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Dybska E, Adams AT, Duclaux-Loras R, Walkowiak J, Nowak JK. Waiting in the wings: RUNX3 reveals hidden depths of immune regulation with potential implications for inflammatory bowel disease. Scand J Immunol 2021; 93:e13025. [PMID: 33528856 DOI: 10.1111/sji.13025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2020] [Revised: 01/11/2021] [Accepted: 01/27/2021] [Indexed: 12/14/2022]
Abstract
BACKGROUND Complex interactions between the environment and the mucosal immune system underlie inflammatory bowel disease (IBD). The involved cytokine signalling pathways are modulated by a number of transcription factors, one of which is runt-related transcription factor 3 (RUNX3). OBJECTIVE To systematically review the immune roles of RUNX3 in immune regulation, with a focus on the context of IBD. METHODS Relevant articles and reviews were identified through a Scopus search in April 2020. Information was categorized by immune cell types, analysed and synthesized. IBD transcriptome data sets and FANTOM5 regulatory networks were processed in order to complement the literature review. RESULTS The available evidence on the immune roles of RUNX3 allowed for its description in twelve cell types: intraepithelial lymphocyte, Th1, Th2, Th17, Treg, double-positive T, cytotoxic T, B, dendritic, innate lymphoid, natural killer and macrophages. In the gut, the activity of RUNX3 is multifaceted and context-dependent: it may promote homeostasis or exacerbated reactions via cytokine signalling and regulation of receptor expression. RUNX3 is mostly engaged in pathways involving ThPOK, T-bet, IFN-γ, TGF-β/IL-2Rβ, GATA/CBF-β, SMAD/p300 and a number of miRNAs. RUNX3 targets relevant to IBD may include RAG1, OSM and IL-17B. Moreover, in IBD RUNX3 expression correlates positively with GZMM, and negatively with IFNAR1, whereas in controls, it strongly associates with TGFBR3. CONCLUSIONS Dysregulation of RUNX3, mostly in the form of deficiency, likely contributes to IBD pathogenesis. More clinical research is needed to examine RUNX3 in IBD.
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Affiliation(s)
- Emilia Dybska
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznan, Poland
| | - Alex T Adams
- Translational Gastroenterology Unit, Nuffield Department of Medicine, Experimental Medicine Division, John Radcliffe Hospital, University of Oxford, Oxford, UK
| | - Rémi Duclaux-Loras
- INSERM U1111, Centre International de Recherche en Infectiologie, Université Claude Bernard Lyon 1, Lyon, France
| | - Jarosław Walkowiak
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznan, Poland
| | - Jan K Nowak
- Department of Pediatric Gastroenterology and Metabolic Diseases, Poznan University of Medical Sciences, Poznan, Poland
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Zeng Y, Liu C, Gong Y, Bai Z, Hou S, He J, Bian Z, Li Z, Ni Y, Yan J, Huang T, Shi H, Ma C, Chen X, Wang J, Bian L, Lan Y, Liu B, Hu H. Single-Cell RNA Sequencing Resolves Spatiotemporal Development of Pre-thymic Lymphoid Progenitors and Thymus Organogenesis in Human Embryos. Immunity 2019; 51:930-948.e6. [PMID: 31604687 DOI: 10.1016/j.immuni.2019.09.008] [Citation(s) in RCA: 82] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/25/2019] [Accepted: 09/11/2019] [Indexed: 02/05/2023]
Abstract
Generation of the first T lymphocytes in the human embryo involves the emergence, migration, and thymus seeding of lymphoid progenitors together with concomitant thymus organogenesis, which is the initial step to establish the entire adaptive immune system. However, the cellular and molecular programs regulating this process remain unclear. We constructed a single-cell transcriptional landscape of human early T lymphopoiesis by using cells from multiple hemogenic and hematopoietic sites spanning embryonic and fetal stages. Among heterogenous early thymic progenitors, one subtype shared common features with a subset of lymphoid progenitors in fetal liver that are known as thymus-seeding progenitors. Unbiased bioinformatics analysis identified a distinct type of pre-thymic lymphoid progenitors in the aorta-gonad-mesonephros (AGM) region. In parallel, we investigated thymic epithelial cell development and potential cell-cell interactions during thymus organogenesis. Together, our data provide insights into human early T lymphopoiesis that prospectively direct T lymphocyte regeneration, which might lead to development of clinical applications.
