Cleaning up after ICH: the role of Nrf2 in modulating microglia function and hematoma clearance

Intracerebral haemorrhage in multiple sclerosis: assessing the impact of disease-modifying medications

Multiple Sclerosis (MS) is a complex autoimmune disorder that significantly impacts the central nervous system, leading to a range of complications. While intracranial haemorrhage (ICH) is a rare but highly morbid complication, more common CNS complications include progressive multifocal leukoencephalopathy (PML) and other CNS infections. This severe form of stroke, known for its high morbidity and mortality rates, presents a critical challenge in the management of MS. The use of disease-modifying drugs (DMDs) in treating MS introduces a nuanced aspect to patient care, with certain medications like Dimethyl Fumarate and Fingolimod showing potential in reducing the risk of ICH, while others such as Alemtuzumab and Mitoxantrone are associated with an increased risk. Understanding the intricate relationship between these DMDs, the pathophysiological mechanisms of ICH, and the individualised aspects of each patient's condition is paramount. Factors such as genetic predispositions, existing comorbidities, and lifestyle choices play a crucial role in tailoring treatment approaches, emphasising the importance of a personalised, vigilant therapeutic strategy. The necessity for ongoing and detailed research cannot be overstated. It is crucial to explore the long-term effects of DMDs on ICH occurrence and prognosis in MS patients, aiming to refine clinical practices and promote patient-centric, informed therapeutic decisions. This approach ensures that the management of MS is not only comprehensive but also adaptable to the evolving understanding of the disease and its treatments.

The Emerging Role of Microglial Hv1 as a Target for Immunomodulation in Myelin Repair

In the central nervous system (CNS), the myelin sheath ensures efficient interconnection between neurons and contributes to the regulation of the proper function of neuronal networks. The maintenance of myelin and the well-organized subtle process of myelin plasticity requires cooperation among myelin-forming cells, glial cells, and neural networks. The process of cooperation is fragile, and the balance is highly susceptible to disruption by microenvironment influences. Reactive microglia play a critical and complicated role in the demyelination and remyelination process. Recent studies have shown that the voltage-gated proton channel Hv1 is selectively expressed in microglia in CNS, which regulates intracellular pH and is involved in the production of reactive oxygen species, underlying multifaceted roles in maintaining microglia function. This paper begins by examining the molecular mechanisms of demyelination and emphasizes the crucial role of the microenvironment in demyelination. It focuses specifically on the role of Hv1 in myelin repair and its therapeutic potential in CNS demyelinating diseases.

Mas receptor activation facilitates innate hematoma resolution and neurological recovery after hemorrhagic stroke in mice

BACKGROUND

Intracerebral hemorrhage (ICH) is a devastating neurological disease causing severe sensorimotor dysfunction and cognitive decline, yet there is no effective treatment strategy to alleviate outcomes of these patients. The Mas axis-mediated neuroprotection is involved in the pathology of various neurological diseases, however, the role of the Mas receptor in the setting of ICH remains to be elucidated.

METHODS

C57BL/6 mice were used to establish the ICH model by injection of collagenase into mice striatum. The Mas receptor agonist AVE0991 was administered intranasally (0.9 mg/kg) after ICH. Using a combination of behavioral tests, Western blots, immunofluorescence staining, hematoma volume, brain edema, quantitative-PCR, TUNEL staining, Fluoro-Jade C staining, Nissl staining, and pharmacological methods, we examined the impact of intranasal application of AVE0991 on hematoma absorption and neurological outcomes following ICH and investigated the underlying mechanism.

RESULTS

Mas receptor was found to be significantly expressed in activated microglia/macrophages, and the peak expression of Mas receptor in microglia/macrophages was observed at approximately 3-5 days, followed by a subsequent decline. Activation of Mas by AVE0991 post-treatment promoted hematoma absorption, reduced brain edema, and improved both short- and long-term neurological functions in ICH mice. Moreover, AVE0991 treatment effectively attenuated neuronal apoptosis, inhibited neutrophil infiltration, and reduced the release of inflammatory cytokines in perihematomal areas after ICH. Mechanistically, AVE0991 post-treatment significantly promoted the transformation of microglia/macrophages towards an anti-inflammatory, phagocytic, and reparative phenotype, and this functional phenotypic transition of microglia/macrophages by Mas activation was abolished by both Mas inhibitor A779 and Nrf2 inhibitor ML385. Furthermore, hematoma clearance and neuroprotective effects of AVE0991 treatment were reversed after microglia depletion in ICH.

CONCLUSIONS

Mas activation can promote hematoma absorption, ameliorate neurological deficits, alleviate neuron apoptosis, reduced neuroinflammation, and regulate the function and phenotype of microglia/macrophages via Akt/Nrf2 signaling pathway after ICH. Thus, intranasal application of Mas agonist ACE0991 may provide promising strategy for clinical treatment of ICH patients.

The phosphokinase activity of IRE1ɑ prevents the oxidative stress injury through miR-25/Nox4 pathway after ICH

BACKGROUND

Endoplasmic reticulum (ER) stress and oxidative stress are the major pathologies encountered after intracerebral hemorrhage (ICH). Inositol-requiring enzyme-1 alpha (IRE1α) is the most evolutionarily conserved ER stress sensor, which plays a role in monitoring and responding to the accumulation of unfolded/misfolded proteins in the ER lumen. Recent studies have shown that ER stress is profoundly related to oxidative stress in physiological or pathological conditions. The purpose of this study was to investigate the role of IRE1α in oxidative stress and the potential mechanism.

METHODS

A mouse model of ICH was established by autologous blood injection. The IRE1α phosphokinase inhibitor KIRA6 was administrated intranasally at 1 h after ICH, antagomiR-25 and agomiR-25 were injected intraventricularly at 24 h before ICH. Western blot analysis, RT-qPCR, immunofluorescence staining, hematoma volume, neurobehavioral tests, dihydroethidium (DHE) staining, H2O2 content, brain water content, body weight, Hematoxylin and Eosin (HE) staining, Nissl staining, Morris Water Maze (MWM) and Elevated Plus Maze (EPM) were performed.

RESULTS

Endogenous phosphorylated IRE1α (p-IRE1α), miR-25-3p, and Nox4 were increased in the ICH model. Administration of KIRA6 downregulated miR-25-3p expression, upregulated Nox4 expression, promoted the level of oxidative stress, increased hematoma volume, exacerbated brain edema and neurological deficits, reduced body weight, aggravated spatial learning and memory deficits, and increased anxiety levels. Then antagomiR-25 further upregulated the expression of Nox4, promoted the level of oxidative stress, increased hematoma volume, exacerbated brain edema and neurological deficits, whereas agomiR-25 reversed the effects promoted by KIRA6.

CONCLUSION

The IRE1α phosphokinase activity is involved in the oxidative stress response through miR-25/Nox4 pathway in the mouse ICH brain.

Ferroptosis regulation through Nrf2 and implications for neurodegenerative diseases

This article provides an overview of the background knowledge of ferroptosis in the nervous system, as well as the key role of nuclear factor E2-related factor 2 (Nrf2) in regulating ferroptosis. The article takes Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS) as the starting point to explore the close association between Nrf2 and ferroptosis, which is of clear and significant importance for understanding the mechanism of neurodegenerative diseases (NDs) based on oxidative stress (OS). Accumulating evidence links ferroptosis to the pathogenesis of NDs. As the disease progresses, damage to the antioxidant system, excessive OS, and altered Nrf2 expression levels, especially the inhibition of ferroptosis by lipid peroxidation inhibitors and adaptive enhancement of Nrf2 signaling, demonstrate the potential clinical significance of Nrf2 in detecting and identifying ferroptosis, as well as targeted therapy for neuronal loss and mitochondrial dysfunction. These findings provide new insights and possibilities for the treatment and prevention of NDs.

