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Effects of sex hormones on stroke outcome is 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 following organ culture in vitro, a model of vasocontractile receptor upregulation. Female rats with intact ovaries and ovariectomized females treated with 17β-estradiol, progesterone or placebo were subjected to transient, unilateral middle cerebral artery occlusion followed reperfusion (I/R). The maximum contractile response, measured my wire myography, in response to the endothelin B (ETB) receptor agonist sarafotoxin 6c was increased in female arteries after I/R, but the maximum response was significantly lower in arteries from ovariectomized females. Maximum contraction mediated by the serotonin agonist 5-carboxamidotryptamine (5-CT) was diminished after I/R, with arteries from ovariectomized 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 ovariectomized females affected I/R-induced changes in ETB and 5-CT induced vasocontraction. These findings suggest sex hormones do not directly influence vasocontractile alterations that occur after ischemic stroke; however, loss of ovarian function does impact this process.

BACKGROUND: After subarachnoid hemorrhage (SAH), early brain injury (EBI) and delayed cerebral ischemia (DCI) lead to poor outcomes. Discovery of biomarkers indicative of disease severity and predictive of DCI is important. We tested whether leucine-rich alpha-2-glycoprotein 1 (LRG1) is a marker of severity, DCI, and functional outcomes after SAH. METHODS: We performed untargeted proteomics using mass spectrometry in plasma samples collected at < 48 h of SAH in two independent discovery cohorts (n = 27 and n = 45) and identified LRG1 as a biomarker for DCI. To validate our findings, we used enzyme-linked immunosorbent assay and confirmed this finding in an internal validation cohort of plasma from 72 study participants with SAH (22 DCI and 50 non-DCI). Further, we investigated the relationship between LRG1 and markers of EBI, DCI, and poor functional outcomes (quantified by the modified Rankin Scale). We also measured cerebrospinal fluid (CSF) levels of LRG1 and investigated its relationship to EBI, DCI, and clinical outcomes. RESULTS: Untargeted proteomics revealed higher plasma LRG1 levels across EBI severity and DCI in both discovery cohorts. In the validation cohort, the levels of LRG1 were higher in the DCI group compared with the non-DCI group (mean (SD): 95 [44] vs. 72 [38] pg/ml, p < 0.05, Student’s t-test) and in study participants who proceeded to have poor functional outcomes (84 [39.3] vs. 72 [43.2] pg/ml, p < 0.05). Elevated plasma LRG1 levels were also associated with markers of EBI. However, CSF levels of LRG1 were not associated with EBI severity or the occurrence of DCI. CONCLUSIONS: Plasma LRG1 is a biomarker for EBI, DCI, and functional outcomes after SAH. Further studies to elucidate the role of LRG1 in the pathophysiology of SAH are needed.

INTRODUCTION: Stroke is a sexually dimorphic disease. 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/6N 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 14d, and at 21d (cognitive function) post-stroke. Brain glial fibrillary acidic protein (GFAP) expression was evaluated at 42d post-stroke. RESULTS AND DISCUSSION: Mortality (50% vs 14%, p

Background: Ischemic stroke is a devastating disease, often resulting in death or permanent neurological deficits. EMMPRIN/CD147 is a plasma membrane protein that induces the production of matrix metalloproteinases (MMPs), which contribute to secondary damage after stroke by disrupting the blood brain barrier (BBB) and facilitating peripheral leukocyte infiltration into the brain. Results: CD147 surface expression increased significantly after stroke on infiltrating leukocytes, astrocytes and endothelial cells, but not on resident microglia. Inhibition of CD147 reduced MMP levels, decreased ischemic damage, and improved functional, cognitive and histological outcomes after experimental ischemic stroke in both young and aged mice. In stroke patients, high levels of serum CD147 24 hours after stroke predicted poor functional outcome at 12 months. Brain CD147 levels were correlated with MMP-9 and secondary hemorrhage in post-mortem samples from stroke patients. Conclusions: Acute inhibition of CD147 decreases levels of MMP-9, limits tissue loss, and improves long-term cognitive outcomes following experimental stroke in aged mice. High serum CD147 correlates with poor outcomes in stroke patients. This study identifies CD147 as a novel, clinically relevant target in ischemic stroke.

Objective Although COVID-19 is a respiratory disease, all organs can be affected including the brain. To date, specific investigations of brain injury markers (BIM) and endothelial injury markers (EIM) have been limited. Additionally, a male bias in disease severity and mortality after COVID-19 is evident globally. Sex differences in the immune response to COVID-19 may mediate this disparity. We investigated BIM, EIM and inflammatory cytokine/chemokine (CC) levels after COVID-19 and in across sexes. Methods Plasma samples from 57 subjects at Results Three BIMs: MAP2, NSE and S100B, two EIMs: sICAM1 and sVCAM1 and seven CCs: GRO IL10, sCD40L, IP10, IL1Ra, MCP1 and TNFα were significantly (p p Conclusion The acute elevation of BIMs, CCs, and EIMs and the robust associations among them at COVID-19 hospitalization are suggestive of brain and endothelial injury. Higher BIM and inflammatory markers in men additionally suggest that men are more susceptible to the risk compared to women.

