bims-mepmim 2024-07-14 papers

bims-mepmim

Biomed News

on Metabolites in pathological microenvironments and immunometabolism

Issue of 2024‒07‒14
thirteen papers selected by
Erika Mariana Palmieri, NIH/NCI Laboratory of Cancer ImmunoMetabolism

Feedforward cysteine regulation maintains melanoma differentiation state and limits metastatic spread.
Rv0547c, a functional oxidoreductase, supports Mycobacterium tuberculosis persistence by reprogramming host mitochondrial fatty acid metabolism.
Dysregulation of hepatic one-carbon metabolism in classical homocystinuria: Implications of redox-sensitive DHFR repression and tetrahydrofolate depletion for pathogenesis and treatment.
Pressure sensing of lysosomes enables control of TFEB responses in macrophages.
Metabolic gene function discovery platform GeneMAP identifies SLC25A48 as necessary for mitochondrial choline import.
Inhibition of DUSP18 impairs cholesterol biosynthesis and promotes anti-tumor immunity in colorectal cancer.
Classical monocyte ontogeny dictates their functions and fates as tissue macrophages.
ATP6V0A1-dependent cholesterol absorption in colorectal cancer cells triggers immunosuppressive signaling to inactivate memory CD8+ T cells.
Peridroplet mitochondria are associated with the severity of MASLD and the prevention of MASLD by diethyldithiocarbamate.
TNF compromises intestinal bile-acid tolerance dictating colitis progression and limited infliximab response.
Single-cell resolution characterization of myeloid-derived cell states with implication in cancer outcome.
Palmitoylation at a conserved cysteine residue facilitates gasdermin D-mediated pyroptosis and cytokine release.
Glutamine metabolic competition drives immunosuppressive reprogramming of intratumour GPR109A+ myeloid cells to promote liver cancer progression.

Cell Rep. 2024 Jul 10. pii: S2211-1247(24)00813-1. [Epub ahead of print]43(7): 114484

Feedforward cysteine regulation maintains melanoma differentiation state and limits metastatic spread.

Deyang Yu, Jiaxin Liang, Hans R Widlund, Pere Puigserver.

  The inherent ability of melanoma cells to alter the differentiation-associated transcriptional repertoire to evade treatment and facilitate metastatic spread is well accepted and has been termed phenotypic switching. However, how these facets of cellular behavior are controlled remains largely elusive. Here, we show that cysteine availability, whether from lysosomes (CTNS-dependent) or exogenously derived (SLC7A11-dependent or as N-acetylcysteine), controls melanoma differentiation-associated pathways by acting on the melanocyte master regulator MITF. Functional data indicate that low cysteine availability reduces MITF levels and impairs lysosome functions, which affects tumor ferroptosis sensitivity but improves metastatic spread in vivo. Mechanistically, cysteine-restrictive conditions reduce acetyl-CoA levels to decrease p300-mediated H3K27 acetylation at the melanocyte-restricted MITF promoter, thus forming a cysteine feedforward regulation that controls MITF levels and downstream lysosome functions. These findings collectively suggest that cysteine homeostasis governs melanoma differentiation by maintaining MITF levels and lysosome functions, which protect against ferroptosis and limit metastatic spread.

Keywords:  CP: Cancer; cell death; cysteine; lysosome; melanoma; metastasis

DOI:  https://doi.org/10.1016/j.celrep.2024.114484
Mitochondrion. 2024 Jul 08. pii: S1567-7249(24)00089-8. [Epub ahead of print] 101931

Rv0547c, a functional oxidoreductase, supports Mycobacterium tuberculosis persistence by reprogramming host mitochondrial fatty acid metabolism.

Jayashankar Medikonda, Nandini Wankar, Suman Asalla, Sufi O Raja, Sriram Yandrapally, Haneesh Jindal, Anushka Agarwal, Chitrakshi Pant, Shasi V Kalivendi, Harish Kumar Dubey, Krishnaveni Mohareer, Akash Gulyani, Sharmistha Banerjee.

