Caspase inhibitors: prospective therapies for stroke

Inhibition of Apoptosis in a Model of Ischemic Stroke Leads to Enhanced Cell Survival, Endogenous Neural Precursor Cell Activation and Improved Functional Outcomes

Stroke results in neuronal cell death, which causes long-term disabilities in adults. Treatment options are limited and rely on a narrow window of opportunity. Apoptosis inhibitors demonstrate efficacy in improving neuronal cell survival in animal models of stroke. However, many inhibitors non-specifically target apoptosis pathways and high doses are needed for treatment. We explored the use of a novel caspase-3/7 inhibitor, New World Laboratories (NWL) 283, with a lower IC50 than current caspase-3/7 inhibitors. We performed in vitro and in vivo assays to determine the efficacy of NWL283 in modulating cell death in a preclinical model of stroke. In vitro and in vivo assays show that NWL283 enhances cell survival of neural precursor cells. Delivery of NWL283 following stroke enhances endogenous NPC migration and leads to increased neurogenesis in the stroke-injured cortex. Furthermore, acute NWL283 administration is neuroprotective at the stroke injury site, decreasing neuronal cell death and reducing microglia activation. Coincident with NWL283 delivery for 8 days, stroke-injured mice exhibited improved functional outcomes that persisted following cessation of the drug. Therefore, we propose that NWL283 is a promising therapeutic warranting further investigation to enhance stroke recovery.

Cellular stress management by caspases

Cellular stress plays a pivotal role in the onset of numerous human diseases. Consequently, the removal of dysfunctional cells, which undergo excessive stress-induced damage via various cell death pathways, including apoptosis, is essential for maintaining organ integrity and function. The evolutionarily conserved family of cysteine-aspartic-proteases, known as caspases, has been a key player in orchestrating apoptosis. However, recent research has unveiled the capability of these enzymes to govern fundamental cellular processes without triggering cell death. Remarkably, some of these non-lethal functions of caspases may contribute to restoring cellular equilibrium in stressed cells. This manuscript discusses how caspases can function as cellular stress managers and their potential impact on human health and disease. Additionally, it sheds light on the limitations of caspase-based therapies, given our still incomplete understanding of the biology of these enzymes, particularly in non-apoptotic contexts.

Blood soluble Fas concentrations and ischemic stroke patient mortality

BACKGROUND

Fas is a major receptor for cell death by apoptosis. Higher blood concentrations of soluble Fas (sFas) have been reported in patients with ischemic stroke compared to control subjects. The aim of this study was to explore the existence or not of an association between blood sFas concentrations and mortality in patients with ischemic stroke.

METHODS

This study included patients admitted to Intensive Care Units with severe and malignant middle cerebral artery infarction (MCAI), defined as acute infarction, in more than 50% of this territory on computed tomography and less than 9 points on the Glasgow Coma Scale (GCS). Serum sFas levels were determined at the time of diagnosis of MMCAI.

RESULTS

Non-surviving severe MMCAI patients (n = 27) showed lower platelet count (p = 0.004), higher serum sFas (p < 0.001), and lower GCS (p = 0.001) compared to surviving patients (n = 27). Multiple logistic regression found an association of serum sFas levels and mortality at 30 days (OR = 1.015; 95% CI = 1.002-1.027; p = 0.02) after control for CGS and platelet count.

CONCLUSIONS

The main novelty of our study was the existence of an association between high blood sFas concentrations and mortality in patients with ischemic stroke.

13-Acetoxysarcocrassolide induces apoptosis in human hepatocellular carcinoma cells through mitochondrial dysfunction and suppression of the PI3K/AKT/mTOR/p70S6K signalling pathway

CONTEXT

13-Acetoxysarcocrasside, isolated from the Taiwanese soft coral Sarcophyton crassocaule Moser (Alcyoniidae), has biological activity and induces apoptosis in hepatocellular carcinoma cells.

OBJECTIVE

To elucidate the mechanisms underlying apoptosis induced by 13-acetoxysarcocrasside in HA22T and HepG2 hepatocellular carcinoma cells.

MATERIAL AND METHODS

MTT and morphology assays were employed to assess the anti-proliferative effects of 13-acetoxysarcocrasside (1-5 μM). TUNEL/DAPI staining and annexin V-fluorescein isothiocyanate/propidium iodide staining were used to detect apoptosis. Cells were treated with13-acetoxysarcocrassolide (0, 1, 2, and 4 μM) for 24 h, and the mechanism of cells apoptotic was detected by western blotting. Cells treated with DMSO were the control.