Ischemic stroke is major cause of disability and mortality worldwide, and aging is strong risk factor for poor post-stroke outcome. Neutrophils traffic rapidly to the brain following ischemic stroke, and recent evidence has suggested that aging may alter neutrophil function after tissue injury. In this study, we hypothesize that aging enhances the pro-inflammatory function of neutrophils, directly contributing to the poorer outcomes seen in aging patients. We utilized demographic data and biological specimens from ischemic stroke patients and an experimental mouse model to determine the correlation between age, neutrophil function and stroke outcomes. In ischemic stroke patients, age was associated with increased mortality and morbidity and higher levels of neutrophil-activating cytokines. In mice, aged animals had higher stroke mortality and morbidity, higher levels of neutrophil-activating cytokines and enhanced generation of neutrophil reactive oxygen species compared to young mice. Finally, depletion of neutrophils via a specific monoclonal antibody after ischemic stroke led to long-term benefits in functional outcome in aged male and female animals, with no benefit observed in young. These results demonstrate that aging is associated with augmented neutrophil pathogenicity in ischemic stroke, and that neutrophil-targeted therapies may confer greater benefit in aged subjects.

ObjectiveTo investigate brain injury markers (BIM), endothelial injury markers (EIM) and cytokine/chemokine (CC) markers of systemic inflammation in coronavirus disease 2019 (COVID-19) and across sex.MethodsPlasma samples from 57 subjects at ResultsThree BIMs: MAP2, NSE and S100B, two EIMs: sICAM1 and sVCAM1 and seven CCs: GRO IL10, sCD40L, IP10, IL1Ra, MCP1 and TNFα were significantly (pConclusionThe acute elevation of BIMs, CCs, and EIMs and the robust associations among them at COVID-19 hospitalization suggest that brain injury is mediated by endotheliopathy and inflammation. Higher BIM and inflammatory markers in men additionally suggest that men are more susceptible to the risk compared to women.

Introduction Sex is increasingly recognized as an important factor in the epidemiology and outcome of many diseases. This also appears to hold for coronavirus disease 2019 (COVID-19). Evidence from China and Europe has suggested that mortality from COVID-19 infection is higher in men than women, but evidence from US populations is lacking. Utilizing data from a large healthcare provider, we determined if males, as compared to females have a higher likelihood of SARS-CoV-2 susceptibility, and if among the hospitalized COVID-19 patients, male sex is independently associated with COVID-19 severity and poor in-hospital outcomes. Methods and findings Using the Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) guidelines, we conducted a cross-sectional analysis of data from a COVID-19 Surveillance and Outcomes Registry (CURATOR). Data were extracted from Electronic Medical Records (EMR). A total of 96,473 individuals tested for SARS-CoV-2 RNA in nasopharyngeal swab specimens via Polymerized Chain Reaction (PCR) tests were included. For hospital-based analyses, all patients admitted during the same time-period were included. Of the 96,473 patients tested, 14,992 (15.6%) tested positive, of whom 4,785 (31.9%) were hospitalized and 452 (9.5%) died. Among all patients tested, men were significantly older. The overall SARS-CoV-2 positivity among all tested individuals was 15.5%, and was higher in males as compared to females 17.0% vs. 14.6% [OR 1.20]. This sex difference held after adjusting for age, race, ethnicity, marital status, insurance type, median income, BMI, smoking and 17 comorbidities included in Charlson Comorbidity Index (CCI) [aOR 1.39]. A higher proportion of males (vs. females) experienced pulmonary (ARDS, hypoxic respiratory failure) and extra-pulmonary (acute renal injury) complications during their hospital course. After adjustment, length of stay (LOS), need for mechanical ventilation, and in-hospital mortality were significantly higher in males as compared to females. Conclusions In this analysis of a large US cohort, males were more likely to test positive for COVID-19. In hospitalized patients, males were more likely to have complications, require ICU admission and mechanical ventilation, and had higher mortality than females, independent of age. Sex disparities in COVID-19 vulnerability are present, and emphasize the importance of examining sex-disaggregated data to improve our understanding of the biological processes involved to potentially tailor treatment and risk stratify patients.

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.

Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau. Subsequent tau mislocalization causes neurodegeneration and neurobehavioral impairment, and ac-tau accumulates in the blood. Blocking GAPDH S-nitrosylation, inhibiting p300/CBP, or stimulating Sirtuin1 all protect mice from neurodegeneration, neurobehavioral impairment, and blood and brain accumulation of ac-tau after TBI. Ac-tau is thus a therapeutic target and potential blood biomarker of TBI that may represent pathologic convergence between TBI and AD. Increased ac-tau in human AD brain is further augmented in AD patients with history of TBI, and patients receiving the p300/CBP inhibitors salsalate or diflunisal exhibit decreased incidence of AD and clinically diagnosed TBI.

