Role of P2X purinoceptor 7 in neurogenic pulmonary edema after subarachnoid hemorrhage in rats

MicroRNA-124 conducts neuroprotective effect via inhibiting AK4/ATF3 after subarachnoid hemorrhage

Spontaneous subarachnoid hemorrhage (SAH) accounts for approximately 5% of all cases of stroke. SAH is correlated with elevated rates of mortality and disability. Despite significant advancements in comprehending the pathogenesis and surgical management, efficacious clinical interventions remain restricted, and the prognosis is yet to be enhanced. MicroRNAs play a crucial role in various pathological processes in organisms. Revealing these regulatory processes is conducive to the development of new treatment methods. MicroRNA-124 is highly expressed in the nervous system and has significant research value for SAH. This study aims to explore the role of miR-124 in the early post-SAH period on neural function and verify whether it is involved in the pathological and physiological processes of SAH. In this study, we used methods such as comparing the expression levels of miR-124 in cerebrospinal fluid, establishing a rat SAH model, and a mouse embryonic primary neuron hemoglobin stimulation model to verify the downstream proteins of miR-124 in SAH. Through transfection techniques, we adjusted the expression of this small RNA in Vitro and in Vivo models using miR-124 inhibitor and mimic in the primary neuron hemoglobin stimulation model and rat SAH model, and observed the phenotype. Finally, by consulting the literature and verifying in Vivo and in Vitro methods, AK4 and downstream molecule ATF3 were identified as downstream targets of miR-124.

Emerging Roles of Cells and Molecules of Innate Immunity in Alzheimer's Disease

The inflammatory response that marks Alzheimer's disease (neuroinflammation) is considered a double-edged sword. Microglia have been shown to play a protective role at the beginning of the disease. Still, persistent harmful stimuli further activate microglia, inducing an exacerbating inflammatory process which impairs β-amyloid peptide clearance capability and leads to neurotoxicity and neurodegeneration. Moreover, microglia also appear to be closely involved in the spread of tau pathology. Soluble TREM2 also represents a crucial player in the neuroinflammatory processes. Elevated levels of TREM2 in cerebrospinal fluid have been associated with increased amyloid plaque burden, neurodegeneration, and cognitive decline in individuals with Alzheimer's disease. Understanding the intricate relationship between innate immunity and Alzheimer's disease will be a promising strategy for future advancements in diagnosis and new therapeutic interventions targeting innate immunity, by modulating its activity. Still, additional and more robust studies are needed to translate these findings into effective treatments. In this review, we focus on the role of cells (microglia, astrocytes, and oligodendrocytes) and molecules (TREM2, tau, and β-amyloid) of the innate immune system in the pathogenesis of Alzheimer's disease and their possible exploitation as disease biomarkers and targets of therapeutical approaches.

DNase-1 Treatment Exerts Protective Effects in Neurogenic Pulmonary Edema via Regulating the Neutrophil Extracellular Traps after Subarachnoid Hemorrhage in Mice

It has been reported that neutrophil extracellular traps (NETs) involve inflammation, coagulation and cell death. Acute lung injury is also considered to be connected with NETs. Deoxyribonuclease I (DNase-1), a clinical medication for the respiratory system, has been reported to degrade cell-free DNA (cfDNA), which is the main component of NETs. Herein, we did research to clarify the therapeutic value of DNase-1 in NPE after SAH. In this model, we found that the treatment of DNase-1 remarkably decreased lung water, neutrophilic infiltration and inflammation. In addition, DNase-1 inhibited the NETs and proinflammatory subtype transition of the macrophages. Moreover, the depletion of neutrophil also verified the role of NETs in NPE. Our results suggest that DNase-1 has the potential to effectively relieve the NPE after SAH and to be a clinical drug for use after SAH.

