Blood-brain Barrier Integrity Research Articles

The role of histohematologic barriers and the possibility of using polarization biomedical optics methods in the diagnosis of autoimmune thyroiditis

Background. Violation of the integrity of the histohematologic barriers (blood-brain, blood-testis, blood-ocular, blood-labyrinth, blood-thyroid) leads to autoimmune damage to these organs. One of the manifestations of the latter is autoimmune thyroiditis, the structural and quantitative changes of which can be more informatively accurately assessed by polarization biomedical optics. The purpose of the study was to substantiate the possibility of using polarization biomedical optics methods in the diagnosis of autoimmune thyroiditis based on the use of pathophysiological analysis of blood-brain barrier integrity disorders. Materials and methods. Two groups of patients were studied: control group 1 — healthy donors (n = 51), study group 2 — people with autoimmune thyroiditis (n = 51) who underwent a puncture biopsy of the thyroid gland for diagnostic purposes. Instrumental laser methods were used: polarization, interference, multifractal. The statistical parameters of polarization ellipticity maps, polarization ellipticity of phase and multifractal spectra of digital microscopic images of native thyroid histological sections in patients with autoimmune thyroiditis were quantified: mean, dispersion, asymmetry, and kurtosis. The probability of differences compared to the controls, taken as 100 %, was evaluated using the Student’s parametric test (p < 0.05). Results. A significant increase in the mean and variance at inhibition of the asymmetry and kurtosis of polarization ellipticity, as well as in the mean and variance at reduction of the asymmetry and kurtosis of polarization ellipticity of phase digital microscopic images of thyroid native histological sections was revealed. There were a significant increase in dispersion and a decrease in the asymmetry and kurtosis of multifractal spectra of polarization ellipticity maps of digital microscopic images of native histological sections. Conclusions. A significant increase in the biophysical optical parameters of digital microscopic images of thyroid native histological sections from patients with autoimmune thyroiditis was found due to the growth of connective tissue in the interstitium as a result of an autoimmune inflammation. There was a significant inhibition of the asymmetry and kurtosis of the ellipticity of polarization of phase digital and multifractal spectra of polarization ellipticity maps of microscopic images of native histological sections in patients with autoimmune thyroiditis due to a decrease in the amount of colloids as a crystalline component caused by damage to the blood-thyroid barrier.

Effects of cold stress on the blood-brain barrier in Plectropomus leopardus

BackgroundThe leopard coral grouper (Plectropomus leopardus) is a commercially valuable tropical marine fish species known to be sensitive to low temperatures. A comprehensive understanding of the molecular mechanisms governing its response to acute cold stress is of great importance. However, there is a relative scarcity of fundamental research on low-temperature tolerance in the leopard coral grouper.MethodsIn this study, a cooling and rewarming experiment was conducted on 6-month-old leopard coral groupers. Within 24 h, we decreased the ambient temperature from 25 °C to 13 °C and subsequently allowed it to naturally return to 25 °C. During this process, a comprehensive investigation of serum hormone levels, enzyme activity, and brain transcriptome analysis was performed.ResultsP. leopardus displayed a noticeable adaptive response to the initial temperature decrease by temporarily reducing its life activities. Our transcriptome analysis revealed that the differentially expressed genes (DEGs) were primarily concentrated in crucial pathways including the blood-brain barrier (BBB), inflammatory response, and coagulation cascade. In situ hybridization of claudin 15a (cldn15a), a key gene for BBB maintaining, further confirmed that exposure to low temperatures led to the disruption of the blood-brain barrier and stimulated a pronounced inflammatory reaction within the brain. Upon rewarming, there was a recovery of BBB integrity accompanied by the persistence of inflammation within the brain tissue.ConclusionsOur study reveals the complex interactions between blood-brain barrier function, inflammation, and recovery in P. leopardus during short-term temperature drops and rewarming. These findings provide valuable insights into the physiological responses of this species under cold stress conditions.

The Neuroprotection of 1,2,4-Triazole Derivative by Inhibiting Inflammation and Protecting BBB Integrity in Acute Ischemic Stroke.

The oxidative stress and neuroinflammation are important factors in acute ischemic stroke (AIS). Our former study showed the 1,2,4- triazole derivative (SYS18) had obviously neuroprotection by anti- oxidative stress on rat middle cerebral artery occlusion (MCAO) model. In this study, we continue to investigate its neuroprotection by anti-inflammatory effects and protecting BBB integrity in AIS. First, its effect on acute inflammation was evaluated by the mice model of increased peritoneal capillary permeability. Then, the MCAO cerebral edema models were built to evaluate its neuroprotection by reducing the neurological score, cerebral edema, improving the biochemical indicators, and pathological damage of brain tissue. At the same time, its protection on blood-brain barrier (BBB) integrity was proved by decreasing the BBB permeability and inhibiting glycocalyx degradation and regulating the BBB tight junction proteins expression of matrix metalloproteinase- 9 (MMP- 9) and claudin- 5 in brain tissue. Meanwhile, pharmacokinetic experiments showed that the compound had good BBB penetration. It has some advantages in the intensity of efficacy compared with the marketed drug edaravone. Based on these findings, SYS18 has a strong potential to become a neuroprotectant in the future.