Objective: We characterized the vasodilatory effects of ANP, BNP, and CNP in human subcutaneous arterioles in vitro and the cutaneous microcirculation in vivo. Methods: The in vitro experiments were performed using wire myography and the responses were characterized by the use of inhibitors for nitric oxide (L-NAME), prostaglandin synthesis (indomethacin), or the endothelium-derived hyperpolarization factor. In vivo, the vasorelaxant effect of iontophoretically administrated BNP or CNP was measured with a noninvasive laser Doppler technique. Involvement of nitric oxide or prostaglandins was assessed by L-NAME or indomethacin given by iontophoresis. Results: In vitro all three peptides showed significant vasodilatation with the efficacy order: CNP > BNP = ANP. The BNP-induced vasodilatation, but not that of ANP or CNP, was significantly reduced by pretreatment with indomethacin or L-NAME. In vivo administration of BNP induced a marked vasodilatory response that was attenuated by local pretreatment of L-NAME. Indomethacin by itself resulted in increased cutaneous perfusion. Conclusions: NPs are potent vasodilators in the human subcutaneous circulation. The response to BNP differs from that of the other peptides as it seems dependent on cyclooxygenase products and nitric oxide. (Less)

Human aging is characterized by chronic, low-grade inflammation, a phenomenon termed “inflammaging”. Aging is a non-modifiable risk factor for stroke and inflammatory processes are a major contributor to ischemic brain damage. Mast cell (MC) degranulation and the subsequent release of histamine (HA) may contribute to chronic inflammation, BBB leakage and neutrophil accumulation. Over the past decade, the histaminergic system has been implicated in the modulation of cell death in brain disorders including stroke. However, the exact mechanisms underlying HA actions on ischemia-induced damage have not yet been defined. Stroke leads to gut dysfunction and dysbiosis, which might trigger MC infiltration. Since previous studies have shown that the gut/microbiome has a significant impact on stroke outcomes, we hypothesized that stroke increases HA levels, histamine receptors (HR) and MC infiltration in the gut leading to gut barrier breakdown further contributing to post-stroke inflammation (PSI) and damage. Methods: Aged (Ag) C57BL/6 (20-22 months old) and young (Yg) (3 months old) male mice were subjected to 60 min transient middle cerebral artery occlusion (MCAO) or sham surgery. Mice were sacrificed after 6-hours (h), 12-h, 24-h, 3-days (d) and 7-d post-MCAO. Brain, blood, gut and spleen were harvested and used for flow cytometry, mRNA and immunohistochemistry (IHC) before behavior analysis. Luminal contents were collected and subjected to 16s sequencing and metabolomics analysis. Results: Stroke increased HR2 expression in the intestine of 7-d PS Ag mice compared to the Ag controls. HA levels in Ag brain and blood was 2-fold higher than in Yg mouse at 6-h after stroke and remained high at 24-h. In addition, locomotor activity was significantly reduced in post stroke mice. Increased MCs were seen in the gut of PS compared to control mice. The protective gut mucus layer was depleted with increased HR activation and with a pro-inflammatory bio-marker elevation. This was correlated with imbalanced gut microbiota. This work suggests that there is a role of gut HR and systemic HA in modulating brain health. Controlling HA release and suppressing HR activation in the periphery especially in the gut PS might improve recovery after stroke.

The prevalence of cardiovascular disease has increased among middle-aged women in the United States, yet has declined in middle-aged men. In experimental stroke, middle-aged females have larger strokes and greater inflammation than age-matched males or younger females. The mechanism underlying this shift from an “ischemia-protected” to an “ischemia-sensitive” phenotype in aging females is unknown. One potential factor is an age-related increase in systemic factors that induce inflammation. Increased abdominal fat deposition is seen in women during middle age. Adipose tissue plays a key role in obesity-induced systemic inflammation, including increased pro-inflammatory cytokines. We hypothesized that age and sex differences in adipose immune cells promote an augmented pro-inflammatory milieu in middle-aged females driven by a balance shift between pro-inflammatory and anti-inflammatory T cells. Abdominal adipose tissue immune cells from young (3–4 months) and middle-aged (15–16 months) male and female C57BL/6J mice were analyzed by flow cytometry. Plasma triglyceride (TG), high-density lipoprotein (HDL), and low-density lipoprotein (LDL) levels were determined with colorimetric assays. Middle-aged mice had higher adipose tissue mass compared to young mice. Lipid profiling showed no sex differences in TG and LDL, but middle-aged females had lower HDL (0.84 ± 0.07 μg/μl) than middle-aged males (1.35 ± 0.06 μg/μl). Flow cytometry data demonstrated an age-associated increase in adipose tissue CD8+ T cells that was augmented by female sex, with middle-aged females having a higher percentage of CD8+ cells (34.4 ± 3.2% of CD3+ T cells) than middle-aged males (24.4 ± 2.2%). This increase in CD8+ T-cell proportion was adipose tissue-specific, as this change was not observed in blood. Middle-aged females had higher numbers of activated (CD69+) CD8+ T cells than males. In addition, female CD8+ T cells produced higher levels of IFN-γ, TNF-α, and granzyme B ex vivo, and females had higher adipose levels of IFN-γ, RANTES and MIP-1β than middle-aged males. In parallel, females had lower levels of regulatory T cells (Tregs), an anti-inflammatory T-cell subtype, compared to age-matched males. In conclusion, middle-aged females have a detrimental combination of elevated pro-inflammatory T cells and decreased anti-inflammatory Tregs in adipose tissue, which may promote a pro-inflammatory milieu and contribute to increased cardiovascular disease burden in aging females.

