Activation of SIRT1 Alleviates Ferroptosis in the Early Brain Injury after Subarachnoid Hemorrhage

Protective effects of flavonoids against intracerebral and subarachnoid hemorrhage (Review)

Intracerebral hemorrhage (ICH), known as non-traumatic cerebrovascular rupture and hemorrhage, often occurs in the deep basal brain segment. It is known for its high morbidity and mortality rates. Subarachnoid hemorrhage (SAH) is a clinical syndrome caused by the rupture of blood vessels at the base or surface of the brain that allows blood to flow directly into the subarachnoid space. It progresses quickly and typically manifests at younger ages compared with ICH. ICH and SAH are both devastating events in the category of hemorrhagic strokes and are attracting increasing attention from researchers. Flavonoids, being important natural molecules, have remarkable anti-inflammatory and antioxidant effects. Flavonoids have extensive biological activities in inflammation and oxidative stress (OS), and have protective effects in vascular function associated with cerebrovascular diseases. They have an impact on the onset of ICH and SAH by targeting various pathways, including the suppression of inflammation and OS. Recently, the role of flavonoid compounds in ICH and SAH has also received increasing interest. Thus, to serve as a resource for the prevention and treatment of ICH and SAH, the present review provided an overview of the research on flavonoid compounds in the prevention of brain damage after these two conditions have occurred.

The dual role of FSP1 in programmed cell death: resisting ferroptosis in the cell membrane and promoting necroptosis in the nucleus of THP-1 cells

BACKGROUND

Acute monocytic leukemia-M5 (AML-M5) remains a challenging disease due to its high morbidity and poor prognosis. In addition to the evidence mentioned earlier, several studies have shown that programmed cell death (PCD) serves a critical function in treatment of AML-M5. However, the role and relationship between ferroptosis and necroptosis in AML-M5 remains unclear.

METHODS

THP-1 cells were mainly treated with Erastin and IMP-366. The changes of ferroptosis and necroptosis levels were detected by CCK-8, western blot, quantitative real-time PCR, and electron microscopy. Flow cytometry was applied to detect the ROS and lipid ROS levels. MDA, 4-HNE, GSH and GSSG were assessed by ELISA kits. Intracellular distribution of FSP1 was studied by immunofluorescent staining and western blot.

RESULTS

The addition of the myristoylation inhibitor IMP-366 to erastin-treated acute monocytic leukemia cell line THP-1 cell not only resulted in greater susceptibility to ferroptosis characterized by lipid peroxidation, glutathione (GSH) depletion and mitochondrial shrinkage, as the FSP1 position on membrane was inhibited, but also increased p-RIPK1 and p-MLKL protein expression, as well as a decrease in caspase-8 expression, and triggered the characteristic necroptosis phenomena, including cytoplasmic translucency, mitochondrial swelling, membranous fractures by FSP1 migration into the nucleus via binding importin α2. It is interesting to note that ferroptosis inhibitor fer-1 reversed necroptosis.

CONCLUSION

We demonstrated that inhibition of myristoylation by IMP-366 is capable of switching ferroptosis and ferroptosis-dependent necroptosis in THP-1 cells. In these findings, FSP1-mediated ferroptosis and necroptosis are described as alternative mechanisms of PCD of THP-1 cells, providing potential therapeutic strategies and targets for AML-M5.

Iron Metabolism and Ferroptosis in Early Brain Injury after Subarachnoid Haemorrhage

At present, it appears that the prognosis for subarachnoid haemorrhage (SAH), which has a high death and disability rate, cannot be greatly improved by medication or other treatment. Recent research suggests that different types of cell death are implicated in early brain injury (EBI) after SAH, and this has been recognised as a major factor impacting the prognosis of SAH. Ferroptosis, which is a recently identified imbalance of iron metabolism and programmed cell death triggered by phospholipid peroxidation, has been shown to be involved in EBI after SAH and is thought to have a significant impact on EBI. The decomposition of cleaved haemoglobin during SAH involves the release of enormous amounts of free iron, resulting in iron metabolism disorders. Potential therapeutic targets for the signalling pathways of iron metabolism disorders and ferroptosis after SAH are constantly being discovered. To serve as a guide for research into other possible therapeutic targets, this paper will briefly describe the mechanisms of dysregulated iron metabolism and ferroptosis in the pathogenesis of SAH and highlight how they are involved in the development and promotion of EBI in SAH.

Therapeutic Potential of Natural Compounds in Subarachnoid Haemorrhage

Subarachnoid hemorrhage (SAH) is a common and fatal cerebrovascular disease with high morbidity, mortality and very poor prognosis worldwide. SAH can induce a complex series of pathophysiological processes, and the main factors affecting its prognosis are early brain injury (EBI) and delayed cerebral ischemia (DCI). The pathophysiological features of EBI mainly include intense neuroinflammation, oxidative stress, neuronal cell death, mitochondrial dysfunction and brain edema, while DCI is characterized by delayed onset ischemic neurological deficits and cerebral vasospasm (CVS). Despite much exploration in people to improve the prognostic outcome of SAH, effective treatment strategies are still lacking. In recent years, numerous studies have shown that natural compounds of plant origin have unique neuro- and vascular protective effects in EBI and DCI after SAH and long-term neurological deficits, which mainly include inhibition of inflammatory response, reduction of oxidative stress, anti-apoptosis, and improvement of blood-brain barrier and cerebral vasospasm. The aim of this paper is to systematically explore the processes of neuroinflammation, oxidative stress, and apoptosis in SAH, and to summarize natural compounds as potential targets for improving the prognosis of SAH and their related mechanisms of action for future therapies.

