Gut. 2026 Sep 7:gutjnl-2025-337414. doi: 10.1136/gutjnl-2025-337414. Online ahead of print.

ABSTRACT

BACKGROUND: Neutrophils are increasingly recognised as immunosuppressive drivers of hepatocellular carcinoma (HCC), yet their persistence in the oxidative, lipid-rich tumour microenvironment remains poorly understood.

OBJECTIVE: To elucidate the metabolic and molecular programmes that enable tumour-associated neutrophils (TANs) to resist ferroptosis and sustain immunosuppression in HCC.

DESIGN: We employed human HCC samples, multiple murine HCC models, transcriptomic and lipidomic profiling, genetic loss-of-function systems and therapeutic interventions. Ferroptosis sensitivity, lipid metabolic rewiring and immunological consequences of TANs were systematically evaluated across models and validated in patient datasets and biospecimens.

RESULTS: TANs in human HCC and mouse models exhibit pronounced lipid accumulation and oxidative stress compared with peripheral neutrophils. Multi-omic profiling revealed that TANs are enriched for lipid-binding gene programmes and undergo rewiring towards sphingolipid and unsaturated fatty acid metabolism. We identified triggering receptor expressed on myeloid cells 2 (TREM2) as a key lipid-sensing receptor selectively expressed in TANs. Functional deletion of TREM2 reprogrammed the tumour immune microenvironment, restoring CD8⁺ T cell activity and suppressing HCC progression. Mechanistically, tumour-derived sphingosine-1-phosphate (S1P) activates TREM2, triggering nuclear factor erythroid 2-related factor 2 (NRF2)-mediated transcription of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), thereby promoting ferroptosis resistance. TREM2 expression is transcriptionally induced by granulocyte-macrophage colony-stimulating factor-signal transducer and activator of transcription 3 (GM-CSF-STAT3) signalling. Genetic deletion of TREM2, clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated knockout of sphingosine kinase 1/2 (SPHK1/2) in tumour cells, or pharmacological inhibition of S1P synthesis disrupts this protective lipid-immune circuit, sensitises TANs to ferroptosis and restricts tumour growth. Therapeutically, a peptide-based TREM2 inhibitor reprogrammes TANs, restores CD8⁺ T cell function and enhances anti-programmed cell death protein 1 (PD-1) immunotherapy efficacy. Clinically, TREM2⁺ polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are enriched in HCC tumours, correlate with SPHK1/2 expression and T cell dysfunction and associate with poor patient prognosis.

CONCLUSION: Our study uncovers the S1P-TREM2-NRF2 axis as a critical metabolic-immune circuit that preserves neutrophil survival and immunosuppressive function in HCC. Targeting this lipid-dependent ferroptosis resistance pathway offers a promising therapeutic strategy to overcome immunotherapy resistance in liver cancer.

PMID:42705697 | DOI:10.1136/gutjnl-2025-337414

Gut. 2026 Sep 7:gutjnl-2025-337414. doi: 10.1136/gutjnl-2025-337414. Online ahead of print.

ABSTRACT

BACKGROUND: Neutrophils are increasingly recognised as immunosuppressive drivers of hepatocellular carcinoma (HCC), yet their persistence in the oxidative, lipid-rich tumour microenvironment remains poorly understood.

OBJECTIVE: To elucidate the metabolic and molecular programmes that enable tumour-associated neutrophils (TANs) to resist ferroptosis and sustain immunosuppression in HCC.

DESIGN: We employed human HCC samples, multiple murine HCC models, transcriptomic and lipidomic profiling, genetic loss-of-function systems and therapeutic interventions. Ferroptosis sensitivity, lipid metabolic rewiring and immunological consequences of TANs were systematically evaluated across models and validated in patient datasets and biospecimens.