Nrf2 and Ferroptosis: A New Research Direction for Ischemic Stroke

Ischemic stroke (IS) is one of the leading causes of death and morbidity worldwide. As a novel form of cell death, ferroptosis is an important mechanism of ischemic stroke. Nuclear factor E2-related factor 2 (Nrf2) is the primary regulator of cellular antioxidant response. In addition to alleviating ischemic stroke nerve damage by reducing oxidative stress, Nrf2 regulates genes associated with ferroptosis, suggesting that Nrf2 may inhibit ferroptosis after ischemic stroke. However, the specific pathway of Nrf2 on ferroptosis in the field of ischemic stroke remains unclear. Therefore, this paper provides a concise overview of the mechanisms underlying ferroptosis, with a particular focus on the regulatory role of Nrf2. The discussion highlights the potential connections between Nrf2 and the mitigation of oxidative stress, regulation of iron metabolism, modulation of the interplay between ferroptosis and inflammation, as well as apoptosis. This paper focuses on the specific pathway of Nrf2 regulation of ferroptosis after ischemic stroke, providing scientific research ideas for further research on the treatment of ischemic stroke.

A Review of the Potential of Nuclear Factor [Erythroid-Derived 2]-like 2 Activation in Autoimmune Diseases

An autoimmune disease is the consequence of the immune system attacking healthy cells, tissues, and organs by mistake instead of protecting them. Inflammation and oxidative stress (OS) are well-recognized processes occurring in association with acute or chronic impairment of cell homeostasis. The transcription factor Nrf2 (nuclear factor [erythroid-derived 2]-like 2) is of major importance as the defense instrument against OS and alters anti-inflammatory activities related to different pathological states. Researchers have described Nrf2 as a significant regulator of innate immunity. Growing indications suggest that the Nrf2 signaling pathway is deregulated in numerous diseases, including autoimmune disorders. The advantageous outcome of the pharmacological activation of Nrf2 is an essential part of Nrf2-based chemoprevention and intervention in other chronic illnesses, such as neurodegeneration, cardiovascular disease, autoimmune diseases, and chronic kidney and liver disease. Nevertheless, a growing number of investigations have indicated that Nrf2 is already elevated in specific cancer and disease steps, suggesting that the pharmacological agents developed to mitigate the potentially destructive or transformative results associated with the protracted activation of Nrf2 should also be evaluated. The activators of Nrf2 have revealed an improvement in the progress of OS-associated diseases, resulting in immunoregulatory and anti-inflammatory activities; by contrast, the depletion of Nrf2 worsens disease progression. These data strengthen the growing attention to the biological properties of Nrf2 and its possible healing power on diseases. The evidence supporting a correlation between Nrf2 signaling and the most common autoimmune diseases is reviewed here. We focus on the aspects related to the possible effect of Nrf2 activation in ameliorating pathologic conditions based on the role of this regulator of antioxidant genes in the control of inflammation and OS, which are processes related to the progression of autoimmune diseases. Finally, the possibility of Nrf2 activation as a new drug development strategy to target pathogenesis is proposed.

Improving outcomes in intracerebral hemorrhage through microglia/macrophage-targeted IL-10 delivery with phosphatidylserine liposomes

Intracerebral hemorrhage (ICH) remains the most lethal type of stroke, and effective clinical therapies that can speed up hematoma resolution after ICH are still lacking. While the beneficial effects of IL-10 on ICH recovery have been demonstrated, the clinical translation of IL-10 requires effective delivery methods by which sufficient IL-10 can be delivered to ICH-affected regions in the brain. Here we report the use of a phosphatidylserine (PS) liposome (PSL)-based nanoparticle system for microglia/macrophage-targeted delivery of IL-10 in ICH. We first prepared IL-10-conjugated PSL (PSL-IL10) and characterized their immunomodulating effects in vitro. Then we evaluated the therapeutic effects, including hematoma absorption, short-term outcomes, and neuroinflammation, of intranasally administered PSL-IL10 (3 μg IL-10 per mouse, 2 h post-ICH) in a collagenase-induced ICH mouse model. We also isolated microglia/macrophages from the mouse brains with ICH to analyze their morphology, phagocytosis ability, and polarization. Our study reveals that, 1) PSL-IL10 treatment resulted in significantly improved outcomes and accelerated hematoma resolution in the acute phase of ICH; 2) PSL-IL10 inhibited glial activation and down-regulated pro-inflammatory cytokine production; 3) PSL-IL10 induced Iba1+ cells with a stronger phagocytosis ability; 4) PSL-IL10 activated STAT3 and upregulated CD36 expression in microglia/macrophage. These findings collectively show that PSL-IL10 is a promising nanotherapeutic for effectively ameliorating ICH.

Regulators of phagocytosis as pharmacologic targets for stroke treatment

Stroke, including ischemic and hemorrhagic stroke, causes massive cell death in the brain, which is followed by secondary inflammatory injury initiated by disease-associated molecular patterns released from dead cells. Phagocytosis, a cellular process of engulfment and digestion of dead cells, promotes the resolution of inflammation and repair following stroke. However, professional or non-professional phagocytes also phagocytose stressed but viable cells in the brain or excessively phagocytose myelin sheaths or prune synapses, consequently exacerbating brain injury and impairing repair following stroke. Phagocytosis includes the smell, eating and digestion phases. Notably, efficient phagocytosis critically depends on phagocyte capacity to take up dead cells continually due to the limited number of phagocytes vs. dead cells after injury. Moreover, phenotypic polarization of phagocytes occurring after phagocytosis is also essential to the proresolving and prorepair properties of phagocytosis. Much has been learned about the molecular signals and regulatory mechanisms governing the sense and recognition of dead cells by phagocytes during the smell and eating phase following stroke. However, some key areas remain extremely understudied, including the mechanisms involved in digestion regulation, continual phagocytosis and phagocytosis-induced phenotypic switching following stroke. Here, we summarize new discoveries related to the molecular mechanisms and multifaceted effects of phagocytosis on brain injury and repair following stroke and highlight the knowledge gaps in poststroke phagocytosis. We suggest that advancing the understanding of poststroke phagocytosis will help identify more biological targets for stroke treatment.

Zhilong Huoxue Tongyu capsule attenuates intracerebral hemorrhage induced redox imbalance by modulation of Nrf2 signaling pathway

Background: One of the severely debilitating and fatal subtypes of hemorrhagic stroke is intracerebral hemorrhage (ICH), which lacks an adequate cure at present. The Zhilong Huoxue Tongyu (ZLHXTY) capsule has been utilized effectively since last decade to treat ICH, in some provinces of China but the scientific basis for its mechanism is lacking. Purpose: To investigate the neuroprotective role of ZLHXTY capsules for ICH-induced oxidative injury through the regulation of redox imbalance with the Nrf2 signaling pathway. Methods: Autologous blood injection model of ICH in C57BL/6J mice was employed. Three treatment groups received ZLHXTY once daily through oral gavage at doses 0.35 g/kg, 0.7 g/kg, and 1.4 g/kg, started after 2 h and continued for 72 h of ICH induction. The neurological outcome was measured using a balance beam test. Serum was tested for inflammatory markers IL-1β, IL-6, and TNF-α through ELISA, oxidative stress through hydrogen peroxide content assay, and antioxidant status by total antioxidant capacity (T-AOC) assay. Nuclear extract from brain tissue was assayed for Nrf2 transcriptional factor activity. RT-qPCR was performed for Nfe2l2, Sod1, Hmox1, Nqo1, and Mgst1; and Western blotting for determination of protein expression of Nrf2, p62, Pp62, Keap, HO1, and NQO1. Fluoro-jade C staining was also used to examine neuronal damage. Results: ZLHXTY capsule treatment following ICH demonstrated a protective effect against oxidative brain injury. Neurological scoring showed improvement in behavioral outcomes. ELISA-based identification demonstrated a significant decline in the expression of serum inflammatory markers. Hydrogen peroxide content in serum was found to be reduced. The total antioxidant capacity was also reduced in serum, but the ZLHXTY extract showed a concentration-dependent increase in T-AOC speculating at its intrinsic antioxidant potential. Nrf2 transcriptional factor activity, mRNA and protein expression analyses revealed normalization of Nrf2 and its downstream targets, which were previously elevated as a result of oxidative stress induced by ICH. Neuronal damage was also reduced markedly after ZLHXTY treatment as revealed by Fluoro-jade C staining. Conclusion: ZLHXTY capsules possess an intrinsic antioxidant potential that can modulate the ICH-induced redox imbalance in the brain as revealed by the normalization of Nrf2 and its downstream antioxidant targets.

