Strong neuroprotection by inhibition of NF-kappaB after neonatal hypoxia-ischemia involves apoptotic mechanisms but is independent of cytokines

Antiapoptotic Effects of Hydroxychloroquine on Hypoxic-Ischemic Injury in Neonatal Rat Brain: May Hydroxychloroquine Be an Adjuvant Theraphy?

OBJECTIVE

Hydroxychloroquine (HCQ) has immunomodulatory, antithrombotic, cardiovascular, antimicrobial, and antineoplastic effects. In this study, we aimed to investigate the antiapoptotic and immunomodulator effects of intraperitoneal HCQ on hypoxic-ischemic (HI) injury in newborn rats.

STUDY DESIGN

Wistar albino rats, 7 to 10 days old, were randomly divided into three groups: hypoxic-ischemic encephalopathy (HIE) group, HIE treated with HCQ group, and Sham group. Left common carotid artery ligation and hypoxia model were performed in HIE and HCQ groups. The HCQ group was treated with 80 mg/kg intraperitoneal HCQ every 24 hours for 3 days, while Sham and HIE groups were given physiological saline. After 72 hours, rats were decapitated and brain tissues were stained with hematoxylin and eosin, TUNEL, and IL-1β for histopathological grading and neuronal cell injury.

RESULTS

Neuronal apoptosis was statistically lower in all neuroanatomical areas in the HCQ group compared with the HIE group. IL-1β-stained areas were similar in both HCQ and HIE groups but significantly higher compared with the Sham group. Histopathological grading scores were found to be lower in the HCQ group on the left parietal cortex and hippocampus region.

CONCLUSION

In this study, we have shown for the first time that HCQ treatment decreased apoptosis in HI newborn rat model in both hemispheres. HCQ may be a promising adjuvant therapy in neonatal HIE.

KEY POINTS

· HCQ decreased neuronal apoptosis in the ischemic penumbra of the rat brain.. · HCQ attenuates hypoxia-ischemia-induced brain injury in neonatal rats.. · HCQ has no anti-inflammatory effect on HI injury..

Post-stroke brain can be protected by modulating the lncRNA FosDT

We previously showed that knockdown or deletion of Fos downstream transcript (FosDT; a stroke-induced brain-specific long noncoding RNA) is neuroprotective. We presently tested the therapeutic potential of FosDT siRNA in rodents subjected to transient middle cerebral artery occlusion (MCAO) using the Stroke Treatment Academic Industry Roundtable criteria, including sex, age, species, and comorbidity. FosDT siRNA (IV) given at 30 min of reperfusion significantly improved motor function recovery (rotarod test, beam walk test, and adhesive removal test) and reduced infarct size in adult and aged spontaneously hypertensive rats of both sexes. FosDT siRNA administered in a delayed fashion (3.5 h of reperfusion following 1 h transient MCAO) also significantly improved motor function recovery and decreased infarct volume. Furthermore, FosDT siRNA enhanced post-stroke functional recovery in normal and diabetic mice. Mechanistically, FosDT triggered post-ischemic neuronal damage via the transcription factor REST as REST siRNA mitigated the enhanced functional outcome in FosDT-/- rats. Additionally, NF-κB regulated FosDT expression as NF-κB inhibitor BAY 11-7082 significantly decreased post-ischemic FosDT induction. Thus, FosDT is a promising target with a favorable therapeutic window to mitigate secondary brain damage and facilitate recovery after stroke regardless of sex, age, species, and comorbidity.

Ethanolic Extract of Polygonum minus Protects Differentiated Human Neuroblastoma Cells (SH-SY5Y) against H2O2-Induced Oxidative Stress

Neuronal models are an important tool in neuroscientific research. Hydrogen peroxide (H2O2), a major risk factor of neuronal oxidative stress, initiates a cascade of neuronal cell death. Polygonum minus Huds, known as 'kesum', is widely used in traditional medicine. P. minus has been reported to exhibit a few medicinal and pharmacological properties. The current study aimed to investigate the neuroprotective effects of P. minus ethanolic extract (PMEE) on H2O2-induced neurotoxicity in SH-SY5Y cells. LC-MS/MS revealed the presence of 28 metabolites in PMEE. Our study showed that the PMEE provided neuroprotection against H2O2-induced oxidative stress by activating the Nrf2/ARE, NF-κB/IκB and MAPK signaling pathways in PMEE pre-treated differentiated SH-SY5Y cells. Meanwhile, the acetylcholine (ACH) level was increased in the oxidative stress-induced treatment group after 4 h of exposure with H2O2. Molecular docking results with acetylcholinesterase (AChE) depicted that quercitrin showed the highest docking score at -9.5 kcal/mol followed by aloe-emodin, afzelin, and citreorosein at -9.4, -9.3 and -9.0 kcal/mol, respectively, compared to the other PMEE's identified compounds, which show lower docking scores. The results indicate that PMEE has neuroprotective effects on SH-SY5Y neuroblastoma cells in vitro. In conclusion, PMEE may aid in reducing oxidative stress as a preventative therapy for neurodegenerative diseases.

CD36 neutralisation blunts TLR2-IRF7 but not IRF3 pathway in neonatal mouse brain and immature human microglia following innate immune challenge

Innate immune response in neonatal brain is associated with a robust microglial activation and induction of Toll-like Receptors (TLRs). To date, the role of the scavenger receptor CD36 in TLRs modulation, particularly TLR2 signaling, has been well established in adult brain. However, the crosstalk between TLR4, TLR2 and CD36 and its immunogenic influence in the neonatal brain remains unclear. In this study, using a CD36 blocking antibody (anti-CD36) at post-natal day 8, we evaluated the response of neonates to systemic endotoxin (lipopolysaccharide; LPS) challenge. We visualized the TLR2 response by bioluminescence imaging using the transgenic mouse model bearing the dual reporter system luciferase/green fluorescent protein under transcriptional control of a murine TLR2 promoter. The anti-CD36 treatment modified the LPS induced inflammatory profile in neonatal brains, causing a significant decrease in inflammatory cytokine levels and the TLR2 and TLR3 mediated signalling.The interferon regulatory factor 3 (IRF3) pathway remained unaffected. Treatment of the LPS-challenged human immature microglia with anti-CD36 induced a marked decrease in TLR2/TLR3 expression levels while TLR4 and IRF3 expression was not affected, suggesting the shared CD36 regulatory mechanisms in human and mouse microglia. Collectively, our results indicate that blocking CD36 alters LPS-induced inflammatory profile of mouse and human microglia, suggesting its role in fine-tuning of neuroinflammation.

NF-κB Signaling-Mediated Activation of WNK-SPAK-NKCC1 Cascade in Worsened Stroke Outcomes of Ang II-Hypertensive Mice

BACKGROUND

Worsened stroke outcomes with hypertension comorbidity are insensitive to blood pressure-lowering therapies. In an experimental stroke model with comorbid hypertension, we investigated causal roles of ang II (angiotensin II)-mediated stimulation of the brain WNK (with no lysine [K] kinases)-SPAK (STE20/SPS1-related proline/alanine-rich kinase)-NKCC1 (Na-K-Cl cotransporter) complex in worsened outcomes.

METHODS

Saline- or ang II-infused C57BL/6J male mice underwent stroke induced by permanent occlusion of the distal branches of the middle cerebral artery. Mice were randomly assigned to receive either vehicle dimethyl sulfoxide/PBS (2 mL/kg body weight/day, IP), a novel SPAK inhibitor, 5-chloro-N-(5-chloro-4-((4-chlorophenyl)(cyano)methyl)-2-methylphenyl)-2-hydroxybenzamide (ZT-1a' 5 mg/kg per day, IP) or a NF-κB (nuclear factor-κB) inhibitor TAT-NBD (transactivator of transcription-NEMO-binding domain' 20 mg/kg per day, IP). Activation of brain NF-κB and WNK-SPAK-NKCC1 cascade as well as ischemic stroke outcomes were examined.

RESULTS

Stroke triggered a 2- to 5-fold increase of WNK (isoforms 1, 2, 4), SPAK/OSR1 (oxidative stress-responsive kinase 1), and NKCC1 protein in the ang II-infused hypertensive mouse brains at 24 hours after stroke, which was associated with increased nuclear translocation of phospho-NF-κB protein in the cortical neurons (a Pearson correlation r of 0.77, P<0.005). The upregulation of WNK-SPAK-NKCC1 cascade proteins resulted from increased NF-κB recruitment on Wnk1, Wnk2, Wnk4, Spak, and Nkcc1 gene promoters and was attenuated by NF-κB inhibitor TAT-NBD. Poststroke administration of SPAK inhibitor ZT-1a significantly reduced WNK-SPAK-NKCC1 complex activation, brain lesion size, and neurological function deficits in the ang II-hypertensive mice without affecting blood pressure and cerebral blood flow.

CONCLUSIONS

The ang II-induced stimulation of NF-κB transcriptional activity upregulates brain WNK-SPAK-NKCC1 cascade and contributes to worsened ischemic stroke outcomes, illustrating the brain WNK-SPAK-NKCC1 complex as a therapeutic target for stroke with comorbid hypertension.

