Ischemic stroke across sexes: What is the status quo?

Inflammation-Driven Plaque Erosion in Atherosclerosis: A Focus on Complement System Pathways

PURPOSE OF REVIEW

Complement system activation is implicated in various stages of atherogenesis, from fatty streak formation to plaque destabilization and thrombus formation, with its dreadful clinical sequelae such as myocardial infarction, stroke and premature death. In this review, we consider these issues and explore recent studies on complement activation in atherosclerotic plaque initiation and progression.

RECENT FINDINGS

Complement pathways impact plaque stability and healing through the modulation of inflammatory processes. Recent studies indicate that complement components, notably C3 and C5b-9, accelerate atherosclerosis progression through their interactions with endothelial cells, smooth muscle cells, and immune cells. Nonetheless, the beneficial versus deleterious effects of complement activation at different stages of atherogenesis remains a matter of ongoing debates. Research also investigates therapies targeting the complement cascade to mitigate plaque erosion and rupture. This review explores the ongoing debates surrounding complement activation in atherogenesis. We bring forward controversial findings and therapeutic strategies aimed at modulating complement cascade activation with the ultimate goal to reduce the burden of atherosclerotic cardiovascular disease.\.

Effect and mechanism of Dichloroacetate in the treatment of stroke and the resolution strategy for side effect

Stroke is a serious disease that leads to high morbidity and mortality, and ischemic stroke accounts for more than 80% of strokes. At present, the only effective drug recombinant tissue plasminogen activator is limited by its indications, and its clinical application rate is not high. Therefore, it is urgent to develop effective new drugs according to the pathological mechanism. In the hypoxic state after ischemic stroke, anaerobic glycolysis has become the main way to provide energy to the brain. This process is essential for the maintenance of important brain functions and has important implications for recovery after stroke. However, acidosis caused by anaerobic glycolysis and lactic acid accumulation is an important pathological process after ischemic stroke. Dichloroacetate (DCA) is an orphan drug that has been used for decades to treat children with genetic mitochondrial diseases. Some studies have confirmed the role of DCA in stroke, but the conclusions are conflicting because some believe that DCA is not effective for ischemic stroke and may aggravate hemorrhagic stroke. This study reviews these studies and finds that DCA has a good effect on ischemic stroke. DCA can protect ischemic stroke by improving oxidative stress, reducing neuroinflammation, inhibiting apoptosis, protecting blood-brain barrier, and regulating metabolism. We also describe the differences in the outcomes of DCA in the treatment of ischemic stroke and the reasons why DCA aggravate hemorrhagic stroke. In addition, DCA, as a water disinfection byproduct, has been concerned about its toxicity. We describe the causes and solutions of peripheral neuropathy caused by DCA. In summary, this study analyzes the neuroprotective mechanism of DCA in ischemic stroke and the contradiction of the different research results, and discusses the causes and solutions of its adverse effects.

Therapeutic Effects of Coenzyme Q10 in the Treatment of Ischemic Stroke

PURPOSE OF REVIEW

Ischemic stroke is the second deadly disease worldwide, but current treatment is very limited. The brain, rich in lipids and high in oxygen consumption, is susceptible to damage from oxidative stress after ischemic stroke. Thus, antioxidants are promising neuroprotective agents for treatment and prevention of ischemic stroke. Coenzyme Q10 is the only lipophilic antioxidant that can be synthesized de novo by cells and plays a key role as an electron carrier in the oxidative phosphorylation of the mitochondrial electron transport chain. However, the reduced form of coenzyme Q10 (Ubiquinol) levels are significantly deficient in the brain. The aim of this article is to review the therapeutic effects and mechanisms of coenzyme Q10 in ischemic stroke.

RECENT FINDINGS

Current studies have found that coenzyme Q10 protects and treats ischemic stroke through multiple mechanisms based on the evidence from in vitro experiments, in vivo experiments, and clinical observations. For the first time, we reviewed the neuroprotective effects of coenzyme Q10 in ischemic stroke. Coenzyme Q10 exerts neuroprotective effects after ischemic stroke through anti-oxidative stress, anti-nitrosative stress, anti-inflammation, and anti-cell death. Here, we provided the evidence on the therapeutic and preventive effects of coenzyme Q10 in ischemic stroke and suggested the potential value of coenzyme Q10 as a medication candidate.

Association of triglyceride glucose index with clinical outcomes in ischemic stroke: a retrospective study

BACKGROUND

Stroke is a major cause of illness, death, and long-term disability and a major health concern worldwide. Experts consider insulin resistance (IR), a defining feature of the metabolic syndrome and a significant risk factor for stroke. Insulin resistance, or IR, is common among stroke patients. The triglyceride-glucose (TYG) index's relevance to both lipotoxicity and glucotoxicity has led to its proposal as an alternative indicator of IR.

