AXL kinase-mediated astrocytic phagocytosis modulates outcomes of traumatic brain injury.

BACKGROUND: Complex changes in the brain microenvironment following traumatic brain injury (TBI) can cause neurological impairments for which there are few efficacious therapeutic interventions. The reactivity of astrocytes is one of the keys to microenvironmental changes, such as neuroinflammation, but its role and the molecular mechanisms that underpin it remain unclear. METHODS: Male C57BL/6J mice were subjected to the controlled cortical impact (CCI) to develop a TBI model. The specific ligand of AXL receptor tyrosine kinase (AXL), recombinant mouse growth arrest-specific 6 (rmGas6) was intracerebroventricularly administered, and selective AXL antagonist R428 was intraperitoneally applied at 30 min post-modeling separately. Post-TBI assessments included neurobehavioral assessments, transmission electron microscopy, immunohistochemistry, and western blotting. Real-time polymerase chain reaction (RT-PCR), siRNA transfection, and flow cytometry were performed for mechanism assessments in primary cultured astrocytes. RESULTS: AXL is upregulated mainly in astrocytes after TBI and promotes astrocytes switching to a phenotype that exhibits the capability of ingesting degenerated neurons or debris. As a result, this astrocytic transformation promotes the limitation of neuroinflammation and recovery of neurological dysfunction. Pharmacological inhibition of AXL in astrocytes significantly decreased astrocytic phagocytosis both in vivo and in primary astrocyte cultures, in contrast to the effect of treatment with the rmGas6. AXL activates the signal transducer and activator of the transcription 1 (STAT1) pathway thereby further upregulating ATP-binding cassette transporter 1 (ABCA1). Moreover, the supernatant from GAS6-depleted BV2 cells induced limited enhancement of astrocytic phagocytosis in vitro. CONCLUSION: Our work establishes the role of AXL in the transformation of astrocytes to a phagocytic phenotype via the AXL/STAT1/ABCA1 pathway which contributes to the separation of healthy brain tissue from injury-induced cell debris, further ameliorating neuroinflammation and neurological impairments after TBI. Collectively, our findings provide a potential therapeutic target for TBI.

Comparison of Operative and Conservative Treatment for Asymptomatic Moyamoya Disease: Preliminary Experience in Small Retrospective Series.

OBJECTIVE: The best management of asymptomatic moyamoya disease (MMD) remains controversial. In this study, the authors aimed to explore an experience for treatment modality for asymptomatic MMD. METHODS: The authors retrospectively reviewed a total of 23 patients (age range 30-58 years) with asymptomatic MMD during the past 5 years at their institutions. The patients were divided into 2 groups: The surgical group included 11 patients, and the conservative group included 12 patients. The demographic, radiologic, and clinical findings of the patients were evaluated. At follow-up over 13-65 months, the future clinical and radiologic progression events were evaluated. RESULTS: During the follow-up period, 3 patients suffered from future clinical progression events in the conservative group: 1 experienced stroke, and 2 experienced transient ischemic attack. Among the patients in the surgical group, only 1 experienced transient ischemic attack. Kaplan-Meier analysis showed that patients undergoing surgeries had longer clinical progression-free survival times compared with patients in the conservative group (P = 0.002). CONCLUSIONS: Surgical treatment may be an alternative choice for patients with asymptomatic MMD. However, the best strategy for asymptomatic MMD in order to reduce future cerebrovascular risks still needs to be further explored.

Stimulator of IFN genes mediates neuroinflammatory injury by suppressing AMPK signal in experimental subarachnoid hemorrhage.

BACKGROUND: Neuroinflammation is closely associated with the poor prognosis in subarachnoid hemorrhage (SAH) patients. This study was aimed to determine the role of stimulator of IFN genes (STING), an essential regulator to innate immunity, in the context of SAH. METHODS: A total of 344 male C57BL/6 J mice were subjected to endovascular perforation to develop a model of SAH. Selective STING antagonist C-176 and STING agonist CMA were administered at 30 min or 1 h post-modeling separately. To investigate the underlying mechanism, the AMPK inhibitor compound C was administered intracerebroventricularly at 30 min before surgery. Post-SAH assessments included SAH grade, neurological test, brain water content, western blotting, RT-PCR, and immunofluorescence. Oxygenated hemoglobin was introduced into BV2 cells to establish a SAH model in vitro. RESULTS: STING was mainly distributed in microglia, and microglial STING expression was significantly increased after SAH. Administration of C-176 substantially attenuated SAH-induced brain edema and neuronal injury. More importantly, C-176 significantly alleviated both short-term and persistent neurological dysfunction after SAH. Meanwhile, STING agonist CMA remarkably exacerbated neuronal injury and deteriorated neurological impairments. Mechanically, STING activation aggravated neuroinflammation via promoting microglial activation and polarizing into M1 phenotype, evidenced by microglial morphological changes, as well as the increased level of microglial M1 markers including IL-1ß, iNOS, IL-6, TNF-α, MCP-1, and NLRP3 inflammasome, while C-176 conferred a robust anti-inflammatory effect. However, all the mentioned beneficial effects of C-176 including alleviated neuroinflammation, attenuated neuronal injury and the improved neurological function were reversed by AMPK inhibitor compound C. Meanwhile, the critical role of AMPK signal in C-176 mediated anti-inflammatory effect was also confirmed in vitro. CONCLUSION: Microglial STING yielded neuroinflammation after SAH, while pharmacologic inhibition of STING could attenuate SAH-induced inflammatory injury at least partly by activating AMPK signal. These data supported the notion that STING might be a potential therapeutic target for SAH.

