Dose-Dependent Influences of Ethanol on Ischemic Stroke: Role of Inflammation

Long-Term Alcohol Exposure Aggravates Ischemic Stroke-Induced Damage by Promoting Pericyte NLRP3 Inflammasome Activation via Pre-Activating the TLR4/NF-κB Pathway in Rats

Background

Ischemic stroke (IS) is one of the leading causes of death and disability in the world, and alcohol consumption has been gaining attention as an independent risk factor for IS. Blood-brain barrier (BBB) dysfunction and neuroinflammation are the core of cerebral ischemia/reperfusion (I/R) injury, and pericytes play a crucial role in the structure and function. This study is to explore the effects of long-term alcohol consumption on IS and the potential mechanisms of pericytes.

Methods

Rat models of long-term alcohol intake followed by transient middle cerebral artery occlusion stroke (EtOH+tMCAO) and cell models of oxygen-glucose deprivation/reoxygenation (OGD/R) with alcohol pre-treatment were constructed.

Results

Worsened infarct volume, neurological scores, and BBB disruption were observed in the EtOH+tMCAO group compared with the tMCAO group, and immunofluorescence staining showed increased pericytes NLPR3 inflammasome activation at the ischemic penumbra. In vitro, pericyte mortality and LDH release elevated pre-treated by alcohol after OGD/R, and amplified expression of NLRP3 inflammasome was detected by Western blotting and qPCR. Alcohol pre-treatment activated the TLR4/NF-κB pathway, and transfecting pericytes with TLR4-small interfering RNA (siRNA) to block TLR4 signaling markedly restrained NLRP3 inflammasome over-activation. Injecting TAK-242 in rats alleviated neurological impairment caused by alcohol.

Conclusion

Long-term alcohol pre-treatment aggravated ischemic stroke-induced brain damage by activating NLRP3 inflammasome via TLR4/NF-κB signaling pathway in the pericytes.

Risk Factors Associated With Exclusion of Obese Patients Ischemic Stroke With a History of Smoking From Thrombolysis Therapy

The objective of this study is to determine risk factors that may contribute to exclusion decision from recombinant tissue plasminogen activator (rtPA) in patients with acute ischemic stroke (AIS) with a combined current or history of smoking and obesity. This study was conducted on data from 5469 patients with AIS collected from a regional stroke registry. Risk factors associated with inclusion or exclusion from rtPA were determined using multivariate logistic regression analysis. The adjusted odds ratios and 95% confidence interval for each risk factor were used to predict the increasing odds of an association of a specific risk factor with exclusion from rtPA. In the adjusted analysis, obese patients with AIS with a history of smoking (current and previous) excluded from rtPA were more likely to present with carotid artery stenosis (OR = 0.069, 95% CI 0.011-0.442), diabetes (OR = 0.604, 95% CI 0.366-0.997), higher total cholesterol (OR = 0.975, 95% CI 0.956-0.995), and history of alcohol use (OR = 0.438, 95% CI 0.232-0.828). Higher NIHSS score (OR = 1.051, 95% CI 1.017-1.086), higher triglycerides (OR = 1.004, 95% CI 1.001-1.006), and higher high-density lipoprotein (OR = 1.028, 95% CI 1.000-1.057) were associated with the inclusion for rtPA. Our findings reveal specific risk factors that contribute to the exclusion of patients with AIS with a combined effect of smoking and obesity from rtPA. These findings suggest the need to develop management strategies to improve the use of rtPA for obese patients with AIS with a history of smoking.

Light Alcohol Consumption Promotes Early Neurogenesis Following Ischemic Stroke in Adult C57BL/6J Mice

Ischemic stroke is one of the leading causes of death and disability worldwide. Neurogenesis plays a crucial role in postischemic functional recovery. Alcohol dose-dependently affects the prognosis of ischemic stroke. We investigated the impact of light alcohol consumption (LAC) on neurogenesis under physiological conditions and following ischemic stroke. C57BL/6J mice (three months old) were fed with 0.7 g/kg/day ethanol (designed as LAC) or volume-matched water (designed as control) daily for eight weeks. To evaluate neurogenesis, the numbers of 5-bromo-2-deoxyuridine (BrdU)+/doublecortin (DCX)+ and BrdU+/NeuN+ neurons were assessed in the subventricular zone (SVZ), dentate gyrus (DG), ischemic cortex, and ischemic striatum. The locomotor activity was determined by the accelerating rotarod and open field tests. LAC significantly increased BrdU+/DCX+ and BrdU+/NeuN+ cells in the SVZ under physiological conditions. Ischemic stroke dramatically increased BrdU+/DCX+ and BrdU+/NeuN+ cells in the DG, SVZ, ischemic cortex, and ischemic striatum. The increase in BrdU+/DCX+ cells was significantly greater in LAC mice compared to the control mice. In addition, LAC significantly increased BrdU+/NeuN+ cells by about three folds in the DG, SVZ, and ischemic cortex. Furthermore, LAC reduced ischemic brain damage and improved locomotor activity. Therefore, LAC may protect the brain against ischemic stroke by promoting neurogenesis.

