Recombinant CCL17 Enhances Hematoma Resolution and Activation of CCR4/ERK/Nrf2/CD163 Signaling Pathway After Intracerebral Hemorrhage in Mice

Adjudin protects blood-brain barrier integrity and attenuates neuroinflammation following intracerebral hemorrhage in mice

Secondary brain injury exacerbates neurological dysfunction and neural cell death following intracerebral hemorrhage (ICH), targeting the pathophysiological mechanism of the secondary brain injury holds promise for improving ICH outcomes. Adjudin, a potential male contraceptive, exhibits neuroprotective effects in brain injury disease models, yet its impact in the ICH model remains unknown. In this study, we investigated the effects of adjudin on brain injury in a mouse ICH model and explored its underlying mechanisms. ICH was induced in male C57BL/6 mice by injecting collagenase into the right striatum. Mice received adjudin treatment (50 mg/kg/day) for 3 days before euthanization and the perihematomal tissues were collected for further analysis. Adjudin significantly reduced hematoma volume and improved neurological function compared with the vehicle group. Western blot showed that Adjudin markedly decreased the expression of MMP-9 and increased the expression of tight junctions (TJs) proteins, Occludin and ZO-1, and adherens junctions (AJs) protein VE-cadherin. Adjudin also decreased the blood-brain barrier (BBB) permeability, as indicated by the reduced albumin and Evans Blue leakage, along with a decrease in brain water content. Immunofluorescence staining revealed that adjudin noticeably reduced the infiltration of neutrophil, activation of microglia/macrophages, and reactive astrogliosis, accompanied by an increase in CD206 positive microglia/macrophages which exhibit phagocytic characteristics. Adjudin concurrently decreased the generation of proinflammatory cytokines, such as TNF-α and IL-1β. Additionally, adjudin increased the expression of aquaporin 4 (AQP4). Furthermore, adjudin reduced brain cell apoptosis, as evidenced by increased expression of anti-apoptotic protein Bcl-2, and decreased expression of apoptosis related proteins Bax, cleaved caspase-3 and fewer TUNEL positive cells. Our data suggest that adjudin protects against ICH-induced secondary brain injury and may serve as a potential neuroprotective agent for ICH treatment.

CC Chemokine Family Members' Modulation as a Novel Approach for Treating Central Nervous System and Peripheral Nervous System Injury-A Review of Clinical and Experimental Findings

Despite significant progress in modern medicine and pharmacology, damage to the nervous system with various etiologies still poses a challenge to doctors and scientists. Injuries lead to neuroimmunological changes in the central nervous system (CNS), which may result in both secondary damage and the development of tactile and thermal hypersensitivity. In our review, based on the analysis of many experimental and clinical studies, we indicate that the mechanisms occurring both at the level of the brain after direct damage and at the level of the spinal cord after peripheral nerve damage have a common immunological basis. This suggests that there are opportunities for similar pharmacological therapeutic interventions in the damage of various etiologies. Experimental data indicate that after CNS/PNS damage, the levels of 16 among the 28 CC-family chemokines, i.e., CCL1, CCL2, CCL3, CCL4, CCL5, CCL6, CCL7, CCL8, CCL9, CCL11, CCL12, CCL17, CCL19, CCL20, CCL21, and CCL22, increase in the brain and/or spinal cord and have strong proinflammatory and/or pronociceptive effects. According to the available literature data, further investigation is still needed for understanding the role of the remaining chemokines, especially six of them which were found in humans but not in mice/rats, i.e., CCL13, CCL14, CCL15, CCL16, CCL18, and CCL23. Over the past several years, the results of studies in which available pharmacological tools were used indicated that blocking individual receptors, e.g., CCR1 (J113863 and BX513), CCR2 (RS504393, CCX872, INCB3344, and AZ889), CCR3 (SB328437), CCR4 (C021 and AZD-2098), and CCR5 (maraviroc, AZD-5672, and TAK-220), has beneficial effects after damage to both the CNS and PNS. Recently, experimental data have proved that blockades exerted by double antagonists CCR1/3 (UCB 35625) and CCR2/5 (cenicriviroc) have very good anti-inflammatory and antinociceptive effects. In addition, both single (J113863, RS504393, SB328437, C021, and maraviroc) and dual (cenicriviroc) chemokine receptor antagonists enhanced the analgesic effect of opioid drugs. This review will display the evidence that a multidirectional strategy based on the modulation of neuronal-glial-immune interactions can significantly improve the health of patients after CNS and PNS damage by changing the activity of chemokines belonging to the CC family. Moreover, in the case of pain, the combined administration of such antagonists with opioid drugs could reduce therapeutic doses and minimize the risk of complications.

Pterostilbene attenuates microglial inflammation and brain injury after intracerebral hemorrhage in an OPA1-dependent manner

Microglial activation and subsequent inflammatory responses are critical processes in aggravating secondary brain injury after intracerebral hemorrhage (ICH). Pterostilbene (3', 5'-dimethoxy-resveratrol) features antioxidant and anti-inflammation properties and has been proven neuroprotective. In this study, we aimed to explore whether Pterostilbene could attenuate neuroinflammation after experimental ICH, as well as underlying molecular mechanisms. Here, a collagenase-induced ICH in mice was followed by intraperitoneal injection of Pterostilbene (10 mg/kg) or vehicle once daily. PTE-treated mice performed significantly better than vehicle-treated controls in the neurological behavior test after ICH. Furthermore, our results showed that Pterostilbene reduced lesion volume and neural apoptosis, and alleviated blood-brain barrier (BBB) damage and brain edema. RNA sequencing and subsequent experiments showed that ICH-induced neuroinflammation and microglial proinflammatory activities were markedly suppressed by Pterostilbene treatment. With regard to the mechanisms, we identified that the anti-inflammatory effects of Pterostilbene relied on remodeling mitochondrial dynamics in microglia. Concretely, Pterostilbene reversed the downregulation of OPA1, promoted mitochondrial fusion, restored normal mitochondrial morphology, and reduced mitochondrial fragmentation and superoxide in microglia after OxyHb treatment. Moreover, conditionally deleting microglial OPA1 in mice largely countered the effects of Pterostilbene on alleviating microglial inflammation, BBB damage, brain edema and neurological impairment following ICH. In summary, we provided the first evidence that Pterostilbene is a promising agent for alleviating neuroinflammation and brain injury after ICH in mice, and uncovered a novel regulatory relationship between Pterostilbene and OPA1-mediated mitochondrial fusion.

