AM differentiation and maintenance, but how TGFβ directly modulates the innate immune responses of AMs remains unclear. This shortcoming prevents effective targeting of AMs to improve lung function in health and disease. Here, we leveraged an optimized ex vivo AM model system, fetal liver-derived alveolar-like macrophages (FLAMs), to dissect the role of TGFβ in AMs. Using transcriptional analysis, we first globally defined how TGFβ regulates gene expression of resting FLAMs. We found that TGFβ maintains the baseline metabolic state of AMs by driving lipid metabolism through oxidative phosphorylation and restricting inflammation. To better understand inflammatory regulation in FLAMs, we next directly tested how TGFβ alters the response to TLR2 agonists. While both TGFβ (+) and TGFβ (-) FLAMs robustly responded to TLR2 agonists, we found an unexpected activation of type I interferon (IFN) responses in TGFβ (+) FLAMs and primary AMs. Surprisingly, mitochondrial antiviral signaling protein and the IFN regulator factors 3 and 7 were required for IFN production by TLR2 agonists and the IFN response was dependent on mitochondrial reactive oxygen species. Together, these data suggest that TGFβ modulates AM metabolic networks and innate immune signaling cascades to control inflammatory pathways in AMs.
    Keywords:  alveolar macrophages; pulmonary innate immune responses; type I IFN regulation
    DOI:  https://doi.org/10.1093/jimmun/vkag090
  13. bioRxiv. 2026 May 07. pii: 2026.05.04.722733. [Epub ahead of print]
       Introduction: ApoE4 is the strongest genetic risk factor for Alzheimer's disease (AD). Emerging evidence suggests that ApoE4 increases AD risk by disrupting microglial metabolism and function. However, whether ApoE lipidation state contributes to microglial dysfunction remains poorly understood.
    Methods: Human microglia were treated with lipid-free or lipid-bound ApoE3 or ApoE4. Label-free live-cell holotomography and global proteomics were used to assess isoform- and lipidation-specific effects on lipid droplet dynamics, mitochondrial morphology, and microglial phenotype.
    Results: ApoE4 treatment resulted in fewer but enlarged lipid droplets and increased mitochondrial fragmentation compared to ApoE3, effects that were enhanced by lipid-bound ApoE4. Proteomic analyses revealed a strong type I interferon response in cells exposed to lipid-free ApoE, which was exacerbated by lipid-free ApoE4.
    Discussion: These findings indicate that lipid-bound ApoE4 drives metabolic reprogramming, whereas lipid-free ApoE4 promotes inflammatory signaling, identifying ApoE lipidation as a critical modifier of ApoE4-associated AD risk.
    DOI:  https://doi.org/10.64898/2026.05.04.722733
  14. Front Immunol. 2026 ;17 1768845
      Type 2 diabetes mellitus (T2D) features chronic low-grade inflammation in white adipose tissue (WAT), where adipocytes and innate immune cells engage in immunometabolic crosstalk. Mitochondrial damage-associated molecular patterns (mtDAMPs) released from stressed adipocytes are thought to sustain metaflammation, but how they are handled by specific macrophage subsets in human T2D WAT is unclear. We hypothesized that in T2D subcutaneous white adipose tissue (scWAT), the mitochondrial stress-clearance circuit between adipocytes and macrophages becomes maladaptive. scWAT biopsies from 6 patients with T2D and 7 non-diabetic controls were profiled by single-nucleus RNA sequencing (snRNA-seq). We integrated transcriptomic data across donors, annotated adipocyte and immune cell states, and performed differential expression analysis along with pathway and immunometabolic module scoring. To map intercellular communication and mitochondrial waste handling, we applied metabolic flux inference (COMPASS), mitochondrial-derived vesicle (MDV) and phagocytosis gene signatures, ligand-receptor analysis (CellChat), and pseudotime trajectories of lipid-associated macrophages. Macrophages and adipocytes showed the strongest T2D-associated transcriptional and metabolic rewiring. We identified a stress-enriched adipocyte state (AD3) with upregulated mitophagy, vesicle and MDV trafficking, and inflammatory signaling, whose mitochondrial-stress module overlapped genes enriched in adipocyte-derived extracellular vesicles. Among lipid-associated macrophages, we resolved a LAM-ST1 subset with immunometabolic activation but downregulation of receptors and lysosomal programs for MDV uptake and degradation. Cell-cell communication and trajectory analyses indicated that AD3 engages LAM-ST1 through inflammatory and vesicular signaling and that LAM-ST1 occupies a terminal, clearance-incompetent branch along the LAM continuum, consistent with a maladaptive mitochondrial stress-clearance response. Our human snRNA-seq analysis delineates an adipocyte-macrophage immunometabolic circuit in which mitochondrial stress in AD3 adipocytes and defective MDV clearance by LAM-ST1 macrophages jointly sustain metaflammation in T2D scWAT. These findings highlight mitochondrial waste handling by tissue-resident macrophages as a potential checkpoint for restoring adipose immune homeostasis and reducing cardiometabolic risk.
