Expression of HSP70 in cerebral ischemia and neuroprotetive action of hypothermia and ketoprofen

Regulation of blood-brain barrier integrity by brain microvascular endothelial cells in ischemic stroke: A therapeutic opportunity

Stroke is the second leading cause of death from cardiovascular diseases. Brain microvascular endothelial cells (BMECs) are crucial in the treatment of cerebral ischemic stroke, as their functional status directly affects the integrity of the blood-brain barrier (BBB). This review systematically discusses the central role of BMECs in ischemia. The mitochondrial dysfunction and activation of apoptosis/necrosis pathways in BMECs directly disrupt the integrity of the BBB and the degradation of junctional complexes (such as TJs and AJs) further exacerbates its permeability. In the neurovascular unit (NVU), astrocytes, microglia, and pericytes regulate the function of BMECs by secreting cytokines (such as TGF-β and VEGF), showing dual effects of promoting repair and damage. The dynamic changes of transporters, including those from the ATP-binding cassette and solute carrier families, as well as ion channels and exchangers, such as potassium and calcium channels, offer novel insights for the development of targeted drug delivery systems.

Cell-Permeable HSP70 Protects Neurons and Astrocytes Against Cell Death in the Rotenone-Induced and Familial Models of Parkinson's Disease

Heat shock protein 70 (HSP70) is activated under stress response. Its involvement in cell protection, including energy metabolism and quality control makes it a promising pharmacological target. A strategy to increase HSP70 levels inside the cells is the application of recombinant HSP70. However, cell permeability and functionality of these exogenously applied proteins inside the cells is still disputable. Here, using fluorescence- labeled HSP70, we have studied permeability and distribution of HSP70 inside primary neurons and astrocytes, and how exogenous HSP70 changes mitochondrial metabolism and mitophagy. We have found that exogenous recombinant HSP70 can penetrate the neurons and astrocytes and distributes in mitochondria, lysosomes and in lesser degree in the endoplasmic reticulum. HSP70 increases mitochondrial membrane potential in control neurons and astrocytes, and in fibroblasts of patients with familial Parkinson´s disease (PD) with PINK1 and LRRK2 mutations. Increased mitochondrial membrane potential was associated with higher mitochondrial ROS production and activation of mitophagy. Importantly, preincubation of the cells with HSP70 protected neurons and astrocytes against cell death in a toxic model of PD induced by rotenone, and in the PINK1 and LRRK2 PD human fibroblasts. Thus, exogenous recombinant HSP70 is cell permeable, and acts as endogenous HSP70 protecting cells in the case of toxic model and familial forms of Parkinson's Disease.

Dynamically changed HSP70 after reperfusion following cerebral infarction in human and rats: correlation with p38 MAPK

We aimed to clarify the correlation between dynamic change of blood HSP70 and the prognosis of thrombolysis in human and rats, so as to explain the neuroprotection and early warning role of HSP70 in cerebral ischemia-reperfusion. Forty-two patients with acute ischemic stroke were divided into two groups according to the time from onset to thrombolytic therapy: 0 h-3 h (27 patients) and 3-4.5 h group (15 patients). The level of HSP70 in serum before and after thrombolysis was detected by ELISA. Furthermore, a rat model was also used to mimic the ischemic stroke and reperfusion. Peripheral blood of rat samples was collected to detect the level of HSP70 using Elisa. Several signal proteins from MAPK signaling pathway including JNK, p38, ERK (p42/44) were detected at different time points by Western blot of brain tissue. Patients who underwent thrombolytic therapy within 0-3 h had the highest HSP70 level at 1 h after thrombolysis. The higher HSP70 after thrombolysis, the better the patient prognosis. NIHSS scores showed HSP70 was positively correlated with cerebral ischemia. The levels of ERK family (p42/44 MAPK) and p-JNK were decreased gradually along with the time suffering cerebral ischemia. P-ERK, JNK, p-p38 had dynamic changes with increased ischemic time in the middle cerebral artery occlusion model. Dynamic change of HSP70 level in blood may be a biological index that reflects the functional condition of cell survival for cerebral ischemia and estimating the prognostic conditions. Importantly, HSP70 levels in blood were positively correlated with the p38 MAPK pathway in brain tissue.

Advanced Diagnostic Tools in Hypothermia-Related Fatalities-A Pathological Perspective

BACKGROUND AND OBJECTIVES

Although classical gross features are known in hypothermia victims, they lack specific diagnosis features. The aim of our study was to reveal specific brain and lung pathological features in a group of hypothermia-related fatalities.

MATERIALS AND METHODS

The study group comprised 107 cases from our files associated with hypothermia. Routine hematoxylin-eosin (H&E) staining and postmortem immunohistochemistry were performed.

