White matter repair and treatment strategy after intracerebral hemorrhage

Hypothermia protects the integrity of corticospinal tracts and alleviates mitochondria injury after intracerebral hemorrhage in mice

Disruption of corticospinal tracts (CST) is a leading factor for motor impairments following intracerebral hemorrhage (ICH) in the striatum. Previous studies have shown that therapeutic hypothermia (HT) improves outcomes of ICH patients. However, whether HT has a direct protection effect on the CST integrity and the underlying mechanisms remain largely unknown. In this study, we employed a chemogenetics approach to selectively activate bilateral warm-sensitive neurons in the preoptic areas to induce a hypothermia-like state. We then assessed effects of HT treatment on the integrity of CST and motor functional recovery after ICH. Our results showed that HT treatment significantly alleviated axonal degeneration around the hematoma and the CST axons at remote midbrain region, ultimately promoted skilled motor function recovery. Anterograde and retrograde tracing revealed that HT treatment protected the integrity of the CST over an extended period. Mechanistically, HT treatment prevented mitochondrial swelling in degenerated axons around the hematoma, alleviated mitochondrial impairment by reducing mitochondrial ROS accumulation and improving mitochondrial membrane potential in primarily cultured cortical neurons with oxyhemoglobin treatment. Serving as a proof of principle, our study provided novel insights into the application of HT to improve functional recovery after ICH.

Buyang huanwu decoction promotes remyelination via miR-760-3p/GPR17 axis after intracerebral hemorrhage

ETHNOPHARMACOLOGICAL RELEVANCE

The repairment of myelin sheaths is crucial for mitigating neurological impairments of intracerebral hemorrhage (ICH). However, the current research on remyelination processes in ICH remains limited. A representative traditional Chinese medicine, Buyang Huanwu decoction (BYHWD), shows a promising therapeutic strategy for ICH treatment.

AIM OF THE STUDY

To investigate the pro-remyelination effects of BYHWD on ICH and explore the underlying mechanisms.

MATERIALS AND METHODS

The collagenase-induced mice ICH model was created for investigation. BYHWD's protective effects were assessed by behavioral tests and histological staining. Transmission electron microscopy was used for displaying the structure of myelin sheaths. The remyelination and oligodendrocyte differentiation were evaluated by the expressions of myelin proteolipid protein (PLP), myelin basic protein (MBP), MBP/TAU, Olig2/CC1, and PDGFRα/proliferating cell nuclear antigen (PCNA) through RT-qPCR and immunofluorescence. Transcriptomics integrated with disease database analysis and experiments in vivo and in vitro revealed the microRNA-related underlying mechanisms.

RESULTS

Here, we reported that BYHWD promoted the neurological function of ICH mice and improved remyelination by increasing PLP, MBP, and TAU, as well as restoring myelin structure. Besides, we showed that BYHWD promoted remyelination by boosting the differentiation of PDGFRα+ oligodendrocyte precursor cells into olig2+/CC1+ oligodendrocytes. Additionally, we demonstrated that the remyelination effects of BYHWD worked by inhibiting G protein-coupled receptor 17 (GPR17). miRNA sequencing integrated with miRNA database prediction screened potential miRNAs targeting GPR17. By applying immunofluorescence, RNA in situ hybridization and dual luciferase reporter gene assay, we confirmed that BYHWD suppressed GPR17 and improved remyelination by increasing miR-760-3p.

CONCLUSIONS

BYHWD improves remyelination and neurological function in ICH mice by targeting miR-760-3p to inhibit GPR17. This study may shed light on the orchestration of remyelination mechanisms after ICH, thus providing novel insights for developing innovative prescriptions with brain-protective properties.

Rasd1 is involved in white matter injury through neuron-oligodendrocyte communication after subarachnoid hemorrhage

AIMS

Rasd1 has been reported to be correlated with neurotoxicity, metabolism, and rhythm, but its effect in case of subarachnoid hemorrhage (SAH) remained unclear. White matter injury (WMI) and ferroptosis participate in the early brain injury (EBI) after SAH. In this work, we have investigated whether Rasd1 can cause ferroptosis and contribute to SAH-induced WMI.

METHODS

Lentivirus for Rasd1 knockdown/overexpression was administrated by intracerebroventricular (i.c.v) injection at 7 days before SAH induction. SAH grade, brain water content, short- and long-term neurobehavior, Western blot, real-time PCR, ELISA, biochemical estimation, immunofluorescence, diffusion tensor imaging (DTI), and transmission electron microscopy (TEM) were systematically performed. Additionally, genipin, a selective uncoupling protein 2(UCP2) inhibitor, was used in primary neuron and oligodendrocyte co-cultures for further in vitro mechanistic studies.

RESULTS

Rasd1 knockdown has improved the neurobehavior, glia polarization, oxidative stress, neuroinflammation, ferroptosis, and demyelination. Conversely, Rasd1 overexpression aggravated these changes by elevating the levels of reactive oxygen species (ROS), inflammatory cytokines, MDA, free iron, and NCOA4, as well as contributing to the decrease of the levels of UCP2, GPX4, ferritin, and GSH mechanistically. According to the in vitro study, Rasd1 can induce oligodendrocyte ferroptosis through inhibiting UCP2, increasing reactive oxygen species (ROS), and activating NCOA4-mediated ferritinophagy.

