Carvacrol improves neurological function by inhibiting TRPM7-mediated BBB disruption and hemorrhage after TBI.

VSIG4 alleviates intracerebral hemorrhage induced brain injury by suppressing TLR4-regulated inflammatory response

Objectives: Ischemic stroke triggers a pattern of cellular and molecular disturbances that include lipid peroxidation, uncompensated oxidative stress, and neuronal injury. Recently, we have uncovered and characterized a novel neuroprotective signaling mechanism, which involves the activation of the biosynthesis of a family of lipid mediators in the brain made from omega-3 very-long-chain polyunsaturated fatty acids, that we named Elovanoids (ELVs). The present study evaluated ELVs, made of 32 and 34 C atoms in length (ELV-N32 and ELV-N34) and their potential mechanisms of action in cerebral ischemia. Methods: Male Sprague-Dawley rats were subjected to 2 h of middle cerebral artery occlusion (MCAo). Sodium salts (Na) or methyl esters (Me) ELVs were dissolved in artificial CSF and administered into right lateral ventricle at 3 h after onset of stroke. There were five groups: ELV-N32-Na, ELV-N32-Me, ELV-N34-Na, ELV-N34-Me (5μg/50μl), and CSF (50μl). Neurological function was evaluated on days 1, 3, and 7 after MCAo. Ex vivo MRI and immunohistochemistry were conducted on day 7. Results: All ELV treatments greatly improved neurologic scores in a sustained fashion up to the 7-day survival period. Ischemic core and penumbra volumes (computed from T2WI) were significantly reduced by all ELV treatments, and total lesion volumes were significantly reduced by ELV-N32-Na, ELV-N32-Me, ELV-N34-Na, and ELV-N34-Me compared to CSF-treated group (by 60%, 56%, 99%, and 91%, respectively). ELV-treated rats showed less infarction with an increased number of NeuN- and GFAP-positive cells as well as SMI-71-positive vessels in the cortex and less IgG staining in the cortex. ELV-mediated protection was extensive in the frontal-parietal cortex (tissue was salvaged by 57-96%), subcortex (73-75%), and total infarct volume, correction for brain swelling was dramatically reduced in all ELV-treated groups by 55-91%. Conclusion: We have shown that the administration of ELVs provides high-grade neurobehavioral recovery, decreases ischemic core and penumbra volumes, as well as attenuates cellular damage, blood vessel integrity, and BBB disruption.

BackgroundIntracerebral hemorrhage (ICH) is a serious medical problem, and promising strategy is limited. Macrophage initiated brain inflammatory injury following ICH, but the molecular mechanism had not been well identified. E3 ligase Nedd4L is implicated in the pathogenesis of the inflammatory immune response. MethodsIn the present study, we detected the levels of Nedd4L in macrophages following ICH. Furthermore, Macrophage M1 polarization, pro-inflammatory cytokine production, BBB disruption, brain water content and neurological function were examined in ICH mice. ResultsHere, we demonstrated that E3 ligase Nedd4L levels of macrophage increased following ICH, promoted M1 polarization inflammation by TRAF3. Nedd4L promoted BBB disruption, as well as neurological deficits. Inhibition of Nedd4L significantly attenuated M1 polarization in vivo. Inhibition of Nedd4L decreased TRAF3 and TBK1 levels, and subsequent phosphorylation of p38 and NF-κB p65 subunit following ICH. ConclusionsOur data demonstrated that Nedd4L was involved in the pathogenesis of ICH, which promoted inflammatory responses and exacerbated brain damage by TRAF3 following ICH.

Apelin-13 enhances neurofunctional recovery and suppresses neuroinflammation via the SIRT1/NF-κB axis in ischemic stroke.

