1
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Vaill M, Kawanishi K, Varki N, Gagneux P, Varki A. Comparative physiological anthropogeny: exploring molecular underpinnings of distinctly human phenotypes. Physiol Rev 2023; 103:2171-2229. [PMID: 36603157 PMCID: PMC10151058 DOI: 10.1152/physrev.00040.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Revised: 12/26/2022] [Accepted: 12/28/2022] [Indexed: 01/06/2023] Open
Abstract
Anthropogeny is a classic term encompassing transdisciplinary investigations of the origins of the human species. Comparative anthropogeny is a systematic comparison of humans and other living nonhuman hominids (so-called "great apes"), aiming to identify distinctly human features in health and disease, with the overall goal of explaining human origins. We begin with a historical perspective, briefly describing how the field progressed from the earliest evolutionary insights to the current emphasis on in-depth molecular and genomic investigations of "human-specific" biology and an increased appreciation for cultural impacts on human biology. While many such genetic differences between humans and other hominids have been revealed over the last two decades, this information remains insufficient to explain the most distinctive phenotypic traits distinguishing humans from other living hominids. Here we undertake a complementary approach of "comparative physiological anthropogeny," along the lines of the preclinical medical curriculum, i.e., beginning with anatomy and considering each physiological system and in each case considering genetic and molecular components that are relevant. What is ultimately needed is a systematic comparative approach at all levels from molecular to physiological to sociocultural, building networks of related information, drawing inferences, and generating testable hypotheses. The concluding section will touch on distinctive considerations in the study of human evolution, including the importance of gene-culture interactions.
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Affiliation(s)
- Michael Vaill
- Center for Academic Research and Training in Anthropogeny, University of California, San Diego, La Jolla, California
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California
| | - Kunio Kawanishi
- Center for Academic Research and Training in Anthropogeny, University of California, San Diego, La Jolla, California
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California
- Department of Experimental Pathology, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Nissi Varki
- Center for Academic Research and Training in Anthropogeny, University of California, San Diego, La Jolla, California
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California
- Department of Pathology, University of California, San Diego, La Jolla, California
| | - Pascal Gagneux
- Center for Academic Research and Training in Anthropogeny, University of California, San Diego, La Jolla, California
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California
- Department of Pathology, University of California, San Diego, La Jolla, California
| | - Ajit Varki
- Center for Academic Research and Training in Anthropogeny, University of California, San Diego, La Jolla, California
- Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, California
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2
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Essawi K, Hakami W, Naeem Khan MB, Martin R, Zeng J, Chu R, Uchida N, Bonifacino AC, Krouse AE, Linde NS, Donahue RE, Blobel GA, Gerdemann U, Kean LS, Maitland SA, Wolfe SA, Metais JY, Gottschalk S, Bauer DE, Tisdale JF, Demirci S. Pre-existing immunity does not impair the engraftment of CRISPR-Cas9-edited cells in rhesus macaques conditioned with busulfan or radiation. Mol Ther Methods Clin Dev 2023; 29:483-493. [PMID: 37273902 PMCID: PMC10236215 DOI: 10.1016/j.omtm.2023.04.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 04/17/2023] [Indexed: 06/06/2023]
Abstract
CRISPR-Cas9-based therapeutic genome editing approaches hold promise to cure a variety of human diseases. Recent findings demonstrate pre-existing immunity for the commonly used Cas orthologs from Streptococcus pyogenes (SpCas9) and Staphylococcus aureus (SaCas9) in humans, which threatens the success of this powerful tool in clinical use. Thus, a comprehensive investigation and potential risk assessment are required to exploit the full potential of the system. Here, we investigated existence of immunity to SpCas9 and SaCas9 in control rhesus macaques (Macaca mulatta) alongside monkeys transplanted with either lentiviral transduced or CRISPR-SpCas9 ribonucleoprotein (RNP)-edited cells. We observed significant levels of Cas9 antibodies in the peripheral blood of all transplanted and non-transplanted control animals. Transplantation of ex vivo transduced or SpCas9-mediated BCL11A enhancer-edited cells did not alter the levels of Cas9 antibodies in rhesus monkeys. Following stimulation of peripheral blood cells with SpCas9 or SaCas9, neither Cas9-specific T cells nor cytokine induction were detected. Robust and durable editing frequencies and expression of high levels of fetal hemoglobin in BCL11A enhancer-edited rhesus monkeys with no evidence of an immune response (>3 years) provide an optimistic outlook for the use of ex vivo CRISPR-SpCas9 (RNP)-edited cells.
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Affiliation(s)
- Khaled Essawi
- Department of Medical Laboratory Technology, College of Applied Medical Sciences, Jazan University, Gizan, Saudi Arabia
| | - Waleed Hakami
- Department of Medical Laboratory Technology, College of Applied Medical Sciences, Jazan University, Gizan, Saudi Arabia
| | - Muhammad Behroz Naeem Khan
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
- Dr. Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan
| | - Reid Martin
- Department of Bone Marrow Transplantation and Cellular Therapy, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Jing Zeng
- Division of Hematology/Oncology, Boston Children’s Hospital, Boston, MA, USA
| | - Rebecca Chu
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Naoya Uchida
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
- Division of Molecular and Medical Genetics, Center for Gene and Cell Therapy, The Institute of Medical Science, The University of Tokyo, Minato-ku, Tokyo 108-8639, Japan
| | | | - Allen E. Krouse
- Translational Stem Cell Biology Branch, NHLBI, NIH, Bethesda, MD, USA
| | | | - Robert E. Donahue
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Gerd A. Blobel
- Division of Hematology, The Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Ulrike Gerdemann
- Boston Children’s Hospital, Department of Pediatric Oncology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
| | - Leslie S. Kean
- Boston Children’s Hospital, Department of Pediatric Oncology, Dana Farber Cancer Institute and Harvard Medical School, Boston, MA, USA
| | - Stacy A. Maitland
- Department of Molecular, Cell and Cancer Biology, Li Weibo Institute for Rare Diseases Research, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Scot A. Wolfe
- Department of Molecular, Cell and Cancer Biology, Li Weibo Institute for Rare Diseases Research, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Jean-Yves Metais
- Department of Bone Marrow Transplantation and Cellular Therapy, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Stephen Gottschalk
- Department of Bone Marrow Transplantation and Cellular Therapy, St. Jude Children’s Research Hospital, Memphis, TN, USA
| | - Daniel E. Bauer
- Division of Hematology/Oncology, Boston Children’s Hospital, Boston, MA, USA
| | - John F. Tisdale
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
| | - Selami Demirci
- Cellular and Molecular Therapeutics Branch, National Heart Lung and Blood Institutes (NHLBI), National Institutes of Health (NIH), Bethesda, MD, USA
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3
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Stanczak MA, Läubli H. Siglec receptors as new immune checkpoints in cancer. Mol Aspects Med 2023; 90:101112. [PMID: 35948467 DOI: 10.1016/j.mam.2022.101112] [Citation(s) in RCA: 33] [Impact Index Per Article: 33.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 07/26/2022] [Accepted: 07/28/2022] [Indexed: 02/08/2023]
Abstract
Cancer immunotherapy in the form of immune checkpoint inhibitors and cellular therapies has improved the treatment and prognosis of many patients. Nevertheless, most cancers are still resistant to currently approved cancer immunotherapies. New approaches and rational combinations are needed to overcome these resistances. There is emerging evidence that Siglec receptors could be regarded as new immune checkpoints and targets for cancer immunotherapy. In this review, we summarize the experimental evidence supporting Siglec receptors as new immune checkpoints in cancer and discuss their mechanisms of action, as well as current efforts to target Siglec receptors and their interactions with sialoglycan Siglec-ligands.
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Affiliation(s)
- Michal A Stanczak
- The Bloomberg-Kimmel Institute for Cancer Immunotherapy at Johns Hopkins, Baltimore, MD, 21287, USA
| | - Heinz Läubli
- Laboratory for Cancer Immunotherapy, Department of Biomedicine, University of Basel, Division of Oncology, University Hospital Basel, Switzerland.
