PARK2-dependent mitophagy induced by acidic postconditioning protects against focal cerebral ischemia and extends the reperfusion window

Mitophagy in acute central nervous system injuries: regulatory mechanisms and therapeutic potentials

Acute central nervous system injuries, including ischemic stroke, intracerebral hemorrhage, subarachnoid hemorrhage, traumatic brain injury, and spinal cord injury, are a major global health challenge. Identifying optimal therapies and improving the long-term neurological functions of patients with acute central nervous system injuries are urgent priorities. Mitochondria are susceptible to damage after acute central nervous system injury, and this leads to the release of toxic levels of reactive oxygen species, which induce cell death. Mitophagy, a selective form of autophagy, is crucial in eliminating redundant or damaged mitochondria during these events. Recent evidence has highlighted the significant role of mitophagy in acute central nervous system injuries. In this review, we provide a comprehensive overview of the process, classification, and related mechanisms of mitophagy. We also highlight the recent developments in research into the role of mitophagy in various acute central nervous system injuries and drug therapies that regulate mitophagy. In the final section of this review, we emphasize the potential for treating these disorders by focusing on mitophagy and suggest future research paths in this area.

HBCOC attenuates cerebral ischemia-reperfusion injury in mice by inhibiting the inflammatory response and autophagy via TREM-1/ERK/NF-κB

OBJECTIVE

Hemoglobin-based carbon monoxide carrier (HBCOC) can dissociate carbon monoxide and ameliorate organ damage by inhibiting inflammation and oxidative stress. In this study, we evaluated its effect on cerebral ischemia-reperfusion injury in mice and explored its potential mechanism.

METHODS

A middle cerebral artery occlusion/reperfusion (MCAO/R) mouse model was established using the wire embolization method, and HBCOC or equivalent normal saline was administered via the tail vein during reperfusion. HE staining and TEM were used to observe the injury in the tissue. The levels of IL-1β, IL-6, TNF-α were detected by ELISA and RT-qPCR, meantime, western blotting were used to detect expressions of TREM-1, ERK, NF-κB,LC3 and P62.

RESULTS

We found that the HBCOC treatment alleviated nerve injury and reduced the cerebral infarction area caused by ischemia-reperfusion, simultaneously lowered the expression of IL-1β, IL-6, and TNF-α in plasma and brain tissues. HBCOC suppressed the levels of LC3II, lysosomes, and autophagy in the brain, suggesting potent inhibition of autophagy. Mechanistic analysis indicated that the expression of TREM-1/ERK/NF-κB pathway-related proteins and mRNA was higher in the saline group than that in the HBCOC group. HBCOC combined with the targeting TREM-1 receptor inhibitors LP17 inhibited the expression of the TREM-1 protein, further reducing the release of inflammatory factors and autophagy, restoring nerve function and infarct area after reperfusion, and exerting an overall protective effect against cerebral reperfusion injury. In summary, our results indicated that HBCOC alleviated cerebral ischemia-reperfusion injury in mice and inhibited inflammation and autophagy via TREM-1.

Methyl isoeugenol suppresses NLRP3 inflammasome-mediated pyroptosis via activation of Nrf2/NQO1/HO-1 signaling in cerebral ischemia-reperfusion injury

Microglial neuroinflammation is considered to be a vital injury factor aggravating ischemia-reperfusion (I/R) injury on the progression of cerebral ischemic stroke. Mounting evidences have verified the effect of pyroptosis mediated by NLRP3 inflammasome on modulating microglial phenotype, and maintaining the microglial M1/M2 phenotype balance could be a novel target to ameliorate cerebral I/R injury. Herein, we focused on the anti-neuroinflammatory effect of methyl isoeugenol, a bioactive compound isolated from Acorus tatarinowii Schott, on nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated NLRP3 inflammasome in vivo or in vitro. The results showed that methyl isoeugenol reduced cerebral infarct volume, modulated microglia M1/M2 phenotypes, and protected against NLRP3 inflammasome-primed pyroptosis. Mechanistically, methyl isoeugenol increased the nuclear translocation of Nrf2 and decreased that of NF-κB, and consequently, upregulated cellular antioxidants (HO-1 and NQO1), with the increased expression of antioxidant enzymes SOD and the decreased expression of lipid peroxidation MDA. These findings suggest that Nrf2 may serve as a vital target for the protective effect of methyl isoeugenol, making methyl isoeugenol as a promising anti-neuroinflammatory agent for NLRP3 inflammasome mediated microglial neuroinflammation in I/R injury.

Acupuncture alleviates hemorrhagic transformation after delayed rt-PA treatment for acute ischemic stroke by regulating the mitophagy-NLRP3 inflammasome pathway

Background

The clinical application of recombinant tissue plasminogen activator (rt-PA) is significantly constrained by hemorrhagic transformation (HT), a common and severe complication following thrombolysis for ischemic stroke. Notably, the mitochondrial injury-mediated NLRP3 inflammasome plays a crucial role in HT after delayed rt-PA thrombolysis in acute ischemic stroke. Although acupuncture has demonstrated antioxidant and anti-inflammatory effects in acute cerebral infarction, its impact on delayed rt-PA thrombolysis, especially concerning mitophagy and the NLRP3 inflammasome, remains unclear. This study investigates how acupuncture protects against HT resulting from mitochondrial damage and NLRP3 inflammasome activation after delayed rt-PA thrombolysis in acute cerebral stroke.

Methods

We selected an embolic stroke model in rats and assessed brain injury after delayed rt-PA in acute ischemic stroke using neurological deficit score, volume of brain infarct, the permeability assay of the blood-brain barrier (BBB), and HT. Then, the levels of proteins and mRNA involved in mitophagy and the NLRP3 inflammasome pathway were measured by western blot and real-time PCR. The levels of interleukin-18 (IL-18) and interleukin-1β (IL-1β) were assessed using enzyme-linked immunosorbent assay (ELISA). Morphological changes in the BBB and mitochondria of neurons were observed via transmission electron microscopy.

Results

Acupuncture significantly improved neurological deficit scores, volume of cerebral infarction, BBB destruction, and HT in an embolic stroke model rat. Furthermore, acupuncture induced mitophagy and substantially downregulated the activity of the NLRP3 inflammasome. Additionally, the use of mitochondrial inhibitors significantly reversed the suppressive impact of acupuncture on the NLRP3 inflammasome.

Conclusion

Acupuncture can promote mitophagy and suppress NLRP3 inflammasome activation to decrease HT after delayed rt-PA therapy for acute ischemic stroke.

Modulation of autophagy by melatonin and its receptors: implications in brain disorders

Autophagy plays a crucial role in maintaining neuronal homeostasis and function, and its disruption is linked to various brain diseases. Melatonin, an endogenous hormone that primarily acts through MT1 and MT2 receptors, regulates autophagy via multiple pathways. Growing evidence indicates that melatonin's ability to modulate autophagy provides therapeutic and preventive benefits in brain disorders, including neurodegenerative and affective diseases. In this review, we summarize the key mechanisms by which melatonin affects autophagy and explore its therapeutic potential in the treatment of brain disorders.

G6PD protects against cerebral ischemia-reperfusion injury by inhibiting excessive mitophagy

AIMS

Cerebral ischemia-reperfusion injury (CIRI) exacerbates post-stroke brain damage. We aimed to understand the role of glucose-6-phosphate dehydrogenase (G6PD) in CIRI and mitophagy.

MATERIALS AND METHODS

Lentivirus and small interfering RNA were utilized to suppress G6PD in tissues and cells, leading to the establishment of in vivo and in vitro models of ischemia-reperfusion following middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation/ reoxygenation (OGD/R). The expression and function of G6PD were investigated through differential gene analysis and weighted correlation network analysis (WGCNA), immunofluorescence, and western blotting (WB).

KEY FINDINGS

G6PD mRNA levels increased 3 d after MCAO, and G6PD protein expression was elevated in the ischemic penumbra of mice and HT22 cells following OGD/R. G6PD knockdown increased neural deficits, enlarged infarct volume in mice after CIRI, and reduced HT22 cell survival during OGD/R. WGCNA indicated a correlation between G6PD and mitophagy in CIRI. Following G6PD knockdown, the p-DRP1/DRP ratio increased, the PINK1/Parkin pathway was further activated, and TOMM20 expression was downregulated. The mitophagy inhibitor Mdivi-1 reversed these changes, as well as the nerve damage caused by G6PD knockdown, and alleviated mitochondrial damage in the ischemic penumbra.

SIGNIFICANCE

The role of G6PD in CIRI was revealed and its interaction with mitophagy was explored, providing important insights for understanding the molecular mechanism of CIRI and developing new therapeutic strategies.

A quinolinyl analog of resveratrol improves neuronal damage after ischemic stroke by promoting Parkin-mediated mitophagy

Ischemic stroke (IS) is a prevalent neurological disorder often resulting in significant disability or mortality. Resveratrol, extracted from Polygonum cuspidatum Sieb. et Zucc. (commonly known as Japanese knotweed), has been recognized for its potent neuroprotective properties. However, the neuroprotective efficacy of its derivative, (E)-4-(3,5-dimethoxystyryl) quinoline (RV02), against ischemic stroke remains inadequately explored. This study aimed to evaluate the protective effects of RV02 on neuronal ischemia-reperfusion injury both in vitro and in vivo. The research utilized an animal model of middle cerebral artery occlusion/reperfusion and SH-SY5Y cells subjected to oxygen-glucose deprivation and reperfusion to simulate ischemic conditions. The findings demonstrate that RV02 attenuates neuronal mitochondrial damage and scavenges reactive oxygen species (ROS) through mitophagy activation. Furthermore, Parkin knockdown was found to abolish RV02's ability to activate mitophagy and neuroprotection in vitro. These results suggest that RV02 shows promise as a neuroprotective agent, with the activation of Parkin-mediated mitophagy potentially serving as the primary mechanism underlying its neuroprotective effects.

