Anti-inflammatory effects of the 70 kDa heat shock protein in experimental stroke

Acetate Abates Arsenic-Induced Male Reproductive Toxicity by Suppressing HDAC and Uric Acid-Driven Oxido-inflammatory NFkB/iNOS/NO Response in Rats

Arsenic is associated with male reproductive toxicity through histone deacetylation and oxido-inflammatory injury. Notwithstanding, short-chain fatty acids such as acetate exert anti-oxido-inflammatory activities and inhibit histone deacetylation. This study investigated the impact of acetate on arsenic-induced male reproductive toxicity. Forty eight adult male Wistar rats were allotted into any of these four groups (n = 12 rats per group): vehicle-treated, sodium acetate-treated, arsenic-exposed, and arsenic-exposed + sodium acetate-treated. The results revealed that arsenic exposure prolonged the latencies of mount, intromission, and ejaculation and reduced the frequencies of mount, intromission, and ejaculation, as well as mating and fertility indices, litter size and weight, anogenital distance, anogenital index, and survival rate in male F1 offspring at weaning. Also, arsenic reduced the circulating levels of gonadotropin-releasing hormone, luteinizing hormone, follicle-stimulating hormone, and testosterone and testicular 3β-hydroxysteroid dehydrogenase and 17β-hydroxysteroid dehydrogenase activities. In addition, arsenic reduced the daily and total spermatid production, sperm count, motility, and viability but increased the percentage of sperm cells with abnormal morphology. Furthermore, arsenic increased testicular xanthine oxidase activity, uric acid, and malondialdehyde levels, and reduced glutathione content, superoxide dismutase and catalase activities, total antioxidant capacity, and Nrf2 level. More so, arsenic exposure increased testicular iNOS activity and nitric oxide (NO), TNF-α, IL-1β, IL-6, and NFkB levels as well as Bax, caspase 9, and caspase 3 activities, and reduced Bcl-2. These findings were associated with arsenic-induced increase in testicular arsenic concentration, histone deacetylase activity, and reduced testicular weight. Histopathological examination revealed that arsenic also disrupted testicular histoarchitecture, which was accompanied by altered testicular planimetry and reduced spermatogenic cells. Notwithstanding, sodium acetate alleviated arsenic-induced sexual dysfunction as well as biochemical and histological alterations. These were accompanied acetate-driven downregulation of histone deacetylase (HDAC) activity. Succinctly, acetate attenuated arsenic-induced male reproductive toxicity by suppressing HDAC and uric acid-driven oxido-inflammatory NFkB/iNOS/NO response.

Sodium acetate prevents testicular damage in Wistar rats subjected to testicular ischaemia/reperfusion injury

AIMS

The aim of this study was to investigate the potential antioxidant, anti-inflammatory, and sperm function-preserving properties of sodium acetate (ACE), a histone deacetylase (HDAC) inhibitor, in a rat model of testicular torsion/detorsion (T/D).

MAIN METHODS

Littermate Wistar rats of identical weight were subjected to sham surgery or testicular T/D by rotating the left testis at 720° around its axis along the spermatic cord clockwise and fixing it in this position for two and a half hours. 1 h before detorsion, T/D + ACE-treated rats were treated with ACE (200 mg/kg/day, per os) while T/D rats were vehicle-treated by administering 0.5 mL of distilled water. After 72 h, animals were euthanized, and the left testes were harvested for bio-molecular and histological analysis.

KEY FINDINGS

Acetate administration attenuated T/D-induced rises in serum and testicular HDAC and testicular xanthine oxidase, uric acid, MDA, GSSG, MPO, TNF-α, IL-1β, IL-6, NFkB, HIF-1α, and VCAM-1. In addition, acetate treatment alleviated T/D-induced decline in sperm quality (count, motility, viability, and normal morphology) and testicular 3β-HSD, 17β-HSD, testosterone, GSH, GSH/GSSG, SOD, catalase, GPx, GST, Nrf2, and HO-1. Furthermore, acetate prevented T/D-distorted testicular histoarchitecture and spermatogenic germ cell loss.

SIGNIFICANCE

Sodium acetate during the post-ischaemic phase of testicular T/D may be beneficial in preventing I/R injury and maintaining fertility.

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.

Heat shock protein 70 protects the lungs from hyperoxic injury in a neonatal rat model of bronchopulmonary dysplasia

Hyperoxia plays a significant role in the pathogenesis of lung injury, such as bronchopulmonary dysplasia (BPD), in premature infants or newborns. BPD management aims to minimize further injury, provide an optimal environment to support growth and recovery. In clinic neonatal care, we need a new therapy for BPD. Heat shock protein 70 (Hsp70) inhibit cell apoptosis and promote cell repair allowing cells to survive lethal injury. We hypothesized that Hsp70 could be used to prevent hyperoxia related BPD in the neonatal rat model through its anti-apoptotic and anti-inflammatory effects. In this study, we explored the effect of Hsp70 on hyperoxia-induced lung injury using neonatal rats. Neonatal Wistar rats were delivered naturally at full term of gestation and were then pooled and randomly assigned to several groups to receive heat stimulation (41°C for 20 min) or room temperature conditions. The Hsp70 group received recombinant Hsp70 intraperitoneally (200 μg/kg, daily). All newborn rats were placed under hyperoxic conditions (85% oxygen) for 21 days. Survival rates in both heat-hyperoxia and Hsp70-hyperoxia groups were higher than those in the hyperoxia group (p < 0.05). Both endogenous and exogenous Hsp70 could reduce early apoptosis of alveolar cells under hyperoxia. Additionally, there were less macrophage infiltration in the lung of the Hsp70 groups (p < 0.05). Heat stress, heat shock proteins, and exogenous recombinant Hsp70 significantly increased the survival rate and reduced pathological hyperoxia induced lung injuries in the development of BPD. These results suggest that treating hyperoxia-induced lung injury with Hsp70 may reduce the risk of developing BPD.

Glutamine supplementation accelerates functional recovery of EDL muscles after injury by modulating the expression of S100 calcium-binding proteins

The aim of the current study was to investigate the effect of glutamine supplementation on the expression of HSP70 and the calcium-binding proteins from the S100 superfamily in the recovering extensor digitorum longus (EDL) muscle after injury. Two-month-old Wistar rats were subjected to cryolesion of the EDL muscle and then randomly divided into two groups (with or without glutamine supplementation). Starting immediately after the injury, the supplemented group received daily doses of glutamine (1 g/kg/day, via gavage) for 3 and 10 days orally. Then, muscles were subjected to histological, molecular, and functional analysis. Glutamine supplementation induced an increase in myofiber size of regenerating EDL muscles and prevented the decline in maximum tetanic strength of these muscles evaluated 10 days after injury. An accelerated upregulation of myogenin mRNA levels was detected in glutamine-supplemented injured muscles on day 3 post-cryolesion. The HSP70 expression increased only in the injured group supplemented with glutamine for 3 days. The increase in mRNA levels of NF-κB, the pro-inflammatory cytokines IL-1β and TNF-α, and the calcium-binding proteins S100A8 and S100A9 on day 3 post-cryolesion in EDL muscles was attenuated by glutamine supplementation. In contrast, the decrease in S100A1 mRNA levels in the 3-day-injured EDL muscles was minimized by glutamine supplementation. Overall, our results suggest that glutamine supplementation accelerates the recovery of myofiber size and contractile function after injury by modulating the expression of myogenin, HSP70, NF-κB, pro-inflammatory cytokines, and S100 calcium-binding proteins.

Involvement of heat shock proteins HSP70 in the mechanisms of endogenous neuroprotection: the prospect of using HSP70 modulators