Innate immune activation: Parallels in alcohol use disorder and Alzheimer’s disease

Alcohol use disorder is associated with systemic inflammation and organ dysfunction especially in the liver and the brain. For more than a decade, studies have highlighted alcohol abuse-mediated impairment of brain function and acceleration of neurodegeneration through inflammatory mechanisms that directly involve innate immune cells. Furthermore, recent studies indicate overlapping genetic risk factors between alcohol use and neurodegenerative disorders, specifically regarding the role of innate immunity in the pathomechanisms of both areas. Considering the pressing need for a better understanding of the relevance of alcohol abuse in dementia progression, here we summarize the molecular mechanisms of neuroinflammation observed in alcohol abuse and Alzheimer’s disease, the most common cause of dementia. In addition, we highlight mechanisms that are already established in the field of Alzheimer’s disease that may be relevant to explore in alcoholism to better understand alcohol mediated neurodegeneration and dementia, including the relevance of the liver-brain axis.

Lipid-mediated ex vivo cell surface engineering for augmented cellular functionalities

Once administrated, intercellular adhesion to recognize and/or arrest target cells is essential for specific treatments, especially for cancer or tumor. However, immune cells administrated into the tumor-microenvironment could lose their intrinsic functionalities such as target recognition ability, resulting in an ineffective cancer immunotherapy. Various manipulation techniques for decorating functional moieties onto cell surface and enhancing target recognition have been developed. A hydrophobic interaction-mediated ex-vivo cell surface engineering using lipid-based biomaterials could be a state-of-the-art engineering technique that could achieve high-efficiency cell surface modification by a single method without disturbance of intrinsic characteristics of cells. In this regard, this review provides design principles for the development of lipid-based biomaterials with a linear structure of lipid, polyethylene glycol, and functional group, strategies for the synthesis process, and their practical applications in biomedical engineering. Especially, we provide new insights into the development of a novel surface coating techniques for natural killer (NK) cells with engineering decoration of cancer targeting moieties on their cell surfaces. Among immune cells, NK cells are interesting cell population for substituting T cells because of their excellent safety and independent anticancer efficacy. Thus, optimal strategies to select cancer-type-specific targeting moieties and present them onto the surface of immune cells (especially, NK cells) using lipid-based biomaterials could provide additional tools to capture cancer cells for developing novel immune cell therapy products. Enhanced anticancer efficacies by surface-engineered NK cells have been demonstrated both in vitro and in vivo. Therefore, it could be speculated that recent progresses in cell surface modification technology via lipid-based biomaterials could strengthen immune surveillance and immune synapses for utilization in a next-generation cancer immunotherapy, beyond currently available genetic engineering tool such as chimeric antigen receptor-mediated immune cell modulation.

Impact of Alcohol Consumption on Male Fertility Potential: A Narrative Review

Alcohol abuse disorder is a serious condition, implicating more than 15 million people aged 12 years and older in 2019 in the United States. Ethanol (or ethyl alcohol) is mainly oxidized in the liver, resulting in the synthesis of acetaldehyde and acetate, which are toxic and carcinogenic metabolites, as well as in the generation of a reductive cellular environment. Moreover, ethanol can interact with lipids, generating fatty acid ethyl esters and phosphatidylethanol, which interfere with physiological cellular pathways. This narrative review summarizes the impact of excessive alcohol consumption on male fertility by describing its metabolism and how ethanol consumption may induce cellular damage. Furthermore, the impact of alcohol consumption on hormonal regulation, semen quality, and genetic and epigenetic regulations is discussed based on evidence from animal and human studies, focusing on the consequences on the offspring. Finally, the limitations of the current evidence are discussed. Our review highlights the association between chronic alcohol consumption and poor semen quality, mainly due to the development of oxidative stress, as well as its genotoxic impact on hormonal regulation and DNA integrity, affecting the offspring’s health. New landscapes of investigation are proposed for the identification of molecular markers for alcohol-associated infertility, with a focus on advanced OMICS-based approaches applied to the analysis of semen samples.

Protective Effect of Low-Dose Alcohol Consumption against Post-Ischemic Neuronal Apoptosis: Role of L-PGDS

