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Lawrence R, Munn K, Naser H, Thomas L, Haboubi H, Williams L, Doak S, Jenkins G. The PIG-A gene mutation assay in human biomonitoring and disease. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2023; 64:480-493. [PMID: 37926486 DOI: 10.1002/em.22577] [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: 08/25/2023] [Revised: 10/11/2023] [Accepted: 11/01/2023] [Indexed: 11/07/2023]
Abstract
The blood cell phosphatidylinositol glycan class A (PIG-A) gene mutation assay has been extensively researched in rodents for in vivo mutagenicity testing and is now being investigated in humans. The PIG-A gene is involved in glycosyl phosphatidylinositol (GPI)-anchor biosynthesis. A single mutation in this X-linked gene can lead to loss of membrane-bound GPI anchors, which can be enumerated via corresponding GPI-anchored proteins (e.g., CD55) using flow cytometry. The studies published to date by different research groups demonstrate a remarkable consistency in PIG-A mutant frequencies. Moreover, with the low background level of mutant erythrocytes in healthy subjects (2.9-5.56 × 10-6 mutants), induction of mutation post genotoxic exposure can be detected. Cigarette smoking, radiotherapy, and occupational exposures, including lead, have been shown to increase mutant levels. Future applications of this test include identifying new harmful agents and establishing new exposure limits. This mutational monitoring approach may also identify individuals at higher risk of cancer development. In addition, identifying protective agents that could mitigate these effects may reduce baseline somatic mutation levels and such behaviors can be encouraged. Further technological progress is required including establishing underlying mechanisms of GPI anchor loss, protocol standardization, and the development of cryopreservation methods to improve GPI-anchor stability over time. If successful, this assay has the potential be widely employed, for example, in rural and low-income countries. Here, we review the current literature on PIG-A mutation in humans and discuss the potential role of this assay in human biomonitoring and disease detection.
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Affiliation(s)
- Rachel Lawrence
- Centre for Biomarkers and Biotherapeutics, Barts Cancer Institute, Queen Mary University of London, London, UK
| | - Kathryn Munn
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Hamsa Naser
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Laura Thomas
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Hasan Haboubi
- Department of Gastroenterology, University Hospital Llandough, Cardiff and Vale University Health Board, Cardiff, UK
| | - Lisa Williams
- Department of Gastroenterology, Singleton Hospital, Swansea Bay University Health Board, Swansea, UK
| | - Shareen Doak
- Swansea University Medical School, Swansea University, Swansea, UK
| | - Gareth Jenkins
- Swansea University Medical School, Swansea University, Swansea, UK
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The spectrum of paroxysmal nocturnal hemoglobinuria clinical presentation in a Brazilian single referral center. Ann Hematol 2022; 101:999-1007. [PMID: 35182190 PMCID: PMC8993788 DOI: 10.1007/s00277-022-04797-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 02/13/2022] [Indexed: 11/23/2022]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematological disorder caused by the expansion of a hematopoietic clone harboring a somatic genetic variant in the PIG-A gene translating into a wide spectrum of clinical and laboratory changes, from intravascular hemolysis, thrombosis, and bone marrow failure to subclinical presentation. In this study, we retrospectively analyzed 87 consecutive cases (39 women; median follow-up, 18 months; range, 0–151 months) in whom a PNH clone was detected by flow cytometry between 2006 and 2019 seen at a single Brazilian referral center. The median age at diagnosis was 29 years (range, 8 to 83 years); 29 patients (33%) were initially classified as PNH/bone marrow failure, 13 (15%) as classic PNH, and 45 (52%) as subclinical PNH. The median overall survival (OS) of the entire cohort was not reached during follow-up, without significant differences between groups. At diagnosis, the median PNH clone size was 2.8% (range, 0 to 65%) in erythrocytes and 5.4% (range, 0 to 80%) in neutrophils. Fourteen patients experienced clone expansion during follow-up; in other 14 patients the clone disappeared, and in 18 patients it remained stable throughout the follow-up. A subclinical PNH clone was detected in three telomeropathy patients at diagnosis, but it was persistent and confirmed by DNA sequencing in only one case. In conclusion, PNH presentation was variable, and most patients had subclinical disease or associated with marrow failure and did not require specific anticomplement therapy. Clone size was stable or even disappeared in most cases.
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Waters MD, Warren S, Hughes C, Lewis P, Zhang F. Human genetic risk of treatment with antiviral nucleoside analog drugs that induce lethal mutagenesis: The special case of molnupiravir. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2022; 63:37-63. [PMID: 35023215 DOI: 10.1002/em.22471] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2021] [Revised: 12/28/2021] [Accepted: 01/08/2022] [Indexed: 06/14/2023]
Abstract
This review considers antiviral nucleoside analog drugs, including ribavirin, favipiravir, and molnupiravir, which induce genome error catastrophe in SARS-CoV or SARS-CoV-2 via lethal mutagenesis as a mode of action. In vitro data indicate that molnupiravir may be 100 times more potent as an antiviral agent than ribavirin or favipiravir. Molnupiravir has recently demonstrated efficacy in a phase 3 clinical trial. Because of its anticipated global use, its relative potency, and the reported in vitro "host" cell mutagenicity of its active principle, β-d-N4-hydroxycytidine, we have reviewed the development of molnupiravir and its genotoxicity safety evaluation, as well as the genotoxicity profiles of three congeners, that is, ribavirin, favipiravir, and 5-(2-chloroethyl)-2'-deoxyuridine. We consider the potential genetic risks of molnupiravir on the basis of all available information and focus on the need for additional human genotoxicity data and follow-up in patients treated with molnupiravir and similar drugs. Such human data are especially relevant for antiviral NAs that have the potential of permanently modifying the genomes of treated patients and/or causing human teratogenicity or embryotoxicity. We conclude that the results of preclinical genotoxicity studies and phase 1 human clinical safety, tolerability, and pharmacokinetics are critical components of drug safety assessments and sentinels of unanticipated adverse health effects. We provide our rationale for performing more thorough genotoxicity testing prior to and within phase 1 clinical trials, including human PIG-A and error corrected next generation sequencing (duplex sequencing) studies in DNA and mitochondrial DNA of patients treated with antiviral NAs that induce genome error catastrophe via lethal mutagenesis.
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Affiliation(s)
- Michael D Waters
- Michael Waters Consulting USA, Hillsborough, North Carolina, USA
| | | | - Claude Hughes
- Duke University Medical Center, Durham, North Carolina, USA
| | | | - Fengyu Zhang
- Global Clinical and Translational Research Institute, Bethesda, Maryland, USA
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Molecular characterization of hypoxanthine guanine phosphoribosyltransferase mutant T cells in human blood: The concept of surrogate selection for immunologically relevant cells. MUTATION RESEARCH. REVIEWS IN MUTATION RESEARCH 2022; 789:108414. [PMID: 35690417 PMCID: PMC9188651 DOI: 10.1016/j.mrrev.2022.108414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 03/01/2022] [Accepted: 03/08/2022] [Indexed: 11/23/2022]
Abstract
Somatic cell gene mutations arise in vivo due to replication errors during DNA synthesis occurring spontaneously during normal DNA synthesis or as a result of replication on a DNA template damaged by endogenous or exogenous mutagens. In principle, changes in the frequencies of mutant cells in vivo in humans reflect changes in exposures to exogenous or endogenous DNA damaging insults, other factors being equal. It is becoming increasingly evident however, that somatic mutations in humans have a far greater range of interpretations. For example, mutations in lymphocytes provide invaluable probes for in vivo cellular and molecular processes, providing identification of clonal amplifications of these cells in autoimmune and infectious diseases, transplantation recipients, paroxysmal nocturnal hemoglobinuria (PNH), and cancer. The assay for mutations of the X-chromosomal hypoxanthine guanine phosphoribosyltransferase (HPRT) gene has gained popular acceptance for this purpose since viable mutant cells can be recovered for molecular and other analyses. Although the major application of the HPRT T cell assay remains human population monitoring, the enrichment of activated T cells in the mutant fraction in individuals with ongoing immunological processes has demonstrated the utility of surrogate selection, a method that uses somatic mutation as a surrogate marker for the in vivo T cell proliferation that underlies immunological processes to investigate clinical disorders with immunological features. Studies encompassing a wide range of clinical conditions are reviewed. Despite the historical importance of the HPRT mutation system in validating surrogate selection, there are now additional mutational and other methods for identifying immunologically active T cells. These methods are reviewed and provide insights for strategies to extend surrogate selection in future studies.
