Mechanistic insights into Lipocalin-2 in ischemic stroke and hemorrhagic brain injury: Integrating animal and clinical studies.

Brain injuries, including strokes and traumatic brain injuries (TBI), are a major global health concern, contributing significantly to both mortality and long-term disability. Recent research has identified lipocalin-2 (LCN2), a glycoprotein secreted by various brain cells, as a key factor in influencing brain injury outcomes. Evidence from animal and clinical studies firmly establishes the pivotal role of LCN2 in driving the inflammatory responses triggered by damage to brain tissue. Furthermore, increased LCN2 promotes cellular differentiation, blood-brain barrier breakdown, and decreases cell viability. Interventions with LCN2 inhibitors attenuated brain injury through a reduction in the inflammation process and enhanced cellular viability. Potential mechanisms of LCN2 involve several pathways including the Janus kinase-2 (JAK2)-signal transducers and the transcription-3 (STAT3) signaling, hypoxia-inducible factor 1-alpha (HIF-1α)-LCN2-vascular endothelial growth factor alpha (VEGFα), and the PKR-like ER kinase (PERK) pathways. LCN2 itself interacts with diverse inflammatory cytokines in TBI and intracranial hemorrhage (ICH), resulting in disruption of the blood-brain barrier, increased programmed cell death, and an imbalance in iron homeostasis. Clinical studies have also shown that increased LCN2 level can act as a prognostic biomarker of outcomes following brain injuries. Therefore, this review aims to comprehensively evaluate the role and underlying mechanisms of LCN2 in brain injuries, including stroke and TBI, and explore potential therapeutic interventions targeting LCN2 in these conditions.

Dose-dependent benefits of iron-magnetic nanoparticle-coated human umbilical-derived mesenchymal stem cell treatment in rat intracranial hemorrhage model.

BACKGROUND: This study tested whether two doses of human umbilical-derived mesenchymal stem cells (hUC-MSCs) were superior to one dose for protecting the brain against intracranial hemorrhage (ICH) induced by intracranial injection collagenase and the capacity of ironic-magnetic-nanoparticles (Ir-MNa) coated hUC-MSCs tracked by MRI. METHODS AND RESULTS: Adult male SD rats (n = 40) were equally categorized into group 1 (sham-operated-control), group 2 (ICH), group 3 [ICH + Ir-MNa-coated hUC-MSCs/1.2 × 106 cells with an extracorporeal magnet over rat head (eCMag)/administered by left internal carotid artery (LICA) at post-3 h ICH], and group 4 (ICH + Ir-MNa-coated hUC-MSCs/1.2 × 106 cells with an eCMag/administered post-3 h ICH by LICA and 24 h by IV) and euthanized by day 28. The result showed that by day 28 after ICH induction the neurological function was severely impaired in group 2 than in group 1 that was significantly improved in group 3 and further significantly improved in group 4, whereas ICH volume exhibited an opposite pattern of neurological impairment among the groups (all p < 0.0001). Brain MRI demonstrated that by 4 h after ICH, Ir-MNa-coated hUC-MSCs were abundantly identified in ischemic area in group 4. The protein expressions of inflammatory (TNF-α/MMP-9/IL-1ß/iNOS)/oxidative-stress (NOX-1/NOX-2/oxidized protein)/apoptotic (caspase-3/mitochondrial Bax/PARP)/fibrotic (Smad3/TGF-ß)/mitochondrial-damaged (cytosolic-cytochrome-C) biomarkers displayed an identical pattern of neurological impairment among the groups (all p < 0.0001). The cellular expressions of inflammation (CD68+/CD11b+)/brain edema (AQP4+) biomarkers exhibited an identical pattern, whereas the neuronal-myelin (Doublecortin+/NeuN/nestin) biomarkers displayed an opposite pattern of neurological impairment (all p < 0.0001). CONCLUSION: Two doses of hUC-MSCs were superior to just one dose for protecting the brain against ICH-induced damage and Ir-MNa-coated hUC-MSCs offered a well adopted method for tracking hUC-MSCs homing into the brain.