AIM

Examining the connection between elevated TYG INDEX scores and worse clinical outcomes in ischemic stroke patients is the main goal. Finding out how often bad outcomes (recurrence and all-cause death) are in ischemic stroke patients is the secondary goal.

METHOD

This was a retrospective observational study that involved patients admitted to the 850-bed Dr. Pinnamaneni Siddhartha Institute of Medical Sciences and Research Foundation, a tertiary care teaching hospital located in the Krishna district of Andhra Pradesh (India). The study was conducted over a period of six months. All the 95 patients who satisfied the eligibility criteria were included. The patients' TYG INDEX values were first determined and patients with ischemic stroke who had elevated TYG INDEX values were then compared for clinical outcomes including recurrence and all-cause death with ischemic patients with normal TYG INDEX.

RESULTS

In this study, the total cholesterol of the patients (mean ± SD) was 165.01 ± 51.5 mg/dL; Triglycerides was 157.031 ± 98.9 mg/dL; HDL-c was 37.253 ± 5.52 mg/dl; LDL-c was 107 ± 48.3 mg/Dl; and FBS was 153.74 ± 71.52 mg/dL. The chi-square test showed that only FBS, Triglyceride, and Total cholesterol were significantly associated with TYG INDEX whereas other variables like age, LDL, and HDL were not. There was no significant association between the TYG INDEX and clinical outcomes of ischemic stroke. In both groups of patients, risk and no risk TYG INDEX values, the mRS score showed variable and unpredictable relationship with the TYG INDEX.

CONCLUSION

Contrary to the few studies that discovered one, our research leads us to the conclusion that there may not be a relevant association between the TYG INDEX and clinical results in patients with ischemic stroke.

Identification and Validation of Active Ingredient in Cerebrotein Hydrolysate-I Based on Pharmacokinetic and Pharmacodynamic Studies

Cerebrotein hydrolysate-1 (CH-1), a mixture of small peptides, polypeptides, and various amino acids derived from porcine brain, has been widely used in the treatment of cerebral injury. However, the bioactive composition and pharmacokinetics of CH-1 are still unexplored because of their complicated composition and relatively tiny amounts in vivo. Herein, NanoLC Orbitrap Fusion Lumos Tribrid Mass Spectrometer was firstly used to qualitatively analyze the components of CH-1. A total of 1347 peptides were identified, of which 43 peptides were characterized by high mass spectrometry (MS) intensity and identification accuracy. We then innovatively synthesized four main peptides for activity verification, and the results suggested that Pep72 (NYEPPTVVPGGDL) had the strongest neuroprotective effect on both in vivo and in vitro models. Next, a quantitative method for Pep72 was established based on liquid chromatography tandem mass spectrometry (LC-MS/MS) with the aid of Skyline software and then used in its pharmacokinetic studies. The results revealed that Pep72 had a high elimination rate and low exposure in rats. In addition, a hCMEC/D3-based in vitro model was built and firstly used to investigate the transport of Pep72. We found that Pep72 had extremely low blood-brain barrier permeability and was not a substrate of efflux transporters. The biotransformation of Pep72 in rat fresh plasma and tissues was investigated to explore the contradiction between pharmacokinetics and efficacy. A total of 11 main metabolites were structurally identified, with PGGDL and EPPTVPGGDL being the main metabolites of Pep72. Notably, metalloproteinase and cysteine protease were confirmed to be the main enzymes mediating Pep72 metabolism in rat tissues. SIGNIFICANCE STATEMENT: The NanoLC Orbitrap Fusion Lumos Tribrid Mass Spectrometer was firstly applied to discover the components of CH-1, and one main peptide Pep72 (NYEPPTVVPGGDL) was innovatively synthesized and firstly found to have the strongest neuroprotective effect among 1347 peptides identified from CH-1. Our study is the first time to identify and verify the active ingredient of CH-1 from the perspective of pharmacokinetics and pharmacodynamics, and provides a systematic technical platforms and strategies for the active substance research of other protein hydrolysates.

Sex and gender considerations in Alzheimer’s disease: The Women’s Brain Project contribution

