Autophagy alleviates hypoxia-induced blood-brain barrier injury via regulation of CLDN5 (claudin 5)

Neuritin promotes autophagic flux by inhibiting the cGAS-STING pathway to alleviate brain injury after subarachnoid haemorrhage

BACKGROUND

Early brain injury (EBI) is closely associated with poor prognosis in patients with subarachnoid haemorrhage (SAH), with autophagy playing a pivotal role in EBI. However, research has shown that the stimulator of interferon genes (STING) pathway impacts autophagic flux. While the regulatory impact of neuritin on EBI and autophagic flux has been established previously, the underlying mechanism remains unclear. This study aimed to determine the role of the cGAS-STING pathway in neuritin-mediated regulation of autophagic flux following SAH.

METHODS

A SAH model was established in male Sprague-Dawley rats via intravascular perforation. Neuritin overexpressions using adeno-associated virus, the STING antagonist "C-176," and the activator, "CMA," were determined to investigate the cGAS-STING pathway's influence on autophagic flux and brain injury post-SAH, along with the neuritin's regulatory effect on STING. In this study, SAH grade, neurological score, haematoxylin and eosin (H&E) staining, brain water content (BWC), sandwich enzyme-linked immunosorbent assay, Evans blue staining, immunofluorescence staining, western blot analysis, and transmission electron microscopy (TEM) were examined.

RESULTS

Neuritin overexpression significantly ameliorated neurobehavioural scores, blood-brain barrier injury, brain oedema, and impaired autophagic flux in SAH-induced rats. STING expression remarkably increased post-SAH. C-176 and CMA mitigated and aggravated autophagic flux injury and brain injury, respectively, while inhibiting and enhancing STING, respectively. Particularly, CMA treatment nullified the protective effects of neuritin against autophagic flux and mitigated brain injury.

CONCLUSION

Neuritin alleviated EBI by restoring impaired autophagic flux after SAH through the regulation of the cGAS-STING pathway.

Structure and gene expression changes of the gill and liver in juvenile black porgy (Acanthopagrus schlegelii) under different salinities

Black porgy (Acanthopagrus schlegelii) is an important marine aquaculture species in China. It is an ideal object for the cultivation of low-salinity aquaculture strains in marine fish and the study of salinity tolerance mechanisms in fish because of its strong low-salinity tolerance ability. Gill is the main osmoregulatory organ in fish, and the liver plays an important role in the adaptation of the organism to stressful environments. In order to understand the coping mechanisms of the gills and livers of black porgy in different salinity environments, this study explored these organs after 30 days of culture in hypoosmotic (0.5 ppt), isosmotic (12 ppt), and normal seawater (28 ppt) at histologic, physiologic, and transcriptomic levels. The findings indicated that gill exhibited a higher number of differentially expressed genes than the liver, emphasizing the gill's heightened sensitivity to salinity changes. Protein interaction networks and enrichment analyses highlighted energy metabolism as a key regulatory focus at both 0.5 ppt and 12 ppt salinity in gills. Additionally, gills showed enrichment in ions, substance transport, and other metabolic pathways, suggesting a more direct regulatory response to salinity stress. The liver's regulatory patterns at different salinities exhibited significant distinctions, with pathways and genes related to metabolism, immunity, and antioxidants predominantly activated at 0.5 ppt, and molecular processes linked to cell proliferation taking precedence at 12 ppt salinity. Furthermore, the study revealed a reduction in the volume of the interlamellar cell mass (ILCM) of the gills, enhancing the contact area of the gill lamellae with water. At 0.5 ppt salinity, hepatic antioxidant enzyme activity increased, accompanied by oxidative stress damage. Conversely, at 12 ppt salinity, gill NKA activity significantly decreased without notable changes in liver structure. These results underscore the profound impact of salinity on gill structure and function, highlighting the crucial role of the liver in adapting to salinity environments.

Rhodiola crenulata alleviates hypobaric hypoxia-induced brain injury by maintaining BBB integrity and balancing energy metabolism dysfunction

BACKGROUND/PURPOSE

Rhodiola crenulata (Hook. f. et Thoms.) H. Ohba (R. crenulate), a famous and characteristic Tibetan medicine, has been demonstrated to exert an outstanding brain protection role in the treatment of high-altitude hypoxia disease. However, the metabolic effects of R. crenulate on high-altitude hypoxic brain injury (HHBI) are still incompletely understood. Herein, the anti-hypoxic effect and associated mechanisms of R. crenulate were explored through both in vivo and in vitro experiments.

STUDY DESIGN/METHODS

The mice model of HHBI was established using an animal hypobaric and hypoxic chamber. R. crenulate extract (RCE, 0.5, 1.0 and 2.0 g/kg) and salidroside (Sal, 25, 50 and 100 mg/kg) was given by gavage for 7 days. Pathological changes and neuronal apoptosis of mice hippocampus and cortex were evaluated using H&E and TUNEL staining, respectively. The effects of RCE and Sal on the permeability of blood brain barrier (BBB) were detected by Evans blue staining and NIR-II fluorescence imaging. Meanwhile, the ultrastructural BBB and cerebrovascular damages were observed using a transmission electron microscope (TEM). The levels of tight junction proteins Claudin-1, ZO-1 and occludin were detected by immunofluorescence. Additionally, the metabolites in mice serum and brain were determined using UHPLC-MS and MALDI-MSI analysis. The cell viability of Sal on hypoxic HT22 cells induced by CoCl2 was investigated by cell counting kit-8. The contents of LDH, MDA, SOD, GSH-PX and SDH were detected by using commercial biochemical kits. Meanwhile, intracellular ROS, Ca2+ and mitochondrial membrane potential were determined by corresponding specific labeled probes. The intracellular metabolites of HT22 cells were performed by the targeted metabolomics analysis of the Q300 kit. The cell apoptosis and necrosis were examined by YO-PRO-1/PI, Annexin V/PI and TUNEL staining. In addition, mitochondrial morphology was tested by Mito-tracker red with confocal microscopy and TEM. Real-time ATP production, oxygen consumption rate, and proton efflux rate were measured using a Seahorse analyzer. Subsequently, MCU, OPA1, p-Drp1ser616, p-AMPKα, p-AMPKβ and Sirt1 were determined by immunofluorescent and western blot analyses.

RESULTS

The results demonstrated that R. crenulate and Sal exert anti-hypoxic brain protection from inhibiting neuronal apoptosis, maintaining BBB integrity, increasing tight junction protein Claudin-1, ZO-1 and occludin and improving mitochondrial morphology and function. Mechanistically, R. crenulate and Sal alleviated HHBI by enhancing the tricarboxylic acid cycle to meet the demand of energy of brain. Additionally, experiments in vitro confirmed that Sal could ameliorate the apoptosis of HT22 cells, improve mitochondrial morphology and energy metabolism by enhancing mitochondrial respiration and glycolysis. Meanwhile, Sal-mediated MCU inhibited the activation of Drp1 and enhanced the expression of OPA1 to maintain mitochondrial homeostasis, as well as activation of AMPK and Sirt1 to enhance ATP production.

CONCLUSION

Collectively, the findings suggested that RCE and Sal may afford a protective intervention in HHBI through maintaining BBB integrity and improving energy metabolism via balancing MCU-mediated mitochondrial homeostasis by activating the AMPK/Sirt1 signaling pathway.

Cerebral endothelial cells mediated enhancement of brain pericyte number and migration in oxygen-glucose deprivation involves the HIF-1α/PDGF-β signaling

The present study focused on whether hypoxia-inducible factor-1alpha (HIF-1α) and platelet-derived factor-beta (PDGF-β) are involved in the crosstalk between brain microvascular endothelial cells (BMECs) and brain vascular pericytes (BVPs) under ischaemic-hypoxic conditions. Mono-cultures or co-cultures of BVPs and BMECs were made for the construction of the blood-brain barrier (BBB) model in vitro and then exposed to control and oxygen-glucose deprivation (OGD) conditions. BBB injury was determined by assessing the ability, apoptosis, and migration of BVPs and the transendothelial electrical resistance and horseradish peroxidase permeation of BMECs. Relative mRNA and protein levels of HIF-1α and PDGF-β, as well as tight junction proteins ZO-1 and claudin-5 were analyzed by western blotting, reverse transcription quantitative PCR, and/or immunofluorescence staining. Dual-luciferase reporter assays assessed the relationship between PDGF-β and HIF-1α. Co-culturing with BMECs alleviated OGD-induced reduction in BVP viability, elevation in BVP apoptosis, and repression in BVP migration. Co-culturing with BVPs protected against OGD-induced impairment on BMEC permeability. OGD-induced HIF-1α upregulation enhanced PDGF-β expression in mono-cultured BMECs and co-cultured BMECs with BVPs. Knockdown of HIF-1α impaired the effect of BMECs on BVPs under OGD conditions, and PDGFR-β silencing in BVPs blocked the crosstalk between BMECs and BVPs under OGD conditions. The crosstalk between BMECs and BVPs was implicated in OGD-induced BBB injury through the HIF-1α/PDGF-β signaling.

Octreotide attenuates intestinal barrier damage by maintaining basal autophagy in Caco2 cells

The intestinal mucosal barrier is of great importance for maintaining the stability of the internal environment, which is closely related to the occurrence and development of intestinal inflammation. Octreotide (OCT) has potential applicable clinical value for treating intestinal injury according to previous studies, but the underlying molecular mechanisms have remained elusive. This article is based on a cell model of inflammation induced by lipopolysaccharide (LPS), aiming to explore the effects of OCT in protecting intestinal mucosal barrier function. A Cell Counting Kit‑8 assay was used to determine cell viability and evaluate the effectiveness of OCT. Gene silencing technology was used to reveal the mediated effect of somatostatin receptor 2 (SSTR2). The changes in intestinal permeability were detected through trans‑epithelial electrical resistance and fluorescein isothiocyanate‑dextran 4 experiments, and the alterations in tight junction proteins were detected using immunoblotting and reverse transcription fluorescence‑quantitative PCR technology. Autophagosomes were observed by electron microscopy and the dynamic changes of the autophagy process were characterized by light chain (LC)3‑II/LC3‑I conversion and autophagic flow. The results indicated that SSTR2‑dependent OCT can prevent the decrease in cell activity. After LPS treatment, the permeability of monolayer cells decreased and intercellular tight junctions were disrupted, resulting in a decrease in tight junction protein zona occludens 1 in cells. The level of autophagy‑related protein LC3 was altered to varying degrees at different times. These abnormal changes gradually returned to normal levels after the combined application of LPS and SSTR2‑dependent OCT, confirming the role of OCT in protecting intestinal barrier function. These experimental results suggest that OCT maintains basal autophagy and cell activity mediated by SSTR2 in intestinal epithelial cells, thereby preventing the intestinal barrier dysfunction in inflammation injury.

