Combining Normobaric Oxygen with Ethanol or Hypothermia Prevents Brain Damage from Thromboembolic Stroke via PKC-Akt-NOX Modulation

The BE COOL Treatments (Batroxobin, oxygEn, Conditioning, and cOOLing): Emerging Adjunct Therapies for Ischemic Cerebrovascular Disease

Ischemic cerebrovascular disease (ICD), the most common neurological disease worldwide, can be classified based on the onset time (acute/chronic) and the type of cerebral blood vessel involved (artery or venous sinus). Classifications include acute ischemic stroke (AIS)/transient ischemic attack (TIA), chronic cerebral circulation insufficiency (CCCI), acute cerebral venous sinus thrombosis (CVST), and chronic cerebrospinal venous insufficiency (CCSVI). The pathogenesis of cerebral arterial ischemia may be correlated with cerebral venous ischemia through decreased cerebral perfusion. The core treatment goals for both arterial and venous ICDs include perfusion recovery, reduction of cerebral ischemic injury, and preservation of the neuronal integrity of the involved region as soon as possible; however, therapy based on the current guidelines for either acute ischemic events or chronic cerebral ischemia is not ideal because the recurrence rate of AIS or CVST is still very high. Therefore, this review discusses the neuroprotective effects of four novel potential ICD treatments with high translation rates, known as the BE COOL treatments (Batroxobin, oxygEn, Conditioning, and cOOLing), and subsequently analyzes how BE COOL treatments are used in clinical settings. The combination of batroxobin, oxygen, conditioning, and cooling may be a promising intervention for preserving ischemic tissues.

Improvement of synaptic plasticity by nanoparticles and the related mechanisms: Applications and prospects

Synaptic plasticity is an important basis of learning and memory and participates in brain network remodelling after different types of brain injury (such as that caused by neurodegenerative diseases, cerebral ischaemic injury, posttraumatic stress disorder (PTSD), and psychiatric disorders). Therefore, improving synaptic plasticity is particularly important for the treatment of nervous system-related diseases. With the rapid development of nanotechnology, increasing evidence has shown that nanoparticles (NPs) can cross the blood-brain barrier (BBB) in different ways, directly or indirectly act on nerve cells, regulate synaptic plasticity, and ultimately improve nerve function. Therefore, to better elucidate the effect of NPs on synaptic plasticity, we review evidence showing that NPs can improve synaptic plasticity by regulating different influencing factors, such as neurotransmitters, receptors, presynaptic membrane proteins and postsynaptic membrane proteins, and further discuss the possible mechanism by which NPs improve synaptic plasticity. We conclude that NPs can improve synaptic plasticity and restore the function of damaged nerves by inhibiting neuroinflammation and oxidative stress, inducing autophagy, and regulating ion channels on the cell membrane. By reviewing the mechanism by which NPs regulate synaptic plasticity and the applications of NPs for the treatment of neurological diseases, we also propose directions for future research in this field and provide an important reference for follow-up research.

Nanomedicines, an emerging therapeutic regimen for treatment of ischemic cerebral stroke: A review

Owing to its intricate pathophysiology, cerebral stroke is a serious medical condition caused by interruption or obstruction of blood supply (blockage of vasculature) to the brain tissues which results in diminished supply of essential nutrients and oxygen (hypoxia) and ultimate necrosis of neuronal tissues. A prompt risks assessment and immediate rational therapeutic plan with proficient neuroprotection play critically important role in the effective management of this neuronal emergency. Various conventional medications are being used for treatment of acute ischemic cerebral stroke but fibrinolytic agents, alone or in combination with other agents are considered the mainstay. These clot-busting agents effectively restore blood supply (reperfusion) to ischemic regions of the brain; however, their clinical significance is hampered due to various factors such as short plasma half-life, limited distribution to brain tissues due to the presence of highly efficient physiological barrier, blood brain barrier (BBB), and lacking of target-specific delivery to the ischemic brain regions. To alleviate these issues, various types of nanomedicines such as polymeric nanoparticles (NPs), liposomes, nanoemulsion, micelles and dendrimers have been designed and evaluated. The implication of these newer therapies (nanomedicines) have revolutionized the therapeutic outcomes by improving the plasma half-life, permeation across BBB, efficient distribution to ischemic cerebral tissues and neuroprotection. Furthermore, the adaptation of some diverse techniques including PEGylation, tethering of targeting ligands on the surfaces of nanomedicines, and pH responsive features have also been pondered. The implication of these emerging adaptations have shown remarkable potential in maximizing the targeting efficiency of drugs to ischemic brain tissues, simultaneous delivery of drugs and imaging agents (for early prognosis as well as monitoring of therapy), and therapeutic outcomes such as long-term neuroprotection.

Icariin enhance mild hypothermia-induced neuroprotection via inhibiting the activation of NF-κB in experimental ischemic stroke

