Catecholamines, infection, and death in acute ischemic stroke

Decreased levels of hydrogen sulfide in the hypothalamic paraventricular nucleus contribute to sympathetic hyperactivity induced by cerebral infarction

Paroxysmal sympathetic hyperactivity (PSH) is a common clinical feature secondary to ischemic stroke (IS), but its mechanism is poorly understood. We aimed to investigate the role of H2S in the pathogenesis of PSH. IS patients were divided into malignant (MCI) and non-malignant cerebral infarction (NMCI) group. IS in rats was induced by the right middle cerebral artery occlusion (MCAO). H2S donor (NaHS) or inhibitor (aminooxy-acetic acid, AOAA) were microinjected into the hypothalamic paraventricular nucleus (PVN). Compared with the NMCI group, patients in the MCI group showed PSH, including tachycardia, hypertension, and more plasma norepinephrine (NE) that was positively correlated with levels of creatine kinase, glutamate transaminase, and creatinine respectively. The 1-year survival rate of patients with high plasma NE levels was lower. The hypothalamus of rats with MCAO showed increased activity, especially in the PVN region. The levels of H2S in PVN of the rats with MCAO were reduced, while the blood pressure and renal sympathetic discharge were increased, which could be ameliorated by NaHS and exacerbated by AOAA. NaHS completely reduced the disulfide bond of NMDAR1 in PC12 cells. The inhibition of NMDAR by MK-801 microinjected in PVN of rats with MCAO also could lower blood pressure and renal sympathetic discharge. In conclusion, PSH may be associated with disease progression and survival in patients with IS. Decreased levels of H2S in PVN were involved in regulating sympathetic efferent activity after cerebral infarction. Our results might provide a new strategy and target for the prevention and treatment of PSH.

Exercise transiently increases the density of incipient blood clots in antiplatelet-treated lacunar stroke patients

INTRODUCTION

Older individuals and, in particular, individuals at risk of recurrent stroke, may be susceptible to thrombosis when participating in exercise, however, this aspect has not been well investigated.

METHODS

Clot microstructure and conventional markers of thrombotic risk were determined in twenty lacunar stroke patients and fifteen healthy age-matched controls before, immediately after and 1 h after a bout of moderate intensity cycling exercise. Data were analyzed using a linear mixed model approach.

RESULTS

At rest, clot microstructure (1.69 ± 0.07 vs. 1.64 ± 0.05, corresponding to a difference of ~ 50% in normalized clot mass; p = 0.009) and thrombocyte count (73%; p < 0.0001) were higher, and activated partial thromboplastin time was lower (18%; p = 0.0001) in stroke patients compared to age-matched controls. Acute exercise increased thrombogenic markers similarly in the two groups: incipient clot microstructure (1.69 ± 0.07 vs. 1.74 ± 0.05; p = 0.0004 and 1.64 ± 0.05 vs. 1.71 ± 0.04; p < 0.0001, for stroke and controls respectively), plasma fibrinogen (12%; p < 0.0001 and 18%; p < 0.0001, for stroke and controls respectively) and the combined coagulation factors II, VII and X (p = 0.0001 and p < 0.0001, for stroke and controls respectively).

CONCLUSION

The results show that exercise transiently increases the risk of blood clot formation in both stroke patients and controls, however, due to the higher baseline thrombogenicity in stroke patients, the post exercise risk of forming blood clots may be higher in this group.

TRIAL REGISTRATION

Registered at ClinicalTrials.gov (NCT03635177).

Systemic Characterization of the Gut Microbiota Profile after Single Mild Ischemic Stroke and Recurrent Stroke in Mice

It has been estimated that one in four stroke patients may have recurrent stroke within five years after they experienced the first stroke. Furthermore, clinical studies have shown that recurrent stroke negatively affects patient outcomes; the risk of disability and the death rate increase with each recurrent stroke. Therefore, it is urgent to find effective methods to prevent recurrent stroke. The gut microbiota has been proven to play an essential role after ischemic stroke, while sudden ischemia disrupts microbial dysbiosis, and the metabolites secreted by the microbiota also reshape the gut microenvironment. In the present study, we established a recurrent ischemic mouse model. Using this experimental model, we compared the survival rate and ischemic infarction between single MCAO and recurrent MCAO, showing that, when two surgeries were performed, the mouse survival rate dramatically decreased, while the infarction size increased. Fecal samples were collected on day 1, day 3 and day 7 after the first MCAO and day 9 (2 days after the second MCAO) for 16S sequencing, which provided a relatively comprehensive picture of the microbiota changes. By further analyzing the potential metabolic pathways, our data also highlighted several important pathways that were significantly altered after the first and recurrent stroke. In the present study, using an experimental mouse model, we showed that acute ischemic stroke, especially recurrent ischemia, significantly decreased the diversity of the gut microbiota.

Predictive value of the systemic immune inflammation (SII) index for stroke-associated pneumonia

OBJECTIVE

To investigate the predictive value of the systemic immune inflammation (SII) index on the occurrence of stroke-associated pneumonia (SAP) in patients with acute stroke.

METHODS

Data of patients with or without a previous history of pulmonary who visited the First Affiliated Hospital of Kunming Medical University within 24 h of the onset of stroke were collected between January 2017 and December 2019. Patient's demographic data, stroke type, past medical history, National Institutes of Health Stroke Scale score, Glasgow Coma score, and laboratory tests were collected. Logistic regression models and receiver-operating characteristic (ROC) curves were used to investigate the predictive value of SII for the development of SAP in patients with stroke.

RESULTS

We included 395 patients with acute stroke, with a mean age of 63.89 ± 13.42 years, of whom 340 (86.1%) had ischemic stroke, and 55 (13.9%) had hemorrhagic stroke. Out of 395, 113 (28.6%) had SAP and 282 (71.4%) did not, and the SII level in the SAP group was higher than that of the non-SAP group (p < .05). Logistic regression analysis of patients with stroke showed that higher SII was a risk factor for SAP in patients with stroke (per 100 units, HR = 1.081, 95% CI: 1.035-1.130, p < .001), and tertile grouping of SII showed that the risk of SAP was 5.059 times higher in the SIIQ3 group than in the SIIQ1 group (95% CI: 2.061-12.418, p < .001). ROC curve analysis indicated that the SII index had predictive value for the occurrence of SAP in patients with stroke, with an area under the curve of 0.752 (95% CI: 0.698-0.806). When the cutoff value was 861.01, the SII predicted SAP in patients with stroke with a sensitivity of 61.9% and a specificity of 76.2%.

CONCLUSION

Higher SII is an independent risk factor for the development of SAP in patients with stroke and has some predictive value for the development of SAP.

Optimization of Nutrition after Brain Injury: Mechanistic and Therapeutic Considerations

Emerging science continues to establish the detrimental effects of malnutrition in acute neurological diseases such as traumatic brain injury, stroke, status epilepticus and anoxic brain injury. The primary pathological pathways responsible for secondary brain injury include neuroinflammation, catabolism, immune suppression and metabolic failure, and these are exacerbated by malnutrition. Given this, there is growing interest in novel nutritional interventions to promote neurological recovery after acute brain injury. In this review, we will describe how malnutrition impacts the biomolecular mechanisms of secondary brain injury in acute neurological disorders, and how nutritional status can be optimized in both pediatric and adult populations. We will further highlight emerging therapeutic approaches, including specialized diets that aim to resolve neuroinflammation, immunodeficiency and metabolic crisis, by providing pre-clinical and clinical evidence that their use promotes neurologic recovery. Using nutrition as a targeted treatment is appealing for several reasons that will be discussed. Given the high mortality and both short- and long-term morbidity associated with acute brain injuries, novel translational and clinical approaches are needed.

Biochemical Assessment of Pheochromocytoma and Paraganglioma

Pheochromocytoma and paraganglioma (PPGL) require prompt consideration and efficient diagnosis and treatment to minimize associated morbidity and mortality. Once considered, appropriate biochemical testing is key to diagnosis. Advances in understanding catecholamine metabolism have clarified why measurements of the O-methylated catecholamine metabolites rather than the catecholamines themselves are important for effective diagnosis. These metabolites, normetanephrine and metanephrine, produced respectively from norepinephrine and epinephrine, can be measured in plasma or urine, with choice according to available methods or presentation of patients. For patients with signs and symptoms of catecholamine excess, either test will invariably establish the diagnosis, whereas the plasma test provides higher sensitivity than urinary metanephrines for patients screened due to an incidentaloma or genetic predisposition, particularly for small tumors or in patients with an asymptomatic presentation. Additional measurements of plasma methoxytyramine can be important for some tumors, such as paragangliomas, and for surveillance of patients at risk of metastatic disease. Avoidance of false-positive test results is best achieved by plasma measurements with appropriate reference intervals and preanalytical precautions, including sampling blood in the fully supine position. Follow-up of positive results, including optimization of preanalytics for repeat tests or whether to proceed directly to anatomic imaging or confirmatory clonidine tests, depends on the test results, which can also suggest likely size, adrenal vs extra-adrenal location, underlying biology, or even metastatic involvement of a suspected tumor. Modern biochemical testing now makes diagnosis of PPGL relatively simple. Integration of artificial intelligence into the process should make it possible to fine-tune these advances.

