Protective Effects of ShcA Protein Silencing for Photothrombotic Cerebral Infarction

Pharmacological Inhibition of LRRK2 Exhibits Neuroprotective Activity in Mouse Photothrombotic Stroke Model

Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common cause of Parkinson's disease (PD). Interestingly, recent studies have reported an increased risk of stroke in patients with PD harboring LRRK2 mutations, but there is no evidence showing the functional involvement of LRRK2 in stroke. Here, we found that LRRK2 kinase activity was significantly induced in the Rose-Bengal (RB) photothrombosis-induced stroke mouse model. Interestingly, stroke infarct volumes were significantly reduced, and neurological deficits were diminished by pharmacological inhibition of LRRK2 kinase activity using MLi-2, a brain-penetrant LRRK2 kinase inhibitor. Immunohistochemical analysis showed p-LRRK2 level in stroke lesions, co-localizing with mitophagy-related proteins (PINK, Parkin, LC3B, cytochrome c), suggesting their involvement in stroke progression. Overlapping p-LRRK2 with cytochrome c/TUNEL/JC-1 (an indicator of mitochondrial membrane potential) puncta in RB photothrombosis indicated LRRK2-induced mitochondrial apoptosis, which was blocked by MLi-2. These results suggest that pharmacological inhibition of LRRK2 kinase activity could attenuate mitochondrial apoptosis, ultimately leading to neuroprotective potential in stroke progression. In conclusion, LRRK2 kinase activity might be neuro-pathogenic due to impaired mitophagy in stroke progression, and pharmacological inhibition of LRRK2 kinase activity could be beneficial in reducing the risk of stroke in patients with LRRK2 mutations.

Peptide-mediated targeted delivery of SOX9 nanoparticles into astrocytes ameliorates ischemic brain injury

Astrocytes are highly activated following brain injuries, and their activation influences neuronal survival. Additionally, SOX9 expression is known to increase in reactive astrocytes. However, the role of SOX9 in activated astrocytes following ischemic brain damage has not been clearly elucidated yet. Therefore, in the present study, we investigated the role of SOX9 in reactive astrocytes using a poly-lactic-co-glycolic acid (PLGA) nanoparticle plasmid delivery system in a photothrombotic stroke animal model. We designed PLGA nanoparticles to exclusively enhance SOX9 gene expression in glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Our observations indicate that PLGA nanoparticles encapsulated with GFAP:SOX9:tdTOM reduce ischemia-induced neurological deficits and infarct volume through the prostaglandin D2 pathway. Thus, the astrocyte-targeting PLGA nanoparticle plasmid delivery system provides a potential opportunity for stroke treatment. Since the only effective treatment currently available is reinstating the blood supply, cell-specific gene therapy using PLGA nanoparticles will open a new therapeutic paradigm for brain injury patients in the future.

Intrathecal delivery of Macromolecules: Clinical status and emerging technologies

The proximity and association of cerebrospinal fluid (CSF) and the intrathecal (IT) space with deep targets in the central nervous system (CNS) parenchyma makes IT injection an attractive route of administration for brain drug delivery. However, the extent to which intrathecally administered macromolecules are effective in treating neurological diseases is a question of both clinical debate and technological interest. We present the biological, chemical, and physical properties of the intrathecal space that are relevant to drug absorption, distribution, metabolism, and elimination from CSF. We then analyze the evolution of IT drug delivery in clinical trials over the last 20 years. Our analysis revealed that the percentage of clinical trials assessing IT delivery for the delivery of biologics (i.e., macromolecules, cells) for treatment of chronic conditions (e.g., neurodegeneration, cancer, and metabolic diseases) has steadily increased. Clinical trials exploring cell or macromolecular delivery within the IT space have not evaluated engineering technologies, such as depots, particles, or other delivery systems. Recent pre-clinical studies have evaluated IT macromolecule delivery in small animals, postulating that delivery efficacy can be assisted by external medical devices, micro- or nanoparticles, bulk biomaterials, and viral vectors. Further studies are necessary to evaluate the extent to which engineering technologies and IT administration improve CNS targeting and therapeutic outcome.

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.

