Systemic inflammatory challenges compromise survival after experimental stroke via augmenting brain inflammation, blood- brain barrier damage and brain oedema independently of infarct size

Dysbiosis and fecal microbiota transplant: Contemplating progress in health, neurodegeneration and longevity

The gut-brain axis plays an important role in mental health. The intestinal epithelial surface is colonized by billions of commensal and transitory bacteria, known as the Gut Microbiota (GM). However, potential pathogens continuously stimulate intestinal immunity when they find the place. The last two decades have witnessed several studies revealing intestinal bacteria as a key factor in the health-disease balance of the gut, as well as disease-emergent in other parts of the body. Various neurological processes, such as cognition, learning, and memory, could be affected by dysbiosis in GM. Additionally, the aging process and longevity are related to systemic inflammation caused by dysbiosis. Commensal GM affects brain development, behavior, and healthy aging suggesting that building changes in GM might be a potential therapeutic method. The innovation in GM dysbiosis is intervention by Fecal Microbiota Transplantation (FMT), which has been confirmed as a therapy for recurrent Clostridium difficile infections and is promising for other clinical disorders, such as Parkinson's disease, Multiple Sclerosis (MS), Alzheimer's disease, and depression. Additionally, FMT may be possible to promote healthy aging, and extend longevity. This review aims to connect dysbiosis, neurological disorders, and aging and the potential of FMT as a therapeutic strategy to treat these disorders, and to enhance the quality of life in the elderly.

Associations of long-term exposure to low-level PM2.5 and brain disorders in 260,922 middle-aged and older adults

Long-term exposure to high-level ambient PM2.5 was associated with increased risks of brain disorders, while the associations remain uncertain when the exposure is lower than current air quality standards in numerous countries. This study aimed to assess the effects of PM2.5 exposure on the brain system in the population with annual mean concentrations ≤15 μg/m3. We analyzed data from 260,922 participants without preexisting brain diseases at baseline in the UK Biobank. The geographical distribution of PM2.5 in 2010 was estimated by a land use regression model and linked with individual residential address. We investigated associations of ambient PM2.5 with incident neurological (dementia, Parkinson's diseases [PD], epilepsy, and migraine) and psychiatric (major depressive disorder [MDD] and anxiety disorder) diseases through Cox proportional hazard models. We further estimated the links with brain imaging phenotypes by neuroimaging analysis. Results showed that in the population with PM2.5 concentrations ≤15 μg/m3, each interquartile range (IQR, 1.28 μg/m3) increment in PM2.5 was related to incidence risks of dementia, epilepsy, migraine, MDD, and anxiety disorder with hazard ratios of 1.08 (95% confidence interval [CI]: 1.03, 1.13), 1.12 (1.05, 1.20), 1.07 (1.00, 1.13), 1.06 (1.03, 1.09), and 1.05 (1.02, 1.08), respectively. We did not observe a significant association with PD. The association with dementia was stronger among the population with poor cardiovascular health (measured by Life's Essential 8) than the counterpart (P for interaction = 0.037). Likewise, per IQR increase was associated with specific brain imaging phenotypes, including volumes of total brain (β = -0.036; 95% CI: -0.050, -0.022), white matter (-0.030; -0.046, -0.014), grey matter (-0.030; -0.042, -0.017), respectively. The findings suggest long-term exposure to ambient PM2.5 at low-level still has an adverse impact on the neuro-psychiatric systems. The brain-relevant epidemiological assessment suggests that each country should update the standard for ambient PM2.5 following the World Health Organization Air Quality Guidelines 2021.

Microglial Inflammatory Mechanisms in Stroke: The Jury Is Still Out

Microglia represent the main immune cell population in the CNS with unique homeostatic roles and contribution to broad neurological conditions. Stroke is associated with marked changes in microglial phenotypes and induction of inflammatory responses, which emerge as key modulators of brain injury, neurological outcome and regeneration. However, due to the limited availability of functional studies with selective targeting of microglia and microglia-related inflammatory pathways in stroke, the vast majority of observations remain correlative and controversial. Because extensive review articles discussing the role of inflammatory mechanisms in different forms of acute brain injury are available, here we focus on some specific pathways that appear to be important for stroke pathophysiology with assumed contribution by microglia. While the growing toolkit for microglia manipulation increasingly allows targeting inflammatory pathways in a cell-specific manner, reconsideration of some effects devoted to microglia may also be required. This may particularly concern the interpretation of inflammatory mechanisms that emerge in response to stroke as a form of sterile injury and change markedly in chronic inflammation and common stroke comorbidities.

Data-Driven Analysis Reveals Cortical Infarction Patterns Correlated With Inflammation and Prognosis: A Retrospective, Multicenter Cohort Study

BACKGROUND

We aim to identify the distinct lesion patterns and regions associated with functional outcome and inflammation in patients with acute ischemic stroke, and investigate whether the association between lesion patterns and functional outcome was mediated by inflammation.

METHODS AND RESULTS

We performed nonnegative matrix factorization to derived low-dimensional lesion patterns (atoms), and Bayesian linear regression models were applied to explore the associations of lesion patterns with inflammatory factors including high-sensitivity C-reactive protein and interleukin-6, as well as functional outcome (defined as modified Rankin Scale score at 3 months). The difference distribution mean and 95% highest probability density interval (HPDI) were calculated. Mediation analysis was used to examine the mediating effects of inflammation on the relationships between lesion patterns and functional outcome. Seven lesion patterns were derived from 5914 patients with acute ischemic stroke. Lesion patterns distributed in the cortical regions were associated with inflammatory response, including atom 1 (interleukin-6: mean, 0.113 [95% HPDI, 0.073-0.162]; high-sensitivity C-reactive protein: mean, 0.082 [95% HPDI, 0.038-0.123]) and atom 4 (interleukin-6: mean, 0.113 [95% HPDI, 0.071-0.167]; high-sensitivity C-reactive protein: mean, 0.108 [95% HPDI, 0.058-0.165]). These lesion patterns were also significantly associated with functional outcome (atom 1: mean, 1.958 [95% HPDI, 1.538-2.383]; atom 4: mean, 2.245 [95% HPDI, 1.773-2.741]). Mediation analysis suggested that interleukin-6 explained 15.34% and 7.47% in the association of atom 1 and atom 4 with functional outcome, respectively.

CONCLUSIONS

Certain lesion patterns that are associated with both inflammation and functional outcome of acute ischemic stroke, especially cortical infarction, may play a role in functional outcome through modulating inflammatory reactions.

Blocking cerebral lymphatic system reduces central and peripheral inflammatory response in ischemic stroke

Reduced blood supply to the brain activates the intracranial inflammatory response, a key contributor to secondary brain damage in ischemic stroke. Post-stroke, activation of peripheral immune cells leads to systemic inflammatory responses. Usingin vivo approaches, we investigated meningeal lymphatics' role in central immune cell infiltration and peripheral immune cell activation. The bilateral deep cervical lymph nodes (dCLNs) were removed 7 days before right middle cerebral artery occlusion in Sprague Dawley (SD) rats. At 3, 24, and 72 h post-intervention, brain immune cell infiltration and microglial and astrocyte activation were measured, while immune cells were classified in the spleen and blood. Inflammatory factor levels in peripheral blood were analyzed. Simultaneously, reverse verification was conducted by injecting AAV-vascular endothelial growth factor C (AAV-VEGFC) adenovirus into the lateral ventricle 14 days before middle cerebral artery occlusion (MCAO) induction to enhance meningeal lymph function. Blocking meningeal LVs in MCAO rats significantly reduced infarct area and infiltration, and inhibited microglia and pro-inflammatory astrocytes activation. After removing dCLNs, CD4+ T lymphocytes, CD8+ T lymphocytes, B lymphocytes, macrophages, and neutrophils in the spleen and blood of MCAO rats decreased significantly at different time points. The levels of inflammatory factors IL-6, IL-10, IL-1β, and TNF-α in plasma decreased significantly. Tests confirmed the results, and AAV-VEGFC-induced MCAO rats provided reverse validation.

Developmental stage and infection status may affect drug distribution in the prostate of rats

Prostate inflammation is often treated with drugs which are ineffective. Antibacterial agents fail to reach the prostate epithelium, and the blood-prostate barrier (BPB) may affect the drug transport process. Factors affecting drug efficacy remain unclear.Rats were categorised into groups A and B, corresponding to adulthood and puberty, respectively. Group C included the model of chronic prostate infection. Dialysates of levofloxacin and cefradine were collected from the prostate gland and jugular vein and evaluated. Pharmacokinetic analysis was conducted.The free concentrations of antimicrobials in the prostate and plasma samples of all groups peaked at 20 min, then gradually decreased. The mean AUC0-tprostate/AUC0-tplasma ratio in the levofloxacin group were 0.86, 0.53, and 0.95, and the mean values of AUC0-∞prostate/AUC0-∞plasma ratio were 0.85, 0.63, and 0.97. The corresponding values in the cefradine group were 0.67, 0.30 and 0.84, and 0.66, 0.31, and 0.85, respectively. The mean values in group B were lower than those in group A, and those in group C were higher than those in group B.The maturity of the prostate may affect the ability of the drug to cross the BPB. Infection may disrupt the BPB, affecting drug permeability.

