Hematoma size as major modulator of the cellular immune system after experimental intracerebral hemorrhage

Mesenteric and omental lymphatic malformations in children: seven-year surgical experience from two centers in China

PURPOSE

To compare the clinical characteristics, surgical management and prognosis of mesenteric lymphatic malformations (ML) and omental lymphatic malformations (OL) in children.

METHODS

This retrospective study included 148 ML patients and 53 OL patients who underwent surgical treatment at two centers between January 2016 and December 2022. Details about the patients' clinical characteristics, cyst characteristics, preoperative complications, surgical methods, and prognosis were retrieved and compared.

RESULTS

No significant differences in sex ratio, prenatal diagnosis, or age of diagnosis were noted between ML and OL patients. Vomiting was more common in ML patients than in OL patients (46.6% vs. 22.6%, P = 0.002), but OL patients were more likely to be misdiagnosed (35.8% vs. 18.9%, P = 0.012). The size of the cysts in OL patients was significantly larger than that in ML patients (14.0 [4.0-30.0] vs. 10.0 [2.0-50.0] cm, P<0.001), and cysts with turbid fluid were more common in OL patients (38.0% vs. 20.6%, P<0.001). More OL patients than ML patients had preoperative hemorrhage or infection of cysts (41.5% vs. 31.8%, P<0.016). Cyst excision was performed in 137 (92.6%) ML patients and 51 (96.2%) OL patients, and the incidence of postoperative complications was lower (12.6% vs. 4.2%, P = 0.165) among OL patients. The main postoperative complications included adhesive ileus and recurrence of cysts. Additionally, more OL patients than ML patients were treated with laparoscopic surgery (69.8% vs. 39.2%, P<0.001).

CONCLUSIONS

There were differences in clinical characteristics, cyst characteristics and preoperative complications between ML and OL patients. Cyst excision was the most common surgical method that was used to treat both ML and OL patients, and laparoscopic surgery could be a feasible surgical approach for treating OL patients with a good prognosis.

TRIAL REGISTRATION

Retrospectively registered.

Systemic immune inflammation index and system inflammation response index on the third postoperative day predict poor prognosis of aneurysmal subarachnoid hemorrhage patients

The inflammatory response is involved in the progression of aneurysmal subarachnoid hemorrhage (aSAH). We sought to investigate the relationships of inflammatory indicators including blood cell counts and the ratios of different blood cells counts with the prognosis of aSAH patients. We performed a retrospective study including 140 patients with aSAH and aneurysm surgeries. The relationships of neutrophils, lymphocytes, monocytes, platelets, systemic immune inflammation index (SII), system inflammation response index (SIRI), neutrophil-lymphocyte ratio and platelet-lymphocyte ratio with prognosis were investigated by univariable analysis and multivariable logistic regression model. The patient with Modified Rankin Scale (mRS) score＜3 was defined as having a good prognosis, while with mRS score ≥3 was defined as having a poor prognosis. Among 140 patients included, there were 108 cases with good prognosis and 32 cases with poor prognosis after follow-up. On the 3rd postoperative day, the neutrophils counts, SIRI level and SII level in cases with poor prognosis were significantly higher than cases with good prognosis, P < .05. After adjusting for baseline differences in Hunt-Hess grade, Glasgow Coma Scale score, combination with intraventricular hemorrhage and maximum diameter of aneurysm, the levels of SIRI (odds ratio = 3.968, 95% CI: 1.432-10.992, P = .008) and SII (odds ratio = 3.313, 95% CI: 1.029-10.665, P = .045) on the 3rd postoperative day could predict poor prognosis. SII and SIRI on the 3rd postoperative day could independently predict the poor prognosis in aSAH. However, the cutoff values for predicting prognosis needs to be validated in larger-sample studies.