CCL17 acts as an antitumor chemokine in micromilieu‐driven immune skewing

BACKGROUND

Chemokines are critical players in the local immune responses to tumors. CCL17 (thymus and activation-regulated chemokine, TARC) and CCL22 (macrophage-derived chemokine, MDC) can attract CCR4-bearing cells involving the immune landscape of cancer. However, their direct roles and functional states in tumors remain largely unclear.

METHODS

We analyzed the lymphoma-related scRNA-seq and bulk RNA-seq datasets and identified the CCL17/CCL22-CCR4 axis as the unique participant of the tumor microenvironment. Then we edited the A20 lymphoma cell line to express CCL17 and CCL22 and assessed their function using three mouse models (Balb/C mouse, Nude mouse, and NSG mouse). In addition, we retrospectively checked the relationship between the CCL17/CCL22-CCR4 axis and the survival rates of cancer patients.

RESULTS

The active CCL17/CCL22-CCR4 axis is a distinctive feature of the Hodgkin lymphoma microenvironment. CCR4 is widely expressed in immune cells but highly exists on the surface of NK, NKT, and Treg cells. The tumor model of Balb/C mice showed that CCL17 acts as an anti-tumor chemokine mediated by activated T cell response. In addition, the tumor model of Nude mice showed that CCL17 recruits NK cells for inhibiting lymphoma growth and enhances the NK-cDC1 interaction for resisting IL4i1-mediated immunosuppression. Interestingly, CCL17-mediated antitumor immune responses depend on lymphoid lineages but not mainly myeloid ones. Furthermore, we found CCL17/CCL22-CCR4 axis cannot be regarded as biomarkers of poor prognosis in most cancer types from the TCGA database.

CONCLUSION

We provided direct evidence of antitumor functions of CCL17 mediated by the recruitment of conventional T cells, NKT cells, and NK cells. Clinical survival outcomes of target gene (CCL17, CCL22, and CCR4) expression also identified that CCL17/CCL22-CCR4 axis is not a marker of poor prognosis.

Research progress of endogenous hematoma absorption after intracerebral hemorrhage

Non-traumatic intraparenchymal brain hemorrhage is referred to as intracerebral hemorrhage (ICH). Although ICH is associated with a high rate of disability and case fatality, active intervention can significantly lower the rate of severe disability. Studies have shown that the speed of hematoma clearance after ICH determines the patient's prognosis. Following ICH, depending on the hematoma volume and mass effect, either surgical- or medication-only conservative treatment is chosen. The goal of promoting endogenous hematoma absorption is more relevant because surgery is only appropriate for a small percentage of patients, and open surgery can cause additional trauma to patients. The primary method of removing hematoma after ICH in the future will involve understanding how to produce and manage macrophage/microglial endogenous phagocytic hematomas. Therefore, it is necessary to elucidate the regulatory mechanisms and key targets for clinical purposes.

P7C3-A20 Attenuates Microglial Inflammation and Brain Injury after ICH through Activating the NAD+/Sirt3 Pathway

Intracerebral hemorrhage (ICH) is lethal but lacks effective therapies. Nicotinamide adenine dinucleotide (NAD⁺) is a central metabolite indispensable for a broader range of fundamental intracellular biological functions. Reduction of NAD⁺ usually occurs after acute brain insults, and supplementation of NAD⁺ has been proven neuroprotective. P7C3-A20 is a novel compound featuring its ability to facilitate the flux of NAD⁺. In this study, we sought to determine the potential therapeutic value of P7C3-A20 in ICH. In collagenase-induced ICH mouse models, we found that P7C3-A20 treatment could diminish lesion volume, reduce blood-brain barrier (BBB) damage, mitigate brain edema, attenuate neural apoptosis, and improve neurological outcomes after ICH. Further, RNA sequencing and subsequent experiments revealed that ICH-induced neuroinflammation and microglial proinflammatory activities were significantly suppressed following P7C3-A20 treatment. Mitochondrial damage is an important trigger of inflammatory response. We examined mitochondrial morphology and function and found that P7C3-A20 could attenuate OxyHb-induced impairment of mitochondrial dynamics and functions in vitro. Mechanistically, Sirt3, an NAD⁺-dependent deacetylase located in mitochondria, was then found to play a vital role in the protection of P7C3-A20 against mitochondrial damage and inflammatory response. In rescue experiments, P7C3-A20 failed to exert those protective effects in microglia-specific Sirt3 conditional knockout (CKO) mice. Finally, preclinical research revealed a correlation between the plasma NAD⁺ level and the neurological outcome in ICH patients. These results demonstrate that P7C3-A20 is a promising therapeutic agent for neuroinflammatory injury after ICH and exerts protective actions, at least partly, in a Sirt3-dependent manner.

Role of Inflammatory Processes in Hemorrhagic Stroke

Hemorrhagic stroke is the deadliest form of stroke and includes the subtypes of intracerebral hemorrhage and subarachnoid hemorrhage. A common cause of hemorrhagic stroke in older individuals is cerebral amyloid angiopathy. Intracerebral hemorrhage and subarachnoid hemorrhage both lead to the rapid collection of blood in the central nervous system and generate inflammatory immune responses that involve both brain resident and infiltrating immune cells. These responses are complex and can contribute to both tissue recovery and tissue injury. Despite the interconnectedness of these major subtypes of hemorrhagic stroke, few reviews have discussed them collectively. The present review provides an update on inflammatory processes that occur in response to intracerebral hemorrhage and subarachnoid hemorrhage, and the role of inflammation in the pathophysiology of cerebral amyloid angiopathy-related hemorrhage. The goal is to highlight inflammatory processes that underlie disease pathology and recovery. We aim to discuss recent advances in our understanding of these conditions and identify gaps in knowledge with the potential to develop effective therapeutic strategies.