CONCLUSIONS

It can be concluded that Rasd1 exerts a modulated role in oligodendrocytes ferroptosis in WMI following SAH.

Unraveling the complex pathophysiology of white matter hemorrhage in intracerebral stroke: A single-cell RNA sequencing approach

AIM

This study aims to elucidate the cellular dynamics and pathophysiology of white matter hemorrhage (WMH) in intracerebral hemorrhage (ICH).

METHODS

Using varying doses of collagenase IV, a consistent rat ICH model characterized by pronounced WMH was established. Verification was achieved through behavioral assays, hematoma volume, and histological evaluations. Single-cell suspensions from the hemorrhaged region of the ipsilateral striatum on day three post-ICH were profiled using single-cell RNA sequencing (scRNA-seq). Gene Ontology (GO) and gene set variation analysis (GSVA) further interpreted the differentially expressed genes (DEGs).

RESULTS

Following WMH induction, there was a notable increase in the percentage of myeloid cells and oligodendrocyte precursor cells (OPCs), alongside a reduction in the percentage of neurons, microglia, and oligodendrocytes (OLGs). Post-ICH WMH showed homeostatic microglia transitioning into pro-, anti-inflammatory, and proliferative states, influencing lipid metabolic pathways. Myeloid cells amplified chemokine expression, linked with ferroptosis pathways. Macrophages exhibited M1 and M2 phenotypes, and post-WMH, macrophages displayed a predominance of M2 phenotypes, characterized by their anti-inflammatory properties. A surge in OPC proliferation aligned with enhanced ribosomal signaling, suggesting potential reparative responses post-WMH.

CONCLUSION

The study offers valuable insights into WMH's complex pathophysiology following ICH, highlighting the significance and utility of scRNA-seq in understanding the cellular dynamics and contributing to future cerebrovascular research.

Targeting Ferroptosis Promotes Functional Recovery by Mitigating White Matter Injury Following Acute Carbon Monoxide Poisoning

Survivors experiencing acute carbon monoxide poisoning (ACMP) tend to develop white matter injury (WMI). The mechanism of ACMP-induced WMI remains unclear. Considering the role of ferroptosis in initiating oligodendrocyte damage to deteriorate WMI, exploring therapeutic options to attenuate ferroptosis is a feasible approach to alleviating WMI. Our results indicated that ACMP induced accumulation of iron and reactive oxygen species (ROS) eventually leading to WMI and motor impairment after ACMP. Furthermore, ferrostatin-1 reduced iron and ROS deposition to alleviate ferroptosis, thereafter reducing WMI to promote the recovery of motor function. The nuclear factor erythroid-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway was found to be involved in alleviating ferroptosis as seen with the administration of ferrostatin-1. The present study rationalizes that targeting ferroptosis to alleviate WMI is a feasible therapeutic strategy for managing ACMP.

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.

Genetic analyses identify brain imaging-derived phenotypes associated with the risk of intracerebral hemorrhage

Previous observational studies have reported associations between brain imaging-derived phenotypes (IDPs) and intracerebral hemorrhage (ICH), but the causality between them remains uncertain. We aimed to investigate the potential causal relationship between IDPs and ICH by a two-sample Mendelian randomization (MR) study. We selected genetic instruments for 363 IDPs from a genome-wide association study (GWASs) based on the UK Biobank (n = 33,224). Summary-level data on ICH was derived from a European-descent GWAS with 1,545 cases and 1,481 controls. Inverse variance weighted MR method was applied in the main analysis to investigate the associations between IDPs and ICH. Reverse MR analyses were performed for significant IDPs to examine the reverse causation for the identified associations. Among the 363 IDPs, isotropic or free water volume fraction (ISOVF) in the anterior limb of the left internal capsule was identified to be associated with the risk of ICH (OR per 1-SD increase, 4.62 [95% CI, 2.18-9.81], P = 6.63 × 10-5). In addition, the reverse MR analysis indicated that ICH had no effect on ISOVF in the anterior limb of the left internal capsule (beta, 0.010 [95% CI, -0.010-0.030], P = 0.33). MR-Egger regression analysis showed no directional pleiotropy for the association between ISOVF and ICH, and sensitivity analyses with different MR models further confirmed these findings. ISOVF in the anterior limb of the left internal capsule might be a potential causal mediator of ICH, which may provide predictive guidance for the prevention of ICH. Further studies are warranted to replicate our findings and clarify the underlying mechanisms.

