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Iglesias M, Brennan DC, Larsen CP, Raimondi G. Targeting inflammation and immune activation to improve CTLA4-Ig-based modulation of transplant rejection. Front Immunol 2022; 13:926648. [PMID: 36119093 PMCID: PMC9478663 DOI: 10.3389/fimmu.2022.926648] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/09/2022] [Indexed: 11/16/2022] Open
Abstract
For the last few decades, Calcineurin inhibitors (CNI)-based therapy has been the pillar of immunosuppression for prevention of organ transplant rejection. However, despite exerting effective control of acute rejection in the first year post-transplant, prolonged CNI use is associated with significant side effects and is not well suited for long term allograft survival. The implementation of Costimulation Blockade (CoB) therapies, based on the interruption of T cell costimulatory signals as strategy to control allo-responses, has proven potential for better management of transplant recipients compared to CNI-based therapies. The use of the biologic cytotoxic T-lymphocyte associated protein 4 (CTLA4)-Ig is the most successful approach to date in this arena. Following evaluation of the BENEFIT trials, Belatacept, a high-affinity version of CTLA4-Ig, has been FDA approved for use in kidney transplant recipients. Despite its benefits, the use of CTLA4-Ig as a monotherapy has proved to be insufficient to induce long-term allograft acceptance in several settings. Multiple studies have demonstrated that events that induce an acute inflammatory response with the consequent release of proinflammatory cytokines, and an abundance of allograft-reactive memory cells in the recipient, can prevent the induction of or break established immunomodulation induced with CoB regimens. This review highlights advances in our understanding of the factors and mechanisms that limit CoB regimens efficacy. We also discuss recent successes in experimentally designing complementary therapies that favor CTLA4-Ig effect, affording a better control of transplant rejection and supporting their clinical applicability.
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Affiliation(s)
- Marcos Iglesias
- Vascularized and Composite Allotransplantation (VCA) Laboratory, Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- *Correspondence: Giorgio Raimondi, ; Marcos Iglesias,
| | - Daniel C. Brennan
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Christian P. Larsen
- Department of Surgery, Emory University School of Medicine, Atlanta, GA, United States
| | - Giorgio Raimondi
- Vascularized and Composite Allotransplantation (VCA) Laboratory, Department of Plastic and Reconstructive Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, United States
- *Correspondence: Giorgio Raimondi, ; Marcos Iglesias,
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2
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Swanson KJ. Kidney disease in non-kidney solid organ transplantation. World J Transplant 2022; 12:231-249. [PMID: 36159075 PMCID: PMC9453292 DOI: 10.5500/wjt.v12.i8.231] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2022] [Revised: 04/07/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023] Open
Abstract
Kidney disease after non-kidney solid organ transplantation (NKSOT) is a common post-transplant complication associated with deleterious outcomes. Kidney disease, both acute kidney injury and chronic kidney disease (CKD) alike, emanates from multifactorial, summative pre-, peri- and post-transplant events. Several factors leading to kidney disease are shared amongst solid organ transplantation in addition to distinct mechanisms unique to individual transplant types. The aim of this review is to summarize the current literature describing kidney disease in NKSOT. We conducted a narrative review of pertinent studies on the subject, limiting our search to full text studies in the English language. Kidney disease after NKSOT is prevalent, particularly in intestinal and lung transplantation. Management strategies in the peri-operative and post-transplant periods including proteinuria management, calcineurin-inhibitor minimization/ sparing approaches, and nephrology referral can counteract CKD progression and/or aid in subsequent kidney after solid organ transplantation. Kidney disease after NKSOT is an important consideration in organ allocation practices, ethics of transplantation. Kidney disease after SOT is an incipient condition demanding further inquiry. While some truths have been revealed about this chronic disease, as we have aimed to describe in this review, continued multidisciplinary efforts are needed more than ever to combat this threat to patient and allograft survival.
