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Wang Y, Du Y, Zhou X, Wang L, Li J, Wang F, Huang Z, Huang X, Wei H. Efficient generation of B2m-null pigs via injection of zygote with TALENs. Sci Rep 2016; 6:38854. [PMID: 27982048 PMCID: PMC5159787 DOI: 10.1038/srep38854] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Accepted: 11/14/2016] [Indexed: 02/07/2023] Open
Abstract
Donor major histocompatibility complex class I (MHC I) molecules are the main targets of the host immune response after organ allotransplantation. Whether and how MHC I-deficiency of pig donor tissues affects rejection after xenotransplantation has not been assessed. Beta2-microglobulin (B2M) is indispensable for the assembly of MHC I receptors and therefore provides an effective target to disrupt cell surface MHC I expression. Here, we report the one-step generation of mutant pigs with targeted disruptions in B2m by injection of porcine zygotes with B2m exon 2-specific TALENs. After germline transmission of mutant B2m alleles, we obtained F1 pigs with biallelic B2m frameshift mutations. F1 pigs lacked detectable B2M expression in tissues derived from the three germ layers, and their lymphocytes were devoid of MHC I surface receptors. Skin grafts from B2M deficient pigs exhibited remarkably prolonged survival on xenogeneic wounds compared to tissues of non-mutant littermates. Mutant founder pigs with bi-allelic disruption in B2m and B2M deficient F1 offspring did not display visible abnormalities, suggesting that pigs are tolerant to B2M deficiency. In summary, we show the efficient generation of pigs with germline mutations in B2m, and demonstrate a beneficial effect of donor MHC I-deficiency on xenotransplantation.
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Affiliation(s)
- Yong Wang
- Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China
| | - Yinan Du
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University, National Resource Center for Mutant Mice, Nanjing 210061, China.,School of Life Science and Technology, ShanghaiTech University, 100 Haike Rd., Pudong New Area, Shanghai 201210, China
| | - Xiaoyang Zhou
- Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China
| | - Lulu Wang
- Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China
| | - Jian Li
- Department of Immunology, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China
| | - Fengchao Wang
- Institute of Combined Injury, College of Military Preventive Medicine, Third Military Medical University, Chongqing 400038, China
| | - Zhengen Huang
- Research Institute of Burns, Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Xingxu Huang
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center of Nanjing University, National Resource Center for Mutant Mice, Nanjing 210061, China.,School of Life Science and Technology, ShanghaiTech University, 100 Haike Rd., Pudong New Area, Shanghai 201210, China
| | - Hong Wei
- Department of Laboratory Animal Science, College of Basic Medical Sciences, Third Military Medical University, Chongqing 400038, China
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Kim DE, Oh KH, Yang JH, Kwon SK, Cho TJ, Lee SB, Nam H, Lee DS, Lee JR, Lee G, Cho J. The Porcine Aortic Tissue Culture System in vitro for Stem Cell Research. Int J Stem Cells 2011; 4:116-22. [PMID: 24298344 DOI: 10.15283/ijsc.2011.4.2.116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/18/2011] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND AND OBJECTIVES Due to the shortage of human donors for transplantation, the use of animal organs for xenotransplantation has come into great interest. Xeno-derived vessels and cardiac valves would be possible alternatives for the patient suffering from cardiovascular diseases. Therefore, we established in vitro culture system of a porcine vessel that could be helpful for the research of xenograft and stem cell research. METHODS AND RESULTS We primarily isolated porcine thoracic aorta, cultured square-shaped pieces up to 17 days and analyzed its morphology and characters. The endothelial cells were primarily isolated from cultured porcine aortic pieces and their morphology, function and character were analyzed in order to confirm them as endothelial cells at day 3, 4, 8, 10 and 17. Even at day 17, the morphology exhibited the intact endothelial layer as well as specifically expressed CD31 and von Willebrand factor. The morphology of primarily isolated cells from cultured tissues was identical as an endothelial cell. By flow cytometry analysis, more than 80% of the isolated cells expressed CD31 and up to 80% took up acetyl low density lipoprotein (ac-LDL) until day 10 of tissue culture period even though it decreased to about 50% at day 17 that means they not only showed typical endothelial cell characters but also functioned properly. CONCLUSIONS We successfully established and optimized a porcine vascular tissue in vitro culture system that could be a valuable model for in vitro study of xenotransplantation and stem cell research.
