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Meredith R, Zhu Y, Yoon MK, Tetrault T, Lin J, Zhang W, McGurn M, Cook E, Popp R, Shit P, Carmichael I, Serianni AS. Methyl α-D-galactopyranosyl-(1→3)-β-D-galactopyranoside and methyl β-D-galactopyranosyl-(1→3)-β-D-galactopyranoside: Glycosidic linkage conformation determined from MA'AT analysis. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:544-555. [PMID: 38414300 DOI: 10.1002/mrc.5424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 12/19/2023] [Accepted: 12/20/2023] [Indexed: 02/29/2024]
Abstract
MA'AT analysis has been applied to two biologically-important O-glycosidic linkages in two disaccharides, α-D-Galp-(1→3)-β-D-GalpOMe (3) and β-D-Galp-(1→3)-β-D-GalpOMe (4). Using density functional theory (DFT) to obtain parameterized equations relating a group of trans-O-glycosidic NMR spin-couplings to either phi (ϕ') or psi (ψ'), and experimental 3JCOCH, 2JCOC, and 3JCOCC spin-couplings measured in aqueous solution in 13C-labeled isotopomers, probability distributions of ϕ' and ψ' in each linkage were determined and compared to those determined by aqueous 1-μs molecular dynamics (MD) simulation. Good agreement was found between the MA'AT and single-state MD conformational models of these linkages for the most part, with modest (approximately <15°) differences in the mean values of ϕ' and ψ', although the envelope of allowed angles (encoded in circular standard deviations or CSDs) is consistently larger for ϕ' determined from MA'AT analysis than from MD for both linkages. The MA'AT model of the α-Galp-(1→3)-β-Galp linkage agrees well with those determined previously using conventional NMR methods (3JCOCH values and/or 1H-1H NOEs), but some discrepancy was observed for the β-Galp-(1→3)-β-Galp linkage, which may arise from errors in the conventions used to describe the linkage torsion angles. Statistical analyses of X-ray crystal structures show ranges of ϕ' and ψ' for both linkages that include the mean angles determined from MA'AT analyses, although both angles adopt a wide range of values in the crystalline state, with ϕ' in β-Galp-(1→3)-β-Galp linkages showing greater-than-expected conformational variability.
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Affiliation(s)
- Reagan Meredith
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Yuping Zhu
- Discovery Chemistry, Merck Research Laboratories, Kenilworth, New Jersey, USA
| | - Mi-Kyung Yoon
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Timothy Tetrault
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Jieye Lin
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Wenhui Zhang
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Margaret McGurn
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Evan Cook
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Reed Popp
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Pradip Shit
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - Ian Carmichael
- Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana, USA
| | - Anthony S Serianni
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
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2
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Vadori M, Cozzi E. Current challenges in xenotransplantation. Curr Opin Organ Transplant 2024; 29:205-211. [PMID: 38529696 PMCID: PMC11064916 DOI: 10.1097/mot.0000000000001146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/27/2024]
Abstract
PURPOSE OF REVIEW In recent years, the xenotransplantation science has advanced tremendously, with significant strides in both preclinical and clinical research. This review intends to describe the latest cutting-edge progress in knowledge and methodologies developed to overcome potential obstacles that may preclude the translation and successful application of clinical xenotransplantation. RECENT FINDINGS Preclinical studies have demonstrated that it is now possible to extend beyond two years survival of primate recipients of life saving xenografts. This has been accomplished thanks to the utilization of genetic engineering methodologies that have allowed the generation of specifically designed gene-edited pigs, a careful donor and recipient selection, and appropriate immunosuppressive strategies.In this light, the compassionate use of genetically modified pig hearts has been authorized in two human recipients and xenotransplants have also been achieved in human decedents. Although encouraging the preliminary results suggest that several challenges have yet to be fully addressed for a successful clinical translation of xenotransplantation. These challenges include immunologic, physiologic and biosafety aspects. SUMMARY Recent progress has paved the way for the initial compassionate use of pig organs in humans and sets the scene for a wider application of clinical xenotransplantation.
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Affiliation(s)
- Marta Vadori
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua
| | - Emanuele Cozzi
- Department of Cardiac, Thoracic, Vascular Sciences and Public Health, University of Padua
- Transplant Immunology Unit, Department of Cardiac, Thoracic, Vascular Sciences and Public Health Padua University Hospital, Padua, Italy
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3
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Cooper DKC, Raza SS, Chaban R, Pierson RN. Shooting for the moon: Genome editing for pig heart xenotransplantation. J Thorac Cardiovasc Surg 2023; 166:973-980. [PMID: 35659123 PMCID: PMC10124774 DOI: 10.1016/j.jtcvs.2022.04.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Revised: 04/04/2022] [Accepted: 04/16/2022] [Indexed: 10/18/2022]
Abstract
Gene-edited pigs could eventually provide organs that are safely and effectively protected from the human immune response without exogenous immunosuppression. Genome editing technology has revolutionized heart xenotransplantation and made transplantation of bioengineered pig hearts into humans a possibility. This first clinical application resulted from a tremendous amount of research. Dramatic early attempts of clinical cardiac xenotransplantation during the last century paved the way to modern xenotransplantation using bioengineered pig hearts. It appears that such genome-edited hearts will be most suitable for neonates and infants because of their immature immune system. The bioengineered pig heart may also be used as a bridge to human heart transplantation, avoiding the risk of thromboembolic events of durable ventricular assist devises in these young children. It is also intriguing to think that bioengineered hearts using pigs as a host may result in a new source of donor hearts that would not evoke the human immune response and minimize, if not eliminate, the need for immunosuppression. It this issue of the Journal, a group of experts led by Dr Cooper, whose personal work spans over 50 years of heart transplantation research, outline the current state of the genome editing of bioengineered hearts and discuss the prospects of clinical application.