Ischemic stroke is one of the leading causes of permanent disability and death in adults worldwide. Apoptosis is a major element contributing to post-ischemic neuronal death. We previously found that low-dose alcohol consumption (LAC) protects against neuronal apoptosis in the peri-infarct cortex following transient focal cerebral ischemia. Lipocalin-type prostaglandin D2 synthase (L-PGDS), which is mainly localized in the central nervous system (CNS), was previously shown to inhibit neuronal apoptosis. Therefore, we determined whether L-PGDS is involved in the protective effect of LAC against post-ischemic neuronal apoptosis. Wild-type (WT), CaMKIIα^CreERT2/+/L-PGDS^+/+, and CaMKIIα^CreERT2/+/L-PGDS^flox/flox mice on a C57BL/6J background were gavage fed with ethanol or volume-matched water once a day for 8 weeks. Tamoxifen (2 mg/day) was given intraperitoneally to CaMKIIα^CreERT2/+/L-PGDS^+/+ and CaMKIIα^CreERT2/+/L-PGDS^flox/flox mice for 5 days during the fourth week. AT-56 (30 mg/kg/day), a selective inhibitor of L-PGDS, was given orally to AT-56-treated WT mice from the fifth week for four weeks. Cerebral ischemia/reperfusion (I/R) injury, TUNEL-positive neurons, and cleaved caspase-3-positive neurons were measured at 24 h of reperfusion after a 90 min unilateral middle cerebral artery occlusion (MCAO). We found that 0.7 g/kg/day but not 2.8 g/kg/day ethanol significantly upregulated L-PGDS in the cerebral cortex. In addition, 0.7 g/kg/day ethanol diminished cerebral ischemia/reperfusion (I/R) injury and TUNEL-positive and cleaved caspase-3-positive neurons in the peri-infarct cortex in WT and CaMKIIα^CreERT2/+/L-PGDS^+/+ mice. Furthermore, the neuroprotective effect of 0.7 g/kg/day ethanol was alleviated in AT-56-treated WT and CaMKIIα^CreERT2/+/L-PGDS^flox/flox mice. Our findings suggest that LAC may protect against cerebral I/R injury by suppressing post-ischemic neuronal apoptosis via an upregulated L-PGDS.

Chronic Low-Dose Alcohol Consumption Promotes Cerebral Angiogenesis in Mice

Chronic alcohol consumption dose-dependently affects the incidence and prognosis of ischemic stroke. We determined the influence of chronic alcohol consumption on cerebral angiogenesis under physiological conditions and following ischemic stroke. In in vitro studies, acute exposure to low-concentration ethanol significantly increased angiogenic capability and upregulated vascular endothelial growth factor A (VEGF-A) and vascular endothelial growth factor receptor 2 (VEGFR2) in C57BL/6J mouse brain microvascular endothelial cells (MBMVECs). The increased angiogenic capability was abolished in the presence of a VEGFR2 inhibitor. In addition, the increased angiogenic capability and upregulated VEGF-A and VEGFR2 remained in chronically low-concentration ethanol-exposed MBMVECs. In in vivo studies, 8-week gavage feeding with low-dose ethanol significantly increased vessel density and vessel branches and upregulated VEGF-A and VEGFR2 in the cerebral cortex under physiological conditions. Furthermore, vessel density, vessel branches, and expression of VEGF-A and VEGFR2 in the peri-infarct cortex were significantly greater in low-dose ethanol-fed mice at 72 h of reperfusion. Although low-dose ethanol did not alter cerebral vasoreactivity and regional cerebral blood flow (rCBF) either before or during ischemia, it significantly augmented post-ischemic hyperemia during reperfusion. In contrast, exposure to high-concentration ethanol and 8-week gavage feeding with high-dose ethanol only had a mild inhibitory effect on angiogenic capability and cerebral angiogenesis, respectively. We conclude that heavy alcohol consumption may not dramatically alter cerebral angiogenesis, whereas light alcohol consumption significantly promotes cerebral angiogenesis.

Role of melatonin in TLR4-mediated inflammatory pathway in the MTPT-induced mouse model

Neuroinflammation has an essential role in various neurodegenerative diseases including Parkinson's disease (PD). Microglial activation as a result of neuroinflammation exacerbates the pathological consequences of the disease. The toxic effect of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes alpha-synuclein (α-synuclein) accumulation, which leads to dopaminergic neuron death in the MPTP-induced mouse model. Toll-like receptor 4 (TLR4) stimulates release of cytokine through NF-kB by activating glial cells, thus resulting in the death of dopaminergic neurons. Melatonin has the ability to cross the blood-brain barrier and protect neurons through anti-inflammatory properties. We hypothesized that melatonin could suppress TLR4-mediated neuroinflammation, decrease cytokine release due to the inflammatory response, and reduce dopaminergic neuron loss in the MPTP-induced mouse model. In the MPTP-induced mouse model, we aimed to assess the neuroinflammatory responses caused by TLR4 activation as well as the effect of melatonin on these responses. Three-month-old male C57BL/6 mice were randomly divided into five groups; Control (Group-C), Sham (Group-S), Melatonin-treated (Group-M), MPTP-injected (Group-P), and MPTP + melatonin-injected (Group-P + M). MPTP toxin (20 mg/kg) was dissolved in saline and intraperitoneally (i.p.) injected to mice for two days with 12 h intervals. The total dose per mouse was 80 mg/kg. Melatonin was administered (20 mg/kg) intraperitoneally to Group-M and Group-P + M twice a day for five days. Eight days after starting the experiment, the motor activities of mice were evaluated by locomotor activity tests. The effects on dopamine neurons in the SNPc was determined by tyrosine hydroxylase (TH) immunohistochemistry. TLR4, α-synuclein, and p65 expression was evaluated by immunostaining as well. The amount of TNF-alpha in the total brain was evaluated by western blot analysis. In our results seen that locomotor activity was lower in Group-P compared to Group-C. However, melatonin administration was improved this impairment. MPTPcaused decrease in TH immuno-expression in dopaminergic neurons in Group-P. TLR4 (p < 0.001), α-synuclein (p < 0.001), and p65 (p < 0.01) immuno-expressions were also decreased in Group-P+M compared to Group-P (using MPTP). TNF-α expression was lower in Group-C, Group-S, Group-M, and Group-P+M, when compared to Group-P (p < 0.0001) due to the absence of inflammatory response. In conclusion, our study revealed that melatonin administration reduced α-synuclein aggregation and TLR4-mediated inflammatory response in the MPTP-induced mouse model.

