1
|
Zhou Q, Li T, Wang K, Zhang Q, Geng Z, Deng S, Cheng C, Wang Y. Current status of xenotransplantation research and the strategies for preventing xenograft rejection. Front Immunol 2022; 13:928173. [PMID: 35967435 PMCID: PMC9367636 DOI: 10.3389/fimmu.2022.928173] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Accepted: 07/07/2022] [Indexed: 12/13/2022] Open
Abstract
Transplantation is often the last resort for end-stage organ failures, e.g., kidney, liver, heart, lung, and pancreas. The shortage of donor organs is the main limiting factor for successful transplantation in humans. Except living donations, other alternatives are needed, e.g., xenotransplantation of pig organs. However, immune rejection remains the major challenge to overcome in xenotransplantation. There are three different xenogeneic types of rejections, based on the responses and mechanisms involved. It includes hyperacute rejection (HAR), delayed xenograft rejection (DXR) and chronic rejection. DXR, sometimes involves acute humoral xenograft rejection (AHR) and cellular xenograft rejection (CXR), which cannot be strictly distinguished from each other in pathological process. In this review, we comprehensively discussed the mechanism of these immunological rejections and summarized the strategies for preventing them, such as generation of gene knock out donors by different genome editing tools and the use of immunosuppressive regimens. We also addressed organ-specific barriers and challenges needed to pave the way for clinical xenotransplantation. Taken together, this information will benefit the current immunological research in the field of xenotransplantation.
Collapse
Affiliation(s)
- Qiao Zhou
- Department of Rheumatology and Immunology, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Clinical Immunology Translational Medicine Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China
| | - Ting Li
- Department of Rheumatology, Wenjiang District People’s Hospital, Chengdu, China
| | - Kaiwen Wang
- School of Medicine, Faculty of Medicine and Health, The University of Leeds, Leeds, United Kingdom
| | - Qi Zhang
- School of Medicine, University of Electronics and Technology of China, Chengdu, China
| | - Zhuowen Geng
- School of Medicine, Faculty of Medicine and Health, The University of Leeds, Leeds, United Kingdom
| | - Shaoping Deng
- Clinical Immunology Translational Medicine Key Laboratory of Sichuan Province, Sichuan Provincial People’s Hospital, University of Electronic Science and Technology of China, Chengdu, China
- Chinese Academy of Sciences Sichuan Translational Medicine Research Hospital, Chengdu, China
- Institute of Organ Transplantation, Sichuan Academy of Medical Science and Sichuan Provincial People’s Hospital, Chengdu, China
| | - Chunming Cheng
- Department of Radiation Oncology, James Comprehensive Cancer Center and College of Medicine at The Ohio State University, Columbus, OH, United States
- *Correspondence: Chunming Cheng, ; Yi Wang,
| | - Yi Wang
- Department of Critical Care Medicine, Sichuan Academy of Medical Science and Sichuan Provincial People's Hospital, Chengdu, China
- *Correspondence: Chunming Cheng, ; Yi Wang,
| |
Collapse
|
2
|
Ruggenenti P, Cravedi P, Gotti E, Plati A, Marasà M, Sandrini S, Bossini N, Citterio F, Minetti E, Montanaro D, Sabadini E, Tardanico R, Martinetti D, Gaspari F, Villa A, Perna A, Peraro F, Remuzzi G. Mycophenolate mofetil versus azathioprine in kidney transplant recipients on steroid-free, low-dose cyclosporine immunosuppression (ATHENA): A pragmatic randomized trial. PLoS Med 2021; 18:e1003668. [PMID: 34166370 PMCID: PMC8224852 DOI: 10.1371/journal.pmed.1003668] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 05/23/2021] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND We compared protection of mycophenolate mofetil (MMF) and azathioprine (AZA) against acute cellular rejection (ACR) and chronic allograft nephropathy (CAN) in kidney transplant recipients on steroid-free, low-dose cyclosporine (CsA) microemulsion maintenance immunosuppression. METHODS AND FINDINGS ATHENA, a pragmatic, prospective, multicenter trial conducted by 6 Italian transplant centers, compared the outcomes of 233 consenting recipients of a first deceased donor kidney transplant induced with low-dose thymoglobulin and basiliximab and randomized to MMF (750 mg twice/day, n = 119) or AZA (75 to 125 mg/day, n = 114) added-on maintenance low-dose CsA microemulsion and 1-week steroid. In patients without acute clinical or subclinical rejections, CsA dose was progressively halved. Primary endpoint was biopsy-proven CAN. Analysis was by intention to treat. Participants were included between June 2007 and July 2012 and followed up to August 2016. Between-group donor and recipient characteristics, donor/recipient mismatches, and follow-up CsA blood levels were similar. During a median (interquartile range (IQR)) follow-up of 47.7 (44.2 to 48.9) months, 29 of 87 biopsied patients on MMF (33.3%) versus 31 of 88 on AZA (35.2%) developed CAN (hazard ratio (HR) [95% confidence interval (CI)]: 1.147 (0.691 to 1.904, p = 0.595). Twenty and 21 patients on MMF versus 34 and 14 on AZA had clinical [HR (95% CI): 0.58 (0.34 to 1.02); p = 0.057) or biopsy-proven subclinical [HR (95% CI): 1.49 (0.76 to 2.92); p = 0.249] ACR, respectively. Combined events [HR (95% CI): 0.85 (0.56 to 1.29); p = 0.438], patient and graft survival, delayed graft function (DGF), 3-year glomerular filtration rate (GFR) [53.8 (40.6;65.7) versus 49.8 (36.8;62.5) mL/min/1.73 m2, p = 0.50], and adverse events (AEs) were not significantly different between groups. Chronicity scores other than CAN predict long-term graft outcome. Study limitations include small sample size and unblinded design. CONCLUSIONS In this study, we found that in deceased donor kidney transplant recipients on low-dose CsA and no steroids, MMF had no significant benefits over AZA. This finding suggests that AZA, due to its lower costs, could safely replace MMF in combination with minimized immunosuppression. TRIAL REGISTRATION ClinicalTrials.gov NCT00494741; EUDRACT 2006-005604-14.
Collapse
Affiliation(s)
- Piero Ruggenenti
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
- Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Paolo Cravedi
- Division of Nephrology, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Eliana Gotti
- Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Annarita Plati
- Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Maddalena Marasà
- Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Silvio Sandrini
- Unit of Nephrology, ASST degli Spedali Civili di Brescia, Brescia, Italy
| | - Nicola Bossini
- Unit of Nephrology, ASST degli Spedali Civili di Brescia, Brescia, Italy
| | - Franco Citterio
- Unit of Kidney Transplantation, Fondazione Policlinico Universitario Agostino Gemelli IRCCS, Roma, Italy
| | - Enrico Minetti
- Unit of Nephrology, ASST Grande Ospedale Metropolitano Niguarda, Milano, Italy
| | - Domenico Montanaro
- SOC di Nefrologia, Dialisi e Trapianto Renale della Azienda Ospedaliero Universitaria “S. Maria della Misericordia,” Udine, Italy
| | - Ettore Sabadini
- Unit of Nephrology and Dialysis, ASST Papa Giovanni XXIII, Bergamo, Italy
| | - Regina Tardanico
- Unit of Nephrology, ASST degli Spedali Civili di Brescia, Brescia, Italy
| | - Davide Martinetti
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Flavio Gaspari
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Alessandro Villa
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Annalisa Perna
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Francesco Peraro
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
| | - Giuseppe Remuzzi
- Istituto di Ricerche Farmacologiche Mario Negri IRCCS, Bergamo, Italy
- * E-mail:
| |
Collapse
|
3
|
Brown K, Nowocin AK, Meader L, Edwards LA, Smith RA, Wong W. Immunotoxin Against a Donor MHC Class II Molecule Induces Indefinite Survival of Murine Kidney Allografts. Am J Transplant 2016; 16:1129-38. [PMID: 26799449 PMCID: PMC4988511 DOI: 10.1111/ajt.13584] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Revised: 10/12/2015] [Accepted: 10/14/2015] [Indexed: 01/25/2023]
Abstract
Rejection of donor organs depends on the trafficking of donor passenger leukocytes to the secondary lymphoid organs of the recipient to elicit an immune response via the direct antigen presentation pathway. Therefore, the depletion of passenger leukocytes may be clinically applicable as a strategy to improve graft survival. Because major histocompatibility complex (MHC) class II(+) cells are most efficient at inducing immune responses, selective depletion of this population from donor grafts may dampen the alloimmune response and prolong graft survival. In a fully MHC mismatched mouse kidney allograft model, we describe the synthesis of an immunotoxin, consisting of the F(ab')2 fragment of a monoclonal antibody against the donor MHC class II molecule I-A(k) conjugated with the plant-derived ribosomal inactivating protein gelonin. This anti-I-A(k) gelonin immunotoxin depletes I-A(k) expressing cells specifically in vitro and in vivo. When given to recipients of kidney allografts, it resulted in indefinite graft survival with normal graft function, presence of Foxp3(+) cells within donor grafts, diminished donor-specific antibody formation, and delayed rejection of subsequent donor-type skin grafts. Strategies aimed at the donor arm of the immune system using agents such as immunotoxins may be a useful adjuvant to existing recipient-orientated immunosuppression.
