Abstract WP412: Fibronectin Increases the Paravascular Deposition of Amyloid-β in Aging and Stroke

Introduction: Ischemic stroke is a major risk factor for cerebral amyloid angiopathy (CAA), which may be driven by alterations in the paravascular transport of cerebrospinal fluid (CSF) amyloid-β 1-40 (Aβ 40 ) through the basement membrane (BM). Post-stroke BM thickening may favor CSF Aβ 40 deposition within brain microvessels. This study identifies BM fibronectin (FN) and its receptor, α5β1 integrin, as novel drivers of paravascular Aβ 40 deposition after stroke in aged animals.

Hypothesis: We hypothesize that stroke-induced FN expression induces paravascular deposition of CSF Aβ 40 within the brain. This may worsen with aging due to increased FN binding to α5β1 integrin.

Methods: Young (3 months-old) and aged (18 months-old) male mice were subjected to experimental stroke, and fluorescent tracers were intracisternally microinjected 30 days later to measure brain uptake of CSF Aβ 40 . BM thickening (lectin staining), as well as endogenous levels of FN and α5β1 integrin, were measured by immunohistochemistry and Western blot. To assess FN-Aβ 40 binding, naïve young and aged mice were intracisternally injected with FN or vehicle, and Aβ 40 uptake from CSF measured. Statistical significance was confirmed by two-way ANOVA with Dunnet’s post-hoc test.

Results: Stroke enhanced paravascular Aβ 40 deposition compared to size-matched dextran in young animals ( p<.05 ), which worsened with aging ( p<.001 ). Interestingly, BM thickening positively correlated with paravascular Aβ 40 deposition after stroke in both age groups (R=.98, p<.001 ). Furthermore, FN levels increased in both young ( p<.05 ) and aged ( p<.05 ) cortex after stroke, with additional increases seen in α5β1 integrin expression in aged cortex at baseline ( p<.05 ) and with stroke ( p<.01 ). Finally, FN exhibited affinity for Aβ 40 in vitro (IC50= 216nM), and FN infusion increased paravascular Aβ 40 deposition in vivo ( p<.05 ), which worsened with aging ( p<.05 ) .

Conclusion: These results indicate that FN induces paravascular Aβ 40 deposition after stroke. Furthermore, increased α5β1 integrin may ‘prime’ the aged vasculature for FN-Aβ binding, worsening Aβ 40 deposition after stroke in aged animals. Targeting FN-Aβ adhesion may provide a novel therapeutic avenue to reduce CAA in stroke survivors.

Abstract TP99: Hypoxia Drives Anti-Inflammatory Polarization of Microglia Through the JMJD3-IRF4 Axis

Background: Microglia, as the innate immune cells of the central nervous system, are poised to be the first responders of the immune system to ischemic stroke. In response to an injury or stimulus, microglia polarize from a resting to a pro- or anti-inflammatory phenotype. We have previously shown that hypoxia, such as that in the setting of ischemic stroke, acts as a stimulus itself to polarize microglia to an anti-inflammatory phenotype. Additionally, we have shown that Jumonji Domain Containing 3 (JMJD3) is a histone demethylase that is important for anti-inflammatory polarization of microglia. JMJD3 functions to demethylate trimethylated histone H3 lysine 27 (H3K27me3) at the Irf4 promoter to monomethylation marks (H3K27me1), resulting in transcriptional activation of Irf4 and downstream expression of anti-inflammatory genes.

Hypothesis: Thus, we hypothesized that hypoxia drives microglial anti-inflammatory polarization through the JMJD3-IRF4 axis.

Methods: We cultured male and female primary microglia from neonatal P0.5-P3 C57Bl/6 mice, inhibited JMJD3 with GSK-J4 (Cayman Chemical) or DMSO control, and stimulated cultures with oxygen glucose deprivation (OGD). After 8hr OGD, we isolated RNA (RNEasy Micro Plus kit, Qiagen) and performed down-stream real-time PCR array analysis (PrimePCR Arrays, Bio-Rad) or protein (RIPA Buffer, Thermo Fisher) for Western blot analysis (Bio-Rad) for JMJD3, histone H3 (Abcam), H3K27me1, and H3K27me3 (Millipore).

Results: We found that OGD induced up-regulation anti-inflammatory genes, notably Csf1 , Cntf , Gdf15 , Il1rn , Irf4 , Mif , and Vegfa while down-regulating pro-inflammatory genes Tnfa , Il1b , and Il6 (n=4, p<0.05). Additionally, we found that Kdm6b (the gene encoding JMJD3) was up-regulated following 8hr OGD, suggesting JMJD3 is involved in hypoxia-induced anti-inflammatory microglial phenotype polarization. Pharmacological inhibition of JMJD3 with GSK-J4 prevented demethylation of H3K27me3 at the Irf4 promoter and blocked hypoxia-induced up-regulation of Irf4 and abrogated hypoxia-induced anti-inflammatory gene up-regulation.

Conclusion: In conclusion, our data suggests that hypoxia polarizes microglia to an anti-inflammatory phenotype through the JMJD3-IRF4 axis.

Abstract TP267: Uncertainty-Based Individual Health Preferences for Patients With Primary Intracerebral Hemorrhage

Introduction: Value-based care and patient-perceived outcomes are increasingly important. Standard Gamble (SG) derived utilities directly measure patients’ preferences for health states and form the basis of health economic analyses. We describe distribution of and factors associated with SG utilities (SGU) in a cohort of intracerebral hemorrhage (ICH) patients, and explore changes in SGU over 90 days post-discharge.

Methods: Our study is a multisite cohort aiming to evaluate the comparative effectiveness of ICH patient management at various levels of care across Texas. Consented patients undergo assessments including SG in-hospital, and 30 and 90 days post-discharge. The SG assesses patients’ risk-taking behavior toward achieving a perfect health status, and outputs utility on a scale of 0 - 1 (Figure 1). Median and interquartile range (IQR) are reported for inpatient and day-90 SGU. Quantile regression was used to evaluate factors associated with SGU. Difference in median (DIM) and 95% confidence interval (CI) for the difference are reported.

Results: 158 patients have been enrolled. Inpatient and day-90 SG was obtained from 132 and 54 patients respectively. Median inpatient SGU are significantly lower for older patients, white patients (compared to black patients), and those with higher ICH scores (Table 1). Median day-90 SGU was higher than inpatient SGU (DIM: 0.27; 95% CI: 0.08-0.46). Age >65 and higher ICH score were independently associated with lower SGU (Age: DIM -0.30; 95% CI -0.49, -0.11) (ICH Score: DIM -0.59; 95% CI -0.97, -0.21). Patients with mRS scores 0-3 at day 90 had higher SGU values compared to those with mRS scores 4-5 (DIM: 0.25, 95% CI: 0.09 - 0.41). Enrollment continues; updated analyses to be presented.

Conclusion: Direct assessment of preferences for a morbid condition like ICH provides unique insight into patient values. Assessment of SGU may be routinely conducted in ICH patient studies to generate evidence for comparative effectiveness.

Ischemic stroke induces gut permeability and enhances bacterial translocation leading to sepsis in aged mice

Aging is an important risk factor for post-stroke infection, which accounts for a large proportion of stroke-associated mortality. Despite this, studies evaluating post-stroke infection rates in aged animal models are limited. In addition, few studies have assessed gut microbes as a potential source of infection following stroke. Therefore we investigated the effects of age and the role of bacterial translocation from the gut in post-stroke infection in young (8-12 weeks) and aged (18-20 months) C57Bl/6 male mice following transient middle cerebral artery occlusion (MCAO) or sham surgery. Gut permeability was examined and peripheral organs were assessed for the presence of gut-derived bacteria following stroke. Furthermore, sickness parameters and components of innate and adaptive immunity were examined. We found that while stroke induced gut permeability and bacterial translocation in both young and aged mice, only young mice were able to resolve infection. Bacterial species seeding peripheral organs also differed between young (Escherichia) and aged (Enterobacter) mice. Consequently, aged mice developed a septic response marked by persistent and exacerbated hypothermia, weight loss, and immune dysfunction compared to young mice following stroke.

Stroke sensitivity in the aged: sex chromosome complement vs. gonadal hormones

Stroke is a sexually dimorphic disease. Elderly women not only have higher stroke incidence than age-matched men, but also have poorer recovery and higher morbidity and mortality after stroke. In older, post-menopausal women, gonadal hormone levels are similar to that of men. This suggests that tissue damage and functional outcomes are influenced by biologic sex (XX vs. XY) rather than the hormonal milieu at older ages. We employed the Four Core Genotype (FCG) mouse model to study the contribution of sex chromosome complement and gonadal hormones to stroke sensitivity in aged mice in which the testis determining gene (Sry) is removed from the Y chromosome, allowing for the generation of XX males and XY females. XXF, XXM, XYF, XYM and XYwt aged mice were subjected to middle cerebral artery occlusion (MCAO). XXF and XXM mice had significantly larger infarct volumes than XYF and XYM cohorts respectively. There was no significant difference in hormone levels among aged FCG mice. XXF/XXM mice also had more robust microglial activation and higher serum levels of pro-inflammatory cytokines than XYF/XYM cohort respectively. We concluded that the sex chromosome complement contributes to ischemic sensitivity in aged animals and leads to sex differences in innate immune responses.

Sex differences in neuroinflammation and neuroprotection in ischemic stroke

Stroke is not only a leading cause of mortality and morbidity worldwide it also disproportionally affects women. There are currently over 500,000 more women stroke survivors in the US than men, and elderly women bear the brunt of stroke-related disability. Stroke has dropped to the fifth leading cause of death in men, but remains the third in women. This review discusses sex differences in common stroke risk factors, the efficacy of stroke prevention therapies, acute treatment responses, and post-stroke recovery in clinical populations. Women have an increased lifetime risk of stroke compared to men, largely due to a steep increase in stroke incidence in older postmenopausal women, yet most basic science studies continue to only evaluate young male animals. Women also have an increased lifetime prevalence of many common stroke risk factors, including hypertension and atrial fibrillation, as well as abdominal obesity and metabolic syndrome. None of these age-related risk factors have been well modeled in the laboratory. Evidence from the bench has implicated genetic and epigenetic factors, differential activation of cell-death programs, cell-cell signaling pathways, and systemic immune responses as contributors to sex differences in ischemic stroke. The most recent basic scientific findings have been summarized in this review, with an emphasis on factors that differ between males and females that are pertinent to stroke outcomes. Identification and understanding of the underlying biological factors that contribute to sex differences will be critical to the development of translational targets to improve the treatment of women after stroke. © 2016 Wiley Periodicals, Inc.