This analytical review summarizes literature data and our own research on HSP70-dependent mechanisms of neuroprotection and discusses potential pharmacological agents that can influence HSP70 expression to improve neurological outcomes and effective therapy. The authors formed a systemic concepts of the role of HSP70-dependent mechanisms of endogenous neuroprotection aimed at stopping the formation of mitochondrial dysfunction, activation of apoptosis, desensitization of estrogen receptors, reduction of oxidative and nitrosative stress, prevention of morpho-functional changes in brain cells during cerebral ischemia, and experimentally substantiated new target links for neuroprotection. Heat shock proteins (HSPs) are an evolutionarily integral part of the functioning of all cells acting as intracellular chaperones that support cell proteostasis under normal and various stress conditions (hyperthermia, hypoxia, oxidative stress, radiation, etc.). The greatest curiosity in conditions of ischemic brain damage is the HSP70 protein, as an important component of the endogenous neuroprotection system, which, first of all, performs the function of intracellular chaperones and ensures the processes of folding, holding and transport of synthesized proteins, as well as their degradation, both under normoxic conditions and stress-induced denaturation. A direct neuroprotective effect of HSP70 has been established, which is realized through the regulation the processes of apoptosis and cell necrosis due to a long-term effect on the synthesis of antioxidant enzymes, chaperone activity, and stabilization of active enzymes. An increase in the level of HSP70 leads to the normalization of the glutathione link of the thiol-disulfide system and an increase in the resistance of cells to ischemia. HSP 70 is able to activate and regulate compensatory ATP synthesis pathways during ischemia. It was found that in response to the cerebral ischemia formation, HIF-1a is expressed, which initiates the launch of compensatory mechanisms for energy production. Subsequently, the regulation of these processes switches to HSP70, which "prolongs" the action of HIF-1a, and also independently maintains the expression of mitochondrial NAD-dependent malate dehydrogenase activity, thereby maintaining the activity of the malate-aspartate shuttle mechanism for a long time. During ischemia of organs and tissues, HSP70 performs a protective function, which is realized through increased synthesis of antioxidant enzymes, stabilization of oxidatively damaged macromolecules, and direct anti-apoptotic and mitoprotective action. Such a role of these proteins in cellular reactions during ischemia raises the question of the development of new neuroprotective agents which are able to provide modulation/protection of the genes encoding the synthesis of HSP 70 and HIF-1a proteins. Numerous studies of recent years have noted the important role of HSP70 in the implementation of the mechanisms of metabolic adaptation, neuroplasticity and neuroprotection of brain cells, so the positive modulation of the HSP70 system is a perspective concept of neuroprotection, which can improve the efficiency of the treatment of ischemic-hypoxic brain damage and be the basis for substantiating of the feasibility of using of HSP70 modulators as promising neuroprotectors.

Hippocampal region-specific endogenous neuroprotection as an approach in the search for new neuroprotective strategies in ischemic stroke. Fiction or fact?

Ischemic stroke is the leading cause of death and long-term disability worldwide, and, while considerable progress has been made in understanding its pathophysiology, the lack of effective treatments remains a major concern. In that context, receiving more and more consideration as a promising therapeutic method is the activation of natural adaptive mechanisms (endogenous neuroprotection) - an approach that seeks to enhance and/or stimulate the endogenous processes of plasticity and protection of the neuronal system that trigger the brain's intrinsic capacity for self-defence. Ischemic preconditioning is a classic example of endogenous neuroprotection, being the process by which one or more brief, non-damaging episodes of ischemia-reperfusion (I/R) induce tissue resistance to subsequent prolonged, damaging ischemia. Another less-known example is resistance to an I/R episode mounted by the hippocampal region consisting of CA2, CA3, CA4 and the dentate gyrus (here abbreviated to CA2-4, DG). This can be contrasted with the ischemia-vulnerable CA1 region. There is not yet a good understanding of these different sensitivities of the hippocampal regions, and hence of the endogenous neuroprotection characteristic of CA2-4, DG. However, this region is widely reported to have properties distinct from CA1, and capable of generating resistance to an I/R episode. These include activation of neurotrophic and neuroprotective factors, greater activation of anti-excitotoxic and anti-oxidant mechanisms, increased plasticity potential, a greater energy reserve and improved mitochondrial function. This review seeks to summarize properties of CA2-4, DG in the context of endogenous neuroprotection, and then to assess the potential utility of these properties to therapeutic approaches. In so doing, it appears to represent the first such addressing of the issue of ischemia resistance attributable to CA2-4, DG.

Neutrophil Extracellular Traps in Cerebral Ischemia/Reperfusion Injury: Friend and Foe

Cerebral ischemic injury, one of the leading causes of morbidity and mortality worldwide, triggers various central nervous system (CNS) diseases, including acute ischemic stroke (AIS) and chronic ischemia-induced Alzheimer's disease (AD). Currently, targeted therapies are urgently needed to address neurological disorders caused by cerebral ischemia/reperfusion injury (CI/RI), and the emergence of neutrophil extracellular traps (NETs) may be able to relieve the pressure. Neutrophils are precursors to brain injury following ischemic stroke and exert complicated functions. NETs extracellularly release reticular complexes of neutrophils, i.e., double-stranded DNA (dsDNA), histones, and granulins. Paradoxically, NETs play a dual role, friend and foe, under different conditions, for example, physiological circumstances, infection, neurodegeneration, and ischemia/reperfusion. Increasing evidence indicates that NETs exert anti-inflammatory effects by degrading cytokines and chemokines through protease at a relatively stable and moderate level under physiological conditions, while excessive amounts of NETs release (NETosis) irritated by CI/RI exacerbate the inflammatory response and aggravate thrombosis, disrupt the blood-brain barrier (BBB), and initiates sequential neuron injury and tissue damage. This review provides a comprehensive overview of the machinery of NETs formation and the role of an abnormal cascade of NETs in CI/RI, as well as other ischemia-induced neurological diseases. Herein, we highlight the potential of NETs as a therapeutic target against ischemic stroke that may inspire translational research and innovative clinical approaches.

Therapeutic hypothermia for stroke: Unique challenges at the bedside

Therapeutic hypothermia has shown promise as a means to improving neurological outcomes at several neurological conditions. At the clinical level, it has been shown to improve outcomes in comatose survivors of cardiac arrest and in neonatal hypoxic ischemic encephalopathy, but has yet to be convincingly demonstrated in stroke. While numerous preclinical studies have shown benefit in stroke models, translating this to the clinical level has proven challenging. Major obstacles include cooling patients with typical stroke who are awake and breathing spontaneously but often have significant comorbidities. Solutions around these problems include selective brain cooling and cooling to lesser depths or avoiding hyperthermia. This review will cover the mechanisms of protection by therapeutic hypothermia, as well as recent progress made in selective brain cooling and the neuroprotective effects of only slightly lowering brain temperature. Therapeutic hypothermia for stroke has been shown to be feasible, but has yet to be definitively proven effective. There is clearly much work to be undertaken in this area.

Neuroprotective effects of sodium valproate on hippocampal cell and volume, and cognitive function in a rat model of focal cerebral ischemia

Valproate (VPA) as a histone deacetylase (HDAC) inhibitor has shown neuroprotective effects in neurodegenerative diseases. This study evaluated whether VPA treatment ameliorated the synaptic plasticity dysfunction, hippocampal neuronal loss, and spatial memory deficits induced by cerebral ischemia in the middle cerebral artery occlusion (MCAO) model. Thirty-two male Sprague-Dawley rats were randomly divided into 4 groups control, sham, cerebral ischemia+vehicle (MCAO+V), and MCAO+VPA. The right common carotid artery was occluded for 1 hour. VPA (300 mg/kg) or vehicles were injected intraperitoneally on days 0,1,2 and 3 of the reperfusion. After 7 days of reperfusion the Morris water maze, passive avoidance, and open field tests were performed. Hippocampal synaptic plasticity in the CA1 area was recorded by field potential recording. We used the term neuronal Input-Output (I/O) function and paired-pulse ratio (PPR) to refer to basal synaptic transmission and presynaptic neurotransmitter release probability respectively. After that, the brains were removed for assaying stereological parameters of the CA1 neurons. Our results showed the VPA administration significantly reduced the total infarct volume, improved MCAO-induced spatial learning -memory, fear memory, and anxiety compared to the MCAO+V group. In addition, the field potential recording showed that VPA significantly ameliorated the impaired the long- term potentiation (LTP) induced by MCAO, without any effects on basal synaptic transmission and neurotransmitter release probability. Therefore, it seems that a decrease in total infarct volume and induction of long-term potentiation via postsynaptic mechanisms is responsible for improving MCAO-induced cognitive impairment.

Inflammatory Responses After Ischemic Stroke

Ischemic stroke generates an immune response that contributes to neuronal loss as well as tissue repair. This is a complex process involving a range of cell types and effector molecules and impacts tissues outside of the CNS. Recent reviews address specific aspects of this response, but several years have passed and important advances have been made since a high-level review has summarized the overall state of the field. The present review examines the initiation of the inflammatory response after ischemic stroke, the complex impacts of leukocytes on patient outcome, and the potential of basic science discoveries to impact the development of therapeutics. The information summarized here is derived from broad PubMed searches and aims to reflect recent research advances in an unbiased manner. We highlight valuable recent discoveries and identify gaps in knowledge that have the potential to advance our understanding of this disease and therapies to improve patient outcomes.

An Ethanolic Extract of Cucurbita pepo L. Seeds Modifies Neuroendocrine Disruption in Chronic Stressed Rats and Adrenal Expression of Inflammatory Markers and HSP70

Background: Pumpkins (Cucurbita pepo L.) were described to have antioxidant, anti-inflammatory, anti-fatigue, and antidepressant-like effect. The adrenal gland is an important stress-responsive organ that maintains homeostasis during stress.

Objectives: This study aimed to assess the efficacy of the administration of Cucurbita pepo L. (CP) extract in relieving behavioral, biochemical, and structural changes in the adrenal gland induced by exposure to chronic unpredictable mild stress (CUMS) and to explore the mechanism behind this impact.