The global population is expected to have about 131.5 million people living with Alzheimer’s disease (AD) and other dementias by 2050, posing a severe health crisis. Dementia is a progressive neurodegenerative condition that gradually impairs physical and cognitive functions. Dementia has a variety of causes, symptoms, and heterogeneity concerning the influence of sex on prevalence, risk factors, and outcomes. The proportion of male-to-female prevalence varies based on the type of dementia. Despite some types of dementia being more common in men, women have a greater lifetime risk of developing dementia. AD is the most common form of dementia in which approximately two-thirds of the affected persons are women. Profound sex and gender differences in physiology and pharmacokinetic and pharmacodynamic interactions have increasingly been identified. As a result, new approaches to dementia diagnosis, care, and patient journeys should be considered. In the heart of a rapidly aging worldwide population, the Women’s Brain Project (WBP) was born from the necessity to address the sex and gender gap in AD. WBP is now a well-established international non-profit organization with a global multidisciplinary team of experts studying sex and gender determinants in the brain and mental health. WBP works with different stakeholders worldwide to help change perceptions and reduce sex biases in clinical and preclinical research and policy frameworks. With its strong female leadership, WBP is an example of the importance of female professionals’ work in the field of dementia research. WBP-led peer-reviewed papers, articles, books, lectures, and various initiatives in the policy and advocacy space have profoundly impacted the community and driven global discussion. WBP is now in the initial phases of establishing the world’s first Sex and Gender Precision Medicine Institute. This review highlights the contributions of the WBP team to the field of AD. This review aims to increase awareness of potentially important aspects of basic science, clinical outcomes, digital health, policy framework and provide the research community with potential challenges and research suggestions to leverage sex and gender differences. Finally, at the end of the review, we briefly touch upon our progress and contribution toward sex and gender inclusion beyond Alzheimer’s disease.

Interventional strategies for ischemic stroke based on the modulation of the gut microbiota

The microbiota-gut-brain axis connects the brain and the gut in a bidirectional manner. The organism's homeostasis is disrupted during an ischemic stroke (IS). Cerebral ischemia affects the intestinal flora and microbiota metabolites. Microbiome dysbiosis, on the other hand, exacerbates the severity of IS outcomes by inducing systemic inflammation. Some studies have recently provided novel insights into the pathogenesis, efficacy, prognosis, and treatment-related adverse events of the gut microbiome in IS. In this review, we discussed the view that the gut microbiome is of clinical value in personalized therapeutic regimens for IS. Based on recent non-clinical and clinical studies on stroke, we discussed new therapeutic strategies that might be developed by modulating gut bacterial flora. These strategies include dietary intervention, fecal microbiota transplantation, probiotics, antibiotics, traditional Chinese medication, and gut-derived stem cell transplantation. Although the gut microbiota-targeted intervention is optimistic, some issues need to be addressed before clinical translation. These issues include a deeper understanding of the potential underlying mechanisms, conducting larger longitudinal cohort studies on the gut microbiome and host responses with multiple layers of data, developing standardized protocols for conducting and reporting clinical analyses, and performing a clinical assessment of multiple large-scale IS cohorts. In this review, we presented certain opportunities and challenges that might be considered for developing effective strategies by manipulating the gut microbiome to improve the treatment and prevention of ischemic stroke.

PRMT8 Attenuates Cerebral Ischemia/Reperfusion Injury via Modulating Microglia Activation and Polarization to Suppress Neuroinflammation by Upregulating Lin28a

Activation and polarization of microglia are involved in neuroinflammation and regulate ischemic stroke-associated brain injury. Protein arginine methyltransferase 8 functions as a regulatory component of hypoxic stress-induced neuroinflammation. The protective effect of protein arginine methyltransferase 8 (PRMT8) against ischemic stroke-associated brain injury through regulation of microglia activation and polarization was investigated. First, PRMT8 was downregulated in middle cerebral artery occlusion (MCAO)-induced mice and oxygen-glucose deprivation/reoxygenation (OGD/R)-induced SH-SY5Y. Injection with AAV-PRMT8 reduced infarct volumes in MCAO-induced mice. Moreover, injection with AAV-PRMT8 promoted neuronal survival and ameliorated histopathological changes in the brains of MCAO-induced mice. The neuronal apoptosis and neuroinflammation in MCAO-induced mice were suppressed by AAV-PRMT8 injection. Second, PRMT8 overexpression increased cell viability and suppressed the cell apoptosis and inflammation of OGD/R-induced SH-SY5Y. Third, injection with AAV-PRMT8 reduced almost 50% of CD86 + M1 microglia and enhanced about 20% of CD206 + M2 microglia. Furthermore, PRMT8 overexpression attenuated OGD/R-induced M1 phenotype polarization of BV2. Lastly, PRMT8 upregulated Lin28a and loss of Lin28a attenuated PRMT8 overexpression-induced increase in cell viability and decrease in cell apoptosis and inflammation of OGD/R-induced SH-SY5Y. In conclusion, PRMT8 promoted M2 phenotype polarization of microglia and suppressed neuronal apoptosis to ameliorate cerebral ischemia/reperfusion injury through upregulation of Lin28a.