Sulforaphane Inhibits Foam Cell Formation and Atherosclerosis via Mechanisms Involving the Modulation of Macrophage Cholesterol Transport and the Related Phenotype

Sulforaphane (SFN), an isothiocyanate, is one of the major dietary phytochemicals found in cruciferous vegetables. Many studies suggest that SFN can protect against cancer and cardiometabolic diseases. Despite the proposed systemic and local vascular protective mechanisms, SFN's potential to inhibit atherogenesis by targeting macrophages remains unknown. In this study, in high fat diet fed ApoE-deficient (ApoE^-/-) mice, oral SFN treatment improved dyslipidemia and inhibited atherosclerotic plaque formation and the unstable phenotype, as demonstrated by reductions in the lesion areas in both the aortic sinus and whole aorta, percentages of necrotic cores, vascular macrophage infiltration and reactive oxygen species (ROS) generation. In THP-1-derived macrophages, preadministration SFN alleviated oxidized low-density lipoprotein (ox-LDL)-induced lipid accumulation, oxidative stress and mitochondrial injury. Moreover, a functional study revealed that peritoneal macrophages isolated from SFN-treated mice exhibited attenuated cholesterol influx and enhanced apolipoprotein A-I (apoA-I)- and high-density lipoprotein (HDL)-mediated cholesterol efflux. Mechanistic analysis revealed that SFN supplementation induced both intralesional and intraperitoneal macrophage phenotypic switching toward high expression of nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1) and ATP-binding cassette subfamily A/G member 1 (ABCA1/G1) and low expression of peroxisome proliferator-activated receptor γ (PPARγ) and cluster of differentiation 36 (CD36), which was further validated by the aortic protein expression. These results suggest that the regulation of macrophages' cholesterol transport and accumulation may be mainly responsible for SFN's potential atheroprotective properties, and the regulatory mechanisms might involve upregulating ABCA1/G1 and downregulating CD36 via the modulation of PPARγ and Nrf2.

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.

Augmenting hematoma-scavenging capacity of innate immune cells by CDNF reduces brain injury and promotes functional recovery after intracerebral hemorrhage

During intracerebral hemorrhage (ICH), hematoma formation at the site of blood vessel damage results in local mechanical injury. Subsequently, erythrocytes lyse to release hemoglobin and heme, which act as neurotoxins and induce inflammation and secondary brain injury, resulting in severe neurological deficits. Accelerating hematoma resorption and mitigating hematoma-induced brain edema by modulating immune cells has potential as a novel therapeutic strategy for functional recovery after ICH. Here, we show that intracerebroventricular administration of recombinant human cerebral dopamine neurotrophic factor (rhCDNF) accelerates hemorrhagic lesion resolution, reduces peri-focal edema, and improves neurological outcomes in an animal model of collagenase-induced ICH. We demonstrate that CDNF acts on microglia/macrophages in the hemorrhagic striatum by promoting scavenger receptor expression, enhancing erythrophagocytosis and increasing anti-inflammatory mediators while suppressing the production of pro-inflammatory cytokines. Administration of rhCDNF results in upregulation of the Nrf2-HO-1 pathway, but alleviation of oxidative stress and unfolded protein responses in the perihematomal area. Finally, we demonstrate that intravenous delivery of rhCDNF has beneficial effects in an animal model of ICH and that systemic application promotes scavenging by the brain's myeloid cells for the treatment of ICH.

The hallmark and crosstalk of immune cells after intracerebral hemorrhage: Immunotherapy perspectives

Intracerebral hemorrhage (ICH) is one of the most dangerous types of strokes with a high morbidity and mortality rate. Currently, the treatment of ICH is not well developed, mainly because its mechanisms are still unclear. Inflammation is one of the main types of secondary injury after ICH and catalyzes the adverse consequences of ICH. A large number of immune cells are involved in neuroinflammation, such as microglia, astrocytes, oligodendrocytes, lymphocytes, macrophages, and neutrophils. Nevertheless, the characteristics and crosstalk of immune cells have not been fully elucidated. In this review, we endeavor to delve into the respective characteristics of immune cells and their interactions in neuroimmune inflammation, and further elucidate favorable immunotherapeutic approaches regarding ICH, and finally present an outlook.

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.

Gene expression changes implicate specific peripheral immune responses to Deep and Lobar Intracerebral Hemorrhages in humans

The peripheral immune system response to Intracerebral Hemorrhage (ICH) may differ with ICH in different brain locations. Thus, we investigated peripheral blood mRNA expression of Deep ICH, Lobar ICH, and vascular risk factor-matched control subjects (n = 59). Deep ICH subjects usually had hypertension. Some Lobar ICH subjects had cerebral amyloid angiopathy (CAA). Genes and gene networks in Deep ICH and Lobar ICH were compared to controls. We found 774 differentially expressed genes (DEGs) and 2 co-expressed gene modules associated with Deep ICH, and 441 DEGs and 5 modules associated with Lobar ICH. Pathway enrichment showed some common immune/inflammatory responses between locations including Autophagy, T Cell Receptor, Inflammasome, and Neuroinflammation Signaling. Th2, Interferon, GP6, and BEX2 Signaling were unique to Deep ICH. Necroptosis Signaling, Protein Ubiquitination, Amyloid Processing, and various RNA Processing terms were unique to Lobar ICH. Finding amyloid processing pathways in blood of Lobar ICH patients suggests peripheral immune cells may participate in processes leading to perivascular/vascular amyloid in CAA vessels and/or are involved in its removal. This study identifies distinct peripheral blood transcriptome architectures in Deep and Lobar ICH, emphasizes the need for considering location in ICH studies/clinical trials, and presents potential location-specific treatment targets.

Prognostic significance of ferroptosis pathway gene signature and correlation with macrophage infiltration in cervical squamous cell carcinoma

BACKGROUND

Nuclear factor erythroid 2-related factor 2 (NFE2L2) plays a critical role in ferroptosis and biogenesis, however, its role in cervical squamous cell carcinoma (CESC) remains unknown. Therefore, in this study, we aimed to determine the role of NFE2L2 in CESC using multiomic analysis.

METHODS

All raw data were downloaded from The Cancer Genome Atlas (TCGA) and further validated in our dataset. NFE2L2 mRNA expression and methylation data on CESC were examined using the Tumor Immune Estimation Resource (TIMER) and University of Alabama at Birmingham Cancer Data Analysis Portal (UALCAN) database resources. NFE2L2 expression was examined in paraffin-embedded tissues from our cohort of 240 samples each of cancerous and non-cancerous tissues. Further, cervical cancer biopsies were genetically validated. TIMER and Tumor-Immune System Interactions Database (TISIDB) were used to analyze the correlation between NFE2L2 and cluster of differentiation 163 (CD163) with co-expressed genes in tumor-infiltrating immune cells.

RESULTS

The mRNA and protein levels of NFE2L2 were lower in CESC tissues than they were in adjacent tissues. Importantly, a low NFE2L2 level correlated with poor prognosis in CESC patients. NFE2L2 was specifically expressed in tumor macrophages and correlated with the tumor immune landscape and poor prognosis in the cohort data. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) enrichment analysis showed that co-expressed genes are mainly associated with multiple immune-related pathways. Furthermore, our data analysis revealed that NFE2L2 and macrophage CD163 expression levels were negatively correlated. Interestingly, we discovered multiple NFE2L2 binding sites in promoters of CD163.

CONCLUSION

This study confirmed the novel pyroptosis landscape in CESC, provided a role for NFE2L2 in the tumor microenvironment, and identified prognostic biomarkers for CESC and related immune infiltration.

