Revisiting Minocycline in Intracerebral Hemorrhage: Mechanisms and Clinical Translation

Ferroptosis-associated pathological injury mechanisms and therapeutic strategies after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is an important neurological disease caused by the rupture of blood vessels in the brain parenchyma, with a high mortality and disability rate. At present, many studies have focused on the injury mechanisms and intervention strategies after ICH. However, there is no effective clinical treatment that can significantly improve the prognosis of ICH patients. Ferroptosis, a regulated form of cell death, has been identified as a significant contributor to brain tissues damage and neurological dysfunction following ICH. The hallmark of ferroptosis is iron-dependent lipid peroxidation, which is closely related to the pathological process of iron overload and oxidative stress after ICH. Exploring the interaction between ferroptosis and pathological injury mechanisms post-ICH will contribute to our understanding the key pathways involved in the ferroptosis-related injury mechanisms and facilitating the discovery of appropriate intervention strategies. On this basis, we present a comprehensive overview of ferroptosis-related brain injury mechanisms (e.g., iron overload, oxidative stress, inflammatory response and mass effect) in the pathogenesis and development of ICH. Following ICH, the degradation of hematoma and iron metabolism provide the fundamental material basis for ferroptosis, and oxidative stress primarily participates in the lipid peroxidation process of ferroptosis via related molecular pathways (such as the GPX4). By synthesizing current evidence, this article aims to provide a theoretical foundation for future research on therapeutic strategies targeting ferroptosis and related pathways in ICH.

Crosstalk Between Matrix Metalloproteinases and Their Inducer EMMPRIN/CD147: a Promising Therapeutic Target for Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is characterized by the disruption of cerebrovascular integrity, resulting in hematoma enlargement, edema formation, and physical damage in the brain parenchyma. Primary ICH also leads to secondary brain injury contributed by oxidative stress, dysregulated immune responses, and proteolysis. In this context, matrix metalloproteinases (MMPs) represent a ubiquitous superfamily of structurally related zinc-dependent endopeptidases capable of degrading all components of the extracellular matrix. They disrupt the blood-brain barrier and promote neuroinflammation. Importantly, several MMP members are upregulated following ICH, and members may have different functions at specific periods in ICH. Hence, the modulation and function of MMPs are more complex than expected. Extracellular matrix metalloproteinase inducer (EMMPRIN, CD147) is a transmembrane glycoprotein that induces the production of MMPs. In this review, we systematically discuss the biology and functions of MMPs and EMMPRIN/CD147 in ICH and the complex crosstalk between them.

Pathophysiology of Intracerebral Hemorrhage: Recovery Trajectories

Recovery trajectories in intracerebral hemorrhage (ICH) are recognized as distinct from those observed in ischemic stroke. This narrative review aims to clarify the pathophysiology underlying ICH recovery patterns, highlighting the unique timeline and nature of functional improvements seen in ICH survivors. Population-based cohort studies tracking functional outcomes in a longitudinal fashion, along with randomized clinical trial data with standardized outcome assessments, have demonstrated that ICH recovery generally has a delayed onset in the first weeks, followed by a steep early subacute stage recovery (typically up to 3 months) continuing in protracted, gradual improvements beyond 3 to 6 months. Understanding these recovery patterns, and how these differ from ischemic stroke, is crucial for providing accurate prognostic information, facilitating targeted health care delivery, and optimizing therapeutic interventions and the design of ICH randomized trials. This article synthesizes current evidence on early- and late-stage functional recovery trajectories in primary, spontaneous ICH and cognitive outcomes, emphasizing the clinical and research implications of these recovery patterns.

Microglial Mechanisms and Therapeutic Potential in Brain Injury Post-Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a particularly common public health problem with a high mortality and disability rate and no effective treatments to enhance clinical prognosis. The increased aging population, improved vascular prevention, and augmented use of antithrombotic agents have collectively contributed to the rise in ICH incidence over the past few decades. The exploration and understanding of mechanisms and intervention strategies has great practical significance for expanding treatments and improving prognosis of ICH. Microglia, as resident macrophages of central nervous system, are responsible for the first immune defense post-ICH. After ICH, M1 microglia is firstly activated by primary injury and thrombin; subsequently, reactive microglia can further amplify the immune response and exert secondary injury (eg, oxidative stress, neuronal damage, and brain edema). The pro-inflammatory phenotype transmits to M2 microglia within 7 days post-ICH, which plays a key role in erythrophagocytosis and limiting the inflammatory secondary injury. Microglial M2 polarization has significant implications for improving prognosis, this process can be mediated through crosstalk with other cells, metabolic changes, and microbiota interaction. Clarifying the effect, timing, and potential downstream effects of multiple mechanisms that synergistically trigger anti-inflammatory responses may be necessary for clinical translation. Analyses of such intricate interaction between microglia cells and brain injury/repair mechanisms will contribute to our understanding of the critical microglial responses to microenvironment and facilitating the discovery of appropriate intervention strategies. Here, we present a comprehensive overview of the latest evidences on microglial dynamics following ICH, their role in driving primary/secondary injury mechanisms as well as neurorepair/plasticity, and possible treatment strategies targeting microglia.