Therapeutic hypothermia (TH) is a promising neuroprotective agent for treating stroke. However, its clinical application was limited by the impractical duration. Icariin (ICA) were reported to have therapeutic effect on cerebral ischemia. In this research, our aim was to investigate whether the combination of TH and ICA had better neuroprotective effects on ischemic stroke. An ischemia-reperfusion rat model was established and treated with mild hypothermia, ICA or JSH-23 (inhibitor of NF-κB). Thermistor probe, 2'3'5'-triphenyl tetrazolium chloride (TTC), 5/12-score system, and ELISA were used to detect temperature (rectum, cortex, striatum), infarct volume, neurological deficit, and cerebral cell death of these rats. The expressions of tumor necrosis factor (TNF)-α, Interleukin- 6 (IL-6), nuclear factor-kappa B (NF-κB), nuclear factor erythroid2-related factor (Nrf2), peroxisome proliferator activated receptor gamma (PPARα), PPARγ, Janus kinase 2 (JAK2), p-JAK2, signal transducers and activators of transduction-3 (STAT3), and p-STAT3 were detected by Western blot or q-PCR. Mild hypothermia, ICA, and JSH-23 reduced the cerebral infarct volume, neurological deficit, cerebral cell death of rats, downregulated the expressions of TNF-α, IL-6, C-Caspase 3 and Bax, and the activation of PPARs/Nrf2/NF-κB and JAK2/STAT3 pathways, but elevated the expression of Bcl-2. ICA promoted the effect of mild hypothermia on infarct volume, neurological deficit, and cerebral cell death. Moreover, ICA also enhanced the regulatory effect of mild hypothermia on apoptosis/inflammation factors expressions and activation of PPARs/Nrf2/NF-κB and JAK2/STAT3 pathways. ICA could promote mild hypothermia-induced neuroprotection by inhibiting the activation of NF-κB through the PPARs/Nrf2/NF-κB and JAK2/STAT3/NF-κB pathways in experimental stroke.

Enhanced Cerebral Microbleeds by Long-Term Air Pollution Exposure in Spontaneously Hypertensive Rats

BACKGROUND

Cerebral microbleeds (CMBs) are associated with a high risk for stroke . The present study determined whether long-term exposure to PM2.5 results in progressive worsening of CMBs and induction of systemic inflammation and microvascular oxidative stress.

METHODS

Sixteen male Spontaneously hypertensive rats (SHR) and eight Wistar-Kyoto (WKY) rats were exposed to either filtered air or PM2.5 for 12 months. To detect CMBs, rats were imaged using a 7-T MRI. To determine systemic inflammation and oxidative stress, interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), monocyte chemoattractant protein-1 (MCP-1), as well as reactive oxygen species (ROS), NADPH activity and its subunits p22/47/67phox & gp91phox were measured.

RESULTS

During the exposure period, the mean daily concentration of PM2.5 was 59.2 ± 1.0 μg/m³. PM2.5 exposure significantly increased the incidence of CMBs compared to the PM2.5 (-) group (37.5% vs 12.5% incidence rate, p < 0.001). Animals exposed to PM2.5 also had significantly increased systolic blood pressures (SBPs) at 3 months (173 ± 5 vs 157 ± 5 mmHg, p < 0.05), 6 months (218 ± 6 vs 193 ± 7 mmHg, p < 0.01), 9 months (222 ± 6 vs 203 ± 8 mmHg, p < 0.05), and 12 months (231 ± 4 vs 207 ± 5 mmHg, p = 0.01). Additionally, there were significant elevations in IL-6, MCP-1, and TNF-α in the exposed group. Furthermore, PM2.5 significantly increased NOX activity and protein levels of gp91phox and p22/47/67phox.

CONCLUSION

In the SHR model, long-term exposure to PM2.5 worsened CMBs, increased SBPs, induced systemic inflammation and oxidative stress. Therefore, PM2.5 is potentially a controllable risk factor that promotes CMBs in certain patients, such as those with hypertension.

Mechanisms of disease-modifying effect of saracatinib (AZD0530), a Src/Fyn tyrosine kinase inhibitor, in the rat kainate model of temporal lobe epilepsy

We have recently demonstrated the role of the Fyn-PKCδ signaling pathway in status epilepticus (SE)-induced neuroinflammation and epileptogenesis in experimental models of temporal lobe epilepsy (TLE). In this study, we show a significant disease-modifying effect and the mechanisms of a Fyn/Src tyrosine kinase inhibitor, saracatinib (SAR, also known as AZD0530), in the rat kainate (KA) model of TLE. SAR treatment for a week, starting the first dose (25 mg/kg, oral) 4 h after the onset of SE, significantly reduced spontaneously recurring seizures and epileptiform spikes during the four months of continuous video-EEG monitoring. Immunohistochemistry of brain sections and Western blot analyses of hippocampal lysates at 8-day (8d) and 4-month post-SE revealed a significant reduction of SE-induced astrogliosis, microgliosis, neurodegeneration, phosphorylated Fyn/Src-419 and PKCδ-tyr311, in SAR-treated group when compared with the vehicle control. We also found the suppression of nitroxidative stress markers such as iNOS, 3-NT, 4-HNE, and gp91phox in the hippocampus, and nitrite and ROS levels in the serum of the SAR-treated group at 8d post-SE. The qRT-PCR (hippocampus) and ELISA (serum) revealed a significant reduction of key proinflammatory cytokines TNFα and IL-1β mRNA in the hippocampus and their protein levels in serum, in addition to IL-6 and IL-12, in the SAR-treated group at 8d in contrast to the vehicle-treated group. These findings suggest that SAR targets some of the key biomarkers of epileptogenesis and modulates neuroinflammatory and nitroxidative pathways that mediate the development of epilepsy. Therefore, SAR can be developed as a potential disease-modifying agent to prevent the development and progression of TLE.

