Stent-to-vessel diameter ratio is associated with in-stent stenosis after flow-diversion treatment of intracranial aneurysms.

BACKGROUND AND PURPOSE: Flow-diversion treatment for intracranial aneurysms has been associated with the development of in-stent stenosis (ISS) for unclear reasons. We assess whether the size of the stent relative to that of the vessel (the stent-to-vessel diameter ratio, or SVR) may be predictive of the development of ISS after treatment with flow diverters. METHODS: We retrospectively reviewed patients with unruptured intracranial aneurysms who underwent flow-diversion treatment using either the Pipeline or Tubridge embolization device from September 2018 to September 2022. The relationship between SVR and ISS was analyzed. Multiple logistic regression models were used to determine the significant predictors. RESULTS: A total of 458 patients with 481 aneurysms were included. In a mean angiographic follow-up of 10.73 ± 3.97 months, ISS was detected in 68 cases (14.1 %). After adjusting for candidate variables, a higher distal SVR (DSVR) was associated with an increased risk of ISS (adjusted odds ratio [aOR] = 3.420, 95 % confidence interval [CI] = 1.182 - 9.889, p = 0.023). We conducted a subgroup analysis of the two different flow diverters to assess the effects of their individual characteristics. Our results showed a significant association between the DSVR and the incidence of ISS in both the Pipeline (aOR = 4.033, 95 % CI = 1.156-14.072, p = 0.029) and Tubridge groups (aOR = 11.981, 95 % CI=1.005-142.774, p = 0.049). CONCLUSION: A higher DSVR was associated with an increased risk of ISS. This may help neurointerventionalists select an appropriate stent size when conducting flow-diversion treatment for intracranial aneurysms.

Electroacupuncture promotes remyelination and alleviates cognitive deficit via promoting OPC differentiation in a rat model of subarachnoid hemorrhage.

Subarachnoid hemorrhage (SAH) is a devastating cerebral vascular disease which causes neurological deficits including long-term cognitive deficit. Demyelination of white matter is correlated with cognitive deficit in SAH. Electroacupuncture (EA) is a traditional Chinese medical treatment which protects against cognitive deficit in varies of neurological diseases. However, whether EA exerts protective effect on cognitive function in SAH has not been investigated. The underlying mechanism of remyelination regulated by EA remains unclear. This study aimed to investigate the protective effects of EA on cognitive deficit in a rat model of SAH. SAH was induced in SD rats (n = 72) by endovascular perforation. Rats in EA group received EA treatment (10 min per day) under isoflurane anesthesia after SAH. Rats in SAH and sham groups received the same isoflurane anesthesia with no treatment. The mortality rate, neurological score, cognitive function, cerebral blood flow (CBF), and remyelination in sham, SAH and EA groups were assessed at 21 d after SAH.EA treatment alleviated cognitive deficits and myelin injury of rats compared with that in SAH group. Moreover, EA treatment enhanced remyelination in white matter and promoted the differentiation of OPCs after SAH. EA treatment inhibited the expression of Id2 and promoted the expression of SOX10 in oligodendrocyte cells. Additionally, the cerebral blood flow (CBF) of rats was increased by EA compared with that in SAH group. EA treatment exerts protective effect against cognitive deficit in the late phase of SAH. The underlying mechanisms involve promoting oligodendrocyte progenitor cell (OPC) differentiation and remyelination in white matter via regulating the expression of Id2 and SOX10. The improvement of CBF may also account for the protective effect of EA on cognitive function. EA treatment is a potential therapy for the treatment of cognitive deficit after SAH.

Fluid metabolic pathways after subarachnoid hemorrhage.

Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating cerebrovascular disease with high mortality and morbidity. In recent years, a large number of studies have focused on the mechanism of early brain injury (EBI) and delayed cerebral ischemia (DCI), including vasospasm, neurotoxicity of hematoma and neuroinflammatory storm, after aSAH. Despite considerable efforts, no novel drugs have significantly improved the prognosis of patients in phase III clinical trials, indicating the need to further re-examine the multifactorial pathophysiological process that occurs after aSAH. The complex pathogenesis is reflected by the destruction of the dynamic balance of the energy metabolism in the nervous system after aSAH, which prevents the maintenance of normal neural function. This review focuses on the fluid metabolic pathways of the central nervous system (CNS), starting with ruptured aneurysms, and discusses the dysfunction of blood circulation, cerebrospinal fluid (CSF) circulation and the glymphatic system during disease progression. It also proposes a hypothesis on the metabolic disorder mechanism and potential therapeutic targets for aSAH patients. Cover Image for this issue: https://doi.org/10.1111/jnc.15384.

High intracranial pressure may be the initial inducer of elevated plasma D-dimer level after aneurysmal subarachnoid haemorrhage.