  Mycobacterium tuberculosis (Mtb) successfully thrives in the host by adjusting its metabolism and manipulating the host environment. In this study, we investigated the role of Rv0547c, a protein that carries mitochondria-targeting sequence (MTS), in mycobacterial persistence. We show that Rv0547c is a functional oxidoreductase that targets host-cell mitochondria. Interestingly, the localization of Rv0547c to mitochondria was independent of the predicted MTS but depended on specific arginine residues at the N- and C-terminals. As compared to the mitochondria-localization defective mutant, Rv0547c-2SDM, wild-type Rv0547c increased mitochondrial membrane fluidity and spare respiratory capacity. To comprehend the possible reason, comparative lipidomics was performed that revealed a reduced variability of long-chain and very long-chain fatty acids as well as altered levels of phosphatidylcholine and phosphatidylinositol class of lipids upon expression of Rv0547c, explaining the increased membrane fluidity. Additionally, the over representation of propionate metabolism and β-oxidation intermediates in Rv0547c-targeted mitochondrial fractions indicated altered fatty acid metabolism, which corroborated with changes in oxygen consumption rate (OCR) upon etomoxir treatment in HEK293T cells transiently expressing Rv0547c, resulting in enhanced mitochondrial fatty acid oxidation capacity. Furthermore, Mycobacterium smegmatis over expressing Rv0547c showed increased persistence during infection of THP-1 macrophages, which correlated with its increased expression in Mtb during oxidative and nutrient starvation stresses. This study identified for the first time an Mtb protein that alters mitochondrial metabolism and aids in survival in host macrophages by altering fatty acid metabolism to its benefit and, at the same time increases mitochondrial spare respiratory capacity to mitigate infection stresses and maintain cell viability.

Keywords:  FAO; Lipid metabolism; Lipid profiling; Metabolic flux; Mycobacterium tuberculosis; Oxidoreductase; Rv0547c

DOI:  https://doi.org/10.1016/j.mito.2024.101931
FASEB J. 2024 Jul 15. 38(13): e23795

Dysregulation of hepatic one-carbon metabolism in classical homocystinuria: Implications of redox-sensitive DHFR repression and tetrahydrofolate depletion for pathogenesis and treatment.

Kenneth N Maclean, Hua Jiang, Philip D Neill, Ryan R Chanin, K Joseph Hurt, David J Orlicky, Teodoro Bottiglieri, James R Roede, Sally P Stabler.

  Cystathionine beta-synthase-deficient homocystinuria (HCU) is a life-threatening disorder of sulfur metabolism. HCU can be treated by using betaine to lower tissue and plasma levels of homocysteine (Hcy). Here, we show that mice with severely elevated Hcy and potentially deficient in the folate species tetrahydrofolate (THF) exhibit a very limited response to betaine indicating that THF plays a critical role in treatment efficacy. Analysis of a mouse model of HCU revealed a 10-fold increase in hepatic levels of 5-methyl -THF and a 30-fold accumulation of formiminoglutamic acid, consistent with a paucity of THF. Neither of these metabolite accumulations were reversed or ameliorated by betaine treatment. Hepatic expression of the THF-generating enzyme dihydrofolate reductase (DHFR) was significantly repressed in HCU mice and expression was not increased by betaine treatment but appears to be sensitive to cellular redox status. Expression of the DHFR reaction partner thymidylate synthase was also repressed and metabolomic analysis detected widespread alteration of hepatic histidine and glutamine metabolism. Many individuals with HCU exhibit endothelial dysfunction. DHFR plays a key role in nitric oxide (NO) generation due to its role in regenerating oxidized tetrahydrobiopterin, and we observed a significant decrease in plasma NOx (NO2 + NO3) levels in HCU mice. Additional impairment of NO generation may also come from the HCU-mediated induction of the 20-hydroxyeicosatetraenoic acid generating cytochrome CYP4A. Collectively, our data shows that HCU induces dysfunctional one-carbon metabolism with the potential to both impair betaine treatment and contribute to multiple aspects of pathogenesis in this disease.

Keywords:  cystathionine beta‐synthase; dihydrofolate reductase; homocysteine; homocystinuria; one‐carbon metabolism; tetrahydrofolate

DOI:  https://doi.org/10.1096/fj.202302585R
Nat Cell Biol. 2024 Jul 12.

Pressure sensing of lysosomes enables control of TFEB responses in macrophages.

Ruiqi Cai, Ori Scott, Gang Ye, Trieu Le, Ekambir Saran, Whijin Kwon, Subothan Inpanathan, Blayne A Sayed, Roberto J Botelho, Amra Saric, Stefan Uderhardt, Spencer A Freeman.