Induction of Tertiary Phase Epileptiform Discharges after Postasphyxial Infusion of a Toll-Like Receptor 7 Agonist in Preterm Fetal Sheep

Background: Toll-like receptor (TLR) agonists are key immunomodulatory factors that can markedly ameliorate or exacerbate hypoxic–ischemic brain injury. We recently demonstrated that central infusion of the TLR7 agonist Gardiquimod (GDQ) following asphyxia was highly neuroprotective after 3 days but not 7 days of recovery. We hypothesize that this apparent transient neuroprotection is associated with modulation of seizure-genic processes and hemodynamic control. Methods: Fetuses received sham asphyxia or asphyxia induced by umbilical cord occlusion (20.9 ± 0.5 min) and were monitored continuously for 7 days. GDQ 3.34 mg or vehicle were infused intracerebroventricularly from 1 to 4 h after asphyxia. Results: GDQ infusion was associated with sustained moderate hypertension that resolved after 72 h recovery. Electrophysiologically, GDQ infusion was associated with reduced number and burden of postasphyxial seizures in the first 18 h of recovery (p < 0.05). Subsequently, GDQ was associated with induction of slow rhythmic epileptiform discharges (EDs) from 72 to 96 h of recovery (p < 0.05 vs asphyxia + vehicle). The total burden of EDs was associated with reduced numbers of neurons in the caudate nucleus (r² = 0.61, p < 0.05) and CA1/2 hippocampal region (r² = 0.66, p < 0.05). Conclusion: These data demonstrate that TLR7 activation by GDQ modulated blood pressure and suppressed seizures in the early phase of postasphyxial recovery, with subsequent prolonged induction of epileptiform activity. Speculatively, this may reflect delayed loss of early protection or contribute to differential neuronal survival in subcortical regions.

NF-κB Blockade by NEMO Binding Domain Peptide Ameliorates Inflammation and Neurobehavioral Sequelae After Cranial Radiation Therapy in Juvenile Mice

PURPOSE

Cranial radiation therapy (CRT) is a common treatment for pediatric brain tumor patients. However, side effects include significant neurobehavioral dysfunction in survivors. This dysfunction may in part be caused by inflammation, including increased production of tumor necrosis factor alpha (TNFα) and its receptor TNFR1, which can activate the nuclear factor kappa light-chain enhancer of activated B cells (NF-κB). The TNFα blockade abrogates this inflammatory response, although it presents immunologic risks. Thus, modulation of pathway subsets may be preferable. Here, we test whether inhibition of NF-κB activation using an NF-κB essential modulator binding domain (NBD) peptide mitigates CRT-induced neuroinflammation and improves behavioral outcomes.

METHODS AND MATERIALS

Male C57BL/6J 28-day old mice were randomized to saline (sham), 5 Gy whole-brain CRT, or CRT + NBD-peptide. Brain tissue was collected after 4 hours or 3 months for Western blot or immunohistochemistry. The cortex, corpus callosum (CC), and dentate gyrus were variably imaged for NF-κB-p65, IκBα, proliferation, apoptosis, necroptosis, TNFα, TNFR1, IBA-1, doublecortin, CD11c, and GFAP. Neurobehavioral changes were assessed by open field and elevated plus maze tests 3 months post-CRT.

RESULTS

NF-κB expression increased in whole and nuclear fractions 4 hours after CRT and was abrogated by NBD treatment. Cell death increased and proliferation decreased after CRT, including within neuronal progenitors, with some loss mitigated by NBD. Increased levels of TNFα, IBA-1, and GFAP were found in the CC and cortex months after CRT and were limited by NBD. The anti-NF-κB peptide also improved neurobehavioral assessments, yielding improvements in anxiety and exploration.

CONCLUSIONS

Results suggest a role for NF-κB modulation by NBD peptide in the reduction of neuroinflammation and mitigation of behavioral complications after pediatric radiation therapy.

miR-21 protects neonatal rats from hypoxic-ischemic brain damage by targeting CCL3

Hypoxic-ischemic brain damage (HIBD) represents one of the leading causes of neonatal mortality and permanent neurological disability worldwide. Compelling studies have identified implication of microRNAs (miRNAs) in HIBD. However, the molecular mechanism of miR-21 underlying the disease pathogenesis is unknown. The present study aims to explore the role of miR-21 in neonatal rats with HIBD. HIBD rat models were developed by carotid artery ligation and hypoxia treatment, and in vitro cell models were induced by oxygen-glucose deprivation. Through RT-qPCR and western blot analysis, high expression of CCL3 and poor expression of miR-21 were detected in brain tissues of rats with HIBD. Results of dual-luciferase reporter gene assay demonstrated that miR-21 could target and downregulate CCL3. The effect of miR-21 on the neurobehavioral ability of rats, the pathological characteristics of brain tissues, neuron apoptosis and as well as its impact on the NF-κB signaling pathway-related factors was examined by gain- and loss-of-function experiments. The obtained data suggested that upregulation of miR-21 resulted in significantly reduced cerebral infarct volume and degree of brain tissue damage, and improved neurobehavioral ability and memory ability in rats with HIBD through downregulation of CCL3. Besides, overexpression of miR-21 downregulated CCL3 to repress IKKα/β and p65 phosphorylation both in vivo and in vitro, hence disrupting the NF-κB signaling pathway. Taken together, the key findings of the current study underlie the cerebral protective effect of miR-21 against HIBD in neonatal rats through the inhibition of CCL3.

A high-fat diet rich in corn oil exaggerates the infarct size and memory impairment in rats with cerebral ischemia and is associated with suppressing osteopontin and Akt, and activating GS3Kβ, iNOS, and NF-κB

The increase in osteopontin (OPN) levels after stroke induces neural protection by activating Akt signaling and inhibiting GS3Kβ, iNOS, and NF-κB. This study investigated the effect of a high-fat diet rich in corn oil (CO-HFD) on infarct size and memory function in rats after induction of cerebral ischemia in rats and investigated its effect on the expression of OPN/Akt/iNOS/NF-κB signaling pathways. Rats were initially fed a standard diet (STD, 3.82 kcal/g; 9.4%, from fat) or a CO-HFD (5.4 kcal/g, 40% from fat) for 12 weeks. Then, both groups were further subdivided into either sham group or group exposed to cerebral ischemia by the middle cerebral artery occlusion (MCAO) protocol. Compared with sham-operated rats fed STD diet, neurological scores and both short- and long-term memory functions were significantly impaired in sham-operated CO-HFD-fed rats. In addition, brains collected from CO-HFD-fed rats showed lower protein levels of OPN, p-Akt (Thr³⁰⁸), p-GS3Kβ (Ser⁹), and Bcl-2 and had higher protein levels of iNOS, cleaved caspase-3, nuclear NF-κB p65, and cytoplasmic cytochrome C. However, once exposed to MCAO surgery, similar but more profound alterations of all these biochemical parameters with more severe impairment in short- and long-term memory functions and larger infarct size were noticed in the brains of CO-HFD-fed rats as compared with STD-fed rats exposed to MCAO. In conclusion, chronic consumption of CO-HFD induces memory impairments and worsens memory function recovery and infarct size after cerebral ischemia in rats by reducing levels of OPN, inhibiting the activation of Akt and activating iNOS and NF-κB.

NF-κB as a Key Mediator of Brain Inflammation in Alzheimer's Disease

Alzheimer's disease is the most common form of dementia. It is characterized by betaamyloid peptide fibrils which are extracellular deposition of a specific protein, accompanied by extensive neuroinflammation. Various studies show the presence of a number of inflammation markers in the AD brain: elevated inflammatory cytokines and chemokines, and an accumulation of activated microglia in the damaged regions. NF-κB is a family of redox sensitive transcriptional factors, and it is known that NF-κB has binding sites in the promoter region of the genes involved in amyloidogenesis and inflammation. Long-term use of non-steroidal anti-inflammatory drugs prevents progression of AD and delays its onset, suggesting that there is a close correlation between NF-κB and AD pathogenesis. This study aims to (1) assess the association between NF-κB activity and AD through discussion of a variety of experimental and clinical studies on AD and (2) review treatment strategies designed to treat or prevent AD with NF-κB inhibitors.

IL-10 produces a dual effect on OGD-induced neuronal apoptosis of cultured cortical neurons via the NF-κB pathway

As a classic immunoregulatory cytokine, interleukin-10 (IL-10) can provide in vivo and in vitro neuroprotection respectively during cerebral ischemia and after the oxygen-glucose deprivation (OGD)-induced injury. However, its role in cortical neuronal survival at different post-ischemic phases remains unclear. The current study found that IL-10 had distinct effects on the neuronal apoptosis at different OGD stages: at an early stage after OGD, IL-10 promoted the OGD-induced neuronal apoptosis in the cultured primary cortical neurons by activating p65 subunit, which up-regulated Bax expression and down-regulated Bcl-xL expression; at a late OGD stage, however, it attenuated the OGD-induced neuronal apoptosis by activating c-Rel, which up-regulated Bcl-xL expression and down-regulated Bax expression. The early-stage pro-apoptosis and late-stage anti-apoptosis were both partly abolished by PDTC, an NF-κB inhibitor, and promoted by PMA, an NF-κB activator. The optimal anti-apoptotic effect appeared when the cultured neurons were treated with IL-10 at 9-24 h after OGD. Taken together, our findings suggest that IL-10 exerts a dual effect on the survival of the cultured neurons by activating the NF-κB pathway at different stages after OGD injury and that PMA treatment at a late stage can facilitate the IL-10-conferred neuroprotection against OGD-induced neuronal injury.