RESULTS

The microscopic cerebral exam revealed diffuse perineuronal and perivascular edema, gliosis, mononuclear cell infiltration, acute brain injuries, focal neuronal ischemia, lacunar infarction, and variable hemorrhages. Variable alveolar edema, pulmonary emphysema, intra-alveolar and/or pleural hemorrhage, and bronchopneumonia, as well as other pre-existing lesions, were identified in lung tissue samples. Glial cells displayed S100β expression, while neurons showed moderate Hsp70 immunopositivity. Alveolar basal membranes exhibited diffuse ICAM-1 positive expression, while ICAM-1 and AQP-1 positivity was observed in the alveolar septum vascular endothelium. Statistical analysis revealed a significant correlation between S100β and Hps70 immunoexpression and cerebral pathological features, between ICAM-1 immunoexpression and alveolar edema and pulmonary emphysema, and between AQP-1 immunoexpression and pulmonary emphysema.

CONCLUSIONS

Our results add supplementary data to brain and lung pathological findings in hypothermia-related fatalities, with potential therapeutic value in hypothermia patients.

Microglia Exhibit Distinct Heterogeneity Rather than M1/M2 Polarization within the Early Stage of Acute Ischemic Stroke

The classification of microglial M1/M2 polarization in the acute phase of ischemic stroke remains controversial, which has limited further advances in neuroprotective strategy. To thoroughly assess the microglial phenotypes, we made the middle cerebral artery occlusion model in mice to simulate the acute pathological processes of ischemic stroke from normal conditions to acute cerebral ischemia and then to the early reperfusion period. The temporal changes in gene profiles, cell subtypes, and microglial function were comprehensively analyzed using single-cell RNA sequencing. We identified 37,614 microglial cells and divided them into eight distinct subpopulations. Mic_home, Mic_pre1, and Mic_pre2 subpopulations were three clusters mainly composed of cells from the control samples, in which Mic_home was a homeostatic subpopulation characterized by high expression of Hpgd and Tagap, and Mic_pre1 and Mic_pre2 were two clusters with preliminary inflammatory activation characteristics marked by P2ry13 and Wsb1 respectively. Mic_M1L1 and Mic_M1L2 subpopulations exhibited M1-like polarization manifested by the upregulation of inflammatory genes after ischemic stroke, while the intrinsic heterogeneity on the level of inflammatory responses and neurotrophic support properties was observed. Moreover, we identified three unique clusters of cells with low inflammation levels. Mic_np1, Mic_np2, and Mic_np3 were characterized by high expression of Arhgap45, Rgs10, and Pkm respectively. However, these cells did not show significant M2-like characteristics and their classic microglia function was also attenuated. These subpopulations exhibited higher activation of neuropeptide functional pathways. At last, we performed cell-cell communication analysis and identified major couplings contributing to the interaction between microglia and other cell populations. In summary, our study elucidated the temporal heterogeneity of microglia in the acute phase of ischemic stroke, which may facilitate the identification of effective neuroprotective targets to curb ischemic damage at an early stage.

Predictive Value of Heat-Shock Protein Gene Expression on Severe Neonatal Hypoxic-Ischemic Encephalopathy

This study aims to evaluate significant gene expression in severe hypoxic ischemic encephalopathy (HIE) in newborns, which can be used as a predictable measure for high-risk HIE infants. The study prospectively recruited 77 inborn near-term or term HIE newborns between January 2018 and December 2020. We measured six different genes within 6 h of life among the HIE infants and compared the gene levels between the mild- and severe-HIE groups. Among these, 64 HIE infants (83.1%) did not receive therapeutic hypothermia (TH) because they were categorized as mild HIE, and the 13 remaining (16.9%) infants were categorized as ≥ moderate-HIE group and received TH. More abnormal MRI findings, seizure, and use of anti-convulsant were more found in the ≥ moderate = HIE group along with longer mechanical ventilation days and hospitalization. Heat-shock protein 70 family 1 A (HSPA1A) and serpin family H member 1 (SERPINH1) genes, which encode heat-shock protein (HSP) 70 and 47, respectively, were significantly elevated in the ≥ moderate-HIE, seizure, and abnormal MRI groups. HSP 70 and 47 were significantly elevated in the severe-HIE group, possibly playing protective roles in inhibiting exacerbated neuroinflammation and maintaining a cellular homeostasis. At 18–24 months, ≥ moderate-HIE group manifested a significant language delay.

Molecular chaperones in the brain endothelial barrier: neurotoxicity or neuroprotection?