Targeting brain-peripheral immune responses for secondary brain injury after ischemic and hemorrhagic stroke

The notion that the central nervous system is an immunologically immune-exempt organ has changed over the past two decades, with increasing evidence of strong links and interactions between the central nervous system and the peripheral immune system, both in the healthy state and after ischemic and hemorrhagic stroke. Although primary injury after stroke is certainly important, the limited therapeutic efficacy, poor neurological prognosis and high mortality have led researchers to realize that secondary injury and damage may also play important roles in influencing long-term neurological prognosis and mortality and that the neuroinflammatory process in secondary injury is one of the most important influences on disease progression. Here, we summarize the interactions of the central nervous system with the peripheral immune system after ischemic and hemorrhagic stroke, in particular, how the central nervous system activates and recruits peripheral immune components, and we review recent advances in corresponding therapeutic approaches and clinical studies, emphasizing the importance of the role of the peripheral immune system in ischemic and hemorrhagic stroke.

Development and validation of a nomogram model for prediction of stroke-associated pneumonia associated with intracerebral hemorrhage

BACKGROUND

We aimed to establish risk factors for stroke-associated pneumonia (SAP) following intracerebral hemorrhage (ICH) and develop an efficient and convenient model to predict SAP in patients with ICH.

METHODS

Our study involved 1333 patients consecutively diagnosed with ICH and admitted to the Neurology Department of the First Affiliated Hospital of Wenzhou Medical University. The 1333 patients were randomly divided (3:1) into the derivation cohort (n = 1000) and validation Cohort (n = 333). Variables were screened from demographics, lifestyle-related factors, comorbidities, clinical symptoms, neuroimaging features, and laboratory tests. In the derivation cohort, we developed a prediction model with multivariable logistic regression analysis. In the validation cohort, we assessed the model performance and compared it to previously reported models. The area under the receiver operating characteristic curve (AUROC), GiViTI calibration belt, net reclassification index (NRI), integrated discrimination index (IDI) and decision curve analysis (DCA) were used to assess the prediction ability and the clinical decision-making ability.

RESULTS

The incidence of SAP was 19.9% and 19.8% in the derivation (n = 1000) and validation (n = 333) cohorts, respectively. We developed a nomogram prediction model including age (Odds Ratio [OR] 1.037, 95% confidence interval [CI] 1.020-1.054), male sex (OR 1.824, 95% CI 1.206-2.757), multilobar involvement (OR 1.851, 95% CI 1.160-2.954), extension into ventricles (OR 2.164, 95% CI 1.456-3.215), dysphagia (OR 3.626, 95% CI 2.297-5.725), disturbance of consciousness (OR 2.113, 95% CI 1.327-3.362) and total muscle strength of the worse side (OR 0.93, 95% CI 0.876-0.987). Compared with previous models, our model was well calibrated and showed significantly higher AUROC, better reclassification ability (improved NRI and IDI) and a positive net benefit for predicted probability thresholds between 10% and 73% in DCA.

CONCLUSIONS

We developed a simple, valid, and clinically useful model to predict SAP following ICH, with better predictive performance than previous models. It might be a promising tool to assess the individual risk of developing SAP for patients with ICH and optimize decision-making.

The Osaka prognostic score and Naples prognostic score: novel biomarkers for predicting short-term outcomes after spontaneous intracerebral hemorrhage

OBJECTIVES

Poor immune-nutritional status has been associated with an unfavorable outcome in critical illness. The Osaka prognostic score (OPS) and the Naples prognostic score (NPS), based on inflammatory and nutritional status, has been shown to predict prognosis following cancer and other diseases. The aim of this study was to investigate the relationship between the OPS and NPS and the short-term outcomes of patients with intracerebral hemorrhage (ICH).

METHODS

We retrospectively analyzed the clinical data of patients hospitalized with spontaneous ICH (n = 340) at The Second Affiliated Hospital of Chongqing Medical University between August 2016 and August 2021. Inclusion criteria included patients aged between 18 and 70, and if a blood sample was taken for laboratory testing within 24 h of admission (serum C-reactive protein, albumin, total cholesterol, and counts for neutrophils, lymphocytes, and monocytes were collected on admission). Exclusion criteria included a non-spontaneous cause of ICH and patient death during hospitalization. Patients were divided into four groups based on OPS or five groups according to NPS. Outcomes were evaluated by the modified Rankin Scale (mRS) at six months post-ICH hospitalization. An unfavorable outcome was defined as a mRS score ≥ 3.

