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Abstract
The conventional perception asserts that immunology is the science of ‘discrimination’ between self and non-self. This concept is however no longer tenable as effector cells of the adaptive immune system are first conditioned to be tolerant to the body’s own antigens, collectively known as self until now. Only then attain these effectors the responsiveness to non-self. The acquisition of this essential state of tolerance to self occurs for T cells in the thymus, the last major organ of our body that revealed its intricate function in health and disease. The ‘thymus’ as an anatomical notion was first notably documented in Ancient Greece although our present understanding of the organ’s functions was only deciphered commencing in the 1960s. In the late 1980s, the thymus was identified as the site where clones of cells reactive to self, termed ‘forbidden’ thymocytes, are physically depleted as the result of a process now known as negative selection. The recognition of this mechanism further contributed to the belief that the central rationale of immunology as a science lies in the distinction between self and non-self. This review will discuss the evidence that the thymus serves as a unique lymphoid organ able to instruct T cells to recognize and be tolerant to harmless self before adopting the capacity to defend the body against potentially injurious non-self-antigens presented in the context of different challenges from infections to exposure to malignant cells. The emerging insight into the thymus’ cardinal functions now also provides an opportunity to exploit this knowledge to develop novel strategies that specifically prevent or even treat organ-specific autoimmune diseases.
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Geenen V, Trussart C, Michaux H, Halouani A, Jaïdane H, Collée C, Renard C, Daukandt M, Ledent P, Martens H. The presentation of neuroendocrine self-peptides in the thymus: an essential event for individual life and vertebrate survival. Ann N Y Acad Sci 2019; 1455:113-125. [PMID: 31008523 PMCID: PMC6899491 DOI: 10.1111/nyas.14089] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2019] [Revised: 02/27/2019] [Accepted: 03/10/2019] [Indexed: 12/12/2022]
Abstract
Confirming Burnet's early hypothesis, elimination of self‐reactive T cells in the thymus was demonstrated in the late 1980s, and an important question immediately arose about the nature of the self‐peptides expressed in the thymus. Many genes encoding neuroendocrine‐related and tissue‐restricted antigens (TRAs) are transcribed in thymic epithelial cells (TECs). They are then processed for presentation by proteins of the major histocompatibility complex (MHC) expressed by TECs and thymic dendritic cells. MHC presentation of self‐peptides in the thymus programs self‐tolerance by two complementary mechanisms: (1) negative selection of self‐reactive “forbidden” T cell clones starting already in fetal life, and (2) generation of self‐specific thymic regulatory T lymphocytes (tTreg cells), mainly after birth. Many studies, including the discovery of the transcription factors autoimmune regulator (AIRE) and fasciculation and elongation protein zeta family zinc finger (FEZF2), have shown that a defect in thymus central self‐tolerance is the earliest event promoting autoimmunity. AIRE and FEZF2 control the level of transcription of many neuroendocrine self‐peptides and TRAs in the thymic epithelium. Furthermore, AIRE and FEZF2 mutations are associated with the development of autoimmunity in peripheral organs. The discovery of the intrathymic presentation of self‐peptides has revolutionized our knowledge of immunology and is opening novel avenues for prevention/treatment of autoimmunity.
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Affiliation(s)
- Vincent Geenen
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium
| | | | - Hélène Michaux
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium
| | - Aymen Halouani
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium.,Faculty of Sciences and Faculty of Pharmacy, University of Tunis El Manar, Monastir, Tunisia
| | - Hela Jaïdane
- Faculty of Sciences and Faculty of Pharmacy, University of Tunis El Manar, Monastir, Tunisia
| | - Caroline Collée
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium
| | - Chantal Renard
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium
| | - Marc Daukandt
- X-Press Biologics, Industrial Park of Milmort, Liège, Belgium
| | - Philippe Ledent
- X-Press Biologics, Industrial Park of Milmort, Liège, Belgium
| | - Henri Martens
- GIGA Institute, University of Liège, Liège-Sart Tilman, Belgium
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Feng RY, Chen Q, Yang WJ, Tong XG, Sun ZM, Yan H. Immune Tolerance Therapy: A New Method for Treatment of Traumatic Brain Injury. Chin Med J (Engl) 2018; 131:1990-1998. [PMID: 30082532 PMCID: PMC6085845 DOI: 10.4103/0366-6999.238147] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Objective: Due to the special anatomical structure and pathophysiological mechanism of the central nervous system (CNS), there is a big difference between the repair of brain injury and other systems of the body. More and more evidence shows that targetedly reducing the autoimmune response of brain tissue without affecting the immune function in other parts of the body will be the best optimized treatment for brain injury. Data Sources: This review was based on data in articles published in PubMed up to June 5, 2017, with the following keywords: “immune tolerance”, “traumatic brain injury”, and “central nervous system”. Study Selection: Original articles and critical reviews on immune tolerance and brain damage were selected for this review. References of the retrieved articles were also screened to search for potentially relevant papers. Results: The CNS is isolated from the immune system through the blood-brain barrier. After brain injury, brain antigens are released into the systemic circulation to induce damaging immune responses. Immune tolerance can effectively reduce the brain edema and neurological inflammatory response after brain injury, which is beneficial to the recovery of neurological function. The clinical application prospect and theoretical research value of the treatment of immune tolerance on traumatic brain injury (TBI) is worth attention. Conclusions: The establishment of immune tolerance mechanism has a high clinical value in the treatment of TBI. It opens up new opportunities for the treatment of brain damage.
