Matrix metalloproteinase inhibition prevents oxidative stress-associated blood-brain barrier disruption after transient focal cerebral ischemia

Quantifying blood-brain barrier permeability in patients with ischemic stroke using non-contrast MRI

Increased blood-brain barrier permeability (BBBP) after ischemic stroke predisposes patients to hemorrhagic conversion. While altered BBBP can impact patient recovery, it is not routinely assessed during the workup of acute ischemic stroke (AIS). We study the effectiveness of the non-contrast MRI sequences diffusion-prepared pseudocontinuous arterial spin labeling (DP-pCASL) and Neurite Orientation Dispersion and Density Imaging (NODDI) in assessing BBBP and correlating to tissue microstructure after ischemic insult. Twelve patients with AIS were prospectively enrolled to undergo our multimodal MR imaging, which generated the DP-pCASL-derived cerebral blood flow (CBF), arterial transit time (ATT), and water exchange rate (kw) and the NODDI-derived b0, mean diffusivity (MD), orientation dispersion index (ODI), intracellular volume fraction (ICVF), and isotropic volume fraction (ISO) parametric maps. The mean age of the patients was 70.2 ± 14.8 with an average NIHSS of 13.0 (7.3-19.8). MR imaging was performed on average at 53.7 (27.8-93.3) hours from stroke symptom onset. The water exchange rate (kw) of the infarcted area and its contralateral territory were 89.7 min-1 (66.7-121.9) and 89.9 min-1 (65.9-106.0) respectively (p = 0.887). Multivariable linear regression analysis showed that b0, ODI, ISO and mechanical thrombectomy were significant predictors of kw. DP-pCASL and NODDI are promising non-contrast sequences for the routine assessment of BBBP.

Association between elevated serum matrix metalloproteinase-2 and tumor necrosis factor-α, and clinical symptoms in male patients with treatment-resistant and chronic medicated schizophrenia

BACKGROUND

Inflammation has an important role in the pathogenesis of schizophrenia. The aim of this study was to investigate the levels of tumor necrosis factor (TNF) and matrix metalloproteinase-2 (MMP-2) in male patients with treatment-resistant schizophrenia (TRS) and chronic medicated schizophrenia (CMS), and the relationship with psychopathology.

METHODS

The study enrolled 31 TRS and 49 cm male patients, and 53 healthy controls. Serum MMP-2 and TNF-α levels were measured by the Luminex liquid suspension chip detection method. Positive and Negative Syndrome Scale (PANSS) scores were used to evaluate symptom severity and Repeatable Battery for the Assessment of Neuropsychological Status was used to assess cognitive function.

RESULTS

Serum TNF-α and MMP-2 levels differed significantly between TRS, CMS and healthy control patients (F = 4.289, P = 0.016; F = 4.682, P = 0.011, respectively). Bonferroni correction demonstrated that serum TNF-α levels were significantly elevated in CMS patients (P = 0.022) and MMP-2 levels were significantly higher in TRS patients (P = 0.014) compared to healthy controls. In TRS patients, TNF-α was negatively correlated with age (r=-0.435, P = 0.015) and age of onset (r=-0.409, P = 0.022). In CMS patients, MMP-2 and TNF-α were negatively correlated with PANSS negative and total scores, and TNF-α was negatively correlated with PANSS general psychopathology scores (all P < 0.05). MMP-2 levels were positively correlated with TNF-α levels (P < 0.05), but not with cognitive function (P > 0.05).

CONCLUSION

The results indicate the involvement of inflammation in the etiology of TRS and CMS. Further studies are warranted.

Potential of piperine for neuroprotection in sepsis-associated encephalopathy

AIMS

Sepsis-associated encephalopathy (SAE) is a common complication that increases mortality and leads to long-term cognitive impairment in sepsis survivors. However, no specific or effective therapy has been identified for this complication. Piperine is an alkaloid known for its anti-inflammatory, antioxidant, and neuroprotective properties, which are important characteristics for treatment of SAE. The objective of this study was to evaluate the neuroprotective effect of piperine on SAE in C57BL/6 mice that underwent cecum ligation and perforation surgery (CLP).

MAIN METHODS

C57BL/6 male mice were randomly assigned to groups that underwent SHAM surgery or CLP. Mice in the CLP group were treated with piperine at doses of 20 or 40 mg/kg for short- (5 days) or long-term (10 days) periods after CLP.

KEY FINDINGS

Our results revealed that untreated septic animals exhibited increased concentrations of IL-6, TNF, VEGF, MMP-9, TBARS, and NLRP3, and decreased levels of BDNF, sulfhydryl groups, and catalase in the short term. Additionally, the levels of carbonylated proteins and degenerated neuronal cells were increased at both time points. Furthermore, short-term and visuospatial memories were impaired. Piperine treatment reduced MMP-9 activity in the short term and decreased the levels of carbonylated proteins and degenerated neuronal cells in the long term. It also lowered IL-6 and TBARS levels at both time points evaluated. Moreover, piperine increased short-term catalase and long-term BDNF factor levels and improved memory at both time points.

SIGNIFICANCE

In conclusion, our data demonstrate that piperine exerts a neuroprotective effect on SAE in animals that have undergone CLP.

Renal Fibrosis and Oxidative Stress Induced by Silica Nanoparticles in Male Rats and Its Molecular Mechanisms

Background

The utilization of amorphous silica nanoparticles (SiNPs) is gaining popularity in various applications, but it poses a potential risk to human and environmental health. However, the underlying causes and mechanisms of SiNPs-induced kidney damage are still largely unknown.

Objectives

This study aimed to investigate the SiNPs-induced damage in the kidney and further explore the possible mechanisms of SiNPs-induced nephrotoxicity.

Methods

Thirty adult male rats were divided into 3 different groups. Rats in groups 2 and 3 were administered SiNPs at 2 dosage levels (25 and 100 mg/kg of body weight), while the rats in the control group received no treatment for 28 days. Reactive oxygen species (ROS), antioxidant enzyme activities (glutathione peroxidase [GPx], superoxide dismutase [SOD], and catalase [CAT]), glutathione (GSH) levels, and oxidation markers (such as lipid peroxidation [malondialdehyde (MDA)] and protein oxidation [protein carbonyl (PCO)]) were analyzed in the kidney tissue. Additionally, renal fibrogenesis was studied through histopathological examination and the expression levels of fibrotic biomarkers.

Results

The findings revealed that in vivo treatment with SiNPs significantly triggered oxidative stress in kidney tissues in a dose-dependent manner. This was characterized by increased production of ROS, elevated levels of MDA, PCO, and nitric oxide (NO), along with a significant decline in the activities of SOD, CAT, GPx, and reduced GSH. These changes were consistent with the histopathological analysis, which indicated interstitial fibrosis with mononuclear inflammatory cell aggregation, tubular degeneration, glomerulonephritis, and glomerular atrophy. The fibrosis index was confirmed using Masson's trichrome staining. Additionally, there was a significant upregulation of fibrosis-related genes, including transforming growth factor-beta 1 (TGF-β1), matrix metalloproteinases 2 and 9 (MMP-2/9), whereas the expression of tissue inhibitor of metalloproteinase 2 (TIMP2) was downregulated.

Conclusions

This study provided a new research clue for the role of ROS and deregulated TGF-β signaling pathway in SiNPs nephrotoxicity.

Superoxide-Mediated Upregulation of MMP9 Participates in BMPR2 Destabilization and Pulmonary Hypertension Development

BACKGROUND AND AIMS

we previously reported in studies on organoid-cultured bovine pulmonary arteries that pulmonary hypertension (PH) conditions of exposure to hypoxia or endothelin-1 caused a loss of a cartilage oligomeric matrix protein (COMP) stabilization of bone morphogenetic protein receptor-2 (BMPR2) function, a known key process contributing to pulmonary hypertension development. Based on subsequent findings, these conditions were associated with an extracellular superoxide-mediated increase in matrix metalloproteinase 9 (MMP-9) expression. We investigated if this contributed to PH development using mice deficient in MMP9.

RESULTS

wild-type (WT) mice exposed to Sugen/Hypoxia (SuHx) to induce PH had increased levels of MMP9 in their lungs. Hemodynamic measures from MMP9 knockout mice (MMP9 KO) indicated they had attenuated PH parameters compared to WT mice based on an ECHO assessment of pulmonary artery pressure, right ventricular systolic pressure, and Fulton index hypertrophy measurements. In vitro vascular reactivity studies showed impaired endothelium-dependent and endothelium-independent NO-associated vasodilatory responses in the pulmonary arteries of SuHx mice and decreased lung levels of COMP and BMPR2 expression. These changes were attenuated in MMP9 KO mice potentially through preserving COMP-dependent stabilization of BMPR2.

INNOVATION

this study supports a new function of superoxide in increasing MMP9 and the associated impairment of BMPR2 in promoting PH development which could be a target for future therapies.

CONCLUSION

superoxide, through promoting increases in MMP9, mediates BMPR2 depletion and its consequent control of vascular function in response to PH mediators and the SuHx mouse model of PH.