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Affiliation(s)
- Dong-Eun Kim
- Laboratory of Developmental Biology and Stem Cell Differentiation/Transplantation ; Department of Dental Regenerative Biotechnology, Dental Research Institue, School of Dentistry, Seoul National University
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Onzuka T, Shimizu I, Tomita Y, Iwai T, Okano S, Tominaga R. Application of cyclophosphamide-induced tolerance in alpha1,3-galactosyltransferase knockout mice presensitized with Gal alpha 1-3Gal beta-4-GlcNAc antigens. Surg Today 2008; 38:807-14. [PMID: 18751946 DOI: 10.1007/s00595-007-3715-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2007] [Accepted: 09/27/2007] [Indexed: 11/28/2022]
Abstract
PURPOSE Hyperacute rejection (HAR) mediated by the natural antibody (nAb) against Gal alpha 1-3Gal beta-4-GlcNAc (alpha Gal) is the major obstacle in xenogeneic organ transplantation. Previously, we reported the acceptance of donor heart grafts in anti-alpha Gal nAb-producing galactosyltransferase knockout (GalT KO) mice after cyclophosphamide (CP)-induced tolerance conditioning. In the present study, we applied our tolerance induction conditioning in presensitized recipient mice. METHODS GalT KO (alpha Gal(-/-), H-2(b/d)) recipient mice were presensitized with alpha Gal(+) rabbit red blood cells (RRBCs). Presensitized or nonsensitized recipient mice were treated with CP-induced tolerance conditioning, consisting of AKR (alpha Gal(+/+), H-2(k)) spleen cells (SC), CP, busulfan (BU), and AKR bone marrow cells (BMC). We assessed the survival of donor hearts and skin grafts and analyzed the production of anti-alpha Gal Abs by flow cytometry. RESULTS Donor mixed chimerism was achieved in the presensitized GalT KO mice treated with CP-induced tolerance conditioning. In parallel with the disappearance of anti-alpha Gal Abs, permanent acceptance of donor heart grafts and skin grafts was observed in presensitized and GalT KO mice treated with CP-induced tolerance conditioning. CONCLUSIONS Both B-cell and T-cell tolerance was achieved in the presence of a higher titer of anti-alpha Gal Abs after treatment with CP-induced tolerance conditioning.
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Affiliation(s)
- Tatsushi Onzuka
- Department of Cardiovascular Surgery, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka, 812-8582, Japan
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Yi KS, Lee S, Kang YH, Bae YS, Hwang SY, Ha I, Kim H, Kim MS, Cho B, Kang HJ, Bang KT, Kim JY, Yang J, Chung J, Ahn C. Weak response of porcine C5a receptor towards human C5a in miniature pig endothelial cells and PMNs. Xenotransplantation 2007; 14:563-71. [DOI: 10.1111/j.1399-3089.2007.00421.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Brandl U, Erhardt M, Michel S, Jöckle H, Burdorf L, Bittmann I, Rössle M, Mordstein V, Brenner P, Hammer C, Reichart B, Schmoeckel M. Soluble Galalpha(1,3)Gal conjugate combined with hDAF preserves morphology and improves function of cardiac xenografts. Xenotransplantation 2007; 14:323-32. [PMID: 17669174 DOI: 10.1111/j.1399-3089.2007.00410.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Cytotoxic anti-Galalpha(1,3)Gal antibodies play a key role in the rejection of pig organs transplanted into primates. Regimens reducing anti-Galalpha(1,3)Gal antibodies were associated with severe side effects unable to prevent antibody rebound until soluble synthetic oligosaccharides with terminal Galalpha(1,3)Gal inhibiting antigen binding became available. We displayed kinetics of anti-pig and anti-Galalpha(1,3)Gal IgM and IgG antibody levels using GAS914, a Galalpha(1,3)Gal trisaccharide conjugated to poly-l-lysine, and investigated corresponding changes of parameters of heart function. METHODS Using a working heart model, hDAF pig hearts were perfused with human blood containing GAS914 (group 1). As controls hDAF pig hearts (group 2) and landrace pig hearts (group 3) were perfused with human blood only. Levels of anti-Galalpha(1,3)Gal (IgM, IgG) and anti-pig antibodies were assessed to prove the effectiveness of GAS914. As parameters of heart function, cardiac output (CO), stroke work index (SWI), coronary blood flow (CBF) and coronary resistance were measured. Creatine phosphokinases, lactate