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Endothelial Infection with Cytomegalovirus in Xenotransplantation: Mechanisms, Immunological and Procoagulant Consequences

English title Endothelial Infection with Cytomegalovirus in Xenotransplantation: Mechanisms, Immunological and Procoagulant Consequences
Applicant Müller Nicolas
Number 130705
Funding scheme Project funding
Research institution Klinik für Infektionskrankheiten und Spitalhygiene Universitätsspital Zürich
Institution of higher education University of Zurich - ZH
Main discipline Immunology, Immunopathology
Start/End 01.04.2010 - 31.05.2013
Approved amount 288'000.00
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All Disciplines (2)

Discipline
Immunology, Immunopathology
Cellular Biology, Cytology

Keywords (10)

Endothelium; Transplantation; Cytomegalovirus; Coagulation; Inflammation; xenotransplantation; herpesvirus; infection; indirect effects; enodthelium

Lay Summary (German)

Lead
Lay summary
Die gezielte medikamentöse Unterdrückung unseres Immunsystems machte das Trans-plantieren von Organen oder Zellen von Mensch zu Mensch zu einer klinischen Realität. Im Jahre 2009 fanden sich in der Schweiz 996 Patienten auf der Warteliste für eine Organtransplantation, nur 466 erhielten ein Transplantat, 67 Patienten verstarben auf der Warteliste. Obwohl erfolgreich, bleibt diese häufig lebensrettende Therapie aufgrund einer Organknappheit vielen verwehrt. Die Diskrepanz zwischen Patienten auf der Warteliste und effektiv transplantierten Patienten ist in den letzten Jahren immer grösser geworden. Alternative Organersatzverfahren werden deshalb intensiv geprüft, unter anderem die Verpflanzung von Organen vom Schwein auf den Menschen (Xenotransplantation). Eine Schweinezucht würde Reserveorgane uneingeschränkt zur Verfügung stellen. Bevor die Xenotransplantation klinisch im Menschen getestet werden kann, müssen jedoch ethische, immunologische und physiologische Hürden überwunden werden. Für eine präklinische experimentelle Austestung der Xenotransplantation werden heute Schweineorgane in Primaten (Paviane) transplantiert. Primaten dienen aufgrund immunologischer und anatomischer Eigenschaften als Modell. Sowohl in der humanen Allotransplantation als auch im Xenomodell stellt die Reaktivierung von Zytomegalievirus (ZMV) die wichtigste infektiologische Komplikation dar. Es existieren überzeugende Daten, dass diese Reaktivierung von ZMV über die direkten infektbedingten Folgen hinaus auch eine Rolle bei akuten und chronischen Abstossungen spielt. Mögliche Mechanismen sind Veränderungen in der Expression von Oberflächenmarkern und Aufregulierung von major histocompatibility complex (MHC) Klasse II Molekülen. Bei der Transplantation solider Organe ist das Endothel der Gefässe im Transplantat der entscheidende Berührungspunkt zwischen dem Immunsystem des Empfängers und dem Transplantat. Wir konnten nachweisen, das humanes Zytomegalievirus im porzinen Endothel eine produktive Infektion etablieren kann. Das vorliegende Projekt untersucht die Hypothese, dass durch die Reaktivierung von ZMV Veränderungen des Endothels ausgelöst werden, die über spezifische zelluläre Interaktionen einen entzündlichen Prozess bewirken. Diese pro-inflammatorischen Vorgänge resultieren in einer direkten Schädigung des Endothels, Einwanderung von Zellen in das Transplantat, und führen schliesslich zu akuten bzw. chronischen Abstossungsreaktionen. Die Gerinnung kann aktiviert werden, da die Schutzmechanismen des Endothels beeinträchtigt werden. Nicht zuletzt untersuchen wir die molekularen Grundlagen, wie humanes Zytomegalovirus die porzine Zelle infizieren kann.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Efficiency of porcine endothelial cell infection with human cytomegalovirus depends on both virus tropism and endothelial cell vascular origin.
Millard Anne-Laure, Häberli Lea, Sinzger Christian, Ghielmetti Maddalena, Schneider Mårten K J, Bossart Walter, Seebach Jörg D, Mueller Nicolas J (2010), Efficiency of porcine endothelial cell infection with human cytomegalovirus depends on both virus tropism and endothelial cell vascular origin., in Xenotransplantation, 17(4), 274-87.
Can human viruses infect porcine xenografts?
Millard Anne Laure, Mueller Nicolas J (2010), Can human viruses infect porcine xenografts?, in Xenotransplantation, 17(1), 6-10.
Critical issues related to porcine xenograft exposure to human viruses: lessons from allotransplantation.
Millard Anne-Laure, Mueller Nicolas J (2010), Critical issues related to porcine xenograft exposure to human viruses: lessons from allotransplantation., in Current opinion in organ transplantation, 15(2), 230-5.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
12th day of clinical research, University Hospital Zurich 04.04.2013 Zurich
4th Swiss fundamental virology workshop 05.02.2013 Thun
10th day of clinical research 19.04.2012 Zürich
Third Swiss Workshop in Fundamental Virology 29.08.2011 Thun
13th International CMV / BetaHerpesvirus Workshop 14.05.2011 Nürnberg
SGAI meeting 17.03.2011 Lugano