Innovations in Breaking Barriers: Liposomes as Near-Perfect Drug Carriers in Ischemic Stroke Therapy

Liposomes, noted for their tunable particle size, surface customization, and varied drug delivery capacities, are increasingly acknowledged in therapeutic applications. These vesicles exhibit surface flexibility, enabling the incorporation of targeting moieties or peptides to achieve specific targeting and avoid lysosomal entrapment. Internally, their adaptable architecture permits the inclusion of a broad spectrum of drugs, contingent on their solubility characteristics. This study thoroughly reviews liposome fabrication, surface modifications, and drug release mechanisms post-systemic administration, with a particular emphasis on drugs crossing the blood-brain barrier (BBB) to address lesions. Additionally, the review delves into recent developments in the use of liposomes in ischemic stroke models, offering a comparative evaluation with other nanocarriers like exosomes and nano-micelles, thereby facilitating their clinical advancement.

Delayed Administration of an Angiotensin II Type 2 Receptor Agonist Promotes Functional Recovery of the Brain and Heart After Traumatic Brain Injury

Cardiac injury is a common complication following traumatic brain injury (TBI) that can lead to poor clinical outcomes. Angiotensin II type 2 receptor (AT2R) activation exerts protective roles in the brain and heart, yet its potential impact on TBI or TBI-induced cardiac deficits remains elusive. The goal of this study was to investigate the influence of AT2R activation on recovery after TBI-induced cognitive and cardiac injury using the selective nonpeptide AT2R agonist compound 21 (C21). TBI was induced by cortical impact injury in male adult C57BL/6J mice, and the mice received C21 (0.03 mg/kg, intraperitoneally) starting from 24 h after TBI and continuing once daily. C21 facilitated cognitive function recovery until 1 month after TBI. C21 alleviated blood-brain barrier leakage and brain edema and inhibited the expression of proinflammatory cytokines in the brain after 3 consecutive days of treatment. C21 improved cerebral blood flow after 1 month, although the lesion volume was not affected. C21 also reduced the expression of proinflammatory cytokines in the heart after a 3-day consecutive treatment. Meanwhile, C21 benefited cardiac function, as identified by increased left ventricular ejection fraction 1 month after TBI. In addition, C21 alleviated TBI-induced cardiac hypertrophy and fibrosis; however, blood pressure was not affected. Our results demonstrate that AT2R activation ameliorates TBI-induced neurological and cardiac deficits.

Links between oral microbiome and insulin resistance: Involvement of MAP kinase signaling pathway

Oral dysbiosis contributes to periodontitis and has implications for systemic diseases. Diabetes mellitus is a common metabolic disorder characterized by impaired glucose regulation. AMP-activated protein kinase (AMPK) plays a vital role in regulating glucose uptake and glycogenesis in the liver. This study aimed to investigate the association between periodontal bacteria and diabetes mellitus. A clinical trial was conducted to explore the association between oral bacteria and hyperglycemia. Additionally, we elucidated the molecular mechanisms by which periodontal bacteria cause insulin resistance. In the clinical trial, we discovered significant alterations in the expression levels of Fusobacterium nucleatum (Fn) and Tannerella forsythia (Tf) in patients with diabetes compared with healthy controls. Furthermore, Fn and Tf levels positively correlated with fasting blood glucose and glycated hemoglobin (HbA1C) levels. Moreover, we explored and elucidated the molecular mechanism by which Fusobacterium nucleatum culture filtrate (FNCF) induces cytokine release via the Toll-like receptor 2 (TLR2) signaling pathway in human gingival epithelial Smulow-Glickman (S-G) cells. This study investigated the effects of cytokines on insulin resistance pathways in liver cells. The use of an extracellular signal-regulated kinase (ERK) inhibitor (U0126) demonstrated that FNCF regulates the insulin receptor substrate 1 and protein kinase B (IRS1/AKT) signaling pathway, which affects key proteins involved in hepatic glycogen synthesis, including glycogen synthase kinase-3 beta (GSK3β) and glycogen synthase (GS), ultimately leading to insulin resistance. These findings suggest that ERK plays a crucial role in hepatocyte insulin resistance.

tDCS does not add effect to foot drop stimulator and gait training in improving clinical parameters and neuroplasticity biomarkers in chronic post-stroke: randomized controlled trial

BACKGROUND

Transcranial direct current stimulation (tDCS) and foot drop stimulators (FDS) are widely used for stroke rehabilitation. However, no study has investigated if tDCS could boost the effects of FDS and gait training in improving clinical parameters and neuroplasticity biomarkers of chronic post-stroke subjects.

OBJECTIVE

To investigate the effects of combining tDCS and FDS on motor impairment, functional mobility, and brain-derived neurotrophic factor (BDNF) serum levels. Also, to evaluate the effects of this protocol on the insulin-like growth factor-1 (IGF-1), insulin growth factor-binding proteins-3 (IGFBP-3), interleukin (IL) 6 and 10, and tumor necrosis factor-α (TNF-α) levels.

METHODS

Thirty-two chronic post-stroke individuals were randomized to tDCS plus FDS or sham tDCS plus FDS groups. Both groups underwent ten gait training sessions for two weeks using a FDS device and real or sham tDCS. Blood samples and clinical data were acquired before and after the intervention. Motor impairment was assessed by the Fugl-Meyer Assessment and functional mobility using the Timed up and Go test.

RESULTS

Both groups improved the motor impairment and functional mobility and increased the BDNF levels. Both groups also increased the IL-10 and decreased the cortisol, IL-6, and TNF-α levels. No difference was observed between groups.

CONCLUSION

tDCS did not add effect to FDS and gait training in improving clinical parameters and neuroplasticity biomarkers in chronic post-stroke individuals. Only FDS and gait training might be enough for people with chronic stroke to modify some clinical parameters and neuroplasticity biomarkers.

Pharmacological intervention of curcumin via the NLRP3 inflammasome in ischemic stroke

Ischemic-induced neuronal injury arises due to low oxygen/nutrient levels and an inflammatory response that exacerbates neuronal loss. NOD-like receptor family pyrin domain-containing 3 (NLRP3) is an important regulator of inflammation after ischemic stroke, with its inhibition being involved in nerve regeneration. Curcumin, a main active ingredient in Chinese herbs, plays a positive role in neuronal repair and neuroprotection by regulating the NLRP3 signaling pathway. Nevertheless, the signaling mechanisms relating to how curcumin regulates NLRP3 inflammasome in inflammation and neural restoration following ischemic stroke are unknown. In this report, we summarize the main biological functions of the NLRP3 inflammasome along with the neuroprotective effects and underlying mechanisms of curcumin via impairment of the NLRP3 pathway in ischemic brain injury. We also discuss the role of medicinal interventions that target the NLRP3 and potential pathways, as well as possible directions for curcumin therapy to penetrate the blood-brain barrier (BBB) and hinder inflammation in ischemic stroke. This report conclusively demonstrates that curcumin has neuroprotective properties that inhibit inflammation and prevent nerve cell loss, thereby delaying the progression of ischemic brain damage.

Transmission of NLRP3-IL-1β Signals in Cerebral Ischemia and Reperfusion Injury: from Microglia to Adjacent Neuron and Endothelial Cells via IL-1β/IL-1R1/TRAF6

The pyrin domain-containing protein 3 (NLRP3) inflammasome drives the profound cerebral ischemia and reperfusion injury (I/R) and mediates the secretion of IL-1β (interleukin-1β), which exerts a subsequent cascade of inflammatory injury. The NLRP3-activated-microglial manipulation in adjacent neuronal and endothelial NLRP3 activation has been confirmed in our previous studies. In the present study, we extended the cognition of how microglia mediated neuronal and endothelial NLRP3-IL-1β signaling during cerebral ischemia and reperfusion injury. In vitro, Neuro-2a and bEND3 cells were cultured alone or co-cultured with BV2 cells and oxygen-glucose deprivation/reoxygenation (OGD/R) was performed. In vivo, transient middle cerebral artery occlusion (tMCAO) rat models and lentiviral silencing targeting IL-1R1 were performed. The NLRP3 inflammasome activation was evaluated by enzyme-linked immunosorbent assay, western blotting, immunoprecipitation, immunohistochemistry, and immunofluorescence. In the co-culture system after OGD/R treatment, NLRP3 inflammasomes in neurons and endothelial cells were activated by microglial IL-1β via IL-1β/IL-1R1/TRAF6 signaling pathway, with the basal protein level of NLRP3. In addition, ruptured lysosomes engulfing ASC specks which were possibly secreted from microglia triggered the enhanced NLRP3 expression. In cortices of tMCAO rats at 24 h of reperfusion, silencing IL-1R1, mainly presented in neurons and endothelial cells, was efficient to block the subsequent inflammatory damage and leukocyte brain infiltration, leading to better neurological outcome. Neuronal and endothelial NLRP3 inflammasomes were activated by microglia in cerebral ischemia and reperfusion injury mainly via IL-1β/IL-1R1/TRAF6 signaling, which might be therapeutically targetable.