Triglyceride Glucose Index and Prognosis of Patients with Subarachnoid Hemorrhage

OBJECTIVE

The triglyceride glucose (TyG) index is regarded as a reliable alternative indicator for measuring insulin resistance. We investigated the association between the prognosis of patients with subarachnoid hemorrhage (SAH)and the TyG index, explored the potential of the TyG index as a new biomarker for forecasting the outcomes of SAH patients, and explored independent risk factors for predicting the condition of SAH patients.

METHODS

A retrospective analysis was performed of patients who were admitted to a single center due to SAH. Differences in clinical data and correlation between laboratory indexes, disease severity score on admission, and prognosis score were compared between the 2 groups. The study employed multivariate logistic regression analysis to examine the independent influencing aspects of Glasgow Outcome Scale score. The receiver operating characteristic curve was drawn and the area under the curve (AUC) calculated to predict the best cutoff value of the degree of neurological impairment in patients with SAH.

RESULTS

Univariate analysis showed that Glasgow Coma Scale score (86.3% vs. 12.0%, P < 0.001), Hunt-Hess grade (88.2% vs. 15.7%, P < 0.001), white blood cell count (11.20 [7.9, 15.2] vs. 9.1 [7.0, 12.2], P = 0.027), and TyG index (1.49 [1.40, 1.59] vs. 1.16 [1.06, 1.27], P < 0.001) were statistically significantly different. Multivariate analysis showed that TyG index, Hunt-Hess grade, and GCS score were independent risk factors for poor prognosis.

CONCLUSIONS

Patients with SAH may benefit from using the TyG index as a predictive method. In our clinical practice, the TyG index is beneficial for managing diseases and making decisions. More research is required to determine if improved TyG index control would lead to better clinical results in the future.

Exploring the Role of Ferroptosis-Related Circular RNAs in Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a devastating cerebrovascular event associated with high mortality and significant morbidity. Recent studies have highlighted the emerging role of ferroptosis, a novel form of regulated cell death, in the pathogenesis of SAH. Circular RNAs (circRNAs), have been found to play essential roles in various cellular processes, including gene regulation and disease pathogenesis. The expression profile of circRNAs in neural tissues, particularly in the brain, suggests their critical role in synaptic function and neurogenesis. Moreover, the interplay between circRNAs and ferroptosis-related pathways, such as iron metabolism and lipid peroxidation, is explored in the context of SAH. Understanding the functional roles of specific circRNAs in the context of SAH may provide potential therapeutic targets to attenuate ferroptosis-associated brain injury. Furthermore, the potential of circRNAs as diagnostic biomarkers for SAH severity, prognosis, and treatment response is discussed. Overall, this review highlights the significance of studying the intricate interplay between circRNAs and ferroptosis in the context of SAH. Unraveling the mechanisms by which circRNAs modulate ferroptotic cell death may pave the way for the development of novel therapeutic strategies and diagnostic approaches for SAH management, ultimately improving patient outcomes and quality of life.

EGCG-NPs inhibition HO-1-mediated reprogram iron metabolism against ferroptosis after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH), a devastating disease with a high mortality rate and poor outcomes, tightly associated with the dysregulation of iron metabolism and ferroptosis. (-)-Epigallocatechin-3-gallate (EGCG) is one of major bioactive compounds of tea catechin because of its well-known iron-chelating and antioxidative activities. However, the findings of iron-induced cell injuries after SAH remain controversial and the underlying therapeutic mechanisms of EGCG in ferroptosis is limited. Here, the ability of EGCG to inhibit iron-induced cell death following the alleviation of neurological function deficits was investigated by using in vivo SAH models. As expected, EGCG inhibited oxyhemoglobin (OxyHb)-induced the over-expression of HO-1, which mainly distributed in astrocytes and microglial cells. Subsequently, EGCG blocked ferrous iron accumulation through HO-1-mediated iron metabolic reprogramming. Therefore, oxidative stress and mitochondrial dysfunction was rescued by EGCG, which resulted in the downregulation of ferroptosis and ferritinophagy rather than apoptosis after SAH. As a result, EGCG exerted the superior therapeutic effects in the maintenance of iron homeostasis in glial cells, such as astrocytes and microglial cells, as well as in the improvement of functional outcomes after SAH. These findings highlighted that glial cells were not only the iron-rich cells in the brain but also susceptible to ferroptosis and ferritinophagy after SAH. The detrimental role of HO-1-mediated ferroptosis in glial cells can be regarded as an effective therapeutic target of EGCG in the prevention and treatment of SAH.

DMT1-mediated iron overload accelerates cartilage degeneration in Hemophilic Arthropathy through the mtDNA-cGAS-STING axis

INTRODUCTION

Excess iron contributes to Hemophilic Arthropathy (HA) development. Divalent metal transporter 1 (DMT1) delivers iron into the cytoplasm, thus regulating iron homeostasis.

OBJECTIVES

We aimed to investigate whether DMT1-mediated iron homeostasis is involved in bleeding-induced cartilage degeneration and the molecular mechanisms underlying iron overload-induced chondrocyte damage.

METHODS

This study established an in vivo HA model by puncturing knee joints of coagulation factor VIII gene knockout mice with a needle, and mimicked iron overload conditions in vitro by treatment of Ferric ammonium citrate (FAC).