    Keywords:  immunometabolism; lipid-associated macrophages; metaflammation; mitochondrial stress; mitochondrial-derived vesicles; single-nucleus RNA sequencing; subcutaneous white adipose tissue; type 2 diabetes
    DOI:  https://doi.org/10.3389/fimmu.2026.1768845
  15. medRxiv. 2026 May 04. pii: 2026.05.03.26352309. [Epub ahead of print]
       Background: Tryptophan (Trp) metabolism is a central immunometabolic axis in inflammatory bowel disease (IBD) and has been linked to inflammatory activity and immune regulation. While individual Trp metabolites have been associated with disease severity and treatment response, systems-level frameworks to define metabolic subtypes in IBD are lacking.
    Objective: To identify reproducible Trp-related metabolic subtypes ("metabotypes") in IBD and assess their association with disease activity, clinical outcomes, and early disease development.
    Design: We applied unsupervised clustering to serum concentrations of 16 Trp-related metabolites in a discovery cohort of patients with IBD undergoing biologic induction therapy (n=134). Metabotypes were validated in three independent IBD cohorts (total n>2,800), a healthy reference population, and a prospective cohort of first-degree relatives at risk for Crohn's disease. Associations with disease activity, longitudinal outcomes, and metabolic pathways were assessed using multivariable regression and survival analysis.
    Results: Four reproducible metabotypes with distinct metabolite profiles were identified across cohorts: Low Kyna, High Kyna, High Quin, and Balanced. Low Kyna and High Quin metabotypes were consistently associated with increased inflammatory activity and adverse clinical outcomes, including increased risk of treatment escalation and disease progression.Pathway-level analyses revealed alterations in NAD-related, lipid, and amino acid pathways between inflammatory metabotypes. A metabotype resembling inflammatory disease states was enriched in individuals who later developed Crohn's disease in a prospective pre-disease cohort.
    Conclusion: Trp-linked metabotypes define reproducible immunometabolic states in IBD that associate with disease activity and clinical outcomes and may precede disease onset. These findings provide a framework for metabolic stratification and biomarker-guided clinical trials targeting immunometabolic pathways.
    What is already known on this topic: Tryptophan metabolism through the kynurenine pathway is a central immunometabolic axis in inflammatory bowel disease (IBD) and has been linked to inflammatory activity and immune regulation. Individual tryptophan metabolites have been associated with disease severity and treatment response, but their clinical utility for patient stratification remains limited. Systems-level approaches to define clinically meaningful metabolic subtypes in IBD are lacking.
    What this study adds: We identify four reproducible tryptophan-related metabolic subtypes ("metabotypes") that are consistently associated with disease activity across multiple independent IBD cohorts. Inflammation-associated metabotypes show distinct pathway-level alterations, including differences in NAD-related metabolism and broader metabolic programs. A metabotype resembling inflammatory disease states is detectable before clinical diagnosis in individuals who later develop Crohn's disease.
    How this study might affect research practice or policy: Metabotype-based classification provides a framework for molecular stratification of patients in mechanistic studies and clinical trials targeting immunometabolic pathways. This approach may support biomarker-guided monitoring of disease activity and disease progression in IBD. Identification of preclinical metabolic states highlights the potential of metabolomics for early disease detection and prevention-oriented research strategies.
    DOI:  https://doi.org/10.64898/2026.05.03.26352309
  16. Sci Immunol. 2026 May 29. 11(119): eaef0098
      Mitochondrial metabolism modulates immune cell signaling, yet how individual electron transport chain complexes fine-tune dendritic cell (DC) function remains unclear. Here, we identify mitochondrial complex I (CI) as a critical metabolic checkpoint controlling antigen cross-presentation by DCs in mice. Deficiency of the CI subunit NDUFS4 in DCs led to the formation of a nonfunctional CI subcomplex, resulting in mildly impaired mitochondrial respiration without triggering a compensatory glycolytic shift. NDUFS4 deficiency limited endosomal escape of internalized antigens, thereby impairing antigen cross-presentation while largely preserving direct presentation. CI dysfunction lowered the NAD+/NADH ratio, concomitant with decreased ATP levels, and diminished neutral lipid storage and lipid peroxidation. Restoration of the NAD+/NADH ratio rescued cross-presentation in NDUFS4-deficient DCs. NDUFS2-deficient DCs showed similar defects in cross-presentation, which were also rescued by rebalancing the NAD+/NADH ratio. Together, these findings reveal a link between mitochondrial CI integrity, NAD+-driven redox metabolism, and antigen cross-presentation.
    DOI:  https://doi.org/10.1126/sciimmunol.aef0098
  17. bioRxiv. 2026 May 10. pii: 2026.05.04.722566. [Epub ahead of print]
      Interaction with microbes can reprogram metabolism and alter nutrient availability in plant cells. How metabolic cues modulate immune responses remains unknown. Here, we show that sugar-sensing O -glycosylation of immune-signaling kinases mediates metabolic regulation of immunity. Under sugar-replete conditions, the MAP kinase kinases (MKK4 and MKK5), key components of pattern-triggered immunity (PTI), are glycosylated by O -GlcNAc and O -fucose in their activation loops and thus cannot be activated by upstream kinases, thereby restricting PTI. Pathogen infection or sugar starvation reduces O -glycosylation of MKK4/5 and enhances immune signaling; these effects are reversed by GDP-fucose treatment, demonstrating that reduced sugar availability decreases O -fucosylation and enhances immune signaling in infected cells. Chemical inhibition of O -fucosylation enhances immunity and pathogen resistance in both Arabidopsis and tomato. Our findings establish O -glycosylation of MKKs as a metabolic rheostat that fine-tunes immune responses according to sugar availability during plant-microbe interactions, providing a new strategy for improving crop health.