Neutrophil dynamics and inflammaging in acute ischemic stroke: A transcriptomic review

Stroke is among the leading causes of death and disability worldwide. Restoring blood flow through recanalization is currently the only acute treatment for cerebral ischemia. Unfortunately, many patients that achieve a complete recanalization fail to regain functional independence. Recent studies indicate that activation of peripheral immune cells, particularly neutrophils, may contribute to microcirculatory failure and futile recanalization. Stroke primarily affects the elderly population, and mortality after endovascular therapies is associated with advanced age. Previous analyses of differential gene expression across injury status and age identify ischemic stroke as a complex age-related disease. It also suggests robust interactions between stroke injury, aging, and inflammation on a cellular and molecular level. Understanding such interactions is crucial in developing effective protective treatments. The global stroke burden will continue to increase with a rapidly aging human population. Unfortunately, the mechanisms of age-dependent vulnerability are poorly defined. In this review, we will discuss how neutrophil-specific gene expression patterns may contribute to poor treatment responses in stroke patients. We will also discuss age-related transcriptional changes that may contribute to poor clinical outcomes and greater susceptibility to cerebrovascular diseases.

SARS-CoV-2 infection and diabetes: Pathophysiological mechanism of multi-system organ failure

Since the discovery of the coronavirus disease 2019 outbreak, a vast majority of studies have been carried out that confirmed the worst outcome of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in people with preexisting health conditions, including diabetes, obesity, hypertension, cancer, and cardiovascular diseases. Likewise, diabetes itself is one of the leading causes of global public health concerns that impose a heavy global burden on public health as well as socio-economic development. Both diabetes and SARS-CoV-2 infection have their independent ability to induce the pathogenesis and severity of multi-system organ failure, while the co-existence of these two culprits can accelerate the rate of disease progression and magnify the severity of the disease. However, the exact pathophysiology of multi-system organ failure in diabetic patients after SARS-CoV-2 infection is still obscure. This review summarized the organ-specific possible molecular mechanisms of SARS-CoV-2 and diabetes-induced pathophysiology of several diseases of multiple organs, including the lungs, heart, kidneys, brain, eyes, gastrointestinal system, and bones, and sub-sequent manifestation of multi-system organ failure.

Bradykinin/bradykinin 1 receptor promotes brain microvascular endothelial cell permeability and proinflammatory cytokine release by downregulating Wnt3a

Stroke is a life-threatening disease with limited therapeutic options. Damage to the blood-brain barrier (BBB) is the key pathological feature of ischemic stroke. This study explored the role of the bradykinin (BK)/bradykinin 1 receptor (B1R) and its mechanism of action in the BBB. Human brain microvascular endothelial cells (BMECs) were used to test for cellular responses to BK by using the Cell Counting Kit-8 assay, 5-ethynyl-2'-deoxyuridine staining, enzyme-linked immunosorbent assay, flow cytometry, immunofluorescence, cellular permeability assays, and western blotting to evaluate cell viability, cytokine production, and reactive oxygen species (ROS) levels in vitro. A BBB induced by middle cerebral artery occlusion was used to evaluate BBB injuries, and the role played by BK/B1R in ischemic/reperfusion (I/R) was explored in a rat model. Results showed that BK reduced the viability of BMECs and increased the levels of proinflammatory cytokines (interleukin 6 [IL-6], IL-18, and monocyte chemoattractant protein-1) and ROS. Additionally, cellular permeability was increased by BK treatment, and the expression of tight junction proteins (claudin-5 and occludin) was decreased. Interestingly, Wnt3a expression was inhibited by BK and exogenous Wnt3a restored the effects of BK on BMECs. In an in vivo I/R rat model, knockdown of B1R significantly decreased infarct volume and inflammation in I/R rats. Our results suggest that BK might be a key inducer of BBB injury and B1R knockdown might provide a beneficial effect by upregulating Wnt3a.

Brain injury environment critically influences the connectivity of transplanted neurons

Cell transplantation is a promising approach for the reconstruction of neuronal circuits after brain damage. Transplanted neurons integrate with remarkable specificity into circuitries of the mouse cerebral cortex affected by neuronal ablation. However, it remains unclear how neurons perform in a local environment undergoing reactive gliosis, inflammation, macrophage infiltration, and scar formation, as in traumatic brain injury (TBI). To elucidate this, we transplanted cells from the embryonic mouse cerebral cortex into TBI-injured, inflamed-only, or intact cortex of adult mice. Brain-wide quantitative monosynaptic rabies virus (RABV) tracing unraveled graft inputs from correct regions across the brain in all conditions, with pronounced quantitative differences: scarce in intact and inflamed brain versus exuberant after TBI. In the latter, the initial overshoot is followed by pruning, with only a few input neurons persisting at 3 months. Proteomic profiling identifies candidate molecules for regulation of the synaptic yield, a pivotal parameter to tailor for functional restoration of neuronal circuits.

Associations of Short-Term Exposure to Fine Particulate Matter with Neural Damage Biomarkers: A Panel Study of Healthy Retired Adults

Exposure to fine particulate matter (PM_2.5) is associated with various adverse health effects, such as respiratory and cardiovascular diseases. This study aimed to evaluate the association of PM_2.5 with neural damage biomarkers. A total of 34 healthy retirees were recruited from Xinxiang Medical University from December 2018 to April 2019. Concentrations of PM_2.5 constituents including 24 metals and nonmetallic elements and 6 ions, and 5 biomarkers of neural damage including brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), and S100 calcium-binding protein B (S100B) in serum were measured. A linear mixed-effect model was employed to estimate the association of PM_2.5 and its constituents with neural damage biomarkers. Modification effects of glutathione S-transferase theta 1 gene (GSTT1) polymorphism, sex, education, and physical activity on PM_2.5 exposure with neural damage were explored. PM_2.5 and its key constituents were significantly associated with neural damage biomarkers. A 10 μg/m³ increase in PM_2.5 concentration was associated with 2.09% (95% CI, 39.3-76.5%), 100% (95% CI, 1.73-198%), and 122% (95% CI, 20.7-222%) increments in BDNF, NfL, and PGP9.5, respectively. Several constituents such as Cu, Zn, Ni, Mn, Sn, V, Rb, Pb, Al, Be, Cs, Co, Th, U, Cl^-, and F^- were significantly associated with NfL. The estimated association of PM_2.5 with NSE in GSTT1-sufficient volunteers was significantly higher than that in GSTT1-null volunteers. Therefore, short-term PM_2.5 exposure was associated with neural damage, and GSTT1 expression levels modified the PM_2.5-induced adverse neural effects.

Laser ablation: Heating up the anti-tumor response in the intracranial compartment

Immunotherapies, such as immune checkpoint inhibition (ICI), have had limited success in treating intracranial malignancies. These failures are due partly to the restrictive blood-brain-barrier (BBB), the profound tumor-dependent induction of local and systemic immunosuppression, and immune evasion exhibited by these tumors. Therefore, novel approaches must be explored that aim to overcome these stringent barriers. LITT is an emerging treatment for brain tumors that utilizes thermal ablation to kill tumor cells. LITT provides an additional therapeutic benefit by synergizing with ICI and systemic chemotherapies to strengthen the anti-tumor immune response. This synergistic relationship involves transient disruption of the BBB and local augmentation of immune function, culminating in increased CNS drug penetrance and improved anti-tumor immunity. In this review, we will provide an overview of the challenges facing immunotherapy for brain tumors, and discuss how LITT may synergize with the endogenous anti-tumor response to improve the efficacy of ICI.

Novel Mechanisms and Therapeutic Targets for Ischemic Stroke: A Focus on Gut Microbiota

Ischemic stroke is the most common type of stroke with limited treatment options. Although the pathological mechanisms and potential therapeutic targets of ischemic stroke have been comprehensively studied, no effective therapies were translated into clinical practice. Gut microbiota is a complex and diverse dynamic metabolic ecological balance network in the body, including a large number of bacteria, archaea, and eukaryotes. The composition, quantity and distribution in gut microbiota are found to be associated with the pathogenesis of many diseases, such as individual immune abnormalities, metabolic disorders, and neurodegeneration. New insight suggests that ischemic stroke may lead to changes in the gut microbiota and the alterations of gut microbiota may determine stroke outcomes in turn. The link between gut microbiota and stroke is expected to provide new perspectives for ischemic stroke treatment. In this review, we discuss the gut microbiota alterations during ischemic stroke and gut microbiota-related stroke pathophysiology and complications. Finally, we highlight the role of the gut microbiota as a potential therapeutic target for ischemic stroke and summarize the microbiome-based treatment options that can improve the recovery of stroke patients.