dehydrogenase and aspartate aminotransferase were evaluated as markers of myocardial damage. Histological and immunohistochemical investigations were performed at the end of perfusion. RESULTS In group 1 an immediate and extensive reduction in both IgM and IgG anti-Galalpha(1,3)Gal was found. Anti-pig antibodies were eliminated accordingly. Antibody binding to GAS914 was complete before the start of organ perfusion. Corresponding to rapid antibody elimination in group 1 GAS914 not only was able to significantly prolong the beating time of the heart in hDAF pigs, but also to clearly improve functional parameters. When switching to the working heart mode hDAF pig hearts perfused with human blood containing GAS914 (group 1) revealed a CO starting at a significantly higher level than hDAF (group 2) and non-transgenic pig hearts (group 3) perfused with human blood only. Similarly, in group 1 SWI was significantly increased at the beginning of perfusion compared to that of group 2 and group 3. The increase in CBF during perfusion and the corresponding fall of coronary resistance occurred without significant differences between the groups revealing the independence of hDAF and GAS914. CONCLUSIONS Due to an immediate and profound reduction in Galalpha(1,3)Gal-specific antibodies, soluble Galalpha(1,3)Gal conjugates not only prolong survival, but also improve the hemodynamic performance of the heart in DAF pigs.
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Affiliation(s)
- Ulrike Brandl
- Department of Cardiac Surgery, Ludwig-Maximilians-University Munich, Munich, Germany.
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Liu D, Kobayashi T, Onishi A, Furusawa T, Iwamoto M, Suzuki S, Miwa Y, Nagasaka T, Maruyama S, Kadomatsu K, Uchida K, Nakao A. Relation between human decay-accelerating factor (hDAF) expression in pig cells and inhibition of human serum anti-pig cytotoxicity: value of highly expressed hDAF for xenotransplantation. Xenotransplantation 2007; 14:67-73. [PMID: 17214706 DOI: 10.1111/j.1399-3089.2006.00365.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Although the successful production of alpha1,3-galactosyltransferase-knockout (GT-KO) pigs has increased expectations of clinical xenotransplantation, additional modifications of genetically engineered pigs are still being explored, because even GT-KO pigs are incapable of inhibiting the host's immunological response completely. One of the potential candidates is a complement-regulatory protein, such as human decay-accelerating factor (hDAF). However, there are few reports on how high the expression level of hDAF in pig cells would be required for suppression of complement activation. The purpose of this study was to examine the relationship between the level of hDAF expression and its inhibitory effect on human serum cytotoxicity. METHODS An expression (pCAGGS) vector containing the hDAF gene was transfected into pig fibroblasts using an electroporation system (Gene Pulser II). Forty-eight to fifty-two hours after transfection, the cells were stained with FITC-labeled anti-hDAF antibody and then applied to the cell sorter. hDAF-transfected cells with various expression levels were collected by gating on fluorescence intensity. The level of hDAF expression was determined relative to that in human control endothelial cells. Collected cells expressing x1, x5, x10, x15 and x30 hDAF were incubated into 96-well plates for 16 h, and the cells were subjected to 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl tetrazolium bromide (MTT) assay. RESULTS hDAF expression levels in transfected cells at the time of MTT assay (16 h after sorting) were comparable to those immediately after sorting. hDAF expression in pig cells five times higher than in human endothelial cells was effective in inhibiting complement-dependent cytotoxicity of most human sera. However, 15- to 30-fold expression of hDAF was required for effective inhibition of human sera with the highest cytotoxic capacity. CONCLUSIONS A much higher level of hDAF expression in pig cells than previously considered necessary might be required to provide additional benefit in inhibiting antibody-mediated rejection. Genetically engineered pigs that express very high levels of hDAF would be beneficial for xenotransplantation.