Aggressive LDL-C Lowering and the Brain: Impact on Risk for Dementia and Hemorrhagic Stroke: A Scientific Statement From the American Heart Association

The objective of this scientific statement is to evaluate contemporary evidence that either supports or refutes the conclusion that aggressive low-density lipoprotein cholesterol lowering or lipid lowering exerts toxic effects on the brain, leading to cognitive impairment or dementia or hemorrhagic stroke. The writing group used literature reviews, references to published clinical and epidemiology studies, clinical and public health guidelines, authoritative statements, and expert opinion to summarize existing evidence and to identify gaps in current knowledge. Although some retrospective, case control, and prospective longitudinal studies suggest that statins and low-density lipoprotein cholesterol lowering are associated with cognitive impairment or dementia, the preponderance of observational studies and data from randomized trials do not support this conclusion. The risk of a hemorrhagic stroke associated with statin therapy in patients without a history of cerebrovascular disease is nonsignificant, and achieving very low levels of low-density lipoprotein cholesterol does not increase that risk. Data reflecting the risk of hemorrhagic stroke with lipid-lowering treatment among patients with a history of hemorrhagic stroke are not robust and require additional focused study.

Anti-inflammatory potential of platinum nanozymes: mechanisms and perspectives

Inflammation is a complex process of the body in response to pathogen infections or dysregulated metabolism, involving the recruitment and activation of immune system components. Repeated dangerous stimuli or uncontrolled immune effector mechanisms can result in tissue injury. Reactive Oxygen Species (ROS) play key roles in physiological cell signaling as well as in the destruction of internalized pathogens. However, aberrant ROS production and release have deleterious effects on the surrounding environment, making ROS regulation a priority to reduce inflammation. Most of the current anti-inflammatory therapies rely on drugs that impair the release of pro-inflammatory mediators. Nevertheless, increasing the enzymatic activity to reduce ROS levels could be an alternative or complementary therapeutic approach to decrease inflammation. Nanozymes are nanomaterials with high catalytic activity that mimic natural enzymes, allowing biochemical reactions to take place. Such functional particles typically show different and regenerable oxidation states or catalytically reactive surfaces offering long-term activity and stability. In this scenario, platinum-based nanozymes (PtNZs) exhibit broad and efficient catalytic functionalities and can reduce inflammation mainly through ROS scavenging, e.g. by catalase and superoxide dismutase reactions. Dose-dependent biocompatibility and immune compatibility of PtNZs have been shown in different cells and tissues, both in vitro and in vivo. Size/shape/surface engineering of the nanozymes could also potentiate their efficacy to act at different sites and/or steps of the inflammation process, such as cytokine removal or specific targeting of activated leukocytes. In the present review, we analyze key inflammation triggering processes and the effects of platinum nanozymes under exemplificative inflammatory conditions. We further discuss potential platinum nanozyme design and improvements to modulate and expand their anti-inflammatory action.

Neutrophil biology in injuries and diseases of the central and peripheral nervous systems

The role of inflammation in nervous system injury and disease is attracting increased attention. Much of that research has focused on microglia in the central nervous system (CNS) and macrophages in the peripheral nervous system (PNS). Much less attention has been paid to the roles played by neutrophils. Neutrophils are part of the granulocyte subtype of myeloid cells. These cells, like macrophages, originate and differentiate in the bone marrow from which they enter the circulation. After tissue damage or infection, neutrophils are the first immune cells to infiltrate into tissues and are directed there by specific chemokines, which act on chemokine receptors on neutrophils. We have reviewed here the basic biology of these cells, including their differentiation, the types of granules they contain, the chemokines that act on them, the subpopulations of neutrophils that exist, and their functions. We also discuss tools available for identification and further study of neutrophils. We then turn to a review of what is known about the role of neutrophils in CNS and PNS diseases and injury, including stroke, Alzheimer's disease, multiple sclerosis, amyotrophic lateral sclerosis, spinal cord and traumatic brain injuries, CNS and PNS axon regeneration, and neuropathic pain. While in the past studies have focused on neutrophils deleterious effects, we will highlight new findings about their benefits. Studies on their actions should lead to identification of ways to modify neutrophil effects to improve health.

Astaxanthin: A Marine Drug That Ameliorates Cerebrovascular-Damage-Associated Alzheimer's Disease in a Zebrafish Model via the Inhibition of Matrix Metalloprotease-13

Alzheimer's disease (AD) is a major type of dementia disorder. Common cognitive changes occur as a result of cerebrovascular damage (CVD) via the disruption of matrix metalloproteinase-13 (MMP-13). In diabetic cases, the progress of vascular dementia is faster and the AD rate is higher. Patients with type 2 diabetes are known to have a higher risk of the factor for AD progression. Hence, this study is designed to investigate the role of astaxanthin (AST) in CVD-associated AD in zebrafish via the inhibition of MMP-13 activity. CVD was developed through the intraperitoneal and intracerebral injection of streptozotocin (STZ). The AST (10 and 20 mg/L), donepezil (1 mg/L), and MMP-13 inhibitor (i.e., CL-82198; 10 μM) were exposed for 21 consecutive days in CVD animals. The cognitive changes in zebrafish were evaluated through light and dark chamber tests, a color recognition test, and a T-maze test. The biomarkers of AD pathology were assessed via the estimation of the cerebral extravasation of Evans blue, tissue nitrite, amyloid beta-peptide aggregation, MMP-13 activity, and acetylcholinesterase activity. The results revealed that exposure to AST leads to ameliorative behavioral and biochemical changes. Hence, AST can be used for the management of AD due to its multi-targeted actions, including MMP-13 inhibition.

Research progress of neuroinflammation-related cells in traumatic brain injury: A review

Neuroinflammation after traumatic brain injury (TBI) is related to chronic neurodegenerative diseases and is one of the causes of acute secondary injury after TBI. Therefore, it is particularly important to clarify the role of cellular mechanisms in the neuroinflammatory response after TBI. The objective of this article is to understand the involvement of cells during the TBI inflammatory response (for instance, astrocytes, microglia, and oligodendrocytes) and shed light on the recent progress in the stimulation and interaction of granulocytes and lymphocytes, to provide a novel approach for clinical research. We searched articles in PubMed published between 1950 and 2023, using the following keywords: TBI, neuroinflammation, inflammatory cells, neuroprotection, clinical. Articles for inclusion in this paper were finalized based on their novelty, representativeness, and relevance to the main arguments of this review. We found that the neuroinflammatory response after TBI includes the activation of glial cells, the release of inflammatory mediators in the brain, and the recruitment of peripheral immune cells. These inflammatory responses not only induce secondary brain damage, but also have a role in repairing the nervous system to some extent. However, not all of the mechanisms of cell-to-cell interactions have been well studied. After TBI, clinical treatment cannot simply suppress the inflammatory response, and the inflammatory phenotype of patients' needs to be defined according to their specific conditions after injury. Clinical trials of personalized inflammation regulation therapy for specific patients should be carried out in order to improve the prognosis of patients.

The association between malnutrition status and hemorrhagic transformation in patients with acute ischemic stroke receiving intravenous thrombolysis

OBJECTIVES

We evaluated the impact of malnutrition as estimated by the controlling nutritional status (CONUT) score and prognostic nutritional index (PNI) on hemorrhagic transformation (HT) and stroke outcomes after intravenous thrombolysis (IVT).

MATERIALS AND METHODS

Using a multicenter registry database, we enrolled 808 patients with acute ischemic stroke who received IVT between August 2013 and May 2021. We defined malnutrition as a CONUT score ≥ 2 and low PNI. The primary outcome measure was the occurrence of symptomatic HT contributing to early neurologic deterioration (END-SHT) after IVT. Multivariable analysis was performed to analyze the association between CONUT score, PNI, and END-SHT after IVT.

RESULTS

The rate of END-SHT was higher with increasing CONUT scores and PNI values. In the multivariable analysis, CONUT score ≥ 5 and low PNI were significantly associated with END-SHT (odds ratio [95% confidence interval], CONUT score ≥ 5: 12.23 [2.41-62.07], p = 0.003; low PNI: 4.98 [1.76-14.09], p = 0.003). The receiver operating characteristic curve showed that both the CONUT score and PNI had good predictive ability. The cutoff values for CONUT and PNI were 5 and 42.3, respectively, for END-SHT.

CONCLUSION

Malnutrition, as denoted by a higher CONUT score and lower PNI, was associated with END-SHT. The joint application of both nutritional markers could be useful in predicting END-SHT after IVT.

Mild therapeutic hypothermia protects against inflammatory and proapoptotic processes in the rat model of cochlear implant trauma

OBJECTIVE

Mild therapeutic hypothermia (MTH) has been demonstrated to prevent residual hearing loss from surgical trauma associated with cochlear implant (CI) insertion. Here, we aimed to characterize the mechanisms of MTH-induced hearing preservation in CI in a well-established preclinical rodent model.

APPROACH

Rats were divided into four experimental conditions: MTH-treated and implanted cochleae, cochleae implanted under normothermic conditions, MTH only cochleae and un-operated cochleae (controls). Auditory brainstem responses (ABRs) were recorded at different time points (up to 84 days) to confirm long-term protection and safety of MTH locally applied to the cochlea for 20 min before and after implantation. Transcriptome sequencing profiling was performed on cochleae harvested 24 h post CI and MTH treatment to investigate the potential beneficial effects and underlying active gene expression pathways targeted by the temperature management.

