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Inhibition of glutamine synthetase in monocytes from patients with acute-on-chronic liver failure resuscitates their antibacterial and inflammatory capacity
  1. Hannelie Korf1,
  2. Johannie du Plessis1,2,
  3. Jos van Pelt3,
  4. Sofie De Groote1,
  5. David Cassiman1,4,
  6. Len Verbeke1,4,
  7. Bart Ghesquière5,
  8. Sarah-Maria Fendt6,7,
  9. Matthew J Bird1,5,
  10. Ali Talebi8,
  11. Matthias Van Haele9,
  12. Rita Feio-Azevedo1,
  13. Lore Meelberghs1,
  14. Tania Roskams9,
  15. Rajeshwar P Mookerjee10,
  16. Gautam Mehta10,
  17. Rajiv Jalan10,
  18. Thierry Gustot11,
  19. Wim Laleman1,4,
  20. Frederik Nevens1,4,
  21. Schalk Willem van der Merwe1,4
  1. 1 Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven, Belgium
  2. 2 Department of Immunology, University of Pretoria, Pretoria, South Africa
  3. 3 Department of Oncology, KU Leuven, and Leuven Cancer Institute (LKI), Leuven, Belgium
  4. 4 Department of Gastroenterology and Hepatology, UZ Leuven, Leuven, Belgium
  5. 5 Metabolomics Expertise Centrum, VIB-KU Leuven Center for Cancer Biology, KU Leuven, Leuven, Belgium
  6. 6 Laboratory of Cellular Metabolism and Metabolic Regulation, VIB-KU Leuven Center for Cancer Biology, KU Leuven, Leuven, Belgium
  7. 7 Department of Oncology, Laboratory of Cellular Metabolism and Metabolic Regulation, KU Leuven and Leuven Cancer Institute (LKI), Leuven, Belgium
  8. 8 Department of Oncology, Laboratory of Lipid Metabolism and Cancer, KU Leuven and Leuven Cancer Institute (LKI), KU Leuven, Leuven, Belgium
  9. 9 Department of Imaging and Pathology, Translational Cell and Tissue Research, KU Leuven and University Hospitals Leuven, Leuven, Belgium
  10. 10 Liver Failure Group, Institute for Liver Disease Health, University College London, London, UK
  11. 11 Department of Gastroenterology and Hepato-Pancreatology, Hôpital Erasme, Université Libre de Bruxelles (ULB), Brussels, Belgium
  1. Correspondence to Hannelie Korf; hannelie.korf{at}kuleuven.be and Professor Schalk Willem van der Merwe, Laboratory of Hepatology, Department of Chronic Diseases, Metabolism and Ageing (CHROMETA), KU Leuven, Leuven 3000, Belgium; schalk.vandermerwe{at}uzleuven.be

Abstract

Objective Acute-on-chronic liver failure (ACLF) is associated with dysfunctional circulating monocytes whereby patients become highly susceptible to bacterial infections. Here, we identify the pathways underlying monocyte dysfunction in ACLF and we investigate whether metabolic rewiring reinstates their phagocytic and inflammatory capacity.

Design Following phenotypic characterisation, we performed RNA sequencing on CD14+CD16 monocytes from patients with ACLF and decompensated alcoholic cirrhosis. Additionally, an in vitro model mimicking ACLF patient-derived features was implemented to investigate the efficacy of metabolic regulators on monocyte function.

Results Monocytes from patients with ACLF featured elevated frequencies of interleukin (IL)-10-producing cells, reduced human leucocyte antigen DR isotype (HLA-DR) expression and impaired phagocytic and oxidative burst capacity. Transcriptional profiling of isolated CD14+CD16 monocytes in ACLF revealed upregulation of an array of immunosuppressive parameters and compromised antibacterial and antigen presentation machinery. In contrast, monocytes in decompensated cirrhosis showed intact capacity to respond to inflammatory triggers. Culturing healthy monocytes in ACLF plasma mimicked the immunosuppressive characteristics observed in patients, inducing a blunted phagocytic response and metabolic program associated with a tolerant state. Metabolic rewiring of the cells using a pharmacological inhibitor of glutamine synthetase, partially restored the phagocytic and inflammatory capacity of in vitro generated- as well as ACLF patient-derived monocytes. Highlighting its biological relevance, the glutamine synthetase/glutaminase ratio of ACLF patient-derived monocytes positively correlated with disease severity scores.

Conclusion In ACLF, monocytes feature a distinct transcriptional profile, polarised towards an immunotolerant state and altered metabolism. We demonstrated that metabolic rewiring of ACLF monocytes partially revives their function, opening up new options for therapeutic targeting in these patients.

  • acute liver failure
  • alcoholic liver disease
  • immunology in hepatology
  • macrophages
  • bacterial infection
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Footnotes

  • Contributors SvdM, HK and JvP conceptualised and planned the study. HK, JdP and SvdM wrote the protocol. HK and JdP performed the flow cytometry, monocyte functional studies, gene expression and multiplex cytokine assays. AT, RFA and SDG assisted with the Incucyte experiments. LM documented the clinical patient information. MVH and TR performed immunohistochemistry experiments. BG, DC, MB and S-MF provided support for the metabolic aspects of the study. JvP performed the RNA sequence pathway identification, the hierarchic clustering and statistical analysis. RJ, GM, RPM, TG, DC, FN, WL, LV and SvdM recruited and cared for the patients. HK and SvdM wrote the manuscript.

  • Funding This work was supported by internal funding from the UZ Leuven (KOOR) and KU Leuven (C1) as well as by the FWO and Gilead Sciences.

  • Competing interests SvdM, FN and DC are recipients of Flanders fund for scientific research (FWO fundamenteel-klinisch mandaat). RJ has research collaborations with Yaqrit and Takeda. RJ is the inventor of OPA, which has been patented by UCL and licensed to Mallinckrodt. He is also the founder of a UCL spin out, Yaqrit Limited, Ammun Limited and Cyberliver Limited.

  • Ethics approval Medical Ethics Committee (KU Leuven/UZ Leuven; S54588).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement The RNA sequencing data will become available at the Gene Expression Omnibus (http://www.ncbi.nlm.nih.gov/geo/) under accession number GSE93265.

  • Patient consent for publication Not required.

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