Objective: The plasma D-dimer has been regarded as a poor prognosis factor in aneurysmal subarachnoid haemorrhage (aSAH) patients, but the reason of elevated D-dimer level has not been revealed. In this study, we retrospectively explored the potential clinical parameters which might be related to D-dimer level and further attempted to explain the pathological process of D-dimer level elevation in aSAH patients. Patients and methods: The qualified patients with aSAH were recruited and treated in Sichuan Provincial People's Hospital from 1 October 2015 to 28 February 2018. All clinical data were collected, the blood samples were gathered on admission and the levels of D-dimer were detected by the clinical laboratory. The χ2-test, univariate and multiple linear regression analysis were used to seek the relationship between clinical variables and D-dimer level.Results: Total 98 aSAH patients were enrolled. The χ2-test showed a significant difference in clinical characteristics of gender, hyperlipidaemia and ICP between the patients with normal D-dimer level and the others with a high D-dimer level (p < .05). The univariate linear regression analysis and the multiple linear regression analysis showed the combined CCT and ICP were still significantly related to D-dimer level (p < .05). Conclusion: Besides the other related factors, the increased ICP was obviously associated with the elevated plasma D-dimer level. It may indicate that the high ICP acted as the initial role, then led to poor perfusion, even induced the microthrombosis and activated the fibrinolytic system, which eventually contributed to D-dimer level increasing in aSAH patients.

Bexarotene protects against neurotoxicity partially through a PPARγ-dependent mechanism in mice following traumatic brain injury.

Traumatic brain injury (TBI) causes a high rate of mortality and disability worldwide, and there exists almost none effective drugs to protect against TBI. Neurotoxicity occurring after TBI can be derived from microglia and astrocytes, and causes neuronal death and synapse loss. Bexarotene has been demonstrated to protect neurons in CNS diseases. In the present study, we aimed to investigate the potential role of bexarotene in protecting against neurotoxicity after TBI, as well as the underlying mechanism. The controlled cortical impact (CCI) model was established on adult C57BL/6 mice, followed by intraperitoneal administration of bexarotene for 14 consecutive days. We found that bexarotene improved sensorimotor function and cognitive recovery in CCI mice. In addition, bexarotene decreased neuronal death and synapse loss, as well as inhibited apoptotic cascade. Moreover, bexarotene treatment reduced M1 microglia polarization, microglia-derived pro-inflammatory cytokines, and the number of A1 astrocytes after CCI. These effects of bexarotene were partially abolished by T0070907, an antagonist of peroxisome proliferator-activated receptor gamma (PPARγ). Additionally, bexarotene enhanced nuclear translocation and transcriptional activity of PPARγ. These findings show that bexarotene inhibits neurotoxicity in mice after TBI, at least in part through a PPARγ-dependent mechanism.

IRE1α inhibition decreased TXNIP/NLRP3 inflammasome activation through miR-17-5p after neonatal hypoxic-ischemic brain injury in rats.

BACKGROUND: The endoplasmic reticulum (ER) is responsible for the control of correct protein folding and protein function which is crucial for cell survival. However, under pathological conditions, such as hypoxia-ischemia (HI), there is an accumulation of unfolded proteins thereby triggering the unfolded protein response (UPR) and causing ER stress which is associated with activation of several stress sensor signaling pathways, one of them being the inositol requiring enzyme-1 alpha (IRE1α) signaling pathway. The UPR is regarded as a potential contributor to neuronal cell death and inflammation after HI. In the present study, we sought to investigate whether microRNA-17 (miR-17), a potential IRE1α ribonuclease (RNase) substrate, arbitrates downregulation of thioredoxin-interacting protein (TXNIP) and consequent NLRP3 inflammasome activation in the immature brain after HI injury and whether inhibition of IRE1α may attenuate inflammation via miR-17/TXNIP regulation. METHODS: Postnatal day 10 rat pups (n = 287) were subjected to unilateral carotid artery ligation followed by 2.5 h of hypoxia (8% O2). STF-083010, an IRE1α RNase inhibitor, was intranasally delivered at 1 h post-HI or followed by an additional one administration per day for 2 days. MiR-17-5p mimic or anti-miR-17-5p inhibitor was injected intracerebroventricularly at 48 h before HI. Infarct volume and body weight were used to evaluate the short-term effects while brain weight, gross and microscopic brain tissue morphologies, and neurobehavioral tests were conducted for the long-term evaluation. Western blots, immunofluorescence staining, reverse transcription quantitative real-time polymerase chain reaction (RT-qPCR), and co-immunoprecipitation (Co-IP) were used for mechanism studies. RESULTS: Endogenous phosphorylated IRE1α expression was significantly increased after HI. Intranasal administration of STF-083010 alleviated brain injury and improved neurological behavior. MiR-17-5p expression was reduced after HI, and this decrease was attenuated by STF-083010 treatment. MiR-17-5p mimic administration ameliorated TXNIP expression, NLRP3 inflammasome activation, caspase-1 cleavage, and IL-1ß production, as well as brain infarct volume. Conversely, anti-miR-17-5p inhibitor reversed IRE1α inhibition-induced decrease in TXNIP expression and inflammasome activation, as well as exacerbated brain injury after HI. CONCLUSIONS: IRE1a-induced UPR pathway may contribute to inflammatory activation and brain injury following neonatal HI. IRE1a activation, through decay of miR-17-5p, elevated TXNIP expression to activate NLRP3 inflammasome and aggravated brain damage.