The Crosstalk Between Immune Cells After Intracerebral Hemorrhage

The inflammatory mechanism of intracerebral hemorrhage (ICH) has been widely studied, and it is believed that the regulation of this mechanism is of great significance to the prognosis. In the early stage of the acute phase of ICH, the release of a large number of inflammatory factors around the hematoma can recruit more inflammatory cells to infiltrate the area, further release inflammatory factors, cause an inflammatory cascade reaction, aggravate the volume of cerebral hematoma and edema and further destroy the blood-brain barrier (BBB), according to this, the crosstalk between cells may be of great significance in secondary brain injury (SBI). Because most of the cells recruited are inflammatory immune cells, this paper mainly discusses the cells based on the inflammatory mechanism to discuss their functions after ICH, we found that among the main cells inherent in the brain, glial cells account for the majority, of which microglia are the most widely studied and it can interact with a variety of cells, which is reflected in the literature researches on its pathogenesis and treatment. We believe that exploring multi-mechanism and multi-cell regulated drugs may be the future development trend, and the existing research, the comparison and unification of modeling methods, and the observation of long-term efficacy may be the first problem that researchers need to solve.

The Role of ICP Monitoring in Minimally Invasive Surgery for the Management of Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the second major stroke type, with high incidence, high disability rate, and high mortality. At present, there is no effective and reliable treatment for ICH. As a result, most patients have a poor prognosis. Minimally invasive surgery (MIS) is the fastest treatment method to remove hematoma, which is characterized by less trauma and easy operation. Some studies have confirmed the safety of MIS, but there are still no reports showing that it can significantly improve the functional outcome of ICH patients. Intracranial pressure (ICP) monitoring is considered to be an important part of successful treatment in traumatic brain diseases. By monitoring ICP in real time, keeping stable ICP could help patients with craniocerebral injury get a good prognosis. In the course of MIS treatment of ICH patients, keeping ICP stable may also promote patient recovery. In this review, we will take ICP monitoring as the starting point for an in-depth discussion.

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.

Intracerebral Hemorrhage Models and Behavioral Tests in Rodents

Intracerebral hemorrhage (ICH) is one of the common types of stroke, which can cause neurological dysfunction. In preclinical ICH studies, researchers often established rodent models by donor/autologous whole blood or a collagenase injection. White matter injury (WMI) can result from primary and secondary injuries after ICH. WMI can lead to short- and long-term neurological impairment, and functional recovery can assess the effect of drug therapy after ICH. Therefore, researchers have devised various behavioral tests to assess dysfunction. This review compares the two ICH modeling methods in rodents and summarizes the pathological mechanisms underlying dysfunction after ICH. We also summarize the functions and characteristics of various behavioral methods, including sensation, motion, emotion, and cognition, to assist researchers in selecting the appropriate tests for preclinical ICH research.

Secondary White Matter Injury Mediated by Neuroinflammation after Intracerebral Hemorrhage and Promising Therapeutic Strategies of Targeting the NLRP3 Inflammasome

Intracerebral hemorrhage (ICH) is a neurological disease with high mortality and disability. Recent studies showed that white matter injury (WMI) plays an important role in motor dysfunction after ICH. WMI includes WMI proximal to the lesion and WMI distal to the lesion, such as corticospinal tract injury located at the cervical enlargement of the spinal cord after ICH. Previous studies have tended to focus only on gray matter (GM) injury after ICH, and fewer studies have paid attention to WMI, which may be one of the reasons for the poor outcome of previous drug treatments. Microglia and astrocyte-mediated neuroinflammation are significant mechanisms responsible for secondary WMI following ICH. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation, has been shown to exacerbate neuroinflammation and brain injury after ICH. Moreover, NLRP3 inflammasome is activated in microglia and astrocytes and exerts a vital role in microglia and astrocytes-mediated neuroinflammation. We speculate that NLRP3 inflammasome activation is closely related to the polarization of microglia and astrocytes and that NLRP3 inflammasome activation may exacerbate WMI by polarizing microglia and astrocytes to the pro-inflammatory phenotype after ICH, while NLRP3 inflammasome inhibition may attenuate WMI by polarizing microglia and astrocytes to the anti-inflammatory phenotype following ICH. Therefore, NLRP3 inflammasome may act as leveraged regulatory fulcrums for microglia and astrocytes polarization to modulate WMI and WM repair after ICH. This review summarized the possible mechanisms by which neuroinflammation mediated by NLRP3 inflammasome exacerbates secondary WMI after ICH and discussed the potential therapeutic targets.

Cyclophilin D-induced mitochondrial impairment confers axonal injury after intracerebral hemorrhage in mice