Stroke is the second leading cause of death worldwide, and differences between men and women have been documented in incidence, prevalence, and outcome. Here, we reviewed the literature on sex differences in stroke severity, mortality, functional outcome, and response to therapies after ischemic stroke. Many of the sex differences in stroke severity and mortality are explained by differences in baseline demographics such as older age in women. However, women account for more stroke deaths, consistently suffer from worse stroke outcomes, and are more often institutionalized and permanently disabled than men. These sex differences in functional outcome are equalized after treatment with tissue plasminogen activator (tPA) and women may benefit more from treatment than men. However, this may depend on race, as African-American women have less of a response to tPA than other groups. Regarding endovascular treatments, the few existing studies that have investigated sex differences in stroke outcome point to equal benefit in both sexes; however, many clinical trials are relatively underpowered to detect sex differences. Further, we considered sex-specific effects in animal models of stroke and present recommendations for the performance of stroke studies in female animals. The male-biased use of research animals is distinguished from the clinical situation where there is a disproportionate and growing female stroke population. Stroke in women is greatly understudied, and including both sexes is especially important in both preclinical and clinical studies that evaluate potential stroke therapies.

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.

Background and Purpose: Age and sex have important effects on stroke-induced inflammation. We conducted CBC analysis and RNA-sequencing of ischemic stroke patient blood, with follow-up studies in an experimental mouse model, to test the hypothesis that there are sex differences in neutrophil function and neutrophil-mediated damage after ischemic stroke. Methods: Blood from male and female stroke patients was collected 24 hours after stroke, with transient ischemic attack patients serving as controls. Absolute neutrophil count was quantified and RNA-sequencing was performed on an age and severity matched subset of patients. Results were analyzed by multivariate regression and differential expression analysis, respectively. For animal experiments, aged (18-20 month) and young (8-10 week) male and female mice were subjected to 60 minute middle cerebral artery occlusion and sacrificed at 24 hours. Neutrophils from blood, bone marrow, lung, brain and spleen were quantified and phenotyped by flow cytometry. Results were analyzed by student T-test and two way ANOVA. Results: Absolute neutrophil counts increased significantly after stroke in both sexes (p=.01). Interestingly, females had more differentially expressed genes after stroke than males, including matrix metalloproteinase 9 and TNFa. In animal experiments, aged animals were found to have higher percentages of neutrophils in the blood, spleen, lungs and bone marrow than young animals. In addition, aged female animals were found to have more activated neutrophils 24 hours after stroke than aged males (p= Conclusion: These results suggest that the immune response to ischemic stroke differs in aged males and females. Female neutrophils appear to exhibit enhanced activation, which may contribute to the poorer stroke outcomes seen in aged female patients. Understanding sex and age differences in the acute immune response is crucial to developing future immunomodulatory drugs for the safe and effective treatment of ischemic stroke in both sexes.

Respiratory dysfunction is a common complication of stroke, with an incidence more than 60%, leading to prolonged recovery and increased mortality. Despite the high prevalence of stroke induced respiratory dysfunction (SIRD) little is known regarding how SIRD influences recovery and cognitive outcomes after ischemic stroke. Studies in non-stroke populations have shown that individuals with respiratory dysfunction are drastically more likely to develop cognitive impairment. We propose stroke will induce chronic respiratory dysfunction, instability, and apnea in mice, which are linked to higher mortality and greater post-stroke cognitive deficits. Respiratory dysfunction will be related to progressive cognitive decline following middle cerebral artery occlusion (MCAo) that is worse in aged mice. Whole body plethysmography was performed on C57/B6 young (2-3 month)/aged (20 month) male mice to establish baseline frequency (BPM), tidal volume, minute ventilation and apnea frequency. Animals were exposed to a variety of gas conditions to assess the contribution of peripheral and central chemoreceptors. Mice were subjected to 60 MCAO, producing chronic respiratory dysfunction, instability and apnea, or sham surgery. Days 3, 7 and weekly thereafter plethysmography and a variety of cognitive tests were performed to track respiratory dysfunction and progressive cognitive decline. Young and aged mice displayed hypoventilation (young stroke 181.4±22 vs. sham 264±35 bpm p5 apneas/min N=3). Mice with minor apneas perform better in a variety of cognitive tests. Fear conditioning (freezing behavior minor 1.47±.24s/event vs. mod .74±.07s/event, p=.02), Barnes maze: Escape time minor 158.5±35.2 sec vs. 217.9±82. NORT: ratio time novel/familiar object minor 2.2±.6 vs. 1.1±.3. Suggesting incidence of apneas as an indicator of cognitive decline. Therefore, the treatment of respiratory instability is a viable prospect to improve cognitive outcomes.