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Albertini RJ, Kaden DA. Mutagenicity monitoring in humans: Global versus specific origin of mutations. MUTATION RESEARCH-REVIEWS IN MUTATION RESEARCH 2020; 786:108341. [PMID: 33339577 DOI: 10.1016/j.mrrev.2020.108341] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Revised: 10/08/2020] [Accepted: 10/14/2020] [Indexed: 01/19/2023]
Abstract
An underappreciated aspect of human mutagenicity biomonitoring is tissue specificity reflected in different assays, especially those that measure events that can only occur in developing bone marrow (BM) cells. Reviewed here are 9 currently-employed human mutagenicity biomonitoring assays. Several assays measure chromosome-level events in circulating T-lymphocytes (T-cells), i.e., traditional analyses of aberrations, translocation studies involving chromosome painting and fluorescence in situ hybridization (FISH) and determinations of micronuclei (MN). Other T-cell assays measure gene mutations. i.e., hypoxanthine-guanine phosphoriboslytransferase (HPRT) and phosphoribosylinositol glycan class A (PIGA). In addition to the T-cell assays, also reviewed are those assays that measure events in peripheral blood cells that necessarily arose in BM cells, i.e., MN in reticulocytes; glycophorin A (GPA) gene mutations in red blood cells (RBCs), and PIGA gene mutations in RBC or granulocytes. This review considers only cell culture- or cytometry-based assays to describe endpoints measured, methods, optimal sampling times, and sample summaries of typical quantitative and qualitative results. However, to achieve its intended focus on the target cells where events occur, kinetics of the cells of peripheral blood that derive at some point from precursor cells are reviewed to identify body sites and tissues where the genotoxic events originate. Kinetics indicate that in normal adults, measured events in T-cells afford global assessments of in vivo mutagenicity but are not specific for BM effects. Therefore, an agent's capacity for inducing mutations in BM cells cannot be reliably inferred from T-cell assays as the magnitude of effect in BM, if any, is unknown. By contrast, chromosome or gene level mutations measured in RBCs/reticulocytes or granulocytes must originate in BM cells, i.e. in RBC or granulocyte precursors, thereby making them specific indicators for effects in BM. Assays of mutations arising directly in BM cells may quantitatively reflect the mutagenicity of potential leukemogenic agents.
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Affiliation(s)
- Richard J Albertini
- University of Vermont, 111 Colchester Avenue, Burlington, VT 05401, United States
| | - Debra A Kaden
- Ramboll US Consulting, Inc., 101 Federal Street, Suite 1900, Boston, MA 02110, United States.
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Cao Y, Wang T, Xi J, Zhang G, Wang T, Liu W, You X, Zhang X, Xia Z, Luan Y. PIG-A gene mutation as a genotoxicity biomarker in human population studies: An investigation in lead-exposed workers. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:611-621. [PMID: 32285465 DOI: 10.1002/em.22373] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2019] [Revised: 03/23/2020] [Accepted: 04/03/2020] [Indexed: 05/21/2023]
Abstract
The rodent Pig-a gene mutation assay has demonstrated remarkable sensitivity in identifying in vivo mutagens, while much less is known about the value of the human PIG-A assay for risk assessment. To obtain more evidence of its potential as a predictive biomarker for carcinogen exposure, we investigated PIG-A mutant frequencies (MFs), along with performing the Comet assay and micronucleus (MN) test, in 267 workers occupationally exposed to lead. Multivariate Poisson regression showed that total red blood cell PIG-A MFs were significantly higher in lead-exposed workers (10.90 ± 10.7 × 10-6 ) than in a general population that we studied previously (5.25 ± 3.6 × 10-6 ) (p < .0001). In contrast, there was no increase in lymphocyte MN frequency or in DNA damage as measured by percentage comet tail intensity in whole blood cells. Current year worker blood lead levels (BLL), an exposure biomarker, were elevated (232.6 ± 104.6 μg/L, median: 225.4 μg/L); a cumulative blood lead index (CBLI) also was calculated based on a combination of current and historical worker BLL data. Chi-square testing indicated that PIG-A MFs were significantly related to CBLI (p = .0249), but independent of current year BLL (p = .4276). However, % comet tail intensity and MN frequencies were better associated with current year BLL than CBLI. This study indicates that the PIG-A assay could serve as biomarker to detect the genotoxic effects of lead exposure and demonstrates that a battery of genotoxicity biomarkers having mechanistic complementarity may be useful for comprehensively monitoring human carcinogenic risk.
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Affiliation(s)
- Yiyi Cao
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Tuanwei Wang
- Department of Occupational Health & Toxicology, School of Public Health, Shanghai Medical College of Fudan University, Shanghai, China
| | - Jing Xi
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Guanghui Zhang
- Department of Occupational & Environmental Health, School of Public Health, Xinxiang Medical University, Xinxiang, Henan Province, China
| | - Tongshuai Wang
- Department of Occupational Health & Toxicology, School of Public Health, Shanghai Medical College of Fudan University, Shanghai, China
| | - Weiying Liu
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xinyue You
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - XinYu Zhang
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zhaolin Xia
- Department of Occupational Health & Toxicology, School of Public Health, Shanghai Medical College of Fudan University, Shanghai, China
| | - Yang Luan
- School of Public Health, Hongqiao International Institute of Medicine, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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CRISPR/Cas9 PIG -A gene editing in nonhuman primate model demonstrates no intrinsic clonal expansion of PNH HSPCs. Blood 2019; 133:2542-2545. [PMID: 31003997 DOI: 10.1182/blood.2019000800] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Sreedharanunni S, Varma N, Sachdeva MUS, Naseem S, Malhotra P, Bansal D, Sood A, Bose P, Varma S. Paroxysmal nocturnal hemoglobinuria clones are not infrequent in patients with inherited bone marrow failure syndromes. Eur J Haematol 2018; 99:194-195. [PMID: 28452421 DOI: 10.1111/ejh.12898] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Sreejesh Sreedharanunni
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Neelam Varma
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Man Updesh Singh Sachdeva
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Shano Naseem
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Pankaj Malhotra
- Internal Medicine (Clinical hematology), Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Deepak Bansal
- Advance Pediatric centre (Hematology/oncology unit), Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Anil Sood
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Parveen Bose
- Department of Hematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Subhash Varma
- Internal Medicine (Clinical hematology), Postgraduate Institute of Medical Education and Research, Chandigarh, India
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9
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Loeff FC, Falkenburg JHF, Hageman L, Huisman W, Veld SAJ, van Egmond HME, van de Meent M, von dem Borne PA, Veelken H, Halkes CJM, Jedema I. High Mutation Frequency of thePIGAGene in T Cells Results in Reconstitution of GPI Anchor−/CD52−T Cells That Can Give Early Immune Protection after Alemtuzumab-Based T Cell–Depleted Allogeneic Stem Cell Transplantation. THE JOURNAL OF IMMUNOLOGY 2018; 200:2199-2208. [DOI: 10.4049/jimmunol.1701018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 01/09/2018] [Indexed: 12/30/2022]
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Lazo-Langner A, Kovacs MJ, Hedley B, Al-Ani F, Keeney M, Louzada ML, Chin-Yee I. Screening of patients with idiopathic venous thromboembolism for paroxysmal nocturnal hemoglobinuria clones. Thromb Res 2015; 135:1107-9. [PMID: 25890452 DOI: 10.1016/j.thromres.2015.04.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/01/2015] [Accepted: 04/06/2015] [Indexed: 01/06/2023]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon disorder characterized by hemolysis, thrombosis and marrow failure. Whereas venous and arterial thrombosis is a very common symptom of the disease, the frequency of PNH clones in patients with unexplained venous thromboembolism, including deep vein thrombosis and pulmonary embolism, has not been studied. We conducted a cross sectional study evaluating the presence of PNH clones in patients with prevalent venous thromboembolism using a high sensitivity flow cytometry assay for erythrocytes and neutrophils. Among the 388 patients enrolled in the study one patient had a detectable PNH clone of 0.02% in the neutrophil population (0.26%; 95% CI 0.05 to 1.45) and no detectable erythrocyte clone. We conclude that the presence of PNH clones in patients with idiopathic venous thrombosis is rare. Screening for PNH clones among VTE patients might be better reserved for patients with signs of hemolysis.