PINK1 siRNA-loaded poly(lactic-co-glycolic acid) nanoparticles provide neuroprotection in a mouse model of photothrombosis-induced ischemic stroke

PTEN-induced kinase 1 (PINK1) is a well-known critical marker in the pathway for mitophagy regulation as well as mitochondrial dysfunction. Evidence suggests that mitochondrial dynamics and mitophagy flux play an important role in the development of brain damage from stroke pathogenesis. In this study, we propose a treatment strategy using nanoparticles that can control PINK1. We used a murine photothrombotic ischemic stroke (PTS) model in which clogging of blood vessels is induced with Rose Bengal (RB) to cause brain damage. We targeted PINK1 with poly(lactic-co-glycolic acid) (PLGA)-based nanoparticles loaded with PINK1 siRNA (PINK1 NPs). After characterizing siRNA loading in the nanoparticles, we assessed the efficacy of PINK1 NPs in mice with PTS using immunohistochemistry, 1% 2,3,5-triphenyltetrazolium chloride staining, measurement of motor dysfunction, and Western blot. PINK1 was highly expressed in microglia 24 h after PTS induction. PINK1 siRNA treatment increased phagocytic activity, migration, and expression of an anti-inflammatory state in microglia. In addition, the PLGA nanoparticles were selectively taken up by microglia and specifically regulated PINK1 expression in those cells. Treatment with PINK1 NPs prior to stroke induction reduced expression of mitophagy-inducing factors, infarct volume, and motor dysfunction in mice with photothrombotic ischemia. Experiments with PINK1-knockout mice and microglia depletion with PLX3397 confirmed a decrease in stroke-induced infarct volume and behavioral dysfunction. Application of nanoparticles for PINK1 inhibition attenuates RB-induced photothrombotic ischemic injury by inhibiting microglia responses, suggesting that a nanomedical approach targeting the PINK1 pathway may provide a therapeutic avenue for stroke treatment.

Role of Estrogen-Related Receptor γ and PGC-1α/SIRT3 Pathway in Early Brain Injury After Subarachnoid Hemorrhage

Estrogen-related receptors (ERRs) were shown to play an important role in the regulation of free radical-mediated pathology. This study aimed to investigate the neuroprotective effect of ERRγ activation against early brain injury (EBI) after subarachnoid hemorrhage (SAH) and the potential underlying mechanisms. In a rat model of SAH, the time course of ERRs and SIRT3 and the effects of ERRγ activation were investigated. ERRγ agonist DY131, selective inhibitor GSK5182, or SIRT3 selective inhibitor 3-TYP were administered intracerebroventricularly (icv) in the rat model of SAH. The use of 3-TYP was for validating SIRT3 as the downstream signaling of ERRγ activation. Post-SAH assessments included SAH grade, neurological score, Western blot, Nissl staining, and immunofluorescence staining in rats. In an vitro study, the ERRγ agonist DY131 and ERRγ siRNA were administered to primary cortical neurons stimulated by Hb, after which cell viability and neuronal deaths were accessed. Lastly, the brain ERRγ levels and neuronal death were accessed in SAH patients. We found that brain ERRγ expressions were significantly increased, but the expression of SIRT3 dramatically decreased after SAH in rats. In the brains of SAH rats, ERRγ was expressed primarily in neurons, astrocytes, and microglia. The activation of ERRγ with DY131 significantly improved the short-term and long-term neurological deficits, accompanied by reductions in oxidative stress and neuronal apoptosis at 24 h after SAH in rats. DY131 treatment significantly increased the expressions of PGC-1α, SIRT3, and Bcl-2 while downregulating the expressions of 4-HNE and Bax. ERRγ antagonist GSK5182 and SIRT3 inhibitor 3-TYP abolished the neuroprotective effects of ERRγ activation in the SAH rats. An in vitro study showed that Hb stimulation significantly increased intracellular oxidative stress in primary cortical neurons, and DY131 reduced such elevations. Primary cortical neurons transfected with the ERRγ siRNA exhibited notable apoptosis and abolished the protective effect of DY131. The examination of SAH patients' brain samples revealed increases in ERRγ expressions and neuronal apoptosis marker CC3. We concluded that ERRγ activation with DY131 ameliorated oxidative stress and neuronal apoptosis after the experimental SAH. The effects were, at least in part, through the ERRγ/PGC-1α/SIRT3 signaling pathway. ERRγ may serve as a novel therapeutic target to ameliorate EBI after SAH.

AMPK/MFF Activation: Role in Mitochondrial Fission and Mitophagy in Dry Eye

Purpose

To assess the role of mitochondrial morphology and adenosine monophosphate-activated protein kinase (AMPK)/mitochondrial fission factor (MFF) in dry eye and the underlying mechanisms.

Methods

Immortalized human corneal epithelial cells (HCECs) and primary HCECs were cultured under high osmotic pressure (HOP). C57BL/6 female mice were injected subcutaneously with scopolamine. Quantitative real-time PCR was used to measure mRNA expression. Protein expression was assessed by western blot and immunofluorescence staining. Mitochondrial morphology was observed by confocal microscopy and transmission electron microscopy.