Bioactive Self-Assembled Nanoregulator Enhances Hematoma Resolution and Inhibits Neuroinflammation in the Treatment of Intracerebral Hemorrhage

Hematoma and secondary neuroinflammation continue to pose a significant challenge in the clinical treatment of intracerebral hemorrhage (ICH). This study describes a nanoregulator formed through the self-assembly of Mg2+ and signal regulatory protein α (SIRPα) DNAzyme (SDz), aimed at enhancing hematoma resolution and inhibiting neuroinflammation in the treatment of ICH. The structure of SDz collapses in response to the acidic endo/lysosomal microenvironment of microglia, releasing Mg2+ and the SIRPα DNAzyme. The Mg2+ then acts as a cofactor to activate the SIRPα DNAzyme. By blocking the CD47-SIRPα signaling pathway, microglia can rapidly and effectively phagocytose red blood cells (RBCs), thereby promoting the clearance of the hematoma. Simultaneously, Mg2+ reset the microglia to the M2 phenotype by inhibiting the MYD88/MAPK/NF-κB signaling pathway, thereby modulating the inflammatory microenvironment of ICH. This co-delivery and synergistic strategy resulted in a significant reduction in hematoma size, decreasing from 11.90 to 5.84 mm3, and promoted recovery from ICH with minimal systemic side effects. This simple yet highly effective nanoplatform, which involves complex synergistic mechanisms, proves to be effective for ICH therapy and holds great promise for introducing novel perspectives into clinical and translational approaches for ICH.

Beyond nimodipine: advanced neuroprotection strategies for aneurysmal subarachnoid hemorrhage vasospasm and delayed cerebral ischemia

The clinical management of aneurysmal subarachnoid hemorrhage (SAH)-associated vasospasm remains a challenge in neurosurgical practice, with its prevention and treatment having a major impact on neurological outcome. While considered a mainstay, nimodipine is burdened by some non-negligible limitations that make it still a suboptimal candidate of pharmacotherapy for SAH. This narrative review aims to provide an update on the pharmacodynamics, pharmacokinetics, overall evidence, and strength of recommendation of nimodipine alternative drugs for aneurysmal SAH-associated vasospasm and delayed cerebral ischemia. A PRISMA literature search was performed in the PubMed/Medline, Web of Science, ClinicalTrials.gov, and PubChem databases using a combination of the MeSH terms "medical therapy," "management," "cerebral vasospasm," "subarachnoid hemorrhage," and "delayed cerebral ischemia." Collected articles were reviewed for typology and relevance prior to final inclusion. A total of 346 articles were initially collected. The identification, screening, eligibility, and inclusion process resulted in the selection of 59 studies. Nicardipine and cilostazol, which have longer half-lives than nimodipine, had robust evidence of efficacy and safety. Eicosapentaenoic acid, dapsone and clazosentan showed a good balance between effectiveness and favorable pharmacokinetics. Combinations between different drug classes have been studied to a very limited extent. Nicardipine, cilostazol, Rho-kinase inhibitors, and clazosentan proved their better pharmacokinetic profiles compared with nimodipine without prejudice with effective and safe neuroprotective role. However, the number of trials conducted is significantly lower than for nimodipine. Aneurysmal SAH-associated vasospasm remains an area of ongoing preclinical and clinical research where the search for new drugs or associations is critical.

Mesenchymal Stem Cell-Derived Exosomal miR-150-3p Affects Intracerebral Hemorrhage By Regulating TRAF6/NF-κB Axis, Gut Microbiota and Metabolism

Intracerebral hemorrhage (ICH) is a severe subtype of stroke for which there is no effective treatment. Stem cell and exosome (Exo) therapies have great potential as new approaches for neuroprotection and neurorestoration in treating ICH. We aimed to investigate whether Exo affects ICH by regulating the ecology of gut microbiota and metabolism and the mechanisms involved. First, differential miRNAs in ICH were screened by bioinformatics and verified by qRT-PCR. Then, Exo was extracted from mouse bone marrow mesenchymal stem cells (MSCs) and identified. Dual-luciferase reporter gene assay was utilized to verify the binding relationship between miR-150-3p and TRAF6. A mouse ICH model was constructed and treated with Exo. Next, we knocked down miR-150-3p and performed fecal microbiota transplantation (FMT). Then changes in gut microbiota and differential metabolites were detected by 16S rRNA sequencing and metabolomics analysis. We found that miR-150-3p expression was lowest in the brain tissue of the ICH group compared to the Sham group. Besides, low miR-150-3p level in ICH was encapsulated by MSC-derived Exo. Moreover, miR-150-3p bound to TRAF6 and was negatively correlated. With the addition of Exo^{miR-150-3p inhibitor}, we found that MSC-derived exosomal miR-150-3p may affect ICH injury via TRAF6/NLRP3 axis. MSC-derived exosomal miR-150-3p caused changes in gut microbiota, including Proteobacteria, Muribaculaceae, Lachnospiraceae_NK4A136_group, and Acinetobacter. Moreover, MSC-derived exosomal miR-150-3p caused changes in metabolism. After further FMT, gut microbiota-mediated MSC-derived Exo affected ICH with reduced apoptosis and reduced levels of inflammatory factors. In conclusion, MSC-derived exosomal miR-150-3p affected ICH by regulating TRAF6/NF-κB axis, gut microbiota and metabolism.