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Affiliation(s)
- DaGe Liu
- Department of Surgery II, Nagoya University School of Medicine, Nagoya, Japan
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Manzi L, Montaño R, Abad MJ, Arsenak M, Romano E, Taylor P. Expression of human soluble complement receptor 1 by a pig endothelial cell line inhibits lysis by human serum. Xenotransplantation 2006; 13:75-9. [PMID: 16497215 DOI: 10.1111/j.1399-3089.2005.00265.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The importance of complement activation and naturally occurring anti-pig antibodies in the hyperacute rejection (HAR) observed in models of pig-to-human xenotransplantation is well established. To overcome this, much effort has been dedicated to preparing transgenic pigs by knocking out Galalpha(1-3)Gal expression in these animals, or knocking in the expression of human complement regulatory proteins (CRPs), such as CD59 or decay accelerating factor. A soluble form of another membrane CRP, complement receptor type 1 (CR1), has also been shown to inhibit complement activation. Here, we show that transfection of a pig endothelial cell line with a truncated form of human soluble complement receptor 1 (sCR1) almost completely protected these cells from complement-mediated lysis by human AB serum. Pigs genetically manipulated to express human sCR1 may represent an additional strategy to inhibit HAR of pig-to-human transplanted organs.
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Affiliation(s)
- Lorna Manzi
- Laboratory of Cellular and Molecular Pathology, Centre for Experimental Medicine, Venezuelan Institute for Scientific Research (IVIC), Caracus, Venezuela
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Moore DJ, Markmann JF, Deng S. Avenues for immunomodulation and graft protection by gene therapy in transplantation. Transpl Int 2006; 19:435-45. [PMID: 16771864 DOI: 10.1111/j.1432-2277.2006.00314.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Organ transplantation represents the only definitive therapy for many causes of end-organ failure. However, the universal success of this therapy is limited by chronic allograft rejection, the side effects of chronic immunosuppressive therapy, and a severe shortage of donor organs. Presently, the success of solid-organ transplantation depends on the continuous administration of toxic and nonspecific immunosuppressive agents, therapies that present risks for opportunistic infection, malignancy, and a variety of agent-specific side effects. To promote the use of transplantation with limited risk of long-term sequelae, three dominant research challenges emerge: (i) elimination of the need for exogenous immunosuppression by immunological tolerance induction; (ii) prevention of chronic rejection/graft dysfunction; and (iii) expansion of available organs for transplantation. Gene therapy may provide significant advances and solutions in each of these areas. Rejection of the graft in the immediate post-transplant period has been attacked through the transfer of immunomodulatory molecules in addition to tolerance inducing approaches. Chronic graft rejection may be similarly addressed through permanent tolerance induction or alternatively through the introduction of molecules to resist chronic graft damage. Genetic manipulation of stem cells may ultimately produce transgenic animals to serve as tissue donors to overcome the limited donor organ supply. This review will highlight ongoing developments in the translation of gene therapy approaches to the challenges inherent in transplantation.
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Affiliation(s)
- Daniel J Moore
- Department of Pediatrics, Vanderbilt University, Nashville, TN, USA
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Pöling J, Oezkur M, Kogge K, Mengel M, Niemann H, Winkler M, Haverich A, Wiebe K. Hyperacute rejection in ex vivo-perfused porcine lungs transgenic for human complement regulatory proteins. Transpl Int 2006; 19:225-32. [PMID: 16441772 DOI: 10.1111/j.1432-2277.2006.00267.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Inhibition of complement activation via human membrane-associated complement regulators is known to prevent hyperacute rejection in heart and kidney pig-to-primate transplantation. The protective effect of such strategies in pulmonary xenografts, however, seems to be insufficient. In an ex vivo perfusion, model lungs from donor pigs transgenic for human CD55 (n = 6) or human CD59 (n = 5) were perfused with fresh human blood and compared with nontransgenic organs (n = 6). In addition, a soluble complement component 1 esterase inhibitor (C1-Inh) was applied in h-CD55 transgenic lungs (n = 3). In the h-CD55 transgenic group, survival was prolonged (P < 0.05), quality and maximal time of oxygenation significantly improved and pulmonary vascular resistance reduced compared with the control group. There was a decreased sequestration of platelets, less parenchymal injury and reduced deposition of C(5b-9) in the h-CD55 transgenic group. Additional soluble complement inhibition (C1-Inh) did not prolong survival of h-CD55 transgenic lungs. Survival and pulmonary function in lungs expressing h-CD59 was not significantly different from parameters observed in nontransgenic lungs. In this ex vivo model of pig-to-primate lung transplantation, membrane-based complement inhibition resulted in significantly improved pulmonary function. However, minor histopathological injuries observed in these transgenic xenografts suggested only partial protection from pulmonary dysfunction by complement inhibition alone.