Adjuvant High-Flow Normobaric Oxygen After Mechanical Thrombectomy for Anterior Circulation Stroke: a Randomized Clinical Trial

Adjuvant neuroprotective therapies for acute ischemic stroke (AIS) have demonstrated benefit in animal studies, albeit without human translation. We investigated the safety and efficacy of high-flow normobaric oxygen (NBO) after endovascular recanalization in anterior circulation stroke. This is a prospective randomized controlled study. Eligible patients were randomized to receive high-flow NBO by a Venturi mask (FiO2 50%, flow 15 L/min) or routine low-flow oxygen supplementation by nasal cannula (flow 3 L/min) after vessel recanalization for 6 h. Patient demographics, procedural metrics, complications, functional outcomes, symptomatic intracranial hemorrhage (sICH), and infarct volume were assessed. A total of 91 patients were treated with high-flow NBO. NBO treatment revealed a common odds ratio of 2.2 (95% CI, 1.26 to 3.87) favoring the distribution of global disability scores on the mRS at 90 days. The mortality at 90 days was significantly lower in the NBO group than in the control group, with an absolute difference of 13.86% (rate ratio, 0.35; 95% CI, 0.13-0.93). A significant reduction of infarct volume as determined by MRI was noted in the NBO group. The median infarct volume was 9.4 ml versus 20.5 ml in the control group (beta coefficient, - 20.24; 95% CI, - 35.93 to - 4.55). No significant differences were seen in the rate of sICH, pneumonia, urinary infection, and seizures between the 2 groups. This study suggests that high-flow NBO therapy after endovascular recanalization is safe and effective in improving functional outcomes, decreasing mortality, and reducing infarct volumes in anterior circulation stroke patients within 6 h from stroke onset.

Hydrogen Sulfide Protects Against Uremic Accelerated Atherosclerosis via nPKCδ/Akt Signal Pathway

Background: Cardiovascular disease is the most common complication and leading cause of death in maintenance hemodialysis patients. Previous studies have found that disorders of cystathionine-gamma-lyase/hydrogen sulfide (CSE/H₂S) system in maintenance hemodialysis patients are correlated with the risk of cardiovascular disease. Although the role of CSE/H₂S system in UAAS has been preliminarily explored, the molecular mechanism of CSE/H₂S is still not systematically elaborated, and the molecular mechanism of nPKCδ and its related signaling pathway in UAAS is still not thoroughly studied.

Methods: Forty chronic kidney disease (CHD) patients were studied and the activation of nPKCδ in peripheral blood mononuclear cells (PBMCs) were detected. ApoE^−/− mice aged 6 weeks were treated with 5/6 nephrectomy and high-fat diet to make UAAS model. They were divided into Sham group (Sham group), UAAS group (UAAS group), UAAS+L-cysteine group (UAAS+L-cys group), UAAS+sodium hydrosulfide group (UAAS+NaHS group) and UAAS+propargylglycine group (UAAS+PPG group). The UAAS+L-cys group, UAAS+NaHS group and UAAS+PPG group were respectively given L-cys, NaHS and PPG by intraperitoneal injection. The aorta was taken 6 weeks after surgery. Western blot was used to detect the activation of nPKCδ, the phosphorylation of Akt, and the expression of VCAM-1 in the aorta of mice.

Results: The membrane translocation of nPKCδ in CHD patients with plaque was higher than that in CHD patients without plaque. The membrane translocation of nPKCδ and the expression of VCAM-1 in UAAS group was higher than sham group, L-cys or NaHS injection could suppress the membrane translocation of nPKCδ and the expression of VCAM-1, but PPG treatment resulted in more membrane translocation of nPKCδ and the expression of VCAM-1 (P<0.05, n=6 per group). Akt phosphorylation in UAAS group was lower than sham group, and L-cys or NaHS injection could suppress the degradation of Akt phosphorylation, but PPG treatment resulted in more decrease in the Akt phosphorylation (P<0.05, n=6 per group).

Conclusion: Endogenous CSE/H₂S system protected against the formation of UAAS via nPKCδ/Akt signal pathway. The imbalance of CSE/H₂S system may participate in the formation of UAAS by affecting the expression of downstream molecule VCAM-1, which may be mediated by nPKCδ/Akt signaling pathway.

Normobaric oxygen therapy attenuates hyperglycolysis in ischemic stroke

Normobaric oxygen therapy has gained attention as a simple and convenient means of achieving neuroprotection against the pathogenic cascade initiated by acute ischemic stroke. The mechanisms underlying the neuroprotective efficacy of normobaric oxygen therapy, however, have not been fully elucidated. It is hypothesized that cerebral hyperglycolysis is involved in the neuroprotection of normobaric oxygen therapy against ischemic stroke. In this study, Sprague-Dawley rats were subjected to either 2-hour middle cerebral artery occlusion followed by 3- or 24-hour reperfusion or to a permanent middle cerebral artery occlusion event. At 2 hours after the onset of ischemia, all rats received either 95% oxygen normobaric oxygen therapy for 3 hours or room air. Compared with room air, normobaric oxygen therapy significantly reduced the infarct volume, neurological deficits, and reactive oxygen species and increased the production of adenosine triphosphate in ischemic rats. These changes were associated with reduced transcriptional and translational levels of the hyperglycolytic enzymes glucose transporter 1 and 3, phosphofructokinase 1, and lactate dehydrogenase. In addition, normobaric oxygen therapy significantly reduced adenosine monophosphate-activated protein kinase mRNA expression and phosphorylated adenosine monophosphate-activated protein kinase protein expression. These findings suggest that normobaric oxygen therapy can reduce hyperglycolysis through modulating the adenosine monophosphate-activated protein kinase signaling pathway and alleviating oxidative injury, thereby exhibiting neuroprotective effects in ischemic stroke. This study was approved by the Institutional Animal Investigation Committee of Capital Medical University (approval No. AEEI-2018-033) on August 13, 2018.

