Ischemia induces endoplasmic reticulum stress and cell apoptosis in human brain

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.

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.

Autophagy is involved in the neuroprotective effect of nicotiflorin

ETHNOPHARMACOLOGICAL RELEVANCE

Nicotiflorin is a flavonoid glycoside derived from the traditional Chinese medicine FlosCarthami, dried petals of Carthamus tinctorius L., and has been confirmed to be a promising novel drug candidate for ischemic stroke. Yet, the exact role of nicotiflorin in cerebral I/R injury is uncharacterized and the possible mechanisms have not been clearly expounded.

AIM OF THE STUDY

The present study was designed to determine the effect of nicotiflorin on cerebral ischemia/reperfusion (I/R) injury and its relationship with autophagy.

MATERIALS AND METHODS

Middle cerebral artery occlusion (MCAO) in rats and oxygen-glucose deprivation and reintroduction (OGD/R) in SH-SY5Y cells were established in in vivo and in vitro models, respectively. The severity of MCAO was assessed by brain infarct size, neurological scores and survival rate. The severity of OGD/R was evaluated by cell viability, lactate dehydrogenase (LDH) release and cell apoptosis. The level of autophagy was evaluated both in vivo and in vitro. Autophagosomes were observed using transmission electron microscopy and autophagic flux was measured using mRFP-GFP-tandem fluorescent LC3 adenovirus. Autophagy-related proteins (LC3-II/I, SQSTM1, beclin-1, Phospho-mTOR/mTOR) were measured by immunoblot. Autophagy-related mRNA levels (Becn1, Atg7) were detected by Real-Time PCR. Inhibition of autophagy was implemented by 3-Methyladenine (3-MA) or chloroquine in vitro.

RESULTS

In vivo, nicotiflorin treatment alleviated brain damage and neurological deficit while it dramatically increased 72 h survival rate in rats. In vitro, nicotiflorin treatment also ameliorated the severity of OGD/R. Moreover, nicotiflorin treatment increased ischemic penumbra autophagy (autophagosomes, BECN1, LC3-II/I ratio, SQSTM1, Phospho-mTOR/mTOR, Atg7). In vitro, nicotiflorin likewise enhanced autophagy and promoted autophagy flux. Furthermore, the blockade of autophagy by 3-MA or chloroquine disabled the efficacic of nicotiflorin in preventing cell damage upon OGD/R insult.

CONCLUSION

These findings suggest that autophagy plays a significant role in the protective effect of nicotiflorin against ischemic stroke.

LncRNA KCNQ1OT1 Regulates Endoplasmic Reticulum Stress to Affect Cerebral Ischemia-Reperfusion Injury Through Targeting miR-30b/GRP78

Endoplasmic reticulum stress (ERS) plays an important role in cerebral ischemia-reperfusion injury (CIRI) by regulating apoptosis. Although the role of long non-coding RNA (LncRNA) KCNQ1OT1 in CIRI has been reported, the specific mechanism is still unclear. In this paper, the regulation of ERS by LncRNA KCNQ1OT1 in CIRI and its mechanism were studied. Transient middle cerebral artery occlusion (tMCAO) model was established in SD rats with KCNQ1OT1 intervention. PC12 cells were used to construct the OGD/R cell model. The expressions of LncRNA KCNQ1OT1 and miR-30b were detected by RT-qPCR. TCC staining was used to detect the extent of cerebral ischemia. TUNEL staining was used to detect apoptosis level, and Western blot was used to detect the expressions of ERS and apoptosis-related proteins. The targeted binding of LncRNA KCNQ1OT1, miR-30b, and GRP78 was detected by double luciferase assay. The expressions of LncRNA KCNQ1OT1 and miR-30b were interfered by cell transfection. Cell proliferation was detected by CCK-8. The level of LncRNA KCNQ1OT1 was increased and that of miR-30b was decreased in the blood samples of patients with CIRI. In tMCAO rats with KCNQ1OT1 intervention, the expression of miR-30b was increased, and the ischemic range of brain tissues was decreased. What's more, the level of ERS was decreased, and the apoptosis of brain tissues was decreased. LncRNA KCNQ1OT1 could regulate miR-30b/GRP78 in OGD/R cells in a targeted way. Intervention of KCNQ1OT1 could promote the proliferation of OGD/R cells, inhibiting the level of ERS and cell apoptosis. Further inhibition of miR-30b could reverse the effect of intervention of KCNQ1OT1. LncRNA KCNQ1OT1 regulates ERS to affect CIRI through targeting miR-30b/GRP78.

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 Effect of Hedysarum multijugum Maxim.-Chuanxiong rhizoma Compound on Ischemic Stroke: A Research Based on Network and Experimental Pharmacology

Background

Hedysarum multijugum Maxim.-Chuanxiong rhizoma compound (HCC) is a common herbal formula modified from Buyang Huanwu decoction. Clinical trials have demonstrated its therapeutic potential for ischemic stroke (IS). However, the mechanism of HCC remains unclear.