Periodontopathogen-Related Cell Autophagy-A Double-Edged Sword

The periodontium is a highly organized ecosystem, and the imbalance between oral microorganisms and host defense leads to periodontal diseases. The periodontal pathogens, mainly Gram-negative anaerobic bacteria, colonize the periodontal niches or enter the blood circulation, resulting in periodontal tissue destruction and distal organ damage. This phenomenon links periodontitis with various systemic conditions, including cardiovascular diseases, malignant tumors, steatohepatitis, and Alzheimer's disease. Autophagy is an evolutionarily conserved cellular self-degradation process essential for eliminating internalized pathogens. Nowadays, increasing studies have been carried out in cells derived from periodontal tissues, immune system, and distant organs to investigate the relationship between periodontal pathogen infection and autophagy-related activities. On one hand, as a vital part of innate and adaptive immunity, autophagy actively participates in host resistance to periodontal bacterial infection. On the other, certain periodontal pathogens exploit autophagic vesicles or pathways to evade immune surveillance, therefore achieving survival within host cells. This review provides an overview of the autophagy process and focuses on periodontopathogen-related autophagy and their involvements in cells of different tissue origins, so as to comprehensively understand the role of autophagy in the occurrence and development of periodontal diseases and various periodontitis-associated systemic illnesses.

HO-1-induced autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to reduce gut permeability in cholestatic liver disease

OBJECTIVES

The gut-liver axis disruption is a unified pathogenetic principle of cholestatic liver disease (CSLD). Increased gut permeability is the leading cause of gut-liver axis disruption. HO-1 is capable of protecting against gut-liver axis injury. However, it has rarely been reported whether autophagy is involved in HO-1 protecting gut-liver barrier integrity and the underlying mechanism.

MATERIALS AND METHODS

Mice underwent bile duct ligation (BDL) was established as CSLD model in vivo. Caco-2 cells with LPS treatment was established as in vitro cell model. Immunofluorescence, western blot and transepithelial electrical resistance (TER) assay were used to observe epithelial tight junction (TJ) and autophagy. Liver injury and fibrosis were evaluated as well through H&E staining, masson staining, sirius red staining and ELISA.

RESULTS AND CONCLUSIONS

Our study demonstrated that the epithelial TJ and TER were notably reduced both in BDL mice and in LPS treated intestinal epithelial cells. Increased HO-1 expression could significantly induce intestinal epithelial cell autophagy. Additionally, this increased autophagy level reversed the reduction effects of BDL or LPS on epithelial TJ and TER in vivo and in vitro, therefore decreased transaminase level in serum and relieved liver fibrosis in BDL mice. Besides, increased autophagy level in turn upregulated the expression of HO-1 by p62 degradation of Keap1 and subsequent activation of Nrf2 pathway. Collectively, these results indicate that HO-1 reduces gut permeability by enhancing autophagy level in CSLD, the increased autophagy establishes a HO-1-p62-Nrf2 positive feedback loop to further improve gut-liver axis disruption. Therefore, our study confirms the critical role of autophagy in HO-1 ameliorating gut-liver axis injury during CSLD, highlighting HO-1 as a promising therapeutic target.

Streptococcus pneumoniae extracellular vesicles aggravate alveolar epithelial barrier disruption via autophagic degradation of OCLN (occludin)

Streptococcus pneumoniae (S. pneumoniae) represents a major human bacterial pathogen leading to high morbidity and mortality in children and the elderly. Recent research emphasizes the role of extracellular vesicles (EVs) in bacterial pathogenicity. However, the contribution of S. pneumoniae EVs (pEVs) to host-microbe interactions has remained unclear. Here, we observed that S. pneumoniae infections in mice led to severe lung injuries and alveolar epithelial barrier (AEB) dysfunction. Infections of S. pneumoniae reduced the protein expression of tight junction protein OCLN (occludin) and activated macroautophagy/autophagy in lung tissues of mice and A549 cells. Mechanically, S. pneumoniae induced autophagosomal degradation of OCLN leading to AEB impairment in the A549 monolayer. S. pneumoniae released the pEVs that could be internalized by alveolar epithelial cells. Through proteomics, we profiled the cargo proteins inside pEVs and found that these pEVs contained many virulence factors, among which we identified a eukaryotic-like serine-threonine kinase protein StkP. The internalized StkP could induce the phosphorylation of BECN1 (beclin 1) at Ser93 and Ser96 sites, initiating autophagy and resulting in autophagy-dependent OCLN degradation and AEB dysfunction. Finally, the deletion of stkP in S. pneumoniae completely protected infected mice from death, significantly alleviated OCLN degradation in vivo, and largely abolished the AEB disruption caused by pEVs in vitro. Overall, our results suggested that pEVs played a crucial role in the spread of S. pneumoniae virulence factors. The cargo protein StkP in pEVs could communicate with host target proteins and even hijack the BECN1 autophagy initiation pathway, contributing to AEB disruption and bacterial pathogenicity.Abbreviations: AEB: alveolarepithelial barrier; AECs: alveolar epithelial cells; ATG16L1: autophagy related 16 like 1; ATP:adenosine 5'-triphosphate; BafA1: bafilomycin A1; BBB: blood-brain barrier; CFU: colony-forming unit; co-IP: co-immunoprecipitation; CQ:chloroquine; CTRL: control; DiO: 3,3'-dioctadecylox-acarbocyanineperchlorate; DOX: doxycycline; DTT: dithiothreitol; ECIS: electricalcell-substrate impedance sensing; eGFP: enhanced green fluorescentprotein; ermR: erythromycin-resistance expression cassette; Ery: erythromycin; eSTKs: eukaryotic-like serine-threoninekinases; EVs: extracellular vesicles; HA: hemagglutinin; H&E: hematoxylin and eosin; HsLC3B: human LC3B; hpi: hours post-infection; IP: immunoprecipitation; KD: knockdown; KO: knockout; LAMP1: lysosomal associated membrane protein 1; LC/MS: liquid chromatography-mass spectrometry; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MVs: membranevesicles; NC:negative control; NETs:neutrophil extracellular traps; OD: optical density; OMVs: outer membrane vesicles; PBS: phosphate-buffered saline; pEVs: S.pneumoniaeextracellular vesicles; protK: proteinase K; Rapa: rapamycin; RNAi: RNA interference; S.aureus: Staphylococcusaureus; SNF:supernatant fluid; sgRNA: single guide RNA; S.pneumoniae: Streptococcuspneumoniae; S.suis: Streptococcussuis; TEER: trans-epithelium electrical resistance; moi: multiplicity ofinfection; TEM:transmission electron microscope; TJproteins: tight junction proteins; TJP1/ZO-1: tight junction protein1; TSA: tryptic soy agar; WB: western blot; WT: wild-type.

Myricetin Oligomer Triggers Multi-Receptor Mediated Penetration and Autophagic Restoration of Blood-Brain Barrier for Ischemic Stroke Treatment

Restoration of blood-brain barrier (BBB) dysfunction, which drives worse outcomes of ischemic stroke, is a potential target for therapeutic opportunities, whereas a sealed BBB blocks the therapeutics entrance into the brain, making the BBB protection strategy paradoxical. Post ischemic stroke, hypoxia/hypoglycemia provokes the up-regulation of transmembrane glucose transporters and iron transporters due to multiple metabolic disorders, especially in brain endothelial cells. Herein, we develop a myricetin oligomer-derived nanostructure doped with Ce to bypass the BBB which is cointermediated by glucose transporters and iron transporters such as glucose transporters 1 (GLUT1), sodium/glucose cotransporters 1 (SGLT1), and transferrin(Tf) reporter (TfR). Moreover, it exhibits BBB restoration capacity by regulating the expression of tight junctions (TJs) through the activation of protective autophagy. The myricetin oligomers scaffold not only acts as targeting moiety but is the prominent active entity that inherits all diverse pharmacological activities of myricetin. The suppression of oxidative damage, M1 microglia activation, and inflammatory factors makes it a multitasking nanoagent with a single component as the scaffold, targeting domain and curative components.

A natural small molecule aspidosperma-type alkaloid, hecubine, as a new TREM2 activator for alleviating lipopolysaccharide-induced neuroinflammation in vitro and in vivo

Neuroinflammation and oxidative stress play a crucial role in the pathogenesis of neurodegenerative diseases, including Alzheimer's disease. The triggering receptor expressed on myeloid cells 2 (TREM2), highly expressed by microglia in the central nervous system (CNS), can modulate neuroinflammatory responses. Currently, there are no approved drugs specifically targeting TREM2 for CNS diseases. Aspidosperma alkaloids have shown potential as anti-inflammatory and neuroprotective agents. This study aimed to elucidate the potential therapeutic effect of Hecubine, a natural aspidosperma-type alkaloid, as a TREM2 activator in lipopolysaccharide (LPS)-stimulated neuroinflammation in in vitro and in vivo models. In this study, molecular docking and cellular thermal shift assay (CTSA) were employed to investigate the interaction between Hecubine and TREM2. Enzyme-linked immunosorbent assay (ELISA), quantitative PCR, immunofluorescence, Western blotting, and shRNA gene knockdown were used to assess the anti-neuroinflammatory and antioxidant effects of Hecubine in microglial cells and zebrafish. Our results revealed that Hecubine directly interacted with TREM2, leading to its activation. Knockdown of TREM2 mRNA expression significantly abolished the anti-inflammatory and antioxidant effects of Hecubine on LPS-stimulated proinflammatory mediators (NO, TNF-α, IL-6, and IL-1β) and oxidative stress in microglia cells. Furthermore, Hecubine upregulated Nrf2 expression levels while downregulating TLR4 signaling expression levels both in vivo and in vitro. Silencing TREM2 upregulated TLR4 and downregulated Nrf2 signaling pathways, mimicking the effect of Hecubine, further supporting TREM2 as the drug target by which Hecubine inhibits neuroinflammation. In conclusion, this is the first study to identify a small molecule, namely Hecubine directly targeting TREM2 to mediate anti-neuroinflammation and anti-oxidative effects, which serves as a potential therapeutic agent for the treatment of neural inflammation-associated CNS diseases.