Systemic innate myeloid responses to acute ischaemic and haemorrhagic stroke

Acute ischaemic and haemorrhagic stroke account for significant disability and morbidity burdens worldwide. The myeloid arm of the peripheral innate immune system is critical in the immunological response to acute ischaemic and haemorrhagic stroke. Neutrophils, monocytes, and dendritic cells (DC) contribute to the evolution of pathogenic local and systemic inflammation, whilst maintaining a critical role in ongoing immunity protecting against secondary infections. This review aims to summarise the key alterations to myeloid immunity in acute ischaemic stroke, intracerebral haemorrhage (ICH), and subarachnoid haemorrhage (SAH). By integrating clinical and preclinical research, we discover how myeloid immunity is affected across multiple organ systems including the brain, blood, bone marrow, spleen, and lung, and evaluate how these perturbations associate with real-world outcomes including infection. These findings are placed in the context of the rapidly developing field of human immunology, which offers a wealth of opportunity for further research.

The central role of peripheral inflammation in ischemic stroke

Stroke pathology and its treatments conventionally focus on the brain. Probing inflammation, a critical secondary cell death mechanism in stroke, has been largely relegated to the brain. To this end, peripheral inflammation has emerged as an equally potent contributor to the onset and progression of stroke secondary cell death. Here, we review novel concepts on peripheral organs displaying robust inflammatory response to stroke. These inflammation-plagued organs include the spleen, cervical lymph nodes, thymus, bone marrow, gastrointestinal system, and adrenal glands, likely converging their inflammatory effects through B and T-cells. Recognizing the significant impact of this systemic inflammation, we also discuss innovative stroke therapeutics directed at sequestration of peripheral inflammation. This review paper challenges the paradigm of a brain-centered disease pathology and treatment and offers a peripheral approach to our stroke understanding.

Predictors of parenchymal hemorrhage after endovascular treatment in acute ischemic stroke: data from ANGEL-ACT Registry

BACKGROUND

Parenchymal hemorrhage (PH) is a troublesome complication after endovascular treatment (EVT).

OBJECTIVE

To investigate the incidence, independent predictors, and clinical impact of PH after EVT in patients with acute ischemic stroke (AIS) due to anterior circulation large vessel occlusion (LVO).

METHODS

Subjects were selected from the ANGEL-ACT Registry. PH was diagnosed according to the European Collaborative Acute Stroke Study classification. Logistic regression analyses were performed to determine the independent predictors of PH, as well as the association between PH and 90-day functional outcome assessed by modified Rankin Scale (mRS) score.

RESULTS

Of the 1227 enrolled patients, 147 (12.0%) were diagnosed with PH within 12-36 hours after EVT. On multivariable analysis, low admission Alberta Stroke Program Early CT score (ASPECTS)(adjusted OR (aOR)=1.13, 95% CI 1.02 to 1.26, p=0.020), serum glucose >7 mmol/L (aOR=1.82, 95% CI 1.16 to 2.84, p=0.009), and neutrophil-to-lymphocyte ratio (NLR; aOR=1.05, 95% CI 1.02 to 1.09, p=0.005) were associated with a high risk of PH, while underlying intracranial atherosclerotic stenosis (ICAS; aOR=0.42, 95% CI 0.22 to 0.81, p=0.009) and intracranial angioplasty/stenting (aOR=0.37, 95% CI 0.15 to 0.93, p=0.035) were associated with a low risk of PH. Furthermore, patients with PH were associated with a shift towards to worse functional outcome (mRS score 4 vs 3, adjusted common OR (acOR)=2.27, 95% CI 1.53 to 3.38, p<0.001).

CONCLUSIONS

In Chinese patients with AIS caused by anterior circulation LVO, the risk of PH was positively associated with low admission ASPECTS, serum glucose >7 mmol/L, and NLR, but negatively related to underlying ICAS and intracranial angioplasty/stenting.

TRIAL REGISTRATION NUMBER

NCT03370939.

Research progress on the role of hormones in ischemic stroke

Ischemic stroke is a major cause of death and disability around the world. However, ischemic stroke treatment is currently limited, with a narrow therapeutic window and unsatisfactory post-treatment outcomes. Therefore, it is critical to investigate the pathophysiological mechanisms following ischemic stroke brain injury. Changes in the immunometabolism and endocrine system after ischemic stroke are important in understanding the pathophysiological mechanisms of cerebral ischemic injury. Hormones are biologically active substances produced by endocrine glands or endocrine cells that play an important role in the organism's growth, development, metabolism, reproduction, and aging. Hormone research in ischemic stroke has made very promising progress. Hormone levels fluctuate during an ischemic stroke. Hormones regulate neuronal plasticity, promote neurotrophic factor formation, reduce cell death, apoptosis, inflammation, excitotoxicity, oxidative and nitrative stress, and brain edema in ischemic stroke. In recent years, many studies have been done on the role of thyroid hormone, growth hormone, testosterone, prolactin, oxytocin, glucocorticoid, parathyroid hormone, and dopamine in ischemic stroke, but comprehensive reviews are scarce. This review focuses on the role of hormones in the pathophysiology of ischemic stroke and discusses the mechanisms involved, intending to provide a reference value for ischemic stroke treatment and prevention.

Analysis of Hospitalization Costs in Patients Suffering from Cerebral Infarction along with Varied Comorbidities

OBJECTIVE

This study aimed to study the influence of comorbidities on hospitalization costs for inpatients with cerebral infarction.

METHODS

The data from the medical records pertaining to 76,563 inpatients diagnosed with cerebral infarction were collected from public hospital records for the period between 1 January 2020 and 30 December 2020 in Gansu Province. EpiData 3.1 software was used for data collation, and SPSS 25.0 was used for data analysis. Numbers and percentages were calculated for categorical variables, the chi-squared test was used to compare differences between groups, and multiple independent-sample tests (Kruskal-Wallis H test, test level α = 0.05) and multiple linear regression were used to analyze the influence of different types of comorbidity on hospitalization costs.

RESULTS

Among the 76,563 cerebral infarction inpatients, 41,400 were male (54.07%); the average age of the inpatients was 67.68 ± 10.75 years (the 60~80-year-old group accounted for 65.69%). Regarding the incidence of varied chronic disease comorbidities concomitant with cerebral infarction, hypertension was reported as the most frequent, followed by heart disease and chronic pulmonary disease. The average hospitalization cost of cerebral infarction inpatients is US $1219.66; the hospitalization cost increases according to the number of comorbidities with which a patient suffers (H = 404.506, p < 0.001); Regarding the types of comorbidities, the hospitalization cost of cancer was the highest, at US $1934.02, followed by chronic pulmonary disease (US $1533.02). Regarding the cost of hospitalization for combinations of comorbidities, cerebral infarction + chronic pulmonary disease was the most costly (US $1718.90), followed by cerebral infarction + hypertension + chronic pulmonary disease (US $1530.60). In the results of multiple linear regression analysis, cerebral infarction with chronic pulmonary disease had significant effects on hospitalization costs (β = 0.181, p < 0.001), drug costs (β = 0.144, p < 0.001) and diagnosis costs (β = 0.171, p < 0.001).

CONCLUSIONS

Comorbidities are significantly associated with high hospitalization costs for cerebral infarction patients. Furthermore, relevant health departments should build preventative and control systems to reduce the risk of comorbidities, as well as to improve hospital clinical pathway management and to strengthen and refine the cost-control management of cerebral infarction from the perspective of comorbidities.

A new marker of short-term mortality and poor outcome in patients with acute ischemic stroke: Mean platelet volume-to-lymphocyte ratio

BACKGROUND

The mean platelet volume-to-lymphocyte ratio (MPVLR), as a novel marker of thrombosis and inflammation, has been demonstrated to be closely linked to poor cardiovascular disease prognosis. However, the correlation between MPVLR and acute ischemic stroke (AIS) remains unclear. This study, therefore, aimed to clarify the relationship between MPVLR and the short-term prognosis of AIS.

METHODS

A total of 315 patients with first-time AIS diagnoses were recruited and divided into 3 groups based on the tri-sectional quantiles for MPVLR on admission: group 1 (N = 105) with a MPVLR ≤ 4.93, group 2 (N = 105) with a MPVLR of 4.94 to 7.21, and group 3 (N = 105) with a MPVLR ≥ 7.22. All patients were followed-up for 3 months, and death within 3 months was defined as the endpoint. Baseline characteristics, stroke severity, and functional outcomes were evaluated.

RESULTS

The Spearman's correlation coefficient test showed that MPVLR was significantly positively correlated with the National Institutes of Health Stroke Scale score (R = 0.517, P < .001). Multivariate analysis revealed that MPVLR was an independent predictor of both short-term mortality (adjusted odds ratio [OR] 1.435, P < .001) and poor outcome (adjusted OR 1.589, P < .001). The receiver operating characteristic (ROC) curve analysis showed that the best cutoff value of MPVLR for short-term mortality and poor outcome were 6.69 (sensitivity: 86.4%, specificity: 68.6%) and 6.38 (sensitivity: 78.8%, specificity: 72.3%), respectively.