Methods

The HCC's components were collected from the TCMSP database and TCM@Taiwan database. After that, the HCC's compound targets were predicted by PharmMapper. The IS-related genes were obtained from GeneCards, and OMIM and the protein-protein interaction (PPI) data of HCC's targets and IS genes were obtained from the String database. After that, the DAVID platform was applied for Gene Ontology (GO) enrichment analysis and pathway enrichment analysis and the Cytoscape 3.7.2 was utilized to construct and analyze the networks. Finally, a series of animal experiments were carried out to validate the prediction results of network pharmacology. The expressions of GRP78, p-PERK, and CHOP proteins and mRNAs in different time periods after HCC intervention were detected by Western blot, immunohistochemistry, and RT-qPCR.

Results

A total of 440 potential targets and 388 IS genes were obtained. The results of HCC-IS PPI network analysis showed that HCC may regulate IS-related targets (such as ALB, AKT1, MMP9, IGF1, and CASP3), biological processes (such as endoplasmic reticulum stress, inflammation modules, hypoxia modules, regulation of neuronal apoptosis and proliferation, and angiogenesis), and signaling pathways (such as PI3K-Akt, FoxO, TNF, HIF-1, and Rap1 signaling). The animal experiments showed that HCC can improve the neurobehavioral scores and protect the neurons of IS rats (P < 0.05). HCC inhibited the expression of p-PERK in the PERK pathway from 12 h after surgery, significantly promoted the expression of GRP78 protein, and inhibited the expression of CHOP protein after surgery, especially at 24 h after surgery (P < 0.05). The results of RT-qPCR showed that HCC can significantly reduce the expression of CHOP mRNA in the neurons in the CA1 region of the hippocampus 72 h after MCAO (P < 0.05).

Conclusion

HCC may achieve a role in the treatment of IS by intervening in a series of targets, signaling pathways, and biological processes such as inflammation, oxidative stress, endoplasmic reticulum stress, and angiogenesis.

Non-Survivor Ischemic Stroke Patients Maintain High Serum Caspase-Cleaved Cytokeratin-18 Levels

OBJECTIVE

Caspase-cleaved cytokeratin (CCCK)-18 could appear in blood during apoptosis. In two different studies, on day 1 of cerebral infarction and at 72 hours of cerebral infarction, respectively, higher circulating CCCK-18 levels were found in non-surviving than in surviving patients. The objective of this study was to analyze the ability of these levels to predict mortality at any time during the first week of cerebral infarction.

METHODS

Patients with malignant middle cerebral artery infarction (MMCAI) were included and the diagnosis criteria were the presence, observed in a computed tomography, of an acute cerebral infarction in at least 50% of this territory and midline shift, and an acute neurological deterioration with a Glasgow Coma Scale ≤ 8. Serum CCCK-18 levels at days 1, 4 and 8 of MMCAI were determined.

RESULTS

Serum concentrations of CCCK-18 at days 1, 4 and 8 of MMCAI were higher in non-surviving (n = 34) than in surviving patients (n = 34). Serum CCCK-18 concentrations at days 1, 4 and 8 of MMCAI had an area under curve (95% CI) used to predict a 30-day mortality of 0.83 (0.72--0.91; p < 0.001), 0.78 (0.65-0.89; p < 0.001) and 0.82 (0.68-0.92; p < 0.001).

CONCLUSIONS

The novel finding is that serum levels of CCCK-18 levels at any time after the first week of MMCAI could help predict 30-day mortality.

Predictive Value of Endoplasmic Reticulum Stress Markers in Low Ejection Fractional Heart Failure

BACKGROUND/AIM

Endoplasmic reticulum (ER) stress plays a critical role in the development of cardiac hypertrophy and heart failure. Heart failure is a crucial health problem that affects 23 million people worldwide, causes approximately 2.4 million people to be hospitalized every year in the USA, and leads to the death of more than 300,000 people. In this study, we aimed to investigate the clinical significance of ER stress markers and the predictive value of acute decompensated heart failure in patients with low ejection fraction heart failure (ADHF).

PATIENTS AND METHODS

This is a prospective case control study. The data included laboratory parameters pertaining to patients with ADHF in the emergency service and lipid parameters obtained during their admission to the hospital. In addition, the same parameters obtained from the control group patients with chronic heart failure (CHF) during their routine polyclinic control were recorded in the data set. Admission time to the hospital and length of hospital stay were included in the data. The levels of glucose regulated protein (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), and C/EBP homologous protein (CHOP) in peripheral blood serum obtained from the patients and the control group were measured using the ELISA method.

RESULTS

Serum GRP78 concentration was lower in the HF group (p=0.003) compared to the control. The median value of serum PERK concentration in the HF group was higher than that of the control group (573 pg/ml, IQR=477.5-650 vs. 495.5 pg/ml, IQR=294-648, respectively) (p=0.001). However, there were no statistically significant differences in GRP78 and PERK serum concentrations between ADHF and CHF subgroups. Receiver operating characteristic (ROC) curve analysis showed greater area under the curve (AUC) for the serum GRP78 levels of the healthy individuals (AUC=0.748, 95% CI=0.681-0.814, p=0.0003). The serum GRP78 level was found to be 80% sensitive and 70% specific at 147.5 pg/ml (p=0.0003) for distinguishing healthy individuals from HF patients. In the ADHF subgroup, there was a moderate correlation between hospitalization time and serum CHOP concentrations (Spearman rho=0.586 and p=0.001).