Collapse
Affiliation(s)
- K. Brown
- Medical Research Council (MRC) Centre for TransplantationSchool of Medicine at Guy's, King's, and St. Thomas' HospitalsKing's College LondonLondonUK
| | - A. K. Nowocin
- Medical Research Council (MRC) Centre for TransplantationSchool of Medicine at Guy's, King's, and St. Thomas' HospitalsKing's College LondonLondonUK
| | | | - L. A. Edwards
- Medical Research Council (MRC) Centre for TransplantationSchool of Medicine at Guy's, King's, and St. Thomas' HospitalsKing's College LondonLondonUK
| | - R. A. Smith
- Medical Research Council (MRC) Centre for TransplantationSchool of Medicine at Guy's, King's, and St. Thomas' HospitalsKing's College LondonLondonUK
| | - W. Wong
- Medical Research Council (MRC) Centre for TransplantationSchool of Medicine at Guy's, King's, and St. Thomas' HospitalsKing's College LondonLondonUK
| |
Collapse
|
4
|
Recombinant anti-monkey CD3 immunotoxin depletes peripheral lymph node T lymphocytes more effectively than rabbit anti-thymocyte globulin in naïve baboons. Transpl Immunol 2013; 29:60-3. [PMID: 24157659 DOI: 10.1016/j.trim.2013.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 10/10/2013] [Accepted: 10/14/2013] [Indexed: 12/19/2022]
Abstract
T cell depletion is an important procedure for both experimental and therapeutic immune modulation. Rabbit anti-thymocyte globulin (ATG), which is a commonly used T cell depletion antibody in clinical organ and cell transplantation protocols, is effective in temporarily depleting peripheral blood T lymphocytes but only moderately effective in depleting peripheral lymph node T cells which comprise the majority of T lymphocytes. A recombinant anti-CD3 immunotoxin, A-dmDT390-scfbDb (C207), has been developed and shown in an initial study to retain the lymph node depleting properties of conjugated CD3 immunotoxin. This agent could potentially be used synergistically with or as a replacement for rabbit ATG in preclinical primate models of transplantation. We directly compared the peripheral blood and lymph node depleting abilities of this recombinant anti-CD3 immunotoxin and rabbit ATG in naïve animals at clinically tolerated doses. Baboons were treated with a full course of either rabbit ATG (n=2) or CD3 immunotoxin (n=3). Peripheral blood and lymph node T lymphocytes were measured before and following treatment. Peripheral blood CD3+ cells fell below 100cells/μL in every animal. In the two animals receiving ATG, CD3+ cells represented 53% and 68% of lymph node cells two days following a full course of rabbit ATG. In contrast, CD3+ cells represented 3%, 5%, and 38% in lymph nodes following a full course of CD3-IT. Thus, recombinant anti-monkey CD3 immunotoxin showed improved peripheral lymph node T lymphocyte depletion to rabbit ATG and spared other immune cells.
Collapse
|
5
|
Bugelski PJ, Martin PL. Concordance of preclinical and clinical pharmacology and toxicology of therapeutic monoclonal antibodies and fusion proteins: cell surface targets. Br J Pharmacol 2012; 166:823-46. [PMID: 22168282 PMCID: PMC3417412 DOI: 10.1111/j.1476-5381.2011.01811.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2011] [Revised: 10/14/2011] [Accepted: 11/28/2011] [Indexed: 12/20/2022] Open
Abstract
Monoclonal antibodies (mAbs) and fusion proteins directed towards cell surface targets make an important contribution to the treatment of disease. The purpose of this review was to correlate the clinical and preclinical data on the 15 currently approved mAbs and fusion proteins targeted to the cell surface. The principal sources used to gather data were: the peer reviewed Literature; European Medicines Agency 'Scientific Discussions'; and the US Food and Drug Administration 'Pharmacology/Toxicology Reviews' and package inserts (United States Prescribing Information). Data on the 15 approved biopharmaceuticals were included: abatacept; abciximab; alefacept; alemtuzumab; basiliximab; cetuximab; daclizumab; efalizumab; ipilimumab; muromonab; natalizumab; panitumumab; rituximab; tocilizumab; and trastuzumab. For statistical analysis of concordance, data from these 15 were combined with data on the approved mAbs and fusion proteins directed towards soluble targets. Good concordance with human pharmacodynamics was found for mice receiving surrogates or non-human primates (NHPs) receiving the human pharmaceutical. In contrast, there was poor concordance for human pharmacodynamics in genetically deficient mice and for human adverse effects in all three test systems. No evidence that NHPs have superior predictive value was found.
Collapse
Affiliation(s)
- Peter J Bugelski
- Biologics Toxicology, Janssen Research & Development, division of Johnson & Johnson Pharmaceutical Research & Development, LLC, Radnor, PA 19087, USA
| | | |
Collapse
|
6
|
LaMattina JC, Mezrich JD, Hofmann RM, Foley DP, D'Alessandro AM, Sollinger HW, Pirsch JD. Alemtuzumab as compared to alternative contemporary induction regimens. Transpl Int 2012; 25:518-26. [PMID: 22394259 DOI: 10.1111/j.1432-2277.2012.01448.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Between 1 January 2002 and 31 December 2007, our center performed 1687 adult renal transplants. A retrospective analysis was performed to compare outcomes between patients receiving alemtuzumab (n = 632) and those receiving either basiliximab (n = 690) or thymoglobulin (n = 125). Patients receiving alemtuzumab were younger (49 vs. 51 years, P = 0.02), had fewer HLA matches (1.7 vs. 2.0, P < 0.0001), were more likely to have a cytomegalovirus (CMV) donor(+)/recipient(-) transplant (22% vs. 17%, P = 0.03) and were less likely to receive a living donor allograft (32% vs. 37%, P = 0.04). Alemtuzumab recipients were less likely to receive tacrolimus (35% vs. 47%, P < 0.0001). The 1-, 3-, and 5-year cumulative incidence of antibody-mediated rejection (AMR) in alemtuzumab-treated patients was 19%, 24%, and 27%, vs. 11%, 15%, and 18% for the other group (P < 0.0001). The 1-, 3-, and 5-year allograft survival in the alemtuzumab group was 88%, 75%, and 67%, vs. 91%, 82%, and 74% for the other group (P < 0.0001). Patient survival was equivalent. Alemtuzumab was an independent risk factor for living donor allograft loss (HR 2.0, P = 0.004), opportunistic infections (HR 1.3, P = 0.01), CMV infections (HR 1.6, P = 0.001), and AMR (HR 1.5, P = 0.002). The significantly worse graft survival in the alemtuzumab cohort may be due to the increased rates of AMR and infectious complications.
