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Objectives: Recent investigations in humans and mouse models with lupus have revealed evidence of mitochondrial dysfunction and production of mitochondrial reactive oxygen species (mROS) in T cells and neutrophils. This can provoke numerous cellular changes including oxidation of nucleic acids, proteins, lipids and even induction of cell death. We have previously observed that in T cells from patients with lupus, the increased mROS is capable of provoking oligomerisation of mitochondrial antiviral stimulator (MAVS) and production of type I interferon (IFN-I). mROS in SLE neutrophils also promotes the formation of neutrophil extracellular traps (NETs), which are increased in lupus and implicated in renal damage. As a result, in addition to traditional immunosuppression, more comprehensive treatments for lupus may also include non-immune therapy, such as antioxidants., Methods: Lupus-prone MRL- lpr mice were treated from weaning for 11 weeks with the mitochondria-targeted antioxidant, MitoQ (200 µM) in drinking water. Mice were then assessed for ROS production in neutrophils, NET formation, MAVS oligomerisation, serum IFN-I, autoantibody production and renal function., Results: MitoQ-treated mice manifested reduced neutrophil ROS and NET formation, decreased MAVS oligomerisation and serum IFN-I, and reduced immune complex formation in kidneys, despite no change in serum autoantibody ., Conclusions: These findings reveal the potential utility of targeting mROS in addition to traditional immunosuppressive therapy for lupus., Competing Interests: Competing interests: MPM helped develop MitoQ and has a commercial interest in MitoQ., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY. Published by BMJ.)

Objective: A role for mitochondrial dysfunction has been proposed in the immune dysregulation and organ damage characteristic of systemic lupus erythematosus (SLE). Idebenone is a coenzyme Q10 synthetic quinone analog and an antioxidant that has been used in humans to treat diverse diseases in which mitochondrial function is impaired. This study was undertaken to assess whether idebenone ameliorates lupus in murine models., Methods: Idebenone was administered orally to MRL/lpr mice at 2 different doses (1 gm/kg or 1.5 gm/kg idebenone-containing diet) for 8 weeks. At peak disease activity, clinical, immunologic, and metabolic parameters were analyzed and compared to those in untreated mice (n = 10 per treatment group). Results were confirmed in the lupus-prone NZM2328 mouse model., Results: In MRL/lpr mice, idebenone-treated mice showed a significant reduction in mortality incidence (P < 0.01 versus untreated mice), and the treatment attenuated several disease features, including glomerular inflammation and fibrosis (each P < 0.05 versus untreated mice), and improved renal function in association with decreased renal expression of interleukin-17A (IL-17A) and mature IL-18. Levels of splenic proinflammatory cytokines and inflammasome-related genes were significantly decreased (at least P < 0.05 and some with higher significance) in mice treated with idebenone, while no obvious drug toxicity was observed. Idebenone inhibited neutrophil extracellular trap formation in neutrophils from lupus-prone mice (P < 0.05) and human patients with SLE. Idebenone also improved mitochondrial metabolism (30% increase in basal respiration and ATP production), reduced the extent of heart lipid peroxidation (by one-half that of untreated mice), and significantly improved endothelium-dependent vasorelaxation (P < 0.001). NZM2328 mice exposed to idebenone also displayed improvements in renal and systemic inflammation, reducing the kidney pathology score (P < 0.05), IgG/C3 deposition (P < 0.05), and the gene expression of interferon, proinflammatory, and inflammasome-related genes (at least P < 0.05 and some with higher significance)., Conclusion: Idebenone ameliorates murine lupus disease activity and the severity of organ damage, supporting the hypothesis that agents that modulate mitochondrial biologic processes may have a therapeutic role in human SLE., (Published 2019. This article is a U.S. Government work and is in the public domain in the USA.)