Deletion of the P2X4 receptor is neuroprotective acutely, but induces a depressive phenotype during recovery from ischemic stroke

INTRODUCTION

Acute ischemic injury leads to severe neuronal loss. One of the key mechanisms responsible for this effect is inflammation, which is characterized by the activation of myeloid cells, including resident microglia and infiltrating monocytes/macrophages. P2X4 receptors (P2X4Rs) present on these immune cells modulate the inflammatory response. For example, excessive release of adenosine triphosphate during acute ischemic stroke triggers stimulation of P2X4Rs, leading to myeloid cell activation and proliferation and further exacerbating post-ischemic inflammation. In contrast, during recovery P2X4Rs activation on microglia leads to the release of brain-derived neurotrophic factor (BDNF), which alleviate depression, maintain synaptic plasticity and hasten post-stroke behavioral recovery. Therefore, we hypothesized that deletion of the P2X4R specifically from myeloid cells would have differential effects on acute versus chronic recovery following stroke.

METHODS

We subjected global or myeloid-specific (MS) P2X4R knock-out (KO) mice and wild-type littermates of both sexes to right middle cerebral artery occlusion (60min). We performed histological, behavioral (sensorimotor and depressive), and biochemical (quantitative PCR and flow cytometry) analyses to determine the acute (three days after occlusion) and chronic (30days after occlusion) effects of receptor deletion.

RESULTS

Global P2X4R deletion led to reduced infarct size in both sexes. In MS P2X4R KO mice, only females showed reduced infarct size, an effect that did not change with ovariectomy. MS P2X4R KO mice of both sexes showed swift recovery from sensorimotor deficits during acute recovery but exhibited a more pronounced post-stroke depressive behavior phenotype that was independent of infarct size. Quantitative PCR analysis of whole cell lysate as well as flow-sorted myeloid cells from the perilesional cortex showed increased cellular interleukin 1 beta (IL-1β), interleukin 6 (IL-6), and tumor necrosis factor alpha (TNF-α) mRNA levels but reduced plasma levels of these cytokines in MS P2X4R KO mice after stroke. The expression levels of BDNF and other depression-associated genes were reduced in MS P2X4R KO mice after stroke.

CONCLUSIONS

P2X4R deletion protects against stroke acutely but predisposes to depression-like behavior chronically after stroke. Thus, a time-sensitive approach should be considered when targeting P2X4Rs after stroke.

Splenectomy protects aged mice from injury after experimental stroke

Elderly stroke patients and aged animals subjected to experimental stroke have significantly worse functional recovery and higher mortality compared to younger subjects. Activation of the peripheral immune system is known to influence stroke outcome. Prior studies have shown that splenectomy reduces ischemic brain injury in young mice. As immune function changes with aging, it is unclear whether splenectomy will confer similar benefits in aged animals. We investigated the contribution of spleen to brain injury after cerebral ischemia in aged male mice. Splenic architecture and immune cell composition were altered in aged mice. Splenectomy 2 weeks before stroke resulted in improved neurobehavioral and infarct outcomes in aged male mice. In addition, there was a reduction in peripheral immune cell infiltration into the brain and decreased levels of peripheral inflammatory cytokines after stroke in aged splenectomized mice. Splenectomy immediately after reperfusion also improved behavioral and infarct outcomes. This study suggests that inhibition of the splenic immune response is a translationally relevant target to pursue for stroke treatment in aged individuals.

Enhancing the Alignment of the Preclinical and Clinical Stroke Recovery Research Pipeline: Consensus-Based Core Recommendations From the Stroke Recovery and Rehabilitation Roundtable Translational Working Group

Stroke recovery research involves distinct biological and clinical targets compared to the study of acute stroke. Guidelines are proposed for the pre-clinical modeling of stroke recovery and for the alignment of pre-clinical studies to clinical trials in stroke recovery.

Enhancing the alignment of the preclinical and clinical stroke recovery research pipeline: Consensus-based core recommendations from the Stroke Recovery and Rehabilitation Roundtable translational working group

Stroke recovery research involves distinct biological and clinical targets compared to the study of acute stroke. Guidelines are proposed for the pre-clinical modeling of stroke recovery and for the alignment of pre-clinical studies to clinical trials in stroke recovery.

Multiparity improves outcomes after cerebral ischemia in female mice despite features of increased metabovascular risk

Females show a varying degree of ischemic sensitivity throughout their lifespan, which is not fully explained by hormonal or genetic factors. Epidemiological data suggest that sex-specific life experiences such as pregnancy increase stroke risk. This work evaluated the role of parity on stroke outcome. Age-matched virgin (i.e., nulliparous) and multiparous mice were subjected to 60 min of reversible middle cerebral artery occlusion and evaluated for infarct volume, behavioral recovery, and inflammation. Using an established mating paradigm, fetal microchimeric cells present in maternal mice were also tracked after parturition and stroke. Parity was associated with sedentary behavior, weight gain, and higher triglyceride and cholesterol levels. The multiparous brain exhibited features of immune suppression, with dampened baseline microglial activity. After acute stroke, multiparous mice had smaller infarcts, less glial activation, and less behavioral impairment in the critical recovery window of 72 h. Behavioral recovery was significantly better in multiparous females compared with nulliparous mice 1 mo after stroke. This recovery was accompanied by an increase in poststroke angiogenesis that was correlated with improved performance on sensorimotor and cognitive tests. Multiparous mice had higher levels of VEGF, both at baseline and after stroke. GFP+ fetal cells were detected in the blood and migrated to areas of tissue injury where they adopted endothelial morphology 30 d after injury. Reproductive experience has profound and complex effects on neurovascular health and disease. Inclusion of female mice with reproductive experience in preclinical studies may better reflect the life-long patterning of ischemic stroke risk in women.

Sex differences in stroke across the lifespan: The role of T lymphocytes

Stroke is a sexually dimorphic disease. Ischemic sensitivity changes throughout the lifespan and outcomes depend largely on variables like age, sex, hormonal status, inflammation, and other existing risk factors. Immune responses after stroke play a central role in how these factors interact. Although the post-stroke immune response has been extensively studied, the contribution of lymphocytes to stroke is still not well understood. T cells participate in both innate and adaptive immune responses at both acute and chronic stages of stroke. T cell responses also change at different ages and are modulated by hormones and sex chromosome complement. T cells have also been implicated in the development of hypertension, one of the most important risk factors for vascular disease. In this review, we highlight recent literature on the lymphocytic responses to stroke in the context of age and sex, with a focus on T cell response and the interaction with important stroke risk factors.

CCL11 (Eotaxin-1) Levels Predict Long-Term Functional Outcomes in Patients Following Ischemic Stroke

Circulating levels of the pro-inflammatory cytokine C-C motif chemokine 11 (CCL11, also known as eotaxin-1) are increased in several animal models of neuroinflammation, including traumatic brain injury and Alzheimer's disease. Increased levels of CCL11 have also been linked to decreased neurogenesis in mice. We hypothesized that circulating CCL11 levels would increase following ischemic stroke in mice and humans, and that higher CCL11 levels would correlate with poor long-term recovery in patients. As predicted, circulating levels of CCL11 in both young and aged mice increased significantly 24 h after experimental stroke. However, ischemic stroke patients showed decreased CCL11 levels compared to controls 24 h after stroke. Interestingly, lower post-stroke CCL11 levels were predictive of increased stroke severity and independently predictive of poorer functional outcomes in patients 12 months after ischemic stroke. These results illustrate important differences in the peripheral inflammatory response to ischemic stroke between mice and human patients. In addition, it suggests CCL11 as a candidate biomarker for the prediction of acute and long-term functional outcomes in ischemic stroke patients.

Risk of hemorrhagic transformation after ischemic stroke in patients with antiphospholipid antibody syndrome

BACKGROUND AND PURPOSE

Several rheumatologic conditions including systemic lupus erythematosus, antiphospholipid antibody (APS) syndrome, rheumatoid arthritis, and scleroderma are known risk factors for stroke. The risk of hemorrhagic transformation after an acute ischemic stroke (AIS) in these patients is not known.

METHODS

We queried the Nationwide Inpatient Sample (NIS) data between 2010 and 2012 with ICD 9 diagnostic codes for AIS. The primary outcome was the development of hemorrhagic transformation. Multivariate predictors for hemorrhagic transformation were identified with a logistic regression model. Using SAS 9.2, Survey procedures were used to accommodate for hierarchical two stage cluster design of NIS.

RESULTS

APS (OR 2.57, 95% CI 1.14-5.81, p = 0.0228) independently predicted risk of hemorrhagic transformation in multivariate regression analysis. Similarly, in multivariate regression models for the outcome variables of total charges of the hospitalization and length of stay (LOS), patients with APS had the highest charges ($56,286, p = 0.0228) and LOS (3.87 days, p = 0.0164) compared to other co-variates. Univariate analysis showed increased mortality in the APS compared to the non-APS group (11.68% vs. 7.16%, p = 0.0024).

CONCLUSION

APS is an independent risk factor for hemorrhagic transformation in both thrombolytic and non-thrombolytic treated patients. APS is also associated with longer length and cost of hospital stay. Further research is warranted to identify the unique risk factors in these patients to identify strategies to reduce the risk of hemorrhagic transformation in this subgroup of the population.

Nationwide Estimates of 30-Day Readmission in Patients With Ischemic Stroke

Background and Purpose—

Readmission within 30 days of hospital discharge for ischemic stroke is an important quality of care metric. We aimed to provide nationwide estimates of 30-day readmission in the United States, describe important reasons for readmission, and sought to explore factors associated with 30-day readmission, particularly the association with recanalization therapy.

