Inflammasome Activation in Ankylosing Spondylitis Is Associated With Gut Dysbiosis

Objective: We undertook this study to evaluate the activation and functional relevance of inflammasome pathways in ankylosing spondylitis (AS) patients and rodent models and their relationship to dysbiosis. Methods: An inflammasome pathway was evaluated in the gut and peripheral blood from 40 AS patients using quantitative reverse transcriptase–polymerase chain reaction (qRT-PCR), immunohistochemistry (IHC), flow cytometry, and confocal microscopy, and was compared to that of 20 healthy controls and 10 patients with Crohn’s disease. Bacteria was visualized using silver stain in human samples, and antibiotics were administered to HLA–B27–transgenic rats. The NLRP3 inhibitor MCC950 was administered to SKG mice, and ileal and joint tissues were assessed by IHC analysis and real-time qRT-PCR. The role of inflammasome in modulating the interleukin-23 (IL-23)/IL-17 axis was studied ex vivo. Results: Expression levels of Nlrp3, Nlrc4, and Aim2 were increased in the gut of HLA–B27–transgenic rats and reduced by antibiotic treatment (P 2 = 0.28, P 2 = 0.34, P Conclusion: Inflammasome activation occurs in rodent models of AS and in AS patients, is associated with dysbiosis, and is involved in triggering ileitis in SKG mice. Inflammasomes drive type III cytokine production with an IL-1β–dependent mechanism in AS patients.