ChemR23 signaling ameliorates brain injury via inhibiting NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke.

BACKGROUND: Inflammatory response has been recognized as a pivotal pathophysiological process during cerebral ischemia. ChemR23 signaling is involved in the pathophysiology of various inflammatory diseases. Nevertheless, the role of ChemR23 signaling in ischemic stroke remains largely unknown. METHODS: Permanent ischemic stroke mouse model was accomplished by middle cerebral artery occlusion (MCAO). Resolvin E1 (RvE1) or chemerin-9 (C-9), the agonists of ChemR23, were administered by intracerebroventricular (i.c.v) injection before MCAO induction. Then, analysis of neurobehavioral deficits and brain sampling were done at Day 1 after MCAO. The brain samples were further analyzed by histological staining, immunofluorescence, RNA sequencing, ELISA, transmission electron microscope, and western blots. Furthermore, oxygen-glucose deprivation (OGD) was employed in SH-SY5Y to mimic MCAO in vitro, and ChemR23 signaling pathway was further studied by overexpression of ChemR23 or administration of related agonists or antagonists. Analysis of cell death and related pathway markers were performed. RESULTS: ChemR23 expression was upregulated following MCAO. Under in vitro and in vivo ischemic conditions, ChemR23 deficiency or inhibition contributed to excessive NLRP3-mediated maturation and release of IL-1ß and IL-18, as well as enhanced cleavage of GSDMD-N and neuronal pyroptosis. These influences ultimately aggravated brain injury and neuronal damage. On the other hand, ChemR23 activation by RvE1 or C-9 mitigated the above pathophysiological abnormalities in vivo and in vitro, and overexpression of ChemR23 in SH-SY5Y cells also rescued OGD-induced neuronal pyroptosis. Blockade of NLRP3 mimics the protective effects of ChemR23 activation in vitro. CONCLUSION: Our data indicated that ChemR23 modulates NLRP3 inflammasome-mediated neuronal pyroptosis in ischemic stroke. Activation of ChemR23 may serve as a promising potential target for neuroprotection in cerebral ischemia.

Thrombus enhancement sign on CT angiography is associated with the first pass effect of stent retrievers.

BACKGROUND: The thrombus enhancement sign (TES) is thought to be associated with the source of the stroke and thrombus composition. We investigated whether this imaging sign along with other thrombus characteristics could be used to predict the successful first pass effect (FPE) of mechanical thrombectomy. METHODS: 246 consecutive patients with acute ischemic stroke in the anterior circulation with large vessel occlusion who underwent thrombectomy with a stent retriever and clot collection were included. Patients were divided into FPE (modified Thrombolysis in Cerebral Infarction (mTICI) grade 2c or 3)/non-FPE (mTICI 0-2b) and modified FPE (mFPE) (mTICI 2b-3)/non-mFPE (mTICI 0-2a) groups based on flow restoration after the first pass. TES presence, thrombus density, thrombus length, clot burden score, and thrombus composition were compared. The association between FPE and imaging biomarkers, along with clinical and interventional parameters, was investigated by univariate and multivariate analysis. RESULTS: FPE was achieved in 85 (34.6%) patients. TES presence was significantly lower in the FPE group (64.7% vs 80.7% in the non-FPE group, p=0.008) and mFPE group (69.1% vs 81.0% in the non-mFPE group, p=0.039). Histopathological examination revealed that TES (+) thrombi contained a higher fibrin/platelet proportion (50.9% vs 46.9% in TES (-) thrombi, p=0.029) and fewer erythrocytes (43.3% vs 47.3% in TES (-) thrombi, p=0.030). Thrombus characteristics, namely shorter thrombus length (p=0.032), higher erythrocyte proportions (p=0.026), and less fibrin/platelets (p=0.014), were confirmed in patients with FPE. In multivariable analysis, TES was the only independent predictor of FPE failure (OR 0.51, 95% CI 0.28 to 0.94; p=0.031). CONCLUSIONS: TES was independently associated with first pass angiographic failure in patients treated with a stent retriever.

Ubiquitin-binding domain in ABIN1 is critical for regulating cell death and inflammation during development.