CONCLUSIONS

MPVLR on admission was positively associated with stroke severity. An elevated MPVLR is an independent predictor of short-term mortality and poor outcome after AIS.

Stroke-induced changes to immune function and their relevance to increased risk of severe COVID-19 disease

As the COVID-19 pandemic moves towards endemic disease, it remains of key importance to identify groups of individuals vulnerable to severe infection and understand the biological factors that mediate this risk. Stroke patients are at increased risk of developing severe COVID-19, likely due to stroke-induced alterations to systemic immune function. Furthermore, immune responses associated with severe COVID-19 in patients without a history of stroke parallel many of the immune alterations induced by stroke, possibly resulting in a compounding effect that contributes to worsened disease severity. In this review, we discuss the changes to systemic immune function that likely contribute to augmented COVID-19 severity in patients with a history of stroke and the effects of COVID-19 on the immune system that may exacerbate these effects.

Pneumonia in Nervous System Injuries: An Analytic Review of Literature and Recommendations

Pneumonia is one of the most common complications in intensive care units and is the most common nosocomial infection in this setting. Patients with neurocritical conditions who are admitted to ICUs are no exception, and in fact, are more prone to infections such as pneumonia because of factors such as swallow dysfunction, need for mechanical ventilation, longer length of stay in hospitals, etc. Common central nervous system pathologies such as ischemic stroke, traumatic brain injury, subarachnoid hemorrhage, intracerebral hemorrhage, neuromuscular disorders, status epilepticus, and demyelinating diseases can cause long in-hospital admissions and increase the risk of pneumonia each with a mechanism of its own. Brain injury-induced immunosuppression syndrome is usually considered the common mechanism through which patients with critical central nervous system conditions become susceptible to different kinds of infection including pneumonia. Evaluating the patients and assessment of the risk factors can lead our attention toward better infection control in this population and therefore decrease the risk of infections in central nervous system injuries.

Are beta blockers effective in preventing stroke associated infections? - a systematic review and meta-analysis

BACKGROUND

Excessive sympathoexcitation could lead to stroke associated infection. Inhibiting sympathetic excitation may reduce the infection risk after stroke. Thus, the present study aimed to determine the protective effect of beta blockers on stroke associated infection through systematic review and meta-analysis.

METHODS

A systematic search of multiple databases were performed up to February 2022. The included studies required beta blockers therapy in stroke patients and assessed the incidence of stroke-associated infections. Outcomes of interest included infections, pneumonia, urinary tract infection and sepsis. Random-effects model was used for analysis. Heterogeneity was evaluated using I2 statistics and publication bias was evaluated by the funnel plot.

RESULT

A total of 83 potentially relevant publications was identified in the initial search. Six studies met the inclusion criteria for meta-analysis. The risk of bias in the included articles satisfies the quality requirement of meta-analysis. No significant associations between beta blockers therapy and the prevention of stroke associated infection, stroke associated pneumonia and septicemia were found, However, subgroup analyses revealed an association between beta blockers treatment and the increased risk of post-stroke urinary tract infection or stroke associated pneumonia in some stroke patients (OR = 1.69 [1.33, 2.14], P < 0.0001; OR = 1.85 [1.51, 2.26], P < 0.0001).

CONCLUSION

Due to the lack of robust evidence, this meta-analysis may not support the preventive effect of beta blockers on stroke associated infection. But beta blockers treatment may be associated with development of post-stroke urinary tract infection and stroke associated pneumonia in some stroke patients.

Immunodepression, Infections, and Functional Outcome in Ischemic Stroke

Stroke remains one of the main causes of mortality and morbidity worldwide. Immediately after stroke, a neuroinflammatory process starts in the brain, triggering a systemic immunodepression mainly through excessive activation of the autonomous nervous system. Manifestations of immunodepression include lymphopenia but also dysfunctional innate and adaptive immune cells. The resulting impaired antibacterial defenses render patients with stroke susceptible to infections. In addition, other risk factors like stroke severity, dysphagia, impaired consciousness, mechanical ventilation, catheterization, and older age predispose stroke patients for infections. Most common infections are pneumonia and urinary tract infection, both occur in ≈10% of the patients. Especially pneumonia increases unfavorable outcome and mortality in patients with stroke; systemic effects like hypotension, fever, delay in rehabilitation are thought to play a crucial role. Experimental and clinical data suggest that systemic infections enhance autoreactive immune responses against brain antigens and thus negatively affect outcome but convincing evidence is lacking. Prevention of poststroke infections by preventive antibiotic therapy did not improve functional outcome after stroke. Immunomodulatory approaches counteracting immunodepression to prevent stroke-associated pneumonia need to account for neuroinflammation in the ischemic brain and avoid further tissue damage. Experimental studies discovered interesting targets, but these have not yet been investigated in patients with stroke. A better understanding of the pathobiology may help to develop optimized approaches of preventive antibiotic therapy or immunomodulation to effectively prevent stroke-associated pneumonia while improving long-term outcome after stroke. In this review, we aim to characterize epidemiology, risk factors, cause, diagnosis, clinical presentation, and potential treatment of poststroke immunosuppression and associated infections.

Brain to periphery in acute ischemic stroke: Mechanisms and clinical significance

The social and public health burdens of ischemic stroke have been increasing worldwide. In addition to focal brain damage, acute ischemic stroke (AIS) provokes systemic abnormalities across peripheral organs. AIS profoundly alters the autonomic nervous system, hypothalamic-pituitary-adrenal axis, and immune system, which further yield deleterious organ-specific consequences. Poststroke systemic pathological alterations in turn considerably contribute to the progression of ischemic brain injury, which accounts for the substantial impact of systemic complications on stroke outcomes. This review provides a comprehensive and updated pathophysiological model elucidating the systemic effects of AIS. To address their clinical significance and inform stroke management, we also outline the resulting systemic complications at particular stages of AIS and highlight the mechanisms. Future therapeutic strategies should attempt to integrate the treatment of primary brain lesions with interventions for secondary systemic complications, and should be tailored to patient individualized characteristics to optimize stroke outcomes.

Molecular Mechanisms of Neuroimmune Crosstalk in the Pathogenesis of Stroke

Stroke disrupts the homeostatic balance within the brain and is associated with a significant accumulation of necrotic cellular debris, fluid, and peripheral immune cells in the central nervous system (CNS). Additionally, cells, antigens, and other factors exit the brain into the periphery via damaged blood–brain barrier cells, glymphatic transport mechanisms, and lymphatic vessels, which dramatically influence the systemic immune response and lead to complex neuroimmune communication. As a result, the immunological response after stroke is a highly dynamic event that involves communication between multiple organ systems and cell types, with significant consequences on not only the initial stroke tissue injury but long-term recovery in the CNS. In this review, we discuss the complex immunological and physiological interactions that occur after stroke with a focus on how the peripheral immune system and CNS communicate to regulate post-stroke brain homeostasis. First, we discuss the post-stroke immune cascade across different contexts as well as homeostatic regulation within the brain. Then, we focus on the lymphatic vessels surrounding the brain and their ability to coordinate both immune response and fluid homeostasis within the brain after stroke. Finally, we discuss how therapeutic manipulation of peripheral systems may provide new mechanisms to treat stroke injury.

Effect of Beta-Blockers on Stroke Outcome: A Meta-Analysis

Introduction

Cardiovascular events and infections are common in the acute phase after stroke. It has been suggested that these complications may be associated with excessive sympathetic activation due to the stroke, and that beta-adrenergic antagonists (beta-blockers) therefore may be beneficial.

Aim

The aim of the current meta-analysis was to investigate the association between beta-blocker treatment in acute stroke and the three outcomes: mortality, functional outcome and post-stroke infections.

Methods

A literature search was performed using the keywords stroke, cerebrovascular disorders, adrenergic beta-antagonists, treatment outcome and mortality. Randomized clinical trials and observational studies were eligible for data extraction. Heterogeneity was investigated using I² statistics. Random effect model was used when heterogeneity presented among studies; otherwise, a fixed-effect model was used. Publication bias was assessed using Egger’s test and by visually inspecting funnel plots.

Results

A total of 20 studies were eligible for at least one of the three outcomes. Two of the included studies were randomized controlled trials and 18 were observational studies. Quality assessments indicated that the risk of bias was moderate. The meta-analysis found no significant association between treatment with beta-blockers and any of the three outcomes. The studies analyzed for the outcomes mortality and infection were heterogeneous, while studies analyzed for functional outcome were homogeneous. The articles analyzed for mortality showed signs of publication bias.

Conclusion

The lack of significant effects in the current meta-analysis, comprising more than 100,000 patients, does not support the proposed beneficial effects of beta-blockers in the acute phase of stroke.