Brain microvascular endothelial cells (BMECs) interact with astrocytes and pericytes to form the blood-brain barrier (BBB). Their compromised function alters the BBB integrity, which is associated with early events in the pathogenesis of cancer, neurodegenerative diseases, and epilepsy. Interestingly, these conditions also induce the expression of heat shock proteins (HSPs). Here we review the contribution of major HSP families to BMEC and BBB function. Although investigators mainly report protective effects of HSPs in brain, contrasted results were obtained in BMEC, which depend both on the HSP and on its location, intra- or extracellular. The therapeutic potential of HSPs must be scrupulously analyzed before targeting them in patients to reduce the progression of brain lesions and improve neurologic outcomes in the long term.-Thuringer, D., Garrido, C. Molecular chaperones in the brain endothelial barrier: neurotoxicity or neuroprotection?

The differential neuroprotection of HSP70-hom gene single nucleotide polymorphisms: In vitro (neuronal hypoxic injury model) and in vivo (rat MCAO model) studies

To investigate the effect of HSP70-hom+2437 single nucleotide polymorphisms (SNPs) on hypoxia and ischemia condition, we constructed the neuronal hypoxic injury model and the rat middle cerebral artery occlusion (MCAO) model to compare the inhibition rate of neurons and detect the infarct volume as well as the expression of related apoptotic proteins in order to explore the possible mechanisms. The neuroblastoma cells SHSY5Y were divided into the OE (transfected with the C allele) group, OEmu (transfected with the T allele) group and negative control (NC, transfected with the empty lentiviral vector CON195) group. Varying degrees of hypoxia were induced by deferoxamine (DFO). The inhibition rate of hypoxic neurons and the expression of related apoptotic proteins were detected in the three genotype groups. While in the rat MCAO model, we built five groups including the sham group, the blank control group (injected with physiological saline), the negative control group (injected with lentivirus and physiological saline), the C allele group and the T allele group (injected with lentivirus overexpressing C and T allele). The MCAO model operation was then underwent in all five groups, the infarct volume by TTC staining and the expression of related apoptotic proteins were detected after 24 h. The results in neuronal hypoxic injury model showed a significant difference in the inhibition rate between the three groups (P < 0.05), and the average inhibition rates for the OEmu, OE and NC groups were 13.2%, 19.2% and 23.3%, respectively. The inhibition rates also differed between lower and higher DFO concentrations (P < 0.05). Compared with the NC group, Bax decreased significantly in the OE and OEmu groups, whereas PI3K and HSPA1L (HSP70-hom) increased. However, the expression of Bax in the OEmu group decreased significantly more than in the OE group, whereas PI3K and HSPA1L levels showed no difference between the two groups. Corresponding with the results above, overexpressing HSP70-hom could reduce the infarct volume of ischemic injury by TTC staining in rat MCAO model and the T allele group also had less infarct volume than C allele group. Compared with the sham group, blank control group and negative control group, Bax decreased significantly in the C and T allele groups, while HSPA1L and p- AKT increased. Furthermore, the expression of Bax in the T allele group decreased significantly more than that in the C allele group, while there were no significant differences in HSPA1L and p-AKT levels between the two groups. Therefore, the overexpression of HSP70-hom+2437 could play a protective role in hypoxic neurons and ischemic brain tissue by upregulating the expression of HSPA1L and PI3K/p-AKT and downregulating the expression of BAX. The neuroprotective effect of the T allele was stronger than that of the C allele, which may be related to the strengthened downregulation of BAX.

Understanding Retinal Changes after Stroke

Stroke is the fifth leading cause of death and disability in the United States. According to World Heart Federation, every year, 15 million people suffer from stroke worldwide out of which nearly 6 million people die and another 5 million people are disabled. Out of many organs affected after stroke, one of them is eye. Majority of the stroke victims suffer vision loss due to stroke-induced retinal damage. However, stroke-induced retinal damage and microvascular changes have not been given paramount importance in understanding stroke pathophysiology and predicting its occurrence. Retinal imaging can be a very powerful tool to understand and predict stroke. This review will highlight the importance of retinal changes in predicting occurrence of stroke, major retinal changes, the relationship between retinal diseases and stroke and moreover, molecular mechanisms delineating the stroke induced-retinal changes and therapeutics associated with it.