Polymers are endocytosed and hydrolysed by lysosomal enzymes to generate transportable solutes. While the transport of diverse organic solutes across the plasma membrane is well studied, their necessary ongoing efflux from the endocytic fluid into the cytosol is poorly appreciated by comparison. Myeloid cells that employ specialized types of endocytosis, that is, phagocytosis and macropinocytosis, are highly dependent on such transport pathways to prevent the build-up of hydrostatic pressure that otherwise offsets lysosomal dynamics including vesiculation, tubulation and fission. Without undergoing rupture, we found that lysosomes incurring this pressure owing to defects in solute efflux, are unable to retain luminal Na+, which collapses its gradient with the cytosol. This cation 'leak' is mediated by pressure-sensitive channels resident to lysosomes and leads to the inhibition of mTORC1, which is normally activated by Na+-coupled amino acid transporters driven by the Na+ gradient. As a consequence, the transcription factors TFEB/TFE3 are made active in macrophages with distended lysosomes. In addition to their role in lysosomal biogenesis, TFEB/TFE3 activation causes the release of MCP-1/CCL2. In catabolically stressed tissues, defects in efflux of solutes from the endocytic pathway leads to increased monocyte recruitment. Here we propose that macrophages respond to a pressure-sensing pathway on lysosomes to orchestrate lysosomal biogenesis as well as myeloid cell recruitment.

DOI: https://doi.org/10.1038/s41556-024-01459-y
Nat Genet. 2024 Jul 08.

Metabolic gene function discovery platform GeneMAP identifies SLC25A48 as necessary for mitochondrial choline import.

Artem Khan, Gokhan Unlu, Phillip Lin, Yuyang Liu, Ece Kilic, Timothy C Kenny, Kıvanç Birsoy, Eric R Gamazon.

Organisms maintain metabolic homeostasis through the combined functions of small-molecule transporters and enzymes. While many metabolic components have been well established, a substantial number remains without identified physiological substrates. To bridge this gap, we have leveraged large-scale plasma metabolome genome-wide association studies (GWAS) to develop a multiomic Gene-Metabolite Association Prediction (GeneMAP) discovery platform. GeneMAP can generate accurate predictions and even pinpoint genes that are distant from the variants implicated by GWAS. In particular, our analysis identified solute carrier family 25 member 48 (SLC25A48) as a genetic determinant of plasma choline levels. Mechanistically, SLC25A48 loss strongly impairs mitochondrial choline import and synthesis of its downstream metabolite betaine. Integrative rare variant and polygenic score analyses in UK Biobank provide strong evidence that the SLC25A48 causal effects on human disease may in part be mediated by the effects of choline. Altogether, our study provides a discovery platform for metabolic gene function and proposes SLC25A48 as a mitochondrial choline transporter.

DOI: https://doi.org/10.1038/s41588-024-01827-2
Nat Commun. 2024 Jul 12. 15(1): 5851

Inhibition of DUSP18 impairs cholesterol biosynthesis and promotes anti-tumor immunity in colorectal cancer.

Xiaojun Zhou, Genxin Wang, Chenhui Tian, Lin Du, Edward V Prochownik, Youjun Li.

Tumor cells reprogram their metabolism to produce specialized metabolites that both fuel their own growth and license tumor immune evasion. However, the relationships between these functions remain poorly understood. Here, we report CRISPR screens in a mouse model of colo-rectal cancer (CRC) that implicates the dual specificity phosphatase 18 (DUSP18) in the establishment of tumor-directed immune evasion. Dusp18 inhibition reduces CRC growth rates, which correlate with high levels of CD8+ T cell activation. Mechanistically, DUSP18 dephosphorylates and stabilizes the USF1 bHLH-ZIP transcription factor. In turn, USF1 induces the SREBF2 gene, which allows cells to accumulate the cholesterol biosynthesis intermediate lanosterol and release it into the tumor microenvironment (TME). There, lanosterol uptake by CD8+ T cells suppresses the mevalonate pathway and reduces KRAS protein prenylation and function, which in turn inhibits their activation and establishes a molecular basis for tumor cell immune escape. Finally, the combination of an anti-PD-1 antibody and Lumacaftor, an FDA-approved small molecule inhibitor of DUSP18, inhibits CRC growth in mice and synergistically enhances anti-tumor immunity. Collectively, our findings support the idea that a combination of immune checkpoint and metabolic blockade represents a rationally-designed, mechanistically-based and potential therapy for CRC.

DOI: https://doi.org/10.1038/s41467-024-50138-x
Immunity. 2024 Jul 09. pii: S1074-7613(24)00317-0. [Epub ahead of print]57(7): 1710-1712

Classical monocyte ontogeny dictates their functions and fates as tissue macrophages.

