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Spontaneous subarachnoid hemorrhage (SAH), the third most common stroke subtype, is associated with high mortality and disability rates. Therefore, finding effective therapies to improve neurological function after SAH is critical. The objective of this study was to investigate the potential neuroprotective effects of hydrogen in the context of SAH, specifically, by examining its role in attenuating neuronal ferroptosis and inhibiting neuroinflammation, which are exacerbated by excess iron ions after SAH. Methods: Mice were exposed to chambers containing 3% hydrogen, and cells were cultured in incubators containing 60% hydrogen. Neurological function in mice was assessed using behavioral scores. Protein changes were detected using western blotting. Inflammatory factors were detected using enzyme linked immunosorbent assay. Probes, electron microscopy, and related kits were employed to detect oxidative stress and ferroptosis. Results: Hydrogen improved the motor function, sensory function, and cognitive ability of mice after SAH. Additionally, hydrogen facilitated Nuclear factor erythroid 2 -related factor 2 activation, upregulated Glutathione peroxidase 4, and inhibited Toll-like receptor 4, resulting in downregulation of inflammatory responses, attenuation of oxidative stress after SAH, and inhibition of neuronal ferroptosis. Conclusion: Hydrogen exerts neuroprotective effects by inhibiting neuronal ferroptosis and attenuating neuroinflammation after SAH. Graphical representation illustrating the role of hydrogen intervention in the modulation of various cellular processes involved in ferroptosis and neuroinflammation after subarachnoid hemorrhage. Specifically, the metabolism of hemoglobin leads to the accumulation of excess iron ions and damage-associated molecular patterns (DAMPs), which subsequently activate ferroptosis and Toll-like receptor 4 (TLR4)/myeloid differentiation primary response protein 88 (MyD88) pathway-mediated neuroinflammation. The production of reactive oxygen species (ROS) during ferroptosis further exacerbates the inflammatory response and contributes to nerve damage. However, hydrogen intervention facilitates the translocation of nuclear factor erythroid2-related factor 2 (Nrf2) to the nucleus, thereby promoting the expression of glutathione peroxidase 4 (GPX4) and reducing ROS levels. This inhibition of ferroptosis and attenuation of ROS-dependent inflammatory responses are accompanied by the downregulation of the TLR4/MyD88 pathway, leading to the inhibition of neuroinflammation. [Display omitted] • We provide direct evidence for the anti -ferroptosis effect of hydrogen. • Hydrogen mediates anti -ferroptosis and anti-inflammatory effects after SAH via Nrf2. • Hydrogen can be used for clinical treatment after SAH. [ABSTRACT FROM AUTHOR]

In comparison to other stroke types, subarachnoid hemorrhage (SAH) is characterized by an early age of onset and often results in poor prognosis. The inadequate blood flow at the site of the lesion leads to localized oxygen deprivation, increased level of hypoxia-inducible factor-1α (HIF-1α), and triggers inflammatory responses and oxidative stress, ultimately causing hypoxic brain damage. Despite the potential benefits of oxygen (O 2) administration, there is currently a lack of efficient focal site O 2 delivery following SAH. Conventional clinical O 2 supply methods, such as transnasal oxygenation and hyperbaric oxygen therapy, do not show the ideal therapeutic effect in severe SAH patients. The perfluorocarbon oxygen carrier (PFOC) demonstrates efficacy in transporting O 2 and responding to elevated levels of CO 2 at the lesion site. Through cellular experiments, we determined that PFOC oxygenation serves as an effective therapeutic approach in inhibiting hypoxia. Furthermore, our animal experiments showed that PFOC oxygenation outperforms O 2 breathing, leading to microglia phenotypic switching and the suppression of inflammatory response via the inhibition of HIF-1α. Therefore, as a new type of O 2 therapy after SAH, PFOC oxygenation can effectively reduce hypoxic brain injury and improve neurological function. Subarachnoid hemorrhage primarily arises from the rupture of intracranial aneurysms. The rupture of an aneurysm results in a substantial influx of blood into the subarachnoid space, exerting arterial pressure and accumulating within the cerebral sulcus cerebral pool, thereby forming a hematoma that compresses the brain tissue. Consequently, this compression leads to localized tissue hypoxia, which subsequently triggers excitatory neuroinflammation and oxidative stress. Considering these circumstances, we propose a novel approach utilizing perfluorocarbons following subarachnoid hemorrhage, enhancing oxygenation at the site of the lesion in comparison to conventional O 2 breathing. Perfluorocarbon oxygen carrier oxygenation has been found to have a downregulating effect on HIF-1α, leading to a decrease in the population of M1-type microglia and an increase in the population of M2-type microglia. Additionally, this oxygenation process inhibits inflammatory responses and oxidative stress following subarachnoid hemorrhage, ultimately resulting in an improvement in neurological function. [Display omitted] • HIF-1α mediates hypoxic brain injury after SAH. • We developed a method of supplying oxygen that can be administered intravenously. • Perfluorocarbon oxygen carrier ameliorates hypoxic brain injury by inhibiting HIF-1α. [ABSTRACT FROM AUTHOR]