Methods—

We conducted a weighted analysis of the 2013 Nationwide Readmission Database to represent all US hospitalizations. Adult patients with acute ischemic stroke including those who received intravenous tissue-type plasminogen activator and intra-arterial therapy were identified using International Classification of Diseases -Ninth Revision codes. Readmissions were defined as any readmission during the 30-day post-index hospitalization discharge period for the eligible patient population. Proportions and 95% confidence intervals for overall 30-day readmissions and for unplanned and potentially preventable readmissions are reported. Survey design logistic regression models were fit for determining crude and adjusted odds ratios and 95% confidence interval for association between recanalization therapy and 30-day readmission.

Results—

Of the 319 317 patients with acute ischemic stroke, 12.1% (95% confidence interval, 11.9–12.3) were readmitted. Of these, 89.6% were unplanned and 12.9% were potentially preventable. More than 20% of all readmissions were attributable to acute cerebrovascular disease. Readmitted patients were older and had a higher comorbidity burden. After controlling for age, sex, insurance status, and comorbidities, patients who underwent recanalization therapy had significantly lower odds of 30-day readmission (odds ratio, 0.82; 95% confidence interval, 0.77–0.89).

Conclusions—

Up to 12% of patients with ischemic stroke get readmitted within 30 days post-discharge period, and recanalization therapy is associated with 11% to 23% lower odds of 30-day readmission.

Comparison of Initial Vasopressors Used for Delayed Cerebral Ischemia after Aneurysmal Subarachnoid Hemorrhage

BACKGROUND

The main reason for morbidity after aneurysmal subarachnoid hemorrhage (aSAH) is delayed cerebral ischemia (DCI). The mainstay of medical therapy for treating DCI is induced hypertension with vasopressors to restore cerebral perfusion. Both phenylephrine (PE) and norepinephrine (NE) are commonly used for induced hypertension, but the impact of the initial choice of vasopressor on the efficacy, adverse effects, or outcome after hemodynamic therapy for DCI is unknown.

METHODS

Sixty-three patients with aSAH between January 2012 and October 2014, who developed DCI (defined as new focal deficit or decline in Glasgow Coma Score) and in which PE (n = 45) or NE (n = 18) treatment was initiated were evaluated in this retrospective study. Baseline characteristics, adverse effects, the need to change or add vasopressors, the response to therapy, the need for endovascular therapy, new infarct development, discharge disposition, and 3 months modified Rankin score were all compared between pressor groups.

RESULTS

Baseline characteristics (e.g., Hunt Hess and Fisher grades) were similar. There were no differences in the overall rate of complications including arrhythmia, pulmonary edema, or kidney injury. However, those initiated on PE were more likely to be changed to an alternate vasopressor (64 vs. 33%, p = 0.016), mostly for bradycardia or failure to reach therapeutic targets. Patients initially treated with PE were less likely to respond neurologically (71 vs. 94%, p = 0.01) or to be discharged to home or acute rehabilitation facilities (73 vs. 94%, p = 0.02) and were more likely to have a delayed infarct on imaging (62 vs. 33%, p = 0.04).

CONCLUSIONS

Our study suggests that patients with DCI after aSAH initiated on PE are more likely to require treatment change to another vasopressor and are at greater risk for poor clinical outcomes compared to patients started on NE. Larger comparative studies are warranted.

Abstract WMP74: Sex Differences in T Cell Immune Responses and Outcome After Stroke in Aged Mice

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<0.001). CD8 + 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<0.01). T regulatory cells were significantly increased in the brain after stroke in males compared to sham (P<0.01), but not in females. Open-field testing showed a decrease in center visits after stroke in both sexes at 3 days, however males spent more time immobile (P<0.01) indicating decreased locomotor activity and/or anxiety. This difference equalized at 7 and 14 days post-stroke.

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.

Abstract WP438: The Role of Transforming Growth Factor-beta in Post-Stroke Glymphatic Impairment

Introduction: The recently discovered glymphatic system may protect the brain from dementia by clearing toxic amyloid-β (Aβ) along the basement membrane (BM) via bulk flow of cerebrospinal fluid (CSF). It is not known whether stroke impairs glymphatic flow, or how this might occur. Previous work has shown that stroke enhances astrocytic transforming growth factor-β (TGF-β) signaling, which could increase the expression of pro-fibrotic BM proteins such as fibronectin. BM fibrosis may obstruct glymphatic flow after stroke, driving Aβ accumulation and neurodegenerative disease in stroke survivors.

Hypothesis: I hypothesize that stroke induces BM fibrosis via enhanced TGFβ-Smad2 signaling in perivascular astrocytes, impairing glymphatic flow.

Methods: To test this hypothesis, the glymphatic influx of CSF tracer in mice following stroke or TGF-β treatment (ICV, 500 ng) was assessed. TGF-β signaling was measured as Smad2 phosphorylation. Brain expression of fibronectin and GFAP (astrocytes) were assessed by western blot and immunohistochemistry.

Results: Stroke impaired the glymphatic distribution of FITC-dextran and FITC-Aβ bilaterally ( Fig. 1 ). TGF-β treatment also inhibited glymphatic distribution, measured by reduced 14 C-Inulin uptake (38 fold-reduction, p < .05). Increased fibronectin (5.5 ± 0.7 fold-increase) and GFAP (2.3 ± .2 fold-increase) expression was found after stroke (p < .05 ), localized to the glial scar and around vessels bilaterally . Finally, Smad2 phosphorylation was increased in cortex contralateral to injury (2.5 ± 0.2 fold, p < .01).

Conclusion: The present study shows that stroke impairs glymphatic flow, which may be mediated through increased TGF-β signaling and global BM fibrosis. This could impair the clearance of Aβ, leading to dementia in stroke survivors. TGF-β inhibition can rescue post-stroke fibrosis, glymphatic flow and Aβ clearance, presenting a novel therapeutic target for post-stroke dementia.

Abstract WP5: The Transfer Score May Aid Decisions Whether to Transfer Patients with Large Vessel Occlusions for Endovascular Therapy

Background: While faster reperfusion with EVT leads to better outcomes in acute ischemic stroke due to large vessel occlusion (LVO), most LVO patients present to outside hospitals without EVT capability. Treating physicians are often unsure if EVT would confer benefit upon arrival to tertiary hospitals given inter-facility transfer delays.

Objective: We evaluated independent predictors of good outcome in transferred patients treated with EVT to devise a score that may assist treating physicians to make transfer and treatment decisions.

Methods: Transfer patients were analyzed in a multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) from 11/2013 to 4/2016. Independent factors correlating with good outcome after EVT were identified using univariate and multivariate analyses. We devised a score to identify patients with LVO at the referral facility who may benefit from EVT.

Results: Of 1000 patients enrolled, 226 were anterior circulation occlusions, transferred and treated within 0-8 hrs (Table 1). Age, stroke severity, glucose level, M2 occlusion and achieving onset to groin puncture ≤ 5 hr were independent factors associated with good outcome (Table 2). Other clinical variables were analyzed, as in ASPECTS, but were not significant. A 10 point score was devised (Table 3). Patients with a score of 0-4 had 4 times the odds of good outcome compared to a score of 5-9 (aOR 4.3, 95% CI 1.9-9.9; p <0.001). These results were maintained after adjustment for mTICI and IV-tPA (aOR 4.0, 95% CI 1.7-9.4; p <0.001). Fig 1 shows good outcome rates stratified by score points. ROC curves showed better score performance (AUC= 0.8) compared to THRIVE (AUC=0.74) and HIAT (AUC=0.69) certifying good predictability.

Conclusion: A simple transfer score may be an effective triage method to identify patients at remote facilities who may benefit from EVT upon transfer. Further validation is necessary to confirm these findings.

Abstract WP110: Identification and Validation of a Unique Mirna Target Mir-141-3p in Post Stroke Socially Isolated Aged Mice

Introduction: MicroRNAs (miRNAs) are a class of short non-coding RNAs that have been identified as a powerful interventional tool for many diseases, including stroke. Very recent studies have found that microRNAs also mediate aspects of social interaction. Social environments can directly influence miRNA expression, which then triggers a plethora of downstream gene changes. Social isolation (SI) impairs stroke recovery and leads to inflammation. We hypothesize that miRNAs are involved in the detrimental effects of post-stroke social isolation.

Methods: Eighteen-month-old male C57BL/6 mice were pair housed (PH) for two weeks prior to stroke and randomly assigned to various housing conditions (ST-ISO or ST-PH) immediately after stroke (ST). Mice were sacrificed either at 3, 7 or 14 days after 60-minute right MCAO or sham surgery (n=4-6/group) and perilesional frontal cortex was isolated for miRNA analysis. Total RNA was isolated using either Qiagen miRNeasy® Mini Kit/ miRVANA miRNA isolation kit (Ambion, Life technologies). Whole miRNOme analysis of total RNA isolated from brain tissue was performed using miRCURY LNA TM Universal RT microRNA. Post-treatment with an ‘in vivo ready’ antagomir of miR-141-3p (7mg/kg i.v/day x 3 days; n=4/group) was given through lateral tail veins.

Results: Using whole miRNOme analysis of approx. 800 miRNA, we found miR-141-3p was a unique miRNA whose expression was significantly upregulated in a time dependent manner up to day 14 after stroke. The post treatment with an ‘in vivo ready’ antogomir of miR-141-3p reduced the isolation-induced increase in miR-141-3p to levels almost equal to that of pair-housed controls. Post- treatment significantly reduced mortality (by 21% as compared to -ve control) and sensory motor deficits after stroke. mRNA targets analysis study using qPCR confirmed the significant (p<0.05 vs Neg Control ) upregulation of target several genes like arg-1, ccl22 and TGFbr1, markers of M2 type microglial activation, after antogomir treatment. Summary: The present data suggests the unique role of miR-141-3p in post stroke isolation. Temporal expression profiling studies suggest its validation as a potential targets. Post treatment data confirms the in vivo feasibility of miRNA modulation after stroke.

