Ferrostatin-1 facilitated neurological functional rehabilitation of spinal cord injury mice by inhibiting ferroptosis

Roflumilast inhibits neuronal ferroptosis via AMPK/Nrf2/HO-1 signaling and promotes motor function recovery after spinal cord injury in rats

Spinal cord injury (SCI) is a serious central nervous system disease. Ferroptosis is one of the major causes of spinal cord neurological loss, and targeting ferroptosis is a promising therapeutic strategy. Roflumilast has shown promising applications in the treatment of neurological diseases due to its potent anti-inflammatory and anti-oxidative stress effects. This study aimed to investigate whether roflumilast could inhibit neuronal ferroptosis to improve motor function after SCI in rats. In vitro experiments, we found that roflumilast significantly increased cell survival in an in vitro ferroptosis model, improved mitochondrial function, reduced intracellular iron, reactive oxygen species (ROS), and lipid peroxides accumulation as well as the expression of the pro-ferroptosis proteins, long-chain acyl-coenzyme A synthase 4 (ACSL4), and prostaglandin-endoperoxide synthase 2 (PTGS2), and increased the expression of ferroptosis-inhibitory protein glutathione peroxidase 4 (GPX4), and ferritin heavy chain 1 (FTH1) expression. Mechanistically, these protective effects were achieved by activating AMP-dependent protein kinase (AMPK)/nuclear factor E2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling and were attenuated when AMPK signaling was blocked. In vivo experiments, roflumilast attenuated spinal cord tissue damage, increased the number of motor neuron survivors, and improved motor function after SCI in rats. Overall, activation of AMPK/Nrf2/HO-1 signaling by roflumilast attenuated neuronal ferroptosis and improved motor function after SCI in rats.

RNAi-based ALOX15B silencing augments keratinocyte inflammation in vitro via EGFR/STAT1/JAK1 signalling

Arachidonate 15-lipoxygenase type B (ALOX15B) peroxidises polyunsaturated fatty acids to their corresponding fatty acid hydroperoxides, which are subsequently reduced into hydroxy-fatty acids. A dysregulated abundance of these biological lipid mediators has been reported in the skin and blood of psoriatic compared to healthy individuals. RNAscope and immunohistochemistry revealed increased ALOX15B expression in lesional psoriasis samples. Using a cytokine cocktail containing IL-17A, interferon-gamma and tumour necrosis factor-alpha to produce a psoriasis-like phenotype, a role for ALOX15B in human epidermal keratinocyte inflammation was investigated. siRNA-mediated silencing of ALOX15B increased CCL2 expression and secretion. In addition to CCL2, secretion of CCL5 and CXCL10 were elevated in skin equivalents treated with lipoxygenase inhibitor ML351. Inhibition of the JAK1/STAT1 pathway reversed the enhanced CCL2 expression found with ALOX15B silencing. Previous studies have linked epidermal growth factor receptor (EGFR) inhibition with the upregulation of cytokines including CCL2, CCL5 and CXCL10. ALOX15B silencing reduced EGFR expression and inhibition of EGFR signalling potentiated the effect of ALOX15B silencing on increased CCL2, CCL5 and CXCL10 expression. Confirming previous findings, gene expression of cholesterol biosynthesis genes was reduced via reduced ERK phosphorylation. Reduced ERK phosphorylation was dependant on EGFR and NRF2 activation. Furthermore, plasma membrane lipids were investigated via confocal microscopy, revealing reduced cholesterol and lipid rafts. This study suggests a role for ALOX15B in keratinocyte inflammation through modulation of lipid peroxidation and the EGFR/JAK1/STAT1 signalling axis.

Screening of orthopedic medicines identifies raloxifene hydrochloride as a novel ferroptosis inhibitor for spinal cord injury therapy

Spinal cord injury (SCI) is a severe condition that can lead to irreversible central nervous system damage. Spinal cord injury patients frequently present with coexisting orthopedic conditions, and many of them also have underlying bone and joint diseases. Recent studies have identified ferroptosis as a significant contributor that exacerbates the progression of spinal cord injury. This study conducted a screening in common orthopedic medications, which includes anti-osteoporosis agents and calcium supplements, in order to identify potential ferroptosis inhibitors and investigate their therapeutic effects on spinal cord injury. Among the 8 drugs screened, raloxifene hydrochloride was found to significantly inhibit ferroptosis induced by RSL3 in neural cells. Subsequent studies confirmed its inhibitory effect on ferroptosis both in vitro and in vivo. It was also demonstrated that Nrf2 inhibitor Brusatol could reverse the anti-ferroptotic effect of Raloxifene hydrochloride in neural cells in vitro as well as its therapeutic effect on SCI in vivo, suggesting its inhibitory effect on ferroptosis is through Nrf2. This study identifies a novel ferroptosis inhibitor among orthopedic medicines and also confirms the therapeutic effect of Raloxifene hydrochloride on SCI. The results of the current study may provide reference for the clinical administration of SCI.

Ferroptosis in the neurovascular unit after spinal cord injury

The mechanisms of secondary injury following spinal cord injury are complicated. The role of ferroptosis, which is a newly discovered form of regulated cell death in the neurovascular unit(NVU), is increasingly important. Ferroptosis inhibitors have been shown to improve neurovascular homeostasis and attenuate secondary spinal cord injury(SCI). This review focuses on the mechanisms of ferroptosis in NVU cells and NVU-targeted therapeutic strategies according to the stages of SCI, and analyzes possible future research directions.