Collapse
Affiliation(s)
- John C LaMattina
- Division of Transplantation, University of Maryland School of Medicine, Baltimore, MD 53792, USA
| | | | | | | | | | | | | |
Collapse
|
7
|
SÁNCHEZ–FUEYO ALBERTO, STROM TERRYB. Immunologic basis of graft rejection and tolerance following transplantation of liver or other solid organs. Gastroenterology 2011; 140:51-64. [PMID: 21073873 PMCID: PMC3866688 DOI: 10.1053/j.gastro.2010.10.059] [Citation(s) in RCA: 163] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 10/24/2010] [Accepted: 10/26/2010] [Indexed: 12/13/2022]
Abstract
Transplantation of organs between genetically different individuals of the same species causes a T cell-mediated immune response that, if left unchecked, results in rejection and graft destruction. The potency of the alloimmune response is determined by the antigenic disparity that usually exists between donors and recipients and by intragraft expression of proinflammatory cytokines in the early period after transplantation. Studies in animal models have identified many molecules that, when targeted, inhibit T-cell activation. In addition, some of these studies have shown that certain immunologic interventions induce transplantation tolerance, a state in which the allograft is specifically accepted without the need for chronic immunosuppression. Tolerance is an important aspect of liver transplantation, because livers have a unique microenvironment that promotes tolerance rather than immunity. In contrast to the progress achieved in inducing tolerance in animal models, patients who receive transplanted organs still require nonspecific immunosuppressant drugs. The development of calcineurin inhibitors has reduced the acute rejection rate and improved short-term, but not long-term, graft survival. However, long-term use of immunosuppressive drugs leads to nephrotoxicity and metabolic disorders, as well as manifestations of overimmunosuppression such as opportunistic infections and cancers. The status of pharmacologic immunosuppression in the clinic is therefore not ideal. We review recently developed therapeutic strategies to promote tolerance to transplanted livers and other organs and diagnostic tools that might be used to identify patients most likely to accept or reject allografts.
Collapse
Affiliation(s)
- ALBERTO SÁNCHEZ–FUEYO
- Liver Transplant Unit, Hospital Clinic Barcelona, IDIBAPS, CIBEREHD, University of Barcelona, Barcelona, Spain
| | - TERRY B. STROM
- Transplant Institute, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| |
Collapse
|
8
|
Abstract
The thymus serves as the central organ of immunologic self-nonself discrimination. Thymocytes undergo both positive and negative selection, resulting in T cells with a broad range of reactivity to foreign antigens but with a lack of reactivity to self-antigens. The thymus is also the source of a subset of regulatory T cells that inhibit autoreactivity of T-cell clones that may escape negative selection. As a result of these functions, the thymus has been shown to be essential for the induction of tolerance in many rodent and large animal models. Proper donor antigen presentation in the thymus after bone marrow, dendritic cell, or solid organ transplantation has been shown to induce tolerance to allografts. The molecular mechanisms of positive and negative selection and regulatory T-cell development must be understood if a tolerance-inducing therapeutic intervention is to be designed effectively. In this brief and selective review, we present some of the known information on T-cell development and on the role of the thymus in experimental models of transplant tolerance. We also cite some clinical attempts to induce tolerance to allografts using pharmacologic or biologic interventions.
Collapse
|
9
|
Bringing transplantation tolerance into the clinic: lessons from the ITN and RISET for the Establishment of Tolerance consortia. Curr Opin Organ Transplant 2010; 15:441-8. [PMID: 20631613 DOI: 10.1097/mot.0b013e32833bd371] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
PURPOSE OF REVIEW Fundamental discoveries during the 1990s revolutionized our understanding of transplantation tolerance and our ability to create it in animal models. The Immune Tolerance Network (ITN) and Reprogramming the Immune System for the Establishment of Tolerance (RISET) consortia were created to leverage these advances and work towards the goal of achieving clinical tolerance in transplantation. This article highlights their accomplishments and challenges during the past decade. RECENT FINDINGS In interventional trials, renal allograft tolerance has been achieved using bone marrow transplantation with nonmyeloablative protocols to induce transient hematopoietic chimerism. Drug minimization in renal transplantation was achieved with Campath-1H induction therapy and also with cellular therapy using 'transplant acceptance inducing cells'. Successful drug withdrawal was accomplished in long-term stable pediatric liver transplant recipients. Finally, 'registry' trials of tolerant kidney recipients revealed a B-cell signature of tolerance, which will form the basis for future investigations of its use as a biomarker for drug minimization or withdrawal in selected patients. SUMMARY Although transplantation tolerance is not yet reliably achieved in a clinical setting, collaborative efforts, such as those of the ITN and RISET networks, are an effective means to synergize intellectual and financial resources to bring this goal closer to reality.
Collapse
|
10
|
Correlation of Donor Leukocyte Chimerism With Pulmonary Allograft Survival After Immunosuppressive Drug Withdrawal in a Porcine Model. Transplantation 2009; 87:1468-77. [DOI: 10.1097/tp.0b013e3181a3c4cb] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
11
|
Oluwole SF, Oluwole OO, Adeyeri AO, DePaz HA. New strategies in immune tolerance induction. Cell Biochem Biophys 2009; 40:27-48. [PMID: 15289641 DOI: 10.1385/cbb:40:3:27] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Induction of tolerance in clinical organ transplantation that will obviate the use of chronic immunosuppression and preserve host immune response to other antigens remains the goal of transplant research. The thymus plays a critical role in the ability of the immune system to discriminate between self- and nonself-antigens or harmful and harmless alloantigens. We now know that multiple factors determine how the immune system responds to a self-antigen or foreign antigen. These determinants include developmental stage of the host, stage of T-cell maturity, site of antigen encounter, type and maturity of antigen-presenting cells, and presence and type of costimulatory molecules. Our understanding of the mechanisms of T-cell interactions with peptide/ major histocompatibility complex in peripheral lymphoid organs has led to experiments that translate into peripheral T-cell tolerance. The induction of high-avidity peripheral alloreactive T cells in the early phase of organ transplantation makes it difficult to achieve long-term alloantigen-specific tolerance without the use of transient perioperative immunosuppression. Therefore, protocols that induce robust tolerance in rodent and nonhuman primate models involve the use of donor antigen combined with a short course of perioperative immunosuppression. These studies suggest that the underlying mechanisms of peripheral tolerance include deletion, anergy, immune deviation, and regulatory T cells. This review focuses on recent advances in tolerance induction in experimental animal models and discusses their relevance to the development of protocols for the induction and maintenance of clinical transplant tolerance.
Collapse
Affiliation(s)
- Soji F Oluwole
- Department of Surgery, Columbia University, College of Physicians and Surgeons, New York, NY, USA.
| | | | | | | |
Collapse
|
12
|
Tolerance Induction in a Large-Animal Model Using Total Lymphoid Irradiation and Intrathymic Bone Marrow. Transplantation 2008; 86:1830-6. [DOI: 10.1097/tp.0b013e3181910e67] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
13
|
|
14
|
Donor bone marrow transplantation as an approach to tolerance induction for clinical kidney transplantation. Curr Opin Organ Transplant 2007. [DOI: 10.1097/mot.0b013e3282f1fc01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
15
|
Abstract
BACKGROUND The use of alemtuzumab for induction therapy in kidney transplantation has been increasing. Herein is a report of graft outcomes associated with alemtuzumab induction from the Organ Procurement and Transplantation Network/United Network for Organ Sharing database. METHODS A total of 14,362 deceased donor kidney transplants from 2003 to 2004 received no induction (n=4,364), antithymocyte globulin (ATG; n=4,930), interleukin-2 receptor antagonists (IL-2RA; n=4,378), or alemtuzumab (n=690). Acute rejection within the initial hospitalization, 6 months, and 1 year; graft survival; and rejection-free survival were examined. Graft and rejection-free survival of alemtuzumab recipients maintained with tacrolimus (FK) or cyclosporine (CSA), mycophenolate mofetil (MMF), and steroids versus no calcineurin inhibitors (CNI), MMF, and steroids were compared. RESULTS Alemtuzumab recipients had less acute rejection during the initial hospitalization (2.3%) than no induction, ATG, and IL-2RA (7.6%, 3.4%, and 4.8%, respectively; P<0.001). There was increased acute rejection at 6 months and 1 year with alemtuzumab (14.5% and 19.2%) compared to no induction (12.7% and 14.8%, P<0.001), ATG (8.2% and 10.2%, P<0.001), and IL-2RA (11.1% and 13.0%, P<0.001) with no difference in adjusted relative risk for graft loss. Alemtuzumab recipients receiving FK or CSA, MMF, and steroids had increased graft (FK/MMF/steroids, P<0.001, CSA/MMF/steroids, P=0.007) and rejection-free survival (FK/MMF/steroids, P<0.001, CSA/MMF/steroids, P=0.006) over 24 months compared to no CNI, MMF, and steroids. CONCLUSIONS Despite reduced early rejection, acute rejection rates at 6 months and 1 year with alemtuzumab induction exceeded other forms of induction therapy. Maintenance with CNI-based immunosuppression may improve graft and rejection-free survival compared to CNI-free regimens among alemtuzumab recipients.