ABIN1 is a polyubiquitin-binding protein known to regulate NF-κB activation and cell death signaling. Mutations in Abin1 can cause severe immune diseases in human, such as psoriasis, systemic lupus erythematosus, and systemic sclerosis. Here, we generated mice that disrupted the ubiquitin-binding domain of ABIN1 (Abin1UBD/UBD) died during later embryogenesis owing to TNFR1-mediated cell death, similar to Abin1-/- mice. Abin1UBD/UBD cells were rendered sensitive to TNF-α-induced apoptosis and necroptosis as the inhibition of ABIN1UBD and A20 recruitment to the TNF-RSC complex leads to attenuated RIPK1 deubiquitination. Accordingly, the embryonic lethality of Abin1UBD/UBD mice was rescued via crossing with RIPK1 kinase-dead mice (Ripk1K45A/K45A) or the co-deletion of Ripk3 and one allele of Fadd, but not by the loss of Ripk3 or Mlkl alone. Unexpectedly, Abin1UBD/UBD mice with the co-deletion of Ripk3 and both Fadd alleles died at E14.5. This death was caused by spontaneous RIPK1 ubiquitination-dependent multiple inflammatory cytokines over production and could be rescued by the co-deletion of Ripk1 or Tnfr1 combined with Ifnar. Collectively, these data demonstrate the importance of the ABIN1 UBD domain, which mediates the ABIN1-A20 axis, at limiting RIPK1 activation-dependent cell death during embryonic development. Furthermore, our findings reveal a previously unappreciated ubiquitin pathway that regulates RIPK1 ubiquitination by FADD/Casp8 to suppress spontaneous IKKε/TBK1 activation.

Caspase-8 auto-cleavage regulates programmed cell death and collaborates with RIPK3/MLKL to prevent lymphopenia.

Caspase-8 is an initiator of death receptor-induced apoptosis and an inhibitor of RIPK3-MLKL-dependent necroptosis. In addition, caspase-8 has been implicated in diseases such as lymphoproliferation, immunodeficiency, and autoimmunity in humans. Although auto-cleavage is indispensable for caspase-8 activation, its physiological functions remain poorly understood. Here, we generated a caspase-8 mutant lacking E385 in auto-cleavage site knock-in mouse (Casp8ΔE385/ΔE385). Casp8ΔE385/ΔE385 cells were expectedly resistant to Fas-induced apoptosis, however, Casp8ΔE385/ΔE385 cells could switch TNF-α-induced apoptosis to necroptosis by attenuating RIPK1 cleavage. More importantly, CASP8(ΔE385) sensitized cells to RIPK3-MLKL-dependent necroptosis through promoting complex II formation and RIPK1-RIPK3 activation. Notably, Casp8ΔE385/ΔE385Ripk3-/- mice partially rescued the perinatal death of Ripk1-/- mice by blocking apoptosis and necroptosis. In contrast to the Casp8-/-Ripk3-/- and Casp8-/-Mlkl-/- mice appearing autoimmune lymphoproliferative syndrome (ALPS), both Casp8ΔE385/ΔE385Ripk3-/- and Casp8ΔE385/ΔE385Mlkl-/- mice developed transplantable lymphopenia that could be significantly reversed by RIPK1 heterozygosity, but not by RIPK1 kinase dead mutation. Collectively, these results demonstrate previously unappreciated roles for caspase-8 auto-cleavage in regulating necroptosis and maintaining lymphocytes homeostasis.

Effect of hip fracture on prognosis of acute cerebral infarction.