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Affiliation(s)
- Alejandro Lazo-Langner
- Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada; Department of Epidemiology and Biostatistics, University of Western Ontario, London, Ontario, Canada.
| | - Michael J Kovacs
- Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada
| | - Ben Hedley
- Pathology and Laboratory Medicine, London Health Sciences Centre, London Ontario, Canada
| | - Fatimah Al-Ani
- Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada
| | - Michael Keeney
- Pathology and Laboratory Medicine, London Health Sciences Centre, London Ontario, Canada
| | - Martha L Louzada
- Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada; Department of Epidemiology and Biostatistics, University of Western Ontario, London, Ontario, Canada
| | - Ian Chin-Yee
- Department of Medicine, Division of Hematology, University of Western Ontario, London, Ontario, Canada
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Halkes CJ, Zoutman WH, van der Fits L, Jedema I, Vermeer MH. Mutation in PIGA Results in a CD52-Negative Escape Variant in a Sézary Syndrome Patient during Alemtuzumab Treatment. J Invest Dermatol 2015; 135:1199-1202. [DOI: 10.1038/jid.2014.501] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Liew M, Farley M, Andreasen J, Parker CJ, Wittwer CT. Rare event counting of CD59− red cells in human blood: A 47-month experience using PNH consensus guidelines for WBC and RBC testing in a reference lab. CYTOMETRY PART B-CLINICAL CYTOMETRY 2015; 88:261-9. [DOI: 10.1002/cyto.b.21225] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 01/07/2015] [Accepted: 01/15/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Michael Liew
- Institute for Clinical and Experimental Pathology, ARUP Laboratories; Salt Lake City Utah 84108
| | - Marjorie Farley
- Institute for Clinical and Experimental Pathology, ARUP Laboratories; Salt Lake City Utah 84108
| | - John Andreasen
- Institute for Clinical and Experimental Pathology, ARUP Laboratories; Salt Lake City Utah 84108
| | - Charles J. Parker
- Division of Hematology; Department of Internal Medicine; University of Utah School of Medicine; Salt Lake City Utah 84132
| | - Carl T. Wittwer
- Institute for Clinical and Experimental Pathology, ARUP Laboratories; Salt Lake City Utah 84108
- Department of Pathology; University of Utah School of Medicine; Salt Lake City Utah 84132
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Abstract
The type II secretion system is utilized by many Gram-negative bacteria to export folded proteins to the surface and/or the extracellular environment of the cell. Although the function of the system is to move proteins from the periplasm to the outside of the cell, it is a large trans-envelope structure composed of more than a dozen different proteins present in multiple copies, including peripheral, integral inner membrane and integral outer membrane proteins plus a pseudopilus stretching between them. The establishment of this structure as an integral component of the entire envelope including the peptidoglycan layer between the two membranes requires assembly. Many of the participants and processes involved in this assembly have now been established, while other aspects remain to be discovered or more fully understood.
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Affiliation(s)
- S Peter Howard
- Department of Microbiology and Immunology, University of Saskatchewan, Health Sciences Building, Room 2D01, 107 Wiggins Road, Saskatoon, Saskatchewan, Canada S7N 5E5.
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Araten DJ, Sanders KJ, Anscher D, Zamechek L, Hunger SP, Ibrahim S. Leukemic blasts with the paroxysmal nocturnal hemoglobinuria phenotype in children with acute lymphoblastic leukemia. THE AMERICAN JOURNAL OF PATHOLOGY 2012; 181:1862-9. [PMID: 22940070 DOI: 10.1016/j.ajpath.2012.07.025] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2012] [Revised: 06/21/2012] [Accepted: 07/05/2012] [Indexed: 01/12/2023]
Abstract
It has been proposed that genomic instability is essential to account for the multiplicity of mutations often seen in malignancies. Using the X-linked PIG-A gene as a sentinel gene for spontaneous inactivating somatic mutations, we previously showed that healthy individuals harbor granulocytes with the PIG-A mutant (paroxysmal nocturnal hemoglobinuria) phenotype at a median frequency (f) of ∼12 × 10(-6). Herein, we used a similar approach to determine f in blast cells derived from 19 individuals with acute lymphoblastic leukemia (ALL) and in immortalized Epstein-Barr virus-transformed B-cell cultures (human B-lymphoblastoid cell lines) from 19 healthy donors. The B-lymphoblastoid cell lines exhibited a unimodal distribution, with a median f value of 11 × 10(-6). In contrast, analysis of the f values for the ALL samples revealed at least two distinct populations: one population, representing approximately half of the samples (n = 10), had a median f value of 13 × 10(-6), and the remaining samples (n = 9) had a median f value of 566 × 10(-6). We conclude that in ALL, there are two distinct phenotypes with respect to hypermutability, which we hypothesize will correlate with the number of pathogenic mutations required to produce the leukemia.
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Affiliation(s)
- David J Araten
- Division of Hematology, New York University School of Medicine, New York University Langone Clinical Cancer Center, New York, USA.
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Dobrovolsky VN, Elespuru RK, Bigger CAH, Robison TW, Heflich RH. Monitoring humans for somatic mutation in the endogenous PIG-a gene using red blood cells. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2011; 52:784-794. [PMID: 21826740 DOI: 10.1002/em.20667] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2011] [Revised: 06/03/2011] [Accepted: 06/08/2011] [Indexed: 05/31/2023]
Abstract
The endogenous X-linked PIG-A gene is involved in the synthesis of glycosyl phosphatidyl inositol (GPI) anchors that tether specific protein markers to the exterior of mammalian cell cytoplasmic membranes. Earlier studies in rodent models indicate that Pig-a mutant red blood cells (RBCs) can be induced in animals treated with genotoxic agents, and that flow cytometry can be used to identify rare RBCs deficient in the GPI-anchored protein, CD59, as a marker of Pig-a gene mutation. We investigated if a similar approach could be used for detecting gene mutation in humans. We first determined the frequency of spontaneous CD59-deficient RBCs (presumed PIG-A mutants) in 97 self-identified healthy volunteers. For most subjects, the frequency of CD59-deficient RBCs was low (average of 5.1 ± 4.9 × 10(-6) ; median of 3.8 × 10(-6) and mutant frequency less than 8 × 10(-6) for 75% of subjects), with a statistically significant difference in median mutant frequencies between males and females. PIG-A RBC mutant frequency displayed poor correlation with the age and no correlation with the smoking status of the subjects. Also, two individuals had markedly increased CD59-deficient RBC frequencies of ∼300 × 10(-6) and ∼100 × 10(-6) . We then monitored PIG-A mutation in 10 newly diagnosed cancer patients undergoing chemotherapy with known genotoxic drugs. The frequency of CD59-deficient RBCs in the blood of the patients was measured before the start of chemotherapy and three times over a period of ∼6 months while on/after chemotherapy. Responses were generally weak, most observations being less than the median mutant frequency for both males and females; the greatest response was an approximate three-fold increase in the frequency of CD59-deficient RBCs in one patient treated with a combination of cisplatin and etoposide. These results suggest that the RBC PIG-A assay can be adopted to measuring somatic cell mutation in humans. Further research is necessary to determine the assay's sensitivity in detecting mutations induced by genotoxic agents acting via different mechanisms.