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4
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Angata T, Varki A. Discovery, classification, evolution and diversity of Siglecs. Mol Aspects Med 2023; 90:101117. [PMID: 35989204 PMCID: PMC9905256 DOI: 10.1016/j.mam.2022.101117] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 08/03/2022] [Accepted: 08/06/2022] [Indexed: 02/08/2023]
Abstract
Immunoglobulin (Ig) superfamily proteins play diverse roles in vertebrates, including regulation of cellular responses by sensing endogenous or exogenous ligands. Siglecs are a family of glycan-recognizing proteins belonging to the Ig superfamily (i.e., I-type lectins). Siglecs are expressed on various leukocyte types and are involved in diverse aspects of immunity, including the regulation of inflammatory responses, leukocyte proliferation, host-microbe interaction, and cancer immunity. Sialoadhesin/Siglec-1, CD22/Siglec-2, and myelin-associated glycoprotein/Siglec-4 were among the first to be characterized as members of the Siglec family, and along with Siglec-15, they are relatively well-conserved among tetrapods. Conversely, CD33/Siglec-3-related Siglecs (CD33rSiglecs, so named as they show high sequence similarity with CD33/Siglec-3) are encoded in a gene cluster with many interspecies variations and even intraspecies variations within some lineages such as humans. The rapid evolution of CD33rSiglecs expressed on leukocytes involved in innate immunity likely reflects the selective pressure by pathogens that interact and possibly exploit these Siglecs. Human Siglecs have several additional unique and/or polymorphic properties as compared with closely related great apes, changes possibly related to the loss of the sialic acid Neu5Gc, another distinctly human event in sialobiology. Multiple changes in human CD33rSiglecs compared to great apes include many examples of human-specific expression in non-immune cells, coinciding with human-specific diseases involving such cell types. Some Siglec gene polymorphisms have dual consequences-beneficial in a situation but detrimental in another. The association of human Siglec gene polymorphisms with several infectious and non-infectious diseases likely reflects the ongoing competition between the host and microbial pathogens.
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Affiliation(s)
- Takashi Angata
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Ajit Varki
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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5
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Figtree GA, Kovacic JC, McGuire HM. Human susceptibility to coronary artery disease: lessons from chimpanzee resilience. Nat Rev Cardiol 2022; 19:497-498. [PMID: 35768694 DOI: 10.1038/s41569-022-00738-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Gemma A Figtree
- Kolling Institute of Medical Research, Sydney, New South Wales, Australia. .,Department of Cardiology, Royal North Shore Hospital, Northern Sydney Local Health District, Sydney, New South Wales, Australia. .,Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia.
| | - Jason C Kovacic
- Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia.,St. Vincent's Clinical School, University of NSW, Sydney, New South Wales, Australia.,Cardiovascular Research Institute, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Helen M McGuire
- Charles Perkins Centre, University of Sydney, Sydney, New South Wales, Australia
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6
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Affiliation(s)
- Robert C Brunham
- University of British Columbia and British Columbia Centre for Disease Control, Vancouver, BC
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7
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Angata T. Possible Influences of Endogenous and Exogenous Ligands on the Evolution of Human Siglecs. Front Immunol 2018; 9:2885. [PMID: 30564250 PMCID: PMC6288428 DOI: 10.3389/fimmu.2018.02885] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 11/23/2018] [Indexed: 12/25/2022] Open
Abstract
Sialic acids, a group of acidic sugars abundantly expressed in the tissues of deuterostome animals but rarely found in microbes, serve as a "signature of self" for these animals. Cognate sensors for sialic acids include Siglecs, a family of transmembrane lectins of vertebrate immune systems that recognize glycans containing sialic acids. A type of sialic acid called N-glycolylneuraminic acid (Neu5Gc) is abundant in many mammalian lineages including great apes, the closest extant relatives of modern human, but was lost in the lineage leading to modern human via the pseudogenization of the CMAH gene encoding the enzyme that converts N-acetylneuraminic acid (Neu5Ac) to Neu5Gc. Loss of Neu5Gc appears to have influenced the evolution of human Siglecs, such as the adjustment of sialic acid binding preferences and the inactivation of at least one Siglec. In addition, various mechanistic studies using model systems and genetic association studies have revealed that some human Siglecs interact with pathogens and influence the outcome of infections, and these pathogens in turn likely influence the evolution of these Siglecs. By understanding the evolutionary forces affecting Siglecs, we shall achieve a better appreciation of Siglec functions, and by understanding Siglec functions, we can obtain deeper insight into the evolutionary processes driving Siglec evolution.
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Affiliation(s)
- Takashi Angata
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
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8
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Abstract
Lectins recognize a diverse array of carbohydrate structures and perform numerous essential biological functions. Here we focus on only two families of lectins, the Siglecs and C-type lectins. Triggering of intracellular signaling cascades following ligand recognition by these receptors can have profound effects on the induction and modulation of immunity. In this chapter, we provide a brief overview of each family and then focus on selected examples that highlight how these lectins can influence myeloid cell functioning in health and disease. Receptors that are discussed include Sn (Siglec-1), CD33 (Siglec-3), and Siglec-5, -7, -8, -9, -10, -11, -14, -15, -E, -F, and -G as well as Dectin-1, MICL, Dectin-2, Mincle/MCL, and the macrophage mannose receptor.
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9
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Varki A. Are humans prone to autoimmunity? Implications from evolutionary changes in hominin sialic acid biology. J Autoimmun 2017; 83:134-142. [PMID: 28755952 DOI: 10.1016/j.jaut.2017.07.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 02/06/2023]
Abstract
Given varied intrinsic and extrinsic challenges to the immune system, it is unsurprising that each evolutionary lineage evolves distinctive features of immunoreactivity, and that tolerance mechanisms fail, allowing autoimmunity. Humans appear prone to many autoimmune diseases, with mechanisms both genetic and environmental. Another rapidly evolving biological system involves sialic acids, a family of monosaccharides that are terminal caps on cell surface and secreted molecules of vertebrates, and play multifarious roles in immunity. We have explored multiple genomic changes in sialic acid biology that occurred in human ancestors (hominins), some with implications for enhanced immunoreactivity, and hence for autoimmunity. Human ancestors lost the enzyme synthesizing the common mammalian sialic acid Neu5Gc, with an accumulation of the precursor sialic acid Neu5Ac. Resulting changes include an enhanced reactivity by some immune cells and increased ability of macrophages to kill bacteria, at the cost of increased endotoxin sensitivity. There are also multiple human-specific evolutionary changes in inhibitory and activating Siglecs, immune cell receptors that recognize sialic acids as "self-associated molecular patterns" (SAMPs) to modulate immunity, but can also be hijacked by pathogen molecular mimicry of SAMPs. Altered expression patterns and fixed or polymorphic SIGLEC pseudogenization in humans has modulated both innate and adaptive immunity, sometimes favoring over-reactivity. Meanwhile, dietary intake of Neu5Gc (derived primarily from red meats) allows metabolic incorporation of this non-human molecule into human cells--apparently the first example of "xeno-autoimmunity" involving "xeno-autoantigen" interactions with circulating "xeno-autoantibodies". Taken together, some of these factors may contribute to the apparent human propensity for autoimmunity.
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Affiliation(s)
- Ajit Varki
- Departments of Medicine and Cellular and Molecular Medicine, Glycobiology Research and Training Center (GRTC) and Center for Academic Research and Training in Anthropogeny (CARTA), University of California, San Diego, La Jolla, CA, 92093-0687, USA.