OBJECTIVES: Hip fractures are a worldwide public health problem. The incidence of hip fracture is high among the elderly, and it is an important cause of death and disability in this population. This observational study aimed to investigate the effect of acute hip fracture on the recovery of neurological function and the prognosis of patients with acute cerebral infarction, as well as whether surgical treatment of combined acute fracture can improve the prognosis of patients. METHODS: Thirty patients with acute cerebral infarction combined with acute hip fracture, who were hospitalized in two hospitals between January 1, 2013 and December 31, 2019, were included. The patients did not undergo surgical treatment. The control group included patients with common acute cerebral infarction without hip fracture admitted in the same period. The neurological function recovery, hospitalization period, half a year recovery rate, incidence of complications, and one-year mortality rate between the two groups were compared. Eleven patients with acute cerebral infarction combined with hip fracture, who underwent surgical treatment, were selected and compared with those in the non-surgery group. RESULTS: Compared with patients with common acute cerebral infarction, the National Institutes of Health Stroke Scale score of those with acute cerebral infarction combined with hip fracture was higher (7.2±5.4 vs. 5.6%±4.3, p=0.034), the hospitalization period was prolonged (16.1±8.9% vs. 12.2±5.3, p=0.041), and the half a year recovery rate was lower (26.7% vs. 53.3%, p=0.016). Additionally, the incidence of pulmonary infection and lower extremity deep vein thrombosis was increased (30% vs. 11.7%, p=0.03; 6.7% vs. 0, p=0.043). The one-year mortality rate of patients with hip fracture was higher than that of patients with common cerebral infarction (23.3% vs. 6.7%, p=0.027). Compared with the non-surgical group, the good recovery rate after half a year of surgical treatment of the group with cerebral infarction and acute hip fracture had an increasing trend, while the hospitalization cycle, incidence of complications, and one-year mortality rate were all decreased, although this was not statistically significant. CONCLUSIONS: Acute cerebral infarction combined with hip fracture leads to worse neurological recovery, prolonged hospitalization period, increased complications, decreased patient prognosis, and increased one-year mortality. Surgical treatment improves the prognosis of patients with acute cerebral infarction. These findings may provide insights into the management of acute cerebral infarction.

Arterial wall injury and miRNA expression induced by stent retriever thrombectomy under stenotic conditions in a dog model.

BACKGROUND: Acute ischemic stroke can be caused by in situ stenotic vessel occlusion. In the present study, we compared the extent of arterial wall damage and miRNA expression following stent retriever use under normal and stenotic conditions. METHODS: The stent retriever procedure was simulated in three dogs by the creation of four stenoses on each side of the common carotid artery (CCA) to allow five stent passages. Device safety was also assessed in normal control models by five passages through both CCAs. Device manipulation-related damage to the arterial walls was evaluated and compared between groups by angiography and pathological analysis. Real-time PCR was used to evaluate the differences in the expression of miRNAs between the two groups. RESULTS: Twenty-four stenoses were created in three model dogs, and the mean stenosis rate was 65.58%±18.95%. Angiography revealed greater vasospasm in the stenotic group than in the non-stenotic group (1.17±0.17 vs 0.5±0.23; P=0.04). Pathological examination revealed that SR passage through the stenotic lumen caused higher injury scores (1.63±0.19 vs 0.25±0.09 for the non-stenotic lumen; P<0.001), more endothelial denudation (1.79±0.13 vs 0.58±0.13 for the non-stenotic lumen; P<0.001), and increased thrombus deposition (0.71±0.14 vs 0±0 for the non-stenotic lumen; P<0.001). miR21-3p, miR29-3p, and miR26a were upregulated in stenotic vessels compared with non-stenotic vessels after SR thrombectomy (P<0.001). CONCLUSION: In our model dogs, SR thrombectomy resulted in more severe tissue damage to the arterial wall under stenotic conditions than under non-stenotic conditions. The damage may have resulted from upregulation of miR21-3p, miR29-3p, and miR26a expression.

Role of Macrophages in Status Epilepticus Predisposing to Alzheimer's Disease.

Continuous epileptic seizures hallmark status epilepticus, leading to preferential neuronal cell loss in the hippocampus that can progress into Alzheimer's disease. Previous studies have shown that status epilepticus prompts an overproduction of nitric oxide (NO) by upregulation of NO synthase II (NOS II) to induce apoptosis of neuronal cells in the hippocampus, in a nuclear factor-kappaB (NF-κB) signaling dependent manner. Here, in an experimental rat model for status epilepticus, elicitation of sustained seizure activity was achieved by microinjection of kainic acid (KA) into the hippocampal CA3 subfield. We found that KA induced features of status epilepticus, which could be attenuated by blocking NF-κB signaling through a specific inhibitor. Interestingly, infiltration of macrophages of primarily pro-inflammatory subtype was detected in the hippocampal CA3 region immediately after KA injection. Experimental elimination of macrophages by an anti-CD115 antibody significantly attenuated the features of status epilepticus, likely through suppressing activation of NF-κB signaling. Together, these data suggest that macrophages play a critical role in NF-κB signaling-mediated status epilepticus that predisposes to Alzheimer's disease.

USP18 Overexpression Protects against Focal Cerebral Ischemia Injury in Mice by Suppressing Microglial Activation.