Genetic Aspects of Pathogenesis of Congenital Spastic Cerebral Paralysis

Congenital spastic cerebral palsy (СР) is a large group of non-progressive disorders of the nervous system. The basis of the pathogenesis of these conditions is considered the impact of many factors. The clinical diversity of the disease and the syndromic principle of classification determine the existing uncertainties in the diagnosis of these diseases. The multifactorial nature of the underlying brain lesions is obvious and beyond doubt. The volume of information accumulated to date does not allow one to exclude the role and significance of the direct effect of acute asphyxiation in childbirth on a fetus normally formed during pregnancy, the role of infectious brain lesions, and disorders of neuronal migration. It is impossible to ignore the dependence of the clinical picture of the disease on what stage of ontogenesis the impact of the damaging agent occurs. As one of the pathogenetic factors, the genetic determinism of the phenotype of the clinical picture of a disease is fairly considered. This review focuses on the genetic aspects of the pathogenesis of this pathology. The information on monogenic mechanisms of inheritance is analyzed in detail. Such genetically determined mechanisms of pathogenesis as the inheritance of prerequisites for brain trauma in the perinatal period are considered separately. The new clinically significant variants of chromosomal mutations found in patients with CР are reviewed in detail,  the evidence of the influence of genetic factors on the development of cerebral palsy in the absence of a pronounced monogenic cause of the disease, obtained through twin studies, is reviewed.  Lit search of polymorphisms markers of predisposition to the development of cerebral palsy genes of the folate cycle, genes of glutamate receptors, the gene of apolipoprotein and of the gene for the transcription factor of oligodendrocytes (OLIG2) in Detail the role of epigenetic effects on the activity of genes coding for mitochondrial proteins.

Acupuncture attenuates cognitive impairment, oxidative stress and NF-κB activation in cerebral multi-infarct rats

BACKGROUD

Patients with multiple infarct dementia (MID) have subtle deficits that commonly go unnoticed, and are at risk of developing Alzheimer's disease. Oxidative stress induced by ischaemic injury results in intracellular calcium accumulation and neuronal apoptosis, leading to cognitive impairment by triggering various cellular signal transduction pathways. Several studies have suggested that NF-κB in the presence of p53 has a pro-apoptotic function in various models, but the mechanism is unclear.

AIMS

The aim of this study was to investigate whether acupuncture could protect cognitive function against cerebral multi-infarction (CMi) induced oxidative stress by inhibiting the activation of NF-κB and its target gene p53.

METHODS

An animal model of CMi was established by injecting homologous blood emboli into the right internal carotid artery of male Wistar rats. After 2 weeks of acupuncture treatment, cognitive function was detected by novel object recognition. Electron spin resonance and Fluo-3 fuorescence imaging were used to test the generation of ROS and intracellular calcium accumulation, respectively. Expression of NF-κB and p53 was examined by Western blot analysis and immunofluorescence.

RESULTS

CMi induced spatial learning and memory impairment, overproduction of intracellular hydroxyl radicals, and elevations of Ca²⁺, which were ameliorated by verum acupuncture treatment. Acupuncture inhibited activation of NF-κB and its downstream target gene p53.

CONCLUSION

These findings suggest that acupuncture could protect cognitive function against oxidative stress induced by CMi, which is partially associated with suppression of NF-κB-p53 activation.

Magnesium induces preconditioning of the neonatal brain via profound mitochondrial protection

Magnesium sulphate (MgSO4) given to women in preterm labor reduces cerebral palsy in their offspring but the mechanism behind this protection is unclear, limiting its effective, safe clinical implementation. Previous studies suggest that MgSO4 is not neuroprotective if administered during or after the insult, so we hypothesised that MgSO4 induces preconditioning in the immature brain. Therefore, we administered MgSO4 at various time-points before/after unilateral hypoxia-ischemia (HI) in seven-day-old rats. We found that MgSO4 treatment administered as a bolus between 6 days and 12 h prior to HI markedly reduced the brain injury, with maximal protection achieved by 1.1 mg/g MgSO4 administered 24 h before HI. As serum magnesium levels returned to baseline before the induction of HI, we ascribed this reduction in brain injury to preconditioning. Cerebral blood flow was unaffected, but mRNAs/miRNAs involved in mitochondrial function and metabolism were modulated by MgSO4. Metabolomic analysis (H+-NMR) disclosed that MgSO4 attenuated HI-induced increases in succinate and prevented depletion of high-energy phosphates. MgSO4 pretreatment preserved mitochondrial respiration, reducing ROS production and inflammation after HI. Therefore, we propose that MgSO4 evokes preconditioning via induction of mitochondrial resistance and attenuation of inflammation.

Analysis of long non-coding RNA expression profiles in neonatal rats with hypoxic-ischemic brain damage

Hypoxic-ischemic brain damage (HIBD) which is a common cause of acute mortality and neurological dysfunction in neonates still lacks effective therapeutic methods. Long non-coding RNAs (lncRNAs) were demonstrated to play a crucial role in many diseases. To give a foundation for subsequent functional studies of lncRNAs in HIBD, we investigated the profiling of lncRNAs and messenger RNAs (mRNAs) using neonatal HIBD rat model. Six neonatal rats were divided into sham-operated group (n = 3) and HIBD group (n = 3) randomly. Deep RNA sequencing was implemented to find out the meaningful lncRNAs and mRNAs. Quantitative real-time PCR was used to validate expressions of lncRNAs and mRNAs. The Gene Ontology (GO) and kyoto encyclopedia of genes a genomes (KEGG) database were used to predict functions of lncRNAs. A total of 328 differentially expressed lncRNAs (177 down-regulated vs 151 up-regulated) and 7157 differentially expressed mRNAs (2552 down-regulated vs 4605 up-regulated) were identified. The Quantitative real-time PCR results showed significant differential expressions of five lncRNAs and five mRNAs which were consistent with the RNA-Seq data. Gene ontology and KEGG analysis showed these lncRNAs and their expression-correlated mRNAs were closely related to the Janus tyrosine kinase-signal transducer and activator of transcription (JAK-STAT) signaling pathway, NF-kappa B signaling pathway, Toll-like receptor signaling pathway, calcium signaling pathway, Notch signaling pathway, mitogen activated protein kinase signaling pathway, neuroactive ligand-receptor interaction pathway and more. The results of our study identified the characterization and expression profiles of lncRNAs in neonatal HIBD and may be a basis for further therapeutic research. OPEN SCIENCE BADGES: This article has received a badge for *Open Materials* and *Open Data* because it provided all relevant information to reproduce the study in the manuscript and because it made the data publicly available. The data can be accessed at https://osf.io/yf3da/. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/.

Nuclear factor-kappa β as a therapeutic target for Alzheimer's disease

Alzheimer's disease (AD) is a typical progressive, chronic neurodegenerative disorder with worldwide prevalence. Its clinical manifestation involves the presence of extracellular plaques and intracellular neurofibrillary tangles (NFTs). NFTs occur in brain tissues as a result of both Aβ agglomeration and Tau phosphorylation. Although there is no known cure for AD, research into possible cures and treatment options continues using cell-cultures and model animals/organisms. The nuclear factor-kappa β (NF-κβ) plays an active role in the progression of AD. Impairment to this signaling module triggers undesirable phenotypic changes such as neuroinflammation, activation of microglia, oxidative stress related complications, and apoptotic cell death. These imbalances further lead to homeostatic abnormalities in the brain or in initial stages of AD essentially pushing normal neurons toward the degeneration process. Interestingly, the role of NF-κβ signaling associated receptor-interacting protein kinase is currently observed in apoptotic and necrotic cell death, and has been reported in brains. Conversely, the NF-κβ signaling pathway has also been reported to be involved in normal brain functioning. This pathway plays a crucial role in maintaining synaptic plasticity and balancing between learning and memory. Since any impairment in the pathways associated with NF-κβ signaling causes altered neuronal dynamics, neurotherapeutics using compounds including, antioxidants, bioflavonoids, and non-steroidal anti-inflammatory drugs against such abnormalities offer possibilities to rectify aberrant excitatory neuronal activity in AD. In this review, we have provided an extensive overview of the crucial role of NF-κβ signaling in normal brain homeostasis. We have also thoroughly outlined several established pathomechanisms associated with NF-κβ pathways in AD, along with their respective therapeutic approaches.

Naloxone attenuates ischemic brain injury in rats through suppressing the NIK/IKKα/NF-κB and neuronal apoptotic pathways

Although naloxone has been documented to exert neuroprotection in animal model of cerebral ischemia, the mechanism is not well understood. In this present study we investigated whether naloxone affected the mitochondrial apoptotic pathway in ischemic brain injury of rats. SD rats were subjected to a permanent middle cerebral artery occlusion surgery, and received naloxone (0.5, 1, 2 mg/kg, i.v.) immediately after ischemia. Neurological deficits were evaluated 24 h after ischemia using the McGraw Stroke Index, and then the rats were killed, and the brains were collected for further analyses. We show that naloxone treatment dose-dependently decreased the infarction volume and morphological injury, improved motor behavioral function, and markedly curtailed brain edema. Furthermore, naloxone administration significantly inhibited the nuclear translocation of NF-κB p65 and decreased the levels of nuclear NF-κB p65 in the ischemic penumbra. Naloxone administration also dose-dependently increased the NF-κB inhibitory protein (IκBα) levels and attenuated phosphorylated NIK and IKKα levels in the ischemic penumbra. In addition, naloxone administration dose-dependently increased Bcl-2 levels, decreased Bax levels, stabilized the mitochondrial transmembrane potential, and inhibited cytochrome c release and caspase 3 and caspase 9 activation. These results indicate that the neuroprotective effects of naloxone against ischemic brain injury involve the inhibition of NF-κB activation via the suppression of the NIK/IKKα/IκBα pathway and the obstruction of the mitochondrial apoptotic pathway in neurons.

