Using Evans Blue Dye to Determine Blood-Brain Barrier Integrity in Rodents

Synthesis of Lipidated Ligands and Formulation of Glia-Specific LNPs for RNAi-Mediated BBB Protection

Pro-inflammatory polarization of microglia and astrocytes results in neuroinflammation and blood-brain barrier (BBB) disruption after a primary traumatic brain injury (TBI). Herein, we demonstrate that the dual-ligand functionalized lipid nanoparticles (AM31 LNPs) were actively and specifically internalized by microglia and astrocytes via mannose receptor (MR)- and adenosine receptor (AR)-mediated endocytosis, respectively, in a mouse model of TBI. Systemic administration of AM31 LNPs carrying siRNA against p65 resulted in internalization by the glial cells in the peri-infarct region and a robust knockdown of p65 at both mRNA and protein levels in these cells, leading to significant down-regulation of key pro-inflammatory cytokines and up-regulation of key anti-inflammatory cytokines. AM31 LNP-mediated silencing of p65 ameliorated TBI-induced BBB disruption. Our data proved that AM 31 LNP is a promising vehicle for RNA therapeutics for targeting microglia and astrocytes in neural disorder.

Propofol Protects the Blood-Brain Barrier After Traumatic Brain Injury by Stabilizing the Extracellular Matrix via Prrx1: From Neuroglioma to Neurotrauma

The purpose of this study is to explore the shared molecular pathogenesis of traumatic brain injury (TBI) and high-grade glioma and investigate the mechanism of propofol (PF) as a potential protective agent. By analyzing the Chinese glioma genome atlas (CGGA) and The Cancer Genome Atlas (TCGA) databases, we compared the transcriptomic data of high-grade glioma and TBI patients to identify common pathological mechanisms. Through bioinformatics analysis, in vitro experiments and in vivo TBI model, we investigated the regulatory effect of PF on extracellular matrix (ECM)-related genes through Prrx1 under oxidative stress. The impact of PF on BBB integrity under oxidative stress was investigated using a dual-layer BBB model, and we explored the protective effect of PF on tight junction proteins and ECM-related genes in mice after TBI. The study found that high-grade glioma and TBI share ECM instability as an important molecular pathological mechanism. PF stabilizes the ECM and protects the BBB by directly binding to Prrx1 or indirectly regulating Prrx1 through miRNAs. In addition, PF reduces intracellular calcium ions and ROS levels under oxidative stress, thereby preserving BBB integrity. In a TBI mouse model, PF protected BBB integrity through up-regulated tight junction proteins and stabilized the expression of ECM-related genes. Our study reveals the shared molecular pathogenesis between TBI and glioblastoma and demonstrate the potential of PF as a protective agent of BBB. This provides new targets and approaches for the development of novel neurotrauma therapeutic drugs.

Luteolin-7-O-β-d-Glucuronide Attenuated Cerebral Ischemia/Reperfusion Injury: Involvement of the Blood-Brain Barrier

Ischemic stroke is a common cerebrovascular disease with high mortality, high morbidity, and high disability. Cerebral ischemia/reperfusion injury seriously affects the quality of life of patients. Luteolin-7-O-β-d-glucuronide (LGU) is a major active flavonoid compound extracted from Ixeris sonchifolia (Bge.) Hance, a Chinese medicinal herb mainly used for the treatment of coronary heart disease, angina pectoris, cerebral infarction, etc. In the present study, the protective effect of LGU on cerebral ischemia/reperfusion injury was investigated in an oxygen-glucose deprivation/reoxygenation (OGD/R) neuronal model and a transient middle cerebral artery occlusion (tMCAO) rat model. In in vitro experiments, LGU was found to improve the OGD/R-induced decrease in neuronal viability effectively by the MTT assay. In in vivo experiments, neurological deficit scores, infarction volume rates, and brain water content rates were improved after a single intravenous administration of LGU. These findings suggest that LGU has significant protective effects on cerebral ischemia/reperfusion injury in vitro and in vivo. To further explore the potential mechanism of LGU on cerebral ischemia/reperfusion injury, we performed a series of tests. The results showed that a single administration of LGU decreased the content of EB and S100B and ameliorated the abnormal expression of tight junction proteins ZO-1 and occludin and metalloproteinase MMP-9 in the ischemic cerebral cortex of the tMCAO 24-h injury model. In addition, LGU also improved the tight junction structure between endothelial cells and the degree of basement membrane degradation and reduced the content of TNF-α and IL-1β in the brain tissue. Thereby, LGU attenuated cerebral ischemia/reperfusion injury by improving the permeability of the blood-brain barrier. The present study provides new insights into the therapeutic potential of LGU in cerebral ischemia.

BCAT1 alleviates early brain injury by inhibiting ferroptosis through PI3K/AKT/mTOR/GPX4 pathway after subarachnoid hemorrhage

Regulation of the redox system by branched-chain amino acid transferase 1 (BCAT1) is of great significance in the occurrence and development of diseases, but the relationship between BCAT1 and subarachnoid hemorrhage (SAH) is still unknown. Ferroptosis, featured by iron-dependent lipid peroxidation accompanied by the depletion of glutathione peroxidase 4 (GPX4), has been implicated in the pathological process of early brain injury after subarachnoid hemorrhage. This study established SAH model by endovascular perforation and adding oxyhemoglobin (Hb) to HT22 cells and delved into the mechanism of BCAT1 in SAH-induced ferroptotic neuronal cell death. It was found that SAH-induced neuronal ferroptosis could be inhibited by BCAT1 overexpression (OE) in rats and HT22 cells, and BCAT1 OE alleviated neurological deficits and cognitive dysfunction in rats after SAH. In addition, the effect of BCAT1 could be reversed by the Ly294002, a specific inhibitor of the PI3K pathway. In summary, our present study indicated that BCAT1 OE alleviated early brain injury EBI after SAH by inhibiting neuron ferroptosis via activation of PI3K/AKT/mTOR pathway and the elevation of GPX4. These results suggested that BCAT1 was a promising therapeutic target for subarachnoid hemorrhage.

Acoustic Delivery of Plasma Low-Density Lipoprotein into Liver via ApoB100-Targeted Microbubbles Inhibits Atherosclerotic Plaque Growth

Atherosclerosis is the main risk factor for cardiovascular disease, which accounts for the majority of mortality worldwide. A significantly increased plasma level of low-density lipoprotein cholesterol (LDL-C), surrounded by a monolayer of phospholipids, free cholesterol, and one apolipoprotein B-100 (ApoB-100) in the blood, plays the most significant role in driving the development of atherosclerosis. Commercially available cholesterol-lowering drugs are not sufficient for preventing recurrent cardiovascular events. Developing alternative strategies to decrease the plasma cholesterol levels is desirable. Herein, we develop an approach for reducing LDL-C levels using gas-filled microbubbles (MBs) that were coated with anti-ApoB100 antibodies. These targeted MBApoB100 could selectively capture LDL particles in the bloodstream through forming LDL-MBApoB100 complexes and transport them to the liver for degradation. Further immunofluorescence staining and lipidomic analyses showed that these LDL-MBApoB100 complexes may be taken up by Kupffer cells and delivered to liver cells and bile acids, greatly inhibiting atherosclerotic plaque growth. More importantly, ultrasound irradiation of these LDL-MBApoB100 complexes that accumulated in the liver may induce acoustic cavitation effects, significantly enhancing the delivery of LDL into liver cells and accelerating their degradation. Our study provides a strategy for decreasing LDL-C levels and inhibiting the progression of atherosclerosis.

Insulin Signaling Differentially Regulates the Trafficking of Insulin and Amyloid Beta Peptides at the Blood-Brain Barrier

The blood-brain barrier (BBB) is instrumental in clearing toxic metabolites from the brain, such as amyloid-β (Aβ) peptides, and in delivering essential nutrients to the brain, like insulin. In Alzheimer's disease (AD) brain, increased Aβ levels are paralleled by decreased insulin levels, which are accompanied by insulin signaling deficits at the BBB. Thus, we investigated the impact of insulin-like growth factor and insulin receptor (IGF1R and IR) signaling on Aβ and insulin trafficking at the BBB. Following intravenous infusion of an IGF1R/IR kinase inhibitor (AG1024) in wild-type mice, the BBB trafficking of 125I radiolabeled Aβ peptides and insulin was assessed by dynamic SPECT/CT imaging. The brain efflux of [125I]iodo-Aβ42 decreased upon AG1024 treatment. Additionally, the brain influx of [125I]iodoinsulin, [125I]iodo-Aβ42, [125I]iodo-Aβ40, and [125I]iodo-BSA (BBB integrity marker) was decreased, increased, unchanged, and unchanged, respectively, upon AG1024 treatment. Subsequent mechanistic studies were performed using an in vitro BBB cell model. The cell uptake of [125I]iodoinsulin, [125I]iodo-Aβ42, and [125I]iodo-Aβ40 was decreased, increased, and unchanged, respectively, upon AG1024 treatment. Further, AG1024 reduced the phosphorylation of insulin signaling kinases (Akt and Erk) and the membrane expression of Aβ and insulin trafficking receptors (LRP-1 and IR-β). These findings reveal that insulin signaling differentially regulates the BBB trafficking of Aβ peptides and insulin. Moreover, deficits in IGF1R and IR signaling, as observed in the brains of type II diabetes and AD patients, are expected to increase Aβ accumulation while decreasing insulin delivery to the brain, which has been linked to the progression of cognitive decline in AD.