RESULTS

We demonstrated that blood exposure caused iron overload and cartilage degeneration, as well as elevated expression of DMT1. Furthermore, DMT1 silencing alleviated blood-induced iron overload and cartilage degeneration. In hemophilic mice, articular cartilage degeneration was also suppressed by intro-articularly injection of DMT1 adeno-associated virus 9 (AAV9). Mechanistically, RNA-sequencing analysis indicated the association between iron overload and cGAS-STING pathway. Further, iron overload triggered mtDNA-cGAS-STING pathway activation, which could be effectively mitigated by DMT1 silencing. Additionally, we discovered that RU.521, a potent Cyclic GMP-AMP Synthase (cGAS) inhibitor, successfully suppressed the downward cascades of cGAS-STING, thereby protecting against chondrocyte damage.

CONCLUSION

Taken together, DMT1-mediated iron overload promotes chondrocyte damage and murine HA development, and targeted DMT1 may provide therapeutic and preventive approaches in HA.

NAD-Dependent Protein Deacetylase Sirtuin-1 Mediated Mitophagy Regulates Early Brain Injury After Subarachnoid Hemorrhage

Background

This study focuses on the role of SIRT1 in neuroinflammation caused by early brain injury (EBI) after subarachnoid hemorrhage (SAH), and explores its mechanism in mitophagy after SAH.

Methods

C57BL/6J mice and primary microglia SAH in vivo and in vitro models were constructed to explore the expression level of SIRT1 in neuroinflammation after SAH. Subsequently, the brain edema content, blood-brain barrier (BBB) damage and neurological function scores of the mice were observed after using the SIRT1 inhibitor EX-527. q-PCR and Western blot were used to detect relevant genes and proteins, and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of IL-6, IL-1β, and TNF-α inflammatory factors. Immunofluorescence staining was used to observe the positive level of SIRT1 and the degree of mitochondria-lysosome fusion, and transmission electron microscopy was used to observe mitochondrial damage and autophagosome levels.

Results

In in vivo and in vitro experiments, we found that SIRT1 expression increased after SAH, and neurological deficits, brain edema, and blood-brain barrier damage after SAH were aggravated. Inhibiting SIRT1 further aggravates the aforementioned damage. In addition, EX-527 can also inhibit the level of mitophagy and aggravate neuroinflammation after SAH.

Conclusion

Our results indicated that SIRT1 promotes mitophagy and alleviates neuroinflammation after SAH.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Investigation of the protective effects of piceatannol on experimental subarachnoid hemorrhage in rats

BACKGROUND

Subarachnoid hemorrhage (SAH) is one of the most prevalent brain injuries in humans which has poor prognosis and high mortality rates. Due to several medical or surgical treatment methods, a gold standard method doesn't exist for SAH treatment. Piceatannol (PCN), a natural analog of resveratrol, was reported to reduce inflammation and apoptosis promising a wide range of therapeutic alternatives. In this study, we aimed to investigate the effects of PCN in an experimental SAH model. The alleviating effects of PCN in the hippocampus in an experimental SAH model were investigated for the first time.

METHODS AND RESULTS

In this study, 27 Wistar Albino male rats (200-300 g; 7-8 week) were used. Animals were divided into three groups; SHAM, SAH, and SAH + PCN. SAH model was created with 120 µl of autologous arterial tail blood to prechiasmatic cisterna. 30 mg/kg PCN was administered intraperitoneally at 1st h after SAH. Neurological evaluation was performed with Garcia's score. RT-PCR was performed for gene expression levels in the hippocampus. Pyknosis, edema, and apoptosis were evaluated by H&E and TUNEL staining. Our results indicated that PCN administration reduced apoptosis (P < 0.01), cellular edema, and pyknosis (P < 0.05) in the hippocampus after SAH. Moreover, PCN treatment significantly decreased the expression levels of TNF-α (P < 0.01), IL-6 (P < 0.05), NF-κB (P < 0.05), and Bax (P < 0.05) in the hippocampus.

CONCLUSIONS

Our results demonstrated that PCN might be a potential therapeutic adjuvant agent for the treatment of early brain injury (EBI) following SAH. Further studies are required to clarify the underlying mechanisms and treatment options of SAH.

Ferroptosis in early brain injury after subarachnoid hemorrhage: review of literature

Spontaneous subarachnoid hemorrhage (SAH), mainly caused by ruptured intracranial aneurysms, is a serious acute cerebrovascular disease. Early brain injury (EBI) is all brain injury occurring within 72 h after SAH, mainly including increased intracranial pressure, decreased cerebral blood flow, disruption of the blood-brain barrier, brain edema, oxidative stress, and neuroinflammation. It activates cell death pathways, leading to neuronal and glial cell death, and is significantly associated with poor prognosis. Ferroptosis is characterized by iron-dependent accumulation of lipid peroxides and is involved in the process of neuron and glial cell death in early brain injury. This paper reviews the research progress of ferroptosis in early brain injury after subarachnoid hemorrhage and provides new ideas for future research.

Human umbilical cord mesenchymal stem cell-derived exosomes provide neuroprotection in traumatic brain injury through the lncRNA TUBB6/Nrf2 pathway

Recently, human umbilical cord mesenchymal stem cell (HucMSC) is a new focus of research in neurological diseases, and the beneficial effect of HucMSC is mediated by paracrine factors which are transported by exosome. Our previous study has shown that HucMSC-derived exosome could provide neuroprotection after traumatic brain injury (TBI). However, the underlying mechanisms were not fully understood. In the present study, we found that administration of exosome suppressed TBI-induced inflammation and ferroptosis. In addition, exosome activated the long non-coding ribonucleic acid (lncRNA) TUBB6/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway after TBI. However, exosome partly failed to provide neuroprotection following TBI when TUBB6 was knockdown. Importantly, exosome treatment also decreased neuron cell death, suppressed inflammation, inhibited ferroptosis and activated the lncRNA TUBB6/Nrf2 pathway after TBI in vitro. Taken together, our results provided the first evidence that HucMSC-derived exosome played a key role in neuroprotection after TBI through the lncRNA TUBB6/Nrf2 pathway.