Collapse
|
16
|
Magliocca JF, Knechtle SJ. The evolving role of alemtuzumab (Campath-1H) for immunosuppressive therapy in organ transplantation. Transpl Int 2006; 19:705-14. [PMID: 16918530 DOI: 10.1111/j.1432-2277.2006.00343.x] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Alemtuzumab is a monoclonal anti-CD52 antibody, which has been used extensively off label in solid organ transplantation. Its primary use has been as an induction agent at the time of organ transplantation, although there is limited experience using it to treat steroid-resistant rejection. Prolonged lymphocyte depletion can be expected following alemtuzumab treatment even with one dose of 30 mg intravenously. The nature and kinetics of lymphocyte repopulation depend on the maintenance immunosuppression being administered. In comparison with Thymoglobulin, a polyclonal depleting antibody preparation, alemtuzumab offers significant practical benefits with lower cost, fewer side effects in administration, and no specific issues with i.v. access. The risks and benefits of depleting induction agents, such as alemtuzumab, are compared with nondepleting agents, such as anti-CD25 induction therapy. While the majority of experience in solid organ transplantation has been in kidney transplantation, there is more limited experience in liver, pancreas, islet, small bowel, and lung transplantation. We herein review some of the lessons learned from clinical experience to date in solid organ transplantation using alemtuzumab as an immunosuppressant.
Collapse
Affiliation(s)
- Joseph F Magliocca
- Department of Surgery, Division of Organ Transplantation, University of Wisconsin School of Medicine and Public Health, Madison, WI 53792-7375, USA
| | | |
Collapse
|
17
|
Abstract
Humans are protected from a daily onslaught of pathogenic organisms by an immune system that provides multiple layers of protection. Until solid organ transplantation became technically feasible in the early twentieth century, this constant state of surveillance for foreign cells that are associated with the immune response mostly was viewed as advantageous. Unfortunately for patients who have end-stage failure of heart, lungs, kidney, liver, and pancreas, the immune system is incapable of distinguishing between the presence of beneficial foreign tissue and harmful foreign pathogens; it mounts an effective attack against both. Improving our understanding of the factors that initiate and perpetuate the alloimmune response will result in the development of more refined and better tolerated immunosuppressive strategies.
Collapse
Affiliation(s)
- Douglas A Hale
- Transplantation Branch, National Institute of Diabetes & Digestive & Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
| |
Collapse
|
18
|
Chatenoud L. CD3-specific antibodies as promising tools to aim at immune tolerance in the clinic. Int Rev Immunol 2006; 25:215-33. [PMID: 16818372 DOI: 10.1080/08830180600743032] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Currently, therapies applied in transplantation and autoimmunity are essentially based on the use of immunosuppressants. These agents depress all immune responses and expose individuals to the recurrence of the pathogenic immune process once they are withdrawn, thus necessitating a chronic administration leading to the risk of recurrent infections and increased frequency of tumors. At variance, CD3 monoclonal antibodies appear unique in their capacity to induce immunological tolerance that is an antigen-specific unresponsiveness in the absence of chronic immunosuppression. This has been well-established in experimental models, and recent data show successful clinical translation using humanized anti-CD3 antibodies. The aim of this brief review is to discuss the main characteristics of these very promising tools and to present the experimental and clinical results arguing for their unique tolerogenic ability.
Collapse
Affiliation(s)
- Lucienne Chatenoud
- Université René Descartes Paris 5, Hôpital Necker Enfants Malades, Paris, France.
| |
Collapse
|
19
|
Fechner JH, Haustein SV, Knechtle SJ. Immunosuppression in nonhuman primates. Transplant Rev (Orlando) 2006. [DOI: 10.1016/j.trre.2006.06.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
20
|
Kean LS, Gangappa S, Pearson TC, Larsen CP. Transplant tolerance in non-human primates: progress, current challenges and unmet needs. Am J Transplant 2006; 6:884-93. [PMID: 16611324 DOI: 10.1111/j.1600-6143.2006.01260.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Given the significant morbidity associated with current post-transplant immunosuppressive regimens, induction of immune tolerance continues to be an important goal of clinical organ transplantation. While many strategies for inducing tolerance have been successfully applied in murine models, significant barriers are faced when translating these approaches to the clinic. This has necessitated pre-clinical studies in the more closely related model system, the non-human primates (NHP). In this review, we will discuss the four most prominent strategies for inducing transplantation tolerance and highlight their relative success and shortcomings in NHP. These strategies are: (1) T-cell costimulation blockade (2) mixed chimerism induction (3) T-cell depletion and (4) tolerance induction through regulatory T-cells. After discussing the progress that has been made with each of these strategies, we will identify this field's most pressing unmet needs and discuss how we may best overcome the resulting barriers to tolerance induction.
Collapse
Affiliation(s)
- L S Kean
- Emory Transplant Center, Department of Surgery, Emory University School of Medicine, Atlanta, GA, USA
| | | | | | | |
Collapse
|
21
|
Hale DA, Dhanireddy K, Bruno D, Kirk AD. Induction of transplantation tolerance in non-human primate preclinical models. Philos Trans R Soc Lond B Biol Sci 2006; 360:1723-37. [PMID: 16147537 PMCID: PMC1569541 DOI: 10.1098/rstb.2005.1703] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Short-term outcomes following organ transplantation have improved considerably since the availability of cyclosporine ushered in the modern era of immunosuppression. In spite of this, many of the current limitations to progress in the field are directly related to the existing practice of relatively non-specific immunosuppression. These include increased risks of opportunistic infection and cancer, and toxicity associated with long-term immunosuppressive drug exposure. In addition, long-term graft loss continues to result in part from a failure to adequately control the anti-donor immune response. The development of a safe and reliable means of inducing tolerance would ameliorate these issues and improve the lives of transplant recipients, yet given the improving clinical standard of care, the translation of new therapies has become appropriately more cautious and dependent on increasingly predictive preclinical models. While convenient and easy to use, rodent tolerance models have not to date been reliably capable of predicting a therapy's potential efficacy in humans. Non-human primates possess an immune system that more closely approximates that found in humans, and have served as a more rigorous preclinical testing ground for novel therapies. Prior to clinical adaptation therefore, tolerance regimens should be vetted in non-human primates to ensure that there is sufficient potential for efficacy to justify the risk of its application.
Collapse
Affiliation(s)
- Douglas A Hale
- Digestive and Kidney Diseases, National Institute of Diabetes, NIH, Transplantation Branch, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|
22
|
Kirk AD, Mannon RB, Kleiner DE, Swanson JS, Kampen RL, Cendales LK, Elster EA, Wakefield T, Chamberlain C, Hoffmann SC, Hale DA. Results from a human renal allograft tolerance trial evaluating T-cell depletion with alemtuzumab combined with deoxyspergualin. Transplantation 2005; 80:1051-9. [PMID: 16278585 DOI: 10.1097/01.tp.0000174341.49741.8f] [Citation(s) in RCA: 105] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Perioperative lymphocyte depletion induces allograft tolerance in some animal models, but in humans has only been shown to reduce immunosuppressive requirements. Without maintenance immunosuppression, depleted human renal allograft recipients experience rejection characterized by infiltration of the allograft with monocytes and macrophages. T-cell depletion combined with a brief course of deoxyspergualin (DSG), a drug with inhibitory effects on monocytes and macrophages, induces tolerance in nonhuman primates. We therefore performed a trial to determine if lymphocyte depletion with alemtuzumab combined with DSG would induce tolerance in humans. METHODS Five recipients of live donor kidneys were treated perioperatively with alemtuzumab and DSG and followed postoperatively without maintenance immunosuppression. Patients were evaluated clinically, by flow cytometry, and by protocol biopsies analyzed immunohistochemically and with real-time polymerase chain reaction. Results were compared to previously studied patients receiving alemtuzumab alone or standard immunosuppression. RESULTS Despite profound T-cell depletion and therapeutic DSG dosing, all alemtuzumab/DSG patients developed reversible rejection that was similar in timing, histology, and transcriptional profile to that seen in patients treated with alemtuzumab alone. Chemokine expression was marked prior to and during rejections. CONCLUSIONS We conclude that treatment with alemtuzumab and DSG does not induce tolerance in humans. Chemokine production may not be adequately suppressed using this approach.
