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Harris AG, Iacobazzi D, Caputo M, Bartoli-Leonard F. Graft rejection in paediatric congenital heart disease. Transl Pediatr 2023; 12:1572-1591. [PMID: 37692547 PMCID: PMC10485650 DOI: 10.21037/tp-23-80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Accepted: 07/28/2023] [Indexed: 09/12/2023] Open
Abstract
Congenital heart disease (CHD) affects around 1.35 million neonates worldwide per annum, and surgical repair is necessary in approximately 25% of cases. Xenografts, usually of bovine or porcine origin, are often used for the surgical reconstruction. These xenografts elicit an immune response due to significant immunological incompatibilities between host and donor. Current techniques to dampen the initial hyperacute rejection response involve aldehyde fixation to crosslink xenoantigens, such as galactose-α1,3-galactose and N-glycolylneuraminic acid. While this temporarily masks the epitopes, aldehyde fixation is a suboptimal solution, degrading over time, resulting in cytotoxicity and rejection. The immune response to foreign tissue eventually leads to chronic inflammation and subsequent graft failure, necessitating reintervention to replace the defective bioprosthetic. Decellularisation to remove immunoincompatible material has been suggested as an alternative to fixation and may prove a superior solution. However, incomplete decellularisation poses a significant challenge, causing a substantial immune rejection response and subsequent graft rejection. This review discusses commercially available grafts used in surgical paediatric CHD intervention, looking specifically at bovine jugular vein conduits as a substitute to cryopreserved homografts, as well as decellularised alternatives to the aldehyde-fixed graft. Mechanisms of biological prosthesis rejection are explored, including the signalling cascades of the innate and adaptive immune response. Lastly, emerging strategies of intervention are examined, including the use of tissue from genetically modified pigs, enhanced crosslinking and decellularisation techniques, and augmentation of grafts through in vitro recellularisation or functionalisation with human surface proteins.
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Affiliation(s)
- Amy G. Harris
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Dominga Iacobazzi
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
| | - Massimo Caputo
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
- Bristol Heart Institute, University Hospital Bristol and Weston NHS Foundation Trust, Bristol, UK
| | - Francesca Bartoli-Leonard
- Bristol Medical School, Faculty of Health Sciences, University of Bristol, Bristol, UK
- Bristol Heart Institute, University Hospital Bristol and Weston NHS Foundation Trust, Bristol, UK
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2
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Gramkow AM, Isaksson GL, Palarasah Y, Jensen BL, Alnor A, Thiesson HC. Exploration of complement split products in plasma and urine as biomarkers of kidney graft rejection. Immunobiology 2023; 228:152462. [PMID: 37406469 DOI: 10.1016/j.imbio.2023.152462] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 06/13/2023] [Accepted: 06/22/2023] [Indexed: 07/07/2023]
Abstract
INTRODUCTION The complement system, consisting of more than thirty different soluble and cell-bound proteins, exerts essential functions both in the innate and adaptive immune systems and is believed to be an important contributor to allograft injury in kidney transplantation. The anaphylatoxins C3a and C5a are powerful chemoattractants, recruiting immune effector cells toward the site of complement activation and enhance T-cell response, while C3dg binding to CR2 on B-cells, enhances B-cell immunity at several stages of the B-cell differentiation. Complement split products in plasma and urine could reflect ongoing inflammation and tissue injury. We, therefore, investigated if complement split products increase in plasma and urine in kidney transplant recipients with rejection. METHOD In this case-control feasibility study, complement factors C3a, C3dg, C4a, and C5a were measured in plasma and C3dg and sC5b-9 associated C9 neoantigen in urine in 15 kidney transplant recipients with rejection (cases) and 15 kidney transplant recipients without (controls). The groups were matched on the type of transplantation and the time from transplantation to sampling. The complement split products were compared (i) between cases and controls and (ii) within the rejection group over time, comparing the measurements at rejection with measurements where the kidney transplant recipients were clinically stable. Possible moderators were explored, and results adjusted accordingly. P values < 0.05 were considered significant. Plasma C3dg was analyzed by immune-electrophoresis, plasma C3a, plasma C4a, and plasma C5a by flow cytometry, and urine C3dg and urine C9neo by ELISA. RESULTS In plasma, there were no significant differences between the rejection and the control group. However, steroids and pretransplant C3dg levels significantly influenced C3dg. Within the rejection group, plasma C3a and C3dg were significantly higher at the time of rejection compared to the stable phase (p < 0.01). In urine, C3dg/creatinine and C9 neoantigen/creatinine ratios were not different between the rejection and the control group. Urine C3dg/creatinine and urine C9 neoantigen/creatinine ratios correlated to urine albumin and significantly increased after the transplantation (p < 0.001). CONCLUSION This study shows increased plasma C3a and C3dg in kidney transplant recipients, primarily with T cell mediated rejection. This finding suggests that consecutive measurements of C3a and C3dg in plasma could be applicable to monitor alloreactivity in kidney transplant recipients. Urine complement split products are unsuitable as rejection biomarkers since the permeability of the glomerular filtration barrier strongly influences them. Prospective longitudinal studies on plasma C3a and C3dg dynamics will be needed to validate present findings.
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Affiliation(s)
- Ann-Maria Gramkow
- Dept. of Nephrology, Odense University Hospital, Kløvervænget 6, 5000 Odense, Denmark; Dept. of Clinical Research, University of Southern Denmark, J.B. Winsløwsvej 19, 5000 Odense, Denmark.
| | - Gustaf L Isaksson
- Dept. of Nephrology, Odense University Hospital, Kløvervænget 6, 5000 Odense, Denmark; Dept. of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, J.B. Winsløwsvej 19, 5000 Odense, Denmark.
| | - Yaseelan Palarasah
- Dept. of Molecular Medicine, Cancer and Inflammation, University of Southern Denmark, J.B. Winsløwsvej 19, 5000 Odense, Denmark.
| | - Boye L Jensen
- Dept. of Molecular Medicine, Cardiovascular and Renal Research, University of Southern Denmark, J.B. Winsløwsvej 19, 5000 Odense, Denmark.
| | - Anne Alnor
- Dept. of Clinical Immunology and Biochemistry, Hospital Lillebælt, Beridderbakken 4, 7100 Vejle, Denmark; Dept. of Clinical Biochemistry, Odense University Hospital, J.B. Winsløwsvej 4, 5000 Odense, Denmark.
| | - Helle C Thiesson
- Dept. of Nephrology, Odense University Hospital, Kløvervænget 6, 5000 Odense, Denmark; Dept. of Clinical Research, University of Southern Denmark, J.B. Winsløwsvej 19, 5000 Odense, Denmark.
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Tseng HT, Lin YW, Huang CY, Shih CM, Tsai YT, Liu CW, Tsai CS, Lin FY. Animal Models for Heart Transplantation Focusing on the Pathological Conditions. Biomedicines 2023; 11:biomedicines11051414. [PMID: 37239085 DOI: 10.3390/biomedicines11051414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Revised: 04/29/2023] [Accepted: 05/05/2023] [Indexed: 05/28/2023] Open
Abstract
Cardiac transplant recipients face many complications due to transplant rejection. Scientists must conduct animal experiments to study disease onset mechanisms and develop countermeasures. Therefore, many animal models have been developed for research topics including immunopathology of graft rejection, immunosuppressive therapies, anastomotic techniques, and graft preservation techniques. Small experimental animals include rodents, rabbits, and guinea pigs. They have a high metabolic rate, high reproductive rate, small size for easy handling, and low cost. Additionally, they have genetically modified strains for pathological mechanisms research; however, there is a lacuna, as these research results rarely translate directly to clinical applications. Large animals, including canines, pigs, and non-human primates, have anatomical structures and physiological states that are similar to those of humans; therefore, they are often used to validate the results obtained from small animal studies and directly speculate on the feasibility of applying these results in clinical practice. Before 2023, PubMed Central® at the United States National Institute of Health's National Library of Medicine was used for literature searches on the animal models for heart transplantation focusing on the pathological conditions. Unpublished reports and abstracts from conferences were excluded from this review article. We discussed the applications of small- and large-animal models in heart transplantation-related studies. This review article aimed to provide researchers with a complete understanding of animal models for heart transplantation by focusing on the pathological conditions created by each model.
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Affiliation(s)
- Horng-Ta Tseng
- Taipei Heart Institute, Taipei Medical University, Taipei 11031, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Departments of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Yi-Wen Lin
- Institute of Oral Biology, National Yang Ming Chiao Tung University (Yangming Campus), Taipei 112304, Taiwan
| | - Chun-Yao Huang
- Taipei Heart Institute, Taipei Medical University, Taipei 11031, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Departments of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Chun-Ming Shih
- Taipei Heart Institute, Taipei Medical University, Taipei 11031, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Departments of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
| | - Yi-Ting Tsai
- Division of Cardiovascular Surgery, Tri-Service General Hospital, Defense Medical Center, Taipei 11490, Taiwan
| | - Chen-Wei Liu
- Department of Basic Medical Science, College of Medicine, University of Arizona, Phoenix, AZ 85721, USA
| | - Chien-Sung Tsai
- Taipei Heart Institute, Taipei Medical University, Taipei 11031, Taiwan
- Division of Cardiovascular Surgery, Tri-Service General Hospital, Defense Medical Center, Taipei 11490, Taiwan
- Department and Graduate Institute of Pharmacology, National Defense Medical Center, Taipei 11490, Taiwan
| | - Feng-Yen Lin
- Taipei Heart Institute, Taipei Medical University, Taipei 11031, Taiwan
- Division of Cardiology and Cardiovascular Research Center, Taipei Medical University Hospital, Taipei 11031, Taiwan
- Departments of Internal Medicine, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan
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Anwar IJ, DeLaura I, Ladowski J, Gao Q, Knechtle SJ, Kwun J. Complement-targeted therapies in kidney transplantation-insights from preclinical studies. Front Immunol 2022; 13:984090. [PMID: 36311730 PMCID: PMC9606228 DOI: 10.3389/fimmu.2022.984090] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2022] [Accepted: 09/28/2022] [Indexed: 01/21/2023] Open
Abstract
Aberrant activation of the complement system contributes to solid-organ graft dysfunction and failure. In kidney transplantation, the complement system is implicated in the pathogenesis of antibody- and cell-mediated rejection, ischemia-reperfusion injury, and vascular injury. This has led to the evaluation of select complement inhibitors (e.g., C1 and C5 inhibitors) in clinical trials with mixed results. However, the complement system is highly complex: it is composed of more than 50 fluid-phase and surface-bound elements, including several complement-activated receptors-all potential therapeutic targets in kidney transplantation. Generation of targeted pharmaceuticals and use of gene editing tools have led to an improved understanding of the intricacies of the complement system in allo- and xeno-transplantation. This review summarizes our current knowledge of the role of the complement system as it relates to rejection in kidney transplantation, specifically reviewing evidence gained from pre-clinical models (rodent and nonhuman primate) that may potentially be translated to clinical trials.