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10
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Okerblom J, Varki A. Biochemical, Cellular, Physiological, and Pathological Consequences of Human Loss of N-Glycolylneuraminic Acid. Chembiochem 2017; 18:1155-1171. [PMID: 28423240 DOI: 10.1002/cbic.201700077] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 12/15/2022]
Abstract
About 2-3 million years ago, Alu-mediated deletion of a critical exon in the CMAH gene became fixed in the hominin lineage ancestral to humans, possibly through a stepwise process of selection by pathogen targeting of the CMAH product (the sialic acid Neu5Gc), followed by reproductive isolation through female anti-Neu5Gc antibodies. Loss of CMAH has occurred independently in some other lineages, but is functionally intact in Old World primates, including our closest relatives, the chimpanzee. Although the biophysical and biochemical ramifications of losing tens of millions of Neu5Gc hydroxy groups at most cell surfaces remains poorly understood, we do know that there are multiscale effects functionally relevant to both sides of the host-pathogen interface. Hominin CMAH loss might also contribute to understanding human evolution, at the time when our ancestors were starting to use stone tools, increasing their consumption of meat, and possibly hunting. Comparisons with chimpanzees within ethical and practical limitations have revealed some consequences of human CMAH loss, but more has been learned by using a mouse model with a human-like Cmah inactivation. For example, such mice can develop antibodies against Neu5Gc that could affect inflammatory processes like cancer progression in the face of Neu5Gc metabolic incorporation from red meats, display a hyper-reactive immune system, a human-like tendency for delayed wound healing, late-onset hearing loss, insulin resistance, susceptibility to muscular dystrophy pathologies, and increased sensitivity to multiple human-adapted pathogens involving sialic acids. Further studies in such mice could provide a model for other human-specific processes and pathologies involving sialic acid biology that have yet to be explored.
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Affiliation(s)
- Jonathan Okerblom
- Biomedical Sciences Graduate Program, University of California in San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0687, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, GRTC) and, Center for Academic Research and Training in Anthropogeny, CARTA), Departments of Medicine and Cellular and Molecular Medicine, University of California in San Diego, La Jolla, CA, 92093-0687, USA
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11
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Siglec-7 restores β-cell function and survival and reduces inflammation in pancreatic islets from patients with diabetes. Sci Rep 2017; 7:45319. [PMID: 28378743 PMCID: PMC5381285 DOI: 10.1038/srep45319] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/22/2017] [Indexed: 01/16/2023] Open
Abstract
Chronic inflammation plays a key role in both type 1 and type 2 diabetes. Cytokine and chemokine production within the islets in a diabetic milieu results in β-cell failure and diabetes progression. Identification of targets, which both prevent macrophage activation and infiltration into islets and restore β-cell functionality is essential for effective diabetes therapy. We report that certain Sialic-acid-binding immunoglobulin-like-lectins (siglecs) are expressed in human pancreatic islets in a cell-type specific manner. Siglec-7 was expressed on β-cells and down-regulated in type 1 and type 2 diabetes and in infiltrating activated immune cells. Over-expression of Siglec-7 in diabetic islets reduced cytokines, prevented β-cell dysfunction and apoptosis and reduced recruiting of migrating monocytes. Our data suggest that restoration of human Siglec-7 expression may be a novel therapeutic strategy targeted to both inhibition of immune activation and preservation of β-cell function and survival.
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12
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Okerblom JJ, Schwarz F, Olson J, Fletes W, Ali SR, Martin PT, Glass CK, Nizet V, Varki A. Loss of CMAH during Human Evolution Primed the Monocyte-Macrophage Lineage toward a More Inflammatory and Phagocytic State. THE JOURNAL OF IMMUNOLOGY 2017; 198:2366-2373. [PMID: 28148732 DOI: 10.4049/jimmunol.1601471] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 01/04/2017] [Indexed: 12/21/2022]
Abstract
Humans and chimpanzees are more sensitive to endotoxin than are mice or monkeys, but any underlying differences in inflammatory physiology have not been fully described or understood. We studied innate immune responses in Cmah-/- mice, emulating human loss of the gene encoding production of Neu5Gc, a major cell surface sialic acid. CMP-N-acetylneuraminic acid hydroxylase (CMAH) loss occurred ∼2-3 million years ago, after the common ancestor of humans and chimpanzees, perhaps contributing to speciation of the genus HomoCmah-/- mice manifested a decreased survival in endotoxemia following bacterial LPS injection. Macrophages from Cmah-/- mice secreted more inflammatory cytokines with LPS stimulation and showed more phagocytic activity. Macrophages and whole blood from Cmah-/- mice also killed bacteria more effectively. Metabolic reintroduction of Neu5Gc into Cmah-/- macrophages suppressed these differences. Cmah-/- mice also showed enhanced bacterial clearance during sublethal lung infection. Although monocytes and monocyte-derived macrophages from humans and chimpanzees exhibited marginal differences in LPS responses, human monocyte-derived macrophages killed Escherichia coli and ingested E. coli BioParticles better. Metabolic reintroduction of Neu5Gc into human macrophages suppressed these differences. Although multiple mechanisms are likely involved, one cause is altered expression of C/EBPβ, a transcription factor affecting macrophage function. Loss of Neu5Gc in Homo likely had complex effects on immunity, providing greater capabilities to clear sublethal bacterial challenges, possibly at the cost of endotoxic shock risk. This trade-off may have provided a selective advantage when Homo transitioned to butchery using stone tools. The findings may also explain why the Cmah-/- state alters severity in mouse models of human disease.
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Affiliation(s)
- Jonathan J Okerblom
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Department of Medicine, University of California, San Diego, La Jolla, CA 92093.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Flavio Schwarz
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Department of Medicine, University of California, San Diego, La Jolla, CA 92093.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Josh Olson
- Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093
| | - William Fletes
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Initiative for Maximizing Student Development Program, University of California, San Diego, La Jolla, CA 92093
| | - Syed Raza Ali
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Paul T Martin
- Department of Pediatrics, The Ohio State University College of Medicine, Columbus, OH 42305.,Department of Physiology and Cell Biology, The Ohio State University College of Medicine, Columbus, OH 43210; and.,Center for Gene Therapy, The Research Institute at Nationwide Children's Hospital, Columbus, OH 43205
| | - Christopher K Glass
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Department of Medicine, University of California, San Diego, La Jolla, CA 92093.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Victor Nizet
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093.,Department of Pediatrics, University of California, San Diego, La Jolla, CA 92093.,Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA 92093
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA 92093; .,Department of Medicine, University of California, San Diego, La Jolla, CA 92093.,Department of Cellular and Molecular Medicine, University of California, San Diego, La Jolla, CA 92093
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13
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Favier B. Regulation of neutrophil functions through inhibitory receptors: an emerging paradigm in health and disease. Immunol Rev 2016; 273:140-55. [DOI: 10.1111/imr.12457] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Benoit Favier
- CEA, DRF, IMETI, IMVA, UMR 1184, INSERM; Université Paris-Sud; IDMIT Infrastructure; Fontenay-aux-Roses France
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14
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Hünig T. The rise and fall of the CD28 superagonist TGN1412 and its return as TAB08: a personal account. FEBS J 2016; 283:3325-34. [PMID: 27191544 DOI: 10.1111/febs.13754] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 05/04/2016] [Accepted: 05/13/2016] [Indexed: 12/20/2022]
Abstract
Two decades ago, we discovered 'superagonistic' monoclonal antibodies specific for the CD28 molecule which are able to polyclonally activate T cells, in particular regulatory T cells, and are therapeutically active in many rodent models of autoimmunity, inflammation, transplantation, and tissue repair. A phase I trial of the human CD28 superagonist TGN1412 failed in 2006 due to an unexpected cytokine release syndrome, but after it became clear that dose-reduction allows to preferentially address regulatory T cells also in humans, clinical development was resumed under the name TAB08. Here, I recount the story of CD28 superagonist development from a personal perspective with an emphasis on the dramatic events during and after the 2006 phase I trial, the reasons for the failure of preclinical research to warn of the impending cytokine storm, and on the research which allowed resumption of clinical development.
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Affiliation(s)
- Thomas Hünig
- Institute for Virology and Immunobiology, University of Würzburg, Germany.
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15
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Cañas CA, Tobón GJ, Bonilla-Abadía F. The importance of evolution in the development and course of rheumatoid arthritis. Med Hypotheses 2014; 82:784-91. [PMID: 24746382 DOI: 10.1016/j.mehy.2014.03.026] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 03/24/2014] [Indexed: 12/29/2022]
Abstract
Rheumatoid arthritis (RA) is a complex autoimmune disease of recent evolutionary origin. Genetic drift determines diverse polymorphisms implicated in the susceptibility to RA including the major histocompatibility complex (MHC) class II genes in the so-called shared epitope. These genes originated after the divergence between Homo and Pan from their common ancestry Ardipithecus ramidus about 5 million years ago. Natural selection determined the particular changes in the legs (bipedal position), hands, neck, brain and eusociality in humans which influence the clinical presentation of RA. In this article, we hypothesized that the origin and course of RA may be explainable in the light of evolution.
