The Importance of Considering Sex Differences in Translational Stroke Research

Sepsis compromises post-ischemic stroke neurological recovery and is associated with sex differences

AIMS

Infection is a complication after stroke and outcomes vary by sex. Thus, we investigated if sepsis affects brain from ischemic stroke and sex involvement.

MAIN METHODS

Male and female Wistar rats, were submitted to middle cerebral artery occlusion (MCAO) and after 7 days sepsis to cecal ligation and perforation (CLP). Infarct size, neuroinflammation, oxidative stress, and mitochondrial activity were quantified 24 h after CLP in the prefrontal cortex and hippocampus. Survival and neurological score were assessed up to 15 days after MCAO or 8 days after CLP (starting at 2 h after MCAO) and memory at the end.

KEY FINDINGS

CLP decreased survival, increased neurological impairments in MCAO females. Early, in male sepsis following MCAO led to increased glial activation in the brain structures, and increased TNF-α and IL-1β in the hippocampus. All groups had higher IL-6 in both tissues, but the hippocampus had lower IL-10. CLP potentiated myeloperoxidase (MPO) in the prefrontal cortex of MCAO male and female. In MCAO+CLP, only male increased MPO and nitrite/nitrate in hippocampus. Males in all groups had protein oxidation in the prefrontal cortex, but only MCAO+CLP in the hippocampus. Catalase decreased in the prefrontal cortex and hippocampus of all males and females, and MCAO+CLP only increased this activity in males. Female MCAO+CLP had higher prefrontal cortex complex activity than males. In MCAO+CLP-induced long-term memory impairment only in females.

SIGNIFICANCE

The parameters evaluated for early sepsis after ischemic stroke show a worse outcome for males, while females are affected during long-term follow-up.

Hemorrhagic transformation in patients with large-artery atherosclerotic stroke is associated with the gut microbiota and lipopolysaccharide

JOURNAL/nrgr/04.03/01300535-202407000-00032/figure1/v/2023-11-20T171125Z/r/image-tiff

Hemorrhagic transformation is a major complication of large-artery atherosclerotic stroke (a major ischemic stroke subtype) that worsens outcomes and increases mortality. Disruption of the gut microbiota is an important feature of stroke, and some specific bacteria and bacterial metabolites may contribute to hemorrhagic transformation pathogenesis. We aimed to investigate the relationship between the gut microbiota and hemorrhagic transformation in large-artery atherosclerotic stroke. An observational retrospective study was conducted. From May 2020 to September 2021, blood and fecal samples were obtained upon admission from 32 patients with first-ever acute ischemic stroke and not undergoing intravenous thrombolysis or endovascular thrombectomy, as well as 16 healthy controls. Patients with stroke who developed hemorrhagic transformation (n = 15) were compared to those who did not develop hemorrhagic transformation (n = 17) and with healthy controls. The gut microbiota was assessed through 16S ribosomal ribonucleic acid sequencing. We also examined key components of the lipopolysaccharide pathway: lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14. We observed that bacterial diversity was decreased in both the hemorrhagic transformation and non-hemorrhagic transformation group compared with the healthy controls. The patients with ischemic stroke who developed hemorrhagic transformation exhibited altered gut microbiota composition, in particular an increase in the relative abundance and diversity of members belonging to the Enterobacteriaceae family. Plasma lipopolysaccharide and lipopolysaccharide-binding protein levels were higher in the hemorrhagic transformation group compared with the non-hemorrhagic transformation group. lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14 concentrations were associated with increased abundance of Enterobacteriaceae. Next, the role of the gut microbiota in hemorrhagic transformation was evaluated using an experimental stroke rat model. In this model, transplantation of the gut microbiota from hemorrhagic transformation rats into the recipient rats triggered higher plasma levels of lipopolysaccharide, lipopolysaccharide-binding protein, and soluble CD14. Taken together, our findings demonstrate a noticeable change in the gut microbiota and lipopolysaccharide-related inflammatory response in stroke patients with hemorrhagic transformation. This suggests that maintaining a balanced gut microbiota may be an important factor in preventing hemorrhagic transformation after stroke.

Potential diagnostic biomarkers for immunogenic cell death in elderly female patients with ischemic stroke: identification and analysis

Ischemic stroke (IS) is of increasing concern given the aging population and prevalence of unhealthy lifestyles, with older females exhibiting higher susceptibility. This study aimed to identify practical diagnostic markers, develop a diagnostic model for immunogenic cell death (ICD)-associated IS, and investigate alterations in the immune environment caused by hub genes. Differentially expressed genes associated with ICD in IS were identified based on weighted gene co-expression network analysis and the identification of significant modules. Subsequently, machine learning algorithms were employed to screened hub genes, which were further assessed using Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, and Gene Set Enrichment Analysis. A nomogram mode lwas then constructed for IS diagnosis, and its diagnostic value was assessed using a receiver operating characteristic curve. Finally, alterations in immune cell infiltration were assessed within patients with IS, and the pan-cancer expression patterns of hub genes were evaluated. Three hub genes associated with ICD (PDK4, CCL20, and FBL) were identified. The corresponding nomogram model for IS diagnosis could effectively identify older female patients with IS (area under the curve (AUC) = 0.9555). Overall, the three hub genes exhibit good diagnostic value (AUC > 0.8). CCL20 and FBL are significantly associated with the extent of immune cells infiltration. Moreover, a strong link exists between hub gene expression and pan-cancer prognosis. Cumulatively, these results indicate that ICD-related hub genes critically influence IS progression in older females, presenting novel diagnostic and therapeutic targets for personalized treatment.

Sex differences in treatment effect in neuroprotectant trials for acute ischemic stroke: A systematic review

BACKGROUND

Pre-clinical data suggest sex differences in mechanisms of cerebral ischemic injury. This might result in differential outcomes of putative neuroprotectants by sex, though little systematic data is available to assess this.

METHODS

We performed a systematic review of multicenter randomized controlled trials published from January 1980-June 2022 enrolling >100 subjects and testing neuroprotectants in acute ischemic stroke (AIS). For each trial, reported treatment effect by sex was extracted. When published results by sex were not available, we contacted individual authors to attempt to retrieve these data.

RESULTS

We identified 59 publications reporting 64 trials that met inclusion criteria. Of these, data on treatment effect by sex were published for 14/64 trials. Unpublished data for an additional 5 trials were obtained from trial investigators (19/64, or 29.7%). Two trials (one testing uric acid and one dexborneol) reported treatment benefit in women but not men. Pooled analysis of six trials of tirilazad reported worse treatment outcomes in women and no effect in men. No clear difference was apparent in the other trials.

CONCLUSIONS

Most trials did not report treatment effect by sex. Of those that did, there was little evidence of systematic sex differences in treatment response.

Acute Ischemic Stroke in the Clinic and the Laboratory: Targets for Translational Research

Ischemic stroke research has enabled significant advancements in diagnosis, treatment, and management of this debilitating disease, yet challenges remain standing in the way of better patient prognoses. In this narrative review, a fictional case illustrates challenges and uncertainties that medical professionals still face - penumbra identification, lack of neuroprotective agents, side-effects of tissue plasminogen activator, dearth of molecular biomarkers, incomplete microvascular reperfusion or no-reflow, post-recanalization hyperperfusion, blood pressure management and procedural anesthetic effects. The current state of the field is broadly reviewed per topic, with the aim to introduce a broad audience (scientist and clinician alike) to recent successes in translational stroke research and pending scientific queries that are tractable for preclinical assessment. Opportunities for co-operation between clinical and experimental stroke experts are highlighted to increase the size and frequency of strides the field makes to improve our understanding of this disease and ways of treating it.

Sex-Specific Acute Cerebrovascular Responses to Photothrombotic Stroke in Mice

Mechanisms underlying cerebrovascular stroke outcomes are poorly understood, and the effects of biological sex on cerebrovascular regulation post-stroke have yet to be fully comprehended. Here, we explore the overlapping roles of gonadal sex hormones and rho-kinase (ROCK), two important modulators of cerebrovascular tone, on the acute cerebrovascular response to photothrombotic (PT) focal ischemia in mice. Male mice were gonadectomized and female mice were ovariectomized to remove gonadal hormones, whereas control ("intact") animals received a sham surgery prior to stroke induction. Intact wild-type (WT) males showed a delayed drop in cerebral blood flow (CBF) compared with intact WT females, whereby maximal CBF drop was observed 48 h following stroke. Gonadectomy in males did not alter this response. However, ovariectomy in WT females produced a "male-like" phenotype. Intact Rock2+/- males also showed the same phenotypic response, which was not altered by gonadectomy. Alternatively, intact Rock2+/- females showed a significant difference in CBF values compared with intact WT females, displaying higher CBF values immediately post-stroke and showing a maximal CBF drop 48 h post-stroke. This pattern was not altered by ovariectomy. Altogether, these data illustrate sex differences in acute CBF responses to PT stroke, which seem to involve gonadal female sex hormones and ROCK2. Overall, this study provides a framework for exploring sex differences in acute CBF responses to focal ischemic stroke in mice.

