Microglia and astrocytes mediate synapse engulfment in a MER tyrosine kinase-dependent manner after traumatic brain injury

Recent studies have shown that microglia/macrophages and astrocytes can mediate synaptic phagocytosis through the MER proto-oncokinase in developmental or stroke models,but it is unclear whether the same mechanism is also active in traumatic brain injury.In this study,we established a mouse model of traumatic brain injury and found that both microglia/macrophages and astrocytes phagocytosed synapses and expression of the MER proto-oncokinase increased 14 days after injury.Specific knockout of MER in microglia/macrophages or astrocytes markedly reduced injury volume and greatly improved neurobehavioral function.In addition,in both microglia/macrophages-specific and astrocytes-specific MER knock-out mice,the number of microglia/macrophage and astrocyte phagocytosing synapses was markedly decreased,and the total number of dendritic spines was increased.Our study suggested that MER proto-oncokinase expression in microglia/macrophages and astrocytes may play an important role in synaptic phagocytosis,and inhibiting this process could be a new strategy for treating traumatic brain injury.

Transcranial focused ultrasound stimulation reduces vasogenic edema after middle cerebral artery occlusion in mice

Blood-brain barrier(BBB)disruption underlies the vasogenic edema and neuronal cell death induced by acute ischemic stroke.Reducing this disruption has therapeutic potential.Transcranial focused ultrasound stimulation has shown neuromodulatory and neuroprotective effects in various brain diseases including ischemic stroke.Ultrasound stimulation can reduce inflammation and promote angiogenesis and neural circuit remodeling.However,its effect on the BBB in the acute phase of ischemic stroke is unknown.In this study of mice subjected to middle cerebral artery occlusion for 90 minutes,low-intensity low-frequency(0.5 MHz)transcranial focused ultrasound stimulation was applied 2,4,and 8 hours after occlusion.Ultrasound stimulation reduced edema volume,improved neurobehavioral outcomes,improved BBB integrity(enhanced tight junction protein ZO-1 expression and reduced IgG leakage),and reduced secretion of the inflammatory factors tumor necrosis factor-αand activation of matrix metalloproteinase-9 in the ischemic brain.Our results show that low-intensity ultrasound stimulation attenuated BBB disruption and edema formation,which suggests it may have therapeutic use in ischemic brain disease as a protector of BBB integrity.

Click chemistry extracellular vesicle/peptide/chemokine nanocarriers for treating central nervous system injuries

Central nervous system(CNS)injuries,including stroke,traumatic brain injury,and spinal cord injury,are essential causes of death and long-term disability and are difficult to cure,mainly due to the limited neuron regeneration and the glial scar formation.Herein,we apply extracellular vesicles(EVs)secreted by M2 microglia to improve the differentiation of neural stem cells(NSCs)at the injured site,and simultaneously modify them with the injured vascular targeting peptide(DA7R)and the stem cell recruiting factor(SDF-1)on their surface via copper-free click chemistry to recruit NSCs,inducing their neuronal differentiation,and serving as the nanocarriers at the injured site(Dual-EV).Results prove that the Dual-EV could target human umbilical vascular endothelial cells(HUVECs),recruit NSCs,and promote the neuronal differentiation of NSCs in vitro.Furthermore,10 miRNAs are found to be upregulated in Dual-M2-EVs compared to Dual-M0-EVs via bioinformatic analysis,and further NSC differentiation experiment by flow cytometry reveals that among these miRNAs,miR30b-3p,miR-222-3p,miR-129-5p,and miR-155-5p may exert effect of inducing NSC to differentiate into neurons.In vivo experiments show that Dual-EV nanocarriers achieve improved accumulation in the ischemic area of stroke model mice,potentiate NSCs recruitment,and increase neurogenesis.This work provides new insights for the treatment of neuronal regeneration after CNS injuries as well as endogenous stem cells,and the click chemistry EV/peptide/chemokine and related nanocarriers for improving human health.