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Affiliation(s)
- C A Cañas
- Rheumatology Unit, Fundación Valle del Lili, Universidad ICESI, Cali, Colombia
| | - G J Tobón
- Rheumatology Unit, Fundación Valle del Lili, Universidad ICESI, Cali, Colombia.
| | - F Bonilla-Abadía
- Rheumatology Unit, Fundación Valle del Lili, Universidad ICESI, Cali, Colombia; Human Molecular Genetics Laboratory, Universidad del Valle, Cali, Colombia
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16
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Inverse hormesis of cancer growth mediated by narrow ranges of tumor-directed antibodies. Proc Natl Acad Sci U S A 2014; 111:5998-6003. [PMID: 24711415 DOI: 10.1073/pnas.1209067111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Compelling evidence for naturally occurring immunosurveillance against malignancies informs and justifies some current approaches toward cancer immunotherapy. However, some types of immune reactions have also been shown to facilitate tumor progression. For example, our previous studies showed that although experimental tumor growth is enhanced by low levels of circulating antibodies directed against the nonhuman sialic acid N-glycolyl-neuraminic acid (Neu5Gc), which accumulates in human tumors, growth could be inhibited by anti-Neu5Gc antibodies from a different source, in a different model. However, it remains generally unclear whether the immune responses that mediate cancer immunosurveillance vs. those responsible for inflammatory facilitation are qualitatively and/or quantitatively distinct. Here, we address this question using multiple murine tumor growth models in which polyclonal antibodies against tumor antigens, such as Neu5Gc, can alter tumor progression. We found that although growth was stimulated at low antibody doses, it was inhibited by high doses, over a linear and remarkably narrow range, defining an immune response curve (IRC; i.e., inverse hormesis). Moreover, modulation of immune responses against the tumor by altering antibody avidity or by enhancing innate immunity shifted the IRC in the appropriate direction. Thus, the dualistic role of immunosurveillance vs. inflammation in modulating tumor progression can be quantitatively distinguished in multiple model systems, and can occur over a remarkably narrow range. Similar findings were made in a human tumor xenograft model using a narrow range of doses of a monoclonal antibody currently in clinical use. These findings may have implications for the etiology, prevention, and treatment of cancer.
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17
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Hodara VL, Parodi LM, Chavez D, Smith LM, Lanford R, Giavedoni LD. Characterization of γδT cells in naïve and HIV-infected chimpanzees and their responses to T-cell activators in vitro. J Med Primatol 2014; 43:258-71. [PMID: 24660852 DOI: 10.1111/jmp.12115] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/28/2014] [Indexed: 01/21/2023]
Abstract
BACKGROUND γδT cells are effector cells that eliminate cancer and virus-infected cells. Chimpanzees are an endangered species that can naturally and experimentally be infected with SIV and HIV, respectively, but no information about the functionality of γδT cells during chronic lentiviral infection is currently available. METHODS Healthy and HIV-infected chimpanzee γδT cells were characterized by flow cytometry. γδT subsets were studied after stimulation with T-cell activators, and the release of cytokines was analyzed by Luminex assay. RESULTS γδT-cell subsets, Vδ1 and Vδ2Vγ9, showed different patterns in the expression of CD4, CD195, CD159a, and CD159c. Stimulation of γδT cells resulted in increased levels of CD4 and HLA-DR, which is more pronounced in Vδ1 T cells. Distinct cytokine patterns were found between healthy and HIV-infected chimpanzees. CONCLUSIONS Analyses of major chimpanzee γδT subsets show similarities to human γδT cells and suggest different functionality and roles in their immune response against HIV infection.
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Affiliation(s)
- Vida L Hodara
- Department of Virology & Immunology, Texas Biomedical Research Institute, San Antonio, TX, USA; Southwest National Primate Research Center, San Antonio, TX, USA
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18
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Wilson GA, Butcher LM, Foster HR, Feber A, Roos C, Walter L, Woszczek G, Beck S, Bell CG. Human-specific epigenetic variation in the immunological Leukotriene B4 Receptor (LTB4R/BLT1) implicated in common inflammatory diseases. Genome Med 2014; 6:19. [PMID: 24598577 PMCID: PMC4062055 DOI: 10.1186/gm536] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2013] [Accepted: 02/24/2014] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Common human diseases are caused by the complex interplay of genetic susceptibility as well as environmental factors. Due to the environment's influence on the epigenome, and therefore genome function, as well as conversely the genome's facilitative effect on the epigenome, analysis of this level of regulation may increase our knowledge of disease pathogenesis. METHODS In order to identify human-specific epigenetic influences, we have performed a novel genome-wide DNA methylation analysis comparing human, chimpanzee and rhesus macaque. RESULTS We have identified that the immunological Leukotriene B4 receptor (LTB4R, BLT1 receptor) is the most epigenetically divergent human gene in peripheral blood in comparison with other primates. This difference is due to the co-ordinated active state of human-specific hypomethylation in the promoter and human-specific increased gene body methylation. This gene is significant in innate immunity and the LTB4/LTB4R pathway is involved in the pathogenesis of the spectrum of human inflammatory diseases. This finding was confirmed by additional neutrophil-only DNA methylome and lymphoblastoid H3K4me3 chromatin comparative data. Additionally we show through functional analysis that this receptor has increased expression and a higher response to the LTB4 ligand in human versus rhesus macaque peripheral blood mononuclear cells. Genome-wide we also find human species-specific differentially methylated regions (human s-DMRs) are more prevalent in CpG island shores than within the islands themselves, and within the latter are associated with the CTCF motif. CONCLUSIONS This result further emphasises the exclusive nature of the human immunological system, its divergent adaptation even from very closely related primates, and the power of comparative epigenomics to identify and understand human uniqueness.
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Affiliation(s)
- Gareth A Wilson
- Medical Genomics, UCL Cancer Institute, University College London, London, UK ; Current address: Translational Cancer Therapeutics, CR-UK London Research Institute, Lincoln's Inn Fields, London, UK
| | - Lee M Butcher
- Medical Genomics, UCL Cancer Institute, University College London, London, UK
| | - Holly R Foster
- MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Andrew Feber
- Medical Genomics, UCL Cancer Institute, University College London, London, UK
| | - Christian Roos
- Genebank of Primates and Primate Genetics Laboratory, German Primate Centre, Leibniz Institute for Primate Research, Göttingen, Germany
| | - Lutz Walter
- Genebank of Primates and Primate Genetics Laboratory, German Primate Centre, Leibniz Institute for Primate Research, Göttingen, Germany
| | - Grzegorz Woszczek
- MRC & Asthma UK Centre in Allergic Mechanisms of Asthma, Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Stephan Beck
- Medical Genomics, UCL Cancer Institute, University College London, London, UK
| | - Christopher G Bell
- Medical Genomics, UCL Cancer Institute, University College London, London, UK ; Current address: Department of Twin Research & Genetic Epidemiology, St Thomas' Hospital, King's College London, London, UK
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19
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Naito-Matsui Y, Takada S, Kano Y, Iyoda T, Sugai M, Shimizu A, Inaba K, Nitschke L, Tsubata T, Oka S, Kozutsumi Y, Takematsu H. Functional evaluation of activation-dependent alterations in the sialoglycan composition of T cells. J Biol Chem 2013; 289:1564-79. [PMID: 24297165 DOI: 10.1074/jbc.m113.523753] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Sialic acids (Sias) are often conjugated to the termini of cellular glycans and are key mediators of cellular recognition. Sias are nine-carbon acidic sugars, and, in vertebrates, the major species are N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc), differing in structure at the C5 position. Previously, we described a positive feedback loop involving regulation of Neu5Gc expression in mouse B cells. In this context, Neu5Gc negatively regulated B-cell proliferation, and Neu5Gc expression was suppressed upon activation. Similarly, resting mouse T cells expressed principally Neu5Gc, and Neu5Ac was induced upon activation. In the present work, we used various probes to examine sialoglycan expression by activated T cells in terms of the Sia species expressed and the linkages of Sias to glycans. Upon T-cell activation, sialoglycan expression shifted from Neu5Gc to Neu5Ac, and the linkage shifted from α2,6 to α2,3. These changes altered the expression levels of sialic acid-binding immunoglobulin-like lectin (siglec) ligands. Expression of sialoadhesin and Siglec-F ligands increased, and that of CD22 ligands decreased. Neu5Gc exerted a negative effect on T-cell activation, both in terms of the proliferative response and in the context of activation marker expression. Suppression of Neu5Gc expression in mouse T and B cells prevented the development of nonspecific CD22-mediated T cell-B cell interactions. Our results suggest that an activation-dependent shift from Neu5Gc to Neu5Ac and replacement of α2,6 by α2,3 linkages may regulate immune cell interactions at several levels.