CONCLUSION

High GRP78 serum concentration may protect the patient from ER stress. In addition, the serum PERK level is high in patients with HF, whereas it is insufficient in predicting acute decompensation. CHOP may be useful in predicting the length of hospital stay in patients with ADHF.

Nafamostat mesylate attenuates the pathophysiologic sequelae of neurovascular ischemia

Nafamostat mesylate, an apparent soi-disant panacea of sorts, is widely used to anticoagulate patients undergoing hemodialysis or cardiopulmonary bypass, mitigate the inflammatory response in patients diagnosed with acute pancreatitis, and reverse the coagulopathy of patients experiencing the commonly preterminal disseminated intravascular coagulation in the Far East. The serine protease inhibitor nafamostat mesylate exhibits significant neuroprotective effects in the setting of neurovascular ischemia. Nafamostat mesylate generates neuroprotective effects by attenuating the enzymatic activity of serine proteases, neuroinflammatory signaling cascades, and the endoplasmic reticulum stress responses, downregulating excitotoxic transient receptor membrane channel subfamily 7 cationic currents, modulating the activity of intracellular signal transduction pathways, and supporting neuronal survival (brain-derived neurotrophic factor/TrkB/ERK1/2/CREB, nuclear factor kappa B. The effects collectively reduce neuronal necrosis and apoptosis and prevent ischemia mediated disruption of blood-brain barrier microarchitecture. Investigational clinical applications of these compounds may mitigate ischemic reperfusion injury in patients undergoing cardiac, hepatic, renal, or intestinal transplant, preventing allograft rejection, and treating solid organ malignancies. Neuroprotective effects mediated by nafamostat mesylate support the wise conduct of randomized prospective controlled trials in Western countries to evaluate the clinical utility of this compound.

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.

Endoplasmic reticulum stress markers are of no value in predicting cardiopulmonary resuscitation success and survival in out-of hospital cardiac arrest: A nested case-control study

Objectives

The purpose of this study was to determine the value of the endoplasmic reticulum (ER) stress markers glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP) and PERK in predicting the success of cardiopulmonary resuscitation (CPR) or post-CPR survival.

Materials and Methods

Non-traumatic out-of-hospital CA patients were included in this prospective, nested case-control study. Standard CPR and post-resuscitative care were applied. Levels of ER stress markers were measured at presentation and were investigated to determine whether they might constitute a marker predicting return of spontaneous circulation (ROSC) or sustained ROSC, and of 24-h, and 1 and 3-month survival.

Results

Fifty-two out of 99 non-traumatic CA patients were enrolled. ROSC was determined at a level of 25%, sustained ROSC at 23%, 24-h survival at 7%, and 1- and 3-month survival at 4.6%. No difference was determined in terms of ER stress markers between patients with and without ROSC or sustained ROSC. Only PERK levels were higher in surviving patients than non-surviving subjects in terms of 24-h survival (p = 0.01). Otherwise, no stress markers differed between surviving and non-surviving patients at any survival time point.

Conclusion

ER stress markers are of no value in determining establishment of ROSC or sustained ROSC, success of CPR, or survival. Only PERK levels may be valuable in terms of 24-h survival.

Impaired capacity to restore proteostasis in the aged brain after ischemia: Implications for translational brain ischemia research

Brain ischemia induced by cardiac arrest or ischemic stroke is a severe form of metabolic stress that substantially disrupts cellular homeostasis, especially protein homeostasis (proteostasis). As proteostasis is fundamental for cellular and organismal health, cells have developed a complex network to restore proteostasis impaired by stress. Many components of this network - including ubiquitination, small ubiquitin-like modifier (SUMO) conjugation, autophagy, and the unfolded protein response (UPR) - are activated in the post-ischemic brain, and play a crucial role in cell survival and recovery of neurologic function. Importantly, recent studies have shown that ischemia-induced activation of these proteostasis-related pathways in the aged brain is impaired, indicating an aging-related decline in the self-healing capacity of the brain. This impaired capacity is a significant factor for consideration in the field of brain ischemia because the vast majority of cardiac arrest and stroke patients are elderly. In this review, we focus on the effects of aging on these critical proteostasis-related pathways in the brain, and discuss their implications in translational brain ischemia research.

The value of endoplasmic reticulum stress markers (GRP78 and CHOP) in the diagnosis of acute mesenteric ischemia

AIM

To evaluate levels of the endoplasmic reticulum (ER) stress markers GRP78 and CHOP in acute mesenteric ischemia (AMI) and to examine relations with degrees of AMI-related intestinal injury.