CERKL alleviates ischemia reperfusion-induced nervous system injury through modulating the SIRT1/PINK1/Parkin pathway and mitophagy induction

Recent studies showed that Ceramide Kinase-Like Protein (CERKL)was expressed in the nerve cells and could regulate autophagy. Sirtuin-1 (SIRT1) is the regulator of the mitophagy, which can be stabilized by CERKL. Furthermore, the study also revealed that the SIRT1 induced mitophagy by activating PINK1/Parkin signaling. Therefore, we speculated that CERKL has potential to activate the SIRT1/PINK1/Parkin pathway to induce mitophagy. In this study, cerebral ischemia reperfusion mouse model was established. CERKL was overexpressed in those mice and human neuroblastoma cells. Tunel staining and flow cytometry were applied for the detection of cell apoptosis. The ratios of LC3Ⅱ to LC3Ⅰ and the expression of LC3Ⅱ in mitochondria were determined by gel electrophoresis. Overexpression of CERKL alleviated the cerebral ischemia reperfusion injury and damage to OGD/R human neuroblastoma cells. Overexpression of CERKL enhanced the expression of LC3 Ⅱ in mitochondria and induced occurrence of mitophagy. Overexpression of CERKL promoted the stability of SIRT1 and facilitated the expression of PINK1 and Parkin in those cells. Knockdown of PINK1 impeded the mitophagy and suppressed the expression of LC3 Ⅱ in mitochondria. It can be concluded that CERKL alleviated the ischemia reperfusion induced nervous system injury through inducing mitophagy in a SIRT1/PINK1/Parkin dependent pathway.

Heart-brain interactions in cardiac and brain diseases: why sex matters

Cardiovascular disease and brain disorders, such as depression and cognitive dysfunction, are highly prevalent conditions and are among the leading causes limiting patient's quality of life. A growing body of evidence has shown an intimate crosstalk between the heart and the brain, resulting from a complex network of several physiological and neurohumoral circuits. From a pathophysiological perspective, both organs share common risk factors, such as hypertension, diabetes, smoking or dyslipidaemia, and are similarly affected by systemic inflammation, atherosclerosis, and dysfunction of the neuroendocrine system. In addition, there is an increasing awareness that physiological interactions between the two organs play important roles in potentiating disease and that sex- and gender-related differences modify those interactions between the heart and the brain over the entire lifespan. The present review summarizes contemporary evidence of the effect of sex on heart-brain interactions and how these influence pathogenesis, clinical manifestation, and treatment responses of specific heart and brain diseases.

|Therapeutic and preventive effects of apigenin in cerebral ischemia: a review

APG can exert various protective effects against cerebral ischemia. Moreover, APG has shown a highly promising ability to prevent cerebral ischemia in terms of regulating blood glucose, blood pressure, lipids and gut microbes.

TNF-α antagonism rescues the effect of ageing on stroke: Perspectives for targeting inflamm-ageing

AIMS

Epidemiologic evidence links ischemic stroke to age, yet the mechanisms that underlie the specific and independent effects of age on stroke remain elusive, impeding the development of targeted treatments. This study tested the hypothesis that age directly aggravates stroke outcomes and proposes inflamm-aging as a mediator and potential therapeutic target.

METHODS

3 months- (young) and 18-20 months-old (old) mice underwent transient middle cerebral artery occlusion (tMCAO) for 30 minutes followed by 48 hours of reperfusion. Old animals received weekly treatment with the TNF-α neutralizing antibody adalimumab over 4 weeks before tMCAO in a separate set of experiments. Plasma levels of TNF- α were assessed in patients with ischemic stroke and correlated with age and outcome.

RESULTS

Old mice displayed larger stroke size than young ones with increased neuromotor deficit. Immunohistochemical analysis revealed impairment of the blood-brain barrier in old mice, i.e. increased post-stroke degradation of endothelial tight junctions and expression of tight junctions-digesting and neurotoxic matrix metalloproteinases. At baseline, old animals showed a broad modulation of several circulating inflammatory mediators. TNF-α displayed the highest increase in old animals and its inhibition restored the volume of stroke, neuromotor performance, and survival rates of old mice to the levels observed in young ones. Patients with ischemic stroke showed increased TNF-α plasma levels which correlated with worsened short-term neurological outcome as well as with age.

CONCLUSIONS

This study identifies TNF-α as a causative contributor to the deleterious effect of aging on stroke and points to inflamm-aging as a mechanism of age-related worsening of stroke outcomes and potential therapeutic target in this context. Thus, this work provides a basis for tailoring novel stroke therapies for the particularly vulnerable elderly population.

CSE-Derived H2S Inhibits Reactive Astrocytes Proliferation and Promotes Neural Functional Recovery after Cerebral Ischemia/Reperfusion Injury in Mice Via Inhibition of RhoA/ROCK2 Pathway

