Glymphatic Drainage Blocking Aggravates Brain Edema, Neuroinflammation via Modulating TNF-α, IL-10, and AQP4 After Intracerebral Hemorrhage in Rats

Cannabinoid Receptors Reduced Early Brain Damage by Regulating NOX-2 and the NLRP3 Inflammasome in an Animal Model of Intracerebral Hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is a leading cause of death and disability worldwide. Following the initial mechanical injury caused by hematoma expansion, a secondary injury occurs, characterized by the production of reactive oxygen species (ROS) generated by NOX-2 and neuroinflammation, which is exacerbated by the upregulation of the NLRP3 inflammasome. These conditions collectively aggravate brain damage. The endocannabinoid system (ECS), through the activation of the cannabinoid receptors, has demonstrated neuroprotective properties in various models of brain injury. However, the role of the ECS during ICH remains poorly understood, particularly regarding the action of the CB1 receptor in the activation of NOX-2 and the inflammasome. The present study investigates the neuroprotective effects of the cannabinoid receptor agonist WIN55,212-2 in an ICH animal model, specifically examining the roles of NLRP3 and NOX-2.

METHODS

Male C57BL/6 mice were subjected to ICH through an intracerebral injection of collagenase, followed by intraperitoneal administration of WIN55,212-2 and/or MCC950, a selective NLRP3 inhibitor. Various outcome measures were employed, including assessments of motor activity, hematoma volume, brain water content, and blood-brain barrier (BBB) permeability, which was evaluated using Evans blue assay. Additionally, the activity of NOX and the protein levels of crucial markers such as CB1, gp91phox, NLRP3, AQP4, and caspase-1 were measured via western blot analysis.

RESULT

The findings demonstrate that ICH induced a significant brain lesion characterized by hematoma formation, edema, BBB disruption, and subsequent motor impairments in the affected mice. Notably, these detrimental effects were markedly reduced in animals treated with WIN55,212-2. The study also revealed an activation of both NOX-2 and NLRP3 in response to ICH, which was reduced by cannabinoid receptor activation. Furthermore, the pharmacological inhibition of NLRP3 using MCC950 also led to a reduction in hematoma size, edema, and motor impairment secondary to ICH.

CONCLUSIONS

These results support a neuroprotective role of the cannabinoid receptor activation during ICH and suggest the involvement of NOX-2 and NLRP3.

Impaired Glymphatic Function in Acute Spontaneous Intracerebral Hemorrhage

BACKGROUND AND AIMS

Alterations in glymphatic function during the acute phase of acute spontaneous intracerebral hemorrhage (sICH) remain poorly understood. The aim of this study was to investigate whether, compared to healthy controls (HCs), the glymphatic system is impaired in patients with sICH, and to assess its association with hemorrhage and edema severity and outcome.

METHODS

Fifty-five sICH patients (including 46 supratentorial sICH and 9subtentorial sICH $$ \mathrm{subtentorial}\ \mathrm{sICH} $$ ) and 97 age- and sex-matched HCs underwent conventional MRI and diffusion tensor imaging. The diffusion along the perivascular space (DTI-ALPS) index, serving as a marker for glymphatic function, was computed, with supratentorial cases being categorized into ipsilateral and contralateral ALPS. Volumes of hemorrhage and edema were evaluated using susceptibility-weighted imaging (SWI) and T2-weighted magnetic resonance images, and the relative edema ratio was calculated. Clinical outcomes were categorized as favorable or poor based on a modified Rankin scale score of ≤ 2 or > 2 at 90 days.

RESULTS

sICH patients showed significantly lower DTI-ALPS values on the ipsilateral side compared to the average in the HC group (1.34 ± 0.24 vs. 1.46 ± 0.22, p = 0.003), whereas contralateral DTI-ALPS values in sICH patients did not differ significantly from HCs (1.48 ± 0.21 vs. 1.46 ± 0.22, p = 0.524). The ipsilateral DTI-ALPS was notably associated with both hemorrhage and relative edema volumes (both p < 0.05). A higher ipsilateral DTI-ALPS was independently associated with a favorable outcome at 90 days (odds ratio = 1.686 per 0.1 increase, p = 0.038).

CONCLUSIONS

The DTI-ALPS index, which reflects glymphatic functionality, is notably diminished on the ipsilateral side in acute sICH, correlating significantly with increased volumes of hemorrhage and edema. This study suggests that glymphatic dysfunction may contribute to the severity of clinical outcomes, and highlights the potential role of the glymphatic system in the pathophysiology of sICH.

Melatonin Regulates Glymphatic Function to Affect Cognitive Deficits, Behavioral Issues, and Blood-Brain Barrier Damage in Mice After Intracerebral Hemorrhage: Potential Links to Circadian Rhythms

BACKGROUND

Intracerebral hemorrhage (ICH) is a life-threatening cerebrovascular disorder with no specific pharmacological treatment. ICH causes significant behavioral deficits and cognitive impairments. Recent research suggests that circadian rhythm regulation could be a promising therapeutic strategy for ICH. Melatonin has been shown to alleviate glymphatic system (GS) dysfunction by regulating circadian rhythms, thereby improving depressive-like behaviors and postoperative sleep disorders in mice. However, its application in ICH treatment and specific mechanisms are not well understood.

METHODS

ICH models were created in 8-to-10-week-old mice using collagenase injection. Circadian rhythm modulation was tested with melatonin and luzindole. Behavioral and cognitive impairments were assessed with the modified neurological severity score, corner test, and novel object recognition test. Brain water content was measured by the dry/wet weight method, and cerebral perfusion was assessed by cerebral blood flow measurements. GS function was evaluated using RITC-dextran and Evans blue assays. Immunofluorescence and western blotting were used to analyze GS function and BBB permeability.

RESULTS

Melatonin restored GS transport after ICH, promoting hematoma and edema absorption, reducing BBB damage, and improving cognitive and behavioral outcomes. However, luzindole partially blocked these benefits and reversed the neuroprotective effects.

CONCLUSION

Melatonin and luzindole treatment affect GS function, BBB permeability, and cognitive-behavioral outcomes in mice with ICH. The underlying mechanism may involve the regulation of circadian rhythms.

New targets in spontaneous intracerebral hemorrhage

PURPOSE OF REVIEW

Intracerebral hemorrhage (ICH) is a devastating stroke with limited medical treatments; thus, timely exploration of emerging therapeutic targets is essential. This review focuses on the latest strategies to mitigate secondary brain injury post-ICH other than targeting surgery or hemostasis, addressing a significant gap in clinical practice and highlighting potential improvements in patient outcomes.

