Background/Purpose: Emerging evidence indicates that macrophage activation is critically supported by glucose metabolic shifts. Although macrophages are key contributors to inflammation, little is known about the role of glucose metabolism in the pathogenesis of inflammatory gouty arthritis. Thus, we evaluated glucose metabolism in the murine air-pouch model of acute gouty inflammation.

Methods: Mice (N=6 in each group) were injected with PBS or 3-bromopyruvate (BrPa; 7.5 mg/kg) 1 hour before MSU injection to assess the effect of glycolysis inhibition in vivo. After 6 hours injection of monosodium urate (MSU) crystals (3 mg/ml) in the air pouch, both the air pouch lavage and peripheral blood were collected. The infiltrating leukocytes obtained from the lavage after centrifugation and peripheral blood mononuclear cells (PBMCs) isolated from the blood were subjected to quantitative RT-PCR for expression of glycolysis-related genes Glut1 and LDHa, and NLRP3 inflammasome-related genes IL-1band NLRP3. Production of IL-1b, CXCL1 and IL-6 were quantified from supernatant of the lavage by ELISA analysis. The air-pouch tissues were also collected and fixed, and subsequently H&E staining was performed. For ex vivostudies, thioglycolate-elicited peritoneal macrophages were collected and stimulated with LPS (100 ng/ml for four hours) and MSU (0.2 mg/ml overnight) with and without pretreatment of 2-deoxy-glucose (2DG, 10mM), another glycolysis inhibitor, for one hour. Expression of glycolysis-related genes and cytokine production were assessed from the cells and conditioned media, respectively, using the methods mentioned above.

Results: MSU crystals promoted glycolysis in both infiltrating leukocytes and PBMCs, evidenced by increased expression of Glut1 and LDHa. This was associated with upregulation of gene expression of IL-1band NLRP3 in both PBMC and air-pouch elicited cells. BrPa significantly lowered numbers of infiltrating leukocytes (3.26±0.79×10⁶ vs 0.74±0.1×10⁶,±p<0.01, in the MSU group after PBS or BrPa respectively) and the amount of proinflammatory cytokines CXCL1 (2379±620 vs 992±255 pg/ml, p<0.05), IL-1b(429.6±140.7 vs 103.3±12 pg/ml, p=0.02), and IL-6 (2111±418 vs 865±236 pg/ml) in the air pouch. It also markedly reduced leukocyte infiltration in the air pouch lining in response to MSU crystals (3±0.66 vs 1±0.57, p=0.012 in PBS or BrPa-treated mice respectively). Treatment with 2-DG in peritoneal macrophages significantly inhibited gene expression of Glut 1, hexokinase 2 (HK2), and LDHa, and production of CXCL1, IL-1b, IL-6, and TNF after LPS and/or MSU stimulation.

Conclusion: Glycolytic inhibition could attenuate MSU crystal-induced inflammatory response. Targeting metabolic dysfunction could be a novel treatment strategy for acute gouty arthritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/targeting-glucose-metabolism-in-the-murine-air-pouch-model-of-acute-gouty-inflammation/