The roles of chemokines following intracerebral hemorrhage in animal models and humans

Intracerebral hemorrhage (ICH) is one common yet devastating stroke subtype, imposing considerable burdens on families and society. Current guidelines are limited to symptomatic treatments after ICH, and the death rate remains significant in the acute stage. Thus, it is crucial to promote research to develop new targets on brain injury after ICH. In response to hematoma formation, amounts of chemokines are released in the brain, triggering the infiltration of resident immune cells in the brain and the chemotaxis of peripheral immune cells via the broken blood-brain barrier. During the past decades, mounting studies have focused on the roles of chemokines and their receptors in ICH injury. This review summarizes the latest advances in the study of chemokine functions in the ICH. First, we provide an overview of ICH epidemiology and underlying injury mechanisms in the pathogenesis of ICH. Second, we introduce the biology of chemokines and their receptors in brief. Third, we outline the roles of chemokines in ICH according to subgroups, including CCL2, CCL3, CCL5, CCL12, CCL17, CXCL8, CXCL12, and CX3CL1. Finally, we summarize current drug usage targeting chemokines in ICH and other cardio-cerebrovascular diseases. This review discusses the expressions of these chemokines and receptors under normal or hemorrhagic conditions and cell-specific sources. Above all, we highlight the related data of these chemokines in the progression and outcomes of the ICH disease in preclinical and clinical studies and point to therapeutic opportunities targeting chemokines productions and interactions in treating ICH, such as accelerating hematoma absorption and alleviating brain edema.

Secukinumab alleviates cognitive impairment by attenuating oxidative stress and neuronal apoptosis via the IL-17RA/AKT/ERK1/2 pathway in a rat model of sepsis

BACKGROUND

Septic-associated encephalopathy (SAE) is a critical manifestation of sepsis that leads to long-term cognitive impairment. Interleukin (IL)-17A has been shown to mediate neuronal apoptosis in central nervous system diseases, while oxidative stress has been found to have a detrimental effect in SAE. However, the relationship between IL-17A and oxidative stress in SAE remains unclear. This study aimed to investigate the effects of secukinumab on alleviating cognitive impairment in a rat model of sepsis, as well as examine its underlying molecular mechanism of action.

METHODS

A total of 282 male 8-week-old Sprague-Dawley rats were randomly subjected to cecal ligation and puncture (CLP) or sham treatment followed by volume resuscitation immediately after surgery. Secukinumab was administered intranasally 1 h post-CLP. Rats were given the p-ERK activator ceramide C6 intracerebroventricularly (i.c.v) 24 h before CLP surgery. Recombinant rIL-17A was administered i.c.v. at 0 h in naive rats, followed by intraperitoneal injection of the AKT inhibitor GDC0068 1 h post-rIL-17A injection. Clinical scores, body weight, and survival rate were assessed. In addition, immunofluorescence staining, neurobehavioral tests, Nissl staining, and western blotting were performed. Cognitive function was assessed 15-20 days post-CLP using the Morris water maze test.

RESULTS

IL-17A and IL-17RA protein expression levels in the rat hippocampus increased and peaked 24 h post-CLP. Furthermore, IL-17RA was found to be expressed in neurons. The survival rate after CLP was 50%. Following CLP, an increased clinical score and significant decrease in body weight were observed. However, treatment with secukinumab led to a decrease in the clinical score of rats 24 h post-CLP. CLP resulted in spatial and memory impairment and anxiety-like behaviors in rats, while secukinumab treatment significantly alleviated cognitive impairment compared to the CLP group (p < 0.05). In addition, oxidative stress and neuronal apoptosis were found to be increased in the CLP group, while secukinumab significantly reduced oxidative stress and neuronal apoptosis in the hippocampus following CLP. Furthermore, secukinumab treatment led to a significant decrease in the protein expression levels of p-AKT, p-ERK1/2, Romo1, and Bax, together with increased Bcl-2 protein expression. Finally, treatment with ceramide C6 and GDC0068 abolished the neuroprotective effects of secukinumab post-CLP.

CONCLUSION

Our results demonstrated that secukinumab attenuated oxidative stress and neuronal apoptosis and partially ameliorated cognitive impairment via the IL-17RA/AKT/ERK1/2 pathway in a rat model of sepsis. Thus, secukinumab may be a potential therapeutic strategy for septic patients.

Exploring the pharmacological mechanism of Naoxueshu oral liquid in the treatment of intracerebral hemorrhage through weighted gene co-expression network analysis, network pharmacological and experimental validation

BACKGROUND

Intracerebral hemorrhage (ICH) is a life-threatening stroke subtype with high rates of disability and mortality. Naoxueshu oral liquid is a proprietary Chinese medicine that absorbs hematoma and exhibits neuroprotective effects in patients with ICH. However, the underlying mechanisms remain obscure.

PURPOSE

Exploring and elucidating the pharmacological mechanism of Naoxueshu oral liquid in the treatment of ICH.

STUDY DESIGN AND METHODS

The Gene Expression Omnibus (GEO) database was used to download the gene expression data on ICH. ICH-related hub modules were obtained by weighted gene co-expression network analysis (WGCNA) of differentially co-expressed genes (DEGs). The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses were conducted using the obtained key modules to identify the ICH-related signaling pathways. Network pharmacology technology was applied to forecast the targets of Naoxueshu oral liquid and to establish a protein-protein interaction (PPI) network of overlapping targets between Naoxueshu oral liquid and ICH. Functional annotation and enrichment pathway analyses of the intersectional targets were performed using the omicsbean database. Finally, we verified the therapeutic role and mechanism of Naoxueshu oral liquid in ICH through molecular docking and experiments.