Effects of human umbilical cord blood CD34+ cell transplantation in neonatal hypoxic-ischemia rat model

Perinatal brain injury can cause death in the neonatal period and lifelong neurodevelopmental deficits. Stem cell transplantation had been proved to be effective approach to ameliorate neurological deficits after brain damage. In this study we examine the effect of human umbilical cord blood CD34⁺ cells on model of neonatal rat hypoxic-ischemic brain damage and compared the neuroprotection of transplantation of CD34⁺ cells to mononuclear cells from which CD34⁺ cells isolated on neonatal hypoxic-ischemia rat model. Seven-day-old Sprague-Dawley rats were subjected to hypoxic-ischemic (HI) injury, CD34⁺ cells (1.5 × 10⁴ cells) or mononuclear cells (1.0 × 10⁶ cells) were transplanted into mice by tail vein on the 7 day after HI. The transplantation of CD34⁺ cells significantly improved motor function of rat, and reduced cerebral atrophy, inhibited the expression of glial fibrillary acidic protein (GFAP) and apoptosis-related genes: TNF-α, TNFR1, TNFR2, CD40, Fas, and decreased the activation of Nuclear factor kappa B (NF-κB) in damaged brain. CD34⁺ cells treatment increased the expression of DCX and lectin in ipsilateral brain. Moreover, the transplantation of CD34⁺ cells and MNCs which were obtained from the same amount of human umbilical cord blood had similar effects on HI. Our data demonstrated that transplantation of human umbilical cord blood CD34+ cells can ameliorate the neural functional defect and reduce apoptosis and promote nerve and vascular regeneration in rat brain after HI injury and the effects of transplantation of CD34+ cells were comparable to that of MNCs in neonatal hypoxic-ischemia rat model.

Increased Active OMI/HTRA2 Serine Protease Displays a Positive Correlation with Cholinergic Alterations in the Alzheimer's Disease Brain

OMI/HTRA2 (high-temperature requirement serine protease A2) is a mitochondrial serine protease involved in several cellular processes, including autophagy, chaperone activity, and apoptosis. Few studies on the role of OMI/HTRA2 in Alzheimer's disease (AD) are available, but none on its relationship with the cholinergic system and neurotrophic factors as well as other AD-related proteins. In this study, immunohistochemical analyses revealed that AD patients had a higher cytosolic distribution of OMI/HTRA2 protein compared to controls. Quantitative analyses on brain extracts indicated a significant increase in the active form of OMI/HTRA2 in the AD brain. Activated OMI/HTRA2 protein positively correlated with stress-associated read-through acetylcholinesterase activity. In addition, α7 nicotinic acetylcholine receptor gene expression, a receptor also known to be localized on the outer membrane of mitochondria, showed a strong correlation with OMI/HTRA2 gene expression in three different brain regions. Interestingly, the activated OMI/HTRA2 levels also correlated with the activity of the acetylcholine-biosynthesizing enzyme, choline acetyltransferase (ChAT); with levels of the neurotrophic factors, NGF and BDNF; with levels of the soluble fragments of amyloid precursor protein (APP); and with gene expression of the microtubule-associated protein tau in the examined brain regions. Overall, the results demonstrate increased levels of the mitochondrial serine protease OMI/HTRA2, and a coherent pattern of association between the activated form of OMI/HTRA2 and several key proteins involved in AD pathology. In this paper, we propose a new hypothetical model to highlight the importance and needs of further investigation on the role of OMI/HTRA2 in the mitochondrial function and AD.

Nuclear expansion and pore opening are instant signs of neuronal hypoxia and can identify poorly fixed brains

The initial phase of neuronal death is not well characterized. Here, we show that expansion of the nuclear membrane without losing its integrity along with peripheralization of chromatin are immediate signs of neuronal injury. Importantly, these changes can be identified with commonly used nuclear stains and used as markers of poor perfusion-fixation. Although frozen sections are widely used, no markers are available to ensure that the observed changes were not confounded by perfusion-induced hypoxia/ischemia. Moreover, HMGB1 was immediately released and p53 translocated to mitochondria in hypoxic/ischemic neurons, whereas nuclear pore complex inhibitors prevented the nuclear changes, identifying novel neuroprotection targets.

Perinatal Hypoxic-Ischemic Encephalopathy and Neuroprotective Peptide Therapies: A Case for Cationic Arginine-Rich Peptides (CARPs)

Perinatal hypoxic-ischemic encephalopathy (HIE) is the leading cause of mortality and morbidity in neonates, with survivors suffering significant neurological sequelae including cerebral palsy, epilepsy, intellectual disability and autism spectrum disorders. While hypothermia is used clinically to reduce neurological injury following HIE, it is only used for term infants (>36 weeks gestation) in tertiary hospitals and improves outcomes in only 30% of patients. For these reasons, a more effective and easily administrable pharmacological therapeutic agent, that can be used in combination with hypothermia or alone when hypothermia cannot be applied, is urgently needed to treat pre-term (≤36 weeks gestation) and term infants suffering HIE. Several recent studies have demonstrated that cationic arginine-rich peptides (CARPs), which include many cell-penetrating peptides [CPPs; e.g., transactivator of transcription (TAT) and poly-arginine-9 (R9; 9-mer of arginine)], possess intrinsic neuroprotective properties. For example, we have demonstrated that poly-arginine-18 (R18; 18-mer of arginine) and its D-enantiomer (R18D) are neuroprotective in vitro following neuronal excitotoxicity, and in vivo following perinatal hypoxia-ischemia (HI). In this paper, we review studies that have used CARPs and other peptides, including putative neuroprotective peptides fused to TAT, in animal models of perinatal HIE. We critically evaluate the evidence that supports our hypothesis that CARP neuroprotection is mediated by peptide arginine content and positive charge and that CARPs represent a novel potential therapeutic for HIE.

Notch signaling and neuronal death in stroke

Ischemic stroke is a leading cause of morbidity and death, with the outcome largely determined by the amount of hypoxia-related neuronal death in the affected brain regions. Cerebral ischemia and hypoxia activate the Notch1 signaling pathway and four prominent interacting pathways (NF-κB, p53, HIF-1α and Pin1) that converge on a conserved DNA-associated nuclear multi-protein complex, which controls the expression of genes that can determine the fate of neurons. When neurons experience a moderate level of ischemic insult, the nuclear multi-protein complex up-regulates adaptive stress response genes encoding proteins that promote neuronal survival, but when ischemia is more severe the nuclear multi-protein complex induces genes encoding proteins that trigger and execute a neuronal death program. We propose that the nuclear multi-protein transcriptional complex is a molecular mediator of neuronal hormesis and a target for therapeutic intervention in stroke.

Vitexin protects against hypoxic-ischemic injury via inhibiting Ca2+/Calmodulin-dependent protein kinase II and apoptosis signaling in the neonatal mouse brain

Neonatal hypoxic-ischemic is a major cause of death and disability in neonates. In this study, we suggest for the first time that pretreatment with vitexin may suppress a pro-apoptotic signaling pathway in hypoxic-ischemic neuronal injury in neonates by inhibition of the phosphorylation of Ca²⁺/Calmodulin-dependent protein kinase II. Here we found that vitexin pretreatment reduced brain infarct volume in a dose-dependent manner. In addition, vitexin decreased the number of TUNEL-positive cells and brain atrophy. Furthermore, vitexin improved neurobehavioral outcomes. Vitexin also reduced oxygen glucose deprivation-induced neuronal injury and calcium entry. Vitexin pretreatment increased the Bcl-2/Bax protein ratio and decreased phosphorylation of Ca²⁺/Calmodulin-dependent protein kinase II and NF-κB, cleaved caspase-3 protein expression 24 hours after injury. Our data indicate that pretreatment with vitexin protects against neonatal hypoxic-ischemic brain injury and thus has potential as a treatment for hypoxic-ischemic brain injury.

Mitochondrial dynamics, mitophagy and biogenesis in neonatal hypoxic-ischaemic brain injury

Hypoxic-ischaemic encephalopathy, resulting from asphyxia during birth, affects 2-3 in every 1000 term infants and depending on severity, brings about life-changing neurological consequences or death. This hypoxic-ischaemia (HI) results in a delayed neural energy failure during which the majority of brain injury occurs. Currently, there are limited treatment options and additional therapies are urgently required. Mitochondrial dysfunction acts as a focal point in injury development in the immature brain. Not only do mitochondria become permeabilised, but recent findings implicate perturbations in mitochondrial dynamics (fission, fusion), mitophagy and biogenesis. Mitoprotective therapies may therefore offer a new avenue of intervention for babies who suffer lifelong disabilities due to birth asphyxia.