Hemin-Induced Death Models Hemorrhagic Stroke and Is a Variant of Classical Neuronal Ferroptosis.

Ferroptosis is a caspase-independent, iron-dependent form of regulated necrosis extant in traumatic brain injury, Huntington disease, and hemorrhagic stroke. It can be activated by cystine deprivation leading to glutathione depletion, the insufficiency of the antioxidant glutathione peroxidase-4, and the hemolysis products hemoglobin and hemin. A cardinal feature of ferroptosis is extracellular signal-regulated kinase (ERK)1/2 activation culminating in its translocation to the nucleus. We have previously confirmed that the mitogen-activated protein (MAP) kinase kinase (MEK) inhibitor U0126 inhibits persistent ERK1/2 phosphorylation and ferroptosis. Here, we show that hemin exposure, a model of secondary injury in brain hemorrhage and ferroptosis, activated ERK1/2 in mouse neurons. Accordingly, MEK inhibitor U0126 protected against hemin-induced ferroptosis. Unexpectedly, U0126 prevented hemin-induced ferroptosis independent of its ability to inhibit ERK1/2 signaling. In contrast to classical ferroptosis in neurons or cancer cells, chemically diverse inhibitors of MEK did not block hemin-induced ferroptosis, nor did the forced expression of the ERK-selective MAP kinase phosphatase (MKP)3. We conclude that hemin or hemoglobin-induced ferroptosis, unlike glutathione depletion, is ERK1/2-independent. Together with recent studies, our findings suggest the existence of a novel subtype of neuronal ferroptosis relevant to bleeding in the brain that is 5-lipoxygenase-dependent, ERK-independent, and transcription-independent. Remarkably, our unbiased phosphoproteome analysis revealed dramatic differences in phosphorylation induced by two ferroptosis subtypes. As U0126 also reduced cell death and improved functional recovery after hemorrhagic stroke in male mice, our analysis also provides a template on which to build a search for U0126's effects in a variant of neuronal ferroptosis.SIGNIFICANCE STATEMENT Ferroptosis is an iron-dependent mechanism of regulated necrosis that has been linked to hemorrhagic stroke. Common features of ferroptotic death induced by diverse stimuli are the depletion of the antioxidant glutathione, production of lipoxygenase-dependent reactive lipids, sensitivity to iron chelation, and persistent activation of extracellular signal-regulated kinase (ERK) signaling. Unlike classical ferroptosis induced in neurons or cancer cells, here we show that ferroptosis induced by hemin is ERK-independent. Paradoxically, the canonical MAP kinase kinase (MEK) inhibitor U0126 blocks brain hemorrhage-induced death. Altogether, these data suggest that a variant of ferroptosis is unleashed in hemorrhagic stroke. We present the first, unbiased phosphoproteomic analysis of ferroptosis as a template on which to understand distinct paths to cell death that meet the definition of ferroptosis.

Androgen receptor contributes to microglial/macrophage activation in rats with intracranial hemorrhage by mediating the JMJD3/Botch/Notch1 axis.

Intracerebral hemorrhage (ICH) is a leading medical problem and has no effective treatment approach up until now. The transcription factor androgen receptor (AR) has been indicated in the cerebrovascular function recently. However, its participation in ICH remains unclear. The present study aims to expound the regulation of AR in microglia/macrophage phenotypes and the secondary brain injury in a rat model with ICH, and to discuss the involved pathway. Following the induction of ICH in rats, we found that ICH led to increased mNSS score, enhanced microglial activity, and promoted levels of inflammatory factors and apoptosis of brain cells. Using microarray analysis, AR was found to be significantly overexpressed in ICH rat brain tissues. AR repressed the transcription of Jumonji d3 (JMJD3, histone 3 demethylase). JMJD3 inhibited the methylation of Botch and promoted the activity of Notch1. JMJD3 hampered microglial activity and ameliorated secondary brain injury in rats, whereas upregulation of AR or downregulation of Botch reversed the protective effects of JMJD3. In conclusion, we found that AR promoted microglial activation and secondary brain injury via transcriptionally repressing JMJD3 and mediating the subsequent Botch/Notch1 pathway, which may provide novel insights into therapeutic options for the treatment of ICH.