Ferroptosis: Underlying mechanism and the crosstalk with other modes of neuronal death after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a serious cerebrovascular disease with high rates of morbidity, mortality, and disability. Optimal treatment of ICH is a major clinical challenge, as the underlying mechanisms remain unclear. Ferroptosis, a newly identified form of non-apoptotic programmed cell death, is characterized by the iron-induced accumulation of lipid reactive oxygen species (ROS), leading to intracellular oxidative stress. Lipid ROS causes damage to nucleic acids, proteins, and cell membranes, eventually resulting in ferroptosis. In the past 10 years, ferroptosis has resulted in plenty of discoveries and breakthroughs in cancer, neurodegeneration, and other diseases. Some studies have also reported that ferroptosis does occur after ICH in vitro and in vivo and contribute to neuronal death. However, the studies on ferroptosis following ICH are still in the preliminary stage. In this review, we will summarize the current evidence on the mechanism underlying ferroptosis after ICH. And review the traditional modes of neuronal death to identify the crosstalk with ferroptosis in ICH, including apoptosis, necroptosis, and autophagy. Additionally, we also aim to explore the promising therapeutic application of ferroptosis in cell death-based ICH.

Constitutively active microglial populations limit anorexia induced by the food contaminant deoxynivalenol

Microglia are involved in neuroinflammatory processes during diverse pathophysiological conditions. To date, the possible contribution of these cells to deoxynivalenol (DON)-induced brain inflammation and anorexia has not yet been evaluated. DON, one of the most abundant trichothecenes found in cereals, has been implicated in mycotoxicosis in both humans and farm animals. DON-induced toxicity is characterized by reduced food intake, weight gain, and immunological effects. We previously showed that exposure to DON induces an inflammatory response within the hypothalamus and dorsal vagal complex (DVC) which contributes to DON-induced anorexia. Here, in response to anorectic DON doses, we reported microglial activation within two circumventricular organs (CVOs), the area postrema (AP) and median eminence (ME) located in the DVC and the hypothalamus, respectively. Interestingly, this microglial activation was observed while DON-induced anorexia was ongoing (i.e., 3 and 6 h after DON administration). Next, we took advantage of pharmacological microglia deletion using PLX3397, a colony-stimulating factor 1 receptor (CSF1R)-inhibitor. Surprisingly, microglia-depleted mice exhibited an increased sensitivity to DON since non-anorectic DON doses reduced food intake in PLX3397-treated mice. Moreover, low DON doses induced c-Fos expression within feeding behavior-associated structures in PLX3397-treated mice but not in control mice. In parallel, we have highlighted heterogeneity in the phenotype of microglial cells present in and around the AP and ME of control animals. In these areas, microglial subpopulations expressed IBA1, TMEM119, CD11b and CD68 to varying degrees. In addition, a CD68 positive subpopulation showed, under resting conditions, a noticeable phagocytotic/endocytotic activity. We observed that DON strongly reduced CD68 in the hypothalamus and DVC. Finally, inactivation of constitutively active microglia by intraperitoneal administration of minocycline resulted in anorexia with a DON dose ineffective in control mice. Taken together, these results strongly suggest that various populations of microglial cells residing in and around the CVOs are maintained in a functionally active state even under physiological conditions. We propose that these microglial cell populations are attempting to protect the brain parenchyma from hazardous molecules coming from the blood. This study could contribute to a better understanding of how microglia respond to environmental contaminants.

Therapeutic strategies for intracerebral hemorrhage

Stroke is the second highest cause of death globally, with an increasing incidence in developing countries. Intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes. ICH is associated with poor neurological outcomes and high mortality due to the combination of primary and secondary injury. Fortunately, experimental therapies are available that may improve functional outcomes in patients with ICH. These therapies targeting secondary brain injury have attracted substantial attention in their translational potential. Here, we summarize recent advances in therapeutic strategies and directions for ICH and discuss the barriers and issues that need to be overcome to improve ICH prognosis.