Protective Effect of Purinergic P2X7 Receptor Inhibition on Acrolein-Induced Urothelial Cell Damage

Patients undergoing chemotherapy with cyclophosphamide experience cystitis due to excretion of a toxic metabolite, acrolein. Cystitis, an inflammation of the bladder, is associated with damage to the integrity of the urothelial barrier. The purinergic P2X7 receptor (P2X7R) is increasingly recognized for its role in inflammation and cell death. P2X7R is expressed abundantly on the bladder urothelium. The aim of this study was to investigate the role of P2X7R in acrolein-induced inflammatory damage in primary cultured porcine bladder urothelial cells. Confluent urothelial cells in culture were treated with acrolein to induce damage; also, with the P2X7R selective antagonist, A804598. Cell viability assay, immunocytochemistry, and trans-epithelial electrical resistance (TEER) studies were carried out to investigate the effect of treatments on urothelial cell function. Acrolein induced a significant reduction in urothelial cell viability, which was protected by the presence of A804598 (10 µM). The urothelial barrier function, indicated by TEER values, was also significantly reduced by acrolein, whereas pre-incubation with P2X7R antagonist significantly protected the urothelial cell barrier from acrolein-induced TEER reduction. The structure of urothelial cell tight junctions was similarly impacted by acrolein treatment, showing the fragmentation of zona occludens-1 (ZO-1) immunoreactivity. Pre-treatment of cells with A804598 countered against the actions of acrolein and maintained ZO-1 expression level and cell structure. The damaging effect of acrolein on urothelial cells integrity could be impaired by inhibition of P2X7R, therefore P2X7R blockade may be a possible therapy in patients with bladder cystitis caused by cyclophosphamide treatment.

P2X7 Receptor Blockade Protects Against Acrolein-Induced Bladder Damage: A Potential New Therapeutic Approach for the Treatment of Bladder Inflammatory Diseases

Inflammatory conditions of the urinary bladder have been shown to be associated with urothelial damage and loss of function. The purinergic P2X7 receptor has been implicated in several inflammatory conditions. The aim of this study was to investigate the role of the P2X7 receptor in acrolein-induced inflammatory damage using the porcine urinary bladder. For this purpose, an ex-vivo model of porcine urothelial damage induced by direct instillation of acrolein into the whole bladder lumen was used. To determine the role of the P2X7 receptor, the bladders were pre-incubated with a selective P2X7 receptor antagonist, A804598 (10 μM), for 1 h. The effects of the acrolein-induced urothelial damage on the bladder’s function were assessed by examining the bladder wall contractile response, structure changes, apoptosis, and oxidative stress in the bladder tissues. The acrolein treatment led to significant damage to the urothelium histology, tight junction expression, and contractile responses. Acrolein also induced apoptosis in the mucosa layer. All these acrolein-induced responses were attenuated by pre-treatment with the P2X7 receptor antagonist A804598. Acrolein also significantly induced DNA oxidation in the submucosal layer; however, the P2X7 receptor antagonism did not show any protective effect towards the acrolein-induced oxidative stress. These findings suggested that the P2X7 receptor is involved in the acrolein-induced damage to the urothelium; therefore, the P2X7 receptor antagonists may be a new therapeutic option for the treatment of bladder inflammation.

Enterovirus A71 Infection Activates Human Immune Responses and Induces Pathological Changes in Humanized Mice

Since the discovery of enterovirus A71 (EV-A71) half a century ago, it has been recognized as the cause of large-scale outbreaks of hand-foot-and-mouth disease worldwide, particularly in the Asia-Pacific region, causing great concern for public health and economic burdens. Detailed mechanisms on the modulation of immune responses after EV-A71 infection have not been fully known, and the lack of appropriate models hinders the development of promising vaccines and drugs. In the present study, NOD-scid IL2Rγ^-/- (NSG) mice with a human immune system (humanized mice) at the age of 4 weeks were found to be susceptible to a human isolate of EV-A71 infection. After infection, humanized mice displayed limb weakness, which is similar to the clinical features found in some of the EV-A71-infected patients. Histopathological examination indicated the presence of vacuolation, gliosis, or meningomyelitis in brain stem and spinal cord, which were accompanied by high viral loads detected in these organs. The numbers of activated human CD4⁺ and CD8⁺ T cells were upregulated after EV-A71 infection, and EV-A71-specific human T cell responses were found. Furthermore, the secretion of several proinflammatory cytokines, such as human gamma interferon (IFN-γ), interleukin-8 (IL-8), and IL-17A, was elevated in the EV-A71-infected humanized mice. Taken together, our results suggested that the humanized mouse model permits insights into the human immune responses and the pathogenesis of EV-A71 infection, which may provide a platform for the evaluation of anti-EV-A71 drug candidates in the future.IMPORTANCE Despite causing self-limited hand-food-and-mouth disease in younger children, EV-A71 is consistently associated with severe forms of neurological complications and pulmonary edema. Nevertheless, only limited vaccines and drugs have been developed over the years, which is possibly due to a lack of models that can more accurately recapitulate human specificity, since human is the only natural host for wild-type EV-A71 infection. Our humanized mouse model not only mimics histological symptoms in patients but also allows us to investigate the function of the human immune system during infection. It was found that human T cell responses were activated, accompanied by an increase in the production of proinflammatory cytokines in EV-A71-infected humanized mice, which might contribute to the exacerbation of disease pathogenesis. Collectively, this model allows us to delineate the modulation of human immune responses during EV-A71 infection and may provide a platform to evaluate anti-EV-A71 drug candidates in the future.