P43 Unmasking posterior reversible encephalopathy syndrome: a hidden threat in juvenile lupus

Abstract Introduction Posterior reversible encephalopathy syndrome (PRES) is a neurological condition identifiable through clinical presentation and magnetic resonance imaging (MRI). While PRES has been rarely documented in children as a complication of juvenile lupus, it remains a potentially reversible condition. However, it can be complicated by vasculopathy, infarction, or haemorrhage. The pathogenesis of PRES is still unclear. In juvenile lupus, the risk factors for PRES are multifaceted and interact with each other, including vasculitis, lupus nephritis, chronic kidney disease (CKD) leading to renal-origin hypertension, and iatrogenic hypertension caused by several hypertension-inducing drugs commonly used as first-line treatments for lupus. Case description A 14-year-old girl diagnosed with lupus presented with persistent fatigue, lower limb oedema, and abdominal symptoms (vomiting and diarrhoea). She experienced two episodes of PRES, three months apart. Active SLE was confirmed through clinical and laboratory findings, including positive autoimmune and serologic results for ENA antibody screen, high levels of anti-double-stranded DNA (>400), and low complements C3 (0.15 g/L) and C4 (<0.03 g/L). Urine analysis revealed 2+ RBCs, 3+ proteins, and an estimated glomerular filtration rate (eGFR) of ∼21 ml/min/1.73 m² with a plasma creatinine of 226 micromol/L. Renal biopsy identified lupus nephritis class IV and chronic kidney disease (CKD) changes, leading to a diagnosis of CKD stage 4. Initial treatment included a course of pulse methylprednisolone (1 g daily for 3 days) alongside rituximab and MMF for remission induction followed by high-dose oral prednisone (2 mg/kg/d). Her blood pressure started to increase following the first methylprednisolone pulse. In addition, two weeks later, severe fluid overload necessitated dialysis. Despite dialysis and the use of four antihypertensive agents (lisinopril, amlodipine, atenolol, doxazosin), her blood pressure fluctuated and remained uncontrolled. A week later, she experienced focal seizures. While a CT brain scan showed no abnormalities, an MRI revealed multifocal areas of bilateral cerebral hemispheric cortico-subcortical signal and diffusion alteration, indicating evolving PRES. A steroid weaning plan was implemented, and IV cyclophosphamide was initiated according to the National Institutes of Health protocol. Eight weeks later, she had another PRES episode, presenting with seizures confirmed by MRI findings. On both occasions, hypertensive encephalopathy was promptly recognized, and she was transferred to the PICU. Fortunately, her symptoms completely resolved within 12 hours of anticonvulsant and antihypertensive therapies. Discussion Common triggers of PRES include autoimmune conditions such as systemic lupus erythematosus (SLE), hypertensive encephalopathy, and drug toxicities (mainly cytotoxic and immunosuppressive drugs), all of which interact in lupus patients. However, it remains unclear how each factor contributes to the development of PRES. Additionally, the exact pathophysiological mechanism behind PRES is still debated. The two most widely accepted hypotheses involve: firstly, increased arterial blood pressure overwhelming cerebral autoregulatory mechanisms, leading to vascular leakage and vasogenic oedema. Secondly, endothelial dysfunction, where endothelial damage caused by circulating toxins enhances the release of vasoactive and immunogenic agents, altering vascular permeability. Our patient’s development of PRES is multifactorial, with lupus nephritis being a primary cause, aggravated by chronic kidney disease, leading to salt and water retention, which was further exacerbated by prednisolone. Other drugs, such as rituximab and cyclophosphamide, might have also been implicated in causing hypertension. PRES following rituximab infusion has been documented, with onset ranging from immediately after infusion to up to four weeks later. Proposed mechanisms include compromised blood-brain barrier integrity and immune dysregulation. Intravenous cyclophosphamide has also been identified as a potential trigger for PRES in patients with and without SLE, though the exact reason for this remains unclear. The dual role of these drugs in potentially precipitating life-threatening risks like PRES while being therapeutic agents presents a confusing dilemma. Much remains to be learned to enable the prevention and prompt response to PRES. Key learning points • Juvenile lupus with PRES is an uncommon neurological manifestation influenced by multiple factors. • Risk factors for PRES in juvenile lupus include lupus nephritis, CKD secondary to lupus, and iatrogenic hypertension including steroids, rituximab, and cyclophosphamide. These factors commonly exist and interplay together. • The pathogenesis of PRES in lupus, including the role of drugs, remains unclear. • Patients with lupus should be closely monitored, particularly their blood pressure. • Early diagnosis and prompt treatment of PRES can reverse radiologic and neurologic findings, leading to a favourable prognosis.