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Affiliation(s)
- Yang Zeng
- State Key Laboratory of Experimental Hematology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China
| | - Chen Liu
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Yandong Gong
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Zhijie Bai
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Siyuan Hou
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Jian He
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Zhilei Bian
- Key Laboratory for Regenerative Medicine of Ministry of Education, Institute of Hematology, School of Medicine, Jinan University, Guangzhou 510632, China; Guangzhou Regenerative Medicine and Health-Guangdong Laboratory (GRMH-GDL), Guangzhou 510530, China
| | - Zongcheng Li
- State Key Laboratory of Experimental Hematology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China
| | - Yanli Ni
- State Key Laboratory of Experimental Hematology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China
| | - Jing Yan
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Tao Huang
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Hui Shi
- State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China
| | - Chunyu Ma
- Department of Gynecology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China
| | - Xueying Chen
- Department of Rheumatology and Immunology, Rare Disease Center, the State Key Laboratory of Biotherapy, West China Hospital, Sichuan University. Collaboration and Innovation Center for Biotherapy. Chengdu 610041, China
| | - Jinyong Wang
- CAS Key Laboratory of Regenerative Biology, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Lihong Bian
- Department of Gynecology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China
| | - Yu Lan
- Key Laboratory for Regenerative Medicine of Ministry of Education, Institute of Hematology, School of Medicine, Jinan University, Guangzhou 510632, China; Guangzhou Regenerative Medicine and Health-Guangdong Laboratory (GRMH-GDL), Guangzhou 510530, China.
| | - Bing Liu
- State Key Laboratory of Experimental Hematology, Fifth Medical Center of Chinese PLA General Hospital, Beijing 100071, China; State Key Laboratory of Proteomics, Academy of Military Medical Sciences, Academy of Military Sciences, Beijing 100071, China; Key Laboratory for Regenerative Medicine of Ministry of Education, Institute of Hematology, School of Medicine, Jinan University, Guangzhou 510632, China; State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences, Tianjin 300020, China.
| | - Hongbo Hu
- Department of Rheumatology and Immunology, Rare Disease Center, the State Key Laboratory of Biotherapy, West China Hospital, Sichuan University. Collaboration and Innovation Center for Biotherapy. Chengdu 610041, China.
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3
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Nyanhete TE, Frisbee AL, Bradley T, Faison WJ, Robins E, Payne T, Freel SA, Sawant S, Weinhold KJ, Wiehe K, Haynes BF, Ferrari G, Li QJ, Moody MA, Tomaras GD. HLA class II-Restricted CD8+ T cells in HIV-1 Virus Controllers. Sci Rep 2019; 9:10165. [PMID: 31308388 PMCID: PMC6629643 DOI: 10.1038/s41598-019-46462-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 06/27/2019] [Indexed: 12/16/2022] Open
Abstract
A paradigm shifting study demonstrated that induction of MHC class E and II-restricted CD8+ T cells was associated with the clearance of SIV infection in rhesus macaques. Another recent study highlighted the presence of HIV-1-specific class II-restricted CD8+ T cells in HIV-1 patients who naturally control infection (virus controllers; VCs). However, questions regarding class II-restricted CD8+ T cells ontogeny, distribution across different HIV-1 disease states and their role in viral control remain unclear. In this study, we investigated the distribution and anti-viral properties of HLA-DRB1*0701 and DQB1*0501 class II-restricted CD8+ T cells in different HIV-1 patient cohorts; and whether class II-restricted CD8+ T cells represent a unique T cell subset. We show that memory class II-restricted CD8+ T cell responses were more often detectable in VCs than in chronically infected patients, but not in healthy seronegative donors. We also demonstrate that VC CD8+ T cells inhibit virus replication in both a class I- and class II-dependent manner, and that in two VC patients the class II-restricted CD8+ T cells with an anti-viral gene signature expressed both CD4+ and CD8+ T cell lineage-specific genes. These data demonstrated that anti-viral memory class II-restricted CD8+ T cells with hybrid CD4+ and CD8+ features are present during natural HIV-1 infection.