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Affiliation(s)
- Vasily N Dobrovolsky
- Division of Genetic and Molecular Toxicology, National Center for Toxicological Research, US FDA, Jefferson, Arkansas, USA.
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Borowitz MJ, Craig FE, Digiuseppe JA, Illingworth AJ, Rosse W, Sutherland DR, Wittwer CT, Richards SJ. Guidelines for the diagnosis and monitoring of paroxysmal nocturnal hemoglobinuria and related disorders by flow cytometry. CYTOMETRY PART B-CLINICAL CYTOMETRY 2010; 78:211-30. [PMID: 20533382 DOI: 10.1002/cyto.b.20525] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Paroxysmal nocturnal hemoglobinuria (PNH) is a rare hematopoietic stem cell disorder characterized by a somatic mutation in the PIGA gene, leading to a deficiency of proteins linked to the cell membrane via glycophosphatidylinositol (GPI) anchors. While flow cytometry is the method of choice for identifying cells deficient in GPI-linked proteins and is, therefore, necessary for the diagnosis of PNH, to date there has not been an attempt to standardize the methodology used to identify these cells. METHODS In this document, we present a consensus effort that describes flow cytometric procedures for detecting PNH cells. RESULTS We discuss clinical indications and offer recommendations on data interpretation and reporting but mostly focus on analytical procedures important for analysis. We distinguish between routine analysis (defined as identifying an abnormal population of 1% or more) and high-sensitivity analysis (in which as few as 0.01% PNH cells are detected). Antibody panels and gating strategies necessary for both procedures are presented in detail. We discuss methods for assessing PNH populations in both white blood cells and red blood cells and the relative advantages of measuring each. We present steps needed to validate the more elaborate high-sensitivity techniques, including the need for careful titration of reagents and determination of background rates in normal populations, and discuss technical pitfalls that might affect interpretation. CONCLUSIONS This document should both enable laboratories interested in beginning PNH testing to establish a valid procedure and allow experienced laboratories to improve their techniques.
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Affiliation(s)
- Michael J Borowitz
- Department of Pathology and Oncology, Johns Hopkins Medical Institutions, Baltimore, Maryland 21231, USA.
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Rachidi S, Musallam KM, Taher AT. A closer look at paroxysmal nocturnal hemoglobinuria. Eur J Intern Med 2010; 21:260-7. [PMID: 20603032 DOI: 10.1016/j.ejim.2010.04.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/01/2010] [Accepted: 04/05/2010] [Indexed: 12/28/2022]
Abstract
Knowledge of the molecular mechanisms leading to the paroxysmal nocturnal hemoglobinuria (PNH) phenotypes has substantially increased in the past two decades. The associated intravascular hemolysis, hypercoagulablilty, and bone marrow failure result in a wide range of clinical sequlae. Although treatment has usually been symptomatic through several modalities and rarely curative through hematopoietic cell transplantation, recent development of the novel targeted therapeutic agent eculizumab has offered new promises for this highly morbid and fatal disease. This review summarizes current knowledge of the pathophysiology, diagnostic modalities, clinical implications, and treatment approaches of patients with PNH.
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MESH Headings
- Anemia, Hemolytic/etiology
- Anemia, Hemolytic/physiopathology
- Antibodies, Monoclonal/therapeutic use
- Antibodies, Monoclonal, Humanized
- Blood Coagulation/physiology
- Blood Coagulation Disorders/etiology
- Blood Coagulation Disorders/physiopathology
- Hemoglobinuria, Paroxysmal/complications
- Hemoglobinuria, Paroxysmal/diagnosis
- Hemoglobinuria, Paroxysmal/genetics
- Hemoglobinuria, Paroxysmal/physiopathology
- Hemoglobinuria, Paroxysmal/therapy
- Hemolysis/physiology
- Humans
- Kidney Diseases/etiology
- Kidney Diseases/physiopathology
- Prognosis
- Thrombosis/etiology
- Thrombosis/physiopathology
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Affiliation(s)
- Saleh Rachidi
- Department of Internal Medicine, Division of Hematology & Oncology, American University of Beirut Medical Center, Beirut, Lebanon
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Araten DJ, Martinez-Climent JA, Perle MA, Holm E, Zamechek L, DiTata K, Sanders KJ. A quantitative analysis of genomic instability in lymphoid and plasma cell neoplasms based on the PIG-A gene. Mutat Res 2010; 686:1-8. [PMID: 20060400 DOI: 10.1016/j.mrfmmm.2009.11.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Revised: 10/23/2009] [Accepted: 11/18/2009] [Indexed: 11/25/2022]
Abstract
It has been proposed that hypermutability is necessary to account for the high frequency of mutations in cancer. However, historically, the mutation rate (mu) has been difficult to measure directly, and increased cell turnover or selection could provide an alternative explanation. We recently developed an assay for mu using PIG-A as a sentinel gene and estimated that its average value is 10.6 x 10(-7) mutations per cell division in B-lymphoblastoid cell lines (BLCLs) from normal donors. Here we have measured mu in human malignancies and found that it was elevated in cell lines derived from T cell acute lymphoblastic leukemia, mantle cell lymphoma, follicular lymphoma in transformed phase, and 2 plasma cell neoplasms. In contrast, mu was much lower in a marginal zone lymphoma cell line and 5 other plasma cell neoplasms. The highest mu value that we measured, 3286 x 10(-7), is 2 orders of magnitude above the range we have observed in non-malignant human cells. We conclude that the type of genomic instability detected in this assay is a common but not universal feature of hematologic malignancies.
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Affiliation(s)
- David J Araten
- Division of Hematology, NYU School of Medicine, NYU Langone Cancer Center, NY, USA.
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Araten DJ, Sanders KJ, Pu J, Lee S. Spontaneously arising red cells with a McLeod-like phenotype in normal donors. Mutat Res 2009; 671:1-5. [PMID: 19909712 DOI: 10.1016/j.mrfmmm.2009.03.009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2008] [Revised: 03/05/2009] [Accepted: 03/24/2009] [Indexed: 11/26/2022]
Abstract
Very few human genes can be used to identify spontaneous inactivating somatic mutations. We hypothesized that because the XK gene is X-linked, it would be easy to identify spontaneously arising red cells with a phenotype resembling the McLeod syndrome, which results from inherited XK mutations. Here, by flow cytometry, we detect such phenotypic variants at a median frequency of 9 x 10(-6) in neonatal cord blood samples and 39 x 10(-6) in healthy adults (p=0.004). It may be possible to further investigate the relationship between aging, mutations, and cancer using this approach.
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Affiliation(s)
- David J Araten
- Division of Hematology, Department of Medicine, NYU School of Medicine, New York, NY, United States.