Neurons enhance blood–brain barrier function via upregulating claudin-5 and VE-cadherin expression due to glial cell line-derived neurotrophic factor secretion

Blood–brain barrier (BBB) prevents neurotoxins from entering central nervous system. We aimed to establish and characterize an in vitro triple co-culture BBB model consisting of brain endothelial cells hCMEC/D3, astrocytoma U251 cells, and neuroblastoma SH-SY5Y cells. Co-culture of SH-SY5Y and U251 cells markedly enhanced claudin-5 and VE-cadherin expression in hCMEC/D3 cells, accompanied by increased transendothelial electrical resistance and decreased permeability. Conditioned medium (CM) from SH-SY5Y cells (S-CM), U251 cells (U-CM), and co-culture of SH-SY5Y and U251 cells (US-CM) also promoted claudin-5 and VE-cadherin expression. Glial cell line-derived neurotrophic factor (GDNF) levels in S-CM and US-CM were significantly higher than CMs from hCMEC/D3 and U-CM. Both GDNF and US-CM upregulated claudin-5 and VE-cadherin expression, which were attenuated by anti-GDNF antibody and GDNF signaling inhibitors. GDNF increased claudin-5 expression via the PI3K/AKT/FOXO1 and MAPK/ERK pathways. Meanwhile, GDNF promoted VE-cadherin expression by activating PI3K/AKT/ETS1 and MAPK/ERK/ETS1 signaling. The roles of GDNF in BBB integrity were validated using brain-specific Gdnf silencing mice. The developed triple co-culture BBB model was successfully applied to predict BBB permeability. In conclusion, neurons enhance BBB integrity by upregulating claudin-5 and VE-cadherin expression through GDNF secretion and established triple co-culture BBB model may be used to predict drugs’ BBB permeability.

Neurons enhance blood-brain barrier function via upregulating claudin-5 and VE-cadherin expression due to glial cell line-derived neurotrophic factor secretion.

Blood-brain barrier (BBB) prevents neurotoxins from entering central nervous system. We aimed to establish and characterize an in vitro triple co-culture BBB model consisting of brain endothelial cells hCMEC/D3, astrocytoma U251 cells, and neuroblastoma SH-SY5Y cells. Co-culture of SH-SY5Y and U251 cells markedly enhanced claudin-5 and VE-cadherin expression in hCMEC/D3 cells, accompanied by increased transendothelial electrical resistance and decreased permeability. Conditioned medium (CM) from SH-SY5Y cells (S-CM), U251 cells (U-CM), and co-culture of SH-SY5Y and U251 cells (US-CM) also promoted claudin-5 and VE-cadherin expression. Glial cell line-derived neurotrophic factor (GDNF) levels in S-CM and US-CM were significantly higher than CMs from hCMEC/D3 and U-CM. Both GDNF and US-CM upregulated claudin-5 and VE-cadherin expression, which were attenuated by anti-GDNF antibody and GDNF signaling inhibitors. GDNF increased claudin-5 expression via the PI3K/AKT/FOXO1 and MAPK/ERK pathways. Meanwhile, GDNF promoted VE-cadherin expression by activating PI3K/AKT/ETS1 and MAPK/ERK/ETS1 signaling. The roles of GDNF in BBB integrity were validated using brain-specific Gdnf silencing mice. The developed triple co-culture BBB model was successfully applied to predict BBB permeability. In conclusion, neurons enhance BBB integrity by upregulating claudin-5 and VE-cadherin expression through GDNF secretion and established triple co-culture BBB model may be used to predict drugs' BBB permeability.

Effects of Artemisia asiatica ex on Akkermansia muciniphila dominance for modulation of Alzheimer's disease in mice.

The gut microbiome influences neurological disorders through bidirectional communication between the gut and the brain, i.e., the gut-brain axis. Artemisia asiatica ex, an extract of Artemisia asiatica Nakai (Stillen®, DA-9601) has been reported to improve depression by increasing brain-derived neurotropic factor. Therefore, we hypothesized that DA-9601 can be a potential therapeutic candidate for Alzheimer's disease (AD) acting through the gut-brain axis. Four groups of Tg2576 mice were used as the animal model for AD: wild type mice (n = 6), AD mice (n = 6), and DA-9601-administered AD mice given dosages of 30mg/kg/day (DA_30mg; n = 6) or 100mg/kg/day (DA_100mg; n = 6). Microglial activation, blood‒brain barrier integrity, amyloid beta accumulation, cognitive behavior, and changes in the gut microbiome were analyzed. DA-9601 improved the cognitive behavior of mice (DA_30mg **p<0.01; DA_100mg **p<0.01) and reduced amyloid beta accumulation (DA_30mg ***p<0.001; DA_100mg **p<0.01). Increased Iba-1 and upregulation of claudin-5 (DA_30mg *p<0.05) and occludin (DA_30mg **p<0.01; DA_100mg ***p<0.001) indicated altered microglial activation and improved blood‒brain barrier integrity. Akkermansia muciniphila was dramatically increased by DA-9601 administration (DA_30mg 47%; DA_100mg 61%). DA-9601 improved AD pathology with Akkermansia muciniphila dominance in the gut microbiome in a mouse model of AD, inferring that DA-9601 can affect AD through the gut-brain axis.