RESULTS

Survival of the cells decreased with the addition of 13-acetoxysarcocrassolide, and at 4 μM cell survival was inhibited by approximately 40%. After treatment of cells with 13-acetoxysarcocrassolide, the incidence of early/late apoptosis to be 0.3%/0.5%∼5.4%/22.7% for HA22T cells, in the HePG2 cells were 0.6%/0.2%∼14.4%/23.7%. Western blotting analysis showed that the expression of Bax, Bad, cleaved caspase 3, cleaved caspase 9, cleaved-PARP-1, cytochrome c, and p-4EBP1 increased with an increasing concentration of 13-acetoxysarcocrasside (0, 1, 2, and 4 μM), whereas that of Bcl-2, Bcl-xL, Mcl-1, p-Bad, p-PI3K, p-AKT, p-mTOR, p-70S6K, p-S6, p-eIF4E, and p-eIF4B decreased.

DISCUSSION AND CONCLUSIONS

Apoptosis induced by 13-acetoxysarcocrassolide in HA22T and HepG2 cells is mediated by mitochondrial dysfunction and inactivation of the PI3K/AKT/mTOR/p70S6K pathway. The potential of 13-acetoxysarcocrassolide as a chemotherapeutic agent should be further assessed for use in human hepatocellular carcinoma treatment.

Metabolomics-based study of the potential interventional effects of Xiao-Xu-Ming Decoction on cerebral ischemia/reperfusion rats

ETHNOPHARMACOLOGICAL RELEVANCE

Xiao-Xu-Ming Decoction (XXMD) is a classical Chinese medicinal compound for the treatment of ischemic stroke, which has good efficacy in clinical studies and also plays a neuroprotective role in pharmacological studies.

AIM OF THE STUDY

The purpose of this study is to investigate the potential and integral interventional effects of XXMD on cerebral ischemia/reperfusion rat model.

MATERIALS AND METHODS

In this study, ¹H NMR metabolomics was used, combined with neurological functional assessments, cerebral infarct area measurements, and pathological staining including Nissl staining, immunofluorescence staining of NeuN and TUNEL, and immunohistochemical staining of MCT2, to analyze the metabolic effects of XXMD in the treatment of an ischemia/reperfusion rat model.

RESULTS

It's observed that XXMD treatment could improve the neurological deficit scores and reduce the cerebral infarct areas on cerebral ischemia/reperfusion rat model. The pathological staining results performed that XXMD treatment could improve the decrease of Nissl bodies and the expression of NeuN and MCT2, reduce the high expression of TUNEL. In ¹H NMR study, it revealed that the metabolic patterns among three experimental groups were different, the level of lactate, acetate, NAA, glutamate, and GABA were improved to varying degrees in different brain area.

CONCLUSION

Our findings indicated that XXMD has positive effect on neuroprotection and improvement of metabolism targeting cerebral ischemic injury in rats, which showed great potential for ischemic stroke.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

The Role of Caspase Family in Acute Brain Injury: The Potential Therapeutic Targets in the Future

The caspase family is commonly involved in the pathophysiology of acute brain injury (ABI) through complex apoptotic, pyroptotic, and inflammatory pathways. Current translational strategies for caspase modulation in ABI primarily focus on caspase inhibitors. Because there are no caspase-inhibiting drugs approved for clinical use on the market, the development of caspase inhibitors remains an attractive challenge for researchers and clinicians. Therefore, we conducted the present review with the aim of providing a comprehensive introduction of caspases in ABI. In this review, we summarized the available evidence and potential mechanisms regarding the biological function of caspases. We also reviewed the therapeutic effects of caspase inhibitors on ABI and its subsequent complications. However, various important issues remain unclear, prompting further verification of the efficacy and safety regarding clinical application of caspase inhibitors. We believe that our work will be helpful to further understand the critical role of the caspase family and will provide novel therapeutic potential for ABI treatment.

Tanhuo Formula Inhibits Astrocyte Activation and Apoptosis in Acute Ischemic Stroke

Tanhuo formula (THF), a traditional Chinese medicinal formula, has been demonstrated to be effective in the clinical treatment of acute ischemic stroke (AIS). However, its active ingredients, potential targets, and molecular mechanisms remain unknown. Based on the validation of active ingredient concentrations, our study attempted to elucidate the possible mechanisms of THF based on network pharmacological analysis and experimental validation. Components of THF were screened using network pharmacological analysis, and a compound–target network and protein–protein interaction (PPI) network were constructed. In total, 42 bioactive compounds and 159 THF targets related to AIS were identified. The PPI network identified AKT1, TNF, IL6, IL1B, and CASP3 as key targets. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis demonstrated that the inflammation and apoptotic pathways were enriched by multiple targets. The main components of THF were identified via high-performance liquid chromatography. Subsequently, a validation experiment was conducted, and the expressions of GFAP, C3, TNF-α, and IL-6 were detected via immunofluorescence staining, confirming the inflammatory response at 30 min and 3 days post injury. Immunohistochemical staining for caspase-3 and TUNEL was also performed to assess apoptosis at the same time points. These results indicate that THF can effectively decrease neural cell apoptosis through the caspase-3 pathway and restrain excessive abnormal activation of astrocytes and the release of TNF-α and IL-6, which might be accompanied by the recovery of motor function. Thus, THF may serve as a promising therapeutic strategy for AIS through multiple targets, components, and pathways.