FGF10 protects against LPS-induced epithelial barrier injury and inflammation by inhibiting SIRT1-ferroptosis pathway in acute lung injury in mice

Pulmonary alveolar epithelial cell injury is considered the main pathological and physiological change in acute lung injury. Ferroptosis in alveolar epithelial cells is one of crucial factors contributing to acute lung injury (ALI). Therefore, reducing ferroptosis and repair epithelial barrier is very necessary. More and more evidence suggested that FGF10 plays an important role in lung development and repair after injury. However, the relationship between FGF10 and ferroptosis remains unclear. This study aims to explore the regulatory role of FGF10 on ferroptosis in ALI. Differential gene expression analysis indicated that genes associated with ferroptosis showed that FGF10 can significantly alleviate LPS induced lung injury and epithelial barrier damage by decreasing levels of malonaldehyde(MDA), and lipid ROS. SIRT1 activator (Resveratrol) and inhibitor (EX527) are used in vivo showed that FGF10 protects ferroptosis of pulmonary epithelial cells through SIRT1 signal. Furthermore, knockdown of FGFR2 gene reduced the protective effect of FGF10 on acute lung injury in mice and SIRT1 activation. After the application of NRF2 inhibitor ML385 in vitro, the results showed that SIRT1 regulated the expression of ferroptosis related proteins NRF2, GPX4 and FTH1 are related to activation of NRF2. These data indicate that SIRT-ferroptosis was one of the critical mechanisms contributing to LPS-induced ALI. FGF10 is promising as a therapeutic candidate against ALI through inhibiting ferroptosis.

Transfer of cGAMP from neuron to microglia activates microglial type I interferon responses after subarachnoid hemorrhage

Primary subarachnoid hemorrhage (SAH) is a type of acute stroke, accounting for approximately 10% of cases, with high disability and mortality rate. Early brain injury (EBI) is a critical factor in determining SAH mortality; however, there are no effective treatment interventions for EBI. Based on our results, the transmission of cyclic GMP-AMP (cGAMP) from neurons to microglia is a key molecular event that triggers type I interferon response, amplifies neuroinflammation, and leads to neuronal apoptosis. Abnormal intracytoplasmic mitochondrial DNA (mtDNA) is the initiating factor of the cGAS-cGAMP-STING signaling axis. Overall, the cGAS-cGAMP-STING signaling axis is closely associated with neuroinflammation after subarachnoid hemorrhage. Targeting cGAS triggered by cytoplasmic mtDNA may be useful for comprehensive clinical treatment of patients after SAH. Further studies targeting cGAS-specific antagonists for treating SAH are warranted. Video Abstract.

Menaquinone-4 attenuates ferroptosis by upregulating DHODH through activation of SIRT1 after subarachnoid hemorrhage

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.

Perampanel attenuates oxidative stress and pyroptosis following subarachnoid hemorrhage via the SIRT3/FOXO3α pathway

Subarachnoid hemorrhage (SAH) occurs most commonly after rupture of an aneurysm, resulting in high disability and mortality due to the absence of effective therapy. Its subsequent stage, early brain injury (EBI), promotes the sustainable development of injury in the brain and ultimately leads to poor prognosis. As a new antiepileptic drug, the effect of perampanel on EBI after SAH is unknown. Pyroptosis, a process of inflammatory programmed cell death, has been confirmed in most studies to play a substantial role in aggravating SAH-post EBI. Similarly, oxidative stress is closely involved in neuronal pyroptosis and the pathophysiological mechanism of SAH-post EBI, leading to a devastating outcome for SAH patients. Nonetheless, no studies have been conducted to determine whether perampanel reduces pyroptosis and oxidative stress in the context of SAH-induced EBI. Rat SAH model via endovascular perforation was constructed in this study, to assess the neuroprotective effect of perampanel on SAH-post EBI, and to clarify the possible molecular mechanism. By means of the neurological score, brain edema detection, FJB staining, immunofluorescence, WB, ELISA, and ROS assay, we found that perampanel can improve neuroscores and reduce brain edema and neuronal degeneration at 24 h after SAH; we also found that perampanel reduced oxidative stress, neuronal pyroptosis, and inhibition of the SIRT3-FOXO3α pathway at 24 h after SAH. When 3-TYP, an inhibitor of SIRT3, was administered, the effects of perampanel on the SIRT3-FOXO3a pathway, antioxidant stress, and neuronal pyroptosis were reversed. Taken together, our data indicate that perampanel attenuates oxidative stress and pyroptosis following subarachnoid hemorrhage via the SIRT3/FOXO3α pathway. This study highlights the application value of perampanel in subarachnoid hemorrhage and lays a foundation for clinical research and later transformation of perampanel in SAH.

Abnormalities in the SIRT1-SIRT3 axis promote myocardial ischemia-reperfusion injury through ferroptosis caused by silencing the PINK1/Parkin signaling pathway

BACKGROUND

Myocardial ischemia-reperfusion injury (MIRI) is one of the main reasons for poor prognosis in patients with ischemic cardiomyopathy (ICM). To date, the mechanism remains unknown. As members of the silent information regulator 2 (SIR2) family, both SIRT1 and SIRT3 have been shown to play critical roles in protecting cardiomyocytes against MIRI, but their specific protective mechanism, their interact between the two and their relationship with ferroptosis are still unclear. Hence, in this study, we investigated the interact and specific mechanism of SIRT1 and SIRT3 in protecting cardiomyocytes against MIRI, as well as their association with ferroptosis.