RESULTS

Through the WGCNA analysis, combined with network pharmacology, it was found that immune inflammation was closely related to the early pathological mechanism of ICH. Naoxueshu oral liquid suppressed the inflammatory response; hence, it could be a potential drug for ICH treatment. Molecular docking further confirmed that the effective components of Naoxueshu oral liquid docked well with CD163. Finally, the experimental results showed that Naoxueshu oral liquid treatment in the ICH rat model attenuated neurological deficits and neuronal injury, decreased hematoma volume, and promoted hematoma absorption. In addition, Naoxueshu oral liquid treatment also significantly increased the levels of Arg-1, CD163, Nrf2, and HO-1 around hematoma after ICH.

CONCLUSION

This study demonstrated that Naoxueshu oral liquid attenuated neurological deficits and accelerated hematoma absorption, possibly by suppressing inflammatory responses, which might be related to the regulation of Nrf2/CD163/HO-1 that interfered with the activation of M2 microglia, thus accelerating the clearance and decomposition of hemoglobin in the hematoma.

The Critical Role of Erythrolysis and Microglia/Macrophages in Clot Resolution After Intracerebral Hemorrhage: A Review of the Mechanisms and Potential Therapeutic Targets

Intracerebral hemorrhage (ICH) is a common cerebrovascular disorder with high morbidity and mortality. Secondary brain injury after ICH, which is initiated by multiple hemolytic products during erythrolysis, has been identified as a critical factor accounting for the poor prognosis of ICH patients. Clot resolution and hematoma clearance occur immediately after ICH via erythrolysis and erythrophagocytosis. During this process, erythrolysis after ICH results in the release of hemoglobin and products of degradation along with rapid morphological changes in red blood cells (RBCs). Phagocytosis of deformed erythrocytes and products of degradation by microglia/macrophages accelerates hematoma clearance, which turns out to be neuroprotective. Thus, a better understanding of the mechanism of erythrolysis and the role of microglia/macrophages after ICH is urgently needed. In this review, the current research progresses on the underlying mechanism of erythrolysis and erythrophagocytosis, as well as several useful tools for the quantification of erythrolysis-induced brain injury, are summarized, providing potential intervention targets and possible treatment strategies for ICH patients.

TREM2 improves neurological dysfunction and attenuates neuroinflammation, TLR signaling and neuronal apoptosis in the acute phase of intracerebral hemorrhage

Neuroinflammation contributes to secondary brain injury following intracerebral hemorrhage (ICH). Triggering receptor expressed on myeloid cells 2 (TREM2) confers strong neuroprotective effect by suppressing neuroinflammatory response in experimental ischemic stroke. This study aimed to clarify the neuroprotective role of TREM2 and potential underlying mechanism in a mouse model of ICH and in vitro. Adeno-associated virus (AAV) and green fluorescent protein-lentivirus (GFP-LV) strategies were employed to enhance TREM2 expression in the C57/BL6 mice and BV2 cells, respectively. The adult male C57/BL6 mice were subjected to ICH by administration of collagenase-IV in 1 month after the AAV particles injection. An in vitro ICH model was performed with oxygen hemoglobin in BV2 cells. Toll-like receptor 4 (TLR4) antagonist TAK242 was applied at 6 h following ICH. Neurological function, TREM2, pro-inflammatory cytokines, brain water content and Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining were evaluated at 24 h following ICH. TLR4, NF-κB and mitogen-activated protein kinases (MAPK) signaling pathways were also determined by Western blot analysis at the same time point. The levels of TREM2 were increased at 12 h, peaked at 24 h and recovered on 7d following ICH. TREM2 overexpression ameliorated ICH induced neurological dysfunction, inhibited neuroinflammation, and attenuated apoptosis and brain edema. Further mechanistic study revealed that TREM2 overexpression inhibited TLR4 activation and NF-κB and MAPK signaling pathways. ICH increased the percentage of TUNEL-positive cells, which was markedly decreased by TREM2 overexpression. A similar improvement was also observed by the administration of TAK242 following ICH. TREM2 improves neurological dysfunction and attenuates neuroinflammation and neuronal apoptosis in the acute phase of ICH, which is, at least in part, mediated by negatively regulating TLR4 signaling pathway. These findings highlight TREM2 as a potential target for early brain injury following ICH.

Neuroinflammation of microglia polarization in intracerebral hemorrhage and its potential targets for intervention

Microglia are the resident immune cells of the central nervous system (CNS) and play a key role in neurological diseases, including intracerebral hemorrhage (ICH). Microglia are activated to acquire either pro-inflammatory or anti-inflammatory phenotypes. After the onset of ICH, pro-inflammatory mediators produced by microglia at the early stages serve as a crucial character in neuroinflammation. Conversely, switching the microglial shift to an anti-inflammatory phenotype could alleviate inflammatory response and incite recovery. This review will elucidate the dynamic profiles of microglia phenotypes and their available shift following ICH. This study can facilitate an understanding of the self-regulatory functions of the immune system involving the shift of microglia phenotypes in ICH. Moreover, suggestions for future preclinical and clinical research and potential intervention strategies are discussed.

Regulation of nuclear factor erythroid-2-related factor 2 as a potential therapeutic target in intracerebral hemorrhage

Hemorrhagic stroke can be categorized into several subtypes. The most common is intracerebral hemorrhage (ICH), which exhibits significant morbidity and mortality, affecting the lives of millions of people worldwide every year. Brain injury after ICH includes the primary injury that results from direct compression as well as stimulation by the hematoma and secondary brain injury (SBI) that is due to ischemia and hypoxia in the penumbra around the hematoma. A number of recent studies have analyzed the mechanisms producing the oxidative stress and inflammation that develop following hematoma formation and are associated with the ICH induced by the SBI as well as the resulting neurological dysfunction. Nuclear factor erythroid-2-related factor 2 (Nrf2) is a critical component in mediating oxidative stress and anti-inflammatory response. We summarize the pathological mechanisms of ICH focusing on oxidative stress and the regulatory role of Nrf2, and review the mechanisms regulating Nrf2 at the transcriptional and post-transcriptional levels by influencing gene expression levels, protein stability, subcellular localization, and synergistic effects with other transcription factors. We further reviewing the efficacy of several Nrf2 activators in the treatment of ICH in experimental ICH models. Activation of Nrf2 might produce antioxidant, anti-inflammatory, and neuron-protection effects, which could potentially be a focus for developing future treatments and prevention of ICH.