Abstract WMP9: Endovascular Thrombectomy Impact in the First Three “Golden” Hours

Background: Endovascular thrombectomy (EVT) substantially increases the likelihood of good outcome in acute ischemic strokes due to large vessel occlusion (LVO). Expediting EVT to achieve faster reperfusion is an important factor that correlates with good outcome. Ultra-early intervention in the first 3 “golden” hours from onset was not well characterized in recent trials.

Objective: We sought to assess the impact of early treatment within the first 3 hours on clinical outcomes in large, real life, world-wide practice.

Methods: We analyzed a multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) between11/2013 and 4/2016. We stratified patients based on treatment time, onset to groin puncture (GP), into 3 groups: 0-3, 3-6, >6 hrs. 90 day mRS was the primary outcome (0-2 good outcome). Logistic regression modeling was performed to evaluate the impact of treatment within the golden 3 hours on outcomes and to determine the independent factors associated with EVT initiation within 3 hours.

Results: In the 905 patients, GP occurred in: 23.1% 0-3 hrs, 44.3% 3-6 hrs and 32.6% >6 hrs. Table 1 shows similar baseline characteristics among the groups. Patient-level predictors of treatment within 3 hrs were age (aOR 1.1 per decade of age ≥18) and good ASPECTS (aOR 1.2 per point). No hospital-level predictors of early treatment were found. Patients treated within 3 hrs have a higher likelihood of good outcome as compared to those treated >3 hrs (aOR 2.0, 95% CI 1.4-2.9; p <0.001) after adjustment for age, NIHSS, IV tPA and mTICI ≥2b (Table 2). No differences were found in mortality and sICH. Treatment in the golden hours had the highest impact on excellent outcome rates (mRS 0-1) (Fig 1).

Conclusion: Early thrombectomy of LVO strokes, within the first three hours provides the highest impact compared with later time windows. Streamlining processes to deliver rapid intervention within 3 hours would improve clinical outcomes.

Abstract TP20: Uncertainties of Endovascular Therapy Outside the AHA Guidelines

Background: The efficacy of endovascular therapy (EVT) in randomized clinical trials (RCTs) for acute strokes due to large vessel occlusion (LVO) led to AHA guidelines recommending EVT as standard of care for selected patients. However, many conditions were under-represented in the RCTs: ASPECTS <6, age ≥80 yo, NIHSS <6, onset to treatment >6 hrs and M2/ distal/ posterior circulation occlusions.

Objective: We evaluated EVT outcomes in these populations compared to counterparts represented in the RCTs.

Methods: A large multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry) between 11/2013 and 4/2016 was analyzed. 90 day mRS was the primary outcome (0-2 good outcome). Multivariate logistic regression modeling was employed to evaluate EVT impact in the different groups.

Results: Of 1000 patients, 81 had NIHSS <6 and 81.5% of those achieved a good outcome (aOR 3.6, 95% CI 1.9-6.8; p< 0.001 compared with NIHSS ≥6) (Table 1). Over 80 yo, however, had low odds of independence (aOR 0.3, 95% CI 0.2-0.5; p <0.001 compared with <80 yo). Among 212 patients treated >6 hrs, 51% had a good outcome (aOR 0.78, 95% CI 0.55-1.1; p =0.17) compared to ≤6 hrs. Nearly half of patients with ASPECTS <6 (3-5) had a good outcome. Fig 1 illustrates mRS distributions stratified by the different subgroups. There were low rates of sICH for treated patients with NIHSS<6, age≥80, ASPECTS <6 or treatment >6 hrs. Fig 2 demonstrates the likelihood of good outcome by clot location. M2 and distal occlusions had the highest good outcome probabilities while proximal ICAs had the lowest (48.1%). More than half of vertebrobasilar patients achieved independence (54.8%).

Conclusion: While effectiveness cannot be determined in the absence of medically treated controls, our analyses of real world data show several groups outside AHA guidelines may benefit from EVT. In particular, further study is needed to examine EVT benefits for mild stroke and M2 occlusions.

Abstract WMP106: Soluble CD163 as a Prognostic Marker for Perihematomal Edema Formation and Functional Outcomes in Intracerebral Hemorrhage

Introduction: Macrophages are the predominant cell capable of removing toxic hemoglobin at sites of tissue injury, and CD163 has been recognized as the hemoglobin scavenger receptor present on the macrophage cell surface. In this study, we explored the levels of soluble CD163 (sCD163) in patients with intracerebral hemorrhage (ICH) to ascertain whether sCD163 was associated with clinicoradiologic features and long-term functional outcomes.

Methods: Our ICH cohort was comprised of 50 patients with moderate-sized basal ganglia hematomas. We collected serial serum and cerebrospinal fluid (CSF) at pre-specified timepoints (24 hours, 48 hours, 3-5 days, 6-8 days, and greater than 10 days post-ictus). We also obtained samples from 10 healthy controls. Levels of sCD163 were measured by enzyme-linked immunosorbent assay. A linear mixed model was used to compare sCD163 values among various groups, using a Bonferroni correction for multiple test adjustment. The method of generalized estimating equations was used to determine associations with dichotomized outcomes (modified Rankin Scale score 0-3 versus 4-6).

Results: Compared to healthy controls, serum sCD163 was higher in the ICH patients (40.6 versus 128.4 ng/mL). Within the ICH cohort, early values (24 hours to 5 days post-ictus) of serum sCD163 were significantly higher in patients who elaborated minimal perihematomal edema (PHE) (200.3 in patients with less than 10 mL PHE versus 71.8; p = 0.046). 6 to greater than 10 days post-ictus, sCD163 levels tailed off for patients with less PHE whereas levels rose in patients with greater PHE. Continued subacute elevation of sCD163, particularly in the CSF, was highly associated with poorer outcomes, both at discharge and at 90 days (p < 0.001). These associations were independent of age, gender, peak hematoma volume, and ICH score; there was a statistically significant association of CSF sCD163 values with degree of intraventricular hemorrhage (p = 0.04).

Conclusions: sCD163 may be a dynamic marker in ICH, with acute levels distinguishing edema patterns and subacute levels predicting functional outcome. Further studies are needed to confirm these findings and explore the pathophysiology behind these observations.

Abstract WP4: Transfer Patients and Patients Presenting Directly to Endovascular Capable Centers Achieve Similar Good Outcome Rates with Endovascular Therapy

Background: While endovascular therapy (EVT) is effective for large vessel occlusions (LVO), most patients present to hospitals without EVT capability and are transferred for intervention, delaying treatment.

Objective: We evaluated outcomes in LVO patients treated with thrombectomy who were transferred compared to those presenting directly to EVT facilities.

Methods: In a large multicenter international prospective cohort study of LVO patients treated with stent retriever thrombectomy (TREVO Registry), patients were stratified by initial presentation into transferred (TNS) vs direct (DIR). 90 day mRS was the primary outcome (0-1 excellent, 0-2 good outcomes); sICH and reperfusion by mTICI were secondary outcomes. Outcomes were compared in the 2 groups (0-8 hrs onset to groin puncture (GP) then in time matched 3-8 hrs subgroups for validation). Logistic regression identified independent predictors of good outcome in TNS patients.

Results: We identified 540 patients (230 TNS; 310 DIR) (Fig 1). TNS patients were younger and had longer onset to GP times (4.6 vs 3.1 hrs; p <0.001) (Table 1). DIR achieved higher excellent outcomes (50.4 vs 38.7%; p <0.001) (Table 2). There were no significant differences in good clinical outcomes (61 DIR vs 57.4% TNS, OR 0.90, 95% CI 0.63-1.27; p =0.4) (Fig 2) and no difference in the time matched 3-8 hrs subgroups (59.2% DIR vs 56.3% TNS, p =0.6). Fig 3 plots good outcome probabilities over time, showing similar confidence interval bands. Younger age (OR 0.95), lower NIHSS (OR 0.90), glucose level < 170 mg/dL (OR 2.4), distal clot location (M2) (OR 1.7), excellent reperfusion (mTICI≥2b) (OR 2) and time to GP <5 hrs (OR 1.6) were independent predictors of good outcome in TNS patients.

Conclusion: While excellent outcomes were higher in directly-presenting patients, EVT-treated transfers may achieve similar good outcomes. The association between earlier EVT after transfer and better outcomes emphasizes the need to streamline the transfer process.

Abstract WP58: Correlating Stroke Volume with National Institute of Health Stroke Scale as a Means of Determining Patient Prognosis

Introduction: The NIH Stroke Scale (SS) is a widely used tool for directing treatment and predicting outcomes in Acute Ischemic Stroke (AIS). Severe strokes with high admission SS often correlate with long term disability, and as such, SS serves as a strong predictor of outcome. Final infarct volume (FIV) is also a pivotal predictor of stroke outcome. We aimed to evaluate the relationship between SS, FIV and outcome, and hypothesize that a combined approach evaluating both FIV and SS may more accurately correlate with patient outcomes.

Methods: A single center, retrospective cohort study, examined AIS patients with large vessel occlusion (LVO) affecting the anterior circulation, between July 2004 and April 2013. Patients were stratified by treatment to 1) intra-arterial therapy, 2) IV tPA, 3) both or 4) neither. Primary outcomes measured were mRS at discharge and 90 days (good outcome mRS 0-2, poor 4-6). FIV was manually calculated from DWI obtained within the first 7 days of presentation. SS and FIV were compared against good and poor mRS outcomes using Wilcoxon rank sum test. Logistic regression analysis was used to evaluate the association between SS, FIV and mRS. Finally, likelihood ratio test was used to compare model fit between a model including SS alone and model including both SS and FIV.

Results: In 332 patients, SS was significantly higher in the poor outcome group (17.3 ± 5.4) when compared to the good outcome group (13.0 ± 6.1) (p=0.0002). In the same analysis, FIVs were also larger in the poor outcome group (110.3 ± 113 cm3) when compared to the good outcome group (37.2 ± 68.3 cm3) (p<0.0001). A combined SS and FIV model correlated significantly better with discharge outcome than did SS alone (p=0.0015). Analysis of 182 patient outcomes at 90 days maintained similar findings, with SS (18 ± 5.9) and FIVs (115.4 ± 121.0 cm3) significantly higher in poor outcomes than in good outcomes; (13.0 ± 5.4) and (35.7 ± 38.2 cm3) respectively (p<0.0001). Combined SS and FIV model, again, was significantly better at modeling outcome at 90 days than was a model including SS alone (p=0.0044).