A critical appraisal of ferroptosis in Alzheimer's and Parkinson's disease: new insights into emerging mechanisms and therapeutic targets

Neurodegenerative diseases represent a pressing global health challenge, and the identification of novel mechanisms underlying their pathogenesis is of utmost importance. Ferroptosis, a non-apoptotic form of regulated cell death characterized by iron-dependent lipid peroxidation, has emerged as a pivotal player in the pathogenesis of neurodegenerative diseases. This review delves into the discovery of ferroptosis, the critical players involved, and their intricate role in the underlying mechanisms of neurodegeneration, with an emphasis on Alzheimer's and Parkinson's diseases. We critically appraise unsolved mechanistic links involved in the initiation and propagation of ferroptosis, such as a signaling cascade resulting in the de-repression of lipoxygenase translation and the role played by mitochondrial voltage-dependent anionic channels in iron homeostasis. Particular attention is given to the dual role of heme oxygenase in ferroptosis, which may be linked to the non-specific activity of P450 reductase in the endoplasmic reticulum. Despite the limited knowledge of ferroptosis initiation and progression in neurodegeneration, Nrf2/Bach1 target genes have emerged as crucial defenders in anti-ferroptotic pathways. The activation of Nrf2 and the inhibition of Bach1 can counteract ferroptosis and present a promising avenue for future therapeutic interventions targeting ferroptosis in neurodegenerative diseases.

Mechanisms and therapeutic targets of ferroptosis: Implications for nanomedicine design

Ferroptosis is a nonapoptotic form of cell death and differs considerably from the well-known forms of cell death in terms of cell morphology, genetics, and biochemistry. The three primary pathways for cell ferroptosis are system Xc-/glutathione peroxidase 4 (GPX4), lipid metabolism, and ferric metabolism. Since the discovery of ferroptosis, mounting evidence has revealed its critical regulatory role in several diseases, especially as a novel potential target for cancer therapy, thereby attracting increasing attention in the fields of tumor biology and anti-tumor therapy. Accordingly, broad prospects exist for identifying ferroptosis as a potential therapeutic target. In this review, we aimed to systematically summarize the activation and defense mechanisms of ferroptosis, highlight the therapeutic targets, and discuss the design of nanomedicines for ferroptosis regulation. In addition, we opted to present the advantages and disadvantages of current ferroptosis research and provide an optimistic vision of future directions in related fields. Overall, we aim to provide new ideas for further ferroptosis research and inspire new strategies for disease diagnosis and treatment.

Ferroptosis inhibitor improves outcome after early and delayed treatment in mild spinal cord injury

We show that redox active iron can induce a regulated form of non-apoptotic cell death and tissue damage called ferroptosis that can contribute to secondary damage and functional loss in the acute and chronic periods after spinal cord injury (SCI) in young, adult, female mice. Phagocytosis of red blood cells at sites of hemorrhage is the main source of iron derived from hemoglobin after SCI. Expression of hemeoxygenase-1 that induces release of iron from heme, is increased in spinal cord macrophages 7 days after injury. While iron is stored safely in ferritin in the injured spinal cord, it can, however, be released by NCOA4-mediated shuttling of ferritin to autophagosomes for degradation (ferritinophagy). This leads to the release of redox active iron that can cause free radical damage. Expression of NCOA4 is increased after SCI, mainly in macrophages. Increase in the ratio of redox active ferrous (Fe2+) to ferric iron (Fe3+) is also detected after SCI by capillary electrophoresis inductively coupled mass spectrometry. These changes are accompanied by other hallmarks of ferroptosis, i.e., deficiency in various elements of the antioxidant glutathione (GSH) pathway. We also detect increases in enzymes that repair membrane lipids (ACSL4 and LPCAT3) and thus promote on-going ferroptosis. These changes are associated with increased levels of 4-hydroxynonenal (4-HNE), a toxic lipid peroxidation product. Mice with mild SCI (30 kdyne force) treated with the ferroptosis inhibitor (UAMC-3203-HCL) either early or delayed times after injury showed improvement in locomotor recovery and secondary damage. Cerebrospinal fluid and serum samples from human SCI cases show evidence of increased iron storage (ferritin), and other iron related molecules, and reduction in GSH. Collectively, these data suggest that ferroptosis contributes to secondary damage after SCI and highlights the possible use of ferroptosis inhibitors to treat SCI.

Both hemoglobin and hemin cause damage to retinal pigment epithelium through the iron ion accumulation

Subretinal hemorrhages result in poor vision and visual field defects. During hemorrhage, several potentially toxic substances are released from iron-based hemoglobin and hemin, inducing cellular damage, the detailed mechanisms of which remain unknown. We examined the effects of excess intracellular iron on retinal pigment epithelial (RPE) cells. A Fe2+ probe, SiRhoNox-1 was used to investigate Fe2+ accumulation after treatment with hemoglobin or hemin in the human RPE cell line ARPE-19. We also evaluated the production of reactive oxygen species (ROS) and lipid peroxidation. Furthermore, the protective effect of-an iron chelator, 2,2'-bipyridyl (BP), and ferrostatin-1 (Fer-1) on the cell damage, was evaluated. Fe2+ accumulation increased in the hemoglobin- or hemin-treated groups, as well as intracellular ROS production and lipid peroxidation. In contrast, BP treatment suppressed RPE cell death, ROS production, and lipid peroxidation. Pretreatment with Fer-1 ameliorated cell death in a concentration-dependent manner and suppressed ROS production and lipid peroxidation. Taken together, these findings indicate that hemoglobin and hemin, as well as subretinal hemorrhage, may induce RPE cell damage and visual dysfunction via intracellular iron accumulation.