The impacts of tobacco and nicotine on HIV-1 infection, inflammation, and the blood-brain barrier in the central nervous system

Human immunodeficiency virus (HIV-1) remains a persistent global health crisis. Even while successfully virologically suppressed, people with HIV (PWH) experience a higher risk for inflammatory disorders such as HIV-associated neurocognitive disorder (HAND). Tobacco use puts PWH at higher risk for neurocognitive symptoms resulting from HIV-associated neuroinflammation. The NLR Family Pyrin Domain Containing 3 (NLRP3) inflammasome has been implicated as a driver of HIV-associated inflammation, including HAND. Nicotine, the psychoactive component of tobacco smoke, has also been shown to signal through the NLRP3 inflammasome and modulate inflammatory signaling in the CNS. Here, we explore the impacts of nicotine and tobacco on the complex neurobiology of HAND, including effects on cognition, inflammation, viral latency, and blood-brain barrier integrity. We outline nicotine’s role in the establishment of active and latent infection in the brain and posit the NLRP3 inflammasome as a common pathway by which HIV-1 and nicotine promote neuroinflammation in PWH.

Apolipoprotein C3-rich low-density lipoprotein (AC3RL) exacerbates cerebral ischaemic stroke injury by increasing BBB leakage via LOX-1

Abstract Background Ischaemic stroke causes the abrupt reduction or cessation of blood flow to the brain results in a cascade of events that can compromise blood-brain barrier (BBB) integrity. We revealed that an increase in apolipoprotein C3 (ApoC3)-rich low-density lipoprotein (AC3RL) is associated with endothelial cell apoptosis and inflammatory responses, indicating that AC3RL is one of the risk factors for cardiovascular events. Lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) triggers a cascade of events within endothelial cells that leads to endothelial dysfunction. Purpose We aimed to investigate whether AC3RL affects BBB permeability via the LOX-1, and thus increases brain damage. Methods We collected the whole blood from normal and patients with ischaemic events and separated them by centrifugation. AC3RL were collected using FPLC. We performed middle cerebral artery occlusion (MCAO) surgery to induce ischaemic stroke using B6 (C57BL/6) and LOX-1-/- mice injected with AC3RL. Triphenyl tetrazolium chloride (TTC) and Evans blue stains were accessed to confirm brain injury and BBB permeability. Results FPLC results showed that patients with ischaemic events presented higher levels of AC3RL compared to normal people. TTC stain showed the increased area of ischaemic penumbra damage in B6 mice with AC3RL injection, and LOX-1-/- mice with AC3RL injection were significantly protected. Evans blue dye leakage was observed in the brain tissues of B6 mice with AC3RL injection. LOX-1-/- mice with AC3RL injection revealed a decrease in BBB permeability. The modified neurological severity score (mNSS) method revealed a significant rise in B6 mice with AC3RL injection, which suggested a decline in motor and nervous function. LOX-1-/- mice with AC3RL injection significantly improved in motor and neurological functioning. Conclusions We demonstrate that AC3RL, through its effects on LOX-1, is associated with an increased risk of BBB damage after stroke. Therefore, pharmacological inhibition of AC3RL-LOX-1 interaction will be the main strategy to reduce severe brain damage. Figure 1: (A) AC3RL percentage (%) in individuals. Normal: healthy people, Ischemic event: patients who have experienced an ischemic event. **p &amp;lt; 0.001 vs. Normal group. (B, C) TTC stain of brain tissue after euthanasia to pinpoint the site of brain damage. The white portion of the mice brains indicated the site of the injury. (D, E) Evans blue dye leakage study in mice brains exhibited BBB permeability changes. (F) Assessment of mice's motor and neurological performance using the mNSS. Data are expressed as the mean ± SEM. **p &amp;lt; 0.001, ****p &amp;lt; 0.0001 vs. sham group, ##p &amp;lt; 0.001 vs. B6 I.V. AC3RL group.Graphical abstractFigure 1.

Brain inflammaging in the pathogenesis of late-life depression.