Comprehensive review on sexual dimorphism to improve scalp acupuncture in nervous system disease

BACKGROUND

With the development of modern medicine, the Traditional Chinese Medicine (TCM) combined with western medicine began to be produced and applied. Scalp acupuncture (SA) as a Chinese medicine based on neurological theory, has a great advantage compared with TCM in the treatment of nervous system diseases.

METHOD

In this paper, we analyze the physiological and pathological manifestations of sexual dimorphism (SD) to illustrate the necessity of SD treatment. In addition, we review the factors that can affect SD and analyze in physiological structure, function, and pathological neurons. Diseases (pathological basis, pathological manifestations, and incidence) and factors leading to gender differences, which to analyze the possibility of gender differences in SA.

RESULT

Furthermore, we creatively a new insight of SD-SA and provide the complete SD treatment cases on the basis of the existing SA in different kinds of diseases including stroke, migraine, attention deficit hyperactivity disorder (ADHD), and depression.

CONCLUSION

In summary, we believe that it is feasible to improve the clinical effectiveness of SA, which is able to promote the development of SA, and then provides an actionable evidence for the promotion of precision medicine in the future.

Effect and mechanisms of resveratrol in animal models of ischemic stroke: A systematic review and Bayesian meta-analysis

Resveratrol (RSV) holds promise as cerebroprotective treatment in cerebral ischemia. This systematic review aims to assess the effects and mechanisms of RSV in animal models of ischemic stroke. We searched Medline, Embase and Web of Science to identify 75 and 57 eligible rodent studies for qualitative and quantitative syntheses, respectively. Range of evidence met 10 of 13 STAIR criteria. Median (Q1, Q3) quality score was 7 (5, 8) on the CAMARADES 15-item checklist. Bayesian meta-analysis showed SMD estimates (95% CI) favoring RSV: infarct size (-1.72 [-2.03; -1.41]), edema size (-1.61 [-2.24; -0.98]), BBB impairment (-1.85 [-2.54; -1.19]), neurofunctional impairment (-1.60 [-1.92; -1.29]), and motor performance (1.39 [0.64; 2.08]); and less probably neuronal survival (0.63 [-1.40; 2.48]) and apoptosis (-0.96 [-2.87; 1.02]). Species (rat vs mouse) was associated to a larger benefit. Sensitivity analyses confirmed robustness of the estimates. Reduction of oxidative stress, inflammation, and apoptosis underlie these effects. Our results quantitatively state the beneficial effects of RSV on structural and functional outcomes in rodent stroke models, update the evidence on the mechanisms of action, and provide an exhaustive list of targeted signaling pathways. Current evidence highlights the need for conducting further high-quality preclinical research to better inform clinical research.

Dysphagia after ischemic and hemorrhagic stroke: A propensity-matched 20-year analysis of the national inpatient sample

OBJECTIVE

Dysphagia is a common symptom of acute ischemic stroke (AIS) and intracerebral hemorrhage (ICH), but little is known surrounding national trends of this post-stroke condition. Hence, this study aimed to identify the risk factors for dysphagia following AIS and ICH and evaluate in-hospital outcomes in these patients.

METHODS

The 2000-2019 Nationwide Inpatient Sample was queried for patients admitted with AIS (ICD9 433, 43401, 43411, 43491, ICD-10 I63) and ICH (ICD9 431, 432.9, ICD-10 I61, I62.9). Univariate analysis with t-tests or chi-square performed as appropriate. A 1:1 nearest neighbor propensity score matched cohort was generated. Variables with standardized mean differences >0.1 were used in multivariable regression to generate adjusted odds ratios (AOR)/β-coefficients for the presence of dysphagia on outcomes.

RESULTS

Of 10,415,286 patients with AIS, 956,662 (9.2%) had in-hospital dysphagia. Total of 2,000,868 patients with ICH were identified; 203,511 (10.2%) had in-hospital dysphagia. Patients with dysphagia after AIS were less likely to experience in-hospital mortality (OR 0.61;95%CI: 0.60-0.63) or be discharged home (AOR 0.51;95%CI: 0.51-0.52), had increased length of stay (Beta-coefficient = 0.43 days; 95%CI: 0.36-0.50), and had increased hospital charges ($14411.96;95%CI: 13565.68-15257.44) (all p < 0.001). Patients with dysphagia after ICH were less likely to experience in-hospital mortality (AOR 0.39;95%CI: 0.37-0.4), less likely to be discharged home (AOR 0.59,95%CI:0.57-0.61), have longer hospital stay (Beta-coefficient = 1.99 days;95%CI: 1.78-2.21), and increased hospital charges ($28251.93; 95%CI: $25594.57-30909.28)(all p < 0.001).

CONCLUSION

This is the first study to report on national trends in patients with dysphagia after AIS and ICH. These patients had longer hospital LOS, worse functional outcomes at discharge, and higher hospital costs.

Sex and gender differences in acute stroke care: metrics, access to treatment and outcome. A territorial analysis of the Stroke Code System of Catalonia

INTRODUCTION

Previous studies have reported differences in the management and outcome of women stroke patients in comparison with men. We aim to analyze sex and gender differences in the medical assistance, access to treatment and outcome of acute stroke patients in Catalonia.

PATIENTS AND METHODS

Data were obtained from a prospective population-based registry of stroke code activations in Catalonia (CICAT) from January/2016 to December/2019. The registry includes demographic data, stroke severity, stroke subtype, reperfusion therapy, and time workflow. Centralized clinical outcome at 90 days was assessed in patients receiving reperfusion therapy.

RESULTS

A total of 23,371 stroke code activations were registered (54% men, 46% women). No differences in prehospital time metrics were observed. Women more frequently had a final diagnosis of stroke mimic, were older and had a previous worse functional situation. Among ischemic stroke patients, women had higher stroke severity and more frequently presented proximal large vessel occlusion. Women received more frequently reperfusion therapy (48.2% vs 43.1%, p < 0.001). Women tended to present a worse outcome at 90 days, especially for the group receiving only IVT (good outcome 56.7% vs 63.8%; p < 0.001), but not for the group of patients treated with IVT + MT or MT alone, although sex was not independently associated with clinical outcome in logistic regression analysis (OR 1.07; 95% CI, 0.94-1.23; p = 0.27) nor in the analysis after matching using the propensity score (OR 1.09; 95% CI, 0.97-1.22).

DISCUSSION AND CONCLUSION

We found some differences by sex in that acute stroke was more frequent in older women and the stroke severity was higher. We found no differences in medical assistance times, access to reperfusion treatment and early complications. Worse clinical outcome at 90 days in women was conditioned by stroke severity and older age, but not by sex itself.

Sex differences in mild vascular cognitive impairment: A multimodal transcranial magnetic stimulation study

BACKGROUND

Sex differences in vascular cognitive impairment (VCI) at risk for future dementia are still debatable. Transcranial magnetic stimulation (TMS) is used to evaluate cortical excitability and the underlying transmission pathways, although a direct comparison between males and females with mild VCI is lacking.

METHODS

Sixty patients (33 females) underwent clinical, psychopathological, functional, and TMS assessment. Measures of interest consisted of: resting motor threshold, latency of motor evoked potentials (MEPs), contralateral silent period, amplitude ratio, central motor conduction time (CMCT), including the F wave technique (CMCT-F), short-interval intracortical inhibition (SICI), intracortical facilitation, and short-latency afferent inhibition, at different interstimulus intervals (ISIs).

RESULTS

Males and females were comparable for age, education, vascular burden, and neuropsychiatric symptoms. Males scored worse at global cognitive tests, executive functioning, and independence scales. MEP latency was significantly longer in males, from both sides, as well CMCT and CMCT-F from the left hemisphere; a lower SICI at ISI of 3 ms from the right hemisphere was also found. After correction for demographic and anthropometric features, the effect of sex remained statistically significant for MEP latency, bilaterally, and for CMCT-F and SICI. The presence of diabetes, MEP latency bilaterally, and both CMCT and CMCT-F from the right hemisphere inversely correlated with executive functioning, whereas TMS did not correlate with vascular burden.

CONCLUSIONS

We confirm the worse cognitive profile and functional status of males with mild VCI compared to females and first highlight sex-specific changes in intracortical and cortico-spinal excitability to multimodal TMS in this population. This points to some TMS measures as potential markers of cognitive impairment, as well as targets for new drugs and neuromodulation therapies.