RESULTS

A total of 289 patients met our inclusion criteria. The unfavorable outcome group had older age, a lower Glasgow Coma Scale score, a higher rate of complications and cerebral herniation, a longer hospital stay, and higher OPS and NPS when compared with the favorable outcome group. Univariate analysis showed that both OPS and NPS were strongly correlated with mRS (r = 0.196,P < 0.001; r = 0.244, P = 0.001, respectively). Multivariate analysis further showed that OPS and NPS were both independent predictors of unfavorable outcomes for patients with ICH with adjusted odds ratios of 1.802 (95% confidence interval [CI]:1.140-2.847, P = 0.012) and 1.702 (95% CI: 1.225-2.635, P = 0.02), respectively. The area under the curve (AUC) of NPS for predicting a poor outcome was 0.732 (95% CI: 0.665-0.799), which was similar to the AUC of OPS 0.724 (95% CI: 0.657-0.792).

CONCLUSIONS

In this cohort, a higher OPS and NPS on admission was associated with poor outcome at six months following ICH, supporting their potential role as markers for predicting the outcome of patients with ICH.

The use of multiple datasets to identify autophagy-related molecular mechanisms in intracerebral hemorrhage

Background: Intracerebral hemorrhage (ICH) is a stroke syndrome with high mortality and disability rates, but autophagy’s mechanism in ICH is still unclear. We identified key autophagy genes in ICH by bioinformatics methods and explored their mechanisms.

Methods: We downloaded ICH patient chip data from the Gene Expression Omnibus (GEO) database. Based on the GENE database, differentially expressed genes (DEGs) for autophagy were identified. We identified key genes through protein–protein interaction (PPI) network analysis and analyzed their associated pathways in Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG). Gene-motif rankings, miRWalk and ENCORI databases were used to analyze the key gene transcription factor (TF) regulatory network and ceRNA network. Finally, relevant target pathways were obtained by gene set enrichment analysis (GSEA).

Results: Eleven autophagy-related DEGs in ICH were obtained, and IL-1B, STAT3, NLRP3 and NOD2 were identified as key genes with clinical predictive value by PPI and receiver operating characteristic (ROC) curve analysis. The candidate gene expression level was significantly correlated with the immune infiltration level, and most of the key genes were positively correlated with the immune cell infiltration level. The key genes are mainly related to cytokine and receptor interactions, immune responses and other pathways. The ceRNA network predicted 8,654 interaction pairs (24 miRNAs and 2,952 lncRNAs).

Conclusion: We used multiple bioinformatics datasets to identify IL-1B, STAT3, NLRP3 and NOD2 as key genes that contribute to the development of ICH.

CNS-peripheral immune interactions in hemorrhagic stroke

Stroke is a sudden and rapidly progressing ischemic or hemorrhagic cerebrovascular disease. When stroke damages the brain, the immune system becomes hyperactive, leading to systemic inflammatory response and immunomodulatory disorders, which could significantly impact brain damage, recovery, and prognosis of stroke. Emerging researches suggest that ischemic stroke-induced spleen contraction could activate a peripheral immune response, which may further aggravate brain injury. This review focuses on hemorrhagic strokes including intracerebral hemorrhage (ICH) and subarachnoid hemorrhage (SAH) and discusses the central nervous system-peripheral immune interactions after hemorrhagic stroke induction. First, inflammatory progression after ICH and SAH is investigated. As a part of this review, we summarize the various kinds of inflammatory cell infiltration to aggravate brain injury after blood-brain barrier interruption induced by hemorrhagic stroke. Then, we explore hemorrhagic stroke-induced systemic inflammatory response syndrome (SIRS) and discuss the interactions of CNS and peripheral inflammatory response. In addition, potential targets related to inflammatory response for ICH and SAH are discussed in this review, which may lead to novel therapeutic strategies for hemorrhagic stroke.