Utility of serum nuclear factor erythroid 2-related factor 2 as a potential prognostic biomarker of severe traumatic brain injury in adults: A prospective cohort study

Objective

Nuclear factor erythroid 2-related factor 2 (Nrf2) may harbor endogenous neuroprotective role. We strived to ascertain the prognostic significance of serum Nrf2 in severe traumatic brain injury (sTBI).

Methods

This prospective cohort study included 105 controls and 105 sTBI patients, whose serum Nrf2 levels were quantified. Its relations to traumatic severity and 180-day overall survival, mortality, and poor prognosis (extended Glasgow Outcome Scale score 1–4) were discerned using multivariate analysis.

Results

There was a substantial enhancement of serum Nrf1 levels of patients (median, 10.9 vs. 3.3 ng/ml; P < 0.001), as compared to controls. Serum Nrf2 levels were independently correlative to Rotterdam computed tomography (CT) scores (ρ = 0.549, P < 0.001; t = 2.671, P = 0.009) and Glasgow Coma Scale (GCS) scores (ρ = −0.625, P < 0.001; t = −3.821, P < 0.001). Serum Nrf2 levels were significantly higher in non-survivors than in survivors (median, 12.9 vs. 10.3 ng/ml; P < 0.001) and in poor prognosis patients than in good prognosis patients (median, 12.5 vs. 9.4 ng/ml; P < 0.001). Patients with serum Nrf2 levels > median value (10.9 ng/ml) had markedly shorter 180-day overall survival time than the other remainders (mean, 129.3 vs. 161.3 days; P = 0.002). Serum Nrf2 levels were independently predictive of 180-day mortality (odds ratio, 1.361; P = 0.024), overall survival (hazard ratio, 1.214; P = 0.013), and poor prognosis (odds ratio, 1.329; P = 0.023). Serum Nrf2 levels distinguished the risks of 180-day mortality and poor prognosis with areas under receiver operating characteristic curve (AUCs) at 0.768 and 0.793, respectively. Serum Nrf2 levels > 10.3 ng/ml and 10.8 ng/ml discriminated patients at risk of 180-day mortality and poor prognosis with the maximum Youden indices of 0.404 and 0.455, respectively. Serum Nrf2 levels combined with GCS scores and Rotterdam CT scores for death prediction (AUC, 0.897; 95% CI, 0.837–0.957) had significantly higher AUC than GCS scores (P = 0.028), Rotterdam CT scores (P = 0.007), or serum Nrf2 levels (P = 0.006) alone, and the combination for poor outcome prediction (AUC, 0.889; 95% CI, 0.831–0.948) displayed significantly higher AUC than GCS scores (P = 0.035), Rotterdam CT scores (P = 0.006), or serum Nrf2 levels (P = 0.008) alone.

Conclusion

Increased serum Nrf2 levels are tightly associated with traumatic severity and prognosis, supporting the considerable prognostic role of serum Nrf2 in sTBI.

Elevated serum nuclear factor erythroid 2-related factor 2 levels contribute to a poor prognosis after acute supratentorial intracerebral hemorrhage: A prospective cohort study

Objective

Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcriptional factor for antioxidant response element-regulated genes. The purpose of this study was to assess the prognostic role of serum Nrf2 in intracerebral hemorrhage (ICH).

Materials and methods

In this prospective observational study, serum Nrf2 levels of 115 acute supratentorial ICH patients and 115 controls were gaged. Early neurologic deterioration (END) was defined as an increase of four or greater points in National Institutes of Health Stroke Scale (NIHSS) score or death at post-stroke 24 h. A poor outcome was referred to as the post-stroke 90-day modified Rankin scale (mRS) score of 3–6. END and a poor outcome were considered as the two prognostic parameters.

Results

As compared to controls, serum Nrf2 levels of patients were substantially elevated (P &lt; 0.001), with its levels increasing during the 6-h period immediately, peaking in 12–18 h, plateauing at 18–24 h, and decreasing gradually thereafter (P &lt; 0.05). Serum Nrf2 levels of patients were independently correlated with NIHSS score (t = 3.033; P = 0.003) and hematoma volume (t = 3.210; P = 0.002), independently predicted END (odds ratio 1.125; 95% confidence interval 1.027–1.232; P = 0.011) and poor outcome (odds ratio 1.217; 95% confidence interval 1.067–1.387; P = 0.013), as well as efficiently distinguished END (area under curve 0.771; 95% confidence interval 0.666–0.877; P &lt; 0.001) and poor outcome (area under curve 0.803; 95% confidence interval 0.725–0.882; P &lt; 0.001). Its predictive ability was equivalent to those of NIHSS score and hematoma volume (both P &gt; 0.05), and it also significantly improved their predictive abilities under receiver operating characteristic (ROC) curve (all P &lt; 0.05).

Conclusion

Elevated serum Nrf2 levels are closely correlated with severity, END, and 90-day poor outcome following ICH. Hence, Nrf2 may play an important role in acute brain injury after ICH, and serum Nrf2 may have the potential to serve as a prognostic biomarker of ICH.

Activation of Nrf2 to Optimise Immune Responses to Intracerebral Haemorrhage

Haemorrhage into the brain parenchyma can be devastating. This manifests as spontaneous intracerebral haemorrhage (ICH) after head trauma, and in the context of vascular dementia. Randomised controlled trials have not reliably shown that haemostatic treatments aimed at limiting ICH haematoma expansion and surgical approaches to reducing haematoma volume are effective. Consequently, treatments to modulate the pathophysiological responses to ICH, which may cause secondary brain injury, are appealing. Following ICH, microglia and monocyte derived cells are recruited to the peri-haematomal environment where they phagocytose haematoma breakdown products and secrete inflammatory cytokines, which may trigger both protective and harmful responses. The transcription factor Nrf2, is activated by oxidative stress, is highly expressed by central nervous system microglia and macroglia. When active, Nrf2 induces a transcriptional programme characterised by increased expression of antioxidant, haem and heavy metal detoxification and proteostasis genes, as well as suppression of proinflammatory factors. Therefore, Nrf2 activation may facilitate adaptive-protective immune cell responses to ICH by boosting resistance to oxidative stress and heavy metal toxicity, whilst limiting harmful inflammatory signalling, which can contribute to further blood brain barrier dysfunction and cerebral oedema. In this review, we consider the responses of immune cells to ICH and how these might be modulated by Nrf2 activation. Finally, we propose potential therapeutic strategies to harness Nrf2 to improve the outcomes of patients with ICH.

The Fate of Erythrocytes after Cerebral Hemorrhage

After a cerebral hemorrhage (intracerebral, subarachnoid, and intraventricular), extravasated blood contributes to both initial brain injury, via physical disruption and mass effect, and secondary injury, through the release of potentially neurotoxic and pro-inflammatory factors such as hemoglobin, iron, and peroxiredoxin-2. Erythrocytes are a major blood component and are a source of such damaging factors. Erythrolysis after cerebral hemorrhage releases potential neurotoxins, contributing to brain injury and edema. Alternatively, erythrocyte phagocytosis via microglia or macrophages may limit the spill of neurotoxins therefore limiting subsequent brain injury. The aim of this review is to discuss the process of phagocytosis of erythrocytes by microglia or macrophages after cerebral hemorrhage, the effect of erythrolysis on brain injury, novel mechanisms of erythrocyte and phagocyte egress from the brain, and exciting new targets in this pathway to attenuate brain injury. Understanding the fate of erythrocytes after cerebral hemorrhage may uncover additional potential interventions for clinical translational research.

