Kidney tubular cell death induced by transforming growth factor-β1 (TGF-β1) is known to contribute to diabetic nephropathy, a major complication of diabetes. Caspase-3-dependent apoptosis and caspase-1-dependent pyroptosis are also involved in tubular cell death under diabetic conditions. Recently, ferroptosis, an atypical form of iron-dependent cell death, was reported to cause kidney disease, including acute kidney injury. Ferroptosis is primed by lipid peroxide accumulation through the cystine/glutamate antiporter system Xc− (xCT) and glutathione peroxidase 4 (GPX4)-dependent mechanisms. The aim of this study was to evaluate the role of ferroptosis in diabetes-induced tubular injury. TGF-β1-stimulated proximal tubular epithelial cells and diabetic mice models were used for in vitro and in vivo experiments, respectively. xCT and GPX4 expression, cell viability, glutathione concentration, and lipid peroxidation were quantified to indicate ferroptosis. The effect of ferroptosis inhibition was also assessed. In kidney biopsy samples from diabetic patients, xCT and GPX4 mRNA expression was decreased compared to nondiabetic samples. In TGF-β1-stimulated tubular cells, intracellular glutathione concentration was reduced and lipid peroxidation was enhanced, both of which are related to ferroptosis-related cell death. Ferrostatin-1 (Fer-1), a ferroptosis inhibitor, alleviated TGF-β1-induced ferroptosis. In diabetic mice, kidney mRNA and protein expressions of xCT and GPX4 were reduced compared to control. Kidney glutathione concentration was decreased, while lipid peroxidation was increased in these mice, and these changes were alleviated by Fer-1 treatment. Ferroptosis is involved in kidney tubular cell death under diabetic conditions. Ferroptosis inhibition could be a therapeutic option for diabetic nephropathy.

IgA vasculitis, formerly known as Henoch-Schönlein purpura, is a systemic IgA-mediated vasculitis of the small vessels commonly seen in children. The natural history of IgA vasculitis is generally self-limiting; however, one-third of patients experience symptom recurrence and a refractory course. This systematic review examined the use of dapsone in refractory IgA vasculitis cases. A literature search of PubMed databases retrieved 13 articles published until June 14, 2018. The most common clinical feature was a palpable rash (100% of patients), followed by joint pain (69.2%). Treatment response within 1–2 days was observed in 6 of 26 patients (23.1%) versus within 3–7 days in 17 patients (65.4%). Relapse after treatment discontinuation was reported in 17 patients (65.4%) but not in 3 patients (11.5 %). Four of the 26 patients (15.4%) reported adverse effects of dapsone including arthralgia (7.7%), rash (7.7%), and dapsone hypersensitivity syndrome (3.8%). Our findings suggest that dapsone may affect refractory IgA vasculitis. Multicenter randomized placebo-controlled trials are necessary to determine the standard dosage of dapsone at initial or tapering of treatment in IgA vasculitis patients and evaluate whether dapsone has a significant benefit versus steroids or other medications.

A Correction to this paper has been published: https://doi.org/10.1038/s41419-021-03667-y

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