P2X7 as a scavenger receptor for innate phagocytosis in the brain

The P2X7 receptor has been widely studied for its ATP-induced pro-inflammatory effect, but in the absence of a ligand, P2X7 has a second function as a scavenger receptor, which is active in the development of the human brain. The scavenger activity of P2X7 is only evident in the absence of serum but is fully active in cerebrospinal fluid. P2X7 on the cell surface is present as a membrane complex, and an attachment to non-muscle myosin of the cytoskeleton is required for particle engulfment. Selective antagonists of P2X7 pro-inflammatory function have little effect on phagocytosis, but inheritance of a variant haplotype spanning the P2RX7 and P2RX4 genes has been associated with loss of P2X7-mediated phagocytosis. Recent studies in mice suggest that the innate phagocytosis mediated by P2X7 receptors declines with ageing. Thus, defective P2X7-mediated phagocytosis may contribute to age-related neuro-degenerative diseases including Alzheimer's disease, age-related macular degeneration and primary progressive multiple sclerosis.

The potential of P2X7 receptors as a therapeutic target, including inflammation and tumour progression

Seven P2X ion channel nucleotide receptor subtypes have been cloned and characterised. P2X7 receptors (P2X7R) are unusual in that there are extra amino acids in the intracellular C terminus. Low concentrations of ATP open cation channels sometimes leading to cell proliferation, whereas high concentrations of ATP open large pores that release inflammatory cytokines and can lead to apoptotic cell death. Since many diseases involve inflammation and immune responses, and the P2X7R regulates inflammation, there has been recent interest in the pathophysiological roles of P2X7R and the potential of P2X7R antagonists to treat a variety of diseases. These include neurodegenerative diseases, psychiatric disorders, epilepsy and a number of diseases of peripheral organs, including the cardiovascular, airways, kidney, liver, bladder, skin and musculoskeletal. The potential of P2X7R drugs to treat tumour progression is discussed.

Could cardiac biomarkers predict neurogenic pulmonary edema in aneurysmal subarachnoid hemorrhage?

BACKGROUND

Neurogenic pulmonary edema (NPE) is a clinical syndrome characterized by the acute onset of pulmonary edema after a significant central nervous system (CNS) insult. NPE occurs as a result of release of catecholamines into the blood immediately after aneurysm rupture. The aim of this study is to investigate the connection between the value of cardiac biomarkers on admission and incidence of NPE in patients with aneurysmal subarachnoid hemorrhage (SAH).

METHODS

A total of 262 SAH patients (162 women, 100 men) were prospectively included in the study. Clinical characteristics, electrocardiographic (ECG) changes, serum cardiac and inflammatory biomarkers were measured on admission and on the day of development of NPE. These data were analyzed in order to predict the development NPE.

RESULTS

Nineteen patients (7.25%) developed NPE. Comparison revealed that patients who subsequently developed NPE, sustained more severe SAH. Cardiac damage was more severe in these patients, as represented by significantly higher mean values of all examined cardiac biomarkers (P = 0.000), except for troponin I value that was significantly lower (P = 0.000). Multivariate regression analysis revealed that elevated troponin I (OR, 4.980; 95% CI, 1.27-19.49; P = 0.021) and white blood cell count (OR, 22.195; 95% CI, 3.99-123.50; P = 0.000) are predictors of NPE.