The mitochondrial permeability transition pore is a nonspecific transmembrane channel. Inhibition of mitochondrial permeability transition pore opening has been shown to alleviate mitochondrial swelling, calcium overload, and axonal degeneration. Cyclophilin D is an important component of the mitochondrial permeability transition pore. Whether cyclophilin D participates in mitochondrial impairment and axonal injury after intracerebral hemorrhage is not clear. In this study, we established mouse models of intracerebral hemorrhage in vivo by injection of autologous blood and oxyhemoglobin into the striatum in Thy1-YFP mice, in which pyramidal neurons and axons express yellow fluorescent protein. We also simulated intracerebral hemorrhage in vitro in PC12 cells using oxyhemoglobin. We found that axonal degeneration in the early stage of intracerebral hemorrhage depended on mitochondrial swelling induced by cyclophilin D activation and mitochondrial permeability transition pore opening. We further investigated the mechanism underlying the role of cyclophilin D in mouse models and PC12 cell models of intracerebral hemorrhage. We found that both cyclosporin A inhibition and short hairpin RNA interference of cyclophilin D reduced mitochondrial permeability transition pore opening and mitochondrial injury. In addition, inhibition of cyclophilin D and mitochondrial permeability transition pore opening protected corticospinal tract integrity and alleviated motor dysfunction caused by intracerebral hemorrhage. Our findings suggest that cyclophilin D is used as a key mediator of axonal degeneration after intracerebral hemorrhage; inhibition of cyclophilin D expression can protect mitochondrial structure and function and further alleviate corticospinal tract injury and motor dysfunction after intracerebral hemorrhage. Our findings provide a therapeutic target for preventing axonal degeneration of white matter injury and subsequent functional impairment in central nervous diseases.

Long-term outcome of cerebral amyloid angiopathy-related hemorrhage

Object

The long‐term functional outcome of cerebral amyloid angiopathy‐related hemorrhage (CAAH) patients is unclear. We sought to assess the long‐term functional outcome of CAAH and determine the prognostic factors associated with unfavorable outcomes.

Methods

We enrolled consecutive CAAH patients from 2014 to 2020 in this observational study. Baseline characteristics and clinical outcomes were presented. Multivariable logistic regression analysis was performed to identify the prognostic factors associated with long‐term outcome.

Results

Among the 141 CAAH patients, 76 (53.9%) achieved favorable outcomes and 28 (19.9%) of them died at 1‐year follow‐up. For the longer‐term follow‐up with a median observation time of 19.0 (interquartile range, 12.0–26.5) months, 71 (50.4%) patients obtained favorable outcomes while 33 (23.4%) died. GCS on admission (OR, 0.109; 95% CI, 0.021–0.556; p = 0.008), recurrence of ICH (OR, 2923.687; 95% CI, 6.282–1360730.14; p = 0.011), WML grade 3–4 (OR, 31.007; 95% CI, 1.041–923.573; p = 0.047), severe central atrophy (OR, 4220.303; 95% CI, 9.135–1949674.84; p = 0.008) assessed by CT was identified as independent predictors for long‐term outcome.

Interpretation

Nearly 50% of CAAH patients achieved favorable outcomes at long‐term follow‐up. GCS, recurrence of ICH, WML grade and cerebral atrophy were identified as independent prognostic factors of long‐term outcome.

Dexpramipexole Attenuates White Matter Injury to Facilitate Locomotion and Motor Coordination Recovery via Reducing Ferroptosis after Intracerebral Hemorrhage

Deciphering the factors causing damage to white matter fiber bundles and exploring new strategies to alleviate white matter injury (WMI) is a promising treatment to improve neurological impairments after intracerebral hemorrhage (ICH). Ferroptosis usually occurs at perihematomal region and contributes to neuronal death due to reactive oxygen species (ROS) production. Dexpramipexole (DPX) easily crosses the blood brain barrier (BBB) and exerts antioxidative properties by reducing ROS production, while the role of DPX in ferroptosis after ICH remains elusive. Here, our results indicated that ferroptosis played a significant role in WMI resulting from iron and ROS accumulation around hematoma. Further evidence demonstrated that the administration of DPX decreased iron and ROS deposition to inhibit ferroptosis at perihematomal site. With the inhibition of ferroptosis, WMI was alleviated at perihematomal site, thereafter promoting locomotion and motor coordination recovery in mice after ICH. Subsequently, the results showcased that the expression of glutathione peroxidase 4 (GPX4) and ferroptosis suppressing protein 1 (FSP1) was upregulated with the administration of DPX. Collectively, the present study uncovers the underlying mechanism and elucidates the therapeutic effect of DPX on ICH, and even in other central nervous system (CNS) diseases with the presence of ferroptosis.

Lithium attenuates blood-brain barrier damage and brain edema following intracerebral hemorrhage via an endothelial Wnt/β-catenin signaling-dependent mechanism in mice

Background

Vasogenic cerebral edema resulting from blood–brain barrier (BBB) damage aggravates the devastating consequences of intracerebral hemorrhage (ICH). Although augmentation of endothelial Wnt/β‐catenin signaling substantially alleviates BBB breakdown in animals, no agents based on this mechanism are clinically available. Lithium is a medication used to treat bipolar mood disorders and can upregulate Wnt/β‐catenin signaling.

Methods

We evaluated the protective effect of lithium on the BBB in a mouse model of collagenase IV‐induced ICH. Furthermore, we assessed the effect and dependency of lithium on Wnt/β‐catenin signaling in mice with endothelial deletion of the Wnt7 coactivator Gpr124.