RECENT FINDINGS

Promising therapeutic targets to reduce secondary brain injury following ICH have recently been identified, including attenuation of iron toxicity and inhibition of ferroptosis, enhancement of endogenous resorption of hematoma, and modulation of perihematomal inflammatory responses and edema. Additionally, novel insights suggest the lymphatic system of the brain may potentially play a role in hematoma clearance and edema management. Various experimental and early-phase clinical trials have demonstrated these approaches may potentially offer clinical benefits, though most research remains in the preliminary stages.

SUMMARY

Continued research is essential to identify multifaceted treatment strategies for ICH. Clinical translation of these emerging targets could significantly enhance the efficacy of therapeutic interventions and potentially reduce secondary brain damage and improve neurological recovery. Future efforts should focus on large-scale clinical trials to validate these approaches, to pave the way for more effective treatment protocols for spontaneous ICH.

Electroacupuncture attenuates ferroptosis by promoting Nrf2 nuclear translocation and activating Nrf2/SLC7A11/GPX4 pathway in ischemic stroke

OBJECTIVE

Electroacupuncture has been shown to play a neuroprotective role following ischemic stroke, but the underlying mechanism remains poorly understood. Ferroptosis has been shown to play a key role in the injury process. In the present study, we wanted to explore whether electroacupuncture could inhibit ferroptosis by promoting nuclear factor erythroid-2-related factor 2 (Nrf2) nuclear translocation.

METHODS

The ischemic stroke model was established by middle cerebral artery occlusion/reperfusion (MCAO/R) in adult rats. These rats have been randomly divided into the EA + MCAO/R group, the MCAO/R group, the EA + MCAO/R + Brusatol group (the inhibitor of Nrf2), and the EA + MCAO/R + DMSO group, and the Sham group. The EA + MCAO/R group, EA + MCAO/R + Brusatol group, and the EA + MCAO/R + DMSO group received EA intervention 24 h after modeling for 7 consecutive days. The behavioral function was evaluated by Neurologic severity score (NSS), Garcia score, Foot-fault Test, and Rotarod Test. The infarct volume was detected by TTC staining, and the neuronal damage was observed by Nissl staining. The levels of Fe2+, reactive oxygen species (ROS), superoxide dismutase (SOD), and malondialdehyde (MDA) were measured by ELISA. The immunofluorescence and Western blotting were used to detect the expression of Total Nrf2, p-Nrf2, Nuclear Nrf2, and Cytoplasmic Nrf2, and the essential ferroptosis proteins, including glutathione peroxidase 4 (GPX4), solute carrier family 7 member 11 (SLC7A11) and ferritin heavy chain 1 (FTH1). The mitochondria were observed by transmission electron microscopy (TEM).

RESULTS

Electroacupuncture improved neurological deficits in rats model of MCAO/R, decreased the brain infarct volume, alleviated neuronal damage, inhibited the Fe2+, ROS, and MDA accumulation, increased SOD levels, increased the expression of GPX4, SLC7A11 and FTH1, and rescued injured mitochondria. Especially, we found that the electroacupuncture up-regulated the expression of Nrf2, and promoted phosphorylation of Nrf2 and nuclear translocation, However, Nrf2 inhibitor Brusatol reversed the neuroprotective effect of electroacupuncture.

CONCLUSION

Electroacupuncture can alleviate cerebral I/R injury-induced ferroptosis by promoting Nrf2 nuclear translocation. It is expected that these data will provide novel insights into the mechanisms of electroacupuncture protecting against cerebral I/R injury and potential targets underlying ferroptosis in the stroke.

Clearance rate of contrast extravasation after endovascular therapy is associated with functional outcome and mediated by cerebral edema

The brain's function of clearance and transport is closely related to the prognosis of acute ischemic stroke (AIS). In this study, we proposed a novel method, clearance rate of contrast extravasation (CROCE), to measure brain clearance and transport function in AIS patients undergoing endovascular therapy (EVT), and examined its association with cerebral edema and functional outcome. We conducted a pooled analysis of AIS patients of anterior circulation large vessel occlusion who underwent EVT in two academic hospitals. Patients who experienced contrast extravasation but not intracerebral hemorrhage following EVT were included. CROCE was defined as the mass of contrast agent cleared per hour on non-contrast CT (NCCT). Among the 215 patients finally included, we found that high CROCE was significantly associated with 90-day favorable functional outcome, and the association retained after adjustment for potential confounders. Different correlation analysis demonstrated a significant correlation between CROCE, cerebral edema, and functional outcome. Further mediation analysis revealed that cerebral edema mediated the effect of CROCE on functional outcome. These results revealed that CROCE may be a promising indicator of brain clearance function for patients who received EVT and had contrast extravasation.

Correlation Between Dietary Nutrition and Glymphatic System Activity in Healthy Participants

Background Dietary nutrition is an important approach to the prevention and treatment of the physical and mental states of humans. Nowadays, many studies show the neuroprotective and antioxidative effects of nutrients, such as B vitamins, zinc, and iron, on the central nervous system (CNS). However, there were no studies focusing on the relationships between the serum concentration of nutrients and the brain glymphatic system activity and macroscopic waste clearance system, including reactive oxygen species. Objectives This study tries to evaluate the relationships between them using diffusion tensor image analysis along the perivascular space (DTI‑ALPS) index as the proxy of glymphatic system activity. Methods The subjects were 159 healthy participants who underwent 1.5-Tesla DTI (diffusion tensor imaging) and blood sampling. We computed the DTI‑ALPS index and estimated the relationships between the DTI‑ALPS index and the serum concentrations of vitamin B6, vitamin B12, folate, zinc, ferritin, and iron. Results There were significant positive correlations of the DTI‑ALPS index with age and sex. Additionally, we found that age, sex, and serum zinc level were good independent variables that predicted the dependent variable, the DTI‑ALPS index, as revealed by multiple regression analyses. Conclusion We found a significant correlation between brain clearance system activity and serum zinc levels in healthy participants. Though zinc is known to play an important physiological role in the CNS, excessive zinc accumulation or zinc deficiency might induce neurodegeneration. Further works with varying serum zinc concentrations would reveal the neuroprotective effect of zinc in its proper concentration.