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Affiliation(s)
- Kurtis J Swanson
- Division of Nephrology and Hypertension, University of Minnesota, Minneapolis, MN 55414, United States
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3
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Nelson J, Alvey N, Bowman L, Schulte J, Segovia M, McDermott J, Te HS, Kapila N, Levine DJ, Gottlieb RL, Oberholzer J, Campara M. Consensus recommendations for use of maintenance immunosuppression in solid organ transplantation: Endorsed by the American College of Clinical Pharmacy, American Society of Transplantation, and the International Society for Heart and Lung Transplantation. Pharmacotherapy 2022; 42:599-633. [DOI: 10.1002/phar.2716] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/29/2022] [Accepted: 04/08/2022] [Indexed: 12/17/2022]
Affiliation(s)
- Joelle Nelson
- Department of Pharmacotherapy and Pharmacy Services University Health San Antonio Texas USA
- Pharmacotherapy Education and Research Center University of Texas Health San Antonio San Antonio Texas USA
- Department of Pharmacy, Pharmacotherapy Division, College of Pharmacy The University of Texas at Austin Austin Texas USA
| | - Nicole Alvey
- Department of Pharmacy Rush University Medical Center Chicago Illinois USA
- Science and Pharmacy Roosevelt University College of Health Schaumburg Illinois USA
| | - Lyndsey Bowman
- Department of Pharmacy Tampa General Hospital Tampa Florida USA
| | - Jamie Schulte
- Department of Pharmacy Services Thomas Jefferson University Hospital Philadelphia Pennsylvania USA
| | | | - Jennifer McDermott
- Richard DeVos Heart and Lung Transplant Program, Spectrum Health Grand Rapids Michigan USA
- Department of Medicine, Michigan State University College of Human Medicine Grand Rapids Michigan USA
| | - Helen S. Te
- Liver Transplantation, Center for Liver Diseases, Department of Medicine University of Chicago Medical Center Chicago Illinois USA
| | - Nikhil Kapila
- Department of Transplant Hepatology Duke University Hospital Durham North Carolina USA
| | - Deborah Jo Levine
- Division of Critical Care Medicine, Department of Medicine The University of Texas Health Science Center at San Antonio San Antonio Texas USA
| | - Robert L. Gottlieb
- Baylor University Medical Center and Baylor Scott and White Research Institute Dallas Texas USA
| | - Jose Oberholzer
- Department of Surgery/Division of Transplantation University of Virginia Charlottesville Virginia USA
| | - Maya Campara
- Department of Surgery University of Illinois Chicago Chicago Illinois USA
- Department of Pharmacy Practice University of Illinois Chicago Chicago Illinois USA
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Belatacept Conversion in Kidney After Liver Transplantation. Transplant Direct 2021; 7:e780. [PMID: 34712780 PMCID: PMC8547931 DOI: 10.1097/txd.0000000000001229] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/01/2022] Open
Abstract
Background. Costimulatory blockade with belatacept has demonstrated long-term benefits in renal transplantation, but de novo use in liver transplant recipients has resulted in increased rejection, graft loss, and death. However, belatacept conversion as a calcineurin inhibitor (CNI) avoidance strategy has not been studied and may be of benefit in liver transplantation where CNI-induced renal dysfunction and toxicity are barriers to improved outcomes. Methods. Using clinical data extracted from our institutional medical record, we report on 8 patients who underwent kidney after liver transplantation and were treated with belatacept-based immunosuppression and transient CNI therapy. Results. All patients tolerated belatacept therapy without any patient deaths or graft losses. No episodes of rejection, de novo donor-specific antibody formation, or major systemic infections were observed, and all patients demonstrated preserved liver and excellent renal allograft function. Patients received belatacept for a median duration of 13.2 mo, and at a median follow-up of 15.9 mo post–kidney transplant, 6 of 8 patients continued on belatacept with 3 completely off and 3 poised to transition off CNI. Conclusions. These findings are the first evidence that in liver transplant recipients requiring subsequent kidney transplantation, belatacept-based therapy can potentially facilitate CNI-free maintenance immunosuppression. This supports the possibility of belatacept conversion in stand-alone liver transplant recipients as a viable method of CNI avoidance.