A hyperacute immune map of ischaemic stroke patients reveals alterations to circulating innate and adaptive cells

Systemic immune changes following ischaemic stroke are associated with increased susceptibility to infection and poor patient outcome due to their role in exacerbating the ischaemic injury and long-term disability. Alterations to the abundance or function of almost all components of the immune system post-stroke have been identified, including lymphocytes, monocytes and granulocytes. However, subsequent infections have often confounded the identification of stroke-specific effects. Global understanding of very early changes to systemic immunity is critical to identify immune targets to improve clinical outcome. To this end, we performed a small, prospective, observational study in stroke patients with immunophenotyping at a hyperacute time point (< 3 h) to explore early changes to circulating immune cells. We report, for the first time, decreased frequencies of type 1 conventional dendritic cells (cDC1), haematopoietic stem and progenitor cells (HSPCs), unswitched memory B cells and terminally differentiated effector memory T cells re-expressing CD45RA (TEMRA). We also observed concomitant alterations to human leucocyte antigen D-related (HLA-DR), CD64 and CD14 expression in distinct myeloid subsets and a rapid activation of CD4+ T cells based on CD69 expression. The CD69+ CD4+ T cell phenotype inversely correlated with stroke severity and was associated with naive and central memory T (TCM) cells. Our findings highlight early changes in both the innate and adaptive immune compartments for further investigation as they could have implications the development of post-stroke infection and poorer patient outcomes.

Targeting the Autonomic Nervous System for Risk Stratification, Outcome Prediction and Neuromodulation in Ischemic Stroke

Ischemic stroke is a worldwide major cause of mortality and disability and has high costs in terms of health-related quality of life and expectancy as well as of social healthcare resources. In recent years, starting from the bidirectional relationship between autonomic nervous system (ANS) dysfunction and acute ischemic stroke (AIS), researchers have identified prognostic factors for risk stratification, prognosis of mid-term outcomes and response to recanalization therapy. In particular, the evaluation of the ANS function through the analysis of heart rate variability (HRV) appears to be a promising non-invasive and reliable tool for the management of patients with AIS. Furthermore, preclinical molecular studies on the pathophysiological mechanisms underlying the onset and progression of stroke damage have shown an extensive overlap with the activity of the vagus nerve. Evidence from the application of vagus nerve stimulation (VNS) on animal models of AIS and on patients with chronic ischemic stroke has highlighted the surprising therapeutic possibilities of neuromodulation. Preclinical molecular studies highlighted that the neuroprotective action of VNS results from anti-inflammatory, antioxidant and antiapoptotic mechanisms mediated by α7 nicotinic acetylcholine receptor. Given the proven safety of non-invasive VNS in the subacute phase, the ease of its use and its possible beneficial effect in hemorrhagic stroke as well, human studies with transcutaneous VNS should be less challenging than protocols that involve invasive VNS and could be the proof of concept that neuromodulation represents the very first therapeutic approach in the ultra-early management of stroke.

Blood Biomarkers to Predict Long-Term Mortality after Ischemic Stroke

Stroke is a major cause of disability and death globally, and prediction of mortality represents a crucial challenge. We aimed to identify blood biomarkers measured during acute ischemic stroke that could predict long-term mortality. Nine hundred and forty-one ischemic stroke patients were prospectively recruited in the Stroke-Chip study. Post-stroke mortality was evaluated during a median 4.8-year follow-up. A 14-biomarker panel was analyzed by immunoassays in blood samples obtained at hospital admission. Biomarkers were normalized and standardized using Z-scores. Multiple Cox regression models were used to identify clinical variables and biomarkers independently associated with long-term mortality and mortality due to stroke. In the multivariate analysis, the independent predictors of long-term mortality were age, female sex, hypertension, glycemia, and baseline National Institutes of Health Stroke Scale (NIHSS) score. Independent blood biomarkers predictive of long-term mortality were endostatin > quartile 2, tumor necrosis factor receptor-1 (TNF-R1) > quartile 2, and interleukin (IL)-6 > quartile 2. The risk of mortality when these three biomarkers were combined increased up to 69%. The addition of the biomarkers to clinical predictors improved the discrimination (integrative discriminative improvement (IDI) 0.022 (0.007–0.048), p < 0.001). Moreover, endostatin > quartile 3 was an independent predictor of mortality due to stroke. Altogether, endostatin, TNF-R1, and IL-6 circulating levels may aid in long-term mortality prediction after stroke.

Is cerebral salt wasting related to sympathetic dysregulation in tuberculous meningitis?

BACKGROUND

Cerebral Salt wasting (CSW) is common in Tuberculous Meningitis (TBM) and is suggested to be due to sympathetic dysregulation of renal blood supply but has not been proven.

OBJECTIVE

To evaluate plasma Catecholamines in TBM patients with CSW and correlate with the markers of stress.

MATERIALS AND METHODS

The diagnosis of TBM was based on clinical, CSF and MRI criteria. Catecholamines level was measured by LC-MS on admission, at the time of hyponatremia and on correction of hyponatremia. Catecholamine levels were correlated with clinical and laboratory markers of stress, hyponatremia and severity of CSW using pre-defined criteria.

RESULTS

There were 24 patients with TBM (12 with CSW) and 12 controls. The median age of patients was 31 (18-75) years and 12 (50 %) were females. TBM patients with CSW had significantly higher levels of catecholamines compared to controls (p < 0.001). TBM patients with CSW had higher levels of norepinephrine than those without CSW (p = 0.034). Sequential studies revealed that dopamine and epinephrine increased at the time of hyponatremia and declined on its correction. Severity of TBM was related to dopamine (p = 0.04) and severity of CSW was related to epinephrine (p = 0.016).

CONCLUSION

CSW in TBM seems to be related to catecholamine dysregulation.

Inflammatory Factors as Potential Markers of Early Neurological Deterioration in Acute Ischemic Stroke Patients Receiving Endovascular Therapy - The AISRNA Study

BACKGROUND AND PURPOSE

This study aimed to explore several peripheral blood-based markers related to the inflammatory response in a total of 210 patients with acute ischemic stroke (AIS) caused by large artery occlusion in the anterior circulation who received endovascular therapy (EVT) from an observational study of clinical significance of circulating non-coding RNA in acute ischemic stroke (AISRNA).

METHODS

We collected baseline characteristics of 210 AIS patients participating in an observational acute stroke cohort: the AISRNA study. The following inflammatory factors were measured in these participants: interleukin-2 [IL-2], IL-4, IL-6, IL-10, tumor necrosis factor-α [TNF-α], and interferon-γ [IFN-γ]. The National Institute of Health Stroke Scale score increase of ≥4 within 24 hours after EVT defined as early neurological deterioration (END).

RESULTS

Compared with patients without END, patients with END had a higher incidence of atrial fibrillation (P=0.012), and also had higher levels of IL-6 and IL-10 (P<0.01). Furthermore, we found that the area under the curves (AUCs) of IL-6 and IL-10 for predicting END were 0.768 (0.697-0.829), and 0.647 (0.570-0.719), respectively. Adjusting for age, sex, and atrial fibrillation, the odds ratios (ORs; 95% confidence interval) for incident END for IL-6 and IL-10 were 1.98 (1.05-6.69) and 1.18 (1.04-1.33), respectively. Additionally, we found significant changes over time in the expression levels of IL-4, IL-6, and IL-10 in patients with END compared with patients without END (P<0.05).

CONCLUSION

IL-6 and IL-10 levels at admission may be potential markers of END after EVT, and the time course of IL-4, IL-6, and IL-10 is correlated with stroke progression. Further larger studies are needed to confirm the current findings.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04175691. Registered November 21, 2019, https://www.clinicaltrials.gov/ct2/show/NCT04175691.

Blood Pressure Management in Acute Ischemic Stroke

PURPOSE OF REVIEW

Abrupt blood pressure (BP) rise is the most common clinical symptom of acute ischemic stroke (AIS). However, BP alterations during AIS reflect many diverse mechanisms, both stroke-related and nonspecific epiphenomena, which change over time and across patients. While extremes of BP as well as high BP variability have been related with worse outcomes in observational studies, optimal BP management after AIS remains challenging.

RECENT FINDINGS

This review discusses the complexity of the factors linking BP changes to the clinical outcomes of patients with AIS, depending on the treatment strategy and local vessel status and, in particular, the degree of reperfusion achieved. The evidence for possible additional clinical markers, including the presence of arterial hypertension, and comorbid organ dysfunction in individuals with AIS, as informative and helpful factors in therapeutic decision-making concerning BP will be reviewed, as well as recent data on neurovascular monitoring targeting person-specific local cerebral perfusion and metabolic demand, instead of the global traditional parameters (BP among others) alone. The individualization of BP management protocols based on a complex evaluation of the homeostatic response to focal cerebral ischemia, including but not limited to BP changes, may be a valuable novel goal proposed in AIS, but further trials are warranted.