The immunopathology of B lymphocytes during stroke-induced injury and repair

B cells, also known as B lymphocytes or lymphoid lineage cells, are a historically understudied cell population with regard to brain-related injuries and diseases. However, an increasing number of publications have begun to elucidate the different phenotypes and roles B cells can undertake during central nervous system (CNS) pathology, including following ischemic and hemorrhagic stroke. B cell phenotype is intrinsically linked to function following stroke, as they may be beneficial or detrimental depending on the subset, timing, and microenvironment. Factors such as age, sex, and presence of co-morbidity also influence the behavior of post-stroke B cells. The following review will briefly describe B cells from origination to senescence, explore B cell function by integrating decades of stroke research, differentiate between the known B cell subtypes and their respective activity, discuss some of the physiological influences on B cells as well as the influence of B cells on certain physiological functions, and highlight the differences between B cells in healthy and disease states with particular emphasis in the context of ischemic stroke.

Essential topics about the imaging diagnosis and treatment of Hemorrhagic Stroke: a comprehensive review of the 2022 AHA guidelines

Intracerebral hemorrhage (ICH) is a severe stroke with a high death rate (40 % mortality). The prevalence of hemorrhagic stroke has increased globally, with changes in the underlying cause over time as anticoagulant use and hypertension treatment have improved. The fundamental etiology of ICH and the mechanisms of harm from ICH, particularly the complex interaction between edema, inflammation, and blood product toxicity, have been thoroughly revised by the American Heart Association (AHA) in 2022. Although numerous trials have investigated the best medicinal and surgical management of ICH, there is still no discernible improvement in survival and functional tests. Small vessel diseases, such as cerebral amyloid angiopathy (CAA) or deep perforator arteriopathy (hypertensive arteriopathy), are the most common causes of spontaneous non-traumatic intracerebral hemorrhage (ICH). Even though ICH only causes 10-15% of all strokes, it contributes significantly to morbidity and mortality, with few acute or preventive treatments proven effective. Current AHA guidelines acknowledge up to 89% sensitivity for unenhanced brain CT and 81% for brain MRI. The imaging findings of both methods are helpful for initial diagnosis and follow-up, sometimes necessary a few hours after admission, especially for detecting hemorrhagic transformation or hematoma expansion. This review summarized the essential topics on hemorrhagic stroke epidemiology, risk factors, physiopathology, mechanisms of injury, current management approaches, findings in neuroimaging, goals and outcomes, recommendations for lifestyle modifications, and future research directions ICH. A list of updated references is included for each topic.

Interactions between the Autonomic Nervous System and the Immune System after Stroke

Acute stroke is one of the leading causes of morbidity and mortality worldwide. Stroke-induced immune-inflammatory response occurs in the perilesion areas and the periphery. Although stroke-induced immunosuppression may alleviate brain injury, it hinders brain repair as the immune-inflammatory response plays a bidirectional role after acute stroke. Furthermore, suppression of the systemic immune-inflammatory response increases the risk of life-threatening systemic bacterial infections after acute stroke. Therefore, it is essential to explore the mechanisms that underlie the stroke-induced immune-inflammatory response. Autonomic nervous system (ANS) activation is critical for regulating the local and systemic immune-inflammatory responses and may influence the prognosis of acute stroke. We review the changes in the sympathetic and parasympathetic nervous systems and their influence on the immune-inflammatory response after stroke. Importantly, this article summarizes the mechanisms on how ANS regulates the immune-inflammatory response through neurotransmitters and their receptors in immunocytes and immune organs after stroke. To facilitate translational research, we also discuss the promising therapeutic approaches modulating the activation of the ANS or the immune-inflammatory response to promote neurologic recovery after stroke. © 2022 American Physiological Society. Compr Physiol 12:3665-3704, 2022.

Natural killer cell deficiency experiences higher risk of sepsis after critical intracerebral hemorrhage

Background: Lymphopenia is common in intracerebral hemorrhage (ICH) and may predispose to severe infections such as sepsis. However, what specific kind of lymphocytes subsets decreases is still unclear. We investigated the impact of lymphocytes subsets on post-critical ICH infections and mortality.

Methods: Consecutive ICH patients (admitted to a single center between January 2017 and January 2018) were prospectively assessed to evaluate the following main parameters: peripheral blood lymphocytes, infections, and clinical scores. Predicting factors of sepsis were measured using multivariate Logistic regressions analysis. A Kaplan–Meier survival curve was performed to compare the mortality between septic and nonseptic patients. Survival status was evaluated by multivariate Cox regression analysis.