Altered brain glymphatic function on diffusion-tensor MRI in patients with spontaneous intracerebral hemorrhage: an exploratory study

Objectives

To investigate the function of the glymphatic system (GS) and its association with neuropsychological tests in spontaneous intracerebral hemorrhage (sICH) by diffusion tensor imaging analysis along the perivascular space (DTI-ALPS).

Methods

This retrospective study included 58 patients with sICH and 63 age- and sex-matched healthy controls (HCs). Partial correlation analyses were performed to examine the relationships between the DTI-ALPS index and radiological as well as clinical data. Mediation analyses were performed to explore the mediating role of the grey matter proportion (GM%) in the relationship between DTI-ALPS index and Montreal Cognitive Assessment (MoCA) score.

Results

Significantly lower DTI-ALPS index values were observed in sICH compared with HCs (FDR-p < 0.001). In the acute-subacute sICH group, the ALPS index was significantly correlated with hematoma volume (r = -0.572, FDR-p = 0.031). In the chronic sICH group, the ALPS index was significantly correlated with MoCA scores (r = 0.425, FDR-p = 0.014). In chronic sICH groups, GM% served as a significant mediator in the relationship between the DTI-ALPS index and MoCA scores (indirect effects β = 4.925, 95%CI: 0.028, 11.841). The ALPS index was identified as an independent prognostic indicator for unfavorable outcomes in sICH (β = -9.851, p = 0.018).

Conclusion

Our study demonstrated that the DTI-ALPS index decreased in sICH patients, suggesting potential functional impairment of the lymphoid system. Additionally, the DTI-ALPS index served as an independent predictor of poor 90-day prognosis. In the acute-subacute stage of sICH, the DTI-ALPS index had negative correlation with hematoma volume. In the chronic sICH group, the GM% partially mediated the relationship between the GS and cognitive function.

TRPML1 acts as a predisposing factor in lymphedema development by regulating the subcellular localization of aquaporin-3, -5

An imbalance in lymphatic fluid, whether it is caused by generation, transport, outflow, or dysfunctional vessels, can lead to lymphedema; however, the exact pathogenesis of this disease remains unclear. To explore the mechanism, we focused on the association among TRPML1, aquaporin-3 (AQP3), and aquaporin-5 (AQP5) in human lymphatic endothelial cells (HLECs). We explored the role of TRPML1 in altering the permeability of HLECs in lymphedema. Meanwhile, we constructed a disease model using gene-knockout mice to observe the effect of TRPML1 on inflammation and fibrosis in lymphedema sites. Our results indicate that TRPML1 not only regulates the localization of AQP3, -5 to the cell membrane but also increases HLEC permeability, disrupts lymphatic fluid transport, and mediates the development of chronic inflammation at the site of lymphedema. Our study suggests that TRPML1 is a precipitating factor in lymphedema. Our findings improve the understanding of TRPML1 and aquaporins in secondary lymphedema, providing valuable insights for future research.

Fasudil attenuates lipopolysaccharide-induced cognitive impairment in C57BL/6 mice through anti-oxidative and anti-inflammatory effects: Possible role of aquaporin-4

Introduction

Processes that generate systemic inflammation are strongly associated with neurodegenerative diseases. This study aimed to explore the potential anti-oxidative and anti-inflammatory effects of fasudil and its role in modulating aquaporin-4 (AQP-4) to improve cognitive impairment in a systemic inflammation model induced by lipopolysaccharide (LPS).

Method

fourty C57BL/6 mice were assigned to four groups, including sham, LPS, sham+fasudil, and LPS+fasudil). Intraperitoneal LPS was given (500 μg/kg/day) at hours 0, 24, 48, and 72, and fasudil (30 mg/kg) administered intraperitoneal injections 2 hours after LPS injection. The open field, Y-maze, and Novel object tasks was used to assess learning and memory. The levels of malondialdehyde (MDA), superoxide dismutase (SOD), interleukin-10 (IL-10), and tumor necrosis factor-α (TNF-α) in the hippocampus also measured as markers of oxidative stress and inflammation. Furthermore, the expression of AQP-4 measured in the intact and experimental groups.

Results

The results showed that Fasudil significantly improved memory and anxiety behavior induced by LPS in the open field maze, spatial recognition memory in the Y-maze, and performance in the novel object recognition task. It also mitigates hippocampal MDA and SOD levels. Additionally, fasudil ameliorated LPS-induced hippocampal levels of TNFα and IL-10 and increased hippocampal levels of AQP-4 expression in mice.

Conclusion

Our results suggest that fasudil in the LPS model of systemic inflammation could improve cognition by suppressing oxidative stress and inflammation and increasing AQP-4 protein expression. These findings highlighted the potential of fasudil as a neuroprotective agent. However, further research is required to fully understand its neuroprotective properties in the treatment of neurodegenerative disorders.

Panax Notoginseng Saponins promotes the meningeal lymphatic system-mediated hematoma absorption in intracerebral hemorrhage

BACKGROUND

Hematoma clearance is crucial for treating intracerebral hemorrhage (ICH). Currently, there is a lack of pharmacological therapy aimed at promoting hematoma absorption. Meningeal lymphatic system, as a drain of brain, is a potential therapeutic approach in ICH. Panax Notoginseng Saponins (PNS), proven to promote lymphangiogenesis in periphery, effectively reduces hematoma in ICH patients. However, the potential pharmacological effect of PNS on meningeal lymphatic vessels (MLVs) remains unknown.

PURPOSE

In this study, we aimed to investigate the impact of PNS on the meningeal lymphatic system and ICH.

METHODS

The collagenase-ICH model was conducted to investigate the effect of PNS. Behavioral tests, including modified neurological severity score (mNSS) and foot-fault test, and hematoma volume were used to estimate the neurological function and curative effect. The structure and drainage function of MLVs was detected by immunohistochemical staining. Visudyne intracisternal magna injection combined with red laser photoconversion was performed to ablate MLVs. RNA-sequencing was used to obtain mRNA profiles for mechanistic investigation.

RESULTS

The meningeal lymphatic drainage function was enhanced after ICH on day 14 without obvious lymphangiogenesis. Additionally, PNS further facilitated the process of drain with simultaneously inducing lymphangiogenesis. Moreover, ablation of MLVs by photoconverting of visudyne significantly blocked the benefits of neurological deficits improvement and hematoma absorption conducted by PNS. Furthermore, RNA-sequencing revealed that PNS regulated axonogenesis and inflammation, relying on the intact MLVs. In which, solute carrier family 17 member 7 (Slc17a7) and tumor necrosis factor (Tnf) were identified as bottleneck and hub nodes of the protein-protein interaction network of target genes, respectively.