Sébastien Trzebanski, Jung-Seok Kim, Niss Larossi, Ayala Raanan, Daliya Kancheva, Jonathan Bastos, Montaser Haddad, Aryeh Solomon, Ehud Sivan, Dan Aizik, Jarmila Sekeresova Kralova, Mor Gross-Vered, Sigalit Boura-Halfon, Tsvee Lapidot, Ronen Alon, Kiavash Movahedi, Steffen Jung.

DOI: https://doi.org/10.1016/j.immuni.2024.06.011
Nat Commun. 2024 Jul 06. 15(1): 5680

ATP6V0A1-dependent cholesterol absorption in colorectal cancer cells triggers immunosuppressive signaling to inactivate memory CD8+ T cells.

Tu-Xiong Huang, Hui-Si Huang, Shao-Wei Dong, Jia-Yan Chen, Bin Zhang, Hua-Hui Li, Tian-Tian Zhang, Qiang Xie, Qiao-Yun Long, Yang Yang, Lin-Yuan Huang, Pan Zhao, Jiong Bi, Xi-Feng Lu, Fan Pan, Chang Zou, Li Fu.

Obesity shapes anti-tumor immunity through lipid metabolism; however, the mechanisms underlying how colorectal cancer (CRC) cells utilize lipids to suppress anti-tumor immunity remain unclear. Here, we show that tumor cell-intrinsic ATP6V0A1 drives exogenous cholesterol-induced immunosuppression in CRC. ATP6V0A1 facilitates cholesterol absorption in CRC cells through RAB guanine nucleotide exchange factor 1 (RABGEF1)-dependent endosome maturation, leading to cholesterol accumulation within the endoplasmic reticulum and elevated production of 24-hydroxycholesterol (24-OHC). ATP6V0A1-induced 24-OHC upregulates TGF-β1 by activating the liver X receptor (LXR) signaling. Subsequently, the release of TGF-β1 into the tumor microenvironment by CRC cells activates the SMAD3 pathway in memory CD8+ T cells, ultimately suppressing their anti-tumor activities. Moreover, we identify daclatasvir, a clinically used anti-hepatitis C virus (HCV) drug, as an ATP6V0A1 inhibitor that can effectively enhance the memory CD8+ T cell activity and suppress tumor growth in CRC. These findings shed light on the potential for ATP6V0A1-targeted immunotherapy in CRC.

DOI: https://doi.org/10.1038/s41467-024-50077-7
J Lipid Res. 2024 Jul 07. pii: S0022-2275(24)00095-6. [Epub ahead of print] 100590

Peridroplet mitochondria are associated with the severity of MASLD and the prevention of MASLD by diethyldithiocarbamate.

Xiangyun Sun, Qinghong Yu, Yifei Qi, Bilian Kang, Xinyan Zhao, Lin Liu, Ping Wang, Min Cong, Tianhui Liu.

  Mitochondria can contact lipid droplets (LDs) to form peridroplet mitochondria (PDM) which trap fatty acids in LDs by providing ATP for triglyceride synthesis, and prevent lipotoxicity. However, the role of PDM in metabolic dysfunction associated steatotic liver disease (MASLD) is not clear. Here, the features of PDM in dietary MASLD models with different severity in mice were explored. Electron microscope photographs show that LDs and mitochondria rarely come into contact with each other in normal liver. In mice fed with high-fat diet, PDM can be observed in the liver as early as the beginning of steatosis in hepatocytes. For the first time, we show that PDM in mouse liver varies with the severity of MASLD. PDM and cytosolic mitochondria (CM) were isolated from the liver tissue of MASLD and analyzed by quantitative proteomics. Compared with CM, PDM have enhanced mitochondrial respiration and ATP synthesis. Diethyldithiocarbamate (DDC) alleviates choline-deficient, L-amino acid-defined diet-induced MASLD, while increases PDM in the liver. Similarly, DDC promotes the contact of mitochondria-LDs in steatotic C3A cells in vitro. Meanwhile, DDC promotes triglyceride synthesis and improves mitochondrial dysfunction in MASLD. In addition, DDC upregulates perilipin 5 both in vivo and in vitro, which is considered as a key regulator in PDM formation. Knockout of Plin5 inhibits the contact of mitochondria-LDs induced by DDC in C3A cells. These results demonstrate that PDM might be associated with the progression of MASLD and the prevention of MASLD by DDC. The regulation of PDM might be a new pharmacological strategy for MASLD.