Materials and Methods: Forty male albino rats were divided into 4 groups (n = 10): control, CUMS, fluoxetine-treated, and CP-treated groups. Behavioral changes, corticosterone level, pro-inflammatory cytokines TNF-α and IL-6, and oxidant/antioxidant profile were assessed in the serum at the end of the experiment. Adrenal glands were processed for histopathological and immunohistochemical assessment. Gene expression of caspase-3 and Ki67 and heat shock protein 70 (HSP70) were assessed in adrenal glands using RT-PCR.

Results: The CP extract significantly reduced the corticosterone level (p < 0.001), immobility time (p < 0.001), and inflammatory and oxidative changes associated with CUMS-induced depression compared to the untreated group. The CP extract alleviated CUMS-induced adrenal histopathological changes and significantly reduced apoptosis (p < 0.001) and significantly upregulated antioxidant levels in the serum.

Conclusion:Cucurbita pepo L. effectively ameliorated the chronic stress-induced behavioral, biochemical, and adrenal structural changes mostly through its antioxidant and anti-inflammatory effects.

Mechanism of Phosgene-Induced Acute Lung Injury and Treatment Strategy

Phosgene (COCl₂) was once used as a classic suffocation poison and currently plays an essential role in industrial production. Due to its high toxicity, the problem of poisoning caused by leakage during production, storage, and use cannot be ignored. Phosgene mainly acts on the lungs, causing long-lasting respiratory depression, refractory pulmonary edema, and other related lung injuries, which may cause acute respiratory distress syndrome or even death in severe cases. Due to the high mortality, poor prognosis, and frequent sequelae, targeted therapies for phosgene exposure are needed. However, there is currently no specific antidote for phosgene poisoning. This paper reviews the literature on the mechanism and treatment strategies to explore new ideas for the treatment of phosgene poisoning.

Nanodelivery of traditional Chinese Gingko Biloba extract EGb-761 and bilobalide BN-52021 induces superior neuroprotective effects on pathophysiology of heat stroke

Military personnel often exposed to high summer heat are vulnerable to heat stroke (HS) resulting in abnormal brain function and mental anomalies. There are reasons to believe that leakage of the blood-brain barrier (BBB) due to hyperthermia and development of brain edema could result in brain pathology. Thus, exploration of suitable therapeutic strategies is needed to induce neuroprotection in HS. Extracts of Gingko Biloba (EGb-761) is traditionally used in a variety of mental disorders in Chinese traditional medicine since ages. In this chapter, effects of TiO2 nanowired EGb-761 and BN-52021 delivery to treat brain pathologies in HS is discussed based on our own investigations. We observed that TiO2 nanowired delivery of EGb-761 or TiO2 BN-52021 is able to attenuate more that 80% reduction in the brain pathology in HS as compared to conventional drug delivery. The functional outcome after HS is also significantly improved by nanowired delivery of EGb-761 and BN-52021. These observations are the first to suggest that nanowired delivery of EGb-761 and BN-52021 has superior therapeutic effects in HS not reported earlier. The clinical significance in relation to the military medicine is discussed.

Phosgene: toxicology, animal models, and medical countermeasures

Phosgene is a gas crucial to industrial chemical processes with widespread production (∼1 million tons/year in the USA, 8.5 million tons/year worldwide). Phosgene's high toxicity and physical properties resulted in its use as a chemical warfare agent during the First World War with a designation of CG ('Choky Gas'). The industrial availability of phosgene makes it a compound of concern as a weapon of mass destruction by terrorist organizations. The hydrophobicity of phosgene exacerbates its toxicity often resulting in a delayed toxidrome as the upper airways are moderately irritated; by the time symptoms appear, significant damage has occurred. As the standard of care for phosgene intoxication is supportive therapy, a pressing need for effective therapeutics and treatment regimens exists. Proposed toxicity mechanisms for phosgene based on human and animal exposures are discussed. Whereas intermediary components in the phosgene intoxication pathways are under continued discussion, generation of reactive oxygen species and oxidative stress is a common factor. As animal models are required for the study of phosgene and for FDA approval via the Animal Rule; the status of existing models and their adherence to Haber's Rule is discussed. Finally, we review the continued search for efficacious therapeutics for phosgene intoxication; and present a rapid post-exposure response that places exogenous human heat shock protein 72, in the form of a cell-penetrating fusion protein (Fv-HSP72), into lung tissues to combat apoptosis resulting from oxidative stress. Despite significant progress, additional work is required to advance effective therapeutics for acute phosgene exposure.

Functions and Therapeutic Potential of Extracellular Hsp60, Hsp70, and Hsp90 in Neuroinflammatory Disorders

Neuroinflammation is implicated in central nervous system (CNS) diseases, but the molecular mechanisms involved are poorly understood. Progress may be accelerated by developing a comprehensive view of the pathogenesis of CNS disorders, including the immune and the chaperone systems (IS and CS). The latter consists of the molecular chaperones; cochaperones; and chaperone cofactors, interactors, and receptors of an organism and its main collaborators in maintaining protein homeostasis (canonical function) are the ubiquitin–proteasome system and chaperone-mediated autophagy. The CS has also noncanonical functions, for instance, modulation of the IS with induction of proinflammatory cytokines. This deserves investigation because it may be at the core of neuroinflammation, and elucidation of its mechanism will open roads toward developing efficacious treatments centered on molecular chaperones (i.e., chaperonotherapy). Here, we discuss information available on the role of three members of the CS—heat shock protein (Hsp)60, Hsp70, and Hsp90—in IS modulation and neuroinflammation. These three chaperones occur intra- and extracellularly, with the latter being the most likely involved in neuroinflammation because they can interact with the IS. We discuss some of the interactions, their consequences, and the molecules involved but many aspects are still incompletely elucidated, and we hope that this review will encourage research based on the data presented to pave the way for the development of chaperonotherapy. This may consist of blocking a chaperone that promotes destructive neuroinflammation or replacing or boosting a defective chaperone with cytoprotective activity against neurodegeneration.

Exogenous recombinant Hsp70 mediates neuroprotection after photothrombotic stroke

Ischaemic stroke is an acute interruption of the blood supply to the brain, which leads to rapid irreversible damage to nerve tissue. Ischaemic stroke is accompanied by the development of neuroinflammation and neurodegeneration observed around the affected brain area. Heat shock protein 70 (Hsp70) facilitates cell survival under a variety of different stress conditions. Hsp70 may be secreted from cells and exhibits cytoprotective activity. This activity most likely occurs by decreasing the levels of several proinflammatory cytokines through interaction with a few receptors specific to the innate immune system. Herein, we demonstrated that intranasal administration of recombinant human Hsp70 shows a significant twofold decrease in the volume of local ischaemia induced by photothrombosis in the mouse prefrontal brain cortex. Our results revealed that intranasal injections of recombinant Hsp70 decreased the apoptosis level in the ischaemic penumbra, stimulated axonogenesis and increased the number of neurons producing synaptophysin. Similarly, in the isolated crayfish stretch receptor, consisting of a single sensory neuron surrounded by the glial envelope, exogenous Hsp70 significantly decreased photoinduced apoptosis and necrosis of glial cells. The obtained data enable one to consider human recombinant Hsp70 as a promising compound that could be translated from the bench into clinical therapies.

Poncirin suppresses lipopolysaccharide (LPS)-induced microglial inflammation and ameliorates brain ischemic injury in experimental stroke in mice

Background

Based on accumulating evidence, excessive activation of microglia-mediated inflammatory responses plays an essential role in ischemic stroke. Poncirin (Pon) exerts anti-hyperalgesic, anti-osteoporotic and anti-tumor effects on various diseases. However, the roles of Pon in microglial activation and the underlying mechanism have not been elucidated. This study aimed to explore whether Pon inhibits lipopolysaccharide (LPS)-induced microglial neuroinflammation and protects against brain ischemic injury in experimental stroke in mice.

Methods

Primary microglia cells were prepared from the cerebral cortices of 1- to 2-day-old C57BL/6J mice. Murine BV2 cells and primary microglia were stimulated with LPS and the effects of a non-cytotoxic concentration of Pon on LPS-stimulated pro-inflammatory factors were measured using real-time PCR and enzyme-linked immunosorbent assays (ELISAs). Western blot analyses were used for mechanistic studies. In an in vivo study, 8-week-old male C57BL/6J mice were subjected to focal cerebral ischemia through middle cerebral artery occlusion (MCAO). Pon (30 mg/kg, i.p.) or the same volume of saline was administered after the MCAO model was established, and the infarct volume was evaluated using 2,3,5-triphenyltetrazolium chloride (TTC) staining. We also evaluated animal behaviours, the expression of pro-inflammatory cytokines and microglial activation in the ischemic hemisphere.

