Acute kidney injury is a common complication of rhabdomyolysis. A better understanding of this syndrome may be useful to identify novel therapeutic targets because there is no specific treatment so far. Ferroptosis is an iron‐dependent form of regulated nonapoptotic cell death that is involved in renal injury. In this study, we investigated whether ferroptosis is associated with rhabdomyolysis‐mediated renal damage, and we studied the therapeutic effect of curcumin, a powerful antioxidant with renoprotective properties. Induction of rhabdomyolysis in mice increased serum creatinine levels, endothelial damage, inflammatory chemokines, and cytokine expression, alteration of redox balance (increased lipid peroxidation and decreased antioxidant defenses), and tubular cell death. Treatment with curcumin initiated before or after rhabdomyolysis induction ameliorated all these pathologic and molecular alterations. Although apoptosis or receptor‐interacting protein kinase (RIPK)3‐mediated necroptosis were activated in rhabdomyolysis, our results suggest a key role of ferroptosis. Thus, treatment with ferrostatin 1, a ferroptosis inhibitor, improved renal function in glycerol‐injected mice, whereas no beneficial effects were observed with the pan‐caspase inhibitor carbobenzoxy‐valyl‐alanyl‐aspartyl‐( O ‐methyl)‐fluoromethylketone or in RIPK3‐deficient mice. In cultured renal tubular cells, myoglobin (Mb) induced ferroptosis‐sensitive cell death that was also inhibited by curcumin. Mechanistic in vitro studies showed that curcumin reduced Mb‐mediated inflammation and oxidative stress by inhibiting the TLR4/NF‐κB axis and activating the cytoprotective enzyme heme oxygenase 1. Our findings are the first to demonstrate the involvement of ferroptosis in rhabdomyolysis‐associated renal damage and its sensitivity to curcumin treatment. Therefore, curcumin may be a potential therapeutic approach for patients with this syndrome.—Guerrero‐Hue, M., García‐Caballero, C., Palomino‐Antolín, A., Rubio‐Navarro, A., Vázquez‐Carballo, C., Herencia, C., Martín‐Sanchez, D., Farré‐Alins, V., Egea, J., Cannata, P., Praga, M., Ortiz, A., Egido, J., Sanz, A. B., Moreno, J. A. Curcumin reduces renal damage associated with rhabdomyolysis by decreasing ferroptosis‐mediated cell death. FASEB J. 33,8961–8975 (2019). www.fasebj.org

Background and Purpose: Ischaemic stroke is a leading cause of death, disability, and a high unmet medical need. Post‐reperfusion inflammation and an up‐regulation of toll‐like receptor 4 (TLR4), an upstream sensor of innate immunity, are associated with poor outcome in stroke patients. Here, we identified the therapeutic effect of targeting the LPS/TLR4 signal transduction pathway.Experimental Approach: We tested the effect of the TLR4 inhibitor, eritoran (E5564) in different in vitro ischaemia‐related models: human organotypic cortex culture, rat organotypic hippocampal cultures, and primary mixed glia cultures. We explored the therapeutic window of E5564 in the transient middle cerebral artery occlusion model of cerebral ischaemia in mice.Key Results: In vivo, administration of E5564 1 and 4 hr post‐ischaemia reduced the expression of different pro‐inflammatory chemokines and cytokines, infarct volume, blood–brain barrier breakdown, and improved neuromotor function, an important clinically relevant outcome. In the human organotypic cortex culture, E5564 reduced the activation of microglia and ROS production evoked by LPS.Conclusion and Implications: TLR4 signalling has a causal role in the inflammation associated with a poor post‐stroke outcome. Importantly, its inhibition by eritoran (E5564) provides neuroprotection both in vitro and in vivo, including in human tissue, suggesting a promising new therapeutic approach for ischaemic stroke.

Microglia controls the immune system response in the brain. Specifically, the activation and dysregulation of the NLRP3 inflammasome is responsible for the initiation of the inflammatory process through IL-1β and IL-18 release. In this work, we have focused on studying the effect of melatonin on the regulation of the NLRP3 inflammasome through α7 nicotinic receptor (nAChR) and its relationship with autophagy. For this purpose, we have used pharmacological and genetic approaches in lipopolysaccharide (LPS)-induced inflammation models in both in vitro and in vivo models. In the BV2 cell line, LPS inhibited autophagy, which increased NLRP3 protein levels. However, melatonin promoted an increase in the autophagic flux. Treatment of glial cultures from wild-type (WT) mice with LPS followed by extracellular adenosine triphosphate (ATP) produced the release of IL-1β, which was reversed by melatonin pretreatment. In cultures from α7 nAChR knock-out (KO) mice, melatonin did not reduce IL-1β release. Furthermore, melatonin decreased the expression of inflammasome components and reactive oxygen species (ROS) induced by LPS; co-incubation of melatonin with α-bungarotoxin (α-bgt) or luzindole abolished the anti-inflammatory and antioxidant effects. In vivo, melatonin reverted LPS-induced cognitive decline, reduced NLRP3 levels and promoted autophagic flux in the hippocampi of WT mice, whereas in α7 nAChR KO mice melatonin effect was not observed. These results suggest that melatonin may modulate the complex interplay between α7 nAChR and autophagy signaling.

Despite the numerous research studies on traumatic brain injury (TBI), many physiopathologic mechanisms remain unknown. TBI is a complex process, in which neuroinflammation and glial cells play an important role in exerting a functional immune and damage-repair response. The activation of the NLRP3 inflammasome is one of the first steps to initiate neuroinflammation and so its regulation is essential. Using a closed-head injury model and a pharmacological (MCC950; 3 mg/kg, pre- and post-injury) and genetical approach (NLRP3 knockout (KO) mice), we defined the transcriptional and behavioral profiles 24 h after TBI. Wild-type (WT) mice showed a strong pro-inflammatory response, with increased expression of inflammasome components, microglia and astrocytes markers, and cytokines. There was no difference in the IL1β production between WT and KO, nor compensatory mechanisms of other inflammasomes. However, some microglia and astrocyte markers were overexpressed in KO mice, resulting in an exacerbated cytokine expression. Pretreatment with MCC950 replicated the behavioral and blood–brain barrier results observed in KO mice and its administration 1 h after the lesion improved the damage. These findings highlight the importance of NLRP3 time-dependent activation and its role in the fine regulation of glial response.