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Affiliation(s)
- Tinashe E Nyanhete
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Alyse L Frisbee
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,University of Virginia Department of Microbiology, Immunology and Cancer Biology, 345 Crispell Drive, University of Virginia Health System, Charlottesville, Virginia, 22908, USA
| | - Todd Bradley
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA
| | - William J Faison
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Elizabeth Robins
- Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Tamika Payne
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Stephanie A Freel
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Sheetal Sawant
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kent J Weinhold
- Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kevin Wiehe
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Barton F Haynes
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Guido Ferrari
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Qi-Jing Li
- Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - M Anthony Moody
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA.,Department of Pediatrics, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Georgia D Tomaras
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, NC, 27710, USA. .,Department of Immunology, Duke University School of Medicine, Durham, NC, 27710, USA. .,Department of Medicine, Duke University School of Medicine, Durham, NC, 27710, USA. .,Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27710, USA. .,Department of Surgery, Duke University School of Medicine, Durham, NC, 27710, USA.
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Maccani JZ, Maccani MA. Altered placental DNA methylation patterns associated with maternal smoking: current perspectives. ADVANCES IN GENOMICS AND GENETICS 2015; 2015:205-214. [PMID: 26203295 PMCID: PMC4507353 DOI: 10.2147/agg.s61518] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The developmental origins of health and disease hypothesis states that adverse early life exposures can have lasting, detrimental effects on lifelong health. Exposure to maternal cigarette smoking during pregnancy is associated with morbidity and mortality in offspring, including increased risks for miscarriage, stillbirth, low birth weight, preterm birth, asthma, obesity, altered neurobehavior, and other conditions. Maternal cigarette smoking during pregnancy interferes with placental growth and functioning, and it has been proposed that this may occur through the disruption of normal and necessary placental epigenetic patterns. Epigenome-wide association studies have identified a number of differentially methylated placental genes that are associated with maternal smoking during pregnancy, including RUNX3, PURA, GTF2H2, GCA, GPR135, and HKR1. The placental methylation status of RUNX3 and NR3C1 has also been linked to adverse infant outcomes, including preterm birth and low birth weight, respectively. Candidate gene analyses have also found maternal smoking-associated placental methylation differences in the NR3C1, CYP1A1, HTR2A, and HSD11B2 genes, as well as in the repetitive elements LINE-1 and AluYb8. The differential methylation patterns of several genes have been confirmed to also exhibit altered gene expression patterns, including CYP1A1, CYP19A1, NR3C1, and HTR2A. Placental methylation patterns associated with maternal smoking during pregnancy may be largely gene-specific and tissue-specific and, to a lesser degree, involve global changes. It is important for future research to investigate the mechanistic roles that these differentially methylated genes may play in mediating the association between maternal smoking during pregnancy and disease in later life, as well as to elucidate the potential influence of emerging tobacco product use during pregnancy, including the use of electronic cigarettes, on placental epigenetics.