Clinical and Basic Evaluation of the Prognostic Value of Uric Acid in Traumatic Brain Injury.

Background: As a major antioxidant in serum, uric acid (UA) was once considered only as the leading cause of gout; however, recent studies have validated its neuroprotective role in ischemic stroke. Because the potential protective effects of UA in traumatic brain injury (TBI) remain largely unknown, this study investigated the role of UA in TBI in both clinical patients and experimental animals. Methods: In TBI patients, serum UA concentrations were measured within 3 days after injury. Clinical outcomes at discharge were classified according to the Glasgow Outcome Scale: good outcome (4-5) and poor outcome (1-3). Risk factors for good outcome were identified via backward logistic regression analysis. For the animal study, a controlled cortical impact (CCI) injury model was established in mice. These mice were given UA at different doses intraperitoneally, and subsequent UA concentrations in mouse serum and brain tissue were determined. Neurological function, oxidative stress, inflammatory response, neuronal maintenance, cerebral blood flow, and lesion size were also assessed. Results: The serum UA level was significantly lower in TBI patients who had a good outcome (P<0.01), and low serum UA was an independent predictor of good outcome after TBI (P<0.01; odds ratio, 0.023; 95% confidence interval, 0.006-0.082). Consistently, decreased levels of serum UA were observed in both TBI patients and CCI animals (P<0.05), whereas the UA concentration was increased in CCI brain tissue (P<0.05). Administration of UA further increased the UA level in brain tissue as compared to that in control animals (P<0.05). Among the different doses administered, 16 mg/kg UA improved sensorimotor functional recovery, spatial learning, and memory in CCI mice (P<0.05). Moreover, oxidative stress and the inflammatory response were inhibited by UA treatment (P<0.05). UA treatment also improved neuronal maintenance and cortical blood flow (P<0.05) but not lesion size (P>0.05). Conclusions: UA acted to attenuate neuronal loss, cerebral perfusion impairment and neurological deficits in TBI mice through suppression of neuronal and vascular oxidative stress. Following TBI, active antioxidant defense in the brain may result in consumption of UA in the serum, and thus, a decreased serum UA level could be predictive of good clinical recovery.

Effect of premorbid hypertension control on outcome of patients with aneurysmal subarachnoid hemorrhage.

OBJECTIVE: Hypertension is common in patients with aneurysmal subarachnoid hemorrhage (SAH). However, it is still unclear whether premorbid antihypertensive therapy can help to reduce the risk of severe aneurysmal bleeding. Therefore, this study aims to assess the effect of premorbid hypertension control on outcome of patients with aneurysmal SAH. METHODS: We retrospectively reviewed the clinical data of patients with intracranial aneurysms admitted to our institution from February 2012 to December 2017. Based on premorbid hypertension history and use of antihypertensive agents, all patients with aneurysmal SAH were divided into antihypertensive group and uncontrolled group. Patient characteristics, imaging features, clinical complication, and outcome were analyzed between the two groups. RESULTS: A total of 348 patients with ruptured aneurysms were included in this study. Compared to those with premorbid controlled hypertension, patients with premorbid uncontrolled hypertension presented worse clinical grade, with more severe aneurysmal SAH and more frequent intracerebral hematoma. Patients receiving a treatment for ACEI type or ARB type of drugs in the antihypertensive group suffered from less amount of aneurysmal bleeding, while patients with grade 3 hypertension in the uncontrolled group suffered from more amount of aneurysmal bleeding. Patients with premorbid controlled hypertension had a lower incidence of rebleeding, hydrocephalus, and cerebral vasospasm, and had a lower rate of disability and mortality. CONCLUSIONS: Premorbid hypertension control is associated with favorable clinical outcome of patients with aneurysmal SAH. Besides, the ACEI type or ARB type of antihypertensive agents is associated with the less amount of bleeding after aneurysm rupture.

Hyperbaric Oxygen Reduces Infarction Volume and Hemorrhagic Transformation Through ATP/NAD+/Sirt1 Pathway in Hyperglycemic Middle Cerebral Artery Occlusion Rats.