Pulsed Electromagnetic Field Protects Against Brain Injury After Intracerebral Hemorrhage: Involvement of Anti-Inflammatory Processes and Hematoma Clearance via CD36

Intracerebral hemorrhage causes high mortality and morbidity, but its therapy methods are limited. In the present study, pulsed electromagnetic field (PEMF) was demonstrated to have beneficial effects on an intracerebral hemorrhage (ICH) model. This study explored the effects and underlying mechanisms of PEMF in a mouse model of ICH and cultured BV2 cells. PEMF was applied 4 hours after collagenase-induced ICH at day 0 and 4 hours per day for seven consecutive days. The expression levels of proinflammatory factors were assessed by ELISA kits and western blotting. Hematoma volume was measured by histological analysis. The effects of PEMF on phagocytosis of the erythrocytes were observed in cultured BV2 cells and ICH mouse models. Seven days after ICH, the hematoma volume was significantly reduced in PEMF-treated animals compared to nontreated mice. We found that PEMF decreased the hematoma volume and the expression levels of proinflammatory factors after ICH. Moreover, PEMF enhanced the erythrophagocytosis of microglia via CD36. Furthermore, we found that downregulation CD36 with Genistein blocked the effects of PEMF-induced hematoma clearance and anti-inflammations effects. Thus, the PEMF-mediated promotion of neurological functions may at least partly involve anti-inflammatory processes and hematoma clearance. These results suggest that PEMF treatment promoted the hematoma clearance and alleviated the inflammation after ICH.

Microglial phagocytosis and regulatory mechanisms after stroke

Stroke, including ischemic stroke and hemorrhagic stroke can cause massive neuronal death and disruption of brain structure, which is followed by secondary inflammatory injury initiated by pro-inflammatory molecules and cellular debris. Phagocytic clearance of cellular debris by microglia, the brain's scavenger cells, is pivotal for neuroinflammation resolution and neurorestoration. However, microglia can also exacerbate neuronal loss by phagocytosing stressed-but-viable neurons in the penumbra, thereby expanding the injury area and hindering neurofunctional recovery. Microglia constantly patrol the central nervous system using their processes to scour the cellular environment and start or cease the phagocytosis progress depending on the "eat me" or "don't eat me'' signals on cellular surface. An optimal immune response requires a delicate balance between different phenotypic states to regulate neuro-inflammation and facilitate reconstruction after stroke. Here, we examine the literature and discuss the molecular mechanisms and cellular pathways regulating microglial phagocytosis, their resulting effects in brain injury and neural regeneration, as well as the potential therapeutic targets that might modulate microglial phagocytic activity to improve neurological function after stroke.

The Role of Concomitant Nrf2 Targeting and Stem Cell Therapy in Cerebrovascular Disease

Despite the reality that a death from cerebrovascular accident occurs every 3.5 min in the United States, there are few therapeutic options which are typically limited to a narrow window of opportunity in time for damage mitigation and recovery. Novel therapies have targeted pathological processes secondary to the initial insult, such as oxidative damage and peripheral inflammation. One of the greatest challenges to therapy is the frequently permanent damage within the CNS, attributed to a lack of sufficient neurogenesis. Thus, recent use of cell-based therapies for stroke have shown promising results. Unfortunately, stroke-induced inflammatory and oxidative damage limit the therapeutic potential of these stem cells. Nuclear factor erythroid 2-related factor 2 (Nrf2) has been implicated in endogenous antioxidant and anti-inflammatory activity, thus presenting an attractive target for novel therapeutics to enhance stem cell therapy and promote neurogenesis. This review assesses the current literature on the concomitant use of stem cell therapy and Nrf2 targeting via pharmaceutical and natural agents, highlighting the need to elucidate both upstream and downstream pathways in optimizing Nrf2 treatments in the setting of cerebrovascular disease.

Phagocytic microglia and macrophages in brain injury and repair

AIMS

Phagocytosis is the cellular digestion of extracellular particles, such as pathogens and dying cells, and is a key element in the evolution of central nervous system (CNS) disorders. Microglia and macrophages are the professional phagocytes of the CNS. By clearing toxic cellular debris and reshaping the extracellular matrix, microglia/macrophages help pilot the brain repair and functional recovery process. However, CNS resident and invading immune cells can also magnify tissue damage by igniting runaway inflammation and phagocytosing stressed-but viable-neurons.

DISCUSSION

Microglia/macrophages help mediate intercellular communication and react quickly to the "find-me" signals expressed by dead/dying neurons. The activated microglia/macrophages then migrate to the injury site to initiate the phagocytic process upon encountering "eat-me" signals on the surfaces of endangered cells. Thus, healthy cells attempt to avoid inappropriate engulfment by expressing "do not-eat-me" signals. Microglia/macrophages also have the capacity to phagocytose immune cells that invade the injured brain (e.g., neutrophils) and to regulate their pro-inflammatory properties. During brain recovery, microglia/macrophages engulf myelin debris, initiate synaptogenesis and neurogenesis, and sculpt a favorable extracellular matrix to support network rewiring, among other favorable roles. Here, we review the multilayered nature of phagocytotic microglia/macrophages, including the molecular and cellular mechanisms that govern microglia/macrophage-induced phagocytosis in acute brain injury, and discuss strategies that tap into the therapeutic potential of this engulfment process.

CONCLUSION

Identification of biological targets that can temper neuroinflammation after brain injury without hindering the essential phagocytic functions of microglia/macrophages will expedite better medical management of the stroke recovery stage.

Increasing miR-126 Can Prevent Brain Injury after Intracerebral Hemorrhage in Rats by Regulating ZEB1

Background

Studies have found that microRNA (miR) is abnormally expressed in intracerebral hemorrhage (ICH) and is considered a therapeutic target for ICH.

Objective

To investigate the expression and role of miR-126 in the ICH rat model.

Methods

The ICH rat model was established, and miR-126 agomir and ZEB1 antagomir were injected into the lateral ventricle of ICH rats. The neurological function and water content of brain tissue were evaluated 48 hours later. Brain tissue around the hematoma of rats was taken to detect the expression of miR-126, ZEB1, glial fibrillary acidic protein (GFAP), and inflammatory cytokines (TNF-α, IL-1β, and IL-6). The luciferase reporter gene was applied to analyze the relationship between miR-126 and ZEB1.

Results

miR-126 was downregulated in the ICH rat model, while ZEB1 was upregulated. miR-126 agomir or ZEB1 antagomir injection could improve neurological function and cerebral edema in ICH rats. In addition, it could also reduce the expression of TNF-α, IL-1β, IL-6, and GFAP in the brain tissue of ICH rats. Luciferase reporter gene showed that ZEB1 could be targeted and regulated by miR-126.

Conclusion

miR-126 is downregulated in ICH rats, and miR-126 can reduce brain injury in ICH rats by inhibiting ZEB1 expression.

Traditional Chinese medicine use in the pathophysiological processes of intracerebral hemorrhage and comparison with conventional therapy

Intracerebral hemorrhage (ICH) refers to hemorrhage caused by non-traumatic vascular rupture in the brain parenchyma, which is characterized by acute onset, severe illness, and high mortality and disability. The influx of blood into the brain tissue after cerebrovascular rupture causes severe brain damage, including primary injury caused by persistent hemorrhage and secondary brain injury (SBI) induced by hematoma. The mechanism of brain injury is complicated and is a significant cause of disability after ICH. Therefore, it is essential to understand the mechanism of brain injury after ICH to develop drugs to prevent and treat ICH. Studies have confirmed that many traditional Chinese medicines (TCM) can reduce brain injury by improving neurotoxicity, inflammation, oxidative stress (OS), blood-brain barrier (BBB), apoptosis, and neurological dysfunction after ICH. Starting from the pathophysiological process of brain injury after ICH, this paper summarizes the mechanisms by which TCM improves cerebral injury after ICH and its comparison with conventional western medicine, so as to provide clues and a reference for the clinical application of TCM in the prevention and treatment of hemorrhagic stroke and further research and development of new drugs.

Nrf2 activation in the human brain after stroke due to supratentorial intracerebral haemorrhage: a case–control study

Aims

Pharmacological activation of the antioxidative transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) improves outcomes in experimental models of intracerebral haemorrhage (ICH). However, the Nrf2 pathway has not been previously studied in humans after ICH. Our study aims to address this gap.