Brain Immune Cell Infiltration and Serum Metabolomic Characteristics Reveal that Lauric Acid Promotes Immune Cell Infiltration in Brain and Streptococcus suis Meningitis in Mice

Although naturally Streptococcus suis serotype 2 (SS2) causes meningitis resulting in death or sequela of neurological symptoms in pigs and humans, severely threatening public health in the world, it has been difficult to build up and confirm experimental meningitis mouse models with obvious neurological syndrome for about two decades, which strongly hampers the in-depth study on the control measures and mechanisms of SS2-induced meningitis. In this study, a typical meningitis mouse model of SS2 was successfully established, as confirmed by the behavioral indicators of balance beam test, suspension test, and gait analysis. With bacteria gathering in the brain, distinguishable unique features including meningeal thickening, vacuolization of the Nissl body, brain barrier damage, glial cell activation, and more infiltration of T cells, macrophages, and DCs are observed in SS2 meningitis mice with typical neurological signs. Some meningitis mice were also accompanied by identical nephritis, ophthalmia, and cochlearitis. Investigation of the metabolic features demonstrated the downregulated cholic acid and upregulated 2-hydroxyvaleric acid, tetrahydrocortisone, nicotinic acid, and lauric acid in blood serum of mice and piglets with meningitis. And feeding trials show that lauric acid can promote meningitis by promoting the infiltration of immune cells into brain. These findings demonstrated that infection of ICR (improved castle road) mice with SS2 was able to induce typical meningitis accompanied by immune cell infiltration and lauric acid upregulation. These data provide a basis for the deep study of SS2 meningitis.

Mertk Reduces Blood-Spinal Cord Barrier Permeability Through the Rhoa/Rock1/P-MLC Pathway After Spinal Cord Injury

Disruption of the blood-spinal cord barrier (BSCB) is a critical event in the secondary injury following spinal cord injury (SCI). Mertk has been reported to play an important role in regulating inflammation and cytoskeletal dynamics. However, the specific involvement of Mertk in BSCB remains elusive. Here, we demonstrated a distinct role of Mertk in the repair of BSCB. Mertk expression is decreased in endothelial cells following SCI. Overexpression of Mertk upregulated tight junction proteins (TJs), reducing BSCB permeability and subsequently inhibiting inflammation and apoptosis. Ultimately, this led to enhanced neural regeneration and functional recovery. Further experiments revealed that the RhoA/Rock1/P-MLC pathway plays a key role in the effects of Mertk. These findings highlight the role of Mertk in promoting SCI recovery through its ability to mitigate BSCB permeability and may provide potential targets for SCI repair.

Focused ultrasound stimulation of infralimbic cortex attenuates reinstatement of methamphetamine-induced conditioned place preference in rats

Methamphetamine (MA) use disorder poses significant challenges to both the affected individuals and society. Current non-drug therapies like transcranial direct-current stimulation and transcranial magnetic stimulation have limitations due to their invasive nature and limited reach to deeper brain areas. Transcranial focused ultrasound (FUS) is gaining attention as a noninvasive option with precise spatial targeting, able to affect deeper areas of the brain. This research focused on assessing the effectiveness of FUS in influencing the infralimbic cortex (IL) to prevent the recurrence of MA-seeking behavior, using the conditioned place preference (CPP) method in rats. The study involved twenty male Sprague-Dawley rats. Neuronal activation by FUS was first examined via electromyography (EMG). Rats received alternately with MA or saline, and confined to one of two distinctive compartments in a three compartment apparatus over a 4-day period. After CPP test, extinction, the first reinstatement, and extinction again, FUS was applied to IL prior to the second MA priming-induced reinstatement. Safety assessments were conducted through locomotor and histological function examinations. EMG data confirmed the effectiveness of FUS in activating neurons. Significant attenuation of reinstatement of MA CPP was found, along with successful targeting of the IL region, confirmed through acoustic field scanning, c-Fos immunohistochemistry, and Evans blue dye staining. No damage to brain tissue or impaired locomotor activity was observed. The results of the study indicate that applying FUS to the IL markedly reduced the recurrence of MA seeking behavior, without harming brain tissue or impairing motor skills. This suggests that FUS could be a promising method for treating MA use disorder, with the infralimbic cortex being an effective target for FUS in preventing MA relapse.

Kaempferol-3-O-(2″-O-galloyl-β-D-glucopyranoside): a novel neuroprotective agent from Diospryros kaki against cerebral ischemia-induced brain injury

Our previous study demonstrated neuroprotective and therapeutic effects of a standardized flavonoid extract from leaves of Diospyros kaki L.f. (DK) on middle cerebral artery occlusion-and-reperfusion (MCAO/R)-induced brain injury and its underlying mechanisms. This study aimed to clarify flavonoid components responsible for the effects of DK using in vitro and in vivo transient brain ischemic models. Organotypic hippocampal slice cultures (OHSCs) subjected to oxygen- and glucose-deprivation (OGD) were performed to evaluate in vitro neuroprotective activity of DK extract and nine isolated flavonoid components. MCAO/R mice were employed to elucidate in vivo neuroprotective effects of the flavonoid component that exhibited the most potent neuroprotective effect in OHSCs. DK extract and seven flavonoids [quercetin, isoquercetin, hyperoside, quercetin-3-O-(2″-O-galloyl-β-D-galactopyranoside), kaempferol, astragalin, and kaempferol-3-O-(2″-O-galloyl-β-D-glucopyranoside) compound (9)] attenuated OGD-induced neuronal cell damage and compound (9) possessed the most potent neuroprotective activity in OHSCs. The MCAO/R mice showed cerebral infarction, massive weight loss, characteristic neurological symptoms, and deterioration of neuronal cells in the brain. Compound (9) and a reference drugs, edaravone, significantly attenuated these physical and neurological impairments. Compound (9) mitigated the blood-brain barrier dysfunction and the change of glutathione and malondialdehyde content in the MCAO mouse brain. Edaravone suppressed the oxidative stress but did not significantly affect the blood-brain barrier permeability. The present results indicated that compound (9) is a flavonoid constituent of DK with a potent neuroprotective activity against transient ischemia-induced brain damage and this action, at least in part, via preservation of blood-brain barrier integrity and suppression of oxidative stress caused by ischemic insult.

Vascular Endothelial Growth Factor-C Treatment Enhances Cerebrospinal Fluid Outflow during Toxoplasma gondii Brain Infection but Does Not Improve Cerebral Edema

Cerebral edema frequently develops in the setting of brain infection and can contribute to elevated intracranial pressure, a medical emergency. How excess fluid is cleared from the brain is not well understood. Previous studies have shown that interstitial fluid is transported out of the brain along perivascular channels that collect into the cerebrospinal fluid (CSF)-filled subarachnoid space. CSF is then removed from the central nervous system through venous and lymphatic routes. The current study tested the hypothesis that increasing lymphatic drainage of CSF would promote clearance of cerebral edema fluid during infection with the neurotropic parasite Toxoplasma gondii. Fluorescent microscopy and magnetic resonance imaging was used to show that C57BL/6 mice develop vasogenic edema 4 to 5 weeks after infection with T. gondii. Tracer experiments were used to evaluate how brain infection affects meningeal lymphatic function, which demonstrated a decreased rate in CSF outflow in T. gondii-infected mice. Next, mice were treated with a vascular endothelial growth factor (VEGF)-C-expressing viral vector, which induced meningeal lymphangiogenesis and improved CSF outflow in chronically infected mice. No difference in cerebral edema was observed between mice that received VEGF-C and those that rececived sham treatment. Therefore, although VEGF-C treatment can improve lymphatic outflow in mice infected with T. gondii, this effect does not lead to increased clearance of edema fluid from the brains of these mice.

Edaravone dexborneol alleviates cerebral ischemia-reperfusion injury through NF-κB/NLRP3 signal pathway

Inflammatory injury following ischemia-reperfusion (I/R) severely limits the efficacy of stroke treatment. Edaravone dexborneol (C.EDA) has been shown to reduce inflammation following a cerebral hemorrhage. However, the precise anti-inflammatory mechanism of C.EDA is unknown. In this study, we investigated whether C.EDA provides neuroprotection after I/R in rats, as well as the potential mechanisms involved. A middle cerebral artery occlusion/reperfusion (I/R) model was created using Sprague-Dawley rats. The blood flow of the central cerebral artery was monitored by a laser speckle imaging system. The neurological score was used to assess behavioral improvement. Cerebral infarction volume was measured by TTC staining. And the integrity of the blood-brain barrier was detected by Evan's blue staining. The expression of the nuclear factor kappa-B (NF-κB)/ the NOD-like receptor protein (NLRP3) inflammasome signal pathway and microglia polarization were detected by immunofluorescence and Western blotting. The cerebral blood flow ratio indicates that the cerebral I/R model was successfully established. After reperfusion for 72 h, the improvement of neurological scores, infarct volume reduction, and integrity of the blood-brain barrier was observed in I/R rats with C.EDA treatment. Meanwhile, the immunofluorescence result showed that the expression of iNOS, NLRP3, and NF-κB protein was decreased and the level of Arg1 was increased. Western blot analysis showed that the expression of NF-κB/NLRP3 signal pathway-related protein was decreased. In conclusion, this study indicates that C.EDA alleviates I/R injury by blocking the activation of the NLRP3 inflammasome and regulating the polarization of M1/M2 microglia via the NF-κB signal pathway.

Long-term effect of indomethacin on a rat model of neonatal hypoxia ischemic encephalopathy through behavioral tests

BACKGROUND

Many medical experts prescribe indomethacin because of its anti-inflammatory, analgesic, tocolytic, and duct closure effects. This article presents an evaluation of the enduring impact of indomethacin on neonatal rats with hypoxic-ischemic (HI) insults, employing behavioral tests as a method of assessment.