CONCLUSION

PNS might be effective for ICH treatment by enhancing lymphangiogenesis and the meningeal lymphatic drainage function, thereby attenuating inflammation and promoting neurological recovery. The role of PNS in regulation of MLVs was investigated for the first time. This study provides a novel insight for PNS in the medical therapy of ICH.

Glymphatic system: a gateway for neuroinflammation

The glymphatic system is a relatively recently identified fluid exchange and transport system in the brain. Accumulating evidence indicates that glymphatic function is impaired not only in central nervous system disorders but also in systemic diseases. Systemic diseases can trigger the inflammatory responses in the central nervous system, occasionally leading to sustained inflammation and functional disturbance of the central nervous system. This review summarizes the current knowledge on the association between glymphatic dysfunction and central nervous system inflammation. In addition, we discuss the hypothesis that disease conditions initially associated with peripheral inflammation overwhelm the performance of the glymphatic system, thereby triggering central nervous system dysfunction, chronic neuroinflammation, and neurodegeneration. Future research investigating the role of the glymphatic system in neuroinflammation may offer innovative therapeutic approaches for central nervous system disorders.

Navigating Neurotoxicity and Safety Assessment of Nanocarriers for Brain Delivery: Strategies and Insights

Nanomedicine, an area that uses nanomaterials for theragnostic purposes, is advancing rapidly, particularly in the detection and treatment of neurodegenerative diseases. The design of nanocarriers can be optimized to enhance drug bioavailability and targeting to specific organs, improving therapeutic outcomes. However, clinical translation hinges on biocompatibility and safety. Nanocarriers can cross the blood-brain barrier (BBB), potentially causing neurotoxic effects through mechanisms such as oxidative stress, DNA damage, and neuroinflammation. Concerns about their accumulation and persistence in the brain make it imperative to carry out a nanotoxicological risk assessment. Generally, this involves identifying exposure sources and routes, characterizing physicochemical properties, and conducting cytotoxicity assays both in vitro and in vivo. The lack of a specialized regulatory framework creates substantial gaps, making it challenging to translate findings across development stages. Additionally, there is a pressing need for innovative testing methods due to constraints on animal use and the demand for high-throughput screening. This review examines the mechanisms of nanocarrier-induced neurotoxicity and the challenges in risk assessment, highlighting the impact of physicochemical properties and the advantages and limitations of current neurotoxicity evaluation models. Future perspectives are also discussed. Additional guidance is crucial to improve the safety of nanomaterials and reduce associated uncertainty. STATEMENT OF SIGNIFICANCE: Nanocarriers show tremendous potential for theragnostic purposes in neurological diseases, enhancing drug targeting to the brain, and improving biodistribution and pharmacokinetics. However, their neurotoxicity is still a major field to be explored, with only 5% of nanotechnology-related publications addressing this matter. This review focuses on the issue of neurotoxicity and safety assessment of nanocarriers for brain delivery. Neurotoxicity-relevant exposure sources, routes, and molecular mechanisms, along with the impact of the physicochemical properties of nanomaterials, are comprehensively described. Moreover, the different experimental models used for neurotoxicity evaluation are explored at length, including their main advantages and limitations. To conclude, we discuss current challenges and future perspectives for a better understanding of risk assessment of nanocarriers for neurobiomedical applications.

Didang Tang alleviates neuronal ferroptosis after intracerebral hemorrhage by modulating the PERK/eIF2α/ATF4/CHOP/GPX4 signaling pathway

Introduction

Ferroptosis is a crucial process contributing to neuronal damage following intracerebral hemorrhage (ICH). Didang Tang (DDT), a traditional therapeutic, has been used clinically to manage ICH for many years, yet the molecular mechanisms by which by DDT protects neurons from ferroptosis after ICH remain elusive.

Methods

This study utilized high-performance liquid chromatography-based fingerprint analysis to characterize DDT's chemical composition. An ICH rat model and hemin and erastin-induced PC12 cell ferroptosis models were developed to investigate DDT's neuroprotective mechanisms. Histological assessments of brain tissue morphology and iron deposition were performed using hematoxylin-eosin, Nissl, and Perl's blue staining. Neurological function was evaluated using Longa and Berderson scores, while lipid peroxidation was measured using biochemical assays and flow cytometry. Protein expression levels of ferroptosis- and endoplasmic reticulum stress (ERS)-related markers were analyzed via Western blotting and immunofluorescence.

Results

Our results demonstrated that DDT reduced hematoma volume, decreased iron deposition, lowered malondialdehyde (MDA) levels, and upregulated glutathione peroxidase (GPX4) and SLC7A11 expression in affected brain regions. Furthermore, DDT downregulated GRP78 expression and inhibited the PERK/eIF2α/ATF4/CHOP/GPX4 pathway, exerting strong neuroprotective effects. The fluorescence staining results of MAP2/GPX4 and MAP2/CHOP suggested that DDT may regulate neuronal ferroptosis and ERs to exert the protective effect. In vitro experiments using hemin- and erastin-induced neuron-derived PC12 cells as neuronal ferroptosis models developed in our laboratory corroborated these in vivo findings, showing increased survival and reduced lipid peroxidation in DDT-treated cells, along with similar inhibitory effects on ferroptosis and ERS. Molecular docking suggested that DDT components, such as sennoside B, amygdalin, rhein, and emodin, interact favorably with PERK/eIF2α/ATF4/CHOP signaling pathway proteins, highlighting their potential role in DDT's anti-ferroptosis effects.

Conclusion

DDT alleviates neuronal ferroptosis after ICH by modulating the PERK/eIF2α/ATF4/CHOP/GPX4 signaling pathway. Overall, this study provides novel insights into DDT's protective mechanisms against ICH-induced neuronal injury by modulating ferroptosis and ERS pathways, underscoring its potential as an effective therapeutic strategy.