LncRNA SNHG1 protects SH-SY5Y cells from hypoxic injury through miR-140-5p/Bcl-XL axis

Background: Hypoxic brain injury is one of the major causes of neurodevelopmental impairment and cardiovascular disability. LncRNA SNHG1 works as a critical factor in hypoxic induced injury, however, the potential mechanism is still not known well.Methods: The expression level of small nucleolar RNA host gene 1 (SNHG1) and miR-140-5p was detected by qRT-PCR. The western blot assay was performed to measure the level of Bcl-XL and apoptosis-related proteins. The target relationship between lncRNA SNHG1 and miR-140-5p, as well as miR-140-5p and Bcl-XL was detected by dual luciferase reporter gene assay. Cell apoptosis was assessed using Annexin V/PI staining by flow cytometry. Cell viability was analyzed by MTT assay.Results: Oxygen glucose deprivation (OGD) treatment inhibited SNHG1 and Bcl-XL expression and enhanced miR-140-5p expression. OGD treatment-induced cell viability inhibition, cell apoptosis promotion were partially abrogated when SH-SY5Y cells were transfected with pcDNA3.1-SNHG1 or miR-140-5p inhibitor. Moreover, luciferase reporter assay revealed that lncRNA SNHG1 bound directly to miR-140-5p, and miR-140-5p directly targeted Bcl-XL. The protective effect of SNHG1 overexpressing on cell apoptosis induced by OGD was attenuated after transfected with miR-140-5p mimic or sh-Bcl-XL in SH-SY5Y cells.Conclusion: LncRNA SNHG1-modulated miR-140-5p inhibition regulates Bcl-XL expression, thereby reducing cell apoptosis and recovering cell viability of SH-SY5Y cells. The results in this study provide novel insight into the mechanism of SNHG1 mediated signaling pathway during hypoxic brain injury.

Activation of Protein Kinase Cδ Contributes to the Induction of Src/EGF Receptor/ERK Signaling in Ammonia-treated Astrocytes

Previously, we showed that Src-mediated EGF receptor transactivation/ERK activation mediates ammonia-induced astrocyte swelling, which represents a major component of brain edema in hyperammonemic disorders. Here, we tested the role of PKC in the induction of this signaling pathway and its involvement in ammonia-mediated cell swelling. We found that incubating astrocytes with bisindolylmaleimide (BIM, an inhibitor of classical and novel PKC isoforms) or rottlerin, a PKCδ-specific inhibitor, attenuated the ammonia-induced phosphorylation of EGFR, while GF109203X had no effect on this pathway. We further found that BIM or rottlerin pretreatment inhibited the ammonia-induced phosphorylation of Src and that ammonia significantly increased the level of PKCδ pulled down by a Src antibody. AG1478, a specific EGFR kinase activity inhibitor, effectively inhibited phosphorylation at Tyr1068 but had no discernable effect on phosphorylation at Tyr845. Moreover, BIM or rottlerin abrogated ammonia-induced ERK phosphorylation. BIM-, rottlerin-, or GF109203X-treated astrocytes showed a significant reduction in cell swelling compared to that observed after treatment with ammonia alone. Finally, it was found that AG1478 attenuated ammonia-induced PKCα translocation to the particulate fraction. Taken together, our results indicate that PKCδ mediates ammonia-induced astrocyte swelling by activating Src and downstream EGF receptor/ERK signaling, which may contribute to the pathogenesis of neuropsychiatric disorders associated with hyperammonemia.

Advances in Normobaric Hyperoxia Brain Protection in Experimental Stroke

As we all know that stroke is still a leading cause of death and acquired disability. Etiological treatment and brain protection are equally important. This review aimed to summarize the advance of normobaric-hyperoxia (NBHO) on brain protection in the setting of experimental stroke and brain trauma. We analyzed the data from relevant studies published on PubMed Central (PMC) and EMBASE, about NBHO on brain protection in the setting of experimental ischemic and hemorrhagic strokes and brain trauma, which revealed that NBHO had important value on improving hypoxia and attenuating ischemia damage. The mechanisms of NBHO involved increasing the content of oxygen in brain tissues, restoring the function of mitochondria, enhancing the metabolism of neurons, alleviating blood-brain barrier (BBB) damage, weakening brain cell edema, reducing intracranial pressure, and improving cerebral blood flow, especially in the surrounding of injured area of the brain, to make the neurons in penumbral area alive. Compared to hyperbaric oxygen (HBO), NBHO is more safe and more easily to transform to clinical use, whereby, further studies about the safety and efficacy as well as the proper treatment protocol of NBHO on human may be still needed.

Reduced culture temperature attenuates oxidative stress and inflammatory response facilitating expansion and differentiation of adipose-derived stem cells

Background

Adipose-derived stem cell (ASC) expansion under atmospheric oxygen levels (21%) was previously shown to cause increased reactive oxygen species (ROS) accumulation and genetic instability compared to cells cultured under physiological oxygen levels (2–8%). However, since culture under physiological oxygen levels is costly and complicated, a simpler method to reduce ROS accumulation is desirable. The current study aimed to determine whether lower culture temperature can reduce ROS production in ASCs without impairing their culture expansion.

Methods

Proliferation, differentiation, ROS accumulation, and gene expression were compared between ASC cultures at 35 °C and 37 °C. ASCs isolated either from rat fat depots or from human lipoaspirates were examined in the study.

Results

Rat visceral ASCs (vASCs) cultured at 35 °C demonstrated reduced ROS production and apoptosis and enhanced expansion and adipogenic differentiation compared to vASCs cultured at 37 °C. Similarly, the culture of human ASCs (hASCs) at 35 °C led to reduced ROS accumulation and apoptosis, with no effect on the proliferation rate, compared to hASCs cultured at 37 °C. Comparison of gene expression profiles of 35 °C versus 37 °C vASCs uncovered the development of a pro-inflammatory phenotype in 37 °C vASCs in correlation with culture temperature and ROS overproduction. This correlation was reaffirmed in both hASCs and subcutaneous rat ASCs.