METHODS

Bioinformatics analysis methods were used to explore the expression of SIRT1 and SIRT3 during MIRI, and then a cell hypoxia/reoxygenation injury model was constructed to verify the results. Then, Pearson correlation analysis was further used to explore the relationship between SIRT1 and SIRT3, whose roles in the regulation of ferroptosis were also analysed by gene knock down, Western Blotting and flow cytometry. Several biomarkers, such as Fe2+ concentration, lipid peroxidation marker MDA and mitochondrial membrane potential (MMP), were used to evaluate changes in ferroptosis.

RESULTS

The expression of SIRT1 and SIRT3 was abnormal during MIRI, and SIRT1 was significantly negatively correlated with SIRT3 in the SIRT1-SIRT3 axis. Further analysis revealed that the SIRT1-SIRT3 axis was closely correlated with ferroptosis, and its silencing effectively increase the incidence of ferroptosis. Furthermore, SIRT1-SIRT3 axis silencing was accompanied by changes in PINK1, Parkin, P62/SQSTM1 and LC3 expression. PINK1 silencing significantly increased the incidence of ferroptosis, while resveratrol (Res) and/or honokiol (HKL) effectively reversed the outcome.

CONCLUSION

Abnormalities in the SIRT1-SIRT3 axis promote MIRI through ferroptosis caused by silencing the PINK1/Parkin signaling pathway.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Managing ferroptosis-related diseases with indirect dietary modulators of ferroptosis

Ferroptosis is an iron-dependent form of programmed cell death driven by excessive oxidation of polyunsaturated phospholipids on cellular membranes. Accumulating evidence suggests that ferroptosis has been implicated in the pathological process of various diseases, such as cardiovascular diseases, neurological diseases, liver diseases, kidney injury, lung injury, diabetes, and cancer. Targeting ferroptosis is therefore considered to be a reasonable strategy to fight against ferroptosis-associated diseases. Many dietary bioactive agents have been identified to be able to either suppress or promote ferroptosis, indicating that ferroptosis-based intervention by dietary approach may be an effective strategy for preventing and treating diseases associated with ferroptosis dysregulation. In this review, we summarize the present understanding of the functional role of ferroptosis in the pathogenesis of aforementioned diseases with an emphasis on the evidence of managing ferroptosis-related diseases with indirect dietary modulators of ferroptosis and propose issues that need to be addressed to promote practical application of dietary approach targeting ferroptosis.

Salidroside ameliorates acetaminophen-induced acute liver injury through the inhibition of endoplasmic reticulum stress-mediated ferroptosis by activating the AMPK/SIRT1 pathway

Acetaminophen (APAP) overdose has long been considered a major cause of drug-induced liver injury. Ferroptosis is a type of programmed cell death mediated by iron-dependent lipid peroxidation. Endoplasmic reticulum (ER) stress is a systemic response triggered by the accumulation of unfolded or misfolded proteins in the ER. Ferroptosis and ER stress have been proven to contribute to the progression of APAP-induced acute liver injury (ALI). It was reported that salidroside protects against APAP-induced ALI, but the potential mechanism remain unknown. In this study, male C57BL/6 J mice were intraperitoneally (i.p.) injected APAP (500 mg/kg) to induce an ALI model. Salidroside was i.p. injected at a dose of 100 mg/kg 2 h prior to APAP administration. Mice were sacrificed 12 h after APAP injection and the liver and serum of the mice were obtained for histological and biochemistry analysis. AML12 cells were used in in vitro assays. The results indicated that salidroside mitigated glutathione degradation via inhibiting cation transport regulator homolog 1 (CHAC1) to attenuate ferroptosis, and simultaneously suppressing PERK-eIF2α-ATF4 axis-mediated ER stress, thus alleviating APAP-induced ALI. However, PERK activator CCT020312 and overexpression of ATF4 inhibited the protective function of salidroside on CHAC1-mediated ferroptosis. Besides this, activation of the AMPK/SIRT1 signaling pathway by salidroside was demonstrated to have a protective effect against APAP-induced ALI. Interestingly, selective inhibition of SIRT1 ameliorated the protective effects of salidroside on ER stress and ferroptosis. Overall, salidroside plays a significant part in the mitigation of APAP-induced ALI by activating the AMPK/SIRT1 signaling to inhibit ER stress-mediated ferroptosis in the ATF4-CHAC1 axis.

ACSL4-Mediated Ferroptosis and Its Potential Role in Central Nervous System Diseases and Injuries

As an iron-dependent regulated form of cell death, ferroptosis is characterized by iron-dependent lipid peroxidation and has been implicated in the occurrence and development of various diseases, including nervous system diseases and injuries. Ferroptosis has become a potential target for intervention in these diseases or injuries in relevant preclinical models. As a member of the Acyl-CoA synthetase long-chain family (ACSLs) that can convert saturated and unsaturated fatty acids, Acyl-CoA synthetase long-chain familymember4 (ACSL4) is involved in the regulation of arachidonic acid and eicosapentaenoic acid, thus leading to ferroptosis. The underlying molecular mechanisms of ACSL4-mediated ferroptosis will promote additional treatment strategies for these diseases or injury conditions. Our review article provides a current view of ACSL4-mediated ferroptosis, mainly including the structure and function of ACSL4, as well as the role of ACSL4 in ferroptosis. We also summarize the latest research progress of ACSL4-mediated ferroptosis in central nervous system injuries and diseases, further proving that ACSL4-medicated ferroptosis is an important target for intervention in these diseases or injuries.