Results: In total, 112 critical ICH cases were enrolled including 29 septic patients. Total counts of lymphocytes decreased accordingly with reduced lymphocyte subsets, especially natural killer (NK) cells and CD8⁺T lymphocytes after ICH. Septic patients had a higher incidence of pneumonia, a longer length of stay, higher 90-day mortality, and worse long-term outcomes. Multivariate Logistic regression analysis showed venous catheterization, high APACHE-II score (>15), low GCS score (3–5), and NK cells percentages on admission were independently associated with ensuing sepsis. After sepsis, the percentages of CD4+T and NK cells percentages decreased, CD8+T cells increased followed by a significantly decreased CD4/CD8 ratio. Bloodstream infection alone directly affected the survival status of patients with sepsis.

Conclusions: Critical ICH patients underwent immune dysfunction and NK cells deficiency could favor nosocomial threatening sepsis after ICH.

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.

Immune changes in peripheral blood and hematoma of patients with intracerebral hemorrhage

Immunologic changes in the hematoma of patients with intracerebral hemorrhage (ICH) and the contribution of these changes to prognosis are unknown. We collected the blood samples and hematoma fluid from 35 patients with acute ICH (<30 hours from symptom onset) and 55 age-matched healthy controls. Using flow cytometry and ELISA, we found that the percentages of granulocytes, regulatory T cells, helper T (Th) 17 cells, and dendritic cells were higher in the peripheral blood of patients with ICH than in healthy controls, whereas the percentages of lymphocytes, M1-like macrophages, and M2-like macrophages were lower. Levels of IL-6, IL-17, IL-23, TNF-α, IL-4, IL-10, and TGF-β were higher in the peripheral blood of patients with ICH. The absolute counts of white blood cells, lymphocytes, monocytes, and granulocytes in the hematoma tended to be greater at 12-30 hours than they were within 12 hours after ICH, but the percentage of Th cells decreased in peripheral blood. Increased levels of IL-10 in the serum and hematoma, and a reduction in M1-like macrophages in hematoma were independently associated with favorable outcome on day 90. These results indicate that immunocytes present in the hematoma may participate in the acute-phase inflammatory response after ICH.

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.

Minocycline Preserves the Integrity and Permeability of BBB by Altering the Activity of DKK1-Wnt Signaling in ICH Model

Disruption of the blood-brain barrier (BBB) and subsequent neurological deficits are the most severe consequence of intracerebral hemorrhage (ICH). Minocycline has been wildly used clinically as a neurological protective agent in clinical practice. However, the underlying mechanisms by which minocycline functions remain unclear. Therefore, we assessed the influence of minocycline on BBB structure, neurological function, and inflammatory responses in a collagenase-induced ICH model, and elucidated underlying molecular mechanisms as well. Following a single injection of collagenase VII-S into the basal ganglia, BBB integrity was assessed by Evans blue extravasation while neurological function was assessed using an established neurologic function scoring system. Minocycline treatment significantly alleviated the severity of BBB disruption, brain edema, and neurological deficits in ICH model. Moreover, minocycline decreased the production of inflammatory mediators including TNF, IL-6, and MMP-9, by microglia. Minocycline treatment decreased DKK1 expression but increased Wnt1, β-catenin and Occludin, a phenomenon mimicked by DKK1 silencing. These data suggest that minocycline improves the consequences of ICH by preserving BBB integrity and attenuating neurologic deficits in a DKK1-related manner that involves enhancement of the Wnt1-β-catenin activity.

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.