The effect of cystathionine-γ-lyase (CSE)-derived hydrogen sulfide (H₂S) on the reactive proliferation of astrocytes and neural functional recovery over 30 d after acute cerebral ischemia and reperfusion (I/R) was determined by applying wild-type (WT) and CSE knockout (KO) mice. The changes of glial fibrillary acidic protein (GFAP) expression in hippocampal tissues was tested. Besides, we assessed the changes of mice spatial learning memory ability, neuronal damage, RhoA, Rho kinase 2 (ROCK₂), and myelin basic protein (MBP) expressions in hippocampal tissues. The results revealed that cerebral I/R resulted in obvious increase of GFAP expression in hippocampal tissues. Besides, we found the neuronal damage, learning, and memory deficits of mice induced by cerebral I/R as well as revealed the upregulation of RhoA and ROCK₂ expressions and reduced MBP expression in hipppcampal tissues of mice following cerebral I/R. Not surprisingly, the GFAP expression and cerebral injury as well as the upregulation of the RhoA/ROCK₂ pathway were more remarkable in CSE KO mice, compared with those in WT mice over 30 d following acute cerebral I/R, which could be blocked by NaHS treatment, a donor of exogenous H₂S. In addition, the ROCK inhibitor Fasudil also inhibited the reactive proliferation of astrocytes and ameliorated the recovery of neuronal function over 30 d after cerebral I/R. For the purpose of further confirmation of the role of H₂S on the astrocytes proliferation following cerebral I/R, the immunofluorescence double staining: bromodeoxyuridine (BrdU) and GFAP was evaluated. There was a marked upregulation of BrdU-labeled cells coexpressed with GFAP in hippocampal tissues at 30 d after acute cerebral I/R; however, the increment of astrocytes proliferation could be ameliorated by both NaHS and Fasudil. These findings indicated that CSE-derived H₂S could inhibit the reactive proliferation of astrocytes and promote the recovery of mice neural functional deficits induced by a cerebral I/R injury via inhibition of the RhoA/ROCK₂ signal pathway.

Long-term dietary supplementation with plant-derived omega-3 fatty acid improves outcome in experimental ischemic stroke

BACKGROUND AND AIMS

Early revascularization -the gold standard therapy for ischemic stroke- is often withheld in the elderly population due to high risk of complications. Thus, safe and effective preventive and therapeutic options are needed. The plant-derived omega-3-fatty-acid alpha-linolenic-acid (ALA) has emerged as a novel cardiovascular-protective agent. As of yet, little is known about its potential therapeutic effects on stroke. We hereby aimed to investigate the impact of a clinically relevant long-term dietary intervention with ALA on stroke outcome.

METHODS

Six month-old C57BL/6 wildtype males were either fed an ALA-rich (high ALA) or a control diet (low ALA) for 12 months. At 18 months, brain ischemia/reperfusion was induced by transient middle cerebral artery occlusion (tMCAO). Stroke size and neurological function were assessed. Functional blood-brain-barrier-(BBB) permeability and protein expression were assessed by immunohistochemistry. Baseline inflammatory markers were measured at 18 months.

RESULTS

High ALA-fed animals displayed decreased circulating TNF-α levels and Neutrophil-to-Lymphocyte Ratios at 18 months. Stroke size and neurological dysfunction were significantly reduced in high ALA-fed animals. Coherently to the reduced stroke size, functional BBB integrity and occludin endothelial expression were maintained by high ALA supplementation. Additionally, ALA reduced endothelial activation and thus recruitment and activation of macrophages and resident microglia. Finally, high ALA diet reduced the expression of BBB-degrading and neurotoxic MMP-3 and MMP-9.

CONCLUSIONS

We demonstrate the beneficial effects of a clinically relevant and feasible dietary intervention with a safe and readily available compound in the setting of stroke. The protective effects observed with ALA supplementation may relate to blunting of inflammation and might pave the way for novel stroke treatments.

Isoflurane post-conditioning contributes to anti-apoptotic effect after cerebral ischaemia in rats through the ERK5/MEF2D signaling pathway

The mechanisms of brain protection during ischaemic reperfusion injury induced by isoflurane (ISO) post‐conditioning are unclear. Myocyte enhancement factor 2 (MEF2D) has been shown to promote neural survival in a variety of models, in which multiple survival and death signals converge on MEF2D and modulate its activity. Here, we investigated the effect of MEF2D on the neuroprotective effects of ISO post‐conditioning on rats after cerebral ischaemia/reperfusion (I/R) injury. Rats underwent middle cerebral artery occlusion (MCAO) surgery with ischaemia for 90 minutes and reperfusion for 24‐48 hours. After MCAO, neurological status was assessed at 12, 24 and 48 hours by the Modified Neurological Severity Score (mNSS) test. The passive avoidance test (PAT) was used to assess cognition function. Histological and neuropathological evaluations were performed with HE staining and Nissl's staining, respectively. We measured the expression of MEF2D, ERK5, GFAP and caspase‐3 by immunofluorescent staining and Western blotting, and TUNEL staining to assess the severity of apoptosis in hippocampal CA1 area. We found that MEF2D was involved in nerve protection after I/R injury, and post‐treatment of ISO significantly promoted the phosphorylation of ERK5, increased MEF2D transcriptional activity, inhibited the expression of caspase‐3 and played a role of brain protection.