Conclusions

This is the first evidence of the effect of culture temperature on ASC growth and differentiation properties. Reduced temperatures may result in superior ASC cultures with enhanced expansion capacities in vitro and effectiveness in vivo.

Reduced Apoptotic Injury by Phenothiazine in Ischemic Stroke through the NOX-Akt/PKC Pathway

Phenothiazine treatment has been shown to reduce post-stroke ischemic injury, though the underlying mechanism remains unclear. This study sought to confirm the neuroprotective effects of phenothiazines and to explore the role of the NOX (nicotinamide adenine dinucleotide phosphate oxidase)/Akt/PKC (protein kinase C) pathway in cerebral apoptosis. Sprague-Dawley rats underwent middle cerebral artery occlusion (MCAO) for 2 h and were randomly divided into 3 different cohorts: (1) saline, (2) 8 mg/kg chlorpromazine and promethazine (C+P), and (3) 8 mg/kg C+P as well as apocynin (NOX inhibitor). Brain infarct volumes were examined, and cell death/NOX activity was determined by assays. Western blotting was used to assess protein expression of kinase C-δ (PKC-δ), phosphorylated Akt (p-Akt), Bax, Bcl-XL, and uncleaved/cleaved caspase-3. Both C+P and C+P/NOX inhibitor administration yielded a significant reduction in infarct volumes and cell death, while the C+P/NOX inhibitor did not confer further reduction. In both treatment groups, anti-apoptotic Bcl-XL protein expression generally increased, while pro-apoptotic Bax and caspase-3 proteins generally decreased. PKC protein expression was decreased in both treatment groups, demonstrating a further decrease by C+P/NOX inhibitor at 6 and 24 h of reperfusion. The present study confirms C+P-mediated neuroprotection and suggests that the NOX/Akt/PKC pathway is a potential target for efficacious therapy following ischemic stroke.

The interrelationship between cerebral ischemic stroke and glioma: a comprehensive study of recent reports

Glioma and cerebral ischemic stroke are two major events that lead to patient death worldwide. Although these conditions have different physiological incidences, ~10% of ischemic stroke patients develop cerebral cancer, especially glioma, in the postischemic stages. Additionally, the high proliferation, venous thrombosis and hypercoagulability of the glioma mass increase the significant risk of thromboembolism, including ischemic stroke. Surprisingly, these events share several common pathways, viz. hypoxia, cerebral inflammation, angiogenesis, etc., but the proper mechanism behind this co-occurrence has yet to be discovered. The hypercoagulability and presence of the D-dimer level in stroke are different in cancer patients than in the noncancerous population. Other factors such as atherosclerosis and coagulopathy involved in the pathogenesis of stroke are partially responsible for cancer, and the reverse is also partially true. Based on clinical and neurosurgical experience, the neuronal structures and functions in the brain and spine are observed to change after a progressive attack of ischemia that leads to hypoxia and atrophy. The major population of cancer cells cannot survive in an adverse ischemic environment that excludes cancer stem cells (CSCs). Cancer cells in stroke patients have already metastasized, but early-stage cancer patients also suffer stroke for multiple reasons. Therefore, stroke is an early manifestation of cancer. Stroke and cancer share many factors that result in an increased risk of stroke in cancer patients, and vice-versa. The intricate mechanisms for stroke with and without cancer are different. This review summarizes the current clinical reports, pathophysiology, probable causes of co-occurrence, prognoses, and treatment possibilities.

PM2.5 exposure induces systemic inflammation and oxidative stress in an intracranial atherosclerosis rat model

OBJECTIVES

Exposure to airborne particle (PM_2.5 ) is a risk factor for intracranial atherosclerosis (ICA). Because of the established role of systemic inflammation and oxidative stress by PM_2.5 , we determined whether these processes account for PM_2.5 -mediated ICA, and also whether omega-3 fatty acid (O3FA) dietary supplementation could attenuate them.

METHODS

Adult Sprague-Dawley rats were exposed to filtered air (FA) or PM_2.5 and fed either a normal chow diet (NCD) or a high-cholesterol diet (HCD), administered with or without O3FA (5 mg/kg/day by gavage) for 12 weeks. The lumen and thickness of the middle cerebral artery (MCA) were assessed. Serum tumor necrosis factor alpha (TNF-α), interleukin 6 (IL-6), interleukin-1β (IL-1β), and interferon gamma (IFN-γ) were detected by ELISA. Reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) activity, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase (NOX) activity, mRNA levels of Nrf2, HO-1, NQO-1, and protein level of NOX subunit gp91 were quantified to determine the oxidative profile of brain vessels.

RESULTS

PM_2.5 increased (P < .05) ICA, especially in the HCD group; elevated serum TNF-α, IL-6, IL-1β, and IFN-γ; increased cerebrovascular ROS, MDA, NOX activity, and gp91 protein levels; and decreased cerebrovascular SOD activity. Nrf2, HO-1, and NQO-1 mRNA levels were upregulated (P < .05) by PM_2.5 exposure, especially in the HCD group. O3FA attenuated (P < .05) PM_2.5 -induced systemic inflammation, vascular oxidative injury, and ICA.

CONCLUSIONS

PM_2.5 exposure induced systemic inflammation, cerebrovascular oxidative injury, and ICA in rats with HCD. O3FA prevented ICA development, and may therefore exert a protective effect against the atherogenic potential of PM_2.5 .