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Affiliation(s)
- David K C Cooper
- Center for Transplantation Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, Mass
| | | | - Ryan Chaban
- Center for Transplantation Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, Mass; Department of Cardiovascular Surgery, University Hospital of Johannes Gutenberg University, Mainz, Germany.
| | - Richard N Pierson
- Center for Transplantation Sciences, Massachusetts General Hospital and Harvard Medical School, Boston, Mass
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4
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Tector AJ, Adams AB, Tector M. Current Status of Renal Xenotransplantation and Next Steps. KIDNEY360 2023; 4:278-284. [PMID: 36821619 PMCID: PMC10103350 DOI: 10.34067/kid.0007152021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 12/18/2022] [Indexed: 12/23/2022]
Abstract
Renal transplantation is the preferred treatment of ESKD, but the shortage of suitable donor kidneys from the cadaver pool means that many patients with ESKD will not receive a kidney transplant. Xenotransplantation has long represented a solution to the kidney shortage, but the occurrence of antibody-mediated rejection has precluded its clinical development. Developments in somatic cell nuclear transfer in pigs and gene editing tools have led to the creation of new donor pigs with greatly improved crossmatches to patients. In addition, improvements in preclinical kidney xenotransplant survival using new anti-CD40/CD154-based immunosuppression have pushed xenotransplantation to the point where it is reasonable to consider initiating a clinical trial to evaluate this potential therapy in patients.
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Affiliation(s)
- Alfred J. Tector
- Department of Surgery, University of Miami School of Medicine, Miami, Florida
| | - Andrew B. Adams
- Department of Surgery, University of Minnesota School of Medicine, Minneapolis, Minnesota
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5
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DuPont M, Visca H, Moshnikova A, Engelman DM, Reshetnyak YK, Andreev OA. Tumor treatment by pHLIP-targeted antigen delivery. Front Bioeng Biotechnol 2023; 10:1082290. [PMID: 36686229 PMCID: PMC9853002 DOI: 10.3389/fbioe.2022.1082290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 12/12/2022] [Indexed: 01/09/2023] Open
Abstract
Targeted antigen delivery allows activation of the immune system to kill cancer cells. Here we report the targeted delivery of various epitopes, including a peptide, a small molecule, and a sugar, to tumors by pH Low Insertion Peptides (pHLIPs), which respond to surface acidity and insert to span the membranes of metabolically activated cancer and immune cells within tumors. Epitopes linked to the extracellular ends of pH Low Insertion Peptide peptides were positioned at the surfaces of tumor cells and were recognized by corresponding anti-epitope antibodies. Special attention was devoted to the targeted delivery of the nine residue HA peptide epitope from the Flu virus hemagglutinin. The HA sequence is not present in the human genome, and immunity is readily developed during viral infection or immunization with KLH-HA supplemented with adjuvants. We tested and refined a series of double-headed HA-pHLIP agents, where two HA epitopes were linked to a single pH Low Insertion Peptide peptide via two Peg12 or Peg24 polymers, which enable HA epitopes to engage both antibody binding sites. HA-epitopes positioned at the surfaces of tumor cells remain exposed to the extracellular space for 24-48 h and are then internalized. Different vaccination schemes and various adjuvants, including analogs of FDA approved adjuvants, were tested in mice and resulted in a high titer of anti-HA antibodies. Anti-HA antibody binds HA-pHLIP in blood and travels as a complex leading to significant tumor targeting with no accumulation in organs and to hepatic clearance. HA-pHLIP agents induced regression of 4T1 triple negative breast tumor and B16F10 MHC-I negative melanoma tumors in immunized mice. The therapeutic efficacy potentially is limited by the drop of the level of anti-HA antibodies in the blood to background level after three injections of HA-pHLIP. We hypothesize that additional boosts would be required to keep a high titer of anti-HA antibodies to enhance efficacy. pH Low Insertion Peptide-targeted antigen therapy may provide an opportunity to treat tumors unresponsive to T cell based therapies, having a small number of neo-antigens, or deficient in MHC-I presentation at the surfaces of cancer cells either alone or in combination with other approaches.