Results

First, HOP induced mitochondrial oxidative damage to HCECs, accompanied by mitochondrial fission and increased mitophagy. Then, AMPK/MFF pathway proteins were increased consequent to HOP-induced energy metabolism dysfunction. Interestingly, the AMPK pathway promoted mitochondrial fission and mitophagy by increasing the recruitment of dynamin-related protein 1 (DRP1) to the mitochondrial outer membrane in the HOP group. Moreover, AMPK knockdown attenuated mitochondrial fission and mitophagy due to HOP in HCECs. AMPK activation triggered mitochondrial fission and mitophagy. Mitochondrial fission of HCECs stressed by HOP was mediated via MFF phosphorylation. MFF knockdown reversed mitochondrial fragmentation and mitophagy in HCECs treated with HOP. Inhibition of MFF protected HCECs against oxidative damage, cell death, and inflammation in the presence of HOP. Finally, we detected mitochondrial fission and AMPK pathway activation in vivo.

Conclusions

The AMPK/MFF pathway mediates the development of dry eye by positively regulating mitochondrial fission and mitophagy. Inhibition of mitochondrial fission can alleviate oxidative damage and inflammation in dry eye and may provide experimental evidence for treating dry eye.

LONG NONCODING RNA UPREGULATES ADAPTER SHCA PROTEIN EXPRESSION TO PROMOTE COGNITIVE IMPAIRMENT AFTER CARDIAC ARREST AND RESUSCITATION

ABSTRACT

Aim: More patients are resuscitated from cardiac arrest and cardiopulmonary resuscitation (CA/CPR) due to advances in medical care. However, the burden now lies with post-cardiac arrest cognitive impairment in CA/CPR survivors. Based on our previous study, we aimed to further confirm the correlation between the long noncoding RNA-promoting ShcA (lncRNA-PS)/Src homology and collagen A (ShcA) axis and CA/CPR-induced cognitive impairment in molecular, cellular, and tissue levels. Methods and Results: The in vivo experiments were based on a mouse model of CA/CPR, while oxygen-glucose deprivation and reoxygenation was used as a cell model in vitro. Conditional ShcA suppression in neurons of the hippocampal CA1 region was achieved by cyclization recombinase of bacteriophage P1 recognizing DNA fragment locus of x-over P1 site (Cre/LoxP recombination system). Genetic manipulation of HT22 was achieved by lentivirus targeting lncRNA-PS and ShcA. Neurological function score was remarkably decreased, and cognitive function was affected after restoration of spontaneous circulation. LncRNA-PS and ShcA overexpression after CA/CPR, mainly happened in neurons of hippocampal CA1 region, was observed by in situ hybridization and immunofluorescence. Neuronal ShcA knockdown in hippocampal CA1 region before CA/CPR attenuated cognitive impairment after CA/CPR. ShcA deficiency protected HT22 cell line against oxygen-glucose deprivation and reoxygenation by inhibiting inflammation and apoptosis. In vitro upregulation of lncRNA-PS elevated ShcA expression, which was reversed by knockdown of ShcA. Conclusions: This study revealed that lncRNA-PS/ShcA axis is critically involved in the pathogenesis of cognitive impairment after CA/CPR. By inhibiting ShcA expression in neurons of the hippocampal CA1 region could improve the survival outcomes in mice after CA/CPR.

Perampanel Reduces Brain Damage via Induction of M2 Microglia in a Neonatal Rat Stroke Model

Purpose

Ischemic stroke is a leading cause of death and disability worldwide. Additionally, neonatal ischemia is a common cause of neonatal brain injury, resulting in cerebral palsy with subsequent learning disabilities and epilepsy. However, there is currently a lack of effective treatments available for patients with perinatal ischemic stroke. In this study, we investigated the effect of perampanel (PER)-loaded poly lactic-co-glycolic acid (PLGA) by targeting microglia in perinatal stroke.

Methods

After formation of focal ischemic stroke by photothrombosis in P7 rats, PER-loaded PLGA was injected intrathecally. Proinflammatory markers (TNF-α, IL-1β, IL-6, COX2, and iNOS) and M2 polarization markers (Ym1 and Arg1) were evaluated. We investigated whether PER increased M2 microglial polarization in vitro.

Results

PER-loaded PLGA nanoparticles decreased the pro-inflammatory cytokines compared to the control group. Furthermore, they increased M2 polarization.

Conclusion

PER-loaded PLGA nanoparticles decreased the size of the infarct and increased motor function in a perinatal ischemic stroke rat model. Pro-inflammatory cytokines were also reduced compared to the control group. Finally, this development of a drug delivery system targeting microglia confirms the potential to develop new therapeutic agents for perinatal ischemic stroke.

Pan-Cancer Study of SHC-Adaptor Protein 1 (SHC1) as a Diagnostic, Prognostic and Immunological Biomarker in Human Cancer

Background: Recent studies highlight the carcinogenesis role of SHC-adaptor protein 1 (SHC1) in cancer initiation, development, and progression. However, its aberrant expression, diagnostic and prognostic value remain unknown in a variety of tumors.