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Affiliation(s)
| | | | | | | | - Stuart J. Knechtle
- Duke Transplant Center, Department of Surgery, Duke University School of Medicine, Durham, NC, United States
| | - Jean Kwun
- Duke Transplant Center, Department of Surgery, Duke University School of Medicine, Durham, NC, United States
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5
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Nyambuya TM, Dludla PV, Mxinwa V, Nkambule BB. The pleotropic effects of fluvastatin on complement-mediated T-cell activation in hypercholesterolemia. Biomed Pharmacother 2021; 143:112224. [PMID: 34649351 DOI: 10.1016/j.biopha.2021.112224] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 09/06/2021] [Accepted: 09/17/2021] [Indexed: 12/16/2022] Open
Abstract
T-cells orchestrate the inflammatory responses in atherosclerosis, and their function is modified by the lipoprotein milieu and complement activity. We investigated the effects of fluvastatin on the expression of complement decay-accelerating factor (DAF/CD55) antigen, and the levels of transcription factors in circulating T-cells in hypercholesterolemia. The hypercholesterolemic state was associated with the upregulation of DAF expression on circulating T-cells and increased levels nuclear factor kappa B (NF-kB) and interferon regulatory factor 4 (IRF4). Notably, the elevated levels of DAF and NF-kB expression persisted following treatment with fluvastatin. Therefore, the pleiotropic effects of fluvastatin are partially ascribed to its ability to mediate T-cell activation and regulate complement activity. Consequently, enhanced therapeutic interventions that targets complement-induced T-cell activation may be important in mitigating the development of atherosclerosis and major cardiovascular events in individuals with hypercholesterolemia.
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Affiliation(s)
- Tawanda Maurice Nyambuya
- School of Laboratory Medicine and Medical Sciences (SLMMS), College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa; Department of Health Sciences, Faculty of Health and Applied Sciences, Namibia University of Science and Technology, Windhoek, Namibia.
| | - Phiwayinkosi Vusi Dludla
- Biomedical Research and Innovation Platform, South African Medical Research Council, Tygerberg, South Africa.
| | - Vuyolwethu Mxinwa
- School of Laboratory Medicine and Medical Sciences (SLMMS), College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
| | - Bongani Brian Nkambule
- School of Laboratory Medicine and Medical Sciences (SLMMS), College of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
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6
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Frye CC, Bery AI, Kreisel D, Kulkarni HS. Sterile inflammation in thoracic transplantation. Cell Mol Life Sci 2020; 78:581-601. [PMID: 32803398 DOI: 10.1007/s00018-020-03615-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 07/20/2020] [Accepted: 08/07/2020] [Indexed: 02/08/2023]
Abstract
The life-saving benefits of organ transplantation can be thwarted by allograft dysfunction due to both infectious and sterile inflammation post-surgery. Sterile inflammation can occur after necrotic cell death due to the release of endogenous ligands [such as damage-associated molecular patterns (DAMPs) and alarmins], which perpetuate inflammation and ongoing cellular injury via various signaling cascades. Ischemia-reperfusion injury (IRI) is a significant contributor to sterile inflammation after organ transplantation and is associated with detrimental short- and long-term outcomes. While the vicious cycle of sterile inflammation and cellular injury is remarkably consistent amongst different organs and even species, we have begun understanding its mechanistic basis only over the last few decades. This understanding has resulted in the developments of novel, yet non-specific therapies for mitigating IRI-induced graft damage, albeit with moderate results. Thus, further understanding of the mechanisms underlying sterile inflammation after transplantation is critical for identifying personalized therapies to prevent or interrupt this vicious cycle and mitigating allograft dysfunction. In this review, we identify common and distinct pathways of post-transplant sterile inflammation across both heart and lung transplantation that can potentially be targeted.
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Affiliation(s)
- C Corbin Frye
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA.
| | - Amit I Bery
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, 4523 Clayton Avenue, Campus Box 8052, St. Louis, MO, 63110, USA.
| | - Daniel Kreisel
- Division of Cardiothoracic Surgery, Department of Surgery, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Hrishikesh S Kulkarni
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Washington University School of Medicine, 4523 Clayton Avenue, Campus Box 8052, St. Louis, MO, 63110, USA
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7
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Khan MA, Shamma T, Kazmi S, Altuhami A, Ahmed HA, Assiri AM, Broering DC. Hypoxia-induced complement dysregulation is associated with microvascular impairments in mouse tracheal transplants. J Transl Med 2020; 18:147. [PMID: 32234039 PMCID: PMC7110829 DOI: 10.1186/s12967-020-02305-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Accepted: 03/16/2020] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Complement Regulatory Proteins (CRPs), especially CD55 primarily negate complement factor 3-mediated injuries and maintain tissue homeostasis during complement cascade activation. Complement activation and regulation during alloimmune inflammation contribute to allograft injury and therefore we proposed to investigate a crucial pathological link between vascular expression of CD55, active-C3, T cell immunity and associated microvascular tissue injuries during allograft rejection. METHODS Balb/c→C57BL/6 allografts were examined for microvascular deposition of CD55, C3d, T cells, and associated tissue microvascular impairments during rejection in mouse orthotopic tracheal transplantation. RESULTS Our findings demonstrated that hypoxia-induced early activation of HIF-1α favors a cell-mediated inflammation (CD4+, CD8+, and associated proinflammatory cytokines, IL-2 and TNF-α), which proportionally triggers the downregulation of CRP-CD55, and thereby augments the uncontrolled release of active-C3, and Caspase-3 deposition on CD31+ graft vascular endothelial cells. These molecular changes are pathologically associated with microvascular deterioration (low tissue O2 and Blood flow) and subsequent airway epithelial injuries of rejecting allografts as compared to non-rejecting syngrafts. CONCLUSION Together, these findings establish a pathological correlation between complement dysregulation, T cell immunity, and microvascular associated injuries during alloimmune inflammation in transplantation.
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Affiliation(s)
- Mohammad Afzal Khan
- Organ Transplant Research Section, Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia.
| | - Talal Shamma
- Organ Transplant Research Section, Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Shadab Kazmi
- Organ Transplant Research Section, Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Abdullah Altuhami
- Organ Transplant Research Section, Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Hala Abdalrahman Ahmed
- Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Abdullah Mohammed Assiri
- Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia.,College of Medicine, Alfaisal University, Riyadh, Kingdom of Saudi Arabia.,Institute for Research and Medical Consultations, Imam Abdulrahman Bin Faisal University, Dammam, Kingdom of Saudi Arabia
| | - Dieter Clemens Broering
- Organ Transplant Research Section, Comparative Medicine Department, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
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8
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Lo MW, Woodruff TM. Complement: Bridging the innate and adaptive immune systems in sterile inflammation. J Leukoc Biol 2020; 108:339-351. [PMID: 32182389 DOI: 10.1002/jlb.3mir0220-270r] [Citation(s) in RCA: 44] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2019] [Revised: 02/07/2020] [Accepted: 02/19/2020] [Indexed: 12/24/2022] Open
Abstract
The complement system is a collection of soluble and membrane-bound proteins that together act as a powerful amplifier of the innate and adaptive immune systems. Although its role in infection is well established, complement is becoming increasingly recognized as a key contributor to sterile inflammation, a chronic inflammatory process often associated with noncommunicable diseases. In this context, damaged tissues release danger signals and trigger complement, which acts on a range of leukocytes to augment and bridge the innate and adaptive immune systems. Given the detrimental effect of chronic inflammation, the complement system is therefore well placed as an anti-inflammatory drug target. In this review, we provide a general outline of the sterile activators, effectors, and targets of the complement system and a series of examples (i.e., hypertension, cancer, allograft transplant rejection, and neuroinflammation) that highlight complement's ability to bridge the 2 arms of the immune system.
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Affiliation(s)
- Martin W Lo
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, Brisbane, Queensland, Australia
| | - Trent M Woodruff
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, Brisbane, Queensland, Australia
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9
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Abstract
The complement system is an evolutionarily ancient key component of innate immunity required for the detection and removal of invading pathogens. It was discovered more than 100 years ago and was originally defined as a liver-derived, blood-circulating sentinel system that classically mediates the opsonization and lytic killing of dangerous microbes and the initiation of the general inflammatory reaction. More recently, complement has also emerged as a critical player in adaptive immunity via its ability to instruct both B and T cell responses. In particular, work on the impact of complement on T cell responses led to the surprising discoveries that the complement system also functions within cells and is involved in regulating basic cellular processes, predominantly those of metabolic nature. Here, we review current knowledge about complement's role in T cell biology, with a focus on the novel intracellular and noncanonical activities of this ancient system.
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Affiliation(s)
- Erin E West
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, United States; ,
| | - Martin Kolev
- Division of Transplant Immunology and Mucosal Biology, King's College London, London SE1 9RT, United Kingdom;
| | - Claudia Kemper
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, United States; , .,Division of Transplant Immunology and Mucosal Biology, King's College London, London SE1 9RT, United Kingdom; .,Institute for Systemic Inflammation Research, University of Lübeck, 23562 Lübeck, Germany
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10
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Chun N, Horwitz J, Heeger PS. Role of Complement Activation in Allograft Inflammation. CURRENT TRANSPLANTATION REPORTS 2019; 6:52-59. [PMID: 31673484 PMCID: PMC6822566 DOI: 10.1007/s40472-019-0224-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
PURPOSE Novel paradigms have broadened our understanding of mechanisms through which complement mediates allograft inflammation/injury. Herein we review advances in the field and highlight therapeutic implications. RECENT FINDINGS Pre-clinical and translational human trials have elucidated complement-dependent mechanisms of post-transplant ischemia-reperfusion (I/R) injury. Immune cell-derived, and intracellular, complement activation are newly linked to proinflammatory T cell immunity relevant to allograft rejection. Complement-induced immune regulation, including C5a ligation of C5a receptor 2 on T cells, C5a/C5a receptor 1 interactions on regulatory myeloid cells, and C1q binding to CD8+ T cells can inhibit proinflammatory T cells and/or prolong murine allograft survival. Pilot trials of complement inhibition to treat/prevent human I/R- or antibody-initiated allograft injury show promise. SUMMARY The complement system participates in allograft injury through multiple context- dependent mechanisms involving various components and receptors. These new insights along with development and implementation of individualized complement inhibitory strategies have potential to improve transplant outcomes.