Late-life depression (LLD) is a prevalent mental disorder among older adults. Previous studies revealed that many pathologic factors are associated with the onset and development of LLD. However, the precise mechanisms that cause LLD remain elusive. Aging induces chronic inflammatory changes mediated by alterations of immune responses. The chronic systemic inflammation termed "inflammaging" is linked to the etiology of aging-related disorders. Aged microglia induce senescence-associated secretory phenotype (SASP) and transition to M1-phenotype, cause neuroinflammation, and diminish neuroprotective effects. In addition, there is an age-dependent loss of blood-brain barrier (BBB) integrity. As the BBB breakdown can lead to invasion of immune cells into brain parenchyma, peripheral immunosenescence may cause microglial activation and neuroinflammation. Therefore, it is suggested that these mechanisms related to brain inflammaging may be involved in the pathogenesis of LLD. In this review, we described the role of brain inflammaging in LLD. Pharmacologic approaches to prevent brain inflammaging appears to be a promising strategy for treating LLD.

Association Between the Gut Microbiota and Alzheimer's Disease: An Update on Signaling Pathways and Translational Therapeutics.

Alzheimer's disease (AD) is a cognitive disease with high morbidity and mortality. In AD patients, the diversity of the gut microbiota is altered, which influences pathology through the gut-brain axis. Probiotic therapy alleviates pathological and psychological consequences by restoring the diversity of the gut microbial flora. This study addresses the role of altered gut microbiota in the progression of neuroinflammation, which is a major hallmark of AD. This process begins with the activation of glial cells, leading to the release of proinflammatory cytokines and the modulation of cholinergic anti-inflammatory pathways. Short-chain fatty acids, which are bacterial metabolites, provide neuroprotective effects and maintain blood‒brain barrier integrity. Furthermore, the gut microbiota stimulates oxidative stress and mitochondrial dysfunction, which promote AD progression. The signaling pathways involved in gut dysbiosis-mediated neuroinflammation-mediated promotion of AD include cGAS-STING, C/EBPβ/AEP, RAGE, TLR4 Myd88, and the NLRP3 inflammasome. Preclinical studies have shown that natural extracts such as Ganmaidazao extract, isoorentin, camelia oil, Sparassis crispa-1, and xanthocerasides improve gut health and can delay the worsening of AD. Clinical studies using probiotics such as Bifidobacterium spp., yeast beta-glucan, and drugs such as sodium oligomannate and rifaximine have shown improvements in gut health, resulting in the amelioration of AD symptoms. This study incorporates the most current research on the pathophysiology of AD involving the gut microbiota and highlights the knowledge gaps that need to be filled to develop potent therapeutics against AD.

IL-33/ST2 signaling in monocyte-derived macrophages maintains blood-brain barrier integrity and restricts infarctions early after ischemic stroke

BackgroundBrain microglia and infiltrating monocyte-derived macrophages are vital in preserving blood vessel integrity after stroke. Understanding mechanisms that induce immune cells to adopt vascular-protective phenotypes may hasten the development of stroke treatments. IL-33 is a potent chemokine released from damaged cells, such as CNS glia after stroke. The activation of IL-33/ST2 signaling has been shown to promote neuronal viability and white matter integrity after ischemic stroke. The impact of IL-33/ST2 on blood-brain barrier (BBB) integrity, however, remains unknown. The current study fills this gap and reveals a critical role of IL-33/ST2 signaling in macrophage-mediated BBB protection after stroke.MethodsTransient middle cerebral artery occlusion (tMCAO) was performed to induce ischemic stroke in wildtype (WT) versus ST2 knockout (KO) male mice. IL-33 was applied intranasally to tMCAO mice with or without dietary PLX5622 to deplete microglia/macrophages. ST2 KO versus WT bone marrow or macrophage cell transplantations were used to test the involvement of ST2+ macrophages in BBB integrity. Macrophages were cocultured in transwells with brain endothelial cells (ECs) after oxygen-glucose deprivation (OGD) to test potential direct effects of IL33-treated macrophages on the BBB in vitro.ResultsThe ST2 receptor was expressed in brain ECs, microglia, and infiltrating macrophages. Global KO of ST2 led to more IgG extravasation and loss of ZO-1 in cerebral microvessels 3 days post-tMCAO. Intranasal IL-33 administration reduced BBB leakage and infarct severity in microglia/macrophage competent mice, but not in microglia/macrophage depleted mice. Worse BBB injury was observed after tMCAO in chimeric WT mice reconstituted with ST2 KO bone marrow, and in WT mice whose monocytes were replaced by ST2 KO monocytes. Macrophages treated with IL-33 reduced in vitro barrier leakage and maintained tight junction integrity after OGD. In contrast, IL-33 exerted minimal direct effects on the endothelial barrier in the absence of macrophages. IL-33-treated macrophages demonstrated transcriptional upregulation of an array of protective factors, suggesting a shift towards favorable phenotypes.ConclusionOur results demonstrate that early-stage IL-33/ST2 signaling in infiltrating macrophages reduces the extent of acute BBB disruption after stroke. Intranasal IL-33 administration may represent a new strategy to reduce BBB leakage and infarct severity.