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Sugimori C, Mochizuki K, Qi Z, Sugimori N, Ishiyama K, Kondo Y, Yamazaki H, Takami A, Okumura H, Nakao S. Origin and fate of blood cells deficient in glycosylphosphatidylinositol-anchored protein among patients with bone marrow failure. Br J Haematol 2009; 147:102-12. [DOI: 10.1111/j.1365-2141.2009.07822.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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Brodsky RA. How do PIG-A mutant paroxysmal nocturnal hemoglobinuria stem cells achieve clonal dominance? Expert Rev Hematol 2009; 2:353-6. [PMID: 21082939 DOI: 10.1586/ehm.09.35] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare clonal blood disorder that manifests with hemolytic anemia, bone marrow failure, and thrombosis. Many of the clinical manifestations of the disease result from complement-mediated intravascular hemolysis. Allogeneic bone marrow transplantation is the only curative therapy for PNH. Eculizumab, a monoclonal antibody that blocks terminal complement activation, is highly effective in reducing hemolysis, improving quality of life, and reducing the risk for thrombosis in PNH patients. Insights into the relevance of detecting PNH cells in PNH and other bone marrow failure disorders are highlighted, and indications for treating PNH patients with bone marrow transplantation and eculizumab are explored.
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Affiliation(s)
- Robert A Brodsky
- Division of Hematology, Department of Medicine, Johns Hopkins University School of Medicine, 720 Rutland Avenue, Baltimore, MD 21205-2196, USA.
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Silencing of genes required for glycosylphosphatidylinositol anchor biosynthesis in Burkitt lymphoma. Exp Hematol 2009; 37:423-434.e2. [PMID: 19302917 DOI: 10.1016/j.exphem.2009.01.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2008] [Revised: 01/07/2009] [Accepted: 01/08/2009] [Indexed: 11/21/2022]
Abstract
OBJECTIVE To investigate the mechanism of glycosylphosphatidylinositol (GPI) anchor deficiency in Burkitt lymphoma cell lines. METHODS We identified a large GPI anchor protein deficient population in three different Burkitt lymphoma cell lines through proaerolysin treatment of the cells and flow cytometry analysis using a proaerolysin variant (FLAER). The mechanism of GPI anchor protein deficiency was studied by DNA gene sequencing, a cell-free assay to investigate the GPI anchor biosynthetic pathway, microarray analysis, and quantitative real-time polymerase chain reaction. RESULTS Burkitt lymphoma cell lines harbor large populations of FLAER(neg) cells, which are resistant to proaerolysin. In all three cell lines, silencing of a gene involved in an early step in GPI-anchor biosynthesis was responsible for the lack of GPI-anchored proteins on the cell surface. Quantitative polymerase chain reaction and microarray analysis demonstrate that the level of mRNA for PIGL and PIGY is lower in the FLAER(neg) Ramos cells and that mRNA levels of PIGY are reduced in the Akata and Daudi cells. Hypermethylation of these genes was associated with the low levels of mRNA and treatment of the cells with 5-aza-2' deoxycytidine restored cell surface GPI-anchored proteins to the FLAER(neg) cells. CONCLUSION GPI-anchored protein deficiency in Burkitt lymphoma cells is not due to a genetic mutation (e.g., PIGA); rather, the lack of GPI-anchored proteins results from transcriptional silencing of PIGL and PIGY.
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Dobrovolsky VN, Shaddock JG, Mittelstaedt RA, Manjanatha MG, Miura D, Uchikawa M, Mattison DR, Morris SM. Evaluation of Macaca mulatta as a model for genotoxicity studies. MUTATION RESEARCH-GENETIC TOXICOLOGY AND ENVIRONMENTAL MUTAGENESIS 2009; 673:21-8. [DOI: 10.1016/j.mrgentox.2008.11.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 11/06/2008] [Accepted: 11/10/2008] [Indexed: 10/21/2022]
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Savage WJ, Barber JP, Mukhina GL, Hu R, Chen G, Matsui W, Thoburn C, Hess AD, Cheng L, Jones RJ, Brodsky RA. Glycosylphosphatidylinositol-anchored protein deficiency confers resistance to apoptosis in PNH. Exp Hematol 2008; 37:42-51. [PMID: 19013003 DOI: 10.1016/j.exphem.2008.09.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2008] [Revised: 08/28/2008] [Accepted: 09/02/2008] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Investigate the contribution of PIG-A mutations to clonal expansion in paroxysmal nocturnal hemoglobinuria (PNH). MATERIALS AND METHODS Primary CD34+ hematopoietic progenitors from PNH patients were assayed for annexin-V positivity by flow cytometry in a cell-mediated killing assay using autologous effectors from PNH patients or allogeneic effectors from healthy controls. To specifically assess the role of the PIG-A mutation in the development of clonal dominance and address confounders of secondary mutation and differential immune attack that can confound experiments using primary cells, we established an inducible PIG-A CD34+ myeloid cell line, TF-1. Apoptosis resistance was assessed after exposure to allogeneic effectors, NK92 cells (an interleukin-2-dependent cell line with the phenotype and function of activated natural killer [NK] cells), tumor necrosis factor (TNF)-alpha, and gamma-irradiation. Apoptosis was measured by annexin-V staining and caspase 3/7 activity. RESULTS In PNH patients, CD34+ hematopoietic progenitors lacking glycosylphosphatidylinositol (GPI)-anchored proteins (GPI-AP(-)) were less susceptible than GPI-AP+ CD34+ precursors to autologous (8% vs 49%; p < 0.05) and allogeneic (28% vs 58%; p < 0.05) cell-mediated killing from the same patients. In the inducible PIG-A model, GPI-AP(-) TF-1 cells exhibited less apoptosis than induced, GPI-AP+ TF-1 cells in response to allogeneic cell-mediated killing, NK92-mediated killing, TNF-alpha, and gamma-irradiation. GPI-AP(-) TF-1 cells maintained resistance to apoptosis when effectors were raised against GPI-AP(-) cells, arguing against a GPI-AP being the target of immune attack in PNH. NK92-mediated killing was partially inhibited with blockade by specific antibodies to the stress-inducible GPI-AP ULBP1 and ULBP2 that activate immune effectors. Clonal competition experiments demonstrate that the mutant clone expands over time under proapoptotic conditions with TNF-alpha. CONCLUSION PIG-A mutations contribute to clonal expansion in PNH by conferring a survival advantage to hematopoietic progenitors under proapoptotic stresses.
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Affiliation(s)
- William J Savage
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-2196, USA
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Miura D, Dobrovolsky VN, Kasahara Y, Katsuura Y, Heflich RH. Development of an in vivo gene mutation assay using the endogenous Pig-A gene: I. Flow cytometric detection of CD59-negative peripheral red blood cells and CD48-negative spleen T-cells from the rat. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:614-621. [PMID: 18626999 DOI: 10.1002/em.20414] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
The product of the phosphatidylinositol glycan complementation group A gene (Pig-A) is involved in the synthesis of glycosylphosphatidylinositol (GPI) anchors that link various protein markers to the surface of several types of mammalian cells, including hematopoietic cells. Previous observations indicate that Pig-A mutation results in the lack of GPI synthesis and the absence of GPI-anchored proteins on the cell surface. As a first step in designing a rapid assay for measuring Pig-A mutation in the rat, we developed flow cytometry (FCM) strategies for detecting GPI-negative cells in rat peripheral blood and spleen. Anti-CD59 was used to detect GPI-anchored proteins on red blood cells (RBCs), and anti-CD48 was used to detect GPI-anchored proteins on spleen T-cells. The spontaneous frequency of CD59-negative RBCs in five male F344 rats ranged from 1 x 10(-6) to 27 x 10(-6). In contrast, treatment of five rats with three doses of 40 mg/kg N-ethyl-N-nitrosourea (ENU) increased the frequency of CD59-negative RBCs to 183 x 10(-6) to 249 x 10(-6) at 2 weeks and to 329 x 10(-6) to 413 x 10(-6) at 4 weeks after dosing. In the same 4-week posttreatment rats, the frequency of CD48-negative T-cells was 11 x 10(-6) to 16 x 10(-6) in control rats and 194 x 10(-6) to 473 x 10(-6) in ENU-treated rats. The frequencies of GPI-deficient cells were similar for RBCs and spleen T-cells. These results indicate that FCM detection of GPI-linked markers may form the basis for a rapid in vivo mutation assay. Although RBCs may be useful for a minimally invasive assay, T-cells are a promising tissue for both detecting GPI-deficient cells and confirming that Pig-A gene mutation is the cause of the phenotype.