Conclusions: A combined model including FIV and SS better correlates with clinical outcomes at discharge and 90 days in patients with AIS due to LVO, than does a model using SS alone.

Abstract 46: The Influence of Age and Stroke on Gut Inflammation and Microbiota

Introduction: Earlier work by our laboratory and other groups has identified that aging leads to changes in both the immune system and the microbiome. The elderly have high mortality and more disability after a stroke, a finding that is recapitulated in murine model. Recently, pro-inflammatory γδ T cells have received increasing attention as a major contributor to gut immune responses. These cells may be a link in the bidirectional communication between the microbiome and the central nervous system. We hypothesize that fecal transplant of aged biome into young animals will enhance inflammation, γδ T cell numbers, and worsen functional recovery after stroke in young mice.

Methods: Young C57BL/6 male mice, were randomized and subjected to sham surgery/right middle cerebral artery occlusion (MCAO-60min) followed by reperfusion. All mice received streptomycin treatment at 24h and 48h after MCAO. Subsequently, mice were gavaged with biome from either young or aged animals at 72 and 96 h post-stroke. Behavioral and functional outcomes were evaluated. Animals were sacrificed 15 days after stroke. Brain atrophy was quantified, and Flow Cytometry (FACS) and immunohistochemistry was performed on gut tissue and spleen to determine if stroke or the aged biome influence γδ T cells.

Results: Young mice transplanted with aged biome take a longer time to regain their pre-stroke body weight. These mice have higher post-stroke hyperactivity compared with mice treated with young biome, as measured by average velocity (p<.006) and total distance traveled (p<.006) in the Open Field. Young mice given aged biome had poorer grip strength, as well as a depressive phenotype, when compared with mice transplanted with young biome. FACS analysis shows higher levels of γδ T cell in the gut with stroke and with fecal transplant of aged biome (sham vs. stroke p=0.0443; young vs. aged biome p=0.0199).

Conclusion: Collectively our findings suggests that the gut microbiome plays an important role in post-stroke recovery. Understanding the underlying mechanisms may identify novel therapeutic targets for the treatment of stroke patients.

Abstract WP122: Heterochronic Parabiosis Reverses the Epigenetic Imbalance of the Aged Central Nervous System

Background: Microglia, the innate immune cells of the central nervous system (CNS), are the first cellular responders to stroke. Microglia populate the brain during development and age throughout the life of the individual. With aging, microglia transition to an activated, pro-inflammatory phenotype, making them primed to respond in a malicious manner following an ischemic event. These primed microglia are the same cells that populated the brain during development but now have an altered gene expression profile due to the inflammaging environment (e.g. cell damage, inflammatory cytokine milieu). Cells, including microglia, may respond to inflammaging by altering their epigenetic landscape to ultimately result in changes in gene expression.

Hypothesis: We hypothesized that epigenetic mechanisms are responsible for the changes observed in microglia gene expression with aging, and that by definition these changes are reversible.

Methods: We utilized a model of heterochronic parabiosis in which young (2-3-month) and aged (18-20-month) male C57Bl/6 mice (Charles River, NIA) were surgically attached and share a common blood supply. Pairs were attached for 8 weeks. Young and aged isochronic pairs served as surgical controls. Brains were collected for immunohistochemical (IHC), Western blot, and multiplex cytokine analysis. P0.5-P3 neonatal pups were used for in vitro culture of primary microglia and were stimulated with lipopolysaccharide (LPS) and interferon-γ for 24hr.

Results: We screened 10 histone modifications and found that aging causes an imbalance in the epigenetic status of the CNS, with 1.26±0.08-fold higher histone H3 lysine 27 trimethylation (H3K27me3) and 0.649±0.063-fold reduced H3K27me1 (n=3, p<0.05). Pro-inflammatory stimulation of primary microglia resulted in elevated H3K27me3 (n=3, p<0.01), suggesting this mark is central to the pro-inflammatory status of aged microglia. Heterochronic parabiosis reversed these age-related changes, with reduced H3K27me3 in the brains of aged heterochronic mice (rejuvenation) and reduced H3K27me1 in young heterochronic mice (accelerated aging) (n=3-4, p<0.05).

Conclusion: We conclude that the aged CNS has an imbalanced epigenetic landscape, and that this is reversible.

Abstract WP120: MicroRNA Expression in Patients With Acute Ischemic Stroke

Background and Purpose: MicroRNAs (miRNAs) are a class of endogenous small non-coding ribonucleic acids that regulate gene expression and can impact cellular function by suppressing or activating downstream mRNA targets. Pre-clinical studies in animal models of stroke have demonstrated specific changes in miRNA expression profiles after ischemic stroke.

Methods: Patients admitted to Hartford Hospital from January 2011 - March 2014 were considered for this study. Blood samples were collected within 24 hours of stroke presentation. miRNA profiles from peripheral blood samples of ischemic stroke patients were compared to controls. Patients with acute middle cerebral artery (MCA) cardioembolic strokes (based on TOAST criteria) were included (n=16). Blood collected from patients with no acute neurological deficits in an outpatient setting served as controls (n=8). Individuals with a history of active cancer, neoplastic brain lesions or traumatic brain injury were excluded. Based on literature review, 173 miRNAs were selected to assess for differential expression between cases and controls. miRNA profiling was conducted at Exiqon Services, Denmark, using miRCURY LNA™ microRNA Array. Statistical analysis was performed using SAS.

Results: In patients with acute ischemic strokes, a statistically significant differential expression was observed in 14 miRNAs as compared to controls. MicroRNAs miR-1273e, miR-5187-3p were found to be downregulated in stroke patients (p=0.01). Other miRNAs showing a significant downregulation included let 7e-5p (p=0.03); miR-4709-3p, miR-4756-3p, miR-5584-3p, miR-647 (p=0.02); miR-4742-3p (p=0.03); miR-4764-5p, miR-4531 and miR-2116-5p (p=0.04). MicroRNAs miR-664a-3p (p=0.02), miR-943 (p=0.04) and miR-145-5p (p=0.03) were significantly upregulated. Differential expression in males and females was not observed.

Conclusion: Ischemic stroke patients show a differential microRNA expression profile as compared to controls. Further studies can help identify microRNA signatures as well as the downstream targets involved in the ischemic stroke molecular cascade.

Abstract WP283: Sex Differences in Hipoxic-ischemic Encephalopathy Are Modulated by Cx3cl1/Cx3cr1 Signaling

Background: Neonatal hypoxic-ischemic encephalopathy (HIE) is a major cause of cognitive impairment in children. Clinically, male infants are more sensitive to the ischemic insult and have worse long-term deficits than girls. The mechanism underlying the sex difference remains elusive. Our previous study using an HIE animal model on post-natal day 10 (P10) mice has revealed that male animals exhibited worse outcomes than females, corresponding to an increased microglial activation that initiates post-ischemia immune responses. CX3CL1/CX3CR1 axis is an endogenous inhibitory signaling pathway that keeps microglia quiescent in normal brains. Whether the CX3CL1/CX3CR1 axis is sex-differently expressed in neonatal brains to cause the sexually dimorphic phenotypes of HIE is not known.

Hypothesis: We hypothesize that neonatal female brains are protected against HIE due to a more robust CX3CL1/CX3CR1 signaling compared to males and that manipulation of CX3CL1/CX3CR1 axis has sex-specific effects on HIE.

Methods: C57BL6 P10 mice (WT) of both sexes were subjected to a 45-min Rice-Vanucci model (RVM) to induce HIE. CX3CR1 expression, microglial activation, and the infiltration of peripheral leukocytes were examined by flow cytometry. CX3CR1 knockout mice were also used to evaluate the effect of genetic deletion of CX3CL1/CX3CR1 signaling.

Results: WT females had a better outcome after neonatal HIE. In addition, WT females have significantly higher expression of CX3CR1 on microglia at baseline than males, measured by CX3CR1 MFI with flow cytometry. Importantly, the majority of the CX3CR1 + microglia co-expressed CD206, a marker of anti-inflammatory phenotype for phagocytes. CX3CR1 KO females lost the resistance to ischemic damage as the knockout of CX3CR1 gene led to exacerbate HIE outcomes only in females.

Conclusions: The high expression of CX3CR1 primes female brains to resist inflammatory responses to HIE and has beneficial effects, though the protective mechanism is not sufficient in male brains. Sex differences seen in neonatal HIE are at least in part ascribed to the sexually dimorphic CX3CL1/CX3CR1 signaling.

Funding: R01: NS093042 and R21: NS091794 to Fudong Liu.

Abstract WP101: Hypoxia Drives Anti-inflammatory Polarization of Microglia in Ischemic Stroke

Background: As the innate immune cell of the central nervous system (CNS), microglia are poised to be the first cellular responders to ischemic stroke. Microglia are capable of polarizing from a resting (M0) phenotype to a pro-inflammatory (M1) or anti-inflammatory (M2) phenotype depending on the signals these cells receive from the microenvironment. Typically cell damage through neurological injury results in a pro-inflammatory phenotype. Paradoxically, despite the cell death that occurs following ischemic stroke that presumably polarizes microglia to a pro-inflammatory phenotype, our lab and others have shown that microglia in mice are predominantly anti-inflammatory after ischemic stroke.

Hypothesis: To possibly explain this anomaly, we hypothesized that hypoxia itself is a stimulus of anti-inflammatory microglia M2 polarization following ischemic stroke that overrides pro-inflammatory polarizing signals from cellular damage.

Methods: We developed a novel method of culturing primary microglia from individual male and female neonatal mice. We then exposed isolated microglia to oxygen glucose deprivation (OGD, 95% nitrogen / 5% carbon dioxide) and examined the expression of M1 and M2 genes by quantitative PCR. Media was collected at 24hr and analyzed by lactate dehydrogenase (LDH) assay and ELISA.