Keywords:  Lipid droplets; Perilipin 5; fatty acids; proteomics; steatotsis; triglyceride

DOI:  https://doi.org/10.1016/j.jlr.2024.100590
Cell Metab. 2024 Jun 28. pii: S1550-4131(24)00233-X. [Epub ahead of print]

TNF compromises intestinal bile-acid tolerance dictating colitis progression and limited infliximab response.

Mengqi Zheng, Yunjiao Zhai, Yanbo Yu, Jing Shen, Shuzheng Chu, Enrico Focaccia, Wenyu Tian, Sui Wang, Xuesong Liu, Xi Yuan, Yue Wang, Lixiang Li, Bingcheng Feng, Zhen Li, Xiaohuan Guo, Ju Qiu, Cuijuan Zhang, Jiajie Hou, Yiyuan Sun, Xiaoyun Yang, Xiuli Zuo, Mathias Heikenwalder, Yanqing Li, Detian Yuan, Shiyang Li.

  The intestine constantly encounters and adapts to the external environment shaped by diverse dietary nutrients. However, whether and how gut adaptability to dietary challenges is compromised in ulcerative colitis is incompletely understood. Here, we show that a transient high-fat diet exacerbates colitis owing to inflammation-compromised bile acid tolerance. Mechanistically, excessive tumor necrosis factor (TNF) produced at the onset of colitis interferes with bile-acid detoxification through the receptor-interacting serine/threonine-protein kinase 1/extracellular signal-regulated kinase pathway in intestinal epithelial cells, leading to bile acid overload in the endoplasmic reticulum and consequent apoptosis. In line with the synergy of bile acids and TNF in promoting gut epithelial damage, high intestinal bile acids correlate with poor infliximab response, and bile acid clearance improves infliximab efficacy in experimental colitis. This study identifies bile acids as an "opportunistic pathogenic factor" in the gut that would represent a promising target and stratification criterion for ulcerative colitis prevention/therapy.

Keywords:  bile acid; detoxification; infliximab; tumor necrosis factor; ulcerative colitis

DOI:  https://doi.org/10.1016/j.cmet.2024.06.008
Nat Commun. 2024 Jul 07. 15(1): 5694

Single-cell resolution characterization of myeloid-derived cell states with implication in cancer outcome.

Gabriela Rapozo Guimarães, Giovanna Resk Maklouf, Cristiane Esteves Teixeira, Leandro de Oliveira Santos, Nayara Gusmão Tessarollo, Nayara Evelin de Toledo, Alessandra Freitas Serain, Cristóvão Antunes de Lanna, Marco Antônio Pretti, Jéssica Gonçalves Vieira da Cruz, Marcelo Falchetti, Mylla M Dimas, Igor Salerno Filgueiras, Otavio Cabral-Marques, Rodrigo Nalio Ramos, Fabiane Carvalho de Macedo, Fabiana Resende Rodrigues, Nina Carrossini Bastos, Jesse Lopes da Silva, Edroaldo Lummertz da Rocha, Cláudia Bessa Pereira Chaves, Andreia Cristina de Melo, Pedro M M Moraes-Vieira, Marcelo A Mori, Mariana Boroni.

Tumor-associated myeloid-derived cells (MDCs) significantly impact cancer prognosis and treatment responses due to their remarkable plasticity and tumorigenic behaviors. Here, we integrate single-cell RNA-sequencing data from different cancer types, identifying 29 MDC subpopulations within the tumor microenvironment. Our analysis reveals abnormally expanded MDC subpopulations across various tumors and distinguishes cell states that have often been grouped together, such as TREM2+ and FOLR2+ subpopulations. Using deconvolution approaches, we identify five subpopulations as independent prognostic markers, including states co-expressing TREM2 and PD-1, and FOLR2 and PDL-2. Additionally, TREM2 alone does not reliably predict cancer prognosis, as other TREM2+ macrophages show varied associations with prognosis depending on local cues. Validation in independent cohorts confirms that FOLR2-expressing macrophages correlate with poor clinical outcomes in ovarian and triple-negative breast cancers. This comprehensive MDC atlas offers valuable insights and a foundation for futher analyses, advancing strategies for treating solid cancers.

DOI: https://doi.org/10.1038/s41467-024-49916-4
Proc Natl Acad Sci U S A. 2024 Jul 16. 121(29): e2400883121

Palmitoylation at a conserved cysteine residue facilitates gasdermin D-mediated pyroptosis and cytokine release.

Zhonghua Liu, Sai Li, Chuanping Wang, Kaylynn J Vidmar, Syrena Bracey, Ling Li, Belinda Willard, Masaru Miyagi, Tong Lan, Bryan C Dickinson, Abdullah Osme, Theresa T Pizarro, Tsan Sam Xiao.