Oxidative stress diseases unique to the perinatal period: A window into the developing innate immune response

The innate immune system has evolved to play an integral role in the normally developing lung and brain. However, in response to oxidative stress, innate immunity, mediated by specific cellular and molecular programs and signaling, contributes to pathology in these same organ systems. Despite opposing drivers of oxidative stress, namely hyperoxia in neonatal lung injury and hypoxia/ischemia in neonatal brain injury, similar pathways-including toll-like receptors, NFκB and MAPK cascades-have been implicated in tissue damage. In this review, we consider recent insights into the innate immune response to oxidative stress in both neonatal and adult models to better understand hyperoxic lung injury and hypoxic-ischemic brain injury across development and aging. These insights support the development of targeted immunotherapeutic strategies to address the challenge of harnessing the innate immune system in oxidative stress diseases of the neonate.

Cell Death in the Developing Brain after Hypoxia-Ischemia

Perinatal insults such as hypoxia–ischemia induces secondary brain injury. In order to develop the next generation of neuroprotective therapies, we urgently need to understand the underlying molecular mechanisms leading to cell death. The cell death mechanisms have been shown to be quite different in the developing brain compared to that in the adult. The aim of this review is update on what cell death mechanisms that are operating particularly in the setting of the developing CNS. In response to mild stress stimuli a number of compensatory mechanisms will be activated, most often leading to cell survival. Moderate-to-severe insults trigger regulated cell death. Depending on several factors such as the metabolic situation, cell type, nature of the stress stimulus, and which intracellular organelle(s) are affected, the cell undergoes apoptosis (caspase activation) triggered by BAX dependent mitochondrial permeabilzation, necroptosis (mixed lineage kinase domain-like activation), necrosis (via opening of the mitochondrial permeability transition pore), autophagic cell death (autophagy/Na⁺, K⁺-ATPase), or parthanatos (poly(ADP-ribose) polymerase 1, apoptosis-inducing factor). Severe insults cause accidental cell death that cannot be modulated genetically or by pharmacologic means. However, accidental cell death leads to the release of factors (damage-associated molecular patterns) that initiate systemic effects, as well as inflammation and (regulated) secondary brain injury in neighboring tissue. Furthermore, if one mode of cell death is inhibited, another route may step in at least in a scenario when upstream damaging factors predominate over protective responses. The provision of alternative routes through which the cell undergoes death has to be taken into account in the hunt for novel brain protective strategies.

Effect of Trp53 gene deficiency on brain injury after neonatal hypoxia-ischemia

Hypoxia-ischemia (HI) can result in permanent life-long injuries such as motor and cognitive deficits. In response to cellular stressors such as hypoxia, tumor suppressor protein p53 is activated, potently initiating apoptosis and promoting Bax-dependent mitochondrial outer membrane permeabilization. The aim of this study was to investigate the effect of Trp53 genetic inhibition on injury development in the immature brain following HI. HI (50 min or 60 min) was induced at postnatal day 9 (PND9) in Trp53 heterozygote (het) and wild type (WT) mice. Utilizing Cre-LoxP technology, CaMK2α-Cre mice were bred with Trp53-Lox mice, resulting in knockdown of Trp53 in CaMK2α neurons. HI was induced at PND12 (50 min) and PND28 (40 min). Extent of brain injury was assessed 7 days following HI. Following 50 min HI at PND9, Trp53 het mice showed protection in the posterior hippocampus and thalamus. No difference was seen between WT or Trp53 het mice following a severe, 60 min HI. Cre-Lox mice that were subjected to HI at PND12 showed no difference in injury, however we determined that neuronal specific CaMK2α-Cre recombinase activity was strongly expressed by PND28. Concomitantly, Trp53 was reduced at 6 weeks of age in KO-Lox Trp53 mice. Cre-Lox mice subjected to HI at PND28 showed no significant difference in brain injury. These data suggest that p53 has a limited contribution to the development of injury in the immature/juvenile brain following HI. Further studies are required to determine the effect of p53 on downstream targets.

Haploinsufficiency in the mitochondrial protein CHCHD4 reduces brain injury in a mouse model of neonatal hypoxia-ischemia

Mitochondria contribute to neonatal hypoxic-ischemic brain injury by releasing potentially toxic proteins into the cytosol. CHCHD4 is a mitochondrial intermembrane space protein that plays a major role in the import of intermembrane proteins and physically interacts with apoptosis-inducing factor (AIF). The purpose of this study was to investigate the impact of CHCHD4 haploinsufficiency on mitochondrial function and brain injury after cerebral hypoxia-ischemia (HI) in neonatal mice. CHCHD4+/- and wild-type littermate mouse pups were subjected to unilateral cerebral HI on postnatal day 9. CHCHD4 haploinsufficiency reduced insult-related AIF and superoxide dismutase 2 release from the mitochondria and reduced neuronal cell death. The total brain injury volume was reduced by 21.5% at 3 days and by 31.3% at 4 weeks after HI in CHCHD4+/- mice. However, CHCHD4 haploinsufficiency had no influence on mitochondrial biogenesis, fusion, or fission; neural stem cell proliferation; or neural progenitor cell differentiation. There were no significant changes in the expression or distribution of p53 protein or p53 pathway-related genes under physiological conditions or after HI. These results suggest that CHCHD4 haploinsufficiency afforded persistent neuroprotection related to reduced release of mitochondrial intermembrane space proteins. The CHCHD4-dependent import pathway might thus be a potential therapeutic target for preventing or treating neonatal brain injury.

Time-lapse imaging of p65 and IκBα translocation kinetics following Ca2+-induced neuronal injury reveals biphasic translocation kinetics in surviving neurons

The transcription factor nuclear factor-κB (NF-κB) regulates neuronal differentiation, plasticity and survival. It is well established that excitatory neurotransmitters such as glutamate control NF-κB activity. Glutamate receptor overactivation is also involved in ischemic- and seizure-induced neuronal injury and neurodegeneration. However, little is known at the single cell-level how NF-κB signaling relates to neuronal survival during excitotoxic injury. We found that silencing of p65/NF-κB delayed N-methyl-d-aspartate (NMDA)-induced excitotoxic injury in hippocampal neurons, suggesting a functional role of p65 in excitotoxicity. Time-lapse imaging of p65 and its inhibitor IκBα using GFP and Cerulean fusion proteins revealed specific patterns of excitotoxic NF-κB activation. Nuclear translocation of p65 began on average 8±3min following 15min of NMDA treatment and was observed in up to two thirds of hippocampal neurons. Nuclear translocation of IκBα preceded that of p65 suggesting independent translocation processes. In surviving neurons, the onset of p65 nuclear export correlated with mitochondrial membrane potential recovery. Dying neurons exhibited persistent nuclear accumulation of p65-eGFP until plasma membrane permeabilization. Our data demonstrate an important role for p65 activation kinetics in neuronal cell death decisions following excitotoxic injury.

Positive effects of intermittent fasting in ischemic stroke

Intermittent fasting (IF) is a dietary protocol where energy restriction is induced by alternate periods of ad libitum feeding and fasting. Prophylactic intermittent fasting has been shown to extend lifespan and attenuate the progress and severity of age-related diseases such as cardiovascular (e.g. stroke and myocardial infarction), neurodegenerative (e.g. Alzheimer's disease and Parkinson's disease) and cancerous diseases in animal models. Stroke is the second leading cause of death, and lifestyle risk factors such as obesity and physical inactivity have been associated with elevated risks of stroke in humans. Recent studies have shown that prophylactic IF may mitigate tissue damage and neurological deficit following ischemic stroke by a mechanism(s) involving suppression of excitotoxicity, oxidative stress, inflammation and cell death pathways in animal stroke models. This review summarizes data supporting the potential hormesis mechanisms of prophylactic IF in animal models, and with a focus on findings from animal studies of prophylactic IF in stroke in our laboratory.

Post-traumatic administration of the p53 inactivator pifithrin-α oxygen analogue reduces hippocampal neuronal loss and improves cognitive deficits after experimental traumatic brain injury

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. Neuronal apoptosis in the hippocampus has been detected after TBI. The hippocampal dysfunction may result in cognitive deficits in learning, memory, and spatial information processing. Our previous studies demonstrated that a p53 inhibitor, pifithrin-α oxygen analogue (PFT-α (O)), significantly reduced cortical cell death, which is substantial following controlled cortical impact (CCI) TBI, and improved neurological functional outcomes via anti-apoptotic mechanisms. In the present study, we examined the effect of PFT-α (O) on CCI TBI-induced hippocampal cellular pathophysiology in light of this brain region's role in memory. To investigate whether p53-dependent apoptosis plays a role in hippocampal neuronal loss and associated cognitive deficits and to define underlying mechanisms, SD rats were subjected to experimental CCI TBI followed by the administration of PFT-α or PFT-α (O) (2mg/kg, i.v.) or vehicle at 5h after TBI. Magnetic resonance imaging (MRI) scans were acquired at 24h and 7days post-injury to assess evolving structural hippocampal damage. Fluoro-Jade C was used to stain hippocampal sub-regions, including CA1 and dentate gyrus (DG), for cellular degeneration. Neurological functions, including motor and recognition memory, were assessed by behavioral tests at 7days post injury. p53, p53 upregulated modulator of apoptosis (PUMA), 4-hydroxynonenal (4-HNE), cyclooxygenase-IV (COX IV), annexin V and NeuN were visualized by double immunofluorescence staining with cell-specific markers. Levels of mRNA encoding for caspase-3, p53, PUMA, Bcl-2, Bcl-2-associated X protein (BAX) and superoxide dismutase (SOD) were measured by RT-qPCR. Our results showed that post-injury administration of PFT-α and, particularly, PFT-α (O) at 5h dramatically reduced injury volumes in the ipsilateral hippocampus, improved motor outcomes, and ameliorated cognitive deficits at 7days after TBI, as evaluated by novel object recognition and open-field test. PFT-α and especially PFT-α (O) significantly reduced the number of FJC-positive cells in hippocampus CA1 and DG subregions, versus vehicle treatment, and significantly decreased caspase-3 and PUMA mRNA expression. PFT-α (O), but not PFT-α, treatment significantly lowered p53 and elevated SOD2 mRNA expression. Double immunofluorescence staining demonstrated that PFT-α (O) treatment decreased p53, annexin V and 4-HNE positive neurons in the hippocampal CA1 region. Furthermore, PUMA co-localization with the mitochondrial maker COX IV, and the upregulation of PUMA were inhibited by PFT-α (O) after TBI. Our data suggest that PFT-α and especially PFT-α (O) significantly reduce hippocampal neuronal degeneration, and ameliorate neurological and cognitive deficits in vivo via antiapoptotic and antioxidative properties.