RESULTS

MTH treatment preserved residual hearing up to 3 months following CI when compared to the normothermic CI group. In addition, MTH applied locally to the cochleae using our surgical approach was safe and did not affect hearing in the long-term. Results of RNA sequencing analysis highlight positive modulation of signaling pathways and gene expression associated with an activation of cellular inflammatory and immune responses against the mechanical damage caused by electrode insertion.

SIGNIFICANCE

These data suggest that multiple and possibly independent molecular pathways play a role in the protection of residual hearing provided by MTH against the trauma of cochlear implantation.

Impacts of stress hyperglycemia ratio on early neurological deterioration and functional outcome after endovascular treatment in patients with acute ischemic stroke

Background and Purpose

Hyperglycemia has been associated with unfavorable outcome of acute ischemic stroke, but this association has not been verified in patients with endovascular thrombectomy treatment. This study aimed to assess the impact of stress hyperglycemia ratio on early neurological deterioration and favorable outcome after thrombectomy in patients with acute ischemic stroke.

Methods

Stroke patients with endovascular thrombectomy in two comprehensive centers were enrolled. Early neurological deterioration was defined as ≥4 points increase of National Institutes of Health Stroke Scale (NIHSS) at 24 hours after endovascular procedure. Favorable outcome was defined as modified Rankin Scale (mRS) score of 0-2 at 90 days of stroke onset. Multivariate regression analysis was used to identify the predictors for early neurological deterioration and favorable outcome.

Results

Among the 559 enrolled, 74 (13.2%) patients developed early neurological deterioration. The predictors for early neurological deterioration were high stress hyperglycemia ratio at baseline (OR =5.77; 95% CI, 1.878-17.742; P =0.002), symptomatic intracranial hemorrhage (OR =4.90; 95% CI, 2.439-9.835; P <0.001) and high NIHSS score after 24 hours (OR =1.11; 95% CI, 1.071-1.151; P <0.001). The predictors for favorable outcome were stress hyperglycemia ratio (OR =0.196, 95% CI, 0.077-0.502; P =0.001), age (OR =0.942, 95% CI, 0.909-0.977; P =0.001), NIHSS score 24 hours after onset (OR =0.757, 95% CI =0.693-0.827; P <0.001), groin puncture to recanalization time (OR =0.987, 95% CI, 0.975-0.998; P =0.025), poor collateral status before treatment (ASITN/SIR grade 0-3, OR =62.017, 95% CI, 25.920-148.382; P <0.001), successful recanalization (mTICI 2b or 3, OR =7.415, 95% CI, 1.942-28.313; P =0.001).

Conclusion

High stress hyperglycemia ratio may be related to early neurological deterioration and decreased likelihood of favourable outcomes after endovascular thrombectomy in patients with acute ischemic stroke.

Therapeutic Benefits of Adropin in Aged Mice After Transient Ischemic Stroke via Reduction of Blood-Brain Barrier Damage

BACKGROUND

Adropin is a peptide encoded by the energy homeostasis-associated gene (Enho) that is highly expressed in the brain. Aging and stroke are associated with reduced adropin levels in the brain and plasma. We showed that treatment with synthetic adropin provides long-lasting neuroprotection in permanent ischemic stroke. However, it is unknown whether the protective effects of adropin are observed in aged animals following cerebral ischemia/reperfusion. We hypothesized that adropin provides neuroprotection in aged mice subjected to transient middle cerebral artery occlusion.

METHODS

Aged (18-24 months old) male mice were subjected to 30 minutes of middle cerebral artery occlusion followed by 48 hours or 14 days of reperfusion. Sensorimotor (weight grip test and open field) and cognitive tests (Y-maze and novel object recognition) were performed at defined time points. Infarct volume was quantified by 2,3,5-triphenyltetrazolium chloride staining at 48 hours or Cresyl violet staining at 14 days post-middle cerebral artery occlusion. Blood-brain barrier damage, tight junction proteins, and MMP-9 (matrix metalloproteinase-9) were assessed 48 hours after middle cerebral artery occlusion by ELISA and Western blots.

RESULTS

Genetic deletion of Enho significantly increased infarct volume and worsened neurological function, whereas overexpression of adropin dramatically reduced stroke volume compared to wild-type controls. Postischemic treatment with synthetic adropin peptide given at the onset of reperfusion markedly reduced infarct volume, brain edema, and significantly improved locomotor function and muscular strength at 48 hours. Delayed adropin treatment (4 hours after the stroke onset) reduced body weight loss, infarct volume, and muscular strength dysfunction, and improved long-term cognitive function. Postischemic adropin treatment significantly reduced blood-brain barrier damage. This effect was associated with reduced MMP-9 and preservation of tight junction proteins by adropin treatment.

CONCLUSIONS

These data unveil a promising neuroprotective role of adropin in the aged brain after transient ischemic stroke via reducing neurovascular damage. These findings suggest that poststroke adropin therapy is a potential strategy to minimize brain injury and improve functional recovery in ischemic stroke patients.

Oxidative Stress and Extracellular Matrix Remodeling Are Signature Pathways of Extracellular Vesicles Released upon Morphine Exposure on Human Brain Microvascular Endothelial Cells

Morphine, a commonly used antinociceptive drug in hospitals, is known to cross the blood-brain barrier (BBB) by first passing through brain endothelial cells. Despite its pain-relieving effect, morphine also has detrimental effects, such as the potential induction of redox imbalance in the brain. However, there is still insufficient evidence of these effects on the brain, particularly on the brain endothelial cells and the extracellular vesicles that they naturally release. Indeed, extracellular vesicles (EVs) are nanosized bioparticles produced by almost all cell types and are currently thought to reflect the physiological state of their parent cells. These vesicles have emerged as a promising source of biomarkers by indicating the functional or dysfunctional state of their parent cells and, thus, allowing a better understanding of the biological processes involved in an adverse state. However, there is very little information on the morphine effect on human brain microvascular endothelial cells (HBMECs), and even less on their released EVs. Therefore, the current study aimed at unraveling the detrimental mechanisms of morphine exposure (at 1, 10, 25, 50 and 100 µM) for 24 h on human brain microvascular endothelial cells as well as on their associated EVs. Isolation of EVs was carried out using an affinity-based method. Several orthogonal techniques (NTA, western blotting and proteomics analysis) were used to validate the EVs enrichment, quality and concentration. Data-independent mass spectrometry (DIA-MS)-based proteomics was applied in order to analyze the proteome modulations induced by morphine on HBMECs and EVs. We were able to quantify almost 5500 proteins in HBMECs and 1500 proteins in EVs, of which 256 and 148, respectively, were found to be differentially expressed in at least one condition. Pathway enrichment analysis revealed that the "cell adhesion and extracellular matrix remodeling" process and the "HIF1 pathway", a pathway related to oxidative stress responses, were significantly modulated upon morphine exposure in HBMECs and EVs. Altogether, the combination of proteomics and bioinformatics findings highlighted shared pathways between HBMECs exposed to morphine and their released EVs. These results put forward molecular signatures of morphine-induced toxicity in HBMECs that were also carried by EVs. Therefore, EVs could potentially be regarded as a useful tool to investigate brain endothelial cells dysfunction, and to a different extent, the BBB dysfunction in patient circulation using these "signature pathways".

Association of the stress hyperglycemia ratio and clinical outcomes in patients with stroke: A systematic review and meta-analysis

Objective

Stress hyperglycemia (SH) is common in patients with acute diseases, such as stroke and myocardial infarction. Stress hyperglycemia ratio (SHR) is calculated by glucose/glycated hemoglobin and has been widely used for evaluating SH. But whether SHR is associated with clinical outcomes in stroke patients remains unclear so far. Although many studies have shown that higher SHR means poor outcomes, there is still no absolute evidence that SHR plays a critical role in stroke patients. Hence, we performed a systematic review and meta-analysis aiming to investigate the association between SHR and clinical outcomes in stroke patients.

Methods

We performed a comprehensive literature search of the PubMed, Embase, Cochrane Library databases, Clinicaltrials.gov, and WHO-ICTRP. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), we performed our study. The Newcastle-Ottawa Scale (NOS) tool was used to examine the potential bias of included studies. The endpoints including poor outcome, mortality, neurological deficit, hemorrhagic transformation (HT), and infectious complications were statistically analyzed.

Results

Sixteen retrospective studies met the eligibility criteria, and a number of 183,588 patients were included. Our meta-analysis demonstrated a significant increase in the incidence of poor outcome, according to assessment by the modified Rankin Scale (mRS) ≥ 3 points [odds ratio (OR) 2.53, 95% confidence interval (CI) 1.99–3.22, P < 0.00001, I² = 68%], mortality (OR 1.96, 95% CI 1.58–2.44, P < 0.00001, I² = 61%), neurological deficit (OR 1.99, 95% CI 1.47–2.70, P < 0.00001, I² = 75%), hemorrhagic transformation (HT) (OR 3.70, 95% CI 2.69–5.08, P < 0.00001, I² = 0%), and infectious complications [(Pneumonia) OR 2.06, 95% CI 1.57–2.72, P < 0.00001, I² = 24%; (Urinary tract infection) OR 2.53, 95% CI 1.45–4.42, P = 0.001, I² = 57%] in stroke patients with higher SHR. However, no significant influence was observed for recanalization rate (OR 0.86, 95% CI 0.54–1.38, P = 0.53, I² = 0%).