The activation of inflammatory cytokines following stroke leads to neuron apoptosis and microglial activation, both of which are involved in ischemic brain damages. The ubiquitin-specific protease 18 (USP18) negatively regulated the expression of inflammatory cytokines and suppresses microglial activation. This study aims to determine whether USP18 expression protects against brain damage in ischemic models of stroke. We investigated USP18 expression, overexpression, and knockout under ischemic conditions in vitro and in vivo. Using BV2 microglial cells under oxygen and glucose deprivation (OGD) and 60 min transient middle cerebral artery occlusion (MCAO) in mice as models of ischemia, we assessed the infarct volume, the extent of neurogenesis, the expression of proinflammatory cytokines and Janus Kinases(JAKs)/Signal Transducer and Activator of Transcription (STAT) pathway members. BV2 cells under OGD for 0, 6, 12, or 24 h exhibited decreased USP18 expression and increased expression of the proinflammatory cytokines including interleukin (IL)-1ß, IL-6, IL-8, tumor necrosis factor (TNF)-α, and interferon (INF)-γ. Lentiviral overexpression of USP18 in MCAO mice significantly decreased the infarct volume and significantly increased the number of new neurons that coexpressed bromodeoxyuridine (BrdU)/neuronal nuclei (NeuN). Additionally, microglial activation was inhibited, including the suppression of the JAK/STAT pathway and the proinflammatory cytokines expression. In vitro experiments demonstrated that USP18 inhibited BV2 microglial activity and reduced the mRNA and protein levels of NF-κB, JAK1, p-JAK1, STAT1, and p-STAT1 in BV2 microglial cells. USP18 overexpression decreased ischemic brain injury through the suppression of microglial activation by negatively regulating the release of proinflammatory cytokines.

Atherosclerosis in intracranial or extracranial vessels in diabetic patients and the association with stroke subtype.

BACKGROUND: Diabetes mellitus (DM) is associated with increased prevalence and severity of atherosclerosis. This study aimed to assess the prevalence and location of atherosclerosis in intracranial and extracranial vessels in diabetic patients and to investigate their association with ischemic stroke subtype. METHODS: Diabetes patients (n=128) and nondiabetic patients (n=195) were enrolled. Brain MRI, MR angiography, and digital subtraction angiography (DSA) imaging findings in the two groups were retrospectively compared. The characteristics of atherosclerosis (prevalence, location, severity) and collateral flow in diabetic and nondiabetic patients and their association with stroke subtype were analyzed. RESULTS: Atherosclerosis in extracranial vessels was more common in diabetes patients than in nondiabetic patients (43.8% vs. 23.1%; P<0.001). Symptomatic stenoses were commonly in the proximal internal carotid artery (ICA) and proximal vertebral artery (pVA). Diabetes patients were more likely to have lacunar infarction (49.2% vs. 32.3%; P=0.002) and less likely to have large artery infarct (36.7% vs. 48.2%; P=0.042). DM (OR, 2.03; 95% CI, 1.96-4.30; P=0.006) and age >65 years (OR, 2.55; 95% CI, 1.24-5.22; P=0.011) were independent risk factors for lacunar infarct. Diabetes patients with symptomatic extracranial stenosis or occlusion, combined with good collateral circulation, had significantly higher risk of lacunar infarction than nondiabetic patients (47.8% vs. 30.5%; P=0.045). CONCLUSIONS: DM aggravates the severity of extracranial atherosclerosis. Lacunar stroke is relatively common in diabetic patients and could even be due to large artery disease (LAD).

Role of Post-Transcriptional Control of Calpain by miR-124-3p in the Development of Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disease prevalent in aged people, clinically characterized by progressive memory loss, behavioral and learning dysfunction, and cognitive deficits. The pathogenesis of AD is hallmarked by formation of amyloid-ß peptide aggregates (Aß) and intraneuronal neurofibrillary tangles (NFTs), which are induced by hyperphosphorylation of amyloid-ß protein precursor and tau protein, respectively. The hyperphosphorylation is controlled by cyclin-dependent kinase-5 (CDK5), the aberrant activation of which is mediated by calpain (CAPN)-induced cleavage of p35 into p25. However, the regulation of CAPN in AD remains largely unknown. Here, we studied the post-transcriptional control of CAPN1 by microRNAs (miRNAs) in the setting of AD. We found that miR-124-3p, previously reported as a miRNA that was downregulated in AD, was a CAPN1-targeting miRNA that functionally inhibited the protein translation of CAPN1 in a human neural cell line, HCN-2. In vitro, transfection with miR-124-3p reduced the levels of CAPN1 protein, the cleavage of p35 into p25, and cell apoptosis dose-dependently in HCN-2 cells. Moreover, a significant inverse correlation was detected between the levels of miR-124-3p and CAPN1 in AD specimens. Furthermore, intracranial injection of adeno-associated virus expressing miR-124-3p into APP/PS1-AD mice significantly reduced Aß deposition and significantly improved the AD-mouse behavior in the social recognition test and plus-maze discriminative avoidance task. Together, our data suggest that post-transcriptional control of calpain by miR-124-3p plays an essential role in the development of AD.