Ulinastatin alleviates early brain injury after intracerebral hemorrhage by inhibiting oxidative stress and neuroinflammation via ROS/MAPK/Nrf2 signaling pathway

Purpose:

Spontaneous intracerebral hemorrhage (ICH) is still a major public health problem, with high mortality and disability. Ulinastatin (UTI) was purified from human urine and has been reported to be anti-inflammatory, organ protective, and antioxidative stress. However, the neuroprotection of UTI in ICH has not been confirmed, and the potential mechanism is unclear. In the present study, we aimed to investigate the neuroprotection and potential molecular mechanisms of UTI in ICH-induced early brain injury in a C57BL/6 mouse model.

Methods:

The neurological score, brain water content, neuroinflammatory cytokine levels, oxidative stress levels, and neuronal damage were evaluated.

Results:

UTI treatment markedly increased the neurological score, alleviated brain edema, decreased the levels of the inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), IL-6, and NF-κB, decreased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA), and upregulated the levels of glutathione (GSH), superoxide dismutase (SOD), and Nrf2. This finding indicated that UTI-mediated inhibition of neuroinflammation and oxidative stress alleviated neuronal damage after ICH. The neuroprotective capacity of UTI is partly dependent on the ROS/MAPK/Nrf2 signaling pathway.

Conclusions:

UTI improves neurological outcomes in mice and reduces neuronal death by protecting against neural neuroinflammation and oxidative stress.

Regulation of microglia phagocytosis and potential involvement of exercise

Microglia are considered the main phagocytic cells in the central nervous system, remodeling neural circuits by pruning synapses during development. Microglial phagocytosis is also a crucial process in maintaining adult brain homeostasis and clearing potential toxic factors, which are recognized to be associated with neurodegenerative and neuroinflammatory disorders. For example, microglia can engulf amyloid-β plaques, myelin debris, apoptotic cells, and extracellular harmful substances by expressing a variety of specific receptors on the cell surface or by reprogramming intracellular glucose and lipid metabolism processes. Furthermore, physical exercise has been implicated to be one of the non-pharmaceutical treatments for various nervous system diseases, which is closely related to neuroplasticity and microglia functions including proliferation, activation, and phagocytosis. This review focuses on the central regulatory mechanisms related to microglia phagocytosis and the potential role of exercise training in this process.

Targeting Oxidative Stress and Inflammatory Response for Blood-Brain Barrier Protection in Intracerebral Hemorrhage

Significance: Blood-brain barrier (BBB) disruption is a major pathological change after intracerebral hemorrhage (ICH) and is both the cause and result of oxidative stress and of the immune response post-ICH. These processes contribute to ICH-induced brain injury. Recent Advances: After the breakdown of cerebral vessels, blood components, including erythrocytes and their metabolites, thrombin, and fibrinogen, can access the cerebral parenchyma through the compromised BBB, triggering oxidative stress and inflammatory cascades. These aggravate BBB disruption and contribute to further infiltration of blood components, resulting in a vicious cycle that exacerbates brain edema and neurological injury after ICH. Experimental and clinical studies have highlighted the role of BBB disruption in ICH-induced brain injury. Critical Issues: In this review, we focus on the strategies to protect the BBB in ICH. Specifically, we summarize the evidence and the underlying mechanisms, including the ICH-induced process of oxidative stress and inflammatory response, and we highlight the potential therapeutic targets to protect BBB integrity after ICH. Future Directions: Future studies should probe the mechanism of ferroptosis as well as oxidative stress-inflammation coupling in BBB disruption after ICH and investigate the effects of antioxidants and immunomodulatory agents in more ICH clinical trials. Antioxid. Redox Signal. 37, 115-134.

Dexmedetomidine exerts its protective effect on cerebral ischemia reperfusion injury in mice by inhibiting ferroptosis

OBJECTIVES

Stroke is one of the major diseases that can threaten human life and health. The incidence of ischemic stroke accounts for more than 70% of stroke. The mechanism of ischemia reperfusion (IR) injury caused by ischemic stroke is extremely complex. In recent years, dexmedetomidine has been increasingly studied in anti-cerebral IR injury as a common clinical anesthetic adjunct, but its specific mechanism is not fully understood. Therefore, this study aims to explore the effects and mechanisms of dexmedetomidine on cerebral IR injury in mice.

METHODS

The mouse middle cerebral artery occlusion (MCAO) model was prepared by modified suture method. Male ICR mice were randomly divided into a sham group, an IR group, an IR+D1 group (IR+administered 25 µg/kg dexmedetomidine), an IR+D2 group(IR+administered 50 µg/kg dexmedetomidine), an IR+D3 group (IR+administered 100 µg/kg dexmedetomidine), and an IR+D2+ML385 group (IR+administered 50 µg/kg dexmedetomidine and 30 mg/kg ML385). The neurologic behavior of mice was evaluated by Longa's five-point method. 2,3,5-triphenyltetrazolium chloride (TTC) staining was used to detect the percentage of cerebral infarct volume in mice. The protein expressions of nuclear factor erythroid 2-related factor 2 (Nrf2), transferrin receptor 1 (TFR1), glutathione peroxidase 4 (GPX4), and solute carrier family 7 member 11 (SLC7A11) in the cerebral tissues of mice were detected by Western blotting.Mitochondrial morphology was observed under the transmission electron microscope. The contents of MDA, Fe2+, and GSH in the cerebral tissues of mice were detected.