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Affiliation(s)
- Michael DuPont
- Physics Department, University of Rhode Island, Kingston, RI, United States
| | - Hannah Visca
- Physics Department, University of Rhode Island, Kingston, RI, United States
| | - Anna Moshnikova
- Physics Department, University of Rhode Island, Kingston, RI, United States
| | - Donald M. Engelman
- Department of Molecular Biophysics and Biochemistry, Yale, New Haven, CT, United States
| | - Yana K. Reshetnyak
- Physics Department, University of Rhode Island, Kingston, RI, United States
| | - Oleg A. Andreev
- Physics Department, University of Rhode Island, Kingston, RI, United States
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Kavarana S, Kwon JH, Zilinskas K, Kang L, Turek JW, Mohiuddin MM, Rajab TK. Recent advances in porcine cardiac xenotransplantation: from aortic valve replacement to heart transplantation. Expert Rev Cardiovasc Ther 2022; 20:597-608. [PMID: 35818712 DOI: 10.1080/14779072.2022.2100760] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
INTRODUCTION Cardiac xenotransplantation presents significant potential to the field of heart failure by addressing the high demand for donor organs. The availability of xenograft hearts would substantially augment the number of life-saving organs available to patients and may ultimately liberalize eligibility criteria for transplantation. AREAS COVERED In this review, we will discuss the need for cardiac xenotransplantation and the history of research and clinical practice in this field. Specifically, we address immunologic concepts and clinical lessons learned from heart valve replacement using xenogeneic tissues, the advancement of xenotransplantation using organs from genetically modified animals, and the progression of this research to the first-in-man pig-to-human heart transplantation. EXPERT OPINION Cardiac xenotransplantation holds tremendous promise, but the indications for this new treatment will need to be clearly defined because mechanical support with ventricular assist devices and total artificial hearts are increasingly successful alternatives for adults in heart failure. Cardiac xenotransplantation will also serve as temporary bridge to allotransplantation in babies with complex congenital heart disease who are too small for the currently available mechanical assist devices. Moreover, xenotransplantation of the part of the heart containing a heart valve could deliver growing heart valve implants for babies with severe heart valve dysfunction.
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Mahmoud A, Toth I, Stephenson R. Developing an Effective Glycan‐Based Vaccine for
Streptococcus Pyogenes. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202115342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Asmaa Mahmoud
- School of Chemistry and Molecular Biosciences The University of Queensland St Lucia Australia
| | - Istvan Toth
- School of Chemistry and Molecular Biosciences The University of Queensland Woolloongabba Australia
- School of Pharmacy The Universitry of Queensland St Lucia Australia
- Institue for Molecular Biosciences The University of Queensland St Lucia Australia
| | - Rachel Stephenson
- School of Chemistry and Molecular Biosciences The University of Queensland St Lucia Australia
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Mahmoud A, Toth I, Stephenson R. Developing an Effective Glycan-based Vaccine for Streptococcus Pyogenes. Angew Chem Int Ed Engl 2021; 61:e202115342. [PMID: 34935243 DOI: 10.1002/anie.202115342] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Indexed: 11/11/2022]
Abstract
Streptococcus pyogenes is a primary infective agent that causes approximately 700 million human infections each year, resulting in more than 500,000 deaths. Carbohydrate-based vaccines are proven to be one of the most promising subunit vaccine candidates, as the bacterial glycan pattern(s) are different from mammalian cells and show increased pathogen serotype conservancy than the protein components. In this review we highlight reverse vaccinology for use in the development of subunit vaccines against S. pyogenes, and report reproducible methods of carbohydrate antigen production, in addition to the structure-immunogenicity correlation between group A carbohydrate epitopes and alternative vaccine antigen carrier systems. We also report recent advances used to overcome hurdles in carbohydrate-based vaccine development.
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Affiliation(s)
- Asmaa Mahmoud
- The University of Queensland - Saint Lucia Campus: The University of Queensland, School of Chemistry and Molecular Biosciences, AUSTRALIA
| | - Istvan Toth
- The University of Queensland - Saint Lucia Campus: The University of Queensland, School of Chemistry and Molecular Biosciences, AUSTRALIA
| | - Rachel Stephenson
- The University of Queensland, School of Chemistry and Molecular Biosciences, The University of Queensland, 4068, Brisbane, AUSTRALIA
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9
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Ladowski JM, Houp J, Hauptfeld-Dolejsek V, Javed M, Hara H, Cooper DKC. Aspects of histocompatibility testing in xenotransplantation. Transpl Immunol 2021; 67:101409. [PMID: 34015463 PMCID: PMC8197754 DOI: 10.1016/j.trim.2021.101409] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 05/14/2021] [Indexed: 12/16/2022]
Abstract
Xenotransplantation, using genetically-modified pigs for clinical organ transplantation, is a solution to the organ shortage. The biggest barrier to clinical implementation is the antigenicity of pig cells. Humans possess preformed antibody to pig cells that initiate antibody-mediated rejection of pig organs in primates. Advances in genetic engineering have led to the development of a pig lacking the three known glycan xenoantigens (triple-knockout [TKO] pigs). A significant number of human sera demonstrate no antibody binding to TKO pig cells. As a result of the TKO pig's low antigen expression, survival of life-supporting pig organs in immunosuppressed nonhuman primates has significantly increased, and hope has been renewed for clinical trials of xenotransplantation. It is important to understand the context in which xenotransplantation's predecessor, allotransplantation, has been successful, and the steps needed for the success of xenotransplantation. Successful allotransplantation has been based on two main immunological approaches - (i) adequate immunosuppressive therapy, and (ii) careful histocompatibility matching. In vivo studies suggest that the available immunosuppressive regimens are adequate to suppress the human anti-pig cellular response. Methods to evaluate and screen patients for the first clinical xenotransplantation trial are the next challenge. The goal of this review is to summarize the history of histocompatibility testing, and the available tools that can be utilized to determine xenograft histocompatibility.