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Affiliation(s)
- Jochen Pöling
- Klinik für Herz-,Thorax- und Gefäbchirurgie, Medizinische Hochschule Hannover, Hannover, Germany
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Shimizu I, Smith NR, Zhao G, Medof E, Sykes M. Decay-Accelerating Factor Prevents Acute Humoral Rejection Induced by Low Levels of Anti-αGal Natural Antibodies. Transplantation 2006; 81:95-100. [PMID: 16421483 DOI: 10.1097/01.tp.0000188176.18666.68] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Hyperacute and delayed vascular rejection due to natural antibodies (NAb) present major obstacles in pig-to-primate xenotransplantation. Although "supraphysiologic" expression of human complement regulatory proteins (CRPs) can prevent hyperacute rejection in discordant xenogenic recipients, their physiologic role in the homologous setting is undefined. We have evaluated the effect of the absence of decay-accelerating factor (DAF) on cardiac allograft rejection in the presence of different levels of antidonor antibodies (Ab). METHODS DAF1-deficient (DAF KO; B6129F2 H-2) mice were used as heart graft donors to alpha1,3-galactosyltransferase deficient (GalT KO; B6, H-2) recipients. Heterotopic heart grafting was performed with or without presensitization. Graft survival, histology, and anti-alphaGal Ab levels were monitored. RESULTS DAF knockout (KO) but not wild-type (WT) grafts showed hyperacute or acute humoral rejection in nonsensitized GalT KO mice with low levels of anti-alphaGal IgM NAb. However, humoral rejection of both DAF KO and DAF WT donor grafts occurred in presensitized GalT KO recipients. CONCLUSIONS The expression of DAF prevents hyperacute rejection in mice with low titers of anti-alphaGal antibody. These studies demonstrate the physiologic role of DAF in preventing humoral rejection in the presence of low levels of NAb and have implications for transplantation of discordant vascularized xenografts.
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Affiliation(s)
- Ichiro Shimizu
- Transplantation Biology Research Center, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129, USA
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Kim DD, Song WC. Membrane complement regulatory proteins. Clin Immunol 2005; 118:127-36. [PMID: 16338172 DOI: 10.1016/j.clim.2005.10.014] [Citation(s) in RCA: 252] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2005] [Accepted: 10/28/2005] [Indexed: 12/12/2022]
Abstract
A number of proteins anchored on the cell surface function to protect host tissues from bystander injury when complement is activated. In humans, they include decay-accelerating factor (DAF, CD55), membrane cofactor protein (MCP, CD46), complement receptor 1 (CR1, CD35) and CD59. Although disease conditions directly attributable to abnormal function of these proteins are relatively rare, it has become evident from recent studies using animal models that membrane complement regulatory proteins are important modulators of tissue injury in many autoimmune and inflammatory disease settings. Evidence is also emerging to support a role of these proteins in regulating cellular immunity. In this article, we highlight recent advances on the in vivo biology of membrane complement regulatory proteins and discuss their relevance in human disease pathogenesis and therapeutics.