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Nachiappan A, Fallah T, Willert R, Chojnowski D, Deshpande C, Courtwright A. Severe Acute Cellular Rejection With High-Grade Lymphocytic Bronchiolitis Following Transition from Tacrolimus to Belatacept in a Lung Transplantation Recipient: A Case Report. Transplant Proc 2021; 54:165-168. [PMID: 34756649 DOI: 10.1016/j.transproceed.2021.08.051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/19/2021] [Accepted: 08/30/2021] [Indexed: 12/01/2022]
Abstract
This case report describes a lung transplantation recipient who developed severe acute cellular rejection with high-grade lymphocytic bronchiolitis after transition to a calcineurin-free regimen using belatacept. A 53-year-old man who had undergone lung transplantation 3 years prior developed progressive chronic kidney disease related to tacrolimus. He was transitioned off tacrolimus to belatacept to prevent the need for dialysis. He was admitted 2 months later with acute hypoxemic respiratory failure. Video-assisted thoracic surgery biopsy showed acute fibrinous and organizing pneumonia and A4B2 rejection. He subsequently developed chronic lung allograft dysfunction. This case illustrates the potential increased risk of acute rejection associated with belatacept maintenance immunosuppression.
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Affiliation(s)
- Arun Nachiappan
- Department of Radiology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Tara Fallah
- Advanced Lung Disease and Lung Transplantation, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Rebecca Willert
- Advanced Lung Disease and Lung Transplantation, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Donna Chojnowski
- Advanced Lung Disease and Lung Transplantation, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Charuhas Deshpande
- Department of Pathology, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Andrew Courtwright
- Advanced Lung Disease and Lung Transplantation, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania, USA.
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6
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Ding M, He Y, Zhang S, Guo W. Recent Advances in Costimulatory Blockade to Induce Immune Tolerance in Liver Transplantation. Front Immunol 2021; 12:537079. [PMID: 33732228 PMCID: PMC7959747 DOI: 10.3389/fimmu.2021.537079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 01/12/2021] [Indexed: 01/25/2023] Open
Abstract
Liver transplantation is an effective therapy for end-stage liver disease. However, most postoperative patients must take immunosuppressive drugs to prevent organ rejection. Interestingly, some transplant recipients have normal liver function and do not experience organ rejection after the withdrawal of immunosuppressive agents. This phenomenon, called immune tolerance, is the ultimate goal in clinical transplantation. Costimulatory molecules play important roles in T cell-mediated immune responses and the maintenance of T cell tolerance. Blocking costimulatory pathways can alter T cell responses and prolong graft survival. Better understanding of the roles of costimulatory molecules has facilitated the use of costimulatory blockade to effectively induce immune tolerance in animal transplantation models. In this article, we review the state of the art in costimulatory pathway blockade for the induction of immune tolerance in transplantation and its potential application prospects for liver transplantation.
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Affiliation(s)
- Mingjie Ding
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, China.,Zhengzhou Key Laboratory of Hepatobiliary & Pancreatic Diseases and Organ Transplantation Medicine, Zhengzhou, China
| | - Yuting He
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, China
| | - Shuijun Zhang
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, China.,Zhengzhou Key Laboratory of Hepatobiliary & Pancreatic Diseases and Organ Transplantation Medicine, Zhengzhou, China
| | - Wenzhi Guo
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, China.,Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, Zhengzhou, China.,Zhengzhou Key Laboratory of Hepatobiliary & Pancreatic Diseases and Organ Transplantation Medicine, Zhengzhou, China
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7
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Belatacept in Solid Organ Transplant: Review of Current Literature Across Transplant Types. Transplantation 2019; 102:1440-1452. [PMID: 29787522 DOI: 10.1097/tp.0000000000002291] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Calcineurin inhibitors (CNIs) have been the backbone immunosuppressant for solid organ transplant recipients for decades. Long-term use of CNIs unfortunately is associated with multiple toxicities, with the biggest concern being CNI-induced nephrotoxicity. Belatacept is a novel agent approved for maintenance immunosuppression in renal transplant recipients. In the kidney transplant literature, it has shown promise as being an alternative agent by preserving renal function and having a minimal adverse effect profile. There are emerging studies of its use in other organ groups, particularly liver transplantation, as well as using with other alternative immunosuppressive strategies. The purpose of this review is to analyze the current literature of belatacept use in solid organ transplantation and discuss its use in current practice.