Therapeutic Effects of Hydroalcoholic Extracts from the Ancient Apple Mela Rosa dei Monti Sibillini in Transient Global Ischemia in Rats

The Mela Rosa dei Monti Sibillini is an ancient apple variety cultivated by Romans in the foothills of the Sibillini Mountains, central Italy, showing potential as a source of nutraceuticals. The purpose of this study was to evaluate the protective effects of the hydroalcoholic extracts from the peel (APE) and pulp (APP) of this fruit in an animal model of transient global ischemia. Chemical constituents were analyzed by liquid chromatography–mass spectrometry (LC-DAD-MSⁿ) indicating several polyphenols such as B-type procyanidins, quercetin derivatives and hydroxycinnamic acids as the main bioactive components. Acute pre-treatment of extracts (30 mg/kg, i.p.) significantly decreased the brain levels of the pro-inflammatory cytokines IL-1β (p < 0.01) and TNF-α (p < 0.001 and p < 0.01 for APE and APP, respectively), the expression of caspase-3 (p < 0.01, For APE) and MDA (p < 0.05), a lipid peroxidation biomarker in rats. Both extracts restricted the pathological changes of the brain induced by ischemic stroke in hematoxylin and eosin assay. Moreover, they improved the scores of behavioral tests in grid-walking and modified neurological severity scores (mNSS) tests. In conclusion, these results proved this ancient Italian apple is a source of nutraceuticals able to protect/prevent damage from brain ischemia.

Regulatory role of miR-129 and miR-384-5p on apoptosis induced by oxygen and glucose deprivation in PC12 cell

This study aimed to establish the role of miR-129 and miR-384-5p in cerebral ischemia-induced apoptosis. Using PC12 cells transfected with miR-129 or miR-384-5p mimics or inhibitors, oxygen glucose deprivation (OGD) conditions were applied for 4 h to simulate transient cerebral ischemia. Apoptotic phenotypes were assessed via lactate dehydrogenase (LDH) assay, MTT cell metabolism assay, and fluorescence-activated cell sorting (FACS). The effect of miR overexpression and inhibition was evaluated by protein and mRNA detection of bcl-2 and caspase-3, critical apoptosis factors. Finally, the direct relationship of miR-129 and bcl-2 and miR-384-5p and caspase-3 was measured by luciferase reporter assay. The overexpression of miR-384-5p and miR-129 deficiency significantly enhanced cell viability, reduced LDH release, and inhibited apoptosis. By contrast, overexpression of miR-129 and miR-384-5p deficiency aggravated hypoxia-induced apoptosis and cell injury. miR-129 overexpression significantly reduced mRNA and protein levels of bcl-2 and miR-129 inhibition significantly increased mRNA and protein levels of bcl-2 in hypoxic cells.miR-384-5p overexpression significantly reduced protein levels of caspase-3 while miR-384-5p deficiency significantly increased protein levels of caspase-3. However, no changes were observed in caspase-3 mRNA in either transfection paradigm. Finally, luciferase reporter assay confirmed caspase-3 to be a direct target of miR-384-5p; however, no binding activity was detected between bcl-2 and miR-129.Transient cerebral ischemia induces differential expression of miR-129 and miR-384-5p which influences apoptosis by regulating apoptotic factors caspase-3 and bcl-2, thereby participating in the pathological mechanism of cerebral ischemia, and becoming potential targets for the treatment of ischemic cerebral injury in the future.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

Serum Levels of B-cell Lymphoma-2 Anti-Apoptotic Protein and Malignant Middle Cerebral Artery Infarction Mortality

INTRODUCTION AND GOAL

There is scarce and contradictory data on B-cell lymphoma 2 (Bcl2), member of the Bcl-2 antiapoptotic molecules family of intrinsic apoptosis pathway, in ischemic stroke patients. The objective of this study was to determine whether there is an association between blood Bcl2 concentrations and mortality of ischemic stroke patients.

MATERIAL AND METHODS

Five Intensive Care Units participated in this prospective and observational study of patients with severe malignant middle cerebral artery infarction (MMCAI). Severe MMCAI was diagnosed when acute infarction was present in 50% or more of said region and with a Glasgow Coma Scale (GCS) score of less than 9 points. Serum samples were collected at the time of MMCAI diagnosis.