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20
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Aliesky H, Courtney CL, Rapoport B, McLachlan SM. Thyroid autoantibodies are rare in nonhuman great apes and hypothyroidism cannot be attributed to thyroid autoimmunity. Endocrinology 2013; 154:4896-907. [PMID: 24092641 PMCID: PMC3836060 DOI: 10.1210/en.2013-1717] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 09/26/2013] [Indexed: 11/19/2022]
Abstract
The great apes include, in addition to Homo, the genera Pongo (orangutans), Gorilla (gorillas), and Pan, the latter comprising two species, P. troglodytes (chimpanzees) and P. paniscus (bonobos). Adult-onset hypothyroidism was previously reported in 4 individual nonhuman great apes. However, there is scarce information on normal serum thyroid hormone levels and virtually no data for thyroid autoantibodies in these animals. Therefore, we examined thyroid hormone levels and TSH in all nonhuman great ape genera including adults, adolescents, and infants. Because hypothyroidism in humans is commonly the end result of thyroid autoimmunity, we also tested healthy and hypothyroid nonhuman great apes for antibodies to thyroglobulin (Tg), thyroid peroxidase (TPO), and the TSH receptor (TSHR). We established a thyroid hormone and TSH database in orangutans, gorillas, chimpanzees, and bonobos (447 individuals). The most striking differences are the greatly reduced free-T4 and free-T3 levels in orangutans and gorillas vs chimpanzees and bonobos, and conversely, elevated TSH levels in gorillas vs Pan species. Antibodies to Tg and TPO were detected in only 2.6% of adult animals vs approximately 10% in humans. No animals with Tg, TPO, or TSHR antibodies exhibited thyroid dysfunction. Conversely, hypothyroid nonhuman great apes lacked thyroid autoantibodies. Moreover, thyroid histology in necropsy tissues was similar in euthyroid and hypothyroid individuals, and lymphocytic infiltration was absent in 2 hypothyroid animals. In conclusion, free T4 and free T3 are lower in orangutans and gorillas vs chimpanzees and bonobos, the closest living human relatives. Moreover, thyroid autoantibodies are rare and hypothyroidism is unrelated to thyroid autoimmunity in nonhuman great apes.
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Affiliation(s)
- Holly Aliesky
- Cedars-Sinai Medical Center, 8700 Beverly Boulevard, Suite B-131, Los Angeles, CA 90048.
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21
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Buchlis G, Odorizzi P, Soto PC, Pearce OMT, Hui DJ, Jordan MS, Varki A, Wherry EJ, High KA. Enhanced T cell function in a mouse model of human glycosylation. THE JOURNAL OF IMMUNOLOGY 2013; 191:228-37. [PMID: 23709682 DOI: 10.4049/jimmunol.1202905] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Clinical evidence for a more active immune response in humans compared with our closest hominid relative, the chimpanzee, includes the progression of HIV infection to AIDS, hepatitis B- and C-related inflammation, autoimmunity, and unwanted harmful immune responses to viral gene transfer vectors. Humans have a unique mutation of the enzyme CMP-N-acetylneuraminic acid hydroxylase (CMAH), causing loss of expression of the sialic acid Neu5Gc. This mutation, occurring 2 million years ago, likely altered the expression and function of ITIM-bearing inhibitory receptors (Siglecs) that bind sialic acids. Previous work showed that human T cells proliferate faster than chimpanzee T cells upon equivalent stimulation. In this article, we report that Cmah(-/-) mouse T cells proliferate faster and have greater expression of activation markers than wild-type mouse T cells. Metabolically reintroducing Neu5Gc diminishes the proliferation and activation of both human and murine Cmah(-/-) T cells. Importantly, Cmah(-/-) mice mount greater T cell responses to an adenovirus encoding an adeno-associated virus capsid transgene. Upon lymphocytic choriomeningitis virus infection, Cmah(-/-) mice make more lymphocytic choriomeningitis virus-specific T cells than WT mice, and these T cells are more polyfunctional. Therefore, a uniquely human glycosylation mutation, modeled in mice, leads to a more proliferative and active T cell population. These findings in a human-like mouse model have implications for understanding the hyperimmune responses that characterize some human diseases.
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Affiliation(s)
- George Buchlis
- University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA
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22
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Bhattarai N, McLinden JH, Xiang J, Landay AL, Chivero ET, Stapleton JT. GB virus C particles inhibit T cell activation via envelope E2 protein-mediated inhibition of TCR signaling. THE JOURNAL OF IMMUNOLOGY 2013; 190:6351-9. [PMID: 23686495 DOI: 10.4049/jimmunol.1300589] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Viruses enter into complex interactions within human hosts, leading to facilitation or suppression of each other's replication. Upon coinfection, GB virus C (GBV-C) suppresses HIV-1 replication in vivo and in vitro, and GBV-C coinfection is associated with prolonged survival in HIV-infected people. GBV-C is a lymphotropic virus capable of persistent infection. GBV-C infection is associated with reduced T cell activation in HIV-infected humans, and immune activation is a critical component of HIV disease pathogenesis. We demonstrate that serum GBV-C particles inhibited activation of primary human T cells. T cell activation inhibition was mediated by the envelope glycoprotein E2, because expression of E2 inhibited TCR-mediated activation of Lck. The region on the E2 protein was characterized and revealed a highly conserved peptide motif sufficient to inhibit TCR-mediated signaling. The E2 region contained a predicted Lck substrate site, and substitution of an alanine or histidine for the tyrosine reversed TCR-signaling inhibition. GBV-C E2 protein and a synthetic peptide representing the inhibitory amino acid sequence were phosphorylated by Lck in vitro. The synthetic peptide also inhibited TCR-mediated activation of primary human CD4(+) and CD8(+) T cells. Extracellular microvesicles from GBV-C E2-expressing cells contained E2 protein and inhibited TCR signaling in bystander T cells not expressing E2. Thus, GBV-C reduced global T cell activation via competition between its envelope protein E2 and Lck following TCR engagement. This novel inhibitory mechanism of T cell activation may provide new approaches for HIV and immunoactivation therapy.
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Affiliation(s)
- Nirjal Bhattarai
- Iowa City Veterans Affairs Medical Center, Iowa City, IA 52242, USA
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23
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Potential role of human-specific genes, human-specific microRNAs and human-specific non-coding regulatory RNAs in the pathogenesis of systemic sclerosis and Sjögren's syndrome. Autoimmun Rev 2013; 12:1046-51. [PMID: 23684698 DOI: 10.1016/j.autrev.2013.04.004] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Accepted: 04/24/2013] [Indexed: 12/20/2022]
Abstract
The etiology and pathogenesis of human autoimmune diseases remain unknown despite intensive investigations. Although remarkable progress has been accomplished through genome wide association studies in the identification of genetic factors that may predispose to their occurrence or modify their clinical presentation to date no specific gene abnormalities have been conclusively demonstrated to be responsible for these diseases. The completion of the human and chimpanzee genome sequencing has opened up novel opportunities to examine the possible contribution of human specific genes and other regulatory elements unique to the human genome, such as microRNAs and non-coding RNAs, towards the pathogenesis of a variety of human disorders. Thus, it is likely that these human specific genes and non-coding regulatory elements may be involved in the development or the pathogenesis of various disorders that do not occur in non-human primates including certain autoimmune diseases such as Systemic Sclerosis and Primary Sjögren's Syndrome. Here, we discuss recent evidence supporting the notion that human specific genes or human specific microRNA and other non-coding RNA regulatory elements unique to the human genome may participate in the development or in the pathogenesis of Systemic Sclerosis and Primary Sjögren's Syndrome.