Prevention of chemotherapy-induced peripheral neuropathy by the small-molecule inhibitor pifithrin-μ

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of cancer treatment. It is the most frequent cause of dose reduction or treatment discontinuation in patients treated for cancer with commonly used drugs including taxanes and platinum-based compounds. No FDA-approved treatments for CIPN are available. In rodents, CIPN is represented by peripheral mechanical allodynia in association with retraction of intraepidermal nerve fibers. The mechanism of chemotherapy-induced neurotoxicity is unclear, but it has been established that mitochondrial dysfunction is an important component of the dysregulation in peripheral sensory neurons. We have shown earlier that inhibition of mitochondrial p53 accumulation with the small compound pifithrin-μ (PFT-μ) prevents cerebral neuronal death in a rodent model of hypoxic-ischemic brain damage. We now explore whether PFT-μ is capable of preventing neuronal mitochondrial damage and CIPN in mice. We demonstrate for the first time that PFT-μ prevents both paclitaxel- and cisplatin-induced mechanical allodynia. Electron microscopic analysis of peripheral sensory nerves revealed that PFT-μ secured mitochondrial integrity in paclitaxel-treated mice. In addition, PFT-μ administration protects against chemotherapy-induced loss of intraepidermal nerve fibers in the paw. To determine whether neuroprotective treatment with PFT-μ would interfere with the antitumor effects of chemotherapy, ovarian tumor cells were cultured in vitro with PFT-μ and paclitaxel. Pifithrin-μ does not inhibit tumor cell death but even enhances paclitaxel-induced tumor cell death. These data are the first to identify PFT-μ as a potential therapeutic strategy for prevention of CIPN to combat one of the most devastating side effects of chemotherapy.

Protein methionine oxidation augments reperfusion injury in acute ischemic stroke

Reperfusion injury can exacerbate tissue damage in ischemic stroke, but little is known about the mechanisms linking ROS to stroke severity. Here, we tested the hypothesis that protein methionine oxidation potentiates NF-κB activation and contributes to cerebral ischemia/reperfusion injury. We found that overexpression of methionine sulfoxide reductase A (MsrA), an antioxidant enzyme that reverses protein methionine oxidation, attenuated ROS-augmented NF-κB activation in endothelial cells, in part, by protecting against the oxidation of methionine residues in the regulatory domain of calcium/calmodulin-dependent protein kinase II (CaMKII). In a murine model, MsrA deficiency resulted in increased NF-κB activation and neutrophil infiltration, larger infarct volumes, and more severe neurological impairment after transient cerebral ischemia/reperfusion injury. This phenotype was prevented by inhibition of NF-κB or CaMKII. MsrA-deficient mice also exhibited enhanced leukocyte rolling and upregulation of E-selectin, an endothelial NF-κB-dependent adhesion molecule known to contribute to neurovascular inflammation in ischemic stroke. Finally, bone marrow transplantation experiments demonstrated that the neuroprotective effect was mediated by MsrA expressed in nonhematopoietic cells. These findings suggest that protein methionine oxidation in nonmyeloid cells is a key mechanism of postischemic oxidative injury mediated by NF-κB activation, leading to neutrophil recruitment and neurovascular inflammation in acute ischemic stroke.

Drugs for neuroprotection after birth asphyxia: Pharmacologic adjuncts to hypothermia

An adverse outcome is still encountered in 45% of full-term neonates with perinatal asphyxia who are treated with moderate hypothermia. At present pharmacologic therapies are developed to be added to hypothermia. In the present article, these potential neuroprotective interventions are described based on the molecular pathways set in motion during fetal hypoxia and following reoxygenation and reperfusion after birth. These pathways include excessive production of excitotoxins with subsequent over-stimulation of NMDA receptors and calcium influx in neuronal cells, excessive production of reactive oxygen and nitrogen species, activation of inflammation leading to inappropriate apoptosis, and loss of neurotrophic factors. Possibilities for pharmacologic combination therapy, where each drug will be administered based on the optimal point of time in the cascade of destructive molecular reactions, may further reduce brain damage due to perinatal asphyxia.

Pretreatment of Mouse Neural Stem Cells with Carbon Monoxide-Releasing Molecule-2 Interferes with NF-κB p65 Signaling and Suppresses Iron Overload-Induced Apoptosis

Neural stem cell (NSC) transplantation is a promising approach to repair the damaged brain after hemorrhagic stroke; however, it is largely limited by the poor survival of donor cells. Breakdown products of the hematoma and subsequent iron overload contribute to the impairment of survival of neural cells. There is little information regarding the mechanism involved in the death of grafted cells. Furthermore, therapeutic research targeted to improving the survival of grafted neural stem cells (NSCs) is strikingly lacking. Here, we showed that iron overload induced apoptosis of C17.2 cells, a cell line originally cloned from mouse NSCs and immortalized by v-myc. Pretreatment with carbon monoxide-releasing molecule-2 (CORM-2) markedly protected C17.2 cells against iron overload in a dose-dependent manner. Moreover, CORM-2 interfered with NF-κB signaling, including inhibition of nuclear translocation and down-regulation of NF-κB p65. TUNEL staining showed that preconditioning C17.2 cells with CORM-2 enhanced their resistance to apoptosis induced by iron overload, which was concomitant with down-regulation of the pro-apoptotic proteins (Bax and cleaved caspase-3) and up-regulation of the anti-apoptotic protein Bcl2. The protective effect of CORM-2 could be simulated by BAY11-7082, a special inhibitor of NF-κB p65. These results provide a novel and effective strategy to enhance the survival of NSCs after transplantation and, therefore, their efficacy in repairing brain injury due to hemorrhagic stroke.

Effects of the Combination of the Main Active Components of Astragalus and Panax notoginseng on Inflammation and Apoptosis of Nerve Cell after Cerebral Ischemia-Reperfusion

Astragalus and Panax notoginseng are commonly used to treat cardio-cerebrovascular diseases in China and are often combined together to promote curative effect. We speculate that the enhancement of the combination on anticerebral ischemia injury may come from the main active components. The purpose of this work was to probe the effects and mechanisms of Astragaloside IV (the active component of Astragalus) combined with Ginsenoside Rg1, Ginsenoside Rb1, and Notoginsenoside R1 (the active components of P. notoginseng) to antagonize ischemia/reperfusion (I/R) injury via inflammation and apoptosis. C57BL/6 mice were randomly divided into sham, model, Astragaloside IV, Ginsenoside Rg1, Ginsenoside Rb1, Notoginsenoside R1, four active components combination, and Edaravone groups. After administration for 3 days, bilateral common carotid arteries (CCA) were occluded with artery clip for 20[Formula: see text]min followed by reperfusion for 24[Formula: see text]h. Our results showed that the survival rate of nerve cell in hippocampal CA1 decreased while the apoptotic rate increased, and the level of caspase-3 protein in brain tissues was elevated, the expressions of TNF-a, IL-1, and ICAM-1 mRNA as well as phosphorylated nuclear factor kappa B (NF-[Formula: see text]B) inhibitor protein [Formula: see text] (p-I[Formula: see text]Ba) in brain tissues were up-regulated, and the nuclear translocation rate of NF-[Formula: see text]B was raised. Additionally, the protein expressions of phosphorylated tyrosine kinase 1 (p-JAK1), phosphorylated signal transducer and activator of transcription-1 (p-STAT1), glucose regulated protein 78 (GRP78), caspase-12, and phosphorylated c-Jun N-terminal kinases 1/2 (p-JNK1/2) in brain tissues were also significantly strengthened after I/R for 24[Formula: see text]h. All drugs could increase neurocyte survival rate in hippocampal CA1, decrease the apoptotic rate, and inhibit caspase-3 protein expression, in contrast, the effects of four active components combination were better than those of active components alone. In addition, Astragaloside IV and Ginsenoside Rg1 could down-regulate the level of TNF-[Formula: see text], and ICAM-1 mRNA, respectively, Notoginsenoside R1 reduced both TNF-[Formula: see text] and ICAM-1 mRNA, and the combination of the 4 effective components had inhibitory effects on the expressions of TNF-[Formula: see text], IL-1[Formula: see text], and ICAM-1 mRNA. Astragaloside IV, Ginsenoside Rg1, Notoginsenoside R1, and 4 effective components combination were able to restrain the phosphorylation of I[Formula: see text]B[Formula: see text], and relieve the nuclear translocation rate of NF-[Formula: see text]B. Moreover, the effects of the combination are greater than those of active components alone. All drugs could suppress the phosphorylation of JAK1 induced by I/R; meanwhile the expression of p-STAT1 exhibited a decrease in Ginsenoside Rg1 and four active components combination groups. The decreases of p-JAK1 and p-STAT1 in the four active components combination group were more obvious than those in active components alone groups. Astragaloside IV, Ginsenoside Rg1, and Notoginsenoside R1 further augmented GRP78 expression caused by I/R, Notoginsenoside R1 attenuated caspase-12 protein expression, Astragaloside IV and Ginsenoside Rg1 lessened the phosphorylation of JNK1/2, and the four active components combination was capable of up-regulating GRP78 protein while down-regulating the expressions of caspase-12 and p-JNK1/2. Similarly, the effects of the four active components combination were greater than those of effective components alone. These suggested that the combination of the main active components of Astragalus and Panax notoginseng could strengthen protective effects on cerebral ischemia injury via anti-apoptosis and anti-inflammation, and the mechanisms might be associated with restraining the activation of NF-[Formula: see text]B and JAK1/STAT1 signal pathways and regulating endoplasmic reticulum stress (ERS) after cerebral ischemia.