Mitochondrial ferritin upregulation reduced oxidative stress and blood-brain-barrier disruption by maintaining cellular iron homeostasis in a neonatal rat model of germinal matrix hemorrhage

Germinal matrix hemorrhage (GMH) is a devasting neurological disease in premature newborns. After GMH, brain iron overload associated with hemoglobin degradation contributed to oxidative stress, causing disruption of the already vulnerable blood-brain barrier (BBB). Mitochondrial ferritin (FTMT), a novel mitochondrial outer membrane protein, is crucial in maintaining cellular iron homeostasis. We aimed to investigate the effect of FTMT upregulation on oxidative stress and BBB disruption associated with brain iron overload in rats. A total of 222 Sprague-Dawley neonatal rat pups (7 days old) were used to establish a collagenase-induced GMH model and an iron-overload model of intracerebral FeCl2 injection. Deferiprone was administered via gastric lavage 1 h after GMH and given daily until euthanasia. FTMT CRISPR Knockout and adenovirus (Ad)-FTMT were administered intracerebroventricularly 48 h before GMH and FeCl2 injection, respectively. Neurobehavioral tests, immunofluorescence, Western blot, Malondialdehyde measurement, and brain water content were performed to evaluate neurobehavior deficits, oxidative stress, and BBB disruption, respectively. The results demonstrated that brain expressions of iron exporter Ferroportin (FPN) and antioxidant glutathione peroxidase 4 (GPX4) as well as BBB tight junction proteins including Claudin-5 and Zona Occulta (ZO)-1 were found to be decreased at 72 h after GMH. FTMT agonist Deferiprone attenuated oxidative stress and preserved BBB tight junction proteins after GMH. These effects were partially reversed by FTMT CRISPR Knockout. Iron overload by FeCl2 injection resulted in oxidative stress and BBB disruption, which were improved by Ad-FTMT mediated FTMT overexpression. Collectively, FTMT upregulation is neuroprotective against brain injury associated with iron overload. Deferiprone reduced oxidative stress and BBB disruption by maintaining cellular iron homeostasis partially by the upregulating of FTMT after GMH. Deferiprone may be an effective treatment for patients with GMH.

Electroacupuncture Ameliorates Neuronal Injury by NLRP3/ASC/Caspase-1 Mediated Pyroptosis in Cerebral Ischemia-Reperfusion

NLRP3/ASC/Caspase-1 mediated pyroptosis is one of the important causes of cerebral ischemia-reperfusion (I/R) injury. Electroacupuncture (EA) is widely used in clinical treatment of ischemic stroke. However, mechanism of EA on ischemic stroke remains unclear. Therefore, on basis of a previous work, this study used middle cerebral artery occlusion (MCAO) 2 h and then reperfusion 7 days in rats to simulate brain I/R process. EA with Bahui (GV20) and Zusanli (ST36) and VX-765 (a specific inhibitor of Caspase-1) was performed. In this study, we found that EA improved cerebral infarct size and neuronal damage, including ultrastructural injury, and ameliorated nitro/oxidative stress in cerebral I/R. Additionally, EA treatment significantly decreased ASC, Caspase-1, GSDMD, and IL-1β expression and VX-765 treatment significantly decreased NLRP3, Caspase-1, and IL-1β expression. This proved that EA can regulate NLRP3/ASC/Caspase-1 mediated pyroptosis, improve neuronal injury during cerebral I/R, and provide basic experimental data for clinical treatment.

Association between SpO2 and the risk of death in elderly T2DM patients with cerebral infarction: a retrospective cohort study

Objective

This study aimed to evaluate the SpO2 (transcutaneous oxygen saturation) -mortality link in elderly T2DM (diabetes mellitus type 2) patients with cerebral infarction and identify their optimal SpO2 range.

Methods

In this investigation, we employed a comprehensive approach. Initially, we screened the MIMIC-IV database, identifying elderly T2DM patients with cerebral infarction, utilizing specific ICD-9 and ICD-10 codes. We then harnessed the power of restricted cubic splines to craft a visual representation of the correlation between SpO2 and 1-year mortality. To enhance our analysis, we harnessed Cox multivariate regression, allowing us to compute adjusted hazard ratios (HR) accompanied by 95% confidence intervals (CIs). Additionally, we crafted Cumulative Mortality Curve analyses, augmenting our study by engaging in rigorous subgroup analyses, stratifying our observations based on pertinent covariates.

Results

In this study, 448 elderly T2DM patients with cerebral infarction were included. Within 1-year post-discharge, 161 patients (35.94%) succumbed. Employing Restricted Cubic Spline analysis, a statistically significant U-shaped non-linear relationship between admission ICU SpO2 levels and 1-year mortality was observed (P-value < 0.05). Further analysis indicated that both low and high SpO2 levels increased the mortality risk. Cox multivariate regression analysis, adjusting for potential confounding factors, confirmed the association of low (≤94.5%) and high SpO2 levels (96.5-98.5%) with elevated 1-year mortality risk, particularly notably high SpO2 levels (>98.5%) [HR = 2.06, 95% CI: 1.29-3.29, P-value = 0.002]. The cumulative mortality curves revealed the following SpO2 subgroups from high to low cumulative mortality at the 365th day: normal levels (94.5% < SpO2 ≤ 96.5%), low levels (SpO2 ≤ 94.5%), high levels (96.5% < SpO2 ≤ 98.5%), and notably high levels (>98.5%). Subgroup analysis demonstrated no significant interaction between SpO2 and grouping variables, including Sex, Age, Congestive heart failure, Temperature, and ICU length of stay (LOS-ICU; P-values for interaction were >0.05).

Conclusions

Striking an optimal balance is paramount, as fixating solely on lower SpO2 limits or neglecting high SpO2 levels may contribute to increased mortality rates. To mitigate mortality risk in elderly T2DM patients with cerebral infarction, we recommend maintaining SpO2 levels within the range of 94.5-96.5%.

Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons

Hypoglycemia-associated autonomic failure (HAAF) is a well-established complication of diabetes. Although HAAF has serious outcomes such as recurrent morbidity, coma, and death, the mechanisms of HAAF and its pathological components are largely unknown. Our previous studies have revealed that hypoglycemia is associated with the upregulation of an immediate early gene - FOS. In addition, it is documented that glucose deprivation activates neuronal autophagic activities. Therefore, the present study aimed to identify the role of FOS and one of the core components of the autophagy pathway, Beclin-1 (encoded by the BECN1 gene), in the regulation of autophagic mechanisms in embryonic hypothalamic neurons in response to hypoglycemic conditions. Embryonic Mouse Hypothalamic Cell Line N39 (mHypoE-N39 or N39) was cultured in reduced concentrations of glucose (2000, 900, 500, and 200 mg/L). Gene and protein expression, as well as immunofluorescence studies on autophagy were conducted under different reduced glucose concentrations in N39 hypothalamic neurons with and without FOS and BECN1 gene knockdowns (KD). The outcomes of the present study have demonstrated a significant increase in autophagosome formation and subsequent lysosomal degradation in the hypothalamic neurons in response to reduced glucose concentrations. This hypoglycemic response appears to be lowered to a similar extent in the FOS KD and BECN1 KD cells, albeit insignificantly from the negative control, is indicative of the involvement of FOS in the autophagic response of hypothalamic neurons to hypoglycemia. Moreover, the KD cells exhibited a change in morphology and reduced cell viability compared with the control cells. Our findings suggest that reduced FOS expression could potentially be associated with impaired autophagic activities that are dependent on BECN1, which could lead to decreased or blunted hypothalamic activation in response to hypoglycemia, and this, in turn, may contribute to the development of HAAF.

Treadmill exercise improves hippocampal neural plasticity and relieves cognitive deficits in a mouse model of epilepsy

Epilepsy frequently leads to cognitive dysfunction and approaches to treatment remain limited. Although regular exercise effectively improves learning and memory functions across multiple neurological diseases, its application in patients with epilepsy remains controversial. Here, we adopted a 14-day treadmill-exercise paradigm in a pilocarpine injection-induced mouse model of epilepsy. Cognitive assays confirmed the improvement of object and spatial memory after endurance training, and electrophysiological studies revealed the maintenance of hippocampal plasticity as a result of physical exercise. Investigations of the mechanisms underlying this effect revealed that exercise protected parvalbumin interneurons, probably via the suppression of neuroinflammation and improved integrity of blood-brain barrier. In summary, this work identified a previously unknown mechanism through which exercise improves cognitive rehabilitation in epilepsy.

Upregulated Tβ4 expression in inflammatory bowel disease impairs the intestinal mucus barrier by inhibiting autophagy in mice

Disrupted intestinal barrier homeostasis is fundamental to inflammatory bowel disease. Thymosin β4 (Tβ4) improves inflammation and has beneficial effects in dry-eye diseases, but its effects on the intestinal mucus barrier remain unknown. Therefore, this study evaluated the underlying regulatory mechanisms and effects of Tβ4 by examining Tβ4 expression in a mouse model with dextran sodium sulfate (DSS)-induced colitis and colonic barrier damage. Additionally, we intraperitoneally injected C57BL/6 mice with Tβ4 to assess barrier function, microtubule-associated protein 1 light chain 3 (LC3II) protein expression, and autophagy. Finally, normal human colon tissue and colon carcinoma cells (Caco2) were cultured to verify Tβ4-induced barrier function and autophagy changes. Mucin2 levels decreased, microbial infiltration increased, and Tβ4 expression increased in the colitis mouse model versus the control mice, indicating mucus barrier damage. Moreover, Tβ4-treated C57BL/6 mice had damaged intestinal mucus barriers and decreased LC3II levels. Tβ4 also inhibited colonic mucin2 production, disrupted tight junctions, and downregulated autophagy; these results were confirmed in Caco2 cells and normal human colon tissue. In summary, Tβ4 may be implicated in colitis by compromising the integrity of the intestinal mucus barrier and inhibiting autophagy. Thus, Tβ4 could be a new diagnostic marker for intestinal barrier defects.