FINDINGS

Higher serum Bcl2 concentrations (p = 0.001), lower platelet count (p = 0.01) and lower GCS (p = 0.002) were found in non-survivors (n = 28) than in MMCAI survivors (n = 28). Serum Bcl2 levels had an area under the curve for mortality prediction of 75% (95% CI = 62%-88%; p < 0.001). Patients with serum Bcl2 levels > 43.6 ng/mL had higher mortality rate according to Kaplan-Meier analysis (Hazard ratio=10.0; 95% CI = 3.4-29.5; p < 0.001). Multiple logistic regression showed an association between serum Bcl2 and mortality at 30 days (OR = 1.041; 95% CI = 1.006-1.077; p = 0.02) controlling for GCS and platelet count.

CONCLUSIONS

This study reports for the first time the higher blood Bcl2 concentrations in non-surviving ischemic stroke patients than in survivors and the association between elevated blood Bcl2 and mortality in ischemic stroke patients.

The neuroprotective action of 3,3'-diindolylmethane against ischemia involves an inhibition of apoptosis and autophagy that depends on HDAC and AhR/CYP1A1 but not ERα/CYP19A1 signaling

There are no studies examining the effects of 3,3′-diindolylmethane (DIM) in neuronal cells subjected to ischemia. Little is also known about the roles of apoptosis and autophagy as well as AhR and ERα signaling and HDACs in DIM action. We demonstrated for the first time the strong neuroprotective capacity of DIM in mouse primary hippocampal cell cultures exposed to ischemia at early and later stages of neuronal development. The protective effects of DIM were mediated via inhibition of ischemia-induced apoptosis and autophagy that was accompanied by a decrease in AhR/CYP1A1 signaling and an increase in HDAC activity. DIM decreased the levels of pro-apoptotic factors, i.e., Fas, Caspase-3, and p38 mitogen-activated protein kinase (MAPK). DIM also reduced the protein levels of autophagy-related Beclin-1 (BECN1) and microtubule-associated proteins 1A/1B light chain (LC3), partially reversed the ischemia-induced decrease in Nucleoporin 62 (NUP62) and inhibited autophagosome formation. In addition, DIM completely reversed the ischemia-induced decrease in histone deacetylase (HDAC) activity in hippocampal neurons. Although DIM inhibited AhR/CYP1A1 signaling, it did not influence the protein expression levels of ERα and ERα-regulated CYP19A1 which are known to be controlled by AhR. This study demonstrated for the first time, that the neuroprotective action of 3,3′-diindolylmethane against ischemia involves an inhibition of apoptosis and autophagy and depends on AhR/CYP1A1 signaling and HDAC activity, thus creating the possibility of developing new therapeutic strategies that target neuronal degeneration at specific molecular levels.

Comparative Cerebroprotective Potential of d- and l-Carnosine Following Ischemic Stroke in Mice

l-carnosine is an attractive therapeutic agent for acute ischemic stroke based on its robust preclinical cerebroprotective properties and wide therapeutic time window. However, large doses are needed for efficacy because carnosine is rapidly degraded in serum by carnosinases. The need for large doses could be particularly problematic when translating to human studies, as humans have much higher levels of serum carnosinases. We hypothesized that d-carnosine, which is not a substrate for carnosinases, may have a better pharmacological profile and may be more efficacious at lower doses than l-carnosine. To test our hypothesis, we explored the comparative pharmacokinetics and neuroprotective properties of d- and L-carnosine in acute ischaemic stroke in mice. We initially investigated the pharmacokinetics of d- and L-carnosine in serum and brain after intravenous (IV) injection in mice. We then investigated the comparative efficacy of d- and l-carnosine in a mouse model of transient focal cerebral ischemia followed by in vitro testing against excitotoxicity and free radical generation using primary neuronal cultures. The pharmacokinetics of d- and l-carnosine were similar in serum and brain after IV injection in mice. Both d- and l-carnosine exhibited similar efficacy against mouse focal cerebral ischemia. In vitro studies in neurons showed protection against excitotoxicity and the accumulation of free radicals. d- and l-carnosine exhibit similar pharmacokinetics and have similar efficacy against experimental stroke in mice. Since humans have far higher levels of carnosinases, d-carnosine may have more favorable pharmacokinetics in future human studies.

Therapeutic potential of natural compounds from Chinese medicine in acute and subacute phases of ischemic stroke

Stroke is one of the leading causes of death and disability in adults worldwide, resulting in huge social and financial burdens. Extracts from herbs, especially those used in Chinese medicine, have emerged as new pharmaceuticals for stroke treatment. Here we review the evidence from preclinical studies investigating neuroprotective properties of Chinese medicinal compounds through their application in acute and subacute phases of ischemic stroke, and highlight potential mechanisms underlying their therapeutic effects. It is noteworthy that many herbal compounds have been shown to target multiple mechanisms and in combinations may exert synergistic effects on signaling pathways, thereby attenuating multiple aspects of ischemic pathology. We conclude the paper with a general discussion of the prospects for novel natural compound-based regimens against stroke.