The mechanism of ferroptosis in early brain injury after subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a cerebrovascular accident with an acute onset, severe disease characteristics, and poor prognosis. Within 72 hours after the occurrence of SAH, a sequence of pathological changes occur in the body including blood-brain barrier breakdown, cerebral edema, and reduced cerebrovascular flow that are defined as early brain injury (EBI), and it has been demonstrated that EBI exhibits an obvious correlation with poor prognosis. Ferroptosis is a novel programmed cell death mode. Ferroptosis is induced by the iron-dependent accumulation of lipid peroxides and reactive oxygen species (ROS). Ferroptosis involves abnormal iron metabolism, glutathione depletion, and lipid peroxidation. Recent study revealed that ferroptosis is involved in EBI and is significantly correlated with poor prognosis. With the gradual realization of the importance of ferroptosis, an increasing number of studies have been conducted to examine this process. This review summarizes the latest work in this field and tracks current research progress. We focused on iron metabolism, lipid metabolism, reduction systems centered on the GSH/GPX4 system, other newly discovered GSH/GPX4-independent antioxidant systems, and their related targets in the context of early brain injury. Additionally, we examined certain ferroptosis regulatory mechanisms that have been studied in other fields but not in SAH. A link between death and oxidative stress has been described. Additionally, we highlight the future research direction of ferroptosis in EBI of SAH, and this provides new ideas for follow-up research.

Resveratrol Alleviates Diabetic Periodontitis-Induced Alveolar Osteocyte Ferroptosis Possibly via Regulation of SLC7A11/GPX4

The mode and mechanism of diabetic periodontitis-induced alveolar-osteocyte death are still unclear. This study aimed to investigate the occurrence of ferroptosis in alveolar osteocytes during diabetic periodontitis and the therapeutic potential of resveratrol to alleviate osteocyte ferroptosis. Diabetic periodontitis was induced in C57/BL6-male mice and treated with or without resveratrol. Periodontitis pathogenicity was analyzed by micro-CT and histology, and alveolar-osteocyte ferroptosis was analyzed by immunohistochemistry. MLOY4 osteocytes were treated with P. gingivalis-derived lipopolysaccharide (LPS)+advanced glycosylated end products (AGEs) mimicking diabetic periodontitis condition in vitro, with or without resveratrol or ferrostatin-1 (ferroptosis inhibitor). Osteocyte ferroptosis and expression of inflammatory mediators were analyzed. Diabetic periodontitis aggravated periodontitis pathogenicity and inhibited the expression of GPX4 and SLC7A11 in alveolar osteocytes and resveratrol alleviated these effects. LPS+AGEs triggered osteocyte ferroptosis in vitro as indicated by the downregulated GPX4 and SLC7A11, upregulated malondialdehyde, disrupted mitochondrial morphology, and overexpressed pro-inflammatory mediators IL-1β, TNF-α, SOST, RANKL, and IL-6, and ferrostatin-1 or resveratrol treatment reversed these effects. LPS+AGEs upregulated pIKBα and pNF-κB p65 expression in osteocytes, and resveratrol or ferrostatin-1 reversed this effect. In conclusion, diabetic periodontitis triggers alveolar osteocyte ferroptosis possibly via disruption of the SLC7A11/GPX4 axis, and resveratrol has therapeutic potential to correct this biological event.

The Critical Role of Sirt1 in Subarachnoid Hemorrhages: Mechanism and Therapeutic Considerations

The subarachnoid hemorrhage (SAH) is an important cause of death and long-term disability worldwide. As a nicotinamide adenine dinucleotide-dependent deacetylase, silent information regulator 1 (Sirt1) is a multipotent molecule involved in many pathophysiological processes. A growing number of studies have demonstrated that Sirt1 activation may exert positive effects on SAHs by regulating inflammation, oxidative stress, apoptosis, autophagy, and ferroptosis. Thus, Sirt1 agonists may serve as potential therapeutic drugs for SAHs. In this review, we summarized the current state of our knowledge on the relationship between Sirt1 and SAHs and provided an updated overview of the downstream molecules of Sirt1 in SAHs.

Neuroprotective Effects of Piceatannol on Olfactory Bulb Injury after Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) accounts for 5% of all stroke cases and is responsible for significant permanent brain and neurological damage within the first few days. Loss of smell is one of those neurological disorders following olfactory bulb injury after SAH. Olfaction plays a critical role in several aspects of life. The primary underlying mechanism of olfactory bulb (OB) injury and loss of smell after SAH remains unknown. Piceatannol (PIC), a natural stilbene, possesses anti-inflammatory and anti-apoptotic effects against various diseases. In this study, we aimed to investigate the potential therapeutic effects of PIC on OB injury following SAH at molecular mechanism based on SIRT1, inflammatory (TNF-α, IL1-β, NF-κB, IL-6, TLR4), and apoptosis (p53, Bax, Bcl-2, caspase-3)-related gene expression markers and histopathology level; 27 male Wistar Albino rats were used in a pre-chiasmatic subarachnoid hemorrhage model. Animals were divided into groups (n = 9): SHAM, SAH, and PIC. Garcia's neurological examination, brain water content, RT-PCR, histopathology, and TUNEL analyses were performed in all experimental groups with OB samples. Our results indicated that PIC administration significantly suppressed inflammatory molecules (TNF-α, IL-6, IL1-β, TLR4, NF-κB, SIRT1) and apoptotic molecules (caspase-3, p53, Bax). We also evaluated edema levels and cell damage in OB injury after SAH. Ameliorative effects of PIC are also observed at the histopathology level. Garcia's neurological score test performed a neurological assessment. This study is the first to demonstrate the neuroprotective effects of PIC on OB injury after SAH. It suggests that PIC would be a potential therapeutic agent for alleviating OB injury after SAH.