Review of treatment and therapeutic targets in brain arteriovenous malformation.

Brain arteriovenous malformations (bAVM) are an important cause of intracranial hemorrhage (ICH), especially in younger patients. The pathogenesis of bAVM are largely unknown. Current understanding of bAVM etiology is based on studying genetic syndromes, animal models, and surgically resected specimens from patients. The identification of activating somatic mutations in the Kirsten rat sarcoma viral oncogene homologue (KRAS) gene and other mitogen-activated protein kinase (MAPK) pathway genes has opened up new avenues for bAVM study, leading to a paradigm shift to search for somatic, de novo mutations in sporadic bAVMs instead of focusing on inherited genetic mutations. Through the development of new models and understanding of pathways involved in maintaining normal vascular structure and functions, promising therapeutic targets have been identified and safety and efficacy studies are underway in animal models and in patients. The goal of this paper is to provide a thorough review or current diagnostic and treatment tools, known genes and key pathways involved in bAVM pathogenesis to summarize current treatment options and potential therapeutic targets uncovered by recent discoveries.

MiR-18a Aggravates Intracranial Hemorrhage by Regulating RUNX1-Occludin/ZO-1 Axis to Increase BBB Permeability.

OBJECTIVES: To study the molecular mechanisms of miR-18a aggravating intracranial hemorrhage (ICH) by increasing the blood-brain barrier (BBB) permeability. METHODS: Brain microvascular endothelial cells (BMVECs) and astrocytes were isolated, identified, and co-cultured to establish in vitro BBB model. BMVECs co-cultured with astrocytes were stimulated with or without thrombase and then transfected with miR-18a mimic and/or si-RUNX1. The trans-endothelial electric resistance (TEER) and FlNa flux were measured, respectively. The potential interaction between RUNX1 and miR-18a was also detected. Additionally, SD rats were injected with fresh autologous non-anticoagulant blood into the brain basal ganglia to establish ICH model. After administration with miR-18a, sh-miR-18a, miR-18a+RUNX1, sh-miR-18a+sh-RUNX1, respectively, BBB permeability was assessed. RESULTS: After overexpressing miR-18a, the expression levels of RUNX1, Occludin and ZO-1 were decreased, but the Evan's blue contents and brain water contents were significantly increased in ICH rats. Additionally, rat neurological function was impaired, accompanying with an increase of TEER and fluorescein sodium flux. MiR-18a was a direct target of RUNX1 and it could bind to the promoters of RUNX1 to inhibit the expression of Occuldin and ZO-1. Consistently, these phenomena could also be observed in the corresponding cell model. Conversely, miR-18a knockdown or RUNX1 overexpression just presented an improvement effect on ICH. CONCLUSIONS: MiR-18a plays a critical role during ICH because it targets to RUNX1 to inhibit the expression of tight junction proteins (Occludin and ZO-1) and then disrupt BBB permeability. MiR-18a might be a probable therapeutic target for ICH diseases.