METHODS

The experiment was conducted on male Wistar-Albino rats weighing 10 to 15 g, aged between seven and 10 days. The rats were divided into three groups using a random allocation method as follows: hypoxic ischemic encephalopathy (HIE) group, HIE treated with indomethacin group (INDO), and Sham group. A left common carotid artery ligation and hypoxia model was applied in both the HIE and INDO groups. The INDO group was treated with 4 mg/kg intraperitoneal indomethacin every 24 h for 3 days, while the Sham and HIE groups were given dimethylsulfoxide (DMSO). After 72 h, five rats from each group were sacrificed and brain tissue samples were stained with 2,3,5-Triphenyltetrazolium chloride (TCC) for infarct-volume measurement. Seven rats from each group were taken to the behavioral laboratory in the sixth postnatal week (PND42) and six from each group were sacrificed for the Evans blue (EB) experiment for blood-brain barrier (BBB) integrity evaluation. The open field (OF) test and Morris water maze (MWM) tests were performed. After behavioral tests, brain tissue were obtained and stained with TCC to assess the infarct volume.

RESULTS

The significant increase in the time spent in the central area and the frequency of crossing to the center in the INDO group compared with the HIE group indicated that indomethacin decreased anxiety-like behavior (p < 0.001, p < 0.05). However, the MWM test revealed that indomethacin did not positively affect learning and memory performance (p > 0.05). Additionally, indomethacin significantly reduced infarct volume and neuropathological grading in adolescence (p < 0.05), although not statistically significant in the early period. Moreover, the EB experiment demonstrated that indomethacin effectively increased BBB integrity (p < 0.05).

CONCLUSIONS

In this study, we have shown for the first time that indomethacin treatment can reduce levels of anxiety-like behavior and enhance levels of exploratory behavior in a neonatal rat model with HIE. It is necessary to determine whether nonsteroidal anti-inflammatory agents, such as indomethacin, should be used for adjuvant therapy in newborns with HIE.

Astrocyte-targeted siRNA delivery by adenosine-functionalized LNP in mouse TBI model

Traumatic brain injury (TBI) induces pro-inflammatory polarization of astrocytes and causes secondary disruption of the blood-brain barrier (BBB) and brain damage. Herein, we report a successful astrocyte-targeted delivery of small interfering RNA (siRNA) by ligand functionalized lipid nanoparticles (LNPs) formulated from adenosine-conjugated lipids and a novel ionizable lipid (denoted by Ad4 LNPs). Systemic administration of Ad4 LNPs carrying siRNA against TLR4 to the mice TBI model resulted in the specific internalization of the LNPs by astrocytes in the vicinity of damaged brain tissue. A substantial knockdown of TLR4 at both mRNA and protein levels in the brain was observed, which led to a significant decrease of key pro-inflammatory cytokines and an increase of key anti-inflammatory cytokines in serum. Dye leakage measurement suggested that the Ad4-LNP-mediated knockdown of TLR4 attenuated the TBI-induced BBB disruption. Together, our data suggest that Ad4 LNP is a promising vehicle for astrocyte-specific delivery of nucleic acid therapeutics.

Transcranial photobiomodulation improves insulin therapy in diabetic microglial reactivity and the brain drainage system

The dysfunction of microglia in the development of diabetes is associated with various diabetic complications, while traditional insulin therapy is insufficient to rapidly restore the function of microglia. Therefore, the search for new alternative methods of treating diabetes-related dysfunction of microglia is urgently needed. Here, we evaluate the effects of transcranial photobiomodulation (tPBM) on microglial function in diabetic mice and investigate its mechanism. We find tPBM treatment effectively improves insulin therapy on microglial morphology and reactivity. We also show that tPBM stimulates brain drainage system through activation of meningeal lymphatics, which contributes to the removal of inflammatory factor, and increase of microglial purinergic receptor P2RY12. Besides, the energy expenditure and locomotor activity of diabetic mice are also improved by tPBM. Our results demonstrate that tPBM can be an efficient, non-invasive method for the treatment of microglial dysfunction caused by diabetes, and also has the potential to prevent diabetic physiological disorders.

Cladribine induces apoptosis, neuroinflammation, mitochondrial oxidative stress, tau phosphorylation and Aβ (1-42) pathway in the hippocampus: An in vivo approach

Cladribine is a purine nucleoside found to enhance toxic amyloid protein and cause memory impairment. Patients following chemotherapy treatment commonly suffer from cognitive deficits more prevalent in the elderly than adults. A previous research study revealed that cladribine has a high affinity to the brain, increases the level of amyloid precursor protein, and results in learning deficits. The study was designed to validate an animal model of cladribine administration to rats through mitochondrial oxidative stress, inflammation, apoptosis, tau phosphorylation, and amyloid-β (1-42) accumulation. In this study, all rats were orally given cladribine (0.5 and 1 mg/kg) for 28 days, resulting in impaired spatial memory confirmed by behavioural activity. On day 29, all rats were euthanized, and the hippocampal tissues were isolated and used for the estimation of neuroinflammatory markers, biochemicals parameters (glutathione, catalase, lipid peroxidation, and nitrite), amyloid-β (1-42) level, neurotransmitters, and nuclear factor kappa B analysis. Cladribine administration significantly elevated cytokines release, dysbalanced neurotransmitter concentration, and promoted the Aβ accumulation and hyperphosphorylation of tau protein. Our study outcome confirmed that cladribine produces cognitive impairment via activation of Nuclear factor kappa B, mitochondrial oxidative stress and dysbalanced of the endogenous antioxidant defence system.

Subchronic exposure to di-(2-ethylhexyl) phthalate (DEHP) elicits blood-brain barrier dysfunction and neuroinflammation in male C57BL/6J mice

BACKGROUND

Exposure to di-(2-ethylhexyl) phthalate (DEHP) can cause neurotoxicity but the mechanism is not clear. Blood brain barrier (BBB) is one of the most important tissues to protect the brain. However, whether DEHP can disrupt the BBB or not remains unclear. The objective of this study is to investigate the potential effects of subchronic DEHP exposure on BBB integrity and discuss the role of BBB in DEHP inducible neurotoxicity with an emphasis on neuroinflammatory responses. Male adult C57BL/6J mice were orally administered with vehicle or 200 or 750 mg/kg/day DEHP for 90 days. Subchronic exposure to high-dose DEHP increased water intake but decreased body weight and brain weight. The concentrations of DEHP metabolites increased in serum from all DEHP-exposed groups while increased in brain only from the high-dose group. DEHP induced neurobehavioural alterations and damaged hippocampal neurons. DEHP increased BBB permeability by Evans blue (EB) extravasation and decreased tight junction proteins (ZO-1, occludin, and claudin-5) while presenting a neuroinflammatory feature characterized by the upregulated inflammatory mediators TNF-α and the NLRP3/caspase-1/IL-1β inflammasome pathway. Our data provide new insights into neurotoxicity caused by subchronic DEHP exposure, which is probably involved in BBB dysfunction and neuroinflammatory responses.

2-Carba cyclic phosphatidic acid regulates blood coagulation and fibrinolysis system for repair after brain injury

Effective blood coagulation prevents inflammation and neuronal loss after brain injury. 2-Carba-cyclic phosphatidic acid (2ccPA), a biotherapeutic for brain injury, inhibits blood extravasation resulting from blood-brain barrier breakdown. However, the hemostasis mechanism of 2ccPA remains unclear. We determined the effects of 2ccPA-injection on blood coagulation and fibrinolysis using a needle-induced brain injury model. 2ccPA suppressed the expression of platelet degranulation-related genes. Immediately after brain injury, 2ccPA increased CD41+ platelet aggregation around the lesions and promoted fibrin aggregation. Additionally, 2ccPA supported fibrinolysis by upregulating plasminogen activator expression. These results suggest the acute effects of 2ccPA on brain hemostasis.

Memantine Attenuates Cognitive and Emotional Dysfunction in Mice with Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is the most common complication of sepsis, with increased morbidity and mortality. To date, there has still been no established pharmacological therapy. Memantine, as an NMDA (N-methyl-d-aspartate) receptor antagonist, exhibited neuroprotective effects against cognitive and emotional dysfunction in many disorders. We performed cecal ligation and puncture (CLP) inducing sepsis as the ideal animal model of SAE. CLP-induced septic mice were given a memantine treatment through intragastric administration. The novel object recognition test indicated that memantine significantly improved cognitive dysfunction in septic mice. The open field test revealed that the anxiety-like behaviors and locomotion ability of septic mice were relieved by memantine. The pole test further confirmed the protective effects of memantine against immobility. Memantine significantly inhibited the excessive glutamate production and improved impaired neurogenesis on first and seventh day after sepsis, accompanying with reducing proinflammatory cytokines production (tumor necrosis factor alpha (TNF-α), interleukin (IL)-1beta (IL-1β), and IL-10) and microglia activation in the brain of SAE. In addition, memantine treatment also reducing sepsis-induced brain blood barrier disruption via inhibiting the expression of metalloproteinase-9 (MMP-9). In conclusion, memantine exerted neuro-protective effects against cognitive and emotional defects, which might be considered as a promising therapy for SAE.

Effects of Five Coumarins and Standardized Extracts from Tagetes lucida Cav. on Motor Impairment and Neuroinflammation Induced with Cuprizone

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system (CNS) with no curative treatment, and the available therapies aim to modify the course of the disease. It has been demonstrated that extracts of Tagetes lucida have immunomodulatory and neuroprotective effects. This work induced motor damage and neuroinflammation in male BALB/c mice by oral administration of cuprizone (CPZ) (40 mg/kg) for five weeks. In addition, the extracts and coumarins of Tagetes lucida (25 mg/kg) were used to control these damage variables; during the experiment, animals were subject to behavioral tests, and at the end of 5 weeks, mice from each group were used to measure the integrity of biological barriers (brain, kidneys, and spleen) through the extravasation test with blue Evans dye. In another group of animals, the ELISA method measured the brain concentrations of IL-1β, IL-4, IL-10, and TNF-α. The results presented here allow us to conclude that the extracts and coumarins IC, HN, PE, DF, and SC of Tagetes lucida exert a neuroprotective effect by controlling the motor damage and neuroinflammation by increasing the expression of IL-4 and IL-10 and decreasing IL-1β and TNF-α; notably, these treatments also protect organs from vascular permeability increase, mainly the BBB, in mice with CPZ-induced experimental encephalomyelitis (VEH * p < 0.05). However, more studies must be carried out to elucidate the molecular mechanisms of the pharmacological effects of this Mexican medicinal plant.