Glymphatic pathway: An emerging perspective in the pathophysiology of neurodegenerative diseases

The central nervous system (CNS) is widely recognized as the only organ system without lymphatic capillaries to promote the removal of interstitial metabolic by-products. Thus, the newly identified glymphatic system which provides a pseudolymphatic activity in the nervous system has been focus of latest research in neurosciences. Also, findings reported that, sleep stimulates the elimination actions of glymphatic system and is linked to normal brain homeostatis. The CNS is cleared of potentially hazardous compounds via the glymphatic system, particularly during sleep. Any age-related alterations in brain functioning and pathophysiology of various neurodegenerative illnesses indicates the disturbance of the brain's glymphatic system. In this context, β-amyloid as well as tau leaves the CNS through the glymphatic system, it's functioning and CSF discharge markedly altered in elderly brains as per many findings. Thus, glymphatic failure may have a potential mechanism which may be therapeutically targetable in several neurodegenerative and age-associated cognitive diseases. Therefore, there is an urge to focus for more research into the connection among glymphatic system and several potential brain related diseases. Here, in our current review paper, we reviewed current research on the glymphatic system's involvement in a number of prevalent neurodegenerative and neuropsychiatric diseases and, we also discussed several therapeutic approaches, diet and life style modifications which might be used to acquire a more thorough performance and purpose of the glymphatic system to decipher novel prospects for clinical applicability for the management of these diseases.

The glymphatic system in migraine and other headaches

Glymphatic system is an emerging pathway of removing metabolic waste products and toxic solutes from the brain tissue. It is made of a network of perivascular spaces, filled in cerebrospinal and interstitial fluid, encompassing penetrating and pial vessels and communicating with the subarachnoid space. It is separated from vessels by the blood brain barrier and from brain tissue by the endfeet of the astrocytes rich in aquaporin 4, a membrane protein which controls the water flow along the perivascular space. Animal models and magnetic resonance (MR) studies allowed to characterize the glymphatic system function and determine how its impairment could lead to numerous neurological disorders (e.g. Alzheimer's disease, stroke, sleep disturbances, migraine, idiopathic normal pressure hydrocephalus). This review aims to summarize the role of the glymphatic system in the pathophysiology of migraine in order to provide new ways of approaching to this disease and to its therapy.

The role of astrocytes in the glymphatic network: a narrative review

To date, treatment of Central Nervous System (CNS) pathology has largely focused on neuronal structure and function. Yet, revived attention towards fluid circulation within the CNS has exposed the need to further explore the role of glial cells in maintaining homeostasis within neural networks. In the past decade, discovery of the neural glymphatic network has revolutionized traditional understanding of fluid dynamics within the CNS. Advancements in neuroimaging have revealed alternative pathways of cerebrospinal fluid (CSF) generation and efflux. Here, we discuss emerging perspectives on the role of astrocytes in CSF hydrodynamics, with particular focus on the contribution of aquaporin-4 channels to the glymphatic network. Astrocytic structural features and expression patterns are detailed in relation to their function in maintaining integrity of the Blood Brain Barrier (BBB) as part of the neurovascular unit (NVU). This narrative also highlights the potential role of glial dysfunction in pathogenesis of neurodegenerative disease, hydrocephalus, intracranial hemorrhage, ischemic stroke, and traumatic brain injury. The purpose of this literature summary is to provide an update on the changing landscape of scientific theory surrounding production, flow, and absorption of cerebrospinal fluid. The overarching aim of this narrative review is to advance the conception of basic, translational, and clinical research endeavors investigating glia as therapeutic targets for neurological disease.

Astrocytes in intracerebral hemorrhage: impact and therapeutic objectives

Intracerebral hemorrhage (ICH) manifests precipitously and profoundly impairs the neurological function in patients who are affected. The etiology of subsequent injury post-ICH is multifaceted, characterized by the intricate interplay of various factors, rendering therapeutic interventions challenging. Astrocytes, a distinct class of glial cells, interact with neurons and microglia, and are implicated in a series of pathophysiological alterations following ICH. A comprehensive examination of the functions and mechanisms associated with astrocytic proteins may shed light on the role of astrocytes in ICH pathology and proffer innovative therapeutic avenues for ICH management.

IL-10 protects against OPC ferroptosis by regulating lipid reactive oxygen species levels post stroke

Accumulation of reactive oxygen species (ROS), especially on lipids, induces massive cell death in neurons and oligodendrocyte progenitor cells (OPCs) and causes severe neurologic deficits post stroke. While small compounds, such as deferoxamine, lipostatin-1, and ferrostatin-1, have been shown to be effective in reducing lipid ROS, the mechanisms by which endogenously protective molecules act against lipid ROS accumulation and subsequent cell death are still unclear, especially in OPCs, which are critical for maintaining white matter integrity and improving long-term outcomes after stroke. Here, using mouse primary OPC cultures, we demonstrate that interleukin-10 (IL-10), a cytokine playing roles in reducing neuroinflammation and promoting hematoma clearance, significantly reduced hemorrhage-induced lipid ROS accumulation and subsequent ferroptosis in OPCs. Mechanistically, IL-10 activated the IL-10R/STAT3 signaling pathway and upregulated the DLK1/AMPK/ACC axis. Subsequently, IL-10 reprogrammed lipid metabolism and reduced lipid ROS accumulation. In addition, in an autologous blood injection intracerebral hemorrhagic stroke (ICH) mouse model, deficiency of the endogenous Il-10, specific knocking out Il10r or Dlk1 in OPCs, or administration of ACC inhibitor was associated with increased OPC cell death, demyelination, axonal sprouting, and the cognitive deficits during the chronic phase of ICH and vice versa. These data suggest that IL-10 protects against OPC loss and white matter injury by reducing lipid ROS, supporting further development of potential clinical applications to benefit patients with stroke and related disorders.

Phosphorylation of AQP4 by LRRK2 R1441G impairs glymphatic clearance of IFNγ and aggravates dopaminergic neurodegeneration

Aquaporin-4 (AQP4) is essential for normal functioning of the brain's glymphatic system. Impaired glymphatic function is associated with neuroinflammation. Recent clinical evidence suggests the involvement of glymphatic dysfunction in LRRK2-associated Parkinson's disease (PD); however, the precise mechanism remains unclear. The pro-inflammatory cytokine interferon (IFN) γ interacts with LRRK2 to induce neuroinflammation. Therefore, we examined the AQP4-dependent glymphatic system's role in IFNγ-mediated neuroinflammation in LRRK2-associated PD. We found that LRRK2 interacts with and phosphorylates AQP4 in vitro and in vivo. AQP4 phosphorylation by LRRK2 R1441G induced AQP4 depolarization and disrupted glymphatic IFNγ clearance. Exogeneous IFNγ significantly increased astrocyte expression of IFNγ receptor, amplified AQP4 depolarization, and exacerbated neuroinflammation in R1441G transgenic mice. Conversely, inhibiting LRRK2 restored AQP4 polarity, improved glymphatic function, and reduced IFNγ-mediated neuroinflammation and dopaminergic neurodegeneration. Our findings establish a link between LRRK2-mediated AQP4 phosphorylation and IFNγ-mediated neuroinflammation in LRRK2-associated PD, guiding the development of LRRK2 targeting therapy.