Serum Caspase-3 Levels and Early Mortality of Patients with Malignant Middle Cerebral Artery Infarction

PURPOSE

Circulating caspase-3 levels at 24 h of ischemic stroke were found to be associated with poorer functional neurological outcome in a previous study. The aim of this study was to determine whether there is an association between serum caspase-3 levels and early mortality in patients with malignant middle cerebral artery infarction (MMCAI).

METHODS

We included patients with MMCAI defined as computer tomography showing ischemic changes in more than 50% of the middle cerebral artery territory and Glasgow Coma Scale ≤ 8. Serum caspase-3 levels at days 1, 4, and 8 of MMCAI were determined.

RESULTS

Non-surviving MMCAI (n = 34) showed higher serum caspase-3 levels at days 1 (p < 0.001), 4 (p = 0.001), and 8 (p = 0.01) than surviving patients (n = 34). We found that the area under the curve of serum caspase-3 levels for prediction of mortality at 30 days was 88% (95% CI = 78-95%; p < 0.001). Multiple logistic regression showed that serum caspase-3 levels were associated with 30-day mortality (OR = 51.25; 95% CI = 8.30-316.31; p < 0.001).

CONCLUSIONS

The novel and more important findings of our study were that high serum caspase-3 levels were associated with mortality in MMCAI patients.

Interleukin-11 treatment protected against cerebral ischemia/reperfusion injury

OBJECTIVE

Inflammation and immune responses are crucial factors associated with the onset and progression of stroke. Interleukin-11 (IL-11) is a hematopoietic IL-6 family cytokine that functions as an anti-inflammatory agent against various inflammatory diseases. However, its roles in stroke remain unknown. In this study, we investigated the effects of IL-11 on cerebral ischemia-reperfusion injury in a model of focal cerebral ischemia.

METHODS

Mice were randomly divided into five groups the vehicle group, the middle cerebral artery occlusion (MCAO) group, the MCAO plus adenosine monophosphate-activated protein kinase (AMPK) inhibitor compound C group, the MCAO plus IL-11 treatment group, and the MCAO plus IL-11 treatment and compound C group. Focal cerebral ischemia was induced by occluding the left middle cerebral artery, and reperfusion was achieved by withdrawing the suture 2 h after ischemia. The protein expression levels of IL-11 were measured using Western blot analysis, and its location was detected using immunohistochemistry and immunofluorescence staining. The infarct volume was examined using 2,3,5-triphenyl tetrazolium chloride (TTC) staining, and the neurobehavioral progression was assessed using the neurological scoring system. The expression of astrocytes and microglia was detected using immunochemistry, and real-time quantitative PCR was used for the gene quantification of inflammatory cytokines. The extent of cerebral ischemia-reperfusion injury was tested using Nissl staining and the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay. The expression of the apoptotic proteins Bax, Bcl-2 and cleaved caspase-3 were detected using Western blot analysis, and the oxidative stress was also measured.

RESULTS

The expression of IL-11 mRNA and protein significantly decreased after cerebral ischemia. Immunohistochemical staining showed a large amount of IL-11 in the cerebral cortex of the mice in the vehicle group, whereas the immunoreactivity of IL-11 remained weak for 24 h in the MCAO group. Immunofluorescent staining further confirmed that IL-11 was mainly expressed in the neurons. It was suggested that IL-11 (20 μg/kg) treatment ameliorated infarction and reduced neurological scores. In addition, IL-11 proved to reduce neuropathic damage, glial activation, and the expression of proinflammatory cytokines and increase the expression of anti-inflammatory cytokines after cerebral ischemia. IL-11 was also able to alleviate oxidative stress caused by cerebral ischemia, and AMPK inhibition enhanced the alleviation. Moreover, IL-11 was found to inhibit apoptosis caused by cerebral ischemia, which could also be facilitated by AMPK inhibitors.

SIGNIFICANCE

Our research suggests that IL-11 is decreased during cerebral ischemia-reperfusion injury, but IL-11 treatment can improve neurological function and reduce the cerebral infarct volume, which can trigger stroke in mice. AMPK inhibition can further promote the protective effect of IL-11 in stroke. Overall, we demonstrate that IL-11 is of therapeutic interest in controlling stroke and managing cerebral ischemia-reperfusion injury.

Administration of troxerutin and cerebroprotein hydrolysate injection alleviates cerebral ischemia/reperfusion injury by down-regulating caspase molecules

BACKGROUND

Cerebral ischemia/reperfusion injury (I/R injury) is an important pathological process for nervous system. The I/R injury usually causes cerebral hypoxia, infarct or stroke. This study aimed to evaluate effects of troxerutin and cerebroprotein hydrolysate injection (TC) on I/R injury in rat models.