Knockdown of Arginyl-tRNA Synthetase Attenuates Ischemia-Induced Cerebral Cortex Injury in Rats After Middle Cerebral Artery Occlusion

Some researchers have previously shown that RNAi knockdown of arginyl-tRNA synthetase (ArgRS) before or after a hypoxic injury can rescue animals from death, based on the model organism, C. elegans. However, there has been no study on the application of arginyl-tRNA synthetase knockdown in treating mammalian ischemic stroke, and its potential mechanism and effect on ischemic brain damage are still unknown. Here, we focused on the Rars gene, which encodes an arginyl-tRNA synthetase, and examined the effects of Rars knockdown in a permanent middle cerebral artery occlusion model in rats. To achieve this aim, adult male Sprague-Dawley (SD) rats were given right cerebral cortex injections of short hairpin RNA (shRNA) adenovirus (AV) particles to knock down arginyl-tRNA synthetase, and a non-targeting control (NTC) vector or phosphate-buffered solution served as the controls. After 4 days, the rats were exposed to permanent middle cerebral artery occlusion (pMCAO). Then, the right cerebral cortex level of arginyl-tRNA synthetase was examined, and the effects of the Rars knockdown were evaluated by differences in infarction volume, oxidative stress, blood-brain barrier, mitochondrial function, and glucose metabolism at 1 day and 3 days after MCAO. The injection of shRNA adenovirus particles successfully suppressed the expression of arginyl-tRNA synthetase in the cerebral cortex. We observed an improvement in oxidative stress, mitochondrial function, and glucose utilization and a reduction in brain edema compared with the non-targeting control rats with suppressed expression of arginyl-tRNA synthetase mRNA in the ipsilateral ischemic cortex of the brain. Our findings indicate that knockdown of arginyl-tRNA synthetase in the cerebral cortex exerted neuroprotective effects, which were achieved not only by the improvement of oxidative stress and glucose utilization but also by the maintenance of mitochondrial morphological integrity and the preservation of mitochondrial function. Knockdown of ArgRS administration could be a promising approach to protect ischemic stroke.

A Systematic Review and Meta-Analysis of Animal Studies Testing Intra-Arterial Chilled Infusates After Ischemic Stroke

Background: As not all ischemic stroke patients benefit from currently available treatments, there is considerable need for neuroprotective co-therapies. Therapeutic hypothermia is one such co-therapy, but numerous issues have hampered its clinical use (e.g., pneumonia risk with whole-body cooling). Some problems may be avoided with brain-specific methods, such as intra-arterial selective cooling infusion (IA-SCI) into the arteries supplying the ischemic tissue. Objective: Our research question was about the efficacy of IA-SCI in animal middle cerebral artery occlusion models. We hypothesized that IA-SCI would be beneficial, but translationally-relevant study elements may be missing (e.g., aged animals). Methods: We completed a systematic review of the PubMed database following the PRISMA guidelines on May 21, 2020 for animal studies that administered IA-SCI in the peri-reperfusion period and assessed infarct volume, behavior (primary meta-analytic endpoints), edema, or blood-brain barrier injury (secondary endpoints). Our search terms included: "focal ischemia" and related terms, "IA-SCI" and related terms, and "animal" and related terms. Nineteen studies met inclusion criteria. We adapted a methodological quality scale from 0 to 12 for experimental design assessment (e.g., use of blinding/randomization, a priori sample size calculations). Results: Studies were relatively homogenous (e.g., all studies used young, healthy animals). Some experimental design elements, such as blinding, were common whereas others, such as sample size calculations, were infrequent (median methodological quality score: 5; range: 2-7). Our analyses revealed that IA-SCI provides benefit on all endpoints (mean normalized infarct volume reduction = 23.67%; 95% CI: 19.21-28.12; mean normalized behavioral improvement = 35.56%; 95% CI: 25.91-45.20; mean standardized edema reduction = 0.95; 95% CI: 0.56-1.34). Unfortunately, blood-brain barrier assessments were uncommon and could not be analyzed. However, there was substantial statistical heterogeneity and relatively few studies. Therefore, exploration of heterogeneity via meta-regression using saline infusion parameters, study quality, and ischemic duration was inconclusive. Conclusion: Despite convincing evidence of benefit in ischemic stroke models, additional studies are required to determine the scope of benefit, especially when considering additional elements (e.g., dosing characteristics). As there is interest in using this treatment alongside current ischemic stroke therapies, more relevant animal studies will be critical to inform patient studies.

Endothelial SIRT6 blunts stroke size and neurological deficit by preserving blood-brain barrier integrity: a translational study

AIMS

Aging is an established risk factor for stroke; genes regulating longevity are implicated in the pathogenesis of ischaemic stroke where to date, therapeutic options remain limited. The blood-brain barrier (BBB) is crucially involved in ischaemia/reperfusion (I/R) brain injury thus representing an attractive target for developing novel therapeutic agents. Given the role of endothelial cells in the BBB, we hypothesized that the endothelial-specific expression of the recently described longevity gene SIRT6 may exhibit protective properties in stroke.