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Affiliation(s)
- Joseph M Ladowski
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Julie Houp
- Histocompatibility Laboratory, University of Alabama at Birmingham, Birmingham, AL, USA
| | | | - Mariyam Javed
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hidetaka Hara
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA.
| | - David K C Cooper
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL, USA
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10
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Barra JM, Kozlovskaya V, Kepple JD, Seeberger KL, Kuppan P, Hunter CS, Korbutt GS, Kharlampieva E, Tse HM. Xenotransplantation of tannic acid-encapsulated neonatal porcine islets decreases proinflammatory innate immune responses. Xenotransplantation 2021; 28:e12706. [PMID: 34245064 DOI: 10.1111/xen.12706] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/10/2021] [Accepted: 06/27/2021] [Indexed: 01/04/2023]
Abstract
BACKGROUND Islet transplantation with neonatal porcine islets (NPIs) is a promising treatment for type 1 diabetes (T1D), but immune rejection poses a major hurdle for clinical use. Innate immune-derived reactive oxygen species (ROS) synthesis can facilitate islet xenograft destruction and enhance adaptive immune responses. METHODS To suppress ROS-mediated xenograft destruction, we utilized nanothin encapsulation materials composed of multilayers of tannic acid (TA), an antioxidant, and a neutral polymer, poly(N-vinylpyrrolidone) (PVPON). We hypothesized that (PVPON/TA)-encapsulated NPIs will maintain euglycemia and dampen proinflammatory innate immune responses following xenotransplantation. RESULTS (PVPON/TA)-encapsulated NPIs were viable and glucose-responsive similar to non-encapsulated NPIs. Transplantation of (PVPON/TA)-encapsulated NPIs into hyperglycemic C57BL/6.Rag or NOD.Rag mice restored euglycemia, exhibited glucose tolerance, and maintained islet-specific transcription factor levels similar to non-encapsulated NPIs. Gene expression analysis of (PVPON/TA)-encapsulated grafts post-transplantation displayed reduced proinflammatory Ccl5, Cxcl10, Tnf, and Stat1 while enhancing alternatively activated macrophage Retnla, Arg1, and Stat6 mRNA accumulation compared with controls. Flow cytometry analysis demonstrated significantly reduced innate immune infiltration, MHC-II, co-stimulatory molecule, and TNF expression with concomitant increases in arginase-1+ macrophages and dendritic cells. Similar alterations in immune responses were observed following xenotransplantation into immunocompetent NOD mice. CONCLUSION Our data suggest that (PVPON/TA) encapsulation of NPIs is an effective strategy to decrease inflammatory innate immune signals involved in NPI xenograft responses through STAT1/6 modulation without compromising islet function.
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Affiliation(s)
- Jessie M Barra
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Veronika Kozlovskaya
- Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA.,Center for Nanoscale Materials and Biointegration, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Jessica D Kepple
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Karen L Seeberger
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Purushothaman Kuppan
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Chad S Hunter
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Medicine, Division of Endocrinology Diabetes and Metabolism, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Gregory S Korbutt
- Department of Surgery, Alberta Diabetes Institute, University of Alberta, Edmonton, AB, Canada
| | - Eugenia Kharlampieva
- Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA.,Department of Chemistry, University of Alabama at Birmingham, Birmingham, AL, USA.,Center for Nanoscale Materials and Biointegration, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Hubert M Tse
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA.,Comprehensive Diabetes Center, University of Alabama at Birmingham, Birmingham, AL, USA.,Center for Nanoscale Materials and Biointegration, University of Alabama at Birmingham, Birmingham, AL, USA
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11
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Spruit CM, Nemanichvili N, Okamatsu M, Takematsu H, Boons GJ, de Vries RP. N-Glycolylneuraminic Acid in Animal Models for Human Influenza A Virus. Viruses 2021; 13:815. [PMID: 34062844 PMCID: PMC8147317 DOI: 10.3390/v13050815] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 04/26/2021] [Accepted: 04/28/2021] [Indexed: 12/14/2022] Open
Abstract
The first step in influenza virus infection is the binding of hemagglutinin to sialic acid-containing glycans present on the cell surface. Over 50 different sialic acid modifications are known, of which N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the two main species. Animal models with α2,6 linked Neu5Ac in the upper respiratory tract, similar to humans, are preferred to enable and mimic infection with unadapted human influenza A viruses. Animal models that are currently most often used to study human influenza are mice and ferrets. Additionally, guinea pigs, cotton rats, Syrian hamsters, tree shrews, domestic swine, and non-human primates (macaques and marmosets) are discussed. The presence of NeuGc and the distribution of sialic acid linkages in the most commonly used models is summarized and experimentally determined. We also evaluated the role of Neu5Gc in infection using Neu5Gc binding viruses and cytidine monophosphate-N-acetylneuraminic acid hydroxylase (CMAH)-/- knockout mice, which lack Neu5Gc and concluded that Neu5Gc is unlikely to be a decoy receptor. This article provides a base for choosing an appropriate animal model. Although mice are one of the most favored models, they are hardly naturally susceptible to infection with human influenza viruses, possibly because they express mainly α2,3 linked sialic acids with both Neu5Ac and Neu5Gc modifications. We suggest using ferrets, which resemble humans closely in the sialic acid content, both in the linkages and the lack of Neu5Gc, lung organization, susceptibility, and disease pathogenesis.