Neuroprotective effects of Daphnetin on hippocampal neurons and blood-brain barrier integrity in a mouse model of cerebral ischemia

The purpose of this research was to assess the impact of different doses of Daphnetin (DAP, a natural compound derived from coumarin) on hippocampus neuronal injury, neurobehavioral function, blood-brain barrier (BBB) integrity, expression of claudin-5, brain-derived neurotrophic factor (BDNF), superoxide dismutase (SOD), and inflammatory markers in a mouse model of cerebral ischemia. Cerebral ischemia was induced in mice through 30 minutes of bilateral common carotid occlusion (BCCAO), followed by 48 hours of reperfusion. The viability of hippocampal neurons was assessed using Cresyl violet staining and BBB function was determined by measuring Evans blue (E.B) dye leakage. Spatial memory was tested using the Radial Arm Water Maze (RAWM) task. Claudin-5 and BDNF were measured by immunofluorescence, while SOD, interleukin-1 beta (IL-1β), and nuclear factor-κB (NF-κB) expression were determined through western blotting. Administering DAP significantly increased neuron survival in the hippocampus CA1, CA3, and dentate gyrus (DG) regions and improved spatial memory dose-dependently (P<0.0001). Treatment with DAP (40 mg/kg IP) significantly reduced E.B leakage and brain water content (P<0.001). Furthermore, it increased the claudin-5, BDNF, and SOD levels and diminished NF-κB and IL-1β expression (P<0.0001). The research found that DAP protected neurons in the CA1, CA3, and DG areas of the hippocampus, enhanced behavioral functions, and preserved BBB integrity in a cerebral ischemia model. This positive impact is achieved by increasing the expression of claudin-5, BDNF, and SOD and diminishing neuroinflammation. Further research is required to clarify the mechanisms and possible clinical uses.

Exploring the effects of moxibustion on cognitive function in rats with multiple cerebral infarctions from the perspective of glial vascular unit repairing.

This study aimed to explore the effect of moxibustion at Governor Vessel (GV) acupoints, including Baihui (GV 20), Shenting (GV 24) and Dazhui (GV 14) for 14days on glial vascular unit (GVU) in rats with multiple microinfarctions (MMI), and to explore its action mechanism. The effect and mechanism of moxibustion on vascular dementia (VD) were studied in MMI rats by means of behavioral and molecular biology experiments. Rats receiving MMI showed impairment of memory function, reduction of cerebral blood flow, damage of blood-brain barrier (BBB) integrity and increased brain mass. MMI also increased neuronal degeneration in the hippocampus. Notably, levels of glial fibrillary acidic protein (GFAP) and complement component 3 significantly increased, but those of Connexin43 (CX43) and platelet derived growth factor receptor β (PDGFRβ) significantly decreased in the hippocampus of the rats receiving MMI. Moxibustion, as well as oxiracetam (ORC) treatment improved memory function and neuronal degeneration, ameliorated BBB integrity, increased cerebral blood flow and decreased brain mass. In addition, moxibustion as well as oxiracetam (ORC) treatment reduced the decrease of CX43 protein and increased PDGFRβ protein level in the hippocampus of MMI rats. Moreover, moxibustion treatment reversed MMI-induced increase of the GFAP/CX43 ratio in vascular structural units. Importantly, after PDGFRβ inhibition, VD rats treated with moxibustion had impaired learning and memory, decreased cerebral blood flow, and BBB disruption. Moxibustion treatment at various GV acupoints improved cerebral blood flow and repaired BBB function in rats with MMI, likely through protecting GVU.

New Evidence for the Role of the Blood-Brain Barrier and Inflammation in Stress-Associated Depression: A Gene-Environment Analysis Covering 19,296 Genes in 109,360 Humans.

Mounting evidence supports the key role of the disrupted integrity of the blood-brain barrier (BBB) in stress- and inflammation-associated depression. We assumed that variations in genes regulating the expression and coding proteins constructing and maintaining this barrier, along with those involved in inflammation, have a predisposing or protecting role in the development of depressive symptoms after experiencing severe stress. To prove this, genome-by-environment (GxE) interaction analyses were conducted on 6.26 M SNPS covering 19,296 genes on PHQ9 depression in interaction with adult traumatic events scores in the UK Biobank (n = 109,360) in a hypothesis-free setup. Among the 63 genes that were significant in stress-connected depression, 17 were associated with BBB, 23 with inflammatory processes, and 4 with neuroticism. Compared to all genes, the enrichment of significant BBB-associated hits was 3.82, and those of inflammation-associated hits were 1.59. Besides some sex differences, CSMD1 and PTPRD, encoding proteins taking part in BBB integrity, were the most significant hits in both males and females. In conclusion, the identified risk genes and their encoded proteins could provide biomarkers or new drug targets to promote BBB integrity and thus prevent or decrease stress- and inflammation-associated depressive symptoms, and possibly infection, e.g., COVID-19-associated mental and neurological symptoms.

