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Eeckhout E, Asaoka T, Van Gorp H, Demon D, Girard-Guyonvarc’h C, Andries V, Vereecke L, Gabay C, Lamkanfi M, van Loo G, Wullaert A. The autoinflammation-associated NLRC4 V341A mutation increases microbiota-independent IL-18 production but does not recapitulate human autoinflammatory symptoms in mice. Front Immunol 2023; 14:1272639. [PMID: 38090573 PMCID: PMC10713841 DOI: 10.3389/fimmu.2023.1272639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 11/13/2023] [Indexed: 12/18/2023] Open
Abstract
Background Autoinflammation with infantile enterocolitis (AIFEC) is an often fatal disease caused by gain-of-function mutations in the NLRC4 inflammasome. This inflammasomopathy is characterized by macrophage activation syndrome (MAS)-like episodes as well as neonatal-onset enterocolitis. Although elevated IL-18 levels were suggested to take part in driving AIFEC pathology, the triggers for IL-18 production and its ensuing pathogenic effects in these patients are incompletely understood. Methods Here, we developed and characterized a novel genetic mouse model expressing a murine version of the AIFEC-associated NLRC4V341A mutation from its endogenous Nlrc4 genomic locus. Results NLRC4V341A expression in mice recapitulated increased circulating IL-18 levels as observed in AIFEC patients. Housing NLRC4V341A-expressing mice in germfree (GF) conditions showed that these systemic IL-18 levels were independent of the microbiota, and unmasked an additional IL-18-inducing effect of NLRC4V341A expression in the intestines. Remarkably, elevated IL-18 levels did not provoke detectable intestinal pathologies in NLRC4V341A-expressing mice, even not upon genetically ablating IL-18 binding protein (IL-18BP), which is an endogenous IL-18 inhibitor that has been used therapeutically in AIFEC. In addition, NLRC4V341A expression did not alter susceptibility to the NLRC4-activating gastrointestinal pathogens Salmonella Typhimurium and Citrobacter rodentium. Conclusion As observed in AIFEC patients, mice expressing a murine NLRC4V341A mutant show elevated systemic IL-18 levels, suggesting that the molecular mechanisms by which this NLRC4V341A mutant induces excessive IL-18 production are conserved between humans and mice. However, while our GF and infection experiments argue against a role for commensal or pathogenic bacteria, identifying the triggers and mechanisms that synergize with IL-18 to drive NLRC4V341A-associated pathologies will require further research in this NLRC4V341A mouse model.
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Affiliation(s)
- Elien Eeckhout
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Tomoko Asaoka
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Hanne Van Gorp
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Dieter Demon
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Charlotte Girard-Guyonvarc’h
- Division of Rheumatology, Department of Medicine, University Hospital of Geneva, Department of Pathology and Immunology, University of Geneva Faculty of Medicine, Geneva, Switzerland
| | - Vanessa Andries
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Lars Vereecke
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
| | - Cem Gabay
- Division of Rheumatology, Department of Medicine, University Hospital of Geneva, Department of Pathology and Immunology, University of Geneva Faculty of Medicine, Geneva, Switzerland
| | - Mohamed Lamkanfi
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
| | - Geert van Loo
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
- Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium
| | - Andy Wullaert
- Department of Internal Medicine and Pediatrics, Ghent University, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, VIB, Ghent, Belgium
- Laboratory of Proteinscience, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp, Antwerp, Belgium
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Pang J, Vince JE. The role of caspase-8 in inflammatory signalling and pyroptotic cell death. Semin Immunol 2023; 70:101832. [PMID: 37625331 DOI: 10.1016/j.smim.2023.101832] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Revised: 07/20/2023] [Accepted: 08/16/2023] [Indexed: 08/27/2023]
Abstract
The programmed cell death machinery exhibits surprising flexibility, capable of crosstalk and non-apoptotic roles. Much of this complexity arises from the diverse functions of caspase-8, a cysteine-aspartic acid protease typically associated with activating caspase-3 and - 7 to induce apoptosis. However, recent research has revealed that caspase-8 also plays a role in regulating the lytic gasdermin cell death machinery, contributing to pyroptosis and immune responses in contexts such as infection, autoinflammation, and T-cell signalling. In mice, loss of caspase-8 results in embryonic lethality from unrestrained necroptotic killing, while in humans caspase-8 deficiency can lead to an autoimmune lymphoproliferative syndrome, immunodeficiency, inflammatory bowel disease or, when it can't cleave its substrate RIPK1, early onset periodic fevers. This review focuses on non-canonical caspase-8 signalling that drives immune responses, including its regulation of inflammatory gene transcription, activation within inflammasome complexes, and roles in pyroptotic cell death. Ultimately, a deeper understanding of caspase-8 function will aid in determining whether, and when, targeting caspase-8 pathways could be therapeutically beneficial in human diseases.
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Affiliation(s)
- Jiyi Pang
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia
| | - James E Vince
- The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; The Department of Medical Biology, University of Melbourne, Parkville, VIC 3010, Australia.
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