Increased blood-brain barrier permeability in contralateral hemisphere predicts worse outcome in acute ischemic stroke after reperfusion therapy

Post-endovascular treatment, blood-brain barrier disruption, predicts patient outcomes better than pre-treatment status

OBJECTIVES

Blood-brain barrier (BBB) disruption is an important pathological change after cerebral infarction that exacerbates brain injury. We aimed to investigate and compare the predictive utility of pre-treatment BBB permeability (BBBP) and BBBP within 1 h after endovascular treatment (EVT) for hemorrhagic transformation (HT) and 90-day prognosis.

METHODS

Patients underwent preoperative computed tomography perfusion (CTP) and non-contrast CT (NCCT) within 1 h after EVT. Preoperative BBBP was determined by the relative permeability surface area product (rPS) in the hypoperfusion area. Postoperative BBBP was determined by the post-EVT Alberta Stroke Program Early CT Score (Post-ASPECTS), which is based on brain parenchymal hyperdensity on the postoperative NCCT.

OUTCOMES

We included 100 patients. Univariate logistic regression analysis revealed correlations of preoperative rPS with HT, poor outcomes, and death. However, these correlations were not observed in multivariate logistic regression. A Post-ASPECTS ≤7 and could independently predict poor outcomes, while Post-ASPECTS ≤6 could independently predict death and HT. The baseline National Institutes of Health Stroke Scale (NIHSS) score could independently predict poor outcomes and death but not HT. A combined model using the baseline NIHSS and Post-ASPECTS scores had better predictive performance for poor outcomes and death than baseline NIHSS score alone; however, it was not superior to the predictive performance of the Post-ASPECTS score.

CONCLUSION

The preoperative rPS cannot independently predict clinical outcomes in EVT-treated patients; contrastingly, the Post-ASPECTS score could independently predict poor outcomes, death, and HT. This parameter could inform prompt postoperative treatment decisions.

Microvascular dysfunction associated with unfavorable venous outflow in acute ischemic stroke patients

Unfavorable venous outflow (VO) is associated with cerebral edema, which represents microvascular dysfunction. This study estimated the relationship between VO and microvascular function in acute ischemic stroke patients. We retrospectively included 102 MCA/ICA occluded patients with anterior circulation infarction who underwent reperfusion therapy between July 2017 and April 2022. Unfavorable VO was defined as a cortical vein opacification score of 0-3 and favorable VO as that of 4-6. The clinical characteristics, collateral status, microvascular integrity, and outcomes were compared between patients with favorable and unfavorable VO. Multivariate analysis and receiver operator characteristic (ROC) analysis were used. The patients with unfavorable VO had higher extravascular-extracellular volume fraction (Ve) in the infarct core and a lower percentage of robust arterial collateral circulation. ROC analysis revealed that Ve in the infarct core predicts unfavorable VO (AUC = 0.67, sensitivity = 65.08%, specificity = 69.23%). The higher Ve in the infarct core (odds ratio = 1.011, 95% CI = 1.000-1.021, P = 0.046) and poor arterial collateral flow (odds ratio = 0.102, 95% CI = 0.032-0.327, P < 0.001) were independent predictors of unfavorable VO. This suggests that microvascular dysfunction may be one of the mechanisms underlying impaired VO.

Predictive Value of CT Perfusion in Hemorrhagic Transformation after Acute Ischemic Stroke: A Systematic Review and Meta-Analysis