The glymphatic system for neurosurgeons: a scoping review

The discovery of the glymphatic system has revolutionized our understanding of cerebrospinal fluid (CSF) circulation and interstitial waste clearance in the brain. This scoping review aims to synthesize the current literature on the glymphatic system's role in neurosurgical conditions and its potential as a therapeutic target. We conducted a comprehensive search in PubMed and Scopus databases for studies published between January 1, 2012, and October 31, 2023. Studies were selected based on their relevance to neurosurgical conditions and glymphatic function, with both animal and human studies included. Data extraction focused on the methods for quantifying glymphatic function and the main results. A total of 67 articles were included, covering conditions such as idiopathic normal pressure hydrocephalus (iNPH), idiopathic intracranial hypertension (IIH), subarachnoid hemorrhage (SAH), stroke, intracranial tumors, and traumatic brain injury (TBI). Significant glymphatic dysregulation was noted in iNPH and IIH, with evidence of impaired CSF dynamics and delayed clearance. SAH studies indicated glymphatic dysfunction with the potential therapeutic effects of nimodipine and tissue plasminogen activator. In stroke, alterations in glymphatic activity correlated with the extent of edema and neurological recovery. TBI studies highlighted the role of the glymphatic system in post-injury cognitive outcomes. Results indicate that the regulation of aquaporin-4 (AQP4) channels is a critical target for therapeutic intervention. The glymphatic system plays a critical role in the pathophysiology of various neurosurgical conditions, influencing brain edema and CSF dynamics. Targeting the regulation of AQP4 channels presents as a significant therapeutic strategy. Although promising, the translation of these findings into clinical practice requires further human studies. Future research should focus on establishing non-invasive biomarkers for glymphatic function and exploring the long-term effects of glymphatic dysfunction.

Exploring the molecular mechanism of Yinao Fujian formula on ischemic stroke based on network pharmacology and experimental verification

Background

Ischemic stroke (IS) is a leading cause of long-term disability and even mortality, threatening people's lives. Yinao Fujian (YNFJ) formula is a Traditional Chinese Medicine formula that has been widely used to treat patients with IS. However, the molecular mechanism of YNFJ for the treatment of IS is still elusive. Our study aimed to explore the potential protective effect and the underlying mechanisms of YNFJ on IS using a network pharmacology approach coupled with experimental validation.

Materials and methods

Effective compounds of YNFJ were collected from BATMAN-TCM and TCMSP databases, while IS targets were obtained from GeneCards, OMIM, TTD and DrugBank databases. The protein-protein interaction (PPI) network was constructed to further screen the hub targets of YNFJ in IS treatment. GO and KEGG enrichment analyses were used to identify the critical biological processes and signaling pathways of YNFJ for IS. Moreover, Nissl staining, HE, TTC staining and Tunel staining were used in the MCAO model to prove the neuroprotective effect of YNFJ. Oxidative damage, inflammatory factor release and related pathways were tested in MCAO rat model and hypoxia-induced BV2 cell model, respectively.

Results

We found that YNFJ treatment significantly alleviated MCAO-induced nerve damage and apoptosis. Then, network pharmacology screening combined with literature research revealed IL6, TNF, PTGS2, NFKBIA and NFE2L2 as the critical targets in a PPI network. Moreover, the top 20 signaling pathways and biological processes associated with the protective effects of YNFJ on IS were enriched through GO and KEGG analyses. Further analysis indicated that NF-κB and Nrf2/HO-1 signaling pathways might be highly involved in the protective effects of YNFJ on IS. Finally, in vitro and in vivo experiments confirmed that YNFJ inhibited the release of inflammatory factors (IL-6 and TNF-α) and MDA content, and increased the activity of SOD. In terms of the mechanism, YNFJ inhibited the release of inflammatory factors by suppressing the NF-κB pathway and decreased the expression of iNOS and COX-2 to protect microglia from inflammation damage. In addition, YNFJ initiated the dissociation of Keap-1 and Nrf2, and activated the downstream protein HO-1, NQO1, thus decreasing oxidative stress.

Conclusion

Taken together, the findings in our research showed that the protective effects of YNFJ on IS were mainly achieved by regulating the NF-κB and Nrf2/HO-1 signaling pathways to inhibit oxidative stress damage and inflammatory damage of microglia.

Galectin-3 promotes brain injury by modulating the phenotype of microglia via binding TLR-4 after intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) is a stroke subtype with high mortality and disability rate, and neuroinflammation is involved in secondary brain injury. Galectin-3 (Gal-3) is one of the scaffold proteins of Galectins. Studies have indicated that Gal-3 plays an important role in the physiological and pathological state of the nervous system. Here we focus on the role of Gal-3 in ICH, especially in neuroinflammation.

METHODS

Injection of autologous blood into the right basal ganglia was used to simulate ICH injury, and the level of Gal-3 in brain was regulated by related means. The changes of Gal-3 were detected by western blot and immunofluorescence, the level of neuroinflammation by immunofluorescence staining and ELISA. Apoptosis and neuron loss were detected by TUNEL staining FJB staining and Nissl staining, and neurological deficits were judged by neurobehavioral tests.

RESULTS

The protein level of Gal-3 increased at 24 h after ICH. Downregulation of Gal-3 level can reduce the infiltration of M1-type microglia and peripheral inflammatory cells, thus alleviating post-ICH neuroinflammation, and reducing cell apoptosis and neuron loss in brain tissue. ICH-induced neurological damage was rescued. Meanwhile, the promotion in the expression level of Gal-3 increased neuroinflammatory activation and nerve cell death, aggravating ICH-induced brain injury.

CONCLUSIONS

This study proves that Gal-3 is involved in neuroinflammation and nerve damage after ICH. Gal-3 expression should not be encouraged early on to prevent neuroinflammation. which provides a new possibility for clinical treatment for ICH patients.