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Affiliation(s)
- Cindy M. Spruit
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands; (C.M.S.); (G.-J.B.)
| | - Nikoloz Nemanichvili
- Division of Pathology, Department of Biomolecular Health Sciences, Faculty of Veterinary Medicine, Utrecht University, 3584 CL Utrecht, The Netherlands;
| | - Masatoshi Okamatsu
- Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0818, Hokkaido, Japan;
| | - Hiromu Takematsu
- Department of Molecular Cell Biology, Faculty of Medical Technology, Graduate School of Health Sciences, Fujita Health University, 1-98 Dengakugakubo, Kutsukake, Toyoake 470-1192, Aichi, Japan;
| | - Geert-Jan Boons
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands; (C.M.S.); (G.-J.B.)
- Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA
| | - Robert P. de Vries
- Department of Chemical Biology & Drug Discovery, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, 3584 CG Utrecht, The Netherlands; (C.M.S.); (G.-J.B.)
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12
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Abstract
Advances in genetic engineering, particularly CRISPR/Cas9, have resulted in the development of a triple glycan-knockout (TKO) pig. There is minimal human antipig antibody binding to TKO pig cells. The TKO background has decreased antibody binding to a sufficiently low level that any additional xenoantigens expressed on the cells can now be more easily detected. One of these xenoantigens is the swine major histocompatibility complex, termed swine leukocyte antigens (SLA). SLA are the homolog to HLAs, a protein complex expressed on human tissue capable of stimulating the development of new antibodies in allotransplantation. These antibodies can result in graft failure through hyperacute, acute, or chronic rejection. Our knowledge of SLA, particularly in the last 5 years, has grown considerably. The presence, cause, and methods to detect anti-SLA antibodies will need to be carefully considered for the first clinical trial of xenotransplantation. The focus of this review is to summarize the role of SLA in xenotransplantation and consider whether it will prove to be a major barrier. Techniques are now available to mutate target SLA amino acids to ensure that cross-reactive anti-HLA antibodies no longer bind to SLA on the cells of the organ-source pigs. While deletion of SLA expression is possible, it would render the pig at risk for infectious complications. The ideal organ-source pig for HLA highly sensitized recipients may therefore be 1 with site-specific mutations to eliminate cross-reactive binding.
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Affiliation(s)
- Joseph M Ladowski
- Xenotransplantation Program, Department of Surgery, University of Alabama at Birmingham, Birmingham, AL
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13
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Extensive germline genome engineering in pigs. Nat Biomed Eng 2020; 5:134-143. [PMID: 32958897 DOI: 10.1038/s41551-020-00613-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 08/22/2020] [Indexed: 12/30/2022]
Abstract
The clinical applicability of porcine xenotransplantation-a long-investigated alternative to the scarce availability of human organs for patients with organ failure-is limited by molecular incompatibilities between the immune systems of pigs and humans as well as by the risk of transmitting porcine endogenous retroviruses (PERVs). We recently showed the production of pigs with genomically inactivated PERVs. Here, using a combination of CRISPR-Cas9 and transposon technologies, we show that pigs with all PERVs inactivated can also be genetically engineered to eliminate three xenoantigens and to express nine human transgenes that enhance the pigs' immunological compatibility and blood-coagulation compatibility with humans. The engineered pigs exhibit normal physiology, fertility and germline transmission of the 13 genes and 42 alleles edited. Using in vitro assays, we show that cells from the engineered pigs are resistant to human humoral rejection, cell-mediated damage and pathogenesis associated with dysregulated coagulation. The extensive genome engineering of pigs for greater compatibility with the human immune system may eventually enable safe and effective porcine xenotransplantation.
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14
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HLA Class I-sensitized Renal Transplant Patients Have Antibody Binding to SLA Class I Epitopes. Transplantation 2020; 103:1620-1629. [PMID: 30951017 DOI: 10.1097/tp.0000000000002739] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
BACKGROUND Highly sensitized patients are difficult to match with suitable renal allograft donors and may benefit from xenotransplant trials. We evaluate antibody binding from sensitized patients to pig cells and engineered single allele cells to identify anti-human leukocyte antigen (HLA) antibody cross-species reactivity with swine leukocyte antigen (SLA). These novel testing strategies assess HLA/SLA epitopes and antibody-binding patterns and introduce genetic engineering of SLA epitopes. METHODS Sensitized patient sera were grouped by calculated panel reactive antibody and luminex single antigen reactivity profile and were tested with cloned GGTA1/CMAH/B4GalNT2 glycan knockout porcine cells. Pig reactivity was assessed by direct flow cytometric crossmatch and studied following elution from pig cells. To study the antigenicity of individual class I HLA and SLA alleles in cells, irrelevant sera binding to lymphoblastoid cells were minimized by CRISPR/Cas9 elimination of endogenous class I and class II HLA, B-cell receptor, and Fc receptor genes. Native HLA, SLA, and mutants of these proteins after mutating 144K to Q were assessed for antibody binding. RESULTS Those with predominately anti-HLA-B&C antibodies, including Bw6 and Bw4 sensitization, frequently have low pig reactivity. Conversely, antibodies eluted from porcine cells are more commonly anti-HLA-A. Single HLA/SLA expressing engineered cells shows variable antigenicity and mutation of 144K to Q reduces antibody binding for some sensitized patients. CONCLUSIONS Anti-HLA antibodies cross-react with SLA class I in predictable patterns, which can be identified with histocompatibility strategies, and SLA class I is a possible target of genetic engineering.