Conclusion

With or without diabetes, no matter whether undergoing intravenous thrombolysis or mechanical thrombectomy, higher SHR significantly increased the occurrence of poor outcomes, mortality, neurological deficit, HT, and infectious complications. The recanalization rate was not statistically significant between the two groups. More attention must be paid in clinical practice to SH. Future investigation should focus on the diagnostic value of SHR and the early control of hyperglycemia. Meanwhile, whether SHR could become a novel and promising target for early intervention is worthy of attention in further research. Besides, the influence of the dynamic change of glucose-to-HbA1c ratio, namely SHR, on intracerebral hemorrhage outcomes requires further investigation in future research. Although no randomized double-blind studies have been conducted, the available massive sample studies reflect the actual situation in the clinic and assist clinical decision makers.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022345587.

Crosstalk between neuroinflammation and oxidative stress in epilepsy

The roles of both neuroinflammation and oxidative stress in the pathophysiology of epilepsy have begun to receive considerable attention in recent years. However, these concepts are predominantly studied as separate entities despite the evidence that neuroinflammatory and redox-based signaling cascades have significant crosstalk. Oxidative post-translational modifications have been demonstrated to directly influence the function of key neuroinflammatory mediators. Neuroinflammation can further be controlled on the transcriptional level as the transcriptional regulators NF-KB and nrf2 are activated by reactive oxygen species. Further, neuroinflammation can induce the increased expression and activity of NADPH oxidase, leading to a highly oxidative environment. These factors additionally influence mitochondria function and the metabolic status of neurons and glia, which are already metabolically stressed in epilepsy. Given the implication of this relationship to disease pathology, this review explores the numerous mechanisms by which neuroinflammation and oxidative stress influence one another in the context of epilepsy. We further examine the efficacy of treatments targeting oxidative stress and redox regulation in animal and human epilepsies in the literature that warrant further investigation. Treatment approaches aimed at rectifying oxidative stress and aberrant redox signaling may enable control of neuroinflammation and improve patient outcomes.

Secondary Brain Injury by Oxidative Stress After Cerebral Hemorrhage: Recent Advances

Intracerebral hemorrhage (ICH) is a clinical syndrome in which blood accumulates in the brain parenchyma because of a nontraumatic rupture of a blood vessel. Because of its high morbidity and mortality rate and the lack of effective therapy, the treatment of ICH has become a hot research topic. Meanwhile, Oxidative stress is one of the main causes of secondary brain injury(SBI) after ICH. Therefore, there is a need for an in-depth study of oxidative stress after ICH. This review will discuss the pathway and effects of oxidative stress after ICH and its relationship with inflammation and autophagy, as well as the current antioxidant therapy for ICH with a view to deriving better therapeutic tools or targets for ICH.

Impact of Stress Hyperglycemia on Early Neurological Deterioration in Acute Ischemic Stroke Patients Treated With Intravenous Thrombolysis

Background and Purpose

It has been widely reported that stress hyperglycemia contributes to poor prognosis in patients experiencing acute ischemic stroke (AIS). However, its predictive value for early neurological deterioration (END) after intravenous administration of recombinant tissue-type plasminogen activator (IV-rtPA) in AIS patients is still unclear. The aim of this study was to evaluate the impact of stress hyperglycemia on the risk of END after IV-rtPA.

Methods

A total of 798 consecutive patients treated with IV-rtPA were included in this study. The stress hyperglycemia ratio (SHR) was calculated as fasting plasma glucose level at admission (mg/dl)/glycosylated hemoglobin (HbAlc) (%). END was defined as a National Institutes of Health Stroke Scale Score (NIHSS) ≥ 4 points 24 h after IV-rtPA, and poor functional outcome at discharge was defined as a modified Rankin Scale (mRS) score of 3–6 at discharge. Patients with a prior history of diabetes or HbAlc ≥ 6.5% were considered to have diabetes mellitus. Patients were grouped according to SHR values. Multivariate logistical regression was used to evaluate the risk of END for patients within specific SHR categories.

Results

In total, 139 (17.4%) patients had END. After adjusting for confounders, the highest tertile group had higher risks of END and poor functional outcome at discharge than those of patients in the lowest tertile group (OR, 1.95; 95% CI, 1.21–3.15; p = 0.006) (OR, 1.85; 95% CI, 1.163–2.941; p = 0.009), and the predictive value of high SHR for END was also significant in patients with diabetes mellitus (OR, 3.05; 95% CI, 1.29–7.21; p = 0.011). However, a significant association of high SHR and poor functional outcome was only found in patients without diabetes (OR, 1.85; 95% CI, 1.002–3.399; p = 0.045).

Conclusion

A higher SHR predicted that patients with severe stress hyperglycemia had higher risks of END and poor functional outcome at discharge after IV-rtPA.

Angong Niuhuang Wan reduces hemorrhagic transformation and mortality in ischemic stroke rats with delayed thrombolysis: involvement of peroxynitrite-mediated MMP-9 activation

Background

Hemorrhagic transformation (HT) is a common complication of delayed tissue plasminogen activator (t-PA) treatment for ischemic stroke. Peroxynitrite plays an important role in the breakdown of blood–brain barrier (BBB) and the development of HT. We tested the hypothesis that Angong Niuhuang Wan (AGNHW), a traditional Chinese medicinal formula, could be used in conjunction with t-PA to protect the BBB, minimize HT, and improve neurological function by suppressing peroxynitrite-mediated matrix metalloproteinase-9 (MMP-9) activation.

Methods

We first performed quality control study and chemical identification of AGNHW by using UPLC. In animal experiments, male Sprague–Dawley rats were subjected to 5 h of middle cerebral artery occlusion (MCAO) followed by 19 h of reperfusion plus t-PA infusion (10 mg/kg) at 5 h of cerebral ischemia. AGNHW (257 mg/kg) was given orally at 2 h after MCAO. Hemorrhagic transformation was measured using hemorrhagic scores and hemoglobin levels in ischemic brains. Evans blue leakage was utilized to assess the severity of the blood–brain barrier (BBB) damage. The modified neurologic severity score (mNSS) test was used to assess neurological functions. Peroxynitrite and superoxide was detected by using fluorescent probes. MMP-9 activity and expression were examined by gelatin zymography and immunostaining. The antioxidant effects were also studied by using brain microvascular endothelial b.End3 cells exposed to 5 h of oxygen and glucose deprivation (OGD) plus 5 h of reoxygenation with t-PA treatment (20 µg/ml).

Results

AGNHW significantly reduced the BBB damage, brain edema, reduced hemorrhagic transformation, enhanced neurological function, and reduced mortality rate in the ischemic stroke rats with t-PA treatment. AGNHW reduced peroxynitrite and superoxide in vivo and in vitro and six active chemical compounds were identified from AGNHW with peroxynitrite scavenging activity. Furthermore, AGNHW inhibited MMP-9 activity, and preserved tight junction protein claudin-5 and collagen IV in the ischemic brains.

Conclusion

AGNHW could be a potential adjuvant therapy with t-PA to protect the BBB integrity, reduce HT, and improve therapeutic outcome in ischemic stroke treatment via inhibiting peroxynitrite-mediated MMP-9 activation.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s13020-022-00595-7.

Protective Effects of Natural Polysaccharides on Intestinal Barrier Injury: A Review

Owing to their minimal side effects and effective protection from oxidative stress, inflammation, and malignant growth, natural polysaccharides (NPs) are a potential adjuvant therapy for several diseases caused by intestinal barrier injury (IBI). More studies are accumulating on the protective effects of NPs with respect to IBI, but the underlying mechanisms remain unclear. Thus, this review aims to represent current studies that investigate the protective effects of NPs on IBI by directly maintaining intestinal epithelial barrier integrity (inhibiting oxidative stress, regulating inflammatory cytokine expression, and increasing tight junction protein expression) and indirectly regulating intestinal immunity and microbiota. Furthermore, the mechanisms underlying IBI development are briefly introduced, and the structure-activity relationships of polysaccharides with intestinal barrier protection effects are discussed. Potential developments and challenges associated with NPs exhibiting protective effects against IBI have also been highlighted to guide the application of NPs in the treatment of intestinal diseases caused by IBI.

Cerebral blood flow is associated with matrix metalloproteinase levels during the early symptomatic phase of concussion

Concussion is associated with disrupted cerebral blood flow (CBF), although there appears to be substantial inter-individual variability in CBF response. At present, the mechanisms of variable CBF response remain incompletely understood, but one potential contributor is matrix metalloproteinase (MMP) expression. In more severe forms of acquired brain injury, MMP up-regulation contributes to CBF impairments via increased blood-brain barrier permeability. A similar relationship is hypothesized for concussion, where recently concussed individuals with higher MMP levels have lower CBF. To test this hypothesis, 35 concussed athletes were assessed longitudinally at early symptomatic injury (median: 5 days post-injury) and at medical clearance (median: 24 days post-injury), along with 71 athletic controls. For all athletes, plasma MMPs were measured and arterial spin labelling was used to measure CBF. Consistent with our hypothesis, higher concentrations of MMP-2 and MMP-3 were correlated with lower global CBF. The correlations between MMPs and global CBF were also significantly diminished for concussed athletes at medical clearance and for athletic controls. These results indicate an inverse relationship between plasma MMP levels and CBF that is specific to the symptomatic phase of concussion. Analyses of regional CBF further showed that correlations with MMP levels exhibited some spatial specificity, with greatest effects in occipital, parietal and temporal lobes. These findings provide new insights into the mechanisms of post-concussion cerebrovascular dysfunction.