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

Background and Purpose: Brain tissue-resident microglia and monocyte-derived macrophages (MDMs) are innate immune cells that contribute to the inflammatory response, phagocytosis of debris, and tissue repair after injury. We have previously reported that both microglia and MDMs transition from proinflammatory to reparative phenotypes over days after an intracerebral hemorrhage (ICH). However, their individual functional properties in the brain remain largely unknown. Here we characterized the differences between microglia and MDMs and further elucidate their distinct activation states and functional contributions to the pathophysiology and recovery after ICH. Methods: Autologous blood injection was used to model ICH in mice. Longitudinal transcriptomic analyses on isolated microglia and MDMs from mice at days 1, 3, 7 and 10 after ICH and naive controls identified core transcriptional programs that distinguish these cells. Imaging flow cytometry and in vivo phagocytosis assays were used to study phagocytic ability of microglia and MDMs. Antigen presentation was evaluated by ovalbumin-OTII CD4 T-cell proliferation assays with bone marrow­derived macrophages and primary microglia cultures. Results: MDMs had higher phagocytic activity and higher erythrophagocytosis in the ICH brain. Differential gene expression revealed distinct transcriptional signatures in the MDMs and microglia after ICH. MDMs had higher expression of MHCII (major histocompatibility complex class II) genes than microglia at all time points and greater ability to induce antigen-specific T-cell proliferation. Conclusions: The different ontogeny of microglia and MDMs lead to divergent responses and functions in the inflamed brain as these 2 cell populations differ in phagocytic functions and antigen-presenting capabilities in the brain after ICH.

The CTSC-RAB38 Fusion Transcript Is Associated With the Risk of Hemorrhage in Brain Arteriovenous Malformations.

Brain arteriovenous malformations (bAVMs) are congenital anomalies of blood vessels that cause intracranial hemorrhage in children and young adults. Chromosomal rearrangements and fusion genes play an important role in tumor pathogenesis, though the role of fusion genes in bAVM pathophysiological processes is unclear. The aim of this study was to identify fusion transcripts in bAVMs and analyze their effects. To identify fusion transcripts associated with bAVM, RNA sequencing was performed on 73 samples, including 66 bAVM and 7 normal cerebrovascular samples, followed by STAR-Fusion analysis. Reverse transcription polymerase chain reaction and Sanger sequencing were applied to verify fusion transcripts. Functional pathway analysis was performed to identify potential effects of different fusion types. A total of 21 fusion transcripts were detected. Cathepsin C (CTSC)-Ras-Related Protein Rab-38 (RAB38) was the most common fusion and was detected in 10 of 66 (15%) bAVM samples. In CTSC-RAB38 fusion-positive samples, CTSC and RAB38 expression was significantly increased and activated immune/inflammatory signaling. Clinically, CTSC-RAB38 fusion bAVM cases had a higher hemorrhage rate than non-CTSC-RAB38 bAVM cases (p < 0.05). Our study identified recurrent CTSC-RAB38 fusion transcripts in bAVMs, which may be associated with bAVM hemorrhage by promoting immune/inflammatory signaling.

Rh-relaxin-2 attenuates degranulation of mast cells by inhibiting NF-κB through PI3K-AKT/TNFAIP3 pathway in an experimental germinal matrix hemorrhage rat model.

BACKGROUND: Mast cells play an important role in early immune reactions in the brain by degranulation and the consequent inflammatory response. Our aim of the study is to investigate the effects of rh-relaxin-2 on mast cells and the underlying mechanisms in a germinal matrix hemorrhage (GMH) rat model. METHODS: One hundred seventy-three P7 rat pups were subjected to GMH by an intraparenchymal injection of bacterial collagenase. Clodronate liposome was administered through intracerebroventricular (i.c.v.) injections 24 h prior to GMH to inhibit microglia. Rh-relaxin-2 was administered intraperitoneally at 1 h and 13 h after GMH. Small interfering RNA of RXFP1 and PI3K inhibitor LY294002 were given by i.c.v. injection. Post-GMH evaluation included neurobehavioral function, Western blot analysis, immunofluorescence, Nissl staining, and toluidine blue staining. RESULTS: Our results demonstrated that endogenous relaxin-2 was downregulated and that RXFP1 level peaked on the first day after GMH. Administration of rh-relaxin-2 improved neurological functions, attenuated degranulation of mast cells and neuroinflammation, and ameliorated post-hemorrhagic hydrocephalus (PHH) after GMH. These effects were associated with RXFP1 activation, increased expression of PI3K, phosphorylated AKT and TNFAIP3, and decreased levels of phosphorylated NF-κB, tryptase, chymase, IL-6, and TNF-α. However, knockdown of RXFP1 and PI3K inhibition abolished the protective effects of rh-relaxin-2. CONCLUSIONS: Our findings showed that rh-relaxin-2 attenuated degranulation of mast cells and neuroinflammation, improved neurological outcomes, and ameliorated hydrocephalus after GMH through RXFP1/PI3K-AKT/TNFAIP3/NF-κB signaling pathway.