METHODS

Middle-cerebral artery occlusion/reperfusion (MCAO/R) rat models were established. Rats were divided into normal control (NC), MCAO/R rat model (injecting saline) and MCAO/R rats administrating with TC group (injecting with TC at concentration of 2 mL/100 g body weight). Neurological scores were evaluated with Garcia scale. Magnetic resonance imaging (MRI) was employed to observe infarct area, contralateral area and apparent diffusion coefficient (ADC) values. Cerebral infarct size was examined and visualized by staining with 2,3,5-triphenyltetrazolium chloride (TTC). Western blotting assay was used to determine caspase-1, caspase-3 and caspase-8 expression.

RESULTS

The infarct size of mice in MCAO/R+TC group was smaller significantly compared to that in MCAO/R group (p<0.05). The infarct/contralateral area ratio of T2 and T2 Flair signals in MCAO/R+TC group were lower significantly compared to that in MCAO/R group (p<0.05). ADC values in MCAO/R+TC group were significantly enhanced compared to that in MCAO/R group (p<0.05). The troxerutin and cerebroprotein treatment significantly increased neurological scores compared to that in MCAO/R group (p<0.05). Troxerutin and cerebroprotein treatment significantly decreased expression of caspase-1, caspase-3, caspase-8 compared to that in MCAO/R group (p<0.05).

CONCLUSION

Troxerutin and cerebroprotein administration alleviated cerebral I/R injury by down-regulating caspase molecules.

Electroacupuncture Inhibits Apoptosis of Peri-Ischemic Regions via Modulating p38, Extracellular Signal-Regulated Kinase (ERK1/2), and c-Jun N Terminal Kinases (JNK) in Cerebral Ischemia-Reperfusion-Injured Rats

BACKGROUND Previous studies suggested that inhibition of apoptosis prevents the dysfunction of ischemia-reperfusion injury. In the pathogenesis of ischemia-reperfusion injury, JNK/ERK1/2 and p38 play an essential role in regulation of cell apoptosis. Electroacupuncture (EA), a form of acupuncture, has demonstrated superiority in preventing ischemia-reperfusion injury, but the underlying mechanism is unclear. In the present study, we explored the effects of electroacupuncture at Shenting (GV24) and Baihui (GV20) acupoints on focal cerebral ischemia-reperfusion (MCAO) rats, and explored whether JNK/ERK1/2- and p38-mediated cell apoptosis are involved. MATERIAL AND METHODS The rats were divided into a sham operation control group, an ischemia group, and an electroacupuncture group with acupuncture applied for 10 days (30 min per day). TTC staining was used to calculate the ischemic brain volume. TUNEL staining and transmission electron microscopy were used to detect cell apoptosis. Western blot analysis and Bio-Plex were used to detect JNK, p38, ERK1/2, Bcl-2, and Bax protein expression. RESULTS We found that electroacupuncture at day 10 significantly reduced cerebral infarction. In addition, electroacupuncture suppressed activation of JNK and p38, while enhancing the activation of ERK1/2 in the peri-ischemic regions. Consequently, the effect of electroacupuncture on these pathways resulted in the inhibition of apoptosis, which was demonstrated by TUNEL and transmission electron microscopy. We found that electroacupuncture upregulated the anti-apoptotic Bcl-2/Bax ratio in peri-ischemic regions. CONCLUSIONS Our findings suggest that inhibition of cell apoptosis via regulating multiple signaling pathways might be a mechanism whereby electroacupuncture has a positive therapeutic effect on post-stroke impairment.

Suppression of microRNA-144-3p attenuates oxygen-glucose deprivation/reoxygenation-induced neuronal injury by promoting Brg1/Nrf2/ARE signaling

Accumulating evidence has reported that microRNA-144-3p (miR-144-3p) is highly related to oxidative stress and apoptosis. However, little is known regarding its role in cerebral ischemia/reperfusion-induced neuronal injury. Herein, our results showed that miR-144-3p expression was significantly downregulated in neurons following oxygen-glucose deprivation and reoxygenation (OGD/R) treatment. Overexpression of miR-144-3p markedly reduced cell viability, promoted cell apoptosis, and increased oxidative stress in neurons with OGD/R treatment, whereas downregulation of miR-144-3p protected neurons against OGD/R-induced injury. Brahma-related gene 1 (Brg1) was identified as a potential target gene of miR-144-3p. Moreover, downregulation of miR-144-3p promoted the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and increased antioxidant response element (ARE) activity. However, knockdown of Brg1 significantly abrogated the neuroprotective effects of miR-144-3p downregulation. Overall, our results suggest that miR-144-3p contributes to OGD/R-induced neuronal injury in vitro through negatively regulating Brg1/Nrf2/ARE signaling.