    DOI:  https://doi.org/10.64898/2026.05.04.722566
  18. Nat Commun. 2026 05 19. pii: 4453. [Epub ahead of print]17(1):
      Neutrophils are essential for host defense and inflammation, yet their dysfunction is a hallmark of acquired immunodeficiency in kidney disease, contributing to increased susceptibility to infections such as peritonitis, sepsis, and pneumonia. We speculated that impaired renal clearance of the metabolite soluble uric acid (sUA) accounts for neutrophil dysfunction. Indeed, hyperuricemia (HU, serum UA of 9-14 mg/dL) related or unrelated to kidney disease significantly exacerbates the inflammatory immune response in mice with endotoxemia and bacterial sepsis. Despite promoting hyperinflammation, HU simultaneously impairs host defense, an effect that is partially reversible by lowering UA levels with febuxostat. We validated these findings in vitro using neutrophils or serum from healthy individuals or hyperuricemic patients with chronic kidney disease. Depleting UA partially restores neutrophil function. Mechanistically, sUA promotes neutrophil activation and degranulation but impairs phagocytosis, leading to reduced NOX2 expression independent of intracellular MPO levels. This results in diminished ROS production and defective bacterial clearance in human neutrophils. In contrast, sUA has no impact on neutrophil extracellular trap formation following exposure to LPS or E.coli. Together, our findings identify HU as an immunometabolic regulator that amplifies hyperinflammation, while simultaneously impairing effective host defense, suggesting that targeting UA may help to overcome acquired immunodeficiency in kidney disease.
    DOI:  https://doi.org/10.1038/s41467-026-73090-4
  19. Signal Transduct Target Ther. 2026 May 19. pii: 186. [Epub ahead of print]11(1):
      Metabolic dysfunction-associated steatotic liver disease (MASLD) is driven by unresolved inflammation, yet precise mechanisms linking immune metabolism to disease progression remain elusive. Here, we identified myeloid-expressed Mas, a G protein-coupled receptor, as a critical metabolic checkpoint in MASLD. Mas expression is elevated in hepatic myeloid cells from patients and diet-induced mouse models. Myeloid-specific Mas1 deletion attenuated MASLD by restraining glycolytic reprogramming and inflammatory senescence. Single-cell RNA sequencing analyses revealed that this deletion specifically impaired the glycolytic flux and subsequent pathogenic differentiation of FN1⁺CCR2⁺ monocyte precursors. Mechanistically, Mas interacts with the glycolytic enzyme PKM2, enhancing lactate production that drives lactylation of the transcription factor Spi1 at lysine 208. Spi1-K208 lactylation promotes its nuclear localization and transcriptional activation of senescence-associated secretory phenotype (SASP) genes. Myeloid-specific Pkm2 ablation phenocopied the protective effect of Mas1 deletion, and PKM2 overexpression rescued the metabolic and transcriptional defects caused by Mas loss. Virtual screening identified theaflavin-3,3'-digallate (TFDG) as a Mas inhibitor that disrupts the Mas-PKM2 interaction. A macrophage membrane-coated nanoparticle (MM@NP-TFDG) delivered TFDG specifically to hepatic macrophages, suppressed the Mas-PKM2-Spi1 lactylation axis, and ameliorated MASLD pathology in vivo. Our findings define a novel Mas-PKM2-Spi1 lactylation axis that orchestrates glycolytic reprogramming, monocyte precursor differentiation, and macrophage-driven inflammation in MASLD, presenting a targeted nanotherapeutic strategy for its treatment.
    DOI:  https://doi.org/10.1038/s41392-026-02704-6
  20. Front Immunol. 2026 ;17 1810985
      L-arginine (ARG) availability is a critical determinant of macrophage antimicrobial capacity, as it fuels nitric oxide production and other immune effector pathways essential for restricting Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB). L-citrulline (CIT), a precursor in the ARG regeneration cycle, can replenish intracellular ARG pools when transport is limited. However, the comparative and combined effects of exogenous ARG and/or CIT on intracellular Mtb control across macrophage lineages and activation states remain insufficiently defined. This study investigated how supplementation with ARG, CIT or their combination influences Mtb survival in human and murine, primary macrophages and cell line, both in naïve and IFNγ-activated states, and evaluated whether these amino acids can enhance the activity of anti-TB drugs, isoniazid (INH) and rifampicin (RIF). Across a 5-day infection course, both ARG and CIT significantly reduced intracellular Mtb loads relative to untreated cells, with high-dose supplementation eliciting earlier and more sustained inhibition. These effects were amplified in IFNγ-stimulated macrophages, accelerating Mtb control and minimizing dose-dependent differences. Combination of ARG plus CIT at intermediate doses produced additive benefits, most notably in murine macrophages where single-agent effects were limited. Co-supplementation with ARG or CIT improved early antimicrobial effects of INH and RIF in all macrophage types, particularly under IFNγ stimulation. Gene expression analyses revealed coordinated metabolic and inflammatory reprogramming. For example, TNF expression was reduced by amino acid supplementation, while IL6 expression was increased, and NOS2 was significantly upregulated by ARG in IFNγ-stimulated cells, and ARG1 expression was broadly suppressed in these cells. These findings demonstrate that ARG and CIT reshape macrophage antimicrobial response in a complementary manner, augmenting innate and drug-enhanced control of Mtb. The results support metabolic supplementation with ARG and CIT as a promising host-directed therapeutic approach to improve macrophage-mediated restriction of Mtb infection.