MATERIALS AND METHODS

Twenty-four rats were divided into four groups. Group I and Group III represented the control groups, from which blood and tissue specimens were collected 2 and 6 h after laparotomy without superior mesenteric artery (SMA) ligation. Group II and Group IV constituted the ischemia groups, from which blood and tissue specimens were collected 2 and 6 h after SMA ligation. The ER stress markers GRP78 and CHOP, total oxidant status (TOS), total antioxidant status (TAS), and the oxidative stress index (OSI) were investigated in each group. Ileum specimens were assessed in terms of ischemic injury, and appropriate comparisons were performed.

RESULTS

Significantly higher GRP78, CHOP, TOS, and TAS values were determined in the ischemia groups (groups II and IV) compared to the control groups (groups I and III). This elevation was greater in the 6 h ischemia group, the group exposed to the greatest ischemic injury (Group IV). Significant and powerful correlation was present between histopathological damage and levels of the ER stress markers and oxidative markers.

CONCLUSION

According to our results, ER stress markers (GRP78 and CHOP) increase significantly following ischemic injury. This elevation has the potential to be used diagnostically and also in prognostic terms due to the powerful correlation it exhibits with AMI-related ischemic injury.

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.

Neuroprotective and Anti-Apoptotic Effects of CSP-1103 in Primary Cortical Neurons Exposed to Oxygen and Glucose Deprivation

CSP-1103 (formerly CHF5074) has been shown to reverse memory impairment and reduce amyloid plaque as well as inflammatory microglia activation in preclinical models of Alzheimer's disease. Moreover, it was found to improve cognition and reduce brain inflammation in patients with mild cognitive impairment. Recent evidence suggests that CSP-1103 acts through a single molecular target, the amyloid precursor protein intracellular domain (AICD), a transcriptional regulator implicated in inflammation and apoptosis. We here tested the possible anti-apoptotic and neuroprotective activity of CSP-1103 in a cell-based model of post-ischemic injury, wherein the primary mouse cortical neurons were exposed to oxygen-glucose deprivation (OGD). When added after OGD, CSP-1103 prevented the apoptosis cascade by reducing cytochrome c release and caspase-3 activation and the secondary necrosis. Additionally, CSP-1103 limited earlier activation of p38 and nuclear factor κB (NF-κB) pathways. These results demonstrate that CSP-1103 is neuroprotective in a model of post-ischemic brain injury and provide further mechanistic insights as regards its ability to reduce apoptosis and potential production of pro-inflammatory cytokines. In conclusion, these findings suggest a potential use of CSP-1103 for the treatment of brain ischemia.

Chemical Chaperone 4-Phenylbutyric Acid Reduces Cardiac Ischemia/Reperfusion Injury by Alleviating Endoplasmic Reticulum Stress and Oxidative Stress

Background

Cardiovascular diseases are the leading cause of death in many countries and myocardial ischemia-reperfusion (I/R) injury is the cause of many serious heart diseases. Recent reports suggested that endoplasmic reticulum (ER) stress is associated with the progress of ischemia/reperfusion (I/R) injury. In a previous study, we illustrated that 4-phenylbutyric acid (4-PBA) reduces I/R-induced cell death in vitro through inhibiting the ER stress-initiated cell apoptosis. In the present study we investigated whether 4-PBA improves heart function in isolated rat hearts subjected to I/R and elucidated the potential mechanisms involved in 4-PBA-induced cardioprotective effects.

Material/Methods

The isolated rat hearts were subjected to global ischemia and reperfusion in the absence or presence of 4-PBA. Hemodynamic parameters (LVSP, LVEDP, ±dP/dt_max, and HR) were monitored and histopathological examination was applied. The biomarkers related to oxidative stress were detected by LDH, ROS, MDA, CK, SOD, and GSH-Px kits. A TUNEL apoptosis assay kit was used to detect apoptosis. The expression levels of ER stress and apoptosis proteins were evaluated by Western blotting.

Results

We found that 4-PBA (5 mM, 10 mM) pretreatment significantly attenuated cardiac dysfunction and depressed oxidative stress induced by I/R. Moreover, I/R activated the ER stress proteins Grp78 and PERK, which are all decreased by 4-PBA. 4-PBA pretreatment also inhibited the expression of CHOP, Caspase-12, and Bax, reduced the phosphorylation of JNK, and enhanced the expression of anti-apoptotic protein Bcl-2.

Conclusions

We elucidated the significant protective effects of 4-PBA against I/R injuries by inhibition of ER stress, oxidative stress, and their associated apoptosis.