Protective Effects of Low-Dose Alcohol against Acute Stress-Induced Renal Injury in Rats: Involvement of CYP4A/20-HETE and LTB4/BLT1 Pathways

Low-dose alcohol possesses multiple bioactivities. Accordingly, we investigated the protective effect and related molecular mechanism of low-dose alcohol against acute stress- (AS-) induced renal injury. Herein, exhaustive swimming for 15 min combined with restraint stress for 3 h was performed to establish a rat acute stress model, which was verified by an open field test. Evaluation of renal function (blood creatinine and urea nitrogen), urine test (urine leukocyte esterase and urine occult blood), renal histopathology, oxidative stress, inflammation, and apoptosis was performed. The key indicators of the cytochrome P450 (CYP) 4A1/20-hydroxystilbenetetraenoic acid (20-HETE) pathway, cyclooxygenase (COX)/prostaglandin E₂ (PGE₂) pathway, and leukotriene B₄ (LTB₄)/leukotriene B₄ receptor 1 (BLT1) pathway were measured by real-time PCR and ELISA. We found that low-dose alcohol (0.05 g/kg, i.p.) ameliorated AS-induced renal dysfunction and histological damage. Low-dose alcohol also attenuated AS-induced oxidative stress and inflammation, presenting as reduced malondialdehyde and hydrogen peroxide formation, increased superoxide dismutase and glutathione activity, and decreased myeloperoxidase, interleukin-6, interleukin-1β, and monocyte chemoattractant protein-1 levels (P < 0.05). Moreover, low-dose alcohol alleviated AS-induced apoptosis by downregulating Bax and cleaved caspase 3 protein expression and reduced numbers of terminal deoxynucleotidyl transferase-mediated dUTP nick-end label-positive cells (P < 0.01). Correlation analysis indicated that 20-HETE was strongly correlated with oxidative stress, while LTB₄ was strongly correlated with inflammation. Low-dose alcohol inhibited AS-induced increases in CYP4A1, CYP4A2, CYP4A3, CYP4A8, and BLT1 mRNA levels and LTB₄ and 20-HETE content (P < 0.01). Interestingly, low-dose alcohol had no effect on COX1 or COX2 mRNA expression or the concentration of PGE₂. Furthermore, low-dose alcohol reduced calcium-independent phospholipase A₂ mRNA expression, but did not affect secreted phospholipase A₂ or cytosolic phospholipase A₂ mRNA expression. Together, these results indicate that low-dose alcohol ameliorated AS-induced renal injury by inhibiting CYP4A/20-HETE and LTB₄/BLT1 pathways, but not the COX/PGE₂ pathway.

Chronic Low-Dose Alcohol Consumption Attenuates Post-Ischemic Inflammation via PPARγ in Mice

Ischemic stroke is one of the leading causes of death and permanent disability in adults. Recently, we found that light alcohol consumption (LAC) suppresses post-ischemic inflammatory response, which plays an important role in ischemic brain damage. Our goal was to determine the role of peroxisome proliferator-activated receptor-gamma (PPARγ) in the anti-inflammatory effect of LAC against transient focal cerebral ischemia. In in vivo study, male C57BL/6J wild type (WT) and endothelial-specific conditional PPARγ knockout mice were gavage fed with 0.7 g/kg/day ethanol or volume-matched water daily for 8 weeks. From the 7th week, 3 mg/kg/day GW9662 (a selective PPARγ antagonist) was intraperitoneally given for two weeks. Cerebral ischemia/reperfusion (I/R) injury and expression of manganese superoxide dismutase (MnSOD) and adhesion molecules, neutrophil infiltration, and microglial activation in the cerebral cortex before and following a 90 min unilateral middle cerebral artery occlusion (MCAO)/24 h reperfusion were evaluated. In in vitro study, the impact of chronic alcohol exposure on expression of PPARγ and MnSOD in C57BL/6J mouse brain microvascular endothelial cells (MBMVECs) was measured. PPARγ and MnSOD were significantly upregulated in the cerebral cortex of ethanol-fed WT mice and low-concentration ethanol-exposed C57BL/6J MBMVECs. GW9662 significantly inhibited alcohol-induced upregulation of MnSOD. Eight-week ethanol feeding significantly reduced cerebral I/R injury and alleviated the post-ischemic inflammatory response (upregulation of intercellular adhesion molecule-1 (ICAM-1) and E-selectin, microglial activation, and neutrophil infiltration). Treatment with GW9662 and endothelial-specific conditional knockout of PPARγ did not alter cerebral I/R injury and the inflammatory response in the control mice but abolish the neuroprotective effect in ethanol-fed mice. In addition, GW9662 and endothelial-specific conditional knockout of PPARγ diminished the inhibitory effect of LAC on the post-ischemic expression of adhesion molecules and neutrophil infiltration. Our findings suggest that LAC may protect against cerebral I/R injury by suppressing the post-ischemic inflammation via activation of PPARγ.