Methods: The SHC1 expression profiles were analyzed using GTEx database, TCGA database, Oncomine and CPTAC database. The survival analysis was conducted using GEPIA2, Kaplan-Meier Plotter, UALCAN, and PrognoScan. The diagnostic values of SHC1 were calculated with the “pROC” package in R software. The genetic alteration of SHC1 and mutations were analyzed using cBioPortal. TIMER2 was employed to estimate the correlations between SHC1 expression and tumor-infiltrating immune cells in the TCGA cohort. Enrichment analysis of SHC1 was conducted using the R package “clusterProfiler.”

Results: SHC1 was ubiquitously highly expressed and closely associated with worse prognosis of multiple major cancer types (all p < 0.05). Further, SHC1 gene mutations were strongly linked to poor OS and DFS in SKCM (all p < 0.05). An enhanced phosphorylation level of SHC1 at the S139 site was observed in clear cell RCC. Additionally, the results revealed SHC1 expression was strongly linked to TMB, MMRs, MSI, TAMs, DNA methylation, m6A RNA methylation, tumor-associated immune infiltration, and immune checkpoints in multiple cancers (all p < 0.05). In addition, the results of the ROC analysis indicated the SHC1 exhibited strong diagnostic capability for KICH (AUC = 0.92), LIHC (AUC = 0.95), and PAAD (AUC = 0.95). Finally, enrichment analysis indicated that SHC1 may potentially involve in the regulation of numerous signaling pathways in cancer metabolism and protein phosphorylation-related functions.

Conclusions: These findings highlight that SHC1 plays an important role in the tumor immune microenvironment, and SHC1 has been identified to have prognostic and diagnostic value in multiple cancers. Thus, SHC1 is a potential target for cancer immunotherapy and effective prognostic and diagnostic biomarker.

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.

Dipsacoside B Exerts a Beneficial Effect on Brain Injury in the Ischemic Stroke Rat through Inhibition of Mitochondrial E3 Ubiquitin Ligase 1

BACKGROUND

Upregulation of mitochondrial E3 ubiquitin ligase 1 (Mul1) contributes to brain injury in ischemic stroke due to disturbance of mitochondrial dynamics, and bioinformatics analysis predicts that Mul1 is a potential target of Dipsacoside B.

OBJECTIVE

The aim of the study was to explore whether Dipsacoside B can exert a beneficial effect on brain injury in the ischemic stroke rat via targeting Mul1.

METHODS

The SD rat brains or PC12 cells were subjected to 2 h-ischemia or 8 h-hypoxia plus 24 h-reperfusion or 24 h-reoxygenation to establish the ischemic stroke rat model in vivo or in vitro, which were treated with Dipsacoside B at different dosages. The brain or PC12 cell injury, relevant protein levels and mitochondrial functions were measured by methods of biochemistry, flow cytometry or Western blot.

RESULTS

The neurological dysfunction and brain injury (such as infarction and apoptosis) observed in the ischemic stroke rats were accompanied by increases in Mul1 and dynamin-related protein 1 (Drp1) levels along with decreases in mitofusin 2 (Mfn2) level and ATP production. These effects were attenuated by Dipsacoside B. Consistently, cell injury (necroptosis and apoptosis) occurred in the PC12 cells exposed to hypoxia concomitant with the upregulation of Mul1 and Drp1 along with downregulation of Mfn2 and mitochondrial functions (such as increases in reactive oxygen species production and mitochondrial fission and decreases in mitochondrial membrane potential and ATP production).These phenomena were reversed in the presence of Dipsacoside B.

CONCLUSION

Dipsacoside B can protect the rat brain against ischemic injury via inhibition of Mul1 due to the improvement of mitochondrial function.

Mitochondrial Dynamics: A Potential Therapeutic Target for Ischemic Stroke

Stroke is one of the leading causes of death and disability worldwide. Brain injury after ischemic stroke involves multiple pathophysiological mechanisms, such as oxidative stress, mitochondrial dysfunction, excitotoxicity, calcium overload, neuroinflammation, neuronal apoptosis, and blood-brain barrier (BBB) disruption. All of these factors are associated with dysfunctional energy metabolism after stroke. Mitochondria are organelles that provide adenosine triphosphate (ATP) to the cell through oxidative phosphorylation. Mitochondrial dynamics means that the mitochondria are constantly changing and that they maintain the normal physiological functions of the cell through continuous division and fusion. Mitochondrial dynamics are closely associated with various pathophysiological mechanisms of post-stroke brain injury. In this review, we will discuss the role of the molecular mechanisms of mitochondrial dynamics in energy metabolism after ischemic stroke, as well as new strategies to restore energy homeostasis and neural function. Through this, we hope to uncover new therapeutic targets for the treatment of ischemic stroke.