A comprehensive review of therapeutic targets that induce microglia/macrophage-mediated hematoma resolution after germinal matrix hemorrhage.

Currently, there is no effective treatment for germinal matrix hemorrhage and intraventricular hemorrhage (GMH-IVH), a common and often fatal stroke subtype in premature infants. Secondary brain injury after GMH-IVH is known to involve blood clots that contribute to inflammation and neurological deficits. Furthermore, the subsequent blood clots disrupt normal cerebrospinal fluid circulation and absorption after GMH-IVH, contributing to posthemorrhagic hydrocephalus (PHH). Clinically, GMH-IVH severity is graded on a I to IV scale: Grade I is confined to the germinal matrix, grade II includes intraventricular hemorrhage, grade III includes intraventricular hemorrhage with extension into dilated ventricles, and grade IV includes intraventricular hemorrhage with extension into dilated ventricles as well as parenchymal hemorrhaging. GMH-IVH hematoma volume is the best prognostic indicator, where patients with higher grades have worsened outcomes. Various preclinical studies have shown that rapid hematoma resolution quickly ameliorates inflammation and improves neurological outcomes. Current experimental evidence identifies alternatively activated microglia as playing a pivotal role in hematoma clearance. In this review, we discuss the pathophysiology of GMH-IVH in the development of PHH, microglia/macrophage's role in the neonatal CNS, and established/potential therapeutic targets that enhance M2 microglia/macrophage phagocytosis of blood clots after GMH-IVH.

Prothrombin Complex Concentrates are Superior to Fresh Frozen Plasma for Emergency Reversal of Vitamin K Antagonists: A Meta-Analysis in 2606 Subjects.

BACKGROUND: Urgent reversal of vitamin K antagonists (VKAs) is required for major bleeding or urgent surgery by intravenous vitamin K with either prothrombin complex concentrates (PCCs) or fresh frozen plasma (FFP). However, there is lack of consensus regarding the superiority of either reversal agent. We sought to compare the performance of PCC and FFP in urgent reversal of VKA. METHODS: A meta-analysis was conducted up to November 2018. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using a random effects model. RESULTS: Seventeen studies comprising 2606 participants met the inclusion criteria. Compared with FFP treatment, PCC treatment led to a reduction in 90-day all-cause mortality (OR 0.60, 95% CI 0.40-0.90, p = 0.01), better reversal of INR (OR 7.36, 95% CI 4.18-12.98; p < 0.00001) and lower risk of at least one treatment-related adverse event (OR 0.45, 95% CI 0.26-0.80, p = 0.006). Among patients with VKA-associated intracranial haemorrhage, PCC treatment led to a reduction in 90-day all-cause mortality (OR 0.58, 95% CI 0.35-0.94, p = 0.03) and better reversal of INR (OR 6.52, 95% CI 1.66-25.59, p = 0.007). There were no differences between these two agents in thrombogenicity, requirement for and quantity of red blood cell transfusions, all adverse events, fluid overload or disability on discharge or at 90 days. CONCLUSIONS: As an agent for urgent reversal of VKA, PCC outperforms FFP in 90-day all-cause mortality including those with VKA-related intracranial haemorrhage, INR reversal and treatment-related adverse events.