RESULTS

Compared with the sham group, neurobehavioral scores, cerebral infarct volume, the contents of MDA and Fe2+, as well as the protein expression of TFR1 were significantly increased; the contents of GSH and the protein expression of SLC7A11 and GPX4 were significantly reduced (all P<0.05); mitochondria in cerebral tissue were wrinkled, cristae were reduced, and membrane density was increased in the IR group. Compared with the IR group, neurobehavioral scores, cerebral infarction volume, MDA and Fe2+ contents, as well as the protein expression of TFR1 were significantly reduced; the contents of GSH and the protein expression of SLC7A11 and GPX4 were significantly increased (all P<0.05); mitochondrial damage in cerebral tissue was significantly relieved with the pre-treatment of dexmedetomidine. Compared with the IR+D2 group, neurobehavioral scores, cerebral infarction volume, MDA and Fe2+ contents, as well as the protein expression of TFR1 were significantly increased; the contents of GSH and the protein expression of SLC7A11 and GPX4 were significantly reduced (all P<0.05);mitochondria reappeared significantly damaged with the ML385 on the basis of dexmedetomidine pre-treatment.

CONCLUSIONS

The protective effect of dexmedetomidine on cerebral IR injury mice is related to its inhibition of ferroptosis, and the mechanism might be related to its regulation of Nrf2 expression.

The Novel Nrf2 Activator Omaveloxolone Regulates Microglia Phenotype and Ameliorates Secondary Brain Injury after Intracerebral Hemorrhage in Mice

The polarization of microglia is recognized as a crucial factor in reducing neuroinflammation and promoting hematoma clearance after intracerebral hemorrhage (ICH). Previous studies have revealed that redox components participate in the regulation of microglial polarization. Recently, the novel Nrf2 activator omaveloxolone (Omav) has been validated to improve neurological function in patients with neurodegenerative disorders by regulating antioxidant responses. In this study, we examined the efficacy of Omav in ICH. Omav significantly promoted Nrf2 nuclear accumulation and the expression of HO-1 and NQO1 in BV2 cells. In addition, both in vitro and in vivo experiments showed that Omav treatment inhibited M1-like activation and promoted the activation of the M2-like microglial phenotype. Omav inhibited OxyHb-induced ROS generation and preserved the function of mitochondria in BV2 cells. Intraperitoneal administration of Omav improved sensorimotor function in the ICH mouse model. Importantly, these effects were blocked by pretreatment with ML385, a selective inhibitor of Nrf2. Collectively, Omav modulated microglial polarization by activating Nrf2 and inhibiting ROS generation in ICH models, suggesting that it might be a promising drug candidate for the treatment of ICH.

Proteinase-activated receptor-1 antagonist attenuates brain injury via regulation of FGL2 and TLR4 after intracerebral hemorrhage in mice

Proteinase-activated receptor-1 (PAR1) antagonist plays a protective effect in brain injury. We investigated the potential function and mechanisms of PAR1 antagonist in ICH-induced brain injury. Results showed that PAR1 antagonist protected against neurobehavior deficits, brain edema and BBB integrity in ICH mice via activating JNK/ERK/p38 MAPK signaling pathway at 24h after ICH. In addition, ICH resulted in the increase of FGL2 and TLR4 expression over time, and phosphorylated JNK, ERK and p38 MAPK expression. Suppression of FGL2 and TLR4 alleviated brain injury and decreased the expression of p-JNK, p-ERK, p-p38 MAPK and p-IKKα at 24 h after ICH; while overexpression of them showed the opposite result. Moreover, the protective effect of PAR1 antagonist on ICH-induced brain injury was blocked by FGL2 or TLR4 overexpression, and the levels of p-JNK, p-ERK and p-p38 MAPK were inhibited. Furthermore, PAR1 antagonist combined with TLR4 antagonist markedly alleviated brain injury after ICH at 72h. Overall, PAR1 antagonist protected against short-term brain injury, and the effect of PAR1 antagonist on ICH-induced brain injury was mediated by FGL2 or TLR4.

Erythrophagocytosis by Microglia/Macrophage in Intracerebral Hemorrhage: From Mechanisms to Translation

Intracerebral hemorrhage (ICH) is a devastating condition characterized by hematoma related mass effect. Microglia/macrophage (M φ) are rapidly recruited in order to remove the red blood cells through erythrophagocytosis. Efficient erythrophagocytosis can detoxify hemolytic products and facilitate neurological recovery after ICH. The underlying mechanisms include modulation of inflammatory response and oxidative stress, among others. It is a dynamic process mediated by a cascade of signal transduction, including “find-me” signals, “eat-me” signals and a set of phagocytotic receptors-ligand pairs that may be exploited as therapeutic targets. This review summarizes mechanistic signaling pathways of erythrophagocytosis and highlights the potential of harnessing M φ-mediated phagocytosis for ICH treatment.

VSIG4 Attenuates NLRP3 and Ameliorates Neuroinflammation via JAK2-STAT3-A20 Pathway after Intracerebral Hemorrhage in Mice

Intracerebral hemorrhage (ICH) is a fatal cerebrovascular disease. Neuroinflammation plays an important pathological role in brain injury after ICH. NLRP3 contributes to the pathogenesis of ICH, but the underlying mechanisms regulating of NLRP3 remain elusive. V-set and immunoglobulin domain containing 4 (VSIG4), specifically expressed in resting tissue-resident macrophages, can deliver anti-inflammatory signals into various inflammatory diseases. However, the interaction between VSIG4 and NLRP3, as well as the underlying mechanisms after ICH have not been reported. C57BL/6 mice were subjected to the autologous blood injection ICH model. VSIG4 and NLRP3 levels of macrophages were detected following ICH. Ad-VSIG4 or controls were administered via intracerebroventricular (i.c.v) injection before ICH induction. STAT3 inhibitor (S31-201), JAK2 inhibitor (TG101348), or Ad-A20 RNAi was administered to investigate the role of JAK2-STAT3-A20 pathway in VSIG4-mediated neuroinflammation after ICH. Pro-inflammatory cytokine production, BBB disruption, brain water content, and neurological test were examined in ICH mice. VSIG4 levels were significantly decreased, and NLRP3 levels were significantly increased in the perihematomal brain tissues after ICH. Ad-VSIG4 attenuated NLRP3 levels and inhibited inflammation, as well as improved neurological function and reduced BBB disruption and brain water content. Furthermore, Ad-VSIG4 increased the protein levels of phosphorylated JAK2 and STAT3, and A20 levels at 24 h after ICH. STAT3 inhibitor, JAK2 inhibitor, and A20 RNAi abolished the beneficial effects of Ad-VSIG4 after ICH. In summary, these data suggested that VSIG4 attenuated NLRP3 and ameliorated neuroinflammation via JAK2-STAT3-A20 pathway after intracerebral hemorrhage in mice. VSIG4 might be an ideal therapeutic target for ICH patients.