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15
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Kim SC, Mathews DV, Breeden CP, Higginbotham LB, Ladowski J, Martens G, Stephenson A, Farris AB, Strobert EA, Jenkins J, Walters EM, Larsen CP, Tector M, Tector AJ, Adams AB. Long-term survival of pig-to-rhesus macaque renal xenografts is dependent on CD4 T cell depletion. Am J Transplant 2019; 19:2174-2185. [PMID: 30821922 PMCID: PMC6658347 DOI: 10.1111/ajt.15329] [Citation(s) in RCA: 124] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2018] [Revised: 01/22/2019] [Accepted: 02/04/2019] [Indexed: 01/25/2023]
Abstract
The shortage of available organs remains the greatest barrier to expanding access to transplant. Despite advances in genetic editing and immunosuppression, survival in experimental models of kidney xenotransplant has generally been limited to <100 days. We found that pretransplant selection of recipients with low titers of anti-pig antibodies significantly improved survival in a pig-to-rhesus macaque kidney transplant model (6 days vs median survival time 235 days). Immunosuppression included transient pan-T cell depletion and an anti-CD154-based maintenance regimen. Selective depletion of CD4+ T cells but not CD8+ T cells resulted in long-term survival (median survival time >400 days vs 6 days). These studies suggested that CD4+ T cells may have a more prominent role in xenograft rejection compared with CD8+ T cells. Although animals that received selective depletion of CD8+ T cells showed signs of early cellular rejection (marked CD4+ infiltrates), animals receiving selective CD4+ depletion exhibited normal biopsy results until late, when signs of chronic antibody rejection were present. In vitro study results suggested that rhesus CD4+ T cells required the presence of SLA class II to mount an effective proliferative response. The combination of low pretransplant anti-pig antibody and CD4 depletion resulted in consistent, long-term xenograft survival.
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Affiliation(s)
- SC Kim
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - DV Mathews
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - CP Breeden
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - LB Higginbotham
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - J Ladowski
- National Swine Resource and Research Center, University of Missouri, Columbia, Missouri
| | - G Martens
- National Swine Resource and Research Center, University of Missouri, Columbia, Missouri
| | - A Stephenson
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - AB Farris
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia
| | - EA Strobert
- Yerkes National Primate Research Center, School of Medicine, Emory University, Atlanta, Georgia
| | - J Jenkins
- Yerkes National Primate Research Center, School of Medicine, Emory University, Atlanta, Georgia
| | - EM Walters
- National Swine Resource and Research Center, University of Missouri, Columbia, Missouri
| | - CP Larsen
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia,Yerkes National Primate Research Center, School of Medicine, Emory University, Atlanta, Georgia
| | - M Tector
- Comprehensive Transplant Institute, University of Alabama Birmingham School of Medicine, Birmingham, Alabama
| | - AJ Tector
- Comprehensive Transplant Institute, University of Alabama Birmingham School of Medicine, Birmingham, Alabama
| | - AB Adams
- Emory Transplant Center, Department of Surgery, School of Medicine, Emory University, Atlanta, Georgia,Yerkes National Primate Research Center, School of Medicine, Emory University, Atlanta, Georgia
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16
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Jacob NIT, Anraku K, Kimishima A, Zhou B, Collins KC, Lockner JW, Ellis BA, Janda KD. A bioconjugate leveraging xenoreactive antibodies to alleviate cocaine-induced behavior. Chem Commun (Camb) 2018; 53:8156-8159. [PMID: 28677711 DOI: 10.1039/c7cc04055e] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
A method for potentiating the response to an anti-cocaine vaccine by leveraging xenoreactive antibodies against the carbohydrate epitope Galα1,3-Gal (GAL) was found to result in a highly specific anti-cocaine response that was able to significantly attenuate cocaine-induced locomotion at 20 mg kg-1 with superior efficacy compared to a standard conjugate.
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Affiliation(s)
- NIcholas T Jacob
- Department of Chemistry, Department of Immunology and Microbial Science, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N. Torrey Pines Rd, La Jolla, CA 92037, USA.