The mitochondria as a potential therapeutic target in cerebral I/R injury

Ischemic stroke is a major cause of mortality and disability worldwide. Among patients with ischemic stroke, the primary treatment goal is to reduce acute cerebral ischemic injury and limit the infarct size in a timely manner by ensuring effective cerebral reperfusion through the administration of either intravenous thrombolysis or endovascular therapy. However, reperfusion can induce neuronal death, known as cerebral reperfusion injury, for which effective therapies are lacking. Accumulating data supports a paradigm whereby cerebral ischemia/reperfusion (I/R) injury is coupled with impaired mitochondrial function, contributing to the pathogenesis of ischemic stroke. Herein, we review recent evidence demonstrating a heterogeneous mitochondrial response following cerebral I/R injury, placing a specific focus on mitochondrial protein modifications, reactive oxygen species, calcium (Ca2+), inflammation, and quality control under experimental conditions using animal models.

LncRNA Tug1 Regulates Post-Stroke Microglial Pyroptosis via PINK1/Parkin-Mediated Mitophagy

Microglia, the central nervous system's primary immune cells, play a key role in the progression of cerebral ischemic stroke, particularly through their involvement in pyroptosis. The long non-coding RNA taurine up-regulated gene 1 (Tug1) is elevated during ischemic stroke and is critical in driving post-stroke neuroinflammation. However, the underlying molecular mechanisms remain unclear. This study explores the biological role of Tug1 and its potential mechanisms in regulating pyroptosis in microglia. We utilized an in vivo photothrombosis (PT) mice model and an in vitro oxygen-glucose deprivation and reperfusion (OGD/R) BV2 cell model to explore the mechanisms underlying ischemic stroke. Initially, we assessed the expression levels of Tug1 in the OGD/R model in vitro and the PT model in vivo. Subsequently, we investigated the impact of Tug1 on microglial pyroptosis by knocking down Tug1, silencing the PTEN-induced putative kinase 1 (Pink1) expression, and employing the mitophagy inhibitor mdivi-1. Tug1 exacerbated microglial pyroptosis by inhibiting mitophagy in both in vivo and in vitro models. The increase in mitophagy observed following Tug1 knockdown was reversed by either silencing Pink1 expression or using the mitophagy inhibitor mdivi-1. This reversal resulted in exacerbated pyroptosis and worsened neurological damage. Further mechanistic studies revealed that Tug1 knockdown significantly reduced microglial pyroptosis and alleviated neuronal damage by enhancing PINK1/Parkin-mediated mitophagy. For the first time, this study reveals that Tug1 promotes hypoxia-induced microglial pyroptosis by inhibiting PINK1/Parkin-mediated mitophagy, potentially providing a promising therapeutic target for ischemic inflammatory injury.

Exercise training alleviates neuronal apoptosis and re-establishes mitochondrial quality control after cerebral ischemia by increasing SIRT3 expression

Existing evidence indicates that exercise training can enhance neural function by regulating mitochondrial quality control (MQC), which can be impaired by cerebral ischemia, and that sirtuin-3 (SIRT3), a protein localized in mitochondria, is crucial in maintaining mitochondrial functions. However, the relationship among exercise training, SIRT3, and MQC after cerebral ischemia remains obscure. This study attempted to elucidate the relationship among exercise training, SIRT3 and MQC after cerebral ischemia in rats. Male adult SD rats received tMCAO after the transfection of adeno-associated virus encoding either sirtuin-3 (AAV-SIRT3) or SIRT3 knockdown (AAV-sh-SIRT3) into the ipsilateral striata and cortex. Subsequently, the animals were randomly selected for exercise training. The index changes were measured by transmission electron microscopy, Western blot analysis, nuclear magnetic resonance imaging, TUNEL staining, and immunofluorescence staining, etc. The results revealed that after cerebral ischemia, exercise training increased SIRT3 expression, significantly improved neural function, alleviated infarct volume and neuronal apoptosis, maintained the mitochondrial structural integrity, and re-established MQC. The latter promoted mitochondrial biogenesis, balanced mitochondrial fission/fusion, and enhanced mitophagy. These favorable benefits were reversed after SIRT3 interference. In addition, a cellular OGD/R model showed that the increased SIRT3 expression alleviates neuronal apoptosis and re-establishes mitochondrial quality control by activating the β-catenin pathway. These findings suggest that exercise training may optimize mitochondrial quality control by increasing the expression of SIRT3, thereby improving neural functions after cerebral ischemia, which illuminates the mechanism underlying the exercise training-conferred neural benefits and indicates SIRT3 as a therapeutic strategy for brain ischemia.

Potential application of natural compounds in ischaemic stroke: Focusing on the mechanisms underlying "lysosomocentric" dysfunction of the autophagy-lysosomal pathway

Ischaemic stroke (IS) is the second leading cause of death and a major cause of disability worldwide. Currently, the clinical management of IS still depends on restoring blood flow via pharmacological thrombolysis or mechanical thrombectomy, with accompanying disadvantages of narrow therapeutic time window and risk of haemorrhagic transformation. Thus, novel pathophysiological mechanisms and targeted therapeutic candidates are urgently needed. The autophagy-lysosomal pathway (ALP), as a dynamic cellular lysosome-based degradative process, has been comprehensively studied in recent decades, including its upstream regulatory mechanisms and its role in mediating neuronal fate after IS. Importantly, increasing evidence has shown that IS can lead to lysosomal dysfunction, such as lysosomal membrane permeabilization, impaired lysosomal acidity, lysosomal storage disorder, and dysfunctional lysosomal ion homeostasis, which are involved in the IS-mediated defects in ALP function. There is tightly regulated crosstalk between transcription factor EB (TFEB), mammalian target of rapamycin (mTOR) and lysosomal function, but their relationship remains to be systematically summarized. Notably, a growing body of evidence emphasizes the benefits of naturally derived compounds in the treatment of IS via modulation of ALP function. However, little is known about the roles of natural compounds as modulators of lysosomes in the treatment of IS. Therefore, in this context, we provide an overview of the current understanding of the mechanisms underlying IS-mediated ALP dysfunction, from a lysosomal perspective. We also provide an update on the effect of natural compounds on IS, according to their chemical structural types, in different experimental stroke models, cerebral regions and cell types, with a primary focus on lysosomes and autophagy initiation. This review aims to highlight the therapeutic potential of natural compounds that target lysosomal and ALP function for IS treatment.

Inhibition of the AP-1/TFPI2 axis contributes to alleviating cerebral ischemia/reperfusion injury by improving blood-brain barrier integrity

Reperfusion after cerebral ischemia leads to secondary damage to the nervous system, called cerebral ischemia/reperfusion injury (CIRI). The blood-brain barrier (BBB) consists of endothelial cells and tight junction (TJ) proteins, and its disruption aggravates CIRI. Two GSE datasets identified Tissue Factor Pathway Inhibitor 2 (TFPI2) as a differentially upregulated gene (Log2FC > 1, p < 0.01) in the cerebral cortex of ischemic rats, and TFPI2 affects angiogenesis of endothelial cells. Moreover, genes (c-Jun, c-Fos, FosL1) encoding subunits of Activator Protein-1 (AP-1), a transcription factor involved in IRI, were highly expressed in ischemic samples. Thus, the effects of the AP-1/TFPI2 axis on CIRI were explored. We determined increased TFPI2 expression in the cerebral cortex of rats receiving middle cerebral artery occlusion (MCAO) for 90 min and reperfusion (R) for 48 h. Then AAV2-shTFPI2 particles (5 × 1010 vg) were injected into the right lateral ventricle of rats 3 weeks before MCAO/R. TFPI2 knockdown decreased infarct size and neuronal injury in ischemic rats. It improved BBB integrity, demonstrated by reduced FITC-dextran leakage in brain tissues of MCAO/R-operated rats. Furthermore, it increased the expression of TJ proteins (Occludin, Claudin-5, TJP-1) in the cerebral cortex of rats with CIRI. Consistently, we found that TFPI2 knockdown mitigated cell damage in mouse endothelial bEND.3 cells with oxygen and glucose deprivation (ODG) for 6 h and reoxygenation (R) for 18 h (OGD/R) treatment. High co-expression of c-Jun and c-Fos significantly elevated TFPI2 promoter activity. c-Jun knockdown inhibited TFPI2 expression in OGD/R-treated bEND.3 cell. Collectively, our findings demonstrate that inhibition of the AP-1/TFPI2 axis alleviates CIRI.

Isoliquiritigenin alleviates cerebral ischemia-reperfusion injury by reducing oxidative stress and ameliorating mitochondrial dysfunction via activating the Nrf2 pathway

Cerebral ischemia-reperfusion injury (CIRI) refers to a secondary brain injury that occurs when blood supply is restored to ischemic brain tissue and is one of the leading causes of adult disability and mortality. Multiple pathological mechanisms are involved in the progression of CIRI, including neuronal oxidative stress and mitochondrial dysfunction. Isoliquiritigenin (ISL) has been preliminarily reported to have potential neuroprotective effects on rats subjected to cerebral ischemic insult. However, the protective mechanisms of ISL have not been elucidated. This study aims to further investigate the effects of ISL-mediated neuroprotection and elucidate the underlying molecular mechanism. The findings indicate that ISL treatment significantly alleviated middle cerebral artery occlusion (MCAO)-induced cerebral infarction, neurological deficits, histopathological damage, and neuronal apoptosis in mice. In vitro, ISL effectively mitigated the reduction of cell viability, Na+-K+-ATPase, and MnSOD activities, as well as the degree of DNA damage induced by oxygen-glucose deprivation (OGD) injury in PC12 cells. Mechanistic studies revealed that administration of ISL evidently improved redox homeostasis and restored mitochondrial function via inhibiting oxidative stress injury and ameliorating mitochondrial biogenesis, mitochondrial fusion-fission balance, and mitophagy. Moreover, ISL facilitated the dissociation of Keap1/Nrf2, enhanced the nuclear transfer of Nrf2, and promoted the binding activity of Nrf2 with ARE. Finally, ISL obviously inhibited neuronal apoptosis by activating the Nrf2 pathway and ameliorating mitochondrial dysfunction in mice. Nevertheless, Nrf2 inhibitor brusatol reversed the mitochondrial protective properties and anti-apoptotic effects of ISL both in vivo and in vitro. Overall, our findings revealed that ISL exhibited a profound neuroprotective effect on mice following CIRI insult by reducing oxidative stress and ameliorating mitochondrial dysfunction, which was closely related to the activation of the Nrf2 pathway.