Men Are at Higher Risk of Screening Positive for Vascular Cognitive Impairment Compared to Women after Stroke and Transient Ischemic Attack

While women have greater incidence of dementia, men have higher prevalence of vascular risk factors. This study examined sex differences in risk of screening positive for cognitive impairment after stroke. Ischemic stroke/TIA patients (N = 5969) participated in this prospective, multi-centered study, which screened for cognitive impairment using a validated brief screen. Men showed a higher risk of screening positive for cognitive impairment after adjusting for age, education, stroke severity, and vascular risk factors, suggesting that other factors may be contributing to increased risk among men (OR = 1.34, CI 95% [1.16, 1.55], p < 0.001). The effect of sex on cognitive impairment after stroke warrants further attention.

Sex as a biological variable in determining the metabolic changes influencing acute ischemic stroke outcomes-Where is the data: A systematic review

Women continue to face a greater lifetime morbidity and mortality from stroke and have been shown to respond differently to stroke treatments compared to men. Since 2016, updated National Institutes of Health (NIH) policies require research studies to consider sex as a biological variable. However, the way in which this policy affects study design, analysis, and reporting is variable, with few studies performing and reporting a subgroup analysis based on biological sex. In acute ischemic stroke, the underlying biological explanation for sex-based differences in patient outcomes and response to treatments remains understudied. We performed a systematic review of preclinical and clinical research studies that explored sex differences in the metabolic response to acute ischemic stroke as it relates to neurological outcomes. Through a literature search in Ovid Medline, Embase, and Web of Science, 1,004 potential references were identified for screening. After abstract and full-text review, we identified only two studies which assessed metabolic response to acute ischemic stroke (within 72 h of last known well) and neurological outcome [Barthel Index, modified Rankin Scale (mRS) or an equivalent in preclinical models] and reported results based on biological sex. One article was a preclinical rat model and the other a clinical cohort study. In both studies, metabolites involved in amino acid metabolism, energy metabolism, fat metabolism, or oxidative stress were identified. We review these results and link to additional articles that use metabolomics to identify metabolites differentially expressed by sex or regulated based on stroke outcomes, but not both. The results of this systematic review should not only help identify targets in need of further investigation to improve the understanding of sex differences in the pathophysiology of acute ischemic stroke, but also highlight the critical need to expand the incorporation of sex as a biological variable in acute stroke research beyond simply including both sexes and reporting the proportion of males/females in each population studied.

Adenosine A1R/A3R agonist AST-004 reduces brain infarction in mouse and rat models of acute ischemic stroke

Acute ischemic stroke (AIS) is the second leading cause of death globally. No Food and Drug Administration (FDA) approved therapies exist that target cerebroprotection following stroke. Our group recently reported significant cerebroprotection with the adenosine A1/A3 receptor agonist, AST-004, in a transient stroke model in non-human primates (NHP) and in a preclinical mouse model of traumatic brain injury (TBI). However, the specific receptor pathway activated was only inferred based on in vitro binding studies. The current study investigated the underlying mechanism of AST-004 cerebroprotection in two independent models of AIS: permanent photothrombotic stroke in mice and transient middle cerebral artery occlusion (MCAO) in rats. AST-004 treatments across a range of doses were cerebroprotective and efficacy could be blocked by A3R antagonism, indicating a mechanism of action that does not require A1R agonism. The high affinity A3R agonist MRS5698 was also cerebroprotective following stroke, but not the A3R agonist Cl-IB-MECA under our experimental conditions. AST-004 efficacy was blocked by the astrocyte specific mitochondrial toxin fluoroacetate, confirming an underlying mechanism of cerebroprotection that was dependent on astrocyte mitochondrial metabolism. An increase in A3R mRNA levels following stroke suggested an intrinsic cerebroprotective response that was mediated by A3R signaling. Together, these studies confirm that certain A3R agonists, such as AST-004, may be exciting new therapeutic avenues to develop for AIS.

Selective brain hypothermia attenuates focal cerebral ischemic injury and improves long-term neurological outcome in aged female mice

AIMS

This study aimed to investigate the effects of mild selective brain hypothermia on aged female ischemic mice.

METHODS

A distal middle cerebral artery occlusion (dMCAO) model was established in aged female mice, who were then subjected to mild selective brain hypothermia immediately after the dMCAO procedure. Neurological behavioral examinations were conducted prior to and up to 35 days post-ischemia. Infarct volume, brain atrophy, pro-inflammation, and anti-inflammation microglia/macrophages phenotype and white matter injury were evaluated by immunofluorescence staining. Correlations between neurological behaviors and histological parameters were evaluated by Pearson product linear regression analysis.

RESULTS

Sensorimotor and cognitive function tests confirmed the protective effect of mild selective brain hypothermia in elderly female ischemic mice. In addition, hypothermia decreased the infarct volume and brain atrophy induced by focal cerebral ischemia. Furthermore, hypothermia alleviated ischemia-induced short-term and long-term white matter injury, which was correlated with behavioral deficits. Finally, hypothermia suppressed the harmful immunological response by promoting the transformation of pro-inflammatory microglia/macrophages to anti-inflammatory phenotype. This polarization was negatively correlated with neuronal loss and white matter injury.

CONCLUSION

Mild selective brain hypothermia promoted long-term functional recovery by alleviating white matter damage in an aged female mouse model of ischemia.

Female-specific neuroprotection after ischemic stroke by vitronectin-focal adhesion kinase inhibition

We found that blood vitronectin (VTN) leaks into the brain and exacerbates tissue loss after stroke by increasing pro-inflammatory IL-6 expression in female, but not male, mice. VTN signals through integrins and downstream focal adhesion kinase (FAK). Here, a two day systemic treatment with a small molecule FAK inhibitor starting 6 h after middle cerebral artery occlusion reduced ipsilateral brain injury size by ∼40-45% at 7 and 14 d, as well as inflammation and motor dysfunction in wild-type female, but not male, mice. FAK inhibition also reduced IL-6 expression in the injured female striatum at 24 h by 62%. Inducible selective gene deletion of FAK in astrocytes also reduced acute IL-6 expression by 72% only in females, and mitigated infarct size by ∼80% and inflammation at 14 d after stroke. Lastly, VTN-/- females had better outcomes, but FAK inhibitor treatment had no additional protective or anti-inflammatory effects. Altogether, this suggests that VTN is detrimental in females primarily through FAK and that FAK inhibition provides neuroprotection (cerebroprotection) by reducing VTN-induced IL-6 expression in astrocytes. Thus, VTN signaling can be targeted to mitigate harmful inflammation with relevance to treatments for women with ischemic stroke, who often have worse outcomes than men.

Blockade of Platelet Glycoprotein Ibα Augments Neuroprotection in Orai2-Deficient Mice during Middle Cerebral Artery Occlusion

During ischemic stroke, infarct growth before recanalization diminishes functional outcome. Hence, adjunct treatment options to protect the ischemic penumbra before recanalization are eagerly awaited. In experimental stroke targeting two different pathways conferred protection from penumbral tissue loss: (1) enhancement of hypoxic tolerance of neurons by deletion of the calcium channel subunit Orai2 and (2) blocking of detrimental lymphocyte–platelet responses. However, until now, no preclinical stroke study has assessed the potential of combining neuroprotective with anti-thrombo-inflammatory interventions to augment therapeutic effects. We induced focal cerebral ischemia in Orai2-deficient (Orai2^-/-) mice by middle cerebral artery occlusion (MCAO). Animals were treated with anti-glycoprotein Ib alpha (GPIbα) Fab fragments (p0p/B Fab) blocking GPIbα–von Willebrand factor (vWF) interactions. Rat immunoglobulin G (IgG) Fab was used as the control treatment. The extent of infarct growth before recanalization was assessed at 4 h after MCAO. Moreover, infarct volumes were determined 6 h after recanalization (occlusion time: 4 h). Orai2 deficiency significantly halted cerebral infarct progression under occlusion. Inhibition of platelet GPIbα further reduced primary infarct growth in Orai2^-/- mice. During ischemia–reperfusion, upon recanalization, mice were likewise protected. All in all, we show that neuroprotection in Orai2^-/- mice can be augmented by targeting thrombo-inflammation. This supports the clinical development of combined neuroprotective/anti-platelet strategies in hyper-acute stroke.

Prevalence of dysphagia and risk of pneumonia and mortality in acute stroke patients: a meta-analysis

Background

Post-stroke dysphagia (PSD) has been associated with high risk of aspiration pneumonia and mortality. However, limited evidence on pooled prevalence of post-stroke dysphagia and influence of individual, disease and methodological factors reveals knowledge gap. Therefore, to extend previous evidence from systematic reviews, we performed the first meta-analysis to examine the pooled prevalence, risk of pneumonia and mortality and influence of prognostic factors for PSD in acute stroke.

Methods

Our search was conducted in CINAHL, Cochrane Library, EMBASE, Ovid-Medline, PubMed, and Web of Science an initial search in October 2020 and a follow-up search in May 2021. Data synthesis was conducted using the Freeman-Tukey double-arcsine transformation model for the pooled prevalence rate and the DerSimonian-Lard random-effects model for prognostic factors and outcomes of PSD.

