Anti-inflammatory effect of artemisinin on uric acid-induced NLRP3 inflammasome activation through blocking interaction between NLRP3 and NEK7

Objective: Artemisinin is a potent anti-malarial agent that plays a potent role in regulating inflammatory disorders. NEK7 is a major interacting partner with NLRP3 in NLRP3 inflammasome. The aim of this study was to clarify the anti-inflammatory effect of artemisinin on activation of uric acid-induced NLRP3 inflammasome through regulation of NEK7. Methods: Human macrophage U937 cells treated with lipopolysaccharide (LPS), monosodium urate (MSU) crystals, or artemisinin were used in in vitro study. Intracellular potassium (K+) level was measured in U937 cells treated with and without artemisinin. Expression of target genes or proteins NEK7, NLRP3, ASC, caspase-1, interleukin-1 beta (IL-1 beta), and NF-kappa B signaling molecules was measured. MSU crystal-induced arthritis model was used for in vivo study. Results: Gout patients showed higher NLRP3 and NEK7 mRNA expression, compared to controls. Enhanced expression of NLRP3, caspase-1, and IL-1 beta was noted in macrophages treated with LPS (10 ng/ml) and MSU crystals (0.1 mg/ml), which was markedly suppressed by treatment with artemisinin (1,10, and 100 mu M). Artemisinin significantly inhibited interaction between NLRP3 and NEK7 in NLRP3 inflammasome activation. Artemisinin (10 and 100 mu M) attenuated intracellular K+ efflux in macrophages stimulated with LPS and MSU crystals. Artemisinin suppressed foot and ankle swelling in MSU crystal-induced arthritis mice. Conclusion: This study revealed that artemisinin inhibited activation of NLRP3 inflammasome by suppressing interaction between NEK7 and NLRP3 in uric acid-induced inflammation. (C) 2019 Elsevier Inc. All rights reserved.