Cerebral hemodynamics in stroke thrombolysis (CHiST) study

Despite careful patient selection, successful recanalization in intravenous thrombolysis is only achieved in approximately 50% of cases. Understanding changes in cerebral autoregulation during and following successful recanalization in acute ischemic stroke patients who receive intravenous thrombolysis, may inform the management of common physiological perturbations, including blood pressure, in turn reducing the risk of reperfusion injury. Cerebral blood velocity (Transcranial Doppler), blood pressure (Finometer) and end-tidal carbon dioxide (capnography) were continuously recorded in 11 acute ischemic stroke patients who received intravenous thrombolysis (5 female, mean ± SD age 68±12 years) over 4-time points, during and at the following time intervals after intravenous thrombolysis: 23.9±2.6 hrs, 18.1±7.0 days and 89.6±4.2 days. Reductions in blood pressure (p = 0.04) were observed during intravenous thrombolysis. Reductions in heart rate (p<0.005) and critical closing pressure [Affected hemisphere (p = 0.02) and non-affected hemisphere (p<0.005)] were observed post intravenous thrombolysis. End-tidal CO2 increased during the sub-acute and chronic stages (p = 0.028). Reduction in affected hemisphere phase at low frequency was observed during intravenous thrombolysis (p = 0.021) and at subsequent visits (p = 0.048). No changes were observed in cerebral blood velocity, coherence, gain and Autoregulation Index during the follow-up period. Intravenous thrombolysis in acute ischemic stroke patients induced changes in affected hemisphere phase and other key hemodynamic parameters, but not Autoregulation Index. Further investigation of cerebral autoregulation is warranted in a larger acute ischemic stroke cohort to inform its potential role in individualized management plans.

Predictors of urinary tract infection in acute stroke patients: A cohort study

Patients with stroke have a high risk of infection which may be predicted by age, procalcitonin, interleukin-6, C-reactive protein, National Institute of Health stroke scale (NHSS) score, diabetes, etc. These prediction methods can reduce unfavourable outcome by preventing the occurrence of infection.We aim to identify early predictors for urinary tract infection in patients after stroke.In 186 collected acute stroke patients, we divided them into urinary tract infection group, other infection type groups, and non-infected group. Data were recorded at admission. Independent risk factors and infection prediction model were determined using Logistic regression analyses. Likelihood ratio test was used to detect the prediction effect of the model. Receiver operating characteristic curve and the corresponding area under the curve were used to measure the predictive accuracy of indicators for urinary tract infection.Of the 186 subjects, there were 35 cases of urinary tract infection. Elevated interleukin-6, higher NIHSS, and decreased hemoglobin may be used to predict urinary tract infection. And the predictive model for urinary tract infection (including sex, NIHSS, interleukin-6, and hemoglobin) have the best predictive effect.This study is the first to discover that decreased hemoglobin at admission may predict urinary tract infection. The prediction model shows the best accuracy.

The Local and Peripheral Immune Responses to Stroke: Implications for Therapeutic Development

The immune response to stroke is an exciting target for future stroke therapies. Stroke is a leading cause of morbidity and mortality worldwide, and clot removal (mechanical or pharmacological) to achieve tissue reperfusion is the only therapy currently approved for patient use. Due to a short therapeutic window and incomplete effectiveness, however, many patients are left with infarcted tissue that stimulates inflammation. Although this is critical to promote repair, it can also damage surrounding healthy brain tissue. In addition, acute immunodepression and subsequent infections are common and are associated with worse patient outcomes. Thus, the acute immune response is a major focus of researchers attempting to identify ways to amplify its benefits and suppress its negative effects to improve short-term recovery of patients. Here we review what is known about this powerful process. This includes the role of brain resident cells such as microglia, peripherally activated cells such as macrophages and neutrophils, and activated endothelium. The role of systemic immune activation and subsequent immunodepression in the days after stroke is also discussed, as is the chronic immune responses and its effects on cognitive function. The biphasic role of inflammation, as well as complex timelines of cell production, differentiation, and trafficking, suggests that the relationship between the acute and chronic phases of stroke recovery is complex. Gaining a more complete understanding of this intricate process by which inflammation is initiated, propagated, and terminated may potentially lead to therapeutics that can treat a larger population of stroke patients than what is currently available. The immune response plays a critical role in patient recovery in both the acute and chronic phases after stroke. In patients, the immune response can be beneficial by promoting repair and recovery, and also detrimental by propagating a pro-inflammatory microenvironment. Thus, it is critical to understand the mechanisms of immune activation following stroke in order to successfully design therapeutics.

Leukocytes, Collateral Circulation, and Reperfusion in Ischemic Stroke Patients Treated With Mechanical Thrombectomy

Background and Purpose—

Peripheral immune cells are activated after stroke and may in turn influence the fate of ischemic brain tissue, thus exerting a dual role in ischemic stroke. We evaluated the contribution of neutrophil and lymphocyte counts to hemorrhagic complications and functional outcome in stroke patients treated with mechanical thrombectomy (MT) with varying degrees of collateral circulation and reperfusion.

Methods—

We retrospectively analyzed 433 consecutive ischemic stroke patients treated with MT. Neutrophil and lymphocyte counts and the neutrophil-to-lymphocyte ratio (NLR) were collected before MT and 1 day after symptom onset. Outcome measures included categories of hemorrhagic transformation, symptomatic intracerebral hemorrhage, 3-month functional dependence (modified Rankin Scale, 3–6), and mortality. Patients were categorized according to their baseline collateral status and the degree of reperfusion after MT.

Results—

Neutrophil counts and NLR increased, whereas lymphocyte counts decreased after MT ( P <0.001), and changes in neutrophils and NLR at day 1 were significantly greater in patients with poor reperfusion. Neutrophil counts and NLR were significantly higher already at admission in patients with poor 3-month outcome. In adjusted analysis, the impact of neutrophilia on poor functional outcome was more substantial in patients with good collaterals achieving successful reperfusion (aOR, 3.09 per quartile; 95% CI, 1.95–4.90), whereas admission lymphopenia (aOR, 4.08 per decreasing quartile; 95% CI, 1.56–10.64) and higher NLR (aOR, 3.76 per quartile; 95% CI, 1.44–9.79) predicted subsequent symptomatic intracerebral hemorrhage in patients with poor collaterals and successful reperfusion.

Conclusions—

In patients treated with MT, neutrophil and lymphocyte counts are dynamic parameters associated with hemorrhagic complications and long-term outcome. The extent of collateral circulation and the success of brain reperfusion influence the strength of these associations and highlight the dual role of leukocytes in acute stroke.

Baroreflex sensitivity is associated with post-stroke infections. An open, prospective study

BACKGROUND AND PURPOSE

Autonomic nervous system (ANS) seems to play an important role in the post-stroke immunosuppression syndrome with increased susceptibility to infections. The aim of this study was to investigate if ANS activity measured at admission is associated with post-stroke infections.

METHODS

We prospectively analyzed patients with acute ischemic stroke. ANS was measured using the cross-correlational baroreflex sensitivity (BRS) at admission. The occurrence and cause of in-hospital infections was assessed based on the clinical and laboratory examination. Demographic and clinical variables including initial stroke severity, dysphagia, procedures as nasogastric tubes, central venous and urinary catheters and mechanical ventilation were included in the analysis.

RESULTS

We included 161 patients with ischemic stroke, of those 49 (30.4%) developed a nosocomial infection during the first 7 days of hospital stay. Patients with infections had significantly lower BRS (median 3 vs 5 ms/mmHg, p < .001) higher initial NIHSS (median 15 vs 5, p < .001), had more often non-lacunar etiology and underwent more invasive procedures. In the multivariable regression model decreased BRS (adjusted OR 1.21, 95% CI 1.03-1.41, p = .02), admission NIHSS (adjusted OR 1.10, 95% CI 1.02-1.19, p = .02) and invasive procedures (adjusted OR 1.46, 95% CI 1.03-2.06, p = .03) were independently associated with infection after ischemic stroke.

CONCLUSIONS

Decreased BRS was independently associated with infections after ischemic stroke. Autonomic shift may play an important role in increased susceptibility to infections after stroke. The possible diagnostic and therapeutic relevance of this finding deserves further research.

The Influence of β-Adrenergic Receptor Kinase-1 on Stroke-induced Immunodeficiency Syndrome

BACKGROUND

Immunodeficiency in acute ischemic stroke (AIS) is thought to be a result of norepinephrine suppression of the lymphoid tissue. The possible differences in the distribution of lymphocytes after stroke may be due to differences in responsiveness of lymphocyte β-adrenergic receptors to their kinase (BARK-1).

OBJECTIVE

The objective was to quantify the influence of lymphocyte BARK-1 on stroke-induced immunodeficiency in AIS patients.

METHODS

A prospective clinical cohort study was conducted (N = 44). Measures included age, gender, race, risk factors for stroke, stroke severity, comorbidities, presence of infection, white blood cell counts and differential proportions, and lymphocyte BARK-1. Student t tests, effect sizes, and linear and logistic regressions were conducted to test the study objective. The study was approved by the Oregon Health & Science University Institutional Review Board.