Results

The pooled prevalence of PSD was 42% in 42 studies with 26,366 participants. PSD was associated with higher pooled odds ratio (OR) for risk of pneumonia 4.08 (95% CI, 2.13–7.79) and mortality 4.07 (95% CI, 2.17–7.63). Haemorrhagic stroke 1.52 (95% CI, 1.13–2.07), previous stroke 1.40 (95% CI, 1.18–1.67), severe stroke 1.38 (95% CI, 1.17–1.61), females 1.25 (95% CI, 1.09–1.43), and diabetes mellitus 1.24 (95% CI, 1.02–1.51) were associated with higher risk of PSD. Males 0.82 (95% CI, 0.70–0.95) and ischaemic stroke 0.54 (95% CI, 0.46–0.65) were associated with lower risk of PSD. Haemorrhagic stroke, use of instrumental assessment method, and high quality studies demonstrated to have higher prevalence of PSD in the moderator analysis.

Conclusions

Assessment of PSD in acute stroke with standardized valid and reliable instruments should take into account stroke type, previous stroke, severe stroke, diabetes mellitus and gender to aid in prevention and management of pneumonia and thereby, reduce the mortality rate.

Trial registration

https://osf.io/58bjk/?view_only=26c7c8df8b55418d9a414f6d6df68bdb.

Supplementary information

The online version contains supplementary material available at 10.1186/s12877-022-02960-5.

Liver vitronectin release into the bloodstream increases due to reduced vagal muscarinic signaling after cerebral stroke in female mice

Vitronectin (VTN) is a glycoprotein enriched in the blood and activates integrin receptors. VTN blood levels increase only in female mice 24 h after an ischemic stroke and exacerbate brain injury through IL-6-driven inflammation, but the VTN induction mechanism is unknown. Here, a 30 min middle cerebral artery occlusion (MCAO) in female mice induced VTN protein in the liver (normally the main source) in concert with plasma VTN. Male mice were excluded as VTN is not induced after stroke. MCAO also increased plasma VTN levels after de novo expression of VTN in the liver of VTN^-/- female mice, using a hepatocyte-specific (SERPINA1) promoter. MCAO did not affect SERPINA1 or VTN mRNA in the liver, brain, or several peripheral organs, or platelet VTN, compared to sham mice. Thus, hepatocytes are the source of stroke-induced increases in plasma VTN, which is independent of transcription. The cholinergic innervation by the parasympathetic vagus nerve is a potential source of brain-liver signaling after stroke. Right-sided vagotomy at the cervical level led to increased plasma VTN levels, suggesting that VTN release is inhibited by vagal tone. Co-culture of hepatocytes with cholinergic neurons or treatment with acetylcholine, but not noradrenaline (sympathetic transmitter), suppressed VTN expression. Hepatocytes have muscarinic receptors and the M1/M3 agonist bethanechol decreased VTN mRNA and protein release in vitro via M1 receptors. Finally, systemic bethanechol treatment blocked stroke-induced plasma VTN. Thus, VTN translation and release are inhibited by muscarinic signaling from the vagus nerve and presents a novel target for lessening detrimental VTN expression.

Repair-related molecular changes during recovery phase of ischemic stroke in female rats

BACKGROUND

Some degree of spontaneous recovery is usually observed after stroke. Experimental studies have provided information about molecular mechanisms underlying this recovery. However, the majority of pre-clinical stroke studies are performed in male rodents, and females are not well studied. This is a clear discrepancy when considering the clinical situation. Thus, it is important to include females in the evaluation of recovery mechanisms for future therapeutic strategies. This study aimed to evaluate spontaneous recovery and molecular mechanisms involved in the recovery phase two weeks after stroke in female rats.

METHODS

Transient middle cerebral artery occlusion was induced in female Wistar rats using a filament model. Neurological functions were assessed up to day 14 after stroke. Protein expression of interleukin 10 (IL-10), transforming growth factor (TGF)-β, neuronal specific nuclei protein (NeuN), nestin, tyrosine-protein kinase receptor Tie-2, extracellular signal-regulated kinase (ERK) 1/2, and Akt were evaluated in the peri-infarct and ischemic core compared to contralateral side of the brain at day 14 by western blot. Expression of TGF-β in middle cerebral arteries was evaluated by immunohistochemistry.

RESULTS

Spontaneous recovery after stroke was observed from day 2 to day 14 and was accompanied by a significantly higher expression of nestin, p-Akt, p-ERK1/2 and TGF-β in ischemic regions compared to contralateral side at day 14. In addition, a significantly higher expression of TGF-β was observed in occluded versus non-occluded middle cerebral arteries. The expression of Tie-2 and IL-10 did not differ between the ischemic and contralateral sides.

CONCLUSION

Spontaneous recovery after ischemic stroke in female rats was coincided by a difference observed in the expression of molecular markers. The alteration of these markers might be of importance to address future therapeutic strategies.

Human cytomegalovirus infection is associated with stroke in women: the US National Health and Nutrition Examination Survey 1999-2004

BACKGROUND

Increasing evidence indicated that infection factors play important roles in stroke development. Human cytomegalovirus (HCMV) infection was positively associated with atherosclerosis and hypertension which are stroke risk factors. Therefore, we aimed to explore the relationship between HCMV infection and stroke using the data of US National Health and Nutrition Examination Survey (NHANES).

METHODS

We analysed data on 2844 men and 3257 women in the NHANES 1999-2004. We included participants aged 20-49 years who had valid data on HCMV infection and stroke.

RESULTS

54.1% of participants had serological evidence of HCMV infection and 0.8% of them had a previous diagnosis of stroke. There were ethnic differences in the prevalence of HCMV seropositivity (p<0.001). There was no significant association between HCMV seropositivity and stroke in men in any of the models. In women, HCMV seropositivity was associated with stroke before adjustment (OR=3.45, 95% CI 1.09 to 10.95, p=0.036). After adjusting for race/ethnicity, the association remained significant (OR=4.40, 95% CI 1.37 to 14.09, p=0.014). After further adjustment for body mass index, diabetes, hypercholesterolaemia, hypertension, alcohol consumption, smoking and physical activity, the association still existed (OR=3.58, 95% CI 1.14 to 11.25, p=0.030). The association was significant consistently in adjusted model for age (OR=3.39, 95% CI 1.08 to 10.64, p=0.037).

CONCLUSIONS

We found a strong association between HCMV and stroke in women from the nationally representative population-based survey. This provide additional motivation for undertaking the difficult challenge to reduce the prevalence of stroke.

Ovariectomy Reduces Vasocontractile Responses of Rat Middle Cerebral Arteries After Focal Cerebral Ischemia

ABSTRACT

Effects of sex hormones on stroke outcome are not fully understood. A deleterious consequence of cerebral ischemia is upregulation of vasoconstrictor receptors in cerebral arteries that exacerbate stroke injury. Here, we tested the hypothesis that female sex hormones alter vasocontractile responses after experimental stroke in vivo or after organ culture in vitro, a model of vasocontractile receptor upregulation. Female rats with intact ovaries and ovariectomized (OVX) females treated with 17β-estradiol, progesterone, or placebo were subjected to transient, unilateral middle cerebral artery occlusion followed by reperfusion (I/R). The maximum contractile response, measured my wire myography, in response to the endothelin B receptor agonist sarafotoxin 6c was increased in female arteries after I/R, but the maximum response was significantly lower in arteries from OVX females. Maximum contraction mediated by the serotonin agonist 5-carboxamidotryptamine was diminished after I/R, with arteries from OVX females showing a greater decrease in maximum contractile response. Contraction elicited by angiotensin II was similar in all arteries. Neither estrogen nor progesterone treatment of OVX females affected I/R-induced changes in endothelin B- and 5-carboxamidotryptamine-induced vasocontraction. These findings suggest that sex hormones do not directly influence vasocontractile alterations that occur after ischemic stroke; however, loss of ovarian function does impact this process.

Progress and challenges in preclinical stroke recovery research

Significant innovations in the management of acute ischemic stroke have led to an increased incidence in the long-term complications of stroke. Therefore, there is an urgent need for improvements in and refinement of rehabilitation interventions that can lead to functional and neuropsychological recovery. The goal of this review is to summarize the current progress and challenges involved with preclinical stroke recovery research. Moving forward, stroke recovery research should be placing an increased emphasis on the incorporation of comorbid diseases and biological variables in preclinical models in order to overcome translational roadblocks to establishing successful clinical rehabilitation interventions.