CONCLUSIONS

Significantly higher values of cardiac biomarkers were observed in SAH patients complicated with NPE. Elevated values of cardiac biomarkers appear to play an active role in prediction of NPE, although white blood cell count may be involved in the prediction of NPE. There is an influence of SAH therapy on predictors of NPE.

Subarachnoid Hemorrhage: An Update

Subarachnoid hemorrhage (SAH) is a debilitating, although uncommon, type of stroke with high morbidity, mortality, and economic impact. Modern 30-day mortality is as high as 40%, and about 50% of survivors have permanent disability. Care at high-volume centers with dedicated neurointensive care units is recommended. Euvolemia, not hypervolemia, should be targeted, and the aneurysm should be secured early. Neither statin therapy nor magnesium infusions should be initiated for delayed cerebral ischemia. Cerebral vasospasm is just one component of delayed cerebral edema. Hyponatremia is common in subarachnoid hemorrhage and is associated with longer length of stay, but not increased mortality.

Melatonin attenuates neurogenic pulmonary edema via the regulation of inflammation and apoptosis after subarachnoid hemorrhage in rats

Neurogenic pulmonary edema (NPE) is a serious non-neurological complication that can occur after a subarachnoid hemorrhage (SAH) and is associated with decreased survival and a poor neurological outcome. Melatonin is a strong antioxidant that has beneficial effects against SAH in rats, including reduced mortality and reduced neurological deficits. The molecular mechanisms underlying these clinical effects in the SAH model, however, have not been clearly identified. This study was undertaken to determine the influence of melatonin on SAH-induced NPE and the potential mechanism of these effects using the filament perforation model of SAH in male Sprague Dawley rats. Either melatonin (150 mg/kg) or a vehicle was given via an intraperitoneal injection 2 hr after an SAH induction. Lung samples were extracted 24 hr after SAH. The results show that the melatonin treatment attenuated SAH-induced NPE by preventing alveolar-capillary barrier dysfunctions via inhibiting the disruption of tight junction proteins (ZO-1 and occludin). Moreover, the treatment downregulated the levels of mature interleukin (IL) -1β, myeloperoxidase (MPO), and matrix metallopeptidase (MMP) 9 expression/activation, which were increased in the lung; also, melatonin treatment improved neurological deficits. Furthermore, the melatonin treatment markedly reduced caspase-3 activity and the number of TUNEL-positive cells in the lung. Taken together, these findings show that administration of melatonin attenuates NPE by preventing alveolar-capillary barrier dysfunctions via repressing the inflammatory response and by anti-apoptosis effects after SAH.

Rosiglitazone attenuates early brain injury after experimental subarachnoid hemorrhage in rats

Early brain injury (EBI) plays a crucial role in the pathological progress of subarachnoid hemorrhage (SAH). This study was designed to determine whether rosiglitazone protects the brain against EBI in rats, and discuss the role of the anti-apoptotic mechanism mediated by Bcl-2 family proteins in this neuroprotection. 86 male Sprague-Dawley rats were divided into the sham group, the SAH+ vehicle group and the SAH+ rosiglitazone group. SAH was induced via an endovascular perforation technique and rosiglitazone (3mg/kg) or vehicle was administered. Mortality, neurological scores, brain water content, Evans blue dye assay, TUNEL stain assay, Gelatin zymography, and western blot analysis were performed. Rosiglitazone significantly improved mortality, neurological scores, brain water content, blood brain barrier (BBB) and apoptosis compared with the vehicle group within 24h after SAH. The TUNEL staining assay demonstrated that apoptosis was ameliorated. Cleaved Caspase-3 and MMP-9 expression was reduced, whereas Bcl-2 and p-Bad was markedly preserved by rosiglitazone. A significant elevation of p-Akt was detected after rosiglitazone treatment. Our study demonstrated that rosiglitazone plays a neuroprotective role in EBI after SAH via attenuation of BBB disruption, brain edema and apoptosis.