ENDOPLASMIC RETICULUM STRESS IN SEPSIS

Sepsis is an enormous public health issue and the leading cause of death in critically ill patients in intensive care units. Overwhelming inflammation, characterized by cytokine storm, oxidative threats, and neutrophil sequestration, is an underlying component of sepsis-associated organ failure. Despite recent advances in sepsis research, there is still no effective treatment available beyond the standard of care and supportive therapy. To reduce sepsis-related mortality, a better understanding of the biological mechanism associated with sepsis is essential. Endoplasmic reticulum (ER), a subcellular organelle, is responsible for the facilitation of protein folding and assembly and involved in several other physiological activities. Under stress and inflammatory conditions, ER loses homeostasis in its function, which is termed ER stress. During ER stress, unfolded protein response (UPR) is activated to restore ER function to its normal balance. However, once stress is beyond the compensatory capacity of UPR or protracted, apoptosis would be initiated by triggering cell injuries, even cell death. As such, ER stress and UPR are reported to be implicated in several pathological and inflammatory conditions. Although the detrimental role of ER stress during infections has been demonstrated, there is growing evidence that ER stress participates in the pathogenesis of sepsis. In this review, we summarize current research in the context of ER stress and UPR signaling associated with sepsis and its related clinical conditions, such as trauma-hemorrhage and ischemia/reperfusion injury. We also discuss the potential implications of ER stress as a novel therapeutic target and prognostic marker in patients with sepsis.

Chemical chaperone 4-phenylbutyric acid protects H9c2 cardiomyocytes from ischemia/reperfusion injury by attenuating endoplasmic reticulum stress-induced apoptosis

Myocardial ischemia/reperfusion (I/R) is a potential contributor to high rates of mortality in several cardiovascular diseases. I/R initiates the unfolded protein response and endoplasmic reticulum (ER) stress, which may lead to apoptotic pathways and exaggerate I/R injury. 4‑phenylbutyric acid (4‑PBA), a low molecular weight, terminal aromatic substituted fatty acid, has been reported to function as an ER chaperone. The aim of the present study was to investigate whether 4‑PBA is able to reduce ER stress‑induced apoptosis and prevent cardiomyocyte damage during the process of I/R in vitro. Accordingly, the rat cardiomyocyte line, H9c2, was treated with hypoxia/reoxygenation as an I/R model in vitro. Myocardium apoptosis was determined with TUNEL staining. The expression of ER stress‑related proteins were examined by western blotting. The resulting data showed that I/R activates the ER stress proteins, glucose‑regulated protein 78, activating transcription factor 6 and protein kinase RNA‑like endoplasmic reticulum kinase, which were all reduced by pretreatment with 4‑PBA. In addition, pretreatment with 4‑PBA significantly inhibited the expression levels of pro‑apoptotic proteins, C/EBP homologous protein, B cell lymphoma (Bcl‑2)‑associated X protein and phosphorylated c‑Jun N‑terminal kinase, and enhanced the expression of the anti‑apoptotic protein Bcl‑2 (n=3; P<0.05). The data demonstrated that I/R initiates ER stress‑associated apoptotic pathways, and 4‑PBA pretreatment protected the cardiomyocytes from I/R‑induced cell death. To the best of our knowledge, the present study is the first to report on the cell repair mechanism of 4‑PBA against I/R damage in cardiomyocytes based on ER stress‑associated apoptotic pathways.

YiQiFuMai Powder Injection Ameliorates Cerebral Ischemia by Inhibiting Endoplasmic Reticulum Stress-Mediated Neuronal Apoptosis

YiQiFuMai (YQFM) powder injection as a modern preparation derived from Sheng Mai San, a traditional Chinese medicine, has been widely used in the treatment of cardiovascular and cerebrovascular diseases. However, its neuroprotective effect and underlying mechanism in cerebral ischemia remain to be explored. The present study was designed to investigate the neuroprotective effect of YQFM on endoplasmic reticulum (ER) stress-mediated neuronal apoptosis in the permanent middle cerebral artery occlusion- (MCAO-) injured mice and the oxygen-glucose deprivation- (OGD-) induced pheochromocytoma (PC12) cells. The results showed that single administration of YQFM (1.342 g/kg, i.p.) could reduce the brain infarction and improve the neurological deficits and the cerebral blood flow (CBF) after MCAO for 24 h in mice. Moreover, incubation with YQFM (100, 200, and 400 μg/mL) could increase the cell viability, decrease the caspase-3 activity, and inhibit the cell apoptosis in OGD-induced PC12 cells for 12 h. In addition, YQFM treatment could significantly modulate cleaved caspase-3 and Bcl-2 expressions and inhibit the expressions of ER stress-related marker proteins and signaling pathways in vivo and in vitro. In conclusion, our findings provide the first evidence that YQFM ameliorates cerebral ischemic injury linked with modulating ER stress-related signaling pathways, which provided some new insights for its prevention and treatment of cerebral ischemia diseases.