Reactive astrocytes associated with prion disease impair the blood brain barrier

BACKGROUND

Impairment of the blood-brain barrier (BBB) is considered to be a common feature among neurodegenerative diseases, including Alzheimer's, Parkinson's and prion diseases. In prion disease, increased BBB permeability was reported 40 years ago, yet the mechanisms behind the loss of BBB integrity have never been explored. Recently, we showed that reactive astrocytes associated with prion diseases are neurotoxic. The current work examines the potential link between astrocyte reactivity and BBB breakdown.

RESULTS

In prion-infected mice, the loss of BBB integrity and aberrant localization of aquaporin 4 (AQP4), a sign of retraction of astrocytic endfeet from blood vessels, were noticeable prior to disease onset. Gaps in cell-to-cell junctions along blood vessels, together with downregulation of Occludin, Claudin-5 and VE-cadherin, which constitute tight and adherens junctions, suggested that loss of BBB integrity is linked with degeneration of vascular endothelial cells. In contrast to cells isolated from non-infected adult mice, endothelial cells originating from prion-infected mice displayed disease-associated changes, including lower levels of Occludin, Claudin-5 and VE-cadherin expression, impaired tight and adherens junctions, and reduced trans-endothelial electrical resistance (TEER). Endothelial cells isolated from non-infected mice, when co-cultured with reactive astrocytes isolated from prion-infected animals or treated with media conditioned by the reactive astrocytes, developed the disease-associated phenotype observed in the endothelial cells from prion-infected mice. Reactive astrocytes were found to produce high levels of secreted IL-6, and treatment of endothelial monolayers originating from non-infected animals with recombinant IL-6 alone reduced their TEER. Remarkably, treatment with extracellular vesicles produced by normal astrocytes partially reversed the disease phenotype of endothelial cells isolated from prion-infected animals.

CONCLUSIONS

To our knowledge, the current work is the first to illustrate early BBB breakdown in prion disease and to document that reactive astrocytes associated with prion disease are detrimental to BBB integrity. Moreover, our findings suggest that the harmful effects are linked to proinflammatory factors secreted by reactive astrocytes.

Levcromakalim provokes an acute rapid-onset migraine-like phenotype without inducing cortical spreading depolarization

BACKGROUND

Migraine headache attacks and accompanying sensory augmentation can be induced by several agents including levcromakalim (LVC), that is also capable of provoking aura-like symptoms in migraineurs. We investigated whether single LVC injection causes acute migraine-like phenotype in rats and induces/modulates cortical spreading depolarization (CSD), a rodent model of migraine aura.

METHODS

Wistar rats were administered LVC (1 mg/kg, i.p.) and compared to control (CTRL, vehicle, i.p.) and nitroglycerin (NTG, 10 mg/kg, i.p.) groups. Von Frey filaments were used to examine the periorbital and hind paw mechanical allodynia. Dark-light box (DLB), elevated plus maze (EPM), and open field arena (OFA) were used to evaluate light sensitivity and anxiety-related behaviors. The effects of LVC on CSD parameters, somatosensory evoked potentials, and baseline dural EEG (electroencephalography) were investigated. Possible CSD-induced c-fos expression was studied with Western Blot. Blood-brain barrier integrity in cortex was examined with Evans blue assay.

RESULTS

LVC and NTG administration robustly reduced periorbital mechanical thresholds in rats and induced anxiety-like behaviors and photophobia within 30 and 120 min, respectively. LVC induced migraine-like phenotype recovered in 2 h while NTG group did not fully recover before 4 h. Both LVC and NTG did not provoke DC (direct current) shift, EEG alterations or cortical c-fos expression characteristic to CSD. LVC did not induce de novo CSD and affect KCl (potassium chloride)-induced CSD parameters except for an increase in propagation failure. However, NTG significantly increased both CSD susceptibility and propagation failure. Somatosensory evoked potential (SSEP) configurations were not altered in both LVC and NTG groups, but SSEP latencies were prolonged after CSD. Acute LVC or NTG injection did not increase cortical BBB permeability.

CONCLUSIONS

Single LVC administration induced the fastest manifestation and recovery of acute migraine-like phenotype which was not mediated by CSD waves in the cerebral cortex. We suppose LVC triggered rapid-onset migraine-like symptoms are probably related to functional alterations in the trigeminal nociceptive system and K⁺ channel opening properties of LVC. Understanding the neurobiological mechanisms of this nociceptive window, may provide a novel target in migraine treatment.

Inhibition of lysophosphatidic acid receptor 1 relieves PMN recruitment in CNS via LPA1/TSP1/CXCR2 pathway and alleviates disruption on blood-brain barrier following intracerebral haemorrhage in mice

BACKGROUD

The frequencies of morbidity and impairment associated with spontaneous intracerebral haemorrhage (ICH) are comparatively high. Blood-brain barrier (BBB) integrity was compromised due to subsequent brain injury induced by ICH, which is crucial for a poor prognosis. Polymorphonuclear leukocyte (PMN) strongly modulate the disruption of BBB in the central nervous system (CNS). The lysophosphatidic acid receptor 1 (LPA1) mediated thrombospondin-1 (TSP1) regulation in astrocytes, which induce macrophage inflammatory protein 2(MIP2) secretion. MIP2 enhance PMN recruitment through CXC chemokine type 2 (CXCR2) activation. The purpose of this study was to investigate whether the LPA1-mediated inhibition of PMN recruitment and BBB protection after ICH is regulated by TSP1 and CXCR2 networks.

METHODS

ICH induction was performed in CD1 mice using collagenase administration. AM966, a targeted LPA1 antagonist, was orally administered 1 and 12 h following ICH. further identify possible LPA1-mediated BBB protection mechanisms, we intracerebroventricularly (ICV) administered a CXCR2 ligand MIP2, as well as TSP1 CRISPR activation (ACT) with AM966. Consequently, we performed neurobehavioral, brain water content (BWC), Evans blue staining (EBS), immunofluorescence (IF), and western blot (WB) analyses.

RESULTS

After ICH, astrocytes showed signs of LPA1, which peaked after 24 h, while PMN\ displayed evidence of CXCR2. The AM966-mediated LPA1 suppression relieved PMN recruitment, diminished brain oedema, demonstrated extravasation (as evidenced by EBS), protected BBB integrity, and enhanced neurologic activity following ICH. AM966 treatment strongly reduced TSP1, CXCR2, Occludin, and Claudin-5 expressions and PMN recruitment following ICH, and their expressions were restored by MIP2 and TSP1 CRISPR (ACT).

CONCLUSIONS

This study shows that LAP1 suppression reduced PMN recruitment after ICH in mice via TSP1/CXCR2 signalling, which minimized BBB disruption and improved the CNS's neurobehavioral functioning. Hence, LPA1 is a strong candidate for therapy to reduce PMN recruitment and offer protection of BBB integrity after ICH.

Therapeutic effects of a standardized-flavonoid Diospyros kaki L.f. leaf extract on transient focal cerebral ischemia-induced brain injury in mice

This study aimed to investigate the neuroprotective and therapeutic effects of Diospyros kaki L.f. leaves (DK) on transient focal cerebral ischemic injury and underlying mechanisms using a middle cerebral artery occlusion (MCAO) model of mice. The animals received the MCAO operation on day 0. The daily administrations of DK (50 and 100 mg/kg, p.o) and edaravone (6 mg/kg, i.v), a reference drug with radical scavenging activity, were started 7 days before (pre-treatment) or immediately after the MCAO operation (post-treatment) and continued during the experimental period. Histochemical, biochemical, and neurological changes and cognitive performance were evaluated. MCAO caused cerebral infarction and neuronal cell loss in the cortex, striatum, and hippocampus in a manner accompanied by spatial cognitive deficits. These neurological and cognitive impairments caused by MCAO were significantly attenuated by pre- and post-ischemic treatments with DK and edaravone, suggesting that DK, like edaravone, has therapeutic potential for cerebral ischemia-induced brain damage. DK and edaravone suppressed MCAO-induced changes in biomarkers for apoptosis (TUNEL-positive cell number and cleaved caspase-3 protein expression) and oxidative stress (glutathione and malondialdehyde contents) in the brain. Interestingly, DK, but not edaravone, mitigated an increase in blood-brain permeability and down-regulation of vascular endothelial growth factor protein expression caused by MCAO. Although the exact chemical constituents implicated in the effects of DK remain to be clarified, the present results indicate that DK exerts neuroprotective and therapeutic activity against transient focal cerebral ischemia-induced injury probably by suppressing oxidative stress, apoptotic process, and mechanisms impairing blood-brain barrier integrity in the brain.