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Affiliation(s)
- Nicholas Chun
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai
- Division of Nephrology in the Department of Medicine, Icahn School of Medicine at Mount Sinai
| | - Julian Horwitz
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai
- The Precision Institute of Immunology, Icahn School of Medicine at Mount Sinai
| | - Peter S Heeger
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai
- Division of Nephrology in the Department of Medicine, Icahn School of Medicine at Mount Sinai
- The Precision Institute of Immunology, Icahn School of Medicine at Mount Sinai
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11
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Llaudo I, Fribourg M, Medof ME, Conde P, Ochando J, Heeger PS. C5aR1 regulates migration of suppressive myeloid cells required for costimulatory blockade-induced murine allograft survival. Am J Transplant 2019; 19:633-645. [PMID: 30106232 PMCID: PMC6375810 DOI: 10.1111/ajt.15072] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 07/17/2018] [Accepted: 07/31/2018] [Indexed: 01/25/2023]
Abstract
Costimulatory blockade-induced murine cardiac allograft survival requires intragraft accumulation of CD11b+ Ly6Clo Ly6G- regulatory myeloid cells (Mregs) that expand regulatory T cells (Tregs) and suppress effector T cells (Teffs). We previously showed that C5a receptor (C5aR1) signaling on T cells activates Teffs and inhibits Tregs, but whether and/or how C5aR1 affects Mregs required for transplant survival is unknown. Although BALB/c hearts survived >60 days in anti-CD154 (MR1)-treated or cytotoxic T-lymphocyte associated protein 4 (CTLA4)-Ig-treated wild-type (WT) recipients, they were rejected at ~30 days in MR1-treated or CTLA4-Ig-treated recipients selectively deficient in C5aR1 restricted to myeloid cells (C5ar1fl/fl xLysM-Cre). This accelerated rejection was associated with ~2-fold more donor-reactive T cells and ~40% less expansion of donor-reactive Tregs. Analysis of graft-infiltrating mononuclear cells on posttransplant day 6 revealed fewer Ly6Clo monocytes in C5ar1fl/fl xLysM-Cre recipients. Expression profiling of intragraft Ly6Clo monocytes showed that C5aR1 deficiency downregulated genes related to migration/locomotion without changes in genes associated with suppressive function. Cotransfer of C5ar1fl/fl and C5ar1fl/fl xLysM-Cre myeloid cells into MR1-treated allograft recipients resulted in less accumulation of C5ar1-/- cells within the allografts, and in vitro assays confirmed that Ly6Chi myeloid cells migrate to C5a/C5aR1-initiated signals. Together, our results newly link myeloid cell-expressed C5aR1 to intragraft accumulation of myeloid cells required for prolongation of heart transplant survival induced by costimulatory blockade.
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Affiliation(s)
- Ines Llaudo
- Translational Transplant Research Center,,Department of Medicine, and Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY
| | - Miguel Fribourg
- Translational Transplant Research Center,,Department of Neurology, Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY
| | - M. Edward Medof
- Institute of Pathology, Case Western Reserve University, Cleveland OH
| | - Patricia Conde
- Department of Medicine, and Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY
| | - Jordi Ochando
- Department of Medicine, and Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY
| | - Peter S. Heeger
- Translational Transplant Research Center,,Department of Medicine, and Immunology Institute Icahn School of Medicine at Mount Sinai, New York, NY
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12
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Horwitz JK, Chun NH, Heeger PS. Complement and Transplantation: From New Mechanisms to Potential Biomarkers and Novel Treatment Strategies. Clin Lab Med 2018; 39:31-43. [PMID: 30709507 DOI: 10.1016/j.cll.2018.10.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The complement system, traditionally considered a component of innate immunity, is now recognized as a crucial mediator of the adaptive immune response in solid organ transplantation. Preclinical and early human trials have demonstrated the importance of complement effector mechanisms in driving allograft injury during specific antigraft immune responses, including ischemia-reperfusion injury, T-cell-mediated rejection, and antibody-mediated rejection, as well as a potential role for complement-derived risk stratification biomarkers. These data support the need for further testing of complement inhibitors in solid organ transplant recipients.
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Affiliation(s)
- Julian K Horwitz
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA; Department of Surgery, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA
| | - Nicholas H Chun
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA; Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA
| | - Peter S Heeger
- Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA; Department of Medicine, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA; The Precision Institute of Immunology, Icahn School of Medicine at Mount Sinai, One Gustave L Levy Place, New York, NY 10029, USA.
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13
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Verghese DA, Chun N, Paz K, Fribourg M, Woodruff TM, Flynn R, Hu Y, Xiong H, Zhang W, Yi Z, Du J, Blazar BR, Heeger PS. C5aR1 regulates T follicular helper differentiation and chronic graft-versus-host disease bronchiolitis obliterans. JCI Insight 2018; 3:124646. [PMID: 30568034 DOI: 10.1172/jci.insight.124646] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/06/2018] [Indexed: 01/17/2023] Open
Abstract
CD4+ follicular helper T (Tfh) cells are specialized providers of T cell help to B cells and can function as pathogenic mediators of murine antibody-dependent chronic graft-versus-host disease (GvHD). Using a parent→F1 model of lupus-like chronic GvHD, in which Tfh cell and germinal center (GC) B cell differentiation occurs over 14 days, we demonstrate that absence of CD4+ T cell-expressed C5a receptor 1 (C5ar1) or pharmacological C5aR1 blockade abrogated generation/expansion of Tfh cells, GC B cells, and autoantibodies. In a Tfh cell-dependent model of chronic GvHD manifested by bronchiolitis obliterans syndrome (BOS), C5aR1 antagonism initiated in mice with established disease ameliorated BOS and abolished the associated differentiation of Tfh and GC B cells. Guided by RNA-sequencing data, mechanistic studies performed using murine and human T cells showed that C5aR1 signaling amplifies IL-6-dependent expression of the transcription factor c-MAF and the cytokine IL-21 via phosphorylating phosphokinase B (AKT) and activating the mammalian target of rapamycin (mTOR). In addition to linking C5aR1-initiated signaling to Tfh cell differentiation, our findings suggest that C5aR1 may be a useful therapeutic target for prevention and/or treatment of individuals with Tfh cell-dependent diseases, including those chronic GvHD patients who have anti-host reactive antibodies.
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Affiliation(s)
- Divya A Verghese
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Nicholas Chun
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Katelyn Paz
- Division of Blood and Marrow Transplant, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Miguel Fribourg
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Trent M Woodruff
- School of Biomedical Sciences, University of Queensland, St. Lucia, Queensland, Brisbane, Australia
| | - Ryan Flynn
- Division of Blood and Marrow Transplant, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yuan Hu
- Precision Institute, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Huabao Xiong
- Precision Institute, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Weijia Zhang
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Zhengzi Yi
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Jing Du
- Division of Blood and Marrow Transplant, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Bruce R Blazar
- Division of Blood and Marrow Transplant, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
| | - Peter S Heeger
- Department of Medicine, Translational Transplant Research Center, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA.,Precision Institute, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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14
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Khan MA, Shamma T. Complement factor and T-cell interactions during alloimmune inflammation in transplantation. J Leukoc Biol 2018; 105:681-694. [PMID: 30536904 DOI: 10.1002/jlb.5ru0718-288r] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 10/25/2018] [Accepted: 11/21/2018] [Indexed: 02/06/2023] Open
Abstract
Complement factor and T-cell signaling during an effective alloimmune response plays a key role in transplant-associated injury, which leads to the progression of chronic rejection (CR). During an alloimmune response, activated complement factors (C3a and C5a) bind to their corresponding receptors (C3aR and C5aR) on a number of lymphocytes, including T-regulatory cells (Tregs), and these cell-molecular interactions have been vital to modulate an effective immune response to/from Th1-effector cell and Treg activities, which result in massive inflammation, microvascular impairments, and fibrotic remodeling. Involvement of the complement-mediated cell signaling during transplantation signifies a crucial role of complement components as a key therapeutic switch to regulate ongoing inflammatory state, and further to avoid the progression of CR of the transplanted organ. This review highlights the role of complement-T cell interactions, and how these interactions shunt the effector immune response during alloimmune inflammation in transplantation, which could be a novel therapeutic tool to protect a transplanted organ and avoid progression of CR.
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Affiliation(s)
- Mohammad Afzal Khan
- Organ Transplant Research Section, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
| | - Talal Shamma
- Organ Transplant Research Section, King Faisal Specialist Hospital and Research Centre, Riyadh, Kingdom of Saudi Arabia
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15
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Kolev M, Markiewski MM. Targeting complement-mediated immunoregulation for cancer immunotherapy. Semin Immunol 2018; 37:85-97. [PMID: 29454575 PMCID: PMC5984681 DOI: 10.1016/j.smim.2018.02.003] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Revised: 01/31/2018] [Accepted: 02/02/2018] [Indexed: 12/21/2022]
Abstract
Complement was initially discovered as an assembly of plasma proteins "complementing" the cytolytic activity of antibodies. However, our current knowledge places this complex system of several plasma proteins, receptors, and regulators in the center of innate immunity as a bridge between the initial innate responses and adaptive immune reactions. Consequently, complement appears to be pivotal for elimination of pathogens, not only as an early response defense, but by directing the subsequent adaptive immune response. The discovery of functional intracellular complement and its roles in cellular metabolism opened novel avenues for research and potential therapeutic implications. The recent studies demonstrating immunoregulatory functions of complement in the tumor microenvironment and the premetastatic niche shifted the paradigm on our understanding of functions of the complement system in regulating immunity. Several complement proteins, through their interaction with cells in the tumor microenvironment and in metastasis-targeted organs, contribute to modulating tumor growth, antitumor immunity, angiogenesis, and therefore, the overall progression of malignancy and, perhaps, responsiveness of cancer to different therapies. Here, we focus on recent progress in our understanding of immunostimulatory vs. immunoregulatory functions of complement and potential applications of these findings to the design of novel therapies for cancer patients.