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Affiliation(s)
- Jennifer Zj Maccani
- Penn State Tobacco Center of Regulatory Science, College of Medicine, Department of Public Health Sciences, Hershey, PA, USA
| | - Matthew A Maccani
- Penn State Tobacco Center of Regulatory Science, College of Medicine, Department of Public Health Sciences, Hershey, PA, USA
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Joubert B, Honnorat J. Autoimmune channelopathies in paraneoplastic neurological syndromes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2015; 1848:2665-76. [PMID: 25883091 DOI: 10.1016/j.bbamem.2015.04.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2014] [Revised: 03/10/2015] [Accepted: 04/03/2015] [Indexed: 01/17/2023]
Abstract
Paraneoplastic neurological syndromes and autoimmune encephalitides are immune neurological disorders occurring or not in association with a cancer. They are thought to be due to an autoimmune reaction against neuronal antigens ectopically expressed by the underlying tumour or by cross-reaction with an unknown infectious agent. In some instances, paraneoplastic neurological syndromes and autoimmune encephalitides are related to an antibody-induced dysfunction of ion channels, a situation that can be labelled as autoimmune channelopathies. Such functional alterations of ion channels are caused by the specific fixation of an autoantibody upon its target, implying that autoimmune channelopathies are usually highly responsive to immuno-modulatory treatments. Over the recent years, numerous autoantibodies corresponding to various neurological syndromes have been discovered and their mechanisms of action partially deciphered. Autoantibodies in neurological autoimmune channelopathies may target either directly ion channels or proteins associated to ion channels and induce channel dysfunction by various mechanisms generally leading to the reduction of synaptic expression of the considered channel. The discovery of those mechanisms of action has provided insights on the regulation of the synaptic expression of the altered channels as well as the putative roles of some of their functional subdomains. Interestingly, patients' autoantibodies themselves can be used as specific tools in order to study the functions of ion channels. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.
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Affiliation(s)
- Bastien Joubert
- University Lyon 1, University Lyon, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France; INSERM, UMR-S1028, CNRS, UMR-5292, Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-Inflammation Team, 7, Rue Guillaume Paradin, Lyon Cedex 08F-69372, France
| | - Jérôme Honnorat
- University Lyon 1, University Lyon, Rue Guillaume Paradin, 69372 Lyon Cedex 08, France; INSERM, UMR-S1028, CNRS, UMR-5292, Lyon Neuroscience Research Center, Neuro-Oncology and Neuro-Inflammation Team, 7, Rue Guillaume Paradin, Lyon Cedex 08F-69372, France; National Reference Centre for Paraneoplastic Neurological Diseases, hospices civils de Lyon, hôpital neurologique, 69677 Bron, France; Hospices Civils de Lyon, Neuro-oncology, Hôpital Neurologique, F-69677 Bron, France.
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7
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Maccani JZJ, Koestler DC, Houseman EA, Marsit CJ, Kelsey KT. Placental DNA methylation alterations associated with maternal tobacco smoking at the RUNX3 gene are also associated with gestational age. Epigenomics 2013; 5:619-30. [PMID: 24283877 PMCID: PMC3982305 DOI: 10.2217/epi.13.63] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
AIMS The developmental origins of health and disease hypothesis states that later-life disease may be influenced by the quality of the in utero environment. Environmental toxicants can have detrimental effects on fetal development, potentially through effects on placental development and function. Maternal smoking during pregnancy is associated with low birth weight, preterm birth and other complications, and exposure to cigarette smoke in utero has been linked to gross pathologic and molecular changes to the placenta, including differential DNA methylation in placental tissue. The aim of this study was to investigate the relationship between maternal smoking during pregnancy, methylation changes in the placenta and gestational age. MATERIALS & METHODS We used Illumina(®)'s (CA, USA) Human Methylation27 BeadChip technology platform to investigate the methylation status of 21,551 autosomal, non-SNP-associated CpG loci in DNA extracted from 206 human placentas and examined loci whose variation in methylation was associated with maternal smoking during pregnancy. RESULTS We found that methylation patterns of a number of loci within the RUNX3 gene were significantly associated with smoking during pregnancy, and one of these loci was associated with decreased gestational age (p = 0.04). CONCLUSION Our findings, demonstrating maternal smoking-induced changes in DNA methylation at specific loci, suggest a mechanism by which in utero tobacco smoke exposure could exert its detrimental effects upon the health of the fetus.