Thrombin Signaling Contributes to High Glucose-Induced Injury of Human Brain Microvascular Endothelial Cells

BACKGROUND

Diabetes is one of the strongest disease-related risk factors for Alzheimer's disease (AD). In diabetics, hyperglycemia-induced microvascular complications are the major cause of end-organ injury, contributing to morbidity and mortality. Microvascular pathology is also an important and early feature of AD. The cerebral microvasculature may be a point of convergence of both diseases. Several lines of evidence also implicate thrombin in AD as well as in diabetes.

OBJECTIVE

Our objective was to investigate the role of thrombin in glucose-induced brain microvascular endothelial injury.

METHODS

Cultured Human brain microvascular endothelial cells (HBMVECs) were treated with 30 mM glucose±100 nM thrombin and±250 nM Dabigatran or inhibitors of PAR1, p38MAPK, MMP2, or MMP9. Cytotoxicity and thrombin activity assays on supernatants and western blotting for protein expression in lysates were performed.

RESULTS

reatment of HBMVECs with 30 mM glucose increased thrombin activity and expression of inflammatory proteins TNFα, IL-6, and MMPs 2 and 9; this elevation was reduced by the thrombin inhibitor dabigatran. Direct treatment of brain endothelial cells with thrombin upregulated p38MAPK and CREB, and induced TNFα, IL6, MMP2, and MMP9 as well as oxidative stress proteins NOX4 and iNOS. Inhibition of thrombin, thrombin receptor PAR1 or p38MAPK decrease expression of inflammatory and oxidative stress proteins, implying that thrombin may play a central role in glucose-induced endothelial injury.

CONCLUSION

Since preventing brain endothelial injury would preserve blood-brain barrier integrity, prevent neuroinflammation, and retain intact functioning of the neurovascular unit, inhibiting thrombin, or its downstream signaling effectors, could be a therapeutic strategy for mitigating diabetes-induced dementia.

Brothers in arms: platelets and neutrophils in ischemic stroke

PURPOSE OF REVIEW

In this review, we will describe how the combined ability of platelets and neutrophils to interact with each other drives ischemic stroke brain injury.

RECENT FINDINGS

Neutrophils are one of the first cells to respond during ischemic stroke. Although animals stroke models have indicated targeting neutrophils improves outcomes, clinical trials have failed to yield successful strategies. Platelets play a critical role in recruiting neutrophils to sites of injury by acting as a bridge to the injured endothelium. After initial platelet adhesion, neutrophils can rapidly bind platelets through P-selectin and glycoprotein Ibα. In addition, recent data implicated platelet phosphatidylserine as a novel key regulator of platelet-neutrophil interactions in the setting of ischemic stroke. Inhibition of procoagulant platelets decreases circulating platelet-neutrophil aggregates and thereby reduces infarct size. Platelet binding alters neutrophil function, which contributes to the injury associated with ischemic stroke. This includes inducing the release of neutrophil extracellular traps, which are neurotoxic and pro-thrombotic, leading to impaired stroke outcomes.

SUMMARY

Platelet-neutrophil interactions significantly contribute to the pathophysiology of ischemic stroke brain injury. Better understanding the mechanisms behind their formation and the downstream consequences of their interactions will lead to improved therapies for stroke patients.

Apelin-13 attenuates injury following ischemic stroke by targeting matrix metalloproteinases (MMP), endothelin- B receptor, occludin/claudin-5 and oxidative stress

Oxidative stress, an adverse consequence of brain ischemia-reperfusion injury (IRI), activates matrix metalloproteinase enzymes which cause to destruction of extracellular matrix and tight junction proteins. Oxidative stress during stroke increases serum endothelin-1 and endothelin B receptor (ETBR) expression. Apelin-13, an endogenous peptide, is expressed in numerous tissues that regulate diverse physiological and pathological processes. This study aimed to investigate the effect of intravenous (IV) injection of apelin-13 on cerebral vasogenic edema due to brain IRI. Animals were divided into sham, ischemia, and treat groups. IRI model was induced by middle cerebral artery occlusion (MCAO) for 60 min followed by 23 h reperfusion. Apelin-13 was injected into the tail vein 5 min before reperfusion. Neurological defects were evaluated with longa test. Brain water content and BBB permeability were assessed according to cerebral dry-wet weight and brain Evans blue extraction. Malondialdehyde (MDA), superoxide dismutase (SOD), and catalase (CAT) were measured using the colorimetric method. Expression of occludin and claudin-5, matrix metalloproteinase- 2 and 9 (MMP-2 & 9) and, ETBR were evaluated using Western blot. Brain IRI was associated with BBB breakdowns and vasogenic edema. Apelin-13 significantly reduced BBB permeability and vasogenic edema. Apelin-13 significantly attenuated IRI-related oxidative stress. Apelin-13 decreased expression of mmp-2, 9 and ETBR, prevented from decrement of occludin and claudin-5 expersion, which protected BBB integrity and reduced vasogenic edema. In conclusion, our results have suggested that an IV injection of apelin-13 could somehow reduce vasogenic edema via targeting oxidative stress and ETBR expression.

Effect of genetic depletion of MMP-9 on neurological manifestations of hypertension-induced intracerebral hemorrhages in aged mice

Clinical and experimental studies show that hypertension induces intracerebral hemorrhages (ICH), including cerebral microhemorrhages in the aged brain, which contribute to the pathogenesis of vascular cognitive impairment (VCI). Previous studies showed that aging increased oxidative stress-mediated activation of matrix metalloproteinases (MMPs) that importantly contributes to the pathogenesis of ICHs. In particular, oxidative stress has been implicated in activation of MMP-9, which is known to be involved in the degradation of the extracellular matrix and cleavage of collagen IV, a key constituent of the basal membrane of cerebral vessels. To determine the role of MMP-9 activation in the genesis of ICHs, we induced hypertension in 20-month-old MMP-9 null and age-matched control mice by angiotensin II and L-NAME treatment. Contrary to our hypothesis, MMP-9 deficiency did not delay the onset or incidence of neurological consequences of hypertension-induced ICHs. Our results indicate that MMP-9 activation does not play a role in the age-related exacerbation of hypertension-induced ICH.

Development of Novel Therapeutics Targeting the Blood-Brain Barrier: From Barrier to Carrier

The blood-brain barrier (BBB) is a highly specialized neurovascular unit, initially described as an intact barrier to prevent toxins, pathogens, and potentially harmful substances from entering the brain. An intact BBB is also critical for the maintenance of normal neuronal function. In cerebral vascular diseases and neurological disorders, the BBB can be disrupted, contributing to disease progression. While restoration of BBB integrity serves as a robust biomarker of better clinical outcomes, the restrictive nature of the intact BBB presents a major hurdle for delivery of therapeutics into the brain. Recent studies show that the BBB is actively engaged in crosstalk between neuronal and the circulatory systems, which defines another important role of the BBB: as an interfacing conduit that mediates communication between two sides of the BBB. This role has been subject to extensive investigation for brain-targeted drug delivery and shows promising results. The dual roles of the BBB make it a unique target for drug development. Here, recent developments and novel strategies to target the BBB for therapeutic purposes are reviewed, from both barrier and carrier perspectives.

Neuroprotective Potential of Limonene and Limonene Containing Natural Products

Limonene is a monoterpene confined to the family of Rutaceae, showing several biological properties such as antioxidant, anti-inflammatory, anticancer, antinociceptive and gastroprotective characteristics. Recently, there is notable interest in investigating the pharmacological effects of limonene in various chronic diseases due to its mitigating effect on oxidative stress and inflammation and regulating apoptotic cell death. There are several available studies demonstrating the neuroprotective role of limonene in neurodegenerative diseases, including Alzheimer's disease, multiple sclerosis, epilepsy, anxiety, and stroke. The high abundance of limonene in nature, its safety profile, and various mechanisms of action make this monoterpene a favorable molecule to be developed as a nutraceutical for preventive purposes and as an alternative agent or adjuvant to modern therapeutic drugs in curbing the onset and progression of neurodegenerative diseases. This manuscript presents a comprehensive review of the available scientific literature discussing the pharmacological activities of limonene or plant products containing limonene which attribute to the protective and therapeutic ability in neurodegenerative disorders. This review has been compiled based on the existing published articles confined to limonene or limonene-containing natural products investigated for their neurotherapeutic or neuroprotective potential. All the articles available in English or the abstract in English were extracted from different databases that offer an access to diverse journals. These databases are PubMed, Scopus, Google Scholar, and Science Direct. Collectively, this review emphasizes the neuroprotective potential of limonene against neurodegenerative and other neuroinflammatory diseases. The available data are indicative of the nutritional use of products containing limonene and the pharmacological actions and mechanisms of limonene and may direct future preclinical and clinical studies for the development of limonene as an alternative or complementary phytomedicine. The pharmacophore can also provide a blueprint for further drug discovery using numerous drug discovery tools.