MALAT1 Activates the P53 Signaling Pathway by Regulating MDM2 to Promote Ischemic Stroke.

BACKGROUND/AIMS: This study focused on evaluating the effect of MALAT1 and MDM2 on ischemic stroke through regulation of the p53 signaling pathway. MATERIALS: Bioinformatics analysis was performed to identify abnormally expressed lncRNAs, mRNAs and their associated pathways. Oxygen-glucose deprivation/reoxygenation (OGD/R) in cells and middle cerebral artery occlusion/reperfusion (MCAO/R) in mice were performed to simulate an ischemic stroke environment. Western blot and qRT-PCR were used to examine lncRNA expression and mRNA levels. Fluorescence in situ hybridization (FISH) LncRNA was used to locate mRNA. MTT and flow cytometry were performed to examine cell proliferation and apoptosis. Finally, immunohistochemistry was used to observe the expression of genes in vivo. RESULTS: MALAT1 and MDM2, which exhibit strong expression in stroke tissues, were subjected to bioinformatics analysis, and the p53 pathway was chosen for further study. MALAT1, MDM2 and p53 signaling pathway-related proteins were all up regulated in OGD/R cells. Furthermore, Malat1, Mdm2 and p53 pathway related-proteins were also up regulated in MCAO/R mice. Both MALAT1 and MDM2 were localized in the nuclei. Down regulation of MALAT1 and MDM2 enhanced cell proliferation ability and reduced apoptosis, resulting in decreased infarct size in MCAO/R brains. CONCLUSION: These results indicate that MALAT1/MDM2/p53 signaling pathway axis may provide more effective clinical therapeutic strategy for patients with ischemic stroke.

PTEN inhibition enhances angiogenesis in an in vitro model of ischemic injury by promoting Akt phosphorylation and subsequent hypoxia inducible factor-1α upregulation.

Angiogenesis is an important pathophysiological response to cerebral ischemia. PTEN is a lipid phosphatase whose loss activates PI3K/Akt signaling, which is related to HIF-1α upregulation and enhanced angiogenesis in human cancer cells. However, the specific roles of PTEN in endothelial cell functions and angiogenesis after cerebral ischemia remain unknown. Therefore, we sought to examine the potential effects of PTEN inhibition on post-ischemic angiogenesis in human blood vessel cells and to determine the underlying mechanism. In this present study, human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation (OGD), cell proliferation, migration and apoptosis, in vitro tube formation and expression of PTEN/Akt pathway and angiogenic factors were examined in HUVECs after treatment with PTEN inhibitor bisperoxovanadium (bpV) at different doses. The results showed that bpV significantly increased the cell proliferation and reduced cell apoptosis indicating that the drug exerts a cytoprotective effect on HUVECs with OGD exposure. bpV also enhanced cell migration and tube formation in HUVECs following OGD, and upregulated HIF-1α and VEGF expressions, but attenuated endostatin expression. Additionally, western blotting analysis demonstrated that Akt phosphorylation in HUVECs was significantly increased after bpV treatment. These findings suggest that PTEN inhibition promotes post-ischemic angiogenesis in HUVECs after exposure to OGD and this enhancing effect might be achieved through activation of the Akt signal cascade.

Aquaporin-4 deletion ameliorates hypoglycemia-induced BBB permeability by inhibiting inflammatory responses.