    Keywords:  amino acids; antibiotics; antimicrobial response; gene expression; host directed therapy; infection; macrophages; tuberculosis
    DOI:  https://doi.org/10.3389/fimmu.2026.1810985
  21. Braz J Microbiol. 2026 May 18. pii: 146. [Epub ahead of print]57(1):
       BACKGROUND: Tuberculosis, a predominant health issue worldwide caused by Mycobacterium tuberculosis (Mtb), is refractory due to drug resistance. This study aims to explore whether Mtb reinforces M2 polarization of macrophages by modulating glutamine metabolism, thereby offering novel perspectives into its pathogenic mechanisms and potential therapeutic targets.
    METHODS: This research established an in vivo model of C57BL/6 mice infected with Mtb H37Rv, and an in vitro infection model based on RAW264.7 macrophages. The expression of M2 polarization markers and activation of the key signaling molecule STAT6 were detected via flow cytometry, immunohistochemistry, RT-qPCR, Western blot (WB), and ELISA. The levels and activity of key enzymes in glutamine metabolism were evaluated by WB and enzyme activity assays, respectively. Furthermore, intervention experiments utilizing the glutamine metabolism inhibitor BPTES were conducted to validate the function of glutamine metabolism in Mtb-induced M2 polarization.
    RESULTS: In vivo assay revealed that Mtb infection markedly promoted M2 polarization of macrophages in murine lung tissues. Flow cytometry detected an increased proportion of CD206 + macrophages, and immunohistochemical staining further confirmed elevated expression of the M2 markers Arg1 and Ym-1. In vitro experiments further confirmed that Mtb infection induced macrophage transition to the M2 phenotype and activated the glutamine metabolism pathway. Critically, the glutamine metabolism inhibitor BPTES substantially reversed Mtb-induced M2 polarization of macrophages, as evidenced by suppressed levels of M2 markers' expression and STAT6 phosphorylation. These results confirmed that glutamine metabolism was a key driver of Mtb-induced M2 macrophage polarization.
    CONCLUSION: This study demonstrates that Mtb drives the polarization of host macrophages toward an M2 phenotype favorable for pathogen survival by activating the host glutamine metabolic pathway, revealing a novel mechanism by which pathogens exploit host metabolism to achieve immune evasion.
    Keywords:   Mycobacterium tuberculosis ; Drug-resistant tuberculosis; Glutamine metabolism; Macrophages
    DOI:  https://doi.org/10.1007/s42770-026-01960-6
  22. Int J Biol Macromol. 2026 May 19. pii: S0141-8130(26)02550-X. [Epub ahead of print] 152623
      Glioblastoma (GBM) remains a highly lethal malignancy for which current treatments offer only a limited therapeutic benefit. Although vimentin (VIM) is classically regarded as a cytoskeletal protein, its role in tumour immune regulation is poorly understood. Here, we showed that extracellular tumour-derived VIM was associated with impaired CD8+ T-cell antitumour immunity and altered metabolic fitness. Single-cell RNA sequencing revealed that CD8+ T cells within VIM-high tumour microenvironments exhibited dysfunctional transcription in GBM. Functional assays revealed that VIM knockdown (VIM-KD) increased the antitumour activity of CD8+ T cells. Notably, under in vitro monoculture conditions, the modulation of VIM expression did not induce significant changes in GBM cell proliferation or apoptosis, indicating that VIM did not exert direct cytotoxic or growth-promoting effects on tumour cells. In contrast, in vivo tumour growth was strongly correlated with VIM expression levels, which was subsequently demonstrated to be mediated by CD8+ T-cell-dependent immune suppression. Metabolic analyses indicated that exposure to VIM-overexpressing (VIM-OE) tumour cells correlated with reduced triglyceride levels and decreased mitochondrial oxidative phosphorylation in CD8+ T cells. In vivo, VIM-KD mice exhibited decreased intracranial tumour growth and prolonged survival. Mechanistically, VIM stability is subject to posttranslational regulation, and we identified the deubiquitinase USP7 as a key regulator associated with maintaining VIM protein levels by limiting its proteasomal degradation. Collectively, these findings reveal a previously unrecognized USP7-VIM axis that mediates metabolic dysfunction and immune suppression in GBM, providing a mechanistic foundation for future therapeutic investigations.