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Affiliation(s)
- Martin Kolev
- Complement and Inflammation Research Section, DIR, NHLBI, NIH, Bethesda, MD, 20892, United States.
| | - Maciej M Markiewski
- Department of Immunotherapeutics and Biotechnology, School of Pharmacy, Texas Tech University Health Sciences Center, Abilene, TX, 79601, United States.
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16
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West EE, Afzali B, Kemper C. Unexpected Roles for Intracellular Complement in the Regulation of Th1 Responses. Adv Immunol 2018; 138:35-70. [PMID: 29731006 DOI: 10.1016/bs.ai.2018.02.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The complement system is generally recognized as an evolutionarily ancient and critical part of innate immunity required for the removal of pathogens that have breached the protective host barriers. It was originally defined as a liver-derived serum surveillance system that induces the opsonization and killing of invading microbes and amplifies the general inflammatory reactions. However, studies spanning the last four decades have established complement also as a vital bridge between innate and adaptive immunity. Furthermore, recent work on complement, and in particular its impact on human T helper 1 (Th1) responses, has led to the unexpected findings that the complement system also functions within cells and that it participates in the regulation of basic processes of the cell, including metabolism. These recent new insights into the unanticipated noncanonical activities of this ancient system suggest that the functions of complement extend well beyond mere host protection and into cellular physiology.
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Affiliation(s)
- Erin E West
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung and Blood Institute, Bethesda, MD, United States
| | - Behdad Afzali
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung and Blood Institute, Bethesda, MD, United States; Lymphocyte Cell Biology Section (Molecular Immunology and Inflammation Branch), National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Claudia Kemper
- Laboratory of Molecular Immunology and Immunology Center, National Heart, Lung and Blood Institute, Bethesda, MD, United States; Division of Transplant Immunology and Mucosal Biology, King's College London, London, United Kingdom; Institute for Systemic Inflammation Research, University of Lübeck, Lübeck, Germany.
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17
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Freeley S, Kemper C, Le Friec G. The "ins and outs" of complement-driven immune responses. Immunol Rev 2017; 274:16-32. [PMID: 27782335 DOI: 10.1111/imr.12472] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The complement system represents an evolutionary old and critical component of innate immunity where it forms the first line of defense against invading pathogens. Originally described as a heat-labile fraction of the serum responsible for the opsonization and subsequent lytic killing of bacteria, work over the last century firmly established complement as a key mediator of the general inflammatory response but also as an acknowledged vital bridge between innate and adaptive immunity. However, recent studies particularly spanning the last decade have provided new insights into the novel modes and locations of complement activation and highlighted unexpected additional biological functions for this ancient system, for example, in regulating basic processes of the cell. In this review, we will cover the current knowledge about complement's established and novel roles in innate and adaptive immunity with a focus on the functional differences between serum circulating and intracellularly active complement and will describe and discuss the newly discovered cross-talks of complement with other cell effector systems particularly during T-cell induction and contraction.
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Affiliation(s)
- Simon Freeley
- Division of Transplant Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, Guy's Hospital, London, UK
| | - Claudia Kemper
- Division of Transplant Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, Guy's Hospital, London, UK. .,Laboratory of Molecular Immunology and the Immunology Center, National Heart, Lung, and Blood Institute (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA.
| | - Gaëlle Le Friec
- Division of Transplant Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, Guy's Hospital, London, UK
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18
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Cernoch M, Viklicky O. Complement in Kidney Transplantation. Front Med (Lausanne) 2017; 4:66. [PMID: 28611987 PMCID: PMC5447724 DOI: 10.3389/fmed.2017.00066] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2017] [Accepted: 05/09/2017] [Indexed: 12/12/2022] Open
Abstract
The complement system is considered to be an important part of innate immune system with a significant role in inflammation processes. The activation can occur through classical, alternative, or lectin pathway, resulting in the creation of anaphylatoxins C3a and C5a, possessing a vast spectrum of immune functions, and the assembly of terminal complement cascade, capable of direct cell lysis. The activation processes are tightly regulated; inappropriate activation of the complement cascade plays a significant role in many renal diseases including organ transplantation. Moreover, complement cascade is activated during ischemia/reperfusion injury processes and influences delayed graft function of kidney allografts. Interestingly, complement system has been found to play a role in both acute cellular and antibody-mediated rejections and thrombotic microangiopathy. Therefore, complement system may represent an interesting therapeutical target in kidney transplant pathologies.
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Affiliation(s)
- Marek Cernoch
- Transplant Laboratory, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia
| | - Ondrej Viklicky
- Transplant Laboratory, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia.,Department of Nephrology, Transplant Center, Institute for Clinical and Experimental Medicine, Prague, Czechia
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19
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Sheen JH, Strainic MG, Liu J, Zhang W, Yi Z, Medof ME, Heeger PS. TLR-Induced Murine Dendritic Cell (DC) Activation Requires DC-Intrinsic Complement. THE JOURNAL OF IMMUNOLOGY 2017; 199:278-291. [PMID: 28539427 DOI: 10.4049/jimmunol.1700339] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 05/04/2017] [Indexed: 01/04/2023]
Abstract
Induction of proinflammatory T cell immunity is augmented by innate dendritic cell (DC) maturation commonly initiated by TLR signaling. We demonstrate that ligation of TLR3, TLR4, and TLR9 induces murine DC production of complement components and local production of the anaphylatoxin C5a. In vitro, ex vivo, and in vivo analyses show that TLR-induced DC maturation, as assessed by surface phenotype, expression profiling by gene array, and functional ability to stimulate T cell responses, requires autocrine C3a receptor and C5a receptor (C3ar1/C5ar1) signaling. Studies using bone marrow chimeric animals and Foxp3-GFP/ERT2-Cre/dTomato fate-mapping mice show that TLR-initiated DC autocrine C3ar1/C5ar1 signaling causes expansion of effector T cells and instability of regulatory T cells and contributes to T cell-dependent transplant rejection. Together, our data position immune cell-derived complement production and autocrine/paracrine C3ar1/C5ar1 signaling as crucial intermediary processes that link TLR stimulation to DC maturation and the subsequent development of effector T cell responses.
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Affiliation(s)
- Joong-Hyuk Sheen
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029.,Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029.,Precision Institute of Immunology, Icahn School of Medicine at Mount Sinai, New York, NY 10029; and
| | - Michael G Strainic
- Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106
| | - Jinbo Liu
- Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106
| | - Weijia Zhang
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029.,Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Zhengzi Yi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029.,Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - M Edward Medof
- Institute of Pathology, Case Western Reserve University, Cleveland, OH 44106
| | - Peter S Heeger
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029; .,Translational Transplant Research Center, Icahn School of Medicine at Mount Sinai, New York, NY 10029.,Precision Institute of Immunology, Icahn School of Medicine at Mount Sinai, New York, NY 10029; and
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20
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Lubbers R, van Essen MF, van Kooten C, Trouw LA. Production of complement components by cells of the immune system. Clin Exp Immunol 2017; 188:183-194. [PMID: 28249350 DOI: 10.1111/cei.12952] [Citation(s) in RCA: 293] [Impact Index Per Article: 41.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/25/2017] [Indexed: 12/14/2022] Open
Abstract
The complement system is an important part of the innate immune defence. It contributes not only to local inflammation, removal and killing of pathogens, but it also assists in shaping of the adaptive immune response. Besides a role in inflammation, complement is also involved in physiological processes such as waste disposal and developmental programmes. The complement system comprises several soluble and membrane-bound proteins. The bulk of the soluble proteins is produced mainly by the liver. While several complement proteins are produced by a wide variety of cell types, other complement proteins are produced by only a few related cell types. As these data suggest that local production by specific cell types may have specific functions, more detailed studies have been employed recently analysing the local and even intracellular role of these complement proteins. Here we review the current knowledge about extrahepatic production and/or secretion of complement components. More specifically, we address what is known about complement synthesis by cells of the human immune system.
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Affiliation(s)
- R Lubbers
- Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
| | - M F van Essen
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - C van Kooten
- Department of Nephrology, Leiden University Medical Center, Leiden, the Netherlands
| | - L A Trouw
- Department of Rheumatology, Leiden University Medical Center, Leiden, the Netherlands
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21
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Valero-Hervás DM, Sánchez-Zapardiel E, Castro MJ, Gallego-Bustos F, Cambra F, Justo I, Laguna-Goya R, Jiménez-Romero C, Moreno E, López-Medrano F, San Juan R, Fernández-Ruiz M, Aguado JM, Paz-Artal E. Complement C3F allotype synthesized by liver recipient modifies transplantation outcome independently from donor hepatic C3. Clin Transplant 2016; 31. [PMID: 27801525 DOI: 10.1111/ctr.12866] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2016] [Indexed: 12/12/2022]
Abstract
Complement component 3 (C3) presents both slow (C3S) and fast (C3F) variants, which can be locally produced and activated by immune system cells. We studied C3 recipient variants in 483 liver transplant patients by RT-PCR-HRM to determine their effect on graft outcome during the first year post-transplantation. Allograft survival was significantly decreased in C3FF recipients (C3SS 95% vs C3FS 91% vs C3FF 83%; P=.01) or C3F allele carriers (C3F absence 95% vs C3F presence 90%, P=.02). C3FF genotype or presence of C3F allele independently increased risk for allograft loss (OR: 2.38, P=.005 and OR: 2.66, P=.02, respectively). C3FF genotype was more frequent among patients whose first infection was of viral etiology (C3SS 13% vs C3FS 18% vs C3FF 32%; P=.04) and independently increased risk for post-transplant viral infections (OR: 3.60, P=.008). On the other hand, C3FF and C3F protected from rejection events (OR: 0.54, P=.03 and OR: 0.63, P=.047, respectively). Differences were not observed in hepatitis C virus recurrence or patient survival. In conclusion, we show that, independently from C3 variants produced by donor liver, C3F variant from recipient diminishes allograft survival, increases susceptibility to viral infections, and protects from rejection after transplantation. C3 genotyping of liver recipients may be useful to stratify risk.
