Background/Purpose: Monosodium urate (MSU) andmonoclinic calcium pyrophosphate dihydrated(mCPPD)crystals are responsible for relapsing acute arthritis which is driven by interleukin 1β (IL-1β).IL-1βproductionrelies onNLRP3 inflammasome activationleading to ASC and caspase-1 recruitment. In tumor cells and in LPS-stimulated macrophages a switch of cell metabolisms toward glycolysis favors IL-1β production.

The aims of this study were to assess 1/ whethercrystal-induced NLRP3 activation and IL-1βproduction involved glucose metabolism and 2/ how MSU and mCPPD crystals induced glucose uptake focusing on the role of glucose transporter Glut1.

Methods: Synthetic and pyrogen-free MSU andmCPPDcrystalswere used to stimulate THP-1 cells and mouse bone marrow-derived macrophages (BMDM). Cells were stimulated in presence or absence of glucose (2g/L) and pyruvate (10mM).Glycolysis was inhibited by 2-deoxy-glucose (2DG) and the role of glucose transporter 1 (Glut1)was assessed by pharmacological inhibitor (STF-31) and siRNA. IL-1β production was quantified by ELISA.Metabolomicanalysis was performed by mass spectrometry.Glucose uptake was determined using ¹⁸F-DG (Fluor18 labeled-2DG) and positron emission tomography (PET). Glut1 membrane localization was assessed by flux cytometry and confocal microscopy, ASC speck formation by confocal microscopy. In vivo, we used murine air pouch model to assess the effects of 2DG and Glut1 inhibition in crystal-mediated inflammation.Glut1 membrane localization ofcirculating neutrophils was compared to synovial fluid neutrophils harvested during gout flare.

Results: In vitro, both MSU and mCPPDcrystal-induced IL-1β secretion and ASC speck formationwere inhibitedwhen cells were cultured in glucose-free medium or in presence of 2DG.Similarly,MSU and mCPPD crystal-induced inflammation was abrogated in mice treated with 2DG.In THP-1 cells stimulated by MSU and mCPPD crystals, metabolomicanalysis displayedalteration of glycolysis pathway and Krebs’cycle and decrease of intracellular ATP production.Interestingly, MSU and mCPPD crystals increased glucoseuptakein vitro, ex vivo and in vivo.Crystal-induced glucose uptake was inhibited by STF-31 and decreased in THP-1 cells transfected with Glut1 siRNA.Next, we observed that MSU and mCPPD crystals increased membrane localization of Glut1 in THP-1, BMDM and neutrophils infiltrated in air pouch lavages and membranes. Glut1 membrane localization was positively correlated with IL-1β production. Moreover, during gout flare, the proportion of Glut1 positive neutrophils was higher in synovial fluid neutrophils than in circulating neutrophils. Finally, STF-31 treatment decreased,in vitro,glucose uptake and IL-1 β production induced by MSU and mCPPD crystals, and in vivoMSU and mCPPD crystal-induced inflammation.

Conclusion: Glucose uptake through Glut1 transporter enhanced IL-1β production induced by MSU and mCPPDcrystals. Studies to decipher how these crystals induced Glut1 membrane localization are ongoing. Similarly, we investigate how glycolysis regulates NLRP3 and ASC activation. Decreasing Glut1 membrane localization might be a potential target to dampen crystal-induced inflammation.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/monosodium-urate-and-calcium-pyrophosphatecrystal-induced-interleukin-1-production-depends-on-glucose-uptake-through-glut1-transporter/