Collapse
Affiliation(s)
- Allan D Kirk
- Transplantation Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Bruno DA, Dhanireddy KK, Kirk AD. Challenges in therapeutic strategies for transplantation: Where now from here? Transpl Immunol 2005; 15:149-55. [PMID: 16412959 DOI: 10.1016/j.trim.2005.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 07/12/2005] [Indexed: 10/25/2022]
Abstract
The current standard of care in transplantation reliably achieves acceptable graft and patient survival but still depends on life long immunosuppression in most patients. Current strategies employ medications that, in general, inhibit distal events mediating rejection, namely T cell activation and cytotoxicity. They do not typically interfere with initial allorecognition or the factors that influence the direction of an immune response (towards cytotoxicity as opposed to anergy or regulation). Given the exponential amplification of immune responses, these proximal targets may be more efficient in preventing rejection. Recent laboratory investigations have identified several approaches, e.g., costimulation blockade, depletion, and hematopoietic chimerism, that influence the initial stages of the alloimmune response, or establish self-perpetuating means of eliminating rejection without chronic immunosuppression. This manuscript reviews methods of immune manipulation that the authors view as promising for future exploitation and transfer to the clinic. These therapies are similar in that they are viewed as attempts to influence the ability of the body to mount an immune response and its subsequent direction, as opposed to supplying late effector phase inhibition. While it is recognized as unlikely that any one therapy will universally lead to tolerance, the authors propose that these concepts will make immunosuppressive drug minimization more readily successful.
Collapse
Affiliation(s)
- David A Bruno
- Transplantation Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Building 10, Room 5-5750, Bethesda, MD 20892, USA
| | | | | |
Collapse
|
24
|
Kirk AD, Mannon RB, Swanson SJ, Hale DA. Strategies for minimizing immunosuppression in kidney transplantation. Transpl Int 2005; 18:2-14. [PMID: 15612977 DOI: 10.1111/j.1432-2277.2004.00019.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Immunosuppression remains the cause of most morbidity following organ transplantation. However, its use is also responsible for the outstanding graft and patient survival rates commonplace in modern transplantation. Thus, the predominant challenge for transplant clinicians is to provide a level of immunosuppression that prevents graft rejection while preserving immunocompetence against environmental pathogens. This review will outline several strategies for minimizing or tailoring the use of immunosuppressive drugs. The arguments for various strategies will be based on clinical trial data rather than animal studies. A distinction will be made between conventional immunosuppressive drug reduction based on over-immunosuppression, and newer induction methods specifically designed to lessen the need for chronic immunosuppression. Based on the available data we suggest that most patients can be transplanted with less immunosuppression than is currently standard.
Collapse
Affiliation(s)
- Allan D Kirk
- Transplantation Branch, Department of Health and Human Services, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Center Drive, Bethesda, MD 20892, USA.
| | | | | | | |
Collapse
|
25
|
Preston EH, Xu H, Dhanireddy KK, Pearl JP, Leopardi FV, Starost MF, Hale DA, Kirk AD. IDEC-131 (anti-CD154), sirolimus and donor-specific transfusion facilitate operational tolerance in non-human primates. Am J Transplant 2005; 5:1032-41. [PMID: 15816883 DOI: 10.1111/j.1600-6143.2005.00796.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
CD154-specific antibody therapy prevents allograft rejection in many experimental transplant models. However, initial clinical transplant trials with anti-CD154 have been disappointing suggesting the need for as of yet undetermined adjuvant therapy. In rodents, donor antigen (e.g., a donor blood transfusion), or mTOR inhibition (e.g., sirolimus), enhances anti-CD154's efficacy. We performed renal transplants in major histocompatibility complex-(MHC) mismatched rhesus monkeys and treated recipients with combinations of the CD154-specific antibody IDEC-131, and/or sirolimus, and/or a pre-transplant donor-specific transfusion (DST). Therapy was withdrawn after 3 months. Triple therapy prevented rejection during therapy in all animals and led to operational tolerance in three of five animals including donor-specific skin graft acceptance in the two animals tested. IDEC-131, sirolimus and DST are highly effective in preventing renal allograft rejection in primates. This apparently clinically applicable regimen is promising for human renal transplant trials.
Collapse
Affiliation(s)
- Edwin H Preston
- Transplantation Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland, USA
| | | | | | | | | | | | | | | |
Collapse
|
26
|
Dhanireddy KK, Xu H, Mannon RB, Hale DA, Kirk AD. The clinical application of monoclonal antibody therapies in renal transplantation. Expert Opin Emerg Drugs 2005. [DOI: 10.1517/14728214.9.1.23] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
27
|
Torrealba JR, Colburn M, Golner S, Chang Z, Scheunemann T, Fechner JH, Roenneburg D, Hu H, Alam T, Kim HT, Kanmaz T, Oberley T, Knechtle SJ, Hamawy MM. Selenium-binding protein-1 in smooth muscle cells is downregulated in a rhesus monkey model of chronic allograft nephropathy. Am J Transplant 2005; 5:58-67. [PMID: 15636612 DOI: 10.1111/j.1600-6143.2004.00651.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Treating patients with kidney failure by organ transplantation has been extraordinarily successful. Although, current immunosuppressants have improved short-term allograft survival, most transplants are eventually lost due to chronic allograft nephropathy (CAN). The molecular mechanisms underlying CAN are poorly understood. Smooth muscle cells (SMC) play a major role in the pathogenesis of CAN by contributing to the thickening of the intima and narrowing of the lumen of blood vessels. We show that selenium-binding protein-1 (SBP-1), a protein implicated in protein trafficking and secretion, is localized primarily to SMC in vivo. SBP-1 was heavily tyrosine-phosphorylated in vivo. Remarkably, SBP-1 was absent or strongly downregulated in vascular SMC in monkey kidney allografts with CAN. In contrast, the SMC alpha-actin was strongly expressed in the vascular SMC of the same allografts, indicating that the decrease in SBP-1 was not due to a global decrease in SMC proteins. Out of four growth factors implicated in the pathogenesis of CAN, only TGF-beta blocked the expression of SBP-1; thus, TGF-beta could regulate the expression of SBP-1 in CAN. These results show that SBP-1 localizes primarily to SMC in vivo and implicate this phosphoprotein in the effects of TGF-beta on SMC and in the process of CAN.
Collapse
Affiliation(s)
- Jose R Torrealba
- Department of Pathology, University of Wisconsin-Madison, WI, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
|
29
|
Fernandez LA, Tsuchida M, Manthei E, Fechner JH, Oberley TD, Leverson GE, Knechtle SJ, Hamawy MM. Immune status assay (ISA): a noninvasive procedure for studying allograft rejection. Transpl Immunol 2004; 13:147-54. [PMID: 15380545 DOI: 10.1016/j.trim.2004.05.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/21/2004] [Indexed: 10/26/2022]
Abstract
BACKGROUND There is a need for a simple, sensitive, noninvasive technique for monitoring graft function. We report here on a simple assay called immune status assay (ISA) that determines the status of the graft by simply examining the activation status of blood T cells. METHODS Graft-derived fibroblasts were used as a source of alloantigens and the recipient blood as a source of allograft-specific peripheral blood lymphocytes (PBL). PBL were added to wells containing donor or third-party graft-derived fibroblasts in the presence or absence of interleukin-2 (IL-2). On day 4 [(3)H]thymidine incorporation was quantified after the cells were incubated for 3 days at 37 degrees C, in a 5% CO(2) water-jacketed incubator. The results were analyzed using the following equation: %IL2 - /IL2+ = ((mean[(3)H]thymidine uptake in the absence of IL - 2) / (mean [(3)H]thymidine uptake in the presence of IL - 2)) x 100. RESULTS The ISA score (%IL-2 - /IL-2+) correlated strongly with the outcome of the graft, as it had a sensitivity of 82% for detecting rejections (14/17), and a specificity of 81% (30/37) for detecting non-rejections. Notably, the ISA detected immune T cell activation in the blood of graft rejecting subjects, which were not detected by currently used techniques such as mixed lymphocytes reaction. CONCLUSION The ISA is a straightforward procedure that detects allograft rejection with high specificity and sensitivity.