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24
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Abstract
Acquired immunodeficiency syndrome (AIDS) of humans is caused by two lentiviruses, human immunodeficiency viruses types 1 and 2 (HIV-1 and HIV-2). Here, we describe the origins and evolution of these viruses, and the circumstances that led to the AIDS pandemic. Both HIVs are the result of multiple cross-species transmissions of simian immunodeficiency viruses (SIVs) naturally infecting African primates. Most of these transfers resulted in viruses that spread in humans to only a limited extent. However, one transmission event, involving SIVcpz from chimpanzees in southeastern Cameroon, gave rise to HIV-1 group M-the principal cause of the AIDS pandemic. We discuss how host restriction factors have shaped the emergence of new SIV zoonoses by imposing adaptive hurdles to cross-species transmission and/or secondary spread. We also show that AIDS has likely afflicted chimpanzees long before the emergence of HIV. Tracing the genetic changes that occurred as SIVs crossed from monkeys to apes and from apes to humans provides a new framework to examine the requirements of successful host switches and to gauge future zoonotic risk.
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Affiliation(s)
- Paul M Sharp
- Institute of Evolutionary Biology and Centre for Immunity, Infection and Evolution, University of Edinburgh, Edinburgh EH9 3JT, United Kingdom
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25
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Abstract
Given the unprecedented tools that are now available for rapidly comparing genomes, the identification and study of genetic and genomic changes that are unique to our species have accelerated, and we are entering a golden age of human evolutionary genomics. Here we provide an overview of these efforts, highlighting important recent discoveries, examples of the different types of human-specific genomic and genetic changes identified, and salient trends, such as the localization of evolutionary adaptive changes to complex loci that are highly enriched for disease associations. Finally, we discuss the remaining challenges, such as the incomplete nature of current genome sequence assemblies and difficulties in linking human-specific genomic changes to human-specific phenotypic traits.
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Poirier N, Mary C, Dilek N, Hervouet J, Minault D, Blancho G, Vanhove B. Preclinical efficacy and immunological safety of FR104, an antagonist anti-CD28 monovalent Fab' antibody. Am J Transplant 2012; 12:2630-40. [PMID: 22759318 DOI: 10.1111/j.1600-6143.2012.04164.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Antagonist anti-CD28 antibodies prevent T cell costimulation and differentiate from CTLA4Ig since they cannot block CTLA-4 and PDL-1 coinhibitory signals. They demonstrated efficacy in suppressing effector T cells while enhancing regulatory T cells function and immune tolerance. However, anti-CD28 antibodies devoid of immunotoxicity and with a good pharmacokinetic profile have not yet been developed. Here, we describe FR104, a novel humanized pegylated anti-CD28 Fab' antibody fragment presenting a long elimination half-life in monkeys. In vitro, FR104 failed to induce human T cell proliferation and cytokines secretion, even in the presence of anti-CD3 antibodies or when cross-linked with secondary antibodies. Furthermore, in humanized NOD/SCID mice adoptively transferred with human PBMC, whereas superagonist and divalent antibodies elicited rapid cytokines secretion and human T cell activation, FR104 did not. These humanized mice developed a florid graft-versus-host disease, which was prevented by administration of FR104 in a CTLA4-dependent manner. Interestingly, administration of high doses of CTLA4-Ig was ineffective to prevent GVHD, whereas administration of low doses was partially effective. In conclusion, we demonstrated that FR104 is devoid of agonist activity on human T cells and thus compatible with a clinical development that might lead to higher therapeutic indexes, by sparing CTLA-4, as compared to CD80/CD86 antagonists.
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Affiliation(s)
- N Poirier
- Institut National de la Santé Et de la Recherche Médicale Unité Mixte de Recherche 1064, Nantes, France
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27
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Brinkworth JF, Pechenkina EA, Silver J, Goyert SM. Innate immune responses to TLR2 and TLR4 agonists differ between baboons, chimpanzees and humans. J Med Primatol 2012; 41:388-93. [PMID: 22978822 DOI: 10.1111/jmp.12002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/14/2012] [Indexed: 12/17/2022]
Abstract
BACKGROUND African catarrhine primates differ in bacterial disease susceptibility. METHODS Human, chimpanzee, and baboon blood were stimulated with TLR-detected bacterial agonists and cytokine/chemokine induction assessed by real-time PCR. RESULTS Humans and chimpanzees shared similar cytokine/chemokine responses, while baboon cytokine/chemokine induction differed. Generally, responses were agonist independent. CONCLUSIONS These primates tend to generate species rather than agonist-specific responses to bacterial agonists.
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Affiliation(s)
- J F Brinkworth
- Department of Anthropology, Graduate Center, City University of New York, New York, NY, USA.
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28
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Cell-intrinsic mechanism involving Siglec-5 associated with divergent outcomes of HIV-1 infection in human and chimpanzee CD4 T cells. J Mol Med (Berl) 2012; 91:261-70. [PMID: 22945238 PMCID: PMC3558668 DOI: 10.1007/s00109-012-0951-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Revised: 08/10/2012] [Accepted: 08/19/2012] [Indexed: 11/30/2022]
Abstract
Human and chimpanzee CD4+ T cells differ markedly in expression of the inhibitory receptor Siglec-5, which contributes towards differential responses to activating stimuli. While CD4+ T cells from both species are equally susceptible to HIV-1 infection, chimpanzee cells survive better, suggesting a cell-intrinsic difference. We hypothesized that Siglec-5 expression protects T cells from activation-induced and HIV-1-induced cell death. Transduction of human CEM T cells with Siglec-5 decreased cell responses to stimulation. Following HIV-1 infection, a higher percentage of Siglec-5-positive cells survived, suggesting relative resistance to virus-induced cell death. Consistent with this, we observed an increase in percentage of Siglec-5-positive cells surviving in mixed infected cultures. Siglec-5-transduced cells also showed decreased expression of apoptosis-related proteins following infection and reduced susceptibility to Fas-mediated cell death. Similar Siglec-5-dependent differences were seen when comparing infection outcomes in primary CD4+ T cells from humans and chimpanzees. A protective effect of Siglec-5 was further supported by observing greater proportions of circulating CD4+ T cells expressing Siglec-5 in acutely infected HIV-1 patients, compared to controls. Taken together, our results suggest that Siglec-5 expression protects T cells from HIV-1- and apoptosis-induced cell death and contributes to the different outcomes of HIV-1 infection in humans and chimpanzees.
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29
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Poirier N, Blancho G, Vanhove B. CD28-specific immunomodulating antibodies: what can be learned from experimental models? Am J Transplant 2012; 12:1682-90. [PMID: 22471377 DOI: 10.1111/j.1600-6143.2012.04032.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Tolerance induction to alloantigens remains a major challenge in transplant immunology. Progress in the last decade of our understanding of T-cell activation has led to the development of new immunotherapeutic strategies to replace conventional immunosuppression which inhibits the immune system in a nonspecific way. In particular, positive and negative costimulatory molecules of the CD28 family have been consistently demonstrated to be critical for the development of productive immune responses as well as the establishment and maintenance of peripheral tolerance. However, recent discoveries of novel costimulatory interactions confer a novel dimension to the immunoregulatory interactions within the B7:CD28 family and compels a revised view within a "quintet" of costimulatory molecules: CD28/B7/CTLA-4/PD-L1/ICOSL. Complexity introduced in this more detailed costimulatory pathway has important implications in therapeutic interventions against human immunological diseases and, especially, highlight the fundamental differences in selectively targeting CD28 molecules instead of B7 counterparts. In this review, we discuss these differences and emphasize different CD28-specific immunomodulating strategies evaluated in experimental models of transplantation and autoimmune diseases.