BACKGROUND: Severe hypoglycemia induces brain edema by upregulating aquaporin-4 (AQP4) expression and by degrading tight junctions. Acute severe hypoglycemia induces a proinflammatory environment that may contribute to a disruption in the epithelial barrier by decreasing tight junction protein expression. Interestingly, the altered AQP4 expression has been considered to play a critical role in neuroinflammation during acute brain injury. It has been shown that AQP4 deletion reduces brain inflammation in AQP4-null mice after intracerebral LPS injection. However, the effect of AQP4 deletion regarding protection against hypoglycemia-induced blood-brain barrier (BBB) breakdown is unknown. METHODS: An acute severe hypoglycemic stress model was established via injection of 4 unit/kg body weight of insulin. Evans blue (EB) staining and water measurement were used to assess BBB permeability. Western blot, reverse transcription polymerase chain reaction, and immunofluorescence were used to detect the expression of related proteins. The production of cytokines was assessed via enzyme-linked immunosorbent assay. RESULTS: Hypoglycemia-induced brain edema and BBB leakage were reduced in AQP4-/- mice. AQP4 deletion upregulated PPAR-γ and inhibited proinflammatory responses. Moreover, knockdown of aquaporin-4 by small interfering RNA in astrocytes co-cultured with endothelial cells effectively reduced transendothelial permeability and degradation of tight junctions. Treatment with PPAR-γ inhibitors showed that upregulation of PPAR-γ was responsible for the protective effect of AQP4 deletion under hypoglycemic conditions. CONCLUSIONS: Our data suggest that AQP4 deletion protects BBB integrity by reducing inflammatory responses due to the upregulation of PPAR-γ expression and attenuation of proinflammatory cytokine release. Reduction in AQP4 may be protective in acute severe hypoglycemia.

No inferiority of Tonbridge thrombectomy device for acute thrombus retrial compared with Solitaire device: an experimental evaluation with a canine distal external carotid-maxillary artery occlusion model.

INTRODUCTION: Mechanical thrombectomy (MT) has been widely accepted as a safe and effective treatment for acute ischemic stroke (AIS). Development of stent retriever devices has been intensively developed over the past two decades. In this study, we compared the effectiveness and safety of a new thrombectomy device with Solitaire FR for the treatment of AIS models. METHODS: Mechanical performance of stent retrievers was tested in vitro. Thrombin-induced thrombus was pre-injected into the right distal external carotid-maxillary artery in 18 dogs to create an acute thrombus occlusion model, and these animals were divided into a Tonbridge group (n=9, with Tonbridge stent Tonbridge Medical Technology) and a Solitaire group as control (n=9, with Solitaire stent, ev3 Neurovascular). Final flow restoration, side branches, recanalization time, distal vessel embolism, and device-related complications were recorded and compared. A post-procedure angiogram was obtained at 30 and 90 days after thrombectomy. Device manipulation-related damage to the arterial walls was evaluated histologically. RESULTS: In vitro test showed that the maximum friction within the microcatheter was 0.763 for the Tonbridge device and 0.784 n for the Solitaire (P>0.05). Slight increase in radial force was noticed for the Tonbridge (0.035 N/mm vs 0.031 N/mm of Solitaire, P>0.05). Eighteen and 16 retriever attempts were done in the Tonbridge (mean 2.0 attempts) and the Solitaire (mean 1.8 attempts) groups (P=0.74). The Tonbridge device led to good flow restoration in all nine (100%) models compared with eight (88.9%) in the Solitaire group (P=0.30). Side branches' influence (P=0.39), distal thromboembolism (P=0.60), and device-related complications (P=1.00) found no difference between the two groups. The rates of disruption of the internal elastic lamina (IEL) were 8.3% (2/24) and 4.2% (1/24) of the specimens, respectively (P=0.683). TICI 2b/3 flow of the right CCA were similar between the two groups at 1 (6/6 vs 6/6) and 3 months (6/6 vs 6/6) follow-up (P>0.05). CONCLUSION: Our preliminary study indicated this new device was technically feasible and effective to be used in thrombectomy for the treatment of acute thrombus occlusion in canine models.

Protective effects of angiopoietin-like 4 on the blood-brain barrier in acute ischemic stroke treated with thrombolysis in mice.