Effect of GLT-1 modulator and P2X7 antagonists alone and in combination in the kindling model of epilepsy in rats

INTRODUCTION

Multiple lines of investigation have explored the role of glutamatergic and purinergic systems in epilepsy, related cognitive impairment, and oxidative stress. Glutamate transporters, particularly GLT-1 expression, were found to be decreased, and purinergic receptor, P2X7 expression, was found to be increased in brain tissue associated with epilepsy. The present study was carried out to investigate the effect of ceftriaxone (GLT-1 upregulator) and Brilliant Blue G (P2X7 antagonist) against PTZ-induced kindling in rats. The study was further extended to elucidate the cross-link between glutamatergic and purinergic pathways in epilepsy.

MATERIAL AND METHODS

Systemic administration of subconvulsant dose of PTZ (30 mg/kg) every other day for 27days (14 injections) significantly increased the mean kindling, and developed generalized tonic-clonic seizures, and reduced motor co-ordination, cognitive skills, oxidative defense (increases lipid peroxidation, nitrite levels and decreases GSH level) and acetylcholinesterase enzyme activities in the cortex and subcortical region. Treatments with CEF (100 and 200mg/kg) and BBG (15 and 30 mg/kg) alone and in combination (CEF 100mg/kg and BBG 15 mg/kg) significantly decreased the mean kindling score and restored behavioral and oxidative defense activities compared with treatment with PTZ.

CONCLUSIONS

The combination of both the drugs was shown to have better effect in preventing kindled seizures and a significantly synergistic effect compared with their effect alone in PTZ-kindled rats. The present study elucidated the mechanistic role of GLT-1 modulator and selective P2X7 antagonist and their combination against PTZ-induced kindling. The study for the first time demonstrated the cross-link between glutamatergic and purinergic pathways in epilepsy treatment.

Peripheral to central: Organ interactions in stroke pathophysiology

Stroke is associated with a high risk of disability and mortality, and with the exception of recombinant tissue-type plasminogen activator for acute stroke, most treatments have proven ineffective. Clinical translation of promising experimental therapeutics is limited by inadequate stroke models and a lack of understanding of the mechanisms underlying acute stroke and how they affect outcome. Bidirectional communication between the ischemic brain and peripheral immune system modulates stroke progression and tissue repair, while epidemiological studies have provided evidence of an association between organ dysfunction and stroke risk. This crosstalk can determine the fate of stroke patients and must be taken into consideration when investigating the pathophysiological mechanisms and therapeutic options for stroke. This review summarizes the current evidence for interactions between the brain and other organs in stroke pathophysiology in basic and clinic studies, and discusses the role of these interactions in the progression and outcome of stroke and how they can direct the development of more effective treatment strategies.

Neurogenic pulmonary edema caused by spontaneous cerebellar hemorrhage: A fatal case report

Background:

Neurogenic pulmonary edema (NPE) is a clinical syndrome characterized by an acute increase of pulmonary interstitial and alveolar fluid. It could result from a significant central nervous system (CNS) insult such as intracranial hemorrhage. However, NPE as a major presenting manifestation of cerebellar hemorrhage was seldom reported.

Case Description:

We introduce a rare case of a 34-year-old woman suffering from a fulminant NPE in parallel with a spontaneous cerebellar hemorrhage. Although appropriate supportive measures were taken in the neuroscience care unit, the patient failed to survive hypoxemia within 28 h after hospital admission.

Conclusion:

Pathological lesions of the cerebellum may initiate a cascade of reactions including massive sympathetic discharge and catecholamine storm, leading to a dysfunction of both cardiovascular and respiratory systems. By far, no effective therapeutic strategies have been utilized to treat such a situation. Our present report would shed light on the underlying mechanism of NPE.

The harmful effects of subarachnoid hemorrhage on extracerebral organs

Subarachnoid hemorrhage (SAH) is a devastating neurological disorder. Patients with aneurysmal SAH develop secondary complications that are important causes of morbidity and mortality. Aside from secondary neurological injuries, SAH has been associated with nonneurologic medical complications, such as neurocardiogenic injury, neurogenic pulmonary edema, hyperglycemia, and electrolyte imbalance, of which cardiac and pulmonary complications are most common. The related mechanisms include activation of the sympathetic nervous system, release of catecholamines and other hormones, and inflammatory responses. Extracerebral complications are directly related to the severity of SAH-induced brain injury and indicate the clinical outcome in patients. This review provides an overview of the extracerebral complications after SAH. We also aim to describe the manifestations, underlying mechanisms, and the effects of those extracerebral complications on outcome following SAH.