Background: Existing studies indicate that some computed tomography perfusion (CTP) parameters may predict hemorrhagic transformation (HT) after acute ischemic stroke (AIS), but there is an inconsistency in the conclusions alongside a lack of comprehensive comparison. Objective: To comprehensively evaluate the predictive value of CTP parameters in HT after AIS. Data sources: A systematical literature review of existing studies was conducted up to 1st October 2022 in six mainstream databases that included original data on the CTP parameters of HT and non-HT groups or on the diagnostic performance of relative cerebral blood flow (rCBF), relative permeability-surface area product (rPS), or relative cerebral blood volume (rCBV) in patients with AIS that completed CTP within 24 h of onset. Data Synthesis: Eighteen observational studies were included. HT and non-HT groups had statistically significant differences in CBF, CBV, PS, rCBF, rCBV, and rPS (p < 0.05 for all). The hierarchical summary receiver operating characteristic (HSROC) revealed that rCBF (area under the curve (AUC) = 0.9), rPS (AUC = 0.89), and rCBV (AUC = 0.85) had moderate diagnostic performances in predicting HT. The pooled sensitivity and specificity of rCBF were 0.85 (95% CI, 0.75−0.91) and 0.83 (95% CI, 0.63−0.94), respectively. Conclusions: rCBF, rPS, and rCBV had moderate diagnostic performances in predicting HT, and rCBF had the best pooled sensitivity and specificity.

Association between cerebral blood flow changes and blood-brain barrier compromise in spontaneous intracerebral haemorrhage

AIM

To quantitatively evaluate blood-brain barrier (BBB) permeability in the perihaematomal region of spontaneous intracerebral haemorrhage (ICH) and investigate the association between the alterations in cerebral blood flow and BBB permeability around the haematoma.

MATERIALS AND METHODS

Spontaneous ICH patients underwent unenhanced computed tomography (CT) and CT perfusion (CTP) simultaneously. Haematoma volume was measured on CT. The values of cerebral haemodynamic parameters including cerebral blood flow (CBF), cerebral blood volume (CBV), mean transit time (MTT), time to peak (TTP), and permeability-surface area product (PS) were measured in the perihaematomal region and the contralateral mirror region, and then relative values were calculated for statistical analysis. Linear regression was used to evaluate associations between BBB permeability and variables.

RESULTS

A total of 87 ICH patients were included in this study. The focally elevated BBB permeability was observed in the perihaematomal region in ICH patients. Linear regression showed that reduced rCBF (β = -0.379, p=0.001) and increased rCBV (β = 0.412, p=0.000) correlated independently with increased relative PS (rPS) value in deep ICH, while only increased rCBV (β = 0.423, p=0.071) correlated to increased rPS value in patients with lobar ICH.

CONCLUSIONS

BBB permeability is focally elevated in the region around the haematoma. Cerebral haemodynamic alterations are associated with increased BBB permeability. Cerebral hypoperfusion may aggravate BBB compromise, and a compensatory increase in CBV may lead to reperfusion injury on BBB.

Microglia: The Hub of Intercellular Communication in Ischemic Stroke

Communication between microglia and other cells has recently been at the forefront of research in central nervous system (CNS) disease. In this review, we provide an overview of the neuroinflammation mediated by microglia, highlight recent studies of crosstalk between microglia and CNS resident and infiltrating cells in the context of ischemic stroke (IS), and discuss how these interactions affect the course of IS. The in-depth exploration of microglia-intercellular communication will be beneficial for therapeutic tools development and clinical translation for stroke control.

Relationship between treatment types and blood–brain barrier disruption in patients with acute ischemic stroke: Two case reports

BACKGROUND

Blood-brain barrier (BBB) disruption plays an important role in the development of neurological dysfunction in ischemic stroke. However, diagnostic modalities that can clearly diagnose the degree of BBB disruption in ischemic stroke are limited. Here, we describe two cases in which the usefulness of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) in detecting BBB disruption was evaluated after treatment of acute ischemic stroke using two different methods.

CASE SUMMARY

The two patients of similar age and relatively similar cerebral infarction locations were treated conservatively or with thrombectomy, although their sex was different. As a result of analysis by performing DCE-MRI, it was confirmed that BBB disruption was significantly less severe in the patient who underwent thrombectomy (P = 3.3 × 10^-7), whereas the average K_trans of the contralateral hemisphere in both patients was similar (2.4 × 10^-5 min^-1 and 2.0 × 10^-5 min^-1). If reperfusion is achieved through thrombectomy, it may indicate that the penumbra can be saved and BBB recovery can be promoted.

