Background/Purpose: Mucosal-associated invariant T (MAIT) cells contribute to protection against certain microorganism infections and play an important role in mucosal immunity. Upon antigen recognition, MAIT cells rapidly produce Th1/Th17 cytokines, including interferon (IFN)-γ, tumor necrosis factor (TNF)-α, and interleukin (IL)-17, in an innate-like manner. MAIT cells are known to play important roles in autoimmunity, infectious diseases and cancers. In addition, severe MAIT cell abnormalities are seen in patients with metabolic disorders (e.g., obesity and type 2 diabetes), suggesting a potential role in these disorders. However, little is known about the role of MAIT cells in gouty arthritis. Here, we examined the level and function of MAIT cells in patients with gouty arthritis.

Methods: The study cohort was composed of 60 patients with gouty arthritis (10 acute gout, 25 intercritical gout, and 25 chronic gout), 11 hyperuricemia subjects, and 30 healthy controls. MAIT cell, cytokine, CD69, programmed death-1 (PD-1), and lymphocyte-activation gene 3 (LAG-3) levels were measured by flow cytometry. In addition, peripheral blood mononuclear cells (PBMCs) were cultured in vitro with MSU crystals, and CD69, PD-1, and LAG-3 expression was assessed by flow cytometry.

Results: Circulating MAIT cell levels were significantly reduced in patients with acute, intercritical and chronic gout, but their capacities for IFN-γ, IL-17, or TNF-α production were preserved. Notably, expressions of CD69, PD-1, or LAG-3 in MAIT cells were found to be elevated in patients with gouty arthritis as compared with healthy controls. Freshly isolated PBMCs from healthy donor subjects were stimulated with MSU crystals. MSU crystals induced the expressions of CD69, PD-1, and LAG-3 in MAIT cells. In addition, MAIT cell levels were significantly higher in synovial fluid than in peripheral blood of gouty arthritis patients, suggesting accumulation of MAIT cells in the synovial fluid of gouty arthritis patients.

Conclusion: This study demonstrates that circulating MAIT cells are activated, numerically deficient in gouty arthritis patients. In addition, circulating MAIT cell deficiency in gouty arthritis patients is related to accumulation into synovial fluid. These findings suggest that MAIT cells play an important role in gouty arthritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/activation-and-deficiency-of-circulating-mucosal-associated-invariant-t-cells-in-patients-with-gouty-arthritis/