Compromised endothelial Wnt/β-catenin signaling mediates the blood-brain barrier disruption and leads to neuroinflammation in endotoxemia.

The blood-brain barrier (BBB) is a critical interface that maintains the central nervous system homeostasis by controlling the exchange of substances between the blood and the brain. Disruption of the BBB plays a vital role in the development of neuroinflammation and neurological dysfunction in sepsis, but the mechanisms by which the BBB becomes disrupted during sepsis are not well understood. Here, we induced endotoxemia, a major type of sepsis, in mice by intraperitoneal injection of lipopolysaccharide (LPS). LPS acutely increased BBB permeability, activated microglia, and heightened inflammatory responses in brain endothelium and parenchyma. Concurrently, LPS or proinflammatory cytokines activated the NF-κB pathway, inhibiting Wnt/β-catenin signaling in brain endothelial cells in vitro and in vivo. Cell culture study revealed that NF-κB p65 directly interacted with β-catenin to suppress Wnt/β-catenin signaling. Pharmacological NF-κB pathway inhibition restored brain endothelial Wnt/β-catenin signaling activity and mitigated BBB disruption and neuroinflammation in septic mice. Furthermore, genetic or pharmacological activation of brain endothelial Wnt/β-catenin signaling substantially alleviated LPS-induced BBB leakage and neuroinflammation, while endothelial conditional ablation of the Wnt7a/7b co-receptor Gpr124 exacerbated the BBB leakage caused by LPS. Mechanistically, Wnt/β-catenin signaling activation rectified the reduced expression levels of tight junction protein ZO-1 and transcytosis suppressor Mfsd2a in brain endothelial cells of mice with endotoxemia, inhibiting both paracellular and transcellular permeability of the BBB. Our findings demonstrate that endotoxemia-associated systemic inflammation decreases endothelial Wnt/β-catenin signaling through activating NF-κB pathway, resulting in acute BBB disruption and neuroinflammation. Targeting the endothelial Wnt/β-catenin signaling may offer a promising therapeutic strategy for preserving BBB integrity and treating neurological dysfunction in sepsis.

Enhancing Blood-Brain Barrier Integrity in Patients With Acute Ischemic Stroke Via Normobaric Hyperoxia.

Recent advancements in animal studies have demonstrated the potential of normobaric hyperoxia (NBO) as a promising intervention for preserving the integrity of the blood-brain barrier (BBB). However, there is still limited understanding of the effects of NBO on BBB function in patients with clinical stroke. Therefore, the objective of this study was to investigate the efficacy of NBO therapy in attenuating BBB damage and reducing brain injury in individuals undergoing endovascular treatment (EVT) for acute stroke. This study enrolled patients from the OPENS-1 (Normobaric Hyperoxia Combined With Reperfusion for Acute Ischemic Stroke) study, with 43 patients receiving NBO combined with EVT and 43 patients receiving EVT alone. The main outcome measures included serum levels of occludin, MMP-9 (matrix metalloproteinase-9), NSE (neuron-specific enolase), and S100b at 24 hours and 7 days, as well as the intracranial extravasation rate at 24 hours. Serum markers were assessed using ELISA, and intracranial contrast extravasation was visualized using dual-energy computed tomography scan. We analyzed a total of 86 patients and found that the 24-hour serum markers levels of BBB damage and brain injury were significantly lower in the group receiving NBO therapy combined with EVT compared with the group receiving EVT alone. Similarly, at 7 days, the levels of occludin, MMP-9, and NSE were lower in the NBO+EVT group. We also found that the 24-hour serum levels of occludin and MMP-9 were correlated with intracranial contrast extravasation. Additionally, the incidence of intracranial contrast extravasation was lower in the NBO+EVT group compared with the EVT group (35.9% versus 60.5%, P=0.031). This study offers valuable insights into the positive impact of NBO on maintaining BBB integrity and reducing brain injury in patients with acute stroke undergoing EVT.