The Blockade of NF-κB Activation by a Specific Inhibitory Peptide Has a Strong Neuroprotective Role in a Sprague-Dawley Rat Kernicterus Model

Kernicterus, the permanent nerve damage occurring as a result of bilirubin precipitation, still occurs worldwide and may lead to death or permanent neurological impairments. However, the underlying mechanisms remain unclear, and effective therapeutic strategies are lacking. The present study aims to investigate the activation of NF-κB and to identify the effect of NF-κB inhibition on the newborn rat kernicterus model. The NF-κB essential modifier-binding domain peptide (NBD), coupled with the HIV trans-activator of transcription peptide (TAT) was used to inhibit NF-κB. NF-κB was significantly activated in the cerebrum at 1 and 3 h (p < 0.05) after the model was established, as measured by EMSA. NF-κB activation was inhibited by intraperitoneal administration of TAT-NBD. The general conditions of the TAT-NBD-treated rats were improved; meanwhile, these rats performed much better on the neurological evaluation, the rotarod test, and the Morris water maze test (p < 0.05) than the vehicle-treated rats at 28 days. Furthermore, the morphology of the nerve cells was better preserved in the TAT-NBD group, and these cells displayed less neurodegeneration and astrocytosis. Simultaneously, apoptosis in the brain was attenuated, and the levels of the TNF-α and IL-1β proteins were decreased (p < 0.01). These results suggested that NF-κB was activated, and inhibition of NF-κB activation by TAT-NBD not only attenuated the acute neurotoxicity, apoptosis, and inflammation, but also improved the long term neurobehavioral impairments in the kernicterus model rats in vivo. Thus, inhibiting NF-κB activation might be a potential therapeutic approach for kernicterus.

Neuroprotective agents for neonatal hypoxic-ischemic brain injury

Hypoxic-ischemic (H-I) brain injury in newborns is a major cause of morbidity and mortality that claims thousands of lives each year. In this review, we summarize the promising neuroprotective agents tested on animal models and pilot clinical studies of neonatal H-I brain injury according to the different phases of the disease. These agents target various phases of injury including the early phase of excitotoxicity, oxidative stress and apoptosis as well as late-phase inflammatory reaction and neural repair. We analyze the cell survival and cell death pathways modified by these agents in neonatal H-I brain injury. We aim to 'build a bridge' between animal trials of neuroprotective agents and potential candidate treatments for future clinical applications against H-I encephalopathy.

NF-κB Signaling is Involved in the Effects of Intranasally Engrafted Human Neural Stem Cells on Neurofunctional Improvements in Neonatal Rat Hypoxic-Ischemic Encephalopathy

AIM

Hypoxic-ischemic encephalopathy (HIE) is a common neurological disease in infants with persistent neurobehavioral impairments. Studies found that neural stem cell (NSC) therapy benefits HIE rats; however, the mechanisms underlying are still unclear. The current study investigated the efficacy and molecular events of human embryonic neural stem cells (hNSCs) in neonatal hypoxic-ischemic (HI) rats.

METHODS

PKH-26-labeled hNSCs were intranasally delivered to P7 Sprague Dawley rats 24 h after HI. Neurobehavioral tests were performed at the indicated time after delivery: righting reflex and gait testing at D1, 3, 5, and 7; grid walking at D7 and 14; social choice test (SCT) at D28; and Morris water maze from D35 to 40. Protein expression was determined by Western blot analysis. Brain damage was assessed by cresyl violet staining and MBP staining. hNSC distribution and differentiation were observed by in vivo bioluminescence imaging and immunofluorescence staining.

RESULTS

(1) hNSCs migrated extensively into brain areas within 24 h after the delivery, survived even at D42 with the majority in ipsi-hemisphere, and could be co-labeled with NeuN or GFAP. (2) hNSCs reduced the upregulation in cytosolic IL-1β, p-IκBα, and NF-κB p65 levels, whereas enhanced nuclear p65 expression in HI rats at D3 after the delivery. (3) hNSCs decreased HI-induced brain tissue loss and white matter injury at D42 after the delivery. (4) hNSCs improved neurological outcomes in HI rats in the tests of righting reflex (within 3 days), gait (D5), grid (D7), SCT (D28), and water maze (D42).

CONCLUSION

Intranasal delivery of hNSCs could prevent HI-induced brain injury and improve neurobehavioral outcomes in neonatal HI rats, which is possibly related to the modulation of NF-κB signaling.

Pathophysiology and neuroprotection of global and focal perinatal brain injury: lessons from animal models

BACKGROUND

Arterial ischemic stroke occurs more frequently in term newborns than in the elderly, and brain immaturity affects mechanisms of ischemic injury and recovery. The susceptibility to injury of the brain was assumed to be lower in the perinatal period as compared with childhood. This concept was recently challenged by clinical studies showing marked motor disabilities after stroke in neonates, with the severity of motor and cortical sensory deficits similar in both perinatal and childhood ischemic stroke. Our understanding of the triggers and the pathophysiological mechanisms of perinatal stroke has greatly improved in recent years, but many factors remain incompletely understood.

METHODS

In this review, we focus on the pathophysiology of perinatal stroke and on therapeutic strategies that can protect the immature brain from the consequences of stroke by targeting inflammation and brain microenvironment.

RESULTS

Studies in neonatal rodent models of cerebral ischemia have suggested a potential role for soluble inflammatory molecules as important modulators of injury and recovery. A great effort is underway to investigate neuroprotective molecules based on our increasing understanding of the pathophysiology.

CONCLUSION

In this review, we provide a comprehensive summary of new insights concerning pathophysiology of focal and global perinatal brain injury and their implications for new therapeutic approaches.

The role of inflammation in perinatal brain injury

Inflammation is increasingly recognized as being a critical contributor to both normal development and injury outcome in the immature brain. The focus of this Review is to highlight important differences in innate and adaptive immunity in immature versus adult brain, which support the notion that the consequences of inflammation will be entirely different depending on context and stage of CNS development. Perinatal brain injury can result from neonatal encephalopathy and perinatal arterial ischaemic stroke, usually at term, but also in preterm infants. Inflammation occurs before, during and after brain injury at term, and modulates vulnerability to and development of brain injury. Preterm birth, on the other hand, is often a result of exposure to inflammation at a very early developmental phase, which affects the brain not only during fetal life, but also over a protracted period of postnatal life in a neonatal intensive care setting, influencing critical phases of myelination and cortical plasticity. Neuroinflammation during the perinatal period can increase the risk of neurological and neuropsychiatric disease throughout childhood and adulthood, and is, therefore, of concern to the broader group of physicians who care for these individuals.

Inflammation-induced sensitization of the brain in term infants

Perinatal insults are a leading cause of infant mortality and amongst survivors are frequently associated with neurocognitive impairment, cerebral palsy (CP), and seizure disorders. The events leading to perinatal brain injury are multifactorial. This review describes how one subinjurious factor affecting the brain sensitizes it to a second injurious factor, causing an exacerbated injurious cascade. We will review the clinical and experimental evidence, including observations of high rates of maternal and fetal infections in term-born infants with neonatal encephalopathy and cerebral palsy. In addition, we will discuss preclinical evidence for the sensitizing effects of inflammation on injuries, such as hypoxia-ischaemia, our current understanding of the mechanisms underpinning the sensitization process, and the possibility for neuroprotection.