RESULTS

There were significant changes in all white blood cells and differential proportions and in the National Institutes of Health Stroke Scale from admission to 48 hours after onset of stroke deficits. Higher BARK-1 influenced the lower lymphocyte proportion at 48 hours, independent of age, P < .0001. Furthermore, BARK-1 also was associated with an increase in the likelihood of having sustained or stroke-induced immunodeficiency at 48 hours: odds ratio, 2.41; 95% confidence interval, 1.10-5.25; P = .027, and odds ratio, 2.79; 95% confidence interval, 1.03-7.52; P = .043, respectively. In all backward stepwise selection of factors, BARK-1 was the only factor consistently retained in the models.

CONCLUSIONS

β-Adrenergic receptor kinase-1 has a significant quantifiable influence on lymphocyte proportion at 48 hours and on the classification of sustained stroke-induced immunodeficiency.

CLINICAL IMPLICATIONS

β-Adrenergic stimulation influences immunodeficiency in AIS.

QT interval prolongation in patients with acute ischemic stroke: a report in northwest China

Aims

QT interval prolongation is common in patients with stroke and increases the risk of malignant arrhythmia and sudden death. Our aim was to analyze differences in the QT interval and electrocardiogram abnormalities between acute ischemic stroke patients and controls.

Methods

We retrospectively collected data from 273 patients with acute ischemic stroke from the neurological intensive care unit and 495 controls from other departments. A standard 12-lead electrocardiogram was recorded within 24 hours of hospitalization. Clinical information, the QT interval corrected for heart rate (QTc), and the incidence of electrocardiogram abnormalities were compared between groups.

Results

There was no difference in age, sex, or the prevalence of hypertension or diabetes mellitus between the acute ischemic stroke group and controls. Acute ischemic stroke patients showed a significantly longer QTc and a higher incidence of both sinus bradycardia and ST-T changes compared with controls. We also showed that the changes in electrocardiogram results observed in acute ischemic stroke might be transient.

Conclusion

Acute ischemic stroke patients may have a longer QT interval and a higher incidence of electrocardiogram abnormalities. In clinical practice, careful attention should be paid to acute ischemic stroke patients to prevent malignant arrhythmia.

Interleukin-1 receptor antagonist treatment in acute ischaemic stroke does not alter systemic markers of anti-microbial defence

Background: Blockade of the cytokine interleukin-1 (IL-1) with IL-1 receptor antagonist (IL-1Ra) is a candidate treatment for stroke entering phase II/III trials, which acts by inhibiting harmful inflammatory responses.  Infection is a common complication after stroke that significantly worsens outcome and is related to stroke-induced deficits in systemic immune function thought to be mediated by the sympathetic nervous system.  Therefore, immunomodulatory treatments for stroke, such as IL-1Ra, carry a risk of aggravating stroke-associated infection. Our primary objective was to determine if factors associated with antibody-mediated antibacterial defences were further compromised in patients treated with IL-1Ra after stroke. Methods: We assessed plasma concentrations of immunoglobulin isotypes and complement components in stroke patients treated with IL-1Ra or placebo and untreated non-stroke controls using multiplex protein assays. Activation of the sympathetic nervous system (SNS) was determined by measuring noradrenaline, a major SNS mediator. Results:  There were significantly lower plasma concentrations of IgM, IgA, IgG1 and IgG4 in stroke-patients compared to non-stroke controls, however there were no differences between stroke patients treated with placebo or IL-1Ra. Concentrations of complement components associated with the classical pathway  were increased and those associated with the alternative pathways decreased in stroke patients, neither being affected by treatment with IL-1Ra.  Noradrenaline concentrations were increased after stroke in both placebo and IL-1Ra-treated stroke patients compared to non-stroke controls.  Conclusion: These data show treatment with IL-1Ra after stroke does not alter circulating immunoglobulin and complement concentrations and is therefore unlikely to further aggravate stroke-associated infection susceptibility through altered availability of these key anti-microbial mediators.

Interleukin-1 receptor antagonist treatment in acute ischaemic stroke does not alter systemic markers of anti-microbial defence

Background: Blockade of the cytokine interleukin-1 (IL-1) with IL-1 receptor antagonist (IL-1Ra) is a candidate treatment for stroke entering phase II/III trials, which acts by inhibiting harmful inflammatory responses.  Infection is a common complication after stroke that significantly worsens outcome and is related to stroke-induced deficits in systemic immune function thought to be mediated by the sympathetic nervous system.  Therefore, immunomodulatory treatments for stroke, such as IL-1Ra, carry a risk of aggravating stroke-associated infection. Our primary objective was to determine if factors associated with antibody-mediated antibacterial defences were further compromised in patients treated with IL-1Ra after stroke. Methods: We assessed plasma concentrations of immunoglobulin isotypes and complement components in stroke patients treated with IL-1Ra or placebo and untreated non-stroke controls using multiplex protein assays. Activation of the sympathetic nervous system (SNS) was determined by measuring noradrenaline, a major SNS mediator. Results:  There were significantly lower plasma concentrations of IgM, IgA, IgG1 and IgG4 in stroke-patients compared to non-stroke controls, however there were no differences between stroke patients treated with placebo or IL-1Ra. Concentrations of complement components associated with the classical pathway  were increased and those associated with the alternative pathways decreased in stroke patients, neither being affected by treatment with IL-1Ra.  Noradrenaline concentrations were increased after stroke in both placebo and IL-1Ra-treated stroke patients compared to non-stroke controls.  Conclusion: These data show treatment with IL-1Ra after stroke does not alter circulating immunoglobulin and complement concentrations and is therefore unlikely to further aggravate stroke-associated infection susceptibility through reduced availability of these key anti-microbial mediators.

Old Dog New Tricks; Revisiting How Stroke Modulates the Systemic Immune Landscape

Infections in the post-acute phase of cerebral ischaemia impede optimal recovery by exacerbating morbidity and mortality. Our review aims to reconcile the increased infection susceptibility of patients post-stroke by consolidating our understanding of compartmentalised alterations to systemic immunity. Mounting evidence has catalogued alterations to numerous immune cell populations but an understanding of the mechanisms of long-range communication between the immune system, nervous system and other organs beyond the involvement of autonomic signalling is lacking. By taking our cues from established and emerging concepts of neuro-immune interactions, immune-mediated inter-organ cross-talk, innate immune training and the role of microbiota-derived signals in central nervous system (CNS) function we will explore mechanisms of how cerebral ischaemia could shape systemic immune function. In this context, we will also discuss a key question: how are immune requirements critical for mediating repair of the ischaemic insult balanced by the need for anti-microbial immunity post-stroke, given that they are mediated by mutually exclusive immune networks? Our reformed understanding of the immune landscape post-stroke and novel mechanisms at play could guide targeted therapeutic interventions and initiate a step-change in the clinical management of these infectious complications post-stroke.

Prognostic significance of acute hypertensive response in ischemic stroke or transient ischemic attack patients and its relationship with left ventricular myocardial function

OBJECTIVES

Acute hypertensive response (AHR) in acute stroke is associated with adverse outcomes; however, the underlying pathophysiology of the association is poorly understood and its prognostic impact in ischemic stroke remains unclear. We aimed to investigate the prognostic significance of AHR in patients with ischemic stroke or transient ischemic attack (TIA), and further examined the relationship between AHR and myocardial function, using two-dimensional speckle-tracking echocardiography (2D-STE).

METHODS

A total of 244 consecutive patients with acute ischemic stroke (AIS) (n = 192) or TIA (n = 52), who were evaluated with 2D-STE within 7 days from admission, were retrospectively analysed. The primary endpoint was a composite of major adverse cardiovascular and cerebrovascular events (MACCE), including death, myocardial infraction or recurrent ischemic stroke.

RESULTS

Among the study population, AHR was observed in 161 (66%) patients. During a mean follow-up of 21.0 ± 12.5 months, 29 patients (11.9%) [25 (15.5%) AHR vs. 4 (4.8%) No AHR, P = 0.014] reached the primary endpoint. A Kaplan-Meier curve revealed that patients with AHR had a significantly higher incidence of MACCE than those without AHR (log-rank P = 0.013). Multivariate Cox regression analysis demonstrated that AHR [adjusted hazard ratio 4.60, 95% confidence interval (95% CI) 1.31-16.15] was a strong predictor of MACCE. In multivariate logistic regression analysis, left ventricular global longitudinal strain (per 1% decrease) showed a significant relationship with AHR (adjusted odds ratio 1.17, 95% CI 1.02-1.35).

CONCLUSION

AHR in patients with AIS or TIA may be an important poor prognostic marker related to myocardial dysfunction.

Systemic inflammation in hemorrhagic strokes - A novel neurological sign and therapeutic target?