Novel therapeutic targets for reperfusion injury in ischemic stroke: Understanding the role of mitochondria, excitotoxicity and ferroptosis

Ischemic reperfusion injury (IRI) remains a significant challenge in various clinical settings, including stroke. Despite advances in reperfusion strategies, the restoration of blood flow to ischemic tissues often exacerbates tissue damage through a complex cascade of cellular and molecular events. In recent years, there has been growing interest in identifying novel therapeutic targets to ameliorate the detrimental effects of IRI and improve patient outcomes. This review critically evaluates emerging therapeutic targets and strategies for IRI management, such as R-spondin 3, neurolysin, glial cell gene therapy and inter alpha inhibitors. Diverse pathophysiology involved in IRI stroke such as oxidative stress, inflammation, mitochondrial dysfunction, and ferroptosis are also closely discussed. Additionally, we explored the intricate interplay between inflammation and IRI, focusing on cell-mediated gene therapy approaches and anti-inflammatory agents that hold promise for attenuating tissue damage. Moreover, we delve into novel strategies aimed at preserving endothelial function, promoting tissue repair, and enhancing cellular resilience to ischemic insults. Finally, we discuss challenges, future directions, and translational opportunities for the development of effective therapies targeting ischemic reperfusion injury.

Impact of acupuncture on ischemia/reperfusion injury: Unraveling the role of miR-34c-5p and autophagy activation

We have previously reported that the expression of miR-34c-5p was up-regulated during acupuncture treatment in the setting of a cerebral ischemia/reperfusion injury (CIRI), indicating that miR-34c-5p plays an important role in healing from a CIRI-induced brain injury. This study sought to evaluate the effects of acupuncture on miR-34c-5p expression and autophagy in the forward and reverse directions using a rat focal cerebral ischemia/reperfusion model. After 120 minutes of middle cerebral artery occlusion and reperfusion, rats were treated with acupuncture at the "Dazhui" (DU20), "Baihui" (DU26) and "Renzhong" (DU14) points. Neurologic function deficit score, cerebral infarct area ratio, neuronal apoptosis and miR-34c-5p expression were evaluated 72 hr after treatment. The autophagy agonist RAPA and the antagonist 3MA were used to evaluate the neuro protective effects of autophagy-mediated acupuncture. We found that acupuncture treatment improved autophagy in the brain tissue of CIRI rats. Acupuncture reversed the negative effects of 3MA on CIRI, and acupuncture combined with RAPA further enhanced autophagy. We also found that acupuncture could increase miR-34c-5p expression in hippocampal neurons after ischemia/reperfusion. Acupuncture and a miR-34c agomir were able to enhance autophagy, improve neurologic deficits, and reduce the cerebral infarct area ratio and apoptosis rate by promoting the expression of miR-34c-5p. Silencing miR-34c resulted in a significantly reduced activating effect of acupuncture on autophagy and increased apoptosis, neurologic deficit symptoms, and cerebral infarct area ratio. This confirms that acupuncture can upregulate miR-34c-5p expression, which is beneficial in the treatment of CIRI.

A quinolinyl resveratrol derivative alleviates acute ischemic stroke injury by promoting mitophagy for neuroprotection via targeting CK2α'

Ischemic stroke (IS) is a serious threat to human health. The naturally derived small molecule (E)-5-(2-(quinolin-4-yl) ethenyl) benzene-1,3-diol (RV01) is a quinolinyl analog of resveratrol with great potential in the treatment of IS. The aim of this study was to investigate the potential mechanisms and targets for the protective effect of the RV01 on IS. The mouse middle cerebral artery occlusion and reperfusion (MCAO/R) and oxygen-glucose deprivation and reperfusion (OGD/R) models were employed to evaluate the effects of RV01 on ischemic injury and neuroprotection. RV01 was found to significantly increase the survival of SH-SY5Y cells and prevent OGD/R-induced apoptosis in SH-SY5Y cells. Furthermore, RV01 reduced oxidative stress and mitochondrial damage by promoting mitophagy in OGD/R-exposed SH-SY5Y cells. Knockdown of CK2α' abolished the RV01-mediated promotion on mitophagy and alleviation on mitochondrial damage as well as neuronal injury after OGD/R. These results were further confirmed by molecular docking, drug affinity responsive target stability and cellular thermal shift assay analysis. Importantly, in vivo study showed that treatment with the CK2α' inhibitor CX-4945 abolished the RV01-mediated alleviation of cerebral infarct volume, brain edema, cerebral blood flow and neurological deficit in MCAO/R mice. These data suggest that RV01 effectively reduces damage caused by acute ischemic stroke by promoting mitophagy through its interaction with CK2α'. These findings offer valuable insights into the underlying mechanisms through which RV01 exerts its therapeutic effects on IS.

The potential roles of PKM2 in cerebrovascular diseases

Pyruvate kinase M2 (PKM2), a key enzyme involved in glycolysis,plays an important role in regulating cell metabolism and growth under different physiological conditions. PKM2 has been intensively investigated in multiple cancer diseases. Recent years, many studies have found its pivotal role in cerebrovascular diseases (CeVDs), the disturbances in intracranial blood circulation. CeVDs has been confirmed to be closely associated with oxidative stress (OS), mitochondrial dynamics, systemic inflammation, and local neuroinflammation in the brain. It has further been revealed that PKM2 exerts various biological functions in the regulation of energy supply, OS, inflammatory responses, and mitochondrial dysfunction. The roles of PKM2 are closely related to its different isoforms, expression levels in subcellular localization, and post-translational modifications. Therefore, summarizing the roles of PKM2 in CeVDs will help further understanding the molecular mechanisms of CeVDs. In this review, we illustrate the characteristics of PKM2, the regulated PKM2 expression, and the biological roles of PKM2 in CeVDs.

THSG alleviates cerebral ischemia/reperfusion injury via the GluN2B-CaMKII-ERK1/2 pathway

BACKGROUND

The potential therapeutic targeting of PINK1-PARK2-mediated mitophagy against cerebral ischemia/reperfusion (CI/R) injury involves the pathophysiological processes of neurovascular unit (NVU) and is closely associated with N-methyl-D-aspartate receptors (NMDARs) commonly expressed in NVU. 2,3,5,4'-Tetrahydroxy-stilbene-2-O-β-D-glucoside (THSG), a compound derived from the traditional Chinese medicine Polygonum multiflorum Thunb., has demonstrated notable neuroprotective properties against CI/R injury. However, it remains unclear whether THSG exerts its protective effects through GluN2B related PINK1/ PARK2 pathway.

PURPOSE

This study aims to explore the pharmacological effects of THSG on alleviating CI/R injury via the GluN2B-CaMKII-ERK1/2 pathway.

METHODS

THSG neuroprotection against CI/R injury was studied in transient middle cerebral artery occlusion/reversion (tMCAO/R) model rats and in oxygen and glucose deprivation/ reoxygenation (OGD/R) induced neurons. PINK1-PARK2-mediated mitophagy involvement in the protective effect of THSG was investigated in tMCAO/R rats and OGD/R-induced neurons via THSG and 3-methyladenine (3-MA) treatment. Furthermore, the beneficial role of GluN2B in reperfusion and its contribution to the THSG effect via CaMKII-ERK1/2 and PINK1-PARK2-mediated mitophagy was explored using the GluN2B-selective antagonist Ro 25-6981 both in vivo and in vitro. Finally, the interaction between THSG and GluN2B was evaluated using molecular docking.

RESULTS

THSG significantly reduced infarct volume, neurological deficits, penumbral neuron structure, and functional damage, upregulated the inhibitory apoptotic marker Bcl-2, and suppressed the increase of pro-apoptotic proteins including cleaved caspase-3 and Bax in tMCAO/R rats. THSG (1 μM) markedly improved the neuronal survival under OGD/R conditions. Furthermore, THSG promoted PINK1 and PARK2 expression and increased mitophagosome numbers and LC3-II-LC3-I ratio both in vivo and in vitro. The effects of THSG were considerably abrogated by the mitophagy inhibitor 3-MA in OGD/R-induced neurons. Inhibiting GluN2B profoundly decreased mitophagosome numbers and OGD/R-induced neuronal viability. Specifically, inhibiting GluN2B abolished the protection of THSG against CI/R injury and reversed the upregulation of PINK1-PARK2-mediated mitophagy by THSG. Inhibiting GluN2B eliminated THSG upregulation of ERK1/2 and CaMKII phosphorylation. The molecular docking analysis results demonstrated that THSG bound to GluN2B (binding energy: -5.2 ± 0.11 kcal/mol).

CONCLUSIONS

This study validates the premise that THSG alleviates CI/R injury by promoting GluN2B expression, activating CaMKII and ERK1/2, and subsequently enhancing PINK1-PARK2-mediated mitophagy. This work enlightens the potential of THSG as a promising candidate for novel therapeutic strategies for treating ischemic stroke.

Regulated cell death in hypoxic-ischaemic encephalopathy: recent development and mechanistic overview

Hypoxic-ischaemic encephalopathy (HIE) in termed infants remains a significant cause of morbidity and mortality worldwide despite the introduction of therapeutic hypothermia. Depending on the cell type, cellular context, metabolic predisposition and insult severity, cell death in the injured immature brain can be highly heterogenous. A continuum of cell death exists in the H/I-injured immature brain. Aside from apoptosis, emerging evidence supports the pathological activation of necroptosis, pyroptosis and ferroptosis as alternative regulated cell death (RCD) in HIE to trigger neuroinflammation and metabolic disturbances in addition to cell loss. Upregulation of autophagy and mitophagy in HIE represents an intrinsic neuroprotective strategy. Molecular crosstalk between RCD pathways implies one RCD mechanism may compensate for the loss of function of another. Moreover, mitochondrion was identified as the signalling "hub" where different RCD pathways converge. The highly-orchestrated nature of RCD makes them promising therapeutic targets. Better understanding of RCD mechanisms and crosstalk between RCD subtypes likely shed light on novel therapy development for HIE. The identification of a potential RCD converging node may open up the opportunity for simultaneous and synergistic inhibition of cell death in the immature brain.