Deposition of TiN/TiAlN multilayers by plasma-activated EB-PVD:tailored microstructure by jumping beam technology

Plasma-activated electron beam-physical vapor deposition（EB-PVD）was used for depositing nitride multilayer coatings in this work.Different from the conventional coating methods,the multilayers were obtained by manipulating electron beam（EB）to jump between two different evaporation sources alternately with variable frequencies（jumping beam technology）.The plasma activation was generated by a hollow cathode plasma unit.The deposition process was demonstrated by means of tailoring TiN/TiAlN multilayers with different modulation periods（M1：26.5 nm,M2：80.0 nm,M3：6.0 nm,M4：4.0 nm）.The microstructure and hardness of the multilayer coatings were comparatively studied with TiN and TiAlN singlelayer coatings.The columnar structure of the coatings（TiN,TiAlN,M1,M2）is replaced by a glassy-like microstructure when the modulation period decreases to less than 10 nm（M3,M4）.Simultaneously,superlattice growth occurs.With the decrease of modulation period,both the hardness and the plastic deformation resistance（H^3/E^2,H-hardness and E-elastic modulus）increase.M4coating exhibits the maximum hardness of（49.6±2.7）GPa and the maximum plastic deformation resistance of^0.74 GPa.

Arterial stiffness and stroke:de-stiffening strategy,a therapeutic target for stroke

Stroke is the second leading cause of mortality and morbidity worldwide.Early intervention is of great importance in reducing disease burden.Since the conventional risk factors cannot fully account for the pathogenesis of stroke,it is extremely important to detect useful biomarkers of the vascular disorder for appropriate intervention.Arterial stiffness,a newly recognised reliable feature of arterial structure and function,is demonstrated to be associated with stroke onset and serve as an independent predictor of stroke incidence and poststroke functional outcomes.In this review article,different measurements of arterial stiffness,especially pressure wave velocity,were discussed.We explained the association between arterial stiffness and stroke occurrence by discussing the secondary haemodynamic changes.We reviewed clinical data that support the prediction role of arterial stiffness on stroke.Despite the lack of long-term randomised double-blind controlled therapeutic trials,it is high potential to reduce stroke prevalence through a significant reduction of arterial stiffness(which is called de-stiffening therapy).Pharmacological interventions or lifestyle modification that can influence blood pressure,arterial function or structure in either the short or long term are promising de-stiffening therapies.Here,we summarised different de-stiffening strategies including antihypertension drugs,antihyperlipidaemic agents,chemicals that target arterial remodelling and exercise training.Large and well-designed clinical trials on de-stiffening strategy are needed to testify the prevention effect for stroke.Novel techniques such as modern microscopic imaging and reliable animal models would facilitate the mechanistic analyses in pathophysiology,pharmacology and therapeutics.

Decreased expression of gap junction delta-2 (GJD2) messenger RNA and connexin 36 protein in form-deprivation myopia of guinea pigs

Background:More than ten genome-wide association studies have identified the significant association between the gap junction delta-2 (GJD2) gene and myopia.However,no functional studies have been performed to confirm that this gene is correlated with myopia.This study aimed to observe how this gene changed in mRNA and protein level in the form-deprivation myopia (FDM) animal model.Methods:Four-week-old guinea pigs were randomly divided into two groups:control and FDM groups (n =12 for each group).The right eyes of the FDM group were covered with opaque hemispherical plastic lenses for 3 weeks.For all the animals,refractive status,axial length (AL),and corneal radius of curvature were measured at baseline and 3 weeks later by streak retinoscope,A-scan ultrasonography,and keratometer,respectively.Retinal GJD2 mRNA expression and connexin 36 (Cx36) levels in FDM and control groups were measured by quantitative real-time PCR and Western blot analyses,respectively.Those results were compared using independent t test,Mann-Whitney U test,or paired t test.A significance level of P < 0.05 was used.Results:Three weeks later,the FDM group (form-deprived eyes) showed about a myopic shift of approximately-6.75 (-7.94 to -6.31) D,while the control group remained hyperopic with only a shift of-0.50 (-0.75 to 0.25) D (Z =-3.38,P < 0.01).The AL increased by 0.74 (0.61-0.76) and 0.10 (0.05-0.21) mm in FDM and control groups,respectively (Z =-3.37,P < 0.01).The relative mRNA expression of GJD2 in the FDM group decreased 31.58% more than the control group (t =11.44,P < 0.01).The relative protein expression of CX36 on the retina was lowered by 37.72% in form-deprivation eyes as compared to the controls (t=17.74,P < 0.01).Conclusion:Both the mRNA expression of GJD2 and Cx36 protein amount were significantly decreased in the retina of FDM guinea pigs.This indicates that Cx36 is involved in FDM development,providing compensating evidence for the results obtained from genome-wide association studies.