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Affiliation(s)
| | | | - María José Castro
- Department of Immunology, Hospital 12 de Octubre, Madrid, Spain.,I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain
| | | | - Félix Cambra
- Department of General and Digestive Surgery and Abdominal Organ Transplantation, Hospital 12 de Octubre, Madrid, Spain
| | - Iago Justo
- Department of General and Digestive Surgery and Abdominal Organ Transplantation, Hospital 12 de Octubre, Madrid, Spain
| | - Rocío Laguna-Goya
- Department of Immunology, Hospital 12 de Octubre, Madrid, Spain.,I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain
| | - Carlos Jiménez-Romero
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,Department of General and Digestive Surgery and Abdominal Organ Transplantation, Hospital 12 de Octubre, Madrid, Spain.,School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Enrique Moreno
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,Department of General and Digestive Surgery and Abdominal Organ Transplantation, Hospital 12 de Octubre, Madrid, Spain.,School of Medicine, Universidad Complutense de Madrid, Madrid, Spain
| | - Francisco López-Medrano
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,Unit of Infectious Diseases, Hospital 12 de Octubre, Madrid, Spain
| | - Rafael San Juan
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,Unit of Infectious Diseases, Hospital 12 de Octubre, Madrid, Spain
| | - Mario Fernández-Ruiz
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,Unit of Infectious Diseases, Hospital 12 de Octubre, Madrid, Spain
| | - José María Aguado
- I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,Unit of Infectious Diseases, Hospital 12 de Octubre, Madrid, Spain
| | - Estela Paz-Artal
- Department of Immunology, Hospital 12 de Octubre, Madrid, Spain.,I+12 Research Institute, Hospital 12 de Octubre, Madrid, Spain.,School of Medicine, Universidad Complutense de Madrid, Madrid, Spain.,Section of Immunology, Universidad San Pablo CEU, Madrid, Spain
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22
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Valenzuela NM, Hickey MJ, Reed EF. Antibody Subclass Repertoire and Graft Outcome Following Solid Organ Transplantation. Front Immunol 2016; 7:433. [PMID: 27822209 PMCID: PMC5075576 DOI: 10.3389/fimmu.2016.00433] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Accepted: 10/03/2016] [Indexed: 12/20/2022] Open
Abstract
Long-term outcomes in solid organ transplantation are constrained by the development of donor-specific alloantibodies (DSA) against human leukocyte antigen (HLA) and other targets, which elicit antibody-mediated rejection (ABMR). However, antibody-mediated graft injury represents a broad continuum, from extensive complement activation and tissue damage compromising the function of the transplanted organ, to histological manifestations of endothelial cell injury and mononuclear cell infiltration but without concurrent allograft dysfunction. In addition, while transplant recipients with DSA as a whole fare worse than those without, a substantial minority of patients with DSA do not experience poorer graft outcome. Taken together, these observations suggest that not all DSA are equally pathogenic. Antibody effector functions are controlled by a number of factors, including antibody concentration, antigen availability, and antibody isotype/subclass. Antibody isotype is specified by many integrated signals, including the antigen itself as well as from antigen-presenting cells or helper T cells. To date, a number of studies have described the repertoire of IgG subclasses directed against HLA in pretransplant patients and evaluated the clinical impact of different DSA IgG subclasses on allograft outcome. This review will summarize what is known about the repertoire of antibodies to HLA and non-HLA targets in transplantation, focusing on the distribution of IgG subclasses, as well as the general biology, etiology, and mechanisms of injury of different humoral factors.
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Affiliation(s)
- Nicole M Valenzuela
- UCLA Immunogenetics Center, University of California Los Angeles, Los Angeles, CA, USA; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Michelle J Hickey
- UCLA Immunogenetics Center, University of California Los Angeles, Los Angeles, CA, USA; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Elaine F Reed
- UCLA Immunogenetics Center, University of California Los Angeles, Los Angeles, CA, USA; Department of Pathology and Laboratory Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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23
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Abstract
Direct allorecognition is the process by which donor-derived major histocompatibility complex (MHC)-peptide complexes, typically presented by donor-derived ‘passenger’ dendritic cells, are recognised directly by recipient T cells. In this review, we discuss the two principle theories which have been proposed to explain why individuals possess a high-precursor frequency of T cells with direct allospecificity and how self-restricted T cells recognise allogeneic MHC-peptide complexes. These theories, both of which are supported by functional and structural data, suggest that T cells recognising allogeneic MHC-peptide complexes focus either on the allopeptides bound to the allo-MHC molecules or the allo-MHC molecules themselves. We discuss how direct alloimmune responses may be sustained long term, the consequences of this for graft outcome and highlight novel strategies which are currently being investigated as a potential means of reducing rejection mediated through this pathway.
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Affiliation(s)
- Dominic A Boardman
- MRC Centre for Transplantation, King's College London, Guy's Hospital, London, SE1 9RT UK ; NIHR Biomedical Research Centre, Guy's & St Thomas' NHS Foundation Trust & King's College London, Guy's Hospital, London, SE1 9RT UK
| | - Jacinta Jacob
- MRC Centre for Transplantation, King's College London, Guy's Hospital, London, SE1 9RT UK
| | - Lesley A Smyth
- MRC Centre for Transplantation, King's College London, Guy's Hospital, London, SE1 9RT UK ; School of Health, Sport and Bioscience, Stratford Campus, University of East London, London, E15 4LZ UK
| | - Giovanna Lombardi
- MRC Centre for Transplantation, King's College London, Guy's Hospital, London, SE1 9RT UK ; NIHR Biomedical Research Centre, Guy's & St Thomas' NHS Foundation Trust & King's College London, Guy's Hospital, London, SE1 9RT UK
| | - Robert I Lechler
- MRC Centre for Transplantation, King's College London, Guy's Hospital, London, SE1 9RT UK ; NIHR Biomedical Research Centre, Guy's & St Thomas' NHS Foundation Trust & King's College London, Guy's Hospital, London, SE1 9RT UK
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24
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González-Molina M, Ruiz-Esteban P, Caballero A, Burgos D, Cabello M, Leon M, Fuentes L, Hernandez D. Immune response and histology of humoral rejection in kidney transplantation. Nefrologia 2016; 36:354-67. [PMID: 27267916 DOI: 10.1016/j.nefro.2016.03.023] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 02/22/2016] [Accepted: 03/26/2016] [Indexed: 11/15/2022] Open
Abstract
The adaptive immune response forms the basis of allograft rejection. Its weapons are direct cellular cytotoxicity, identified from the beginning of organ transplantation, and/or antibodies, limited to hyperacute rejection by preformed antibodies and not as an allogenic response. This resulted in allogenic response being thought for decades to have just a cellular origin. But the experimental studies by Gorer demonstrating tissue damage in allografts due to antibodies secreted by B lymphocytes activated against polymorphic molecules were disregarded. The special coexistence of binding and unbinding between antibodies and antigens of the endothelial cell membranes has been the cause of the delay in demonstrating the humoral allogenic response. The endothelium, the target tissue of antibodies, has a high turnover, and antigen-antibody binding is non-covalent. If endothelial cells are attacked by the humoral response, immunoglobulins are rapidly removed from their surface by shedding and/or internalization, as well as degrading the components of the complement system by the action of MCP, DAF and CD59. Thus, the presence of complement proteins in the membrane of endothelial cells is transient. In fact, the acute form of antibody-mediated rejection was not demonstrated until C4d complement fragment deposition was identified, which is the only component that binds covalently to endothelial cells. This review examines the relationship between humoral immune response and the types of acute and chronic histological lesion shown on biopsy of the transplanted organ.
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Affiliation(s)
- Miguel González-Molina
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain.
| | - Pedro Ruiz-Esteban
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Abelardo Caballero
- Immunology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Dolores Burgos
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Mercedes Cabello
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Miriam Leon
- Pathology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Laura Fuentes
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
| | - Domingo Hernandez
- Nephrology Department, Regional University Hospital of Malaga, Malaga University, IBIMA, REDINREN RD12/0021/0015, Malaga, Spain
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25
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Hypodermin A improves survival of skin allografts. J Surg Res 2016; 203:15-21. [DOI: 10.1016/j.jss.2016.03.037] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Revised: 03/11/2016] [Accepted: 03/16/2016] [Indexed: 01/23/2023]
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Montero RM, Sacks SH, Smith RA. Complement-here, there and everywhere, but what about the transplanted organ? Semin Immunol 2016; 28:250-9. [PMID: 27179705 DOI: 10.1016/j.smim.2016.04.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 04/20/2016] [Accepted: 04/26/2016] [Indexed: 12/15/2022]
Abstract
The part of the innate immune system that communicates and effectively primes the adaptive immune system was termed "complement" by Ehrlich to reflect its complementarity to antibodies having previously been described as "alexine" (i.e protective component of serum) by Buchner and Bordet. It has been established that complement is not solely produced systemically but may have origin in different tissues where it can influence organ specific functions that may affect the outcome of transplanted organs. This review looks at the role of complement in particular to kidney transplantation. We look at current literature to determine whether blockade of the peripheral or central compartments of complement production may prevent ischaemic reperfusion injury or rejection in the transplanted organ. We also review new therapeutics that have been developed to inhibit components of the complement cascade with varying degrees of success leading to an increase in our understanding of the multiple triggers of this complex system. In addition, we consider whether biomarkers in this field are effective markers of disease or treatment.
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Affiliation(s)
- R M Montero
- MRC Centre for Transplantation, Division of Transplant Immunology and Mucosal Biology, NIHR Comprehensive Biomedical Research Centre, King's College London, Guy's & St Thomas' NHS Foundation Trust, United Kingdom
| | - S H Sacks
- MRC Centre for Transplantation, Division of Transplant Immunology and Mucosal Biology, NIHR Comprehensive Biomedical Research Centre, King's College London, Guy's & St Thomas' NHS Foundation Trust, United Kingdom.
| | - R A Smith
- MRC Centre for Transplantation, Division of Transplant Immunology and Mucosal Biology, NIHR Comprehensive Biomedical Research Centre, King's College London, Guy's & St Thomas' NHS Foundation Trust, United Kingdom
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27
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Ermini L, Weale ME, Brown KM, Mesa IR, Howell WM, Vaughan R, Chowdhury P, Sacks SH, Sheerin NS. Systematic assessment of the influence of complement gene polymorphisms on kidney transplant outcome. Immunobiology 2015; 221:528-34. [PMID: 26797657 DOI: 10.1016/j.imbio.2015.12.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 12/10/2015] [Indexed: 01/01/2023]
Abstract
The importance of the innate immune system, including complement, in causing transplant injury and augmenting adaptive immune responses is increasingly recognized. Therefore variability in graft outcome may in part be due to genetic polymorphism in genes encoding proteins of the immune system. This study assessed the relationship between single nucleotide polymorphisms (SNPs) in complement genes and outcome after transplantation. Analysis was performed on two patient cohorts of 650 and 520 transplant recipients. 505 tagged SNPs in 47 genes were typed in both donor and recipient. The relationships between SNPs and graft survival, serum creatinine, delayed graft function and acute rejection were analyzed. One recipient SNP in the gene encoding mannose binding lectin was associated with graft outcome after correction for analysis of multiple SNPs (p=6.41 × 10(-5)). When further correction was applied to account for analysis of the effect of SNPs in both donor and recipient this lost significance. Despite association p values of <0.001 no SNP was significantly associated with clinical phenotypes after Bonferroni correction. In conclusion, the variability seen in transplant outcome in this patient cohort cannot be explained by variation in complement genes. If causal genetic effects exist in these genes, they are too small to be detected by this study.