Results

Pon prevented the release of nitric oxide (NO), prostaglandin E2 (PGE2), interleukin (IL)-1β, IL-6 and tumor necrosis factor-alpha (TNF-α) in both BV2 cells and primary microglia stimulated with LPS. The inhibitory effects of Pon were associated with the regulation of the ERK1/2, JNK and nuclear factor kappa B (NF-κB) signaling pathways. In mice that underwent MCAO, Pon administration decreased the lesion size and improved neurological deficits. Furthermore, Pon attenuated the production of inflammatory cytokines mainly by restraining microglial activation after ischemic stroke.

Conclusions

Based on the findings from the present study, Pon provides neuroprotection through its anti-inflammatory effects on microglia and it may be a useful treatment for ischemic stroke.

Hsp70 and NF-kB Mediated Control of Innate Inflammatory Responses in a Canine Macrophage Cell Line

The pathogenesis of many inflammatory diseases is associated with the uncontrolled activation of nuclear factor kappa B (NF-κB) in macrophages. Previous studies have shown that in various cell types, heat shock protein 70 (Hsp70) plays a crucial role in controlling NF-κB activity. So far, little is known about the role of Hsp70 in canine inflammatory processes. In this study we investigated the potential anti-inflammatory effects of Hsp70 in canine macrophages as well as the mechanisms underlying these effects. To this end, a canine macrophage cell line was stressed with arsenite, a chemical stressor, which upregulated Hsp70 expression as detected by flow cytometry and qPCR. A gene-edited version of this macrophage cell line lacking inducible Hsp70 was generated using CRISPR-Cas9 technology. To determine the effects of Hsp70 on macrophage inflammatory properties, arsenite-stressed wild-type and Hsp70 knockout macrophages were exposed to lipopolysaccharide (LPS), and the expression of the inflammatory cytokines IL-6, IL-1β and tumor necrosis factor-α (TNF-α) and levels of phosphorylated NF-κB were determined by qPCR and Western Blotting, respectively. Our results show that non-toxic concentrations of arsenite induced Hsp70 expression in canine macrophages; Hsp70 upregulation significantly inhibited the LPS-induced expression of the pro-inflammatory mediators TNF-α and IL-6, as well as NF-κB activation in canine macrophages. Furthermore, the gene editing of inducible Hsp70 by CRISPR-Cas9-mediated gene editing neutralized this inhibitory effect of cell stress on NF-κB activation and pro-inflammatory cytokine expression. Collectively, our study reveals that Hsp70 may regulate inflammatory responses through NF-κB activation and cytokine expression in canine macrophages.

Heat Shock Protein 70 (HSP70) Induction: Chaperonotherapy for Neuroprotection after Brain Injury

The 70 kDa heat shock protein (HSP70) is a stress-inducible protein that has been shown to protect the brain from various nervous system injuries. It allows cells to withstand potentially lethal insults through its chaperone functions. Its chaperone properties can assist in protein folding and prevent protein aggregation following several of these insults. Although its neuroprotective properties have been largely attributed to its chaperone functions, HSP70 may interact directly with proteins involved in cell death and inflammatory pathways following injury. Through the use of mutant animal models, gene transfer, or heat stress, a number of studies have now reported positive outcomes of HSP70 induction. However, these approaches are not practical for clinical translation. Thus, pharmaceutical compounds that can induce HSP70, mostly by inhibiting HSP90, have been investigated as potential therapies to mitigate neurological disease and lead to neuroprotection. This review summarizes the neuroprotective mechanisms of HSP70 and discusses potential ways in which this endogenous therapeutic molecule could be practically induced by pharmacological means to ultimately improve neurological outcomes in acute neurological disease.

Manipulation of Quercetin and Melatonin in the Down-Regulation of HIF-1α, HSP-70 and VEGF Pathways in Rat's Kidneys Induced by Hypoxic Stress

Hypoxia may lead to inflammatory responses by numerous signaling pathways. This investigation intended to inspect the defensive role of Quercetin (Quer) and/ or Melatonin (Mel) against reno toxicity induced by Sodium nitrite (Sod ntr). Sod ntr injection significantly decreased blood hemoglobin concentration (Hb) with a concurrent increase in serum tumor necrosis factor- α, interleukin-6, C-reactive protein, creatinine, and urea levels. Over protein-expression of vascular endothelial growth factor and heat shock, protein-70 and mRNA of HIF-1α were also observed. Pretreatment of the Sod ntr- injected rats with the aforementioned antioxidants; either alone or together significantly improved such parameters. Histopathological examination reinforced the previous results. It was concluded that the combined administration of Quer and Mel may be useful as a potential therapy against renal injury induced by Sod ntr. HIF-1α and HSP-70 are implicated in the induction of hypoxia and its treatment.

Selenium Deficiency Induces Inflammation via the iNOS/NF-κB Pathway in the Brain of Pigs

Selenium (Se) is an essential trace element to maintain homeostasis in humans and animals. The aim of the present study was to clarify the mechanism of Se deficiency-induced inflammation in the pig's brain. Twenty-four healthy pigs were randomly divided into two groups (n = 12/group): control group (group C) was fed diet with 0.3 mg/kg inorganic Se, and Se-deficient group (group L) was fed diet with 0.007 mg/kg inorganic Se. At the 90th day of the experiment, the histology in the pig's brain was observed by the microscope, the NO levels and iNOS activity were assayed, and the mRNA and protein expression levels of inflammatory cytokines (iNOS, COX-2, NF-κB, and PTGEs) and HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) were detected by real-time quantitative PCR and Western blot. Compared with group C, both of NO levels and iNOS activity were increased in group L, and the mRNA and protein expression levels of inflammatory cytokines (iNOS, COX-2, NF-κB, and PTGEs) and HSPs (HSP27, HSP40, HSP60, HSP70, and HSP90) were also upregulated; histological observation displayed inflammatory response in the brain of pig. In summary, diet with Se deficiency can activate the iNOS/NF-κB pathway to upregulate the expression of inflammatory cytokines, thereby leading to inflammatory lesions in the pig's brain, and HSPs are involved in the compensatory regulation of inflammation. This study provides a reference for the prevention of pig brain inflammation from the perspective of nutrition.

Histone Deacetylases Inhibitors in Neurodegenerative Diseases, Neuroprotection and Neuronal Differentiation

Histone deacetylases (HADC) are the enzymes that remove acetyl group from lysine residue of histones and non-histone proteins and regulate the process of transcription by binding to transcription factors and regulating fundamental cellular process such as cellular proliferation, differentiation and development. In neurodegenerative diseases, the histone acetylation homeostasis is greatly impaired, shifting towards a state of hypoacetylation. The histone hyperacetylation produced by direct inhibition of HDACs leads to neuroprotective actions. This review attempts to elaborate on role of small molecule inhibitors of HDACs on neuronal differentiation and throws light on the potential of HDAC inhibitors as therapeutic agents for treatment of neurodegenerative diseases. The role of HDACs in neuronal cellular and disease models and their modulation with HDAC inhibitors are also discussed. Significance of these HDAC inhibitors has been reviewed on the process of neuronal differentiation, neurite outgrowth and neuroprotection regarding their potential therapeutic application for treatment of neurodegenerative diseases.

The Local and Peripheral Immune Responses to Stroke: Implications for Therapeutic Development

The immune response to stroke is an exciting target for future stroke therapies. Stroke is a leading cause of morbidity and mortality worldwide, and clot removal (mechanical or pharmacological) to achieve tissue reperfusion is the only therapy currently approved for patient use. Due to a short therapeutic window and incomplete effectiveness, however, many patients are left with infarcted tissue that stimulates inflammation. Although this is critical to promote repair, it can also damage surrounding healthy brain tissue. In addition, acute immunodepression and subsequent infections are common and are associated with worse patient outcomes. Thus, the acute immune response is a major focus of researchers attempting to identify ways to amplify its benefits and suppress its negative effects to improve short-term recovery of patients. Here we review what is known about this powerful process. This includes the role of brain resident cells such as microglia, peripherally activated cells such as macrophages and neutrophils, and activated endothelium. The role of systemic immune activation and subsequent immunodepression in the days after stroke is also discussed, as is the chronic immune responses and its effects on cognitive function. The biphasic role of inflammation, as well as complex timelines of cell production, differentiation, and trafficking, suggests that the relationship between the acute and chronic phases of stroke recovery is complex. Gaining a more complete understanding of this intricate process by which inflammation is initiated, propagated, and terminated may potentially lead to therapeutics that can treat a larger population of stroke patients than what is currently available. The immune response plays a critical role in patient recovery in both the acute and chronic phases after stroke. In patients, the immune response can be beneficial by promoting repair and recovery, and also detrimental by propagating a pro-inflammatory microenvironment. Thus, it is critical to understand the mechanisms of immune activation following stroke in order to successfully design therapeutics.

