Catégorie : Article scientifique

Endothelial precursor cell cross-match using Tie-2-enriched spleen cells

Abstract

Background

Non-HLA antibodies against human endothelial progenitor cells (EPC) in pre-transplant recipient serum can have a deleterious influence on the graft. EPC enriched from peripheral blood have been commonly used for EPC cross-matching. In the present study, we describe cross-matches using EPC enriched from fresh or frozen-thawed spleen cell preparations, thereby widening the sample source for deceased-donor cross-matching and retrospective studies.

Methods

EPC cross-matches were performed retrospectively using spleen cells and the flow cytometric XM-ONE cross-match test kit.

Results

Healthy controls (n = 28) showed no IgG antibodies against EPC. When sera of 11 random dialysis patients were studied, 2 patients (18%) exhibited IgG EPC antibodies. When pre-transplant sera of 20 kidney graft recipients with good long-term graft outcome (serum creatinine 1.0 ± 0.2 mg/dL measured 2463 ± 324 days post-transplant) were investigated using frozen-thawed and then separated Tie-2-enriched spleen cells of the original transplant donor, 3 patients (15%) had pre-transplant IgG EPC antibodies. When pre-transplant sera of 5 patients with intra-operative graft loss were studied employing the original donor spleen cells, 4 (80%) patients showed IgG EPC antibodies.

Conclusions

Cross-matches with spleen cell-derived EPC using the XM-ONE assay are technically possible. Our very preliminary experience suggests clinical relevance.

© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Septembre 2017 / Clinical Transplantation – Daniel V, Süsal C, Scherer S, Tran H, Gombos P, Trojan K, Sadeghi M, Morath C, Opelz G.

Biglycan expression in the melanoma microenvironment promotes invasiveness via increased tissue stiffness inducing integrin-β1 expression

Abstract

Novel targeted and immunotherapeutic approaches have revolutionized the treatment of metastatic melanoma. A better understanding of the melanoma-microenvironment, in particular the interaction of cells with extracellular matrix molecules, may help to further improve these new therapeutic strategies.We observed that the extracellular matrix molecule biglycan (Bgn) was expressed in certain human melanoma cells and primary fibroblasts when evaluated by microarray-based gene expression analysis. Bgn expression in the melanoma tissues correlated with low overall-survival and low progression-free-survival in patients. To understand the functional role of Bgn we used gene-targeted mice lacking functional Bgn. Here we observed that melanoma growth, metastasis-formation and tumor-related death were reduced in Bgn-/- mice compared to Bgn+/+ mice. In vitro invasion of melanoma cells into organotypic-matrices derived from Bgn-/- fibroblasts was reduced compared to melanoma invasion into Bgn-proficient matrices. Tissue stiffness as determined by atomic-force-microscopy was reduced in Bgn-/- matrices. Isolation of melanoma cells and fibroblasts from the stiffer Bgn+/+ matrices revealed an increase in integrin-β1 expression compared to the Bgn-/- fibroblast matrices. Overexpression of integrin-β1 in B16-melanoma cells abolished the survival benefit seen in Bgn-/- mice. Consistent with the studies performed in mice, the abundance of Bgn-expression in human melanoma samples positively correlated with the expression of integrin-β1, which is in agreement with results from the organotypic invasion-assay and the in vivo mouse studies.This study describes a novel role for Bgn-related tissue stiffness in the melanoma-microenvironment via regulation of integrin-β1 expression by melanoma cells in both mice and humans.

Juin 2017 / Oncotarget – écrit par Andrlová H, Mastroianni J, Madl J, Kern JS, Melchinger W, Dierbach H, Wernet F, Follo M, Technau-Hafsi K, Has C, Rao Mittapalli V, Idzko M, Herr R, Brummer T, Ungefroren H, Busch H, Boerries M, Narr A, Ihorst G, Vennin C, Schmitt-Graeff A, Minguet S, Timpson P, Duyster J, Meiss F, Römer W, Zeiser R

Clinical Relevance of HLA Antibodies in Kidney Transplantation: Recent Data from the Heidelberg Transplant Center and the Collaborative Transplant Study