Focused ultrasound for treatment of peripheral brain tumors

Malignant brain tumors are the leading cause of cancer-related death in children and remain a significant cause of morbidity and mortality throughout all demographics. Central nervous system (CNS) tumors are classically treated with surgical resection and radiotherapy in addition to adjuvant chemotherapy. However, the therapeutic efficacy of chemotherapeutic agents is limited due to the blood-brain barrier (BBB). Magnetic resonance guided focused ultrasound (MRgFUS) is a new and promising intervention for CNS tumors, which has shown success in preclinical trials. High-intensity focused ultrasound (HIFU) has the capacity to serve as a direct therapeutic agent in the form of thermoablation and mechanical destruction of the tumor. Low-intensity focused ultrasound (LIFU) has been shown to disrupt the BBB and enhance the uptake of therapeutic agents in the brain and CNS. The authors present a review of MRgFUS in the treatment of CNS tumors. This treatment method has shown promising results in preclinical trials including minimal adverse effects, increased infiltration of the therapeutic agents into the CNS, decreased tumor progression, and improved survival rates.

Recovery of neurosurgical high-frequency electroporation injury in the canine brain can be accelerated by 7,8-dihydroxyflavone

BACKGROUND

Although traumatic brain injury (TBI) occurs in a very short time, the biological consequence of a TBI, such as Alzheimer's disease, may last a lifetime. To date, effective interventions are not available to improve recovery from a TBI. Herein we aimed to ascertain whether recovery of neurosurgical high-frequency irreversible electroporation (HFIRE) injury in brain tissues can be accelerated by 7,8-dihydroxyflavone (7,8-DHF).

METHODS

The HFIRE injury was induced in the right parietal cortex of 8 adult healthy and neurologically intact male dogs. Two weeks before HFIRE injury, each dog was administered orally with or without 7,8-DHF (30 mg/kg) once daily for consecutive 2 weeks (n = 4 for each group). The values of blood-brain barrier (BBB) disruption, brain edema, and cerebral infarction volumes were measured. The concentrations of beta-amyloid, interleukin-1β, interleukin-6 and tumor necrosis factor-α in the cerebrospinal fluid were measured biochemically.

RESULTS

The BBB disruption, brain edema, infarction volumes, and maximal cross-section area caused by HFIRE injury in canine brain were significantly attenuated by 7,8-DHF therapy (P < 0.0001). Additionally, 7,8-DHF significantly reduced the HFIRE-induced cerebral overproduction of beta-amyloid and proinflammatory cytokines in the cerebrospinal fluid (P < 0.0001) in dogs with HFIRE.

CONCLUSIONS

Recovery of neurosurgical HFIRE injury in canine brain tissues can be accelerated by 7,8-DHT via ameliorating BBB disruption as well as cerebral overproduction of both beta-amyloid and proinflammatory cytokines.

Reactive astrocytes associated with prion disease impair the blood brain barrier

Background

Impairment of the blood-brain barrier (BBB) is considered to be a common feature among neurodegenerative diseases, including Alzheimer's, Parkinson's and prion diseases. In prion disease, increased BBB permeability was reported 40 years ago, yet the mechanisms behind the loss of BBB integrity have never been explored. Recently, we showed that reactive astrocytes associated with prion diseases are neurotoxic. The current work examines the potential link between astrocyte reactivity and BBB breakdown.

Results

In prion-infected mice, the loss of BBB integrity and aberrant localization of aquaporin 4 (AQP4), a sign of retraction of astrocytic endfeet from blood vessels, were noticeable prior to disease onset. Gaps in cell-to-cell junctions along blood vessels, together with downregulation of Occludin, Claudin-5 and VE-cadherin, which constitute tight and adherens junctions, suggested that loss of BBB integrity is linked with degeneration of vascular endothelial cells. In contrast to cells isolated from non-infected adult mice, endothelial cells originating from prion-infected mice displayed disease-associated changes, including lower levels of Occludin, Claudin-5 and VE-cadherin expression, impaired tight and adherens junctions, and reduced trans-endothelial electrical resistance (TEER). Endothelial cells isolated from non-infected mice, when co-cultured with reactive astrocytes isolated from prion-infected animals or treated with media conditioned by the reactive astrocytes, developed the disease-associated phenotype observed in the endothelial cells from prion-infected mice. Reactive astrocytes were found to produce high levels of secreted IL-6, and treatment of endothelial monolayers originating from non-infected animals with recombinant IL-6 alone reduced their TEER. Remarkably, treatment with extracellular vesicles produced by normal astrocytes partially reversed the disease phenotype of endothelial cells isolated from prion-infected animals.

Conclusions

To our knowledge, the current work is the first to illustrate early BBB breakdown in prion disease and to document that reactive astrocytes associated with prion disease are detrimental to BBB integrity. Moreover, our findings suggest that the harmful effects are linked to proinflammatory factors secreted by reactive astrocytes.

Reactive Oxygen Species-Responsive Transformable and Triple-Targeting Butylphthalide Nanotherapy for Precision Treatment of Ischemic Stroke by Normalizing the Pathological Microenvironment

High potency and safe therapies are still required for ischemic stroke, which is a leading cause of global death and disability. Herein, a reactive oxygen species (ROS)-responsive, transformable, and triple-targeting dl-3-n-butylphthalide (NBP) nanotherapy was developed for ischemic stroke. To this end, a ROS-responsive nanovehicle (OCN) was first constructed using a cyclodextrin-derived material, which showed considerably enhanced cellular uptake in brain endothelial cells due to notably reduced particle size, morphological transformation, and surface chemistry switching upon triggering via pathological signals. Compared to a nonresponsive nanovehicle, this ROS-responsive and transformable nanoplatform OCN exhibited a significantly higher brain accumulation in a mouse model of ischemic stroke, thereby affording notably potentiated therapeutic effects for the nanotherapy derived from NBP-containing OCN. For OCN decorated with a stroke-homing peptide (SHp), we found significantly increased transferrin receptor-mediated endocytosis, in addition to the previously recognized targeting capability to activated neurons. Consistently, the engineered transformable and triple-targeting nanoplatform, i.e., SHp-decorated OCN (SON), displayed a more efficient distribution in the injured brain in mice with ischemic stroke, showing considerable localization in endothelial cells and neurons. Furthermore, the finally formulated ROS-responsive transformable and triple-targeting nanotherapy (NBP-loaded SON) demonstrated highly potent neuroprotective activity in mice, which outperformed the SHp-deficient nanotherapy at a 5-fold higher dose. Mechanistically, our bioresponsive, transformable, and triple-targeting nanotherapy attenuated the ischemia/reperfusion-induced endothelial permeability and improved dendritic remodeling and synaptic plasticity of neurons in the injured brain tissue, thereby promoting much better functional recovery, which were achieved by efficiently enhancing NBP delivery to the ischemic brain tissue, targeting injured endothelial cells and activated neurons/microglial cells, and normalizing the pathological microenvironment. Moreover, preliminary studies indicated that the ROS-responsive NBP nanotherapy displayed a good safety profile. Consequently, the developed triple-targeting NBP nanotherapy with desirable targeting efficiency, spatiotemporally controlled drug release performance, and high translational potential holds great promise for precision therapy of ischemic stroke and other brain diseases.

CD8+ T cells contribute to diet-induced memory deficits in aged male rats

We have previously shown that short-term (3-day) high fat diet (HFD) consumption induces a neuroinflammatory response and subsequent impairment of long-term memory in aged, but not young adult, male rats. However, the immune cell phenotypes driving this proinflammatory response are not well understood. Previously, we showed that microglia isolated from young and aged rats fed a HFD express similar levels of priming and proinflammatory transcripts, suggesting that additional factors may drive the exaggerated neuroinflammatory response selectively observed in aged HFD-fed rats. It is established that T cells infiltrate both the young and especially the aged central nervous system (CNS) and contribute to immune surveillance of the parenchyma. Thus, we investigated the modulating role of short-term HFD on T cell presence in the CNS in aged rats using bulk RNA sequencing and flow cytometry. RNA sequencing results indicate that aging and HFD altered the expression of genes and signaling pathways associated with T cell signaling, immune cell trafficking, and neuroinflammation. Moreover, flow cytometry data showed that aging alone increased CD4+ and CD8+ T cell presence in the brain and that CD8+, but not CD4+, T cells were further increased in aged rats fed a HFD. Based on these data, we selectively depleted circulating CD8+ T cells via an intravenous injection of an anti-CD8 antibody in aged rats prior to 3 days of HFD to infer the functional role these cells may be playing in long-term memory and neuroinflammation. Results indicate that peripheral depletion of CD8+ T cells lowered hippocampal cytokine levels and prevented the HFD-induced i) increase in brain CD8+ T cells, ii) memory impairment, and iii) alterations in pre- and post-synaptic structures in the hippocampus and amygdala. Together, these data indicate a substantial role for CD8+ T cells in mediating diet-induced memory impairments in aged male rats.

Three-dimensional cerebral vasculature topological parameter extraction of transgenic zebrafish embryos with a filling-enhancement deep learning network

Quantitative analysis of zebrafish cerebral vasculature is essential for the study of vascular development and disease. We developed a method to accurately extract the cerebral vasculature topological parameters of transgenic zebrafish embryos. The intermittent and hollow vascular structures of transgenic zebrafish embryos, obtained from 3D light-sheet imaging, were transformed into continuous solid structures with a filling-enhancement deep learning network. The enhancement enables the extraction of 8 vascular topological parameters accurately. Quantitation of the zebrafish cerebral vasculature vessels with the topological parameters show a developmental pattern transition from 2.5 to 5.5 dpf.