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Affiliation(s)
- N Poirier
- Institut National de la Santé Et de la Recherche Médicale, Unité Mixte de Recherche 1064, Nantes, France
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30
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Bailey J. Lessons from chimpanzee-based research on human disease: the implications of genetic differences. Altern Lab Anim 2012; 39:527-40. [PMID: 22243397 DOI: 10.1177/026119291103900608] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Assertions that the use of chimpanzees to investigate human diseases is valid scientifically are frequently based on a reported 98-99% genetic similarity between the species. Critical analyses of the relevance of chimpanzee studies to human biology, however, indicate that this genetic similarity does not result in sufficient physiological similarity for the chimpanzee to constitute a good model for research, and furthermore, that chimpanzee data do not translate well to progress in clinical practice for humans. Leading examples include the minimal citations of chimpanzee research that is relevant to human medicine, the highly different pathology of HIV/AIDS and hepatitis C virus infection in the two species, the lack of correlation in the efficacy of vaccines and treatments between chimpanzees and humans, and the fact that chimpanzees are not useful for research on human cancer. The major molecular differences underlying these inter-species phenotypic disparities have been revealed by comparative genomics and molecular biology - there are key differences in all aspects of gene expression and protein function, from chromosome and chromatin structure to post-translational modification. The collective effects of these differences are striking, extensive and widespread, and they show that the superficial similarity between human and chimpanzee genetic sequences is of little consequence for biomedical research. The extrapolation of biomedical data from the chimpanzee to the human is therefore highly unreliable, and the use of the chimpanzee must be considered of little value, particularly given the breadth and potential of alternative methods of enquiry that are currently available to science.
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Abstract
BACKGROUND Graves' disease, caused by stimulatory thyrotropin receptor (TSHR) autoantibodies, has not been observed in animals. In contrast, Hashimoto's thyroiditis develops in chickens, rats, mice, dogs, and marmosets. Attempts to induce an immune response in mice to the luteinizing-hormone receptor suggested that autoantigen glycosylation was one parameter involved in breaking self-tolerance. Over evolution, TSHR glycosylation increased from three asparagine-linked-glycans (N-glycans) in fish to six N-glycans in humans and great apes. All other placental mammals lack one N-glycan in the shed TSHR A-subunit, the primary Graves' disease autoantigen. We hypothesized that (a) lesser TSHR A-subunit glycosylation reduces immunogenicity, accounting for the absence of Graves' disease in most placental mammals; (b) due to human-like A-subunit glycosylation, Graves' disease might arise in great apes. Here, we review and analyze the literature on this subject and report the results of a survey of veterinarians at primate centers and zoos in North America. SUMMARY Previous experimental data from induced TSHR antibodies in mice support a role for A-subunit glycosylation in breaking self-tolerance. An extensive search of the great-ape literature revealed five reports of noncongenital thyroid dysfunction, four with hypothyroidism and one with hyperthyroidism. The latter was a gorilla who was treated with anti-thyroid drugs but is now deceased. Neither serum nor thyroid tissue from this gorilla were available for analysis. The survey of veterinarians revealed that none of the 979 chimpanzees in primate research centers had a diagnosis of noncongenital thyroid dysfunction and among ∼1100 great apes (gorillas, orangutans, and chimpanzees) in U.S. zoos, only three were hypothyroid, and none were hyperthyroid. CONCLUSIONS Graves' disease appears to be either very rare or does not occur in great apes based on the literature and a survey of veterinarians. Although the available data do not advance our hypothesis, there is a paucity of information regarding thyroid function tests and thyroid autoantibodies in the great apes In addition, these primates may be protected against TSHR autoimmunity by the absence of genetic polymorphisms and putative environmental triggers. Finally, larger numbers of great apes need to be followed, and tests of thyroid function and thyroid autoantibodies be performed, to confirm that spontaneous Graves' disease is restricted to humans.
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Affiliation(s)
- Sandra M McLachlan
- Autoimmune Disease Unit, Cedars-Sinai Research Institute, UCLA School of Medicine, Los Angeles, California 90048, USA.
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Siberry GK, Leister E, Jacobson DL, Foster SB, Seage GR, Lipshultz SE, Paul ME, Purswani M, Colin AA, Scott G, Shearer WT. Increased risk of asthma and atopic dermatitis in perinatally HIV-infected children and adolescents. Clin Immunol 2011; 142:201-8. [PMID: 22094294 DOI: 10.1016/j.clim.2011.10.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 10/25/2011] [Indexed: 12/15/2022]
Abstract
The incidence of asthma and atopic dermatitis (AD) was evaluated in HIV-infected (n = 451) compared to HIV-exposed (n = 227) but uninfected (HEU) children and adolescents by abstraction from clinical charts. Asthma was more common in HIV-infected compared to HEU children by clinical diagnosis (25% vs. 20%, p = 0.101), by asthma medication use, (31% vs. 22%, p = 0.012), and by clinical diagnosis and/or medication use, (34% vs. 25%, p = 0.012). HIV-infected children had a greater risk of asthma compared to HEU children (HR = 1.37, 95% CI: 1.01 to 1.86). AD was more common in HIV-infected than HEU children (20% vs. 12%, p = 0.009)) and children with AD were more likely to have asthma in both cohorts (41% vs. 29%, p = 0.010). HIV-infected children and adolescents in this study had an increased incidence of asthma and AD, a finding critical for millions of HIV-infected children worldwide.
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Affiliation(s)
- George K Siberry
- Pediatric, Adolescent, and Maternal AIDS Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA
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Ponce RA. Safety assessment of immunomodulatory biologics: The promise and challenges of regulatory T-cell modulation. J Immunotoxicol 2011; 8:389-97. [DOI: 10.3109/1547691x.2011.603390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
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Bakacs T, Mehrishi JN, Moss RW. Ipilimumab (Yervoy) and the TGN1412 catastrophe. Immunobiology 2011; 217:583-9. [PMID: 21821307 DOI: 10.1016/j.imbio.2011.07.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2011] [Accepted: 07/03/2011] [Indexed: 12/12/2022]
Abstract
The development of the anti-CTLA-4 antibody (ipilimumab; marketed as Yervoy) immune regulatory therapy was based on the premise that "Abrogation of the function of CTLA-4 would permit CD28 to function unopposed and might swing the balance in favor of immune stimulation, tolerance breakdown and tumor eradication…" (Weber, 2009). By now, the vast majority of data collected from more than 4000 patients proves that this prediction was entirely correct. Paradoxically, the successful blockade of immune checkpoints raises the question whether an anti-CTLA-4 antibody could ever become an important therapy against cancer. T cells lost their ability to discriminate between self and non-self. Thus, tolerance to self tissues was broken in ∼70% of the patients. In the recent industry-sponsored phase III clinical trial of ipilimumab, 147 (38.7%) of the patients experienced severe adverse events and 6.8% suffered dose-limiting events (8.4%, in the ipilimumab-alone group). There were 14 deaths related to the study drugs and 7 of these were associated with immune-related adverse events. In contrast, the complete response rate was only 0.2%, in one patient out of 403 who received ipilimumab plus a peptide vaccine. Promoters of ipilimumab appear to be unmindful of the clinical trial catastrophe in London. Then, a humanized "superagonist" anti-CD28 monoclonal antibody, TGN1412, which "preferentially" activated regulatory T cells, at a higher dose, also activated all CD28 positive T cells. This precipitated a "cytokine storm" leading to life-threatening multiple organ failure in the six healthy human volunteers. Neither anti-CD28 nor anti-CTLA-4 therapies rely on antigen-specificity. Both release free antibody into the body against common molecular targets that are expressed on the targeted as well as on the non-targeted T cells. At lower antibody doses specific T cells are preferentially activated. With increasing antibody dose, however, the kinetics of the interaction is pushed in favor of widespread non-specific T cell expansion. Using the law of mass action we calculated that the vast majority of the CTLA-4 receptors on all activated T cells (including melanoma specific T cells) in the phase III clinical trial of ipilimumab will have been saturated. This would explain the runaway immune response observed. The conclusions drawn by the authors of the ipilimumab trial paper could bear an independent inspection and reassessment concerning the validation of the blockade of immune checkpoints as an important therapeutic strategy against cancer.
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Affiliation(s)
- Tibor Bakacs
- Department of Probability, Alfred Renyi Institute of Mathematics, Hungarian Academy of Sciences, Realtanoda utca 13-15, H-1053 Budapest, Hungary.