Résumé
Herein, we summarize our recent findings from the international Collaborative Transplant Study (CTS) and Heidelberg Transplant Center regarding the role of HLA antibodies in kidney transplantation and their application into the clinical routine. Based on the antibody findings from the CTS serum study, an algorithm was developed in 2006 for the transplantation of high-risk sensitized patients at the Heidelberg Transplant Center which includes seven different pre- and posttransplant measures. Using this algorithm, the number of transplantations could be increased in high-risk presensitized patients and the previously existing impact of antibodies on graft survival could greatly be diminished but not totally eliminated. More recent findings led to the hypothesis that T cell help from a preactivated immune system supports the harmful effects of pretransplant donor-specific HLA antibodies that otherwise disappear in many cases after transplantation without any consequence.

Juin 2017 / Journal of Immunology Research – Süsal C, Fichtner A, Tönshoff B, Mehrabi A, Zeier M, Morath C

Plus d’informations : https://www.ncbi.nlm.nih.gov/pubmed/28660215

MicroRNA-146a reduces MHC-II expression via targeting JAK/STAT signaling in dendritic cells after stem cell transplantation

Résumé
Acute Graft-versus-host disease (GVHD) is a major immunological complication after allogeneic hematopoietic cell transplantation and a better understanding of the molecular regulation of the disease could help to develop novel targeted therapies. Here we found that a G/C polymorphism within the human microRNA-146a (miR-146a) gene of transplant recipients, which causes reduced miR-146a levels, was strongly associated with the risk of developing severe acute GVHD (n=289). In mice, deficiency of miR-146a in the hematopoietic system or transfer of recipient-type miR-146a-/- dendritic cells (DCs) enhanced GVHD, while miR-146a mimic-transfected DCs ameliorated disease. Mechanistically, lack of miR-146a enhanced JAK2-STAT1 pathway activity, which led to higher expression of class II-transactivator (CIITA) and consecutively increased MHCII-levels on DCs. Inhibition of JAK1/2 or CIITA knockdown in DCs prevented miR-146a-/- DC-induced GVHD exacerbation. Consistent with our findings in mice, patients with the miR-146a polymorphism rs2910164 in hematopoietic cells displayed higher MHCII levels on monocytes, which could be targeted by JAK1/2 inhibition. Our findings indicate that the miR-146a polymorphism rs2910164 identifies patients at high risk for GVHD before allo-HCT. Functionally we show that miR-146a acts as a central regulator of recipient-type DC activation during GVHD by dampening the pro-inflammatory JAK-STAT/CIITA/MHCII axis, which provides a scientific rationale for early JAK1/2 inhibition in selected patients.Leukemia advance online publication, 26 May 2017; doi:10.1038/leu.2017.137.

Mai 2017 / Leukemia – écrit par Stickel N, Hanke K, Marschner D, Prinz G, Köhler M, Melchinger W, Pfeifer D, Schmitt-Graeff A, Brummer T, Heine A, Brossart P, Wolf D, von Bubnoff N, Finke J, Duyster J, Ferrara J, Salzer U, Zeiser R.

Pour plus d’informations : https://www.ncbi.nlm.nih.gov/pubmed/28484267

An update on chemical pharmacotherapy options for the prevention of kidney transplant rejection with a focus on costimulation blockade

Résumé
The introduction of calcineurin inhibitors (CNI) has greatly improved graft survival in the past three decades. However, long-term graft survival is still limited due to chronic allograft injury and side-effects of immunosuppressive medication.
The present overview gives an update on pharmacotherapeutic strategies after kidney transplantation. The main focus is on CNI-sparing regimens using co-stimulatory blockade and on new substances on the horizone.

Mots clefs : Kidney transplantation, immunosuppressive regimens, calcineurin inhibitors, belatacept, mammalian target of rapamycin inhibitors, chronic antibody-mediated rejection

Avril 2017 / Expert Opinion on Pharmacotheraphy – Kälbe F, Schaier M, Schäffer S, Süsal C, Zeier M, Sommerer C et Morath C

Pour plus d’informations: http://www.tandfonline.com/doi/full/10.1080/14656566.2017.1323876