Results

Lithium treatment (3 mmol/kg) significantly decreased the hematoma volume (11.15 ± 3.89 mm³ vs. 19.97 ± 3.20 mm³ in vehicle controls, p = 0.0016) and improved the neurological outcomes of mice following ICH. Importantly, lithium significantly increased the BBB integrity, as evidenced by reductions in the levels of brain edema (p = 0.0312), Evans blue leakage (p = 0.0261), and blood IgG extravasation (p = 0.0009) into brain tissue around the hematoma. Mechanistically, lithium upregulated the activity of endothelial Wnt/β‐catenin signaling in mice and increased the levels of tight junction proteins (occludin, claudin‐5 and ZO‐1). Furthermore, the protective effect of lithium on cerebral damage and BBB integrity was abolished in endothelial Gpr124 knockout mice, suggesting that its protective effect on BBB function was mainly dependent on Gpr124‐mediated endothelial Wnt/β‐catenin signaling.

Conclusion

Our findings indicate that lithium may serve as a therapeutic candidate for treating BBB breakdown and brain edema following ICH.

Targeting NLRP3 inflammasome modulates gut microbiota, attenuates corticospinal tract injury and ameliorates neurobehavioral deficits after intracerebral hemorrhage in mice

Intracerebral hemorrhage (ICH) has a high mortality and disability rate. Fewer studies focus on white matter injury (WMI) after ICH, especially the corticospinal tract (CST) injury located in the spinal cord, which correlates with motor impairments. Recent studies have shown that gut microbiota dysbiosis occurs after ICH. Furthermore, NLRP3 inflammasome can be activated after ICH, resulting in inflammatory cascade reactions and aggravating brain injury. However, no direct and causal correlation among NLRP3 inflammasome inhibition, altered gut microbiota, and CST injury following ICH has been reported. This study aimed to investigate the effect of MCC950, a selective NLRP3 inflammasome inhibitor, on the gut microbiota and CST injury after ICH. We observed that compared with the sham group, the members of Firmicutes, such as Faecalibaculum and Dubosiella, were depleted in the ICH + Vehicle group, whereas the members of Proteobacteria and Campilobacterota were enriched, such as Enterobacter and Helicobacter. After treatment with MCC950, the Bacteroides, Bifidobacterium and Paenibacillus were relatively abundant in the gut flora of mice. Moreover, we observed CST injury located in cervical enlargement of the spinal cord, and MCC950 alleviated it. Furthermore, treatment with MCC950 decreased the mNSS score and brain water content in ICH. Taken together, the present study showed that MCC950 modulated gut microbiota, effectively attenuated CST injury located in cervical enlargement of the spinal cord, and ameliorated neurological deficits after ICH. This study provided a novel report that links NLRP3 inflammasome inhibition, gut microbiota alteration and CST injury following ICH and profound implications for ICH treatment.

Targeting the multifaceted roles of mitochondria in intracerebral hemorrhage and therapeutic prospects

Intracerebral hemorrhage (ICH) is a severe, life-threatening subtype of stoke that constitutes a crucial health and socioeconomic problem worldwide. However, the current clinical treatment can only reduce the mortality of patients to a certain extent, but cannot ameliorate neurological dysfunction and has a high recurrence rate. Increasing evidence has demonstrated that mitochondrial dysfunction occurs in the early stages of brain injury and participates in all stages of secondary brain injury (SBI) after ICH. As the energy source of cells, various pathobiological processes that lead to SBI closely interact with the mitochondria, such as oxidative stress, calcium overload, and neuronal injury. In this review, we discussed the structure and function of mitochondria and the abnormal morphological changes after ICH. In addition, we discussed recent research on the involvement of mitochondrial dynamics in the pathological process of SBI after ICH and introduced the pathological variations and related molecular mechanisms of mitochondrial dysfunction in the occurrence of brain injury. Finally, we summarized the latest progress in mitochondrion-targeted agents for ICH, which provides a direction for the development of emerging therapeutic strategies targeting the mitochondria after ICH.

Ferroptosis in oligodendrocyte progenitor cells mediates white matter injury after hemorrhagic stroke

Oligodendrocyte progenitor cells (OPCs) differentiate to myelin-producing mature oligodendrocytes and enwrap growing or demyelinated axons during development and post central nervous diseases. Failure of remyelination owing to cell death or undifferentiation of OPCs contributes to severe neurologic deficits and motor dysfunction. However, how to prevent the cell death of OPCs is still poorly understood, especially in hemorrhagic diseases. In the current study, we injected autologous blood into the mouse lateral ventricular to study the hemorrhage-induced OPC cell death in vivo. The integrity of the myelin sheath of the corpus callosum was disrupted post intraventricular hemorrhage (IVH) assessed by using magnetic resonance imaging, immunostaining, and transmission electron microscopy. Consistent with the severe demethylation, we observed massive cell death of oligodendrocyte lineages in the periventricular area. In addition, we found that ferroptosis is the major cell death form in Hemin-induced OPC death by using RNA-seq analysis, and the mechanism was glutathione peroxidase 4 activity reduction-resulted lipid peroxide accumulation. Furthermore, inhibition of ferroptosis rescued OPC cell death in vitro, and in vivo attenuated IVH-induced white matter injury and promoted recovery of neurological function. These data demonstrate that ferroptosis is an essential form of OPC cell death in hemorrhagic stroke, and rescuing ferroptotic OPCs could serve as a therapeutic target for stroke and related diseases.