Transcranial low-level light therapy (LLLT) has gained interest as a non-invasive, inexpensive and safe method of modulating neurological and psychological functions in recent years. This study was designed to examine the preventive effects of LLLT via visible light source against cerebral ischemia at the behavioral, structural and neurochemical levels. The mice received LLLT twice a day for 2 days prior to photothrombotic cortical ischemia. LLLT significantly reduced infarct size and edema and improved neurological and motor function 24 h after ischemic injury. In addition, LLLT markedly inhibited Iba-1- and GFAP-positive cells, which was accompanied by a reduction in the expression of inflammatory mediators and inhibition of MAPK activation and NF-κB translocation in the ischemic cortex. Concomitantly, LLLT significantly attenuated leukocyte accumulation and infiltration into the infarct perifocal region. LLLT also prevented BBB disruption after ischemic events, as indicated by a reduction of Evans blue leakage and water content. These findings were corroborated by immunofluorescence staining of the tight junction-related proteins in the ischemic cortex in response to LLLT. Non-invasive intervention of LLLT in ischemic brain injury may provide a significant functional benefit with an underlying mechanism possibly being suppression of neuroinflammation and reduction of BBB disruption.

Intracerebral hemorrhage (ICH) is a fatal cerebrovascular disease. Neuroinflammation plays an important pathological role in brain injury after ICH. NLRP3 contributes to the pathogenesis of ICH, but the underlying mechanisms regulating of NLRP3 remain elusive. V-set and immunoglobulin domain containing 4 (VSIG4), specifically expressed in resting tissue-resident macrophages, can deliver anti-inflammatory signals into various inflammatory diseases. However, the interaction between VSIG4 and NLRP3, as well as the underlying mechanisms after ICH have not been reported. C57BL/6 mice were subjected to the autologous blood injection ICH model. VSIG4 and NLRP3 levels of macrophages were detected following ICH. Ad-VSIG4 or controls were administered via intracerebroventricular (i.c.v) injection before ICH induction. STAT3 inhibitor (S31-201), JAK2 inhibitor (TG101348), or Ad-A20 RNAi was administered to investigate the role of JAK2-STAT3-A20 pathway in VSIG4-mediated neuroinflammation after ICH. Pro-inflammatory cytokine production, BBB disruption, brain water content, and neurological test were examined in ICH mice. VSIG4 levels were significantly decreased, and NLRP3 levels were significantly increased in the perihematomal brain tissues after ICH. Ad-VSIG4 attenuated NLRP3 levels and inhibited inflammation, as well as improved neurological function and reduced BBB disruption and brain water content. Furthermore, Ad-VSIG4 increased the protein levels of phosphorylated JAK2 and STAT3, and A20 levels at 24h after ICH. STAT3 inhibitor, JAK2 inhibitor, and A20 RNAi abolished the beneficial effects of Ad-VSIG4 after ICH. In summary, these data suggested that VSIG4 attenuated NLRP3 and ameliorated neuroinflammation via JAK2-STAT3-A20 pathway after intracerebral hemorrhage in mice. VSIG4 might be an ideal therapeutic target for ICH patients.

Taurine attenuates neuronal ferroptosis by regulating GABAB/AKT/GSK3β/β-catenin pathway after subarachnoid hemorrhage.

Apolipoprotein E (ApoE)-mimetic peptides have been demonstrated to be beneficial in secondary brain injury following experimental subarachnoid hemorrhage (SAH). However, the molecular mechanisms underlying these benefits in SAH models have not been clearly identified. This study investigated whether an ApoE-mimetic peptide affords neuroprotection in early brain injury (EBI) following SAH by attenuating BBB disruption. SAH was induced by an endovascular perforation in young, healthy, male wild-type (WT) C57BL/6J mice. Multiple techniques, including MRI with T2-weighted imaging, 18 FDG PET-CT scanning and histological studies, were used to examine BBB integrity and neurological dysfunction in EBI following SAH. We found that SAH induced a significant increase of BBB permeability and neuron apoptosis, whereas ApoE-mimetic peptide treatment significantly reduced the degradation of tight junction proteins and endothelial cell apoptosis. These effects reduced brain edema and neuron apoptosis, increased cerebral glucose uptake, and improved neurological functions. Further investigation revealed that the ApoE-mimetic peptide inhibited the proinflammatory activators of MMP-9, including CypA, NF-κB, IL-6, TNF-α, and IL-1β, thereby ameliorating BBB disruption at the acute stage of SAH. Together, these data indicate that ApoE-mimetic peptide may be a novel and promising therapeutic strategy for EBI amelioration after SAH that are worthy of further study.