    Keywords:  CD8(+) T cells; Glioblastoma; Lipid metabolism; Mitochondrial fitness; Tumour microenvironment; USP7; Vimentin
    DOI:  https://doi.org/10.1016/j.ijbiomac.2026.152623
  23. Front Immunol. 2026 ;17 1797949
      Metabolic dysfunction-associated steatohepatitis (MASH) is a major challenge in hepatology. Despite considerable progress in our understanding of MASH, the particular mechanisms underlying disease development and the variable progression among patients with similar clinical risk factors remain inadequately explained. The liver contains one of the most varied populations of resident immune cells in the body. Accumulating evidence indicates that immune activity substantially influences the clinical trajectory of hepatic diseases. Myeloid and lymphoid cell subsets respond differently to local signals, either sustaining inflammation or facilitating tissue repair and disease remission. In MASH, metabolic and immunological pathways reinforce each other, creating a self-perpetuating pathogenic circuit. The hepatic microenvironment reprograms the metabolism and function of immune cells, while aberrant immune responses intensify hepatic metabolic stress. Consequently, MASH should be recognized as an immunometabolic disorder. Immune dysregulation is not simply a secondary effect of metabolic dysfunction but a principal driver of disease progression. Therefore, immune modulation is a central therapeutic approach. Addressing the complexity of MASH requires a thorough comprehension of hepatic immune dynamics. This review examines recent findings that place immune cells at the core of MASH pathogenesis and contends that effective management should integrate metabolic and immunological perspectives.
    Keywords:  T cells; hepatic macrophages; immune dysregulation; lipid metabolism; liver inflammation; lymphocytes; obesity; oxidative stress
    DOI:  https://doi.org/10.3389/fimmu.2026.1797949
  24. Cancer Res Commun. 2026 May 20.
      Pancreatic ductal adenocarcinoma (PDAC) is characterized by an immunosuppressive tumor microenvironment (TME) that limits the efficacy of immunotherapies. Many tumor-suppressive immune cells, including inflammatory macrophage subsets, rely on glycolysis to sustain effector function; however, the pancreatic TME is relatively glucose-limited. Here, we investigated whether increasing glucose availability in the periphery, which in turn translates to increased intratumoral glucose, could enhance immune-based therapies in PDAC. In vitro, glucose restriction induced metabolic reprogramming of inflammatory (M1-like) macrophages toward an oxidative, M2-like state with reduced inflammatory effector markers. In immunocompetent mice, administration of 30% dextrose drinking water increased both peripheral and intratumoral glucose levels and modestly shifted tumor transcriptional profiles toward a more inflammatory state without altering overall immune cell abundance. When macrophage-targeting immunotherapies (CSF1R inhibition with PLX3397 or CCR2 inhibition with PF-4136309) were combined with systemic hyperglycemia, tumors exhibited a pronounced increase in iNOS⁺ M1-like macrophages, a reduction in arginase⁺ M2-like macrophages, enhanced CD8⁺ T cell infiltration, and decreased abundance of tumor-associated fibroblasts. These immunotherapies improved overall survival in immunocompetent mice bearing orthotopic pancreatic tumors only when combined with hyperglycemia. Analyses of patient samples confirmed the presence of a favorable anti-tumor immune infiltrate with elevated glucose levels. Together, these findings identify glucose availability as a key regulator of macrophage polarization and immunotherapy efficacy in PDAC.
    DOI:  https://doi.org/10.1158/2767-9764.CRC-25-0338
  25. J Neuroimmunol. 2026 May 14. pii: S0165-5728(26)00108-6. [Epub ahead of print]418 578960
      Müller glia are pivotal in providing a pro-survival environment for retinal cells and a sustainable energy metabolism is essential for upholding Müller glia functions. Changes in metabolic shifts impact on immune cell physiology. HIV-associated chronic, low-grade inflammation disrupts the metabolic machinery of the immune system promoting a state of neurodegeneration, and can also contribute to comorbidities. Here we show in an in vitro model of retinal Müller glia, induction of highly glycolytic activity upon activation. Increased oxidative stress in recombinant HIV-1 TAT activated Müller glia start as early changes, reflected in Redox functions, mitochondrial staining and 8 hydroxy 2-deoxy guanosine. Glucose transporter 1 expression, glucose uptake and glycolytic activity prominently increase in activated cells. This is also reflected in the microarray data where genes associated with metabolism and mitochondrial function along with those associated with aging are differentially regulated in activated Müller glia. In Müller glia, Glut 1 and IL1 increase with TAT. Transcriptomic data in activated Müller glia show changes in the PI3K/AKT pathway. Inhibition of PI3K/AKT reverses this increase. A clearer insight into metabolic changes in the presence of inflammatory signals at the retina can aid in understanding HIV associated retinal comorbidities.
    Keywords:  Glucose transporter; HIV-1 TAT; Metabolism; Müller glia; Oxidative stress; PI3K/AKT; Retina
    DOI:  https://doi.org/10.1016/j.jneuroim.2026.578960
  26. Adv Sci (Weinh). 2026 May 19. e20519
      In rheumatoid arthritis (RA), regulatory T cells (Tregs) within the synovium present a paradox: they are numerically enriched yet functionally impaired, leading to a loss of immune tolerance. Here, we report that synovial iron overload establishes a ferroptosis-permissive microenvironment that disrupts Treg homeostasis. Exposure to RA synovial fluid induced ferroptosis, autoimmune Treg-associated metabolic shifts through lipid peroxide-driven mitochondrial dysfunction, characterized by electron transport chain (ETC) collapse and impaired oxidative phosphorylation. Mechanistically, metabolic disturbance by ferroptotic stress or complex III blockade triggered TXK kinase upregulation, which is required for the phosphorylation of STAT3 (Tyr705) and PLCγ1 (Tyr783), activating a proinflammatory transcriptional program that destabilized Treg identity and promoted Th17-like conversion. Crucially, this pathogenic reprogramming was reversed through iron chelation or TXK inhibition in vitro and in vivo. Our findings unveil a ferroptosis-ETC-TXK/STAT3 axis as a core mechanism of synovial Treg failure. Targeting synovial iron homeostasis or inhibiting TXK signaling thus represents a promising therapeutic strategy to restore immune tolerance in RA by rescuing Treg functionality.