Protective Role of Low Ethanol Administration Following Ischemic Stroke via Recovery of KCC2 and p75NTR Expression

A striking result from epidemiological studies show a correlation between low alcohol intake and lower incidence for ischemic stroke and severity of derived brain injury. Although reduced apoptosis and inflammation has been suggested to be involved, little is known about the mechanism mediating this effect in vivo. Increase in intracellular chloride concentration and derived depolarizing GABAAR-mediated transmission are common consequences following various brain injuries and are caused by the abnormal expression levels of the chloride cotransporters NKCC1 and KCC2. Downstream pro-apoptotic signaling through p75NTR may link GABAA depolarization with post-injury neuronal apoptosis. Here, we show that changes in GABAergic signaling, Cl- homeostasis, and expression of chloride cotransporters in the post-traumatic mouse brain can be significantly reduced by administration of 3% ethanol to the drinking water. Ethanol-induced upregulation of KCC2 has a positive impact on neuronal survival, preserving a large part of the cortical peri-infarct zone, as well as preventing the massive post-ischemic upregulation of the pro-apoptotic protein p75NTR. Importantly, intracortical multisite in vivo recordings showed that ethanol treatment could significantly ameliorate stroke-induced reduction in cortical activity. This surprising finding discloses a pathway triggered by low concentration of ethanol as a novel therapeutically relevant target.

Blood-brain barrier integrity is the primary target of alcohol abuse

The effects of long-term alcohol consumptions on cognitive function remain elusive with contradictory results. Whilst it is widely accepted that long-term intoxication can cause cognitive impairment, moderate drinking can improve cognitive function. In reality, many older people and those with chronic medical conditions are long-term alcohol consumers in Asian countries. Our previous studies have suggested that long-term alcohol consumption can damage blood-brain barrier (BBB) integrity and aggravate cognitive deficit in APPswe/PS1De9 mice, but little is known about the underlying mechanisms, especially whether this consumption can cause cognitive decline via aggravating BBB damage in people who are exposed to the risk factors for cognitive disorders such as aging or inflammation. These questions were addressed in this study. The mouse models of cognitive deficit induced by d-galactose or lipopolysaccharide, the important risk conditions in human on cognitive function, were used to evaluate the effects of long-term alcohol consumption on the BBB integrity. After alcohol administration for 30 days in these models the BBB integrity was significantly destroyed with remarkably increased permeability and down-regulated protein expression of zonula occludens-1, VE-cadherin, occludin, low-density lipoprotein receptor-related protein-1, receptor for advanced glycation end products, major facilitator superfamily domain-containing protein-2a and aquaporin-4, which is the most closely related with the structure and function of BBB integrity. Meanwhile, the level of oxidative stress in d-galactose mice or inflammatory factors in cortex and serum in lipopolysaccharide mice, which might be involved in the cognitive dysfunctions, was significantly amplified. Furthermore, the impaired memory and hippocampal neuron damage induced by d-galactose and lipopolysaccharide were concurrently aggravated. Collectively, our study provided novel and compelling evidence that the structural and functional proteins for BBB integrity may be the primary targets for the detrimental effects of alcohol abuse that lead to cognitive dysfunction and neurological deficits in high risk populations.

Low-dose alcohol ameliorated high fat diet-induced anxiety-related behavior via enhancing adiponectin expression and activating the Nrf2 pathway

Long-term high-fat-diet (HFD)-induced obesity is associated with many comorbidities, such as cognitive impairment and anxiety, which are increasing public health burdens that have gained prevalence in adolescents. Although low-dose alcohol could attenuate the risk of cardiovascular disease, its mechanism on HFD-induced anxiety-related behavior remains not clear. The mice were divided into 4 groups, Control (Con), Alcohol (Alc), HFD and HFD + Alc groups. To verify the effects of low-dose alcohol on HFD-induced anxiety-related behavior, the mice were fed with HFD for 16 weeks. At the beginning of week 13, the HFD-fed mice were administered intragastrically with low-dose alcohol (0.8 g kg^-1) for 4 weeks. After 4 weeks of oral administration, low-dose alcohol decreased body weight and Lee's index in HFD-induced obese mice. Moreover, low-dose alcohol alleviated the anxiety-related behaviors of obese mice in the open field test and the elevated plus maze test. The HFD-induced damage to the hippocampus was improved in hematoxylin-eosin staining assay in mice. In addition, low-dose alcohol also suppressed HFD-induced oxidative stress and increased HFD-suppressed adiponectin (APN) expression and nuclear factor erythroid 2-related factor 2 (Nrf2) activation in the hippocampus. Taken together, low-dose alcohol significantly ameliorates HFD-induced obesity, oxidative stress and anxiety-related behavior in mice, which might be related to APN upregulation, Nrf2 activation and related antioxidase expression including SOD1, HO-1, and catalase.

