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Jung SH, Hwang JH, Kim SE, Young Kyu K, Park HC, Lee HT. The potentiating effect of hTFPI in the presence of hCD47 reduces the cytotoxicity of human macrophages. Xenotransplantation 2017; 24. [PMID: 28393401 DOI: 10.1111/xen.12301] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 01/30/2017] [Accepted: 03/01/2017] [Indexed: 01/16/2023]
Abstract
BACKGROUND In pig-to-human xenotransplantation, hyperacute rejection of pig organs could be overcome by the production of α1,3-galactosyltransferase knockout pigs. However, macrophage-mediated acute rejection is another obstacle that needs to be overcome. Among the various candidate genes involved in acute rejection, CD47 inhibits monocyte/macrophage-mediated phagocytosis by identifying the CD47 signal regulatory protein alpha (SIRP-α) as self/non-self. Tissue factor pathway inhibitor (TFPI) is involved in the regulation of the coagulation pathway and is able to bind to another ligand of CD47, thrombospondin-1 (TSP-1). When TSP-1 binds to CD47, phagocytosis in macrophages is increased. METHODS The 2A peptide system was used to establish pig kidney cells (PK15) simultaneously expressing human CD47 and human TFPI, and they were cultured with activated THP-1 cells. After staining with 7-aminoactinomycin D, flow cytometry analysis was carried out. TFPI siRNA analysis and recombinant human TFPI (rhTFPI) treatment were performed to determine the potentiating effect of TFPI on pig cells for activated THP-1 cells in the presence of CD47. Related inflammatory cytokines produced by activated THP-1 cells were analyzed using qPCR and Western blot technique. In addition, the tyrosine phosphorylation level of SIRP-α in activated THP-1 cells was analyzed using immunoprecipitation and Western blot. RESULTS hCD47/hTFPI-PK15 cells survived better than hCD47-PK15, hTFPI-PK15, or normal PK15 cells on cytotoxicity tests using activated THP-1 cells. TSP-1, derived from these activated THP-1 cells, served as a mediator for this enhancing effect, and it also played a role in activated adherent peripheral blood mononuclear cells (PBMCs). The tyrosine phosphorylation level of SIRP-α in activated THP-1 cells was further increased in the case of co-expression of CD47/TFPI than in individual non-expression or expression of CD47 or TFPI alone. CONCLUSIONS When hCD47 was expressed, the expression of hTFPI leaded to tyrosine phosphorylation of SIRP-α in activated THP-1 cells via hTSP-1 inhibition, and consequently, it might improve the effect of hCD47-SIRP-a signaling.
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Affiliation(s)
- Sung Han Jung
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea
| | - Jeong Ho Hwang
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea.,Korea Institute of Toxicology, Jeongeup-si, Jeollabuk-do, Korea
| | - Sang Eun Kim
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea
| | - Kim Young Kyu
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea
| | - Hyo Chang Park
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea
| | - Hoon Taek Lee
- Department of Bioscience and Biotechnology, Konkuk University, Seoul, Korea
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Iwase H, Kobayashi T. Current status of pig kidney xenotransplantation. Int J Surg 2015; 23:229-233. [PMID: 26305729 PMCID: PMC4684762 DOI: 10.1016/j.ijsu.2015.07.721] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Revised: 07/21/2015] [Accepted: 07/26/2015] [Indexed: 12/27/2022]
Abstract
Significant progress in life-supporting kidney xenograft survival in nonhuman primates (NHPs) has been associated largely with the increasing availability of pigs with genetic modifications that protect the pig tissues from the primate immune response and/or correct molecular incompatibilities between pig and primate. Blockade of the CD40/CD154 costimulation pathway with anti-CD154 mAb therapy has contributed to prolongation of kidney xenograft survival, although this agent may not be clinically available. An anti-CD40 mAb-based regimen is proving equally successful, but blockade of the CD28/B7 pathway is inadequate. Severe proteinuria were uniformly documented in the early studies of pig kidney xenotransplantation, but whether this resulted from immune injury or from physiological incompatibilities between the species, or both, remained uncertain. Recent experiments suggest it was related to a continuing immune response. Before 2014, the longest survival of a pig kidney graft in a NHP was 90 days, though graft survival >30 days was unusual. Recently this has been extended to >125 days, without features of a consumptive coagulopathy or a protein-losing nephropathy. In conclusion, overcoming the immune, coagulation, and inflammatory responses by the development of precise genetic modifications in donor pigs, along with effective immunosuppressive and anticoagulant/anti-inflammatory therapy is advancing the field towards clinical trials.
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Affiliation(s)
- Hayato Iwase
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA.