    Keywords:  OXPHOS; autoimmunity; electron transport chain; ferroptosis; regulatory T cell; rheumatoid arthritis
    DOI:  https://doi.org/10.1002/advs.202520519
  27. Nat Commun. 2026 May 21.
      The metabolic basis of tumor-associated macrophages (TAMs)-driven immune checkpoint blockade (ICB) resistance remains poorly understood. Here, in patients with immunotherapy-resistant cancer, we identify significant enrichment of TAMs marked by elevated aldehyde dehydrogenase 2 (ALDH2) expression. Myeloid-restricted ALDH2 ablation converts TAMs from a pro-tumorigenic phenotype to immunostimulatory regulators, concomitantly amplifying CD8+ T cell infiltration and cytotoxicity to improve ICB responsiveness. Mechanistically, ALDH2 deficiency induces the intracellular accumulation of reactive aldehydes, specifically 4-hydroxynonenal, which activates the PI3K-AKT signaling axis. This pathway phosphorylates and suppresses EZH2 methyltransferase activity, leading to the erosion of H3K27me3-mediated epigenetic silencing at CXCL9 promoter region. Subsequent CXCL9 derepression in TAMs facilitates persistent CD8+ T cell infiltration and enhances their cytotoxic effector functions. Clinical validation confirms that pronounced ALDH2 elevation in TAMs correlates with accelerated immunotherapy failure. Therapeutically, as a clinically approved ALDH2 inhibitor, disulfiram exerts its anti-tumor effect by selective reprogramming TAMs metabolism. Overall, our findings delineate a druggable ALDH2-metabolism-epigenetics axis in antitumor immunity, nominating ALDH2 inhibition for combination immunotherapy.
    DOI:  https://doi.org/10.1038/s41467-026-73234-6
  28. Nat Immunol. 2026 May 18.
      Inflammatory responses are associated with recruitment of monocyte-derived cells (Mdcs) into tissues. Although tissue-specific Mdc reprogramming is well established, how Mdc infiltration alters tissue metabolism remains unclear. Here, using a mouse neuroinflammation model coupled with genetic fate mapping, metabolomics and metabolite imaging, we identify that central nervous system (CNS) Mdc infiltration is associated with substantial metabolic changes and assign disease-linked metabolites therein. In particular, we found that increased arginine catabolism driven by lesion-associated arginase 1 (Arg1)-expressing Mdcs promoted oxidative damage, lipid accumulation and Mdc dysfunction. Genetic ARG1 deficiency within Mdcs during neuroinflammation increased extracellular arginine and was associated with rewiring of the CNS metabolic landscape, including attenuated disease-linked metabolites. This was accompanied by enhanced Mdc-driven anti-inflammation, regulatory T cell expansion and improved disease outcome. Opposing effects were observed following dietary arginine deficiency. Together, our work highlights key roles for Mdcs in CNS metabolism and reveals the pleiotropic beneficial effects of arginine in neuroinflammation.
    DOI:  https://doi.org/10.1038/s41590-026-02516-4
  29. Nat Metab. 2026 May 18.
      Loss of host-microbiota balance promotes gut inflammation, colitis and inflammatory bowel disease. Yet, whether host or microbial factors are the critical driver of the pathology remains unclear. Here, we investigate how cardiolipin maintains metabolic fitness of regulatory T (Treg) cells to preserve gut-immune homeostasis. We discover that deleting the cardiolipin-synthesizing enzyme protein tyrosine phosphatase mitochondrial 1 (PTPMT1) in T cells predisposes mice to colitis due to impaired Treg cell function in the absence of dysbiosis. Subsequent pathobiont infections accelerate the progression and severity of gut inflammation. Mechanistically, the absence of cardiolipin impairs Treg cell metabolic fitness and triggers a maladaptive integrated stress response, which can be reversed pharmacologically or genetically, restoring gut homeostasis and extending lifespan in PTPMT1 ΔT mice. Barth syndrome, a genetic disorder marked by severe cardiolipin deficiency, also exhibits gastrointestinal symptoms and inflammation associated with helper T cell imbalance and an active integrated stress response signature. Overall, these results suggest that a cardiolipin-mediated mitonuclear axis in T cells preserves gut-immune homeostasis and dictates outcome in pathobiont infections.
    DOI:  https://doi.org/10.1038/s42255-026-01533-9
  30. J Transl Med. 2026 May 22.
       BACKGROUND: Innate immune-driven neuroinflammation in the spinal cord is a key mechanism underlying neuropathic pain (NP). Increasing evidence indicates that mitochondrial dysfunction and metabolic stress critically influence inflammatory responses. However, the mechanistic link between mitochondrial impairment and persistent neuroinflammation in NP remains incompletely understood.
    METHODS: A peripheral nerve injury model was used to induce NP in mice. Mitochondrial integrity, mitochondrial DNA (mtDNA) release, and activation of the cGAS-STING-IRF3 pathway were examined in the spinal cord using immunofluorescence, molecular analyses, and single-cell RNA sequencing. Genetic silencing of CMPK2 was achieved by adeno-associated virus delivery, and pharmacological inhibition was performed using nordihydroguaiaretic acid (NDGA). Pain-related behaviors were assessed in vivo. Complementary in vitro experiments were conducted in BV2 cells and primary microglia to evaluate mitochondrial function and mtDNA-driven innate immune activation.
