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S1P-TREM2 axis protects immunosuppressive neutrophils from ferroptosis to promote tumour progression in hepatocellular carcinoma
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
S1P-TREM2 axis protects immunosuppressive neutrophils from ferroptosis to promote tumour progression in hepatocellular carcinoma
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
Nonlinear atomic tunnelling boosted by bright squeezed vacuum
Nature, Published online: 20 May 2026; doi:10.1038/s41586-026-10485-9
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Catgut implantation at acupoints improves anti-PD-1 inhibitor efficacy in lung cancer by inducing immune responses and remodeling the tumor microenvironment
Cancer Immunol Immunother. 2026 Mar 31;75(4):126. doi: 10.1007/s00262-026-04368-1.
ABSTRACT
While anti-programmed death-1 (anti-PD-1) therapy has revolutionized lung cancer treatment, its efficacy remains limited by an immunosuppressive tumor microenvironment (TME). We therefore investigated whether combining anti-PD-1 inhibitor with catgut embedding at the Zusanli acupoint (CIAA) could enhance anti-tumor immunity by reprogramming the TME in a lung cancer mouse model. Combining in vivo tumor monitoring, multi-parametric immune profiling (flow cytometry, IHC, ELISA), and multi-omics analyses (transcriptomics and metabolomics), we found that the combination therapy was associated with enhanced tumor growth inhibition. This effect correlated with a comprehensive TME transformation: conversion to an immunologically active state with increased effector immune cell infiltration (CD8⁺ T, CD4⁺ T, B cells, macrophages) and decreased regulatory T cells, coupled with suppression of pro-tumorigenic factors (VEGF, IL-6). Integrated omics analysis suggests that the combined treatment may modulate tumor-stroma interaction pathways (e.g., PI3K-Akt, focal adhesion) and rewire immunometabolic networks (e.g., tryptophan metabolism). Our study provides hypothesis-generating correlative data positioning CIAA as a potential adjunct capable of remodeling the TME to potentiate anti-PD-1 therapy in lung cancer.
PMID:41915222 | PMC:PMC13038699 | DOI:10.1007/s00262-026-04368-1
Catgut implantation at acupoints improves anti-PD-1 inhibitor efficacy in lung cancer by inducing immune responses and remodeling the tumor microenvironment
Cancer Immunol Immunother. 2026 Mar 31;75(4):126. doi: 10.1007/s00262-026-04368-1.
ABSTRACT
While anti-programmed death-1 (anti-PD-1) therapy has revolutionized lung cancer treatment, its efficacy remains limited by an immunosuppressive tumor microenvironment (TME). We therefore investigated whether combining anti-PD-1 inhibitor with catgut embedding at the Zusanli acupoint (CIAA) could enhance anti-tumor immunity by reprogramming the TME in a lung cancer mouse model. Combining in vivo tumor monitoring, multi-parametric immune profiling (flow cytometry, IHC, ELISA), and multi-omics analyses (transcriptomics and metabolomics), we found that the combination therapy was associated with enhanced tumor growth inhibition. This effect correlated with a comprehensive TME transformation: conversion to an immunologically active state with increased effector immune cell infiltration (CD8⁺ T, CD4⁺ T, B cells, macrophages) and decreased regulatory T cells, coupled with suppression of pro-tumorigenic factors (VEGF, IL-6). Integrated omics analysis suggests that the combined treatment may modulate tumor-stroma interaction pathways (e.g., PI3K-Akt, focal adhesion) and rewire immunometabolic networks (e.g., tryptophan metabolism). Our study provides hypothesis-generating correlative data positioning CIAA as a potential adjunct capable of remodeling the TME to potentiate anti-PD-1 therapy in lung cancer.
PMID:41915222 | DOI:10.1007/s00262-026-04368-1