Ulinastatin alleviates early brain injury after intracerebral hemorrhage by inhibiting necroptosis and neuroinflammation via MAPK/NF-κB signaling pathway

Purpose:

Spontaneous intracerebral hemorrhage (ICH) is a major public health problem with a huge economic burden worldwide. Ulinastatin (UTI), a serine protease inhibitor, has been reported to be anti-inflammatory, immune regulation, and organ protection by reducing reactive oxygen species production, and inflammation. Necroptosis is a programmed cell death mechanism that plays a vital role in neuronal cell death after ICH. However, the neuroprotection of UTI in ICH has not been confirmed, and the potential mechanism is unclear. The present study aimed to investigate the neuroprotection and potential molecular mechanisms of UTI in ICH-induced EBI in a C57BL/6 mouse model.

Methods:

The neurological score, brain water content, neuroinflammatory cytokine levels, and neuronal damage were evaluated. The anti-inflammation effectiveness of UTI in ICH patients also was evaluated.

Results:

UTI treatment markedly increased the neurological score, alleviate the brain edema, decreased the inflammatory cytokine TNF-α, interleukin‑1β (IL‑1β), IL‑6, NF‑κB levels, and RIP1/RIP3, which indicated that UTI-mediated inhibition of neuroinflammation, and necroptosis alleviated neuronal damage after ICH. UTI also can decrease the inflammatory cytokine of ICH patients. The neuroprotective capacity of UTI is partly dependent on the MAPK/NF-κB signaling pathway.

Conclusions:

UTI improves neurological outcomes in mice and reduces neuronal death by protecting against neural neuroinflammation, and necroptosis.

The neuroprotection of cerebrolysin after spontaneous intracerebral hemorrhage through regulates necroptosis via Akt/ GSK3β signaling pathway

PURPOSE

Spontaneous intracerebral hemorrhage (ICH) is a major cause of death and disability with a huge economic burden worldwide. Cerebrolysin (CBL) has been previously used as a nootropic drug. Necroptosis is a programmed cell death mechanism that plays a vital role in neuronal cell death after ICH. However, the precise role of necroptosis in CBL neuroprotection following ICH has not been confirmed.

METHODS

In the present study, we aimed to investigate the neuroprotective effects and potential molecular mechanisms of CBL in ICH-induced early brain injury (EBI) by regulating neural necroptosis in the C57BL/6 mice model. Mortality, neurological score, brain water content, and neuronal death were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining, Evans blue extravasation, Western blotting, and quantitative real-time polymerase chain reaction (PCR).

RESULTS

The results show that CBL treatment markedly increased the survival rate, neurological score, and neuron survival, and downregulated the protein expression of RIP1 and RIP3, which indicated that CBL-mediated inhibition of necroptosis, and ameliorated neuronal death after ICH. The neuroprotective capacity of CBL is partly dependent on the Akt/GSK3β signaling pathway.

CONCLUSIONS

CBL improves neurological outcomes in mice and reduces neuronal death by protecting against neural necroptosis.

Emerging therapeutic targets for cerebral edema

INTRODUCTION

Cerebral edema is a key contributor to death and disability in several forms of brain injury. Current treatment options are limited, reactive, and associated with significant morbidity. Targeted therapies are emerging based on a growing understanding of the molecular underpinnings of cerebral edema.

AREAS COVERED

We review the pathophysiology and relationships between different cerebral edema subtypes to provide a foundation for emerging therapies. Mechanisms for promising molecular targets are discussed, with an emphasis on those advancing in clinical trials, including ion and water channels (AQP4, SUR1-TRPM4) and other proteins/lipids involved in edema signaling pathways (AVP, COX2, VEGF, and S1P). Research on novel treatment modalities for cerebral edema [including recombinant proteins and gene therapies] is presented and finally, insights on reducing secondary injury and improving clinical outcome are offered.

EXPERT OPINION

Targeted molecular strategies to minimize or prevent cerebral edema are promising. Inhibition of SUR1-TRPM4 (glyburide/glibenclamide) and VEGF (bevacizumab) are currently closest to translation based on advances in clinical trials. However, the latter, tested in glioblastoma multiforme, has not demonstrated survival benefit. Research on recombinant proteins and gene therapies for cerebral edema is in its infancy, but early results are encouraging. These newer modalities may facilitate our understanding of the pathobiology underlying cerebral edema.

Intermittent hypoxia mimicking obstructive sleep apnea aggravates early brain injury following ICH via neuroinflammation and apoptosis

Spontaneous intracerebral hemorrhage (ICH) is a subtype of stroke associated with high mortality and morbidity due to the lack of effective therapy. Obstructive sleep apnea (OSA) has been reported to aggravate early brain injury (EBI) and worsen the overall outcome of patients with ICH. However, the precise role of OSA-mediated neuroinflammation and apoptosis following ICH has not been confirmed. The present study aimed to investigate the neuronal damage induced by OSA and the potential molecular mechanisms by which ICH-induced EBI regulates neural apoptosis in a C57BL/6 mouse ICH model. Mortality, neurological score, brain water content and neuronal death were evaluated by Evans blue extravasation, TUNEL staining, ELISA, analysis of reactive oxygen species/lipid peroxidation and western blotting. The results showed that OSA induction decreased survival rate, neurological score and neuron survival and upregulated the protein expression levels of Caspase-3, Bax, cytokines IL-1β, IL-6 and TNF-α and NF-κB, which indicated that OSA-mediated induction of apoptosis and neuroinflammation aggravated neuronal death following ICH. The molecular mechanism was partly dependent on the activating transcription factor/CHOP pathway. Taken together, the results demonstrated that OSA worsens neurological outcomes in mice and increases neuronal death by enhancing neural apoptosis and neuroinflammation.