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8
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CTLA4Ig Improves Murine iTreg Induction via TGF β and Suppressor Function In Vitro. J Immunol Res 2018; 2018:2484825. [PMID: 30057914 PMCID: PMC6051081 DOI: 10.1155/2018/2484825] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Revised: 04/26/2018] [Accepted: 05/29/2018] [Indexed: 12/30/2022] Open
Abstract
Blockade of the CD28:CD80/86 costimulatory pathway has been shown to be potent in blocking T cell activation in vitro and in vivo. The costimulation blocker CTLA4Ig has been approved for the treatment of autoimmune diseases and transplant rejection. The therapeutic application of regulatory T cells (Tregs) has recently gained much attention for its potential of improving allograft survival. However, neither costimulation blockade with CTLA4Ig nor Treg therapy induces robust tolerance on its own. Combining CTLA4Ig with Treg therapy would be an attractive approach for minimizing immunosuppression or for possibly achieving tolerance. However, since the CD28 pathway is more complex than initially thought, the question arose whether blocking CD80/86 would inadvertently impact immunological tolerance by interfering with Treg generation and function. We therefore wanted to investigate the compatibility of CTLA4Ig with regulatory T cells by evaluating direct effects of CTLA4Ig on murine Treg generation and function in vitro. For generation of polyclonal-induced Tregs, we utilized an APC-free in vitro system and added titrated doses of CTLA4Ig at different time points. Phenotypical characterization by flow cytometry and functional characterization in suppressor assays did not reveal negative effects by CTLA4Ig. The costimulation blocker CTLA4Ig does not impair but rather improves murine iTreg generation and suppressor function in vitro.
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9
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Schwarz C, Mahr B, Muckenhuber M, Wekerle T. Belatacept/CTLA4Ig: an update and critical appraisal of preclinical and clinical results. Expert Rev Clin Immunol 2018; 14:583-592. [PMID: 29874474 DOI: 10.1080/1744666x.2018.1485489] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
INTRODUCTION The B7/CD28/CTLA4 signaling cascade is the most thoroughly studied costimulatory pathway and blockade with CTLA4Ig (abatacept) or its derivative belatacept has emerged as a valuable option for pharmacologic immune modulation. Several clinical studies have ultimately led to the approval of belatacept for immunosuppression in kidney transplant recipients. Areas covered: This review will discuss the immunological background of costimulation blockade and recent preclinical data and clinical results of CTLA4Ig/belatacept. Expert commentary: The development of belatacept is a major advance in clinical transplantation. However, in spite of promising results in preclinical and clinical trials, clinical use remains limited at present, in part due to increased rates of acute rejection. Recent efforts showing encouraging progress in refining such protocols might be a step toward harnessing the full potential of costimulation blockade-based immunosuppression.
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Affiliation(s)
- Christoph Schwarz
- a Division of General Surgery, Department of Surgery , Medical University of Vienna , Vienna , Austria.,b Section of Transplantation Immunology, Department of Surgery , Medical University of Vienna , Vienna , Austria
| | - Benedikt Mahr
- b Section of Transplantation Immunology, Department of Surgery , Medical University of Vienna , Vienna , Austria
| | - Moritz Muckenhuber
- b Section of Transplantation Immunology, Department of Surgery , Medical University of Vienna , Vienna , Austria
| | - Thomas Wekerle
- b Section of Transplantation Immunology, Department of Surgery , Medical University of Vienna , Vienna , Austria
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10
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Schwarz C, Unger L, Mahr B, Aumayr K, Regele H, Farkas AM, Hock K, Pilat N, Wekerle T. The Immunosuppressive Effect of CTLA4 Immunoglobulin Is Dependent on Regulatory T Cells at Low But Not High Doses. Am J Transplant 2016; 16:3404-3415. [PMID: 27184870 DOI: 10.1111/ajt.13872] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2015] [Revised: 04/18/2016] [Accepted: 05/09/2016] [Indexed: 01/25/2023]
Abstract