Growing evidences suggest that stroke is a systemic disease affecting many organ systems beyond the brain. Stroke-related systemic inflammatory response and immune dysregulations may play an important role in brain injury, recovery, and stroke outcome. The two main phenomena in stroke-related peripheral immune dysregulations are systemic inflammation and post-stroke immunosuppression. There is emerging evidence suggesting that the spleen contracts following ischemic stroke, activates peripheral immune response and this may further potentiate brain injury. Whether similar brain-immune crosstalk occurs in hemorrhagic strokes such as intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) is not established. In this review, we systematically examined animal and human evidence to date on peripheral immune responses associated with hemorrhagic strokes. Specifically, we reviewed the impact of clinical systemic inflammatory response syndrome (SIRS), inflammation- and immune-associated biomarkers, the brain-spleen interaction, and cellular mediators of peripheral immune responses to ICH and SAH including regulatory T cells (Tregs). While there is growing data suggesting that peripheral immune dysregulation following hemorrhagic strokes may be important in brain injury pathogenesis and outcome, details of this brain-immune system cross-talk remain insufficiently understood. This is an important unmet scientific need that may lead to novel therapeutic strategies in this highly morbid condition.

Nosocomial Infections among Patients with Intracranial Hemorrhage: A Retrospective Data Analysis of Predictors and Outcomes

OBJECTIVE

Intracranial hemorrhage is a critical medical emergency. Nosocomial infections may promote worse outcomes in these vulnerable patients. This study investigated microbial features, predictors, and clinical outcomes of nosocomial infections among patients with multiple subtypes of intracranial hemorrhage.

PATIENTS AND METHODS

We conducted a retrospective cohort study of patients that were hospitalized with intracranial hemorrhage between January 2015 and October 2018, and divided them into two groups based on the development of nosocomial infection. Within the cohort of patients with nosocomial infections, microbiology and resistance patterns were established across multiple sites of infection. Moreover, consequences of nosocomial infection such as mortality and length of hospital stay were determined.

RESULTS

A total of 233 cases were identified that met our inclusion and exclusion criteria out of which were 94 cases of nosocomial infection (40.3%) versus 139 cases with no nosocomial infection (59.7%). The most common infections were pneumonia, urinary tract infections, and bacteremia. Resistance accounted for 70.2% of cultures. Multivariable analysis revealed significant association of nosocomial infections with hypertension (OR: 2.62, 95% CI: 1.11-6.16, p = 0.027), hospital LOS (OR: 1.08, 95% CI: 1.05-1.12, p < 0.001), levetiracetam (OR: 3.6, 95% CI: 1.41-0.922, p = 0.007), and GCS category (OR: 5.42, 95% CI: 1.67-17.55, p = 0.005 and OR: 7.63, 95% CI: 2.44-23.87, p < 0.001 for moderate and severe, respectively). Patients with nosocomial infections witnessed a significant increase in the length of hospital stay (23 versus 8 hospital days, p < 0.001). This finding was significant across most types of brain hemorrhage. Mortality was significantly associated with GCS category (OR: 10.1, 95% CI: 4-25.7, p < 0.001) and percutaneous endoscopic gastrostomy tube insertion (OR: 19.6, 95% CI: 4.1-91, p < 0.001).

CONCLUSIONS

Collectively, these findings suggest that nosocomial infections are common among patients with intracranial hemorrhage and can be predictable by considering certain risk factors. Future studies are warranted to evaluate the efficacy of implementing infection control strategies or protocols on these patients to achieve better therapeutic outcomes.

Clinical Improvement Following Stroke Promptly Reverses Post-stroke Cellular Immune Alterations

Background and Purpose: Stroke induces immediate profound alterations of the peripheral immune system rendering patients more susceptible to post-stroke infections. The precise mechanisms maintaining stroke-induced immune alterations (SIIA) remain unknown. High-Mobility-Group-Protein B1 (HMGB-1) is elevated for at least 7 days post-stroke and has been suggested to mediate SIIA. Patients with rapid clinical recovery of neurological deficits rarely develop severe infections. We therefore investigated whether rapid neurological recovery (either spontaneous or secondary to neurovascular recanalization therapy) alters the course of SIIA. National Institutes of Health Stroke Scale (NIHSS) served as surrogate marker for neurological improvement.

Methods: Fluorescence-activated cell sorting was used to define leukocyte subpopulations. C-reactive protein (CRP), procalcitonin (PCT), HMGB-1, GM-CSF; IFN-β, IFN-γ, IL-1β, IL-1RA, IL-2, IL-4, IL-5, IL-6, IL-10, IL-12, IL-17, IL-17F, IL-18, TNF-α, MIF, IL-8, MCP-1, MCP-4, MIP-3α, MIP-3β, Eotaxin, soluble IL-6 receptor, E-selectin, and P-selectin were analyzed by ELISA or Multiplex Assays. Serum miRNA expression changes were analyzed by qPCR.

Results: Cellular parameters were similar in the improved and non-improved cohort on admission. In patients with rapid clinical recovery absolute and relative leukocyte, neutrophil, and lymphocyte numbers normalized promptly overnight. In contrast, HMGB-1 serum levels did not differ between the two groups. Nine miRNA were found to be differentially expressed between improved and non-improved patients.

Conclusions: SIIA are detectable on admission of acute stroke patients. While it was assumed that post-stroke immunosuppression is rapidly reversed with improvement this is the first data set that shows that improvement actually is associated with a rapid reversal of SIIA demonstrating that SIIA require a constant signal to persist. The observation that HMGB-1 serum concentrations were similar in improved and non-improved cohorts argues against a role for this pro-inflammatory mediator in the maintenance of SIIA. Serum miRNA observed to be regulated in stroke in other publications was counter regulated with improvement in our cohort.

Management of Blood Pressure After Acute Ischemic Stroke

PURPOSE OF REVIEW

The present manuscript examines the significance of blood pressure elevation in patients with acute ischemic stroke, the physiologic principles worthy of consideration during its treatment, and the recent empirical evidence that should guide management protocols. It also provides a sound and practical approach to treatment along the time continuum, with particular relevance to reperfusion strategies.

RECENT FINDINGS

The existing evidence shows that both insufficient and excessive blood pressures are detrimental to the outcome of patients with acute ischemic stroke. This "U-shaped" relation, however, relates to measurements at the time of presentation, and clinical studies lack detail and specificity relative to differential measurements along the time continuum, particularly prior to and following reperfusion. Extrapolating from recent series, it is possible to construct treatment protocols balanced for effectiveness and safety. The management of blood pressure after acute ischemic stroke is an important, complex, and challenging aspect of care, requiring a thorough understanding of cerebrovascular physiology. Along the time continuum, the therapeutic priorities start with the preservation of penumbral tissue prior to reperfusion and then follow with the limitation of the damaging effects of excessive blood pressure readings after reperfusion, optimizing the chances of improved outcomes.

Randomised controlled trial of a Calcium Channel or Angiotensin Converting Enzyme Inhibitor/Angiotensin Receptor Blocker Regime to Reduce Blood Pressure Variability following Ischaemic Stroke (CAARBS): a protocol for a feasibility study

INTRODUCTION

Raised blood pressure (BP) is common after stroke and is associated with a poor prognosis, yet trials of BP lowering in the immediate poststroke period have not demonstrated a benefit. One possible explanation for this may be that BP variability (BPV) rather than absolute levels predicts outcome, as BPV is increased after stroke and is associated with poor outcomes. Furthermore, there is evidence of distinct antihypertensive class effects on BPV despite similar BP-lowering effects. However, whether BPV in the immediate poststroke period is a therapeutic target has not been prospectively investigated.The objectives of this trial are to assess the feasibility and safety of recruiting patients following an acute ischaemic stroke or transient ischaemic attack (TIA) to an interventional randomised controlled trial comparing the effects of two different antihypertensive drug classes on BPV. Secondary exploratory objectives are to assess if different therapeutic strategies have diverse effects on levels of BPV and if this has an impact on outcomes.

METHODS

150 adult patients with first-ever ischaemic stroke or TIA who require antihypertensive therapy for secondary prevention will be recruited within 7 days of the event from stroke services across three sites. After baseline assessments they will be randomly assigned to treatment with a calcium channel blocker or ACE inhibitor/angiotensin receptor blocker-based regimen and followed up for a period of three months.

ETHICS AND DISSEMINATION

Ethical and regulatory approvals have been granted. Dissemination is planned via publication in peer-reviewed medical journals and presentation at relevant conferences.

TRIAL REGISTRATION NUMBER

ISRCTN10853487.

Association of Elevated Blood Pressure Levels with Outcomes in Acute Ischemic Stroke Patients Treated with Intravenous Thrombolysis: A Systematic Review and Meta-Analysis

BACKGROUND AND PURPOSE

Although arbitrary blood pressure (BP) thresholds exist for acute ischemic stroke (AIS) patients eligible for intravenous thrombolysis (IVT), current international recommendations lack clarity on the impact of mean pre- and post-IVT BP levels on clinical outcomes.

METHODS

Eligible studies involving IVT-treated AIS patients were identified that reported the association of mean systolic BP (SBP) or diastolic BP levels before and after IVT with the following outcomes: 3-month favorable functional outcome (modified Rankin Scale [mRS] scores of 0-1) and 3-month functional independence (mRS scores of 0-2), 3-month mortality and symptomatic intracranial hemorrhage (sICH). Unadjusted analyses of standardized mean differences and adjusted analyses of studies reporting odds ratios (ORadj) per 10 mm Hg BP increment were performed using random-effects models.