BACKGROUND AND PURPOSE: Energy depletion is a critical factor leading to cell death and brain dysfunction after ischemic stroke. In this study, we investigated whether energy depletion is involved in hyperglycemia-induced hemorrhagic transformation after ischemic stroke and determined the pathway underlying the beneficial effects of hyperbaric oxygen (HBO). METHODS: After 2-hour middle cerebral artery occlusion, hyperglycemia was induced by injecting 50% dextrose (6 mL/kg) intraperitoneally at the onset of reperfusion. Immediately after it, rats were exposed to HBO at 2 atmospheres absolutes for 1 hour. ATP synthase inhibitor oligomycin A, nicotinamide phosphoribosyl transferase inhibitor FK866, or silent mating type information regulation 2 homolog 1 siRNA was administrated for interventions. Infarct volume, hemorrhagic volume, and neurobehavioral deficits were recorded; the level of blood glucose, ATP, and nicotinamide adenine dinucleotide and the activity of nicotinamide phosphoribosyl transferase were monitored; the expression of silent mating type information regulation 2 homolog 1, acetylated p53, acetylated nuclear factor-κB, and cleaved caspase 3 were detected by Western blots; and the activity of matrix metalloproteinase-9 was assayed by zymography. RESULTS: Hyperglycemia deteriorated energy metabolism and reduced the level of ATP and nicotinamide adenine dinucleotide and exaggerated hemorrhagic transformation, blood-brain barrier disruption, and neurological deficits after middle cerebral artery occlusion. HBO treatment increased the levels of the ATP and nicotinamide adenine dinucleotide and consequently increased silent mating type information regulation 2 homolog 1, resulting in attenuation of hemorrhagic transformation, brain infarction, as well as improvement of neurological function in hyperglycemic middle cerebral artery occlusion rats. CONCLUSIONS: HBO induced activation of ATP/nicotinamide adenine dinucleotide/silent mating type information regulation 2 homolog 1 pathway and protected blood-brain barrier in hyperglycemic middle cerebral artery occlusion rats. HBO might be promising approach for treatment of acute ischemic stroke patients, especially patients with diabetes mellitus or treated with r-tPA (recombinant tissue-type plasminogen activator).

DLK silencing attenuated neuron apoptosis through JIP3/MA2K7/JNK pathway in early brain injury after SAH in rats.

OBJECTIVE: Dual leucine zipper kinase (DLK/MA3K12) has been reported involved in apoptosis and neuronal degeneration during neural development and traumatic brain injury. This study was designed to investigate the role of DLK with its adaptor protein JNK interacting protein-3 (JIP3), and its downstream MA2K7/JNK signaling pathway in early brain injury (EBI) after subarachnoid hemorrhage (SAH) in a rat model. DESIGN: Controlled in vivo laboratory study. SETTING: Animal research laboratory. SUBJECTS: Two hundred and twenty-three adult male Sprague-Dawley rats weighing 280-320g. INTERVENTIONS: SAH was induced by endovascular perforation in rats. The SAH grade, neurological score, and brain water content were measured at 24 and 72h after SAH. Immunofluorescence staining was used to detect the cells that expressed DLK. The terminal deoxynucleotid transferase-deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL) was used to detect the neuronal apoptosis. In mechanism research, the expression of DLK, JIP3, phosphorylated-JNK (p-JNK)/JNK, and cleaved caspase-3 (CC-3) were analyzed by western blot at 24h after SAH. The DLK small interfering RNA (siRNA), JIP3 siRNA, MA2K7 siRNA and recombinant DLK protein which injected intracerebroventricularly were given as the interventions. MEASUREMENTS AND MAIN RESULTS: The DLK expression was increased in the left cortex neurons and peaked at 24h after SAH. DLK siRNA attenuated brain edema, reduced neuronal apoptosis, and improved the neurobehavioral functions after SAH, but the recombinant DLK protein deteriorated neurobehavioral functions and brain edema. DLK siRNA decreased and recombinant DLK protein increased the expression of MA2K7/p-JNK/CC-3 at 24h after SAH. The JIP3 siRNA reduced the level of JIP3/MA2K7/p-JNK/CC-3, combined DLK siRNA and JIP3 siRNA further decreased the expression of DLK/MA2K7/p-JNK/CC-3, and MA2K7 siRNA lowered the amount of MA2K7/p-JNK/CC-3 at 24h after SAH. CONCLUSIONS: As a negative role, DLK was involved in EBI after SAH, possibly mediated by its adaptor protein JIP3 and MA2K7/JNK signaling pathways. To reduce the level of DLK may be a new target as intervention for SAH.

Peroxisome Proliferator-Activated Receptor ß/δ Alleviates Early Brain Injury After Subarachnoid Hemorrhage in Rats.