Identification of novel biomarkers for intracerebral hemorrhage via long noncoding RNA-associated competing endogenous RNA network

Intracerebral hemorrhage (ICH) is a leading cause of death and disability worldwide. This study aimed to examine the involvement of long non-coding RNAs (lncRNAs), a group of non-coding transcripts, in ICH as potential biomarkers. An expression profile of patients with ICH using four contralateral grey matter controls (GM) and four contralateral white matter controls (WM) was downloaded from the Gene Expression Omnibus (GEO) database. Co-expressed lncRNAs and mRNAs were selected to create competing endogenous RNA (ceRNA) networks. Key lncRNAs were identified in ceRNA networks, which were validated through Real-time qPCR (RT-qPCR) with peripheral blood samples from patients with ICH. A total of 49 differentially expressed lncRNAs were discovered in different brain regions. The ceRNA network in GM included 9 lncRNAs, 40 mRNAs, and 20 microRNAs (miRNAs), while the one in WM covered 6 lncRNAs, 25 mRNAs, and 14 miRNAs. Six hub lncRNAs were observed and RT-qPCR results showed that LY86-AS1, DLX6-AS1, RRN3P2, and CRNDE were down-regulated, while HCP5 and MIAT were up-regulated in patients with ICH. Receiver Operating Characteristic (ROC) assessments demonstrated the diagnostic value of these lncRNAs. Our findings highlight the potential roles of lncRNA in ICH pathogenesis. Moreover, the hub lncRNAs discovered here might become novel biomarkers and promising targets for ICH drug development.

Inhibition of P2X4R attenuates white matter injury in mice after intracerebral hemorrhage by regulating microglial phenotypes

Background

White matter injury (WMI) is a major neuropathological event associated with intracerebral hemorrhage (ICH). P2X purinoreceptor 4 (P2X4R) is a member of the P2X purine receptor family, which plays a crucial role in regulating WMI and neuroinflammation in central nervous system (CNS) diseases. Our study investigated the role of P2X4R in the WMI and the inflammatory response in mice, as well as the possible mechanism of action after ICH.

Methods

ICH was induced in mice via collagenase injection. Mice were treated with 5-BDBD and ANA-12 to inhibit P2X4R and tropomyosin-related kinase receptor B (TrkB), respectively. Immunostaining and quantitative polymerase chain reaction (qPCR) were performed to detect microglial phenotypes after the inhibition of P2X4R. Western blots (WB) and immunostaining were used to examine WMI and the underlying molecular mechanisms. Cylinder, corner turn, wire hanging, and forelimb placement tests were conducted to evaluate neurobehavioral function.

Results

After ICH, the protein levels of P2X4R were upregulated, especially on day 7 after ICH, and were mainly located in the microglia. The inhibition of P2X4R via 5-BDBD promoted neurofunctional recovery after ICH as well as the transformation of the pro-inflammatory microglia induced by ICH into an anti-inflammatory phenotype, and attenuated ICH-induced WMI. Furthermore, we found that TrkB blockage can reverse the protective effects of WMI as well as neuroprotection after 5-BDBD treatment. This result indicates that P2X4R plays a crucial role in regulating WMI and neuroinflammation and that P2X4R inhibition may benefit patients with ICH.

Conclusions

Our results demonstrated that P2X4R contributes to WMI by polarizing microglia into a pro-inflammatory phenotype after ICH. Furthermore, the inhibition of P2X4R promoted pro-inflammatory microglia polarization into an anti-inflammatory phenotype, enhanced brain-derived neurotrophic factor (BDNF) production, and through the BDNF/TrkB pathway, attenuated WMI and improved neurological function. Therefore, the regulation of P2X4R activation may be beneficial for the reducing of ICH-induced brain injury.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02239-3.

MEC17-induced α-tubulin acetylation restores mitochondrial transport function and alleviates axonal injury after intracerebral hemorrhage in mice

Injury to long axonal projections is a central pathological feature at the early phase of intracerebral hemorrhage (ICH). It has been reported to contribute to persistent functional disability following ICH. However, the molecular mechanisms that drive axonal degeneration remain unclear. Autologous blood was injected into the striatum to mimic the pathology of ICH. Observed significant swollen axons with characteristic retraction bulbs were found around the striatal hematoma at 24 h after ICH. Electronic microscopic examination revealed highly disorganized microtubule and swollen mitochondria in the retraction bulbs. MEC17 is a specific α-tubulin acetyltransferase, ablation of acetylated α-tubulin in MEC17^-/- mice aggravated axonal injury, axonal transport mitochondria dysfunction, and motor dysfunction. In contrast, treatment with tubastatin A (TubA), which promotes microtubule acetylation, significantly alleviated axonal injury and protected the integrity of the corticospinal tract and fine motor function after ICH. Moreover, results showed that 41% mitochondria were preferentially bundled to the acetylated α-tubulin in identifiable axons and dendrites in primary neurons. This impaired axonal transport of mitochondria in primary neurons of MEC17^-/- mice. Given that opening of mitochondrial permeability transition pore (mPTP) induces mitochondrial dysfunction and impairs ATP supply thereby promoting axonal injury, we enhanced the availability of acetylated α-tubulin using TubA and inhibited mPTP opening with cyclosporin A. The results indicated that this combined treatment synergistically protected corticospinal tract integrity and promoted fine motor control recovery. These findings reveal key intracellular mechanisms that drive axonal degeneration after ICH and highlight the need to target multiple factors and respective regulatory mechanisms as an effective approach to prevent axonal degeneration and motor dysfunction after ICH.