Delayed Chronic Acidic Postconditioning Improves Poststroke Motor Functional Recovery and Brain Tissue Repair by Activating Proton-Sensing TDAG8

Acidic postconditioning by transient CO2 inhalation applied within minutes after reperfusion has neuroprotective effects in the acute phase of stroke. However, the effects of delayed chronic acidic postconditioning (DCAPC) initiated during the subacute phase of stroke or other acute brain injuries are unknown. Mice received daily DCAPC by inhaling 5%/10%/20% CO2 for various durations (three cycles of 10- or 20-min CO2 inhalation/10-min break) at days 3-7, 7-21, or 3-21 after photothrombotic stroke. Grid-walk, cylinder, and gait tests were used to assess motor function. DCAPC with all CO2 concentrations significantly promoted motor functional recovery, even when DCAPC was delayed for 3-7 days. DCAPC enhanced the puncta density of GAP-43 (a marker of axon growth and regeneration) and synaptophysin (a marker of synaptogenesis) and reduced the amoeboid microglia number, glial scar thickness and mRNA expression of CD16 and CD32 (markers of proinflammatory M1 microglia) compared with those of the stroke group. Cerebral blood flow (CBF) increased in response to DCAPC. Furthermore, the mRNA expression of TDAG8 (a proton-activated G-protein-coupled receptor) was increased during the subacute phase of stroke, while DCAPC effects were blocked by systemic knockout of TDAG8, except for those on CBF. DCAPC reproduced the benefits by re-expressing TDAG8 in the peri-infarct cortex of TDAG8-/- mice infected with HBAAV2/9-CMV-TDAG8-3flag-ZsGreen. Taken together, we first showed that DCAPC promoted functional recovery and brain tissue repair after stroke with a wide therapeutic time window of at least 7 days after stroke. Brain-derived TDAG8 is a direct target of DCAPC that induces neuroreparative effects.

Molecular network mechanism in cerebral ischemia-reperfusion rats treated with human urine stem cells

Objective

To explore the effect of human urine-derived stem cells (husc) in improving the neurological function of rats with cerebral ischemia-reperfusion (CIR), and report new molecular network by bioinformatics, combined with experiment validation.

Methods

After CIR model was established, and husc were transplanted into the lateral ventricle of rats，neurological severe score (NSS) andgene network analysis were performed. Firstly, we input the keywords "Cerebral reperfusion" and "human urine stem cells" into Genecard database and merged data with findings from PubMed so as to get their targets genes, and downloaded them to make Venny intersection plot. Then, Gene ontology (GO) analysis, kyoto encyclopedia of genes and genomes (KEGG) pathway analysis and protein-protein interaction (PPI) were performed to construct molecular network of core genes. Lastly, the expressional level of core genes was validated via quantitative real-time polymerase chain reaction (qRT-PCR), and localized by immunofluorescence.

Results

Compared with the Sham group, the neurological function of CIR rats was significantly improved after the injection of husc into the lateral ventricle; at 14 days, P = 0.028, which was statistically significant. There were 258 overlapping genes between CIR and husc, and integrated with 252 genes screened from PubMed and CNKI. GO enrichment analysis were mainly involved neutrophil degranulation, neutrophil activation in immune response and platelet positive regulation of degranulation, Hemostasis, blood coagulation, coagulation, etc. KEGG pathway analysis was mainly involved in complement and coagulation cascades, ECM-receptor. Hub genes screened by Cytoscape consist ofCD44, ACTB, FN1, ITGB1, PLG, CASP3, ALB, HSP90AA1, EGF, GAPDH. Lastly, qRT-PCR results showed statistic significance (P < 0.05) in ALB, CD44 and EGF before and after treatment, and EGF immunostaining was localized in neuron of cortex.

Conclusion

husc transplantation showed a positive effect in improving neural function of CIR rats, and underlying mechanism is involved in CD44, ALB, and EGF network.

Huang-Lian-Jie-Du decoction drug-containing serum inhibits IL-1β secretion from D-glucose and PA induced BV2 cells via autophagy/NLRP3 signaling

ETHNOPHARMACOLOGICAL RELEVANCE

Huang-Lian-Jie-Du decoction (HLJDD), a famous traditional Chinese medicine prescription with heat-clearing and detoxifying effects, has been widely used to treat diabetes, dementia, stroke, and other diseases. However, the detailed mechanisms of HLJDD against type 2 diabetes associated cognitive dysfunction (DACD) through inhibiting interleukin-1β (IL-1β) mediated neuroinflammation remain to be further elucidated.

AIM OF THE STUDY

The aim of this study was to investigate the effect and potential mechanism of HLJDD on IL-1β secretion in a DACD model of BV2 cells induced by D-glucose and palmitic acid (PA).

MATERIALS AND METHOD

sUltra-performance liquid chromatography-quadrupole/electrostatic field orbital well high-resolution mass spectrometry technology was used to analyze the compounds in HLJDD drug-containing serum. The cytotoxicity was detected by cell counting kit-8. Enzyme-linked immunosorbent assay was used to measure the secretion of IL-1β in BV2 cells. Reactive oxygen species, glutathione, superoxide dismutase, and malondialdehyde kits were used to detect the intracellular oxidative stress levels. The autophagy level was determined by autophagy staining kit and transmission electron microscope. The expression levels of autophagy-related 7 (Atg7), P62, LC3, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3(NLRP3), Caspase1, and IL-1β were detected by real-time PCR, immunofluorescence, and western blotting. The Atg7siRNA was transfected into BV2 cells to produce autophagy inhibitory effect. Then the effect of HLJDD drug-containing serum on IL-1β secretion in D-glucose and PA induced BV2 cells and the potential mechanism of autophagy-NLRP3 inflammasome activation were further observed.

RESULTS

Eighty-eight compounds were preliminarily identified in HLJDD drug-containing serum, among which geniposide, baicalin, palmatine, berberine, wogonoside, wogonin, and geniposidic acid were identified as the main prototype components of HLJDD into the blood. In this study, the DACD model of BV2 cells induced by high concentrations of glucose and PA was successfully constructed. HLJDD drug-containing serum significantly reduced the secretion of IL-1β and the activity of NLRP3 inflammasome with improving the oxidative stress level. Interestingly, the enhanced autophagy level was also found. After transfection of Atg7siRNA into BV2 cells, the effect of HLJDD drug-containing serum on autophagy promotion was reversed, but the inhibitory effects on IL-1β secretion, NLRP3 inflammasome activation, and oxidative stress were reduced.

CONCLUSIONS

These results indicated that the inhibition of HLJDD drug-containing serum on the IL-1β secretion in D-glucose and PA induced BV2 cells was related to autophagy promotion, the decreased NLRP3 inflammasome activation, and the improved oxidative stress. Moreover, the improvement of HLJDD drug-containing serum on IL-1β secretion, NLRP3 inflammasome activation, and oxidative stress were all closely associated with Atg7 mediated autophagy promotion. Geniposide, baicalin, palmatine, berberine, wogonoside, wogonin, and geniposidic acid may be the potential active ingredients of HLJDD drug-containing serum.

The Multiple Roles of Autophagy in Neural Function and Diseases

Autophagy involves the sequestration and delivery of cytoplasmic materials to lysosomes, where proteins, lipids, and organelles are degraded and recycled. According to the way the cytoplasmic components are engulfed, autophagy can be divided into macroautophagy, microautophagy, and chaperone-mediated autophagy. Recently, many studies have found that autophagy plays an important role in neurological diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, neuronal excitotoxicity, and cerebral ischemia. Autophagy maintains cell homeostasis in the nervous system via degradation of misfolded proteins, elimination of damaged organelles, and regulation of apoptosis and inflammation. AMPK-mTOR, Beclin 1, TP53, endoplasmic reticulum stress, and other signal pathways are involved in the regulation of autophagy and can be used as potential therapeutic targets for neurological diseases. Here, we discuss the role, functions, and signal pathways of autophagy in neurological diseases, which will shed light on the pathogenic mechanisms of neurological diseases and suggest novel targets for therapies.

Shared Proteins and Pathways of Cardiovascular and Cognitive Diseases: Relation to Vascular Cognitive Impairment

One of the primary goals of systems medicine is the detection of putative proteins and pathways involved in disease progression and pathological phenotypes. Vascular cognitive impairment (VCI) is a heterogeneous condition manifesting as cognitive impairment resulting from vascular factors. The precise mechanisms underlying this relationship remain unclear, which poses challenges for experimental research. Here, we applied computational approaches like systems biology to unveil and select relevant proteins and pathways related to VCI by studying the crosstalk between cardiovascular and cognitive diseases. In addition, we specifically included signals related to oxidative stress, a common etiologic factor tightly linked to aging, a major determinant of VCI. Our results show that pathways associated with oxidative stress are quite relevant, as most of the prioritized vascular cognitive genes and proteins were enriched in these pathways. Our analysis provided a short list of proteins that could be contributing to VCI: DOLK, TSC1, ATP1A1, MAPK14, YWHAZ, CREB3, HSPB1, PRDX6, and LMNA. Moreover, our experimental results suggest a high implication of glycative stress, generating oxidative processes and post-translational protein modifications through advanced glycation end-products (AGEs). We propose that these products interact with their specific receptors (RAGE) and Notch signaling to contribute to the etiology of VCI.

Nomogram to predict 6-month mortality in acute ischemic stroke patients treated with endovascular treatment

Background

Acute Ischemic Stroke (AIS) presents significant challenges in evaluating the effectiveness of Endovascular Treatment (EVT). This study develops a novel prognostic model to predict 6-month mortality post-EVT, aiding in identifying patients likely to benefit less from this intervention, thus enhancing therapeutic decision-making.

Methods

We employed a cohort of AIS patients from Shenyang First People's Hospital, serving as the Validation set, to develop our model. LASSO regression was used for feature selection, followed by logistic regression to create a prognostic nomogram for predicting 6-month mortality post-EVT. The model's performance was validated using a dataset from PLA Northern Theater Command General Hospital, assessing discriminative ability (C-index), calibration (calibration plot), and clinical utility (decision curve analysis). Statistical significance was set at p < 0.05.

Results

The development cohort consisted of 219 patients. Six key predictors of 6-month mortality were identified: "Lack of Exercise" (OR, 4.792; 95% CI, 1.731-13.269), "Initial TICI Score 1" (OR, 1.334; 95% CI, 0.628-2.836), "MRS Score 5" (OR, 1.688; 95% CI, 0.754-3.78), "Neutrophil Percentage" (OR, 1.08; 95% CI, 1.042-1.121), "Onset Blood Sugar" (OR, 1.119; 95% CI, 1.007-1.245), and "Onset NIHSS Score" (OR, 1.074; 95% CI, 1.029-1.121). The nomogram demonstrated a high predictive capability with a C-index of 0.872 (95% CI, 0.830-0.911) in the development set and 0.830 (95% CI, 0.726-0.920) in the validation set.