BACKGROUND AND PURPOSE: Early brain injury is proposed to be the primary cause of the poor outcome after subarachnoid hemorrhage (SAH), which is closely related to the neural apoptosis. To date, the relationship between peroxisome proliferator-activated receptor ß/δ (PPARß/δ) and nuclear factor-κB/matrix metalloproteinase-9 (NF-κB/MMP-9) pathway, both of which are closely related to apoptotic effects, has been poorly studied in SAH. The present study was undertaken to evaluate the effects of PPARß/δ on early brain injury and NF-κB/MMP-9 pathway after SAH in rats. METHODS: SAH model was established by injecting nonheparinized autologous arterial blood into the prechiasmatic cistern in male Sprague-Dawley rats. Adenoviruses or small interfering RNAs were injected into the right lateral cerebral ventricle to, respectively, up- or downregulate PPARß/δ expression before SAH. All animals were assessed with a neurological score and then killed at 24 hours after SAH surgery. The indexes of brain water content, blood-brain barrier permeability, and apoptosis were used to detect brain injury. The expression of PPARß/δ, NF-κB, and MMP-9 were measured by immunohistochemistry, gelatin zymography, and Western Blot methods, respectively. In addition, GW0742, a specific agonist of PPARß/δ, was used to treat SAH in rats, the effects of which were evaluated by neurological scoring and Evans blue extravasation. RESULTS: Overexpression of PPARß/δ by adenoviruses treatment significantly ameliorated brain injury with improvement in neurological deficits, brain edema, blood-brain barrier impairment, and neural cell apoptosis at 24 hours after SAH in rats, whereas downregulation of PPARß/δ by small interfering RNAs administration resulted in the reverse effects of the above. The expression levels of NF-κB and MMP-9 were markedly downregulated when PPARß/δ increased after PPARß/δ adenovirus transfection and upregulated when PPARß/δ decreased by PPARß/δ small interfering RNAs treatment. Moreover, GW0742 improved neurological deficits and reduced Evans blue extravasation at 24 hours after SAH. CONCLUSIONS: PPARß/δ's overexpression may attenuate early brain injury after rats' SAH administration, which reduces neural apoptosis possibly through blocking NF-κB/MMP-9 pathway.

Lipoxin A4 Reduces Inflammation Through Formyl Peptide Receptor 2/p38 MAPK Signaling Pathway in Subarachnoid Hemorrhage Rats.

BACKGROUND AND PURPOSE: Lipoxin A4 (LXA4) has been reported to reduce inflammation in several neurological injury models. We studied the effects of LXA4 on neuroinflammation after subarachnoid hemorrhage (SAH) in a rat model. METHODS: Two hundred and thirty-eight Sprague-Dawley male rats, weight 280-320 g, were used. Exogenous LXA4 (0.3 and 1.0 nmol) were injected intracerebroventricularly at 1.5 hours after SAH. Neurological scores, brain water content, and blood-brain barrier were evaluated at 24 hours after SAH; Morris water maze and T-maze tests were examined at 21 days after SAH. The expression of endogenous LXA4 and its receptor formyl peptide receptor 2 (FPR2), as well as p38, interleukin-1ß, and interleukin-6 were studied either by ELISA or by Western blots. Neutrophil infiltration was observed by myeloperoxidase staining. FPR2 siRNA was used to knock down LXA4 receptor. RESULTS: The expression of endogenous LXA4 decreased, and the expression of FPR2 increased after SAH. Exogenous LXA4 decreased brain water content, reduced Evans blue extravasation, and improved neurological functions and improved the learning and memory ability after SAH. LXA4 reduced neutrophil infiltration and phosphorylation of p38, interleukin-1ß, and interleukin-6. These effects of LXA4 were abolished by FPR2 siRNA. CONCLUSIONS: Exogenous LXA4 inhibited inflammation by activating FPR2 and inhibiting p38 after SAH. LXA4 may serve as an alternative treatment to relieve early brain injury after SAH.

Intraventricular apolipoprotein ApoJ infusion acts protectively in Traumatic Brain Injury.

Traumatic brain injury (TBI) is the leading cause of mortality and morbidity in youth, but to date, effective therapies are still lacking. Previous studies revealed a marked response of apolipoprotein J (ApoJ) expression to the brain injury. The aim of this study was to determine the potential roles of ApoJ in functional recovery following TBI. After controlled cortex impact (CCI), a TBI model, in adult wild-type mice, ApoJ expression was up-regulated since 6 h post-injury and sustained for 5 days. Animals infused with recombinant human ApoJ intraventricularly at 30 min prior to CCI showed significantly reduced oxidative stress (3-nitrotyrosine, 4-hydroxynonenal) and complement activation (C5b-9). In addition, ApoJ treatment was shown to suppress the inflammatory response (glial activation, cytokine expression), blood-brain barrier disruption (Evans blue extravasation), and cerebral edema (water content) induced by CCI. Concomitantly, improved neuronal maintenance and neurological behavioral performance were observed in ApoJ-treated mice compared with the vehicle group. These findings support a neuroprotective role of ApoJ via multifunctional pathways, providing a novel and encouraging treatment strategy for TBI. Apolipoprotein J (ApoJ) was up-regulated after controlled cortical impact (CCI). Mice infused with human recombinant ApoJ prior to CCI showed reduced expression of complement and oxidative marker proteins as well as reduced inflammatory response and attenuated blood-brain barrier (BBB) disruption and cerebral edema. Neuronal maintenance and behavioral performance were improved by ApoJ infusion. These findings demonstrated the protective function of ApoJ for traumatic brain injury (TBI) therapy.