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Moser AB, Steinberg SJ, Watkins PA, Moser HW, Ramaswamy K, Siegmund KD, Lee DR, Ely JJ, Ryder OA, Hacia JG. Human and great ape red blood cells differ in plasmalogen levels and composition. Lipids Health Dis 2011; 10:101. [PMID: 21679470 PMCID: PMC3129581 DOI: 10.1186/1476-511x-10-101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2011] [Accepted: 06/17/2011] [Indexed: 02/06/2023] Open
Abstract
Background Plasmalogens are ether phospholipids required for normal mammalian developmental, physiological, and cognitive functions. They have been proposed to act as membrane antioxidants and reservoirs of polyunsaturated fatty acids as well as influence intracellular signaling and membrane dynamics. Plasmalogens are particularly enriched in cells and tissues of the human nervous, immune, and cardiovascular systems. Humans with severely reduced plasmalogen levels have reduced life spans, abnormal neurological development, skeletal dysplasia, impaired respiration, and cataracts. Plasmalogen deficiency is also found in the brain tissue of individuals with Alzheimer disease. Results In a human and great ape cohort, we measured the red blood cell (RBC) levels of the most abundant types of plasmalogens. Total RBC plasmalogen levels were lower in humans than bonobos, chimpanzees, and gorillas, but higher than orangutans. There were especially pronounced cross-species differences in the levels of plasmalogens with a C16:0 moiety at the sn-1 position. Humans on Western or vegan diets had comparable total RBC plasmalogen levels, but the latter group showed moderately higher levels of plasmalogens with a C18:1 moiety at the sn-1 position. We did not find robust sex-specific differences in human or chimpanzee RBC plasmalogen levels or composition. Furthermore, human and great ape skin fibroblasts showed only modest differences in peroxisomal plasmalogen biosynthetic activity. Human and chimpanzee microarray data indicated that genes involved in plasmalogen biosynthesis show cross-species differential expression in multiple tissues. Conclusion We propose that the observed differences in human and great ape RBC plasmalogens are primarily caused by their rates of biosynthesis and/or turnover. Gene expression data raise the possibility that other human and great ape cells and tissues differ in plasmalogen levels. Based on the phenotypes of humans and rodents with plasmalogen disorders, we propose that cross-species differences in tissue plasmalogen levels could influence organ functions and processes ranging from cognition to reproduction to aging.
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Affiliation(s)
- Ann B Moser
- Hugo W. Moser Research Institute at Kennedy Krieger, and Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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Varki NM, Strobert E, Dick EJ, Benirschke K, Varki A. Biomedical differences between human and nonhuman hominids: potential roles for uniquely human aspects of sialic acid biology. ANNUAL REVIEW OF PATHOLOGY-MECHANISMS OF DISEASE 2011; 6:365-93. [PMID: 21073341 DOI: 10.1146/annurev-pathol-011110-130315] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Although humans are genetically very similar to the evolutionarily related nonhuman hominids (chimpanzees, bonobos, gorillas, and orangutans), comparative studies suggest a surprising number of uniquely human differences in the incidence and/or severity of biomedical conditions. Some differences are due to anatomical changes that occurred during human evolution. However, many cannot be explained either by these changes or by known environmental factors. Because chimpanzees were long considered models for human disease, it is important to be aware of these differences, which appear to have been deemphasized relative to similarities. We focus on the pathophysiology and pathobiology of biomedical conditions that appear unique to humans, including several speculative possibilities that require further study. We pay particular attention to the possible contributions of uniquely human changes in the biology of cell-surface sialic acids and the proteins that recognize them. We also discuss the metabolic incorporation of a diet-derived nonhuman sialic acid, which generates a novel xeno-autoantigen reaction, and chronic inflammation known as xenosialitis.
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Affiliation(s)
- Nissi M Varki
- Glycobiology Research and Training Center, University of California at San Diego, La Jolla, 92093-0687, USA.
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Poirier N, Blancho G, Vanhove B. A more selective costimulatory blockade of the CD28-B7 pathway. Transpl Int 2010; 24:2-11. [DOI: 10.1111/j.1432-2277.2010.01176.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Taylor RE, Gregg CJ, Padler-Karavani V, Ghaderi D, Yu H, Huang S, Sorensen RU, Chen X, Inostroza J, Nizet V, Varki A. Novel mechanism for the generation of human xeno-autoantibodies against the nonhuman sialic acid N-glycolylneuraminic acid. ACTA ACUST UNITED AC 2010; 207:1637-46. [PMID: 20624889 PMCID: PMC2916132 DOI: 10.1084/jem.20100575] [Citation(s) in RCA: 117] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The nonhuman sialic acid N-glycolylneuraminic acid (Neu5Gc) is metabolically incorporated into human tissues from certain mammalian-derived foods, and this occurs in the face of an anti-Neu5Gc “xeno-autoantibody” response. Given evidence that this process contributes to chronic inflammation in some diseases, it is important to understand when and how these antibodies are generated in humans. We show here that human anti-Neu5Gc antibodies appear during infancy and correlate with weaning and exposure to dietary Neu5Gc. However, dietary Neu5Gc alone cannot elicit anti-Neu5Gc antibodies in mice with a humanlike Neu5Gc deficiency. Other postnatally appearing anti-carbohydrate antibodies are likely induced by bacteria expressing these epitopes; however, no microbe is known to synthesize Neu5Gc. Here, we show that trace exogenous Neu5Gc can be incorporated into cell surface lipooligosaccharides (LOS) of nontypeable Haemophilus influenzae (NTHi), a human-specific commensal/pathogen. Indeed, infant anti-Neu5Gc antibodies appear coincident with antibodies against NTHi. Furthermore, NTHi that express Neu5Gc-containing LOS induce anti-Neu5Gc antibodies in Neu5Gc-deficient mice, without added adjuvant. Finally, Neu5Gc from baby food is taken up and expressed by NTHi. As the flora residing in the nasopharynx of infants can be in contact with ingested food, we propose a novel model for how NTHi and dietary Neu5Gc cooperate to generate anti-Neu5Gc antibodies in humans.
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Affiliation(s)
- Rachel E Taylor
- Department of Medicine, Skaggs School of Pharmacy and PharmaceuticalSciences, University of California, San Diego, La Jolla, CA 92093, USA
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Colloquium paper: uniquely human evolution of sialic acid genetics and biology. Proc Natl Acad Sci U S A 2010; 107 Suppl 2:8939-46. [PMID: 20445087 DOI: 10.1073/pnas.0914634107] [Citation(s) in RCA: 193] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Darwinian evolution of humans from our common ancestors with nonhuman primates involved many gene-environment interactions at the population level, and the resulting human-specific genetic changes must contribute to the "Human Condition." Recent data indicate that the biology of sialic acids (which directly involves less than 60 genes) shows more than 10 uniquely human genetic changes in comparison with our closest evolutionary relatives. Known outcomes are tissue-specific changes in abundant cell-surface glycans, changes in specificity and/or expression of multiple proteins that recognize these glycans, and novel pathogen regimes. Specific events include Alu-mediated inactivation of the CMAH gene, resulting in loss of synthesis of the Sia N-glycolylneuraminic acid (Neu5Gc) and increase in expression of the precursor N-acetylneuraminic acid (Neu5Ac); increased expression of alpha2-6-linked Sias (likely because of changed expression of ST6GALI); and multiple changes in SIGLEC genes encoding Sia-recognizing Ig-like lectins (Siglecs). The last includes binding specificity changes (in Siglecs -5, -7, -9, -11, and -12); expression pattern changes (in Siglecs -1, -5, -6, and -11); gene conversion (SIGLEC11); and deletion or pseudogenization (SIGLEC13, SIGLEC14, and SIGLEC16). A nongenetic outcome of the CMAH mutation is human metabolic incorporation of foreign dietary Neu5Gc, in the face of circulating anti-Neu5Gc antibodies, generating a novel "xeno-auto-antigen" situation. Taken together, these data suggest that both the genes associated with Sia biology and the related impacts of the environment comprise a relative "hot spot" of genetic and physiological changes in human evolution, with implications for uniquely human features both in health and disease.
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