    RESULTS: Peripheral nerve injury induced mitochondrial damage in the spinal cord, accompanied by cytosolic mtDNA release and activation of cGAS-STING-IRF3 signaling. IRF3 was observed to associate with the CMPK2 promoter and regulate CMPK2 transcription, consistent with a potential feedback mechanism that may exacerbate mitochondrial stress, enhance mtDNA release, and sustain innate immune activation. Single-cell RNA sequencing and immunofluorescence analyses revealed that CMPK2 was expressed in multiple spinal cord cell types, with microglia representing a major population contributing to CMPK2 upregulation in the spinal dorsal horn after nerve injury. Genetic silencing or pharmacological inhibition of CMPK2 was associated with reduced cGAS-STING signaling, improved mitochondrial homeostasis, decreased microglial activation, and attenuation of NP-like behaviors in vivo. Consistently, CMPK2 knockdown in microglia attenuated mtDNA-induced innate immune activation and improved mitochondrial function in vitro.
    CONCLUSIONS: These findings support a model in which an mtDNA-cGAS-STING-IRF3-CMPK2-associated immunometabolic feedback mechanism operates within the spinal cord microenvironment, with notable microglial involvement, linking mitochondrial dysfunction to sustained neuroinflammation and NP. Targeting mitochondrial immunometabolism may represent a potential therapeutic strategy for chronic inflammatory conditions characterized by persistent innate immune activation.
    Keywords:  CMPK2; Immunometabolism; Microglia; Mitochondrial dysfunction; Neuroinflammation; Neuropathic pain; cGAS-STING; mtDNA
    DOI:  https://doi.org/10.1186/s12967-026-08314-8
  31. Nat Commun. 2026 May 22.
      While iron homeostasis in cancer cells is well-established, its role in mediating crosstalk between tumors and CD8+ T cells within the tumor microenvironment (TME) remains largely elusive. In this study, we compare iron levels across primary tissues populated by CD8+ T cells. Contrary to the systemic iron deficiency commonly found in cancer patients, the TME exhibits marked iron enrichment compared to lymphatic fluid and peripheral blood, a phenomenon primarily attributed to tumor necrosis. However, this iron-overloaded TME is detrimental to CD8+ T cells, triggering their ferroptosis and dysfunction. Mechanistically, tumoral T cell receptor (TCR) hyperactivation and tumor-derived hepcidin cooperatively downregulate the iron exporter SLC40A1 in CD8+ T cells, leading to intracellular iron accumulation and ferroptosis. Both genetic restoration of SLC40A1 and iron chelation inhibit CD8+ T cell ferroptosis and restore their cytotoxic activity, thereby suppressing tumor growth. Finally, to enhance chimeric antigen receptor T (CAR-T) cell adaptability to the iron-overloaded TME, we engineer SLC40A1-overexpressing CAR-T cells. These engineered cells resist ferroptosis induced by the TME and elicit potent anti-tumor immunity.
    DOI:  https://doi.org/10.1038/s41467-026-73379-4
  32. Front Immunol. 2026 ;17 1793865
      Non-infectious uveitis encompasses a diverse array of autoimmune ocular disorders marked by the breakdown of immune tolerance and recurrent inflammatory episodes. Regulatory T cells (Tregs) are integral to the maintenance of ocular homeostasis in all subtypes of this condition. However, Behçet's disease, Vogt-Koyanagi-Harada (VKH) disease, and HLA-B27-associated uveitis exhibit distinct patterns of Treg quantitative reduction, lineage instability, and functional exhaustion. Tregs play a crucial role in maintaining ocular homeostasis; however, their quantitative reduction, lineage instability, and functional exhaustion significantly contribute to the persistence of the disease. This review provides a systematic synthesis of the molecular and immunometabolic mechanisms underlying Treg exhaustion in uveitis, emphasizing both universal pathways and subtype-specific mechanisms. We examine critical intrinsic regulators of Treg fitness, including the multidimensional control of FoxP3 stability, the upregulation of inhibitory checkpoints such as TIGIT and PD-1, and the dysregulated plasticity within the Th17/Treg axis. Additionally, the review emphasizes how extrinsic microenvironmental factors influence Treg functionality, with a specific focus on adenosine A2A receptor (A2Ar) signaling, circadian rhythm disruption mediated by the clock gene Per1, and the immunomodulatory role of gut microbiota. Regarding therapeutic strategies, we evaluate recent advances in restoring Treg competence, including immune checkpoint agonists, metabolic reprogramming agents (e.g., Itaconate), and traditional herbal formulations.