Mitigating the effects of Endothelin-1 following a minimally invasive surgery reduces the blood-brain barrier permeability in a rabbit model of intracerebral hemorrhage

Traumatic brain injury (TBI) induces the excessive inflammation and disruption of blood–brain barrier, both of which are partially mediated by the activation of microglia and release of inflammatory cytokines. Previous reports showed that administration of regulatory T cells (Tregs) could suppress inflammation and promote neurological function recovery, and that the IL-2/anti-IL-2 complex (IL-2C) could increase the number of Tregs. Thus, we hypothesized that IL-2C-mediated expansion of Tregs would be beneficial in mice subjected to TBI. In this study, mice received an intraperitoneal injection of IL-2C for three consecutive days. We observed that IL-2C dose-dependently increased Tregs without affecting the populations of CD4, CD8, or natural killer cells. IL-2C could improve the neurological recovery and reduce brain edema, tissue loss, neutrophils infiltration, and tight junction proteins degradation. Furthermore, this complex could also reduce the expression of CD16/32, IL-1β, or TNF-α, and elevate the expression of CD206, arginase 1, or TGF-β. These results suggest that IL-2C could be a potential therapeutic method to alleviate excessive inflammation and maintain blood vessel stability after TBI.

BackgroundGlucocorticoids (GCs) have been widely used in the treatment of severe traumatic brain injury (TBI) to inhibit neuroinflammation and alleviating brain edema and cannot be replaced by other drugs. However, their systemic application still faces many obstacles, such as the poor blood-brain-barrier (BBB) penetration and severe side effects. Therefore, new treatment strategy or compounds are urgently needed in clinic.MethodsHerein, an injectable nanocomposite hydrogel is developed as a biofunctionalized delivery platform for intraoperative administration of dexamethasone (DEX) after TBI. By using a mice TBI model, the safety and efficacy of the nanohydrogels in treating BBB disruption, brain edema and nerve injury were evaluated after TBI.ResultsThe hydrogel is composed of polysaccharide matrix (carboxymethyl chitosan and oxidized dextran) and mesoporous polydopamine (MPDA) nanoparticles loaded with DEX (MPDA@DEX@gel) that could realize in situ injection, self-assembly, a high DEX loading rate and sustained release around the lesion. The MPDA@DEX@gel exhibits excellent antibacterial and hemostatic properties, good biocompatibility and antioxidation, and self-healing capability in vitro. These in vitro and in vivo results show that local application of MPDA@DEX@gel not only alleviates brain edema, promotes neuronal survival, and improves neurological function by restoring the integrity of BBB and inhibiting neuroinflammation after TBI, but also effectively avoids the peripheral and central side effects.ConclusionOur study provides a promising treatment strategy for the rational use of GCs in patients with severe TBI.

The role of the PDGF-BB/PDGFR-β signaling pathway in microcirculatory disturbances and BBB destruction after experimental subarachnoid hemorrhage in mice.

BackgroundNeuroinflammation is closely associated with functional outcome in subarachnoid hemorrhage (SAH) patients. Our recent study demonstrated that fluoxetine inhibited NLRP3 inflammasome activation and attenuated necrotic cell death in early brain injury after SAH, while the effects and potential mechanisms of fluoxetine on neuroinflammation after SAH have not been well-studied yet.MethodsOne hundred and fifty-three male SD rats were subjected to the endovascular perforation model of SAH. Fluoxetine (10 mg/kg) was administered intravenously at 6 h after SAH induction. TAK-242 (1.5 mg/kg), an exogenous TLR4 antagonist, was injected intraperitoneally 1 h after SAH. SAH grade, neurological scores, brain water content, Evans blue extravasation, immunofluorescence/TUNEL staining, quantitative real-time polymerase chain reaction (qRT-PCR), and western blot were performed.ResultsFluoxetine administration attenuated BBB disruption, brain edema, and improved neurological function after SAH. In addition, fluoxetine alleviated the number of Iba-1-positive microglia/macrophages, neutrophil infiltration, and cell death. Moreover, fluoxetine reduced the levels of pro-inflammatory cytokines, downregulated the expression of TLR4 and MyD88, and promoted the nuclear translocation of NF-κB p65, which were also found in rats with TAK-242 administration. Combined administration of fluoxetine and TAK-242 did not enhance the neuroprotective effects of fluoxetine.ConclusionFluoxetine attenuated neuroinflammation and improved neurological function in SAH rats. The potential mechanisms involved, at least in part, TLR4/MyD88/NF-κB signaling pathway.