Retrospective analysis of brain abscess in 183 patients: A 10-year survey.

This study aims to identify predictive factors related to clinical outcome, reoperation, and complications in patients with brain abscess.Patients with a diagnosis of brain abscess at discharge at the Second Affiliated Hospital of Zhejiang University School of Medicine between 2008 and 2018 were reviewed. Logistic regression was used to identify predictive factors associated with Glasgow Outcome Scale (GOS) at discharge, GOS at 1 year after discharge, reoperation and complications.Among 183 patients enrolled into the study, 142 patients had a good outcome at discharge (GOS ≥ 4) and 41 had a poor outcome (GOS ≤ 3). During the follow-up period, 20 additional patients had a good outcome. A total of 156 patients were treated by open craniotomy excision (n = 72) and aspiration (n = 84), 10 of whom underwent reoperation. Complications in surgical patients for brain abscess occurred in 54 patients. Poor outcome was related to Glasgow coma scale (P = .007) and ventricular proximity (P = .001). Surgical method was associated with reoperation (P = .04) and complications (P < .001). Seizure at admission was related to epilepsy (P < .001). Surgical method was related to postoperative intracranial hemorrhage (P = .02).Glasgow coma scale (GCS) and ventricular proximity were associated with poor outcome. Further, patients who underwent aspiration were more likely to experience reoperation, while open craniotomy excision (OCE) was related to complications. Patients presenting seizure at admission were more likely to develop epilepsy. Patients who underwent OCE tended to experience postoperative intracranial hemorrhage.

Mesencephalic astrocyte-derived neurotrophic factor affords neuroprotection to early brain injury induced by subarachnoid hemorrhage via activating Akt-dependent prosurvival pathway and defending blood-brain barrier integrity.

This study aimed to explore the neuroprotective effect of mesencephalic astrocyte-derived neurotrophic factor (MANF) protein on early brain injury caused by subarachnoid hemorrhage (SAH) and the relevant mechanisms in experimental rats, expecting to understand whether MANF was a potential therapeutic target for SAH treatment. A perforation model of SAH was introduced into the study. Recombinant human MANF (rh-MANF) and protein kinase B (Akt) inhibitor (MK2206) were used to explore the effect and the mechanisms. Multiple approaches for systemic assessment were employed in the research, including the Garcia test, the SAH grade, Evans blue (EB) dye leakage, brain-water content (BWC), the rotarod test, and the Morris water-navigation task, as were biotechniques, such as immunohistochemistry, Western blot, transmission electron microscopy, and flow cytometry. MANF was mainly expressed in rat neurons, and its expression increased significantly at 3 h after SAH induction and peaked at 24 h. Stereotactic injection of rh-MANF into the cerebroventricle significantly increased the level of MANF, p-Akt, p-mouse double minute 2 homolog (p-MDM2), and B-cell lymphoma 2 (Bcl-2) in brain tissue, whereas it down-regulated the expression of P53, Bcl-2-associated X protein (Bax), and cleaved caspase-3, which indicated that neuronal apoptosis was remarkably suppressed. Expression of matrix metallopeptidase 9 (MMP-9) was also suppressed by the rh-MANF injection. Furthermore, neurologic deficits, EB dye leakage, and BWC were reduced, and long-lasting neuroprotection was noted with rh-MANF administration. The antiapoptotic and blood-brain barrier (BBB) protective effect could be offset by administering MK2206. MANF could alleviate neuronal apoptosis by activating Akt-dependent prosurvival pathway and abate BBB damage via MMP-9 suppression. MANF showed not only transient but also long-lasting neuroprotective properties. The rh-MANF as a potential drug for treating SAH might be of clinical use.-Li, T., Xu, W., Gao, L., Guan, G., Zhang, Z., He, P., Xu, H., Fan, L., Yan, F., Chen, G. Mesencephalic astrocyte-derived neurotrophic factor affords neuroprotection to early brain injury induced by subarachnoid hemorrhage via activating Akt-dependent prosurvival pathway and defending blood-brain barrier integrity.