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17
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Abstract
PURPOSE OF REVIEW To review the progress in the field of xenotransplantation with special attention to most recent encouraging findings which will eventually bring xenotransplantation to the clinic in the near future. RECENT FINDINGS Starting from early 2000, with the introduction of galactose-α1,3-galactose (Gal)-knockout pigs, prolonged survival especially in heart and kidney xenotransplantation was recorded. However, remaining antibody barriers to non-Gal antigens continue to be the hurdle to overcome. The production of genetically engineered pigs was difficult requiring prolonged time. However, advances in gene editing, such as zinc finger nucleases, transcription activator-like effector nucleases, and most recently clustered regularly interspaced short palindromic repeats (CRISPR) technology made the production of genetically engineered pigs easier and available to more researchers. Today, the survival of pig-to-nonhuman primate heterotopic heart, kidney, and islet xenotransplantation reached more than 900, more than 400, and more than 600 days, respectively. The availability of multiple-gene pigs (five or six genetic modifications) and/or newer costimulation blockade agents significantly contributed to this success. Now, the field is getting ready for clinical trials with an international consensus. SUMMARY Clinical trials in cellular or solid organ xenotransplantation are getting closer with convincing preclinical data from many centers. The next decade will show us new achievements and additional barriers in clinical xenotransplantation.
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18
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Anraku K, Sato S, Jacob NT, Eubanks LM, Ellis BA, Janda KD. The design and synthesis of an α-Gal trisaccharide epitope that provides a highly specific anti-Gal immune response. Org Biomol Chem 2018; 15:2979-2992. [PMID: 28294277 DOI: 10.1039/c7ob00448f] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Carbohydrate antigens displaying Galα(1,3)Gal epitopes are recognized by naturally occurring antibodies in humans. These anti-Gal antibodies comprise up to 1% of serum IgG and have been viewed as detrimental as they are responsible for hyperacute organ rejections. In order to model this condition, α(1,3)galactosyltransferase-knockout mice are inoculated against the Galα(1,3)Gal epitope. In our study, two α-Gal trisaccharide epitopes composed of either Galα(1,3)Galβ(1,4)GlcNAc or Galα(1,3)Galβ(1,4)Glc linked to a squaric acid ester moiety were examined for their ability to elicit immune responses in KO mice. Both target epitopes were synthesized using a two-component enzymatic system using modified disaccharide substrates containing a linker moiety for coupling. While both glycoconjugate vaccines induced the required high anti-Gal IgG antibody titers, it was found that this response had exquisite specificity for the Galα(1,3)Galβ(1,4)GlcNAc hapten used, with little cross reactivity with the Galα(1,3)Galβ(1,4)Glc hapten. Our findings indicate that while homogenous glycoconjugate vaccines provide high IgG titers, the carrier and adjuvanting factors can deviate the specificity to an antigenic determinant outside the purview of interest.
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Affiliation(s)
- Kensaku Anraku
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA. and Department of Medical Technology, Kumamoto Health Science University, 325 Izumi-machi, Kita-ku, Kumamoto 861-5598, Japan
| | - Shun Sato
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA. and Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5-2, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan
| | - Nicholas T Jacob
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA.
| | - Lisa M Eubanks
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA.
| | - Beverly A Ellis
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA.
| | - Kim D Janda
- Departments of Chemistry and Immunology, The Skaggs Institute for Chemical Biology, The Worm Institute for Research and Medicine (WIRM), The Scripps Research Institute, 10550 N Torrey Pines Rd BCC-582, La Jolla, CA 92037, USA.
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Cimeno A, Hassanein W, French BM, Powell JM, Burdorf L, Goloubeva O, Cheng X, Parsell DM, Ramsoondar J, Kuravi K, Vaught T, Uluer MC, Redding E, O'Neill N, Laird C, Hershfeld A, Tatarov I, Thomas K, Ayares D, Azimzadeh AM, Pierson RN, Barth RN, LaMattina JC. N-glycolylneuraminic acid knockout reduces erythrocyte sequestration and thromboxane elaboration in an ex vivo pig-to-human xenoperfusion model. Xenotransplantation 2017; 24. [PMID: 28940313 DOI: 10.1111/xen.12339] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 05/31/2017] [Accepted: 07/15/2017] [Indexed: 01/26/2023]
Abstract
BACKGROUND Wild-type pigs express several carbohydrate moieties on their cell surfaces that differ from those expressed by humans. This difference in profile leads to pig tissue cell recognition of human blood cells causing sequestration, in addition to antibody-mediated xenograft injury. One such carbohydrate is N-glycolylneuraminic acid (Neu5Gc), a sialic acid molecule synthesized in pigs but not in humans. Here, we evaluate livers with and without Neu5Gc in an ex vivo liver xeno perfusion model. METHODS Livers from pigs with an α1,3-galactosyl transferase gene knockout (GalTKO) and transgenic for human membrane cofactor (hCD46) with (n = 5) or without (n = 7) an additional Neu5Gc gene knock out (Neu5GcKO) were perfused ex vivo with heparinized whole human blood. A drug regimen consisting of a histamine inhibitor, thromboxane synthase inhibitor, and a murine anti-human GPIb-blocking antibody fragment was given to half of the experiments in each group. RESULTS Liver function tests (AST and ALT) were not significantly different between livers with and without the Neu5GcKO. GalTKO.hCD46.Neu5GcKO livers had less erythrocyte sequestration as evidenced by a higher mean hematocrit over time compared to GalTKO.hCD46 livers (P = .0003). The addition of Neu5GcKO did not ameliorate profound thrombocytopenia seen within the first 15 minutes of perfusion. TXB2 was significantly less with the added drug regimen (P = .006) or the presence of Neu5GcKO (P = .017). CONCLUSIONS The lack of Neu5Gc expression attenuated erythrocyte loss but did not prevent profound early onset thrombocytopenia or platelet activation, although TXB2 levels were decreased in the presence of Neu5GcKO.