Adaptations to the mudflat: Insights from physiological and transcriptional responses to thermal stress in a burrowing bivalve Sinonovacula constricta

Understanding physiological adaptations of organisms to temperature changes that characterize their habitat is the first step in predicting the putative effects of global climate change on population dynamics. Mudflats are an important part of the intertidal zone and experience extreme and fluctuating temperatures. Therein, species would be potentially susceptible to global warming. The present study explored physiological adaptations of burrowing species to life in an intertidal mudflat by analyzing the potential operative temperatures in the mudflat, and assessing cardiac performance and the transcriptional response to thermal stress by a typical burrowing bivalve, the razor clam Sinonovacula constricta in different thermal environments, mimicking conditions during low tides. Clams showed higher thermal sublethal limits in mud with overlying air than in mud with overlying water, indicating an adaptation to rapidly changing ambient temperatures and thermal environments during emersion. This sublethal limit was far above the maximum operative temperature in the actual habitat site and suggests a potential buffer zone to ensure survival under unexpected high temperatures, that could occur with global warming. In response to high temperature, S. constricta exhibited the common heat stress response by up-regulating expression of the Bcl2-associated athanogene 3 (BAG3) and heat shock proteins to cope with the adverse effects of high temperature on protein homeostasis. Increased expression of key genes, including molybdenum cofactor synthesis 3 (MOCS3), oligoribonuclease (REX2), and NFκappaB inhibitor alpha (NFIA) may further remit the effect of thermal stress during the emersion period and delay a situation where clams reach their thermal sublethal limit, thereby helping to endure high temperature during low tide. These results clearly illustrate significant adaptations of a burrowing bivalve to life in intertidal mudflats at both physiological and molecular levels and can provide insights into potential physiological or evolutionary responses that could aid survival of mudflat species in a changing global climate.

Subcutaneous injection of recombinant heat shock protein 70 ameliorates atopic dermatitis skin lesions in a mouse model

Atopic dermatitis (AD) is a chronic inflammatory skin disease and sometimes is a tough challenge for physicians. We previously reported that in Th2 environment, the production and secretion of thymic stromal lymphopoietin (TSLP) from human keratinocytes was inhibited by recombinant heat shock protein 70 (rHSP70). The present study assessed the therapeutic effectiveness of rHSP70 in a mouse model of AD. An experimental model of AD was reproduced by systemic sensitization and local epicutaneous challenge with ovalbumin (OVA). Treatment of rHSP70 was performed by subcutaneous administration. The levels of OVA-specific IgE, as well as cytokines, were detected by ELISA. Skin samples from patch areas were also taken for histologic examination. Injection of rHSP70 improved the histologic picture by reducing the thickness of epidermis and allergic inflammation. Skin sonography revealed rHSP70 ameliorated skin remodeling. rHSP70 also significantly decreased the protein expression of TSLP of skin from patch areas. Furthermore, in ex vivo studies also showed group of rHSP70 treatment decreased IL-13, RANTES, MIP-1β and increased IFN-γ secreted from splenocytes stimulated with OVA. The rHSP70 intervention in the mouse model of AD reduced the skin expression of TSLP and attenuated the clinical appearance of OVA-induced AD mice. The effect was achieved by suppressed Th2 immune response in injected skin tissue and enhanced systemic Th1 immune response. These results suggest that rHSP70 have potential as a promising protein for the treatment of AD.

Cofilin-actin rod formation in experimental stroke is attenuated by therapeutic hypothermia and overexpression of the inducible 70 kD inducible heat shock protein (Hsp70)

BACKGROUND AND PURPOSE

Cofilin-actin rods are covalently linked aggregates of cofilin-1 and actin. Under ischemic conditions, these rods have been observed in neuronal dendrites and axons and may contribute to the loss of these processes. Hypothermia (Hypo) and the 70 kD inducible heat shock protein (Hsp70) are both known to improve outcomes after stroke, but the mechanisms are uncertain. Here, we evaluated the effect of these factors on cofilin-actin rod formation in a mouse model of stroke.

MATERIALS AND METHODS

Mice were subjected to distal middle cerebral artery occlusion (dMCAO) and treated with Hypo using a paradigm previously shown to be neuroprotective. We similarly studied mice that overexpressed transgenic (Tg) or were deficient knockout (Ko) in the inducible 70 kDa heat shock protein (Hsp70), also previously shown to be protective by our group and others. Cofilin-actin rod formation was assessed by histological analysis at 4 and 24 h after dMCAO. Its expression was analyzed in three different regions, namely, infarct core (the center of the infarct), middle cerebral artery (MCA) borderzone (the edge of the brain regions supplied by the MCA), and the ischemic borderzone (border of ischemic lesion). Ischemic lesion size and neurological deficits were also assessed.

RESULTS

Both Hypo-treated and Hsp70 Tg mice had smaller lesion sizes and improved neurological outcomes, whereas Hsp70 Ko mice had larger lesion sizes and worsened neurological outcomes. Cofilin-actin rods were increased after stroke, but were reduced by therapeutic Hypo and in Hsp70 Tg mice. In contrast, cofilin-actin rods were increased in ischemic brains of Hsp70 Ko mice.

CONCLUSIONS

Cofilin-actin rod formation was suppressed under the conditions of neuroprotection and increased under circumstances where outcome was worsened. This suggests that cofilin-actin rods may act to participate in or exacerbate ischemic pathology and warrants further study as a potential therapeutic target.

Heat shock protein signaling in brain ischemia and injury

Heat shock proteins (HSPs) are chaperones that catalyze the refolding of denatured proteins. In addition to their ability to prevent protein denaturation and aggregation, the HSPs have also been shown to modulate many signaling pathways. Among HSPs, the inducible 70 kDa HSP (HSP70) has especially been shown to improve neurological outcome in experimental models of brain ischemia and injury. HSP70 can modulate various aspects of the programmed cell death pathways and inflammation. This review will focus on potential mechanisms of the neuroprotective effects of HSP70 in stroke and brain trauma models. We also comment on potential ways in which HSP70 could be translated into clinical therapies.

Carnosine and L-arginine attenuate the downregulation of brain monoamines and gamma aminobutyric acid; reverse apoptosis and upregulate the expression of angiogenic factors in a model of hemic hypoxia in rats

PURPOSE

The purpose of the present study was to investigate the preventive effect of L-arginine (ARG) and carnosine (CAR) on hypoxia-induced neurotoxicity in rats. The impact on neuro-inflammation, apoptosis, angiogenesis, and the brain levels of monoamines and GABA were investigated.

METHODS

Rats were divided into the following: normal control, hypoxia model induced by sodium nitrite (75 mg/kg s.c), and hypoxic rats pre-treated with CAR (250 mg/kg), ARG (200 mg/kg), and their combination.

RESULTS

Data revealed that hypoxia induced significant elevation of hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), and its receptor reflecting the stimulation of angiogenesis. Hypoxia also resulted in increased inflammatory mediators-including nuclear factor kappa B (NF-κB), tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6). In addition, hypoxia initiates cerebral apoptosis as revealed by increased caspase-3 and BAX with reduced Bcl-2. These changes were associated with reduced brain levels of GABA and monoamines including noradrenaline (NADR), dopamine (DOP), and serotonin (SER). Pre-treatment with ARG and/or CAR significantly mitigated the neural changes induced by hypoxia and attenuated the elevated levels of NF-κB, TNF-α, IL-6, caspase-3, and BAX, while ameliorated the reduced levels of Bcl-2, NADR, DOP, SER, and GABA, with the best improvement observed with the combination. Further elevation of the angiogenic markers was observed indicating their role in boosting oxygen delivery to brain.

CONCLUSION

CAR, ARG, and, importantly, their combination could effectively protect against hypoxia-induced neurotoxicity, via their angiogenic, anti-inflammatory, and anti-apoptotic properties in addition to reversing the effect on GABA and monoamines.

Triggering receptor expressed on myeloid cells-2 expression in the brain is required for maximal phagocytic activity and improved neurological outcomes following experimental stroke

Triggering receptor expressed on myeloid cells-2 (TREM2) is an innate immune receptor that promotes phagocytosis by myeloid cells such as microglia and macrophages. We previously showed that TREM2 deficiency worsened outcomes from experimental stroke and impeded phagocytosis. However, myeloid cells participating in stroke pathology include both brain resident microglia and circulating macrophages. We now clarify whether TREM2 on brain microglia or circulating macrophages contribute to its beneficial role in ischemic stroke by generating bone marrow (BM) chimeric mice. BM chimera mice from TREM2 knockout (KO) or wild type (Wt) mice were used as donor and recipient mice. Mice were subjected to experimental stroke, and neurological function and infarct volume were assessed. Mice with intact TREM2 in brain microglia showed better neurological recovery and reduced infarct volumes, compared with mice lacking microglial TREM2. Myeloid cell activation and numbers of phagocytes were decreased in mice lacking brain TREM2, compared with mice with intact brain TREM2. These results suggest that TREM2 expression is important for post-stroke recovery, and that TREM2 expression on brain resident microglia is more essential to this recovery, than that of circulating macrophages. These findings might suggest a new therapeutic target for cerebrovascular diseases.