High concentration of blood cobalt is associated with the impairment of blood-brain barrier permeability

Excess heavy metals can lead to many kinds of adverse effects in human. The present study is designed to investigate whether the internal excess burden of heavy metals relate to the disturbance of the Blood-brain-barrier (BBB) and oxidative stress (OS) in subjects, and identify specific metallic constituents responsible for the disturbance. We collected the blood from recruited 122 subjects for our comparison study, 69 were living at an area near e-waste dismantling factories (exposed group), who have higher levels of heavy metals in the body; and others were in a chosen reference area (reference group), who were the general residents in city, in December 2017 in Taizhou, Zhejiang province. The analyses showed that the concentrations of altogether 4 metals, including nickel (Ni), cobalt (Co), mercury (Hg) and stannum (Sn), and the triggers of BBB disruption (Apolipoprotein E4 and matrix-metalloproteinase-9), indicators of BBB (Myelin basic protein, serotonin and dopamine) and biomarkers of OS (Malondialdehyde and 8-isoprostane) were statistically significant higher in exposed group than in reference group. Moreover, they are also significantly positively correlated with each other. Among all the metals, both Pearson correlation and multiple linear regression showed Co was positive correlated with almost all biomarkers. Considering the explicit correlation between Co and BBB permeability, we speculated that high burden of Co in blood may have a connection with neurodegenerative diseases, which propose a requirement for constructing the environmental criteria for Co and might provide a potential new hint for the intervention of dementia.

Role of P2X7 Receptors in Immune Responses During Neurodegeneration

P2X7 receptors are ion-gated channels activated by ATP. Under pathological conditions, the extensive release of ATP induces sustained P2X7 receptor activation, culminating in induction of proinflammatory pathways with inflammasome assembly and cytokine release. These inflammatory conditions, whether occurring peripherally or in the central nervous system (CNS), increase blood-brain-barrier (BBB) permeability. Besides its well-known involvement in neurodegeneration and neuroinflammation, the P2X7 receptor may induce BBB disruption and chemotaxis of peripheral immune cells to the CNS, resulting in brain parenchyma infiltration. For instance, despite common effects on cytokine release, P2X7 receptor signaling is also associated with metalloproteinase secretion and activation, as well as migration and differentiation of T lymphocytes, monocytes and dendritic cells. Here we highlight that peripheral immune cells mediate the pathogenesis of Multiple Sclerosis and Parkinson's and Alzheimer's disease, mainly through T lymphocyte, neutrophil and monocyte infiltration. We propose that P2X7 receptor activation contributes to neurodegenerative disease progression beyond its known effects on the CNS. This review discusses how P2X7 receptor activation mediates responses of peripheral immune cells within the inflamed CNS, as occurring in the aforementioned diseases.

New epigenetic players in stroke pathogenesis: From non-coding RNAs to exosomal non-coding RNAs

Non-coding RNAs (ncRNAs) have critical role in the pathophysiology as well as recovery after ischemic stroke. ncRNAs, particularly microRNAs, and the long non-coding RNAs (lncRNAs) are critical for angiogenesis and neuroprotection, and they have been suggested to be therapeutic, diagnostic and prognostic tools in cerebrovascular diseases, including stroke. Moreover, exosomes have been considered as nanocarriers capable of transferring various cargos, such as lncRNAs and miRNAs to recipient cells, with prominent inter-cellular roles in the mediation of neuro-restorative events following strokes and neural injuries. In this review, we summarize the pathogenic role of ncRNAs and exosomal ncRNAs in the stroke.

Shear Stress Rescued the Neuronal Impairment Induced by Global Cerebral Ischemia Reperfusion via Activating PECAM-1-eNOS-NO Pathway

Microvessel hypoperfusion following ischemic stress resulted in a decreased shear stress of brain microvascular endothelial cells (BMECs) and contributed to abnormal expression of PECAM-1 after global cerebral ischemia/reperfusion (I/R) injury. Here, we identified novel pathophysiologic and rehabilitative procedures specific to shear stress in microvascular endothelial cells in response to global cerebral I/R injury. We found that the decrease in cerebral blood flow of gerbils after global cerebral I/R injury reduces shear stress, and the abnormal change in shear stress leads to microvascular endothelial cell and neuron damage. Nevertheless, suitable high levels of shear stress contribute to rescuing the dysfunction and malformation of BMECs via regulating the PECAM-1-eNOS-NO pathway to enhance nitric oxide release, decrease the expression of caspase-3 to reduce apoptosis, and improve the shear-adaptability of endothelial cells, thereby playing a protective role in the gerbil brain.

A new role for matrix metalloproteinase-3 in the NGF metabolic pathway: Proteolysis of mature NGF and sex-specific differences in the continuum of Alzheimer's pathology

Matrix metalloproteinase-3 (MMP-3) has been associated with risk of Alzheimer's disease (AD). In this study we introduce a novel role for MMP-3 in degrading nerve growth factor (NGF) in vivo and examine its mRNA and protein expression across the continuum of AD pathology. We provide evidence that MMP-3 participates in the degradation of mature NGF in vitro and in vivo and that it is secreted from the rat cerebral cortex in an activity-dependent manner. We show that cortical MMP-3 is upregulated in the McGill-R-Thy1-APP transgenic rat model of AD-like amyloidosis. A similar upregulation was found in AD and MCI brains as well as in cognitively normal individuals with elevated amyloid deposition. We also observed that frontal cortex MMP-3 protein levels are higher in males. MMP-3 protein correlated with more AD neuropathology, markers of NGF metabolism, and lower cognitive scores in males but not in females. These results suggest that MMP-3 upregulation in AD might contribute to NGF dysmetabolism, and therefore to cholinergic atrophy and cognitive deficits, in a sex-specific manner. MMP-3 should be further investigated as a biomarker candidate or as a therapeutic target in AD.

Unravelling the Network of Nuclear Matrix Metalloproteinases for Targeted Drug Design

Matrix metalloproteinases (MMPs) are zinc-dependent endopeptidases that are responsible for the degradation of a wide range of extracellular matrix proteins, which are involved in many cellular processes to ensure the normal development of tissues and organs. Overexpression of MMPs has been observed to facilitate cellular growth, migration, and metastasis of tumor cells during cancer progression. A growing number of these proteins are being found to exist in the nuclei of both healthy and tumor cells, thus highlighting their localization as having a genuine purpose in cellular homeostasis. The mechanism underlying nuclear transport and the effects of MMP nuclear translocation have not yet been fully elucidated. To date, nuclear MMPs appear to have a unique impact on cellular apoptosis and gene regulation, which can have effects on immune response and tumor progression, and thus present themselves as potential therapeutic targets in certain types of cancer or disease. Herein, we highlight and evaluate what progress has been made in this area of research, which clearly has some value as a specific and unique way of targeting the activity of nuclear matrix metalloproteinases within various cell types.

Activation of endothelial Wnt/β-catenin signaling by protective astrocytes repairs BBB damage in ischemic stroke

The role of astrocytes in dysregulation of blood-brain barrier (BBB) function following ischemic stroke is not well understood. Here, we investigate the effects of restoring the repair properties of astrocytes on the BBB after ischemic stroke. Mice deficient for NHE1, a pH-sensitive Na⁺/H⁺ exchanger 1, in astrocytes have reduced BBB permeability after ischemic stroke, increased angiogenesis and cerebral blood flow perfusion, in contrast to wild-type mice. Bulk RNA-sequencing transcriptome analysis of purified astrocytes revealed that ∼177 genes were differentially upregulated in mutant astrocytes, with Wnt7a mRNA among the top genes. Using a Wnt reporter line, we confirmed that the pathway was upregulated in cerebral vessels of mutant mice after ischemic stroke. However, administration of the Wnt/β-catenin inhibitor, XAV-939, blocked the reparative effects of Nhe1-deficient astrocytes. Thus, astrocytes lacking pH-sensitive NHE1 protein are transformed from injurious to "protective" by inducing Wnt production to promote BBB repair after ischemic stroke.

The Relationship Between Cerebral Reperfusion And Regional Expression Of Matrix Metalloproteinase-9 In Rat Brain Following Focal Cerebral Ischemia

We investigated the effect of full and partial mechanical reperfusion on MMP-9 expression in rat brain following middle cerebral artery occlusion, mimicking mechanical thrombectomy. Using percentage hemispheric lesion volume and oedema as measures, partial reperfusion reduced extent of brain damage caused by MCA occlusion, but the protective effect was less pronounced than with complete reperfusion. Using ELISA quantification in fresh frozen tissue, confirmed by immunofluorescence in perfusion fixed tissue, increased MMP-9 expression was observed in infarcted tissue. MMP-9 was increased in lesioned tissue of the anterior and posterior temporal cortex and underlying striatal tissue, but also the normal appearing frontal cortex. No significant increase in MMP-9 in the hippocampus was observed, nor in the unlesioned contralateral hemisphere. Both partial reperfusion and full reperfusion reduced the regional MMP expression significantly. The highest levels of MMP-9 were observed in lesioned brain regions in the non-reperfused group. MMP-9 expression was evident in microvessels and in neuronal cell bodies of affected tissue. This study shows that MMP-9 brain levels are reduced relative to the extent of reperfusion. These observations suggest targeting early increases in MMP-9 expression as a possible neuroprotective therapeutic strategy and highlight the rat MCA occlusion model as an ideal model in which to study candidate therapeutics.