Filling the gaps on stroke research: Focus on inflammation and immunity

For the last two decades, researchers have placed hopes in a new era in which a combination of reperfusion and neuroprotection would revolutionize the treatment of stroke. Nevertheless, despite the thousands of papers available in the literature showing positive results in preclinical stroke models, randomized clinical trials have failed to show efficacy. It seems clear now that the existing data obtained in preclinical research have depicted an incomplete picture of stroke pathophysiology. In order to ameliorate bench-to-bed translation, in this review we first describe the main actors on stroke inflammatory and immune responses based on the available preclinical data, highlighting the fact that the link between leukocyte infiltration, lesion volume and neurological outcome remains unclear. We then describe what is known on neuroinflammation and immune responses in stroke patients, and summarize the results of the clinical trials on immunomodulatory drugs. In order to understand the gap between clinical trials and preclinical results on stroke, we discuss in detail the experimental results that served as the basis for the summarized clinical trials on immunomodulatory drugs, focusing on (i) experimental stroke models, (ii) the timing and selection of outcome measuring, (iii) alternative entry routes for leukocytes into the ischemic region, and (iv) factors affecting stroke outcome such as gender differences, ageing, comorbidities like hypertension and diabetes, obesity, tobacco, alcohol consumption and previous infections like Covid-19. We can do better for stroke treatment, especially when targeting inflammation following stroke. We need to re-think the design of stroke experimental setups, notably by (i) using clinically relevant models of stroke, (ii) including both radiological and neurological outcomes, (iii) performing long-term follow-up studies, (iv) conducting large-scale preclinical stroke trials, and (v) including stroke comorbidities in preclinical research.

Ischemic stroke with a preceding Trans ischemic attack (TIA) less than 24 hours and thrombolytic therapy

Background

Acute ischemic stroke attack with and without a recent TIA may differ in clinical risk factors, and this may affect treatment outcomes following thrombolytic therapy. We examined whether the odds of exclusion or inclusion for thrombolytic therapy are greater in ischemic stroke with TIA less than 24 h preceding ischemic stroke (recent-TIA) as compared to those without recent TIA or non-TIA > 24 h and less than 1 month (past-TIA).

Methods

A retrospective hospital-based analysis was conducted on 6315 ischemic stroke patients, of whom 846 had proven brain diffusion-weighted magnetic resonance imaging (DW-MRI) of an antecedent TIA within 24 h prior to ischemic stroke. The logistic regression model was developed to generate odds ratios (OR) to determine clinical factors that may increase the likelihood of exclusion or inclusion for thrombolytic therapy. The validity of the model was tested using a Hosmer-Lemeshow test, while the Receiver Operating Curve (ROC) was used to test the sensitivity of our model.

Results

In the recent-TIA ischemic stroke population, patients with a history of alcohol abuse (OR = 5.525, 95% CI, 1.003–30.434, p = 0.05), migraine (OR = 4.277, 95% CI, 1.095–16.703, p = 0.037), and increasing NIHSS score (OR = 1.156, 95% CI, 1.058–1.263, p = 0.001) were associated with the increasing odds of receiving rtPA, while older patients (OR = 0.965, 95% CI, 0.934–0.997, P = 0.033) were associated with the increasing odds of not receiving rtPA.

Conclusion

In recent-TIA ischemic stroke patients, older patients with higher INR values are associated with increasing odds of exclusion from thrombolytic therapy. Our findings demonstrate clinical risks factors that can be targeted to improve the use and eligibility for rtPA in in recent-TIA ischemic stroke patients.

Acute Alcohol Intoxication With Accompanying Neurovascular Decline in Young Adults: A Sobering Case Series

With an increase in both popularity and incidence, young adults continue to consume increasing amounts of ethanol-containing beverages at alarmingly short intervals, at times, far surpassing the threshold of binge drinking. From mixed beverages to party delights, high-concentration ethanol consumption continues to wreak havoc on the health of the younger generation. In this dual case series, we discuss two unique cases of alcohol-induced neurovascular compromise following episodes of high-volume ethanol consumption and acute neurovascular decline with varying outcomes. These cases highlight the hyperacute onset of severe pathology and the dire need for immediate medical intervention. While outcomes vary from case to case, our findings are congruent with those of vast medical literature that supports the consensus that immediate intervention to restore neurovascular flow is crucial for desired outcomes. At the end of the day, we cannot control the amount of alcohol that enters the mouths of our patients, but rather, we can educate them on safer practices while highlighting the risk and life-changing consequences of such risky behavior.

