AIM2 and NLRC4-driven inflammasome activation in adult-onset Still's disease and the preliminary therapeutic effect exploration of carboxyamidotriazole

Abstract

Objectives: This study aimed to explore the changes of four major inflammasomes in adult-onset Still's disease (AOSD) and preliminarily evaluate the therapeutic effect of carboxyamidotriazole (CAI), which has previously been reported to have the significant anti-inflammatory activity.

Method: The mRNA expressions of proinflammatory cytokines and inflammasome components in peripheral blood mononuclear cells (PBMCs) from AOSD patients and healthy controls (HC) were determined by reverse transcription-quantitative PCR. Poly(dA:dT)-induced AIM2 inflammasome and flagellin-induced NLRC4 inflammasome activation models were established in bone marrow-derived macrophages (BMDMs). The levels of cytokines in serum and culture supernatants were measured by ELISA method.

Results: The serum levels of IL-1β, IL-6, and TNF-α in AOSD patients were significantly higher than those in HC. However, the mRNA expressions of IL-1β, IL-6, IL-18, and TNF-α in PBMCs did not differ markedly in AOSD patients in comparison with HC. Significantly increased mRNA levels of AIM2, NLRC4, ASC, and caspase-1 were observed in patients with AOSD when compared with HC, while NLRP1 and NLRP3 showed no change in AOSD samples. In addition, CAI treatment could significantly reduce the levels of IL-1β, IL-6, and TNF-α secreted by AOSD PBMCs and inhibit AIM2 and NLRC4 inflammasomes activation in BMDMs.

Conclusions: Increased levels of proinflammatory cytokines in AOSD might be associated with NLRC4 and AIM2 inflammasomes activation. CAI is likely to have the therapeutic potential for AOSD by inhibiting NLRC4 and AIM2 inflammasomes activation and reducing the proinflammatory cytokines and worthy of further investigation. These results provide new ideas for elucidating the pathogenesis of AOSD and providing specific targeted therapy. Key points • Significantly higher mRNA levels of AIM2 and NLRC4 inflammsome signaling were observed in AOSD patients compared with health controls, indicating that AIM2 and NLRC4 inflammsome activation might be related to the increased proinflammatory cytokines in AOSD. • CAI treatment markedly reduced the secretion levels of cytokines IL-1β, IL-6, and TNF-α in AOSD PBMCs and inhibited AIM2 and NLRC4 inflammasome activation.

Keywords: Adult-onset Still’s disease; Carboxyamidotriazole; Cytokines; Inflammasome.