Results: We found that microglia are resistant to OGD-induced cytotoxicity, with LDH assay showing only 16% cell death after 8hr of OGD (p<0.05). OGD induced a robust up-regulation of anti-inflammatory M2 genes (Interferon Regulatory Factor 4 (IRF4), 2.08±0.08-fold, p<0.05; Vascular Endothelial Growth Factor (VEGF), 1.76±0.05-fold, p<0.0001) immediately following OGD and also down-regulated expression of pro-inflammatory M1 genes (IRF5, 0.385±0.018-fold, p<0.0001; Interleukin-1β (IL1B), 0.018±0.005-fold, p<0.01; Tumor Necrosis Factor-α (TNFA), 0.345±0.024-fold, p<0.0001) in both male and female microglia (n=7). ELISA of cell culture supernatant following OGD demonstrated that microglia secrete VEGF, suggesting OGD-treated microglia have anti-inflammatory functions.

Conclusion: Collectively, our data suggest that hypoxia drives both male and female microglia to polarize to an anti-inflammatory M2 phenotype.

TGF-β1 modulates microglial phenotype and promotes recovery after intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is a devastating form of stroke that results from the rupture of a blood vessel in the brain, leading to a mass of blood within the brain parenchyma. The injury causes a rapid inflammatory reaction that includes activation of the tissue-resident microglia and recruitment of blood-derived macrophages and other leukocytes. In this work, we investigated the specific responses of microglia following ICH with the aim of identifying pathways that may aid in recovery after brain injury. We used longitudinal transcriptional profiling of microglia in a murine model to determine the phenotype of microglia during the acute and resolution phases of ICH in vivo and found increases in TGF-β1 pathway activation during the resolution phase. We then confirmed that TGF-β1 treatment modulated inflammatory profiles of microglia in vitro. Moreover, TGF-β1 treatment following ICH decreased microglial Il6 gene expression in vivo and improved functional outcomes in the murine model. Finally, we observed that patients with early increases in plasma TGF-β1 concentrations had better outcomes 90 days after ICH, confirming the role of TGF-β1 in functional recovery from ICH. Taken together, our data show that TGF-β1 modulates microglia-mediated neuroinflammation after ICH and promotes functional recovery, suggesting that TGF-β1 may be a therapeutic target for acute brain injury.

Nano-particle delivery of brain derived neurotrophic factor after focal cerebral ischemia reduces tissue injury and enhances behavioral recovery

BACKGROUND

Low levels of brain-derived neurotrophic factor (BDNF) are linked to delayed neurological recovery, depression, and cognitive impairment following stroke. Supplementation with BDNF reverses these effects. Unfortunately, systemically administered BDNF in its native form has minimal therapeutic value due to its poor blood brain barrier permeability and short serum half-life. In this study, a novel nano-particle polyion complex formulation of BDNF (nano-BDNF) was administered to mice after experimental ischemic stroke.

METHODS

Male C57BL/6J (8-10weeks) mice were randomly assigned to receive nano-BDNF, native-BDNF, or saline treatment after being subjected to 60min of reversible middle cerebral artery occlusion (MCAo). Mice received the first dose at 3 (early treatment), 6 (intermediate treatment), or 12h (delayed treatment) following stroke onset; a second dose was given in all cohorts at 24h after stroke onset. Post-stroke outcome was evaluated by behavioral, histological, and molecular analysis for 15days after stroke.

RESULTS

Early and intermediate nano-BDNF treatment led to a significant reduction in cerebral tissue loss. Delayed treatment led to improved memory/cognition, reduced post-stroke depressive phenotypes, and maintained myelin basic protein and brain BDNF levels, but had no effect on tissue atrophy.

CONCLUSIONS

The results indicate that administration of a novel nano-particle formulation of BDNF leads to both neuroprotective and neuro-restorative effects after stroke.

Early retinal inflammatory biomarkers in the middle cerebral artery occlusion model of ischemic stroke

PURPOSE

The transient middle cerebral artery occlusion (MCAO) model of stroke is one of the most commonly used models to study focal cerebral ischemia. This procedure also results in the simultaneous occlusion of the ophthalmic artery that supplies the retina. Retinal cell death is seen days after reperfusion and leads to functional deficits; however, the mechanism responsible for this injury has not been investigated. Given that the eye may have a unique ocular immune response to an ischemic challenge, this study examined the inflammatory response to retinal ischemia in the MCAO model.

METHODS

Young male C57B/6 mice were subjected to 90-min transient MCAO and were euthanized at several time points up to 7 days. Transcription of inflammatory cytokines was measured with quantitative real-time PCR, and immune cell activation (e.g., phagocytosis) and migration were assessed with ophthalmoscopy and flow cytometry.

RESULTS

Observation of the affected eye revealed symptoms consistent with Horner's syndrome. Light ophthalmoscopy confirmed the reduced blood flow of the retinal arteries during occlusion. CX3CR1-GFP reporter mice were then employed to evaluate the extent of the ocular microglia and monocyte activation. A significant increase in green fluorescent protein (GFP)-positive macrophages was seen throughout the ischemic area compared to the sham and contralateral control eyes. RT-PCR revealed enhanced expression of the monocyte chemotactic molecule CCL2 early after reperfusion followed by a delayed increase in the proinflammatory cytokine TNF-α. Further analysis of peripheral leukocyte recruitment by flow cytometry determined that monocytes and neutrophils were the predominant immune cells to infiltrate at 72 h. A transient reduction in retinal microglia numbers was also observed, demonstrating the ischemic sensitivity of these cells. Blood-eye barrier permeability to small and large tracer molecules was increased by 72 h. Retinal microglia exhibited enhanced phagocytic activity following MCAO; however, infiltrating myeloid cells were significantly more efficient at phagocytizing material at all time points. Immune homeostasis in the affected eye was largely restored by 7 days.

CONCLUSIONS

This work demonstrates that there is a robust inflammatory response in the eye following MCAO, which may contribute to a worsening of retinal injury and visual impairment. These results mirror what has been observed in the brain after MCAO, suggesting a conserved inflammatory signaling response to ischemia in the central nervous system. Imaging of the eye may therefore serve as a useful non-invasive prognostic indicator of brain injury after MCAO. Future studies are needed to determine whether this inflammatory response is a potential target for therapeutic manipulation in retinal ischemia.

Age-Associated Resident Memory CD8 T Cells in the Central Nervous System Are Primed To Potentiate Inflammation after Ischemic Brain Injury

Aging is associated with an increase in basal inflammation in the CNS and an overall decline in cognitive function and poorer recovery following injury. Growing evidence suggests that leukocyte recruitment to the CNS is also increased with normal aging, but, to date, no systematic evaluation of these age-associated leukocytes has been performed. In this work, the effect of aging on CNS leukocyte recruitment was examined. Aging was associated with more CD45(high) leukocytes, primarily composed of conventional CD8(+) T cells. These results were strain independent and seen in both sexes. Intravascular labeling and immunohistology revealed the presence of parenchymal CD8(+) T cells in several regions of the brain, including the choroid plexus and meninges. These cells had effector memory (CD44(+)CD62L(-)) and tissue-resident phenotypes and expressed markers associated with TCR activation. Analysis of TCRvβ repertoire usage suggested that entry into the CNS is most likely stochastic rather than Ag driven. Correlational analyses revealed a positive association between CD8 T cell numbers and decreased proinflammatory function of microglia. However, the effects of cerebral ischemia and ex vivo stimulation of these cells dramatically increased production of TNF, IFN-γ, and MCP-1/CCL2. Taken together, we identified a novel population of resident memory, immunosurveillant CD8 T cells that represent a hallmark of CNS aging and appear to modify microglia homeostasis under normal conditions, but are primed to potentiate inflammation and leukocyte recruitment following ischemic injury.

The Importance of Considering Sex Differences in Translational Stroke Research

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.

Abstract 94: Increased P450 Aromatase Level in Post-menopausal Women After an Acute Ischemic Stroke

Background: Ischemic stroke is a sexually dimorphic disease. Sex differences in stroke have been attributed to neuroprotective effects of estrogen, yet most clinical trials of estrogen supplementation have shown detrimental effects. The role of sex hormones in stroke is still a subject of debate. Aromatization of testosterone to estradiol in neural tissue leads to sexual differentiation. Emerging data suggests similar aromatase activity in response to brain injury, as increased aromatase expression is seen in ischemic penumbra in animals. Administration of aromatase inhibitors exacerbates damage in experimental stroke models. However, studies on sex steroids in humans are sorely lacking. Objective of this study was to investigate the contributions of sex steroids to the etiology of sex differences in stroke .

Methods: 253 patients admitted to Hartford Hospital for focal neurological deficit were consented for 24hour blood draw from symptom onset. Stroke was confirmed by CTscan/MRI brain. Patients with intracerebral or subarachnoid hemorrhage, age<56 years, were excluded from the study. Controls were patients with transient ischemic attack/seizure. ELISA was run for estradiol, testosterone &P450 aromatase levels in serum.

Results: In age matched men & women, no difference in estradiol levels was seen. For testosterone, main effect of sex, F(1,3)=26,p<0.001 & sex by stroke interaction F(1,3)=4.7,p<0.03 was seen. There was a significant effect of stroke, F(1,3)=9.3,p<0.003 & sex by stroke interaction, F(1,3)=5.8,p<0.01 in aromatase levels (*).

Conclusions: Aromatase levels increase in post-menopausal women after acute ischemic stroke. This may indicate increased aromatase activity as testosterone levels also decreased as compared with controls. Local production of estradiol may occur in the injured female brain mediated by aromatase as seen in prior animal studies. Ongoing work will assess functional outcomes and correlation with hormonal levels.