CONCLUSION

Our cases suggest that BBB disruption could be important if BBB permeability is used to guide clinical treatment.

S-1-propenylcysteine improves TNF-α-induced vascular endothelial barrier dysfunction by suppressing the GEF-H1/RhoA/Rac pathway

Background

Vascular endothelial barrier function is maintained by cell-to-cell junctional proteins and contributes to vascular homeostasis. Various risk factors such as inflammation disrupt barrier function through down-regulation of these proteins and promote vascular diseases such as atherosclerosis. Previous studies have demonstrated that aged garlic extract (AGE) and its sulfur-containing constituents exert the protective effects against several vascular diseases such as atherosclerosis. In this study, we examined whether AGE and its sulfur-containing constituents improve the endothelial barrier dysfunction elicited by a pro-inflammatory cytokine, Tumor-necrosis factor-α (TNF-α), and explored their mode of action on TNF-α signaling pathway.

Methods

Human umbilical vein endothelial cells (HUVECs) were treated with test substances in the presence of TNF-α for various time periods. The endothelial permeability was measured by using a transwell permeability assay. The localization of cell-to-cell junctional proteins and actin cytoskeletons were visualized by immunostaining. RhoA and Rac activities were assessed by using GTP-binding protein pulldown assay. Gene and protein expression levels of signaling molecules were analyzed by real-time PCR and western blotting, respectively.

Results

We found that AGE and its major sulfur-containing constituent, S-1-propenylcysteine (S1PC), reduced hyperpermeability elicited by TNF-α in HUVECs. In addition, S1PC inhibited TNF-α-induced production of myosin light chain (MLC) kinase and inactivation of MLC phosphatase through the suppression of the Rac and RhoA signaling pathways, respectively, which resulted in the dephosphorylation of MLC2, a key factor of actin remodeling. Moreover, S1PC inhibited the phosphorylation and activation of guanine nucleotide exchange factor-H1 (GEF-H1), a common upstream key molecule and activator of Rac and RhoA. These effects of S1PC were accompanied by its ability to prevent the disruption of junctional proteins on the cell–cell contact regions and the increase of actin stress fibers induced by TNF-α.

Conclusions

The present study suggested that AGE and its major constituent, S1PC, improve endothelial barrier disruption through the protection of junctional proteins on plasma membrane.

Sex-specific differences in white matter microvascular integrity after ischaemic stroke

Background and purpose

Functional outcomes after ischaemic stroke are worse in women, despite adjusting for differences in comorbidities and treatment approaches. White matter microvascular integrity represents one risk factor for poor long-term functional outcomes after ischaemic stroke. The aim of the study is to characterise sex-specific differences in microvascular integrity in individuals with acute ischaemic stroke.

Methods

A retrospective analysis of subjects with acute ischaemic stroke and brain MRI with diffusion-weighted (DWI) and dynamic-susceptibility contrast-enhanced (DSC) perfusion-weighted imaging obtained within 9 hours of last known well was performed. In the hemisphere contralateral to the acute infarct, normal-appearing white matter (NAWM) microvascular integrity was measured using the K₂ coefficient and apparent diffusion coefficient (ADC) values. Regression analyses for predictors of K₂ coefficient, DWI volume and good outcome (90-day modified Rankin scale (mRS) score <2) were performed.

Results

105 men and 79 women met inclusion criteria for analysis. Despite no difference in age, women had increased NAWM K₂ coefficient (1027.4 vs 692.7×10^–6/s; p=0.006). In women, atrial fibrillation (β=583.6; p=0.04) and increasing NAWM ADC (β=4.4; p=0.02) were associated with increased NAWM K₂ coefficient. In multivariable regression analysis, the K₂ coefficient was an independent predictor of DWI volume in women (β=0.007; p=0.01) but not men.

Conclusions

In women with acute ischaemic stroke, increased NAWM K₂ coefficient is associated with increased infarct volume and chronic white matter structural integrity. Prospective studies investigating sex-specific differences in white matter microvascular integrity are needed.