Changes in the cellular immune system and circulating inflammatory markers of stroke patients

This study was designed to investigate dynamic changes in the cellular immune system and circulating inflammatory markers after ischemic stroke. Blood was collected from 96 patients and 99 age-matched control subjects for detection of lymphocyte subpopulations and inflammatory markers. We observed decreases in B cells, Th cells, cytotoxic T cells, and NK cells and an increase in regulatory T (Treg) cells in stroke patients on days 1, 3, and 7. Serum levels of TNF-α, C-reactive protein (CRP), IL-4, IL-6, IL-10, IL-17, IL-23, and TGF-β increased, whereas serum level of IFN-γ decreased at all time points after stroke. Stroke patients with infection exhibited a similar tendency toward changes in some lymphocyte subpopulations and inflammatory markers as stroke patients without infection. After controlling for NIH Stroke Scale (NIHSS), we observed no differences in lymphocyte subpopulations between patients with anterior circulation stroke and those with posterior circulation stroke at any time point. The splenic volume correlated positively with the percentages of B cells, Th cells, and cytotoxic T cells, but negatively with Treg cells on day 3 after stroke. Infections were associated with splenic volume, leukocyte counts, percentage of Treg cells, and serum levels of CRP, IL-10, and IFN-γ on day 3. Lesion volume correlated positively with CRP, IL-6, and IL-23, but negatively with IFN-γ on day 3. The NIHSS showed a positive relation with IL-6 and IL-10 on day 3. Ischemic stroke has a profound effect on the systemic immune system that might explain the increased susceptibility of stroke patients to infection.

Organ- and cell-specific immune responses are associated with the outcomes of intracerebral hemorrhage

Severe brain injury significantly influences immune responses; however, the levels at which this influence occurs and which neurogenic pathways are involved are not well defined. Here, we used MRI to measure spleen volume and tissue diffusion changes in patients with intracerebral hemorrhage (ICH). We observed increased capillary exchange and spleen shrinkage by d 3 post-ICH, with recovery by d 14. The extent of spleen shrinkage was associated with brain hematoma size, and a reduced progression of perihematomal edema was observed in the presence of severe spleen shrinkage. At the cellular level, lymphopenia was present in patients with ICH at admission and persisted up to 14 d. Lymphopenia did not parallel the observed spleen alteration. In addition, patients with ICH with infection had significant deficiencies of T and NK cells and poor functional outcomes. Finally, in mouse models of ICH, spleen shrinkage could be related to innervations from adrenergic input and the hypothalamus-pituitary-adrenal (HPA) axis. In sum, the profound impact of ICH on the immune system involves the coordinated actions of sympathetic innervation and the HPA axis, which modulate spleen shrinkage and cellular immunity.-Zhang, J., Shi, K., Li, Z., Li, M., Han, Y., Wang, L., Zhang, Z., Yu, C., Zhang, F., Song, L., Dong, J.-F., La Cava, A., Sheth, K. N., Shi, F.-D. Organ- and cell-specific immune responses are associated with the outcomes of intracerebral hemorrhage.

Injury mechanisms in acute intracerebral hemorrhage

Intracerebral hemorrhage (ICH) is the most common hemorrhagic stroke subtype, and rates are increasing with an aging population. Despite an increase in research and trials of therapies for ICH, mortality remains high and no interventional therapy has been demonstrated to improve outcomes. We review known mechanisms of injury, recent clinical trial results, and newly discovered signaling pathways involved in hematoma clearance. Enthusiasm remains high for methods of minimally invasive clot removal as well as pharmacologic strategies to improve recovery after ICH, both of which are currently being evaluated in clinical trials. This article is part of the Special Issue entitled 'Cerebral Ischemia'.

Assessment of systemic cellular inflammatory response after spontaneous intracerebral hemorrhage

OBJECTIVE

After spontaneous intracerebral hemorrhage (ICH) a local and systemic inflammatory response is activated. Interleukin-6 (IL) is one of most relevant orchestrators of inflammatory responses in the brain and is released from multiple immune cells, including neutrophils. Herby we assessed the relevance of systemic inflammation in patients suffering ICH.

METHODS

From October 2010 to October 2011 we included in our routine of laboratory investigations besides to C-reactive protein (CRP), the addition of IL-6 and an analysis of the subpopulation of circulating blood cells. Values at admission, at 3rd and 7th day after admission were evaluated. We analyzed 43 patients with non-traumatic ICH; stroke-related ICH or tumor associated hemorrhage were excluded. Outcome variables were 30 and 90-day mortality and NIHSS at discharge. A natural logarithmic transformation of IL-6, lymphocytes, and monocytes was used.