Connexin 43 Promotes Neurogenesis via Regulating Aquaporin-4 after Cerebral Ischemia

We aimed to test the effects of connexin43 (Cx43) on ischemic neurogenesis and examined whether it was dependent on aquaporin-4 (AQP4). We detected the expression of Cx43 and AQP4 in the ipsilateral subventricular zone (SVZ) and peri-infarct cortex after middle cerebral artery occlusion (MCAO). Also, we examined neurogenesis in the above regions via co-labeling of 5-bromo-2-deoxyuridine (BrdU)/neuronal nuclear antigen (NeuN) and BrdU/doublecortin (DCX). The effects of Cx43 and AQP4 were investigated by using two transgenic animals: heterozygous Cx43 (Cx43±) mice and AQP4 knockout (AQP4-/-) mice, and connexin mimetic peptide (CMP), a selective Cx43 blocker. We demonstrated AQP4 and Cx43 were co-expressed in the astrocytes after MCAO and the expression was highly increased in ipsilateral SVZ and peri-infarct cortex. Cx43± mice had larger infarction volumes and worse neurological function. Both BrdU/NeuN and BrdU/DCX co-labeled cells in the two regions were reduced in Cx43± and AQP4-/- mice compared to wild-type (WT) mice, suggesting Cx43 and AQP4 participated in neurogenesis of neural stem cells. Moreover, CMP decreased AQP4 expression and inhibited neurogenesis in WT mice, while the latter failed to be observed in AQP4-/- mice. Besides, higher levels of IL-1β and TNF-α were detected in the SVZ and peri-infarct cortex of AQP4-/- and Cx43± mice than those in WT mice. In conclusion, our data suggest that Cx43 elicits neuroprotective effects after cerebral ischemia through promoting neurogenesis in the SVZ to regenerate the injured neurons, which is AQP4 dependent and associated with down-regulation of inflammatory cytokines IL-1β and TNF-α.

rTMS treatment for abrogating intracerebral hemorrhage-induced brain parenchymal metabolite clearance dysfunction in male mice by regulating intracranial lymphatic drainage

BACKGROUND

The discovery of the glymphatic system and meningeal lymphatic vessels challenged the traditional view regarding the lack of a lymphatic system in the central nervous system. It is now known that the intracranial lymphatic system plays an important role in fluid transport, macromolecule uptake, and immune cell trafficking. Studies have also shown that the function of the intracranial lymphatic system is significantly associated with neurological diseases; for example, an impaired intracranial lymphatic system can lead to Tau deposition and an increased lymphocyte count in the brain tissue of mice with subarachnoid hemorrhage.

METHODS

In this study, we assessed the changes in the intracranial lymphatic system after intracerebral hemorrhage and the regulatory effects of repeated transcranial magnetic stimulation on the glymphatic system and meningeal lymphatic vessels in an intracerebral hemorrhage (ICH) model of male mice. Experimental mice were divided into three groups: Sham, ICH, and ICH + repeated transcranial magnetic stimulation (rTMS). Three days after ICH, mice in the ICH+rTMS group were subjected to rTMS daily for 7 days. Thereafter, the function of the intracranial lymphatic system, clearance of RITC-dextran and FITC-dextran, and neurological functions were evaluated.

RESULTS

Compared with the Sham group, the ICH group had an impaired glymphatic system. Importantly, rTMS treatment could improve intracranial lymphatic system function as well as behavioral functions and enhance the clearance of parenchymal RITC-dextran and FITC-dextran after ICH.

CONCLUSION

Our results indicate that rTMS can abrogate ICH-induced brain parenchymal metabolite clearance dysfunction by regulating intracranial lymphatic drainage.

Targeted drug delivery to the brain endothelium dominates over passive delivery via vascular leak in experimental intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is one of the most common causes of fatal stroke, yet has no specific drug therapies. Many attempts at passive intravenous (IV) delivery in ICH have failed to deliver drugs to the salvageable area around the hemorrhage. The passive delivery method assumes vascular leak through the ruptured blood-brain barrier will allow drug accumulation in the brain. Here we tested this assumption using intrastriatal injection of collagenase, a well-established experimental model of ICH. Fitting with hematoma expansion in clinical ICH, we showed that collagenase-induced blood leak drops significantly by 4 h after ICH onset and is gone by 24 h. We observed passive-leak brain accumulation also declines rapidly over ∼4 h for 3 model IV therapeutics (non-targeted IgG; a protein therapeutic; PEGylated nanoparticles). We compared these passive leak results with targeted brain delivery by IV monoclonal antibodies (mAbs) that actively bind vascular endothelium (anti-VCAM, anti-PECAM, anti-ICAM). Even at early time points after ICH induction, where there is high vascular leak, brain accumulation via passive leak is dwarfed by brain accumulation of endothelial-targeted agents: At 4 h after injury, anti-PECAM mAbs accumulate at 8-fold higher levels in the brain vs. non-immune IgG; anti-VCAM nanoparticles (NPs) deliver a protein therapeutic (superoxide dismutase, SOD) at 4.5-fold higher levels than the carrier-free therapeutic at 24 h after injury. These data suggest that relying on passive vascular leak provides inefficient delivery of therapeutics even at early time points after ICH, and that a better strategy might be targeted delivery to the brain endothelium, which serves as the gateway for the immune attack on the peri-hemorrhage inflamed brain region.

Aquaporin-4 in glymphatic system, and its implication for central nervous system disorders

The clearance function is essential for maintaining brain tissue homeostasis, and the glymphatic system is the main pathway for removing brain interstitial solutes. Aquaporin-4 (AQP4) is the most abundantly expressed aquaporin in the central nervous system (CNS) and is an integral component of the glymphatic system. In recent years, many studies have shown that AQP4 affects the morbidity and recovery process of CNS disorders through the glymphatic system, and AQP4 shows notable variability in CNS disorders and is part of the pathogenesis of these diseases. Therefore, there has been considerable interest in AQP4 as a potential and promising target for regulating and improving neurological impairment. This review aims to summarize the pathophysiological role that AQP4 plays in several CNS disorders by affecting the clearance function of the glymphatic system. The findings can contribute to a better understanding of the self-regulatory functions in CNS disorders that AQP4 were involved in and provide new therapeutic alternatives for incurable debilitating neurodegenerative disorders of CNS in the future.