Hyperbaric Oxygen Preconditioning Attenuates Hemorrhagic Transformation Through Reactive Oxygen Species/Thioredoxin-Interacting Protein/Nod-Like Receptor Protein 3 Pathway in Hyperglycemic Middle Cerebral Artery Occlusion Rats.

OBJECTIVES: To clarify whether hyperbaric oxygen preconditioning can attenuate hyperglycemia-enhanced hemorrhagic transformation and to establish a role for Nod-like receptor protein 3 inflammasome in the pathophysiology of hemorrhagic transformation. DESIGN: Controlled prospective animal study. SETTING: University research laboratory. SUBJECTS: Male Sprague-Dawley rats weighing 260-280 g. INTERVENTIONS: Rats received 1-hour-long hyperbaric oxygen preconditioning for five consecutive days. Hyperglycemic middle cerebral artery occlusion model was induced at 24 hours after the last hyperbaric oxygen exposure. Reactive oxygen species scavenger (N-acetyl-L-cysteine), thioredoxin-interacting protein small interfering RNA, and Nod-like receptor protein 3 small interfering RNA were given in different groups separately to verify the possible pathway. MEASUREMENTS AND MAIN RESULTS: Rats were randomly divided into sham, middle cerebral artery occlusion, middle cerebral artery occlusion + dextrose, middle cerebral artery occlusion + dextrose + normobaric oxygen preconditioning, middle cerebral artery occlusion + dextrose + hyperbaric oxygen, middle cerebral artery occlusion + dextrose + hyperbaric oxygen + N-acetyl-L-cysteine, middle cerebral artery occlusion + dextrose + hyperbaric oxygen + control small interfering RNA, middle cerebral artery occlusion + dextrose + hyperbaric oxygen + thioredoxin-interacting protein small interfering RNA, and middle cerebral artery occlusion + dextrose + hyperbaric oxygen + Nod-like receptor protein 3 small interfering RNA groups. Hyperglycemia was induced by administration of 50% dextrose (6 mL/kg) intraperitoneally 30 minutes before middle cerebral artery occlusion. Control small interfering RNA/thioredoxin-interacting protein small interfering RNA or Nod-like receptor protein 3 small interfering RNA (500 pmol/5 µL) were injected intracerebroventricularly 72 hours before middle cerebral artery occlusion for intervention. The neurologic scores, infarction and hemorrhage volumes, the expression of Nod-like receptor protein 3, and its downstream targets were analyzed. Hyperbaric oxygen preconditioning decreased both infarction and hemorrhage volumes and improved neurobehavioral function. In addition, hyperbaric oxygen preconditioning provided additional protective effects in hemorrhagic transformation, which was independent of infarction volume. The benefits of hyperbaric oxygen preconditioning on hyperglycemic middle cerebral artery occlusion rats were reversed after blocking the reactive oxygen species/thioredoxin-interacting protein/Nod-like receptor protein 3 pathway. CONCLUSIONS: Nod-like receptor protein 3 inflammasome played an important role in hyperglycemia-enhanced hemorrhagic transformation. Hyperbaric oxygen preconditioning attenuated hemorrhagic transformation through reactive oxygen species/thioredoxin-interacting protein/Nod-like receptor protein 3 pathway.

Macrophage-Inducible C-Type Lectin/Spleen Tyrosine Kinase Signaling Pathway Contributes to Neuroinflammation After Subarachnoid Hemorrhage in Rats.

BACKGROUND AND PURPOSE: Macrophage-inducible C-type lectin (Mincle, CLEC4E) receptor is reported involved in neuroinflammation in cerebral ischemia and traumatic brain injury. This study was designed to investigate the role of Mincle and its downstream spleen tyrosine kinase (Syk) signal pathway in early brain injury after subarachnoid hemorrhage (SAH) in a rat model. METHODS: Two hundred fifteen male Sprague-Dawley rats (280-320 g) were subjected to endovascular perforation model of SAH. SAH grade, neurological score, and brain water content were measured at 24 hours after SAH. Mincle/Syk, as well as CARD9 (a member of the caspase-associated recruitment domain [CARD], involved in innate immune response), interleukin-1ß,and myeloperoxidase expressions were analyzed by Western blot at 24 hours after SAH. Specific cell types that expressed Mincle were detected with double immunofluorescence staining. Mincle small interfering RNA, recombinant SAP130, and a selective Syk phosphorylation inhibitor piceatannol were used for intervention. RESULTS: Brain water content increased and neurological functions decreased in rats after SAH. The expression of SAP130, Mincle, Syk, and p-Syk increased at 12 hours and peaked at 24 hours after SAH. Mincle small interfering RNA reduced interleukin-1ß and infiltration of myeloperoxidase positive cells, decreased brain water content, and improved neurological functions at 24 hours after SAH. Recombinant SAP130 upregulated the expression of p-Syk and CARD9 and increased the levels of interleukin-1ß and myeloperoxidase, even though it did not increase brain water content nor it deteriorated neurological function at 24 hours after SAH. Syk inhibitor piceatannol reduced brain edema at 24 hours after SAH. CONCLUSION: Mincle/Syk is involved in early brain injury after SAH, and they may serve as new targets for therapeutic intervention.