High serum levels of caspase-cleaved cytokeratin-18 are associated with malignant middle cerebral artery infarction patient mortality

BACKGROUND

There have been found apoptotic changes in brain tissue samples from humans after cerebral ischemia. Caspase-cleaved cytokeratin (CCCK)-18 could appears in blood during apoptosis. High circulating levels of CCCK-18 have been associated with a poor prognosis in patients with cerebral process, such as traumatic brain injury and spontaneous cerebral hemorrhage. However, they have not been explored in patients with ischemic stroke. Thus, the aim of this study was to determine whether there is an association between serum CCCK-18 levels and mortality in patients with severe malignant middle cerebral artery infarction (MMCAI).

METHODS

This was an observational, prospective and multicentre study. We included patients with severe MMCAI. We considered MMCAI as severe when Glasgow Coma Scale (GCS) was lower than 9. We measured serum CCCK-18 levels at the diagnosis moment of the severe MMCAI.

RESULTS

We found that non-surviving severe MMCAI patients (n = 33) showed lower GCS and platelet count, and higher serum CCCK-18 levels than survivor ones (n = 33). We found an area under the curve (AUC) of serum CCCK-18 levels to predict 30-day mortality of 82% (95% CI = 71%-91%; p < 0.001). In the multiple logistic regression analysis was found that serum CCCK-18 levels were associated with 30-day mortality (OR = 1.023; 95% CI = 1.010-1.037; p = 0.001) after to control for platelet count and GCS.

CONCLUSIONS

To our knowledge, this is the first series reporting data on serum CCCK-18 levels in ischemic stroke patients. The novel findings of our study were that non-surviving severe MMCAI patients had higher serum CCCK-18 levels than surviving patients, and that there is an association between high serum CCCK-18 levels and MMCAI patients mortality.

Proteomic identification of synaptic caspase substrates

The dismantling and elimination of excess neurons and their connections (pruning) is essential for brain development and may be aberrantly reactivated in some neurodegenerative diseases. Growing evidence implicates caspase-mediated apoptotic and nonapoptotic cascades in the dysfunction and death of neurons in neurodegenerative disorders such as Alzheimer's, Parkinson, and Huntington's diseases. It is the cleaved caspase substrates that are the effectors of synapse elimination. However, their identities, specific cleavage sites, and functional consequences of cleavage are largely unknown. An important gap in our knowledge is a comprehensive catalog of synapse-specific or synapse-enriched caspase targets. Traditional biochemical approaches have revealed only a small number of neuronal caspase targets. Instead, we utilized a gel-based proteomics approach to enable the first global analysis of caspase-mediated cleavage events in mammalian brain synapses, employing both an in vitro system with recombinant activated caspases and an in vivo model of ethanol-induced neuronal apoptosis. Of the more than 70 putative cleavage substrates that were identified, 22 were previously known caspase substrates. Among the novel targets identified and validated by Western blot were the proton pump ATPase subunit ATP6V1B2 and the N-ethylmaleimide-sensitive fusion protein (NSF). Our work represents the first comprehensive, proteome-wide screen for proteolytic targets of caspases in neuronal synapses. Our discoveries will have significance for both furthering basic understanding of roles of caspases in synaptic plasticity and synaptic loss in neurodegeneration, and on a more immediately practical level, may provide candidate biomarkers for measuring synapse loss in human disease states.

Endothelial cell-derived exosomes protect SH-SY5Y nerve cells against ischemia/reperfusion injury

Cerebral ischemia is a leading cause of death and disability. A previous study indicated that remote ischemic postconditioning (RIP) in the treatment of cerebral ischemia reduces ischemia/reperfusion (I/R) injury. However, the underlying mechanism is not well understood. In the present study, the authors hypothesized that the protective effect of RIP on neurological damage is mediated by exosomes that are released by endothelial cells in femoral arteries. To test this, right middle cerebral artery occlusion/reperfusion with RIP was performed in rats. In addition, an I/R injury cell model was tested that included human umbilical vein endothelial cells (HUVECs) and SH-SY5Y cells. Both the in vivo and in vitro models were examined for injury. Markers of exosomes (CD63, HSP70 and TSG101) were assessed by immunohistochemistry, western blot analysis and flow cytometry. Exosomes were extracted from both animal serum and HUVEC culture medium and identified by electron microscopy. They investigated the role of endothelial cell-derived exosomes in the proliferation, apoptosis, cell cycle, migration and invasion of I/R-injured SH-SY5Y cells. In addition, apoptosis-related molecules caspase-3, Bax and Bcl-2 were detected. RIP was determined to increase the number of exosomes and the expression levels of CD63, HSP70 and TSG101 in plasma, but not in brain hippocampal tissue. The size of exosomes released after I/R in HUVECs was similar to the size of exosomes released in rats subjected to RIP. Endothelial cell-derived exosomes partly suppressed the I/R-induced cell cycle arrest and apoptosis, and inhibited cell proliferation, migration and invasion in SH-SY5Y nerve cells. Endothelial cell-derived exosomes directly protect nerve cells against I/R injury, and are responsible for the protective role of RIP in I/R.