RESULTS

We identified 26 studies comprising 56,513 patients. Higher pre- (P=0.02) and posttreatment (P=0.006) SBP levels were observed in patients with sICH. Patients with 3-month functional independence had lower post-treatment (P<0.001) SBP whereas trended towards lower pre-treatment (P=0.06) SBP. In adjusted analyses, elevated pre- (ORadj, 1.08; 95% confidence interval [CI], 1.01 to 1.16) and post-treatment (ORadj, 1.13; 95% CI, 1.01 to 1.25) SBP levels were associated with increased likelihood of sICH. Increasing pre- (ORadj, 0.91; 95% CI, 0.84 to 0.98) and post-treatment (ORadj, 0.70; 95% CI, 0.57 to 0.87) SBP values were also related to lower odds of 3-month functional independence.

CONCLUSION

s We found that elevated BP levels adversely impact AIS outcomes in patients receiving IVT. Future randomized-controlled clinical trials will provide definitive data on the aforementioned association.

Chemical Sympathectomy, but not Adrenergic Blockade, Improves Stroke Outcome

BACKGROUND

A robust adrenergic response following stroke impairs lymphocyte function, which may prevent the development of autoimmune responses to brain antigens. We tested whether inhibition of the sympathetic response after stroke would increase the propensity for developing autoimmune responses to brain antigens.

METHODS

Male Lewis rats were treated with 6-hydroxydopamine (OHDA) prior to middle cerebral artery occlusion (MCAO), labetalol after MCAO, or appropriate controls. Behavior was assessed weekly and animals survived to 1 month at which time ELISPOT assays were done on lymphocytes from spleen and brain to determine the Th1 and Th17 responses to myelin basic protein (MBP), ovalbumin (OVA), and concanavalin A. A subset of animals was sacrificed 72 hours after MCAO for evaluation of infarct volume and lymphocyte responsiveness. Plasma C-reactive protein (CRP) was measured as a biomarker of systemic inflammation.

RESULTS

Despite similar initial stroke severity and infarct volumes, 6-OHDA-treated animals lost less weight and experienced less hyperthermia after stroke. 6-OHDA-treated animals also had decreased CRP in circulation early after stroke and experienced better neurological outcomes at 1 month. The Th1 and Th17 responses to MBP did not differ among treatment groups at 1 month, but the Th1 response to OVA in spleen was more robust in labetalol and less robust in 6-OHDA-treated animals.

CONCLUSIONS

Chemical sympathectomy with 6-OHDA, but not treatment with labetalol, decreased systemic markers of inflammation early after stroke and improved long-term outcome. An increase in Th1 and Th17 responses to MBP was not seen with inhibition of the sympathetic response.

The effect of tyramine infusion and exercise on blood flow, coagulation and clot microstructure in healthy individuals

BACKGROUND

The long term benefits of exercise on the cardiovascular status of a patient have been proven, however, their benefit/risk relationship with exercise intensity is unclear. Furthermore, many thromboembolic diseases such as myocardial infarction and ischaemic stroke are associated with profound catecholamine release. In this study we explore the relationship between catecholamine release and hemodynamic changes and their effect on coagulation.

MATERIALS AND METHODS

Twelve healthy recreationally active males were recruited. Local anesthesia was given and catheters were placed under aseptic conditions, in the femoral artery and vein of the experimental leg. The first experiment involved tyramine infusion into the femoral artery at a dose of 1.0 μmol·min^-1·L leg volume^-1. The second experiment involved single leg knee-extensor exercise performed at 30 W for 15 min. Venous blood was collected at each time point to assess clot microstructure using the d_f biomarker.

RESULTS AND CONCLUSIONS

Tyramine infusion causes a local noradrenaline release in the leg. The increase in noradrenaline was associated with a significant increase in clot microstructure formation (d_f increased from 1.692 ± 0.029 to 1.722 ± 0.047, p = 0.016). Additionally moderate intensity single leg knee extensor exercise, which minimally alters sympathetic activity, also induced an increases in d_f (from 1.688 ± 0.025 to 1.723 ± 0.023, p = 0.001). This suggests that exercise can alter clot microstructure formation both via an increase in catecholeamine levels and by factors related to muscle activity per se, such as increased blood flow and consequent shear. These findings have implications for recommendations of exercise in patients at risk of cardiovascular events.

Prognostic Significance of Infarct Size and Location: The Case of Insular Stroke

The prognostic relevance of strokes in different locations is debated. For example, insular strokes have been associated with increased mortality, but this association could reflect their greater severity. In two independent cohorts of patients with supratentorial ischemic stroke (n = 90 and 105), we studied the prognostic consequences of lesion size and location using voxel-based lesion-symptom mapping before and after volume control, which better accounts for total lesion volume. Strokes affecting the insula were larger than non-insular strokes (28 vs 2cc and 25 vs 3cc, p < 0.001 in both cohorts). A number of supratentorial areas (mainly in the left hemisphere), including the insula, were associated with poor functional outcome in both cohorts before (4014 voxels) and after volume control (1378 voxels), while the associations with death were greatly reduced after volume control (from 8716 to 325 voxels). Exploratory analyses suggested that the method of lesion volume quantification, the National Institutes of Health Stroke Scale hemispheric bias and patient selection can result in false associations between specific brain lesions and outcomes. In conclusion, death in the first months after stroke is mainly explained by large infarct volumes, whereas lesions of specific supratentorial structures, mostly in the left hemisphere, also contribute to poor functional outcomes.

Adrenal hormones and circulating leukocyte subtypes in stroke patients treated with reperfusion therapy

Ischemic stroke sets in motion a dialogue between the central nervous and the immune systems that includes the sympathetic/adrenal system. We investigated the course of immune cells and adrenocortical and adrenomedullary effectors in a cohort of 51 patients with acute stroke receiving reperfusion therapy (intravenous alteplase or mechanical thrombectomy) and its correlation with stroke outcomes and infarct growth. Cortisol increased rapidly and fleetingly after stroke, but 39% of patients who had larger infarctions on admission showed a positive delta cortisol at day 1. It was associated with enhanced infarct growth (p = 0.002) and poor outcome [OR (95% CI) 5.30 (1.30-21.69)], and correlated with less lymphocytes and T cells at follow up. Likewise, fewer circulating lymphocytes, T cells, and Tregs were associated with infarct growth. By contrast, metanephrines did not increase at clinical onset, and decreased over time. Higher levels of NMN correlated with more Treg and B cells. Eventually, complete reperfusion at the end of therapy headed the identification of more circulating Tregs at day 1. Then activation of cortical or medullar compartments of the adrenal gland result in specific signatures on leukocyte subpopulations. Manipulation of the adrenal gland hormone levels warrants further investigation.

β-arrestin2 functions as a key regulator in the sympathetic-triggered immunodepression after stroke

Background

Stroke-induced immunodeficiency syndrome (SIDS) is regarded as a protective mechanism for secondary inflammatory injury as well as a contributor to infection complications. Although stroke-induced hyperactivation of the sympathetic system is proved to facilitate SIDS, the involved endogenous factors and pathways are largely elusive. In this study, we aim to investigate the function of beta-arrestin-2 (ARRB2) in the sympathetic-mediated SIDS.

Methods

Splenic ARRB2 expression and the sympathetic system activity were detected after establishing transient models of middle cerebral artery occlusion (MCAO). In addition, a correlation between ARRB2 expression and the sympathetic system activity was analyzed using a linear correlation analysis. Any SIDS reflected in monocyte dysfunction was investigated by measuring inflammatory cytokine secretion and neurological deficit scores and infarct volume were tested to assess neurological outcome. Further, ARRB2 expression in the monocytes was knocked down in vitro by siRNAs. Following the stimulation of noradrenaline and lipopolysaccharide, cytokine secretion and the nuclear factor-κB (NF-κB) pathway were evaluated to gain insight into the mechanisms related to the contribution of ARRB2 to adrenergic-induced monocyte dysfunction.

Results

Splenic ARRB2 expression was significantly increased after stroke and also showed a significant positive correlation with the sympathetic system activity. Stroke-induced monocyte dysfunction resulted in an increase of the interleukin-10 (IL-10) level as well as a decrease of the interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) levels. Also, blockade of adrenergic-activity significantly reversed these cytokine levels, and blockade of adrenergic-activity improved stroke-induced neurological results. However, the improved neurological results had no significant correlation with ARRB2 expression. Furthermore, the in vitro results showed that the deficiency of ARRB2 dramatically repealed adrenergic-induced monocyte dysfunction and the inhibition of NF-κB signaling phosphorylation activity.

Conclusions

ARRB2 is implicated in the sympathetic-triggered SIDS, in particular, monocyte dysfunction after stroke. Accordingly, ARRB2 may be a promising therapeutic target for the immunological management of stroke in a clinic.