Influence of Chronic Ethanol Consumption on Apoptosis and Autophagy Following Transient Focal Cerebral Ischemia in Male Mice

Stroke remains one of the leading causes of permanent disability and death worldwide. Apoptosis and autophagy are two key elements involved in ischemic brain damage. Ethanol is a commonly used and abused chemical substance that affects the prognosis of ischemic stroke. We determined the influence of chronic ethanol consumption on apoptosis and autophagy following transient focal cerebral ischemia. Male C57BL/6 J mice were randomly divided into three groups and gavage fed with 0.7 and 2.8 g/kg/day ethanol or volume-matched water daily for 8 weeks. DNA fragmentation, TUNEL-positive neurons, cleaved caspase-3-positive neurons, translocation of mitochondrial cytochrome C and apoptosis inducing factor (AIF), LC3B-positive neurons, and expression of LC3B, Beclin-1 and Bcl-2 in peri-infarct cortex were evaluated at 24 hours of reperfusion after a 90-minute unilateral middle cerebral artery occlusion (MCAO). Cerebral ischemia/reperfusion (I/R) injury was significantly improved in the 0.7 g/kg/d ethanol group but worsened in the 2.8 g/kg/d ethanol group. DNA fragmentation was significantly increased at 24 hours of reperfusion in all groups. However, the magnitude of the increase was significantly less in the 0.7 g/kg/d ethanol group. In addition, both cleaved caspase-3-positive neurons and TUNEL-positive neurons were significantly less in 0.7 g/kg/d ethanol group. Furthermore, translocation of mitochondrial cytochrome C and AIF was significantly alleviated in the 0.7 g/kg/d ethanol group. On the other hand, baseline expression of LC3B was significantly reduced in the 2.8 g/kg/d ethanol group. Post-ischemic expression of LC3B and LC3B-positive neurons were significantly attenuated in both 0.7 and 2.8 g/kg/d ethanol groups. Moreover, although post-ischemic expression of Beclin-1 was not altered in the ethanol groups, post-ischemic expression of Bcl-2 was significantly greater in both 0.7 and 2.8 g/kg/d ethanol groups. Our findings suggest that light ethanol consumption may protect against cerebral I/R injury by suppressing post-ischemic apoptosis, whereas heavy ethanol consumption may exacerbate cerebral I/R injury by suppressing autophagy.

MicroRNA-126-3p/-5p Overexpression Attenuates Blood-Brain Barrier Disruption in a Mouse Model of Middle Cerebral Artery Occlusion

Background and Purpose—

Blood-brain barrier (BBB) disruption is a critical pathological feature after stroke. MicroRNA-126 (miR-126) maintains BBB integrity by regulating endothelial cell function during development. However, the role of miR-126-3p and -5p in BBB integrity after stroke is unclear. Here, we investigated whether miR-126-3p and -5p overexpression regulates BBB integrity after cerebral ischemia.

Methods—

A lentivirus carrying genes encoding miR-126-3p or -5p was stereotactically injected into adult male Institute of Cancer Research mouse brains (n=36). Permanent middle cerebral artery occlusion was performed 2 weeks after virus injection. Brain infarct volume, edema volume, and modified neurological severity score were assessed at 1 and 3 days after ischemia. Immunostaining of ZO-1 (zonula occludens-1) and occludin was used to evaluate BBB integrity. IL-1β (interleukin-1β), TNF-α (tumor necrosis factor-α), VCAM-1 (vascular cell adhesion molecule-1), and E-selectin expression levels were determined by real-time polymerase chain reaction and Western blot analysis.

Results—

The expression of miR-126-3p and -5p decreased at 1 and 3 days after ischemia ( P <0.05). Injection of lentiviral miR-126-3p or -5p reduced brain infarct volume and edema volume ( P <0.05) and attenuated the decrease in ZO-1/occludin protein levels and IgG leakage at 3 days after stroke ( P <0.05). Injection of lentiviral miR-126-5p improved behavioral outcomes at 3 days after stroke ( P <0.05). miR-126-3p and -5p overexpression downregulated the expression of proinflammatory cytokines IL-1β and TNF-α and adhesion molecules VCAM-1 and E-selectin, as well as decreased MPO + (myeloperoxidase positive) cell numbers at 3 days after ischemia ( P <0.05).

Conclusions—

miR-126-3p and -5p overexpression reduced the expression of proinflammatory cytokines and adhesion molecules, and attenuated BBB disruption after ischemic stroke, suggesting that miR-126-3p and -5p are new therapeutic targets in the acute stage of stroke.