METHODS AND RESULTS

SIRT6 endothelial expression was reduced following stroke. Endothelial-specific Sirt6 knockout (eSirt6-/-) mice, as well as animals in which Sirt6 overexpression was post-ischaemically induced, underwent transient middle cerebral artery occlusion (tMCAO). eSirt6-/- animals displayed increased infarct volumes, mortality, and neurological deficit after tMCAO, as compared to control littermates. Conversely, post-ischaemic Sirt6 overexpression decreased infarct size and neurological deficit. Analysis of ischaemic brain sections revealed increased BBB damage and endothelial expression of cleaved caspase-3 in eSIRT6-/- mice as compared to controls. In primary human brain microvascular endothelial cells (HBMVECs), hypoxia/reoxygenation (H/R) reduced SIRT6 expression and SIRT6 silencing impaired the barrier function (transendothelial resistance) similar to what was observed in mice exposed to I/R. Further, SIRT6-silenced HBMVECs exposed to H/R showed reduced viability, increased cleaved caspase-3 expression and reduced activation of the survival pathway Akt. In ischaemic stroke patients, SIRT6 expression was higher in those with short-term neurological improvement as assessed by NIHSS scale and correlated with stroke outcome.

CONCLUSION

Endothelial SIRT6 exerts a protective role in ischaemic stroke by blunting I/R-mediated BBB damage and thus, it may represent an interesting novel therapeutic target to be explored in future clinical investigation.

Downregulation of MiR-218-5p Protects Against Oxygen-Glucose Deprivation/Reperfusion-Induced Injuries of PC12 Cells via Upregulating N-myc Downstream Regulated Gene 4 (NDRG4)

Background

Cerebral ischemia is a major player of acute ischemic stroke (AIS) and mainly caused by blood vessels obstruction-induced reduced blood flow. Furthermore, miR-218-5p level was elevated in patients with AIS compared with controls. The present study investigated the biochemical mechanisms underlying the role of miR-218-5p in AIS in vitro.

Material/Methods

PC12 cells were chosen to establish oxidative-glucose deprivation/re-oxygenation (OGD/R) injury model. The interaction between miR-218-5p and N-myc downstream regulated gene 4 (NDRG4) was evaluated by Luciferase reporter assay. The levels of NDRG4, endothelial nitric oxide synthase (eNOS) and protein related to cell apoptosis were quantitatively analyzed with real-time quantitative polymerase chain reaction (RT-qPCR) or western blotting. Inflammatory cytokines, myeloperoxidase (MPO) and oxidative stress status were measured using specific commercial assay kits. Further, the cells apoptosis was analyzed with flow cytometry assay.

Results

MiR-218-5p level was notably increased in OGD/R injured PC12 cells and directly targeted NDRG4. MiR-218-5p inhibitor significantly inhibited inflammatory cytokines release, including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and monocyte chemotactic protein 1 (MCP-1). In addition, miR-218-5p downregulation ameliorated nitric oxide (NO) and eNOS levels and suppressed the inducible nitric oxide synthase (iNOS) expression and cell apoptosis. However, NDRG4 silencing abolished all corrective effects of miR-218-5p inhibitor in OGD/R injured PC12 cells.

Conclusions

Downregulation of miR-218-5p protect against OGDR-induced injuries of PC12 cells through reducing inflammatory cytokines secretion, oxidative stress status, apoptosis rate and maintenance of endovascular homeostasis via upregulating NDRG4. MiR-218-5p may serve as a novel effective biomarker to monitor AIS progression.

D-dimer and diffusion-weighted imaging pattern as two diagnostic indicators for cancer-related stroke: A case-control study based on the STROBE guidelines

The aim of this study was to evaluate the risk factors and elucidate the clinical characteristics of cancer-associated ischemic stroke to differentiate it from conventional ischemic stroke in China and East Asia. Between June 2012 and June 2016, a retrospective analysis was performed on 609 stroke patients with cancer. They were divided into 3 groups: cancer-stroke group (CSG, 203 cases), stroke group (SG, 203 cases), and cancer group (CG, 203 cases). The D-dimer levels and diffusion-weighted imaging lesion (DWI) pattern were compared to an age- and sex-matched control group. The most common cancer types were colorectal cancer (20.2%) and lung cancer (18.72%). The average D-dimer level in stroke patients and cancer patients were 0.34 and 1.50 mg/L, respectively. The descending levels of D-dimer from cancer types were lung cancer (2.06 mg/L), pancreas (1.74 mg/L), gastric (1.61 mg/L), among others. Univariate analysis of the CSG and the others shows there were significant differences in the prevalence of the levels of D-dimer and DWI pattern, hypertension, diabetes mellitus, and thrombus. CSG has a unique pathological characteristic including high plasma D-dimer levels and multiple vascular lesions. The results show that D-dimer and DWI can be used as diagnostic index in clinical practice.