Integrated analysis of transcriptome, translatome and proteome reveals insights into yellow catfish (Pelteobagrus fulvidraco) brain in response to hypoxia

Brain plays a central role in adapting to environmental changes and is highly sensitive to the oxygen level. Although previous studies investigated the molecular response of brain exposure to acute hypoxia in fish, the lack of studies at the translational level hinders further understanding of the regulatory mechanism response to hypoxia from multi-omics levels. Yellow catfish (Pelteobagrus fulvidraco) is an important freshwater aquaculture species; however, hypoxia severely restricts the sustainable development of its breeding industry. In the present study, the transcriptome, translatome, and proteome were integrated to study the global landscapes of yellow catfish brain response to hypoxia. The evidently increased amount of cerebral cortical cells with oedema and pyknotic nuclei has been observed in hypoxia group of yellow catfish. A total of 2750 genes were significantly changed at the translational level. Comparative transcriptional and translational analysis suggested the HIF-1 signaling pathway, autophagy and glycolysis/gluconeogenesis were up-regulated after hypoxia exposure. KEGG enrichment of translational efficiency (TE) differential genes suggested that the lysosome and autophagy were highly enriched. Our result showed that yellow catfish tends to inhibit the TE of genes by increasing the translation of uORFs to adapt to hypoxia. Correlation analysis showed that transcriptome and translatome exhibit higher correlation. In summary, this study demonstrated that hypoxia dysregulated the cerebral function of yellow catfish at the transcriptome, translatome, and proteome, which provides a better understanding of hypoxia adaptation in teleost.

Anti-NMDAR antibodies, the blood-brain barrier, and anti-NMDAR encephalitis

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is an antibody-related autoimmune encephalitis. It is characterized by the existence of antibodies against NMDAR, mainly against the GluN1 subunit, in cerebrospinal fluid (CSF). Recent research suggests that anti-NMDAR antibodies may reduce NMDAR levels in this disorder, compromising synaptic activity in the hippocampus. Although anti-NMDAR antibodies are used as diagnostic indicators, the origin of antibodies in the central nervous system (CNS) is unclear. The blood-brain barrier (BBB), which separates the brain from the peripheral circulatory system, is crucial for antibodies and immune cells to enter or exit the CNS. The findings of cytokines in this disorder support the involvement of the BBB. Here, we aim to review the function of NMDARs and the relationship between anti-NMDAR antibodies and anti-NMDAR encephalitis. We summarize the present knowledge of the composition of the BBB, especially by emphasizing the role of BBB components. Finally, we further provide a discussion on the impact of BBB dysfunction in anti-NMDAR encephalitis.

Association between transcutaneous oxygen saturation within 24 h of admission and mortality in critically ill patients with non-traumatic subarachnoid hemorrhage: a retrospective analysis of the MIMIC-IV database

Background

In critically ill patients, transcutaneous oxygen saturation (SpO2) upon admission is typically associated with in-hospital mortality. Nevertheless, the available information for patients with non-traumatic subarachnoid hemorrhage (SAH) is limited. In our study, our objective was to assess the correlation between SpO2 levels and mortality among patients diagnosed with severe SAH.

Methods

In this study, we extracted data from the Medical Information Marketplace in Intensive Care (MIMIC-IV) database, which comprises information on critically ill patients. By employing matching ICD-9 and ICD-10 codes, we identified 3,328 patients diagnosed with SAH. Every individual who was admitted to the intensive care unit (ICU) had their SpO2 data and various covariates, including age, sex, diagnosis, and duration of stay, recorded upon admission. Subsequently, the patients were categorized into three distinct groups according to their SpO2 levels: low (≤95%), moderate (95-98%), and high (≥98%). To investigate the association between percutaneous oxygen saturation and mortality in patients with severe SAH, logistic regression, and cubic spline models were utilized. The main outcomes of interest were 28- and 90-day mortality rates. Additionally, subgroup analyses were conducted to evaluate these correlations and assess the consistency of interactions.

Results

A cohort of 864 patients diagnosed with non-traumatic SAH was included in this study. The correlation between SpO2 and mortality displayed a U-shaped curve when utilizing a finite cubic spline function (non-linearity < 0.001), with the nadir in the probability of in-hospital death at 96%. Mortality at 28 and 90 days showed an inverse correlation with SpO2 < 96% (adjusted odds ratio [OR], 0.8; 95% confidence interval [CI], 0.67-0.95, and 0.76; 95% CI, 0.6-0.96). Conversely, there was a positive correlation between percutaneous oxygen saturation (SpO2) levels of ≥96% and mortality rates at both 28 and 90 days (adjusted OR, 1.17; 95% CI, 1.02-1.35 and 1.2; 95% CI, 1.05-1.39).

Conclusion

In patients with severe subarachnoid hemorrhage, the association between SpO2 and mortality at 28 and 90 days demonstrated a U-shaped pattern. When SpO2 levels were between 95 and 98%, both short- and long-term mortality rates were at their lowest. Patients with significant subarachnoid hemorrhage had a lower chance of survival when their SpO2 values were either high or low.

Research Progress on Natural Plant Molecules in Regulating the Blood-Brain Barrier in Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder. With the aging population and the continuous development of risk factors associated with AD, it will impose a significant burden on individuals, families, and society. Currently, commonly used therapeutic drugs such as Cholinesterase inhibitors, N-methyl-D-aspartate antagonists, and multiple AD pathology removal drugs have been shown to have beneficial effects on certain pathological conditions of AD. However, their clinical efficacy is minimal and they are associated with certain adverse reactions. Furthermore, the underlying pathological mechanism of AD remains unclear, posing a challenge for drug development. In contrast, natural plant molecules, widely available, offer multiple targeting pathways and demonstrate inherent advantages in modifying the typical pathologic features of AD by influencing the blood-brain barrier (BBB). We provide a comprehensive review of recent in vivo and in vitro studies on natural plant molecules that impact the BBB in the treatment of AD. Additionally, we analyze their specific mechanisms to offer novel insights for the development of safe and effective targeted drugs as well as guidance for experimental research and the clinical application of drugs for the prevention and treatment of AD.

USP14 inhibition promotes recovery by protecting BBB integrity and attenuating neuroinflammation in MCAO mice

AIM

Blood-brain barrier (BBB) dysfunction is one of the hallmarks of ischemic stroke. USP14 has been reported to play a detrimental role in ischemic brain injury. However, the role of USP14 in BBB dysfunction after ischemic stroke is unclear.

METHODS

In this study, we tested the role of USP14 in disrupting BBB integrity after ischemic stroke. The USP14-specific inhibitor IU1 was injected into middle cerebral artery occlusion (MCAO) mice once a day. The Evans blue (EB) assay and IgG staining were used to assess BBB leakage 3 days after MCAO. FITC-detran test was slected to examine the BBB leakage in vitro. Behavior tests were conducted to evaluate recovery from ischemic stroke.

RESULTS

Middle cerebral artery occlusion increased endothelial cell USP14 expression in the brain. Furthermore, the EB assay and IgG staining showed that USP14 inhibition through IU1 injection protected against BBB leakage after MCAO. Analysis of protein expression revealed a reduction in the inflammatory response and chemokine release after IU1 treatment. In addition, IU1 treatment was found to rescue neuronal loss resulting from ischemic stroke. Behavior tests showed a positive effect of IU1 in attenuating brain injury and improving motor function recovery. In vitro study showed that IU1 treatment could alleviate endothelial cell leakage induced by OGD in cultured bend.3 cells through modulating ZO-1 expression.

CONCLUSIONS

Our results demonstrate a role for USP14 in disrupting the integrity of the BBB and promoting neuroinflammation after MCAO.

The blood-brain barrier, a key bridge to treat neurodegenerative diseases

As a highly selective and semi-permeable barrier that separates the circulating blood from the brain and central nervous system (CNS), the blood-brain barrier (BBB) plays a critical role in the onset and treatment of neurodegenerative diseases (NDs). To delay or reverse the NDs progression, the dysfunction of BBB should be improved to protect the brain from harmful substances. Simultaneously, a highly efficient drug delivery across the BBB is indispensable. Here, we summarized several methods to improve BBB dysfunction in NDs, including knocking out risk geneAPOE4, regulating circadian rhythms, restoring the gut microenvironment, and activating the Wnt/β-catenin signaling pathway. Then we discussed the advances in BBB penetration techniques, such as transient BBB opening, carrier-mediated drug delivery, and nasal administration, which facilitates drug delivery across the BBB. Furthermore, various in vivo and in vitro BBB models and research methods related to NDs are reviewed. Based on the current research progress, the treatment of NDs in the long term should prioritize the integrity of the BBB. However, a treatment approach that combines precise control of transient BBB permeability and non-invasive targeted BBB drug delivery holds profound significance in improving treatment effectiveness, safety, and clinical feasibility during drug therapy. This review involves the cross application of biology, materials science, imaging, engineering and other disciplines in the field of BBB, aiming to provide multi-dimensional research directions and clinical ideas for the treating NDs.

Iron overload induces cerebral endothelial senescence in aged mice and in primary culture in a sex-dependent manner

Iron imbalance in the brain negatively affects brain function. With aging, iron levels increase in the brain and contribute to brain damage and neurological disorders. Changes in the cerebral vasculature with aging may enhance iron entry into the brain parenchyma, leading to iron overload and its deleterious consequences. Endothelial senescence has emerged as an important contributor to age-related changes in the cerebral vasculature. Evidence indicates that iron overload may induce senescence in cultured cell lines. Importantly, cells derived from female human and mice generally show enhanced senescence-associated phenotype, compared with males. Thus, we hypothesize that cerebral endothelial cells (CEC) derived from aged female mice are more susceptible to iron-induced senescence, compared with CEC from aged males. We found that aged female mice, but not males, showed cognitive deficits when chronically treated with ferric citrate (FC), and their brains and the brain vasculature showed senescence-associated phenotype. We also found that primary culture of CEC derived from aged female mice, but not male-derived CEC, exhibited senescence-associated phenotype when treated with FC. We identified that the transmembrane receptor Robo4 was downregulated in the brain vasculature and in cultured primary CEC derived from aged female mice, compared with those from male mice. We discovered that Robo4 downregulation contributed to enhanced vulnerability to FC-induced senescence. Thus, our study identifies Robo4 downregulation as a driver of senescence induced by iron overload in primary culture of CEC and a potential risk factor of brain vasculature impairment and brain dysfunction.