Methods

We selected cases with fatal ICH from a prospective community-based inception cohort study and age-matched and sex-matched controls who died suddenly of non-neurological disease. We used immunohistochemistry to quantify Nrf2 (% total area stained overall and % of nuclei stained) and CD68 expression in controls and perihaematomal, ipsilateral and contralateral brain tissue from cases. We measured downstream haem oxygenase-1 (HMOX1) and NAD(P)H dehydrogenase quinone 1 [NQO1] expression using RNA in situ hybridisation.

Results

26 ICH cases (median age: 82 (IQR 76–86); 13 (50%) male) and eight controls (median age: 79 (IQR 77–80); 3 (37.5%) male) were included. We found no significant differences in overall % of Nrf2 staining between ICH cases and controls. However, the mean % of nuclei staining for Nrf2 seemed higher in perihaematomal compared with contralateral regions, although this was only statistically significant >60 days after ICH (25% (95% CI 17% to 33%) vs 14% (95% CI 11% to 17%), p=0.029). The percentage of perihaematomal tissue staining for CD68 was higher >60 days after ICH (6.75%, 95% CI 2.78% to 10.73%) compared with contralateral tissue (1.45%, 95% CI 0.93% to 1.96%, p=0.027) and controls (1.08%, 95% CI 0.20% to 1.97%, p=0.0008). RNA in situ hybridisation suggested increased abundance of HMOX1 and NQO1 transcripts in perihaematomal versus distant ipsilateral brain tissue obtained <7 days from onset of ICH.

Conclusions

We found evidence of Nrf2 activation in human brain tissue after ICH. Pharmacological augmentation of Nrf2 activation after ICH might be a promising therapeutic approach.

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.

Nrf2-BDNF-TrkB pathway contributes to cortical hemorrhage-induced depression, but not sex differences

Post-stroke depression, observed in 30-50% of stroke patients, negatively affects quality of life and mortality. The pathogenesis of post-stroke depression is complex, but heightened reactive oxygen species production and inflammation might be two key factors. We have reported that intracerebral hemorrhage (ICH) in cerebral cortex produces depression-like behavior in young male mice. Here, we found that mice lacking nuclear factor erythroid-derived 2-related factor 2 (Nrf2), a transcription factor that upregulates antioxidant proteins and trophic factors such as brain-derived neurotrophic factor (BDNF), had more severe depression-like behavior than wild-type mice at days 21 to 28 after cortical ICH (c-ICH). Moreover, the expression of Nrf2, heme oxygenase-1, BDNF, and TrkB were significantly decreased in wild-type mice after c-ICH. Interestingly, TP-500 (2 mg/kg), a potent Nrf2 inducer, decreased the inflammatory response and reactive oxygen species production on day 28 after c-ICH and improved depression-like behaviors. TrkB receptor antagonist ANA-12 abolished this anti-depression effect. Depression was more severe in female than in male wild-type mice after ICH, but TP-500 improved depression-like behavior in females. These results suggest that downregulation of Nrf2-BDNF-TrkB signaling contributes to development of post-stroke depression, and that Nrf2 inducer TP-500 might improve depression after c-ICH.

Iron toxicity in intracerebral hemorrhage: Physiopathological and therapeutic implications

Intracerebral hemorrhage (ICH)-induced brain injury is a continuous pathological process that involves the deterioration of neurological functions, such as sensory, cognitive or motor functions. Cytotoxic byproducts of red blood cell lysis, especially free iron, appear to be a significant pathophysiologic mechanism leading to ICH-induced injury. Free iron has a crucial role in secondary brain injury after ICH. Chelating iron may attenuate iron-induced neurotoxicity and may be developed as a therapeutic candidate for ICH treatment. In this review, we focused on the potential role of iron toxicity in ICH-induced injury and iron chelation therapy in the management of ICH. It will hopefully advance our understanding of the pathogenesis of ICH and lead to new approaches for treatment.

Microglia Phenotype and Intracerebral Hemorrhage: A Balance of Yin and Yang

Intracerebral hemorrhage (ICH) features extremely high rates of morbidity and mortality, with no specific and effective therapy. And local inflammation caused by the over-activated immune cells seriously damages the recovery of neurological function after ICH. Fortunately, immune intervention to microglia has provided new methods and ideas for ICH treatment. Microglia, as the resident immune cells in the brain, play vital roles in both tissue damage and repair processes after ICH. The perihematomal activated microglia not only arouse acute inflammatory responses, oxidative stress, excitotoxicity, and cytotoxicity to cause neuron death, but also show another phenotype that inhibit inflammation, clear hematoma and promote tissue regeneration. The proportion of microglia phenotypes determines the progression of brain tissue damage or repair after ICH. Therefore, microglia may be a promising and imperative therapeutic target for ICH. In this review, we discuss the dual functions of microglia in the brain after an ICH from immunological perspective, elaborate on the activation mechanism of perihematomal microglia, and summarize related therapeutic drugs researches.

Inflammation and Oxidative Stress: Potential Targets for Improving Prognosis After Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) has a high mortality rate and causes long-term disability in many patients, often associated with cognitive impairment. However, the pathogenesis of delayed brain dysfunction after SAH is not fully understood. A growing body of evidence suggests that neuroinflammation and oxidative stress play a negative role in neurofunctional deficits. Red blood cells and hemoglobin, immune cells, proinflammatory cytokines, and peroxidases are directly or indirectly involved in the regulation of neuroinflammation and oxidative stress in the central nervous system after SAH. This review explores the role of various cellular and acellular components in secondary inflammation and oxidative stress after SAH, and aims to provide new ideas for clinical treatment to improve the prognosis of SAH.

Central Nervous System Tissue Regeneration after Intracerebral Hemorrhage: The Next Frontier

Despite marked advances in surgical techniques and understanding of secondary brain injury mechanisms, the prognosis of intracerebral hemorrhage (ICH) remains devastating. Harnessing and promoting the regenerative potential of the central nervous system may improve the outcomes of patients with hemorrhagic stroke, but approaches are still in their infancy. In this review, we discuss the regenerative phenomena occurring in animal models and human ICH, provide results related to cellular and molecular mechanisms of the repair process including by microglia, and review potential methods to promote tissue regeneration in ICH. We aim to stimulate research involving tissue restoration after ICH.

Impaired meningeal lymphatic vessels exacerbate early brain injury after experimental subarachnoid hemorrhage

BACKGROUND AND PURPOSE

Blood that enters the subarachnoid space (SAS) and its breakdown products are neurotoxic and are the principal inducers of brain injury after subarachnoid hemorrhage (SAH). Recently, meningeal lymphatic vessels (MLVs) have been proven to play an important role in clearing erythrocytes that arise from SAH, as well as other macromolecular solutes. However, evidence demonstrating the relationship between MLVs and brain injury after SAH is still limited. Therefore, we performed this study to observe the effects of meningeal lymphatic impairment on early brain injury (EBI) after experimental SAH.

METHODS

The MLVs of C57BL/6 male adult mice were ablated by injecting Visudyne into the cisterna magna and transcranially photoconverting it with laser light. The MLVs were then examined by immunofluorescence staining for lyve-1. Next, both the MLV-ablated group and the control group (normal mice) underwent filament perforation to model SAH or sham operation. We assessed the cortical perfusion of all the mice before SAH induction, 5 min after SAH and 24 h after SAH. In addition, we evaluated neurological function deficits by Garcia scores and measured brain water content at 24 h post SAH. Then, neuroinflammation and neural apoptosis in the mouse brain were also examined.

RESULTS

Visudyne and transcranial photoconversion treatment notably ablated mouse MLVs. Five minutes after SAH induction, cortical perfusion was significantly impaired, and after 24 h, this impairment was ameliorated considerably in the control group but ameliorated only slightly or worsened in the MLV-ablated group. Additionally, the MLVablated group presented worse neurological function deficits and more severe brain edema than the control group. More notably, neuroinflammation and neural apoptosis were also observed.