Self-Propelled Nanomotors with an Alloyed Engine for Emergency Rescue of Traumatic Brain Injury

In severe traumatic brain injury (sTBI), acute oxidative stress and inflammatory cascades rapidly spread to cause irreversible brain damage and low survival rate within minutes. Therefore, developing a feasible solution for the quick-treatment of life-threatening emergency is urgently demanded to earn time for hospital treatment. Herein, Janus catalysis-driven nanomotors (JCNs) are carefully constructed via plasma-induced alloying technology and sputtering-caused half-coating strategy. The theoretical calculation and experiment results indicate that the heteroatom-doping alloyed engine endows JCNs with much higher catalytic activity for removing reactive oxygen species and reactive nitrogen species than common Pt-based engines. When JCNs are dropped to the surface of the ruptured skull, they can effectively catalyze endogenous hydrogen peroxide, which induces movement as fuels to promote JCNs to deep brain lesions for further nanocatalyst-mediated cascade-blocking therapy. The results demonstrate that the JCNs successfully block the inflammatory cascades, thereby reversing multiple behavioral defects and dramatically declining the mortality of sTBI mice. This work provides a revolutionary nanomotor-based strategy to sense brain injury and scavenge oxidative stress. Meanwhile, the JCNs provide a feasible strategy to adapt various first-aid scenarios due to their self-propelled movement combined with highly multienzyme-like catalytic activity, exhibiting tremendous therapeutic potential to help people for emergency pretreatment.

Magnesium and Zinc Oxide Nanoparticles from Datura alba Improve Cognitive Impairment and Blood Brain Barrier Leakage

Epilepsy is a neurological disorder involving persistent spontaneous seizures and uncontrolled neuronal excitability that leads to cognitive impairments and blood–brain barrier (BBB) disruption. Currently available antiepileptic drugs present side effects and researchers are trying to discover new agents with properties to overcome these drawbacks. The aim was to synthesize magnesium oxide (MgO) and zinc oxide (ZnO) nanoparticles from Datura alba fresh leaf extracts and evaluate their anti-epileptic potential in mice kindling or a repetitive seizures model. The phytoassisted synthesized nanoparticles were characterized using spectroscopy; FT-IR, XRD, SEM, and EDX. Analysis of the NPs confirmed the crystalline pleomorphic shape using the salts of both zinc and magnesium possibly stabilized, functionalized and reduced by bioactive molecules present in plant extract. By using several characterization techniques, NPs were confirmed. UV-Vis spectroscopy of biologically produced ZnO and MgO revealed distinctive peaks at 380 nm and 242 nm, respectively. Our findings categorically demonstrated the reductive role of biomolecules in the formation of ZnO and MgO NPs. The mice kindling model was induced using seven injections of Pentylenetetrazole (PTZ, 40 mg/kg, i.p) for 15 days alternatively. The results showed that mice post-treated with either ZnO or MgO nanoparticles (10 mg/kg, i.p) significantly improved in respect of behavior and memory as confirmed in the Morris water maze (MWM), open field (OF), novel object recognition (NOR) test compared with PTZ treated mice. Furthermore, the ZnO and MgO nanoparticle treatment also maintained the integrity of the BBB, reducing the leakage, as confirmed by Evans blue dye (EBD) compared with PTZ treated mice only. In summary, the current finding demonstrates that green synthesized ZnO and MgO nanoparticles have neuroprotective, ant-epileptic potential, molecular mechanisms, and clinical implications need to be further explored.

A single-cell survey unveils cellular heterogeneity and sensitive responses in mouse cortices induced by oral exposure to triphenyl phosphate

Triphenyl phosphate (TPhP) is a non-halogenated organophosphorus flame retardant, and there is a higher exposure risk in children. TPhP has been found to be neurotoxic upon developmental exposure, yet the specific mechanism remains unclear. To characterize the cellular responses underlying TPhP-induced developmental neurotoxicity, we administered TPhP (0.5, 5 or 50 mg/kg/day) to neonatal mice from postnatal day 10 (P10)-P70. A total of 17,229 cells and 26,338 genes were identified in cortical samples from control and low-dose (the internal doses of metabolite DPhP comparable to human exposure level) groups using single-cell RNA sequencing (scRNA-seq). TPhP exposure led to heterogeneous transcriptional alterations and intercellular crosstalk among neurons, neural stem/progenitor cells (NSPCs), endothelial cells, and immunocytes. Deprivation of NSPCs, loss of mature neurons, and concomitant neuroinflammation mediated by extrinsic and intrinsic immunocytes were found in TPhP-exposed cortices. In addition, we observed blood-brain barrier destruction prior to the anxiety/depression-like neurobehavioral changes. These results reveal the distinctive cellular processes in TPhP's neurodevelopmental toxicity and uncover that the impeded neurogenesis, disrupted vascular barrier, and concomitant neuroinflammation are the sensitive responses to TPhP exposure. Our study paves the way for the application of scRNA-seq in toxicity assessments for emerging neurotoxic pollutants.

Low-Intensity Focused Ultrasound Technique in Glioblastoma Multiforme Treatment

Glioblastoma is one of the central nervous system most aggressive and lethal cancers with poor overall survival rate. Systemic treatment of glioblastoma remains the most challenging aspect due to the low permeability of the blood-brain barrier (BBB) and blood-tumor barrier (BTB), limiting therapeutics extravasation mainly in the core tumor as well as in its surrounding invading areas. It is now possible to overcome these barriers by using low-intensity focused ultrasound (LIFU) together with intravenously administered oscillating microbubbles (MBs). LIFU is a non-invasive technique using converging ultrasound waves which can alter the permeability of BBB/BTB to drug delivery in a specific brain/tumor region. This emerging technique has proven to be both safe and repeatable without causing injury to the brain parenchyma including neurons and other structures. Furthermore, LIFU is also approved by the FDA to treat essential tremors and Parkinson's disease. It is currently under clinical trial in patients suffering from glioblastoma as a drug delivery strategy and liquid biopsy for glioblastoma biomarkers. The use of LIFU+MBs is a step-up in the world of drug delivery, where onco-therapeutics of different molecular sizes and weights can be delivered directly into the brain/tumor parenchyma. Initially, several potent drugs targeting glioblastoma were limited to cross the BBB/BTB; however, using LIFU+MBs, diverse therapeutics showed significantly higher uptake, improved tumor control, and overall survival among different species. Here, we highlight the therapeutic approach of LIFU+MBs mediated drug-delivery in the treatment of glioblastoma.

RGMa Participates in the Blood-Brain Barrier Dysfunction Through BMP/BMPR/YAP Signaling in Multiple Sclerosis

The infiltration of inflammatory cells into the central nervous system (CNS) through the dysfunctional blood–brain barrier (BBB) was critical in the early stages of MS. However, the mechanisms underlying BBB dysfunction remain unknown. Repulsive guidance molecule-a (RGMa) is involved in the pathogenesis of multiple sclerosis (MS), but its role needs to be further explored. This study aimed to evaluate whether RMGa regulates BBB permeability in endothelial cells and MS, and if so, what mechanism may be involved. We created an experimental autoimmune encephalomyelitis (EAE) model in C57BL/6 mice and a human brain microvascular endothelial cell (HBMEC) culture. The permeability of the BBB is measured in response to various interventions. Our results showed that RGMa is expressed in the endothelial cells in HBMECs and EAE mice. RGMa and its signaling counterpart, bone morphogenetic protein 2 (BMP2)/bone morphogenetic protein receptor type II (BMPRII), were gradually increased as the disease progressed. Moreover, as EAE progressed and the BBB was disrupted, the downstream effector, yes-associated protein (YAP), as well as the tight junctional proteins zonula occludens 1 (ZO-1) and claudin-5, decreased significantly. The permeability assay revealed that lentivirus-induced RGMa overexpression in HBMECs caused a significant breakdown of the BBB, whereas RGMa knockdown significantly strengthens the integrity of the BBB. Furthermore, specifically activating BMPR II or inhibiting YAP based on RGMa knockdown results in a significant decrease of ZO-1 and claudin-5 in vitro. On the contrary, inhibition of BMPR II or activation of YAP after upregulating RGMa prevents the downregulation of ZO-1 and claudin-5 in HBMECs. In addition, serum-soluble RGMa (sRGMa) levels were significantly higher in MS patients, particularly in MS patients with Gd⁺ lesions, indicating that the BBB has been disrupted. In conclusion, this study shows that RGMa causes BBB dysfunction in endothelial cells via BMP2/BMPR II/YAP, resulting in BBB integrity disruption in MS and that it could be a novel therapeutic target for BBB permeability in MS.

Diprotin A TFA Exerts Neurovascular Protection in Ischemic Cerebral Stroke

Background

It has been established that the dipeptidyl peptidase-4 (DPP-4) inhibitor Diprotin A TFA can reduce vascular endothelial (VE)-cadherin disruption by inhibiting the increase in cleaved β-catenin in response to hypoxia, thereby protecting the vascular barrier of human umbilical vein endothelial cells. In this study, we sought to investigate the possible effect of Diprotin A TFA on the VE barrier after cerebral ischemic stroke in mice.

Methods

C57BL/6J mice were divided into five groups, namely, (1) sham, (2) stroke, (3) stroke + dimethyl sulfoxide (DMSO), (4) stroke + Diprotin A TFA, and (5) stroke + Diprotin A TFA + XAV-939. First, the cerebral ischemia model was established by photothrombotic ischemia, followed by intraperitoneal injection with Diprotin A TFA and XAV-939 at doses of 70 μg/kg and 40 mg/kg 30 min once in the morning and once in the evening for 3 days. Immunofluorescence staining and Western blot methods were used to analyze the expression of vascular and blood-brain barrier (BBB)-associated molecular markers in the peri-infarct area.

Results

Compared with the vehicle control group, we found that mice injected with Diprotin A TFA exhibited reduced cerebral infarction volume, increased vascular area and length around the brain injury, increased pericyte and basement membrane coverage, upregulated expression of BBB tight junction proteins, and improved their BBB permeability, whereas the group injected with both drug and inhibitor exhibited significantly aggravated vascular injury and BBB permeability.

Conclusion

Diprotin A TFA can reduce VE-cadherin disruption by inhibiting ischemia-hypoxia-induced β-catenin cleavage to protect blood vessels.