Prospective clinical biomarkers of caspase-mediated apoptosis associated with neuronal and neurovascular damage following stroke and other severe brain injuries: Implications for chronic neurodegeneration

Acute brain injuries, including ischemic and hemorrhagic stroke, as well as traumatic brain injury (TBI), are major worldwide health concerns with very limited options for effective diagnosis and treatment. Stroke and TBI pose an increased risk for the development of chronic neurodegenerative diseases, notably chronic traumatic encephalopathy, Alzheimer's disease, and Parkinson's disease. The existence of premorbid neurodegenerative diseases can exacerbate the severity and prognosis of acute brain injuries. Apoptosis involving caspase-3 is one of the most common mechanisms involved in the etiopathology of both acute and chronic neurological and neurodegenerative diseases, suggesting a relationship between these disorders. Over the past two decades, several clinical biomarkers of apoptosis have been identified in cerebrospinal fluid and peripheral blood following ischemic stroke, intracerebral and subarachnoid hemorrhage, and TBI. These biomarkers include selected caspases, notably caspase-3 and its specific cleavage products such as caspase-cleaved cytokeratin-18, caspase-cleaved tau, and a caspase-specific 120 kDa αII-spectrin breakdown product. The levels of these biomarkers might be a valuable tool for the identification of pathological pathways such as apoptosis and inflammation involved in injury progression, assessment of injury severity, and prediction of clinical outcomes. This review focuses on clinical studies involving biomarkers of caspase-3-mediated pathways, following stroke and TBI. The review further examines their prospective diagnostic utility, as well as clinical utility for improved personalized treatment of stroke and TBI patients and the development of prophylactic treatment chronic neurodegenerative disease.

Neuronal death after perinatal cerebral hypoxia-ischemia: Focus on autophagy-mediated cell death

Neonatal hypoxic-ischemic encephalopathy is a critical cerebral event occurring around birth with high mortality and neurological morbidity associated with long-term invalidating sequelae. In view of the great clinical importance of this condition and the lack of very efficacious neuroprotective strategies, it is urgent to better understand the different cell death mechanisms involved with the ultimate aim of developing new therapeutic approaches. The morphological features of three different cell death types can be observed in models of perinatal cerebral hypoxia-ischemia: necrotic, apoptotic and autophagic cell death. They may be combined in the same dying neuron. In the present review, we discuss the different cell death mechanisms involved in neonatal cerebral hypoxia-ischemia with a special focus on how autophagy may be involved in neuronal death, based: (1) on experimental models of perinatal hypoxia-ischemia and stroke, and (2) on the brains of human neonates who suffered from neonatal hypoxia-ischemia.

The effect of concentration and duration of normobaric oxygen in reducing caspase-3 and -9 expression in a rat-model of focal cerebral ischaemia

The aim of this study was to determine the effect of different concentrations of normobaric oxygen (NBO) on neurological function and the expression of caspase-3 and -9 in a rat model of acute cerebral ischaemia. Sprague-Dawley rats (n=120) were randomly divided into four groups (n=30 per group), including 3 groups given NBO at concentrations of 33%, 45% or 61% and one control group given air (21% oxygen). After 2h of ischaemic occlusion, each group was further subdivided into six subgroups (n=5) during reperfusion according to the duration (3, 6, 12, 24, 48 or 72h) and concentration of NBO (33%, 45% or 61%) or air treatment. The Fluorescence Quantitative polymerase chain reaction (PCR) and immunohistochemistry were used to detect caspase-3 and -9 mRNA and protein relative expression respectively. The Neurologic Impairment Score (NIS) was significantly lower in rats given 61% NBO ≥3h after reperfusion when compared to the control group (P<0.05, Mann-Whitney U). NBO significantly reduced caspase-3 and -9 mRNA and protein expression when compared to the control group at all NBO concentrations and time points (P<0.05, ANOVA). The expression of caspase-3 and -9 was lower in the group given 61% NBO compared any other group, and this difference was statistically significant when compared to the group given 33% NBO for ≥48h and the control group (both P<0.05, ANOVA). These findings indicate that NBO may inhibit the apoptotic pathway by reducing caspase-3 and -9 expression, thereby promoting neurological functional recovery after stroke.