CONCLUSION

Ablation of MLVs by Visudyne treatment exacerbated EBI after experimental SAH in mice. The worsening of EBI may have arisen from limited drainage of blood and other breakdown products, which are thought to cause brain edema, neuroinflammation, neuronal apoptosis and other pathological processes.

Melatonin Attenuates Thrombin-induced Inflammation in BV2 Cells and Then Protects HT22 Cells from Apoptosis

Increasing evidence has revealed that the uncontrolled thrombin-induced inflammation following intracerebral hemorrhage (ICH) plays a key role in ICH. Oxidative stress and neuroinflammatory responses are interdependent and bidirectional events. Melatonin is now recognized as an antioxidant and a free radical scavenger due to its roles in various physiological and pathological processes. The aim of this study was to explore the molecular mechanisms underlying the effects of melatonin on thrombin-induced microglial inflammation and its indirect protection of HT22 cells from p53-associated apoptosis. Melatonin treatment attenuated the expression of IL-1β, IL-18, cleaved caspase-1, and NLRP3 and decreased the production of reactive oxygen species (ROS), revealing its inhibitory effects against ROS-NLRP3 inflammasome activation. In further experiments investigating the protection conferred by melatonin, incubating HT22 cells with conditioned medium (CM) from thrombin-stimulated microglia induced HT22 cell apoptosis, and this effect was reversed after treating CM with either melatonin or N-acetyl-L-cysteine (NAC). Additionally, the Bax/Bcl-2 ratio and the levels of cleaved caspase-3 and p53 were markedly lower in the cells cultured in thrombin + melatonin-CM than in the cells cultured in thrombin-CM. Furthermore, the levels of MMP, ROS, SOD, MDA, and GSH-PX in bystander HT22 cells suggested that melatonin decreased HT22 cell apoptosis instigated via the p53-associated apoptotic pathway. Therefore, these findings strongly indicate the anti-inflammatory properties of melatonin that may suppress ROS-NLRP3 inflammasome activation and protect HT22 cells against apoptosis by inhibiting the ROS-mediated p53-dependent mitochondrial apoptotic pathway.

Potential therapeutic effects of Nrf2 activators on intracranial hemorrhage

Intracranial hemorrhage (ICH) is a devastating disease which induces high mortality and poor outcomes including severe neurological dysfunctions. ICH pathology is divided into two types: primary brain injury (PBI) and secondary brain injury (SBI). Although there are numerous preclinical studies documenting neuroprotective agents in experimental ICH models, no effective drugs have been developed for clinical use due to complicated ICH pathology. Oxidative and inflammatory stresses play central roles in the onset and progression of brain injury after ICH, especially SBI. Nrf2 is a crucial transcription factor in the anti-oxidative stress defense system. Under normal conditions, Nrf2 is tightly regulated by the Keap1. Under ICH pathological conditions, such as overproduction of reactive oxygen species (ROS), Nrf2 is translocated into the nucleus where it up-regulates the expression of several anti-oxidative phase II enzymes such as heme oxygenase-1 (HO-1). Recently, many reports have suggested the therapeutic potential of Nrf2 activators (including natural or synthesized compounds) for treating neurodegenerative diseases. Moreover, several Nrf2 activators attenuate ischemic stroke-induced brain injury in several animal models. This review summarizes the efficacy of several Nrf2 activators in ICH animal models. In the future, Nrf2 activators might be approved for the treatment of ICH patients.

Fluid metabolic pathways after subarachnoid hemorrhage

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular disease with high mortality and morbidity. In recent years, a large number of studies have focused on the mechanism of early brain injury (EBI) and delayed cerebral ischemia (DCI), including vasospasm, neurotoxicity of hematoma and neuroinflammatory storm, after aSAH. Despite considerable efforts, no novel drugs have significantly improved the prognosis of patients in phase III clinical trials, indicating the need to further re-examine the multifactorial pathophysiological process that occurs after aSAH. The complex pathogenesis is reflected by the destruction of the dynamic balance of the energy metabolism in the nervous system after aSAH, which prevents the maintenance of normal neural function. This review focuses on the fluid metabolic pathways of the central nervous system (CNS), starting with ruptured aneurysms, and discusses the dysfunction of blood circulation, cerebrospinal fluid (CSF) circulation and the glymphatic system during disease progression. It also proposes a hypothesis on the metabolic disorder mechanism and potential therapeutic targets for aSAH patients.

Involvement of Microglia in the Pathophysiology of Intracranial Aneurysms and Vascular Malformations-A Short Overview

Aneurysms and vascular malformations of the brain represent an important source of intracranial hemorrhage and subsequent mortality and morbidity. We are only beginning to discern the involvement of microglia, the resident immune cell of the central nervous system, in these pathologies and their outcomes. Recent evidence suggests that activated proinflammatory microglia are implicated in the expansion of brain injury following subarachnoid hemorrhage (SAH) in both the acute and chronic phases, being also a main actor in vasospasm, considerably the most severe complication of SAH. On the other hand, anti-inflammatory microglia may be involved in the resolution of cerebral injury and hemorrhage. These immune cells have also been observed in high numbers in brain arteriovenous malformations (bAVM) and cerebral cavernomas (CCM), although their roles in these lesions are currently incompletely ascertained. The following review aims to shed a light on the most significant findings related to microglia and their roles in intracranial aneurysms and vascular malformations, as well as possibly establish the course for future research.

Transforming growth factor‑β1 functions as a competitive endogenous RNA that ameliorates intracranial hemorrhage injury by sponging microRNA‑93‑5p

Intracerebral hemorrhage (ICH) has the highest mortality rate of all stroke subtypes but an effective treatment has yet to be clinically implemented. Transforming growth factor-β1 (TGF-β1) has been reported to modulate microglia-mediated neuroinflammation after ICH and promote functional recovery; however, the underlying mechanisms remain unclear. Non-coding RNAs such as microRNAs (miRNAs) and competitive endogenous RNAs (ceRNAs) have surfaced as critical regulators in human disease. A known miR-93 target, nuclear factor erythroid 2-related factor 2 (Nrf2), has been shown to be neuroprotective after ICH. It was hypothesized that TGF-β1 functions as a ceRNA that sponges miR-93-5p and thereby ameliorates ICH injury in the brain. Short interfering RNA (siRNA) was used to knock down TGF-β1 and miR-93 expression was also pharmacologically manipulated to elucidate the mechanistic association between miR-93-5p, Nrf2, and TGF-β1 in an in vitro model of ICH (thrombin-treated human microglial HMO6 cells). Bioinformatics predictive analyses showed that miR-93-5p could bind to both TGF-β1 and Nrf2. It was found that neuronal miR-93-5p was dramatically decreased in these HMO6 cells, and similar changes were observed in fresh brain tissue from patients with ICH. Most importantly, luciferase reporter assays were used to demonstrate that miR-93-5p directly targeted Nrf2 to inhibit its expression and the addition of the TGF-β1 untranslated region restored the levels of Nrf2. Moreover, an miR-93-5p inhibitor increased the expression of TGF-β1 and Nrf2 and decreased apoptosis. Collectively, these results identified a novel function of TGF-β1 as a ceRNA that sponges miR-93-5p to increase the expression of neuroprotective Nrf2 and decrease cell death after ICH. The present findings provided evidence to support miR-93-5p as a potential therapeutic target for the treatment of ICH.

Efferocytosis Mediated Modulation of Injury after Neonatal Brain Hypoxia-Ischemia

Neonatal brain hypoxia-ischemia (HI) is a leading cause of morbidity and long-term disabilities in children. While we have made significant progress in describing HI mechanisms, the limited therapies currently offered for HI treatment in the clinical setting stress the importance of discovering new targetable pathways. Efferocytosis is an immunoregulatory and homeostatic process of clearance of apoptotic cells (AC) and cellular debris, best described in the brain during neurodevelopment. The therapeutic potential of stimulating defective efferocytosis has been recognized in neurodegenerative diseases. In this review, we will explore the involvement of efferocytosis after a stroke and HI as a promising target for new HI therapies.

