Dimethyl fumarate attenuates MSU-induced gouty arthritis by inhibiting NLRP3 inflammasome activation and oxidative stress

Y. Cao, Y. Hu, X.-F. Jin, Y. Liu, J.-M. Zou

Department of Rheumatology, The First People’s Hospital of LouDi, LouDi, Hunan, China. zjm19900222@126.com

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• Immunology
• Rheumatology

OBJECTIVE: Dimethyl fumarate (DMF) has shown anti-inflammatory and antioxidant activities. However, the effects of DMF on gouty arthritis remain elusive, and the underlying mechanism is not understood. In this study, we aim to investigate the role of DMF in gouty arthritis.

MATERIALS AND METHODS: Mice were gavage with DMF for consecutive 7 days at two different doses (10 mg/kg/day or 30 mg/kg/day, once daily) in advance and then monosodium sodium urate (MSU) was injected into their joint to establish an acute gout mice model. The pain and swelling of the hind paw in mice were determined. The production of pro-inflammatory cytokine in the paw tissues was assessed by Elisa and the inflammatory infiltration of the joint was determined by hematoxylin and eosin (H&E) staining. The activity of superoxide dismutase (SOD) and the content of malondialdehyde (MDA) in the tissues were measured by commercial kits. In addition, the expression of nuclear factor kappa B (NF-κB) and NACHT, LRR, and PYD domains-containing protein 3 (NLRP3) inflammasome and downstream genes were detected by PCR and Western blot. Furthermore, LPS-primed murine macrophages Raw 264.7 cells were treated with different concentrations of DMF (2 μM, 5 μM, 10 μM) for 2 h, and then challenged with MSU (200 μg/mL) for other 12 h to observe the effect of DMF on cell viability via cell counting kit-8 (CCK-8) assay and lactate dehydrogenase (LDH) levels in the supernatant of culture medium. Immunofluorescent staining was used to detect the NLRP3 inflammasome activation and reactive oxygen species (ROS) production in vitro. Caspase-1 activity was measured by corresponding assay kits both in vivo and in vitro.

RESULTS: DMF attenuated pain and swelling in MSU-induced gout mice by decreasing pro-inflammatory cytokine production and inflammatory cell infiltration, as well as improved oxidative stress. Moreover, DMF inhibited the activation of NF-κB and NLRP3 inflammasome and subsequent expression of caspase-1, interleukin-1β (IL-1β), and IL-18 at both mRNA and protein levels. Meanwhile, DMF suppressed NLRP3 inflammasome expression and ROS production in LPS and MSU-stimulated Raw 264.7 cells, thereby protecting the cells from inflammatory injury.

CONCLUSIONS: DMF serves as a new approach for the treatment of MSU-induced gouty arthritis by suppressing NLRP3 inflammasome activation and oxidative stress.

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