Introduction: Sex differences are increasingly recognized in stroke. Stroke incidence is higher in men than in women until an advanced age and women have higher mortality and morbidity. Inflammatory responses are key determinants of outcome but have not been well studies in aged animals. Hypothesis: We hypothesize that there are important sex differences in inflammation in aged male and female mice. Results: We quantified T cells and T regulatory cells, as well as functional outcome after stroke in aged mice. Male and female C57BL/6 mice (20-21 months) were subjected to 60 min middle cerebral artery occlusion (n=16) by the filament model, or sham surgery (n=7). Immune responses in brain, blood and spleen were investigated 15 days post-stroke by flow cytometry. Functional outcomes were assessed at day 3, 7 and 14. Mortality was 25% in females and occurred at day 1, while in males 50% mortality was seen between day 3 and 9. Hemorrhagic transformation was seen in 53% of the males that died (5/8) and in none of the females (0/4). Flow cytometry analysis at day 15 showed significantly higher levels of CD8 + T cells in the blood after stroke in males compared to females (73±5% of CD3 + T cells vs 52±3%, P+ T cells were found in brains from males and females after stroke but levels were not different from sham (Male Stroke: 64±7%, Female Stroke: 58±5%). Independent of the type of surgery (stroke or sham), we observed higher levels of splenic CD8 + T cells in males (P Conclusion: Higher mortality and hemorrhagic transformation rates were seen in aged males than in females after stroke. This may be associated with the elevated levels of CD8 + T cells in blood and possible unfavorable effects on blood brain barrier permeability.

Stroke is a major health issue in women. Our previous studies in male rats showed decreased myogenic tone in middle cerebral arteries (MCAs) after ischemia and reperfusion (I/R), while tone in parenchymal arterioles (PAs) was increased. This vascular response may aggravate stroke damage in males by limiting reperfusion; however, the effect in females is not known. The current study investigated the effect of I/R and tissue plasminogen activator (tPA) on myogenic tone and reactivity of MCAs and PAs in female rats. Nitrosative stress by peroxynitrite and recruitment of inflammatory neutrophils to the microvasculature were also studied. Female rats were subjected to 2-h MCA filament occlusion (n = 16) or sham surgery (n = 17) and given tPA (1 mg/kg, i.v) or vehicle followed by 30-min reperfusion. Myogenic tone and reactivity were measured in isolated and pressurized MCAs and PAs from the same animals. Cerebrovascular F-actin, 3-nitrotyrosine (3-NT, peroxynitrite marker), and intravascular neutrophils were quantified. Myogenic tone and constriction to the nitric oxide synthase inhibitor Nω-nitro-l-arginine were decreased in MCAs but unchanged in PAs after I/R with no effect of tPA. F-actin and 3-NT expression were unaffected by I/R or tPA. Our study showed that MCAs from females, similar to what has been seen in males, are dilated after I/R and have decreased myogenic tone while tone in PAs was unchanged. Increased small vessel resistance may contribute to decreased reperfusion and worse outcome after stroke.

Introduction: Stroke is a growing health problem in women. We previously showed that ischemia/reperfusion (I/R) in male rats reduced tone in middle cerebral arteries (MCA) but enhanced tone in parenchymal arterioles (PA). Tissue plasminogen activator (tPA) may contribute to vascular dysfunction, oxidative stress and inflammation. However, vascular dysfunction and the effect of tPA have not been studied in females. Hypothesis: I/R in ovariectomized (OVX) female rats impairs MCA and PA function differentially, increases vascular oxidative stress and intravascular polymorphonuclear neutrophils (PMN). tPA has an additive effect on the vascular dysfunction after I/R. Methods: OVX female rats underwent 2 h MCA filament occlusion (n=16) or sham surgery (n=17) with 30 min reperfusion. tPA (1 mg/kg, i.v.) or vehicle (Vh) was given 10 min prior to reperfusion. Myogenic tone and reactivity to nitric oxide synthase (L-NNA, 10-4M) and Rho kinase (Y27632, 10-8 to 10-5M) inhibition were measured in pressurized MCA and PA. MCA were stained for F-actin and 3-nitrotyrosine (NT), a marker of oxidative stress. Brain intravascular PMN were identified with myeloperoxidase and collagen IV using immunohistochemistry, and counted blinded to group. Results: In MCA, I/R decreased tone at 75 mmHg (Sham Vh: 26±3%, Sham tPA: 27±3% vs. MCAO Vh: 21±2%, MCAO tPA: 21±3%, P Conclusions: The differential effect of I/R on MCA vs. PA in OVX females on tone suggest parenchymal blood flow may be restricted during reperfusion that could increase perfusion deficits. tPA had no effect on tone in MCA and PA but might enhance intravascular PMN, implicated in no-reflow after I/R. Therapies to alleviate parenchymal vasoconstriction may improve stroke outcome in females.

