Neutrophil Extracellular Trap-Related Extracellular Histones Cause Vascular Necrosis in Severe GN

Severe GN involves local neutrophil extracellular trap (NET) formation. We hypothesized a local cytotoxic effect of NET-related histone release in necrotizing GN. In vitro, histones from calf thymus or histones released by neutrophils undergoing NETosis killed glomerular endothelial cells, podocytes, and parietal epithelial cells in a dose-dependent manner. Histone-neutralizing agents such as antihistone IgG, activated protein C, or heparin prevented this effect. Histone toxicity on glomeruli ex vivo was Toll-like receptor 2/4 dependent, and lack of TLR2/4 attenuated histone-induced renal thrombotic microangiopathy and glomerular necrosis in mice. Anti–glomerular basement membrane GN involved NET formation and vascular necrosis, whereas blocking NET formation by peptidylarginine inhibition or preemptive anti-histone IgG injection significantly reduced all aspects of GN (i.e., vascular necrosis, podocyte loss, albuminuria, cytokine induction, recruitment or activation of glomerular leukocytes, and glomerular crescent formation). To evaluate histones as a therapeutic target, mice with established GN were treated with three different histone-neutralizing agents. Anti-histone IgG, recombinant activated protein C, and heparin were equally effective in abrogating severe GN, whereas combination therapy had no additive effects. Together, these results indicate that NET-related histone release during GN elicits cytotoxic and immunostimulatory effects. Furthermore, neutralizing extracellular histones is still therapeutic when initiated in established GN.     

Ruthenium counterstaining for imaging mass cytometry

Imaging mass cytometry is a novel imaging modality that enables simultaneous antibody‐based detection of >40 epitopes and molecules in tissue sections at subcellular resolution by the use of isotopically pure metal tags. Essential for any imaging approach in which antigen detection is performed is counterstaining, which reveals the overall structure of the tissue. Counterstaining is necessary because antigens of interest are often present in only a small subset of cells, and the rest of the tissue structures are not visible. As most biological tissues are nearly transparent or non‐fluorescent, chromogenic reagents such as haematoxylin (for immunohistochemistry) or fluorescent dyes such as 4′,6‐diamidino‐2‐phenylindole (which stains nuclei for epifluorescence and confocal microscopy) are utilized. Here, we describe a metal‐based counterstain for imaging mass cytometry based on simple oxidation and subsequent covalent binding of the tissue components to ruthenium tetroxide (RuO₄). RuO₄ counterstaining reveals general tissue structure both in areas with high cell content and in stromal areas with low cellularity and fibrous or hyaline material in a manner analogous to haematoxylin in immunohistochemical counterstaining or eosin or other anionic dyes in conventional histology. Our new counterstain approach is applicable to any metal‐based imaging technique, and will facilitate the adaptation of imaging mass cytometry for routine applications in clinical and research laboratories. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Prophylactic CMV therapy does not improve three‐yr patient and graft survival compared to preemptive therapy

Despite increasing evidence in favor of prophylactic valganciclovir treatment in kidney transplant recipients for the prevention of cytomegalovirus (CMV) infection, the impact of preemptive vs. prophylactic treatment on long‐term clinical outcomes is unclear. In this retrospective study, 187 kidney transplant recipients with serologic intermediate‐risk constellation (recipient CMV IgG positive) received either preemptive or prophylactic treatment with valganciclovir. Patient survival (primary endpoint), graft survival, viremia rates, and other CMV‐related outcomes were analyzed. Prophylactic therapy reduced the rates for CMV viremia during the first year (hazard ratio: 0.48, 95% confidence interval [CI] 0.30–0.75; p < 0.001). There was a trend for higher three‐yr patient mortality in the prophylactic group (hazard ratio: 5.08, 95% CI 0.62–41.3; p = 0.091), and the rate of graft loss was not reduced (hazard ratio: 0.93, 95% CI 0.32–2.68; p = 0.894). Estimated glomerular filtration rate over three yr was on average 6.8 mL/min/1.73 m² lower in the prophylactic group (95% CI −11.68 to −1.81; p = 0.007) using a multivariate random effects model but showed more improvement over time. Prophylactic valganciclovir treatment reduced the rate of CMV infections during the first year post‐transplant but no effects of prophylactic treatment on patient and graft survival or kidney function over three yr were observed.     

Cardiovascular medication seems to promote recovery of autonomic dysfunction after stroke

Journal of Neurology - Stroke may compromise cardiovascular–autonomic modulation (CAM). The longitudinal post-stroke CAM alterations remain unclear as previous studies excluded patients with...