RESULTS: TANs in human HCC and mouse models exhibit pronounced lipid accumulation and oxidative stress compared with peripheral neutrophils. Multi-omic profiling revealed that TANs are enriched for lipid-binding gene programmes and undergo rewiring towards sphingolipid and unsaturated fatty acid metabolism. We identified triggering receptor expressed on myeloid cells 2 (TREM2) as a key lipid-sensing receptor selectively expressed in TANs. Functional deletion of TREM2 reprogrammed the tumour immune microenvironment, restoring CD8⁺ T cell activity and suppressing HCC progression. Mechanistically, tumour-derived sphingosine-1-phosphate (S1P) activates TREM2, triggering nuclear factor erythroid 2-related factor 2 (NRF2)-mediated transcription of glutathione peroxidase 4 (GPX4) and solute carrier family 7 member 11 (SLC7A11), thereby promoting ferroptosis resistance. TREM2 expression is transcriptionally induced by granulocyte-macrophage colony-stimulating factor-signal transducer and activator of transcription 3 (GM-CSF-STAT3) signalling. Genetic deletion of TREM2, clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-mediated knockout of sphingosine kinase 1/2 (SPHK1/2) in tumour cells, or pharmacological inhibition of S1P synthesis disrupts this protective lipid-immune circuit, sensitises TANs to ferroptosis and restricts tumour growth. Therapeutically, a peptide-based TREM2 inhibitor reprogrammes TANs, restores CD8⁺ T cell function and enhances anti-programmed cell death protein 1 (PD-1) immunotherapy efficacy. Clinically, TREM2⁺ polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are enriched in HCC tumours, correlate with SPHK1/2 expression and T cell dysfunction and associate with poor patient prognosis.

CONCLUSION: Our study uncovers the S1P-TREM2-NRF2 axis as a critical metabolic-immune circuit that preserves neutrophil survival and immunosuppressive function in HCC. Targeting this lipid-dependent ferroptosis resistance pathway offers a promising therapeutic strategy to overcome immunotherapy resistance in liver cancer.

PMID:42705697 | DOI:10.1136/gutjnl-2025-337414

Signal Transduct Target Ther. 2026 Sep 4;11(1):363. doi: 10.1038/s41392-026-02936-6.

ABSTRACT

Metabolic reprogramming forms the foundation of immune effector functions and the regulation of inflammation. As a pivotal node connecting the tricarboxylic acid cycle to immune signaling, the IRG1/ACOD1 and itaconate axes play a central role in coordinating inflammatory tone and redox balance. Itaconate, generated through the decarboxylation of cis aconitate, acts as an immunometabolic brake that engages multiple regulatory pathways to sustain the dynamic equilibrium between inflammation and tissue homeostasis. Across a broad spectrum of pathological conditions, including infectious diseases, metabolic disorders, ischemia‒reperfusion injury, neurodegenerative diseases, autoimmune disorders, and cancers, itaconate and its derivatives generally exert anti-inflammatory and cytoprotective effects. However, within specific microenvironments, these molecules may also be exploited by pathogens to evade immune clearance or promote immunosuppressive and protumorigenic responses. Future studies should further elucidate tissue- and lineage-specific functions, define bidirectional regulatory mechanisms, and optimize the pharmacokinetic properties of itaconate derivatives. With the advancement of multiomics integration, systems immunology, rational drug design, and engineered itaconate delivery technologies, the IRG1/ACOD1-itaconate axis and derivative-based therapeutic strategies are poised to emerge as key metabolic checkpoints and therapeutic targets in inflammatory-, metabolic-, immune-, and cancer-related diseases.

PMID:42693110 | PMC:PMC13542262 | DOI:10.1038/s41392-026-02936-6

J Hazard Mater. 2026 Sep 15;516:143449. doi: 10.1016/j.jhazmat.2026.143449. Epub 2026 Aug 30.

ABSTRACT

The global incidence of ulcerative colitis (UC) has significantly increased in rapidly industrializing nations, with numerous studies highlighting environmental exposures, particularly nitrogen dioxide (NO₂), as potential contributors to disease susceptibility. However, the clinical implications and molecular mechanisms linking NO₂ exposure to UC susceptibility remain poorly understood. This study investigated the associations between NO₂ and UC by integrating multi-omics data. We identified a CD8⁺ T cell subpopulation with a distinct phenotype characterized by perforin production, which potentially exacerbated colonic inflammation related to NO₂ exposure. To validate this hypothesis, we established mouse models exposed to NO₂, confirming increased CD8⁺ T cell infiltration and elevated perforin secretion through immunofluorescent (IF) staining. Employing artificial intelligence techniques, we identified Cell Division Cycle 25B (CDC25B) as a gene of interest correlated with putative NO₂-related UC signatures. Finally, through molecular docking (MD) and molecular dynamics simulations (MDS), we identified ozanimod as one of several computationally nominated compounds associated with the CDC25B‑related network; however, none of these computational predictions were experimentally validated in the present study. Collectively, these findings suggest a correlative link between perforin or CD8⁺ T cell-associated colonic inflammation and NO₂-associated UC susceptibility, and nominate CDC25B as a candidate gene for further investigation.

PMID:42679583 | DOI:10.1016/j.jhazmat.2026.143449