Collapse
Affiliation(s)
- Luis A Fernandez
- Division of Transplantation, Department of Surgery, University of Wisconsin Medical School, 600 Highland Avenue, Madison, WI 53792-7375, USA
| | | | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
Introduction of modern immunosuppressive agents has led to great success of allotransplantation in humans, and survival rates for all solid organs have been dramatically improved. However, a constant proportion of organs is lost every year due to chronic allograft rejection and immunosuppressive drug toxicity. This has led to a situation where, despite the of donor organ shortage, about one third of the patients on the kidney transplant waiting list are listed for a retransplant. The induction of donor-specific tolerance has the potential of at least partially resolving this problem, since it might prevent chronic rejection and drug toxicity at the same time. For a variety of protocols, successful tolerance induction has been demonstrated in rodent models. However, translation of such protocols to large animal models and on clinical trials has turned out to be very difficult. This review briefly describes mechanisms and barriers to transplantation tolerance, and then focuses on pre-clinical and clinical studies in non-human primates and humans. We have divided the strategies into two groups, based on the principle mechanisms of tolerance induction: the first group are protocols not using hematopoietic stem cell transplantation (HCT) as part of there regimen. They rely mainly on intensive T cell depletion (either by total body irradiation, total lymphoid irradiation or treatment with T cell-depleting agents such as anti-thymocyte globulin, anti-CD52 antibody or CD3 immunotoxin), which have been combined with costimulatory blockade, signaling blockade or donor antigen infusion. The second group are HCT-based protocols combining HCT with T cell-depleting agents and cytoreductive treatment. So far, only two protocols (one with total lymphoid irradiation and anti-thymocyte globulin, but no HCT; one with HCT, cyclophosphamide, anti-thymocyte globulin and thymic irradiation) have been translated into successful human studies. We summarize and discuss the results of these trials and suggest goals for further studies for the development tolerance protocols applicable for a broad population of allograft recipients.
Collapse
Affiliation(s)
- Thomas Fehr
- Transplantation Biology Research Center, Bone Marrow Transplantation Section, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA.
| | | |
Collapse
|
31
|
Abstract
The full potential of organ transplantation has not yet been realized because of the hazards associated with the long-term use of immunosuppressive drugs. Modern research into mechanisms of immune tolerance offers the promise of reprogramming the immune system, so as to harness the body's natural tolerance mechanisms in the service of graft acceptance. This would allow the minimization of immunosuppressive treatment and offers the prospect of eventually weaning transplant recipients off their drugs.
Collapse
Affiliation(s)
- Herman Waldmann
- Sir William Dunn School of Pathology, South Parks Road, Oxford OX13RE, UK.
| | | |
Collapse
|
32
|
Abstract
Many methods for reducing the immunosuppressive requirements of allotransplantation have been proposed based on a growing understanding of physiological and allospecific immunity. As these regimens are developed for clinical application, they require validation in models that are reasonably predictive of their performance in humans. This article provides an overview of the large animal models commonly used to test immunomodulatory organ transplant protocols. The rationale for the use of large animals and the effects of common immunosuppressants in the dog, pig, and non-human primate are reviewed. Promising methods for the induction of allospecific tolerance are surveyed with references to early human trials where appropriate.
Collapse
Affiliation(s)
- Allan D Kirk
- Transplantation Section, Transplantation and Autoimmunity Branch, National Institute of Diabetes, Digestive and Kidney Diseases/NIH/DHHS, Building 10, Room 11S/219, Bethesda, MD 20892, USA.
| |
Collapse
|
33
|
|
34
|
Oluwole SF, Oluwole OO, Adeyeri AO, DePaz HA. New strategies in immune tolerance induction. Cell Biochem Biophys 2004. [DOI: 10.1007/bf02739010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
35
|
Abstract
Insulin-dependent diabetes mellitus is an autoimmune disease that causes a progressive destruction of the pancreatic beta cells. As a result, the patient requires exogenous insulin to maintain normal blood glucose levels. Both the pancreas and the islets of Langerhans have been transplanted successfully in humans and in animal models, resulting in full normalization of glucose homeostasis. However, insulin independence, transient or persistent, was documented in only a small fraction of cases until recently. The chronic immunosuppression required to avoid immunological rejection appears to be toxic to the islets and adds the risk of lymphoproliferative disease reported earlier. For islet transplantation to become the method of choice, it is essential first to identify islet-friendly immunosuppressive regimens and/or to develop methods that induce donor-specific tolerance and improve islet isolation and transplantation protocols. Indeed, researchers have already successfully allografted islets in the presence of nonsteroidal immunosuppression in a process known as the Edmonton protocol. An alternative method, gene therapy, could replace these other methods and better meet the insulin requirement of an individual without requiring pancreatic or islet transplantation. This alternative, however, requires animal models to develop and test clinical protocols and to demonstrate the feasibility of preclinical trials. Nonhuman primates are ideally suited to achieve these goals. The efforts toward developing a nonhuman primate diabetic model with demonstrable insulin dependence are discussed and include pancreatic and islet transplant trials to reverse the diabetic state and achieve insulin independence. Also described are the various protocols that have been tested in primates to circumvent immunosuppression by using tolerance induction strategies in lieu of immunosuppression, thus exploring the field of donor-specific tolerance that extends beyond islet transplantation.
Collapse
Affiliation(s)
- Lakshmi K Gaur
- Washington National Primate Research Center, Department of Microbiology, University of Washington, School of Medicine, Seattle, WA, USA
| |
Collapse
|
36
|
Hubbard WJ, Hutchings A, Eckhoff D, Contreras J, Wilkins M, Thomas FT, Clements M, Thomas JM. Particle-induced circulatory disturbances in transplanted rhesus macaque kidneys. Transpl Int 2003. [DOI: 10.1111/j.1432-2277.2003.tb00354.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
37
|
Kirk AD, Hale DA, Mannon RB, Kleiner DE, Hoffmann SC, Kampen RL, Cendales LK, Tadaki DK, Harlan DM, Swanson SJ. Results from a human renal allograft tolerance trial evaluating the humanized CD52-specific monoclonal antibody alemtuzumab (CAMPATH-1H). Transplantation 2003; 76:120-9. [PMID: 12865797 DOI: 10.1097/01.tp.0000071362.99021.d9] [Citation(s) in RCA: 368] [Impact Index Per Article: 17.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
BACKGROUND Profound T-cell depletion before allotransplantation with gradual posttransplant T-cell repopulation induces a state of donor-specific immune hyporesponsiveness or tolerance in some animal models. Alemtuzumab (Campath-1H, Millennium Pharmaceuticals, Cambridge, MA) is a humanized CD52-specific monoclonal antibody that produces profound T-cell depletion in humans and reduces the need for maintenance immunosuppression after renal transplantation. We therefore performed a study to determine if pretransplant T-cell depletion with alemtuzumab would induce tolerance in human renal allografts and to evaluate the nature of the alloimmune response in the setting of T-cell depletion. METHODS Seven nonsensitized recipients of living-donor kidneys were treated perioperatively with alemtuzumab and followed postoperatively without maintenance immunosuppression. Patients were evaluated clinically by peripheral flow cytometry, protocol biopsies evaluated immunohistochemically, and real-time polymerase chain reaction-based transcriptional analysis. RESULTS Lymphocyte depletion was profound in the periphery and secondary lymphoid tissues. All patients developed reversible rejection episodes within the first month that were characterized by predominantly monocytic (not lymphocytic) infiltrates with only rare T cells in the peripheral blood or allograft. These episodes were responsive to treatment with steroids or sirolimus or both. After therapy, patients remained rejection-free on reduced immunosuppression, generally monotherapy sirolimus, despite the recovery of lymphocytes to normal levels. CONCLUSIONS T-cell depletion alone does not induce tolerance in humans. These data underscore a prominent role for early responding monocytes in human allograft rejection.
Collapse
Affiliation(s)
- Allan D Kirk
- Transplantation and Autoimmunity Branch, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Abstract
In the past two decades, an immense amount of information has been generated on the mechanism of T cell receptor (TCR) signaling (also called signal 1). This overview describes the major signalling pathways in the TCR signal transduction cascade and focuses on proximal events in TCR signaling. The review also discusses some of the strategies that target proximal TCR signaling, which are used for preventing graft rejection.