Diabetes Mellitus/Poststroke Hyperglycemia: a Detrimental Factor for tPA Thrombolytic Stroke Therapy

Intravenous administration of tissue-type plasminogen activator (IV tPA) therapy has long been considered a mainstay in ischemic stroke management. However, patients respond to IV tPA therapy unequally with some subsets of patients having worsened outcomes after treatment. In particular, diabetes mellitus (DM) is recognized as a clinically important vascular comorbidity that leads to lower recanalization rates and increased risks of hemorrhagic transformation (HT). In this short-review, we summarize the recent advances in understanding of the underlying mechanisms involved in post-IV tPA worsening of outcome in diabetic stroke. Potential pathologic factors that are related to the suboptimal tPA recanalization in diabetic stroke include higher plasma plasminogen activator inhibitor (PAI)-1 level, diabetic atherogenic vascular damage, glycation of the tPA receptor annexin A2, and alterations in fibrin clot density. While factors contributing to the exacerbation of HT in diabetic stroke include hyperglycemia, vascular oxidative stress, and inflammation, tPA neurovascular toxicity and imbalance in extracellular proteolysis are discussed. Besides, impaired collaterals in DM also compromise the efficacy of IV tPA therapy. Additionally, several tPA combination approaches developed from experimental studies that may help to optimize IV tPA therapy are also briefly summarized. In summary, more research efforts are needed to improve the safety and efficacy of IV tPA therapy in ischemic stroke patients with DM/poststroke hyperglycemia.

Mechanisms in blood-brain barrier opening and metabolism-challenged cerebrovascular ischemia with emphasis on ischemic stroke

Stroke is the leading cause of disability among adults as well as the 2nd leading cause of death globally. Ischemic stroke accounts for about 85% of strokes, and currently, tissue plasminogen activator (tPA), whose therapeutic window is limited to up to 4.5 h for the appropriate population, is the only FDA approved drug in practice and medicine. After a stroke, a cascade of pathophysiological events results in the opening of the blood-brain barrier (BBB) through which further complications, disabilities, and mortality are likely to threaten the patient's health. Strikingly, tPA administration in eligible patients might cause hemorrhagic transformation and sustained damage to BBB integrity. One must, therefore, delineate upon stroke onset which cellular and molecular factors mediate BBB permeability as well as what key roles BBB rupture plays in the pathophysiology of stroke. In this review article, given our past findings of mechanisms underlying BBB opening in stroke animal models, we elucidate cellular, subcellular, and molecular factors involved in BBB permeability after ischemic stroke. The contribution of each factor to stroke severity and outcome is further discussed. Determinant factors in BBB permeability and stroke include mitochondria, miRNAs, matrix metalloproteinases (MMPs), immune cells, cytokines, chemokines, and adhesion proteins. Once these factors are interrogated and their roles in the pathophysiology of stroke are determined, novel targets for drug discovery and development can be uncovered in addition to novel therapeutic avenues for human stroke management.

Cadmium-Induced Oxidative Stress: Focus on the Central Nervous System

Cadmium (Cd), a category I human carcinogen, is a well-known widespread environmental pollutant. Chronic Cd exposure affects different organs and tissues, such as the central nervous system (CNS), and its deleterious effects can be linked to indirect reactive oxygen species (ROS) generation. Since Cd is predominantly present in +2 oxidation state, it can interplay with a plethora of channels and transporters in the cell membrane surface in order to enter the cells. Mitochondrial dysfunction, ROS production, glutathione depletion and lipid peroxidation are reviewed in order to better characterize the Cd-elicited molecular pathways. Furthermore, Cd effects on different CNS cell types have been highlighted to better elucidate its role in neurodegenerative disorders. Indeed, Cd can increase blood-brain barrier (BBB) permeability and promotes Cd entry that, in turn, stimulates pericytes in maintaining the BBB open. Once inside the CNS, Cd acts on glial cells (astrocytes, microglia, oligodendrocytes) triggering a pro-inflammatory cascade that accounts for the Cd deleterious effects and neurons inducing the destruction of synaptic branches.

Glycyrrhizin Prevents Hemorrhagic Transformation and Improves Neurological Outcome in Ischemic Stroke with Delayed Thrombolysis Through Targeting Peroxynitrite-Mediated HMGB1 Signaling

Peroxynitrite (ONOO^-) and high mobility group box 1 protein (HMGB1) are important cytotoxic factors contributing to cerebral ischemia-reperfusion injury. However, the roles of ONOO^- in mediating HMGB1 expression and its impacts on hemorrhagic transformation (HT) in ischemic brain injury with delayed t-PA treatment remain unclear. In the present study, we tested the hypothesis that ONOO^- could directly mediate the activation and release of HMGB1 in ischemic brains with delayed t-PA treatment. With clinical studies, we found that plasma nitrotyrosine (NT, a surrogate marker of ONOO^-) was positively correlated with HMGB1 level in acute ischemic stroke patients. Hemorrhagic transformation and t-PA-treated ischemic stroke patients had increased levels of nitrotyrosine and HMGB1 in plasma. In animal experiments, we found that FeTmPyP, a representative ONOO^- decomposition catalyst (PDC), significantly reduced the expression of HMGB1 and its receptor TLR2, and inhibited MMP-9 activation, preserved collagen IV and tight junction claudin-5 in ischemic rat brains with delayed t-PA treatment. ONOO^- donor SIN-1 directly induced expression of HMGB1 and its receptor TLR2 in naive rat brains in vivo and induced HMGB1 in brain microvascular endothelial b.End3 cells in vitro. Those results suggest that ONOO^- could activate HMGB1/TLR2/MMP-9 signaling. We then addressed whether glycyrrhizin, a natural HMGB1 inhibitor, could inhibit ONOO^- production and the antioxidant properties of glycyrrhizin contribute to the inhibition of HMGB1 and the neuroprotective effects on attenuating hemorrhagic transformation in ischemic stroke with delayed t-PA treatment. Glycyrrhizin treatment downregulated the expressions of NADPH oxidase p47 phox and p67 phox and iNOS, inhibited superoxide and ONOO^- production, reduced the expression of HMGB1, TLR2, MMP-9, preserved type IV collagen and claudin-5 in ischemic brains. Furthermore, glycyrrhizin significantly decreased the mortality rate, attenuated hemorrhagic transformation, brain swelling, blood-brain barrier damage, neuronal apoptosis, and improved neurological outcomes in the ischemic stroke rat model with delayed t-PA treatment. In conclusion, peroxynitrite-mediated HMGB1/TLR2 signaling contributes to hemorrhagic transformation, and glycyrrhizin could be a potential adjuvant therapy to attenuate hemorrhagic transformation, possibly through inhibiting the ONOO^-/HMGB1/TLR2 signaling cascades.

Suppression of Cerebral Ischemia/Reperfusion Injury by Efficient Release of Encapsulated Ifenprodil From Liposomes Under Weakly Acidic pH Conditions

Although N-methyl-d-aspartate receptor antagonists are hopeful therapeutic agents against cerebral ischemia/reperfusion (I/R) injury, effective approaches are needed to allow such agents to pass through the blood-brain barrier, thus increasing bioavailability of the antagonists to realize secure treatment. We previously demonstrated the usefulness of liposomal delivery of neuroprotectants via spaces between the disrupted blood-brain barrier induced after cerebral I/R. In the present study, a liposomal formulation of an N-methyl-d-aspartate receptor antagonist, ifenprodil, was newly designed; and the potential of liposomal ifenprodil was evaluated in transient middle cerebral artery occlusion rats. Ifenprodil was encapsulated into liposomes by a remote loading method using pH gradient between internal and external water phases of liposomes, focusing on differences of its solubility in water depending on pH. The encapsulated ifenprodil could be quickly released from the liposomes in vitro under a weakly acidic pH condition, which is a distinctive condition after cerebral I/R. Liposomal ifenprodil treatment significantly alleviated I/R-induced increase in permeability of the BBB by inhibiting superoxide anion production, resulting in ameliorating ischemic brain damage. Taken together, these results suggest that Ifen-Lip could become a hopeful neuroprotectant for cerebral I/R injury via efficient release of the encapsulated ifenprodil under weakly acidic pH conditions.

Matrix metalloproteinases and ADAMs in stroke

Stroke is a leading cause of death and disability worldwide. However, after years of in-depth research, the pathophysiology of stroke is still not fully understood. Increasing evidence shows that matrix metalloproteinases (MMPs) and "a disintegrin and metalloproteinase" (ADAMs) participate in the neuro-inflammatory cascade that is triggered during stroke but also in recovery phases of the disease. This review covers the involvement of these proteins in brain injury following cerebral ischemia which has been widely studied in recent years, with efforts to modulate this group of proteins in neuroprotective therapies, together with their implication in neurorepair mechanisms. Moreover, the review also discusses the role of these proteins in specific forms of neurovascular disease, such as small vessel diseases and intracerebral hemorrhage. Finally, the potential use of MMPs and ADAMs as guiding biomarkers of brain injury and repair for decision-making in cases of stroke is also discussed.

Role of Matrix Metalloproteinase-9 in Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Neonatal encephalopathy is a heterogeneous syndrome characterised by signs of central nervous system dysfunction in the newborn. Matrix metalloproteinase-9(MMP-9) increases the blood-brain barrier permeability, and their inhibitors can reduce its damage. MMP-9 has been implicated specifically in cerebral ischemia.