Abstract 171: The Effect of Ischemia and Reperfusion and Tissue Plasminogen Activator on Cerebrovascular Function, Oxidative Stress and Polymorphonuclear Neutrophils in Ovariectomized Female Rats

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<0.05) and reduced constriction to L-NNA (Sham Vh: 35±3%, Sham tPA: 34±2% vs. MCAO Vh: 20±3%, MCAO tPA: 25±3%, P<0.01) with no effect on dilation to Y27632. In PA, myogenic tone (at 40 mmHg) and reactivity to L-NNA and Y27632 was not affected by I/R. PA were less sensitive to Y27632 than MCA after I/R with tPA (EC50: 2.0±0.5 vs. 0.8±0.1 μM, P<0.05). F-actin and NT in the MCA were not affected by I/R or tPA. The number of PMN was small (<0.8±0.3/mm2) in all groups but there was a trend to increased ipsilateral intravascular PMN after I/R with tPA.

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.

Abstract WP217: Sex Differences in Coagulation After Stroke: Factor XI Levels Drop After Acute Ischemic Stroke

Introduction: Sex differences in coagulation have been well documented, but it is unknown if post-stroke coagulation factor levels differ by sex. High levels of Factor XI (FXI) and Factor XII (FXII) have been associated with increased incidence of acute ischemic stroke (AIS), especially in women.

Hypothesis: This study investigates the hypothesis that levels of FXI, FXII and Plasminogen Activating Inhibitor (PAI1) are different after AIS in men and women.

Methods: This was a retrospective study using a biomarker database of patients who presented to the emergency department with stroke. Sample collection occurred 24 hours after AIS onset. Plasma levels of FXI, FXII and PAI1 were assessed with ELISA in a population of 73 patients with no prior history of coagulation disorders, including 29 controls and 44 AIS patients confirmed by MRI, mean age = 68.7+/- 15.1, and 47% female. Log transformation was done before fitting the model. ANOVA was used to investigate the relationship between factor levels in sex and stroke. Tukey-Kramer multiple comparison tests were used for paired group comparisons.

Results: FXI levels were significantly higher in control subjects compared to AIS (p-value=0.007). FXI levels were also higher in females than in males, nearing statistical significance (p-value=0.053). PAI1 and FXII levels were not statistically different in men vs. women, or in control vs. AIS patients. Female controls had higher FXI levels than male AIS patients (0.487, 95% CI 0.085-0.889).

Conclusion: Stroke patients were found to have significantly lower levels of FXI compared to controls. This demonstrates that the pathological process of AIS may result in depletion of circulating plasma FXI at 24 hours after stroke onset. Overall, in stroke and control patients, there was a trend for females to have higher levels of FXI than men. No significant sex or stroke differences were found in FXII or PAI1 levels, likely due to sample size. Additional samples are being evaluated to determine if this stroke-induced decrease in FXI levels is associated with functional outcomes.

Abstract TP452: Systemic Inflammation Reverses Stroke-induced Changes in Astrocytic Aquaporin-4 Expression

Introduction: Aquaporin-4 (AQP4) is a perivascular water channel that plays a key role in regulating the blood-brain barrier (BBB). Stroke acutely reduces expression and polarization of AQP4 on astrocytic endfeet, and these vascular changes might persist chronically and evolve with systemic inflammation. Reduced polarization of AQP4 after traumatic brain injury (TBI) leads to impaired perivascular clearance of debris and cognitive decline in mice, and if similar changes occur after stroke, then they may also contribute to post-stroke dementia.

Hypothesis: Stroke will cause lasting changes in vascular organization, reducing astrocytic AQP4 expression and polarization in the area of injury.

Methods: Thirty male Balb/cJ mice were subjected to distal middle cerebral artery ligation, allowed to survive for 28 days, and sacrificed 24 hours after injection with lipopolysaccharide (LPS, 0.33 mg/kg i.p.) or saline to model systemic inflammation. Three sequential coronal sections (20 μm) near the site of infarct (0.25 mm from Bregma) were stained with lectin, AQP4, and glial fibrillary acidic protein (GFAP) to evaluate BBB organization. Vessel density was evaluated with AngioTool. AQP4 expression was evaluated by Western blot.

Results: Stroke increased vascular density in the injured hemisphere (11 ± 0.8% vs 7.6 ± 0.8% in sham mice, p < 0.05). Decreased AQP4 expression and polarization near the site of the infarct was observed, which were reversed with LPS (Figure 1). LPS increased AQP4 protein levels in stroke (2.5 ± 0.37 fold-increase, p < 0.05), but not sham mice.

Conclusions: Stroke caused a chronic increase in vascular density, with peri-infarct vessels displaying decreased expression and changed polarity of AQP4. However, with systemic inflammation, this is reversed, potentially contributing to neuroinflammation and worsened cognitive outcomes in stroke patients who encounter infections via increased permeability of these abnormal vessels.

Abstract WP270: Myeloid P2X4 Receptor Deletion Confers Neuroprotection in Females but not in Males After Experimental Stroke

Objective: Stroke is a sexually dimorphic disease. A growing body of literature from both clinical and experimental studies suggests that the outcomes after stroke differ in males versus females. Peripheral immune cells play a key role in stroke outcomes and also show sexual dimorphism. However, general immunosuppression has not shown an overall benefit in stroke patients. Therefore, identifying novel targets to improve stroke outcomes are urgently needed. P2X4 receptors (P2X4R) and P2X7 receptors (P2X7R) are the predominant subtypes expressed on immune and neural cells. The P2X7R and P2X4R interact and may physically associate with each other. Recent evidence demonstrates that P2X4R is necessary for the pro-inflammatory function of P2X7R. The goal of this study is to test the hypothesis that genetic deletion of P2X4R in myeloid immune cells impacts on stroke outcome and that such outcome differs in males vs. female mice.

Methods: P2X4R myeloid knockout mice and wild type littermates of both sexes (∼20-25g; C57BL/6), were randomized and subjected to right middle cerebral artery occlusion (MCAO-90min) followed by 3 days of reperfusion. At 72h after stroke mice were perfused and infarcts were quantified from 30μicron cut cresyl violet stained sections. The effect of myeloid P2X4R deletion on chronic functional recovery was assessed with neurological scores, corner test, Open field and the novel object recognition test. Data are expressed as mean±sem. ANOVA was performed and a P < .05 was set for statistical significance.

Results: A significant neuroprotective effect is seen in P2X4R KO compared to WT females (Cortex 36.1±1.5 vs 27.5±4.7; Striatum 67.4±1.5 vs 56.3±7.0; Total 34.8±1.6 vs 26.9±2.8. P<.05; n=7KO, 9WT). Ongoing studies in P2X4R KO ovariectomized females will determine if these sex specific effects are dependent on hormones (estrogen).

Conclusions: There is a sex-specific effect of immune cell P2X4R deletion. Myeloid specific deletion of P2X4R protects females from ischemia/reperfusion injury but has no salutary effect in males. This is the first study to demonstrate a deleterious effect of myeloid P2X4R on stroke outcomes. These initial findings implicate myeloid P2X4 as a novel therapeutic approach to improve ischemic outcomes in females.

Abstract TP375: Vitamin D Deficiency Correlates With Stroke Severity on Presentation in Intracerebral Hemorrhage

Introduction: Vitamin D, a neurosteroid present in cerebrospinal fluid and metabolized by brain tissue regulates calcium signaling and scavenging of reactive oxygen species, which play a role in acute cell injury after ischemic stroke and intracerebral hemorrhage (ICH). Low vitamin D (measured as 25(OH)D), has been found to increase the risk of ischemic stroke, predict severity and poor functional outcome. No studies investigating impact of vitamin D level on ICH stroke severity exist.

Hypothesis: We hypothesize that low 25(OH)D levels are associated with higher stroke severity of ICH on admission and poorer functional outcome.

Methods: A single-center retrospective chart review between February 2012 and September 2014 was performed. A total of 109 patients with primary ICH and 25(OH)D levels on admission were identified. Serum 25(OH)D levels were dichotomized at <30 ng/ml as Vitamin D deficient and <10 ng/ml as severely deficient. Dichotomized 25(OH)D groups were compared for continuous outcome variables using non-parametric Wilcoxon rank-sum test. Severity measures including dichotomized NIHSS (>20 or <20) and dichotomized Glasgow coma scale (GCS of 3-5, 6-15) were compared to vitamin D groups using Pearson Chi-square test of proportion.

Results: NIHSS on admission was higher in patients with severe vitamin D deficiency (p=0.016) with the odds ratio of having an NIHSS of >20 on admission 5.9 (95% CI --1.4-25.5). Patients with severe deficiency were far more likely to have very low GCS (3-5) (p=0.022; OR=8.8; 95% CI 1.7 - 45.5). Vitamin D deficiency was associated with lower pre-albumin level and older age (p=0.021 and 0.018, respectively). No statistical significance between 25(OH)D level and ICH score, ICH volume, location, presence of intraventricular hemorrhage, length of stay, mortality, disposition or pre-stroke and discharge modified Rankin Scale was found.

Conclusions: ICH patients with severe vitamin D deficiency had significantly worse stroke severity. Patients with older age and malnutrition are at higher risk for severe clinical presentation of ICH. Larger scale studies identifying increased risk of morbidity and mortality from ICH in vitamin D deficient patients are needed.

Abstract WMP45: Manipulation of the Microbiome Improves Functional Recovery After Ischemic Stroke

Background: Circulating inflammatory markers increase with age. This pro-inflammatory milieu makes the organism less capable of coping with stressors such as stroke. Age related inflammation occurs in both the brain and peripheral tissues like the gastro-intestinal tract. There is increasing recognition that commensal bacteria in the GI tract are altered with age or with germ-free housing, affecting the brain. The change occurs most notably in the ratio of two major phyla of the microbiome, the Firmicutes and Bacteroidetes . Young age is associated with a low ratio of the two but this ratio increases with age, which has been linked to many diseases including obesity, hypertension, and diabetes which are major risk factors for stroke.

Hypothesis: We hypothesized that there would be age-related differences in the microbiome, and that restoration of a young microbiome would improve functional recovery in aged mice.

Methods: Fecal transplants from young and aged donors were administered to recipient animals after suppression of endogenous microbial compositions through concentrated Streptomycin. This allowed for successful colonization of the gut with the newly transplanted microbiome. A transient middle cerebral artery occlusion (MCAO) was used in young (3-4 month) and aged (18-20 month) male mice 4 weeks after transplant. Functional recovery was assessed by neurological deficit scores, the hang wire test, and open field activity. The Y-maze was used to assess cognitive impairment.