Low-dose alcohol ameliorated homocysteine-induced anxiety-related behavior via attenuating oxidative stress in mice

Recent studies showed that homocysteine (Hcy) levels were obviously elevated in patients with anxiety, furthermore, oxidative stress and inflammation were closely linked with Hcy-related damage. Despite alcohol exposure has differential effects on different forms of anxiety, the role of alcohol on anxiety-related behavior induced by high Hcy levels is still not entirely clear. The present study investigated the protective potential of low-dose alcohol against homocysteine-induced anxiety-related behavior and explored the possible underlying mechanisms. Mice were administered intragastrically with methionine (2.0 g/kg/day) or alcohol (0.6 g/kg/day). After 21 days of administration, the anxiety-related behavior was evaluated through open field (OF) and elevated plus maze (EPM) tests, and the variations of oxidative stress and inflammation levels were measured. The results of OF and EPM tests showed that the anxiety-related behavior in mice was prevented by alcohol treatment. Alcohol lowered the elevated serum Hcy levels and alleviated the damage of hippocampal tissues in hyperhomocysteinemia (HHcy) mice. Meanwhile, the superoxide dismutase (SOD) activity of the hippocampal tissues enhanced, and the malondialdehyde (MDA) concentration of the hippocampal tissues and the serum interleukin-1β (IL-1β) level decreased. In addition, after administering alcohol, the increase of superoxide dismutase 1 (SOD1), heme oxygenase 1 (HO-1) protein expression and the decrease of IL-1β protein expression were also detected in HHcy mice hippocampal tissues. Taken together, low-dose alcohol significantly ameliorated the Hcy-induced anxiety-related behavior in mice, which might be related to SOD1 and HO-1 upregulation and IL-1β downregulation.

TMEM16A Inhibition Preserves Blood-Brain Barrier Integrity After Ischemic Stroke

The inflammatory response plays a pivotal role in Blood–Brain Barrier (BBB) destruction following ischemic brain injury. Enhanced leukocyte adhesion to vascular endothelial cells is an essential event in the inflammatory process. TMEM16A, a newly discovered protein regulating calcium-activated chloride channels, is widely expressed in eukaryotes. Recent studies have suggested that upregulated expression of TMEM16A is associated with the occurrence and development of many diseases. However, the role of TMEM16A in regulating BBB integrity after ischemic stroke has not been fully investigated. In this study, we found that TMEM16A is mainly expressed in brain endothelial cells and upregulated after ischemic stroke in the mouse brain. Caccinh-A01, an TMEM16A inhibitor that reduced its upregulation, attenuated brain infarct size and neurological deficits after ischemic stroke. ICAM-1 and MPO expression and BBB permeability were decreased after TMEM16A inhibitor administration. In addition, TMEM16A silencing rescued oxygen-glucose deprivation/reoxygenation (OGD/R)-induced transendothelial permeability in vitro accompanied by decreased ICAM-1 expression and leukocyte adhesion. Furthermore, our mechanistic study showed that TMEM16A knockdown alleviated NF-κB activation and nuclear translocation, indicating that TMEM16A knockdown downregulated OGD/R-induced ICAM-1 expression in an NF-κB-dependent manner. Finally, NF-κB inhibitor treatment also alleviated OGD/ R-induced BBB permeability, confirming that activated NF-κB and increased ICAM-1 are essential factors involved in ischemia-induced BBB damage. Thus, our research provides a promising treatment strategy against BBB destruction after ischemic stroke, and TMEM16A may become a potential target for the treatment of ischemic stroke.

[Glucosides of chaenomeles speciosa attenuate ischemia/reperfusion-induced brain injury by regulating NF-κB P65/TNF-α in mouse model]

OBJECTIVE

To investigate the effect and mechanism of glucosides of chaenomeles speciosa (GCS) on ischemia/reperfusion-induced brain injury in mouse model.

METHODS

Fifty 8-week C57BL/C mice were randomly divided into five groups with 10 in each group:sham group, model group, GCS 30 mg/kg group, GCS 60 mg/kg group and GCS 90 mg/kg group, and the GCS was administrated by gavage (once a day) for 14 d. HE staining was performed to investigate the cell morphology; the Zea-Longa scores were measured for neurological activity; TUNEL staining was performed to investigate the cell apoptosis; ELISA was used to detected the oxidative stress and inflammation; Western Blot was performed to investigate the key pathway and neurological functional molecules.

RESULTS

Compared with the sham group, the brain tissues in model group were seriously damaged, presenting severe cell apoptosis, oxidative stress and inflammation, associated with increased NF-κB P65 and TNF-α levels as well as decreased myelin associate glycoprotein (MAG) and oligodendrocyte-myelin glycoprotein (OMgp)levels (all P<0.01). Compared with the model group, the brain tissues in GCS groups were ameliorated, and cell apoptosis, oxidative stress and inflammation were inhibited, associated with decreased NF-κB P65 and TNF-α levels as well as increased MAG and OMgp levels (all P<0.01), which were more markedly in GCS 60 mg/kg group.

CONCLUSIONS

GCS can inhibit the NF-κB P65 and TNF-α, reduce the oxidative stress and inflammation, decrease the cell apoptosis in mouse ischemia/reperfusion-induced brain injury model, and 60 mg/kg GCS may be the optimal dose.