MMP-9 expression and activity is concurrent with endothelial cell apoptosis in the basilar artery after subarachnoid hemorrhaging in rats.

Subarachnoid hemorrhage refers to one kind of lethal stroke. While several studies have shown the role of matrix metalloproteinase 9 in cerebral tissues and microvasculature after subarachnoid hemorrhage the role of matrix metalloproteinase 9 in large cerebral vasculature is limited, The present study aimed at investigating the relationship between the expression and activity of matrix metalloproteinase 9 and vascular endothelial cell apoptosis in the basilar artery at early-stage post-subarachnoid hemorrhaging in rats. The expression and activity of matrix metalloproteinase 9 in the basilar artery increased at 12 h after subarachnoid hemorrhage and peaked at 24 h. Concurrently, the number of apoptotic cells in the basilar artery increased at 12 h and peaked at 24 h following subarachnoid hemorrhage. Additionally, laminin and cleaved caspase 3 reached to their lowest and highest levels at 24 h after subarachnoid hemorrhage, respectively. Our results suggested that the change in expression and activity of matrix metalloproteinase 9 paralleled that of apoptotic cells in the basilar artery following subarachnoid hemorrhage. Matrix metalloproteinase 9 may be contributing to the injury of the basilar artery after subarachnoid hemorrhage via laminin degradation. Although the underlying mechanisms need to be explored further, our study has shown a potential association of matrix metalloproteinase 9 with injury of the basilar artery and can be associated with early-stage brain injury following subarachnoid hemorrhage.

Recombinant milk fat globule-EGF factor-8 reduces oxidative stress via integrin ß3/nuclear factor erythroid 2-related factor 2/heme oxygenase pathway in subarachnoid hemorrhage rats.

BACKGROUND AND PURPOSE: Milk fat globule-EGF factor-8 (MFGE8) has been reported to be neuroprotective in ischemic stroke. However, the effects of MFGE8 in early brain injury after subarachnoid hemorrhage (SAH) have not been investigated. We investigated the role of MFGE8 in early brain injury and the potential mechanisms in antioxidation after SAH. METHODS: Two dosages (1 µg and 3.3 µg) of recombinant human MFGE8 were injected intracerebroventricularly at 1.5 hours after SAH. SAH grades, neurological scores, and brain water content were measured at 24 and 72 hours. For mechanistic study, MFGE8 siRNA, integrin ß3 siRNA, and heme oxygenase (HO) inhibitor SnPP IX were used for intervention. The oxidative stress and expression of MFGE8, integrin ß3, HO-1, extracellular signal-regulated kinase, and nuclear factor erythroid 2-related factor 2 were measured by Western blots 24 hours after SAH. RESULTS: The expression of MFGE8 and HO-1 increased and peaked 24 hours after SAH. Administration of recombinant human MFGE8 decreased brain water content and improved neurological functions both at 24 hours and at 72 hours after SAH. Recombinant human MFGE8 reduced oxidative stress and enhanced the expression of extracellular signal-regulated kinase, nuclear factor erythroid 2-related factor 2, and HO-1; and the effects were abolished by integrin ß3 siRNA and HO inhibitor SnPP IX. CONCLUSIONS: Recombinant MFGE8 attenuated oxidative stress that may be mediated by integrin ß3/nuclear factor erythroid 2-related factor 2/HO pathway after SAH. Recombinant MFGE8 may serve as an alternative treatment to ameliorate early brain injury for SAH patients.

Remote Ischemic Post-conditioning Reduces Cognitive Impairment in Rats Following Subarachnoid Hemorrhage: Possible Involvement in STAT3/STAT5 Phosphorylation and Th17/Treg Cell Homeostasis.