Therapeutic application of exosomes in ischaemic stroke

Ischaemic stroke is a leading cause of long-term disability in the world,with limited effective treatments.Increasing evidence demonstrates that exosomes are involved in ischaemic pathology and exhibit restorative therapeutic effects by mediating cell–cell communication.The potential of exosome therapy for ischaemic stroke has been actively investigated in the past decade.In this review,we mainly discuss the current knowledge of therapeutic applications of exosomes from different cell types,different exosomal administration routes,and current advances of exosome tracking and targeting in ischaemic stroke.We also briefly summarised the pathology of ischaemic stroke,exosome biogenesis,exosome profile changes after stroke as well as registered clinical trials of exosome-based therapy.

Plasma from healthy donors protects blood-brain barrier integrity via FGF21 and improves the recovery in a mouse model of cerebral ischaemia

Background Healthy plasma therapy reverses cognitive deficits and promotes neuroplasticity in ageing brain disease.However,whether healthy plasma therapy improve blood-brain barrier integrity after stroke remains unknown.Methods Here,we intravenously injected healthy female mouse plasma into adult female ischaemic stroke C57BL/6 mouse induced by 90 min transient middle cerebral artery occlusion for eight consecutive days.Infarct volume,brain atrophy and neurobehavioural tests were examined to assess the outcomes of plasma treatment.Cell apoptosis,blood-brain barrier integrity and fibroblast growth factor 21 knockout mice were used to explore the underlying mechanism.Results Plasma injection improved neurobehavioural recovery and decreased infarct volume,brain oedema and atrophy after stroke.Immunostaining showed that the number of transferase dUTP nick end labelling+/NeuN+cells decreased in the plasma-injected group.Meanwhile,plasma injection reduced ZO-1,occluding and claudin-5 tight junction gap formation and IgG extravasation at 3 days after ischaemic stroke.Western blot results showed that the FGF21 expression increased in the plasma-injected mice.However,using FGF21 knockout mouse plasma injecting to the ischaemic wild-type mice diminished the neuroprotective effects.Conclusions Our study demonstrated that healthy adult plasma treatment protected the structural and functional integrity of blood-brain barrier,reduced neuronal apoptosis and improved functional recovery via FGF21,opening a new avenue for ischaemic stroke therapy.

Weill-Marchesani-like syndrome caused by an FBN1 mutation with low-penetrance

Weill-Marchesani syndrome(WMS)is a rare connective tissue disorder characterized by brachydactyly,short stature,joint stiffness,cardiovascular abnormalities,and eye anomalies including microspherophakia,cataracts,ectopia lentis,myopia,and secondary glaucoma.Patients with incomplete WMS signs are diagnosed with Weill-Marchesani-like syndrome(WMS-like).To date,both autosomal dominant(AD)and autosomal recessive(AR)inheritance modes have been reported for WMS.Genetic heterogeneity inWMSsuggests a connection between these genes.AR and AD WMS cannot be distinguished clearly by clinical findings alone.[1]Furthermore,inter-familial as well as intra-familial clinical variability due to different fibrillin-1 gene(FBN1)mutations also exists.

Hypoxia-controlled matrix metalloproteinase-9 hyperexpression promotes behavioral recovery after ischemia

Matrix metalloproteinase-9（MMP-9） plays a beneficial role in the sub-acute phase after ischemic stroke.However,unrestrained MMP-9 may disrupt the blood-brain barrier（BBB）,which has limited its use for the treatment of brain ischemia.In the present study,we constructed lentivirus mediated hypoxiacontrolled MMP-9 expression and explored its role after stroke.Hypoxia response element（HRE）was used to confine MMP-9 expression only to the hypoxic region of mouse brain after 120-min transient middle cerebral artery occlusion.Lentiviruses were injected into the peri-infarct area on day 7 after transient ischemia.We found hyperexpression of exogenous HRE-MMP-9 under the control of hypoxia,and its expression was mainly located in neurons and astrocytes without aggravation of BBB damage compared to the CMV group.Furthermore,mice in the HRE-MMP-9 group showed the best behavioral recovery compared with the normal saline,GFP,and SB-3CT groups.Therefore,hypoxia-controlled MMP-9 hyperexpression during the sub-acute phase of ischemia may provide a novel promising approach of gene therapy for stroke.