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Affiliation(s)
- David D Kim
- Institute for Translational Medicine, University of Pennsylvania School of Medicine, Rm 1254 BRBII/III, 421 Curie Blvd, Philadelphia, PA 19104, USA
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Mendicino M, Liu M, Ghanekar A, He W, Koscik C, Shalev I, Javadi M, Turnbull J, Chen W, Fung L, Sakamoto S, Marsden P, Waddell TK, Phillips MJ, Gorczynski R, Levy GA, Grant D. Targeted deletion of Fgl-2/fibroleukin in the donor modulates immunologic response and acute vascular rejection in cardiac xenografts. Circulation 2005; 112:248-56. [PMID: 15998670 DOI: 10.1161/circulationaha.105.534271] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND Xenografts ultimately fail as a result of acute vascular rejection (AVR), a process characterized by intravascular thrombosis, fibrin deposition, and endothelial cell activation. METHODS AND RESULTS We studied whether targeted deletion of Fgl-2, an inducible endothelial cell procoagulant, (Fgl-2-/-) in the donor prevents AVR in a mouse-to-rat cardiac xenotransplantation model. By 3 days after transplant, Fgl-2+/+ grafts developed typical features of AVR associated with increased levels of donor Fgl-2 mRNA. Grafts from Fgl-2-/- mice had reduced fibrin deposition but developed cellular rejection. Treatment with a short course of cobra venom factor and maintenance cyclosporine resulted in long-term acceptance of both Fgl-2+/+ and Fgl-2-/- grafts. On withdrawal of cyclosporine, Fgl-2+/+ grafts developed features of AVR; in contrast, Fgl-2-/- grafts again developed acute cellular rejection. Rejecting Fgl-2+/+ hearts stained positively for IgG, IgM, C3, and C5b-9, whereas rejecting Fgl-2-/- hearts had minimal Ig and complement deposition despite xenoantibodies in the serum. Furthermore, serum containing xenoantibodies failed to stain Fgl-2-/- long-term treated hearts but did stain wild-type heart tissues. Treatment of Fgl-2-/- xenografts with mycophenolate mofetil and tacrolimus, a clinically relevant immune suppression protocol, led to long-term graft acceptance. CONCLUSIONS Deletion of Fgl-2 ameliorates AVR by downregulation of xenoantigens and may facilitate successful clinical heart xenotransplantation.
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Affiliation(s)
- Michael Mendicino
- Multi Organ Transplant Program, University Health Network, Toronto, Ontario, Canada
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White J, Lukacik P, Esser D, Steward M, Giddings N, Bright JR, Fritchley SJ, Morgan BP, Lea SM, Smith GP, Smith RAG. Biological activity, membrane-targeting modification, and crystallization of soluble human decay accelerating factor expressed in E. coli. Protein Sci 2004; 13:2406-15. [PMID: 15322283 PMCID: PMC2280017 DOI: 10.1110/ps.03455604] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Decay-accelerating factor (DAF, CD55) is a glycophosphatidyl inositol-anchored glycoprotein that regulates the activity of C3 and C5 convertases. In addition to understanding the mechanism of complement inhibition by DAF through structural studies, there is also an interest in the possible therapeutic potential of the molecule. In this report we describe the cloning, expression in Escherichia coli, isolation and membrane-targeting modification of the four short consensus repeat domains of soluble human DAF with an additional C-terminal cysteine residue to permit site-specific modification. The purified refolded recombinant protein was active against both classical and alternative pathway assays of complement activation and had similar biological activity to soluble human DAF expressed in Pichia pastoris. Modification with a membrane-localizing peptide restored cell binding and gave a large increase in antihemolytic potency. These data suggested that the recombinant DAF was correctly folded and suitable for structural studies as well as being the basis for a DAF-derived therapeutic. Crystals of the E. coli-derived protein were obtained and diffracted to 2.2 A, thus permitting the first detailed X-ray crystallography studies on a functionally active human complement regulator protein with direct therapeutic potential.
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Affiliation(s)
- Jennifer White
- Adprotech Ltd., Chesterford Research Park, Little Chesterford, Saffron Walden, Essex CB10 1XL, UK
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Abstract
Xenotransplantation, in particular transplantation of pig cells, tissues and organs into human patients, may alleviate the current shortage of suitable allografts available for human transplantation. This overview addresses the physiological, immunological and virological factors considered with regard to xenotransplantation. Among the issues reviewed are the merits of using pigs as xenograft source species, the compatibility of pig and human organ physiology and the immunological hindrances with regard to the various types of rejection and attempts at abrogating rejection. Advances in the prevention of pig organ rejection by creating genetically modified pigs that are more suited to the human microenvironment are also discussed. Finally, with regard to virology, possible zoonotic infections emanating from pigs are reviewed, with special emphasis on the pig endogenous retrovirus (PERV). An in depth account of PERV studies, comprising their discovery as well as recent knowledge of the virus, is given. To date, all retrospective studies on patients with pig xenografts have shown no evidence of PERV transmission, however, many factors make us interpret these results with caution. Although the lack of PERV infection in xenograft recipients up to now is encouraging, more basic research and controlled animal studies that mimic the pig to human xenotransplantation setting more closely are required for safety assessment.
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Affiliation(s)
- Saema Magre
- Wohl Virion Centre, The Windeyer Institute of Medical Sciences, University College London, 46 Cleveland Street, London W1T 4JF, UK
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