RESULTS

8.6% died within 30-days and mortality increased to 39.5% at 90th day. Total leukocytes and neutrophils as well as IL-6 at admission were statistically significant increased among patients who died within 30days after ICH onset (p=0.002). IL-6 and CRP in follow-up (3rd and 7th day) were higher among patients with poor outcome (NIHSS >15). The number of circulating lymphocytes and monocytes was not different in measurement. Leukocytes and neutrophils at 3rd day after admission were augmented in patients with respiratory infection and CRP in follow-up increased if some kind of infection was clinically or microbiologically detected. IL-6 at admission and in follow-up and monocytes at 7th day were related to ICH volume. CRP-values at 3rd or 7th day but not at admission were associated to bigger ICH-volume. The values of IL-6 were highly correlated to 30-day mortality and volume of ICH as CRP only with ICH volume.

CONCLUSION

After ICH onset a systemic activation of immune system seems to be induced and may be influencing outcome. Peripheral recruitment of leukocytes, especially neutrophils could be a target for future therapeutic interventions. Because of the tighter correlation of IL-6 at admission, it might be more accurate for prognostic issues than CRP.

Progress in translational research on intracerebral hemorrhage: is there an end in sight?

Intracerebral hemorrhage (ICH) is a common and often fatal stroke subtype for which specific therapies and treatments remain elusive. To address this, many recent experimental and translational studies of ICH have been conducted, and these have led to several ongoing clinical trials. This review focuses on the progress of translational studies of ICH including those of the underlying causes and natural history of ICH, animal models of the condition, and effects of ICH on the immune and cardiac systems, among others. Current and potential clinical trials also are discussed for both ICH alone and with intraventricular extension.

Variants of COL3A1 are associated with the risk of stroke recurrence and prognosis in the Chinese population: a prospective study

Type III collagen plays an important role in activating platelets, forming thrombus, and maintaining the mechanical properties of arteries. This study aimed to test the hypothesis that genetic variants of COL3A1 (gene encoding type III collagen) contribute to recurrence and prognosis of stroke. We investigated the associations of three variants (rs2138533, rs11887092, and rs1800255) in the COL3A1 gene with stroke recurrence and prognosis in 1,544 patients with three subtypes of stroke: lacunar infarction (n = 442), atherothrombotic infarction (n = 670), and hemorrhage (n = 432). These associations were evaluated by Kaplan-Meier analysis and Cox regression models. Patients were followed up for 4.5 years. The A allele of rs1800255 in the COL3A1 gene coding region was significantly associated with a reduced risk of stroke recurrence in patients with lacunar infarction (adjusted hazard ratio [HR] 0.58, 95 % confidence interval [CI] 0.36-0.93, P = 0.024), but there was an increased risk of all-cause mortality of atherothrombotic patients (adjusted HR 1.43, 95 % CI 1.01-2.00, P = 0.044). The TT genotype of rs2138533 showed a significantly increased risk of death caused by cardiovascular disease or stroke in lacunar infarct patients (adjusted HR 2.98, 95 % CI 1.27-6.98, P = 0.012), but there was a reduced risk of all-cause mortality for patients with intracerebral hemorrhage (adjusted HR 0.34, 95 % CI 0.12-0.93, P = 0.036). The G allele of rs11887092 increased the risk of stroke recurrence in patients with atherothrombotic stroke (adjusted HR 1.59, 95 % CI 1.04-2.44, P = 0.035). In conclusion, variants of COL3A1 might play a vital role in determining the risk of recurrence and prognosis after stroke.

Stress mediators and immune dysfunction in patients with acute cerebrovascular diseases

Background

Post-stroke immune depression contributes to the development of infections which are major complications after stroke. Previous experimental and clinical studies suggested that humoral stress mediators induce immune dysfunction. However, prospective clinical studies testing this concept are missing and no data exists for other cerebrovascular diseases including intracerebral hemorrhage (ICH) and TIA.

Methods

We performed a prospective clinical study investigating 166 patients with TIA, ischemic and hemorrhagic stroke. We measured a broad panel of stress mediators, leukocyte subpopulations, cytokines and infection markers from hospital admission to day 7 and on follow-up after 2–3 months. Multivariate regression analyses detected independent predictors of immune dysfunction and bacterial infections. ROC curves were used to test the diagnostic value of these parameters.