Sirtuin-3: A potential target for treating several types of brain injury

Sirtuin-3 (SIRT3) is responsible for maintaining mitochondrial homeostasis by deacetylating substrates in an NAD+-dependent manner. SIRT3, the primary deacetylase located in the mitochondria, controls cellular energy metabolism and the synthesis of essential biomolecules for cell survival. In recent years, increasing evidence has shown that SIRT3 is involved in several types of acute brain injury. In ischaemic stroke, subarachnoid haemorrhage, traumatic brain injury, and intracerebral haemorrhage, SIRT3 is closely related to mitochondrial homeostasis and with the mechanisms of pathophysiological processes such as neuroinflammation, oxidative stress, autophagy, and programmed cell death. As SIRT3 is the driver and regulator of a variety of pathophysiological processes, its molecular regulation is significant. In this paper, we review the role of SIRT3 in various types of brain injury and summarise SIRT3 molecular regulation. Numerous studies have demonstrated that SIRT3 plays a protective role in various types of brain injury. Here, we present the current research available on SIRT3 as a target for treating ischaemic stroke, subarachnoid haemorrhage, traumatic brain injury, thus highlighting the therapeutic potential of SIRT3 as a potent mediator of catastrophic brain injury. In addition, we have summarised the therapeutic drugs, compounds, natural extracts, peptides, physical stimuli, and other small molecules that may regulate SIRT3 to uncover additional brain-protective mechanisms of SIRT3, conduct further research, and provide more evidence for clinical transformation and drug development.

Macrophage/Microglia Sirt3 Contributes to the Anti-inflammatory Effects of Resveratrol Against Experimental Intracerebral Hemorrhage in Mice

Intracerebral hemorrhage (ICH) is a devastating stroke type with high mortality and disability. Inflammatory response induced by macrophages/microglia (M/Ms) activation is one of the leading causes of brain damage after ICH. The anti-inflammatory effects of resveratrol (RSV) have already been evaluated in several models of central nervous system disease. Therefore, we designed the current study to assess the role of RSV in ICH and explore its downstream mechanism related to Sirt3. The autologous artery blood injection was administrated to create an ICH mouse model. M/Ms-specific Sirt3 knockout Sirt3^f/f; CX3CR1-Cre (Sirt3 cKO) mouse was used to evaluate the role of Sirt3 on RSV treatment. Neuronal function and hematoma volume were assessed to indicate brain damage. The pro-inflammatory marker (CD16) and cytokine (TNF) were measured to evaluate the inflammatory effects. Our results showed that RSV treatment alleviates neurological deficits, reduces cell death, and increases hematoma clearance on day 7 after ICH. In addition, RSV effectively suppressed CD16⁺ M/Ms activation and decreased TNF release. In Sirt3 cKO mice, the protective effects of RSV were abolished, indicating the potential mechanism of RSV was partially due to Sirt3 signaling activation. Therefore, RSV could be a promising candidate and therapeutic agent for ICH and Sirt3 could be a potential target to inhibit inflammation.

Elucidating the progress and impact of ferroptosis in hemorrhagic stroke

Hemorrhagic stroke is a devastating cerebrovascular disease with high morbidity and mortality, for which effective therapies are currently unavailable. Based on different bleeding sites, hemorrhagic stroke can be generally divided into intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH), whose pathogenesis share some similarity. Ferroptosis is a recently defined programmed cell deaths (PCDs), which is a critical supplement to the hypothesis on the mechanism of nervous system injury after hemorrhagic stroke. Ferroptosis is characterized by distinctive morphological changes of mitochondria and iron-dependent accumulation of lipid peroxides. Moreover, scientists have successfully demonstrated the involvement of ferroptosis in animal models of ICH and SAH, indicating that ferroptosis is a promising target for hemorrhagic stroke therapy. However, the studies on ferroptosis still faces a serious of technical and theoretical challenges. This review systematically elaborates the role of ferroptosis in the pathogenesis of hemorrhagic stroke and puts forward some opinions on the dilemma of ferroptosis research.

FERROPTOSIS IN THE PATHOGENESIS OF BRAIN TUMORS

The field of research on ferroptosis has seen explosive growth in the past few years since the term was coined in 2012. This review highlights the current state of knowledge on the developmental mechanism of this unique mode of cell death, induced by iron-dependent phospholipid peroxidation and which is regulated by a variety of cellular metabolic events, including redox homeostasis. Among these factors, the xCT. system, an amino acid antiporter that supports the synthesis of glutathione (GSH) and oxidation protection. The risk of iron accumulation in neurons, astrocytes, oligodendrocytes, microglia, and Schwann cells and the development of oxidative stress is discussed. Ferroptosis triggers a cascade of events including activation of inflammation, oxidation of neurotransmitters, impaired neuronal communication, myelin sheath degeneration, astrocyte dysregulation, dementia, and cell death. On the other hand, the exceptional vulnerability to ferroptosis of cancer cells originating from the nervous tissue is estimated. Evidence is given for the initiation of ferroptosis in tumor cells as a factor in inhibiting the growth and death of these cells. Particular attention is paid to the pharmacological modulation of ferroptosis through its induction and inhibition for the treatment of drug-resistant cancers. The choice of targets for the induction of ferroptosis in cancer cells is discussed. Glutathione peroxidase 4 and xCT amino acid antiporter are recognized as the most preferred targets and the antitumor potential of their inhibition and side effects are being evaluated.