Regional differences in the inflammatory and heat shock response in glia: implications for ALS

Preferential neuronal vulnerability is characteristic of several neurodegenerative diseases including the motor neuron disease amyotrophic lateral sclerosis (ALS). It is well established that glia play a critical role in ALS, but it is unknown whether regional differences in the ability of glia to support motor neurons contribute to the specific pattern of neuronal degeneration. In this study, using primary mixed glial cultures from different mouse CNS regions (spinal cord and cortex), we examined whether regional differences exist in key glial pathways that contribute to, or protect against, motor neuron degeneration. Specifically, we examined the NF-κB-mediated inflammatory pathway and the cytoprotective heat shock response (HSR). Glial cultures were treated with pro-inflammatory stimuli, tumour necrosis factor-ɑ/lipopolysaccharide or heat stressed to stimulate the inflammatory and HSR respectively. We found that spinal cord glia expressed more iNOS and produced more NO compared to cortical glia in response to inflammatory stimuli. Intriguingly, we found that expression of ALS-causing SOD1G93A did not elevate the levels of NO in spinal cord glia. However, activation of the stress-responsive HSR was attenuated in SOD1G93A cultures, with a reduced Hsp70 induction in response to stressful stimuli. Exposure of spinal cord glia to heat shock in combination with inflammatory stimuli reduced the activation of the inflammatory response. The results of this study suggest that impaired heat shock response in SOD1G93A glia may contribute to the exacerbated inflammatory reactions observed in ALS mice. Graphical abstract Mixed primary glial cultures were established from cortical and spinal cord regions of wild-type mice and mice expressing ALS-causing mutant human SOD1 and the inflammatory and heat shock responses were investigated in these cultures. In the absence of stress, all cultures appeared to have similar cellular composition, levels of inflammatory mediators and similar expression level of heat shock proteins. When stimulated, spinal cord glia were more reactive and activated the inflammatory pathway more readily than cortical glia; this response was similar in wild-type and SOD1G93A glial cultures. Although the heat shock response was similar in spinal cord and cortical glial, in SOD1G93A expressing glia from both the spinal cord and cortex, the induction of heat shock response was diminished. This impaired heat shock response in SOD1G93A glia may therefore contribute to the exacerbated inflammatory reactions observed in ALS mice.

Reducing myeloperoxidase activity decreases inflammation and increases cellular protection in ischemic stroke

Myeloperoxidase (MPO) is a pro-inflammatory enzyme abundantly secreted by activated myeloid cells after stroke. We show that when MPO activity is either blocked by the specific inhibitor 4-aminobenzoic acid hydrazide (ABAH) in wildtype (WT) mice or congenitally absent (MPO-/-), there was decreased cell loss, including degenerating neurons and oligodendrocytes, in the ischemic brains compared to vehicle-treated WT mice after stroke. MPO inhibition also reduced the number of activated myeloid cells after ischemia. MPO inhibition increased cytoprotective heat shock protein 70 (Hsp70) by 70% and p-Akt by 60%, while decreased the apoptotic marker p53 level by 62%, compared to vehicle-treated mice after ischemia. Similarly, MPO inhibition increased the number of Hsp70+/NeuN+ cells after stroke by 60%. Notably, MPO inhibition significantly improved neurological outcome compared with the vehicle-treated group after stroke. We further found longer treatment periods resulted in larger reduction of infarct size and greater neurobehavioral improvement from MPO inhibition, even when given days after stroke. Therefore, MPO inhibition with ABAH or MPO deficiency creates a protective environment that decreased inflammatory cell recruitment and increased expression of survival factors to improve functional outcome. MPO inhibition may represent a promising therapeutic target for stroke therapy, possibly even days after stroke has occurred.

Heat-Shock Proteins in Neuroinflammation

The heat-shock response, one of the main pro-survival mechanisms of a living organism, has evolved as the biochemical response of cells to cope with heat stress. The most well-characterized aspect of the heat-shock response is the accumulation of a conserved set of proteins termed heat-shock proteins (HSPs). HSPs are key players in protein homeostasis acting as chaperones by aiding the folding and assembly of nascent proteins and protecting against protein aggregation. HSPs have been associated with neurological diseases in the context of their chaperone activity, as they were found to suppress the aggregation of misfolded toxic proteins. In recent times, HSPs have proven to have functions apart from the classical molecular chaperoning in that they play a role in a wider scale of neurological disorders by modulating neuronal survival, inflammation, and disease-specific signaling processes. HSPs are gaining importance based on their ability to fine-tune inflammation and act as immune modulators in various bodily fluids. However, their effect on neuroinflammation processes is not yet fully understood. In this review, we summarize the role of neuroinflammation in acute and chronic pathological conditions affecting the brain. Moreover, we seek to explore the existing literature on HSP-mediated inflammatory function within the central nervous system and compare the function of these proteins when they are localized intracellularly compared to being present in the extracellular milieu.

Histamine Is an Inducer of the Heat Shock Response in SOD1-G93A Models of ALS

(1) Background: Amyotrophic lateral sclerosis (ALS) is a multifactorial non-cell autonomous disease where activation of microglia and astrocytes largely contributes to motor neurons death. Heat shock proteins have been demonstrated to promote neuronal survival and exert a strong anti-inflammatory action in glia. Having previously shown that the pharmacological increase of the histamine content in the central nervous system (CNS) of SOD1-G93A mice decreases neuroinflammation, reduces motor neuron death, and increases mice life span, here we examined whether this effect could be mediated by an enhancement of the heat shock response. (2) Methods: Heat shock protein expression was analyzed in vitro and in vivo. Histamine was provided to primary microglia and NSC-34 motor neurons expressing the SOD1-G93A mutation. The brain permeable histamine precursor histidine was chronically administered to symptomatic SOD1-G93A mice. Spine density was measured by Golgi-staining in motor cortex of histidine-treated SOD1-G93A mice. (3) Results: We demonstrate that histamine activates the heat shock response in cultured SOD1-G93A microglia and motor neurons. In SOD1-G93A mice, histidine augments the protein content of GRP78 and Hsp70 in spinal cord and cortex, where the treatment also rescues type I motor neuron dendritic spine loss. (4) Conclusion: Besides the established histaminergic neuroprotective and anti-inflammatory effects, the induction of the heat shock response in the SOD1-G93A model by histamine confirms the importance of this pathway in the search for successful therapeutic solutions to treat ALS.

L-glutamine protects mouse brain from ischemic injury via up-regulating heat shock protein 70

INTRODUCTION

L-glutamine is an antioxidant that plays a role in a variety of biochemical processes. Given that oxidative stress is a key component of stroke pathology, the potential of L-glutamine in the treatment of ischemic stroke is worth exploring.

AIMS

In this study, we investigated the effect and mechanisms of action of L-glutamine after cerebral ischemic injury.

RESULTS

L-glutamine reduced brain infarct volume and promoted neurobehavioral recovery in mice. L-glutamine administration increased the expression of heat-shock protein 70 (HSP70) in astrocytes and endothelial cells. Such effects were abolished by the coadministration of Apoptozole, an inhibitor of the ATPase activity of HSP70. L-glutamine also reduced oxidative stress and neuronal apoptosis, and increased the level of superoxide dismutase, glutathione, and brain-derived neurotrophic factor. Cotreatment with Apoptozole abolished these effects. Cell culture study further revealed that the conditioned medium from astrocytes cultured with L-glutamine reduced the apoptosis of neurons after oxygen-glucose deprivation.

CONCLUSION

L-glutamine attenuated ischemic brain injury and promoted functional recovery via HSP70, suggesting its potential in ischemic stroke therapy.

Understanding How Dogs Age: Longitudinal Analysis of Markers of Inflammation, Immune Function, and Oxidative Stress

As in human populations, advances in nutrition and veterinary care have led to an increase in the lifespan of companion animals. Detrimental physiological changes occurring later in life must be understood before interventions can be made to slow or reduce them. One important aspect of human aging is upregulation of the inflammatory response and increase in oxidative damage resulting in pathologies linked to chronic inflammation. To determine whether similar processes occur in the aging dog, changes in markers of inflammation and oxidative stress were investigated in 80 Labrador retrievers from adulthood to the end of life. Serum levels of immunoglobulin M (p < .001) and 8-hydroxy-2-deoxyguanosine (p < .001) increased with age, whereas no effect of age was detected for immunoglobulin G or C-reactive protein unless the last year of life was included in the analysis (p = .002). Baseline levels of heat shock protein 70 decreased with age (p < .001) while those after exposure to heat stress were maintained (p = .018). However, when excluding final year of life data, a decline in the heat shock protein 70 response after heat stress was observed (p = .004). These findings indicate that aging dogs undergo changes similar to human inflammaging and offer the possibility of nutritional or pharmacological intervention to delay or reduce these effects.