Glymphatic Dysfunction Induced Oxidative Stress and Neuro-Inflammation in Major Depression Disorders

Major Depression disorder (MDD) is a potentially life-threatening mental illness, however, many patients have a poor response to current treatments. Recent studies have suggested that stress- or trauma-induced oxidative stress and inflammation could be important factors involved in the development of MDD, but the mechanisms remain unclear. We showed that the glymphatic system is a recently discovered structure in the brain that may be involved in the clearance of large molecular and cell debris in extracellular space. In addition, the glymphatic system can help with the removal of reactive oxygen species (ROS) and cytokines such as IL-1β and HIF-1α. Glymphatic impairment can lead to ROS accumulation in the microenvironment, inducing cellular injury signaling and activating NLRP3 in microglia to induce inflammation and, thus, many brain diseases, including psychiatric disorders. Therefore, trauma-induced glymphatic impairment could induce oxidative stress and inflammation, and thus MDD. This paper will review recent advances with regard to stress-induced glymphatic system impairment and ROS-mediated inflammation in MDD.

Molecular, Pathological, Clinical, and Therapeutic Aspects of Perihematomal Edema in Different Stages of Intracerebral Hemorrhage

Acute intracerebral hemorrhage (ICH) is a devastating type of stroke worldwide. Neuronal destruction involved in the brain damage process caused by ICH includes a primary injury formed by the mass effect of the hematoma and a secondary injury induced by the degradation products of a blood clot. Additionally, factors in the coagulation cascade and complement activation process also contribute to secondary brain injury by promoting the disruption of the blood-brain barrier and neuronal cell degeneration by enhancing the inflammatory response, oxidative stress, etc. Although treatment options for direct damage are limited, various strategies have been proposed to treat secondary injury post-ICH. Perihematomal edema (PHE) is a potential surrogate marker for secondary injury and may contribute to poor outcomes after ICH. Therefore, it is essential to investigate the underlying pathological mechanism, evolution, and potential therapeutic strategies to treat PHE. Here, we review the pathophysiology and imaging characteristics of PHE at different stages after acute ICH. As illustrated in preclinical and clinical studies, we discussed the merits and limitations of varying PHE quantification protocols, including absolute PHE volume, relative PHE volume, and extension distance calculated with images and other techniques. Importantly, this review summarizes the factors that affect PHE by focusing on traditional variables, the cerebral venous drainage system, and the brain lymphatic drainage system. Finally, to facilitate translational research, we analyze why the relationship between PHE and the functional outcome of ICH is currently controversial. We also emphasize promising therapeutic approaches that modulate multiple targets to alleviate PHE and promote neurologic recovery after acute ICH.

Perspectives on the mechanism of pyroptosis after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a highly harmful neurological disorder with high rates of mortality, disability, and recurrence. However, effective therapies are not currently available. Secondary immune injury and cell death are the leading causes of brain injury and a poor prognosis. Pyroptosis is a recently discovered form of programmed cell death that differs from apoptosis and necrosis and is mediated by gasdermin proteins. Pyroptosis is caused by multiple pathways that eventually form pores in the cell membrane, facilitating the release of inflammatory substances and causing the cell to rupture and die. Pyroptosis occurs in neurons, glial cells, and endothelial cells after ICH. Furthermore, pyroptosis causes cell death and releases inflammatory factors such as interleukin (IL)-1β and IL-18, leading to a secondary immune-inflammatory response and further brain damage. The NOD-like receptor protein 3 (NLRP3)/caspase-1/gasdermin D (GSDMD) pathway plays the most critical role in pyroptosis after ICH. Pyroptosis can be inhibited by directly targeting NLRP3 or its upstream molecules, or directly interfering with caspase-1 expression and GSDMD formation, thus significantly improving the prognosis of ICH. The present review discusses key pathological pathways and regulatory mechanisms of pyroptosis after ICH and suggests possible intervention strategies to mitigate pyroptosis and brain dysfunction after ICH.

The Role of ASIC1a in Inflammatory Immune Diseases: A Potential Therapeutic Target

It is acknowledged that chronic inflammation is associated with a rise in extracellular proton concentrations. The acid-sensing ion channel 1a (ASIC1a) belongs to the extracellular H⁺-activated cation channel family. Recently, many studies have been conducted on ASIC1a and inflammatory immune diseases. Here, in this review, we will focus on the role of ASIC1a in several inflammatory immune diseases so as to provide new perspectives for clinical treatment.

Aquaporin 4 Depolarization-Enhanced Transferrin Infiltration Leads to Neuronal Ferroptosis after Subarachnoid Hemorrhage in Mice

The infiltration of blood components into the brain parenchyma through the lymphoid system is an important cause of subarachnoid hemorrhage injury. AQP4, a water channel protein located at the astrocyte foot, has been reported to regulate blood-brain barrier integrity, and its polarization is disrupted after SAH. Neuronal ferroptosis is involved in subarachnoid hemorrhage- (SAH-) induced brain injury, but the inducing factors are not completely clear. Transferrin is one of the inducing factors of ferroptosis. This study is aimed at researching the role and mechanism of AQP4 in brain injury after subarachnoid hemorrhage in mice. An experimental mouse SAH model was established by endovascular perforation. An AAV vector encoding AQP4 with a GFAP-specific promoter was administered to mice to achieve specific overexpression of AQP4 in astrocytes. PI staining, Fer-1 intervention, and transmission electron microscopy were used to detect neuronal ferroptosis, and dextran (40 kD) leakage was used to detect BBB integrity. Western blot analysis of perfused brain tissue protein samples was used to detect transferrin infiltration. First, neuronal ferroptosis 24 h after SAH was observed by PI staining and Fer-1 intervention. Second, a significant increase in transferrin infiltration was found in the brain parenchyma 24 h after SAH modeling, while transferrin content was positively correlated with neuronal ferroptosis. Then, we observed that AQP4 overexpression effectively improved AQP depolarization and BBB injury induced by SAH and significantly reduced transferrin infiltration and neuronal ferroptosis after SAH. Finally, we found that AQP4 overexpression could effectively improve the neurobehavioral ability of SAH mice, and the neurobehavioral ability was negatively correlated with transferrin brain content. Taken together, these data indicate that overexpression of AQP4 in the mouse brain can effectively improve post-SAH neuronal ferroptosis and brain injury, at least partly by inhibiting transferrin infiltration into the brain parenchyma in the glymphatic system.