An update on the therapeutic implications of long-chain acyl-coenzyme A synthetases in nervous system diseases

Long-chain acyl-coenzyme A synthetases (ACSLs) are a family of CoA synthetases that activate fatty acid (FA) with chain lengths of 12-20 carbon atoms by forming the acyl-AMP derivative in an isozyme-specific manner. This family mainly includes five members (ACSL1, ACSL3, ACSL4, ACSL5, and ACSL6), which are thought to have specific and different functions in FA metabolism and oxidative stress of mammals. Accumulating evidence shows that the dysfunction of ACSLs is likely to affect cell proliferation and lead to metabolic diseases in multiple organs and systems through different signaling pathways and molecular mechanisms. Hence, a central theme of this review is to emphasize the therapeutic implications of ACSLs in nervous system disorders.

Inflammation and immune cell abnormalities in intracranial aneurysm subarachnoid hemorrhage (SAH): Relevant signaling pathways and therapeutic strategies

Intracranial aneurysm subarachnoid hemorrhage (SAH) is a cerebrovascular disorder associated with high overall mortality. Currently, the underlying mechanisms of pathological reaction after aneurysm rupture are still unclear, especially in the immune microenvironment, inflammation, and relevant signaling pathways. SAH-induced immune cell population alteration, immune inflammatory signaling pathway activation, and active substance generation are associated with pro-inflammatory cytokines, immunosuppression, and brain injury. Crosstalk between immune disorders and hyperactivation of inflammatory signals aggravated the devastating consequences of brain injury and cerebral vasospasm and increased the risk of infection. In this review, we discussed the role of inflammation and immune cell responses in the occurrence and development of aneurysm SAH, as well as the most relevant immune inflammatory signaling pathways [PI3K/Akt, extracellular signal-regulated kinase (ERK), hypoxia-inducible factor-1α (HIF-1α), STAT, SIRT, mammalian target of rapamycin (mTOR), NLRP3, TLR4/nuclear factor-κB (NF-κB), and Keap1/nuclear factor (erythroid-derived 2)-like 2 (Nrf2)/ARE cascades] and biomarkers in aneurysm SAH. In addition, we also summarized potential therapeutic drugs targeting the aneurysm SAH immune inflammatory responses, such as nimodipine, dexmedetomidine (DEX), fingolimod, and genomic variation-related aneurysm prophylactic agent sunitinib. The intervention of immune inflammatory responses and immune microenvironment significantly reduces the secondary brain injury, thereby improving the prognosis of patients admitted to SAH. Future studies should focus on exploring potential immune inflammatory mechanisms and developing additional therapeutic strategies for precise aneurysm SAH immune inflammatory regulation and genomic variants associated with aneurysm formation.

Activation of Sirtuin-1 by Pinocembrin Treatment Contributes to Reduced Early Brain Injury after Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) as a devastating neurological disorder is closely related to heightened oxidative insults and neuroinflammatory injury. Pinocembrin, a bioflavonoid, exhibits different biological functions, such as immunomodulatory, anti-inflammatory, antioxidative, and cerebroprotective activities. Herein, we examined the protective effects and molecular mechanisms of pinocembrin in a murine model of SAH. Using an endovascular perforation model in rats, pinocembrin significantly mitigated SAH-induced neuronal tissue damage, including inflammatory injury and free-radical insults. Meanwhile, pinocembrin improved behavior function and reduced neuronal apoptosis. We also revealed that sirtuin-1 (SIRT1) activation was significantly enhanced by pinocembrin. In addition, pinocembrin treatment evidently enhanced peroxisome proliferator-activated receptor-γ coactivator expression and suppressed ac-nuclear factor-kappa B levels. In contrast, EX-527, a selective SIRT1 inhibitor, blunted the protective effects of pinocembrin against SAH by suppressing SIRT1-mediated signaling. These results suggested that the cerebroprotective actions of pinocembrin after SAH were through SIRT1-dependent pathway, suggesting the potential application of pinocembrin for the treatment of SAH.

Crosstalk among N6-methyladenosine modification and RNAs in central nervous system injuries

Central nervous system (CNS) injuries, including traumatic brain injury (TBI), intracerebral hemorrhage (ICH) and ischemic stroke, are the most common cause of death and disability around the world. As the most common modification on ribonucleic acids (RNAs), N6-methyladenosine (m6A) modification has recently attracted great attentions due to its functions in determining the fate of RNAs through changes in splicing, translation, degradation and stability. A large number of studies have suggested that m6A modification played an important role in brain development and involved in many neurological disorders, particularly in CNS injuries. It has been proposed that m6A modification could improve neurological impairment, inhibit apoptosis, suppress inflammation, reduce pyroptosis and attenuate ferroptosis in CNS injuries via different molecules including phosphatase and tensin homolog (PTEN), NLR family pyrin domain containing 3 (NLRP3), B-cell lymphoma 2 (Bcl-2), glutathione peroxidase 4 (GPX4), and long non-coding RNA (lncRNA). Therefore, m6A modification showed great promise as potential targets in CNS injuries. In this article, we present a review highlighting the role of m6A modification in CNS injuries. Hence, on the basis of these properties and effects, m6A modification may be developed as therapeutic agents for CNS injury patients.