Results: We successfully reversed the microbiomes of aged organisms and gave young animals “aged” biomes. Animals with “aged” microbiomes prior to stroke had worsened functional recovery based on all behavioral tests. The “aged” biome increased mortality rates most notably in the young recipients which had over 50% mortality. Aged mice had significantly improved functional recovery as assessed by the HW test ( P < 0.05 ) and NDS after reconstitution of “young” microbiome prior to stroke compared to aged control animals with the normal “aged” microbiomes.

Conclusion: Aged mice have high Firmicutes and Bacteroidetes relative abundances. Manipulation of the microbiome in young and aged mice is possible. Restoration of a youthful biome improved functional recovery in aged mice.

Abstract 65: Restoration of Growth Differentiation Factor 11 Protects Against Stroke in Mice

Introduction: GDF 11 is a member of the transforming growth factor β superfamily. Loss of GDF11 occurs with aging and declining levels correlate with several detrimental age-associated phenotypes in both peripheral tissues and brain. Restoration of GDF11 enhances neurogenesis and cognitive function in aged mice. Brain expression of GDF11 has not been investigated after stroke. Stroke differentially affects the elderly. In this work we examined the role of GDF11 in aging, stroke and its potential utility as a neuroprotective agent.

Methods: Male C57/BL6NCrl young (2-3 months) and aged (19-21) mice were used. Brain GDF11 expression was evaluated in young and aged mice by western blot. Focal ischemia was induced with a transient middle cerebral artery occlusion (MCAO). Mice were randomly assigned into two groups and were subjected to 90 min MCAO. Group 1 received vehicle (phosphate buffered saline) and group 2 was administered rGDF11 (100 ug/kg., ip) at the onset of ischemia. In additional experiments, the efficacy of delayed treatment (3 h after ischemia) with rGDF11 was tested. These mice were subjected to a 60 min MCAO. Mice were euthanized after 24 hours and 7 days respectively and brains were harvested to estimate infarct area.

Results: A significant decrease in brain GDF11 levels was observed in aged mice as compared to young (p<0.05). Additionally, a significant decline in brain GDF11 expression was observed after stroke at 24 hours vs. sham groups (p<0.05). A significant decrease in cortical and hemispheric infarct area was observed in the rGDF11 group (cortical 48.73±1.05; hemisphere 49.68±3.58) as compared to vehicle group (60.54±4.88; 61.35±6.03), when GDF was administered at the time of ischemia. Delayed treatment with rGDF11 also reduced infarct at 7 days.

Conclusions: Brain GDF11 levels decline with age and after stroke. Supplementation with rGDF11 ameliorates stroke induced injury in young mice at 24h and 7 days. These finding suggest potential role of GDF11 in age and stroke. Restoration of age-related loss of GDF may be a viable therapy for stroke.

A survey of blood pressure parameters after aneurysmal subarachnoid hemorrhage

Purpose/aim: Blood pressure (BP) regulation is recommended following aneurysmal subarachnoid hemorrhage (aSAH) to prevent re-bleeding and to treat delayed cerebral ischemia. However, optimal BP thresholds are not well established. There is also variation with regard to the BP component (e.g. systolic vs. mean) that is targeted or manipulated.

MATERIALS AND METHODS

An 18-question survey was distributed to physicians and advanced practitioner members of the Neurocritical Care Society. Respondents were asked which BP parameter they manipulated and what their thresholds were in different clinical scenarios. They were also asked whether they were influenced by the presence of incidental aneurysms. Answers were analyzed for differences in training background and treatment setting.

RESULTS

There were 128 responses. The majority were neurointensivists (47 neurology and 37 non-neurology) and treated patients in dedicated neurointensive care units (n = 98). Systolic BP (SBP) was preferred over mean arterial pressure (MAP). Prior to aneurysm treatment, SBP limits ranged from 140 to 180 mm Hg. After aneurysm treatment, SBP limits ranged from 160 to 240 mm Hg. The maximum and minimum MAPs varied by as much as 50%. Nearly two-thirds of the respondents were influenced by the presence of incidental aneurysms. Training background influenced tolerance to BP limits with neurology-trained neurointensivists accepting higher BP limits when treating delayed ischemia ( p = .018). They were also more likely to follow SBP ( p = .018) and have a limit of 140 mm Hg prior to aneurysm treatment ( p = .001).

CONCLUSIONS

There is large practice variability in BP management following aSAH. There is also uncertainty over the importance of incidental aneurysms. Further research could evaluate whether this variability has clinical significance.

Polyuria and cerebral vasospasm after aneurysmal subarachnoid hemorrhage

Background

Natriuresis with polyuria is common after aneurysmal subarachnoid hemorrhage (aSAH). Previous studies have shown an increased risk of symptomatic cerebral vasospasm or delayed cerebral ischemia (DCI) in patients with hyponatremia and/or the cerebral salt wasting syndrome (CSW). However, natriuresis may occur in the absence of hyponatremia or hypovolemia and it is not known whether the increase in DCI in patients with CSW is secondary to a concomitant hypovolemia or because the physiology that predisposes to natriuretic peptide release also predisposes to cerebral vasospasm. Therefore, we investigated whether polyuria per se was associated with vasospasm and whether a temporal relationship existed.

Methods

A retrospective review of patients with aSAH was performed. Exclusion criteria were admission more than 48 h after aneurysmal rupture, death within 5 days, and the development of diabetes insipidus or acute renal failure. Polyuria was defined as >6 liters of urine in a 24 h period. Vasospasm was defined as a mean velocity > 120 m/s on Transcranial Doppler Ultrasonography (TCDs) or by evidence of vasospasm on computerized tomography (CT) or catheter angiography. Multivariable logistic regression was performed to assess the relationship between polyuria and vasospasm.

Results

95 patients were included in the study. 51 had cerebral vasospasm and 63 met the definition of polyuria. Patients with polyuria were significantly more likely to have vasospasm (OR 4.301, 95 % CI 1.378–13.419) in multivariate analysis. Polyuria was more common in younger patients (52 vs 68, p <.001) but did not impact mortality after controlling for age and disease severity. The timing of the development of polyuria was clustered around the diagnosis of vasospasm and patients with polyuria developed vasospasm faster than those without polyuria.

Conclusions

Polyuria is common after aSAH and is significantly associated with cerebral vasospasm. The development of polyuria may be temporally related to the development of vasospasm. An increase in urine volume may be a useful clinical predictor of patients at risk for vasospasm.

Sex differences and the role of IL-10 in ischemic stroke recovery

Females experience poorer recovery after ischemic stroke compared to males, even after controlling for age and stroke severity. IL-10 is an anti-inflammatory cytokine produced by T regulatory cells and Th2 CD4⁺ helper T cells. In ischemic stroke, an excessive IL-10 response contributes to post-stroke immunosuppression, which worsens outcomes. However, it is unknown if sex differences exist in IL-10 levels after ischemic stroke. In this study, we found that higher levels of IL-10 were associated with poor acute and long-term outcomes after ischemic stroke in female patients but not in males. After controlling for confounders, IL-10 was not an independent predictor of functional outcomes. This suggests that higher serum IL-10 levels may reflect factors that interact with sex such as age and stroke severity.

Thyroid hormones and functional outcomes after ischemic stroke

Background

Stroke is the fifth leading cause of death and the primary cause of long-term adult disability in the United States. Increasing evidence suggests that low T3 levels immediately following acute ischemic stroke are associated with greater stroke severity, higher mortality rates, and poorer functional outcomes. Prognosis is also poor in critically ill hospitalized patients who have non-thyroidal illness syndrome (NTIS), where T3 levels are low, but TSH is normal. However, data regarding the association between TSH levels and functional outcomes are contradictory. Thus, this study investigated the role of TSH on stroke outcomes, concomitantly with T3 and T4.

Findings

In this work, blood was collected from patients with radiologically confirmed acute ischemic stroke at 24±6 hours post-symptom onset and serum levels of TSH, free T3, and free T4 were measured. Stroke outcomes were measured at discharge, 3 and 12 months using the modified Rankin scale and modified Barthel Index as markers of disability. Though we found that lower levels of free T3 were associated with worse prognosis at hospital discharge, and at 3 and 12 months post-stroke, none of these outcomes held after multivariate analysis. Thus, it is likely that thyroid hormones are associated with other factors that impact stroke outcomes, such as sex, age and stroke etiology.

Conclusions

This study found that lower levels of free T3 were associated with poorer outcomes at hospital discharge, and at 3 and 12 months post stroke, however, these associations diminished after correction for other known predictors of stroke outcome. Thyroid hormones have a complex relationship with ischemic stroke and stroke recovery, which merits further larger investigations.

Inhibition of glycogen synthase kinase-3β enhances cognitive recovery after stroke: the role of TAK1

Memory deficits are common among stroke survivors. Identifying neuroprotective agents that can prevent memory impairment or improve memory recovery is a vital area of research. Glycogen synthase kinase-3β (GSK-3β) is involved in several essential intracellular signaling pathways. Unlike many other kinases, GSK-3β is active only when dephosphorylated and activation promotes inflammation and apoptosis. In contrast, increased phosphorylation leads to reduced GSK-3β (pGSK-3β) activity. GSK-3β inhibition has beneficial effects on memory in other disease models. GSK-3β regulates both the 5'AMP-activated kinase (AMPK) and transforming growth factor-β-activated kinase (TAK1) pathways. In this work, we examined the effect of GSK-3β inhibition, both independently, in conjunction with a TAK inhibitor, and in AMPK-α2 deficient mice, after stroke to investigate mechanistic interactions between these pathways. GSK-3β inhibition was neuroprotective and ameliorated stroke-induced cognitive impairments. This was independent of AMPK signaling as the protective effects of GSK-3β inhibition were seen in AMPK deficient mice. However, GSK-3β inhibition provided no additive protection in mice treated with a TAK inhibitor suggesting that TAK1 is an upstream regulator of GSK-3β. Targeting GSK-3β could be a novel therapeutic strategy for post-stroke cognitive deficits.