Background: It has been suggested that transcriptional upregulation of cerebral artery contractile endothelin (ETB) and 5-hydroxytryptamine (5-HT1B) receptors play an important role in the development of late cerebral ischemia and increased vasoconstriction after subarachnoid hemorrhage (SAH). We tested the hypothesis that inhibition of calcium calmodulin-dependent protein kinase II (CaMKII) may reduce cerebral vasoconstriction mediated by endothelin and serotonin receptors and improve neurological outcome after experimental SAH. Methods: SAH was induced in adult rats by injection of 250 μL autologous blood into the basal cisterns. The CaMKII activity in cerebral vessels was studied by Western blot and immunohistochemistry. The vasomotor responses of middle cerebral and basilar arteries were measured in a sensitive myograph system. The functional outcome was examined by the rotating pole test 2 and 3 days after SAH. Results: SAH induced a rapid early increase in phosphorylated CaMKII protein at 1 h that was attenuated by cisternal administration of the CaMKII inhibitor KN93 (0.501 μg/kg) 45 min prior and immediately after SAH as evaluated by Western blot. Application of KN93 at 1 h and every 12 h post-SAH significantly reduced vascular CaMKII immunoreactivity at 72 h. In addition, contractile responses of cerebral arteries to endothelin-1 (ET-1) and 5-hydroxycarboxamide (5-CT) were increased at this time-point. KN93 treatment significantly attenuated the contraction induced by ET-1 and 5-CT. Importantly, treatment with the CaMKII inhibitor prevented SAH-induced deficits in neurological function, as evaluated by the rotating pole test, and similar sensorimotor scores were seen in sham-operated animals. Conclusions: The present study has shown that SAH is associated with increased contractile responses to ET-1 and 5-CT in cerebral arteries and enhanced early activation of CaMKII. Treatment with the CaMKII inhibitor KN93 attenuated the contractile responses and prevented impaired sensorimotor function after SAH.

Background Cerebral ischemia induces transcriptional upregulation of inflammatory genes in the brain parenchyma and in cerebral arteries, thereby contributing to the infarct development. The present study was designed to evaluate the involvement of calcium-calmodulin-dependent protein kinase (CaMKII) II and extracellular signal-regulated kinase1/2 (ERK1/2) on inflammatory mediators in rat cerebral arteries using organ culture as a method for inducing ischemic-like vascular wall changes. Methods Rat basilar arteries were cultured in serum-free medium for 0, 3, 6 or 24 hours in the presence or absence of the CaMKII inhibitor KN93 or the MEK1/2 inhibitor U0126. Protein expression of activated CaMKII, ERK1/2, and inflammatory-associated protein kinases and mediators were examined with western blot and immunohistochemistry. Caspase-3 mRNA levels in basilar arteries were studied with real-time PCR. Results Western blot evaluation showed that organ culture induced a significant increase in phosphorylated ERK1/2 at 3, 6 and 24 hours, while CaMKII was found to be already activated in fresh non-incubated arteries and to decrease with incubation time. The addition of U0126 or KN93 decreased levels of phosphorylated c-Jun N-terminal kinase and p-p38, as evaluated by immunohistochemistry. KN93 affected the increase in caspase-3 mRNA expression only when given at the start of incubation, while U0126 had an inhibitory effect when given up to six hours later. Tumor necrosis factor receptor 1 was elevated after organ culture. This inflammatory marker was reduced by both of the two different protein kinase inhibitors. Conclusions The novel findings of the present study are that the cross-talk between the two protein kinases and the inhibition of CaMKII or MEK1/2 in a time-dependent manner attenuates inflammatory-associated protein kinases and mediators, suggesting that they play a role in cerebrovascular inflammation.

Calcitonin gene-related peptide (CGRP) and its receptor are widely distributed within the circulation and the mechanism behind its vasodilation not only differs from one animal species to another but is also dependent on the type and size of vessel. The present study examines the nature of CGRP-induced vasodilation, characteristics of the CGRP receptor antagonist telcagepant and localization of the key components calcitonin receptor-like receptor (CLR) and receptor activity modifying protein 1 (RAMP1) of the CGRP receptor in human subcutaneous arteries.CGRP-induced vasodilation and receptor localization in human subcutaneous arteries were studied by wire myograph in the presence and absence of the CGRP receptor antagonist telcagepant and immunohistochemistry respectively.At concentrations of 1, 3, 5, 10 and 30 nm, telcagepant had a competitive antagonist-like behaviour characterized by a parallel rightwards shift in the log CGRP concentration-tension/calcium curve with no depression of the maximal relaxation. CGRP-induced vasodilation was not affected by mechanical removal of the endothelium or addition of L-NG-nitroarginine methyl ester and indomethacin, antagonists for synthesis of nitric oxide and prostaglandins, respectively. CLR and RAMP1 were localized in the vascular smooth muscle and endothelial cells.The present results indicate that CGRP exerts its vasodilatory effect in human subcutaneous arteries by binding to its receptors located on the smooth muscle cells and is suggested to be endothelium-independent. In conclusion, these results underline the dynamic distribution of CGRP receptor components in the human circulation reflecting the important role of CGRP in fine tuning of the blood flow in resistance arteries.

Background: The present study was designed to examine the influence of inositol 1,4,5-trisphosphate receptor (IP3R) and calcium calmodulin-dependent protein kinase (CaMK) on endothelin receptor regulation during organ culture in rat middle cerebral arteries (MCA). Methods: MCA segments were incubated with or without xestospongin C (XeC), an IP3R inhibitor, or KN93, a CaMKII blocker. The mRNA levels of the ETA and ETB receptors, nuclear factor of activated T cells activating protein (NFam1), CaMKII, IP3R and Downstream regulatory element antagonist modulator (DREAM) protein were determined by real-time PCR or immunohistochemistry. Contractile responses to endothelin-1 (ET-1) and sarafotoxin 6c (S6c) were studied by a sensitive myograph and the intracellular calcium levels [Ca2+]i were evaluated by the FURA-2AM. Results: The contractile responses to ET-1 and S6c, the ETB receptors mRNA level and the baseline level of intracellular calcium [Ca2+]i were all increased after 24 h organ culture. Incubation with XeC or KN93 attenuated ETB receptor expression and increase in [Ca2+]i induced by ET-1 or S6c. XeC decreased the NFam1 mRNA levels while KN93 decreased DREAM protein levels. Conclusions: The study suggests that CaMKII and calcium release via IP3R are involved in the mechanisms regulate ETB receptor putatively via DREAM and NFam1, respectively.