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Affiliation(s)
- Arielle Cimeno
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Wessam Hassanein
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Beth M French
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Jessica M Powell
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Lars Burdorf
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Olga Goloubeva
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Xiangfei Cheng
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Dawn M Parsell
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | | | | | - Mehmet C Uluer
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Emily Redding
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Natalie O'Neill
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Christopher Laird
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Alena Hershfeld
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Ivan Tatarov
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Kathryn Thomas
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | | | - Agnes M Azimzadeh
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Richard N Pierson
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - Rolf N Barth
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
| | - John C LaMattina
- Department of Surgery, University of Maryland School of Medicine, Baltimore, MD, USA
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20
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Giorgi ME, Lopez R, Agusti R, Marino C, de Lederkremer RM. Synthesis of a model trisaccharide for studying the interplay between the anti α-Gal antibody and the trans-sialidase reactions in Trypanosoma cruzi. Carbohydr Res 2017; 450:30-37. [PMID: 28858610 DOI: 10.1016/j.carres.2017.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2017] [Revised: 08/15/2017] [Accepted: 08/15/2017] [Indexed: 12/16/2022]
Abstract
Trypanosoma cruzi, the etiologic agent of Chagas disease, is covered by a dense glycocalix mainly composed by glycoproteins called mucins which are also the acceptors of sialic acid in a reaction catalyzed by a trans-sialidase (TcTS). Sialylation of trypomastigote mucins protects the parasite from lysis by the anti α-Galp antibodies from serum. The TcTS is essential for the infection process since T. cruzi is unable to biosynthesize sialic acid. The enzyme specifically transfers it from a terminal β-d-Galp unit in the host glycoconjugate to terminal β-d-Galp units in the parasite mucins to construct the d-NeuNAc(α2→3)β-d-Galp motif. On the other hand, although galactose is the most abundant sugar in mucins of both, the infective trypomastigotes and the insect stage epimastigotes, α-d-Galp is only present in the infective stage whereas β-d-Galf is characteristic of the epimastigote stage of the less virulent strains. Neither α-d-Galp nor d-Galf is acceptor of sialic acid. In the mucins, some of the oligosaccharides are branched with terminal β-d-Galp units to be able to accept sialic acid in the TcTS reaction. Based on previous reports showing that anti α-Galp antibodies only partially colocalize with sialic acid, we have undertaken the synthesis of the trisaccharide α-d-Galp(1→3)-[β-d-Galp(1→6)]-d-Galp, the smallest structure containing both, the antigenic d-Galp(α1→3)-d-Galp unit and the sialic acid-acceptor β-d-Galp unit. The trisaccharide was obtained as the 6-aminohexyl glycoside to facilitate further conjugation for biochemical studies. The synthetic approach involved the α-galactosylation at O-4 of a suitable precursor of the reducing end, followed by β-galactosylation at O-6 of the same precursor and introduction of the 6-aminohexyl aglycone. The fully deprotected trisaccharide was successfully sialylated by TcTS using either 3'-sialyllactose or fetuin as donors. The product, 6-aminohexyl α-d-NeuNAc(2→3)-β-d-Galp(1→6)-[α-d-Galp(1→3)]-β-d-Galp, was purified and characterized.
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Affiliation(s)
- M Eugenia Giorgi
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina
| | - Rosana Lopez
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina
| | - Rosalia Agusti
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina
| | - Carla Marino
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina.
| | - Rosa M de Lederkremer
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Centro de Investigaciones en Hidratos de Carbono (CIHIDECAR), Facultad de Ciencias Exactas y Naturales, Departamento de Química Orgánica, Buenos Aires, Argentina.
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21
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Abstract
Simple and complex carbohydrates (glycans) have long been known to play major metabolic, structural and physical roles in biological systems. Targeted microbial binding to host glycans has also been studied for decades. But such biological roles can only explain some of the remarkable complexity and organismal diversity of glycans in nature. Reviewing the subject about two decades ago, one could find very few clear-cut instances of glycan-recognition-specific biological roles of glycans that were of intrinsic value to the organism expressing them. In striking contrast there is now a profusion of examples, such that this updated review cannot be comprehensive. Instead, a historical overview is presented, broad principles outlined and a few examples cited, representing diverse types of roles, mediated by various glycan classes, in different evolutionary lineages. What remains unchanged is the fact that while all theories regarding biological roles of glycans are supported by compelling evidence, exceptions to each can be found. In retrospect, this is not surprising. Complex and diverse glycans appear to be ubiquitous to all cells in nature, and essential to all life forms. Thus, >3 billion years of evolution consistently generated organisms that use these molecules for many key biological roles, even while sometimes coopting them for minor functions. In this respect, glycans are no different from other major macromolecular building blocks of life (nucleic acids, proteins and lipids), simply more rapidly evolving and complex. It is time for the diverse functional roles of glycans to be fully incorporated into the mainstream of biological sciences.
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Affiliation(s)
- Ajit Varki
- Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center, University of California at San Diego, La Jolla, CA 92093-0687, USA
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