Identifying Key Biomarkers and Immune Infiltration in Female Patients with Ischemic Stroke Based on Weighted Gene Co-Expression Network Analysis

Stroke is one of the leading causes of death and disability worldwide. Evidence shows that ischemic stroke (IS) accounts for nearly 80 percent of all strokes and that the etiology, risk factors, and prognosis of this disease differ by gender. Female patients may bear a greater burden than male patients. The immune system may play an important role in the pathophysiology of females with IS. Therefore, it is critical to investigate the key biomarkers and immune infiltration of female IS patients to develop effective treatment methods. Herein, we used weighted gene co-expression network analysis (WGCNA) to determine the key modules and core genes in female IS patients using the GSE22255, GSE37587, and GSE16561 datasets from the GEO database. Subsequently, we performed functional enrichment analysis and built a protein-protein interaction (PPI) network. Ten genes were selected as the true central genes for further investigation. After that, we explored the specific molecular and biological functions of these hub genes to gain a better understanding of the underlying pathogenesis of female IS patients. Moreover, the “Cell type Identification by Estimating Relative Subsets of RNA Transcripts (CIBERSORT)” was used to examine the distribution pattern of immune subtypes in female patients with IS and normal controls, revealing a new potential target for clinical treatment of the disease.

Higher total white blood cell and neutrophil counts are associated with an increased risk of fatal stroke occurrence: the Guangzhou biobank cohort study

Background

Chronic inflammatory diseases are linked to an increased risk of stroke events. The white blood cell (WBC) count is a common marker of the inflammatory response. However, it is unclear whether the WBC count, its subpopulations and their dynamic changes are related to the risk of fatal stroke in relatively healthy elderly population.

Methods

In total, 27,811 participants without a stroke history at baseline were included and followed up for a mean of 11.5 (standard deviation = 2.3) years. After review of available records, 503 stroke deaths (ischaemic 227, haemorrhagic 172 and unclassified 104) were recorded. Cox proportional hazards regression was used to assess the associations between the WBC count, its subpopulations and their dynamic changes (two-phase examination from baseline to the 1st follow-up) and the risk of fatal all stroke, fatal ischaemic stroke and fatal haemorrhagic stroke.

Results

(i) Regarding the WBC count in relation to the risk of fatal stroke, restricted cubic splines showed an atypically U-curved association between the WBC count and the risk of fatal all stroke occurrence. Compared with those in the lowest WBC count quartile (< 5.3*10^9/L), the participants with the highest WBC count (> 7.2*10^9/L) had a 53 and 67% increased risk for fatal all stroke (adjusted hazard ratio [aHR] = 1.53, 95% confidence interval (CI) 1.16–2.02, P = 0.003) and fatal haemorrhagic stroke (aHR = 1.67, 95% CI 1.10–2.67, P = 0.03), respectively; compared with those in the lowest quartile (< 3.0*10^9/L), the participants with the highest NEUT count (> 4.5*10^9/L) had a 45 and 65% increased risk for fatal all stroke (aHR = 1.45, 95% CI 1.10–1.89, P = 0.008) and fatal ischaemic stroke (aHR = 1.65, 95%CI 1.10–2.47 P = 0.02), respectively. With the additional adjustment for C-reactive protein, the same results as those for all stroke and ischaemic stroke, but not haemorrhagic stroke, were obtained for the WBC count (4 ~ 10*10^9/L) and the NEUT count (the NEUT counts in the top 1% and bottom 1% at baseline were excluded). (ii) Regarding dynamic changes in the WBC count in relation to the risk of fatal stroke, compared with the stable group (− 25% ~ 25%, dynamic changes from two phases of examination (baseline, from September 1st, 2003 to February 28th, 2008; 1st follow-up, from March 31st 2008 to December 31st 2012)), the groups with a 25% increase in the WBC count and NEUT count respectively had a 60% (aHR = 1.60, 95% CI 1.07–2.40, P = 0.02) and 45% (aHR = 1.45, 95% CI1.02–2.05, P = 0.04) increased risk of fatal all stroke occurrence.

Conclusions

The WBC count, especially the NEUT count, was associated with an increased risk of fatal all stroke occurrence. Longitudinal changes in the WBC count and NEUT count increase in excess of 25% were also associated with an increased risk of fatal all stroke occurrence in the elderly population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12883-021-02495-z.

Complications of Mechanical Thrombectomy in Acute Ischemic Stroke

Multiple randomized clinical trials have supported the use of mechanical thrombectomy (MT) as standard of care in the treatment of large vessel occlusion acute ischemic stroke. Optimal outcomes depend not only on early reperfusion therapy but also on post thrombectomy care. Early recognition of post MT complications including reperfusion hemorrhage, cerebral edema and large space occupying infarcts, and access site complications can guide early initiation of lifesaving therapies that can improve neurologic outcomes. Knowledge of common complications and their management is essential for stroke neurologists and critical care providers to ensure optimal outcomes. We present a review of the available literature evaluating the common complications in patients undergoing MT with emphasis on early recognition and management.

The blood-brain barrier in systemic infection and inflammation

The vascular blood-brain barrier is a highly regulated interface between the blood and brain. Its primary function is to protect central neurons while signaling the presence of systemic inflammation and infection to the brain to enable a protective sickness behavior response. With increasing degrees and duration of systemic inflammation, the vascular blood-brain barrier becomes more permeable to solutes, undergoes an increase in lymphocyte trafficking, and is infiltrated by innate immune cells; endothelial cell damage may occasionally occur. Perturbation of neuronal function results in the clinical features of encephalopathy. Here, the molecular and cellular anatomy of the vascular blood-brain barrier is reviewed, first in a healthy context and second in a systemic inflammatory context. Distinct from the molecular and cellular mediators of the blood-brain barrier's response to inflammation, several moderators influence the direction and magnitude at genetic, system, cellular and molecular levels. These include sex, genetic background, age, pre-existing brain pathology, systemic comorbidity, and gut dysbiosis. Further progress is required to define and measure mediators and moderators of the blood-brain barrier's response to systemic inflammation in order to explain the heterogeneity observed in animal and human studies.

Nanomedicines, an emerging therapeutic regimen for treatment of ischemic cerebral stroke: A review

Owing to its intricate pathophysiology, cerebral stroke is a serious medical condition caused by interruption or obstruction of blood supply (blockage of vasculature) to the brain tissues which results in diminished supply of essential nutrients and oxygen (hypoxia) and ultimate necrosis of neuronal tissues. A prompt risks assessment and immediate rational therapeutic plan with proficient neuroprotection play critically important role in the effective management of this neuronal emergency. Various conventional medications are being used for treatment of acute ischemic cerebral stroke but fibrinolytic agents, alone or in combination with other agents are considered the mainstay. These clot-busting agents effectively restore blood supply (reperfusion) to ischemic regions of the brain; however, their clinical significance is hampered due to various factors such as short plasma half-life, limited distribution to brain tissues due to the presence of highly efficient physiological barrier, blood brain barrier (BBB), and lacking of target-specific delivery to the ischemic brain regions. To alleviate these issues, various types of nanomedicines such as polymeric nanoparticles (NPs), liposomes, nanoemulsion, micelles and dendrimers have been designed and evaluated. The implication of these newer therapies (nanomedicines) have revolutionized the therapeutic outcomes by improving the plasma half-life, permeation across BBB, efficient distribution to ischemic cerebral tissues and neuroprotection. Furthermore, the adaptation of some diverse techniques including PEGylation, tethering of targeting ligands on the surfaces of nanomedicines, and pH responsive features have also been pondered. The implication of these emerging adaptations have shown remarkable potential in maximizing the targeting efficiency of drugs to ischemic brain tissues, simultaneous delivery of drugs and imaging agents (for early prognosis as well as monitoring of therapy), and therapeutic outcomes such as long-term neuroprotection.

Brain to periphery in acute ischemic stroke: Mechanisms and clinical significance

The social and public health burdens of ischemic stroke have been increasing worldwide. In addition to focal brain damage, acute ischemic stroke (AIS) provokes systemic abnormalities across peripheral organs. AIS profoundly alters the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and immune system, which further yield deleterious organ-specific consequences. Poststroke systemic pathological alterations in turn considerably contribute to the progression of ischemic brain injury, which accounts for the substantial impact of systemic complications on stroke outcomes. This review provides a comprehensive and updated pathophysiological model elucidating the systemic effects of AIS. To address their clinical significance and inform stroke management, we also outline the resulting systemic complications at particular stages of AIS and highlight the mechanisms. Future therapeutic strategies should attempt to integrate the treatment of primary brain lesions with interventions for secondary systemic complications, and should be tailored to patient individualized characteristics to optimize stroke outcomes.

Association between serum NLRP3 and malignant brain edema in patients with acute ischemic stroke

BACKGROUND

We aimed to explore the association of serum level of the nucleotide-binding oligomerization domain-like receptor family pyrin domain-containing 3 (NLRP3) and its related inflammatory biomarkers (hypoxia inducible factor-1α, cathepsin B, caspase-1 and matrix metalloproteinase-9) with malignant brain edema (MBE) in patients with acute ischemic stroke.

METHODS

We prospectively enrolled patients with acute ischemic stroke admitted < 24 h from onset of symptoms. Brain CT was performed on admission and blood samples were collected. Repeated brain CT/MRI was performed < 7 days of admission to identify the presence of MBE, defined as neurological deterioration with imaging signs of midline shift or compressed basal cisterns. Logistic regression analysis was performed to assess the association between inflammatory biomarkers and MBE, adjusted for age and National Institutes of Health Stroke Scale (NIHSS).