BACKGROUND AND PURPOSE: Male-female differences may significantly impact stroke prevention and treatment in men and women, however underlying mechanisms for sexual dimorphism in stroke are not understood. We previously found in males that cerebral ischemia upregulates contractile receptors in cerebral arteries, which is associated with lower blood flow. The present study investigates if cerebral arteries from men and women differ in cerebrovascular receptor upregulation. EXPERIMENTAL APPROACH: Freshly obtained human cerebral arteries were placed in organ culture, an established model for studying receptor upregulation. 5-hydroxtryptamine type 1B (5-HT1B), angiotensin II type 1 (AT1) and endothelin-1 type A and B (ETA and ETB) receptors were evaluated using wire myograph for contractile responses, real-time PCR for mRNA and immunohistochemistry for receptor expression. KEY RESULTS: Vascular sensitivity to angiotensin II and endothelin-1 was markedly lower in cultured cerebral arteries from women as compared to men. ETB receptor-mediated contraction occurred in male but not female arteries. Interestingly, there were similar upregulation in mRNA and expression of 5-HT1B, AT1, and ETB receptors and in local expression of Ang II after organ culture. CONCLUSIONS AND IMPLICATIONS: In spite of receptor upregulation after organ culture in both sexes, cerebral arteries from women were significantly less responsive to vasoconstrictors angiotensin II and endothelin-1 as compared to arteries from men. This suggests receptor coupling and/or signal transduction mechanisms involved in cerebrovascular contractility may be suppressed in females. This is the first study to demonstrate sex differences in the vascular function of human brain arteries.

Cerebral arteries subjected to different types of experimental stroke upregulate their expression of certain G-protein-coupled vasoconstrictor receptors, a phenomenon that worsens the ischemic brain damage. Upregulation of contractile endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B)) receptors has been demonstrated after subarachnoid hemorrhage and global ischemic stroke, but the situation is less clear after focal ischemic stroke. Changes in smooth muscle calcium handling have been implicated in different vascular diseases but have not hitherto been investigated in cerebral arteries after stroke. Here, we evaluate changes of ET(B) and 5-HT(1B) receptors, intracellular calcium levels, and calcium channel expression in rat middle cerebral artery (MCA) after focal cerebral ischemia and in vitro organ culture, a proposed model of vasoconstrictor receptor changes after stroke. Rats were subjected to 2 h MCA occlusion followed by reperfusion for 1 or 24 h. Alternatively, MCAs from naïve rats were cultured for 1 or 24 h. ET(B) and 5-HT(1B) receptor-mediated contractions were evaluated by wire myography. Receptor and channel expressions were measured by real-time PCR and immunohistochemistry. Intracellular calcium was measured by FURA-2. Expression and contractile functions of ET(B) and 5-HT(1B) receptors were strongly upregulated and slightly downregulated, respectively, 24 h after experimental stroke or organ culture. ET(B) receptor-mediated contraction was mediated by calcium from intracellular and extracellular sources, whereas 5-HT(1B) receptor-mediated contraction was solely dependent on extracellular calcium. Organ culture and stroke increased basal intracellular calcium levels in MCA smooth muscle cells and decreased the expression of inositol triphosphate receptor and transient receptor potential canonical calcium channels, but not voltage-operated calcium channels.

Experimental cerebral ischaemia and organ culture of cerebral arteries induce an increased endothelin ET(B) receptor-mediated contraction. The aim of this study was to examine whether cytokines and growth factors, known to be activated in ischaemia, can influence the expression and function of endothelin receptors after organ culture.Rat middle cerebral arteries were cultured for 24 h at 37 °C in humidified 5% CO(2) and air in culture medium alone, or with tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), platelet-derived growth factor (PDGF), epidermal growth factor (EGF) or basic fibroblast growth factor (bFGF). Concentration-response curves were obtained for sarafotoxin 6c (ET(B) receptor agonist) and endothelin-1 (here ET(A) receptor agonist, because of ET(B) receptor desensitization). The receptor mRNA expression was examined by real-time PCR and the protein expression by immunohistochemistry and Western blot.Tumour necrosis factor-α (100 ng mL(-1) ) and EGF (20 ng mL(-1) ) potentiated the ET(B) receptor-mediated contraction (increase in pEC(50) without change in E(max) ). bFGF (10 ng mL(-1) ) and IL-1β (10 ng mL(-1) ) induced an enhanced ET(A) receptor-mediated contraction. bFGF (10 ng mL(-1) ) significantly increased the ET(B) mRNA level, and EGF (20 ng mL(-1) ) increased the ET(A) receptor protein. Increased ET(B) receptor mRNA and protein level also were observed after treatment with IL-1β (10 ng mL(-1) ).This study shows that TNF-α, IL-1β, EGF and bFGF can modify the expression and function of endothelin receptors during organ culture. Because there is similar receptor upregulation in experimental stroke, the effect of cytokines and growth factors on endothelin receptor upregulation is an interesting aspect to study in vivo.