A DISEASE-BASED PERSPECTIVE OF THE RELATIONSHIP BETWEEN NEUROINFLAMMATION AND IMPAIRED GLUCOSE METABOLISM

Neuroinflammation is a significant contributor to the pathogenesis of several central nervous system disorders including Alzheimer's Disease, Parkinson's Disease, Huntington's Disease, and amyotrophic lateral sclerosis. Neuroinflammation is the immune response of the central nervous system against central or peripheral abnormalities disturbed by foreign agents, molecules, metabolic activities, or various diseases. Astrocytes and microglia activation are the main activators of neuroinflammation. The polarization changes of these defender cells have some key roles in bodily metabolism as much as neuronal behavior. The blood-brain barrier is known as the first defender of brain parenchyma. Neuroinflammation disrupts blood-brain barrier integrity and may cause blood-brain barrier breakdown. Glucose is the main energy source of brain and glucose uptake is achieved through the blood-brain barrier. Altered glucose metabolism may have detrimental effects on brain functions and may cause brain disorders. Also, it has been suggested that neuroinflammation may have crucial roles in glucose metabolism. The distribution of the blood-brain barrier in vascular endothelial cells of neurons, astrocytes, and microglia contributes to the transport of glucose to the cells of brain. Microglia and astrocyte polarization are suggested as the two main underlying mechanisms in neuroinflammation. It’s obviously determined that neuroinflammation-caused neurodegenerative diseases are tightly linked with the brain insulin resistance and disrupted cerebral and peripheral glucose metabolism. However, there is lacking knowledge about glucose metabolism deficiencies and microglia/astrocyte polarization. Herein this review, we summarized the neuroinflammation and glucose metabolism with the most common neurological diseases and the possible effects of microglia/astrocyte polarization on glucose metabolism.

Reactive Oxygen Species-Responsive Chitosan-Bilirubin Nanoparticles Loaded with Statin for Treatment of Cerebral Ischemia.

Cerebral ischemia impairs blood circulation, leading to elevated reactive oxygen species (ROS) production. A ROS-responsive delivery of drugs can enhance the therapeutic efficacy and minimize the side effects. There is insufficient evidence on the impact of ROS-responsive nanoparticles on ischemic stroke. We developed ROS-responsive chitosan-bilirubin (ChiBil) nanoparticles to target acute ischemic lesions and investigated the effect of atorvastatin-loaded ROS-responsive ChiBil. We randomly assigned rats with transient middle cerebral artery occlusion (MCAO) to 4 groups: saline, Statin, ChiBil, and ChiBil-Statin. These groups were treated daily via the tail vein for 7 d. Behavioral assessment, magnetic resonance (MR) imaging, evaluation of neuroinflammation, blood-brain barrier (BBB) integrity, apoptosis, and neurogenesis after stroke were conducted. Invitro, results showed nanoparticle uptake and reduced intracellular ROS, lipid peroxidation, and inflammatory cytokines (IL-6 and TNF-α). Invivo, results showed improved motor deficits and decreased infarct volumes on MR images in the ChiBil-Statin group compared with the Control group on day 7 (P < 0.05). Furthermore, the expression of inflammatory cytokines such as IL-1β and IL-6 was reduced in the ChiBil-Statin group compared with the Control group (P < 0.05). Improvements in BBB integrity, apoptosis, and neurogenesis were observed in the ChiBil-Statin group. The findings demonstrated that intravenous ROS-responsive multifunctional ChiBil-Statin could effectively deliver drugs to the ischemic brain, exerting marked synergistic pleiotropic neuroprotective effects. Therefore, ChiBil-Statin holds promise as a targeted therapy for ischemic vascular diseases characterized by increased ROS production, leading to new avenues for future research and potential clinical applications.

RiboTag RNA Sequencing Identifies Local Translation of HSP70 In Astrocyte Endfeet After Cerebral Ischemia.

Brain ischemia causes disruption in cerebral blood flow and blood-brain barrier (BBB) integrity which are normally maintained by the astrocyte endfeet. Emerging evidence points to dysregulation of the astrocyte translatome during ischemia, but its effects on the endfoot translatome are unknown. In this study, we aimed to investigate the early effects of ischemia on the astrocyte endfoot translatome in a rodent model of cerebral ischemia-reperfusion. To do so, we immunoprecipitated astrocyte-specific tagged ribosomes (RiboTag IP) from mechanically isolated brain microvessels. In mice subjected to middle cerebral artery occlusion and reperfusion and contralateral controls, we sequenced ribosome-bound RNAs from perivascular astrocyte endfeet and identified 205 genes that were differentially expressed in the translatome after ischemia. Pathways associated with the differential expressions included proteostasis, inflammation, cell cycle, and metabolism. Transcription factors whose targets were enriched amongst upregulated translating genes included HSF1, the master regulator of the heat shock response. The most highly upregulated genes in the translatome were HSF1-dependent Hspa1a and Hspa1b , which encode the inducible HSP70. We found that HSP70 is upregulated in astrocyte endfeet after ischemia, coinciding with an increase in ubiquitination across the proteome. These findings suggest a robust proteostasis response to proteotoxic stress in the endfoot translatome after ischemia. Modulating proteostasis in endfeet may be a strategy to preserve endfeet function and BBB integrity after ischemic stroke.