Proteomic analysis and comparison of intra‑ and extracranial cerebral atherosclerosis responses to hyperlipidemia in rabbits

The present study aimed to investigate protein expression levels of intra‑ and extracranial atherosclerosis in rabbits following administration of a high‑fat diet. Rabbits were randomly divided into control (group A; n=9) and high‑fat diet (group B; n=9) groups. At week 12, tissues were sectioned from the common carotid artery (CCA) and middle cerebral artery (MCA). Pathological analysis was performed. Differential protein expression levels were examined by 2‑D gel electrophoresis (2‑DE) and mass spectrometry (MS) analysis and validated by western blotting. Serum lipid levels, the intima‑media thickness (IMT) and degree of atherosclerosis of the CCA and MCA were increased at week 12 in the high‑fat diet group compared with rabbits that received a normal diet. 2‑DE and MS analysis of the protein extracted from CCA and MCA detected >439 different proteins; the expression of 25 proteins was altered, and 8 proteins [albumin A chain, tropomyosin α‑1 chain (TPM1), heat shock protein 70 (HSP70), α‑smooth muscle actin, β‑galactose binding agglutinin, TPM4 isoform 2, cell keratin 9, single octylic acid glyceride β‑2) demonstrated significant alterations in expression levels. Due to limited antibody sources, only three differentially expressed proteins (TPM1, HSP70 and α‑smooth muscle actin) were examined by western blotting. The results of our previous study demonstrated that hyperlipidemia affected the IMT of intracranial and extracranial cerebral arteries. In the present study, protein expression levels of TPM1 and α‑smooth muscle actin from extracranial cerebral arteries were significantly increased compared with intracranial cerebral arteries; however, protein expression levels of HSP70 from intracranial cerebral arteries was increased compared with extracranial cerebral arteries. The differences may be closely associated with cell proliferation and metastasis, and oxidoreduction, in intra‑ and extracranial cerebral atherosclerosis. HSP70 may have protective properties against atherosclerosis via underlying anti‑inflammatory mechanisms, furthermore, differential protein expression levels (TPM1, HSP70 and α‑smooth muscle actin) between intra‑ and extracranial cerebral arteries may facilitate the identification of novel biological markers for the diagnosis and treatment of cerebral arteriosclerosis.

Protective effects of ginsenoside Rg1 against hydrogen peroxide-induced injury in human neuroblastoma cells

The active ingredient of ginseng, ginsenosides Rg1, has been shown to scavenge free radicals and improve antioxidant capacity. This study hypothesized that ginsenosides Rg1 has a protective role in human neuroblastoma cells injured by H2O2. Ginsenosides Rg1 at different concentrations (50 and 100 μM) was used to treat H2O2 (150 μM)-injured SH-SY5Y cells. Results demonstrated that ginsenoside Rg1 elevated the survival rate of SH-SY5Y cells injured by H2O2, diminished the amount of leaked lactate dehydrogenase, and increased superoxide dismutase activity. Ginsenoside Rg1 effectively suppressed caspase-3 immunoreactivity, and contributed to heat shock protein 70 gene expression, in a dose-dependent manner. These results indicate that ginsenoside Rg1 has protective effects on SH-SY5Y cells injured by H2O2 and that its mechanism of action is associated with anti-oxidation and the inhibition of apoptosis.

Combination of therapeutic hypothermia and other neuroprotective strategies after an ischemic cerebral insult

Abrupt deprivation of substrates to neuronal tissue triggers a number of pathological events (the “ischemic cascade”) that lead to cell death. As this is a process of delayed neuronal cell death and not an instantaneous event, several pharmacological and non-pharmacological strategies have been developed to attenuate or block this cascade. The most promising neuroprotectant so far is therapeutic hypothermia and its beneficial effects have inspired researchers to further improve its protective benefit by combining it with other neuroprotective agents. This review provides an overview of all neuroprotective strategies that have been combined with therapeutic hypothermia in rodent models of focal cerebral ischemia. A distinction is made between drugs interrupting only one event of the ischemic cascade from those mitigating different pathways and having multimodal effects. Also the combination of therapeutic hypothermia with hemicraniectomy, gene therapy and protein therapy is briefly discussed. Furthermore, those combinations that have been studied in a clinical setting are also reviewed.

Role of induced hypothermia in thoracoabdominal aortic aneurysm surgery

For more than 50 years, hypothermia has been used in aortic surgery as a tool for neuroprotection. Hypothermia has been introduced into thoracoabdominal aortic aneurysm (TAAA) surgery by many cardiovascular centers to protect the body's organs, including the spinal cord. Numerous publications have shown that hypothermia can prevent immediate and delayed motor dysfunction after aortic cross-clamping. Here, we reviewed the historical application of hypothermia in aortic surgery, role of hypothermia in preclinical studies, cellular and molecular mechanisms by which hypothermia confers neuroprotection, and the role of systemic and regional hypothermia in clinical protocols to reduce and/or eliminate the devastating consequences of ischemic spinal cord injury after TAAA repair.