AIMS: Given the risk of blood-brain barrier damage (BBB) caused by ischemic and tissue plasminogen activator thrombolysis, the preservation of vascular integrity is important. Angiopoietin-like 4 (ANGPTL4), a protein secreted in hypoxia, is involved in the regulation of vascular permeability. We hypothesized that Angptl4 might exert a protective effect in thrombolysis through stabilizing blood-brain barrier and inhibit hyper-permeability. METHODS: We investigated the role of Angptl4 in stroke using a transient focal cerebral ischemia mouse model. The treated mice were administered Angptl4 1h after the ischemic event upon reperfusion. RESULTS: Our results showed that Angptl4 combined with thrombolysis greatly reduced the infarct volume and consequent neurological deficit. Western blot analyses and gelatin zymography revealed that Angptl4 protected the integrity of the endothelium damaged by thrombolysis. Angptl4 inhibited the up-regulation of vascular endothelial growth factor (VEGF) in the vascular endothelium after stroke, which was suppressed by counteracting VEGFR signaling and diminishing downstream Src signaling, and led to the increased stability of junctions and improved endothelial cell barrier integrity. CONCLUSION: These findings demonstrated that Angptl4 protects the permeability of the BBB damaged by ischemic and thrombolysis. Suggested that Angptl4 might be a promising target molecule in therapies for vasoprotection after thrombolysis treatment.

Changes in serum vascular endothelial growth factor and endostatin concentrations associated with circulating endothelial progenitor cells after acute ischemic stroke.

Angiogenesis is an important pathophysiological response to cerebral ischemia, and can be modulated by vascular endothelial growth factor (VEGF) and endostatin. Circulating endothelial progenitor cells (EPCs) also play an important role as an endogenous repair mechanism for ischemic injury. We sought to investigate early changes in the expression of VEGF and endostatin in serum and the circulating EPCs in patients with acute ischemic stroke (AIS) and analyzed the relations between them. The peripheral blood and serum samples were obtained from 30 patients at 1, 3, 5 and 7 d after AIS. Flow cytometry was used to quantify EPCs, and VEGF and endostatin were measured by enzyme linked immunosorbent assay. Correlation analysis was performed to assess the relations between them. Receiver operating characteristic (ROC) curve was used to appraise the value of EPCs levels in predicting the 90-day prognosis after AIS. Compared with control subjects, circulating EPCs numbers increased from a very lower initial level (P < 0.001) until 7 d after AIS. Serum VEGF and endostatin levels increased and peaked at 3 d and 5 d post-stroke (both P < 0.001), respectively. A significant correlation (P = 0.001) was found between peak serum VEGF concentration and peak endostatin concentration. VEGF/endostatin ratio at day 1 and day 3 after AIS significantly correlated with circulating EPCs numbers at day 5 (P < 0.001) and day 7 post-stroke (P < 0.001). ROC curve analysis suggested that circulating EPCs number at day 7 had a significantly predictive power for good prognosis. VEGF and endostatin may mediate EPCs proliferation in the early phase of ischemic stroke, and the circulating EPCs levels can be a predictor of clinical outcome in AIS.

Protective effect of lithium chloride against hypoglycemia-induced apoptosis in neuronal PC12 cell.

Hypoglycemia is defined by an arbitrary plasma glucose level lower than 3.9mmol/L and is a most common and feared adverse effect of treatment of diabetes mellitus. Emerging evidences demonstrated that hypoglycemia could induce enhanced apoptosis. Lithium chloride (LiCl), a FDA approved drug clinically used for treatment of bipolar disorders, is recently proven having neuroprotection against various stresses in the cellular and animal models of neural disorders. Here, we have established a hypoglycemia model in vitro and assessed the neuroprotective efficacy of LiCl against hypoglycemia-induced apoptosis and the underlying cellular and molecular mechanisms. Our studies showed that LiCl protects against hypoglycemia-induced neurotoxicity in vitro. Exposure to hypoglycemia results in enhanced apoptosis and the underlying cellular and molecular mechanisms involved inhibition of the canonical Wnt signaling pathway by decreasing wnt3a levels, ß-catenin levels and increasing GSK-3ß levels, which was confirmed by the use of Wnt-specific activator LiCl. Hypoglycemia-induced apoptosis were significantly reversed by LiCl, leading to increased cell survival. LiCl also alters the expression/levels of the Wnt pathway genes/proteins, which were reduced due to exposed to hypoglycemia. Overall, our results conclude that LiCl provides neuroprotection against hypoglycemia-induced apoptosis via activation of the canonical Wnt signaling pathway.

Is Helicobacter pylori infection a critical risk factor for vascular dementia?