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Abstract
Dysregulation of coagulation and disordered hemostasis are frequent complications in the pig-to-nonhuman primate preclinical xenotransplantation model. The most extreme manifestations are the systemic development of a life-threatening consumptive coagulopathy, characterized by thrombocytopenia and bleeding, which is balanced at the opposite extreme by local complications of graft loss due to thrombotic microangiopathy. The contributing mechanisms include inflammation, vascular injury, heightened innate, humoral and cellular immune responses, and molecular incompatibilities affecting the regulation of coagulation. There also appear to be organ-specific factors that have been linked to vascular heterogeneity. As examples, liver xenografts rapidly induce thrombocytopenia by sequestering human/primate platelets; renal xenografts cause a broader coagulopathy, linked in some cases to reactivation of porcine CMV, whereas cardiac xenografts often succumb to microvascular thrombosis without associated systemic coagulopathy but with local perturbations in fibrinolysis. Overcoming coagulation dysfunction will require a combination of genetic and pharmacological strategies. Deletion of the xenoantigen αGal, transgenic expression of human complement regulatory proteins, and refinement of immunosuppression to blunt the antibody response have all had some impact, without providing a complete solution. More recently, the addition of approaches specifically targeted at coagulation have produced promising results. As an example, heterotopic cardiac xenografts from donors expressing human thrombomodulin have survived for more than a year in immunosuppressed baboons, with no evidence of thrombotic microangiopathy or coagulopathy.
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Cooper DKC, Satyananda V, Ekser B, van der Windt DJ, Hara H, Ezzelarab MB, Schuurman HJ. Progress in pig-to-non-human primate transplantation models (1998-2013): a comprehensive review of the literature. Xenotransplantation 2014; 21:397-419. [PMID: 25176336 DOI: 10.1111/xen.12127] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 06/03/2014] [Indexed: 12/11/2022]
Abstract
BACKGROUND The pig-to-non-human primate model is the standard choice for in vivo studies of organ and cell xenotransplantation. In 1998, Lambrigts and his colleagues surveyed the entire world literature and reported all experimental studies in this model. With the increasing number of genetically engineered pigs that have become available during the past few years, this model is being utilized ever more frequently. METHODS We have now reviewed the literature again and have compiled the data we have been able to find for the period January 1, 1998 to December 31, 2013, a period of 16 yr. RESULTS The data are presented for transplants of the heart (heterotopic and orthotopic), kidney, liver, lung, islets, neuronal cells, hepatocytes, corneas, artery patches, and skin. Heart, kidney, and, particularly, islet xenograft survival have increased significantly since 1998. DISCUSSION The reasons for this are briefly discussed. A comment on the limitations of the model has been made, particularly with regard to those that will affect progression of xenotransplantation toward the clinic.
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Affiliation(s)
- David K C Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
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5
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Iwase H, Ezzelarab MB, Ekser B, Cooper DKC. The role of platelets in coagulation dysfunction in xenotransplantation, and therapeutic options. Xenotransplantation 2014; 21:201-20. [PMID: 24571124 DOI: 10.1111/xen.12085] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Accepted: 01/08/2014] [Indexed: 12/11/2022]
Abstract
Xenotransplantation could resolve the increasing discrepancy between the availability of deceased human donor organs and the demand for transplantation. Most advances in this field have resulted from the introduction of genetically engineered pigs, e.g., α1,3-galactosyltransferase gene-knockout (GTKO) pigs transgenic for one or more human complement-regulatory proteins (e.g., CD55, CD46, CD59). Failure of these grafts has not been associated with the classical features of acute humoral xenograft rejection, but with the development of thrombotic microangiopathy in the graft and/or consumptive coagulopathy in the recipient. Although the precise mechanisms of coagulation dysregulation remain unclear, molecular incompatibilities between primate coagulation factors and pig natural anticoagulants exacerbate the thrombotic state within the xenograft vasculature. Platelets play a crucial role in thrombosis and contribute to the coagulation disorder in xenotransplantation. They are therefore important targets if this barrier is to be overcome. Further genetic manipulation of the organ-source pigs, such as pigs that express one or more coagulation-regulatory genes (e.g., thrombomodulin, endothelial protein C receptor, tissue factor pathway inhibitor, CD39), is anticipated to inhibit platelet activation and the generation of thrombus. In addition, adjunctive pharmacologic anti-platelet therapy may be required. The genetic manipulations that are currently being tested are reviewed, as are the potential pharmacologic agents that may prove beneficial.