Conclusion

Our nomogram, incorporating factors such as Lack of Exercise, Initial TICI Score 1, MRS Score 5, Neutrophil Percentage, Onset Blood Sugar, and Onset NIHSS Score, provides a valuable tool for predicting 6-month mortality in AIS patients post-EVT. It offers potential to refine early clinical decision-making and optimize patient outcomes, reflecting a shift toward more individualized patient care.

Delayed CO2 postconditioning promotes neurological recovery after cryogenic traumatic brain injury by downregulating IRF7 expression

AIMS

Few treatments are available in the subacute phase of traumatic brain injury (TBI) except rehabilitation training. We previously reported that transient CO2 inhalation applied within minutes after reperfusion has neuroprotective effects against cerebral ischemia/reperfusion injury. In this study, it was hypothesized that delayed CO2 postconditioning (DCPC) starting at the subacute phase may promote neurological recovery of TBI.

METHODS

Using a cryogenic TBI (cTBI) model, mice received DCPC daily by inhaling 5%/10%/20% CO2 for various time-courses (one/two/three cycles of 10-min inhalation/10-min break) at Days 3-7, 3-14 or 7-18 after cTBI. Beam walking and gait tests were used to assess the effect of DCPC. Lesion size, expression of GAP-43 and synaptophysin, amoeboid microglia number and glia scar area were detected. Transcriptome and recombinant interferon regulatory factor 7 (Irf7) adeno-associated virus were applied to investigate the molecular mechanisms.

RESULTS

DCPC significantly promoted recovery of motor function in a concentration and time-course dependent manner with a wide therapeutic time window of at least 7 days after cTBI. The beneficial effects of DCPC were blocked by intracerebroventricular injection of NaHCO3 . DCPC also increased puncta density of GAP-43 and synaptophysin, and reduced amoeboid microglia number and glial scar formation in the cortex surrounding the lesion. Transcriptome analysis showed many inflammation-related genes and pathways were altered by DCPC, and Irf7 was a hub gene, while overexpression of IRF7 blocked the motor function improvement of DCPC.

CONCLUSIONS

We first showed that DCPC promoted functional recovery and brain tissue repair, which opens a new therapeutic time window of postconditioning for TBI. Inhibition of IRF7 is a key molecular mechanism for the beneficial effects of DCPC, and IRF7 may be a potential therapeutic target for rehabilitation after TBI.

Contribution and therapeutic value of mitophagy in cerebral ischemia-reperfusion injury after cardiac arrest

Cardiopulmonary resuscitation and related life support technologies have improved substantially in recent years; however, mortality and disability rates from cardiac arrest (CA) remain high and are closely associated with the high incidence of cerebral ischemia-reperfusion injury (CIRI), which is explained by a "double-hit" model (i.e., resulting from both ischemia and reperfusion). Mitochondria are important power plants in the cell and participate in various biochemical processes, such as cell differentiation and signaling in eukaryotes. Various mitochondrial processes, including energy metabolism, calcium homeostasis, free radical production, and apoptosis, are involved in several important stages of the progression and development of CIRI. Mitophagy is a key mechanism of the endogenous removal of damaged mitochondria to maintain organelle function and is a critical target for CIRI treatment after CA. Mitophagy also plays an essential role in attenuating ischemia-reperfusion in other organs, particularly during post-cardiac arrest myocardial dysfunction. Regulation of mitophagy may influence necroptosis (a programmed cell death pathway), which is the main endpoint of organ ischemia-reperfusion injury. In this review, we summarize the main signaling pathways related to mitophagy and their associated regulatory proteins. New therapeutic methods and drugs targeting mitophagy in ischemia-reperfusion animal models are also discussed. In-depth studies of the mechanisms underlying the regulation of mitophagy will enhance our understanding of the damage and repair processes in CIRI after CA, thereby contributing to the development of new therapeutic strategies.

Synthetic Adrenocorticotropic Peptides Modulate the Expression Pattern of Immune Genes in Rat Brain following the Early Post-Stroke Period

Ischemic stroke is an acute local decrease in cerebral blood flow due to a thrombus or embolus. Of particular importance is the study of the genetic systems that determine the mechanisms underlying the formation and maintenance of a therapeutic window (a time interval of up to 6 h after a stroke) when effective treatment can be provided. Here, we used a transient middle cerebral artery occlusion (tMCAO) model in rats to study two synthetic derivatives of adrenocorticotropic hormone (ACTH). The first was ACTH(4-7)PGP, which is known as Semax. It is actively used as a neuroprotective drug. The second was the ACTH(6-9)PGP peptide, which is elucidated as a prospective agent only. Using RNA-Seq analysis, we revealed hundreds of ischemia-related differentially expressed genes (DEGs), as well as 131 and 322 DEGs related to the first and second peptide at 4.5 h after tMCAO, respectively, in dorsolateral areas of the frontal cortex of rats. Furthermore, we showed that both Semax and ACTH(6-9)PGP can partially prevent changes in the immune- and neurosignaling-related gene expression profiles disturbed by the action of ischemia at 4.5 h after tMCAO. However, their different actions with regard to predominantly immune-related genes were also revealed. This study gives insight into how the transcriptome depends on the variation in the structure of the related peptides, and it is valuable from the standpoint of the development of measures for early post-stroke therapy.

Targeting neuronal mitophagy in ischemic stroke: an update

Cerebral ischemia is a neurological disorder associated with complex pathological mechanisms, including autophagic degradation of neuronal mitochondria, or termed mitophagy, following ischemic events. Despite being well-documented, the cellular and molecular mechanisms underlying the regulation of neuronal mitophagy remain unknown. So far, the evidence suggests neuronal autophagy and mitophagy are separately regulated in ischemic neurons, the latter being more likely activated by reperfusional injury. Specifically, given the polarized morphology of neurons, mitophagy is regulated by different neuronal compartments, with axonal mitochondria being degraded by autophagy in the cell body following ischemia-reperfusion insult. A variety of molecules have been associated with neuronal adaptation to ischemia, including PTEN-induced kinase 1, Parkin, BCL2 and adenovirus E1B 19-kDa-interacting protein 3 (Bnip3), Bnip3-like (Bnip3l) and FUN14 domain-containing 1. Moreover, it is still controversial whether mitophagy protects against or instead aggravates ischemic brain injury. Here, we review recent studies on this topic and provide an updated overview of the role and regulation of mitophagy during ischemic events.

N1-Methyladenosine modification of mRNA regulates neuronal gene expression and oxygen glucose deprivation/reoxygenation induction

N¹-Methyladenosine (m1A) is an abundant modification of transcripts, plays important roles in regulating mRNA structure and translation efficiency, and is dynamically regulated under stress. However, the characteristics and functions of mRNA m1A modification in primary neurons and oxygen glucose deprivation/reoxygenation (OGD/R) induced remain unclear. We first constructed a mouse cortical neuron OGD/R model and then used methylated RNA immunoprecipitation (MeRIP) and sequencing technology to demonstrate that m1A modification is abundant in neuron mRNAs and dynamically regulated during OGD/R induction. Our study suggests that Trmt10c, Alkbh3, and Ythdf3 may be m1A-regulating enzymes in neurons during OGD/R induction. The level and pattern of m1A modification change significantly during OGD/R induction, and differential methylation is closely associated with the nervous system. Our findings show that m1A peaks in cortical neurons aggregate at both the 5' and 3' untranslated regions. m1A modification can regulate gene expression, and peaks in different regions have different effects on gene expression. By analysing m1A-seq and RNA-seq data, we show a positive correlation between differentially methylated m1A peaks and gene expression. The correlation was verified by using qRT-PCR and MeRIP-RT-PCR. Moreover, we selected human tissue samples from Parkinson's disease (PD) and Alzheimer's disease (AD) patients from the Gene Expression Comprehensive (GEO) database to analyse the selected differentially expressed genes (DEGs) and differential methylation modification regulatory enzymes, respectively, and found similar differential expression results. We highlight the potential relationship between m1A modification and neuronal apoptosis following OGD/R induction. Furthermore, by mapping mouse cortical neurons and OGD/R-induced modification characteristics, we reveal the important role of m1A modification in OGD/R and gene expression regulation, providing new ideas for research on neurological damage.

Oridonin ameliorates caspase-9-mediated brain neuronal apoptosis in mouse with ischemic stroke by inhibiting RIPK3-mediated mitophagy

Neuronal loss is a primary factor in determining the outcome of ischemic stroke. Oridonin (Ori), a natural diterpenoid compound extracted from the Chinese herb Rabdosia rubescens, has been shown to exert anti-inflammatory and neuroregulatory effects in various models of neurological diseases. In this study we investigated whether Ori exerted a protective effect against reperfusion injury-induced neuronal loss and the underlying mechanisms. Mice were subjected to transient middle cerebral artery occlusion (tMCAO), and were injected with Ori (5, 10, 20 mg/kg, i.p.) at the beginning of reperfusion. We showed that Ori treatment rescued neuronal loss in a dose-dependent manner by specifically inhibiting caspase-9-mediated neuronal apoptosis and exerted neuroprotective effects against reperfusion injury. Furthermore, we found that Ori treatment reversed neuronal mitochondrial damage and loss after reperfusion injury. In N2a cells and primary neurons, Ori (1, 3, 6 μM) exerted similar protective effects against oxygen-glucose deprivation and reoxygenation (OGD/R)-induced injury. We then conducted an RNA-sequencing assay of the ipsilateral brain tissue of tMCAO mice, and identified receptor-interacting protein kinase-3 (RIPK3) as the most significantly changed apoptosis-associated gene. In N2a cells after OGD/R and in the ipsilateral brain region, we found that RIPK3 mediated excessive neuronal mitophagy by activating AMPK mitophagy signaling, which was inhibited by Ori or 3-MA. Using in vitro and in vivo RIPK3 knockdown models, we demonstrated that the anti-apoptotic and neuroprotective effects of Ori were RIPK3-dependent. Collectively, our results show that Ori effectively inhibits RIPK3-induced excessive mitophagy and thereby rescues the neuronal loss in the early stage of ischemic stroke.