The Neuroprotective Effect of miR-181a After Oxygen-Glucose Deprivation/Reperfusion and the Associated Mechanism

The level of miR-181a decreases rapidly in N2a cells following oxygen-glucose deprivation/reperfusion, but its role in this process is unclear. Reelin, a regulator of neuronal migration and synaptogenesis, is a predicted target of miR-181a. We hypothesized that miR-181a reduces neuronal apoptosis and protects neurons by targeting reelin. Second mitochondria-derived activator of caspases (Smac) is a protein located in mitochondria that regulates apoptosis. The pro-apoptotic effect of Smac is achieved by reversing the effects of apoptosis-inhibiting proteins (IAPs), particularly X-linked inhibitor of apoptosis (XIAP). We also evaluated the effect of miR-181a on the Smac/IAP signaling pathway after oxygen-glucose deprivation and reperfusion in N2a cells. The miR-181a level, apoptosis rate, and the levels of reelin mRNA and protein, Smac, and XIAP were assessed in N2a cells subjected to oxygen-glucose deprivation for 4 h and reperfusion for 0, 4, 12, or 24 h with/without an miR-181a mimic, or mismatched control. Direct targeting of reelin by miR-181a was assessed in vitro by dual luciferase assay and immunoblotting. Pre-treatment with miR-181a mimicked the increase in the miR-181a level in N2a cells after oxygen-glucose deprivation/reperfusion, resulting in a significant decrease in the apoptosis rate. Changes in the miR-181a level in N2a cells were inversely correlated with reelin protein expression. Direct targeting of the reelin 3' untranslated region by miR-181a was verified by dual luciferase assay, which showed that miR-181a significantly inhibited luciferase activity. The Smac level was significantly lower in the miR-181a mimics than the normal control and mimics-cont groups (P < 0.01), whereas the level of XIAP was increased slightly. These findings suggest that miR-181a protects neurons from apoptosis by inhibiting reelin expression and regulating the Smac/IAP signaling pathway after oxygen-glucose deprivation/reperfusion injury.

Autophagy Induced by Oxygen-Glucose Deprivation Mediates the Injury to the Neurovascular Unit

BACKGROUND Autophagy is characterized by the degradation of cellular components in autophagosomes. It plays a significant role in cerebral ischemic injury and has a complex functional connection with apoptosis. The neurovascular unit (NVU) is a structural and functional unit of the nervous system presented as a therapeutic target of stroke. This study aimed to investigate the effect of autophagy induced by ischemic damage on NVUs. MATERIAL AND METHODS SH-SY5Y cells, C6 cells, and rat brain microvascular endothelial cells were cultured with oxygen-glucose deprivation (OGD) exposure for different time durations, and 3-methyladenine (3-MA) was added as an autophagy inhibitor. In all 3 cell lines, lactate dehydrogenase (LDH) release was measured. Furthermore, apoptosis was detected using Annexin V-fluorescein isothiocyanate/propidium iodide labeling and immunofluorescence staining. Autophagosomes were observed through AO/MDC (acridine orange/monodansycadaverine) double staining. LC3-II expression levels were evaluated by western blot analysis. RESULTS In the OGD groups of 3 cell lines, LDH leakage, and apoptotic rates were obviously increased. Remarkable increase in LC3-II expression was found in the OGD groups of SH-SY5Y cells and C6 cells. However, 3-MA decreased the LC3-II expression to varying degrees. CONCLUSIONS OGD could induce the over-activation of autophagy and augment the apoptotic activity in neurons and glial cells of NVUs.

Proteomic analysis of the response of porcine adrenal gland to heat stress

Heat stress (HS) and its associated pathologies are major challenges facing the pig industry in southern China, and are responsible for large economic losses. However, the molecular mechanisms governing the abnormal secretion of HS-responsive hormones, such as glucocorticoids, are not fully understood. The goal of this study was to investigate differentially expressed proteins (DEPs) in the adrenal glands of pigs, and to elucidate changes in the immune neuroendocrine system in pigs following HS. Through a functional proteomics approach, we identified 1202 peptides, corresponding to 415 proteins. Of these, we found 226 DEPs between heat-stressed and control porcine adrenal gland tissue; 99 of these were up-regulated and 127 were down-regulated in response to HS. These DEPs included proteins involved in substrate transport, cytoskeletal changes, and stress responses. Ingenuity Pathway Analysis was used to identify the subcellular characterization, functional pathway involvement, regulatory networks, and upstream regulators of the identified proteins. Functional network and pathway analyses may provide insights into the complexity and dynamics of HS-host interactions, and may accelerate our understanding of the mechanisms of HS.

Microglial Calcium Release-Activated Calcium Channel Inhibition Improves Outcome from Experimental Traumatic Brain Injury and Microglia-Induced Neuronal Death

Store-operated Ca²⁺ entry (SOCE) mediated by calcium release-activated calcium (CRAC) channels contributes to calcium signaling. The resulting intracellular calcium increases activate calcineurin, which in turn activates immune transcription factor nuclear factor of activated T cells (NFAT). Microglia contain CRAC channels, but little is known whether these channels play a role in acute brain insults. We studied a novel CRAC channel inhibitor to explore the therapeutic potential of this compound in microglia-mediated injury. Cultured microglial BV2 cells were activated by Toll-like receptor agonists or IFNγ. Some cultures were treated with a novel CRAC channel inhibitor (CM-EX-137). Western blots revealed the presence of CRAC channel proteins STIM1 and Orai1 in BV2 cells. CM-EX-137 decreased nitric oxide (NO) release and inducible nitric oxide synthase (iNOS) expression in activated microglia and reduced agonist-induced intracellular calcium accumulation in microglia, while suppressing inflammatory transcription factors nuclear factor kappa B (NF-κB) and nuclear factor of activated T cells (NFAT). Male C57/BL6 mice exposed to experimental brain trauma and treated with CM-EX-137 had decreased lesion size, brain hemorrhage, and improved neurological deficits with decreased microglial activation, iNOS and Orai1 and STIM1 levels. We suggest a novel anti-inflammatory approach for managing acute brain injury. Our observations also shed light on new calcium signaling pathways not described previously in brain injury models.

Cytoprotective effect of eupatilin against indomethacin-induced damage in feline esophageal epithelial cells: relevance of HSP27 and HSP70

Indomethacin is a non-steroidal anti-inflammatory drug with clearly known side effects on the gastrointestinal tract. The purpose of the present study was to investigate whether eupatilin inhibit cell injury induced by indomethacin in cultured feline esophageal epithelial cells (EECs). EECs were used to investigate the ability of eupatilin to induce the expression of heat shock proteins (HSP27 and HSP70) and analyze its cytoprotective effect against indomethacin-induced damage. The treatment of EECs with indomethacin for 8 h decreased cell viability. Western blot analysis showed that the levels of HSPs gradually decreased in cells treated with indomethacin, while eupatilin treatment increased the levels of HSPs. When treated with both indomethacin and eupatilin, the levels of HSPs increased rapidly, and were maintained at 130-140%. In addition, treatment with the specific inhibitors of PTK, PKC, PLC, p38 MAPK, JNKs, and PI3K attenuated the eupatilin-induced expression of HSPs. Pretreatment of EECs with the inhibitors of protein synthesis, actinomycin D or cycloheximide, attenuated the cytoprotective effect of eupatilin on indomethacin-induced cell damage. Reactive oxygen species production was upregulated by indomethacin, but downregulated by eupatilin. Taken together, it was suggested that HSPs were partly responsible for the eupatilin-mediated cytoprotective activity against the indomethacin-induced damage in EECs.

Danger signals in stroke and their role on microglia activation after ischemia

Ischemic stroke is a major cause of death. Besides the direct damage resulting from oxygen and glucose deprivation, sterile inflammation plays a pivotal role in increasing cellular death. Damaged-associated molecular patterns (DAMPs) are passively released from dying cells and activate the innate immune system. Thus, they take part in the direct and rapid activation of the inflammatory response after stroke onset. In this review the role of the most important DAMPs, high mobility group box 1, heat and cold shock proteins, purines, and peroxiredoxins, are addressed. Moreover, intracellular pathways activated by DAMPs in microglia are illuminated.