Awards

Title Year
Scholarship award Gesellschaft für Virologie 2011

Associated projects

Number Title Start Funding scheme
103935 Islet Xenotransplantation in the pig-to-nonhuman primate model : evaluation of new immunosuppressive strategies and cross species infections 01.04.2005 Project funding
138376 Transgenic strategies to overcome cellular rejection in pig-to-human xenotransplantation 01.04.2012 Project funding
114020 Endothelial infection with Cytomegalovirus in xeno- and allotransplantation: Immunological and procoagulant consequences 01.12.2006 Project funding

Abstract

The recent success with reversal of diabetes using porcine islets cells in a nonhuman primate model has demonstrated the great potential of xenotransplantation. The limitless supply of cells or organs remains an important goal in transplantation. For solid organs, progress has been slower, despite the availability of genetically altered pigs. Besides immunological and physiological barriers, coagulation has emerged as a main obstacle and has prompted great efforts in deciphering the cross-species incompatibilities and in finding strategies to overcome them. The potential for xenogeneic infections has been a major concern. Much attention has been given to donor-derived infections, neglecting host-derived infection with potentially dire consequences for the graft.Infections represent a major cause of morbidity and mortality in transplantation. Not only do infections cause direct damage, but increasing evidence points to indirect effects such as vasculopathy and graft rejection. Together with ischemia/reperfusion injury and immunosuppressive drug toxicity, infections may lead to accelerated graft loss. Human cytomegalovirus (HCMV) is the most important pathogen posttransplant. After establishing life-long latent infection in immunocompetent hosts, it frequently reactivates in immunosuppressed transplant recipients and potentially triggers graft rejection. In pig-to-baboon preclinical xenotransplantation, porcine CMV was found to cause a consumptive coagulopathy in the recipient animal.The endothelium has emerged as a major compartment of immune regulation, coagulation control and inflammation. The resting endothelium maintains an anti-inflammatory and anti-coagulant state. Activation will result in inflammation and a pro-coagulant state. Being a necessary process in the context of infection or damage, this can be detrimental for a transplanted organ. The graft endothelium is in close contact with the circulating blood of the recipient, exposing it to various immune responses as well as to host-derived CMV infection.Our findings generated in a cross-species model illustrate the potential of CMV to profoundly disturb the delicate hemostasis maintained by the endothelium. We were able to convincingly demonstrate productive infection of HCMV in porcine endothelial cells. Long believed to be a very species-restricted infection, CMV was able to cross the species barrier despite its close evolution with the host. However, we did recognize differences in infectivity and cellular control of infection by apoptosis. Infected porcine endothelial cells (EC) showed an activated phenotype with upregulation of adhesion molecules and strongly increased adhesion of human leukocytes and release of porcine pro-inflammatory cytokines. We established the tools to study the role of suppressor of cytokine signaling proteins in the counter-regulation of pro-inflammatory cellular responses.Based on these findings, the goal of the present proposal is to deepen our understanding of the mechanisms to develop strategies to prevent graft injury mediated by pro-inflammatory and pro-coagulant responses to CMV infection. The following specific aims will be addressed:Aim #1:Study the molecular basis of HCMV entry and replication into porcine endothelial cellsAim #2: Examine immunological consequences of CMV-infected endothelial cellsAim #3: Investigate the interplay between coagulation and CMV infectionThe outlined experiments will improve our understanding of the CMV-induced mechanisms resulting in EC alterations, particularly HCMV infection in porcine EC, and will provide evidence for the potential of different interventional approaches. This knowledge may then help us to design better prophylactic or preemptive therapies in both the human allotransplantation setting, and in xenotransplantation. If xenotransplantation proceeds to the clinical stage, understanding the potential role of cross-species CMV infection will be crucial to guide clinical trials.
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