RESULTS

200 patients (69.3 ± 14.3 years; male 55 %) were included for analysis, of whom 26 patients developed MBE (median time from stroke onset to MBE 32.5 h). Compared with patients without MBE, those with MBE had higher level of serum concentration of NLRP3 (median time from onset to blood collection 3 h, 1.85 ng/ml vs. 1.11 ng/ml, P = 0.026). NLRP3 level was positively correlated with NIHSS on admission (Spearman ρ = 0.18, P = 0.01) and the association between NLRP3 and MBE was attenuated (OR 1.47, 95 % CI 0.88-2.46, P = 0.138) after adjusting for age and NIHSS. There was no significant difference in other biomarkers between MBE and non-MBE groups.

CONCLUSIONS

There was a trend of association between a higher level of serum concentration of NLRP3 and an increased risk of MBE after ischemic stroke, possibly confounded by the severity of stroke, which is worth further validation in large cohort studies.

Development of dexamethasone-loaded mixed polymeric micelles for nasal delivery

Our study aimed to formulate a novel dexamethasone (DXM)-loaded, mixed polymeric micelle-based drug delivery system, focusing on the auspicious nose-to-brain pathway, as a key delivery route to treat central nervous system (CNS) associated diseases. Polymeric micelles might be a solution to deliver drugs to the place of action compared to conventional formulations. Due to low Z-average (89.92 ± 2.7 nm), a polydispersity index of 0.216 ± 0.014 and high surface polarity (52.23%), a significant increase in water solubility (14-fold) was experienced. This increase resulted in favourable dissolution profile at nasal and axonal conditions with high in vitro permeability value (14.6×10^-6 cm/s) on polar brain (porcine) lipid extract. Modified Side-bi-side® type diffusion study confirmed rapid and efficient passive diffusion through the nasal mucosa contributed by strong mucoadhesive properties. The final formulation met all the requirements of a nasal drug delivery system with rapid onset of action, meaning DXM can reach the CNS and there it can exert its beneficial effects in pathological conditions.

LPS Primes Brain Responsiveness to High Mobility Group Box-1 Protein

High mobility group box (HMGB)1 action contributes to late phases of sepsis, but the effects of increased endogenous plasma HMGB1 levels on brain cells during inflammation are unclear. Here, we aimed to further investigate the role of HMGB1 in the brain during septic-like lipopolysaccharide-induced inflammation in rats (LPS, 10 mg/kg, i.p.). HMGB-1 mRNA expression and release were measured in the periphery/brain by RT-PCR, immunohistochemistry and ELISA. In vitro experiments with disulfide-HMGB1 in primary neuro-glial cell cultures of the area postrema (AP), a circumventricular organ with a leaky blood–brain barrier and direct access to circulating mediators like HMGB1 and LPS, were performed to determine the direct influence of HMGB1 on this pivotal brain structure for immune-to-brain communication. Indeed, HMGB1 plasma levels stayed elevated after LPS injection. Immunohistochemistry of brains and AP cultures confirmed LPS-stimulated cytoplasmatic translocation of HMGB1 indicative of local HMGB1 release. Moreover, disulfide-HMGB1 stimulation induced nuclear factor (NF)-κB activation and a significant release of interleukin-6, but not tumor necrosis factor α, into AP culture supernatants. However, only a few AP cells directly responded to HMGB1 with increased intracellular calcium concentration. Interestingly, priming with LPS induced a seven-fold higher percentage of responsive cells to HMGB1. We conclude that, as a humoral and local mediator, HMGB1 enhances brain inflammatory responses, after LPS priming, linked to sustained sepsis symptoms.

Significance of changes in the concentration of inflammatory factors in blood or cerebrospinal fluid in evaluating the severity and prognosis of spontaneous cerebral hemorrhage: A systematic review and meta-analysis

OBJECTIVE

Spontaneous intracerebral hemorrhage (SICH) often leads to severe disability, while inflammation plays an important role in SICH-induced secondary brain injury. The purpose of this study was to investigate the value of inflammatory factors as a means of evaluating the prognosis of SICH and to investigate the relationship between inflammatory factors and the severity and prognosis of SICH.

METHODS

The articles published before November 1 2020 were searched through PubMed, EMBASE, Cochrane library and web of science. Revman5.3 was used, using the inverse variance model to pool the SMD of TNF-a and interleukin concentration.

RESULTS

A total of 25 studies involving 3333 subjects were included in this paper. The concentration of TNF-α in the blood or cerebrospinal fluid of severe SICH patients was significantly higher than that of milder SICH patients or healthy population; SICH patients with high TNF-α concentration had a 1.06 times greater odds of poor outcomes than patients with low TNF-α concentration, odds ratio (OR) = 1.06[95% CI, 1.01-1.12]. The concentration of interleukin-6 (IL-6) in severe SICH patients was significantly higher than that in milder SICH patients; patients with high IL-6 concentration had a 2.61 times greater odds of poor outcomes than patients with low IL-6 concentration, OR = 2.61[95% CI, 1.79-3.80].

CONCLUSIONS

The detection of concentrations of TNF-α and IL-6 in peripheral blood may be helpful for the objective and quantitative assessment of the severity and prognosis of patients with SICH, and have certain significance for the selection of appropriate treatment options.

A systemic immune challenge to model hospital-acquired infections independently regulates immune responses after pediatric traumatic brain injury

Background

Traumatic brain injury (TBI) is a major cause of disability in young children, yet the factors contributing to poor outcomes in this population are not well understood. TBI patients are highly susceptible to nosocomial infections, which are mostly acquired within the first week of hospitalization, and such infections may modify TBI pathobiology and recovery. In this study, we hypothesized that a peripheral immune challenge such as lipopolysaccharide (LPS)—mimicking a hospital-acquired infection—would worsen outcomes after experimental pediatric TBI, by perpetuating the inflammatory immune response.

Methods

Three-week-old male mice received either a moderate controlled cortical impact or sham surgery, followed by a single LPS dose (1 mg/kg i.p.) or vehicle (0.9% saline) at 4 days post-surgery, then analysis at 5 or 8 days post-injury (i.e., 1 or 4 days post-LPS).

Results

LPS-treated mice exhibited a time-dependent reduction in general activity and social investigation, and increased anxiety, alongside substantial body weight loss, indicating transient sickness behaviors. Spleen-to-body weight ratios were also increased in LPS-treated mice, indicative of persistent activation of adaptive immunity at 4 days post-LPS. TBI + LPS mice showed an impaired trajectory of weight gain post-LPS, reflecting a synergistic effect of TBI and the LPS-induced immune challenge. Flow cytometry analysis demonstrated innate immune cell activation in blood, brain, and spleen post-LPS; however, this was not potentiated by TBI. Cytokine protein levels in serum, and gene expression levels in the brain, were altered in response to LPS but not TBI across the time course. Immunofluorescence analysis of brain sections revealed increased glia reactivity due to injury, but no additive effect of LPS was observed.

Conclusions

Together, we found that a transient, infection-like systemic challenge had widespread effects on the brain and immune system, but these were not synergistic with prior TBI in pediatric mice. These findings provide novel insight into the potential influence of a secondary immune challenge to the injured pediatric brain, with future studies needed to elucidate the chronic effects of this two-hit insult.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02114-1.

Altered CSF Albumin Quotient Links Peripheral Inflammation and Brain Damage in MS

OBJECTIVE

CNS damage can increase the susceptibility of the blood-brain barrier (BBB) to changes induced by systemic inflammation. The aim of this study is to better understand BBB permeability in patients with MS and to examine whether compromised BBB integrity in some of these patients is associated with CNS damage and systemic inflammation.

METHODS

Routine CSF measurements of 121 patients with MS were analyzed including number and type of infiltrating cells, total protein, lactate, and oligoclonal bands, as well as intrathecal production of immunoglobulins and CSF/serum quotients for albumin, immunoglobulins, and glucose. In addition, in a subcohort of these patients, we performed ex vivo immunophenotyping of CSF-infiltrating and paired circulating lymphocytes using a panel of 13 monoclonal antibodies, we quantified intrathecal neurofilament light chain (NF-L) and chitinase 3-like 1 (CHI3L1), and we performed intrathecal lipidomic analysis.

RESULTS

Patients with MS with abnormal high levels of albumin in the CSF showed a distinct CSF cell infiltrate and markers of CNS damage such as increased intrathecal levels of NF-L and CHI3L1 as well as a distinct CSF lipidomic profile. In addition, these patients showed higher numbers of circulating proinflammatory Th1 and Th1* cells compatible with systemic inflammation. Of interest, the abnormally high levels of albumin in the CSF of those patients were preserved over time.

CONCLUSIONS

Our results support the hypothesis that CNS damage may increase BBB vulnerability to systemic inflammation in a subset of patients and thus contribute to disease heterogeneity.