Background: Menaquinone-4(MK-4), the isoform of vitamin K2 in the brain, exerts neuroprotective effects against a variety of central nervous system disorders. This study aimed to demonstrate the anti-ferroptosis effects of MK-4 in neurons after SAH. Methods: A subarachnoid hemorrhage (SAH) model was prepared by endovascular perforation in mice. In vitro hemoglobin stimulation of primary cortical neurons mimicked SAH. MK-4, Brequinar (BQR, DHODH inhibitor), and Selisistat (SEL, SIRT1 inhibitor) were administered, respectively. Subsequently, WB, immunofluorescence was used to determine protein expression and localization, and transmission electron microscopy was used to observe neuronal mitochondrial structure while other indicators of ferroptosis were measured. Results: MK-4 treatment significantly upregulated the protein levels of DHODH; decreased GSH, PTGS2, NOX1, ROS, and restored mitochondrial membrane potential. Meanwhile, MK-4 upregulated the expression of SIRT1 and promoted its entry into the nucleus. BQR or SEL partially abolished the protective effect of MK-4 on, neurologic function, and ferroptosis. Conclusions: Taken together, our results suggest that MK-4 attenuates ferroptosis after SAH by upregulating DHODH through the activation of SIRT1. SAH: subarachnoid hemorrhage; ROS: reactive oxygen species; MK-4: menaquinone-4; DHODH: dihydroorotate dehydrogenase; SLC7A11: solute carrier family 7 member 11; GPX4: glutathione peroxidase-4; SIRT1: sirtuin 1; CoQ: Coenzyme Q; MDA: malondialdehyde; PLOOH: phospholipid hydroperoxides. [Display omitted] • Menaquinone-4 improves neurologic function and attenuates ferroptosis after SAH. • Menaquinone-4 attenuates ferroptosis after SAH by upregulating DHODH. • Activation of SIRT1 is a potential mechanism for Menaquinone-4 upregulation of DHODH. • Vitamin K2 levels in cerebrospinal fluid of SAH patients was significantly reduced. [ABSTRACT FROM AUTHOR]

Retinal ischemia/reperfusion (I/R) injury is a common pathological process responsible for cellular damage in glaucoma, diabetic retinopathy and hypertensive retinopathy. Metformin is a biguanide drug that exerts strong effects on multiple diseases. This study aims to evaluate the protective effect of metformin against retinal I/R injury and its underlying mechanism. I/R induced reduction in retina thickness and cell number in ganglion cell layer, and metformin alleviated I/R-induced retinal injury. Both retinal I/R and simulated ischemia/reperfusion (SIR) in R28 cells down-regulated expression of mitochondrial fusion protein Mfn2 and OPA1, which led to mitochondrial fission. Metformin also alleviated damage in R28 cells, and reversed the alteration in Mfn2 and OPA1, mitochondrial fission and mitochondrial membrane potential (MMP) disruption-induced by I/R or SIR as well. Intriguingly, inhibition of AMPK by compound C or siRNA prevented metformin-mediated up-regulation of Mfn2 and OPA1. Compound C and knockdown of Mfn2 or OPA1 dramatically alleviated the protective effect of metformin against intracellular ROS generation, MMP disruption, mitochondrial fission and loss of RGCs in ganglion cell layer induced by SIR or I/R. Moreover, scavenging mitochondrial ROS (mito-ROS) by mito-TEMPO exerted the similar protection against I/R-induced retinal injury or SIR-induced damage in R28 cells as metformin. Our data show for the first time that metformin protects against retinal I/R injury through AMPK-mediated mitochondrial fusion and the decreased mito-ROS generation. These findings might also repurpose metformin as a therapeutic agent for retinal I/R injury. [Display omitted] • I/R results in retinal injury by inducing mitochondrial fission. • Metformin activates AMPK and alleviates I/R-induced retinal injury. • Metformin upregulates expression of mitochondrial fusion proteins via AMPK. • AMPK-mediated mitochondrial fusion protects against retinal I/R injury. [ABSTRACT FROM AUTHOR]