Perampanel, an AMPAR antagonist, alleviates experimental intracerebral hemorrhage‑induced brain injury via necroptosis and neuroinflammation

Spontaneous intracerebral hemorrhage (ICH) is a subtype of stroke with high mortality and morbidity due to the lack of effective therapies. The alpha‑amino‑3‑hydroxy‑5‑methyl‑4‑isoxazolepropionic acid receptor antagonist perampanel has been reported to alleviate early brain injury following subarachnoid hemorrhage and traumatic brain injury by reducing reactive oxygen species, apoptosis, autophagy, and necroptosis. Necroptosis is a caspase‑independent programmed cell death mechanism that serves a vital role in neuronal cell death following ICH. However, the precise role of necroptosis in perampanel‑mediated neuroprotection following ICH has not been confirmed. The present study aimed to investigate the neuroprotective effects and potential molecular mechanisms of perampanel in ICH‑induced early brain injury by regulating neural necroptosis in C57BL/6 mice and in a hemin‑induced neuron damage cell culture model. Mortality, neurological score, brain water content, and neuronal death were evaluated. The results demonstrated that perampanel treatment increased the survival rate and neurological score, and increased neuron survival. In addition, perampanel treatment downregulated the protein expression levels of receptor interacting serine/threonine kinase (RIP) 1, RIP3, and mixed lineage kinase domain like pseudokinase, and of the cytokines IL‑1β, IL‑6, TNF‑α, and NF‑κB. These results indicated that perampanel‑mediated inhibition of necroptosis and neuroinflammation ameliorated neuronal death in vitro and in vivo following ICH. The neuroprotective capacity of perampanel was partly dependent on the PTEN pathway. Taken together, the results of the present study demonstrated that perampanel improved neurological outcomes in mice and reduced neuronal death by protecting against neural necroptosis and neuroinflammation.

Microglia: A Double-Edged Sword in Intracerebral Hemorrhage From Basic Mechanisms to Clinical Research

Microglia are the resident immune cells of the central nervous system (CNS). It is well established that microglia are activated and polarized to acquire different inflammatory phenotypes, either pro-inflammatory or anti-inflammatory phenotypes, which act as a critical component in the neuroinflammation following intracerebral hemorrhage (ICH). Microglia produce pro-inflammatory mediators at the early stages after ICH onset, anti-inflammatory microglia with neuroprotective effects appear to be suppressed. Previous research found that driving microglia towards an anti-inflammatory phenotype could restrict inflammation and engulf cellular debris. The principal objective of this review is to analyze the phenotypes and dynamic profiles of microglia as well as their shift in functional response following ICH. The results may further the understanding of the body's self-regulatory functions involving microglia following ICH. On this basis, suggestions for future clinical development and research are provided.

Recombinant CCL17-dependent CCR4 activation alleviates neuroinflammation and neuronal apoptosis through the PI3K/AKT/Foxo1 signaling pathway after ICH in mice

Background

Intracerebral hemorrhage (ICH), a devastating subtype of stroke, is associated with high mortality and morbidity. Neuroinflammation is an important factor leading to ICH-induced neurological injuries. C-C Chemokine Receptor 4 (CCR4) plays an important role in enhancing hematoma clearance after ICH. However, it is unclear whether CCR4 activation can ameliorate neuroinflammation and apoptosis of neurons following ICH. The aim of the present study was to examine the effects of recombinant CCL17 (rCCL17)-dependent CCR4 activation on neuroinflammation and neuronal apoptosis in an intrastriatal autologous blood injection ICH model, and to determine whether the PI3K/AKT/Foxo1 signaling pathway was involved.

Methods

Two hundred twenty-six adult (8-week-old) male CD1 mice were randomly assigned to sham and ICH surgery groups. An intrastriatal autologous blood injection ICH model was used. rCCL17, a CCR4 ligand, was delivered by intranasal administration at 1 h, 3 h, and 6 h post-ICH. CCL17 antibody was administrated by intraventricular injection at 1 h post-ICH. C021, a specific inhibitor of CCR4 and GDC0068, an AKT inhibitor were delivered intraperitoneally 1 h prior to ICH induction. Brain edema, neurobehavioral assessments, western blotting, Fluoro-Jade C staining, terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunofluorescence staining were conducted.

Results

Endogenous expression of CCL17 and CCR4 were increased following ICH, peaking at 5 days post-induction. CCR4 was found to co-localize with microglia, neurons, and astrocytes. rCCL17 treatment decreased brain water content, attenuated short- and long-term neurological deficits, deceased activation of microglia/macrophages and infiltration of neutrophils, and inhibited neuronal apoptosis in the perihematomal region post-ICH. Moreover, rCCL17 treatment post-ICH significantly increased the expression of CCR4, PI3K, phosphorylated AKT, and Bcl-2, while Foxo1, IL-1β, TNF-α, and Bax expression were decreased. The neuroprotective effects of rCCL17 were reversed with the administration of C021 or GDC0068.

Conclusions

rCCL17-dependent CCR4 activation ameliorated neurological deficits, reduced brain edema, and ameliorated neuroinflammation and neuronal apoptosis, at least in part, through the PI3K/AKT/Foxo1 signaling pathway after ICH. Thus, activation of CCR4 may provide a promising therapeutic approach for the early management of ICH.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02112-3.