DAMPs and RAGE Pathophysiology at the Acute Phase of Brain Injury: An Overview

Early or primary injury due to brain aggression, such as mechanical trauma, hemorrhage or is-chemia, triggers the release of damage-associated molecular patterns (DAMPs) in the extracellular space. Some DAMPs, such as S100B, participate in the regulation of cell growth and survival but may also trigger cellular damage as their concentration increases in the extracellular space. When DAMPs bind to pattern-recognition receptors, such as the receptor of advanced glycation end-products (RAGE), they lead to non-infectious inflammation that will contribute to necrotic cell clearance but may also worsen brain injury. In this narrative review, we describe the role and ki-netics of DAMPs and RAGE at the acute phase of brain injury. We searched the MEDLINE database for “DAMPs” or “RAGE” or “S100B” and “traumatic brain injury” or “subarachnoid hemorrhage” or “stroke”. We selected original articles reporting data on acute brain injury pathophysiology, from which we describe DAMPs release and clearance upon acute brain injury, and the implication of RAGE in the development of brain injury. We will also discuss the clinical strategies that emerge from this overview in terms of biomarkers and therapeutic perspectives

Rapid gut dysbiosis induced by stroke exacerbates brain infarction in turn

OBJECTIVE

Stroke is a leading cause of death and disability worldwide. Neuroprotective approaches have failed in clinical trials, thus warranting therapeutic innovations with alternative targets. The gut microbiota is an important contributor to many risk factors for stroke. However, the bidirectional interactions between stroke and gut microbiota remain largely unknown.

DESIGN

We performed two clinical cohort studies to capture the gut dysbiosis dynamics after stroke and their relationship with stroke prognosis. Then, we used a middle cerebral artery occlusion model to explore gut dysbiosis post-stroke in mice and address the causative relationship between acute ischaemic stroke and gut dysbiosis. Finally, we tested whether aminoguanidine, superoxide dismutase and tungstate can alleviate post-stroke brain infarction by restoring gut dysbiosis.

RESULTS

Brain ischaemia rapidly induced intestinal ischaemia and produced excessive nitrate through free radical reactions, resulting in gut dysbiosis with Enterobacteriaceae expansion. Enterobacteriaceae enrichment exacerbated brain infarction by enhancing systemic inflammation and is an independent risk factor for the primary poor outcome of patients with stroke. Administering aminoguanidine or superoxide dismutase to diminish nitrate generation or administering tungstate to inhibit nitrate respiration all resulted in suppressed Enterobacteriaceae overgrowth, reduced systemic inflammation and alleviated brain infarction. These effects were gut microbiome dependent and indicated the translational value of the brain-gut axis in stroke treatment.

CONCLUSIONS

This study reveals a reciprocal relationship between stroke and gut dysbiosis. Ischaemic stroke rapidly triggers gut microbiome dysbiosis with Enterobacteriaceae overgrowth that in turn exacerbates brain infarction.

The Role of Gut Microbiota in an Ischemic Stroke

The intestinal microbiome, the largest reservoir of microorganisms in the human body, plays an important role in neurological development and aging as well as in brain disorders such as an ischemic stroke. Increasing knowledge about mediators and triggered pathways has contributed to a better understanding of the interaction between the gut-brain axis and the brain-gut axis. Intestinal bacteria produce neuroactive compounds and can modulate neuronal function, which affects behavior after an ischemic stroke. In addition, intestinal microorganisms affect host metabolism and immune status, which in turn affects the neuronal network in the ischemic brain. Here we discuss the latest results of animal and human research on two-way communication along the gut-brain axis in an ischemic stroke. Moreover, several reports have revealed the impact of an ischemic stroke on gut dysfunction and intestinal dysbiosis, highlighting the delicate play between the brain, intestines and microbiome after this acute brain injury. Despite our growing knowledge of intestinal microflora in shaping brain health, host metabolism, the immune system and disease progression, its therapeutic options in an ischemic stroke have not yet been fully utilized. This review shows the role of the gut microflora-brain axis in an ischemic stroke and assesses the potential role of intestinal microflora in the onset, progression and recovery post-stroke.

Peripheral inflammation and blood-brain barrier disruption: effects and mechanisms

The blood-brain barrier (BBB) is an important physiological barrier that separates the central nervous system (CNS) from the peripheral circulation, which contains inflammatory mediators and immune cells. The BBB regulates cellular and molecular exchange between the blood vessels and brain parenchyma. Normal functioning of the BBB is crucial for the homeostasis and proper function of the brain. It has been demonstrated that peripheral inflammation can disrupt the BBB by various pathways, resulting in different CNS diseases. Recently, clinical research also showed CNS complications following SARS-CoV-2 infection and chimeric antigen receptor (CAR)-T cell therapy, which both lead to a cytokine storm in the circulation. Therefore, elucidation of the mechanisms underlying the BBB disruption induced by peripheral inflammation will provide an important basis for protecting the CNS in the context of exacerbated peripheral inflammatory diseases. In the present review, we first summarize the physiological properties of the BBB that makes the CNS an immune-privileged organ. We then discuss the relevance of peripheral inflammation-induced BBB disruption to various CNS diseases. Finally, we elaborate various factors and mechanisms of peripheral inflammation that disrupt the BBB.

EDR Peptide: Possible Mechanism of Gene Expression and Protein Synthesis Regulation Involved in the Pathogenesis of Alzheimer's Disease

The EDR peptide (Glu-Asp-Arg) has been previously established to possess neuroprotective properties. It activates gene expression and synthesis of proteins, involved in maintaining the neuronal functional activity, and reduces the intensity of their apoptosis in in vitro and in vivo studies. The EDR peptide interferes with the elimination of dendritic spines in neuronal cultures obtained from mice with Alzheimer's (AD) and Huntington's diseases. The tripeptide promotes the activation of the antioxidant enzyme synthesis in the culture of cerebellum neurons in rats. The EDR peptide normalizes behavioral responses in animal studies and improves memory issues in elderly patients. The purpose of this review is to analyze the molecular and genetics aspects of the EDR peptide effect on gene expression and synthesis of proteins involved in the pathogenesis of AD. The EDR peptide is assumed to enter cells and bind to histone proteins and/or ribonucleic acids. Thus, the EDR peptide can change the activity of the MAPK/ERK signaling pathway, the synthesis of proapoptotic proteins (caspase-3, p53), proteins of the antioxidant system (SOD2, GPX1), transcription factors PPARA, PPARG, serotonin, calmodulin. The abovementioned signaling pathway and proteins are the components of pathogenesis in AD. The EDR peptide can be AD.

Systemic Inflammatory Response Syndrome and Outcomes in Ischemic Patients Treated with Endovascular Treatment

Purpose

Knowledge regarding the systemic inflammatory response syndrome (SIRS) associated with emergent large vessel occlusion (ELVO) is still insufficient. We aimed to investigate the occurrence rate, predictors, and clinical outcomes of SIRS in patients with ELVO after endovascular treatment (EVT).

Patients and Methods

We retrospectively collected EVT data of patients with ELVO from July 2015 to August 2019 in our center. SIRS in the absence of infection was recorded in detail. A favorable outcome was defined as obtaining a 90-day modified Rankin Scale (mRS) score ≤2.

Results

Among the 256 patients who received EVT, 91 (35.5%) developed SIRS. The patients who developed SIRS had a reduced favorable outcome (OR 4.112 [95% CI 1.705 to 9.920]; p=0.002) and higher mortality (OR 25.336 [95% CI 8.578 to 74.835]; p<0.001) at 90 days. A greater SIRS burden was positively correlated with the NIHSS scores at discharge and mRS scores at 90 days (r=0.265, p=0.011; r=0.245, p=0.019). The development of SIRS was associated with neutrophilic leukocytosis, hyperglycemia, higher NIHSS scores at admission, and worse collateral circulation.

Conclusion

The patients with SIRS had higher odds of poor functional outcomes and higher mortality at 90 days in the EVT-treatment setting. The severity of the inflammatory response was positively correlated with the clinical outcomes of the patients. Clinically, SIRS was associated with neutrophilic leukocytosis, hyperglycemia, baseline stroke severity, and worse collateral circulation.

The Relationship Between Chronic Obstructive Pulmonary Disease and Cerebral Small Vessel Disease Assessed by Magnetic Resonance Imaging: A Case-Control Study from a Single Center in Beijing, China

Background

Chronic obstructive pulmonary disease (COPD) and cerebral small vessel disease (CSVD) reportedly share similar risk factors and pathogenesis. However, the relationship between these 2 diseases is not clear. This study aimed to investigate the association between COPD and CSVD.

Material/Methods

Patients with stable COPD and matched healthy control participants were recruited for this study. Clinical characteristics were collected based on medical history, serological tests, brain magnetic resonance imaging, and pulmonary function tests. Individual CSVD imaging markers (white matter hyperintensities [WMH], enlarged perivascular space [EPVS], and brain atrophy) were assessed to determine their severity. Logistic analysis was used to test the relationship between CSVD markers and COPD.

Results

Significant differences in WMH, basal ganglia EPVS (BG-EPVS), and centrum semiovale EPVS (CSO-EPVS) were found between COPD and control groups (P<0.001). Logistic analysis showed that COPD was a risk factor for WMH (odds ratio [OR]=2.467, 95% confidence interval [95% CI]: 1.550–3.927, P<0.001), while it was a protective factor for BG-EPVS (OR=0.391, 95% CI: 0.246–0.621, P<0.001) and CSO-EPVS (OR=0.053, 95% CI: 0.021–0.138, P<0.001). Among patients in the COPD group, duration of COPD was a risk factor for WMH (P<0.001) and BG-EPVS (P=0.047, 0.013, 0.746), while there was no significant correlation between the COPD grade and the severity of WMH and BG-EPVS (P>0.05).