Age-related macular degeneration is a common cause of blindless among the aged, which can mainly be attributed to oxidative stress and dysregulated autophagy in retinal pigment epithelium cells. Lactate was reported to act as a signaling molecule and exerted beneficial effect against oxidative stress. This study aims to investigate the protective effect of lactate against oxidative stress-induced retinal degeneration. Here, H 2 O 2 -induced oxidative stress cell model and sodium iodate-induced mice retinal degeneration model were established. It was found that H 2 O 2 inhibited cell viability in ARPE-19 cells and sodium iodate induced deterioration of retinal pigment epithelium as well as apoptosis in retina. Pretreatment with lactate alleviated oxidative stress-induced cell death and retinal degeneration. Molecularly, lactate activated autophagy by up-regulating the ratio of LC3II/I, increased formation of LC3 puncta and autophagic vacuole. Further, lactate prevented H 2 O 2 -induced mitochondrial fission and maintained mitochondrial function by alleviating H 2 O 2 -induced mitochondrial membrane potential disruption and intracellular ROS generation. In contrast, application of 3-methyladenine, an inhibitor of autophagy, effectively weakened the protective effect of lactate against oxidative stress in vivo and in vitro. Taken together, all data in this study indicate that lactate protects against oxidative stress-induced retinal degeneration and preserves mitochondrial function by activating autophagy. [Display omitted] • H 2 O 2 causes oxidative stress, mitochondrial dysfunction and retinal degeneration. • Lactate acts as a signaling molecule to activate autophagy pathway in RPE cells. • Autophagy ameliorates H 2 O 2 -induced oxidative stress and mitochondrial dysfunction. • Lactate protects against oxidative stress-induced retinal degeneration by autophagy. [ABSTRACT FROM AUTHOR]

Increasing evidence suggests the significant contribution of high levels of thioredoxin reductase (TrxR) in various stages of tumorigenesis and resistance to tumor chemotherapy. Thus, inhibition of TrxR with small molecules is an attractive strategy for cancer therapy. Eriocalyxin B (EriB), a naturally occurring diterpenoid extracted from Isodon eriocalyx, has reflected potential anticancer activities through numerous pathways. Here, we describe that EriB covalently modifies GSH and selectively inhibits TrxR activity by targeting the Sec residue of the enzyme. Pharmacological inhibition of TrxR by EriB results in elevated ROS levels, reduced total GSH and thiols content, which ultimately induced potent RKO cell apoptosis mediated by oxidative stress. Importantly, EriB indicates potent synthetic lethality with GSH inhibitors, BSO, in RKO cells. In summary, our results highlight that targeting TrxR by EriB explores a novel mechanism for the biological action of EriB. This opened up a new therapeutic indication for using EriB to combat cancers. [Display omitted] • Eriocalyxin B (EriB) selectively inhibits thioredoxin reductase with an IC 50 value of approximately 0.42 μM. • At nanomolar concentration, EriB shows potent synthetic lethality with GSH inhibitor, BSO, in colorectal cancer RKO cells. • EriB induces robust oxidative stress-mediated apoptosis in RKO cells. [ABSTRACT FROM AUTHOR]

Corneal alkali burn, one of the most serious ophthalmic emergencies, is difficult to be cured by conservative treatments. It is well known that oxidative stress, inflammation and neovascularization are the main causes of corneal damage after alkali burn, but its underlying mechanism remains to be elucidated. Here, we reported that the expression and phosphorylation (Ser616) of mitochondrial fission protein Drp1 were up-regulated at day 3 after alkali burn, while mitochondrial fusion protein Mfn2 was down-regulated. The phosphorylation of ERK1/2 in corneas was increased at day 1, 3, 7 and peaked at day 3 after alkali burn. In human corneal epithelial cells (HCE-2), NaOH treatment induced mitochondrial fission, intracellular ROS production and mitochondrial membrane potential disruption, which was prevented by Drp1 inhibitor Mdivi-1. In corneas, Mdivi-1 or knockdown of Drp1 by Lenti-Drp1 shRNA attenuated alkali burn-induced ROS production and phosphorylation of IκBα and p65. In immunofluorescence staining, it was detected that Mdivi-1 also prevented NaOH-induced nuclear translocation of p65 in HCE-2 cells. Moreover, the expression of NADPH oxidase NOX2 and NOX4 in corneas peaked at day 7 after alkali burn. Mdivi-1, Lenti-Drp1 shRNA or the mitochondria-targeted antioxidant mito-TEMPO efficiently alleviated activation of NF-κB, expression of NOX2/4 and inflammatory cytokines including IL-6, IL-1β and TNF-α in corneas after alkali burn. In pharmacological experiments, both Mdivi-1 and NADPH oxidases inhibitor Apocynin protected the corneas against alkali burn-induced neovascularization. Intriguingly, the combined administration of Mdivi-1 and Apocynin had a synergistic inhibitory effect on corneal neovascularization after alkali burn. Taken together, these results indicate that Drp1-dependent mitochondrial fission is involved in alkali burn-induced corneal injury through regulating oxidative stress, inflammatory responses and corneal neovascularization. This might provide a novel therapeutic target for corneal injury after alkali burn in the future. [Display omitted] • Alkali burn stimulates mitochondrial fission in corneas through up-regulation of expression and phosphorylation of Drp1. • Drp1-dependent mitochondrial fission facilitates ROS generation, activation of NF-κB and inflammation. • Drp1-dependent mitochondrial fission may act as the upstream regulator of alkali burn-induced NOX2/4 expression. • Drp1 inhibitor and NOXs inhibitor have a synergistic inhibitory effect on alkali burn-induced CNV and inflammation. [ABSTRACT FROM AUTHOR]