Neuroprotective Effects of Magnesium Lithospermate B against Subarachnoid Hemorrhage in Rats.

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease with few effective pharmacotherapies available. Salvia miltiorrhiza, a traditional Chinese medicinal herb, has been widely used to treat cardiovascular diseases for centuries. Recent studies have demonstrated that magnesium lithospermate B (MLB), a bioactive ingredient extracted from Salvia miltiorrhiza, exerts neuroprotective effects in several central nervous system insults. However, little is known about the role of MLB in SAH-induced brain injury and the exact molecular mechanism. In the current study, we studied the neuroprotective effects of MLB in SAH and explored the potential mechanism. Adult male Sprague-Dawley rats were subjected to an endovascular perforation process to produce an SAH model. MLB was administrated intraperitoneally at 30[Formula: see text]min after SAH with a dose of 25[Formula: see text]mg/kg or 50[Formula: see text]mg/kg. We found that administration of MLB significantly attenuated brain edema and neurological deficits after SAH. In addition, immunofluorescence staining demonstrated that MLB dose-dependently inhibited the activation of microglia and reduced neuronal apoptosis. Western blot analysis showed that MLB decreased the expression of inflammatory cytokine TNF-[Formula: see text] and pro-apoptotic protein cleaved caspase-3. More importantly, MLB increased the expression of SIRT1, while inhibited the acetylation of NF-[Formula: see text]B. Furthermore, pretreatment with sirtinol (a selective inhibitor of SIRT1) reversed all the aforementioned effects of MLB after SAH. In conclusion, our results indicated that MLB exerted robust neuroprotective effects against SAH via suppressing neuroinflammation and apoptosis. These neuroprotective effects of MLB against SAH might be exerted via regulating the SIRT1/NF-[Formula: see text]B pathway. MLB or the SIRT1/NF-[Formula: see text]B pathway could be a novel and promising therapeutic strategy for SAH management.

Phosphodiesterase-4 inhibition confers a neuroprotective efficacy against early brain injury following experimental subarachnoid hemorrhage in rats by attenuating neuronal apoptosis through the SIRT1/Akt pathway.

Phosphodiesterase-4 (PDE4) plays a fundamental role in a range of central nervous system (CNS) insults, however, the role of PDE4 in early brain injury (EBI) after subarachnoid hemorrhage (SAH) remains unclear. The current study was designed to investigate the role of PDE4 in EBI after SAH and explore the potential mechanism. The SAH model in Sprague-Dawley rat was established by endovascular perforation process. Rats were randomly divided into: sham group, SAH?+?vehicle group, SAH?+?rolipram (PDE4 inhibitor) group, SAH?+?rolipram?+?sirtinol (SIRT1 inhibitor) group and SAH?+?rolipram+MK2206 (Akt inhibitor) group. Mortality, SAH grades, neurological function, brain edema, immunofluorescence staining and western blotting were performed. Double fluorescence labeling staining indicated that PDE4 was located predominately in neurons after SAH. Rolipram reduced brain edema, improved neurological function in the rat model of SAH. Moreover, rolipram increased the expression of Sirtuin1 (SIRT1) and up-regulated the phosphorylation of Akt, which was accompanied by the reduction of neuronal apoptosis. Administration of sirtinol inhibited the phosphorylation of Akt. Moreover, all the beneficial effects of rolipram against SAH were abolished by both sirtinol and MK2206. These data indicated that PDE4 inhibition by rolipram protected rats against EBI after SAH via suppressing neuronal apoptosis through the SIRT1/Akt pathway. Rolipram might be an important therapeutic drug for SAH.

Mdivi-1 ameliorates early brain injury after subarachnoid hemorrhage via the suppression of inflammation-related blood-brain barrier disruption and endoplasmic reticulum stress-based apoptosis.