Hypoxic postconditioning restores mitophagy against transient global cerebral ischemia via Parkin-induced posttranslational modification of TBK1

Hypoxic postconditioning (HPC) has been reported to enhance Parkin-catalyzed mitochondrial ubiquitination to restore mitophagy in hippocampal CA1 against transient global cerebral ischemia (tGCI). However, the molecular mechanism leading ubiquitinated mitochondria to final clearance during HPC-mediated mitophagy after tGCI is unclear. This study aims to investigate whether HPC restores mitophagy after tGCI through Parkin-induced K63-linked poly-ubiquitination (K63-Ub) to activate tumor necrosis factor associated factor family member associated nuclear factor κB activator -binding kinase 1 (TBK1) in CA1 of male rats. We found that HPC maintained TBK1 expression, promoted p62 and TBK1 phosphorylation in mitochondria, and enhanced their recruitments to mitochondria in CA1 after tGCI. However, these effects were partially abolished by TBK1 inhibitor BX795. K63-Ub of mitochondrial TBK1 was disturbed at 26 h of reperfusion after tGCI, which was reversed by HPC. The maintenance of K63-Ub of mitochondrial TBK1 induced by HPC was counteracted under Parkin knockdown with AAV-mediated Prkn small-interfering RNA, accompanied by the suppression on TBK1 activation and the reduction of mitochondrial p62 phosphorylation. This innovative study indicated that HPC maintained K63-Ub of TBK1 in a Parkin-dependent manner to promote TBK1 phosphorylation, and then phosphorylated TBK1 activated p62 to restore mitophagy, thereby alleviating neuronal damage in CA1 after tGCI.

Umbelliferone protects against cerebral ischemic injury through selective autophagy of mitochondria

Effective therapeutic treatments for ischemic stroke are limited. Previous studies suggest selective activation of mitophagy alleviates cerebral ischemic injury while excessive autophagy is detrimental. However, few compounds are available to selectively activate mitophagy without affecting autophagy flux. Here, we found that acute administration of Umbelliferone (UMB) upon reperfusion exerted neuroprotective effects against ischemic injury in mice subjected to transient middle cerebral artery occlusion (tMCAO) and suppressed oxygen-glucose deprivation reperfusion (OGD-R)-induced apoptosis in SH-SY5Y cells. Interestingly, UMB promoted the translocation of mitophagy adaptor SQSTM1 to mitochondria and further reduced the mitochondrial content as well as the expression of SQSTM1 in SHSY5Y cells after OGD-R. Importantly, both the mitochondrial loss and reduction of SQSTM1 expression after UMB incubation can be reversed by autophagy inhibitor chloroquine and wortmannin, proving the mitophagy activation by UMB. Nevertheless, UMB failed to further affect neither LC3 lipidation nor the number of autophagosomes after cerebral ischemia in vivo and in vitro. Furthermore, UMB facilitated OGD-R-induced mitophagy in a Parkin-dependent manner. Inhibition of autophagy/mitophagy either pharmaceutically or genetically abolished the neuroprotective effects of UMB. Taken all, these results suggest that UMB protects against cerebral ischemic injury, both in vivo and in vitro, via promoting mitophagy without increasing the autophagic flux. UMB might serve as a potential leading compound for selectively activating mitophagy and the treatment of ischemic stroke.

The Role of Nrf2 in Relieving Cerebral Ischemia-Reperfusion Injury

Ischemic stroke includes two related pathological damage processes: brain injury caused by primary ischemia and secondary ischemia reperfusion (I/R) injury. I/R injury has become a worldwide health problem. Unfortunately, there is still a lack of satisfactory drugs for ameliorating cerebral I/R damage. Nrf2 is a vital endogenous antioxidant protein, which combines with Keap1 to maintain a dormant state under physiological conditions. When pathological changes such as I/R occurs, Nrf2 dissociates from Keap1 and activates the expression of downstream antioxidant proteins to exert a protective effect. Recent research have shown that the activated Nrf2 not only effectively inhibits oxidative stress, but also performs the ability to repair the function of compromised mitochondria, alleviate endoplasmic reticulum stress, eliminate inflammatory response, reduce blood-brain barrier permeability, inhibit neuronal apoptosis, enhance the neural network remolding, thereby exerting significant protective effects in alleviating the injuries caused by cell oxygen-glucose deprivation, or animal cerebral I/R. However, no definite clinical application report demonstrated the efficacy of Nrf2 activators in the treatment of cerebral I/R. Therefore, further efforts are needed to elaborate the role of Nrf2 activators in the treatment of cerebral I/R. Here, we reviewed the possible mechanisms underlying its potential pharmacological benefits in alleviating cerebral I/R injury, so as to provide a theoretical basis for studying its mechanism and developing Nrf2 activators.

Dexmedetomidine (Dex) exerts protective effects on rat neuronal cells injured by cerebral ischemia/reperfusion via regulating the Sphk1/S1P signaling pathway

AIM

To investigate the influence of dexmedetomidine (Dex) on cerebral ischemia/reperfusion (I/R)-injured rat neuronal cells by regulating the Sphk1/S1P pathway.

METHODS

The rats were divided into the following groups, with 18 rats in each group categorized on the basis of random number tables: sham (Sham), I/R (I/R), Dex, Sphk1 inhibitor (PF-543), and Dex together with the Sphk1 agonist phorbol-12-myristate-13-acetate (Dex+PMA). The neurological functions of the rats were assessed by the Longa scoring system at 24 h post reperfusion. The area of brain infarction was inspected using 2,3,5-triphenyltetrazolium chloride staining, and the water content of brain tissue was determined by the dry-wet weight method. The morphology of neurons in the CA1 region of the rat hippocampus was inspected using Nissl staining, while the apoptosis of neurons in this region was detected by terminal-deoxynucleotidyl transferase mediated nick end labeling staining. The Sphk1 and S1P protein levels were determined by immunofluorescence and western blotting, respectively.

RESULTS

Compared to the I/R group, rats in the Dex, PF-543, and Dex+PMA groups had a significantly lower neurological function score, as well as lower brain water content and a decreased infarction area. Moreover, the apoptotic index of the neurons and the Sphk1 and S1P levels in the hippocampal CA1 region were significantly lower in these groups (p<0.05). PMA, an agonist of Sphk1, was able to reverse the protective effects of Dex on I/R-induced neuronal cell injury.

CONCLUSION

Dex could protect cerebral I/R-induced neuronal cell injury by suppressing the Sphk1/S1P signaling pathway.

LncRNA TUG1 compromised neuronal mitophagy in cerebral ischemia/reperfusion injury by targeting sirtuin 1

BACKGROUND

Mitophagy protects against cerebral ischemia/reperfusion (CI/R)-induced neuronal apoptosis via mitochondrial clearance. Although taurine-upregulated gene 1 (lncRNA TUG1) has been proposed to be involved in the neuronal apoptosis evoked by CI/R, its specific role in mitophagy during the progression of CI/R injury remains unknown.

METHODS

The CI/R rat model was established using middle cerebral artery occlusion/reperfusion (MCAO/R). Human neuroblastoma cell line SH-SY5Y was subjected to oxygen-glucose deprivation and reoxygenation (OGD/R). Ubiquitination assay, co-immunoprecipitation assay, RNA pull-down, and RNA immunoprecipitation were used to determine the interplay among TUG1, sirtuin 1 (SIRT1), and F-box and WD repeat domain-containing 7 (FBXW7).

RESULTS

The upregulation of the TUG1 level and downregulation of the mitophagy were observed in both MCAO/R-treated rats and OGD/R-treated cells. The administration of si-TUG1 (a siRNA directed against TUG1) potentiated mitophagy and suppressed neuronal apoptosis in OGD/R-treated cells. However, the neuroprotective effect of si-TUG1 was reversed by mitophagy inhibitor or SIRT1 knockdown in vitro. Functionally, TUG1 enhanced FBXW7-mediated SIRT1 ubiquitination by upregulating FBXW7 expression. The overexpression of FBXW7 abrogated the si-TUG1-reinforced mitophagy by decreasing SIRT1 expression, thus aggravating neuronal apoptosis in the OGD/R+si-TUG1-treated cells. In rats with MCAO/R, the interference of TUG1 clearly decreased neuronal apoptosis, lessened the infarct volume, and relieved the neurological deficits.

CONCLUSION

TUG1 knockdown promotes SIRT1-induced mitophagy by suppressing FBXW7-mediated SIRT1 degradation, thus relieving the neuronal apoptosis induced by CI/R injury. LncRNA TUG1 promotes neuronal apoptosis through inhibition of mitophagy. TUG1 decreased SIRT1 expression by promoting FBXW7-mediated SIRT1 ubiquitination. FBXW7/SIRT1 axis mediated the effect of TUG1 on OGD/R-induced neuronal apoptosis by regulating mitophagy.

Novel Caspase-1 inhibitor CZL80 improves neurological function in mice after progressive ischemic stroke within a long therapeutic time-window

Progressive ischemic stroke (PIS) is featured by progressive neurological dysfunction after ischemia. Ischemia-evoked neuroinflammation is implicated in the progressive brain injury after cerebral ischemia, while Caspase-1, an active component of inflammasome, exaggerates ischemic brain injury. Current Caspase-1 inhibitors are inadequate in safety and druggability. Here, we investigated the efficacy of CZL80, a novel Caspase-1 inhibitor, in mice with PIS. Mice and Caspase-1-/- mice were subjected to photothrombotic (PT)-induced cerebral ischemia. CZL80 (10, 30 mg·kg-1·d-1, i.p.) was administered for one week after PT onset. The transient and the progressive neurological dysfunction (as foot faults in the grid-walking task and forelimb symmetry in the cylinder task) was assessed on Day1 and Day4-7, respectively, after PT onset. Treatment with CZL80 (30 mg/kg) during Day1-7 significantly reduced the progressive, but not the transient neurological dysfunction. Furthermore, we showed that CZL80 administered on Day4-7, when the progressive neurological dysfunction occurred, produced significant beneficial effects against PIS, suggesting an extended therapeutic time-window. CZL80 administration could improve the neurological function even as late as Day43 after PT. In Caspase-1-/- mice with PIS, the beneficial effects of CZL80 were abolished. We found that Caspase-1 was upregulated during Day4-7 after PT and predominantly located in activated microglia, which was coincided with the progressive neurological deficits, and attenuated by CZL80. We showed that CZL80 administration did not reduce the infarct volume, but significantly suppressed microglia activation in the peri-infarct cortex, suggesting the involvement of microglial inflammasome in the pathology of PIS. Taken together, this study demonstrates that Caspase-1 is required for the progressive neurological dysfunction in PIS. CZL80 is a promising drug to promote the neurological recovery in PIS by inhibiting Caspase-1 within a long therapeutic time-window.