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Affiliation(s)
- Luca Ermini
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
| | - Michael E Weale
- Department of Medical and Molecular Genetics, King's College, London SE1 9RT, UK.
| | | | - Irene Rebollo Mesa
- Department of Medical and Molecular Genetics, King's College, London SE1 9RT, UK.
| | | | - Robert Vaughan
- Clinical Transplantation Laboratory, GSTS Pathology, Guy's Hospital, London SE1 9RT, UK.
| | | | - Steven H Sacks
- MRC Centre for Transplantation, King's College, London SE1 9RT, UK.
| | - Neil S Sheerin
- Institute of Cellular Medicine, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
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28
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Abstract
PURPOSE OF REVIEW To summarize the current knowledge regarding mechanisms linking the complement system to transplant injury, highlighting findings reported since 2013. RECENT FINDINGS Building upon the documentation that complement activation is a pathogenic mediator of posttransplant ischemia-reperfusion injury, emerging evidence from animal models indicates that blocking either the classical or lectin pathways attenuates ischemia-reperfusion injury. Immune cell-derived and locally activated complement, including intracellular C3, positively modulates alloreactive T-cell activation and expansion, whereby simultaneously inhibiting regulatory T-cell induction and function, and together promoting transplant rejection. Although alloantibody-initiated complement activation directly injures target cells, complement-dependent signals activate endothelial cells to facilitate T-cell-dependent inflammation. Complement activation within allografts contributes to progressive chronic injury and fibrosis. SUMMARY The complement cascade, traditionally considered to be relevant to transplantation only as an effector mechanism of antibody-initiated allograft injury, is now understood to damage the allograft through multiple mechanisms. Complement activation promotes posttransplant ischemia-reperfusion injury, formation and function of alloantibody, differentiation and function of alloreactive T cells, and contributes to chronic progressive allograft failure. The recognition that complement affects transplant injury at many levels provides a foundation for targeting complement as a therapy to prolong transplant survival and improve patient health.
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29
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Mathern DR, Heeger PS. Molecules Great and Small: The Complement System. Clin J Am Soc Nephrol 2015; 10:1636-50. [PMID: 25568220 DOI: 10.2215/cjn.06230614] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The complement cascade, traditionally considered an effector arm of innate immunity required for host defense against pathogens, is now recognized as a crucial pathogenic mediator of various kidney diseases. Complement components produced by the liver and circulating in the plasma undergo activation through the classical and/or mannose-binding lectin pathways to mediate anti-HLA antibody-initiated kidney transplant rejection and autoantibody-initiated GN, the latter including membranous glomerulopathy, antiglomerular basement membrane disease, and lupus nephritis. Inherited and/or acquired abnormalities of complement regulators, which requisitely limit restraint on alternative pathway complement activation, contribute to the pathogenesis of the C3 nephropathies and atypical hemolytic uremic syndrome. Increasing evidence links complement produced by endothelial cells and/or tubular cells to the pathogenesis of kidney ischemia-reperfusion injury and progressive kidney fibrosis. Data emerging since the mid-2000s additionally show that immune cells, including T cells and antigen-presenting cells, produce alternative pathway complement components during cognate interactions. The subsequent local complement activation yields production of the anaphylatoxins C3a and C5a, which bind to their respective receptors (C3aR and C5aR) on both partners to augment effector T-cell proliferation and survival, while simultaneously inhibiting regulatory T-cell induction and function. This immune cell-derived complement enhances pathogenic alloreactive T-cell immunity that results in transplant rejection and likely contributes to the pathogenesis of other T cell-mediated kidney diseases. C5a/C5aR ligations on neutrophils have additionally been shown to contribute to vascular inflammation in models of ANCA-mediated renal vasculitis. New translational immunology efforts along with the development of pharmacologic agents that block human complement components and receptors now permit testing of the intriguing concept that targeting complement in patients with an assortment of kidney diseases has the potential to abrogate disease progression and improve patient health.
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Affiliation(s)
- Douglas R Mathern
- Translational Transplant Research Center, Department of Medicine, Recanati Miller Transplant Institute, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Peter S Heeger
- Translational Transplant Research Center, Department of Medicine, Recanati Miller Transplant Institute, Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, New York
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Abstract
Complement is traditionally known to be a system of serum proteins that provide protection against pathogens through direct cell lysis and the mobilization of innate and adaptive immunity. However, recent work indicates that the complement system has additional physiological roles beyond those in host defence. In this Opinion article, we describe the new modes and locations of complement activation that enable it to interact with other cell effector systems, such as growth factor receptors, inflammasomes and metabolic pathways. We propose that the location of complement activation dictates its function.
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31
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Clarke EV, Tenner AJ. Complement modulation of T cell immune responses during homeostasis and disease. J Leukoc Biol 2014; 96:745-56. [PMID: 25210145 DOI: 10.1189/jlb.3mr0214-109r] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The complement system is an ancient and critical effector mechanism of the innate immune system as it senses, kills, and clears infectious and/or dangerous particles and alerts the immune system to the presence of the infection and/or danger. Interestingly, an increasing number of reports have demonstrated a clear role for complement in the adaptive immune system as well. Of note, a number of recent studies have identified previously unknown roles for complement proteins, receptors, and regulators in T cell function. Here, we will review recent data demonstrating the influence of complement proteins C1q, C3b/iC3b, C3a (and C3aR), and C5a (and C5aR) and complement regulators DAF (CD55) and CD46 (MCP) on T cell function during homeostasis and disease. Although new concepts are beginning to emerge in the field of complement regulation of T cell function, future experiments should focus on whether complement is interacting directly with the T cell or is having an indirect effect on T cell function via APCs, the cytokine milieu, or downstream complement activation products. Importantly, the identification of the pivotal molecular pathways in the human systems will be beneficial in the translation of concepts derived from model systems to therapeutic targeting for treatment of human disorders.
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Affiliation(s)
- Elizabeth V Clarke
- Department of Molecular Biology and Biochemistry and Institute for Immunology, University of California, Irvine, California, USA
| | - Andrea J Tenner
- Department of Molecular Biology and Biochemistry and Institute for Immunology, University of California, Irvine, California, USA
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32
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Tan Y, Li Y, Fu X, Yang F, Zheng P, Zhang J, Guo B, Wu Y. Systemic C3 modulates CD8+ T cell contraction after Listeria monocytogenes infection. THE JOURNAL OF IMMUNOLOGY 2014; 193:3426-35. [PMID: 25187659 DOI: 10.4049/jimmunol.1302763] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Ag-specific CD8(+) T cell contraction (contraction), which occurs after the resolution of infection, is critical for homeostasis of the immune system. Although complement components regulate the primary CD8(+) T cell response, there is insufficient evidence supporting their role in regulating contraction and memory. In this study, we show that C3-deficient (C3(-/-)) mice exhibited significantly less CD8(+) T cell contraction than did wild-type mice postinfection with recombinant Listeria monocytogenes expressing OVA. Kinetic analyses also revealed decreased contraction in mice treated with cobra venom factor to deplete C3, which was consistent with the results in C3(-/-) recipient mice transplanted with bone marrow cells from the same donors as wild-type recipient mice. The phenotypes of memory cells generated by C3(-/-) mice were not altered compared with those of wild-type mice. Further, C5aR signaling downstream of C3 was not involved in the regulation of contraction. Moreover, the regulation of contraction by C3 may be independent of the duration of antigenic stimulation or the functional avidity of effector CD8(+) T cells. However, reduced contraction in C3(-/-) mice was accompanied by a decrease in the proportion of KLRG-1(hi) (killer-cell lectin-like receptor G1) CD127(lo) short-lived effector cells at the peak of the response and correlated with a reduction in the levels of inflammatory cytokines, such as IL-12 and IFN-γ, produced early postinfection. These results provide new insights into the role of systemic C3 in regulating contraction following intracellular bacterial infection and may help to develop vaccines that are more effective.
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Affiliation(s)
- Yulong Tan
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
| | - Yongsheng Li
- Institute of Cancer, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Xiaolan Fu
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
| | - Fei Yang
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
| | - Ping Zheng
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
| | - Jue Zhang
- Institute of Cancer, Xinqiao Hospital, Third Military Medical University, Chongqing 400037, China
| | - Bo Guo
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
| | - Yuzhang Wu
- Department of Immunology, Third Military Medical University, Chongqing 400038, China; and
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Abstract
Complement proteins are generated both by the liver (systemic compartment) and by peripheral tissue-resident cells and migratory immune cells (local compartment). The immune cell-derived, alternative pathway complement components activate spontaneously, yielding local, but not systemic, production of C3a and C5a. These anaphylatoxins bind to their respective G-protein-coupled receptors, the C3a receptor and the C5a receptor, expressed on T cells and antigen-presenting cells, leading to their reciprocal activation and driving T-cell differentiation, expansion, and survival. Complement deficiency or blockade attenuates T-cell-mediated autoimmunity and delays allograft rejection in mice. Increasing complement activation, achieved by genetic removal of the complement regulatory protein decay accelerating factor, enhances murine T-cell immunity and accelerates allograft rejection. Signaling through the C3a receptor and the C5a receptor reduces suppressive activity of natural regulatory T cells and the generation and stability of induced regulatory T cells. The concepts, initially generated in mice, recently were confirmed in human immune cells, supporting the need for testing of complement targeting therapies in organ transplants patients.