Divergent Functions of Tissue-Resident and Blood-Derived Macrophages in the Hemorrhagic Brain

[Figure: see text].

Significance of changes in the concentration of inflammatory factors in blood or cerebrospinal fluid in evaluating the severity and prognosis of spontaneous cerebral hemorrhage: A systematic review and meta-analysis

OBJECTIVE

Spontaneous intracerebral hemorrhage (SICH) often leads to severe disability, while inflammation plays an important role in SICH-induced secondary brain injury. The purpose of this study was to investigate the value of inflammatory factors as a means of evaluating the prognosis of SICH and to investigate the relationship between inflammatory factors and the severity and prognosis of SICH.

METHODS

The articles published before November 1 2020 were searched through PubMed, EMBASE, Cochrane library and web of science. Revman5.3 was used, using the inverse variance model to pool the SMD of TNF-a and interleukin concentration.

RESULTS

A total of 25 studies involving 3333 subjects were included in this paper. The concentration of TNF-α in the blood or cerebrospinal fluid of severe SICH patients was significantly higher than that of milder SICH patients or healthy population; SICH patients with high TNF-α concentration had a 1.06 times greater odds of poor outcomes than patients with low TNF-α concentration, odds ratio (OR) = 1.06[95% CI, 1.01-1.12]. The concentration of interleukin-6 (IL-6) in severe SICH patients was significantly higher than that in milder SICH patients; patients with high IL-6 concentration had a 2.61 times greater odds of poor outcomes than patients with low IL-6 concentration, OR = 2.61[95% CI, 1.79-3.80].

CONCLUSIONS

The detection of concentrations of TNF-α and IL-6 in peripheral blood may be helpful for the objective and quantitative assessment of the severity and prognosis of patients with SICH, and have certain significance for the selection of appropriate treatment options.

Albumin Reduces Oxidative Stress and Neuronal Apoptosis via the ERK/Nrf2/HO-1 Pathway after Intracerebral Hemorrhage in Rats

BACKGROUND

Albumin has been regarded as a potent antioxidant with free radical scavenging activities. Oxidative stress and neuronal apoptosis are responsible for its highly damaging effects on brain injury after intracerebral hemorrhage (ICH). Here, the present study investigated the neuroprotective effect of albumin against early brain injury after ICH and the potential underlying mechanisms.

METHODS

Adult male Sprague-Dawley rats were subjected to intrastriatal injection of autologous blood to induce ICH. Human serum albumin was given by intravenous injection 1 h after ICH. U0126, an inhibitor of extracellular signal-regulated kinase (ERK1/2), and ML385, an inhibitor of nuclear factor-E2-related factor 2 (Nrf2), were intraperitoneally administered 1 h before ICH induction. Short- and long-term neurobehavioral tests, western blotting, immunofluorescence staining, oxidative stress evaluations, and apoptosis measurements were performed.

RESULTS

Endogenous expression of albumin (peaked at 5 days) and heme oxygenase 1 (HO-1, peaked at 24 h) was increased after ICH compared with the sham group. Albumin and HO-1 were colocalized with neurons. Compared with vehicle, albumin treatment significantly improved short- and long-term neurobehavioral deficits and reduced oxidative stress and neuronal death at 72 h after ICH. Moreover, albumin treatment significantly promoted the phosphorylation of ERK1/2; increased the expression of Nrf2, HO-1, and Bcl-2; and downregulated the expression of Romo1 and Bax. U0126 and ML385 abolished the treatment effects of albumin on behavior and protein levels after ICH.

CONCLUSIONS

Albumin attenuated oxidative stress-related neuronal death may in part via the ERK/Nrf2/HO-1 signaling pathway after ICH in rats. Our study suggests that albumin may be a novel therapeutic method to ameliorate brain injury after ICH.

Microglia-derived interleukin-10 accelerates post-intracerebral hemorrhage hematoma clearance by regulating CD36

Hematoma size after intracerebral hemorrhage (ICH) significantly affects patient outcome. However, our knowledge of endogenous mechanisms that underlie hematoma clearance and the potential role of the anti-inflammatory cytokine interleukin-10 (IL-10) is limited. Using organotypic hippocampal slice cultures and a collagenase-induced ICH mouse model, we investigated the role of microglial IL-10 in phagocytosis ex vivo and hematoma clearance in vivo. In slice culture, exposure to hemoglobin induced IL-10 expression in microglia and enhanced phagocytosis that depended on IL-10-regulated expression of CD36. Following ICH, IL-10-deficient mice had more severe neuroinflammation, brain edema, iron deposition, and neurologic deficits associated with delayed hematoma clearance. Intranasal administration of recombinant IL-10 accelerated hematoma clearance and improved neurologic function. Additionally, IL-10-deficient mice had weakened in vivo phagocytic ability owing to decreased expression of microglial CD36. Moreover, loss of IL-10 significantly increased monocyte-derived macrophage infiltration and enhanced brain inflammation in vivo. These results indicate that IL-10 regulates microglial phagocytosis and monocyte-derived macrophage infiltration after ICH and that CD36 is a key phagocytosis effector regulated by IL-10. Leveraging the innate immune response to ICH by augmenting IL-10 signaling may provide a useful strategy for accelerating hematoma clearance and improving neurologic outcome in clinical translation studies.

Role of cannabinoids in alcohol-induced neuroinflammation

Alcohol is a psychoactive substance highly used worldwide, whose harmful use might cause a broad range of mental and behavioural disorders. Underlying brain impact, the neuroinflammatory response induced by alcohol is recognised as a key contributing factor in the progression of other neuropathological processes, such as neurodegeneration. These sequels are determined by multiple factors, including age of exposure. Strikingly, it seems that the endocannabinoid system modulation could regulate the alcohol-induced neuroinflammation. Although direct CB1 activation can worsen alcohol consequences, targeting other components of the expanded endocannabinoid system may counterbalance the pro-inflammatory response. Indeed, specific modulations of the expanded endocannabinoid system have been proved to exert anti-inflammatory effects, primarily through the CB2 and PPARγ signalling. Among them, some endo- and exogeneous cannabinoids can block certain pro-inflammatory mediators, such as NF-κB, thereby neutralizing the neuroinflammatory intracellular cascades. Furthermore, a number of cannabinoids are able to activate complementary anti-inflammatory pathways, which are necessary for the transition from chronically overactivated microglia to a regenerative microglial phenotype. Thus, cannabinoid modulation provides cooperative anti-inflammatory mechanisms that may be advantageous to resolve a pathological neuroinflammation in an alcohol-dependent context.

Therapeutic Potential of Carbon Monoxide (CO) and Hydrogen Sulfide (H2S) in Hemolytic and Hemorrhagic Vascular Disorders-Interaction between the Heme Oxygenase and H2S-Producing Systems

Over the past decades, substantial work has established that hemoglobin oxidation and heme release play a pivotal role in hemolytic/hemorrhagic disorders. Recent reports have shown that oxidized hemoglobins, globin-derived peptides, and heme trigger diverse biological responses, such as toll-like receptor 4 activation with inflammatory response, reprogramming of cellular metabolism, differentiation, stress, and even death. Here, we discuss these cellular responses with particular focus on their mechanisms that are linked to the pathological consequences of hemorrhage and hemolysis. In recent years, endogenous gasotransmitters, such as carbon monoxide (CO) and hydrogen sulfide (H₂S), have gained a lot of interest in connection with various human pathologies. Thus, many CO and H₂S-releasing molecules have been developed and applied in various human disorders, including hemolytic and hemorrhagic diseases. Here, we discuss our current understanding of oxidized hemoglobin and heme-induced cell and tissue damage with particular focus on inflammation, cellular metabolism and differentiation, and endoplasmic reticulum stress in hemolytic/hemorrhagic human diseases, and the potential beneficial role of CO and H₂S in these pathologies. More detailed mechanistic insights into the complex pathology of hemolytic/hemorrhagic diseases through heme oxygenase-1/CO as well as H₂S pathways would reveal new therapeutic approaches that can be exploited for clinical benefit.