A Water-Soluble Quercetin Conjugate with Triple Targeting Exerts Neuron-Protective Effect on Cerebral Ischemia by Mitophagy Activation

The existing treatments for ischemic stroke cannot meet the clinical needs so far. Quercetin (QT) is an effective apoptosis inhibitor and antioxidant flavonoid, but its water solubility is poor and has no targeting. In this study, QT is modified with hyaluronic acid (HA) to form a water-soluble conjugate HA-QT, which can specifically bind to CD44 receptors and response to hyaluronidase. Next, a novel delivery system SS31-HA-QT is prepared by further modification with SS31, a polypeptide capable of penetrating the blood-brain barrier (BBB) and indiscriminately targeting mitochondria. Meanwhile, IR780, a near-infrared dye, is conjugated onto HA-QT and SS31-HA-QT to form diagnosis tools to trace HA-QT and SS31-HA-QT. In vitro and in vivo results shows that SS31 can four-fold increase the drug penetration into BBB without any toxicity. The highly expressed CD44 and hyaluronidase in ischemic area ensured the targeted delivery of QT to the ischemic region. Importantly, the mitochondrial targeting of damaged neurons is also achieved by SS31. Further studies confirmed that SS31-HA-QT exerted neuron-protection by activating mitophagy, and its mechanism involved Akt/mTOR related TFEB and HIF-1α activation. Hence, SS31-HA-QT shall be a promising neuroprotective drug due to its high water-solubility, superior triple-targeted neuroprotective ability, low toxicity, and high efficiency.

The construction of neurogenesis-related ceRNA network of ischemic stroke treated by oxymatrine

BACKGROUND

Known as a disease associated with high mortality, disability and a significant financial burden, ischemic stroke ranks as one of the three diseases threatening human health. Recent advances in omics technology created opportunities to uncover the mechanism in ischemic stroke occurrence and treatment. In this study, we aimed to construct the competitive endogenous RNA (ceRNA) networks of ischemic stroke treated by oxymatrine intervention.

METHOD

The middle cerebral artery occlusion (MCAO) mouse model of ischemic stroke was constructed, and oxymatrine was administered. Then RNA-Sequencing was performed and integrated analysis of mRNAs, lncRNAs and circRNAs was conducted to reveal the pharmacology of oxymatrine. Functional enrichment analysis was performed to explore the underlying mechanism of differentially expressed (DE) mRNAs. The protein-protein interaction (PPI) network of neurogenesis-related genes and long noncoding RNAs (lncRNAs)/circular RNAs (circRNAs) based ceRNA networks were constructed.

RESULTS

First, this study revealed the DE-mRNAs, DE-lncRNAs and DE-circRNAs between Oxymatrine treated group and the MCAO group. Then, the common 1231 DE-mRNAs, 32 DE-lncRNAs and 31 DE-circRNAs with opposite trends were identified. The Kyoto Encyclopedia of Genes and Genomes to identify the functional enrichment of 1231 DE-mRNAs were enriched in neurogenesis-related biological processes. Based on neurogenesis-related DE-mRNAs, the PPI network was constructed, and hub genes were identified based on centrality. Finally, both the lncRNA-based and circRNAs-based ceRNA networks were constructed.

CONCLUSION

In summary, this study identified novel coding and noncoding ischemic stroke targets of oxymatrine-treated MCAO. Most importantly, we identified lncRNAs and circRNAs candidates as potential oxymatrine targets and constructed the neurogenesis-related ceRNA networks.

Artemisinin attenuated ischemic stroke induced cell apoptosis through activation of ERK1/2/CREB/BCL-2 signaling pathway in vitro and in vivo

Ischemic stroke is characterized by the presence of both brain ischemic and reperfusion-induced injuries in the brain, leading to neuronal dysfunction and death. Artemisinin, an FDA-approved antimalarial drug, has been reported to have neuroprotective properties. However, the effect of artemisinin on ischemic stroke is not known. In the present study, we investigated the effect of artemisinin on ischemic stroke using an oxygen-glucose deprivation/reperfusion (OGD/RP) cellular model and a mouse middle cerebral artery occlusion (MCAO) animal model and examined the underlying mechanisms. The obtained results revealed that a subclinical antimalarial concentration of artemisinin increased cell viability and decreased LDH release and cell apoptosis. Artemisinin also attenuated the production of reactive oxygen species (ROS) and the loss of mitochondrial membrane potential (Δψm). Importantly, artemisinin attenuated the infarction volume and the brain water content in the MCAO animal model. Artemisinin also improved neurological and behavioural outcomes and restored grasp strength and the recovery of motor function in MCAO animals. Furthermore, artemisinin treatment significantly inhibited the molecular indices of apoptosis, oxidative stress and neuroinflammation and activated the ERK1/2/CREB/BCL-2 signaling pathway. Further validation of the involved signaling pathway by the ERK1/2 inhibitor PD98059 revealed that inhibiting the ERK1/2 signaling pathway or silencing ERK1/2 reversed the neuroprotective effects of artemisinin. These results indicate that artemisinin provides neuroprotection against ischemic stroke via the ERK1/2/CREB/BCL-2 signaling pathway. Our study suggests that artemisinin may play an important role in the prevention and treatment of stroke.

Ligustilide ameliorates hippocampal neuronal injury after cerebral ischemia reperfusion through activating PINK1/Parkin-dependent mitophagy

BACKGROUND

Mitophagy plays a critical role in cerebral ischemia/reperfusion by timely removal of dysfunctional mitochondria. In mammals, PINK1/Parkin is the most classic pathway mediating mitophagy. And the activation of PINK1/Parkin mediated mitophagy exerts neuroprotective effects during cerebral ischemia reperfusion injury (CIRI). Ligustilide (LIG) is a natural compound extracted from ligusticum chuanxiong hort and angelica sinensis (Oliv.) diels that exerts neuroprotective activity after cerebral ischemia reperfusion injury (CIRI). However, it still remains unclear whether LIG could attenuates cerebral ischemia reperfusion injury (CIRI) through regulating mitophagy mediated by PINK1/Parkin.

PURPOSE

To explore the underlying mechanism of LIG on PINK1/Parkin mediated mitophagy in the hippocampus induced by ischemia reperfusion.

METHODS

This research used the middle cerebral artery occlusion and reperfusion (MCAO/R) animal model and oxygen-glucose deprivation and reperfusion (OGD/R) as in vitro model. Neurological behavior score, 2, 3, 5-triphenyl tetrazolium chloride (TTC) staining and Hematoxylin and Eosin (HE) Staining were used to detect the neuroprotection of LIG in MCAO/R rats. Also, the levels of ROS, mitochondrial membrane potential (MMP) and activities of Na⁺-K⁺-ATPase were detected to reflect mitochondrial function. Moreover, transmission electron microscope (TEM) and fluorescence microscope were used to observe mitophagy and the western blot was performed to explore the changes in protein expression in PINK1/Parkin mediated mitophagy. Finally, exact mechanism between neuroprotection of LIG and mitophagy mediated by PINK1/Parkin was explored by cell transfection.

RESULTS

The results show that LIG improved mitochondrial functions by mitophagy enhancement in vivo and vitro to alleviate CIRI. Whereas, mitophagy enhanced by LIG under CIRI is abolished by PINK1 deficiency and midivi-1, a mitochondrial division inhibitor which has been reported to have the function of mitophagy, which could further aggravate the ischemia-induced brain damage, mitochondrial dysfunction and neuronal injury.

CONCLUSION

LIG could ameliorate the neuronal injury against ischemia stroke by promoting mitophagy via PINK1/Parkin. Targeting PINK1/Parkin mediated mitophagy with LIG treatment might be a promising therapeutic strategy for ischemia stroke.

Dengzhan Xixin injection derived from a traditional Chinese herb Erigeron breviscapus ameliorates cerebral ischemia/reperfusion injury in rats via modulation of mitophagy and mitochondrial apoptosis

ETHNOPHARMACOLOGICAL RELEVANCE

Dengzhan Xixin injection (DX), a preparation of extracts from traditional Chinese medicine Erigeron breviscapus (Vaniot) Hand.-Mazz., has been widely used in clinical treatment of cerebral ischemia sequelae in China for a long history. However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

The objective of this present study aimed to investigate the therapeutic effects of DX on cerebral ischemia/reperfusion (I/R) injury in a rat model. Meanwhile, its underlying molecular mechanisms on mitochondrial protection were further interpreted.

MATERIALS AND METHODS

The major components of DX were detected by high-performance liquid chromatography analysis. The model of cerebral I/R injury was established by middle cerebral artery occlusion (MCAO) in SD rats. We firstly performed neurobehavioral score, the regional cerebral blood flow (rCBF) assay, and TTC, HE and Nissl staining for evaluating the effects of DX on I/R injury. And then, the cortical levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD), adenosine triphosphate (ATP) and mitochondrial membrane potential (MMP) were determined by commercial kits. Whereafter, real time-PCR and transmission electron microscopy were employed to investigate the relative copy number of mitochondrial DNA (mtDNA) and neuronal ultrastructure changes, respectively. Further, the potential interactions of major components in DX with mitophagy/apoptosis-related proteins were predicted by Schrodinger molecular docking. The expression of mitophagy-related proteins LC3, p62, TOM20, PINK1 and Parkin was estimated by western blot and immunofluorescence analyses. Furthermore, TUNEL staining and western blot were used to detect the apoptotic phenomenon and the protein expression of Bax, Bcl-2, Cytochrome c (Cyto-c) and cleaved Caspase-3.