Role of Endoplasmic Reticulum Stress in Brain Damage After Cardiopulmonary Resuscitation in Rats

Postcardiac arrest syndrome yields poor neurological outcomes, but the mechanisms underlying this condition remain poorly understood. This study investigated whether endoplasmic reticulum (ER) stress-mediated apoptosis is induced in injured brain after resuscitation. Sprague-Dawley rats were subjected to 6 min of cardiac arrest (CA) and then resuscitated successfully. In the first experiment, animals were sacrificed 1, 3, 6, 12, or 24 h (n = 3 per group) after successful cardiopulmonary resuscitation. Brain tissues were analyzed by real-time polymerase chain reaction and Western blotting. In the second experiment, either dimethyl sulfoxide or salubrinal (Sal; 1 mg/kg), an ER stress inhibitor, was injected 30 min before the induction of CA (n = 10 per group). Neurological deficits were evaluated 24 h after CA. Brain specimens were analyzed using electron microscopy, terminal deoxynucleotidyl transferase dUTP nick end labeling assays and immunohistochemistry. We found that the messenger RNA and protein levels of glucose-regulated protein 78, X-box binding protein 1, C/EBP homologous protein, and caspase 12 were significantly elevated after resuscitation. We also observed that rats treated with Sal exhibited an improved neurological deficit score (32.3 ± 15.5 in the Sal group vs. 49.8 ± 20.9 in controls, P < 0.05). In addition, morphological improvements in the hippocampal ER were observed in the Sal group compared with the dimethyl sulfoxide group 24 h after reperfusion. Furthermore, in situ immunostaining revealed that markers of ER stress were significantly inhibited by Sal pretreatment. Our findings suggested that ER stress and the associated apoptotic pathways were activated in the hippocampus after resuscitation. Administration of Sal 30 min before cardiopulmonary resuscitation ameliorated neurological dysfunction 24 h after CA, possibly through the inhibition of ER stress after postresuscitation brain injury.

Cardioprotective effects of Notoginsenoside R1 against ischemia/reperfusion injuries by regulating oxidative stress- and endoplasmic reticulum stress- related signaling pathways

Background: Recent reports suggested the involvement of oxidative stress- and endoplasmic reticulum stress (ERS)-associated pathways in the progression of ischemia/reperfusion (I/R) injury. Notoginsenoside R1 (NGR1) is a novel saponin isolated from P. notoginseng, which has a history of prevention and treatment of cardiovascular diseases. Objective: We aimed to examine the cardioprotective effects of NGR1 on I/R-induced heart dysfunction ex vivo and in vitro. Methods: H9c2 cadiomyocytes were incubated with NGR1 for 24 h and exposed to hypoxia/reoxygenation. Isolated rat hearts were perfused by NGR1 for 15 min and then subjected to global ischemia/reperfusion. Hemodynamic parameters were monitored as left ventricular systolic pressure (LVSP), heart rate, and maximal rate of increase and decrease of left ventricular pressure (±dP/dt max/min). Results: NGR1 pretreatment prevents cell apoptosis and delays the onset of ERS by decreasing the protein expression levels of ERS-responsive proteins GRP78, P-PERK, ATF6, IRE, and inhibiting the expression of pro-apoptosis proteins CHOP, Caspase-12, and P-JNK. Besides, NGR1 scavenges free radical, and increases the activity of antioxidase. NGR1 inhibits Tunicamycin-induced cell death and cardic dysfunction. Conclusion: We elucidated the significant cardioprotective effects of NGR1 against I/R injuries, and demonstrated the involvement of oxidative stress and ERS in the protective effects of NGR1.

Nafamostat mesilate attenuates transient focal ischemia/reperfusion-induced brain injury via the inhibition of endoplasmic reticulum stress

Nafamostat mesilate (NM), a serine protease inhibitor, has a broad range of clinical applications that include use as an anticoagulant during hemodialysis in cerebral hemorrhage patients, as a hemoperfusion anticoagulant for patients with intravascular coagulation, hemorrhagic lesions, and hemorrhagic tendencies, and for the improvement of acute pancreatitis. However, the effects of NM on acute cerebral ischemia have yet to be investigated. Thus, the present study utilized a rat model in which transient middle cerebral artery occlusion (MCAO) was used to induce ischemic injury to investigate the effects of NM on infarct volume and histological and biological changes. NM (1mg/kg) was intravenously administered prior to and after the MCAO procedure. Compared to control rats, the administration of NM significantly decreased infarct size and the extent of brain edema after the induction of focal ischemia via MCAO. Additionally, NM treatment attenuated MCAO-induced neuronal degeneration and activation of microglia and astrocytes. NM treatment also inhibited the MCAO-induced expression levels of glucose-regulated protein 78 (GRP78), CATT/EBP homologous protein (CHOP), and p-eukaryotic initiation factor 2α (eIF2α), which are endoplasmic reticulum (ER) stress markers, in the cerebral cortex. The present findings demonstrate that NM exerts neuroprotective effects in the brain following focal ischemia via, at least in part, the inhibition of ER stress.

MicroRNAs regulate the chaperone network in cerebral ischemia

The highly evolutionarily conserved 70 kDa heat shock protein (HSP70) family was first understood for its role in protein folding and response to stress. Subsequently, additional functions have been identified for it in regulation of organelle interaction, of the inflammatory response, and of cell death and survival. Overexpression of HSP70 family members is associated with increased resistance to and improved recovery from cerebral ischemia. MicroRNAs (miRNAs) are important posttranscriptional regulators that interact with multiple target messenger RNAs (mRNA) coordinately regulating target genes, including chaperones. The members of the HSP70 family are now appreciated to work together as networks to facilitate organelle communication and regulate inflammatory signaling and cell survival after cerebral ischemia. This review will focus on the new concept of the role of the chaperone network in the organelle network and its novel regulation by miRNA.