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Affiliation(s)
- Paolo Cravedi
- Department of Medicine, Recanati Miller Transplant Institute and Immunology Institute, Icahn School of Medicine at Mount Sinai, New York, NY
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34
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Cravedi P, Heeger PS. Complement as a multifaceted modulator of kidney transplant injury. J Clin Invest 2014; 124:2348-54. [PMID: 24892709 DOI: 10.1172/jci72273] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Improvements in clinical care and immunosuppressive medications have positively affected outcomes following kidney transplantation, but graft survival remains suboptimal, with half-lives of approximately 11 years. Late graft loss results from a confluence of processes initiated by ischemia-reperfusion injury and compounded by effector mechanisms of uncontrolled alloreactive T cells and anti-HLA antibodies. When combined with immunosuppressant toxicity, post-transplant diabetes and hypertension, and recurrent disease, among other factors, the result is interstitial fibrosis, tubular atrophy, and graft failure. Emerging evidence over the last decade unexpectedly identified the complement cascade as a common thread in this process. Complement activation and function affects allograft injury at essentially every step. These fundamental new insights, summarized herein, provide the foundation for testing the efficacy of various complement antagonists to improve kidney transplant function and long-term graft survival.
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35
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Touzot M, Obada EN, Beaudreuil S, François H, Durrbach A. Complement modulation in solid-organ transplantation. Transplant Rev (Orlando) 2014; 28:119-25. [PMID: 24996770 DOI: 10.1016/j.trre.2014.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Accepted: 03/08/2014] [Indexed: 01/18/2023]
Abstract
The complement system is a major constituent of the innate immune system. It has a critical role in defense against pathogens but dysregulation of complement activation may lead to tissue injury and modulate the adaptive immune response. In organ transplantation, local complement activation is involved in hyper-acute rejection and antibody-mediated rejection. This last decade, interest in complement activation has increased due to new insights into the pathophysiology of antibody-mediated rejection, but also since the availability of news drugs that target terminal complement activation. In this review, we discuss our current understanding of how local complement activation induces acute and chronic graft injury, and review recent advances in clinical trials that block complement activation using the anti-C5 monoclonal antibody, eculizumab. Finally, we discuss how complement-targeted therapy may be integrated into our current immunosuppressive regimen and what type of patient will benefit most from this therapy.
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Affiliation(s)
- Maxime Touzot
- Nephrology Department, IFRNT, Le Kremlin-Bicêtre, France; Institut National de la Santé et de la Recherche Médicale INSERM U1014, Villejuif, France
| | | | - Severine Beaudreuil
- Nephrology Department, IFRNT, Le Kremlin-Bicêtre, France; Institut National de la Santé et de la Recherche Médicale INSERM U1014, Villejuif, France
| | - Hélène François
- Nephrology Department, IFRNT, Le Kremlin-Bicêtre, France; Institut National de la Santé et de la Recherche Médicale INSERM U1014, Villejuif, France
| | - Antoine Durrbach
- Nephrology Department, IFRNT, Le Kremlin-Bicêtre, France; Institut National de la Santé et de la Recherche Médicale INSERM U1014, Villejuif, France.
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36
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The role of decay accelerating factor in environmentally induced and idiopathic systemic autoimmune disease. Autoimmune Dis 2014; 2014:452853. [PMID: 24592327 PMCID: PMC3921935 DOI: 10.1155/2014/452853] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 11/19/2013] [Indexed: 01/05/2023] Open
Abstract
Decay accelerating factor (DAF) plays a complex role in the immune system through complement-dependent and -independent regulation of innate and adaptive immunity. Over the past five years there has been accumulating evidence for a significant role of DAF in negatively regulating adaptive T-cell responses and autoimmunity in both humans and experimental models. This review discusses the relationship between DAF and the complement system and highlights major advances in our understanding of the biology of DAF in human disease, particularly systemic lupus erythematosus. The role of DAF in regulation of idiopathic and environmentally induced systemic autoimmunity is discussed including studies showing that reduction or absence of DAF is associated with autoimmunity. In contrast, DAF-mediated T cell activation leads to cytokine expression consistent with T regulatory cells. This is supported by studies showing that interaction between DAF and its molecular partner, CD97, modifies expression of autoimmunity promoting cytokines. These observations are used to develop a hypothetical model to explain how DAF expression may impact T cell differentiation via interaction with CD97 leading to T regulatory cells, increased production of IL-10, and immune tolerance.
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37
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Cravedi P, Leventhal J, Lakhani P, Ward SC, Donovan MJ, Heeger PS. Immune cell-derived C3a and C5a costimulate human T cell alloimmunity. Am J Transplant 2013; 13:2530-9. [PMID: 24033923 PMCID: PMC3809075 DOI: 10.1111/ajt.12405] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 06/24/2013] [Accepted: 06/27/2013] [Indexed: 01/25/2023]
Abstract
Emerging evidence indicates that complement provides costimulatory signals for murine T cells but whether complement impacts human T cells remains unclear. We observed production of complement activation products C3a and C5a during in vitro cultures of human T cells responding to allogeneic dendritic cells (DC). Both partners expressed the receptors for C3a (C3aR) and C5a (C5aR) and C3aR- and C5aR-antagonists inhibited T cell proliferation. Recombinant C3a/C5a promoted CD4(+) T cell expansion, bypassed the inhibitory effects of CTLA4-Ig, and induced AKT phosphorylation, the latter biochemically linking C3aR/C5aR to known T cell signaling pathways. Lowering DC C3a/C5a production by siRNA knockdown of DC C3 reduced T cell alloresponses. Conversely downregulating DC expression of the complement regulatory protein decay-accelerating factor increased immune cell C3a/C5a and augmented T cell proliferation, identifying antigen presenting cells as the dominant complement source. Pharmacological C5aR blockade reduced graft versus host disease (GVHD) scores, prolonged survival, and inhibited T cell responses in NOD scid γc(null) mouse recipients of human peripheral blood mononuclear cells, verifying that the mechanisms apply in vivo. Together our findings unequivocally document that immune cell-derived complement impacts human T cell immunity and provide the foundation for future studies targeting C3aR/C5aR as treatments of GVHD and organ transplant rejection in humans.
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Affiliation(s)
- Paolo Cravedi
- Renal Division, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Jeremy Leventhal
- Renal Division, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Parth Lakhani
- Renal Division, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA
| | - Stephen C. Ward
- Department of Pathology, Mount Sinai School of Medicine, New York, NY, USA
| | - Michael J. Donovan
- Department of Pathology, Mount Sinai School of Medicine, New York, NY, USA
| | - Peter S. Heeger
- Renal Division, Department of Medicine, Mount Sinai School of Medicine, New York, NY, USA,Recanati Miller Transplant Institute and Immunology Institute, Mount Sinai School of Medicine, New York, NY, USA
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Abstract
The sensitive and broadly reactive character of the innate immune system makes it liable to activation by stress factors other than infection. Thermal and metabolic stresses experienced during the transplantation procedure are sufficient to trigger the innate immune response and also augment adaptive immunity in the presence of foreign antigen on the donor organ. The resulting inflammatory and immune reactions combine to form a potent effector response that can lead to graft rejection. Here we examine the evidence that the complement and toll-like receptor systems are central to these pathways of injury and present a formidable barrier to transplantation. We review extensive information about the effector mechanisms that are mediated by these pathways, and bring together what is known about the damage-associated molecular patterns that initiate this sequence of events. Finally, we refer to two ongoing therapeutic trials that are evaluating the validity of these concepts in man.
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Affiliation(s)
- Conrad A Farrar
- MRC Centre for Transplantation, Division of Transplantation Immunology and Mucosal Biology, King's College London School of Medicine at Guy's, King's College and St. Thomas' Hospitals, London SE1 9RT, United Kingdom
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39
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Physiological and therapeutic complement regulators in kidney transplantation. Curr Opin Organ Transplant 2013; 18:421-9. [PMID: 23838647 DOI: 10.1097/mot.0b013e32836370ce] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
PURPOSE OF REVIEW This review will summarize the key contribution of complement regulators in the immune response to an allograft. RECENT FINDINGS Over the past 10 years, compelling evidences have been accumulated in support of a critical role of complement in the pathological phenomena related to organ transplantation. In addition to recurrence of complement-mediated disease after graft, complement is involved in situations as diverse as brain death induced tissue damages, ischaemia-reperfusion and antibody-mediated rejections. This complement activation is counterbalanced by various regulatory mechanisms. SUMMARY We discuss the role of physiological and therapeutic complement regulators that are designed to overcome the impact of complement overactivation with the aim of improving long-term transplant outcomes. We will focus primarily on renal allograft, but the discussed mechanisms take place to a different degree in any kind of organ transplantation.
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40
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Kemper C, Köhl J. Novel roles for complement receptors in T cell regulation and beyond. Mol Immunol 2013; 56:181-90. [PMID: 23796748 DOI: 10.1016/j.molimm.2013.05.223] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/20/2013] [Indexed: 12/16/2022]
Abstract
Complement receptors are expressed on cells of the innate and the adaptive immune system. They play important roles in pathogen and danger sensing as they translate the information gathered by complement fluid phase sensors into cellular responses. Further, they control complement activation on viable and apoptotic host cells, clearance of immune complexes and mediate opsonophagocytosis. More recently, evidence has accumulated that complement receptors form a complex network with other innate receptors systems such as the Toll-like receptors, the Notch signaling system, IgG Fc receptors and C-type lectin receptors contributing to the benefit and burden of innate and adaptive immune responses in autoimmune and allergic diseases as well as in cancer and transplantation. Here, we will discuss recent developments and emerging concepts of complement receptor activation and regulation with a particular focus on the differentiation, maintenance and contraction of effector and regulatory T cells.
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Affiliation(s)
- Claudia Kemper
- Division of Transplant Immunology and Mucosal Biology, MRC Centre for Transplantation, King's College London, Guy's Hospital, London, UK.
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41
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Reichenbach DK, Li Q, Hoffman RA, Williams AL, Shlomchik WD, Rothstein DM, Demetris AJ, Lakkis FG. Allograft outcomes in outbred mice. Am J Transplant 2013; 13:580-8. [PMID: 23311531 PMCID: PMC3582712 DOI: 10.1111/ajt.12056] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Revised: 10/22/2012] [Accepted: 11/07/2012] [Indexed: 01/25/2023]
Abstract
Inbreeding depression and lack of genetic diversity in inbred mice could mask unappreciated causes of graft failure or remove barriers to tolerance induction. To test these possibilities, we performed heart transplantation between outbred or inbred mice. Unlike untreated inbred mice in which all allografts were rejected acutely (6-16 days posttransplantation), untreated outbred mice had heterogeneous outcomes, with grafts failing early (<4 days posttransplantation), acutely (6-24 days) or undergoing chronic rejection (>75 days). Blocking T cell costimulation induced long-term graft acceptance in both inbred and outbred mice, but did not prevent the early graft failure observed in the latter. Further investigation of this early phenotype established that it is dependent on the donor, and not the recipient, being outbred and that it is characterized by hemorrhagic necrosis and neutrophilic vasculitis in the graft without preformed, high titer antidonor antibodies in the recipient. Complement or neutrophil depletion prevented early failure of outbred grafts, whereas transplanting CD73-deficient inbred hearts, which are highly susceptible to ischemia-reperfusion injury, recapitulated the early phenotype. Therefore, outbred mice could provide broader insight into donor and recipient determinants of allograft outcomes but their hybrid vigor and genetic diversity do not constitute a uniform barrier to tolerance induction.