Aberrant modulation of mitochondrial dynamic network, which shifts the balance of fusion and fission towards fission, is involved in brain damage of various neurodegenerative diseases including Parkinson's disease, Huntington's disease and Alzheimer's disease. A recent research has shown that the inhibition of mitochondrial fission alleviates early brain injury after experimental subarachnoid hemorrhage, however, the underlying molecular mechanisms have remained to be elucidated. This study was undertaken to characterize the effects of the inhibition of dynamin-related protein-1 (Drp1, a dominator of mitochondrial fission) on blood-brain barrier (BBB) disruption and neuronal apoptosis following SAH and the potential mechanisms. The endovascular perforation model of SAH was performed in adult male Sprague Dawley rats. The results indicated Mdivi-1(a selective Drp1 inhibitor) reversed the morphologic changes of mitochondria and Drp1 translocation, reduced ROS levels, ameliorated the BBB disruption and brain edema remarkably, decreased the expression of MMP-9 and prevented degradation of tight junction proteins-occludin, claudin-5 and ZO-1. Mdivi-1 administration also inhibited the nuclear translocation of nuclear factor-kappa B (NF-κB), leading to decreased expressions of TNF-ɑ, IL-6 and IL-1ß. Moreover, Mdivi-1 treatment attenuated neuronal cell death and improved neurological outcome. To investigate the underlying mechanisms further, we determined that Mdivi-1 reduced p-PERK, p-eIF2α, CHOP, cleaved caspase-3 and Bax expression as well as increased Bcl-2 expression. Rotenone (a selective inhibitor of mitochondrial complexes I) abolished both the anti-BBB disruption and anti-apoptosis effects of Mdivi-1. In conclusion, these data implied that excessive mitochondrial fission might inhibit mitochondrial complex I to become a cause of oxidative stress in SAH, and the inhibition of Drp1 by Mdivi-1 attenuated early brain injury after SAH probably via the suppression of inflammation-related blood-brain barrier disruption and endoplasmic reticulum stress-based apoptosis.

Methylene blue attenuates neuroinflammation after subarachnoid hemorrhage in rats through the Akt/GSK-3ß/MEF2D signaling pathway.

Subarachnoid hemorrhage (SAH) is a serious medical problem with few effective pharmacotherapies available, and neuroinflammation has been identified as an important pathological process in early brain injury (EBI) after SAH. Methylene blue (MB) is an older drug that has been recently proven to exert extraordinary neuroprotective effects in several brain insults. However, no study has reported the beneficial effects of MB in SAH. In the current investigation, we studied the neuroprotective effects of MB in EBI after SAH and focused on its anti-inflammatory role. A total of 303 rats were subjected to an endovascular perforation process to produce an SAH model. We found that MB could significantly ameliorate brain edema secondary to BBB disruption and alleviate neurological dysfunction after SAH. MB administration also promoted the phosphorylation of Akt and GSK-3ß, leading to an increased concentration of MEF2D in the nucleus. The cytokine IL-10 was up-regulated, and IL-1ß, IL-6 and TNF-α were down-regulated after MB administration. MB administration could also alleviate neutrophil infiltration and microglia activation after SAH. MK2206, a selective inhibitor of Akt, abolished the neuroprotective effects of MB, inhibited the phosphorylation of Akt and prevented the nuclear localization of MEF2D. MK2206 also reduced the expression of IL-10 and increased the expression of pro-inflammatory cytokines. In conclusion, these data suggested that MB could ameliorate neuroinflammatory responses after SAH, and its anti-inflammatory effects might be exerted via activation of the Akt/GSK-3ß/MEF2D pathway.

PARP inhibition attenuates early brain injury through NF-κB/MMP-9 pathway in a rat model of subarachnoid hemorrhage.

Poly (ADP-ribose) polymerases (PARPs) play an important role in a range of neurological disorders, however, the role of PARP in early brain injury after subarachnoid hemorrhage (SAH) remains unclear. This study was designed to explore the role and the potential mechanisms of PARP in early brain injury after SAH. Eighty-nine male SD rats were randomly divided into the Sham group, SAH+Vehicle group and SAH+PARP inhibitor (PJ34) group. An endovascular perforation model was used to induce SAH in rats. PJ34 (10mg/kg) or vehicle (0.9% NaCl) was intraperitoneally administered at 5min and 8h after SAH induction. Mortality, SAH grades, neurological function, evans blue extravasation, brain edema, immunofluorescence staining and western blotting were performed. PJ34 reduced BBB permeability and brain edema, improved neurological function and attenuated neuronal cell death in the rat model of SAH. Moreover, PJ34 inhibited the nuclear translocation of NF-κB, decreased the expression of the proinflammatory cytokines IL-1ß, IL-6 and TNF-α, reduced the expression of MMP-9, prevented the degradation of tight junction proteins, and decreased microglia activation. These data indicated that PARP inhibition through PJ34 might be an important therapeutic drug for SAH.