White Matter Injury After Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) accounts for 15% of all stroke cases. ICH is a devastating form of stroke associated with high morbidity, mortality, and disability. Preclinical studies have explored the mechanisms of neuronal death and gray matter damage after ICH. However, few studies have examined the development of white matter injury (WMI) following ICH. Research on WMI indicates that its pathophysiological presentation involves axonal damage, demyelination, and mature oligodendrocyte loss. However, the detailed relationship and mechanism between WMI and ICH remain unclear. Studies of other acute brain insults have indicated that WMI is strongly correlated with cognitive deficits, neurological deficits, and depression. The degree of WMI determines the short- and long-term prognosis of patients with ICH. This review demonstrates the structure and functions of the white matter in the healthy brain and discusses the pathophysiological mechanism of WMI following ICH. Our review reveals that the development of WMI after ICH is complex; therefore, comprehensive treatment is essential. Understanding the relationship between WMI and other brain cells may reveal therapeutic targets for the treatment of ICH.

A new surgical method of treatment spontaneous intracranial hemorrhage

Objective

This study aimed to determine the safety and effectiveness of DTI-assisted neuroendoscopy for treating intracranial hemorrhage (ICH).

Methods

This retrospective study included clinical data from 260 patients with spontaneous supratentorial ICH who received neuroendoscopic hematoma removal. Patients were separated into groups based on the surgery method they received: DTI-assisted neuroendoscopy (69 cases) and standard neuroendoscopy (191 cases). All patients were followed up for 6 months. Multivariate logistic regression analyzed the risk factors affecting the prognosis of patients. The outcomes of the two groups were compared using Kaplan-Meier survival curves.

Results

The prognostic modified Rankin Scale (mRS) score was significantly better (P = 0.027) in the DTI-assisted neuroendoscopy group than in the standard neuroendoscopy group. Logistic regression analysis showed that DTI-assisted neuroendoscopy is an independent protective factor for a favorable outcome (model 1: odds ratio [OR] = 0.42, P = 0.015; model 2: OR = 0.40, P = 0.013). Kaplan-Meier survival curves were used to show that the median time for a favorable outcome was 66 days (95% confidence interval [CI] = 48.50-83.50 days) in the DTI-assisted neuroendoscopy group and 104 days (95% CI = 75.55-132.45 days) in the standard neuroendoscopy group. Log-rank testing showed that the DTI-assisted neuroendoscopy group had a lower pulmonary infection rate (χ ² = 4.706, P = 0.030) and a better prognosis (χ ² = 5.223, P = 0.022) than the standard neuroendoscopy group. The survival rate did not differ significantly between the DTI-assisted neuroendoscopy group and the standard neuroendoscopy group (P > 0.05).

Conclusions

The use of DTI in neuroendoscopic hematoma removal can significantly improve neurological function outcomes in patients, but it does not significantly affect the mortality of patients.

Ceria nanoparticles ameliorate white matter injury after intracerebral hemorrhage: microglia-astrocyte involvement in remyelination

Background

Intracerebral hemorrhage (ICH) can induce excessive accumulation of reactive oxygen species (ROS) that may subsequently cause severe white matter injury. The process of oligodendrocyte progenitor cell (OPC) differentiation is orchestrated by microglia and astrocytes, and ROS also drives the activation of microglia and astrocytes. In light of the potent ROS scavenging capacity of ceria nanoparticles (CeNP), we aimed to investigate whether treatment with CeNP ameliorates white matter injury by modulating ROS-induced microglial polarization and astrocyte alteration.

Methods

ICH was induced in vivo by collagenase VII injection. Mice were administered with PLX3397 for depleting microglia. Primary microglia and astrocytes were used for in vitro experiments. Transmission electron microscopy analysis and immunostaining were performed to verify the positive effects of CeNP in remyelination and OPC differentiation. Flow cytometry, real-time polymerase chain reaction, immunofluorescence and western blotting were used to detect microglia polarization, astrocyte alteration, and the underlying molecular mechanisms.