Conclusions

A significant correlation exists between COPD and imaging markers of CSVD, including WMH, BG-EPVS, and CSO-EPVS. In addition, the severity of WMH and BG-EPVS is positively related to the duration of COPD, suggesting that COPD may be a risk factor for CSVD.

A Rapid Shift from Chronic Hyperoxia to Normoxia Induces Systemic Anaphylaxis via Transient Receptor Potential Ankyrin 1 Channels on Mast Cells

Extensive activation of mast cells is the major switch that triggers systemic anaphylaxis, resulting in the subsequent release of anaphylactic mediators into circulation. We previously demonstrated that rapid changes in oxygen tension lead to mast cell degranulation, and the released tryptase triggers retinal angiogenesis in a murine oxygen-induced retinopathy model. However, whether a rapid shift from hyperoxia to normoxia (relative hypoxic stress) is a risk factor for systemic anaphylaxis remains unknown. In this study, we demonstrated that the relative hypoxia stress induces systemic mast cell activation via transient receptor potential ankyrin 1 (TRPA1) channels, which immediately leads to hypothermia and increased vascular permeability in adult mice. Although mast cell-deficient or TRPA1-deficient mice did not exhibit anaphylactic symptoms following a rapid sift to normoxia, preinjection with bone marrow-derived cultured mast cells (BMCMCs) derived from wild-type TRPA1-expressing mice restored anaphylactic responses. In addition, we found that the rapid reductions in oxygen tension in a culture atmosphere triggered the degranulation of BMCMCs derived from wild-type TRPA1-expressing mice but not that of BMCMCs derived from TRPA1-deficient mice. In human LAD2 mast cells, the relative hypoxic stress led to the degranulation, which was suppressed by the addition of a TRPA1 inhibitor. Gradual reductions from hyperoxia to normoxia led to no anaphylactic symptoms. Our results demonstrated that TRPA1-triggered mast cell degranulation is a novel pathway that induces anaphylactic shock without Ag-Ab reactions. These findings introduce a potential role for oxygen in inducing mast cell-dependent anaphylaxis and highlight the need to reconsider chronic pure oxygen therapy for anoxic diseases.

Impact of Ventilator-associated Pneumonia on Cerebrospinal Fluid Inflammation During Immunosuppression After Subarachnoid Hemorrhage: A Pilot Study

INTRODUCTION

Brain injuries can cause systemic immunosuppression, which in turn can lead to infections that adversely affect the injured brain and worsen clinical outcomes. This study aimed to investigate whether systemic infection, such as ventilator-associated pneumonia (VAP), induce intracranial inflammation in patients with subarachnoid hemorrhage (SAH).

METHODS

This prospective, observational study included 16 adults with SAH treated in the neuro-intensive care unit. Three paired cerebrospinal fluid samples (obtained from an external ventricular drain) and peripheral blood samples were obtained on days 1 to 3, 4 to 5, and 6 to 7 after SAH onset. Cell counts, cell phenotypes (monocyte HLA-DR, T regulatory cells, lymphocytes, and neutrophils), and inflammatory mediator levels were monitored.

RESULTS

Six patients developed VAP in the context of systemic immunosuppression demonstrated by a reduction in monocyte HLA-DR expression, lymphopenia, increased percentages of circulating T regulatory cells, and increased proportions of immature and immunosuppressive neutrophil subsets. During VAP, there was de novo recruitment of leukocytes into the cerebrospinal fluid, preferentially neutrophils, which exacerbated intracranial inflammation.

CONCLUSIONS

VAP increased intracranial inflammatory responses in patients with SAH despite the occurrence of systemic immunosuppression. A better understanding of cell trafficking and their pleiotropic functions in brain injury is needed to define the optimal strategies for preventing infections in patients with SAH.

Stem Cell Repair of the Microvascular Damage in Stroke

Stroke is a life-threatening disease that leads to mortality, with survivors subjected to long-term disability. Microvascular damage is implicated as a key pathological feature, as well as a therapeutic target for stroke. In this review, we present evidence detailing subacute diaschisis in a focal ischemic stroke rat model with a focus on blood–brain barrier (BBB) integrity and related pathogenic processes in contralateral brain areas. Additionally, we discuss BBB competence in chronic diaschisis in a similar rat stroke model, highlighting the pathological changes in contralateral brain areas that indicate progressive morphological brain disturbances overtime after stroke onset. With diaschisis closely approximating stroke onset and progression, it stands as a treatment of interest for stroke. Indeed, the use of stem cell transplantation for the repair of microvascular damage has been investigated, demonstrating that bone marrow stem cells intravenously transplanted into rats 48 h post-stroke survive and integrate into the microvasculature. Ultrastructural analysis of transplanted stroke brains reveals that microvessels display a near-normal morphology of endothelial cells and their mitochondria. Cell-based therapeutics represent a new mechanism in BBB and microvascular repair for stroke.

Serum IgG titers to periodontal pathogens predict 3-month outcome in ischemic stroke patients

Several cohort studies have shown that periodontal disease is associated with an increased risk for stroke. However, it remains unclear whether serum antibody titers for a specific periodontal pathogen are associated with outcome after ischemic stroke, and which kinds of pathogens are associated with ischemic stroke. We examined the relationship between serum IgG titers to periodontal pathogens and outcome in ischemic stroke patients. A total of 445 patients with acute ischemic stroke (194 female [44.0%], mean age 71.9±12.3 years) were registered in this study. Serum IgG titers to 9 periodontal pathogens (Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Prevotella intermedia, Prevotella nigrescens, Fusobacterium nucleatum, Treponema denticola, Tannerella forsythensis, Campylobacter rectus, Eikenella corrodens) were evaluated using the enzyme-linked immunosorbent assay (ELISA) method. An unfavorable outcome was defined as a 3 or higher on the modified Rankin Scale. The proportion of patients with unfavorable outcome was 25.4% (113 patients). Based on multivariate logistic regression analysis, numbers of IgG antibodies positive for periodontal pathogens (odds ratio 1.20, 95% CI 1.02-1.41, p = 0.03) were independent predictors of unfavorable outcome in ischemic stroke patients.

CTRP9: An emerging potential anti-aging molecule in brain

C1q/tumor necrosis factor (TNF)-related proteins (CTRPs) particularly CTRP9, have been established to be as adiponectin (APN) highly conserved paralogs which assemble several APN regulatory functions. Recently, growing body of evidences drawn significant attention to evaluate metabolic and cardiovascular effect of CTRP9. However, the potential role of CTRP9 in brain tissue has not yet fully illustrated. Here, we aimed to uncover latest advances regarding the CTRP9 related signaling pathways and during brain aging process.

Characterization of the TNF and IL-1 systems in human brain and blood after ischemic stroke

Preclinical and clinical proof-of-concept studies have suggested the effectiveness of pharmacological modulation of inflammatory cytokines in ischemic stroke. Experimental evidence shows that targeting tumor necrosis factor (TNF) and interleukin (IL)-1 holds promise, and these cytokines are considered prime targets in the development of new stroke therapies. So far, however, information on the cellular expression of TNF and IL-1 in the human ischemic brain is sparse.We studied 14 cases of human post-mortem ischemic stroke, representing 21 specimens of infarcts aged 1 to > 8 days. We characterized glial and leukocyte reactions in the infarct/peri-infarct (I/PI) and normal-appearing tissue (NAT) and the cellular location of TNF, TNF receptor (TNFR)1 and TNFR2, IL-1α, IL-1β, and IL-1 receptor antagonist (IL-1Ra). The immunohistochemically stained tissue sections received a score reflecting the number of immunoreactive cells and the intensity of the immunoreactivity (IR) in individual cells where 0 = no immunoreactive cells, 1 = many intermediately to strongly immunoreactive cells, and 2 = numerous and intensively immunoreactive cells. Additionally, we measured blood TNF, TNFR, and IL-1 levels in surviving ischemic stroke patients within the first 8 h and again at 72 h after symptom onset and compared levels to healthy controls.We observed IL-1α and IL-1β IR in neurons, glia, and macrophages in all specimens. IL-1Ra IR was found in glia, in addition to macrophages. TNF IR was initially found in neurons located in I/PI and NAT but increased in glia in older infarcts. TNF IR increased in macrophages in all specimens. TNFR1 IR was found in neurons and glia and macrophages, while TNFR2 was expressed only by glia in I/PI and NAT, and by macrophages in I/PI. Our results suggest that TNF and IL-1 are expressed by subsets of cells and that TNFR2 is expressed in areas with increased astrocytic reactivity. In ischemic stroke patients, we demonstrate that plasma TNFR1 and TNFR2 levels increased in the acute phase after symptom onset compared to healthy controls, whereas TNF, IL-1α, IL-1β, and IL-1Ra did not change.Our findings of increased brain cytokines and plasma TNFR1 and TNFR2 support the hypothesis that targeting post-stroke inflammation could be a promising add-on therapy in ischemic stroke patients.