Temperature increase exacerbates apoptotic neuronal death in chemically-induced ischemia

It is well-established that hyperthermia increases neuronal death and worsens stroke outcome. However, little is known about the mechanisms of how hyperthermia is involved in this neuronal death process. In the present study, we examined how temperature increase exacerbates neuronal death using a model of chemical ischemia. Chemical ischemia was induced by treating SH-SY5Y neuroblastoma cells with sodium azide and deoxyglucose. Temperature increase was treated by placing the cells at 37°C (control) and 41°C (experimental). Cell survival was determined by trypan blue assay and ATP levels were measured with ATP assay kits. Protein expression was detected by western blot. Treatment with sodium azide resulted in cell death in a dose-responsive manner. Increased temperature worsened the ATP depletion and cell volume shrinkage. Temperature increase also enhanced ER stress as demonstrated by the elevated level of phospho-eIF2α and C/EBP homologous protein (CHOP). Inhibition of CHOP expression significantly decreased sodium azide-induced neuronal death. In addition, the increased temperature intensified the activation of caspase-3, an apoptotic effector protease, and inhibition of capspase-3 significantly reduced cell death. These findings support that temperature increase worsened the neuronal death by depleting intracellular ATP, inducing ER stress response and activating apoptotic signal transduction.

CART attenuates endoplasmic reticulum stress response induced by cerebral ischemia and reperfusion through upregulating BDNF synthesis and secretion

Cocaine and amphetamine regulated transcript (CART), a neuropeptide, has shown strong neuroprotective effects against cerebral ischemia and reperfusion (I/R) injury in vivo and in vitro. Here, we report a new effect of CART on ER stress which is induced by cerebral I/R in a rat model of middle cerebral artery occlusion (MCAO) or by oxygen and glucose deprivation (OGD) in cultured cortical neurons, as well as a new functionality of BDNF in the neuroprotection by CART against the ER stress in cerebral I/R. The results showed that CART was effective in reducing the neuronal apoptosis and expression of ER stress markers (GRP78, CHOP and cleaved caspase12), and increasing the BDNF expression in I/R injury rat cortex both in vivo and in vitro. In addition, the effects of CART on ischemia-induced neuronal apoptosis and ER stress were suppressed by tyrosine receptor kinase B (TrkB) IgG, whereas the effects of CART on BDNF transcription, synthesis and secretion were abolished by CREB siRNA. This work suggests that CART is functional in inhibiting the cerebral I/R-induced ER stress and neuronal apoptosis by facilitating the transcription, synthesis and secretion of BDNF in a CREB-dependent way.

Multiple interacting cell death mechanisms in the mediation of excitotoxicity and ischemic brain damage: a challenge for neuroprotection

There is currently no approved neuroprotective pharmacotherapy for acute conditions such as stroke and cerebral asphyxia. One of the reasons for this may be the multiplicity of cell death mechanisms, because inhibition of a particular mechanism leaves the brain vulnerable to alternative ones. It is therefore essential to understand the different cell death mechanisms and their interactions. We here review the multiple signaling pathways underlying each of the three main morphological types of cell death--apoptosis, autophagic cell death and necrosis--emphasizing their importance in the neuronal death that occurs during cerebral ischemia and hypoxia-ischemia, and we analyze the interactions between the different mechanisms. Finally, we discuss the implications of the multiplicity of cell death mechanisms for the design of neuroprotective strategies.

Genetic determinants of neuronal vulnerability to apoptosis

Apoptosis is a common mode of cell death that contributes to neuronal loss associated with neurodegeneration. Single-nucleotide polymorphisms (SNPs) in chromosomal DNA are contributing factors dictating natural susceptibility of humans to disease. Here, the most common SNPs affecting neuronal vulnerability to apoptosis are reviewed in the context of neurological disorders. Polymorphic variants in genes encoding apoptotic proteins, either from the extrinsic (FAS, TNF-α, CASP8) or the intrinsic (BAX, BCL2, CASP3, CASP9) pathways could be highly valuable in the diagnosis of neurodegenerative diseases and stroke. Interestingly, the Arg72Pro SNP in TP53, the gene encoding tumor suppressor p53, was recently revealed a biomarker of poor prognosis in stroke due to its ability to modulate neuronal apoptotic death. Search for new SNPs responsible for genetic variability to apoptosis will ensure the implementation of novel diagnostic and prognostic tools, as well as therapeutic strategies against neurological diseases.

Caspase inhibitors: prospective therapies for stroke

In ischemic stroke, apoptosis persists for days to weeks after the onset of an ischemic event. Cysteine-ASPartic proteASEs (caspases) are key mediators of apoptosis and neurodegeneration in stroke. The impact of caspase activity is not restricted to neuronal death, as caspases can exacerbate inflammation and alter glial function. Thus, caspases are logical therapeutic targets for this disease, but they have never been clinically evaluated due to a paucity of ideal drug candidates. Recent developments in caspase inhibition and drug delivery offer novel neuroprotective strategies for stroke, which are deliberated in this review.