    Keywords:  TIGIT; Th17/Treg balance; autoimmune; molecular mechanisms; regulatory T cells (Tregs); therapeutic strategies; uveitis
    DOI:  https://doi.org/10.3389/fimmu.2026.1793865
  33. bioRxiv. 2026 May 07. pii: 2026.05.04.722661. [Epub ahead of print]
      Macrophages play a central role in determining the outcomes of healing, coordinating regeneration in some injuries and scar formation in others. In both cases, this coordination involves the cross-talk between macrophages and surrounding cells. But what drives the different cross-communication pathways to determine healing outcomes is not well known. In this study, we make use of the mouse digit tip amputation model, in which an amputation through the third phalangeal element (P3) is able to completely regenerate whereas an amputation through the second phalangeal element (P2) forms a scar. We identify a population of macrophages that is specific to the P3 regenerating digit. By integrating single-cell RNAseq, spatial transcriptomics, and metabolomic analyses, we show that this population localizes specifically to the growing bone front, express BMP ligands that drive downstream BMP activation in neighboring osteoblasts and is governed by a two-part metabolic switch involving increased fatty acid oxidation coupled with reduced glycolytic activity. This spatially restricted, BMP-expressing macrophage population is entirely absent in the scar-forming P2 injury, and our data indicate that environmental conditions unique to the regenerating digit are responsible for its emergence. Together these findings identify a regeneration-specific macrophage signaling center for patterned bone formation and suggest that targeting the metabolic conditions that drive this population could improve the efficacy of regenerative therapies.
    DOI:  https://doi.org/10.64898/2026.05.04.722661
  34. Cell Mol Immunol. 2026 May 20.
      Mitochondrial dysfunction is a critical factor driving the exhaustion of tumor-infiltrating CD8+ T cells and impeding the efficacy of tumor immunotherapy. However, the key regulatory proteins and molecular mechanisms governing mitochondrial function in CD8+ T cells remain enigmatic. Here, we report that PARK7 is significantly enriched in the mitochondria of tumor-infiltrating CD8+ T cells. T-cell-specific PARK7 deficiency enhanced mitochondrial function in CD8+ T cells, alleviated T-cell exhaustion, and suppressed tumor growth. Mechanistically, we found that PARK7 directly interacted with the mitochondrial membrane protein ATAD3A and downregulated its lactylation level, thereby suppressing the expression of mitochondrial-related genes and ultimately promoting CD8+ T-cell exhaustion. Overall, our study not only identifies the critical role of PARK7 in regulating mitochondrial function in CD8+ T cells but also elucidates the molecular mechanism through which the PARK7-ATAD3A axis modulates mitochondrial gene expression, providing a potential therapeutic strategy for targeting PARK7 in tumor immunotherapy.
    Keywords:  ATAD3A; CD8+ T-cell exhaustion; Lactylation; Mitochondria; PARK7
    DOI:  https://doi.org/10.1038/s41423-026-01425-8
  35. J Immunol. 2026 May 14. pii: vkag085. [Epub ahead of print]215(5):
      NLRP3 inflammasome activation drives interleukin (IL)-1β and IL-18 cleavage and secretion and induces pyroptosis. The ketone body β-hydroxybutyrate (BHB), produced during metabolic stress such as caloric insufficiency, has been reported to inhibit this pathway. However, the conditions that enable this effect, and whether it extends to other short-chain carboxylic acids (SCCAs), are not well defined. Using adenosine triphosphate-stimulated J774 mouse macrophages and human peripheral blood mononuclear cells, we quantified IL-1β secretion to determine the pH dependence of BHB and related SCCAs in inhibiting NLRP3 activation. Both enantiomers of β-hydroxybutyric acid (BHBA) inhibited IL-1β secretion, whereas sodium β-hydroxybutyrate (NaBHB) and sodium hydroxide-neutralized BHBA did not. Acidifying NaBHB stock solutions or the treatment media, or allowing endogenous acidification during cell culture, restored NaBHB's ability to inhibit NLRP3 activation. Several other 3- to 6-carbon SCCAs also inhibited inflammasome activation in a pH-dependent manner and prevented pyroptotic cell death. Activation of the free fatty acid receptor 3 (GPR41/FFAR3) both mimicked and enhanced the inhibitory effects of BHBA. Together, these findings demonstrate that acidic conditions enable BHB and multiple SCCAs to suppress NLRP3 inflammasome activation, partly through GPR41/FFAR3. This expands the set of metabolites that can modulate this key proinflammatory pathway during energetic stress and suggests optimized conditions for the potential therapeutic use of ketone bodies as anti-inflammatory agents.
    Keywords:  NLRP3 inflammasome; beta-hydroxybutyrate; inflammation; ketone bodies; macrophage
    DOI:  https://doi.org/10.1093/jimmun/vkag085
  36. Nat Commun. 2026 May 21.
      Pathogenic bacteria frequently manipulate host cell death pathways to facilitate infection, though the precise mechanisms remain elusive. Here, we demonstrate that pathogenic Escherichia coli disrupts copper homeostasis through upregulation of copper transporter CTR2, thereby triggering cuproptosis to drive infectious pathology. During infection, circulating lipopolysaccharide activates the morphological hallmarks of cuproptosis via the gut-LPS-liver axis. Furthermore, mitochondrial malate dehydrogenase 2 (MDH2) functions as a transcriptional regulator, triggering CTR2 expression and metabolic reprogramming via acetylation-dependent nuclear translocation in response to infection. Notably, inhibiting cuproptosis mitigates liver damage caused by infection, highlighting its critical role in pathogen-host interactions. These findings identify a mechanism underlying E. coli pathogenesis and support therapeutic approaches based on targeted modulation of metal-dependent cell death.
    DOI:  https://doi.org/10.1038/s41467-026-73280-0