Impact of Mild Hypothermia on Final Outcome of Patients with Acute Stroke: A Randomized Clinical Trial

Background and Aim Stroke is a sudden neurological disorder caused by disturbances in the brain blood flow and loss of normal brain function. Stroke is also the second leading cause of death worldwide. In the last two decades, among the various treatment options for stroke, hypothermia has shown the promise of improving the final outcome. This study aimed to investigate the effect of noninvasive hypothermia on the final outcome of patients with an acute stroke in Iran.

Methods In a randomized clinical trial, 60 Iranian patients diagnosed with acute stroke were enrolled in 2018. Patients were selected by convenience sampling method and then randomized in two groups as experimental (n = 30) and control (n = 30). Mild hypothermia was applied using a cooling device for 72 hours on the patients’ heads and intervention results were compared with the control group. Data were collected by using Acute Physiology and Chronic Health Evaluation III (APACHE III), Full Outline of Un-Responsiveness (FOUR), and National Institutes of Health Stroke Scale (NIHSS), and later analyzed by Statistical Package for the Social Sciences (SPSS) software version 22.

Results No significant difference was found in the mean scores of all three scales before and after the intervention in control group (p > 0.05) but statistically significant difference was found in the mean scores of all three scales for the intervention group (p < 0.05). The intervention group had an increased mean score in FOUR, while APACHE and NIHSS values dropped. Researchers found statistically significant difference between the mean scores after the intervention in the experimental group compared with the control group in all three scales (p < 0.05).

Conclusion The findings of this study indicate that hypothermia has a significant statistical and clinical effect on the acute stroke outcome and it can be argued that hypothermia therapy can increase the level of consciousness and reduce the risk of death in stroke patients.

Collateral augmentation treatment with a combination of acetazolamide and head-down tilt in a rat ischemic stroke model

Cerebral collaterals is crucially important in the pathophysiology of acute ischemic stroke and associated with outcome after reperfusion therapy. We explored the effectiveness of collateral augmentation treatment with a combination of acetazolamide (ACZ) and head-down tilt (HDT) in the transient middle cerebral artery occlusion (MCAO) rat model. Transient MCAO was induced in all animals for 1.5 h, followed by reperfusion for 22.5 h. Seventy-two male Wistar rats were divided into four treatment groups: control, ACZ, HDT, and combination. Twenty sham rats, which underwent surgery, were randomly allocated to these groups. Twenty-four hours after MCAO or sham surgery, we measured the infarction volume, brain edema (aquaporin-4 [AQP4], and brain water content), and neurological deficits (Garcia and Longa tests). Collateral augmentation treatments were associated with reduced infarction volume, less brain edema, and better neurological outcomes compared with untreated animals. More specifically, ACZ and HDT treatments resulted in small infarction volumes, and HDT was associated with a low AQP4 expression and improved neurological score, while the combination of ACZ and HDT improved neurological scores and reduced brain water content. This study shows that collateral augmentation treatments are associated with a better stroke prognosis compared with untreated animals after transient MCAO. The combination of ACZ and HDT seems to have some synergistic effect, but was not proven to be superior to HDT treatment alone.

Lipopolysaccharide worsens the prognosis of experimental cerebral ischemia via interferon gamma-induced protein 10 recruit in the acute stage

BACKGROUND

Infection is an important clinical complication facing stroke-patients and triples the risk of death within 30 days post-stroke via mechanisms which are poorly understood.

AIMS

We tried to explore the mechanisms that inflammation caused by infections aggravated the ischemic brain injury after middle cerebral artery occlusion (MCAO).

METHODS

We used lipopolysaccharide (LPS) as systemic inflammatory stimuli to explore the mechanisms of aggravated ischemic brain injury after Sprague-Dawley male rats subjected to MCAO. Brain damage was evaluated by cerebral blood perfusion, Longa-5 scores, infarct volume and edema degree. Systemic cytokine responses and inflammatory changes in the plasma and brain were analyzed by ELISA kit, RT² Profiler™ PCR array, and quantitative real-time PCR. The differential genes were subjected to Gene Ontology enrichment analysis and protein-protein interaction (PPI) network construction.

RESULTS

Lipopolysaccharide profoundly aggravated the brain damage after 24 h post-MCAO. At the acute stage (ischemia/reperfusion 90 min/3 h), the brain homogenate gene expression of interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), interleukin 1β (IL-1β) and Interferon gamma-induced protein 10 (IP-10) was significantly up-regulated and the contents in plasma and brain homogenate were significantly increased in MCAO and MCAO + LPS group. IP-10 was the only gene with significant difference between MCAO and MCAO + LPS group, which was also in an important position with degrees of ≥ 14 in PPI network.

CONCLUSIONS

It was possible that trace LPS aggravated the ischemic brain injury by induction of excessive IP-10 secretion in the acute stage, leading to excessive inflammatory response, which consequently increased the infarct volume and edema degree 24 h post-MCAO.

Interleukin 1 alpha administration is neuroprotective and neuro-restorative following experimental ischemic stroke

Background

Stroke remains a leading cause of death and disability worldwide despite recent treatment breakthroughs. A primary event in stroke pathogenesis is the development of a potent and deleterious local and peripheral inflammatory response regulated by the pro-inflammatory cytokine interleukin-1 (IL-1). While the role of IL-1β (main released isoform) has been well studied in stroke, the role of the IL-1α isoform remains largely unknown. With increasing utilization of intravenous tissue plasminogen activator (t-PA) or thrombectomy to pharmacologically or mechanically remove ischemic stroke causing blood clots, respectively, there is interest in pairing successful cerebrovascular recanalization with neurotherapeutic pharmacological interventions (Fraser et al., J Cereb Blood Flow Metab 37:3531–3543, 2017; Hill et al., Lancet Neurol 11:942–950, 2012; Amaro et al., Stroke 47:2874–2876, 2016).

Methods

Transient stroke was induced in mice via one of two methods. One group of mice were subjected to tandem ipsilateral common carotid artery and middle cerebral artery occlusion, while another group underwent the filament-based middle cerebral artery occlusion. We have recently developed an animal model of intra-arterial (IA) drug administration after recanalization (Maniskas et al., J Neurosci Met 240:22–27, 2015). Sub groups of the mice were treated with either saline or Il-1α, wherein the drug was administered either acutely (immediately after surgery) or subacutely (on the third day after stroke). This was followed by behavioral and histological analyses.

Results

We now show in the above-mentioned mouse stroke models (transient tandem ipsilateral common carotid artery (CCA) and middle cerebral artery occlusion (MCA) occlusion, MCA suture occlusion) that IL-1α is neuroprotective when acutely given either intravenously (IV) or IA at low sub-pathologic doses. Furthermore, while IV administration induces transient hemodynamic side effects without affecting systemic markers of inflammation, IA delivery further improves overall outcomes while eliminating these side effects. Additionally, we show that delayed/subacute IV IL-1α administration ameliorates functional deficit and promotes neurorepair.

Conclusions

Taken together, our present study suggests for the first time that IL-1α could, unexpectedly, be an effective ischemic stroke therapy with a broad therapeutic window.

Cysteinyl Leukotriene Receptor 2 is Involved in Inflammation and Neuronal Damage by Mediating Microglia M1/M2 Polarization through NF-κB Pathway

Microglia activation plays a key role in regulating inflammatory and immune reaction during cerebral ischemia and it exerts pro-inflammatory or anti-inflammatory effect depending on M₁/M₂ polarization phenotype. Cysteinyl leukotriene 2 receptor (CysLT₂R) is a potent inflammatory mediator receptor, and involved in cerebral ischemic injury, but the mechanism of CysLT₂R regulating inflammation and neuron damage remains unclear. Here, we found that LPS and CysLT₂R agonist NMLTC₄ significantly increased microglia proliferation and phagocytosis, up-regulated the mRNA expression of M₁ polarization markers (IL-1β, TNF-α, IFN-γ, CD86 and iNOS), down-regulated the expression of M₂ polarization markers (Arg-1, CD206, TGF-β, IL-10, Ym-1) and increased the release of IL-1β and TNF-α. CysLT₂R selective antagonist HAMI3379 could antagonize these effects. IL-4 significantly up-regulated the mRNA expression of M₂ polarization markers, and HAMI3379 further increased IL-4-induced up-regulation of M₂ polarization markers expression. Additionally, LPS and NMLTC₄ stimulated NF-κB p50 and p65 proteins expression, and promoted p50 transfer to the nucleus. Pre-treatment with HAMI3379 and NF-κB signaling inhibitor Bay 11-7082 could reverse the up-regulation of p50 and p65 proteins expression, and inhibited p50 transfer to the nucleus. The conditional medium of BV-2 cells contained HAMI3379 could inhibit SH-SY5Y cells apoptosis induced by LPS and NMLTC₄. These results were further confirmed in primary microglia. The findings indicate that CysLT₂R was involved in inflammation and neuronal damage by inducing the activation of microglia M1 polarization and NF-κB pathway, inhibiting microglia M1 polarization and promoting microglia polarization toward M2 phenotype which may exerts neuroprotective effects, and targeting CysLT₂R may be a new therapeutic strategy against cerebral ischemia stroke.