Collapse
Affiliation(s)
- Majed M Hamawy
- Department of Surgery, University of Wisconsin, Madison, 53792, USA.
| |
Collapse
|
39
|
Knechtle SJ, Pirsch JD, H Fechner J, Becker BN, Friedl A, Colvin RB, Lebeck LK, Chin LT, Becker YT, Odorico JS, D'Alessandro AM, Kalayoglu M, Hamawy MM, Hu H, Bloom DD, Sollinger HW. Campath-1H induction plus rapamycin monotherapy for renal transplantation: results of a pilot study. Am J Transplant 2003; 3:722-30. [PMID: 12780564 DOI: 10.1034/j.1600-6143.2003.00120.x] [Citation(s) in RCA: 326] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Campath-1H, an anti-CD52 monoclonal antibody, was used as induction therapy (40 mg i.v. total dose) in 29 primary human renal transplants, and the patients were maintained on rapamycin monotherapy (levels 8-15 ng/mL) post-transplant. Campath-1H profoundly depletes lymphocytes long-term and more transiently depletes B cells and monocytes. All patients are alive and well at 3-29 months of follow up. One graft was lost because of rejection. There have been no systemic infections and no malignancies. Eight of 29 patients have experienced rejection, which was successfully treated in seven of eight patients. Five of these patients had pathological evidence of a humoral component of their rejection. Seven of the 29 patients were converted to standard triple therapy on account of rejection. Rapamycin was generally well tolerated in that there were no significant wound-healing problems; two lymphoceles required surgical drainage; and most patients were treated with a lipid-lowering agent. Flow crossmatch testing post-transplant revealed evidence of alloantibody in two patients tested with previous combined cellular and humoral rejection. Biopsies have shown no chronic allograft nephropathy to date. In view of the relatively high incidence of early humoral rejection, we plan to modify the immunosuppressive regimen in subsequent pilot studies. This clinical trial provides insight into the use of Campath-1H induction in combination with rapamycin maintenance monotherapy.
Collapse
Affiliation(s)
- Stuart J Knechtle
- Department of Surgery, University of Wisconsin Medical School, Madison, WI, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
40
|
Clement A, Pereboev A, Curiel DT, Dong SS, Hutchings A, Thomas JM. Converting nonhuman primate dendritic cells into potent antigen-specific cellular immunosuppressants by genetic modification. Immunol Res 2003; 26:297-302. [PMID: 12403367 DOI: 10.1385/ir:26:1-3:297] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
T cell depletion plus donor bone marrow cell (BMC) infusion induces long-term kidney allograft survival in a limited number of rhesus macaque recipients. Therefore, there is a need to enhance the tolerogenic activity of donor BMCs. The tolerogenic effect of donor BMCs is ascribed to a veto activity, mediated by a CD8+ subset that upregulates immunoregulatory effector molecules, transforming growth factor-beta1 (TGF-beta), and FasL, after interaction with donor-reactive cytotoxic T lymphocyte precursors (CTLp), leading to clonal inactivation/deletion of donor-reactive CTLp. Of note, the receptors for TGF-beta1- and FasL-induced signal transduction are upregulated in activated T cells. Since mature dendritic cells (DCs) are exceptionally efficient activators of T cells, we postulated that mature DCs modified to overexpress TGF-beta1 and FasL might exert potent veto (i.e., inactivating/deleting) activity independent of CD8 expression. A fusion protein comprising antihuman CD40 single-chain antibody and soluble coxsackie-adenovirus receptor enabled high-efficiency transduction of rhesus monocyte-derived DCs (Rh MDDCs) by recombinant adenovirus (Ad). Mature Rh MDDCs transduced with Ad encoding active TGF-beta1 retained a mature phenotype yet exhibited potent alloantigen-specific cellular immunosuppression. Such modified MDDCs have the potential to promote tolerance induction to allografts in vivo.
Collapse
Affiliation(s)
- Asiedu Clement
- Department of Surgery, University of Alabama at Birmingham, 35294, USA.
| | | | | | | | | | | |
Collapse
|
41
|
Thomas FT, Hutchings A, Contreras J, Wu J, Jiang XL, Eckhoff D, Thomas JM. Islet transplantation in the twenty-first century. Immunol Res 2003; 26:289-96. [PMID: 12403366 DOI: 10.1385/ir:26:1-3:289] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Isolated islet transplantation is poised for clinical application to treat insulin-dependent diabetes. Unlike exogenous insulin therapy, islet transplantation has promise for preventing and/or reversing the dismal secondary complications of diabetes. Islet transplants are arguably the most unique type of allografts, and we discuss their properties, limitations, and potential in this overview. The induction of immunologic tolerance to allow islet grafts to endure and prevail, without the hardship of chronic immunosuppressive therapy, is a major goal in this field. In this context, we discuss our successful results in preclinical models of primate allogeneic and xenogeneic islet graft tolerance.
Collapse
Affiliation(s)
- Frank T Thomas
- Department of Surgery, University of Alabama at Birmingham, 35294, USA.
| | | | | | | | | | | | | |
Collapse
|
42
|
Affiliation(s)
- A P Monaco
- Harvard Medical School, Boston, Massachusetts, USA
| |
Collapse
|
43
|
Wu A, Yamada K, Neville DM, Awwad M, Wain JC, Shimizu A, Gojo S, Kitamura H, Colvin RB, Cooper DKC, Sykes M, Sachs DH. Xenogeneic thymus transplantation in a pig-to-baboon model. Transplantation 2003; 75:282-91. [PMID: 12589146 DOI: 10.1097/01.tp.0000044137.97841.99] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND We have tested whether fetal porcine thymic tissue transplantation can lead to tolerance across a discordant (pig-to-baboon) xenogeneic barrier. METHODS Six baboons underwent a conditioning regimen with thymectomy, splenectomy, and anti-monkey CD3 antibody conjugated to a diphtheria toxin binding site mutant (FN18-CRM9). Porcine fetal or neonatal thymic tissue was transplanted into three baboons. Three control baboons received either no transplanted pig tissue (n=1) or adult pig lymph node (n=2). Cellular responses and skin xenografts were used to test for tolerance. RESULTS After T-cell depletion and thymic transplantation, recovery of thymus-dependent naïve-type CD4 cells (CD4/CD45RA ) and in vitro xenogeneic hyporesponsiveness were observed. No sensitization of alpha-galactosyl antibody responses was observed. The thymic grafts survived up to 48 days. Porcine skin xenografts were performed in two of these animals with survival of 22 and 24 days. Only two of these animals were completely T-cell depleted, and both failed to recover thymus-dependent T cells (CD4/CD45RA ). In one animal, general in vitro hyporesponsiveness was observed, with subsequent death from infection. The second animal demonstrated delayed recovery of T cells and prolonged general hyporesponsiveness in vitro. Neither animal demonstrated prolongation of porcine skin grafts compared with allografts (both rejected by day 13). CONCLUSIONS Porcine thymic tissue is able to induce xenogeneic hyporesponsiveness. More efficient thymic engraftment may allow this approach to induce xenograft tolerance.
Collapse
Affiliation(s)
- Anette Wu
- Transplantation Biology Research Center, Massachusetts General Hospital/Harvard Medical School, Boston, MA 02129, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Contreras JL, Jenkins S, Eckhoff DE, Hubbard WJ, Lobashevsky A, Bilbao G, Thomas FT, Neville DM, Thomas JM. Stable alpha- and beta-islet cell function after tolerance induction to pancreatic islet allografts in diabetic primates. Am J Transplant 2003; 3:128-38. [PMID: 12603208 DOI: 10.1034/j.1600-6143.2003.00031.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Pancreatic islet transplantation (PIT) is an attractive alternative for type 1 diabetic patients. PIT is not yet an effective clinical reality due in part to early loss of functional islet mass. In addition, current immunosuppressive drugs have toxic effects on islets and increase the risk of morbidity and mortality. Precise and durable alpha- and beta-cell function is essential for the success of PIT. Therefore, it is important to establish whether PIT can produce adequate long-term metabolic control, especially in the absence of chronic immunosuppressive therapy (CIT). In the present study, the stability of functional alpha- and beta-cell mass and metabolic function was assessed in streptozotocin (STZ)-induced diabetic primates following PIT in the absence of CIT. Diabetes was induced in rhesus macaques with STZ, 140 mg/kg. Hyperglycemia was reversed rapidly by PIT coupled with a 14-day tolerance induction protocol based on F(Ab)2-IT and DSG (n = 7). Two diabetic animals received the tolerance induction protocol without PIT. Acute rejection was presented in three animals at 70, 353 and 353 days post transplant in the tolerance induction protocol, whereas the controls [F(Ab)2-IT or DSG alone] showed early 10-day function but all lost islet function by days 15-70. One recipient [F(Ab)2-IT or DSG] died euglycemic after a surgical procedure on day 187. At 2 years, three animals studied had a normal FIM evaluated by oral glucose tolerance test, mixed meal test, acute insulin response to glucose, glucose disposal rate, and hyperinsulinemic hypoglycemic clamp. PIT in STZ-induced diabetic primates resulted in restoration of normal alpha- and beta-cell function. Operational tolerance induction was achieved with only peritransplant administration of F(Ab)2-IT and DSG sparing the animals from chronic exposure of diabetogenic immunosuppressive drugs. These results offer an exciting new potential for treatment of type 1 diabetes mellitus.