Nanoparticles loaded with natural medicines for the treatment of Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease that disrupts cognitive function and severely affects the quality of life. Existing drugs only improve cognitive function and provide temporary relief of symptoms but do not stop or delay disease progression. Recently, natural medicines, especially Chinese herbal medicines, have gained attention in the treatment of AD due to their antioxidant, anti-inflammatory, and neuroprotective effects. However, conventional oral dosage forms lack brain specificity and have side effects that lead to poor patient compliance. Utilizing nanomedicine is a promising approach to improve brain specificity, bioavailability, and patient compliance. This review evaluates recent advances in the treatment of AD with nanoparticles containing various natural medicines. This review highlights that nanoparticles containing natural medicines are a promising strategy for the treatment of AD. It is believed that this technology can be translated into the clinic, thereby providing opportunities for AD patients to participate in social activities.

Reinventing the Penumbra - the Emerging Clockwork of a Multi-modal Mechanistic Paradigm

The concept of the ischemic penumbra was originally defined as the area around a necrotic stroke core and seen as the tissue at imminent risk of further damage. Today, the penumbra is generally considered as time-sensitive hypoperfused brain tissue with decreased oxygen and glucose availability, salvageable tissue as treated by intervention, and the potential target for neuroprotection in focal stroke. The original concept entailed electrical failure and potassium release but one short of neuronal cell death and was based on experimental stroke models, later confirmed in clinical imaging studies. However, even though the basic mechanisms have translated well, conferring brain protection, and improving neurological outcome after stroke based on the pathophysiological mechanisms in the penumbra has yet to be achieved. Recent findings shape the modern understanding of the penumbra revealing a plethora of molecular and cellular pathophysiological mechanisms. We now propose a new model of the penumbra, one which we hope will lay the foundation for future translational success. We focus on the availability of glucose, the brain's central source of energy, and bioenergetic failure as core pathophysiological concepts. We discuss the relation of mitochondrial function in different cell types to bioenergetics and apoptotic cell death mechanisms, autophagy, and neuroinflammation, to glucose metabolism in what is a dynamic ischemic penumbra.

Bloodletting Acupuncture at Jing-Well Points on Hand Induced Autophagy to Alleviate Brain Injury in Acute Altitude Hypoxic Rats by Activating PINK1/Parkin Pathway

OBJECTIVE

To explore the protective effect of bloodletting acupuncture at twelve Jing-well points on hand (BAJP) on acute hypobaric hypoxia (AHH)-induced brain injury in rats and its possible mechanisms.

METHODS

Seventy-five Sprague Dawley rats were divided into 5 groups by a random number table (n=15), including control, model, BAJP, BAJP+3-methyladenine (3-MA), and bloodletting acupuncture at non-acupoint (BANA, tail tip blooding) groups. After 7-day pre-treatment, AHH models were established using hypobaric oxygen chambers. The levels of S100B, glial fibrillary acidic protein (GFAP), superoxide dismutase (SOD), and malondialdehyde (MDA) in serum were measured by enzyme-linked immunosorbent assay. Hematoxylin-eosin staining and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling method were used to assess hippocampal histopathology and apoptosis. Transmission electron microscopy assay was used to observe mitochondrial damage and autophagosomes in hippocampal tissues. Flow cytometry was used to detect mitochondrial membrane potential (MMP). The mitochondrial respiratory chain complexes I, III and IV activities and ATPase in hippocampal tissue were evaluated, respectively. Western blot analysis was used to detect the protein expressions of Beclin1, autophagy protein 5 (ATG5), microtubule-associated protein 1 light chain 3 beta (LC3B), phosphatase and tensin homolog induced kinase 1 (PINK1), and Parkin in hippocampal tissues. The mRNA expressions of Beclin1, ATG5 and LC3-II were analyzed by quantitative real-time polymerase chain reaction.

RESULTS

BAJP treatment reduced hippocampal tissue injury and inhibited hippocampal cell apoptosis in AHH rats. BAJP reduced oxidative stress by decreasing S100B, GFAP and MDA levels and increasing SOD level in the serum of AHH rats (P<0.05 or P<0.01). Then, BAJP increased MMP, the mitochondrial respiratory chain complexes I, III and IV activities, and the mitochondrial ATPase activity in AHH rats (all P<0.01). BAJP improved mitochondrial swelling and increased the autophagosome number in hippocampal tissue of AHH rats. Moreover, BAJP treatment increased the protein and mRNA expressions of Beclin1 and ATG5 and LC3-II/LC3-I ratio in AHH rats (all P<0.01) and activated the PINK1/Parkin pathway (P<0.01). Finally, 3-MA attenuated the therapeutic effect of BAJP on AHH rats (P<0.05 or P<0.01).

CONCLUSION

BAJP was an effective treatment for AHH-induced brain injury, and the mechanism might be through reducing hippocampal tissue injury via increasing the PINK1/Parkin pathway and enhancement of mitochondrial autophagy.

Targeted Delivery of RGD-CD146+CD271+ Human Umbilical Cord Mesenchymal Stem Cell-Derived Exosomes Promotes Blood-Spinal Cord Barrier Repair after Spinal Cord Injury

Spinal cord injury (SCI) disrupts the blood-spinal cord barrier (BSCB), potentially exacerbating nerve damage and emphasizing the criticality of preserving the BSCB integrity during SCI treatment. This study explores an alternative therapeutic approach for SCI by identifying a subpopulation of exosomes with stable BSCB function and achieving a specific targeted delivery. Specific subpopulations of CD146+CD271+ umbilical cord mesenchymal stem cells (UCMSCs) were isolated, from which engineered exosomes (RGD-CD146+CD271+ UCMSC-Exos) with targeted neovascularization function were obtained through gene transfection. In vivo and in vitro experiments were performed to explore the targeting and therapeutic effects of RGD-CD146+CD271+ UCMSC-Exos and the potential mechanisms underlying BSCB stabilization and neural function recovery. The results demonstrated that RGD-CD146+CD271+ UCMSC-Exos exhibited physical and chemical properties similar to those of regular exosomes. Notably, following intranasal administration, RGD-CD146+CD271+ UCMSC-Exos exhibited enhanced aggregation at the SCI center and demonstrated the specific targeting of neovascular endothelial cells. In the SCI model, intranasal administration of RGD-CD146+CD271+ UCMSC-Exos reduced Evans blue dye leakage, increased tight junction protein expression, and improved neurological function recovery. In vitro testing revealed that RGD-CD146+CD271+ UCMSC-Exos treatment significantly reduced the permeability of bEnd.3 cells subjected to oxygen-glucose deprivation, thereby restoring the integrity of tight junctions. Moreover, further exploration of the molecular mechanism underlying BSCB stabilization by CD146+CD271+ UCMSC-Exos identified the crucial role of the miR-501-5p/MLCK axis in this process. In conclusion, targeted delivery of RGD-CD146+CD271+ UCMSC-Exos presents a promising and effective treatment option for SCI.

Butylphthalide improves brain damage induced by renal ischemia-reperfusion injury rats through Nrf2/HO-1 and NOD2/MAPK/NF-κB pathways

Renal ischemia-reperfusion (I/R) injury leads to irreversible brain damage with serious consequences. Activation of oxidative stress and release of inflammatory mediators are considered potential pathological mechanisms. Butylphthalide (NBP) has anti-inflammatory and antioxidant effects on I/R injuries. However, it is unclear whether NBP can effectively mitigate renal I/R secondary to brain injury as well as its mechanism, which are the aims of this study. Both renal I/R injury rats and oxygen and glucose deprivation cell models were established and pre-intervened NBP. The Morris water maze assay was used to detect behavior. Hippocampal histopathology and function were examined after renal I/R. Apoptosis and tube-forming capacity of brain microvascular endothelial cells (BMVECs) were tested. Immunohistochemistry and Western blot were used to measure protein expression of nuclear factor erythroid 2-related factor 2 (Nrf2)/Heme Oxygenase-1 (HO-1) pathway and NOD-like receptor C2 (NOD2)/Mitogen-activated protein kinases (MAPK)/Nuclear factor kappa-B (NF-κB) pathway. NBP treatment attenuated renal I/R-induced brain tissue damage and learning and memory dysfunction. NBP treatment inhibited apoptosis and promoted blood-brain barrier restoration and microangiogenesis. Also, it decreased oxidative stress levels and pro-inflammatory factor expression in renal I/R rats. Furthermore, NBP enhanced BMVECs' viability and tube-forming capacity while inhibiting apoptosis and oxidative stress. Notably, the alleviating effects of NBP were attributed to Nrf2/HO-1 pathway activation and NOD2/MAPK/NF-κB inhibition. This study demonstrates that NBP maintains BBB function by activating the Nrf2/HO-1 pathway and inhibiting the NOD2/MAPK/NF-κB pathway to suppress inflammation and oxidative stress, thereby alleviating renal I/R-induced brain injury.

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.

Genome-wide identification, evolution and expression analysis of tight junction gene family and the immune roles of claudin5 gene in turbot (Scophthalmus maximus L.)

Tight junction proteins (TJs) are important component proteins that maintaining the structure and function of TJs, connecting to each other to form a TJ complex between cells, maintaining the biological homeostasis of the internal environment. In this study, a total of 103 TJ genes were identified in turbot according to our whole-transcriptome database. Transmembrane TJs were divided into seven subfamilies, including claudin (CLDN), occludin (OCLD), tricellulin (MARVELD2), MARVEL domain containing 3 (MARVELD3), junctional adhesion molecules (JAM), immunoglobulin superfamily member 5 (IGSF5/JAM4), blood vessel epicardial substance (BVEs). Moreover, the majority of homologous pairs of TJ genes showed highly conserved alongside length, exon/intron number and motifs. As for phylogenetic analysis for 103 TJ genes, eight of them have undergone a positive selection and JAMB-like has undergone the most neutral evolution. The expression patterns of several TJ genes showed the lowest expression levels in blood, while the highest expression levels were detected in intestine, gill and skin, which all belong to mucosal tissues. Meanwhile, most examined TJ genes showed down-regulated expression patterns during bacterial infection, while several TJ genes exhibited up-regulated expression patterns at a later stage (24 h). At the same time, several potential candidate genes (such as CLDN-15, CLDN-3, CLDN-12, CLDN-5 and OCLD) were significantly down-regulated, which may indicate their important functions that involved in the regulation of bacterial infection. Currently, there is little research on CLDN5 in the intestine, but it is highly expressed in the intestine and has significant changes in intestinal expression after bacterial infection. Thus, we knocked down CLDN5 by the method of lentiviral infection. The result showed CLDN5 was related to cell migration (wound healing) and apoptosis, and the method of dualluciferasereporterassay showed that the functions of CLDN5 could be regulated by miR-24. The study of TJs may lead to a better understanding of the function of TJs in teleost.