Risk factors for hemorrhage of brain arteriovenous malformation.

Patients with brain arteriovenous malformation (bAVM) are at risk of intracranial hemorrhage (ICH). Overall, bAVM accounts for 25% of hemorrhagic strokes in adults <50 years of age. The treatment of unruptured bAVMs has become controversial, because the natural history of these patients may be less morbid than invasive therapies. Available treatments include observation, surgical resection, endovascular embolization, stereotactic radiosurgery, or combination thereof. Knowing the risk factors for bAVM hemorrhage is crucial for selecting appropriate therapeutic strategies. In this review, we discussed several biological risk factors, which may contribute to bAVM hemorrhage.

Inhibition of intracranial hemangioma growth and hemorrhage by TNFSF15.

Hemangioblastoma (HB) is an abnormal intracranial buildup of blood vessels that exhibit a great potential for hemorrhage. Surgical options are limited, and few medications are available for treatment. We show here by immunohistochemical analysis that HB lesions display highly increased levels of VEGF expression and macrophage/microglia infiltration compared with those in normal brain tissues. In the meantime, TNF superfamily 15 (TNFSF15) (also known as vascular endothelial growth inhibitor), an antiangiogenic cytokine, is highly expressed in normal brain blood vessels but diminished in HB lesions. We set up a brain hemangioma model by using mouse bEnd.3 cells of a T antigen-transformed endothelial cell line that produce a large amount of VEGF. When implanted in mouse brains, these cells form lesions that closely resemble the pathologic characteristics of HB. Retroviral infection of bEnd.3 cells with TNFSF15 leads to inhibition of VEGF production and retardation of hemangioma formation. Similar results are obtained when wild-type bEnd.3 cells are implanted in the brains of transgenic mice overexpressing TNFSF15. Additionally, TNFSF15 treatment results in enhanced pericyte coverage of the blood vessels in the lesions together with reduced inflammatory cell infiltration and decreased hemorrhage. These findings indicate that the ability of TNFSF15 to counterbalance the abnormally highly angiogenic and inflammatory potential of the microenvironment of HB is of therapeutic value for the treatment of this disease.-Yang, G.-L., Han, Z., Xiong, J., Wang, S., Wei, H., Qin, T.-T., Xiao, H., Liu, Y., Xu, L.-X., Qi, J.-W., Zhang, Z.-S., Jiang, R., Zhang, J., Li, L.-Y. Inhibition of intracranial hemangioma growth and hemorrhage by TNFSF15.

Selenium Drives a Transcriptional Adaptive Program to Block Ferroptosis and Treat Stroke.

Ferroptosis, a non-apoptotic form of programmed cell death, is triggered by oxidative stress in cancer, heat stress in plants, and hemorrhagic stroke. A homeostatic transcriptional response to ferroptotic stimuli is unknown. We show that neurons respond to ferroptotic stimuli by induction of selenoproteins, including antioxidant glutathione peroxidase 4 (GPX4). Pharmacological selenium (Se) augments GPX4 and other genes in this transcriptional program, the selenome, via coordinated activation of the transcription factors TFAP2c and Sp1 to protect neurons. Remarkably, a single dose of Se delivered into the brain drives antioxidant GPX4 expression, protects neurons, and improves behavior in a hemorrhagic stroke model. Altogether, we show that pharmacological Se supplementation effectively inhibits GPX4-dependent ferroptotic death as well as cell death induced by excitotoxicity or ER stress, which are GPX4 independent. Systemic administration of a brain-penetrant selenopeptide activates homeostatic transcription to inhibit cell death and improves function when delivered after hemorrhagic or ischemic stroke.

Clinical significance of detecting serum melatonin and SBDPs in brain injury in preterm infants.