Collapse
Affiliation(s)
- Juan L Contreras
- The Transplant Center, Department of Surgery, and Gene Therapy Center, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
| | | | | | | | | | | | | | | | | |
Collapse
|
45
|
|
46
|
Fernandez LA, Torrealba J, Yagci G, Ishido N, Tsuchida M, Tae Kim H, Dong Y, Oberley T, Fechner J, Colburn MJ, Schultz J, Kanmaz T, Hu H, Knechtle SJ, Hamawy MM. Piceatannol in combination with low doses of cyclosporine A prolongs kidney allograft survival in a stringent rat transplantation model. Transplantation 2002; 74:1609-17. [PMID: 12490796 DOI: 10.1097/00007890-200212150-00020] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The discovery of new immunosuppressive agents has enhanced short-term graft survival. However, current immunosuppressants often induce toxicities that limit their clinical use. Thus, there is a need for new immunosuppressants for use in clinical transplantation. Piceatannol blocks Syk and ZAP-70, tyrosine kinases involved in immune cell activation. We examined whether piceatannol prolongs kidney allograft survival in the stringent ACI-to-Lewis rat model. METHODS Kidney recipients were divided into four groups. Group 1 (n=8) received piceatannol 30 mg/kg per day intravenously and cyclosporine A (CsA) 2 mg/kg per day intramuscularly from day -3 to day 7 after transplantation. At day 8, piceatannol was reduced to 10 mg/kg per day and the combined treatment continued until day 60. Group 2 (n=9) received 2 mg/kg per day CsA alone from day -3 to day 60. Group 3 (n=4) received piceatannol alone as in group 1. Group 4 (n=2) received only the vehicle dimethyl sulfoxide from day -3 to day 60. Graft rejection was defined as either a serum creatinine level more than 2 mg/dL or animal death. RESULTS Group 1 animals survived for at least 115 days (n=8, P<0.05), with several animals maintaining their grafts for more than 200 days. In contrast, 8 of 9 animals in group 2 rejected their grafts within 10 days of transplantation; one animal survived for 71 days. Excellent graft function was maintained in group 1 animals despite withdrawal of immunosuppression. CONCLUSIONS These results are the first to show that piceatannol, when combined with subtherapeutic dosages of CsA, prevents graft rejection, suggesting that targeting Syk and Zap could be useful for preventing graft rejection.
Collapse
Affiliation(s)
- Luis A Fernandez
- Department of Surgery, Division of Transplantation, Laboratory of Transplant Immunology, University of Wisconsin-Madison, WI, USA
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
47
|
Asiedu C, Dong SS, Pereboev A, Wang W, Navarro J, Curiel DT, Thomas JM. Rhesus monocyte-derived dendritic cells modified to over-express TGF-beta1 exhibit potent veto activity. Transplantation 2002; 74:629-37. [PMID: 12352878 DOI: 10.1097/00007890-200209150-00008] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND The tolerogenic activity of allogeneic bone marrow cells (BMCs) associates with functional inactivation of alloreactive T cells and has been attributed to a veto effect. Studies in mice and rhesus monkeys indicated that the CD8alpha molecule expressed on a subpopulation of allogeneic BMCs is necessary to induce signal transduction within the BMCs to increase veto effector molecules such as transforming growth factor (TGF)-beta1. In vitro activation of alloreactive cytotoxic T-lymphocyte precursor enhances their susceptibility to veto-mediated functional inactivation by specific alloantigen-bearing BMCs. Accordingly, we examined a hypothesis that mature rhesus monkey (Rh) monocyte-derived dendritic cells (MDDCs) modified by gene transfer to over-express active TGF-beta1 might mediate veto activity without the need to express CD8alpha. METHODS Rh MDDCs were modified by recombinant adenovirus (Ad) transduction and characterized by phenotype and functional studies. RESULTS Rh MDDC transduction with Ad vectors using conventional methods was remarkably inefficient. However, a single-chain anti-CD40/soluble Coxsackie and adenovirus receptor-fusion protein (G28/sCAR) permitted high-efficiency transduction of Rh MDDCs by retargeting Ad to Rh MDDC CD40. Mature Rh MDDCs that were transduced to overexpress active TGF-beta1 (AdTGF-beta1 Rh MDDC) significantly suppressed alloimmune responses in [ H]thymidine uptake mixed leukocyte reaction assays. We showed by the carboxyfluorescein succinimidyl ester dilution method that allogeneic mature AdTGF-beta1 Rh MDDCs inhibited proliferation of CD4 and CD8 responder T cells. Notably, AdTGF-beta1 Rh MDDC abrogated alloimmune responses induced by control AdGFP Rh MDDC in an antigen-specific manner. CONCLUSIONS These results suggest that nonhuman primate mature MDDCs can be genetically engineered to function as alloantigen-specific cellular immunosuppressants, an approach that has potential to facilitate induction of allograft tolerance in vivo.
Collapse
Affiliation(s)
- Clement Asiedu
- Department of Surgery, Division of Transplant Immunology, University of Alabama at Birmingham, 35294, USA
| | | | | | | | | | | | | |
Collapse
|
48
|
Preston E, Kirk AD. Context-based therapy: A conceptual framework for transplantation tolerance. Transplant Rev (Orlando) 2002. [DOI: 10.1053/trre.2002.126011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
49
|
Rotrosen D, Matthews JB, Bluestone JA. The immune tolerance network: a new paradigm for developing tolerance-inducing therapies. J Allergy Clin Immunol 2002; 110:17-23. [PMID: 12110811 DOI: 10.1067/mai.2002.124258] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Immune tolerance therapies are designed to reprogram immune cells in a highly specific fashion to eliminate pathogenic responses while preserving protective immunity. A concept that has tantalized immunologists for decades, the development of tolerance-inducing therapies, would revolutionize the management of a wide range of chronic and often debilitating diseases by obviating the need for lifelong immunosuppressive regimens. The advances of the past decade have provided a more detailed understanding of the molecular events associated with T-cell recognition and activation. Building on these advances, immunologists have demonstrated the feasibility of various tolerance-inducing approaches in small- and large-animal models of autoimmunity, allergy, and transplant graft rejection. Unprecedented opportunities to test these approaches in a variety of human diseases have now emerged. To capitalize on these advances, the National Institutes of Health recently established the Immune Tolerance Network (ITN), an international consortium of more than 70 basic and clinical immunologists dedicated to the evaluation of novel tolerance-inducing therapies and associated studies of immunologic mechanisms. By using a unique interactive approach to accelerate the development of clinical tolerance therapies, the ITN is partnering with the biotechnology and pharmaceutical industries to examine innovative tolerogenic approaches in a range of allergic and autoimmune diseases and to prevent graft rejection after transplantation. Two years since its inception, the ITN now has approximately 2 dozen clinical trials or tolerance assays studies ongoing or in later stages of protocol development. This report summarizes the rationale for emphasizing clinical research on immune tolerance and highlights the progress of the ITN.
Collapse
Affiliation(s)
- Daniel Rotrosen
- National Institute of Allergy and Infectious Diseases, Bethesda, MD 20817,USA
| | | | | |
Collapse
|
50
|
Chatenoud L. The use of monoclonal antibodies to restore self-tolerance in established autoimmunity. Endocrinol Metab Clin North Am 2002; 31:457-75, ix. [PMID: 12092461 DOI: 10.1016/s0889-8529(01)00018-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The author hopes to convince the reader that the data presented argue for a stage during the development of IDDM when beta-cell destruction can be counteracted and tolerance to beta cells restored, provided the immune aggression is arrested. This argument constitutes a solid rationale for immunointervention in established IDDM, especially by using potent agents such as CD3. The future for the application of monoclonal antibodies not only in autoimmunity but also in transplantation is exiting. With the development of humanized monoclonal antibodies, therapeutic uses for them are likely to expand. Enormous progress has been made in the last 15 years, and it is likely that before a similar time period has elapsed, monoclonal antibodies will have become standard tools that will dispense the need for long-term immunosuppression and its inherent dangers in various clinical arenas.
Collapse
|