Gastrodin relieves cognitive impairment by regulating autophagy via PI3K/AKT signaling pathway in vascular dementia

Vascular dementia (VaD), the second most common type of dementia, is attributed to lower cerebral blood flow. To date, there is still no available clinical treatment for VaD. The phenolic glucoside gastrodin (GAS) is known for its neuroprotective effects, but the role and mechanisms of action on VD remains unclear. In this study, we aim to investigate the neuroprotective role and underlying mechanisms of GAS on chronic cerebral hypoperfusion (CCH)-mediated VaD rats and hypoxia-induced injury of HT22 cells. The study showed that GAS relieved learning and memory deficits, ameliorated hippocampus histological lesions in VaD rats. Additionally, GAS down-regulated LC3II/I, Beclin-1 levels and up-regulated P62 level in VaD rats and hypoxia-injured HT22 cells. Notably, GAS rescued the phosphorylation of PI3K/AKT pathway-related proteins expression, which regulates autophagy. Mechanistic studies verify that YP-740, a PI3K agonist, significantly resulted in inhibition of excessive autophagy and apoptosis with no significant differences were observed in the YP-740 and GAS co-treatment. Meantime, we found that LY294002, a PI3K inhibitor, substantially abolished GAS-mediated neuroprotection. These results revealed that the effects of GAS on VaD are related to stimulating PI3K/AKT pathway-mediated autophagy, suggesting a potentially beneficial therapeutic strategy for VaD.

Physiological and pathological consequences of exosomes at the blood-brain-barrier interface

Blood-brain barrier (BBB) interface with multicellular structure controls strictly the entry of varied circulating macromolecules from the blood-facing surface into the brain parenchyma. Under several pathological conditions within the central nervous system, the integrity of the BBB interface is disrupted due to the abnormal crosstalk between the cellular constituents and the recruitment of inflammatory cells. Exosomes (Exos) are nano-sized extracellular vesicles with diverse therapeutic outcomes. These particles transfer a plethora of signaling molecules with the potential to modulate target cell behavior in a paracrine manner. Here, in the current review article, the therapeutic properties of Exos and their potential in the alleviation of compromised BBB structure were discussed. Video Abstract.

Chloroquine Protects Hypoxia/Ischemia-Induced Neonatal Brain Injury in Rats by Mitigating Blood-Brain Barrier Disruption

Neonatal hypoxic-ischemic (H/I) brain damage (HIBD) is a devastating condition for which there are presently no effective therapeutic strategies against its severe neurological deficits in neonates and young children. Traditionally, H/I induces the compromise of the blood-brain barrier (BBB), which causes neuronal cell death, eventually resulting in brain secondary injury. In addition to neonatal HIBD, chloroquine (CQ) has been proved to exert a protective effect on BBB disruption in several brain injury models. The main purpose of this research was to study whether CQ protects the BBB from H/I insult and confers beneficial neuroprotection in the neonatal Rice-Vannucci rat model. Herein, we reported that CQ administration significantly reduced brain damage and improved behavioral dysplasia after H/I injury. Moreover, we demonstrated the protective effects of CQ on BBB integrity, evidenced by ameliorating brain edema and Evans blue extravasation, inhibiting the degeneration of the tight junction and adherens junction proteins, and improving pericyte survival in neonatal rats after HIBD. These findings indicated that CQ administration protected the BBB against H/I injury, thereby ameliorating brain damage and promoting neurofunctional recovery. Collectively, our data demonstrated that CQ played a crucial role in BBB integrity after neonatal H/I injury, which sheds light on the development of therapeutic agents to treat HIBD.

Ischemia Reperfusion Injury Induced Blood Brain Barrier Dysfunction and the Involved Molecular Mechanism

Stroke is characterized by the abrupt failure of blood flow to a specific brain region, resulting in insufficient supply of oxygen and glucose to the ischemic tissues. Timely reperfusion of blood flow can rescue dying tissue but can also lead to secondary damage to both the infarcted tissues and the blood-brain barrier, known as ischemia/reperfusion injury. Both primary and secondary damage result in biphasic opening of the blood-brain barrier, leading to blood-brain barrier dysfunction and vasogenic edema. Importantly, blood-brain barrier dysfunction, inflammation, and microglial activation are critical factors that worsen stroke outcomes. Activated microglia secrete numerous cytokines, chemokines, and inflammatory factors during neuroinflammation, contributing to the second opening of the blood-brain barrier and worsening the outcome of ischemic stroke. TNF-α, IL-1β, IL-6, and other microglia-derived molecules have been shown to be involved in the breakdown of blood-brain barrier. Additionally, other non-microglia-derived molecules such as RNA, HSPs, and transporter proteins also participate in the blood-brain barrier breakdown process after ischemic stroke, either in the primary damage stage directly influencing tight junction proteins and endothelial cells, or in the secondary damage stage participating in the following neuroinflammation. This review summarizes the cellular and molecular components of the blood-brain barrier and concludes the association of microglia-derived and non-microglia-derived molecules with blood-brain barrier dysfunction and its underlying mechanisms.

Activation of aryl hydrocarbon receptor (AhR) in Alzheimer's disease: role of tryptophan metabolites generated by gut host-microbiota

Gut microbiota in interaction with intestinal host tissues influences many brain functions and microbial dysbiosis has been linked with brain disorders, such as neuropsychiatric conditions and Alzheimer's disease (AD). L-tryptophan metabolites and short-chained fatty acids (SCFA) are major messengers in the microbiota-brain axis. Aryl hydrocarbon receptors (AhR) are main targets of tryptophan metabolites in brain microvessels which possess an enriched expression of AhR protein. The Ah receptor is an evolutionarily conserved, ligand-activated transcription factor which is not only a sensor of xenobiotic toxins but also a pleiotropic regulator of both developmental processes and age-related tissue degeneration. Major microbiota-produced tryptophan metabolites involve indole derivatives, e.g., indole 3-pyruvic acid, indole 3-acetaldehyde, and indoxyl sulfate, whereas indoleamine and tryptophan 2,3-dioxygenases (IDO/TDO) of intestine host cells activate the kynurenine (KYN) pathway generating KYN metabolites, many of which are activators of AhR signaling. Chronic kidney disease (CKD) increases the serum level of indoxyl sulfate which promotes AD pathogenesis, e.g., it disrupts integrity of blood-brain barrier (BBB) and impairs cognitive functions. Activation of AhR signaling disturbs vascular homeostasis in brain; (i) it controls blood flow via the renin-angiotensin system, (ii) it inactivates endothelial nitric oxide synthase (eNOS), thus impairing NO production and vasodilatation, and (iii) it induces oxidative stress, stimulates inflammation, promotes cellular senescence, and enhances calcification of vascular walls. All these alterations are evident in cerebral amyloid angiopathy (CAA) in AD pathology. Moreover, AhR signaling can disturb circadian regulation and probably affect glymphatic flow. It seems plausible that dysbiosis of gut microbiota impairs the integrity of BBB via the activation of AhR signaling and thus aggravates AD pathology. KEY MESSAGES: Dysbiosis of gut microbiota is associated with dementia and Alzheimer's disease. Tryptophan metabolites are major messengers from the gut host-microbiota to brain. Tryptophan metabolites activate aryl hydrocarbon receptor (AhR) signaling in brain. The expression of AhR protein is enriched in brain microvessels and blood-brain barrier. Tryptophan metabolites disturb brain vascular integrity via AhR signaling. Dysbiosis of gut microbiota promotes inflammation and AD pathology via AhR signaling.

Hypoxia Inhibits Cell Cycle Progression and Cell Proliferation in Brain Microvascular Endothelial Cells via the miR-212-3p/MCM2 Axis

Hypoxia impairs blood-brain barrier (BBB) structure and function, causing pathophysiological changes in the context of stroke and high-altitude brain edema. Brain microvascular endothelial cells (BMECs) are major structural and functional elements of the BBB, and their exact role in hypoxia remains unknown. Here, we first deciphered the molecular events that occur in BMECs under 24 h hypoxia by whole-transcriptome sequencing assay. We found that hypoxia inhibited BMEC cell cycle progression and proliferation and downregulated minichromosome maintenance complex component 2 (Mcm2) expression. Mcm2 overexpression attenuated the inhibition of cell cycle progression and proliferation caused by hypoxia. Then, we predicted the upstream miRNAs of MCM2 through TargetScan and miRanDa and selected miR-212-3p, whose expression was significantly increased under hypoxia. Moreover, the miR-212-3p inhibitor attenuated the inhibition of cell cycle progression and cell proliferation caused by hypoxia by regulating MCM2. Taken together, these results suggest that the miR-212-3p/MCM2 axis plays an important role in BMECs under hypoxia and provide a potential target for the treatment of BBB disorder-related cerebrovascular disease.

Cobalt induces neurodegenerative damages through impairing autophagic flux by activating hypoxia-inducible factor-1α triggered ROS overproduction

Cobalt is an environmental toxicant, and excessive bodily exposure can damage the nervous system. Particularly, our previous study reported that low-dose cobalt (significantly less than the safety threshold) is still able to induce neurodegenerative changes. However, the underlying molecular mechanism is still insufficient revealed. Herein, we further investigate the molecular mechanism between cobalt-induced neurodegeneration and autophagy, as well as explore the interplay between hypoxia-inducible factor-1α (HIF-1α), reactive oxygen species (ROS), and autophagy in cobalt-exposed mice and human neuroglioma cells. We first reveal cobalt as an environmental toxicant to severely induce β amyloid (Aβ) deposition, tau hyperphosphorylation, and dysregulated autophagy in the hippocampus and cortex of mice. In particular, we further identify that cobalt-induced neurotoxicity is triggered by the impairment of autophagic flux in vitro experiments. Moreover, the mechanistic study reveals that cobalt exposure extremely activates HIF-1α expression to facilitate the overproduction of ROS. Then, elevated ROS can target the amino-threonine kinase (AKT)-mammalian target of rapamycin (mTOR)-Unc-51 like autophagy activating kinase 1 (ULK1) signaling pathway to participate in cobalt-induced impairment of autophagic flux. Subsequently, defected autophagy further exacerbates cobalt-induced neurotoxicity for its unable to eliminate the deposition of pathological protein. Therefore, our data provide scientific evidence for cobalt safety evaluation and risk assessment and propose a breakthrough for understanding the regulatory relationship between HIF-1α, ROS, and autophagy in cobalt-induced neurodegeneration.