Histochemistry of microinfarcts in the mouse brain after injection of fluorescent microspheres into the common carotid artery

The mouse model of multiple cerebral infarctions, established by injecting fluorescent microspheres into the common carotid artery, is a recent development in animal models of cerebral ischemia. To investigate its effectiveness, mouse models of cerebral infarction were created by injecting fluorescent microspheres, 45–53 µm in diameter, into the common carotid artery. Six hours after modeling, fluorescent microspheres were observed directly through a fluorescence stereomicroscope, both on the brain surface and in brain sections. Changes in blood vessels, neurons and glial cells associated with microinfarcts were examined using fluorescence histochemistry and immunohistochemistry. The microspheres were distributed mainly in the cerebral cortex, striatum and hippocampus ipsilateral to the side of injection. Microinfarcts were found in the brain regions where the fluorescent microspheres were present. Here the lodged microspheres induced vascular and neuronal injury and the activation of astroglia and microglia. These histopathological changes indicate that this animal model of multiple cerebral infarctions effectively simulates the changes of various cell types observed in multifocal microinfarcts. This model is an effective, additional tool to study the pathogenesis of ischemic stroke and could be used to evaluate therapeutic interventions. This study was approved by the Animal Ethics Committee of the Institute of Acupuncture and Moxibustion, China Academy of Chinese Medical Sciences (approval No. D2021-03-16-1) on March 16, 2021.

Association of single-nucleotide polymorphism on chromosome 9 and ischemic stroke in Heilongjiang province in China

There is a significant correlation between ischemic stroke (IS) and chromosome 9. However, its status was uncertain in China's cold regions. 1920 IS patients, and 1920 healthy individuals were included in the study. Blood samples were collected. The association of SNPs with IS was evaluated by Sequenom, and logistic regression models adjusted for known risk factors of IS were constructed to assess the SNPs' associations in cases and controls. We found rs1333040 and rs2383207 were associated with IS, compared with primitive genotypes. The genotype CT of rs7027526 has a protective role during IS development, while the effect of the genotype TT is still not clear. These results changed after stratification by age and sex. In conclusion, rs1333040 and rs2383207 SNPs in CDKN2BAS are associated with ischemic stroke in the Chinese Han population. This study confirms the association between 9p21.3 and IS.

The Impact of Sex on Arterial Ischemic Stroke in Young Patients: From Stroke Occurrence to Poststroke Consequences

The male sex has been suggested to predominate in paediatric patients with arterial ischemic stroke (AIS), especially in newborns. The explanation for this phenomenon remains unsatisfactory since it focuses on the analysis of the potential relationship with trauma and arterial dissection. In turn, in some populations of young adults, men suffer from AIS more frequently than women, which may be related to the protective role of oestrogen. On the other hand, certain data indicate that women dominate over men. Some of the disparities in the frequencies of particular symptoms of AIS and poststroke consequences in both children and young adults have been suggested; however, data are scarce. Unfortunately, the low number of studies on the subject does not allow certain conclusions to be drawn. For adults, more data are available for patients aged over 60 years, the results of which are more obvious. The present literature review aimed to discuss available data on the prevalence of AIS, its clinical presentations, and poststroke consequences in regard to the sex of young patients. We considered young patients to be children from birth up to the age of 19 years of life and young adults to be individuals up to the age of 55 years. The role of sex hormones in AIS and possible gender differences in genetic risk factors for AIS were also discussed briefly.

Can quantifying morphology and TMEM119 expression distinguish between microglia and infiltrating macrophages after ischemic stroke and reperfusion in male and female mice?

Background

Ischemic stroke is an acquired brain injury with gender-dependent outcomes. A persistent obstacle in understanding the sex-specific neuroinflammatory contributions to ischemic brain injury is distinguishing between resident microglia and infiltrating macrophages—both phagocytes—and determining cell population-specific contributions to injury evolution and recovery processes. Our purpose was to identify microglial and macrophage populations regulated by ischemic stroke using morphology analysis and the presence of microglia transmembrane protein 119 (TMEM119). Second, we examined sex and menopause differences in microglia/macrophage cell populations after an ischemic stroke.

Methods

Male and female, premenopausal and postmenopausal, mice underwent either 60 min of middle cerebral artery occlusion and 24 h of reperfusion or sham surgery. The accelerated ovarian failure model was used to model postmenopause. Brain tissue was collected to quantify the infarct area and for immunohistochemistry and western blot methods. Ionized calcium-binding adapter molecule, TMEM119, and confocal microscopy were used to analyze the microglia morphology and TMEM119 area in the ipsilateral brain regions. Western blot was used to quantify protein quantity.

Results

Post-stroke injury is increased in male and postmenopause female mice vs. premenopause female mice (p < 0.05) with differences primarily occurring in the caudal sections. After stroke, the microglia underwent a region, but not sex group, dependent transformation into less ramified cells (p < 0.0001). However, the number of phagocytic microglia was increased in distal ipsilateral regions of postmenopausal mice vs. the other sex groups (p < 0.05). The number of TMEM119-positive cells was decreased in proximity to the infarct (p < 0.0001) but without a sex group effect. Two key findings prevented distinguishing microglia from systemic macrophages. First, morphological data were not congruent with TMEM119 immunofluorescence data. Cells with severely decreased TMEM119 immunofluorescence were ramified, a distinguishing microglia characteristic. Second, whereas the TMEM119 immunofluorescence area decreased in proximity to the infarcted area, the TMEM119 protein quantity was unchanged in the ipsilateral hemisphere regions using western blot methods.

Conclusions

Our findings suggest that TMEM119 is not a stable microglia marker in male and female mice in the context of ischemic stroke. Until TMEM119 function in the brain is elucidated, its use to distinguish between cell populations following brain injury with cell infiltration is cautioned.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02105-2.

Dynamic capillary stalls in reperfused ischemic penumbra contribute to injury: A hyperacute role for neutrophils in persistent traffic jams

Ever since the introduction of thrombolysis and the subsequent expansion of endovascular treatments for acute ischemic stroke, it remains to be identified why the actual outcomes are less favorable despite recanalization. Here, by high spatio-temporal resolution imaging of capillary circulation in mice, we introduce the pathological phenomenon of dynamic flow stalls in cerebral capillaries, occurring persistently in salvageable penumbra after reperfusion. These stalls, which are different from permanent cellular plugs of no-reflow, were temporarily and repetitively occurring in the capillary network, impairing the overall circulation like small focal traffic jams. In vivo microscopy in the ischemic penumbra revealed leukocytes traveling slowly through capillary lumen or getting stuck, while red blood cell flow was being disturbed in the neighboring segments under reperfused conditions. Stall dynamics could be modulated, by injection of an anti-Ly6G antibody specifically targeting neutrophils. Decreased number and duration of stalls were associated with improvement in penumbral blood flow within 2-24 h after reperfusion along with increased capillary oxygenation, decreased cellular damage and improved functional outcome. Thereby, dynamic microcirculatory stall phenomenon can be a contributing factor to ongoing penumbral injury and is a potential hyperacute mechanism adding on previous observations of detrimental effects of activated neutrophils in ischemic stroke.

Periventricular White Matter Hyperintensity in Males is Associated with Post-Stroke Depression Onset at 3 Months

OBJECTIVE

This study aimed to explore the correlation between white matter hyperintensity (WMH) and post-stroke depression (PSD) at 3 months, and to further investigate sex differences in the pathogenesis of PSD.

METHODS

A total of 238 consecutive patients with acute cerebral infarction were recruited. PSD was assessed at 2 weeks and at 3 months after stroke onset. All stroke cases were divided into four subgroups according to the diagnosis of depression at two time nodes: continuous depression; depression remission; late-onset PSD; and continuous non-depression. The Fazekas and Scheltens visual rating scales were adopted to assess WMH.

RESULTS

Logistic regression revealed that the presence of periventricular white matter hyperintensity (PVWMH) at baseline in male patients was an independent risk factor for PSD at 3 months. Further subgroup analysis revealed that PVWMH was associated with late-onset PSD in males, but not with continuous depression 3 months after stroke. Male acute stroke patients with PVWMH at baseline were more likely to develop PSD at 3 months, especially late-onset PSD.

CONCLUSION

Our data suggest that sex differences may influence the pathogenesis of PSD.

Transcriptome profiling revealed early vascular smooth muscle cell gene activation following focal ischemic stroke in female rats - comparisons with males

Background

Women account for 60% of all stroke deaths and are more often permanently disabled than men, despite their higher observed stroke incidence. Considering the clinical population affected by stroke, an obvious drawback is that many pre-clinical and clinical studies only investigate young males. To improve therapeutic translation from bench to bedside, we believe that it is advantageous to include both sexes in experimental models of stroke. The aims of this study were to identify early cerebral vascular responses to ischemic stroke in females, compare the differential gene expression patterns with those seen in males, and identify potential new therapeutic targets.