PURPOSE: The association of Helicobacter pylori (Hp) infection and Alzheimer's disease has widely been addressed, but no relative data exist regarding vascular dementia (VD). The purpose of this study was to evaluate the relationship between Hp infection and VD. MATERIAL AND METHOD: From January 2014 to March 2015, patients at Tai'an City Central Hospital who were diagnosed with VD were included. Patients were divided into Hp positive and Hp negative group using the (13)C-urea breath test ((13)C-UBT). Three inflammatory cytokines including interleukin-1 beta (IL-1ß), interleukin-6 (IL-6) and tumor necrosis factor α (TNF-α) were detected. RESULTS: A total of 173 VD patients were included in the study. According to (13)C-UBT, 104 patients (60.1%) were Hp positive VD patients and 69 patients (39.9%) were Hp negative patients. No differences were found between Hp positive and Hp negative patients as regard to age, gender, body mass index, education level, hypertension, diabetes mellitus and hyperlipidemia (p > 0.05). Hp positive patients demonstrated significantly lower mean mini-mental state examination and Montreal cognitive assessment scores (p < 0.05) and higher plasma levels of IL-1ß, IL-6 and TNF-α than Hp negative patients (p < 0.05). CONCLUSIONS: Hp infection might contribute, at least in part, to the cognitive decline in patients with VD, and play a critical role possibly through increasing expression of IL-1ß, IL-6 and TNF-α.

Protective effects of vascular endothelial growth factor in cultured brain endothelial cells against hypoglycemia.

Hypoglycemia is a common and serious problem among patients with type 1 diabetes receiving treatment with insulin. Clinical studies have demonstrated that hypoglycemic edema is involved in the initiation of hypoglycemic brain damage. However, the mechanisms of this edema are poorly understood. Vascular endothelial growth factor (VEGF), a potent regulator of blood vessel function, has been observed an important candidate hormone induced by hypoglycemia to protect neurons by restoring plasma glucose. Whether VEGF has a protective effect against hypoglycemia-induced damage in brain endothelial cells is still unknown. To investigate the effects of hypoglycemia on cerebral microvascular endothelial cells and assess the protective effect of exogenous VEGF on endothelial cells during hypoglycemia, confluent monolayers of the brain endothelial cell line bEnd.3 were treated with normal (5.5 mM glucose), hypoglycemic (0, 0.5, 1 mM glucose) medium or hypoglycemic medium in the presence of VEGF. The results clearly showed that hypoglycemia significantly downregulated the expression of claudin-5 in bEnd.3 cells, without affecting ZO-1 and occludin expression and distribution. Besides, transendothelial permeability significantly increased under hypoglycemic conditions compared to that under control conditions. Moreover, the hypoglycemic medium in presence of VEGF decreased endothelial permeability via the inhibition of claudin-5 degradation and improved hypoglycemia-induced cell toxicity. Furthermore, Glucose transporter-1 (Glut-1) and apoptosis regulator Bcl-2 expression were significantly upregulated. Taken together, hypoglycemia can significantly increase paraendocellular permeability by downregulating claudin-5 expression. We further showed that VEGF protected brain endothelial cells against hypoglycemia by enhancing glucose passage, reducing endothelial cell death, and ameliorating paraendocellular permeability.

Glycogen synthase kinase-3 regulates production of amyloid-ß peptides and tau phosphorylation in diabetic rat brain.

The pathogenesis of diabetic neurological complications is not fully understood. Diabetes mellitus (DM) and Alzheimer's disease (AD) are characterized by amyloid deposits. Glycogen synthase kinase-3 (GSK-3) plays an important role in the pathogenesis of AD and DM. Here we tried to investigate the production of amyloid-ß peptides (A ß) and phosphorylation of microtubule-associated protein tau in DM rats and elucidate the role of GSK-3 and Akt (protein kinase B, PKB) in these processes. Streptozotocin injection-induced DM rats displayed an increased GSK-3 activity, decreased activity and expression of Akt. And A ß 40 and A ß 42 were found overproduced and the microtubule-associated protein tau was hyperphosphorylated in the hippocampus. Furthermore, selective inhibition of GSK-3 by lithium could attenuate the conditions of A ß overproduction and tau hyperphosphorylation. Taken together, our studies suggest that GSK-3 regulates both the production of A ß and the phosphorylation of tau in rat brain and may therefore contribute to DM caused AD-like neurological defects.