Riluzole promotes neurological function recovery and inhibits damage extension in rats following spinal cord injury: a meta-analysis and systematic review

Spinal cord injury (SCI) is a devastating condition that has few treatment options. Riluzole, a sodium channel blocker used to treat amyotrophic lateral sclerosis, has been initially trialed in human SCI. We performed a systematic review to critically assess the efficacy of riluzole in locomotor recovery and damage extension in SCI rat models, and the potential for clinical translation. PubMed, Embase, Cochrane Library, and Chinese databases were searched from their inception date to March 2018. Two reviewers independently selected animal studies that evaluated neurological recovery and lesion area following riluzole treatment in SCI rat models, extracted data and assessed methodological quality. Pairwise meta-analysis, subgroup analysis, and network meta-analysis were performed to assess the effects of riluzole on SCI. Ten eligible studies were included. Two studies had high methodological quality. Overall, the Basso, Beattie, and Bresnahan scores were increased in riluzole-treated animals versus controls, and effect sizes showed a gradual increase from the 1st (five studies, n = 104, mean difference = 1.24, 95% CI = 0.11 to 2.37, p = 0.03) to 6th week after treatment (five studies, n = 120, mean difference = 2.34, 95% CI = 1.26 to 3.42, p < 0.0001). Riluzole was associated with improved outcomes in the inclined plane test and the tissue preservation area. Subgroup analyses suggested an association of locomotor recovery with riluzole dose. Network meta-analysis showed that 5 mg/kg riluzole exhibited greater protection than 2.5 and 8 mg/kg riluzole. Collectively, this review suggests that riluzole has a protective effect on SCI, with good safety and a clear mechanism of action and may be suitable for future clinical trials or applications. However, animal results should be interpreted with caution given the known limitations in animal experimental design and methodological quality.

Nicotinamide adenine dinucleotide phosphate oxidase activation and neuronal death after ischemic stroke

Nicotinamide adenine dinucleotide phosphate oxidase (NOX) is a multisubunit enzyme complex that utilizes nicotinamide adenine dinucleotide phosphate to produce superoxide anions and other reactive oxygen species. Under normal circumstances, reactive oxygen species mediate a number of important cellular functions, including the facilitation of adaptive immunity. In pathogenic circumstances, however, excess reactive oxygen species generated by NOX promotes apoptotic cell death. In ischemic stroke, in particular, it has been shown that both NOX activation and derangements in glucose metabolism result in increased apoptosis. Moreover, recent studies have established that glucose, as a NOX substrate, plays a vital role in the pathogenesis of reperfusion injury. Thus, NOX inhibition has the potential to mitigate the deleterious impact of hyperglycemia on stroke. In this paper, we provide an overview of this research, coupled with a discussion of its implications for the development of NOX inhibition as a strategy for the treatment of ischemic stroke. Both inhibition using apocynin, as well as the prospect of developing more specific inhibitors based on what is now understood of the biology of NOX assembly and activation, will be highlighted in the course of our discussion.

ALDH2 protects against alcoholic cardiomyopathy through a mechanism involving the p38 MAPK/CREB pathway and local renin-angiotensin system inhibition in cardiomyocytes

BACKGROUND

Angiotensin II (Ang II) in the local cardiac renin-angiotensin system (RAS) is closely associated with alcoholic cardiomyopathy (ACM). Inhibition of local cardiac RAS has great significance in the treatment of ACM. Although aldehyde dehydrogenase 2 (ALDH2) has been demonstrated to protect against ACM through detoxification of aldehydes, the precise mechanisms are largely unknown. In the present study, we determined whether ALDH2 improved cardiac damage by inhibiting the local RAS in ACM and investigated the related regulatory mechanisms.

METHODS AND RESULTS

Adult male mice were fed with 5% ethanol or a control diet for 2months, with or without the ALDH2 activator Alda-1. Heavy ethanol consumption induced cardiac damage, increased angiotensinogen (AGT) and Ang II and decreased myocardial ALDH2 activity in hearts. ALDH2 activation improved ethanol-induced cardiac damage and decreased AGT and Ang II in hearts. In vitro, ALDH2 activation or overexpression decreased AGT and Ang II in cultured cardiomyocytes treated with 400mmol/L ethanol for 24h. Furthermore, p38 MAP kinase (p38 MAPK)/cyclic adenosine monophosphate response element-binding protein (CREB) pathway activation by ethanol increased AGT and Ang II in cardiomyocytes. In addition, ALDH2 activation or overexpression inhibited the p38 MAPK/CREB pathway leading to decreased AGT and Ang II in cardiomyocytes. We also found that p38 MAPK activation effectively mitigated Alda-1-decreased AGT and Ang II, the effect of which was reversed by inhibition of CREB.

CONCLUSIONS

ALDH2 decreased AGT and Ang II in the local cardiac RAS via inhibiting the p38 MAPK/CREB pathway in ACM, thus improving ethanol-induced cardiac damage.

Synergistically Induced Hypothermia and Enhanced Neuroprotection by Pharmacological and Physical Approaches in Stroke