Results

CeNP treatment strongly inhibited ROS-induced NF-κB p65 translocation in both microglia and astrocytes, and significantly decreased the expression of M1 microglia and A1 astrocyte. Furthermore, we found that CeNP treatment promoted remyelination and OPC differentiation after ICH, and such effects were alleviated after microglial depletion. Interestingly, we also found that the number of mature oligodendrocytes was moderately increased in ICH + CeNP + PLX3397-treated mice compared to the ICH + vehicle + PLX3397 group. Therefore, astrocytes might participate in the pathophysiological process. The subsequent phagocytosis assay indicated that A1 astrocyte highly expressed C3, which could bind with microglia C3aR and hinder microglial engulfment of myelin debris. This result further replenished the feedback mechanism from astrocytes to microglia.

Conclusion

The present study reveals a new mechanism in white matter injury after ICH: ICH induces M1 microglia and A1 astrocyte through ROS-induced NF-κB p65 translocation that hinders OPC maturation. Subsequently, A1 astrocytes inhibit microglial phagocytosis of myelin debris via an astrocytic C3-microglial C3aR axis. Polyethylene glycol-CeNP treatment inhibits this pathological process and ultimately promotes remyelination. Such findings enlighten us that astrocytes and microglia should be regarded as a functional unit in future works.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02101-6.

Usage of Angiotensin-Converting Enzyme Inhibitor or Angiotensin II Receptor Blocker in Hypertension Intracerebral Hemorrhage

BACKGROUND

Inflammation plays an essential role in secondary brain injury after intracerebral hemorrhage (ICH). Angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin II receptor blockers (ARBs) have been suggested to suppress neuroinflammation after central nervous system (CNS) damage in animal models. However, the role of ACEIs and ARBs in ICH patients with hypertension remains unresolved in clinic. The aim of the present study is to evaluate the effect of ACEIs/ARBs on ICH patients with hypertension using a retrospective, single-center data analysis.

METHODS

ICH patients diagnosed by computerized tomographic (CT) at Southwest Hospital, Third Military Medical University were included in the present research from January 2015 to December 2019. According to the medical history for the usage of antihypertensive drugs, patients were assigned into either ACEIs/ARBs group or non-ACEIs/ARBs group. Demographics, clinical baseline, radiological documents and treatments were collected and these data were statistically analyzed between the two groups.

RESULTS

A total of 635 ICH patients with hypertension were included and allocated into 2 groups according to the usage of antihypertensive drugs: 281 in the ACEIs/ARBs group and 354 in the non-ACEIs/ARBs group. The results presented that the 3-months mortality and prevalence of ICH-associated pneumonia were lower in ACEIs/ARBs group than that in non-ACEIs/ARBs group (5.0% vs 11.9%, p=0.002; 58.4% vs 66.7%, p=0.031). While, there was no significant difference in favorable outcome (40.2% vs 33.9%, p=0.101) between the two groups. Furthermore, patients in ACEIs/ARBs group exhibited significantly less perihematomal edema volume on days 3 (23.5 ± 14.4 versus 28.7 ± 20.1 mL, p=0.045) and 7 (21.0 ± 13.7 versus 25.7 ± 17.6 mL, p=0.044), compared to that in non- ACEIs/ARBs group.

CONCLUSION

The usage of ACEIs/ARBs helps decrease mortality, perihematomal edema volume, and prevalence of ICH-associated pneumonia in ICH patients with hypertension.

Intra-hematomal White Matter Tracts Act As a Scaffold for Macrophage Infiltration After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a stroke subtype with high mortality and severe morbidity. Hemorrhages frequently develop within the white matter, but whether white matter fibers within the hematoma survive after ICH has not been well studied. The current study examines whether white matter fibers persist in the hematoma after ICH, fibers that might be impacted by evacuation, and their relationship to macrophage infiltration in a porcine model. Male piglets had 2.5 ml blood with or without CD47 blocking antibody injected into the right frontal lobe. Brains were harvested from 3 days to 2 months after ICH for brain histology. White matter fibers were detected within the hematoma 3 and 7 days after hemorrhage by brain histology and myelin basic protein immunohistochemistry. White matter still remained in the hematoma cavity at 2 months after ICH. Macrophage scavenger receptor-1 positive macrophages/microglia and heme oxygenase-1 positive cells infiltrated into the hematoma along the intra-hematomal white matter fibers at 3 and 7 days after ICH. Treatment with CD47 blocking antibody enhanced the infiltration of these cells. In conclusion, white matter fibers exist within the hematoma after ICH and macrophages/microglia may use such fibers as a scaffold to infiltrate into the hematoma and aid in hematoma clearance.

White matter repair and treatment strategy after intracerebral hemorrhage

The predilection site of intracerebral hemorrhage (ICH) is in the basal ganglia, which is rich in white matter (WM) fiber bundles, such as cerebrospinal tract in the internal capsule. ICH induced damage to this area can easily lead to severe neurological dysfunction and affects the prognosis and quality of life of patients. At present, the pathophysiological mechanisms of white matter injury (WMI) after ICH have attracted researchers' attention, but studies on the repair and recovery mechanisms and therapy strategies remain rare. In this review, we mainly summarized the WM recovery and treatment strategies after ICH by updating the WMI‐related content by reviewing the latest researches and proposing the bottleneck of the current research.