The inflammatory response following subarachnoid hemorrhage (SAH) may lead to Early Brain Injury and subsequently contribute to poor prognosis such as cognitive impairment in patients. Currently, there is a lack of effective strategies for SAH to ameliorate inflammation and improve cognitive impairment in clinical. This study aims to examine the inhibitory impact of remote ischemic post-conditioning (RIPostC) on the body's inflammatory response by regulating Th17/Treg cell homeostasis after SAH. The ultimate goal is to search for potential early treatment targets for SAH. The rat SAH models were made by intravascular puncture of the internal carotid artery. The intervention of RIPostC was administered for three consecutive days immediately after successful modeling. Behavioral experiments including the Morris water maze and Y-maze tests were conducted to assess cognitive functions such as spatial memory, working memory, and learning abilities 2 weeks after successful modeling. The ratio of Th17 cells and Treg cells in the blood was detected using flow cytometry. Immunofluorescence was used to observe the infiltration of neutrophils into the brain. Signal transducers and activators of transcription 5 (STAT5) and signal transducers and activators of transcription 3 (STAT3) phosphorylation levels, receptor-related orphan receptor gamma-t (RORγt), and forkhead box protein P3 (Foxp3) levels were detected by Western blot. The levels of anti-inflammatory factors (IL-2, IL-10, IL-5, etc.) and pro-inflammatory factors (IL-6, IL-17, IL-18, TNF-α, IL-14, etc.) in blood were detected using Luminex Liquid Suspension Chip Assay. RIPostC significantly improved the cognitive impairment caused by SAH in rats. The results showed that infiltration of Th17 cells and neutrophils into brain tissue increased after SAH, leading to the release of pro-inflammatory factors (IL-6, IL-17, IL-18, and TNF-α). This response can be inhibited by RIPostC. Additionally, RIPostC facilitates the transfer of Treg from blood to the brain and triggers the release of anti-inflammatory (IL-2, IL-10, and IL-5) factors to suppress the inflammation following SAH. Finally, it was found that RIPostC increased the phosphorylation of STAT5 while decreasing the phosphorylation of STAT3. RIPostC reduces inflammation after SAH by partially balancing Th17/Treg cell homeostasis, which may be related to downregulation of STAT3 and upregulation of STAT5 phosphorylation, which ultimately alleviates cognitive impairment in rats. Targeting Th17/Treg cell homeostasis may be a promising strategy for early SAH treatment.

Electroacupuncture enhances cerebral blood perfusion by inhibiting HIF-1α in rat subarachnoid hemorrhage.

OBJECTIVE: Cerebral blood perfusion (CBP) reduction is a prevalent complication following subarachnoid hemorrhage (SAH) in clinical practice, often associated with long-term cognitive impairment and prognosis. Electroacupuncture (EA), a widely utilized traditional Chinese therapy for central nervous system disorders, has demonstrated promising therapeutic effects. This study aims to investigate the therapeutic potential of EA in restoring CBP in SAH rats and to explore the mechanisms involving HIF-1α in this process. METHODS: Rats were randomly assigned to one of five groups, including Sham, SAH, EA, EA + Saline, and EA + dimethyloxallyl glycine (DMOG) groups. EA treatment was administered for 10 min daily, while DMOG were intraperitoneally injected. Behavioral tests, cerebral blood flow monitoring, vascular thickness measurement, western blotting, and immunofluorescence staining were conducted to assess the therapeutic effects of EA on cerebral blood flow. RESULTS: SAH resulted in elevated levels of HIF-1α, endothelin (ET), ICAM-1, P-SELECTIN, E-SELECTIN, and decreased level of eNOS in the brain. This led to cerebral vasospasm, decreased CBF, and cognitive deficits in the rat SAH model. EA intervention downregulated the expression of HIF-1α, ET, ICAM-1, P-SELECTIN, and E-SELECTIN, while increasing eNOS expression. This alleviated cerebral vasospasm, restored CBF, and improved cognitive function. However, the administration of the HIF-1α stabilizer (DMOG) counteracted the therapeutic effects of EA. CONCLUSION: EA promotes the recovery of cerebral blood flow after SAH injury, attenuates cerebral vasospasm, and accelerates the recovery of cognitive dysfunction, and its mechanism of action may be related to the inhibition of the HIF-1α signaling pathway.

The potential mechanism and clinical application value of remote ischemic conditioning in stroke.

ABSTRACT: Some studies have confirmed the neuroprotective effect of remote ischemic conditioning against stroke. Although numerous animal researches have shown that the neuroprotective effect of remote ischemic conditioning may be related to neuroinflammation, cellular immunity, apoptosis, and autophagy, the exact underlying molecular mechanisms are unclear. This review summarizes the current status of different types of remote ischemic conditioning methods in animal and clinical studies and analyzes their commonalities and differences in neuroprotective mechanisms and signaling pathways. Remote ischemic conditioning has emerged as a potential therapeutic approach for improving stroke-induced brain injury owing to its simplicity, non-invasiveness, safety, and patient tolerability. Different forms of remote ischemic conditioning exhibit distinct intervention patterns, timing, and application range. Mechanistically, remote ischemic conditioning can exert neuroprotective effects by activating the Notch1/phosphatidylinositol 3-kinase/ Akt signaling pathway, improving cerebral perfusion, suppressing neuroinflammation, inhibiting cell apoptosis, activating autophagy, and promoting neural regeneration. While remote ischemic conditioning has shown potential in improving stroke outcomes, its full clinical translation has not yet been achieved.