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Affiliation(s)
- Hayato Iwase
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh, Pittsburgh, PA, USA
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Cowan PJ, Cooper DKC, d'Apice AJF. Kidney xenotransplantation. Kidney Int 2014; 85:265-75. [PMID: 24088952 PMCID: PMC3946635 DOI: 10.1038/ki.2013.381] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 07/12/2013] [Accepted: 07/17/2013] [Indexed: 12/14/2022]
Abstract
Xenotransplantation using pigs as donors offers the possibility of eliminating the chronic shortage of donor kidneys, but there are several obstacles to be overcome before this goal can be achieved. Preclinical studies have shown that, while porcine renal xenografts are broadly compatible physiologically, they provoke a complex rejection process involving preformed and elicited antibodies, heightened innate immune cell reactivity, dysregulated coagulation, and a strong T cell-mediated adaptive response. Furthermore, the susceptibility of the xenograft to proinflammatory and procoagulant stimuli is probably increased by cross-species molecular defects in regulatory pathways. To balance these disadvantages, xenotransplantation has at its disposal a unique tool to address particular rejection mechanisms and incompatibilities: genetic modification of the donor. This review focuses on the pathophysiology of porcine renal xenograft rejection, and on the significant genetic, pharmacological, and technical progress that has been made to prolong xenograft survival.
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Affiliation(s)
- Peter J Cowan
- 1] Immunology Research Centre, St Vincent's Hospital, Melbourne, Victoria, Australia [2] Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
| | - David K C Cooper
- Thomas E. Starzl Transplantation Institute, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA
| | - Anthony J F d'Apice
- 1] Immunology Research Centre, St Vincent's Hospital, Melbourne, Victoria, Australia [2] Department of Medicine, University of Melbourne, Melbourne, Victoria, Australia
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Byrne GW, Azimzadeh AM, Ezzelarab M, Tazelaar HD, Ekser B, Pierson RN, Robson SC, Cooper DKC, McGregor CGA. Histopathologic insights into the mechanism of anti-non-Gal antibody-mediated pig cardiac xenograft rejection. Xenotransplantation 2013; 20:292-307. [PMID: 25098626 PMCID: PMC4126170 DOI: 10.1111/xen.12050] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2013] [Accepted: 07/31/2013] [Indexed: 01/13/2023]
Abstract
The histopathology of cardiac xenograft rejection has evolved over the last 20 yr with the development of new modalities for limiting antibody-mediated injury, advancing regimens for immune suppression, and an ever-widening variety of new donor genetics. These new technologies have helped us progress from what was once an overwhelming anti-Gal-mediated hyperacute rejection to a more protracted anti-Gal-mediated vascular rejection to what is now a more complex manifestation of non-Gal humoral rejection and coagulation dysregulation. This review summarizes the changing histopathology of Gal- and non-Gal-mediated cardiac xenograft rejection and discusses the contributions of immune-mediated injury, species-specific immune-independent factors, transplant and therapeutic procedures, and donor genetics to the overall mechanism(s) of cardiac xenograft rejection.
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Affiliation(s)
- Guerard W Byrne
- Institute of Cardiovascular Science, University College London, London, UK; Department of Surgery, Mayo Clinic, Rochester, MN, USA
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Lee KFE, Lu B, Roussel JC, Murray-Segal LJ, Salvaris EJ, Hodgkinson SJ, Hall BM, d'Apice AJF, Cowan PJ, Gock H. Protective effects of transgenic human endothelial protein C receptor expression in murine models of transplantation. Am J Transplant 2012; 12:2363-72. [PMID: 22681753 DOI: 10.1111/j.1600-6143.2012.04122.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Thrombosis and inflammation are major obstacles to successful pig-to-human solid organ xenotransplantation. A potential solution is genetic modification of the donor pig to overexpress molecules such as the endothelial protein C receptor (EPCR), which has anticoagulant, anti-inflammatory and cytoprotective signaling properties. Transgenic mice expressing human EPCR (hEPCR) were generated and characterized to test this approach. hEPCR was expressed widely and its compatibility with the mouse protein C pathway was evident from the anticoagulant phenotype of the transgenic mice, which exhibited a prolonged tail bleeding time and resistance to collagen-induced thrombosis. hEPCR mice were protected in a model of warm renal ischemia reperfusion injury compared to wild type (WT) littermates (mean serum creatinine 39.0 ± 2.3 μmol/L vs. 78.5 ± 10.0 μmol/L, p < 0.05; mean injury score 31 ± 7% vs. 56 ± 5%, p < 0.05). Heterotopic cardiac xenografts from hEPCR mice showed a small but significant prolongation of survival in C6-deficient PVG rat recipients compared to WT grafts (median graft survival 6 vs. 5 days, p < 0.05), with less hemorrhage and edema in rejected transgenic grafts. These data indicate that it is possible to overexpress EPCR at a sufficient level to provide protection against transplant-related thrombotic and inflammatory injury, without detrimental effects in the donor animal.