Effects of thymosin β4 on neuronal apoptosis in a rat model of cerebral ischemia‑reperfusion injury

The aim of the present study was to investigate the protective effects of thymosin β4 (Tβ4) on neuronal apoptosis in rat middle cerebral artery occlusion ischemia/reperfusion (MCAO I/R) injury, and determine the mechanisms involved in this process. Forty-eight adult male Sprague-Dawley rats were randomly divided into three groups (n=16 per group): A sham control group, an ischemia/reperfusion group (I/R group), and a Tβ4 group. The focal cerebral I/R model was established by blocking the right MCA for 2 h, followed by reperfusion for 24 h. The Zea-Longa method was used to assess neurological deficits. Cerebral infarct volume was assessed using 2,3,5-triphenyltetrazolium chloride staining, and pathological changes were observed via hematoxylin and eosin staining. The terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) assay was used to detect apoptosis. The expression of glucose-regulated protein 78 (GRP78), C/EBP homologous protein (CHOP), and caspase-12 (CASP12) protein was assessed using immunohistochemistry and western blotting 24 h after reperfusion. Infarct volume and neuronal damage in the I/R and Tβ4 groups were significantly greater than those observed in the sham group. The Zea-Longa score, neuronal apoptosis, and expression of GRP78, CHOP, and CASP12 in the I/R and Tβ4 groups were significantly higher than those reported in the sham group. However, the Longa score and neuronal apoptosis were lower in the Tβ4 group compared to the I/R group. The expression of GRP78 was significantly increased, whereas that of CHOP and CASP12 was significantly decreased in the Tβ4 group compared to the I/R group. The present data revealed that Tβ4 can inhibit neuronal apoptosis by upregulating GRP78 and downregulating CHOP and CASP12, thereby reducing cerebral I/R injury.

Steroids in Stroke with Special Reference to Progesterone

Both sex and steroid hormones are important to consider in human ischemic stroke and its experimental models. Stroke initiates a cascade of changes that lead to neural cell death, but also activates endogenous protective processes that counter the deleterious consequences of ischemia. Steroids may be part of these cerebroprotective processes. One option to provide cerebroprotection is to reinforce these intrinsic protective mechanisms. In the current review, we first summarize studies describing sex differences and the influence of steroid hormones in stroke. We then present and discuss our recent results concerning differential changes in endogenous steroid levels in the brains of male and female mice and the importance of progesterone receptors (PR) during the early phase after stroke. In the third part, we give an overview of experimental studies, including ours, that provide evidence for the pleiotropic beneficial effects of progesterone and its promising cerebroprotective potential in stroke. We also highlight the key role of PR signaling as well as potential additional mechanisms by which progesterone may provide cerebroprotection.

Human serum albumin attenuates global cerebral ischemia/reperfusion-induced brain injury in a Wnt/β-Catenin/ROS signaling-dependent manner in rats

This study sought to clarify the role and underlying mechanisms of human serum albumin (HSA) therapy in global cerebral ischemia/reperfusion (GCI/R)-induced brain damage in rats. Five groups of adult male Wistar rats (n = 12 per group) were created as follows: sham operation (Sham), global cerebral ischemia/reperfusion (GCI/R), HSA treatment (GCI/R + HSA), Dickkopf-1 (DDK1) treatment (GCI/R + DDK1), and DDK1 plus HSA treatment (GCI/R + DKK1 + HSA). The GCI/R injury model was created using the modified Pusinelli four-vessel occlusion method. After 24 h, rats were evaluated using neurological scoring, Nissl staining, and brain tissue water content. The mRNA expression of Wnt, GSK3β, and β-Catenin in the brain were detected by quantitative real time polymerase chain reaction. The protein expression of β-Catenin and GSK-3β were investigated by western blot and immunohistochemical analysis in the presence and absence of the Wnt/β-Catenin antagonist, DKK-1. Complex I activity and ROS content were also measured. After 24 h of reperfusion, the behavior score and brain tissue water content in the GCI/R + HSA group were lower than that in the GCI/R group. In addition, the degree of neuronal injury was significantly reduced in the GCI/R + HSA group (P < 0.05). The ROS content was significantly decreased and Complex I activity was markedly raised in the GCI/R + HSA group compared to the GCI/R group (P < 0.05). Further, GSK-3β expression in the GCI/R + HSA group was lower than that in the GCI/R group, while the Wnt and β-catenin expression were increased. These effects were reversed by DKK1. Taken together, we showed that HSA attenuates GCI/R-induced brain damage and may be neuroprotective via regulation of the Wnt/β-catenin/ROS signaling pathway.