Extracellular matrix metalloproteinase inducer in brain ischemia and intracerebral hemorrhage

Increasing evidence from preclinical and clinical studies link neuroinflammation to secondary brain injury after stroke, which includes brain ischemia and intracerebral hemorrhage (ICH). Extracellular matrix metalloproteinase inducer (EMMPRIN), a cell surface transmembrane protein, is a key factor in neuroinflammation. It is widely elevated in several cell types after stroke. The increased EMMPRIN appears to regulate the expression of matrix metalloproteinases (MMPs) and exacerbate the pathology of stroke-induced blood-brain barrier dysfunction, microvascular thrombosis and neuroinflammation. In light of the neurological effects of EMMPRIN, we present in this review the complex network of roles that EMMPRIN has in brain ischemia and ICH. We first introduce the structural features and biological roles of EMMPRIN, followed by a description of the increased expression of EMMPRIN in brain ischemia and ICH. Next, we discuss the pathophysiological roles of EMMPRIN in brain ischemia and ICH. In addition, we summarize several important treatments for stroke that target the EMMPRIN signaling pathway. Finally, we suggest that EMMPRIN may have prospects as a biomarker of stroke injury. Overall, this review collates experimental and clinical evidence of the role of EMMPRIN in stroke and provides insights into its pathological mechanisms.

Neuroprotective Effects of Chlorogenic Acid in a Mouse Model of Intracerebral Hemorrhage Associated with Reduced Extracellular Matrix Metalloproteinase Inducer

Chlorogenic acid (CGA) has been reported to have various biological activities, such as anti-inflammatory, anti-oxidant and anti-apoptosis effects. However, the role of CGA in intracerebral hemorrhage (ICH) and the underlying mechanisms remain undiscovered. The current study aims to investigate the effect of CGA on neuroinflammation and neuronal apoptosis after inhibition of EMMPRIN in a collagenase-induced ICH mouse model. Dose optimization data showed that intraperitoneal administration of CGA (30 mg/kg) significantly attenuated neurological impairments and reduced brain water content at 24 h and 72 h compared with ICH mice given vehicle. Western blot and immunofluorescence analyses revealed that CGA remarkably decreased the expression of extracellular matrix metalloproteinase inducer (EMMPRIN) in perihematomal areas at 72 h after ICH. CGA also reduced the expression of matrix metalloproteinases-2/9 (MMP-2/9) at 72 h after ICH. CGA diminished Evans blue dye extravasation and reduced the loss of zonula occludens-1 (ZO-1) and occludin. CGA-treated mice had fewer activated Iba-1-positive microglia and MPO-positive neutrophils. Finally, CGA suppressed cell death around the hematoma and reduced overall brain injury. These outcomes highlight that CGA treatment confers neuroprotection in ICH likely by inhibiting expression of EMMPRIN and MMP-2/9, and alleviating neuroinflammation, blood–brain barrier (BBB) disruption, cell death and brain injury.

Iron Neurotoxicity and Protection by Deferoxamine in Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a subtype of stroke that is characterized by high morbidity and mortality, for which clinical outcome remains poor. An extensive literature indicates that the release of ferrous iron from ruptured erythrocytes in the hematoma is a key pathogenic factor in ICH-induced brain injury. Deferoxamine is an FDA-approved iron chelator that has the capacity to penetrate the blood-brain barrier after systemic administration and binds to iron. Previous animal studies have shown that deferoxamine attenuates ICH-induced brain edema, neuronal death, and neurological deficits. This review summarizes recent progress of the mechanisms by which deferoxamine may alleviate ICH and discusses further studies on its clinical utility.

Neuroprotection by Ozanimod Following Intracerebral Hemorrhage in Mice

The destruction of the blood-brain barrier (BBB) after intracerebral hemorrhage (ICH) is associated with poor prognosis. Modulation of sphingosine 1-phosphate receptor (S1PR) may improve outcomes from ICH. Ozanimod (RPC-1063) is a newly developed S1PR regulator which can selectively modulate type 1/5 sphingosine receptors. Here, we studied the impact of Ozanimod on neuroprotection in an experimental mouse model of ICH, induced by injecting collagenase type VII into the basal ganglia. Ozanimod was administered by gavage 2 h after surgery and once a day thereafter until sacrifice. The results demonstrate that Ozanimod treatment improved neurobehavioral deficits in mice and decreased weight loss after ICH. Ozanimod significantly reduced the density of activated microglia and infiltrated neutrophils in the perihematoma region. Furthermore, Ozanimod reduced hematoma volume and water content of the ICH brain. The results of TUNEL staining indicate that Ozanimod mitigated brain cell death. The quantitative data of Evans blue (EB) staining showed that Ozanimod reduced EB dye leakage. Overall, Ozanimod reduces the destruction of the BBB and exert neuroprotective roles following ICH in mice.