Hypothermia is considered as a promising neuroprotective treatment for ischemic stroke but with many limitations. To expand its clinical relevance, this study evaluated the combination of physical (ice pad) and pharmacological [transient receptor potential vanilloid channel 1 (TRPV1) receptor agonist, dihydrocapsaicin (DHC)] approaches for faster cooling and stronger neuroprotection. A total of 144 male Sprague Dawley rats were randomized to 7 groups: sham (n=16), stroke only (n=24), stroke with physical hypothermia at 31ºC for 3 h after the onset of reperfusion (n=24), high-dose DHC (H-DHC)(1.5 mg/kg, n=24), low-dose DHC (L-DHC)(0.5 mg/kg, n=32) with (n=8) or without (n=24) external body temperature control at ~38 ºC (L-DHC, 38 ºC), and combination therapy (L-DHC+ ice pad, n=24). Rats were subjected to middle cerebral artery occlusion (MCAO) for 2 h. Infarct volume, neurological deficits and apoptotic cell death were determined at 24 h after reperfusion. Expression of pro- and anti-apoptotic proteins was evaluated by Western blot. ATP and reactive oxygen species (ROS) were detected by biochemical assays at 6 and 24 h after reperfusion. Combination therapy of L-DHC and ice pad significantly improved every measured outcome compared to monotherapies. Combination therapy achieved hypothermia faster by 28.6% than ice pad, 350% than L-DHC and 200% than H-DHC alone. Combination therapy reduced (p<0.05) neurological deficits by 63% vs. 26% with L-DHC. No effect was observed when using ice pad or H-DHC alone. L-DHC and ice pad combination improved brain oxidative metabolism by reducing (p<0.05) ROS at 6 and 24 h after reperfusion and increasing ATP levels by 42.9% compared to 25% elevation with L-DHC alone. Finally, combination therapy decreased apoptotic cell death by 48.5% vs. 24.9% with L-DHC, associated with increased anti-apoptotic protein and reduced pro-apoptotic protein levels (p<0.001). Our study has demonstrated that combining physical and pharmacological hypothermia is a promising therapeutic approach in ischemic stroke, and warrants further translational investigations.

Effects of Therapeutic Hypothermia Combined with Other Neuroprotective Strategies on Ischemic Stroke: Review of Evidence

Ischemic stroke is a major cause of death and disability globally, and its incidence is increasing. The only treatment approved by the US Food and Drug Administration for acute ischemic stroke is thrombolytic treatment with recombinant tissue plasminogen activator. As an alternative, therapeutic hypothermia has shown excellent potential in preclinical and small clinical studies, but it has largely failed in large clinical studies. This has led clinicians to explore the combination of therapeutic hypothermia with other neuroprotective strategies. This review examines preclinical and clinical progress towards developing highly effective combination therapy involving hypothermia for stroke patients.

Phenothiazines Enhance Mild Hypothermia-induced Neuroprotection via PI3K/Akt Regulation in Experimental Stroke

Physical hypothermia has long been considered a promising neuroprotective treatment of ischemic stroke, but the treatment's various complications along with the impractical duration and depth of therapy significantly narrow its clinical scope. In the present study, the model of reversible right middle cerebral artery occlusion (MCAO) for 2 h was used. We combined hypothermia (33-35 °C for 1 h) with phenothiazine neuroleptics (chlorpromazine & promethazine) as additive neuroprotectants, with the aim of augmenting its efficacy while only using mild temperatures. We also investigated its therapeutic effects on the Phosphatidylinositol 3 kinase/Protein kinase B (PI3K/Akt) apoptotic pathway. The combination treatment achieved reduction in ischemic rat temperatures in the rectum, cortex and striatum significantly (P < 0.01) faster than hypothermia alone, accompanied by more obvious (P < 0.01) reduction of brain infarct volume and neurological deficits. The combination treatment remarkably (P < 0.05) increased expression of p-Akt and anti-apoptotic proteins (Bcl-2 and Bcl-xL), while reduced expression of pro-apoptotic proteins (AIF and Bax). Finally, the treatment's neuroprotective effects were blocked by a p-Akt inhibitor. By combining hypothermia with phenothiazines, we significantly enhanced the neuroprotective effects of mild hypothermia. This study also sheds light on the possible molecular mechanism for these effects which involves the PI3K/Akt signaling and apoptotic pathway.

Dihydrocapsaicin (DHC) enhances the hypothermia-induced neuroprotection following ischemic stroke via PI3K/Akt regulation in rat

OBJECTIVE

Hypothermia has demonstrated neuroprotection following ischemia in preclinical studies while its clinical application is still very limited. The aim of this study was to explore whether combining local hypothermia in ischemic territory achieved by intra-arterial cold infusions (IACIs) with pharmacologically induced hypothermia enhances therapeutic outcomes, as well as the underlying mechanism.

METHODS

Sprague-Dawley rats were subjected to right middle cerebral artery occlusion (MCAO) for 2h using intraluminal hollow filament. The ischemic rats were randomized to receive: 1) pharmacological hypothermia by intraperitoneal (i.p.) injection of dihydrocapsaicin (DHC); 2) physical hypothermia by IACIs for 10min; or 3) the combined treatments. Extent of brain injury was determined by neurological deficit, infarct volume, and apoptotic cell death at 24h and/or 7d following reperfusion. ATP and ROS levels were measured. Expression of p-Akt, cleaved Caspase-3, pro-apoptotic (AIF, Bax) and anti-apoptotic proteins (Bcl-2, Bcl-xL) was evaluated at 24h. Finally, PI3K inhibitor was used to determine the effect of p-Akt.

RESULTS

DHC or IACIs each exhibited hypothermic effect and neuroprotection in rat MCAO models. The combination of pharmacological and physical approaches led to a faster and sustained reduction in brain temperatures and improved ischemia-induced injury than either alone (P<0.01). Furthermore, the combination treatment favorably increased the expression of anti-apoptotic proteins and decreased pro-apoptotic protein levels (P<0.01 or 0.05). This neuroprotective effect was largely blocked by p-Akt inhibition, indicating a potential role of Akt pathway in this mechanism (P<0.01 or 0.05).

CONCLUSIONS

The combination approach is able to enhance the efficiency of hypothermia and efficacy of hypothermia-induced neuroprotection following ischemic stroke. The findings here move us a step closer towards translating this long recognized TH from bench to bedside.