Objective To explore whether miR-199a-5p regulated BBB integrity through PI3K/Akt pathway after ischemia stroke. Methods Adult male Sprague-Dawley rats with permanent middle cerebral artery occlusion(MCAO) were used in experiment. The Ludmila Belayev 12-point scoring was used to measure the neurological function of MCAO rats. The Evans Blue Stain, immunofluorescence staining, western-blotting and RT-PCR were performed to evaluate the effects of miR-199a-5p mimic on BBB integrity in rats following MCAO. Results The result suggested that miR-199a-5p mimic treatment possessed the potential to boost proprioception and motor activity of MCAO rats. MiR-199a-5p decreased the expression of PIK3R2 after MCAO, activated Akt signaling pathway, and increased the expression of Claudin-5 and VEGF in the ischemic penumbra. Furthermore, miR-199a-5p alleviated inflammation after cerebral ischemia. BBB leakage and neurocyte apoptosis were cut down in MCAO rats treated with miR-199a-5p mimic. Conclusions MiR-199a-5p mimic decreased the expression of PIK3R2 and activated Akt signaling pathway after ischemia stroke, reduced the expression of inflammatory cytokines, and attenuated BBB disruption after ischemic stroke.

BackgroundNeuroinflammation is one of the most important pathogeneses in secondary brain injury after traumatic brain injury (TBI). Neutrophil extracellular traps (NETs) forming neutrophils were found throughout the brain tissue of TBI patients and elevated plasma NET biomarkers correlated with worse outcomes. However, the biological function and underlying mechanisms of NETs in TBI-induced neural damage are not yet fully understood. Here, we used Cl-amidine, a selective inhibitor of NETs to investigate the role of NETs in neural damage after TBI.MethodsControlled cortical impact model was performed to establish TBI. Cl-amidine, 2′3′-cGAMP (an activator of stimulating Interferon genes (STING)), C-176 (a selective STING inhibitor), and Kira6 [a selectively phosphorylated inositol-requiring enzyme-1 alpha [IRE1α] inhibitor] were administrated to explore the mechanism by which NETs promote neuroinflammation and neuronal apoptosis after TBI. Peptidyl arginine deiminase 4 (PAD4), an essential enzyme for neutrophil extracellular trap formation, is overexpressed with adenoviruses in the cortex of mice 1 day before TBI. The short-term neurobehavior tests, magnetic resonance imaging (MRI), laser speckle contrast imaging (LSCI), Evans blue extravasation assay, Fluoro-Jade C (FJC), TUNEL, immunofluorescence, enzyme-linked immunosorbent assay (ELISA), western blotting, and quantitative-PCR were performed in this study.ResultsNeutrophils form NETs presenting in the circulation and brain at 3 days after TBI. NETs inhibitor Cl-amidine treatment improved short-term neurological functions, reduced cerebral lesion volume, reduced brain edema, and restored cerebral blood flow (CBF) after TBI. In addition, Cl-amidine exerted neuroprotective effects by attenuating BBB disruption, inhibiting immune cell infiltration, and alleviating neuronal death after TBI. Moreover, Cl-amidine treatment inhibited microglia/macrophage pro-inflammatory polarization and promoted anti-inflammatory polarization at 3 days after TBI. Mechanistically, STING ligand 2′3′-cGAMP abolished the neuroprotection of Cl-amidine via IRE1α/ASK1/JNK signaling pathway after TBI. Importantly, overexpression of PAD4 promotes neuroinflammation and neuronal death via the IRE1α/ASK1/JNK signaling pathway after TBI. However, STING inhibitor C-176 or IRE1α inhibitor Kira6 effectively abolished the neurodestructive effects of PAD4 overexpression after TBI.ConclusionAltogether, we are the first to demonstrate that NETs inhibition with Cl-amidine ameliorated neuroinflammation, neuronal apoptosis, and neurological deficits via STING-dependent IRE1α/ASK1/JNK signaling pathway after TBI. Thus, Cl-amidine treatment may provide a promising therapeutic approach for the early management of TBI.Graphical