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Affiliation(s)
- Daishiro Miura
- Division of Genetic and Reproductive Toxicology, US Food and Drug Administration, National Center for Toxicological Research, Jefferson, Arkansas 72079, USA
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Miura D, Dobrovolsky VN, Mittelstaedt RA, Kasahara Y, Katsuura Y, Heflich RH. Development of an in vivo gene mutation assay using the endogenous Pig-A gene: II. Selection of Pig-A mutant rat spleen T-cells with proaerolysin and sequencing Pig-A cDNA from the mutants. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2008; 49:622-630. [PMID: 18626996 DOI: 10.1002/em.20413] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We previously reported that rat spleen T-cells and peripheral red blood cells that are deficient in glycosylphosphatidylinositol (GPI) synthesis [presumed mutants for the phosphatidylinositol glycan complementation group A gene (Pig-A)] could be detected by flow cytometry (FCM) as cells negative for GPI-linked markers (CD48 and CD59, respectively). To establish this procedure as a rapid in vivo gene mutation assay, we have examined the Pig-A gene of GPI-deficient rat spleen T-cells for DNA sequence alterations. Splenocytes were isolated from male F344 rats, primed with ionomycin and phorbol-12-myristate-13-acetate, and seeded at limiting-dilution into 96-well plates. To select for GPI-deficient T-cells, the cells were cultured for 10 days in a medium containing rat T-STIM and 2 nM proaerolysin (ProAER). The frequency of ProAER-resistant (ProAER(r)) spleen T-cells from control rats ranged from 1.3 x 10(-6) to 4.8 x 10(-6), while administration of three doses of 40 mg/kg N-ethyl-N-nitrosourea increased the frequency of ProAER(r) T-cells 100-fold at 4 weeks after dosing. FCM analysis of the cells in ProAER(r) clones revealed that they were CD48-negative, and thus presumably GPI-deficient. Sequencing of Pig-A cDNA from six ProAER(r) clones indicated that they all contained alterations in the Pig-A protein coding sequence; five had base pair substitutions and one had multiple exons deleted. These results indicate that GPI-deficient spleen T-cells are Pig-A gene mutants and support the use of FCM analysis of GPI-deficient cells as a rapid assay for measuring in vivo gene mutation.
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Affiliation(s)
- Daishiro Miura
- Division of Genetic and Reproductive Toxicology, U.S. Food and Drug Administration, National Center for Toxicological Research, Jefferson, Arkansas
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Brodsky RA. Paroxysmal nocturnal hemoglobinuria: stem cells and clonality. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2008; 2008:111-115. [PMID: 19074067 DOI: 10.1182/asheducation-2008.1.111] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Paroxysmal nocturnal hemoglobinuria is a clonal hematopoietic stem cell disease that manifests with intravascular hemolysis, bone marrow failure, thrombosis, and smooth muscle dystonias. The disease can arise de novo or in the setting of acquired aplastic anemia. All PNH patients to date have been shown to harbor PIG-A mutations; the product of this gene is required for the synthesis of glycosylphosphatidylinositol (GPI) anchored proteins. In PNH patients, PIG-A mutations arise from a multipotent hematopoietic stem cell. Interestingly, PIG-A mutations can also be found in the peripheral blood of most healthy controls; however, these mutations arise from progenitor cells rather than multipotent hematopoietic stem cells and do not propagate the disease. The mechanism of whereby PNH stem cells achieve clonal dominance remains unclear. The leading hypotheses to explain clonal outgrowth in PNH are: 1) PNH cells evade immune attack possibly, because of an absent cell surface GPI-AP that is the target of the immune attack; 2) The PIG-A mutation confers an intrinsic resistance to apoptosis that becomes more conspicuous when the marrow is under immune attack; and 3) A second mutation occurs in the PNH clone to give it an intrinsic survival advantage. These hypotheses may not be mutually exclusive, since data in support of all three models have been generated.
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Affiliation(s)
- Robert A Brodsky
- Division of Hematology, Johns Hopkins University School of Medicine, Baltimore, MD 21205-0185, USA.
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Parker CJ. The pathophysiology of paroxysmal nocturnal hemoglobinuria. Exp Hematol 2007; 35:523-33. [PMID: 17379062 DOI: 10.1016/j.exphem.2007.01.046] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 01/18/2007] [Accepted: 01/19/2007] [Indexed: 12/12/2022]
Abstract
The molecular basis of PNH is known. Somatic mutation of the X-chromosome gene PIGA accounts for deficiency of glycosyl phosphatidylinositol-anchored proteins (GPI-AP) on affected hematopoietic stem cells and their progeny. However, neither mutant PIGA nor the consequent deficiency of GPI-AP provides a direct explanation for the clonal outgrowth of the mutant stem cells. Therefore, PNH differs from malignant myelopathies in which clonal expansion is directly attributable to a specific, monogenetic event (e.g., t(9;22) in CML) that bestows a growth/survival advantage upon the affected cell. Multiple, discrete PIGA mutant clones are present in many patients, suggesting that a selection pressure that favors the PNH phenotype (i.e., GPI-AP deficiency) was applied to the bone marrow. The nature of this putative selection pressure, however, is speculative, as is the basis of clonal expansion. In many patients, the majority of hematopoiesis is derived from PIGA mutant stem cells. Yet clonal expansion is limited (nonmalignant), and the contribution of the mutant clones to hematopoiesis may remain stable for decades. Understanding the basis of clonal selection and expansion will not only delineate further the pathophysiology of PNH but also provide new insights into stem cell biology and suggest novel therapeutic strategies for enhancing marrow function.
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Affiliation(s)
- Charles J Parker
- Division of Hematology and Bone Marrow Transplant, University of Utah School of Medicine and the George E. Whalen Department of Veterans Affairs Medical Center, 500 Foothill Boulevard, Salt Lake City, UT 84114, USA.
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Brodsky RA, Hu R. PIG-A mutations in paroxysmal nocturnal hemoglobinuria and in normal hematopoiesis. Leuk Lymphoma 2007; 47:1215-21. [PMID: 16923549 DOI: 10.1080/10428190600555520] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
PIG-A is an X-linked gene that is essential for the first step in the biosynthesis of glycosylphosphatidyl-inositol (GPI) anchors. A rare clonal hematopoietic stem cell disease, paroxysmal nocturnal hemoglobinuria (PNH), is caused by mutations in the PIG-A gene. PNH is an acquired disease that may arise de novo or emanate from aplastic anemia. PNH blood cells have an absence or marked deficiency of all GPI anchored proteins. Interestingly, rare GPI anchor deficient blood and marrow cells that harbor PIG-A mutations can also be found in most healthy controls. This review examines the clinical and biological relevance of PIG-A mutations in PNH, aplastic anemia and healthy controls.
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Affiliation(s)
- Robert A Brodsky
- Johns Hopkins University School of Medicine, Division of Hematology, Baltimore, MD, USA.