Results

Transient middle cerebral artery occlusion (tMCAO) was used to induce stroke in both female and male rats, the middle cerebral arteries (MCAs) were isolated 3 h post reperfusion and RNA was extracted. Affymetrix whole transcriptome expression profiling was performed on female (n = 12) MCAs to reveal differentially expressed genes. In total, 1076 genes had an increased expression and 879 genes a decreased expression in the occluded MCAs as compared with the control MCAs from female rats. An enrichment of genes related to apoptosis, regulation of transcription, protein autophosphorylation, inflammation, oxidative stress, and tissue repair and recovery were seen in the occluded MCA. The high expression genes chosen for qPCR verification (Adamts4, Olr1, JunB, Fosl1, Serpine1, S1pr3, Ccl2 and Socs3) were all shown to be upregulated in the same manner in both females and males after tMCAO (p < 0.05; n = 23). When comparing the differentially expressed genes in female MCAs (occluded and non-occluded) with our previous findings in males after tMCAO, a total of 297 genes overlapped (all groups had 32 genes in common).

Conclusions

The cascades of processes initiated in the vasculature following reperfusion are complex. Dynamic gene expression alterations were observed in the occluded MCAs, and to a less pronounced degree in the non-occluded MCAs. Dysregulation of inflammation and blood-brain barrier breakdown are possible pharmacological targets. The sample of genes (< 1% of the differentially expressed genes) validated for this microarray did not reveal any sex differences. However, sex differences might be observed for other gene targets.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-020-07295-2.

Does the Occurrence of Particular Symptoms and Outcomes of Arterial Ischemic Stroke Depend on Sex in Pediatric Patients?-A Pilot Study

Arterial ischemic stroke (AIS) in childhood is reported to occur more frequently in boys, which may lead to the assumption that the prevalence of post-stroke deficits is sex related. The present study aimed to evaluate sex-related differences in functional outcomes (hemiparesis, seizures, aphasia, and motor disturbances other than hemiparesis) in pediatric patients with AIS. A total of 89 children (52 boys and 37 girls; mean age at stroke onset: 8.4 ± 5.6 years) were evaluated retrospectively based on data from medical records. The patients were divided into subgroups according to age (i.e., infants and toddlers, children, and adolescents), stroke subtype (i.e., lacunar anterior circulation infarct (LACI), total anterior circulation infarct (TACI), partial anterior circulation infarct (PACI), posterior circulation infarct (POCI)) and stroke location (i.e., anterior stroke, posterior stroke). Significant differences in the prevalence of stroke subtypes between girls and boys were observed (p = 0.034). POCI stroke were found to be more frequent in boys than in girls (OR = 8.57 95%CI 1.05–70.23, p = 0.023). Males predominated in the total group and in all analyzed age subgroups. The proportions of boys within the subgroups according to stroke subtype were extremely high for the POCI and TACI stroke subgroups. On the other hand, girls predominated in the LACI stroke subgroup. Frequency of central type facial nerve palsy and other symptoms of AIS were found to significantly differ between male subgroups according to stroke subtype (p = 0.050 and p < 0.001, respectively), as well as between children with anterior stroke and those with posterior stroke (p = 0.059 and p < 0.001, respectively). Post-stroke seizures appeared significantly more commonly in girls with TACI and POCI stroke than in girls with LACI and PACI stroke (p = 0.022). In turn, the prevalence of post-stroke hemiparesis differed between stroke subtypes in boys (p = 0.026). In conclusion, sex may have an impact in predisposing to a certain type of AIS in the patient. Post-stroke seizure may be related to stroke subtype in girls and hemiparesis in boys. However, further studies are needed to confirm the results.

Network Pharmacology-Based Approach to Revealing Biological Mechanisms of Qingkailing Injection against IschemicStroke: Focusing on Blood-Brain Barrier

Ischemic stroke is the most common type of cerebrovascular accident worldwide. It causes long-term disability and death. Qingkailing (QKL) injection is a traditional Chinese patent medicine which has been clinically applied in the treatment of ischemic stroke for nearly thirty years. In the present study, network pharmacology combined with experimentation was used to elucidate the mechanisms of QKL. ADME screening and target prediction identified 62 active compounds and 275 targets for QKL. Topological screening of the protein-protein interaction (PPI) network was used to build a core PPI network consisting of 408 nodes and 17,830 edges. KEGG enrichment indicated that the main signaling pathway implicated in ischemic stroke involved hypoxia-inducible factor-1 (HIF-1). Experimentation showed that QKL alleviated neurological deficits, brain infraction, blood-brain barrier (BBB) leakage, and tight junction degeneration in a mouse ischemic stroke model. Two-photon laser scanning microscopy was used to evaluate BBB permeability and cerebral microvessel structure in living mice. HIF-1α, matrix metalloproteinase-9 (MMP-9), and tight junction proteins such as occludin, zonula occludins-1 (ZO-1), claudin-5, and VE-Cadherin were measured by western blotting. QKL upregulated ZO-1 and downregulated HIF-1α and MMP-9. QKL has a multiapproach, multitarget, and synergistic effect against ischemic stroke.

Structural and Functional Remodeling of the Brain Vasculature Following Stroke

Maintenance of cerebral blood vessel integrity and regulation of cerebral blood flow ensure proper brain function. The adult human brain represents only a small portion of the body mass, yet about a quarter of the cardiac output is dedicated to energy consumption by brain cells at rest. Due to a low capacity to store energy, brain health is heavily reliant on a steady supply of oxygen and nutrients from the bloodstream, and is thus particularly vulnerable to stroke. Stroke is a leading cause of disability and mortality worldwide. By transiently or permanently limiting tissue perfusion, stroke alters vascular integrity and function, compromising brain homeostasis and leading to widespread consequences from early-onset motor deficits to long-term cognitive decline. While numerous lines of investigation have been undertaken to develop new pharmacological therapies for stroke, only few advances have been made and most clinical trials have failed. Overall, our understanding of the acute and chronic vascular responses to stroke is insufficient, yet a better comprehension of cerebrovascular remodeling following stroke is an essential prerequisite for developing novel therapeutic options. In this review, we present a comprehensive update on post-stroke cerebrovascular remodeling, an important and growing field in neuroscience, by discussing cellular and molecular mechanisms involved, sex differences, limitations of preclinical research design and future directions.

Assessment of Sex Differences in Recovery of Motor and Sensory Impairments Poststroke

Background. Understanding potential sex differences in stroke recovery is important for prognosis, ensuring appropriate allocation of health care resources, and for stratification in research studies. Previously, functional measures have shown poorer outcomes for females, however, little is known about sex differences that may exist in specific motor and sensory impairments. Objective. The aim of this study was to utilize robotic assessments of motor and sensory impairments to determine if there are sex differences at the impairment level in stroke recovery over the first 6 months poststroke. Methods. We used robotic and clinical assessments of motor and sensory impairments at 1, 6, 12, and 26 weeks poststroke in 108 males and 52 females. Linear mixed models were used to examine the effect of sex on recovery poststroke, controlling for age and lesion volume. Results. In general, we did not find significant sex differences across a range of assessments. The exception to this was a sex × age interaction for the Purdue Pegboard Assessment, where we found that females had better performance than males at younger ages (<62 years), but males had better performance at older ages. Conclusions. While recruitment biases need to be acknowledged when generalizing our results to stroke recovery at-large, our results suggest that sex differences do not exist at the impairment level poststroke.

Sex differences in T cell immune responses, gut permeability and outcome after ischemic stroke in aged mice

INTRODUCTION

Stroke is a disease that presents with well-known sex differences. While women account for more stroke deaths, recent data show that after adjusting for age and pre-stroke functional status, mortality is higher in men. Immune responses are key determinants of stroke outcome and may differ by sex. This study examined sex differences in central and peripheral T cell immune responses, systemic effects on gut permeability and microbiota diversity and behavioral outcomes after stroke in aged mice. We hypothesized that there are sex differences in the immune response to stroke in aged animals.

METHODS

C57BL/6CR mice (20-22 months) were subjected to 60 min middle cerebral artery occlusion, or sham surgery. T cells were quantified in brain and blood at 3, 7 and 15 days (d) post-stroke by flow cytometry. Peripheral effects on gut permeability and microbiota diversity, as well as neurological function were assessed up to 14 d, and at 21 d (cognitive function) post-stroke. Brain glial fibrillary acidic protein (GFAP) expression was evaluated at 42 d post-stroke.

RESULTS AND DISCUSSION

Mortality (50% vs 14%, p < 0.05) and hemorrhagic transformation (44% vs 0%) were significantly higher in males than in females. No difference in infarct size at 3d were observed. Peripherally, stroke induced greater gut permeability of FITC-dextran in males at d3 (p < 0.05), and non-reversible alterations in microbiota diversity in males. Following the sub-acute phase, both sexes demonstrated a time-dependent increase of CD4⁺ and CD8⁺ T cells in the brain, with significantly higher levels of CD8⁺ T cells and Regulatory T cells in males at d15 (p < 0.01). Aged males demonstrated greater neurological deficits up to d5 and impaired sensorimotor function up to d15 when assessed by the corner asymmetry test (p < 0.001 and p < 0.01, respectively). A trend in greater cognitive decline was observed at d21 in males. Increased GFAP expression in the ischemic hemisphere, indicating astroglial activation and gliosis, was demonstrated in both males and females 42d post-stroke. Our findings indicate that despite a similar initial ischemic brain injury, aged male mice experience greater peripheral effects on the gut and ongoing central neuroinflammation past the sub-acute phase after stroke.

