Objective Macrophage activation by monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals mediates an interleukin (IL)-1β-dependent inflammation during gout and pseudo-gout flare, respectively. Since metabolic reprogramming of macrophages goes along with inflammatory responses dependently on stimuli and tissue environment, we aimed to decipher the role of glycolysis and oxidative phosphorylation in the IL-1β-induced microcrystal response.
Methods Briefly, an in vitro study (metabolomics and real-time extracellular flux analysis) on MSU and CPP crystal-stimulated macrophages was performed to demonstrate the metabolic phenotype of macrophages. Then, the role of aerobic glycolysis in IL-1β production was evaluated, as well in vitro as in vivo using 18F-fluorodeoxyglucose positron emission tomography imaging and glucose uptake assay, and molecular approach of glucose transporter 1 (GLUT1) inhibition.
Results We observed that MSU and CPP crystals led to a metabolic rewiring toward the aerobic glycolysis pathway explained by an increase in GLUT1 plasma membrane expression and glucose uptake on macrophages. Also, neutrophils isolated from human synovial fluid during gout flare expressed GLUT1 at their plasma membrane more frequently than neutrophils isolated from bloodstream. Both glucose deprivation and treatment with either 2-deoxyglucose or GLUT1 inhibitor suppressed crystal-induced NLRP3 activation and IL-1β production, and microcrystal inflammation in vivo.
Conclusion In conclusion, we demonstrated that GLUT1-mediated glucose uptake is instrumental during the inflammatory IL-1β response induced by MSU and CPP crystals. These findings open new therapeutic paths to modulate crystal-related inflammation.
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Handling editor Josef S Smolen
Presented at This work was presented as a poster communication in the Annual European Congress of Rheumatology (ARD, June 2019, Volume: 78, Supplement: 2, Pages 233-233) and in the American Congress of Rheumatology (Arthritis and Rheumatology, October 2019, Volume: 71, Supplement: 10, Meeting Abstract: 1238).
Contributors H-KE conceived the study. FR, LC-G and H-KE contributed to its design and coordination, participated in data interpretation and cowrote the manuscript. LC-G and FR performed the laboratory experiments. CC synthesised calcium pyrophosphate crystals, characterised their physicochemical structure and contributed to writing the manuscript. LO, FA and NV performed the Seahorse experiments. FC and FF realised the metabolomics study. AP performed PET study. PR, TB, FR and H-KE collected the patient samples. H-KE, CC, PR, MC-S and FL secured the funding. All authors participated in the final approval of the manuscript.
Funding The study was funded by ANR (ANR-126BS08-0022-01), ART Viggo, the 'Prevention et Traitement des Décalcifications (PTD)' Association, Arthritis Courtin foundation (Arthritis R&D 2018-2019) and the French Society of Rheumatology (SFR 2017-2018, SFR 2018-2019). LC-G was financially supported by grants from ANR and ART Viggo, and FR by Paris Diderot University and ART Viggo, PTD.
Competing interests None declared.
Patient and public involvement Patients and/or the public were not involved in the design, conduct, reporting or dissemination plans of this research.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement No data are available. All data relevant to the study are included in the article or uploaded as supplementary information. All data are included in the article.
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