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Brodsky RA. New insights into paroxysmal nocturnal hemoglobinuria. HEMATOLOGY. AMERICAN SOCIETY OF HEMATOLOGY. EDUCATION PROGRAM 2006:24-8, 516. [PMID: 17124035 DOI: 10.1182/asheducation-2006.1.24] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is an uncommon intravascular hemolytic anemia that results from the clonal expansion of hematopoietic stem cells harboring somatic mutations in an X-linked gene, termed PIG-A. PIG-A mutations block glycosylphosphatidylinositol (GPI) anchor biosynthesis, resulting in a deficiency or absence of all GPI-anchored proteins on the cell surface. CD55 and CD59 are GPI-anchored complement regulatory proteins. Their absence on PNH red cells is responsible for the complement-mediated intravascular hemolysis. Intravascular hemolysis leads to release of free hemoglobin, which contributes to many of the clinical manifestations of PNH including fatigue, pain, esophageal spasm, erectile dysfunction and possibly thrombosis. Interestingly, rare PIG-A mutations can be found in virtually all healthy control subjects, leading to speculation that PIG-A mutations in hematopoietic stem cells are common benign events. However, negative selection of PIG-A mutant colony-forming cells with proaerolysin, a toxin that targets GPI-anchored proteins, reveals that most of these mutations are not derived from stem cells. Recently, a humanized monoclonal antibody directed against the terminal complement protein C5 has been shown to reduce hemolysis and greatly improve symptoms and quality of life for PNH patients.
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Affiliation(s)
- Robert A Brodsky
- Johns Hopkins University School of Medicine, Division of Hematology, Baltimore, MD 21205, USA.
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Araten DJ, Golde DW, Zhang RH, Thaler HT, Gargiulo L, Notaro R, Luzzatto L. A quantitative measurement of the human somatic mutation rate. Cancer Res 2005; 65:8111-7. [PMID: 16166284 DOI: 10.1158/0008-5472.can-04-1198] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The mutation rate (mu) is a key biological feature of somatic cells that determines risk for malignant transformation, and it has been exceedingly difficult to measure in human cells. For this purpose, a potential sentinel is the X-linked PIG-A gene, because its inactivation causes lack of glycosylphosphatidylinositol-linked membrane proteins. We previously found that the frequency (f) of PIG-A mutant cells can be measured accurately by flow cytometry, even when f is very low. Here we measure both f and mu by culturing B-lymphoblastoid cell lines and first eliminating preexisting PIG-A mutants by flow sorting. After expansion in culture, the frequency of new mutants is determined by flow cytometry using antibodies specific for glycosylphosphatidylinositol-linked proteins (e.g., CD48, CD55, and CD59). The mutation rate is then calculated by the formula mu = f/d, where d is the number of cell divisions occurring in culture. The mean mu in cells from normal donors was 10.6 x 10(-7) mutations per cell division (range 2.4 to 29.6 x 10(-7)). The mean mu was elevated >30-fold in cells from patients with Fanconi anemia (P < 0.0001), and mu varied widely in ataxia-telangiectasia with a mean 4-fold elevation (P = 0.002). In contrast, mu was not significantly different from normal in cells from patients with Nijmegen breakage syndrome. Differences in mu could not be attributed to variations in plating efficiency. The mutation rate in man can now be measured routinely in B-lymphoblastoid cell lines, and it is elevated in cancer predisposition syndromes. This system should be useful in evaluating cancer risk and in the design of preventive strategies.
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Affiliation(s)
- David J Araten
- Division of Hematology, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
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Garland RJ, Groves SJ, Diamanti P, West SE, Winship KL, Virgo PF, Robinson SP, Oakhill A, Cornish JM, Pamphilon DH, Marks DI, Goulden NJ, Steward CG. Early emergence of PNH-like T cells after allogeneic stem cell transplants utilising CAMPATH-1H for T cell depletion. Bone Marrow Transplant 2005; 36:237-44. [PMID: 15968291 DOI: 10.1038/sj.bmt.1705049] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
CAMPATH-1H (C-1H) is widely used in vivo and / or in vitro for T cell depletion in hematopoietic SCT. This humanised monoclonal antibody is specific for CD52, a marker coexpressed on the majority of human lymphocytes with CD48 and other glycosylphosphatidyl-inositol (GPI) anchored proteins. We detected CD52 / CD48 dual expression on >99% of CD3(+) lymphocytes from normal individuals and all 15 post-SCT patients whose transplants did not utilise C-1H. By contrast, 23 / 26 patients with transplants involving C-1H (in vivo, in vitro or both) exhibited populations lacking CD52 expression that accounted for 49.7% (4.2-86.2%) of the CD3+ lymphocytes (median and range) in samples evaluated at a median of 2 months post-SCT. Most CD52- cells also lacked CD48 expression. These GPI- T cells were of either donor or mixed donor / recipient origin. They were predominant in the early months after SCT at times of profound lymphopenia and inversely correlated with the recovery of the absolute lymphocyte count (r= - 0.663, P<0.0001). The presence of CD52- cells has been correlated previously with clinical outcome after CAMPATH therapy for both malignant and nonmalignant diseases.
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MESH Headings
- Adolescent
- Adult
- Alemtuzumab
- Antibodies, Monoclonal/chemistry
- Antibodies, Monoclonal, Humanized
- Antibodies, Neoplasm/chemistry
- Antigens, CD/biosynthesis
- Antigens, CD/chemistry
- Antigens, Neoplasm/biosynthesis
- Antigens, Neoplasm/chemistry
- Antineoplastic Agents/pharmacology
- CD3 Complex/biosynthesis
- CD48 Antigen
- CD52 Antigen
- Cell Separation
- Child
- Child, Preschool
- Cohort Studies
- Female
- Flow Cytometry
- Glycoproteins/biosynthesis
- Glycoproteins/chemistry
- Glycosylphosphatidylinositols/metabolism
- Hemoglobinuria, Paroxysmal/metabolism
- Humans
- Immunomagnetic Separation
- Male
- Middle Aged
- Stem Cell Transplantation
- T-Lymphocytes/cytology
- T-Lymphocytes/metabolism
- Time Factors
- Transplantation Chimera
- Transplantation, Homologous/methods
- Treatment Outcome
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Affiliation(s)
- R J Garland
- Department of Pathology and Microbiology, University of Bristol, University Walk, Bristol, UK.
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Hu R, Mukhina GL, Piantadosi S, Barber JP, Jones RJ, Brodsky RA. PIG-A mutations in normal hematopoiesis. Blood 2005; 105:3848-54. [PMID: 15687243 PMCID: PMC1895084 DOI: 10.1182/blood-2004-04-1472] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is caused by phosphatidylinositol glycan-class A (PIG-A) mutations in hematopoietic stem cells (HSCs). PIG-A mutations have been found in granulocytes from most healthy individuals, suggesting that these spontaneous PIG-A mutations are important in the pathogenesis of PNH. It remains unclear if these PIG-A mutations have relevance to those found in PNH. We isolated CD34+ progenitors from 4 patients with PNH and 27 controls. The frequency of PIG-A mutant progenitors was determined by assaying for colony-forming cells (CFCs) in methylcellulose containing toxic doses of aerolysin (1 x 10(-9) M). Glycosylphosphatidylinositol (GPI)-anchored proteins serve as receptors for aerolysin; thus, PNH cells are resistant to aerolysin. The frequency of aerolysin resistant CFC was 14.7 +/- 4.0 x 10(-6) in the bone marrow of healthy donors and was 57.0 +/- 6.7 x 10(-6) from mobilized peripheral blood. DNA was extracted from individual day-14 aerolysin-resistant CFCs and the PIG-A gene was sequenced to determine clonality. Aerolysin-resistant CFCs from patients with PNH exhibited clonal PIG-A mutations. In contrast, PIG-A mutations in the CFCs from controls were polyclonal, and did not involve T cells. Our data confirm the finding that PIG-A mutations are relatively common in normal hematopoiesis; however, the finding suggests that these mutations occur in differentiated progenitors rather than HSCs.