RESULTS

DX mainly contains scutellarin, 3,4-O-dicaffeoylquinic acid, 3,5-O-dicaffeoylquinic acid, 4,5-O-dicaffeoylquinic acid, caffeic acid and 5-O-caffeoylquinic acid. Compared with the model group, DX could remarkably relieve ischemia-provoked neurological deficit, rCBF deficiency and cerebral infarction. Pathological changes and neuronal loss in a MCAO model of rats were memorably ameliorated by DX administration. Meanwhile, DX reduced the surged ROS and MDA, while increased the level of SOD. Notably, DX treatment conversed the collapse of ATP and MMP, along with decreased in the relative copy number of mtDNA, contributing to the maintaining of mitochondrial ultrastructure via the increased number of autophagy lysosomes. The representative ingredients in DX had a potential bind with the active sites of mitophagy/apoptosis-related proteins. DX stimulated the protein expression of LC3, PINK1 and Parkin, while reduced the levels of p62 and TOM20. In addition, DX confined TUNEL-positive cell rate with the decreased expressions of Bax, Cyto-c and cleaved Caspase-3 as well as the increased Bcl-2 level.

CONCLUSIONS

We demonstrated that the protection of DX against brain ischemia could attribute to alleviating mitochondrial damage by upregulating mitophagy and inhibiting mitochondria-mediated apoptosis.

Dedicator of cytokinesis 2 (DOCK2) silencing protects against cerebral ischemia/reperfusion by modulating microglia polarization via the activation of the STAT6 signaling pathway

Cerebral ischemia/reperfusion is the major pathophysiological process in stroke and could lead to severe and permanent disability. The current study aimed to investigate the effects of dedicator of cytokinesis 2 (DOCK2) on cerebral ischemia/reperfusion-induced cerebral injury. We established a mouse middle cerebral artery occlusion (MCAO) model with suture-occluded method in vivo. Then, BV-2 cells were conducted to oxygen-glucose deprivation and re-oxygenation (OGD/R) in vitro. The results showed that DOCK2 was highly expressed in ischemic brain following MCAO and in BV-2 cells induced by OGD/R. DOCK2 depletion protected against MCAO-induced brain infarcts and neuron degeneration. DOCK2 downregulation improved long-term neurological function, which was assessed by the Morris water-maze test. Moreover, silencing of DOCK2 promoted M2 polarization (anti-inflammation) and repressed M1 polarization (pro-inflammation) of microglia both in vivo and in vitro. Subsequently, we found that the loss of DOCK2 upregulated the expression of p-STAT6. DOCK2 knockdown-induced microglial cell polarization towards M2 phenotype was partly abrogated by the STAT6 inhibitor AS1517499. In conclusion, DOCK2 downregulation protected against cerebral ischemia/reperfusion by modulating microglia polarization via the activation of the STAT6 signaling pathway.

Mitochondrial Quality and Quantity Control: Mitophagy Is a Potential Therapeutic Target for Ischemic Stroke

Ischemic stroke is a cerebrovascular disease with high mortality and disability, which seriously affects the health and lives of people around the world. Effective treatment for ischemic stroke has been limited by its complex pathological mechanisms. Increasing evidence has indicated that mitochondrial dysfunction plays an essential role in the occurrence, development, and pathological processes of ischemic stroke. Therefore, strict control of the quality and quantity of mitochondria via mitochondrial fission and fusion as well as mitophagy is beneficial to the survival and normal function maintenance of neurons. Under certain circumstances, excessive mitophagy also could induce cell death. This review discusses the dynamic changes and double-edged roles of mitochondria and related signaling pathways of mitophagy in the pathophysiology of ischemic stroke. Furthermore, we focus on the possibility of modulating mitophagy as a potential therapy for the prevention and prognosis of ischemic stroke. Notably, we reviewed recent advances in the studies of natural compounds, which could modulate mitophagy and exhibit neuroprotective effects, and discussed their potential application in the treatment of ischemic stroke.

Role of Mitophagy in the Pathogenesis of Stroke: From Mechanism to Therapy

Mitochondria can supply adenosine triphosphate (ATP) to the tissue, which can regulate metabolism during the pathologic process and is also involved in the pathophysiology of neuronal injury after stroke. Recent studies have suggested that selective autophagy could play important roles in the pathophysiological process of stroke, especially mitophagy. It is usually mediated by the PINK1/Parkin-independent pathway or PINK1/Parkin-dependent pathway. Moreover, mitophagy may be a potential target in the therapy of stroke because the control of mitophagy is neuroprotective in stroke in vitro and in vivo. In this review, we briefly summarize recent researches in mitophagy, introduce the role of mitophagy in the pathogenesis of stroke, then highlight the strategies targeting mitophagy in the treatment of stroke, and finally propose several issues in the treatment of stroke by targeting mitophagy.

Pink1/Parkin-Mediated Mitophagy Regulated the Apoptosis of Dendritic Cells in Sepsis

Dendritic cells (DCs) are vital antigen-presenting cells (APCs) in the immune system, whose apoptosis is closely related to the development of sepsis. Mitophagy is one of the necessary forms of selective autophagy that removes damaged or dysfunctional mitochondria to regulate immunity and inflammation. However, its effect on the apoptosis of DC in sepsis remains unknown. Here, we showed that sepsis activated the apoptosis and mitophagy of DC, and mitophagy had an anti-apoptotic effect on sepsis-induced DC apoptosis. In this study, we used cecal ligation and puncture (CLP) to simulate the pathophysiological state of sepsis. Apoptosis and mitophagy of DC were significantly enhanced in CPL mice compared with controls, and in the Pink1-KO (Pink1-knockout) mice CLP model, the level of apoptosis in DC was further increased while the level of mitophagy was decreased. In addition, more severe mitochondrial dysfunction was exhibited in DC of Pink1-KO mice CLP model compared to wild-type (WT) mice. The results suggest that Pink1/Parkin-mediated mitophagy is activated during sepsis and has an anti-apoptotic effect on DC, which regulates immune functions.

The dual roles of autophagy and the GPCRs-mediating autophagy signaling pathway after cerebral ischemic stroke

Ischemic stroke, caused by a lack of blood supply in brain tissues, is the third leading cause of human death and disability worldwide, and usually results in sensory and motor dysfunction, cognitive impairment, and in severe cases, even death. Autophagy is a highly conserved lysosome-dependent process in which eukaryotic cells removal misfolded proteins and damaged organelles in cytoplasm, which is critical for energy metabolism, organelle renewal, and maintenance of intracellular homeostasis. Increasing evidence suggests that autophagy plays important roles in pathophysiological mechanisms under ischemic conditions. However, there are still controversies about whether autophagy plays a neuroprotective or damaging role after ischemia. G-protein-coupled receptors (GPCRs), one of the largest protein receptor superfamilies in mammals, play crucial roles in various physiological and pathological processes. Statistics show that GPCRs are the targets of about one-fifth of drugs known in the world, predicting potential values as targets for drug research. Studies have demonstrated that nutritional deprivation can directly or indirectly activate GPCRs, mediating a series of downstream biological processes, including autophagy. It can be concluded that there are interactions between autophagy and GPCRs signaling pathway, which provides research evidence for regulating GPCRs-mediated autophagy. This review aims to systematically discuss the underlying mechanism and dual roles of autophagy in cerebral ischemia, and describe the GPCRs-mediated autophagy, hoping to probe promising therapeutic targets for ischemic stroke through in-depth exploration of the GPCRs-mediated autophagy signaling pathway.

Deoxyhypusine hydroxylase as a novel pharmacological target for ischemic stroke via inducing a unique post-translational hypusination modification

Ischemic stroke remains one of the leading causes of death worldwide, thereby highlighting the urgent necessary to identify new therapeutic targets. Deoxyhypusine hydroxylase (DOHH) is a fundamental enzyme catalyzing a unique posttranslational hypusination modification of eukaryotic translation initiation factor 5A (eIF5A) and is highly involved in the progression of several human diseases, including HIV-1 infection, cancer, malaria, and diabetes. However, the potential therapeutic role of pharmacological regulation of DOHH in ischemic stroke is still poorly understood. Our study first discovered a natural small-molecule brazilin (BZ) with an obvious neuroprotective effect against oxygen-glucose deprivation/reperfusion insult. Then, DOHH was identified as a crucial cellular target of BZ using HuProt™ human proteome microarray. By selectively binding to the Cys232 residue, BZ induced a previously undisclosed allosteric effect to significantly increase DOHH catalytic activity. Furthermore, BZ-mediated DOHH activation amplified mitophagy for mitochondrial function and morphology maintenance via DOHH/eIF5A hypusination signaling pathway, thereby protecting against ischemic neuronal injury in vitro and in vivo. Collectively, our study first identified DOHH as a previously unreported therapeutic target for ischemic stroke, and provided a future drug design direction for DOHH allosteric activators using BZ as a novel molecular template.

Mitochondrial Quality Control: A Pathophysiological Mechanism and Therapeutic Target for Stroke

Stroke is a devastating disease with high mortality and disability rates. Previous research has established that mitochondria, as major regulators, are both influenced by stroke, and further regulated the development of poststroke injury. Mitochondria are involved in several biological processes such as energy generation, calcium homeostasis, immune response, apoptosis regulation, and reactive oxygen species (ROS) generation. Meanwhile, mitochondria can evolve into various quality control systems, including mitochondrial dynamics (fission and fusion) and mitophagy, to maintain the homeostasis of the mitochondrial network. Various activities of mitochondrial fission and fusion are associated with mitochondrial integrity and neurological injury after stroke. Additionally, proper mitophagy seems to be neuroprotective for its effect on eliminating the damaged mitochondria, while excessive mitophagy disturbs energy generation and mitochondria-associated signal pathways. The balance between mitochondrial dynamics and mitophagy is more crucial than the absolute level of each process. A neurovascular unit (NVU) is a multidimensional system by which cells release multiple mediators and regulate diverse signaling pathways across the whole neurovascular network in a way with a high dynamic interaction. The turbulence of mitochondrial quality control (MQC) could lead to NVU dysfunctions, including neuron death, neuroglial activation, blood–brain barrier (BBB) disruption, and neuroinflammation. However, the exact changes and effects of MQC on the NVU after stroke have yet to be fully illustrated. In this review, we will discuss the updated mechanisms of MQC and the pathophysiology of mitochondrial dynamics and mitophagy after stroke. We highlight the regulation of MQC as a potential therapeutic target for both ischemic and hemorrhagic stroke.