Autophagy regulates inflammation in intracerebral hemorrhage: Enemy or friend?

Intracerebral hemorrhage (ICH) is the second-largest stroke subtype and has a high mortality and disability rate. Secondary brain injury (SBI) is delayed after ICH. The main contributors to SBI are inflammation, oxidative stress, and excitotoxicity. Harmful substances from blood and hemolysis, such as hemoglobin, thrombin, and iron, induce SBI. When cells suffer stress, a critical protective mechanism called "autophagy" help to maintain the homeostasis of damaged cells, remove harmful substances or damaged organelles, and recycle them. Autophagy plays a critical role in the pathology of ICH, and its function remains controversial. Several lines of evidence demonstrate a pro-survival role for autophagy in ICH by facilitating the removal of damaged proteins and organelles. However, many studies have found that heme and iron can aggravate SBI by enhancing autophagy. Autophagy and inflammation are essential culprits in the progression of brain injury. It is a fascinating hypothesis that autophagy regulates inflammation in ICH-induced SBI. Autophagy could degrade and clear pro-IL-1β and apoptosis-associated speck-like protein containing a CARD (ASC) to antagonize NLRP3-mediated inflammation. In addition, mitophagy can remove endogenous activators of inflammasomes, such as reactive oxygen species (ROS), inflammatory components, and cytokines, in damaged mitochondria. However, many studies support the idea that autophagy activates microglia and aggravates microglial inflammation via the toll-like receptor 4 (TLR4) pathway. In addition, autophagy can promote ICH-induced SBI through inflammasome-dependent NLRP6-mediated inflammation. Moreover, some resident cells in the brain are involved in autophagy in regulating inflammation after ICH. Some compounds or therapeutic targets that regulate inflammation by autophagy may represent promising candidates for the treatment of ICH-induced SBI. In conclusion, the mutual regulation of autophagy and inflammation in ICH is worth exploring. The control of inflammation by autophagy will hopefully prove to be an essential treatment target for ICH.

Claudin and pancreatic cancer

Due to the lack of timely and accurate screening modalities and treatments, most pancreatic cancer (PCa) patients undergo fatal PCa progression within a short period since diagnosis. The claudin(CLDN) family is expressed specifically as tight junction structure in a variety of tumors, including PCa, and affects tumor progression by changing the cell junctions. Thus far, many of the 27 members of the claudin family, including claudin-18.2 and claudin-4, have significantly aberrantly expression in pancreatic tumors. In addition, some studies have confirmed the role of some claudin proteins in the diagnosis and treatment of pancreatic tumors. By targeting different targets of claudin protein and combining chemotherapy, further enhance tumor cell necrosis and inhibit tumor invasion and metastasis. Claudins can either promote or inhibit the development of pancreatic cancer, which indicates that the diagnosis and treatment of different kinds of claudins require to consider different biological characteristics. This literature summarizes the functional characteristics and clinical applications of various claudin proteins in Pca cells, with a focus on claudin-18.2 and claudin-4.

Kruppel-like factor 2 contributes to blood-spinal cord barrier integrity and functional recovery from spinal cord injury by augmenting autophagic flux

Background: Increasing evidence suggests that acute traumatic spinal cord injury (SCI)-induced defects in autophagy and autophagy-lysosomal pathway (ALP) may contribute to endothelial barrier disruption following injury. Recently, Kruppel-like factor 2 (KLF2) was reported as a key molecular switch on regulating autophagy. Whether KLF2 coordinates endothelial endothelial ALP in SCI is not known. Methods: Genetic manipulations of KLF2 were performed in bEnd.3 cells and SCI model. Western blot, qRT-PCR, immunofluorescence staining and Lyso-Tracker Red staining, Evans blue dye extravasation, behavioral assessment via Basso mouse scale (BMS), electrophysiology and footprint analysis were performed. Results: In SCI, autophagy flux disruption in endothelial cells contributes to TJ proteins degradation, leading to blood-spinal cord barrier (BSCB) impairment. Furthermore, the KLF2 level was decreased in SCI, overexpression of which alleviated TJ proteins loss and BSCB damage, which improve motor function recovery in SCI mice, while knockdown of KLF2 displayed the opposite effects. At the molecular level, KLF2 overexpression alleviated the TJ proteins degradation and the endothelial permeability by tuning the ALP dysfunction caused by SCI and oxygen glucose deprivation (OGD). Conclusions: Endothelial KLF2 as one of the key contributors to SCI-mediated ALP dysfunction and BSCB disruption. KLF2 could be a promising pharmacological target for the management and treatment of SCI.

Wharton's jelly mesenchymal stem cells attenuate global hypoxia-induced learning and memory impairment via preventing blood-brain barrier breakdown

Objectives

Intracerebroventricular (ICV) injections of mesenchymal stem cells (MSCs) may improve the function and structure of blood-brain barrier (BBB), possibly by preserving the BBB integrity. This study examined the impact of Wharton's jelly (WJ)-MSCs on cognitive dysfunction and BBB disruption following a protracted hypoxic state.

Materials and Methods

Twenty-four male Wistar rats were randomly studied in four groups: Control (Co): Healthy animals, Sham (Sh): Rats were placed in the cage without hypoxia induction and with ICV injection of vehicle, Hypoxic (Hx)+vehicle: Hypoxic rats with ICV injection of vehicle (5 μl of PBS), and Hx+MSCs: Hypoxic rats with ICV injection of MSCs. Spatial learning and memory were evaluated one week after WJ-MSCs injection, and then animals were sacrificed for molecular research.

Results

Hypoxia increased latency and lowered the time and distance required reaching the target quarter, according to the findings. Furthermore, hypoxic rats had lower gene expression and protein levels of hippocampus vascular endothelial (VE)-cadherin, claudin 5, and tricellulin gene expression than Co and Sh animals (P<0.05). Finally, administering WJ-MSCs after long-term hypoxia effectively reversed the cognitive deficits and prevented the BBB breakdown via the upregulation of VE-cadherin, claudin 5, and tricellulin genes (P<0.05).

Conclusion

These findings suggest that prolonged hypoxia induces spatial learning and memory dysfunction and increases BBB disruption, the potential mechanism of which might be via reducing VE-cadherin, claudin 5, and tricellulin genes. Hence, appropriate treatment with WJ-MSCs could reverse ischemia adverse effects and protect the BBB integrity following prolonged hypoxia.

In-hospital mortality and SpO2 incritical care patients with cerebral injury: data from the MIMIC‑IV Database

BACKGROUND

Evidence regarding the relationship between in-hospital mortality and SpO2 was low oxygen saturations are often thought to be harmful, new research in patients with brain damage has found that high oxygen saturation actually enhances mortality. However, there is currently no clear study to point out the appropriate range for oxygen saturation in patients with craniocerebral diseases.  METHODS: By screening all patients in the MIMIC IV database, 3823 patients with craniocerebral diseases (according to ICD-9 codes and ICD-10) were selected, and non-linear regression was used to analyze the relationship between in-hospital mortality and oxygen saturation. Covariates for all patients included age, weight, diagnosis, duration of ICU stay, duration of oxygen therapy, etc. RESULTS: In-hospital mortality in patients with TBI and SAH was kept to a minimum when oxygen saturation was in the 94-96 range. And in all patients, the relationship between oxygen saturation and in-hospital mortality was U-shaped. Subgroup analysis of the relationship between oxygen saturation and mortality in patients with metabolic encephalopathy and other encephalopathy also draws similar conclusions In-hospital mortality and oxygen saturation were all U-shaped in patients with subarachnoid hemorrhage, metabolic and toxic encephalopathy, cerebral infarction, and other encephalopathy, but the nonlinear regression was statistically significant only in patients with cerebral infarction (p for nonlinearity = 0.002).

CONCLUSION

Focusing too much on the lower limit of oxygen saturation and ignoring too high oxygen saturation can also lead to increase in-hospital mortality. For patients with TBI and SAH, maintaining oxygen saturation at 94-96% will minimize the in-hospital mortality of patients.

Tong-Qiao-Huo-Xue decoction activates PI3K/Akt/mTOR pathway to reduce BMECs autophagy after cerebral ischemia/reperfusion injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tong-Qiao-Huo-Xue Decoction (TQHXD) is a traditional classic Chinese Medicinal Formula (CMF) used for clinical treatment of ischemic stroke. TQHXD leads to improvement in the symptoms of the acute period of cerebral infarction and recovery period after stroke. Our previous studies also showed that TQHXD produced a significant protective effect on the brain after cerebral ischemia-reperfusion (I/R) injury. It is reported that autophagy is closely related to ischemic brain injury; however, the functional contribution of TQHXD to brain microvascular endothelial cell (BMEC) autophagy and its underlying mechanism remains unclear.

AIM OF THE STUDY

The purpose of this study was to investigate the effects and mechanism of TQHXD in inhibiting cerebral ischemia-induced endothelial autophagy.

MATERIALS AND METHODS

The high-performance liquid chromatography (HPLC) fingerprint of the chemical constituents from TQHXD was established for the quality control, and the Longa method was used to evaluate the efficacy of TQHXD in rats with middle cerebral artery occlusion (MCAO). The expression of LC3 was determined by immunofluorescence double staining. To evaluate the protective effects of TQHXD-containing cerebrospinal fluid (CSF) on BMECs injured by oxygen-glucose deprivation and reperfusion, cell survival rate was determined using the CCK-8 assay and cell apoptosis was determined by fluorescein isothiocyanate (FITC)-Annexin V/PI. Autophagy was detected using transmission electron microscopy.