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Affiliation(s)
- Dawn K. Reichenbach
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - Qi Li
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - Rosemary A. Hoffman
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - Amanda L. Williams
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - Warren D. Shlomchik
- Departments of Medicine and Immunobiology, Yale University School of Medicine, New Haven, Connecticut 06520
| | - David M. Rothstein
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - A. Jake Demetris
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
| | - Fadi G. Lakkis
- Thomas E. Starzl Transplantation Institute and Departments of Surgery, Immunology, Medicine, and Pathology, University of Pittsburgh, Pittsburgh, PA, 15261
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42
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Kolev M, Le Friec G, Kemper C. The role of complement in CD4+ T cell homeostasis and effector functions. Semin Immunol 2013; 25:12-9. [DOI: 10.1016/j.smim.2013.04.012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2013] [Accepted: 04/30/2013] [Indexed: 01/22/2023]
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Amano MT, Camara NOS. The immunomodulatory role of carbon monoxide during transplantation. Med Gas Res 2013; 3:1. [PMID: 23295066 PMCID: PMC3582539 DOI: 10.1186/2045-9912-3-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/31/2012] [Indexed: 01/03/2023] Open
Abstract
The number of organ and tissue transplants has increased worldwide in recent decades. However, graft rejection, infections due to the use of immunosuppressive drugs and a shortage of graft donors remain major concerns. Carbon monoxide (CO) had long been regarded solely as a poisonous gas. Ultimately, physiological studies unveiled the endogenous production of CO, particularly by the heme oxygenase (HO)-1 enzyme, recognizing CO as a beneficial gas when used at therapeutic doses. The protective properties of CO led researchers to develop uses for it, resulting in devices and molecules that can deliver CO in vitro and in vivo. The resulting interest in clinical investigations was immediate. Studies regarding the CO/HO-1 modulation of immune responses and their effects on various immune disorders gave rise to transplantation research, where CO was shown to be essential in the protection against organ rejection in animal models. This review provides a perspective of how CO modulates the immune system to improve transplantation and suggests its use as a therapy in the field.
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Affiliation(s)
- Mariane Tami Amano
- Laboratory of Transplantation Immunobiology, Department of Immunology, Institute of Biomedical Sciences, University of Sao Paulo, Sao Paulo, Brazil.
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Abstract
Results of studies published since 2002 reveal that T cells and antigen-presenting cells (APCs) produce complement proteins. The immune cell-derived, alternative pathway complement components activate spontaneously, yielding local, but not systemic, production of C3a and C5a. These anaphylatoxins bind to their respective G-protein-coupled receptors, C3aR and C5aR, expressed on both partners. The resultant complement-induced T cell activation and APC activation drive T cell differentiation, expansion and survival. Complement deficiency or blockade attenuates T cell-mediated autoimmunity and delays allograft rejection in mice. Increasing complement activation, achieved by genetic removal of the complement regulatory protein decay-accelerating factor, enhances murine T cell immunity and accelerates allograft rejection. The findings support the need for design and testing of complement inhibitors in humans.
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Affiliation(s)
- Wing-hong Kwan
- Department of Medicine, Recanati Miller Transplant Institute and Immunology Institute, Mount Sinai School of Medicine, Box 1243, One Gustave L. Levy Plaza, New York, NY 10029, USA
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Bartel G, Brown K, Phillips R, Peng Q, Zhou W, Sacks SH, Wong W. Donor specific transplant tolerance is dependent on complement receptors. Transpl Int 2012; 26:99-108. [DOI: 10.1111/tri.12006] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2012] [Revised: 07/18/2012] [Accepted: 10/07/2012] [Indexed: 12/14/2022]
Affiliation(s)
- Gregor Bartel
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Kathryn Brown
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Richards Phillips
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Qi Peng
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Wuding Zhou
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Steven H. Sacks
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
| | - Wilson Wong
- MRC Centre for Transplantation; King's College London; School of Medicine at Guy's; King's and St. Thomas' Hospitals; London; UK
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Abstract
The complement cascade is a major contributor to the innate immune response. It has now been well accepted that complement plays a critical role in hyperacute rejection and acute antibody-mediated rejection of transplanted organ. There is also increasing evidence that complement proteins contribute to the pathogenesis of organ ischemia-reperfusion injury, and even to cell-mediated rejection. Furthermore, the chemoattractants C3a and C5a and the terminal membrane attack complex that are generated by complement activation can directly or indirectly mediate tissue injury and trigger adaptive immune responses. Here, we review recent findings concerning the role of complement in graft ischemia-reperfusion injury, antibody-mediated rejection and accommodation, and cell-mediated rejection. We also discuss the current status of complement intervention therapies in clinical transplantation and describe potential new therapeutic strategies for clinical application.
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Affiliation(s)
- Gang Chen
- Institute of Organ Transplantation, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
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HDL and ApoA-I inhibit antigen presentation-mediated T cell activation by disrupting lipid rafts in antigen presenting cells. Atherosclerosis 2012; 225:105-14. [PMID: 22862966 DOI: 10.1016/j.atherosclerosis.2012.07.029] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Revised: 07/03/2012] [Accepted: 07/18/2012] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Depletion of cholesterol by methyl-β-cyclodextrin (MCD) on peptide-loaded antigen presenting cells (APCs) inhibits antigen presentation and T cell activation. However, whether membrane cholesterol efflux induced by high-density lipoprotein (HDL) and apolipoprotein A-I (apoA-I) also results in inhibition of antigen presentation and T cell activation is still unknown. METHODS AND RESULTS Various types of APCs, including B cells, macrophages and dendritic cells (DCs), were first loaded with antigen, then incubated with HDL and apoA-I to decrease cellular membrane cholesterol content. After being treated with HDL and apoA-I, APCs demonstrated decreased potential to activate T cells, and this decrease correlated with an increase in cholesterol efflux from APCs. Cholesterol repletion reversed the inhibitory effects of HDL and apoA-I, demonstrating that the observed reduction in T cell proliferation is mediated through cholesterol. Furthermore, lipid raft analysis showed that HDL and apoA-I reduced cholesterol and major histocompatibility (MHC) class II protein content in lipid rafts, suggesting that cholesterol efflux from APCs to HDL and apoA-I inhibits antigen presentation and T cell activation by reducing lipid rafts assembly in APCs. CONCLUSION HDL and apoA-I inhibit the capacity of APCs to stimulate T cell activation, and this inhibition can be attributed to cholesterol efflux and the ensuing disruption of plasma membrane lipid rafts in APCs. Overall, these findings suggest that cholesterol efflux mediated by HDL and apoA-I may serve to link immunity and cardioprotection.
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Soltys J, Wu X. Complement regulatory protein Crry deficiency contributes to the antigen specific recall response in experimental autoimmune myasthenia gravis. JOURNAL OF INFLAMMATION-LONDON 2012; 9:20. [PMID: 22642809 PMCID: PMC3524051 DOI: 10.1186/1476-9255-9-20] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 04/18/2012] [Indexed: 12/20/2022]
Abstract
UNLABELLED BACKGROUND Myasthenia gravis (MG) and animal model of experimental autoimmune myasthenia gravis (EAMG) is the most common autoimmune disorder of neuromuscular transmission. The disease is caused by the breakdown of the acetylcholine receptor (AChR) which is largely due to complement activation at the neuromuscular junction (NMJ). Limited knowledge exists to the extent that complement receptor 1-related gene/protein y deficiency (Crry -/-) modulates the adaptive immune response and EAMG outcome. METHODS Mouse EAMG was induced by s.c. administrations of purified acetylcholine receptor (AChR) to Crry -/- and age- matched WT (C57BL/6) mice. Disease severity was assessed by clinical score assessment and muscle grip strength measurements. Serum complement activity was determined by hemolytic assay. ELISA was used to detect the level of AChR specific antibodies. Splenic cells were analyzed for T and B cells subsets distribution, release of cytokines and AChR specific recall responses. Deposition of complement components at the NMJ was assessed by immunofluorescence staining. RESULTS In comparison to WT EAMG, Crry -/- EAMG mice showed signs of augmented muscle weakness but differences, except for one time point, were not statistically significant. Serum complement activity was reduced in Crry -/- EAMG mice and no substantial changes in deposition of C3, C3b/iC3b and C5b-9 (MAC) at the NMJ between WT EAMG and Crry -/- EAMG mice were detected. Lack of Crry affected adaptive immune response. Crry -/- EAMG mice showed increases in the number of AChR specific splenic T-cells secreting IFN-γ and IL-4. Production of complement fixing antibodies (IgG2b, IgG2c) was also augmented. More Th1, Th2 and Th17 cytokines were released into the bloodstream of Crry -/- EAMG mice. CONCLUSIONS Data suggest that Crry deficiency modulates the adaptive immune response in EAMG, but its effect on disease outcome is limited. This was due to the generally lower serum complement level caused by increased C3 turnover. Modulation of complement activity with soluble or membrane bound regulators of complement activity represents a potentially effective approach to modify autoimmune processes in MG and EAMG.
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Affiliation(s)
- Jindrich Soltys
- Department of Neurology & Psychiatry, 1438 South Grand Boulevard, Saint Louis University School of Medicine, Saint Louis, MO, 63104, USA.
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Abstract
The complement system is a key element of the innate immune system, and the production of complement components can be divided into central (hepatic) and peripheral compartments. Essential complement components such as C3 are produced in both of these compartments, but until recently the functional relevance of the peripheral synthesis of complement was unclear. Here, we review recent findings showing that local peripheral synthesis of complement in a transplanted organ is required for the immediate response of the donor organ to tissue stress and for priming alloreactive T cells that can mediate transplant rejection. We also discuss recent insights into the role of complement in antibody-mediated rejection, and we examine how new treatment strategies that take into account the separation of central and peripheral production of complement are expected to make a difference to transplant outcome.
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