  Gasdermin D (GSDMD)-mediated pyroptotic cell death drives inflammatory cytokine release and downstream immune responses upon inflammasome activation, which play important roles in host defense and inflammatory disorders. Upon activation by proteases, the GSDMD N-terminal domain (NTD) undergoes oligomerization and membrane translocation in the presence of lipids to assemble pores. Despite intensive studies, the molecular events underlying the transition of GSDMD from an autoinhibited soluble form to an oligomeric pore form inserted into the membrane remain incompletely understood. Previous work characterized S-palmitoylation for gasdermins from bacteria, fungi, invertebrates, as well as mammalian gasdermin E (GSDME). Here, we report that a conserved residue Cys191 in human GSDMD was S-palmitoylated, which promoted GSDMD-mediated pyroptosis and cytokine release. Mutation of Cys191 or treatment with palmitoyltransferase inhibitors cyano-myracrylamide (CMA) or 2-bromopalmitate (2BP) suppressed GSDMD palmitoylation, its localization to the membrane and dampened pyroptosis or IL-1β secretion. Furthermore, Gsdmd-dependent inflammatory responses were alleviated by inhibition of palmitoylation in vivo. By contrast, coexpression of GSDMD with palmitoyltransferases enhanced pyroptotic cell death, while introduction of exogenous palmitoylation sequences fully restored pyroptotic activities to the C191A mutant, suggesting that palmitoylation-mediated membrane localization may be distinct from other molecular events such as GSDMD conformational change during pore assembly. Collectively, our study suggests that S-palmitoylation may be a shared regulatory mechanism for GSDMD and other gasdermins, which points to potential avenues for therapeutically targeting S-palmitoylation of gasdermins in inflammatory disorders.

Keywords:  S-palmitoylation; ZDHHC palmitoyltransferase; gasdermin D; inflammasome; pyroptosis

DOI:  https://doi.org/10.1073/pnas.2400883121
Gut. 2024 Jul 09. pii: gutjnl-2024-332429. [Epub ahead of print]

Glutamine metabolic competition drives immunosuppressive reprogramming of intratumour GPR109A+ myeloid cells to promote liver cancer progression.

Yang Yang, Tianduo Pei, Chaobao Liu, Mingtao Cao, Xiaolin Hu, Jie Yuan, Fengqian Chen, Bao Guo, Yuemei Hong, Jibin Liu, Bin Li, Xiaoguang Li, Hui Wang.

  OBJECTIVE: The metabolic characteristics of liver cancer drive considerable hurdles to immune cells function and cancer immunotherapy. However, how metabolic reprograming in the tumour microenvironment impairs the antitumour immune response remains unclear.DESIGN: Human samples and multiple murine models were employed to evaluate the correlation between GPR109A and liver cancer progression. GPR109A knockout mice, immune cells depletion and primary cell coculture models were used to determine the regulation of GPR109A on tumour microenvironment and identify the underlying mechanism responsible for the formation of intratumour GPR109A+myeloid cells.
RESULTS: We demonstrate that glutamine shortage in liver cancer tumour microenvironment drives an immunosuppressive GPR109A+myeloid cells infiltration, leading to the evasion of immune surveillance. Blockade of GPR109A decreases G-MDSCs and M2-like TAMs abundance to trigger the antitumour responses of CD8+ T cells and further improves the immunotherapy efficacy against liver cancer. Mechanistically, tumour cells and tumour-infiltrated myeloid cells compete for glutamine uptake via the transporter SLC1A5 to control antitumour immunity, which disrupts the endoplasmic reticulum (ER) homoeostasis and induces unfolded protein response of myeloid cells to promote GPR109A expression through IRE1α/XBP1 pathway. The restriction of glutamine uptake in liver cancer cells, as well as the blockade of IRE1α/XBP1 signalling or glutamine supplementation, can eliminate the immunosuppressive effects of GPR109A+ myeloid cells and slow down tumour progression.
CONCLUSION: Our findings identify the immunometabolic crosstalk between liver cancer cells and myeloid cells facilitates tumour progression via a glutamine metabolism/ER stress/GPR109A axis, suggesting that GPR109A can be exploited as an immunometabolic checkpoint and putative target for cancer treatment.

Keywords:  HEPATOCELLULAR CARCINOMA; IMMUNOLOGY IN HEPATOLOGY; IMMUNOTHERAPY

DOI:  https://doi.org/10.1136/gutjnl-2024-332429