Quantitative analysis reveals crosstalk mechanisms of heat shock-induced attenuation of NF-κB signaling at the single cell level

Elevated temperature induces the heat shock (HS) response, which modulates cell proliferation, apoptosis, the immune and inflammatory responses. However, specific mechanisms linking the HS response pathways to major cellular signaling systems are not fully understood. Here we used integrated computational and experimental approaches to quantitatively analyze the crosstalk mechanisms between the HS-response and a master regulator of inflammation, cell proliferation, and apoptosis the Nuclear Factor κB (NF-κB) system. We found that populations of human osteosarcoma cells, exposed to a clinically relevant 43°C HS had an attenuated NF-κB p65 response to Tumor Necrosis Factor α (TNFα) treatment. The degree of inhibition of the NF-κB response depended on the HS exposure time. Mathematical modeling of single cells indicated that individual crosstalk mechanisms differentially encode HS-mediated NF-κB responses while being consistent with the observed population-level responses. In particular "all-or-nothing" encoding mechanisms were involved in the HS-dependent regulation of the IKK activity and IκBα phosphorylation, while others involving transport were "analogue". In order to discriminate between these mechanisms, we used live-cell imaging of nuclear translocations of the NF-κB p65 subunit. The single cell responses exhibited "all-or-nothing" encoding. While most cells did not respond to TNFα stimulation after a 60 min HS, 27% showed responses similar to those not receiving HS. We further demonstrated experimentally and theoretically that the predicted inhibition of IKK activity was consistent with the observed HS-dependent depletion of the IKKα and IKKβ subunits in whole cell lysates. However, a combination of "all-or-nothing" crosstalk mechanisms was required to completely recapitulate the single cell data. We postulate therefore that the heterogeneity of the single cell responses might be explained by the cell-intrinsic variability of HS-modulated IKK signaling. In summary, we show that high temperature modulates NF-κB responses in single cells in a complex and unintuitive manner, which needs to be considered in hyperthermia-based treatment strategies.

Cytokine, C-Reactive Protein, and Heat Shock Protein mRNA Expression Levels in Patients with Active Behçet's Uveitis

Background

To investigate the gene expression levels of interleukin 10 (IL10), IL18, interferon gamma (IFNG), IFN-gamma receptor (IFNGR), C-reactive protein (CRP), and heat shock protein 70 (HSP70) in patients with active Behçet’s uveitis.

Material/Methods

Forty patients with Behçet’s disease diagnosed according to the International Study Group criteria and 30 healthy individuals were included in the study. IL10, IL18, IFNG, IFNGR, CRP, and HSP70 gene expression levels were compared.

Results

Expression levels of IL18, IFNG, IFNGR, and CRP were significantly higher in patients with active Behçet’s uveitis than in control subjects (P<0.01 for all), whereas no significant differences were found in IL10 and HSP70 gene expression levels (P>0.01 for both).

Conclusions

IL18, IFNG, IFNGR, and CRP gene expression is significantly increased in active Behçet’s uveitis. There was no significant difference between active Behçet’s uveitis patients and controls in terms of IL10 and HSP70 gene expression levels. We conclude that drugs prescribed to Behçet’s patients with active uveitis downregulate gene expression.

The 70-kDa heat shock protein (Hsp70) as a therapeutic target for stroke

INTRODUCTION

The 70-kDa heat shock protein (Hsp70) is a cytosolic chaperone which facilitates protein folding, degradation, complex assembly, and translocation. Following stroke, these functions have the potential to lead to cytoprotection, and this has been demonstrated using genetic mutant models, direct gene transfer or the induction of Hsp70 via heat stress, approaches which limit its translational utility. Recently, the investigation of Hsp70-inducing pharmacological compounds, which, through their ability to inhibit Hsp90, has obvious clinical implications in terms of potential therapies to mitigate cell death and inflammation, and lead to neuroprotection from brain injury. Areas covered: In this review, we will focus on the role of Hsp70 in cell death and inflammation, and the current literature surrounding the pharmacological induction in acute ischemic stroke models with comments on potential applications at the clinical level. Expert opinion: Such neuroprotectants could be used to synergistically improve neurological outcome or to extend the time window of existing interventions, thus increasing the numbers of stroke victims eligible for treatment.

Korean ginseng extract ameliorates abnormal immune response through the regulation of inflammatory constituents in Sprague Dawley rat subjected to environmental heat stress

Background

Increases in the average global temperature cause heat stress–induced disorders by disrupting homeostasis. Excessive heat stress triggers an imbalance in the immune system; thus protection against heat stress is important to maintain immune homeostasis. Korean ginseng (Panax ginseng Meyer) has been used as a herbal medicine and displays beneficial biological properties.

Methods

We investigated the protective effects of Korean ginseng extracts (KGEs) against heat stress in a rat model. Following acclimatization for 1 week, rats were housed at room temperature for 2 weeks and then exposed to heat stress (40°C/2 h/day) for 4 weeks. Rats were treated with three KGEs from the beginning of the second week to the end of the experiment.

Results

Heat stress dramatically increased secretion of inflammatory factors, and this was significantly reduced in the KGE-treated groups. Levels of inflammatory factors such as heat shock protein 70, interleukin 6, inducible nitric oxide synthase, and tumor necrosis factor-alpha were increased in the spleen and muscle upon heat stress. KGEs inhibited these increases by down-regulating heat shock protein 70 and the associated nuclear factor-κB and mitogen-activated protein kinase signaling pathways. Consequently, KGEs suppressed activation of T-cells and B-cells.

Conclusion

KGEs suppress the immune response upon heat stress and decrease the production of inflammatory cytokines in muscle and spleen. We suggest that KGEs protect against heat stress by inhibiting inflammation and maintaining immune homeostasis.

Low omega-6/omega-3 ratio in a maternal protein-deficient diet promotes histone-3 changes in progeny neural cells and favors leukemia inhibitory factor genetranscription

Omega-3 (n-3) fatty acids modulate epigenetic changes critical to genesis and differentiation of neural cells. Conversely, maternal protein-malnutrition can negatively modify these changes. This study investigated whether a low n-6/n-3 ratio in a maternal diet could favor histone-3 (H3) modifications, gene transcription and differentiation in the offspring neural cells even under protein-deficiency. Female rats fed a control (Ct), or 3 types of multideficient diets differing in protein levels or linoleic/alpha-linolenic fatty acid ratios (RBD, RBD-C, RBD-SO) from 30 days prior to mating and during pregnancy. Cerebral cortex tissue and cortical cultures of progeny embryonic neurons and postnatal astrocytes were analyzed. H3K9 acetylation and H3K27 or H3K4 di-methylation levels were assessed by flow cytometry and/or immunocytochemistry. In astrocyte cultures and cortical tissue, the GFAP protein levels were assessed. Glial derived neurotrophic factor (GDNF) and leukemia inhibitory factor (LIF) gene expression were evaluated in the cortical tissue. GFAP levels were similar in astrocytes of Ct, RBD and RBD-C, but 65% lower in RBD-SO group. Higher levels of H3K9Ac were found in the neurons and H3K4Me2 in the astrocytes of the RBD group. No intergroup difference in the cortical GDNF mRNA expression or the H3K27Me2 levels in astrocytes was detected. LIF mRNA levels were higher in the RDB (P=.002) or RBD-C (P=.004) groups than in the control. The findings indicate the importance of dietary n-3 availability for the brain, even under a protein-deficient condition, inducing Histone modifications and increasing LIF gene transcription, involved in neural cell differentiation and reactivity.

Heat shock protein 70 suppresses neuroinflammation induced by α-synuclein in astrocytes

Neuroinflammation triggered by activation of glial cells plays an important role in the pathophysiology of several neurodegenerative diseases including Parkinson's disease (PD). Besides microglia, astrocytes are also critical in initiating and perpetuating inflammatory process associated with PD. Heat shock protein 70 (Hsp70) is originally described as intracellular chaperone, however, recent study revealed that it had anti-inflammatory effects as well. The present study is designed to investigate whether Hsp70 mediates neuroinflammation in astrocytes. By employing α-synuclein (α-Syn) (A53T) aggregates on primary cultured astrocytes of rats, we found that astrocytes were activated and neuroinflammatory response was triggered, as indicated by over-expression of glial fibrillary acidic protein (GFAP), cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS), increased production of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). The data also showed that the neuroinflammatory response accompanied up-regulated Hsp70 expression. Moreover, over-expression of Hsp70 through transfection of Hsp70 cDNA plasmids could significantly reduce the production of TNF-α, IL-1β, and the expression of GFAP, COX-2 as well as iNOS. While inhibition of Hsp70 by VER155008 exacerbated neuroinflammatory response in astrocytes challenged by α-Syn aggregates. Further mechanistic study indicated that c-Jun N-terminal kinase (JNK) and nuclear factor-κB (NF-κB) signalings were responsible for the neuroinflammation, which was also regulated by Hsp70. These findings demonstrated that Hsp70 was an important modulator in astrocytes induced inflammation, and up-regulation of Hsp70 might be a potential regulating approach for neuroinflammation-related neurodegenerative diseases, such as PD.