BACKGROUND: To investigate the clinical values of serum melatonin and αII spectrin cleavage products (SBDPs) in assessing the severity of brain injury in preterm infants. METHODS: Sixty-four premature infants in total were selected and classified into the brain injury group (BI, n = 30) and the non-brain injury group (CON, n = 34) according to cranial imaging examination. The serum melatonin and SBDPs were detected by ELISA. All the preterm infants were received NBNA testing at 40 weeks of corrected gestational age. RESULTS: The levels of melatonin and SBDPs in the BI group were significantly higher than the CON group (p < 0.05) and the levels in the infants with severe brain injury were significantly higher than those with mild brain injury (p < 0.05), as well as exhibiting a negative correlation with the NBNA score at 40 weeks of corrected gestational age (p < 0.05). CONCLUSIONS: Detecting melatonin and SBDPs has clinical value in diagnosing and assessing the severity of brain injury in preterm infants.

Diverse Inflammatory Response After Cerebral Microbleeds Includes Coordinated Microglial Migration and Proliferation.

BACKGROUND AND PURPOSE: Cerebral microbleeds are linked to cognitive decline, but it remains unclear how they impair neuronal function. Infarction is not typically observed near microbleeds, suggesting more subtle mechanisms, such as inflammation, may play a role. Because of their small size and largely asymptomatic nature, real-time detection and study of spontaneous cerebral microbleeds in humans and animal models are difficult. METHODS: We used in vivo 2-photon microscopy through a chronic cranial window in adult mice to follow the inflammatory response after a cortical microhemorrhage of ≈100 µm diameter, induced by rupturing a targeted cortical arteriole with a laser. RESULTS: The inflammatory response included the invasion of blood-borne leukocytes, the migration and proliferation of brain-resident microglia, and the activation of astrocytes. Nearly all inflammatory cells responding to the microhemorrhage were brain-resident microglia, but a small number of CX3CR1+ and CCR2+ macrophages, ultimately originating from the invasion of blood-borne monocytes, were also found near the lesion. We found a coordinated pattern of microglia migration and proliferation, where microglia within 200 µm of the microhemorrhage migrated toward the lesion over hours to days. In contrast, microglia proliferation was not observed until ≈40 hours after the lesion and occurred primarily in a shell-shaped region where the migration of microglia decreased their local density. These data suggest that local microglia density changes may trigger proliferation. Astrocytes activated in a similar region as microglia but delayed by a few days. By 2 weeks, this inflammatory response had largely resolved. CONCLUSIONS: Although microhemorrhages are small in size, the brain responds to a single bleed with an inflammatory response that involves brain-resident and blood-derived cells, persists for weeks, and may impact the adjacent brain microenvironment.

Rosiglitazone Infusion Therapy Following Minimally Invasive Surgery for Intracranial Hemorrhage Evacuation Decreased Perihematomal Glutamate Content and Blood-Brain Barrier Permeability in Rabbits.

OBJECTIVE: To observe effects of rosiglitazone (RSG) infusion therapy on perihematomal peroxisome-proliferator-activated receptor gamma (PPARγ), glutamate, blood-brain barrier (BBB) permeability, and brain edema. METHODS: Fifty male rabbits (2.8-3.4 kg) were randomly assigned to a normal control (NC) group, model control (MC) group, RSG group, minimally invasive surgery (MIS) group, or MIS and RSG (MIS+RSG) group. Intracranial hemorrhage was induced in all rabbits except for the NC group. MIS procedures were performed to evacuate the intracranial hemorrhage 6 hours after the intracranial hemorrhage model was prepared successfully. The animals were sacrificed on day 7, and the perihematomal brain tissue was obtained to determine PPARγ, glutamate, and BBB permeability. RESULTS: Compared with the MC group, the MIS group displayed a remarkable decrease in PPARγ, glutamate, and BBB permeability. The RSG group showed similar results in glutamate level and BBB permeability but a significant increase in PPARγ. The MIS+RSG group displayed an increase in PPARγ and a more significant decrease in glutamate, BBB permeability, and neurologicl deficit scores compared with the other groups. CONCLUSIONS: Performing MIS followed by RSG infusion therapy might increase PPARγ expression and might be more efficacious for reducing glutamate level and BBB permeability and improving neurologic function than MIS or RSG therapy used alone.