Waldsee R, Ahnstedt H, Eftekhari S, Edvinsson L. Involvement of calcium-calmodulin-dependent protein kinase II in endothelin receptor expression in rat cerebral arteries. Am J Physiol Heart Circ Physiol 298: H823-H832, 2010. First published December 11, 2009; doi:10.1152/ajpheart.00759.2009.-Experimental cerebral ischemia and organ culture of cerebral arteries result in the enhanced expression of endothelin ETB receptors in smooth muscle cells via increased transcription. The present study was designed to evaluate the involvement of calcium-calmodulin-dependent protein kinase (CAMK) in the transcriptional expression of endothelin receptors after organ culture. Rat basilar arteries were incubated for 24 h with or without the CAMK inhibitor KN93 or ERK1/2 inhibitor U0126. The contractile responses to endothelin-1 (ET-1; ETA and ETB receptor agonist) and sarafotoxin 6c (S6c; ETB receptor agonist) were studied using a sensitive myograph. The mRNA levels of the ETA and ETB receptors and CAMKII were determined by real-time PCR, and their protein levels were evaluated by immunohistochemistry and Western blot. The mRNA levels of CAMKII and the ETB receptor increased during organ culture, but there was no change in the expression of the ETA receptor. This effect was abolished by coincubation with KN93 or U0126. In functional studies, both inhibitors attenuated the S6c-induced contraction. Incubating the arteries with KN93, but not U0126, decreased the amount of phosphorylated CAMKII. The inhibitors had no effect on the levels of myosin light chain during organ culture, as measured by Western blot. CAMKII is involved in the upregulation of the endothelin ETB receptor and interacts with the ERK1/2 pathway to enhance receptor expression. CAMKII has no effect on the contractile apparatus in rat cerebral arteries.

Background. Experimental cerebral ischemia and organ culture of cerebral arteries result in enhanced expression of endothelin ETB receptors in smooth muscle cells. The present study was designed to evaluate the involvement of calcium-calmodulin dependent protein kinase (CAMK) on the expression of endothelin receptors. Methods. Rat basilar arteries were incubated for 24hours with and without the CAMK inhibitor, KN93, or the ERK1/2 inhibitor, U0126. The contractile responses to endothelin-1 (ET-1; ETA and ETB receptor agonist) and sarafotoxin 6c (S6c; ETB receptor agonist) were studied using a sensitive myograph. The mRNA levels of ETA and ETB receptors, and of CAMKII were determined with real-time polymerase chain reaction (PCR) while the protein level was evaluated by immunohistochemistry and western blot. Results. The mRNA levels of CAMKII and of the ETB receptor were increased during organ culture but not for ETA receptor. This effect was abolished by co-incubation with KN93 or U0126. In functional studies, both inhibitors attenuated the S6c and potassium induced contractions, and KN93 decreased the ET-1 induced response. This was confirmed at the protein level by immunohistochemistry where the endothelin receptors were found co-localised with CAMKII. Phosphorylated extracellular signal-regulated kinase p-ERK1/2 and CAMKII was measured by immunohistochemistry and western blot. Incubation of arteries with KN93 decreased the protein levels of p-ERK1/2 and CAMKII while U0126 has no effect on CAMKII. Conclusion. Our results show that the CAMK II is involved in the endothelin receptor regulation and interacts with the MEK/ERK1/2 pathway, resulting in enhanced receptors expression in rat cerebral arteries.

Background Cerebral ischemia results in a rapid increase in contractile cerebrovascular receptors, such as the 5-hydroxytryptamine type 1B (5-HT1B), angiotensin II type 1 (AT1), and endothelin type B (ETB) receptors, in the vessel walls within the ischemic region, which further impairs local blood flow and aggravates tissue damage. This receptor upregulation occurs via activation of the mitogen-activated protein kinase pathway. We therefore hypothesized an important role for B-Raf, the first signaling molecule in the pathway. To test our hypothesis, human cerebral arteries were incubated at 37°C for 48 h in the absence or presence of a B-Raf inhibitor: SB-386023 or SB-590885. Contractile properties were evaluated in a myograph and protein expression of the individual receptors and activated phosphorylated B-Raf (p-B-Raf) was evaluated immunohistochemically. Results 5-HT1B, AT1, and ETB receptor-mediated contractions were significantly reduced by application of SB-590885, and to a smaller extent by SB-386023. A marked reduction in AT1 receptor immunoreactivity was observed after treatment with SB-590885. Treatment with SB-590885 and SB-386023 diminished the culture-induced increase of p-B-Raf immunoreactivity. Conclusions B-Raf signaling has a key function in the altered expression of vascular contractile receptors observed after organ culture. Therefore, specific targeting of B-Raf might be a novel approach to reduce tissue damage after cerebral ischemia by preventing the previously observed upregulation of contractile receptors in smooth muscle cells.