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Affiliation(s)
- K F E Lee
- Immunology Research Centre, St. Vincent's Hospital, Melbourne, Australia
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Abstract
PURPOSE OF REVIEW Cardiac xenotransplantation (CXTx) remains a promising approach to alleviate the chronic shortage of donor hearts. This review summarizes recent results of heterotopic and orthotopic CXTx, highlights the role of non-Gal antibody in xenograft rejection, and discusses challenges to clinical orthotopic CXTx. RECENT FINDINGS Pigs mutated in the α 1,3 galactosyltransferase gene (GTKO pigs) are devoid of the galactose α1,3 galactose (αGal) carbohydrate antigen. This situation effectively eliminates any role for anti-Gal antibody in GTKO cardiac xenograft rejection. Survival of heterotopic GTKO cardiac xenografts in nonhuman primates continues to increase. GTKO graft rejection commonly involves vascular antibody deposition and variable complement deposition. Non-Gal antibody responses to porcine antigens associated with inflammation, complement, and hemostatic regulation and to new carbohydrate antigens have been identified. Their contribution to rejection remains under investigation. Orthotopic CXTx is limited by early perioperative cardiac xenograft dysfunction (PCXD). However, hearts affected by PCXD recover full cardiac function and orthotopic survival up to 2 months without rejection has been reported. SUMMARY CXTx remains a promising technology for treating end-stage cardiac failure. Genetic modification of the donor and refinement of immunosuppressive regimens have extended heterotopic cardiac xenograft survival from minutes to in excess of 8 months.
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Affiliation(s)
- Guerard W Byrne
- University College London, Institute for Cardiovascular Sciences, London, UK.
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10
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Abstract
Microvascular thrombosis, following the activation of clotting cascade, is a hallmark of porcine solid organ xenograft rejection. The analysis of differences between human, monkey, and pig coagulation systems is crucial when monkey is used as animal model and pig as organ donor in xenotransplantation. Thrombosis, according to many authors, may be due to the molecular incompatibilities between natural anticoagulants present on pig endothelium and primate activated coagulation factors. The generation of activated protein C (PC) is critical for the physiological anticoagulation. One of the major incompatibilities may be related to the inability of pig thrombomodulin (TM) and endothelial protein C receptor to activate the recipient (primate) circulating PC in the presence of thrombin. Tissue factor pathway inhibitor (TFPI), is the primary inhibitor of tissue factor (TF)-induced coagulation. TFPI directly inhibits the activated factor X (FXa) and blocks the procoagulant activity of the TF/factor VIIa (FVIIa) complex by forming a quaternary TF/FVIIa/FXa/TFPI complex. Microvascular thrombosis, observed in the organ transplant, may also be due to the failure of pig TFPI to bind human FXa efficiently and inhibit human FVIIa/TF activity. The methods described in this chapter can be useful for the identification and characterization of primate and pig coagulation factors (isolated from a small volume of blood) by using SDS-PAGE and immunoblotting. Differences in molecular weight can help in the identification of the origin (pig or primate) of coagulation proteins in plasma from the recipient of xenografts. On the other hand, in vitro models of PC pathway and TFPI on human umbilical vein endothelial cells (HUVEC) and porcine aortic endothelial cells (PAEC) are described which can be used for studying incompatibilities between primate and pig.
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Schmelzle M, Cowan PJ, Robson SC. Which anti-platelet therapies might be beneficial in xenotransplantation? Xenotransplantation 2011; 18:79-87. [PMID: 21496115 DOI: 10.1111/j.1399-3089.2011.00628.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Xenotransplantation could provide an unlimited and elective supply of grafts, once mechanisms of graft loss and vascular injury are better understood. The development of α-1,3-galactosyltransferase gene-knockout (GalT-KO) swine with the removal of a dominant xeno-antigen has been an important advance; however, delayed xenograft and acute vascular reaction in GalT-KO animals persist. These occur, at least in part, because of humoral reactions that result in vascular injury. Intrinsic molecular incompatibilities in the regulation of blood clotting and extracellular nucleotide homeostasis between discordant species may also predispose to thrombophilia within the vasculature of xenografts. Although limited benefits have been achieved with currently available pharmacological anti-thrombotics and anti-coagulants, the highly complex mechanisms of platelet activation and thrombosis in xenograft rejection also require potent immunosuppressive interventions. We will focus on recent thromboregulatory approaches while elucidating appropriate anti-platelet mechanisms. We will discuss potential benefits of additional anti-thrombotic interventions that are possible in transgenic swine and review recent developments in pharmacological anti-platelet therapy.
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Affiliation(s)
- Moritz Schmelzle
- Liver Center and Transplantation Institute, Department of Medicine and Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02115, USA.
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Schneider MKJ, Seebach JD. Xenotransplantation literature update, January-February 2011. Xenotransplantation 2011; 18:147-50. [PMID: 21496121 DOI: 10.1111/j.1399-3089.2011.00630.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mårten K J Schneider
- Laboratory of Vascular Immunology, Division of Internal Medicine, University Hospital Zurich, Zurich, Switzerland.
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