RESULTS

The results showed that TQHXD-CSF significantly ameliorated oxygen-glucose deprivation/reperfusion (OGD/R)-induced injury in BMECs. Confocal microscopy and Western blot results showed that TQHXD-CSF reduced autophagy-related protein expression and autophagosome number. The results of the western blotting indicated that TQHXD-CSF caused a marked increase in the phosphorylation of protein kinase B and phosphoinsotide-3 kinase (Akt/p-Akt and PI3K/p-PI3K, respectively) and their expression levels were down-regulated after treatment with pathway inhibitor, ZSTK474. Furthermore, in a MCAO model in rats, TQHXD markedly increased p-PI3K, p-Akt and p-mTOR, whereas the autophagy related proteins decreased.

CONCLUSIONS

Taken together, these findings demonstrate that TQHXD protects against ischemic insult by inhibiting autophagy through the regulation of the PI3K/Akt/mammalian target of rapamycin (mTOR) pathway and that TQHXD may have therapeutic value for protecting BMECs from cerebral ischemia.

Caveolin-1 accelerates hypoxia-induced endothelial dysfunction in high-altitude cerebral edema

Background

High-altitude cerebral edema (HACE) is a serious and potentially fatal brain injury that is caused by acute hypobaric hypoxia (HH) exposure. Vasogenic edema is the main pathological factor of this condition. Hypoxia-induced disruptions of tight junctions in the endothelium trigger blood‒brain barrier (BBB) damage and induce vasogenic edema. Nuclear respiratory factor 1 (NRF1) acts as a major regulator of hypoxia-induced endothelial cell injury, and caveolin-1 (CAV-1) is upregulated as its downstream gene in hypoxic endothelial cells. This study aimed to investigate whether CAV-1 is involved in HACE progression and the underlying mechanism.

Methods

C57BL/6 mice were exposed to HH (7600 m above sea level) for 24 h, and BBB injury was assessed by brain water content, Evans blue staining and FITC-dextran leakage. Immunofluorescence, transmission electron microscope, transendothelial electrical resistance (TEER), transcytosis assays, and western blotting were performed to confirm the role and underlying mechanism of CAV-1 in the disruption of tight junctions and BBB permeability. Mice or bEnd.3 cells were pretreated with MβCD, a specific blocker of CAV-1, and the effect of CAV-1 on claudin-5 internalization under hypoxic conditions was detected by immunofluorescence, western blotting, and TEER. The expression of NRF1 was knocked down, and the regulation of CAV-1 by NRF1 under hypoxic conditions was examined by qPCR, western blotting, and immunofluorescence.

Results

The BBB was severely damaged and was accompanied by a significant loss of vascular tight junction proteins in HACE mice. CAV-1 was significantly upregulated in endothelial cells, and claudin-5 explicitly colocalized with CAV-1. During the in vitro experiments, hypoxia increased cell permeability, CAV-1 expression, and claudin-5 internalization and downregulated tight junction proteins. Simultaneously, hypoxia induced the upregulation of CAV-1 by activating NRF1. Blocking CAV-1-mediated intracellular transport improved the integrity of TJs in hypoxic endothelial cells and effectively inhibited the increase in BBB permeability and brain water content in HH animals.

Conclusions

Hypoxia upregulated CAV-1 transcription via the activation of NRF1 in endothelial cells, thus inducing the internalization and autophagic degradation of claudin-5. These effects lead to the destruction of the BBB and trigger HACE. Therefore, CAV-1 may be a potential therapeutic target for HACE.

Glaesserella parasuis serotype 5 breaches the porcine respiratory epithelial barrier by inducing autophagy and blocking the cell membrane Claudin-1 replenishment

Glaesserella parasuis (G. parasuis), the primary pathogen of Glässer's disease, colonizes the upper respiratory tract and can break through the epithelial barrier of the respiratory tract, leading to lung infection. However, the underlying mechanisms for this adverse effect remain unclear. The G. parasuis serotype 5 SQ strain (HPS5-SQ) infection decreased the integrity of piglets' lung Occludin and Claudin-1. Autophagy regulates the function of the epithelial barrier and tight junction proteins (TJs) expression. We tested the hypothesis that HPS5-SQ breaking through the porcine respiratory epithelial barrier was linked to autophagy and Claudin-1 degradation. When HPS5-SQ infected swine tracheal epithelial cells (STEC), autophagosomes encapsulated, and autolysosomes degraded oxidatively stressed mitochondria covered with Claudin-1. Furthermore, we found that autophagosomes encapsulating mitochondria resulted in cell membrane Claudin-1 being unable to be replenished after degradation and damaged the respiratory tract epithelial barrier. In conclusion, G. parasuis serotype 5 breaks through the porcine respiratory epithelial barrier by inducing autophagy and interrupting cell membrane Claudin-1 replenishment, clarifying the mechanism of the G. parasuis infection and providing a new potential target for drug design and vaccine development.

Effect of rapamycin treatment on oocyte in vitro maturation and embryonic development after parthenogenesis in yaks

Autophagy plays an important role in mammalian oocyte maturation and early embryonic development and rapamycin is well known for inducing autophagy. Although previous studies have reported the effects of rapamycin on oocytes in vitro maturation (IVM) in different species, few studies have been reported on the role of rapamycin in yak oocytes IVM and embryonic development. Therefore, the objective of this study was to examine the effect of rapamycin treatment on yak oocytes IVM and early embryonic development. Specifically, immature yak oocytes during IVM or parthenogenetic (PA) embryos were treated with different rapamycin concentrations to select an optimal dose. Then evaluated its effect on maturation rates, cleavage, and blastocyst formation rates, mitochondrial membrane potential, ROS levels. Related genes and proteins expression in matured oocytes and blastocysts were also evaluated. The results show that 10 nM rapamycin treatment during IVM significantly improved oocyte maturation rates of oocytes and blastocyst formation rates. Treatment with 10 nM rapamycin reduced ROS level but increased mitochondrial membrane potential. Correspondingly, mRNA and protein expressions of LC3, Beclin-1, and Bcl-2 up-regulated while Bax down-regulated in matured yak COCs. When parthenogenetic embryos were treated with different rapamycin concentrations, 10 nM rapamycin treatment showed higher 8-cell and blastocyst formation rates. Also, CDX2, POU5F1, SOX2, and Nanog levels in blastocysts were upregulated. In summary, our findings demonstrate that rapamycin treatment improves oocytes maturation probably by increasing mitochondrial membrane potential, reducing ROS levels, and regulating the apoptosis in mature yak oocytes. Rapamycin treatment also improves embryonic developmental competence in the yak.

Intrinsically Bioactive Manganese-Eumelanin Nanocomposites Mediated Antioxidation and Anti-Neuroinflammation for Targeted Theranostics of Traumatic Brain Injury

Overproduced reactive oxygen species and the induced oxidative stress and neuroinflammation often result in secondary injury, which is associated with unfavorable prognosis in traumatic brain injury (TBI). Unfortunately, current medications cannot effectively ameliorate the secondary injury at traumatic sites. Here, it is reported that intrinsically bioactive multifunctional nanocomposites (ANG-MnEMNPs-Cur, AMEC) mediate antioxidation and anti-neuroinflammation for targeted TBI theranostics, which are engineered by loading the neuroprotective agent curcumin on angiopep-2 functionalized and manganese doped eumelanin-like nanoparticles. After intravenous delivery, efficient AMEC accumulation is observed in lesions of TBI mice models established by controlled cortical impact method, evidenced by T₁ -T₂ magnetic resonance and photoacoustic dual-modal imaging. Therapeutically, AMEC effectively alleviates neuroinflammation, protects blood-brain barrier integrity, relieves brain edema, reduces brain tissue loss, and improves the cognition of TBI mice. Mechanistically, following the penetration into the traumatic tissues via angiopep-2 mediated targeting effect, the efficacy of AMEC is synergistically improved by combined functional moieties of curcumin and eumelanin. This is achieved by the alleviation of oxidative stress, inhibition of neuroinflammation via M1-to-M2 macrophage reprogramming, and promotion of neuronal regeneration. The as-developed AMEC with well-defined mechanisms of action may represent a promising targeted theranostics strategy for TBI and other neuroinflammation-associated intracranial diseases.

Muscone and (+)-Borneol Cooperatively Strengthen CREB Induction of Claudin 5 in IL-1β-Induced Endothelium Injury

Claudin 5 is one of the major proteins of tight junctions and is responsible for cerebrovascular integrity and BBB function. Muscone and (+)-borneol is the major ingredient of moschus and borneolum, respectively, with antioxidative and anti-inflammatory activities. This study investigated whether muscone and (+)-borneol combination protected claudin 5 by targeting ROS-mediated IL-1β accumulation. Muscone and (+)-borneol reduced cerebral infarct volume and cerebrovascular leakage with claudin 5 protection in mice after stroke, largely due to inhibiting ROS accumulation and inflammatory infiltrate of microglia. Muscone reduced ROS and then blocked the CaN/Erk1/2 pathway to decrease IL-1β release, while (+)-borneol removed mitochondrial ROS and attenuated the SDH/Hif-1α pathway to inhibit IL-1β transcription, thereby jointly reducing IL-1β production. Accumulated IL-1β disrupted cAMP/CREB activation and attenuated transcriptional regulation of claudin 5. Muscone and (+)-borneol combination cooperatively protected BBB function by blocking IL-1β-mediated cAMP/CREB/claudin 5 cascades. Mutation of Ser133 site of CREB or knockdown of claudin 5 weakened the effects of muscone and (+)-borneol on upregulation of TEER value and downregulation of FITC-dextran permeability, suggesting that targeting CREB/claudin 5 was an important strategy to protect vascular integrity. This study provided ideas for the studies of synergistic protection against ischemic brain injury about the active ingredients of traditional Chinese medicines (TCMs).

Role of Caveolin-1 in Sepsis – A Mini-Review

Sepsis is a generalized disease characterized by an extreme response to a severe infection. Moreover, challenges remain in the diagnosis, treatment and management of septic patients. In this mini-review we demonstrate developments on cellular pathogenesis and the role of Caveolin-1 (Cav-1) in sepsis. Studies have shown that Cav-1 has a significant role in sepsis through the regulation of membrane traffic and intracellular signaling pathways. In addition, activation of apoptosis/autophagy is considered relevant for the progression and development of sepsis. However, how Cav-1 is involved in sepsis remains unclear, and the precise mechanisms need to be further investigated. Finally, the role of Cav-1 in altering cell permeability during inflammation, in sepsis caused by microorganisms, apoptosis/autophagy activation and new therapies under study are discussed in this mini-review.