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Affiliation(s)
- Rong Hu
- Johns Hopkins University, School of Medicine, Division of Hematology, Baltimore, MD 21205, USA
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Chen G, Zeng W, Green S, Young NS. Frequent HPRT mutations in paroxysmal nocturnal haemoglobinuria reflect T cell clonal expansion, not genomic instability. Br J Haematol 2004; 125:383-91. [PMID: 15086421 DOI: 10.1111/j.1365-2141.2004.04912.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Paroxysmal nocturnal haemoglobinuria (PNH) results from acquired mutations in the PIG-A gene of an haematopoietic stem cell, leading to defective biosynthesis of glycosylphosphatidylinositol (GPI) anchors and deficient expression of GPI-anchored proteins on the surface of the cell's progeny. Some laboratory and clinical findings have suggested genomic instability to be intrinsic in PNH; this possibility has been supported by mutation analysis of hypoxanthine-guanine phosphoribosyltransferase (HPRT) gene abnormalities. However, the HPRT assay examines lymphocytes in peripheral blood (PB), and T cells may be related to the pathophysiology of PNH. We analysed the molecular and functional features of HPRT mutants in PB mononuclear cells from eleven PNH patients. CD8 T cells predominated in these samples; approximately half of the CD8 cells lacked GPI-anchored protein expression, while only a small proportion of CD4 cells appeared to derive from the PNH clone. The HPRT mutant frequency (Mf) in T lymphocytes from PNH patients was significantly higher than in healthy controls. The majority of the mutant T lymphocyte clones were of CD4 phenotype, and they had phenotypically normal GPI-anchored protein expression. In PNH patients, the majority of HPRT mutant clones were contained within the Vbeta2 T cell receptor (TCR) subfamily, which was oligoclonal by complementarity-determining region three (CDR3) size analysis. Our results are more consistent with detection of uniform populations of expanded T cell clones, which presumably acquired HPRT mutations during antigen-driven cell proliferation, and not due to an increased Mf in PNH. HPRT mutant analysis does not support underlying genomic instability in PNH.
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Affiliation(s)
- Guibin Chen
- Haematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD 20892-1652, USA
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Cui W, Fan Y, Yang M, Zhang Z. Expression of CD59 on lymphocyte and the subsets and its potential clinical application for paroxysmal nocturnal hemoglobinuria diagnosis. ACTA ACUST UNITED AC 2004; 26:95-100. [PMID: 15053802 DOI: 10.1111/j.1365-2257.2004.00586.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lymphocyte analysis has not been accepted as an indicator for the clinical diagnosis of paroxysmal nocturnal hemoglobinuria (PNH), because of diverse CD59 expression, even in the healthy individuals. We studied the expression of CD59 on lymphocytes and lymphocyte subsets in healthy individuals and PNH patients by flow cytometry. In 50 healthy individuals, granulocytes generally showed a single-cell population that was strongly positive for CD59. Lymphocytes showed, in addition to the population of positive cells, a small population of weakly positive cells, while CD3+ T-cells showed a large population of weakly positive cells. Natural killer (NK)-cells showed a profile similar to CD3+ T-cells. CD4+ T-cells showed a larger population of strongly positive cells, as compared with CD3+ T-cells, while CD8+ T-cells showed a smaller population of strongly positive cells. CD20+ B-cells showed a similar profile to granulocytes. CD59 expression studies in all our PNH patients showed that B-cells expressed CD59 at levels similar to granulocytes, which were lower than those of T-cells and NK-cells. Therefore, the lymphocyte population with low level CD59 expression in healthy controls corresponds to T-cells (especially CD8+ T-cells) and NK-cells. CD59 expression on B-cells could thus be used as a new marker for the diagnosis of PNH.
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Affiliation(s)
- W Cui
- Department of Clinical Laboratory, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China.
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Terpos E, Samarkos M, Meletis C, Apostolidou E, Tsironi M, Korovesis K, Mavrogianni D, Viniou N, Meletis J. Unusual association between increased bone resorption and presence of paroxysmal nocturnal hemoglobinuria phenotype in multiple myeloma. Int J Hematol 2003; 78:344-8. [PMID: 14686493 DOI: 10.1007/bf02983560] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) clones deficient in glycosylphosphatidylinositol-anchored molecules, including CD55 and CD59, have been previously described in patients with multiple myeloma (MM). The aim of this study was to investigate the possible association between existence of the PNH phenotype and myeloma bone disease. Forty-three patients with newly diagnosed MM were the subjects of the study. Radiographic evaluation of the skeleton was performed in all patients at diagnosis. The following biochemical markers were measured: bone resorption markers (tartrate-resistant acid phosphatase isoform 5b [TRACP-5b]and N-terminal cross-linking telopeptide of type-I collagen [NTX]), bone formation markers (bone alkaline phosphatase [bALP] and osteocalcin [OC]), osteoprotegerin (OPG), soluble receptor activator of nuclear factor KB ligand (sRANKL), and interleukin 6 (IL-6). Detection of CD55- and/or CD59-deficient red cell populations was performed after diagnosis. Patients with MM had elevated mean baseline NTX, TRACP-5b, sRANKL, and IL-6 levels compared with controls, whereas the mean values of bALP, OC, and OPG were significantly decreased. Four patients had no osteolytic lesions, whereas 8 patients had 1 to 3 lytic lesions, and 31 patients had more than 3 lytic lesions and/or pathologic fractures in the skeletal survey. CD55- and/or CD59-deficient red cell populations were observed in 56% of patients with MM. There was a strong correlation between the presence of PNH-like erythrocytes and increased bone resorption, as measured by NTX, TRACP-5b, and sRANKL/OPG ratio (P < .03, P < .02, and P < .02, respectively). There was also a significant correlation between PNH phenotype and severe bone disease (P < .02). These results suggest that there is a possible link between PNH phenotype and increased osteoclastic activity in MM owing to a potential effect of myeloma microenvironment on a preexisting PNH clone. Further studies are required for clarifying this phenomenon and investigating possible mechanisms of this unusual association.
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Affiliation(s)
- Evangelos Terpos
- Department of Hematology, 251 General Air Force Hospital, Athens, Greece.
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Nishimura JI, Ware RE, Burnette A, Pendleton AL, Kitano K, Hirota T, Machii T, Kitani T, Smith CA, Rosse WF. The hematopoietic defect in PNH is not due to defective stroma, but is due to defective progenitor cells. Blood Cells Mol Dis 2002; 29:159-67. [PMID: 12490282 DOI: 10.1006/bcmd.2002.0552] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although paroxysmal nocturnal hemoglobinuria (PNH) is often associated with aplastic anemia (AA), the nature of the pathogenetic link between PNH and AA remains unclear. Moreover, the PIG-A mutation appears to be necessary but not sufficient for the development of PNH, suggesting other factors are involved. The ability of PNH marrow cells to form in vitro hematopoietic colonies and the ability of PNH marrow to generate stroma that could support hematopoiesis of normal or PNH marrow in cross culture were investigated. PNH marrow from both post-Ficoll and post-lineage depleted hematopoietic progenitor cells grew similarly significantly fewer colonies than normal marrow. Sorting of CD59(+) and CD59(-) CD34(+) CD38(-) cells from patients with PNH showed similarly impaired clonogenic efficiency, indicating that the hematopoietic defect in PNH does not directly relate to GPI-anchored protein expression. PNH marrow readily grew stroma similar to marrow from normal donors. Cross culture experiments revealed that PNH stroma appears to function normally in vitro; it can support growth of normal marrow cells as well as normal stroma does, but neither PNH nor normal stroma could support the growth of PNH marrow cells. The hematopoietic defect in PNH is not due to defective stroma, but is due to defective progenitor cell growth related to additional unknown factors.
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Affiliation(s)
- Jun-ichi Nishimura
- Department of Medicine, Duke University Medical Center, Durham, North Carolina 27710, USA
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