Sex Differences in Cognitive Impairment Induced by Cerebral Microhemorrhage

It has been suggested that cerebral microhemorrhages (CMHs) could be involved in cognitive decline. However, little is known about the sex-dependency of this effect. Using a multimodal approach combining behavioral tests, in vivo imaging, biochemistry, and molecular biology, we studied the cortical and hippocampal impact of a CMH in male and female mice (C57BL/6J) 6 weeks post-induction using a collagenase-induced model. Our work shows for the first time that a single cortical CMH exerts sex-specific effects on cognition. It notably induced visuospatial memory impairment in males only. This sex difference might be explained by cortical changes secondary to the lesion. In fact, the CMH induced an upregulation of ERα mRNA only in the female cortex. Besides, in male mice, we observed an impairment of pathways associated to neuronal, glial, or vascular functions: decrease in the P-GSK3β/GSK3β ratio, in BDNF and VEGF levels, and in microvascular water mobility. The CMH also exerted spatial remote effects in the hippocampus by increasing the number of astrocytes in both sexes, increasing the mean area occupied by each astrocyte in males, and decreasing hippocampal BDNF in females suggesting a cortical-hippocampal network impairment. This work demonstrates that a CMH could directly affect cognition in a sex-specific manner and highlights the need to study both sexes in preclinical models.

Gender and functional outcomes in prestroke depressive patients treated with thrombolytic therapy

Aim: This study investigated the clinical factors associated with functional ambulatory outcomes and gender differences in prestroke depressive patients. Materials & methods: Clinical risk factors associated with improved functional outcomes with recombinant tissue plasminogen activator-treated cohorts were determined using binary logistic regression. Results: In the adjusted analysis, improvement in ambulation was associated with male patients that had higher National Institute of Health stroke scale score (p = 0.04), a stroke history (p = 0.026), lower serum creatinine levels (p = 0.049) and were taking cholesterol reducing medication (p = 0.014). Improvement in females was associated with taking antidepressants (p = 0.027) and having lower National Institute of Health stroke scale score (p = 0.002). Conclusion: Our findings indicate gender disparities between male and female prestroke depressive patients.

Blood Vitronectin Induces Detrimental Brain Interleukin-6 and Correlates With Outcomes After Stroke Only in Female Mice

Background and Purpose- Women have worse stroke outcomes than men, especially after menopause. Few studies have focused on female-specific mechanisms, other than hormones. We investigated the role of the blood protein VTN (vitronectin) after ischemic stroke in mice. Methods- Adult male and female VTN knockout and wild-type littermates and C57BL/6 mice received a middle cerebral artery occlusion and the injured brain tissue analyzed 24 hours to 3 weeks later for cell loss and inflammation, as well as neurological function. Blood VTN levels were measured before and after stroke. Results- Intravenously injected VTN leaked extensively from bloodstream into brain infarct and penumbra by 24 hours after stroke. Strikingly, VTN was detrimental in female, but not male, mice, as shown by reduced brain injury (26.2±2.6% versus 13.4±3.8%; P=0.018; n=6 and 5) and forelimb dysfunction in female VTN knockout mice. Stroke increased plasma VTN 2- to 8-fold at 24 hours in females (36±4 versus 145±24 μg/mL; P<0.0001; n=10 and 7), but not males (62±8 versus 68±6; P>0.99; n=10 and 7), and returned to control levels by 7 days. Individually variable VTN levels at 24 hours correlated with stroke-induced brain injury at 7 days only in females. VTN promoted stroke-induced microglia/macrophage activation and leukocyte infiltration in females. Proinflammatory IL (interleukin)-6 greatly increased in the striatum at 24 hours in wild-type mice but was increased ≈60% less in female (739±159 versus 268±111; P=0.02; n=7 and 6), but not male (889±178 versus 1179±295; P=0.73; n=10 and 11), knockout mice. In individual wild-type females, plasma VTN levels correlated with striatal IL-6 expression at 24 hours. The female-specific effect of VTN-induced IL-6 expression following stroke was not due to gonadal hormones, as shown by ovariectomy and castration. Lastly, intrastriatal injection of IL-6 in female mice immediately before stroke reversed the VTN knockout phenotypes of reduced brain injury and microglia/macrophage activation. Conclusions- VTN plays a novel sexually dimorphic detrimental pathophysiological role in females and might ultimately be a therapeutic target to improve stroke outcomes in women.

Insight into the molecular sex dimorphism of ischaemic stroke in rat cerebral cortex: Focus on neuroglobin, sex steroids and autophagy

Including sex is of paramount importance in preclinical and clinical stroke researches, and molecular studies dealing in depth with sex differences in stroke pathophysiology are needed. To gain insight into the molecular sex dimorphism of ischaemic stroke in rat cerebral cortex, male and female adult rats were subjected to transient middle cerebral artery occlusion. The expression of neuroglobin (Ngb) and other functionally related molecules involved in sex steroid signalling (oestrogen and androgen receptors), steroidogenesis (StAR, TSPO and aromatase) and autophagic activity (LC3B-II/LC3B-I ratio, UCP2 and HIF-1α) was assessed in the ipsilateral ischaemic and contralateral non-ischaemic hemispheres. An increased expression of Ngb was detected in the injured female cerebral cortex. In contrast, increased expression of oestrogen receptor α, GPER, StAR, TSPO and UCP2, and decreased androgen receptor expression were detected in the injured male cortex. In both sexes, the ischaemic insult induced an upregulation of LC3B-II/-I ratio, indicative of increased autophagy. Therefore, the cerebral cortex activates both sex-specific and common molecular responses with neuroprotective potential after ischaemia-reperfusion, which globally results in similar stroke outcome in both sexes. Nonetheless, these different potential molecular targets should be taken into account when neuroprotective drugs aiming to reduce brain damage in ischaemic stroke are investigated.

C3a receptor antagonist therapy is protective with or without thrombolysis in murine thromboembolic stroke

BACKGROUND AND PURPOSE

Intravenous thrombolysis (IVT) after stroke enhances C3a generation, which may abrogate the benefits of reperfusion. The C3aR antagonist SB290157 is neuroprotective following transient but not permanent middle cerebral artery occlusion (MCAo). SB290157 remains untested in thromboembolic (TE) models, which better approximate human stroke and also facilitate testing in combination with IVT. We hypothesized SB290157 would confer neuroprotection in TE stroke with and without "late" IVT.

EXPERIMENTAL APPROACH

We used two different models of TE stroke to examine the efficacy of SB290157 alone and in combination with late IVT. We evaluated the benefit of SB290157 in attenuating post-ischaemic behavioural deficits, infarction, brain oedema and haemorrhage.

KEY RESULTS

Plasma C3a was elevated 6 hr after TE stroke alongside increased cerebrovascular C3aR expression, which was sustained to 4 weeks. Increased C3aR expression also was visualized in human ischaemic brain. In a photothrombotic (PT) stroke model, which exhibits rapid spontaneous reperfusion, SB290157 given at 1 hr post-PT significantly improved neurofunction and reduced infarction at 48 hr. In an embolic (eMCAo) model, SB290157 administered at 2 hr improved histological and functional outcomes. Conversely, late IVT administered 4.5 hr post-eMCAo was ineffective likely due to increased haemorrhage and brain oedema. However, SB290157 administered prior to late IVT ameliorated haemorrhage and oedema and improved outcomes.

CONCLUSIONS AND IMPLICATIONS

We conclude that SB290157 is safe and effective with and without late IVT following TE stroke. Therefore, C3a receptor antagonist therapy represents a promising candidate for clinical translation in stroke, particularly as an adjuvant to IVT.

Transplantation of Directly Reprogrammed Human Neural Precursor Cells Following Stroke Promotes Synaptogenesis and Functional Recovery

Stroke is one of the leading causes of long-term disability. Cell transplantation is a promising strategy to treat stroke. We explored the efficacy of directly reprogrammed human neural precursor cell (drNPC) transplants to promote functional recovery in a model of focal ischemic stroke in the mouse sensorimotor cortex. We show that drNPCs express neural precursor cell markers and are neurally committed at the time of transplantation. Mice that received drNPC transplants recovered motor function, irrespective of transplant vehicle or recipient sex, and with no correlation to lesion volume or glial scarring. The majority of drNPCs found in vivo, at the time of functional recovery, remained undifferentiated. Notably, no correlation between functional recovery and long-term xenograft survival was observed, indicating that drNPCs provide therapeutic benefits beyond their survival. Furthermore, increased synaptophysin expression in transplanted brains suggests that drNPCs promote neuroplasticity through enhanced synaptogenesis. Our findings provide insight into the mechanistic underpinnings of drNPC-mediated recovery for stroke and support the notion that drNPCs may have clinical applications for stroke therapy.