3-Bromo-7-nitroindazole attenuates brain ischemic injury in diabetic stroke via inhibition of endoplasmic reticulum stress pathway involving CHOP

AIMS

The role of nitric oxide (NO) and endoplasmic reticulum (ER) stress has been implicated in the pathogenesis of cerebral ischemic/reperfusion (I/R) injury and diabetes. The aim of the study was to investigate the neuroprotective potential of 3-bromo-7-nitroindazole (3-BNI), a potent and selective neuronal nitric oxide synthase (nNOS) inhibitor against ER stress and focal cerebral I/R injury associated with comorbid type 2 diabetes in-vivo.

MAIN METHODS

Type 2 diabetes was induced by feeding high-fat diet and streptozotocin (35 mg/kg) treatment in rats. Focal cerebral ischemia was induced by 2h middle cerebral artery occlusion (MCAO) followed by 22 h of reperfusion. Immunohistochemistry and western blotting methods were employed for the detection and expression of ER stress/apoptosis markers [78 kDa glucose regulated protein (GRP78) and CCAAT/enhancer binding protein homologous protein (CHOP)]. TUNEL assay for DNA fragmentation was also performed.

KEY FINDINGS

The diabetic rats subjected to cerebral I/R had prominent neurological damage and functional deficits compared with sham-operated rats. Massive DNA fragmentation was observed in ischemic penumbral region of diabetic brains. Concomitantly, the enhanced immunoreactivity and expression of ER stress/apoptosis markers were noticed. 3-BNI (30 mg/kg, i.p.) treatment significantly inhibited the cerebral infarct, edema volume and improved functional recovery of neurological deficits. The neuroprotection was further evident by lesser DNA fragmentation with a concomitant reduction of GRP78 and CHOP.

SIGNIFICANCE

The study demonstrates the neuroprotective potential of 3-BNI in diabetic stroke model which may be partly due to inhibition of ER stress pathway involving CHOP.

miR-181 regulates GRP78 and influences outcome from cerebral ischemia in vitro and in vivo

MicroRNAs (miRNA) are short (~22nt) single stranded RNAs that downregulate gene expression. Although recent studies indicate extensive miRNA changes in response to ischemic brain injury, there is currently little information on the roles of specific miRNAs in this setting. Heat shock proteins (HSP) of the HSP70 family have been extensively studied for their multiple roles in cellular protection, but there is little information on their regulation by miRNAs. We used bioinformatics to identify miR-181 as a possible regulator of several HSP70 family members. We validated GRP78/BIP as a target by dual luciferase assay. In response to stroke in the mouse we find that miR-181 increases in the core, where cells die, but decreases in the penumbra, where cells survive. Increased levels of miR-181a are associated with decreased GRP78 protein levels, but increased levels of mRNA, implicating translational arrest. We manipulated levels of miR-181a using plasmid overexpression of pri-miR-181ab or mimic to increase, and antagomir or inhibitor to reduce levels. Increased miR-181a exacerbated injury both in vitro and in the mouse stroke model. Conversely, reduced levels were associated with reduced injury and increased GRP78 protein levels. Studies in C6 cells show that if GRP78 levels are maintained miR-181a no longer exerts a toxic effect. These data demonstrate that miR-181 levels change in response to stroke and inversely correlate with levels of GRP78. Importantly, reducing or blocking miR-181a protects the brain from stroke.

N-acetylcysteine attenuates leukocytic inflammation and microvascular perfusion failure in critically ischemic random pattern flaps

INTRODUCTION

Microcirculatory dysfunction causes ischemia resulting in tissue necrosis. N-acetylcysteine (NAC) has been shown capable of protecting tissue from ischemic necrosis. However, the mechanism of action of NAC is yet not fully understood.

OBJECTIVE

Herein, we studied whether NAC is capable of attenuating microvascular perfusion failure in critically ischemic musculo-cutaneous tissue.

MATERIAL AND METHODS

A laterally based skin flap was elevated in the dorsum of C57BL/6 mice and fixed into a dorsal skinfold chamber. Arteriolar perfusion, functional capillary density, leukocytic inflammation, apoptotic cell death, and non-perfused tissue area were repetitively analyzed over 10 days by intravital fluorescence microscopy. Treatment with either 100mg/kg NAC or saline (control) was started 30 min before surgery and was continued until day 10 after flap elevation.

RESULTS

Surgery induced leukocytic inflammation, microvascular perfusion failure, apoptosis, and tissue perfusion failure. NAC was capable of significantly attenuating the area of non-perfused tissue. This was associated by a marked arteriolar dilation and an increased capillary perfusion. NAC further reduced the ischemia-associated leukocytic response and significantly attenuated apoptotic cell death in all areas of the flap.

CONCLUSION

NAC is effective to attenuate leukocytic inflammation and microvascular perfusion failure in critically ischemic tissue. Thus, NAC treatment may represent a promising approach to improve the outcome of ischemically endangered flap tissue.