A Calixarene Assembly Strategy of Combined Anti-Neuroinflammation and Drug Delivery Functions for Traumatic Brain Injury Therapy

Excessive inflammatory reaction aggravates brain injury and hinders the recovery of neural function in nervous system diseases. Microglia, as the major players of neuroinflammation, control the progress of the disease. There is an urgent need for effective non-invasive therapy to treat neuroinflammation mediated by microglia. However, the lack of specificity of anti-inflammatory agents and insufficient drug dose penetrating into the brain lesion area are the main problems. Here, we evaluated a series of calixarenes and found that among them the self-assembling architecture of amphiphilic sulfonatocalix[8]arene (SC8A12C) had the most potent ability to suppress neuroinflammation in vitro and in vivo. Moreover, SC8A12C assemblies were internalized into microglia through macropinocytosis. In addition, after applying the SC8A12C assemblies to the exposed brain tissue, we observed that SC8A12C assemblies penetrated into the brain parenchyma and eliminated the inflammatory factor storm, thereby restoring neurobiological functions in a mouse model of traumatic brain injury.

Melatonin Alleviates Venous Dysfunction in a Mouse Model of Iliac Vein Occlusion

The iliac vein can be severely stenosed and occluded due to thrombosis, tumor compression, or an anatomical abnormality. Such occlusion could result in limb swelling, venous claudication, and persistent leg ulcers. Its devastating sequelae heavily impact patients lifestyles and the social economy. Due to a lack of a stable and easy-to-operate iliac vein occlusion (IVO) model, its underlying molecular mechanism and pathophysiological process has not been completely understood. Melatonin (MLT) plays a critical role in anti-inflammation, but the potential protective effect of melatonin on venous dysfunction induced by IVO has not been revealed. In this study, a mouse model of IVO was established to study the effects of MLT on injured veins. The results of laser speckle images and Evans blue showed that MLT inhibited venous permeability in an IVO mouse model. Furthermore, MLT suppressed inflammation of surrounding tissues close to the affected vein by inhibiting the mRNA levels of TNF-α, IL-1α, and MCP-1. In addition, endothelial injury was inhibited by MLT using zonula occludens protein-1 (ZO-1) staining. Taken together, we elucidated the therapeutic effect of MLT on vascular dysfunction induced by IVO, mainly by inhibiting the TNF-α, IL-1α, and MCP-1 mRNA levels, improving endothelial function, and inhibiting vascular leakage.

RORγt-Expressing Pathogenic CD4+ T Cells Cause Brain Inflammation during Chronic Colitis

Neurobehavioral disorders and brain abnormalities have been extensively reported in both Crohn's disease and ulcerative colitis patients. However, the mechanism causing neuropathological disorders in inflammatory bowel disease patients remains unknown. Studies have linked the Th17 subset of CD4⁺ T cells to brain diseases associated with neuroinflammation and cognitive impairment, including multiple sclerosis, ischemic brain injury, and Alzheimer's disease. To better understand how CD4⁺ T lymphocytes contribute to brain pathology in chronic intestinal inflammation, we investigated the development of brain inflammation in the T cell transfer model of chronic colitis. Our findings demonstrate that CD4⁺ T cells infiltrate the brain of colitic Rag1 ^-/- mice in proportional levels to colitis severity. Colitic mice developed hypothalamic astrogliosis that correlated with neurobehavioral disorders. Moreover, the brain-infiltrating CD4⁺ T cells expressed Th17 cell transcription factor retinoic acid-related orphan receptor γt (RORγt) and displayed a pathogenic Th17 cellular phenotype similar to colonic Th17 cells. Adoptive transfer of RORγt-deficient naive CD4⁺ T cells failed to cause brain inflammation and neurobehavioral disorders in Rag1 ^-/- recipients, with significantly less brain infiltration of CD4⁺ T cells. The finding is mirrored in chronic dextran sulfate sodium-induced colitis in Rorc^fl/fl Cd4-Cre mice that showed lower frequency of brain-infiltrating CD4⁺ T cells and astrogliosis despite onset of significantly more severe colitis compared with wild-type mice. These findings suggest that pathogenic RORγt⁺CD4⁺ T cells that aggravate colitis migrate preferentially into the brain, contributing to brain inflammation and neurobehavioral disorders, thereby linking colitis severity to neuroinflammation.

Astaxanthin, a carotenoid antioxidant, pretreatment alleviates cognitive deficits in aircraft noised mice by attenuating inflammatory and oxidative damage to the gut, heart and hippocampus

BACKGROUND

We first explore whether aircraft noise (AN) induces cognitive deficit via inducing oxidative damage in multiple vital organs including intestines, hearts and hippocampus tissues. Second, we explore whether the AN-induced cognitive deficits and inflammatory and oxidative damage to multiple organs can be alleviated by Astaxanthin (AX) pretreatment.

METHODS

Cognitive deficits were induced by subjecting the mice to AN 2 h daily for 7 consecutive days. An intragastrical dose of AX emulsifier (at the dose of daily feed intake [6 g] of a mouse three times weekly) was given to mice for consecutive 8 weeks prior to the start of AN. Cognitive functions were evaluated by using passive avoidance apparatus, Y-maze, Morris water maze and novel recognition test. Intestinal permeability was determined by measuring the intestinal clearance of fluorescein-isothiocyante. Evans Blue extravasation assay was used to measure the permeability of blood-brain-barrier. Inflammatory and oxidative damage to multiple organs were determined by measuring several pro-inflammatory cytokines and oxidative stress indicators in intestines; hearts and hippocampus.

RESULTS

Mice treated with AN displayed exacerbated stress reactions, cognitive deficits, gut barrier hyperpermeability, increased upload of lipopolysaccharide translocation, systemic pro-inflammatory cytokines overproduction, blood-brain-barrier hyperpermeability, hippocampal neuroinflammation and increased levels of oxidative stress indicators in intestine, heart and hippocampus. All of the above-mentioned disorders caused by AN were significantly (P < 0.05) reversed by AX.

CONCLUSIONS

Our data indicate that AX pretreatment alleviates cognitive deficits in aircraft noised mice by attenuating inflammatory and oxidative damage to intestines, hearts and hippocampal tissues.

Effects of Diosmin on Vascular Leakage and Inflammation in a Mouse Model of Venous Obstruction

At present, iliac vein compression syndrome (IVCS) plagues countless people, posing a significant economic and social burden. The progress of current IVCS-related research is slow owing to the limitations of animal models. In this study, we generated a mouse model of iliac vein stenosis (IVS) to monitor the effects of IVCS on venous function, such as increased vascular leakage, the expression of adhesion molecules, and elevated inflammation factors. Diosmin, a widely used clinical bioactive ingredient, was administered to confirm its therapeutic effects on the IVS mouse model. The results revealed that diosmin manifested therapeutic improvement in the IVS mouse model. In addition, we verified that the IVS mouse model is a stable and reproducible animal model for pathophysiological studies. High-purity diosmin can be beneficial to venous dysfunction and hence provides a more effective treatment option for venous diseases.

Sirtuin-1 - Mediated NF-κB Pathway Modulation to Mitigate Inflammasome Signaling and Cellular Apoptosis is One of the Neuroprotective Effects of Intra-arterial Mesenchymal Stem Cell Therapy Following Ischemic Stroke

AIM

Stroke results in long term serious disability that affect millions across the globe. Several clinical and preclinical studies have reinforced the therapeutic use of stem cells in stroke patients to enhance their quality of life. Previous studies from our lab have demonstrated that 1*10⁵ allogeneic bone marrow-derived mesenchymal stem cells (BM-MSCs) when given intraarterially (IA) render neuroprotection by modulating the expression of inflammasomes. Sirtuins are a class of important deacylases having a significant role in cellular functioning. Sirtuin-1 (SIRT-1) is an important enzyme essential for regulating cellular metabolism, which is reduced following an ischemic episode. The present study aims to unviel the role of MSCs in regulating the brain SIRT-1 levels following stroke and the involvement of SIRT-1 in regulating inflammasome signaling to reduce cellular apoptosis towards rendering neuroprotection.

MATERIALS AND METHODS

6 h post-reversible middle cerebral artery occlusion (MCAo), ovariectomized Sprague Dawley (SD) rats were infused intraarterially with 1*10⁵ MSCs. 24 h after MCAo animals were examined for functional and behavioral outcomes. Brains were collected for assessing size of infarct and neuronal morphology. Molecular and immunofluroscence studies were also performed for assessing changes in gene and protein expressions. Extent of apoptosis was also determined in different groups. Inhibition study with SIRT-1 specific inhibitor EX-527 was also performed.

RESULTS

A reduction in infarct size and improvement in motor functional and behavioral outcomes following infusion of MSCs IA at 6 h post-stroke was observed. Increase in average neuronal density and neuronal length was also seen. Increased expression of SIRT-1, BDNF and concomitant reduction in the expression of different inflammatory and apoptotic markers in the brain cortical regions were observed following MSCs treatment.

CONCLUSION

Our study provides a preliminary evidence that post-stroke IA MSCs therapy regulates SIRT-1 to modulate NF-κB pathway to mitigate inflammasome signaling and cellular apoptosis. This study using IA approach for administering MSCs is highly relevant clinically. Our study is the first to report that neuroprotective effects of IA MSCs in rodent focal ischemia is mediated by SIRT-1 regulation of inflammasome signaling.