The neonatal brain is not protected by osteopontin peptide treatment after hypoxia-ischemia

Neonatal encephalopathy due to perinatal hypoxia-ischemia (HI) is a severe condition, and current treatment options are limited. Expression of endogenous osteopontin (OPN), a multifunction glycoprotein, is strongly upregulated in the brain after neonatal HI. Intracerebrally administered OPN has been shown to be neuroprotective following experimental neonatal HI and adult stroke. In the present study, we determined whether intranasal, intraperitoneal or intracerebral treatment with a smaller TAT-OPN peptide is neuroprotective in neonatal mice with HI brain damage. The TAT-OPN peptide exerts bioactivity as it was as potent as full-length OPN in inducing cell adhesion in an in vitro adhesion assay. Intranasal administration of TAT-OPN peptide immediately after HI (T0) or in a repetitive treatment schedule of T0, 3 h, day (D) 1, 2 and 3 after HI did not protect cerebral gray or white matter after HI. Intraperitoneal TAT-OPN treatment at T0 or in two extended treatment schedules (D5, 7, 9, 11, 13, 15 after HI or T0, D1, 3, 5, 7, 9, 11, 13 and 15 after HI) did not result in neuroprotection either. Moreover, no functional improvement (cylinder rearing test and adhesive removal task) was observed following TAT-OPN treatment in any of the intraperitoneal treatment schedules. We validated that the TAT-OPN peptide reached the brain after intranasal or intraperitoneal administration by using an HIV-TAT staining. Finally, also intracerebral administration of the TAT-OPN peptide 1 h after HI did not reduce cerebral damage. Our data show that administration of the TAT-OPN peptide did not exert neuroprotective effects on neonatal HI-induced brain injury or sensorimotor behavioral deficits.

CpG preconditioning regulates miRNA expression that modulates genomic reprogramming associated with neuroprotection against ischemic injury

Cytosine-phosphate-guanine (CpG) preconditioning reprograms the genomic response to stroke to protect the brain against ischemic injury. The mechanisms underlying genomic reprogramming are incompletely understood. MicroRNAs (miRNAs) regulate gene expression; however, their role in modulating gene responses produced by CpG preconditioning is unknown. We evaluated brain miRNA expression in response to CpG preconditioning before and after stroke using microarray. Importantly, we have data from previous gene microarrays under the same conditions, which allowed integration of miRNA and gene expression data to specifically identify regulated miRNA gene targets. CpG preconditioning did not significantly alter miRNA expression before stroke, indicating that miRNA regulation is not critical for the initiation of preconditioning-induced neuroprotection. However, after stroke, differentially regulated miRNAs between CpG- and saline-treated animals associated with the upregulation of several neuroprotective genes, implicating these miRNAs in genomic reprogramming that increases neuroprotection. Statistical analysis revealed that the miRNA targets were enriched in the gene population regulated in the setting of stroke, implying that miRNAs likely orchestrate this gene expression. These data suggest that miRNAs regulate endogenous responses to stroke and that manipulation of these miRNAs may have the potential to acutely activate novel neuroprotective processes that reduce damage.

New antioxidant drugs for neonatal brain injury

The brain injury concept covers a lot of heterogeneity in terms of aetiology involving multiple factors, genetic, hemodynamic, metabolic, nutritional, endocrinological, toxic, and infectious mechanisms, acting in antenatal or postnatal period. Increased vulnerability of the immature brain to oxidative stress is documented because of the limited capacity of antioxidant enzymes and the high free radicals (FRs) generation in rapidly growing tissue. FRs impair transmembrane enzyme Na⁺/K⁺-ATPase activity resulting in persistent membrane depolarization and excessive release of FR and excitatory aminoacid glutamate. Besides being neurotoxic, glutamate is also toxic to oligodendroglia, via FR effects. Neuronal cells die of oxidative stress. Excess of free iron and deficient iron/binding metabolising capacity are additional features favouring oxidative stress in newborn. Each step in the oxidative injury cascade has become a potential target for neuroprotective intervention. The administration of antioxidants for suspected or proven brain injury is still not accepted for clinical use due to uncertain beneficial effects when treatments are started after resuscitation of an asphyxiated newborn. The challenge for the future is the early identification of high-risk babies to target a safe and not toxic antioxidant therapy in combination with standard therapies to prevent brain injury and long-term neurodevelopmental impairment.

Unique brain region-dependent cytokine signatures after prolonged hypothermic cardiac arrest in rats

We previously showed that prolonged cardiac arrest (CA) produces neuronal death with microglial proliferation. Microglial proliferation, but not neuronal death, was attenuated by deeper hypothermia. Microglia are reportedly a major source of cytokines. In this study, we tested the hypotheses that (1) CA will result in highly specific regional and temporal increases in brain cytokines; and (2) these increases will be attenuated by deep hypothermia. Adult male Sprague-Dawley rats were subjected to rapid exsanguination. After 6 minutes of normothermic no-flow, different levels of hypothermia were induced by either ice-cold (IC) or room-temperature (RT) aortic flush. After 20 minutes CA, rats were resuscitated with cardiopulmonary bypass (CPB), and sacrificed at 6 or 24 hours. Rats subjected to CPB only (without CA) and shams (no CPB or CA) served as controls (n=6 per group). Cytokines were analyzed in cerebellum, cortex, hippocampus, and striatum. Immunofluorescence was used to identify cell types associated with individual cytokines. Intra-CA temperature was lower after IC versus RT flush (21°C vs. 28°C, p<0.05). At 6 hours, striatum showed a massive increase in interleukin (IL)-1α and tumor necrosis factor-alpha (TNF-α) (>100-fold higher than in hippocampus), which was attenuated by deeper hypothermia in the IC versus RT group. In contrast, IL-12 was 50-fold higher in hippocampus versus striatum. At 24 hours, cytokines decreased. In striatum, IL-1α colocalized with astrocytes while TNF-α colocalized with neurons. In hippocampus, IL-12 colocalized with hippocampal hilar neurons, the only region where neuronal degeneration was observed at 24 hours at both IC and RT groups. We report important temporo-spatial differences in the brain cytokine response to hypothermic CA, with a novel role of striatum. Astrocytes and neurons, but not microglia colocalized with individual cytokines. Hypothermia showed protective effects. These neuroinflammatory reactions precede neuronal death. New therapeutic strategies may need to target early regional neuroinflammation.

An active component of Achyranthes bidentata polypeptides provides neuroprotection through inhibition of mitochondrial-dependent apoptotic pathway in cultured neurons and in animal models of cerebral ischemia

An active component has been isolated by reverse-phase high performance liquid chromatography (HPLC) from Achyranthes bidentata Blume polypeptides that are extracted from Achyranthes bidentata Blume, a Chinese medicinal herb. The active component is called ABPPk based on the order of HPLC elution. In this study, we used in vitro and in vivo experimental models of cerebral ischemia to investigate the possible neuroprotective effect of ABPPk. ABPPk treatment promoted neuronal survival and inhibited neuronal apoptosis in primary cortical neurons exposed to oxygen and glucose deprivation and in rats subjected to transient middle cerebral artery occlusion. The role of ABPPk in protection against ischemia-induced neuronal damage might be mediated by mitochondrial-dependent pathways, including modulation of apoptosis-related gene expression, regulation of mitochondrial dysfunction through restoring mitochondrial membrane potential, reducing release of mitochondrial apoptogenic factors, and inhibiting intracellular ROS production. The neuroprotective effect of ABPPk may suggest the possible use of this agent in the treatment and prevention of cerebral ischemic stroke.

Penetrating the cell membrane, thermal targeting and novel anticancer drugs: the development of thermally targeted, elastin-like polypeptide cancer therapeutics

Therapeutic peptides offer important cancer treatment approaches. Designed to inhibit oncogenes and other oncoproteins, early therapeutic peptides applications were hampered by pharmacokinetic properties now addressed through tumor targeting strategies. Active targeting with environmentally responsive biopolymers or macromolecules enhances therapeutics accumulation at tumor sites; passive targeting with macromolecules, or liposomes, exploits angiogenesis and poor lymphatic drainage to preferentially accumulate therapeutics within tumors. Genetically engineered, thermally-responsive, elastin-like polypeptides use both strategies and cell-penetrating peptides to further intratumoral cell uptake. This review describes the development and application of cell-penetrating peptide-elastin-like polypeptide therapeutics for the thermally targeted delivery of therapeutic peptides.

Intranasal delivery of a peptide with antidepressant-like effect

A critical issue in drug development is developing effective, noninvasive delivery routes to the central nervous system (CNS). Major depressive disorder (MDD) is an illness associated with significant morbidity. Even with multiple antidepressant trials, 10-15% of patients continue to experience persistent depressive symptoms. We previously developed an interfering peptide that has antidepressant-like effects in rats when injected directly into the brain. To be clinically viable, it must demonstrate efficacy via a noninvasive administration route. We report here that the interfering peptide designed to disrupt the interaction between the D1 and D2 dopamine receptors can be delivered to relevant brain areas using the Pressurized Olfactory Device (POD), a novel intranasal delivery system developed by Impel NeuroPharma. We validate this delivery method by demonstrating that, at doses ⩾1.67 nmol/g, the D1-D2 interfering peptide has a significant antidepressant-like effect comparable to that of imipramine in the forced swimming test (FST), a common test for antidepressant efficacy. The antidepressant-like effect of the interfering peptide can be detected for 2 h after intranasal administration. Furthermore, we show that the interfering peptide disrupts the D1-D2 interaction and it can be detected in the prefrontal cortex after intranasal administration. This study provides strong preclinical support for intranasal administration of the D1-D2 interfering peptide as a new treatment option for patients suffering from MDD.