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Abstract Blood–brain barrier (BBB) disruption contributes to brain injury and neurological impairment. Tight junctions (TJs) and cell–cell adhesion complexes develop between endothelial cells in the brain to establish and maintain the BBB. Occludin, the first transmembrane protein identified in TJs, has received intense research interest because numerous in vitro studies have suggested its importance in maintaining BBB integrity. However, its role in maintaining BBB integrity after ischemic stroke is less clear owing to the lack of in vivo evidence. This study aimed to investigate the dynamics and function of occludin across the acute and chronic phases after stroke using occludin-deficient mice. By photochemically induced thrombosis model, the expression of occludin was decreased in brain endothelial cells from ischemic lesions. The neurological function of occludin-deficient mice was continuously impaired compared to that of wild-type mice. BBB integrity evaluated by Evans blue and 0.5-kDa fluorescein in the acute phase and by 10-kDa fluorescein isothiocyanate-labeled dextran in the chronic phase was decreased to a greater extent after stroke in occludin-deficient mice. Furthermore, occludin-deficient mice showed decreased claudin-5 and neovascularization after stroke. Our study reveals that occludin plays an important role from the acute to the chronic phase after ischemic stroke in vivo. more...

Abstract MicroRNA-132/212 has been supposed as a critical gene related to the blood–brain barrier (BBB) protection after stroke, but its regulation pathway including the upstream regulator and downstream targets is still unclear. Herein, we demonstrated the cAMP response element-binding protein (CREB)-regulated transcription coactivator-1 (CRTC1) to be the upstream regulator of miRNA-132/212 using CRTC1 knockout and wild-type mice. CRTC1 deletion led to the reduction of miRNA-132/212 expression in mice brain after ischemic stroke, significantly increased infarct volume, and aggravated BBB permeability with worsening neurological deficits. Furthermore, we identified that miRNA-132 repressed Claudin-1, tight junction-associated protein-1 (TJAP-1), and RNA-binding Fox-1 (RBFox-1) by directly binding to their respective 3′-untranslated regions, which alleviated the ischemic damage by enhancing neuronal survival and BBB integrity. Moreover, the co-culture of endothelial cells with CRTC1-deficient neurons aggravated the cell vulnerability to hypoxia, also supporting the idea that miRNA-132/212 cluster is regulated by CRTC1 and acts as a crucial role in the mitigation of ischemic damage. This work is a step forward for understanding the role of miRNA-132/212 in neurovascular interaction and may be helpful for potential gene therapy of ischemic stroke. more...

Background and Purpose: Once a stroke occurs in a patient with atrial fibrillation (AF), it is likely to be severe. Patients with newly diagnosed AF after stroke and those with known AF before stroke have different background characteristics, yet the difference in stroke severity has not been sufficiently evaluated. In the current study, we compared the stroke severity and in-hospital outcomes between these patient groups.Methods: We retrospectively analyzed a database of 196 patients with acute ischemic stroke and AF between January 2010 and October 2019. We divided the patients into two groups: patients with “newly diagnosed AF” and those with “known AF.” We assessed the stroke severity using the National Institutes of Health Stroke Scale (NIHSS) score on admission and in-hospital outcomes using the modified Rankin Scale (mRS) score at discharge.Results: The proportion of newly diagnosed AF was 33% (64/196). There were no differences in age, hypertension, diabetes mellitus, and past history of heart failure between patients with newly diagnosed AF and those with known AF. Patients with newly diagnosed AF were associated with a lower proportion of male sex (male; 50 vs. 67%, p < 0.05), a lower proportion of past history of stroke (12 vs. 35%, p < 0.01), a lower CHA2DS2-VASc score (median [interquartile range]; 3 [2–4] vs. 3.5 [3–5], p < 0.01), and a lower proportion of pre-stroke oral anticoagulation (5 vs. 59%, p < 0.01). There were no differences in the NIHSS score on admission (12 [4–19] vs. 9 [3–19]) or the mRS score at discharge (3 [1–5] vs. 3 [1–5]). After adjustment for relevant covariates, newly diagnosed AF was not associated with the NIHSS score on admission [adjusted common odds ratio (OR), 0.85; 95% confidence interval (CI), 0.45–1.60] or the mRS score at discharge (adjusted common OR, 1.67; 95% CI, 0.88–3.18). After propensity score matching, newly diagnosed AF was not associated with the NIHSS score on admission (adjusted common OR, 0.91; 95% CI, 0.48–1.73) and the mRS score at discharge (adjusted common OR, 1.77; 95% CI, 0.92–3.43).Conclusion: Stroke severity and in-hospital outcomes in patients with newly diagnosed AF did not differ from those in patients with known AF after adjustment for clinically relevant factors. The importance of detection of latent AF and subsequent anticoagulation in preventing severe stroke should be further emphasized. more...