Results

Only severe ischemic strokes and ICH increased some catecholamine metabolites, ACTH and cortisol levels. Immunodysfunction was eminent already on hospital admission after large brain lesions with lymphocytopenia as a key feature. None of the stress mediators was an independent predictor of lymphocytopenia or infections. However, lymphocytopenia on hospital admission was detected as an independent explanatory variable of later infections. NIHSSS and lymphocytopenia on admission were excellent predictors of infection.

Conclusions

Our results question the present pathophysiological concept of stress-hormone mediated immunodysfunction after stroke. Early lymphocytopenia was identified as an early independent predictor of post-stroke infections. Absence of lymphocytopenia may serve as a negative predictive marker for stratification for early antibiotic treatment.

Comparison of humoral neuroinflammation and adhesion molecule expression in two models of experimental intracerebral hemorrhage

Background

Inflammatory cascades contribute to secondary injury after intracerebral hemorrhage (ICH) via humoral factors and cell-mediated cytotoxicity. Several experimental models were previously developed to analyze post-hemorrhagic neuroinflammation. However, neuroinflammatory markers have not been compared face-to-face between these models so far, and therefore, pathophysiological conclusions drawn from only one individual model may not be valid.

Methods

We compared neuroinflammatory pathways in the two most common murine models: striatal injection of autologous blood or collagenase. Expression of pro- and anti-inflammatory cytokines (IL-1, TNF-α, IFN-γ, IL-6, TGF-β and IL-10) as well adhesion molecule expression (VCAM-1, ICAM-1) was analyzed by RT-PCR at several time points after ICH induction. Outcome and physiological parameters were compared between the models.

Results

Both models induced a profound and dynamic increase in the expression of pro-inflammatory cytokines and adhesion molecules. However, blood injection resulted in significantly more pronounced alteration of these markers than collagenase injection. This difference was associated with worse outcome after blood injection compared to the collagenase model despite equal ICH volumes.

Conclusions

This is the first study performing a face-to-face comparison of neuroinflammatory pathways in the two most widely used murine ICH models, revealing substantial differences between the models. This discrepancies need to be taken into account in designing future studies employing experimental ICH models, especially when analyzing neuroinflammatory pathways and therapies.

Treatment with the immunomodulator FTY720 does not promote spontaneous bacterial infections after experimental stroke in mice

Background

FTY720, an immunomodulator derived from a fungal metabolite which reduces circulating lymphocyte counts by increasing the homing of lymphocytes to the lymph nodes has recently gained interest in stroke research. The aim of this study was to evaluate the protective efficacy of FTY720 in cerebral ischemia in two different application paradigms and to gather first data on the effect of FTY720 on the rate of spontaneous bacterial infections in experimental stroke.

Methods

Middle cerebral artery occlusion (MCAO) in C57BL/6 mice (strain J, groups of 10 animals) was performed with two different durations of ischemia (90 min and 3 h) and FTY720 was applied 2 h after vessel occlusion to study the impact of reperfusion on the protective potency of FTY720. Lesion size was determined by TTC staining. Mice treated with FTY720 or vehicle were sacrificed 48 h after 90 min MCAO to determine the bacterial burden in lung and blood.

Results

FTY720 1 mg/kg significantly reduced ischemic lesion size when administered 2 h after the onset of MCAO for 3 h (45.4 ± 22.7 mm³ vs. 84.7 ± 23.6 mm³ in control mice, p = 0.001) and also when administered after reperfusion, 2 h after the onset of MCAO for 90 min (31.1 ± 28.49 mm³ vs. 69.6 ± 27.2 mm³ in control mice, p = 0.013). Bacterial burden of lung homogenates 48 h after stroke did not increase in the group treated with the immunomodulator FTY720 while there was no spontaneous bacteremia 48 h after MCAO in treated and untreated animals.

Conclusions

Our results corroborate the experimental evidence of the protective effect of FTY720 seen in different rodent stroke models. Interestingly, we found no increase in bacterial lung infections even though FTY720 strongly reduces the number of circulating leukocytes.