Transient oxygen–glucose deprivation sensitizes brain capillary endothelial cells to rtPA at 4h of reoxygenation

International audienceThrombolysis treatment of acute ischemic stroke is limited by the pro-edematous and hemorrhagic effects exerted by reperfusion, which disrupts the blood-brain barrier (BBB) capillary endothelium in the infarct core. Most studies of the ischemic BBB overlook the complexity of the penumbral area, where the affected brain cells are still viable following deprivation. Our present objective was to examine in vitro the kinetic impact of reoxygenation on the integrity of ischemic BBB cells after oxygen-glucose deprivation. Through the use of a co-culture of brain capillary endothelial cells and glial cells, we first showed that the transendothelial permeability increase induced by deprivation can occur with both preserved cell viability and interendothelial tight junction network. The subtle and heterogeneous alteration of the tight junctions was observable only through electron microscopy. A complete permeability recovery was then found after reoxygenation, when Vimentin and Actin networks were reordered. However, still sparse ultrastructural alterations of tight junctions suggested an acquired vulnerability. Endothelial cells were then exposed to recombinant tissue-type plasminogen activator (rtPA) to define a temporal profile for the toxic effect of this thrombolytic on transendothelial permeability. Interestingly, the reoxygenated BBB broke down with aggravated tight junction disruption when exposed to rtPA only at 4h after reoxygenation. Moreover, this breakdown was enhanced by 50% when ischemic glial cells were present during the first hours of reoxygenation. Our results suggest that post-stroke reoxygenation enables retrieval of the barrier function of brain capillary endothelium when in a non-necrotic environment, but may sensitize it to rtPA at the 4-hour time point, when both endothelial breakdown mechanisms and glial secretions could be identified and targeted in a therapeutical perspective

A Pilot Clinical Study on Post-Operative Recurrence Provides Biological Clues for a Role of Candida Yeasts and Fluconazole in Crohn’s Disease

Background and aims: This study prompted by growing evidence of the relationship between the yeast Candida albicans and Crohn’s disease (CD) was intended to assess the effect of a 6-month course of the antifungal fluconazole (FCZ) on post-operative recurrence of CD. Methods: Mycological samples (mouth swabs and stools) and serum samples were collected from 28 CD patients randomized to receive either FCZ (n = 14) or placebo (n = 14) before surgical resection. Serological analysis focused on levels of calprotectin, anti-glycan antibodies, and antibody markers of C. albicans pathogenic transition. Levels of galectin-3 and mannose binding lectin (MBL) involved in C. albicans sensing and inflammation were also measured. Results: 1, 2, 3, and 6 months after surgery, endoscopy revealed recurrence in 5/12 (41.7%) patients in the FCZ group and 5/9 (55.6%) in the placebo group, the small cohort preventing any clinical conclusions. In both groups, surgery was followed by a marked decrease in C. albicans colonization and biomarkers of C. albicans pathogenic transition decreased to non-significant levels. Anti-glycan antibodies also decreased but remained significant for CD. Galectin-3 and calprotectin also decreased. Conversely, MBL levels, which inversely correlated with anti-C. albicans antibodies before surgery, remained stable. Building biostatistical multivariate models to analyze he changes in antibody and lectin levels revealed a significant relationship between C. albicans and CD. Conclusion: Several combinations of biomarkers of adaptive and innate immunity targeting C. albicans were predictive of CD recurrence after surgery, with area under the curves (AUCs) as high as 0.86. FCZ had a positive effect on biomarkers evolution. ClinicalTrials.gov ID: NCT02997059, 19 December 2016. University Hospital Lille, Ministry of Health, France. Effect of Fluconazole on the Levels of Anti-Saccharomyces cerevisiae Antibodies (ASCA) After Surgical Resection for Crohn’s Disease. Multicenter, Randomized, and Controlled in Two Parallel Groups Versus Placebo