AIM

To measure serum MMP-9 in neonatal hypoxic-ischemic encephalopathy and evaluate its correlation to the severity of early prediction and treatment.

METHODS

its case-control study. The serum concentration of MMP-9 was determined by ELISA in 100 hypoxic neonates and 50 healthy neonates of matched age and sex who served as controls.

RESULTS

In our present study the serum MMP-9 level was significantly higher at p = 0.0001 in hypoxic-ischemic full-term newborns (176.7 ± 68.7 ng/ml)as compared to control newborn (69.4 ± 34.85 ng/ml)and it was significantly higher at p = 0.0075 in hypoxic-ischemic preterm newborn (171.2 ± 132.9 ng/ml) when compared to control newborn (72.54 ± 36.74 ng/ml), also MMP-9 was significantly higher at Sarnat stage III at p = 0.0001.

CONCLUSION

Serum MMP-9 level was significantly higher in hypoxic-ischemic newborns, and significantly increased with severity, so we suggest that serum MMP-9 level is important for predicting neurological sequel and severity in neonatal encephalopathy.

Neuroprotective effect of Vanillin on hypoxic-ischemic brain damage in neonatal rats

Neonatal hypoxic-ischemic brain damage (HIBD) is a leading cause of death and perpetual neurological dysfunction in neonates. Vanillin (Van), a natural phenolic compound with neuroprotective properties, exerts neuroprotection on a gerbil model of global ischemia by inhibiting oxidative damage. This study aimed to explore the potential neuroprotective roles of Van in neonatal rats suffering from hypoxic-ischemic (HI). An HI model of 7-day-old SD rats was induced by left carotid artery ligation followed by exposure to 8% oxygen (balanced with nitrogen) for 2.5 h at 37 °C. At 48 h after intraperitoneal injection with Van (20, 40, and 80 mg/kg) or saline, neurobehavioral function, cerebral infract volume, brain water content, and histomorphological changes were performed to evaluate brain injury. Transmission electron microscopy and immunoglobulin G (IgG) staining were conducted to evaluate the integrity of the blood-brain barrier (BBB). The levels of oxidative stress and tight junction proteins, as well as the activities of matrix metalloproteinases (MMPs), were also determined in the ipsilateral hemisphere. Results showed that Van post-treatment significantly ameliorated early neurobehavioral deficits, decreased infarct volume and brain edema, as well as attenuated histopathologic injury and IgG extravasation. Furthermore, Van markedly increased the activities of endogenous antioxidant enzymes and decreased malondialdehyde content. Meanwhile, the activation of MMP-2 and MMP-9 induced by HI was partially blocked by Van. Finally, Van obviously increased the expression of ZO-1, Occludin, and Claudin-5 compared with the HI group. Collectively, Van can provide neuroprotective effects against neonatal HIBD possibly by attenuating oxidative damage and preserving BBB integrity.

Immunomodulatory Therapeutic Strategies in Stroke

The role of immunity in all stages of stroke is increasingly being recognized, from the pathogenesis of risk factors to tissue repair, leading to the investigation of a range of immunomodulatory therapies. In the acute phase of stroke, proposed therapies include drugs targeting pro-inflammatory cytokines, matrix metalloproteinases, and leukocyte infiltration, with a key objective to reduce initial brain cell toxicity. Systemically, the early stages of stroke are also characterized by stroke-induced immunosuppression, where downregulation of host defences predisposes patients to infection. Therefore, strategies to modulate innate immunity post-stroke have garnered greater attention. A complementary objective is to reduce longer-term sequelae by focusing on adaptive immunity. Following stroke onset, the integrity of the blood–brain barrier is compromised, exposing central nervous system (CNS) antigens to systemic adaptive immune recognition, potentially inducing autoimmunity. Some pre-clinical efforts have been made to tolerize the immune system to CNS antigens pre-stroke. Separately, immune cell populations that exhibit a regulatory phenotype (T- and B- regulatory cells) have been shown to ameliorate post-stroke inflammation and contribute to tissue repair. Cell-based therapies, established in oncology and transplantation, could become a strategy to treat the acute and chronic stages of stroke. Furthermore, a role for the gut microbiota in ischaemic injury has received attention. Finally, the immune system may play a role in remote ischaemic preconditioning-mediated neuroprotection against stroke. The development of stroke therapies involving organs distant to the infarct site, therefore, should not be overlooked. This review will discuss the immune mechanisms of various therapeutic strategies, surveying published data and discussing more theoretical mechanisms of action that have yet to be exploited.

Neuroprotective Effects and Hepatorenal Toxicity of Angong Niuhuang Wan Against Ischemia-Reperfusion Brain Injury in Rats

Angong Niuhuang Wan (AGNHW) is a classic prescription in traditional Chinese medicine (TCM) used for stroke treatment, but its efficacies remain to be confirmed. With its arsenic- and mercury-containing materials, the application of AGNHW raises great safety concerns. Herein, we aim to explore the neuropharmacological effects against cerebral ischemia-reperfusion injury and evaluate the toxicological effects of AGNHW for better use. Male SD rats were subjected to 2 h of middle cerebral artery occlusion (MCAO) and following 22 h of reperfusion. AGNHW (257 mg/kg, 1× AGNHW) were orally administered for pharmacological effects and 257, 514, and 1,028 mg/kg (equivalent to 1×, 2×, 4× AGNHW) were used for the toxicological study. The results revealed that AGNHW treatment reduced the infarct size and protected the blood-brain barrier (BBB) integrity in the MCAO rat ischemic stroke model. AGNHW treatment up-regulated bcl-2 expression and down-regulated the expressions of Bax, p47_phox, inducible nitric oxide synthase (iNOS), and 3-nitrotyrosine (3-NT), and inhibited the expressions and activities of matrix metalloproteinase-2 (MMP-2), MMP-9, and reserved tight junction protein zonula occludens-1 (ZO-1) and claudin-5 in the ischemic brains. These results indicated that the neuroprotective mechanisms of AGNHW could be associated with its antioxidant properties by inhibiting oxidative/nitrative stress-mediated MMP activation and protecting tight junction proteins in the ischemic brains. Administration of 1× AGNHW for 7 days would not induce the accumulation of mercury in blood, liver, and kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days increased the level of mercury in the kidney. For arsenic level, administration of 1× AGNHW for 7 days would increase the level of arsenic in the liver and blood without increase of arsenic in the kidney at day 14. Administration of 2× AGNHW and 4× AGNHW for 7 days would further increase the level of arsenic in the liver and blood. There is no influence on body weight, organ index, histological structures, and renal and liver functions. These results suggest that short-term treatment of AGNHW within 1 week should be safe and has neuroprotective effects against cerebral ischemia-reperfusion injury.

Statins and the Brain: More than Lipid Lowering Agents?

Background:

Statins represent a class of medications widely prescribed to efficiently treat dyslipidemia. These drugs inhibit 3-βhydroxy 3β-methylglutaryl Coenzyme A reductase (HMGR), the rate-limiting enzyme of mevalonate (MVA) pathway. Besides cholesterol, MVA pathway leads to the production of several other compounds, which are essen-tial in the regulation of a plethora of biological activities, including in the central nervous system. For these reasons, statins are able to induce pleiotropic actions, and acquire increased interest as potential and novel modulators in brain processes, es-pecially during pathological conditions.

Objective:

The purpose of this review is to summarize and examine the current knowledge about pharmacokinetic and phar-macodynamic properties of statins in the brain. In addition, effects of statin on brain diseases are discussed providing the most up-to-date information.

Methods:

Relevant scientific information was identified from PubMed database using the following keywords: statins and brain, central nervous system, neurological diseases, neurodegeneration, brain tumors, mood, stroke.

Results:

315 scientific articles were selected and analyzed for the writing of this review article. Several papers highlighted that statin treatment is effective in preventing or ameliorating the symptomatology of a number of brain pathologies. Howev-er, other studies failed to demonstrate a neuroprotective effect.

Conclusion:

Even though considerable research studies suggest pivotal functional outcomes induced by statin therapy, addi-tional investigation is required to better determine the pharmacological effectiveness of statins in the brain, and support their clinical use in the management of different neuropathologies.

Neuroprotective Role of Agmatine in Neurological Diseases

Background:

Neurological diseases have always been one of the leading cause of mobility and mortality world-widely. However, it is still lacking efficient agents. Agmatine, an endogenous polyamine, exerts its diverse biological characteristics and therapeutic potential in varied aspects.

Methods:

This review would focus on the neuroprotective actions of agmatine and its potential mechanisms in the setting of neurological diseases.

Results:

Numerous studies had demonstrated the neuroprotective effect of agmatine in varied types of neurological diseases, including acute attack (stroke and trauma brain injury) and chronic neurodegenerative diseases (Parkinson's disease, Alz-heimer’s disease). The potential mechanism of agmatine induced neuroprotection includes anti-oxidation, anti-apoptosis, anti-inflammation, brain blood barrier (BBB) protection and brain edema prevention.

Conclusions:

The safety and low incidence of adverse effects indicate the vast potential therapeutic value of agmatine in the treatment of neurological diseases. However, most of the available studies relate to the agmatine are conducted in experi-mental models, more clinical trials are needed before the agmatine could be extensively clinically used