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Affiliation(s)
- Jennifer ZJ Maccani
- Department of Pathology & Laboratory Medicine, Brown University, Providence, RI, USA
| | - Devin C Koestler
- Section of Biostatistics & Epidemiology, Department of Community & Family Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | | | - Carmen J Marsit
- Section of Biostatistics & Epidemiology, Department of Community & Family Medicine, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
- Department of Pharmacology & Toxicology, Geisel School of Medicine at Dartmouth, Hanover, NH, USA
| | - Karl T Kelsey
- Department of Pathology & Laboratory Medicine, Brown University, Providence, RI, USA
- Department of Epidemiology, Brown University, Providence, RI, USA
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McClory S, Hughes T, Freud AG, Briercheck EL, Martin C, Trimboli AJ, Yu J, Zhang X, Leone G, Nuovo G, Caligiuri MA. Evidence for a stepwise program of extrathymic T cell development within the human tonsil. J Clin Invest 2012; 122:1403-15. [PMID: 22378041 DOI: 10.1172/jci46125] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2010] [Accepted: 01/11/2012] [Indexed: 02/02/2023] Open
Abstract
The development of a broad repertoire of T cells, which is essential for effective immune function, occurs in the thymus. Although some data suggest that T cell development can occur extrathymically, many researchers remain skeptical that extrathymic T cell development has an important role in generating the T cell repertoire in healthy individuals. However, it may be important in the setting of poor thymic function or congenital deficit and in the context of autoimmunity, cancer, or regenerative medicine. Here, we report evidence that a stepwise program of T cell development occurs within the human tonsil. We identified 5 tonsillar T cell developmental intermediates: (a) CD34⁺CD38dimLin⁻ cells, which resemble multipotent progenitors in the bone marrow and thymus; (b) more mature CD34⁺CD38brightLin⁻ cells; (c) CD34⁺CD1a⁺CD11c⁻ cells, which resemble committed T cell lineage precursors in the thymus; (d) CD34⁻CD1a⁺CD3⁻CD11c⁻ cells, which resemble CD4⁺CD8⁺ double-positive T cells in the thymus; and (e) CD34⁻CD1a⁺CD3⁺CD11c⁻ cells. The phenotype of each subset closely resembled that of its thymic counterpart. The last 4 populations expressed RAG1 and PTCRA, genes required for TCR rearrangement, and all 5 subsets were capable of ex vivo T cell differentiation. TdT⁺ cells found within the tonsillar fibrous scaffold expressed CD34 and/or CD1a, indicating that this distinct anatomic region contributes to pre-T cell development, as does the subcapsular region of the thymus. Thus, we provide evidence of a role for the human tonsil in a comprehensive program of extrathymic T cell development.
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Affiliation(s)
- Susan McClory
- Medical Scientist Training Program, The Ohio State University, Columbus, Ohio, USA
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Abstract
The thymus is a central lymphatic organ that is responsible for many immunological functions, including the production of mature, functional T cells and the induction of self-tolerance. Benign or malignant tumors may originate from the thymus gland, with thymoma being the most common and accounting for 50% of anterior mediastinal tumors. Malignancies linked to thymoma include the loss of self-tolerance and the presence of autoimmunity. In this review, we compiled the current scientific evidence detailing the various interactions between thymoma and autoimmune diseases, including myasthenia gravis, systemic lupus erythematosus, inappropriate antidiuretic hormone secretion, pure red cell aplasia, pernicious anemia, pemphigus and autoimmune thyroid diseases. In recent years, several mechanisms have been proposed to explain these interactions. Most are based on the assumption that the 'sick' thymus, like the 'normal' thymus, can generate mature T cells; however, the T cells generated by the sick thymus are impaired and thus may exert cellular autoreactivity. Here, we present several theories that may shed light on the loss of self-tolerance associated with this epithelial tumor of the thymus.
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