Oxygen or cooling, to make a decision after acute ischemia stroke

The presence of a salvageable penumbra, a region of ischemic brain tissue with sufficient energy for short-term survival, has been widely agreed as the premise for thrombolytic therapy with tissue plasminogen activator (tPA), which remains the only United States Food and Drug Administration (FDA) approved treatment for acute ischemia stroke. However, the use of tPA has been profoundly constrained due to its narrow therapeutic time window and the increased risk of potentially deadly hemorrhagic transformation (HT). Blood brain barrier (BBB) damage within the thrombolytic time window is an indicator for tPA-induced HT and both normobaric hyperoxia (NBO) and hypothermia have been shown to protect the BBB from ischemia/reperfusion injury. Therefore, providing the O₂ as soon as possible (NBO treatment), freezing the brain (hypothermia treatment) to slow down ischemia-induced BBB damage or their combined use may extend the time window for the treatment of tPA. In this review, we summarize the protective effects of NBO, hypothermia or their use combined with tPA on ischemia stroke, based on which, the combination of NBO and hypothermia may be an ideal early stroke treatment to preserve the ischemic penumbra. Given this, there is an urge for large randomized controlled trials to address the effect.

[Salidroside protects PC12 cells from H2O2-induced apoptosis via suppressing NOX2-ROS-MAPKs signaling pathway]

OBJECTIVE

To investigate the molecular mechanism by which salidroside protects PC12 cells from H₂O₂-induced apoptosis.

METHODS

PC12 cells cultured in DMEM supplemented with 10% horse serum and 5% fetal bovine serum were pretreated with different doses of salidroside for 2 h and then stimulated with H₂O₂ for different lengths of time. The expression levels of PARP and caspase 3 and the phosphorylation of p38, ERK and JNK were determined with Western blotting. The cell nuclear morphology was observed after DAPI staining. The production of ROS was detected using a ROS detection kit, and the levels of gp91^phox and p47^phox in the membrane and cytoplasm were detected by membrane-cytoplasm separation experiment; the binding between gp91^phox and p47^phox was assayed by coimmunoprecipitation experiment.

RESULTS

Salidroside dose-dependently suppressed cell apoptosis, lowered phosphorylation levels of p38, ERK and JNK, inhibited the production of ROS, reduced the binding between gp91^phox and p47^phox, and inhibited the activity of NOX2 in PC12 cells exposed to H₂O₂.

CONCLUSION

Salidroside protects PC12 cells from H₂O₂-induced apoptosis at least partly by suppressing NOX2-ROS-MAPKs signaling pathway.

NOX Activation by Subunit Interaction and Underlying Mechanisms in Disease

Nicotinamide adenine dinucleotide phosphate (NAPDH) oxidase (NOX) is an enzyme complex with the sole function of producing superoxide anion and reactive oxygen species (ROS) at the expense of NADPH. Vital to the immune system as well as cellular signaling, NOX is also involved in the pathologies of a wide variety of disease states. Particularly, it is an integral player in many neurological diseases, including stroke, TBI, and neurodegenerative diseases. Pathologically, NOX produces an excessive amount of ROS that exceed the body’s antioxidant ability to neutralize them, leading to oxidative stress and aberrant signaling. This prevalence makes it an attractive therapeutic target and as such, NOX inhibitors have been studied and developed to counter NOX’s deleterious effects. However, recent studies of NOX have created a better understanding of the NOX complex. Comprised of independent cytosolic subunits, p47-phox, p67-phox, p40-phox and Rac, and membrane subunits, gp91-phox and p22-phox, the NOX complex requires a unique activation process through subunit interaction. Of these subunits, p47-phox plays the most important role in activation, binding and translocating the cytosolic subunits to the membrane and anchoring to p22-phox to organize the complex for NOX activation and function. Moreover, these interactions, particularly that between p47-phox and p22-phox, are dependent on phosphorylation initiated by upstream processes involving protein kinase C (PKC). This review will look at these interactions between subunits and with PKC. It will focus on the interaction involving p47-phox with p22-phox, key in bringing the cytosolic subunits to the membrane. Furthermore, the implication of these interactions as a target for NOX inhibitors such as apocynin will be discussed as a potential avenue for further investigation, in order to develop more specific NOX inhibitors based on the inhibition of NOX assembly and activation.

NADPH oxidase 2 does not contribute to early reperfusion-associated reactive oxygen species generation following transient focal cerebral ischemia

Excess production of reactive oxygen species (ROS) critically contributes to occurrence of reperfusion injury, the paradoxical response of ischemic brain tissue to restoration of cerebral blood flow. However, the enzymatic sources of ROS generation remain to be unclear. This study examined Nox2-containing NADPH oxidase (Nox2) expression and its activity in ischemic brain tissue following post-ischemic reperfusion to clarify the mechanism of enzymatic reaction of ROS. Male Sprague-Dawley rats were subjected to 90-minute middle cerebral artery occlusion, followed by 3 or 22.5 hours of reperfusion. Quantitative reverse transcriptase PCR and western blot assay were performed to measure mRNA and protein expression of Nox2. Lucigenin fluorescence assays were performed to assess Nox activity. Our data showed that Nox2 mRNA and protein expression levels were significantly increased (3.7-fold for mRNA and 3.6-fold for protein) in ischemic brain tissue at 22.5 hours but not at 3 hours following post-ischemic reperfusion. Similar results were obtained for the changes of NADPH oxidase activity in ischemic cerebral tissue at the two reperfusion time points. Our results suggest that Nox2 may not contribute to the early burst of reperfusion-related ROS generation, but is rather an important source of ROS generation during prolonged reperfusion.