Overexpression of netrin-1 improves neurological outcomes in mice following transient middle cerebral artery occlusion

Netrin-1(NT-1)is one of the axon-guiding molecules that are critical for neuronal development.Because of its structural homology to the endothelial mitogens,NT-1 may have similar effects on vascular network formation.NT-1 was shown to be able to stimulate the proliferation and migration of human cerebral endothelial cells in vitro and also promote focal neovascularization in adult brain in vivo.In the present study,we reported the delivery of NT-1 using an adeno-associated virus(AAV)vector(AAV-NT-1)into mouse brain followed by transient middle cerebral artery occlusion(tMCAO).We found that AAV vectors did not elicit a detectable inflammatory response,cell loss or neuronal damage after brain transduction.The level of NT-1 was increased in the AAV-NT-1-transduced tMCAO mice compared with the control mice.Furthermore,the neurobehavioral outcomes were significantly improved in AAV-NT-1-transduced mice compared with the control animals(P<0.05)7 days after tMCAO.Our data suggests that NT-1 plays a neuronal function recovery role in ischemic brain and that NT-1 gene transfer might present a valuable approach to treat brain ischemic disorders.

Intraorbital Granular Cell Tumor Involving in Medial Rectus and Optic Nerve

To the Editor： Here, we present a rare case whose medial rectus and optic nerve in the left eye are both affected by intraorbital granular cell tumor （GCT）. Macroscopic size of the mass was around 4.3 cm×2.2 cm ×1.8 cm.

MicroRNA-126 is a prospective target for vasculardisease

MicroRNA-126 was involved in angiogenesis during physiological and pathological process. It was mainly expressed in endothelial cells, and defined as a pivotal biological molecule associated with vascular disease. Increased microRNA-126 in endothelial cells promotes angiogenesis in ischemic stroke, repairs impaired endothelial cells in atherosclerosis, and attenuates vascular dysfunction in diabetics. By contrast, microRNA-126 transferred from endothelial cell to smooth muscle cells could lead to proliferation that induced intimal hyperplasia. Additionally, microRNA-126 could be a tumor suppressor or an oncogene, which was depended on the cancer type. In this review, we summarized the function of microRNA-126 in ischemic stroke, atherosclerosis, diabetics, tumor, and discussed the underlying mechanisms.

Advancement in stroke research

Stroke is the second most common cause of death in the world especially in the ageing population.1 Thrombolysis and intravascular embolectomy are the main treatment and populated rapidly.23 However,the benefi-ciary is still limited because the mechanistic studies are behind.The basic research on stroke is improved because of new devices,novel techniques and the development of other disciplines.4 The update of a broad range of topics related to stroke is a widely appreciated feature.In order to improve the understanding of cellular and molecular mechanisms of stroke,the 2nd Summit of Chinese Basic Science Research on Stroke 2018 has been held in Beijing,China.

Effect of ischaemic brain injury on sexual function in adult mice

Objective:Priapism refers to a condition with persistent abnormal erection of the penis,which is usually caused by disease or injury in the brain or spinal cord,or obstruction to the outflow of blood through the dorsal vein at the root of the penis,without sexual desires.The effect of cerebral ischaemia on sexual function is unknown.The aim of this study is to explore whether priapism occurs in adult mice.Furthermore,we examined the relationship between priapism and the region of infarct in the brain.Design:Adult male CD-1 mice who underwent permanent middle cerebral artery occlusion(pMCAO)were closely examined from 2 hours to 14 days postoperation.Results:We found that priapism occurs in∼80%of the mice with pMCAO,which could persist up to 14 days.Further study has demonstrated that the occurrence of priapism is related to the infarct region:priapism is found only in mice with ischaemic injury extending to the hypothalamus and the hippocampus regions.Conclusion:Our result suggested priapism may be used as a deep brain injury marker for evaluating brain injury in mice after pMCAO.