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Graft-versus-host disease (GVHD) remains a frequently occurring and difficult-to-treat complication in human allogeneic stem cell transplantation. Murine transplantation models are often used to study and understand the complex pathogenesis of GVHD and to explore new treatment strategies. Although GVHD kinetics may differ in murine and human models, adequate models are essential for identification of the crucial factors responsible for the major pathology in GVHD. We present a detailed description of the specific histological features of a graft-versus-host–induced fibrotic response in xenogeneic RAG2−/−γc−/− mice after total body irradiation and injection with human peripheral blood mononuclear cells. We describe the full morphological features of this reaction, including a detailed analysis of the specific tissue infiltration patterns of the human peripheral blood mononuclear cells. Our data show the development of fibrosis, predominantly near blood vessels, and reveal different cell populations and specific cell migration patterns in the affected organs. The combination of immunohistochemical cell characterization and mRNA expression analysis of both human (donor)- and murine (host)-derived cytokines reveals an interaction between host tissues and donor-derived cells in an entangled cytokine profile, in which both donor- and host-derived cytokines contribute to the formation of fibrosis. [ABSTRACT FROM AUTHOR]

: Background:Left ventricular assist device (LVAD) implantation in patients with end-stage heart failure results in impressive hemodynamic improvement. The effects on myocardial apoptosis and its mediators are unknown.: Methods:Myocardial biopsies from 17 patients at the time of LVAD implantation and after explantation, at the time of heart transplantation (HTx), were examined by terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL) reaction and with antibodies against Fas ligand (FasL), Fas, tumor necrosis factor (TNF)-α receptor 1 (TNF-R1), TNF-α receptor 2 (TNF-R2), TNF-α, TNF-α–converting enzyme (TACE), poly(ADP-ribose) polymerase (PARP), poly(ADP-ribose) (PAR), caspase-3 and FLICE inhibitory protein (FLIP).: Results:Apoptosis incidence was low: 0.8% (range 0% to 3%) positive cardiomyocytes nuclei before support, and 0.1% (range 0% to 0.6%) after support (p < 0.01). This was accompanied by low expression of caspase-3 and high expression of the DNA repair enzyme, PARP. Its product, PAR, increased after support. Mediators and receptors inducing apoptosis as well as FLIP were widely present before and after support.: Conclusions:Despite the abundant presence of mediators and receptors inducing apoptosis, the incidence of apoptosis itself was low before and after mechanical support. The abundant expression of FLIP may suggest an important role for this protein in the inhibition of cardiomyocyte death. [Copyright &y& Elsevier]

Background: Collagens are important components of the extracellular matrix (ECM). Alterations in collagen structure and composition can lead to end-stage heart failure. Left ventricular assist devices (LVADs) are frequently used as a bridge to heart transplantation (HTx). In this study, we analyzed changes in composition of the collagens as well as the synthesis or degradation of these collagens after prolonged LVAD support. Methods: The ECM volume was quantified after Picro-Sirius red staining. With immunohistochemistry (IHC), Type I and Type III collagen proteins were analyzed and, using quantitative polymerase chain reaction (PCR), collagen mRNA expression was analyzed. Collagen synthesis and degradation was studied by measuring N-terminal pro-peptide for Type I collagen (PINP), N-terminal pro-peptide for Type III collagen (PIIINP) and carboxyterminal telopeptide for Type I collagen (ICTP) in plasma. Collagen composition was measured using the hydroxyproline/Sircol assay. Results: The ECM volume increased in the first 200 days after LVAD implantation. At between 200 and 400 days the ECM volume decreased, but remained higher than pre-LVAD. After 400 days the ECM volume was smaller than the pre-LVAD volume. IHC did not show a significant difference pre- and post-LVAD for collagen composition. Collagen mRNA expression did not change but an augmented synthesis of collagen during the first month after LVAD support was detected upon measurement of plasma PINP and PIIINP levels. In addition, the quality of the collagen network improved. Conclusions: Reverse remodeling during LVAD support follows a biphasic pattern. Initially, an increase in Type I and Type III collagen turnover occurs, which is paralleled by a volume increase of the ECM. Subsequently, this turnover decreases as ECM volume decreases, which results in a restoration of the collagen network. [Copyright &y& Elsevier]

Objective: To investigate mutations in genes that are potential modifiers of spinal muscular atrophy (SMA) severity., Methods: We performed a hypothesis-based search into the presence of variants in fused in sarcoma ( FUS ) , transactive response DNA-binding protein 43 ( TDP-43 ), plastin 3 ( PLS3 ), and profilin 2 ( PFN2 ) in a cohort of 153 patients with SMA types 1-4, including 19 families. Variants were detected with targeted next-generation sequencing and confirmed with Sanger sequencing. Functional effects of the identified variants were analyzed in silico and for PLS3, by analyzing expression levels in peripheral blood., Results: We identified 2 exonic variants in FUS exons 5 and 6 (p.R216C and p.S135N) in 2 unrelated patients, but clinical effects were not evident. We identified 8 intronic variants in PLS3 in 33 patients. Five PLS3 variants (c.1511+82T>C; c.748+130 G>A; c.367+182C>T; c.891-25T>C (rs145269469); c.1355+17A>G (rs150802596)) potentially alter exonic splice silencer or exonic splice enhancer sites. The variant c.367+182C>T, but not RNA expression levels, corresponded with a more severe phenotype in 1 family. However, this variant or level of PLS3 expression did not consistently correspond with a milder or more severe phenotype in other families or the overall cohort. We found 3 heterozygous, intronic variants in PFN2 and TDP-43 with no correlation with clinical phenotype or effects on splicing., Conclusions: PLS3 and FUS sequence variants do not modify SMA severity at the population level. Specific variants in individual patients or families do not consistently correlate with disease severity., (Copyright © 2020 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.)