The impact of sex and age on T cell immunity and ischemic stroke outcomes

Sex differences are well-recognized in ischemic stroke, a disease mainly affecting the elderly. Stroke results in robust activation of central and peripheral immune responses which contributes to functional outcome. Aging is associated with increased low-grade chronic inflammation known as "inflammaging" that renders aged males and females more susceptible to poor outcomes after ischemic stroke. Despite the fact that sex differences are well-documented in immunity and inflammation, few studies have focused on sex differences in inflammatory responses after ischemic stroke and even fewer have been performed in the context of aging. The role of T cell responses in ischemic stroke have gained increasing attention over the past decade as data suggest a major role in the pathophysiology/recovery after ischemic injury. T cells offer an attractive therapeutic target due to their relatively delayed infiltration into the ischemic brain. This review will focus on T cell immune responses in ischemic stroke, highlighting studies examining the effects of aging and biological sex.

PDGFR-β modulates vascular smooth muscle cell phenotype via IRF-9/SIRT-1/NF-κB pathway in subarachnoid hemorrhage rats

Platelet-derived growth factor receptor-β (PDGFR-β) has been reported to promote phenotypic transformation of vascular smooth muscle cells (VSMCs). The purpose of this study was to investigate the role of the PDGFR-β/IRF9/SIRT-1/NF-κB pathway in VSMC phenotypic transformation after subarachnoid hemorrhage (SAH). SAH was induced using the endovascular perforation model in Sprague-Dawley rats. PDGFR-β small interfering RNA (siRNA) and IRF9 siRNA were injected intracerebroventricularly 48 h before SAH. SIRT1 activator (resveratrol) and inhibitor (EX527) were administered intraperitoneally 1 h after SAH induction. Twenty-four hours after SAH, the VSMC contractile phenotype marker α-smooth muscle actin (α-SMA) decreased, whereas the VSMC synthetic phenotype marker embryonic smooth muscle myosin heavy chain (Smemb) increased. Both PDGFR-β siRNA and IRF9 siRNA attenuated the induction of nuclear factor-κB (NF-κB) and enhanced the expression of α-SMA. The SIRT1 activator (resveratrol) preserved VSMC contractile phenotype, significantly alleviated neurological dysfunction, and reduced brain edema. However, these beneficial effects of PDGFR-β siRNA, IRF9 siRNA and resveratrol were abolished by the SIRT1 inhibitor (EX527). This study shows that PDGFR-β/IRF9/SIRT-1/NF-κB signaling played a role in the VSMC phenotypic transformation after SAH. Inhibition of this signaling cascade preserved the contractile phenotype of VSMCs, thereby improving neurological outcomes following SAH.

Rh-IFN-α attenuates neuroinflammation and improves neurological function by inhibiting NF-κB through JAK1-STAT1/TRAF3 pathway in an experimental GMH rat model

Neuroinflammation occurs after germinal matrix hemorrhage (GMH) and induces secondary brain injury. Interferon-α (IFN-α) has been shown to exert anti-inflammatory effects in infectious diseases via activating IFNAR and its downstream signaling. We aimed to investigate the anti-inflammatory effects of Recombinant human IFN-α (rh-IFN-α) and the underlying mechanisms in a rat GMH model. Two hundred and eighteen P7 rat pups of both sexes were subjected to GMH by an intraparenchymal injection of bacterial collagenase. Rh-IFN-α was administered intraperitoneally. Small interfering RNA (siRNA) of IFNAR, and siRNA of tumor necrosis factor receptor associated factor 3 (TRAF3) were administered through intracerebroventricular (i.c.v.) injections. JAK1 inhibitor ruxolitinib was given by oral lavage. Post-GMH evaluation included neurobehavioral function, Nissl staining, Western blot analysis, and immunofluorescence. Our results showed that endogenous IFN-α and phosphorylated IFNAR levels were increased after GMH. Administration of rh-IFN-α improved neurological functions, attenuated neuroinflammation, inhibited microglial activation, and ameliorated post-hemorrhagic hydrocephalus after GMH. These observations were concomitant with IFNAR activation, increased expression of phosphorylated JAK1, phosphorylated STAT1 and TRAF3, and decreased levels of phosphorylated NF-κB, IL-6 and TNF-α. Specifically, knockdown of IFNAR, JAK1 and TRAF3 abolished the protective effects of rh-IFN-α. In conclusion, our findings demonstrated that rh-IFN-α treatment attenuated neuroinflammation, neurological deficits and hydrocephalus formation through inhibiting microglial activation after GMH, which might be mediated by IFNAR/JAK1-STAT1/TRAF3/NF-κB signaling pathway. Rh-IFN-α may be a promising therapeutic agent to attenuate brain injury via its anti-inflammatory effect.

Sex Differences in Ischemia/Reperfusion Injury: The Role of Mitochondrial Permeability Transition

Brain and heart ischemia are among the leading causes of death and disability in both men and women, but there are significant sex differences in the incidence and severity of these diseases. Ca²⁺ dysregulation in response to ischemia/reperfusion injury (I/RI) is a well-recognized pathogenic mechanism leading to the death of affected cells. Excess intracellular Ca²⁺ causes mitochondrial matrix Ca²⁺ overload that can result in mitochondrial permeability transition (MPT), which can have severe consequences for mitochondrial function and trigger cell death. Recent findings indicate that estrogens and their related receptors are involved in the regulation of MPT, suggesting that sex differences in I/RI could be linked to estrogen-dependent modulation of mitochondrial Ca²⁺. Here, we review the evidence supporting sex differences in I/RI and the role of estrogen and estrogen receptors in producing these differences, the involvement of mitochondrial Ca²⁺ overload in disease pathogenesis, and the estrogen-dependent modulation of MPT that may contribute to sex differences.

Sex-Based Differences in Symptom Perception and Care-Seeking Behavior in Acute Stroke

CONTEXT

Lack of early stroke recognition and delays in seeking emergency care by persons experiencing a stroke severely limit acute treatment options. Sparse and sometimes conflicting evidence suggests sex differences in care-seeking behaviors in stroke, stroke knowledge, perceptions of stroke symptoms, and the importance of physical location at the time of stroke and of having a witnessed stroke.

OBJECTIVE

To explore specific sex-based differences in stroke presentation and associated care-seeking behaviors.

DESIGN

Descriptive study based on a convenience sample of 60 patients with stroke admitted to an academic medical center in Northern California.

MAIN OUTCOME MEASURES

Impact of the patient's sex on 1) time to presentation (early [≤ 4.5 hours] vs late [> 4.5 hours]); 2) perception of symptoms and clinical signs; 3) stroke knowledge and decision making; 4) physical location at the time of stroke; and 5) bystander presence and assistance with decision making.

RESULTS

There was a discrepancy between how patients perceive symptoms and their medical findings on physical examination. Although most patients had at least one sign or symptom associated with nationally used stroke recognition acronyms, both sexes delayed care because they did not perceive their symptoms as urgent. Early-presenting men were more likely to have a higher stroke severity score at admission, receive alteplase, arrive by Emergency Medical Services, and have a witnessed stroke. Both early- and late-presenting women reported more nonfocal symptoms than did men.

CONCLUSION

This study suggests that there are sex-based differences in symptom perception and care-seeking behavior in acute ischemic stroke.

Stroke and the neurovascular unit: glial cells, sex differences, and hypertension

A functional neurovascular unit (NVU) is central to meeting the brain's dynamic metabolic needs. Poststroke damage to the NVU within the ipsilateral hemisphere ranges from cell dysfunction to complete cell loss. Thus, understanding poststroke cell-cell communication within the NVU is of critical importance. Loss of coordinated NVU function exacerbates ischemic injury. However, particular cells of the NVU (e.g., astrocytes) and those with ancillary roles (e.g., microglia) also contribute to repair mechanisms. Epidemiological studies support the notion that infarct size and recovery outcomes are heterogeneous and greatly influenced by modifiable and nonmodifiable factors such as sex and the co-morbid condition common to stroke: hypertension. The mechanisms whereby sex and hypertension modulate NVU function are explored, to some extent, in preclinical laboratory studies. We present a review of the NVU in the context of ischemic stroke with a focus on glial contributions to NVU function and dysfunction. We explore the impact of sex and hypertension as modifiable and nonmodifiable risk factors and the underlying cellular mechanisms that may underlie heterogeneous stroke outcomes. Most of the preclinical investigative studies of poststroke NVU dysfunction are carried out primarily in male stroke models lacking underlying co-morbid conditions, which is very different from the human condition. As such, the evolution of translational medicine to target the NVU for improved stroke outcomes remains elusive; however, it is attainable with further research.