Evidence of Microglial Immune Response Following Coronavirus PHEV Infection of CNS

Porcine hemagglutinating encephalomyelitis virus (PHEV) is a highly neurotropic coronavirus that invades the host central nervous system (CNS) and causes neurological dysfunction. Microglia are key immune cells in the CNS, however, whether and how they response to PHEV infection remains unclear. Herein, microglial activation and proliferation were detected in the CNS of PHEV-infected mice, as along with the proinflammatory response. Moreover, the production of proinflammatory cytokines induced by moderately activated microglia limited viral replication in the early stage of infection. Microglial depletion assays showed that during late infection, excess activation of microglia aggravated neurological symptoms, BBB destruction, and peripheral monocyte/macrophage infiltration into the CNS. Using an in vitro brain slice model, PHEV was identified to specifically and moderately induce microglial activation in the absence of peripheral immune cells infiltration. Consistently, macrophage clearance from circulating blood indicated that peripheral monocytes/macrophages crossing the BBB of mice were responsible for excess activation of microglia and CNS damage in late PHEV infection. Overall, our findings provide evidence supporting a dual role for microglia in the host CNS in response to coronavirus PHEV invasion.

Mechanisms of the host immune response and helminth-induced pathology during Trichobilharzia regenti (Schistosomatidae) neuroinvasion in mice

Helminth neuroinfections represent serious medical conditions, but the diversity of the host-parasite interplay within the nervous tissue often remains poorly understood, partially due to the lack of laboratory models. Here, we investigated the neuroinvasion of the mouse spinal cord by Trichobilharzia regenti (Schistosomatidae). Active migration of T. regenti schistosomula through the mouse spinal cord induced motor deficits in hindlimbs but did not affect the general locomotion or working memory. Histological examination of the infected spinal cord revealed eosinophilic meningomyelitis with eosinophil-rich infiltrates entrapping the schistosomula. Flow cytometry and transcriptomic analysis of the spinal cord confirmed massive activation of the host immune response. Of note, we recorded striking upregulation of the major histocompatibility complex II pathway and M2-associated markers, such as arginase or chitinase-like 3. Arginase also dominated the proteins found in the microdissected tissue from the close vicinity of the migrating schistosomula, which unselectively fed on the host nervous tissue. Next, we evaluated the pathological sequelae of T. regenti neuroinvasion. While no demyelination or blood-brain barrier alterations were noticed, our transcriptomic data revealed a remarkable disruption of neurophysiological functions not yet recorded in helminth neuroinfections. We also detected DNA fragmentation at the host-schistosomulum interface, but schistosomula antigens did not affect the viability of neurons and glial cells in vitro. Collectively, altered locomotion, significant disruption of neurophysiological functions, and strong M2 polarization were the most prominent features of T. regenti neuroinvasion, making it a promising candidate for further neuroinfection research. Indeed, understanding the diversity of pathogen-related neuroinflammatory processes is a prerequisite for developing better protective measures, treatment strategies, and diagnostic tools.

miR-539 Targeting SNAI2 Regulates MMP9 Signaling Pathway and Affects Blood-Brain Barrier Permeability in Cerebrovascular Occlusive Diseases: A Study Based on Head and Neck Ultrasound and CTA

This study aimed to explore the expression level of miR-539 in the blood-brain barrier permeability induced by cerebrovascular occlusion and its mediated mechanism. Altogether, 48 patients with cerebral vascular occlusion lesions from March 2018 to June 2020 were collected. The expression level of miR-539 in the peripheral blood serum of the subjects was analyzed by qRT-PCR, and the participants were divided into two groups according to the results of head and neck ultrasound and CTA hemodynamics. The MCAO model of cerebral ischemia was established in rats, and the expression level of miR-539 was detected by qRT-PCR in brain tissues of different groups of rats. The effects of miR-539 on the permeability of blood-brain barrier were investigated by intraventricular injection of agomiR-539 and antagomir-539. The model of blood-brain barrier was established by culturing brain microvascular endothelial cells and pericytes in vitro, and the changes of miR-539 expression level and permeability after glucose and oxygen deprivation were detected. The expression level of SNAI2/MMP9 signaling pathway protein in cells was detected by Western blot. Compared with the healthy control group, the expression level of miR-539 in peripheral blood of patients with cerebrovascular occlusive disease decreased significantly, and the expression level of miR-539 in the MCAO rat model decreased and affected the permeability of blood-brain barrier. Glucose and oxygen deprivation treatment in brain microvascular endothelial cells can lead to downregulation of miR-539 expression and affect cell permeability. miR-539 in brain microvascular endothelial cells can target and bind to SNAI2 and participate in the regulation of endothelial cell permeability by affecting the SNAI2/MMP9 signaling pathway. The results of this study suggested that circulating miR-539 in peripheral blood may be a potential marker for predicting blood-brain barrier permeability after ischemic stroke. More detailed studies are needed to determine its diagnostic value.

Blood-Brain Barrier Permeability: Is 5-Hydroxytryptamine Receptor Type 4 a Game Changer?

Serotonin affects many functions in the body, both in the central nervous system (CNS) and the periphery. However, its effect on the blood–brain barrier (BBB) in separating these two worlds has been scarcely investigated. The aim of this work was to characterize the serotonin receptor 5-HT₄ in the hCMEC/D3 cell line, in the rat and the human BBB. We also examined the effect of prucalopride, a 5-HT₄ receptor agonist, on the permeability of the hCMEC/D3 in an in vitro model of BBB. We then confirmed our observations by in vivo experiments. In this work, we show that the 5-HT₄ receptor is expressed by hCMEC/D3 cells and in the capillaries of rat and human brains. Prucalopride increases the BBB permeability by downregulating the expression of the tight junction protein, occludin. This effect is prevented by GR113808, a 5-HT₄ receptor antagonist, and is mediated by the Src/ERK1/2 signaling pathway. The canonical G-protein-dependent pathway does not appear to be involved in this phenomenon. Finally, the administration of prucalopride increases the diffusion of Evans blue in the rat brain parenchyma, which is synonymous with BBB permeabilization. All these data indicate that the 5-HT₄ receptor contributes to the regulation of BBB permeability.

Endovascular Stem Cell Therapy Post Stroke Rescues Neurons from Endoplasmic Reticulum Stress-Induced Apoptosis by Modulating Brain-Derived Neurotrophic Factor/Tropomyosin Receptor Kinase B Signaling

Ischemic stroke is devastating, with serious long-term disabilities affecting millions of people worldwide. Growing evidence has shown that mesenchymal stem cells (MSCs) administration after stroke provides neuroprotection and enhances the quality of life in stroke patients. Previous studies from our lab have shown that 1 × 10⁵ MSCs administered intra-arterially (IA) at 6 h post stroke provide neuroprotection through the modulation of inflammasome and calcineurin signaling. Ischemic stroke induces endoplasmic reticulum (ER) stress, which exacerbates the pathology. The current study intends to understand the involvement of brain-derived neurotrophic factor/tropomyosin receptor kinase B (BDNF/TrkB) signaling in preventing apoptosis induced by ER stress post stroke following IA MSCs administration. Ischemic stroke was induced in ovariectomized female Sprague Dawley rats. The MSCs were administered IA, and animals were sacrificed at 24 h post stroke. Infarct area, neurological deficit score, motor coordination, and biochemical parameters were evaluated. The expression of various genes and proteins was assessed. An inhibition study was also carried out to confirm the involvement of BDNF/TrkB signaling in ER stress-induced apoptosis. IA-administered MSCs improved functional outcomes, reduced infarct area, increased neuronal survival, and normalized biochemical parameters. mRNA and protein expression of ER stress markers were reduced, while those of BDNF and TrkB were increased. Reduction in ER stress-mediated apoptosis was also observed. The present study shows that IA MSCs administration post stroke provides neuroprotection and can modulate ER stress-mediated apoptosis via the BDNF/TrkB signaling pathway.

Utilizing the Faxitron MultiRad 225 X-ray irradiation system for the construction of mouse chronic whole brain radiation model

Radiation-induced brain injury (RBI) is a common complication of radiotherapy for head and neck tumors while its mechanism is not fully understood. Animal whole-brain radiation (WBR) models are of key importance in experimental radiation research, and an appropriate radiation source is essential. Previous animal WBR models were administered by clinical linear accelerator to induce the pathophysiological changes of RBI. In the current study, we adopted Faxitron MultiRad 225 X-ray irradiation system to construct a mouse WBR model with a single dose of 30 Gy. In the acute phase of this mouse WBR model, brain edema and blood-brain barrier (BBB) damage were found mild. However, two months later, the results of immunofluorescence showed that astrocytes and microglia were activated continuously, and the number of immature neurons in dentate gyrus (DG) area of hippocampus was significantly reduced, in accordance with the features of chronic pathophysiological changes. Besides, data of MRI scans and behavior tests illustrated the structural changes of brain tissue and cognitive impairment in the chronic phase. To sum up, this mouse WBR model using the Faxitron MultiRad 225 irradiation system with a single dose of 30 Gy is feasible to simulate the RBI-related chronic pathophysiological changes.

Neutrophil Extracellular Traps Exacerbate Secondary Injury via Promoting Neuroinflammation and Blood-Spinal Cord Barrier Disruption in Spinal Cord Injury

As the first inflammatory cell recruited to the site of spinal cord injury (SCI), neutrophils were reported to be detrimental to SCI. However, the precise mechanisms as to how neutrophils exacerbate SCI remain largely obscure. In the present study, we demonstrated that infiltrated neutrophils produce neutrophil extracellular traps (NETs), which subsequently promote neuroinflammation and blood–spinal cord barrier disruption to aggravate spinal cord edema and neuronal apoptosis following SCI in rats. Both inhibition of NETs formation by peptidylarginine deiminase 4 (PAD4) inhibitor and disruption of NETs by DNase 1 alleviate secondary damage, thus restraining scar formation and promoting functional recovery after SCI. Furthermore, we found that NETs exacerbate SCI partly via elevating transient receptor potential vanilloid type 4 (TRPV4) level in the injured spinal cord. Therefore, our results indicate that NETs might be a promising therapeutic target for SCI.