Cerebrovascular Disease: Consequences of Obesity-Induced Endothelial Dysfunction.

Despite the well-known global impact of overweight and obesity in the incidence of cerebrovascular disease, many aspects of this association are still inconsistently defined. In this chapter we aim to present a critical review on the links between obesity and both ischemic and hemorrhagic stroke and discuss its influence on functional outcomes, survival, and current treatments to acute and chronic stroke. The role of cerebrovascular endothelial function and respective modulation is also described as well as its laboratory and clinical assessment. In this context, the major contributing mechanisms underlying obesity-induced cerebral endothelial function (adipokine secretion, insulin resistance, inflammation, and hypertension) are discussed. A special emphasis is given to the participation of adipokines in the pathophysiology of stroke, namely adiponectin, leptin, resistin, apelin, and visfatin.

YAP/TAZ regulates sprouting angiogenesis and vascular barrier maturation.

Angiogenesis is a multistep process that requires coordinated migration, proliferation, and junction formation of vascular endothelial cells (ECs) to form new vessel branches in response to growth stimuli. Major intracellular signaling pathways that regulate angiogenesis have been well elucidated, but key transcriptional regulators that mediate these signaling pathways and control EC behaviors are only beginning to be understood. Here, we show that YAP/TAZ, a transcriptional coactivator that acts as an end effector of Hippo signaling, is critical for sprouting angiogenesis and vascular barrier formation and maturation. In mice, endothelial-specific deletion of Yap/Taz led to blunted-end, aneurysm-like tip ECs with fewer and dysmorphic filopodia at the vascular front, a hyper-pruned vascular network, reduced and disarranged distributions of tight and adherens junction proteins, disrupted barrier integrity, subsequent hemorrhage in growing retina and brain vessels, and reduced pathological choroidal neovascularization. Mechanistically, YAP/TAZ activates actin cytoskeleton remodeling, an important component of filopodia formation and junction assembly. Moreover, YAP/TAZ coordinates EC proliferation and metabolic activity by upregulating MYC signaling. Overall, these results show that YAP/TAZ plays multifaceted roles for EC behaviors, proliferation, junction assembly, and metabolism in sprouting angiogenesis and barrier formation and maturation and could be a potential therapeutic target for treating neovascular diseases.

Ghrelin Therapy Decreases Incidents of Intracranial Hemorrhage in Mice after Whole-Body Ionizing Irradiation Combined with Burn Trauma.

Nuclear industrial accidents and the detonation of nuclear devices cause a variety of damaging factors which, when their impacts are combined, produce complicated injuries challenging for medical treatment. Thus, trauma following acute ionizing irradiation (IR) can deteriorate the IR-induced secondary reactive metabolic and inflammatory impacts to dose-limiting tissues, such as bone marrow/lymphatic, gastrointestinal tissues, and vascular endothelial tissues, exacerbating the severity of the primary injury and decreasing survival from the exposure. Previously we first reported that ghrelin therapy effectively improved survival by mitigating leukocytopenia, thrombocytopenia, and bone-marrow injury resulting from radiation combined with burn trauma. This study was aimed at investigating whether radiation combined with burn trauma induced the cerebro-vascular impairment and intracranial hemorrhage that could be reversed by ghrelin therapy. When B6D2F1 female mice were exposed to 9.5 Gy Cobalt-60 γ-radiation followed by 15% total skin surface burn, cerebro-vascular impairment and intracranial hemorrhage as well as platelet depletion were observed. Ghrelin treatment after irradiation combined with burn trauma significantly decreased platelet depletion and brain hemorrhage. The results suggest that ghrelin treatment is an effective therapy for ionizing radiation combined with burn trauma.