B7.1/2-targeted costimulation blockade (CTLA4 immunoglobulin [CTLA4-Ig]) is available for immunosuppression after kidney transplantation, but its potentially detrimental impact on regulatory T cells (Tregs) is of concern. We investigated the effects of CTLA4-Ig monotherapy in a fully mismatched heart transplant model (BALB/c onto C57BL/6). CTLA4-Ig was injected chronically (on days 0, 4, 14, and 28 and every 4 weeks thereafter) in dosing regimens paralleling clinical use, shown per mouse: low dose (LD), 0.25 mg (≈10 mg/kg body weight); high dose (HD), 1.25 mg (≈50 mg/kg body weight); and very high dose (VHD), 6.25 mg (≈250 mg/kg body weight). Chronic CTLA4-Ig therapy showed dose-dependent efficacy, with the LD regimen prolonging graft survival and with the HD and VHD regimens leading to >95% long-term graft survival and preserved histology. CTLA4-Ig's effect was immunosuppressive rather than tolerogenic because treatment cessation after ≈3 mo led to rejection. FoxP3-positive Tregs were reduced in naïve mice to a similar degree, independent of the CTLA4-Ig dose, but recovered to normal values in heart recipients under chronic CTLA4-Ig therapy. Treg depletion (anti-CD25) resulted in an impaired outcome under LD therapy but had no detectable effect under HD therapy. Consequently, the immunosuppressive effect of partially effective LD CTLA4-Ig therapy is impaired when Tregs are removed, whereas CTLA4-Ig monotherapy at higher doses effectively maintains graft survival independent of Tregs.
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Affiliation(s)
- C Schwarz
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - L Unger
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - B Mahr
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - K Aumayr
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - H Regele
- Clinical Institute of Pathology, Medical University of Vienna, Vienna, Austria
| | - A M Farkas
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - K Hock
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - N Pilat
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
| | - T Wekerle
- Section of Transplantation Immunology, Department of Surgery, Medical University of Vienna, Vienna, Austria
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Abstract
After transplantation of nonrenal solid organs, an acute decline in kidney function develops in the majority of patients. In addition, a significant number of nonrenal solid organ transplant recipients develop chronic kidney disease, and some develop end-stage renal disease, requiring renal replacement therapy. The incidence varies depending on the transplanted organ. Acute kidney injury after nonrenal solid organ transplantation is associated with prolonged length of stay, cost, increased risk of death, de novo chronic kidney disease, and end-stage renal disease. This overview focuses on the risk factors for posttransplant acute kidney injury after liver and heart transplantation, integrating discussion of proteinuria and chronic kidney disease with emphasis on pathogenesis, histopathology, and management including the use of mechanistic target of rapamycin inhibition and costimulatory blockade.
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Affiliation(s)
- Ana P Rossi
- 1 Division of Nephrology and Transplantation, Maine Medical Center, Portland, ME
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12
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Oldhafer F, Bock M, Falk CS, Vondran FWR. Immunological aspects of liver cell transplantation. World J Transplant 2016; 6:42-53. [PMID: 27011904 PMCID: PMC4801804 DOI: 10.5500/wjt.v6.i1.42] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/21/2015] [Accepted: 12/08/2015] [Indexed: 02/05/2023] Open
Abstract
Within the field of regenerative medicine, the liver is of major interest for adoption of regenerative strategies due to its well-known and unique regenerative capacity. Whereas therapeutic strategies such as liver resection and orthotopic liver transplantation (OLT) can be considered standards of care for the treatment of a variety of liver diseases, the concept of liver cell transplantation (LCTx) still awaits clinical breakthrough. Success of LCTx is hampered by insufficient engraftment/long-term acceptance of cellular allografts mainly due to rejection of transplanted cells. This is in contrast to the results achieved for OLT where long-term graft survival is observed on a regular basis and, hence, the liver has been deemed an immune-privileged organ. Immune responses induced by isolated hepatocytes apparently differ considerably from those observed following transplantation of solid organs and, thus, LCTx requires refined immunological strategies to improve its clinical outcome. In addition, clinical usage of LCTx but also related basic research efforts are hindered by the limited availability of high quality liver cells, strongly emphasizing the need for alternative cell sources. This review focuses on the various immunological aspects of LCTx summarizing data available not only for hepatocyte transplantation but also for transplantation of non-parenchymal liver cells and liver stem cells.
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