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Affiliation(s)
- Ruo-Yang Feng
- Department of Neurosurgery, Tianjin Medical University, Tianjin 300070, China
| | - Qian Chen
- Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases; Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin 300350, China
| | - Wei-Jian Yang
- Department of Neurosurgery, Tianjin Medical University, Tianjin 300070, China
| | - Xiao-Guang Tong
- Department of Neurosurgery, Tianjin Huanhu Hospital, Tianjin 300350, China
| | - Zhi-Ming Sun
- Department of Spine Surgery, Tianjin Huanhu Hospital, Tianjin 300350, China
| | - Hua Yan
- Tianjin Key Laboratory of Cerebral Vascular and Neurodegenerative Diseases, Tianjin 300350, China
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Franchini A, Ottaviani E. Thymus: Conservation in evolution. Gen Comp Endocrinol 2017; 246:46-50. [PMID: 28322763 DOI: 10.1016/j.ygcen.2017.03.011] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 03/16/2017] [Accepted: 03/16/2017] [Indexed: 11/17/2022]
Abstract
From an evolutionary point of view, the thymus is a new organ observed for the first time in fish concomitantly with the appearance of adaptive clonotypical immunity. Hormone and neuropeptide expression was demonstrated in different species suggesting a conserved role of these molecules. An integrated evolution of immune and neuroendocrine responses appears to have been realized by means of the re-use of ancestral material, such as neuroendocrine cells and mediators, to create a thymic microenvironment for the maturation and differentiation of T cells.
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Affiliation(s)
- Antonella Franchini
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy
| | - Enzo Ottaviani
- Department of Life Sciences, University of Modena and Reggio Emilia, Modena, Italy.
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Min C, Min H, Kemei P, Ke X, Haibo H, Daiyun Z, Xinting Z. Expression of somatostatin and cDNA cloning in the thymus of the African ostrich. Acta Histochem 2014; 116:191-6. [PMID: 23915476 DOI: 10.1016/j.acthis.2013.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 06/30/2013] [Accepted: 07/02/2013] [Indexed: 11/15/2022]
Abstract
The thymus in addition to being a central lymphoid organ is also an endocrine organ which produces various neuropeptides that influence the function of this gland. Somatostatin is a neuropeptide that was isolated initially in the hypothalamus and which inhibits the release of growth hormone. The distribution of somatostatin-producing cells and the sequence of somatostatin have been determined in many species. In the present study, we investigated the expression of somatostatin in the thymus of the African ostrich and its sequence by reverse-transcriptase polymerase chain reaction and immunohistochemistry. The results showed that somatostatin mRNA was expressed in the thymus and somatostatin immunoreative cells were distributed in both the cortical and medullary regions of the thymus. Results of cDNA cloning revealed that the nucleotide sequence and the encoded protein of African ostrich somatostatin were 348 bases and 116 amino acids in length and that it is highly conserved to that of other reported species. These findings indicated that the somatostatin expressed in the thymus of ostrich might play an important role in the function of the gland. In addition, this research has provided novel molecular data allowing further study of somatostatin in the ostrich.
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Affiliation(s)
- Chen Min
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China; Xinyang College of Agriculture and Forestry, Xinyang 464000, Henan, PR China.
| | - He Min
- Xinyang College of Agriculture and Forestry, Xinyang 464000, Henan, PR China
| | - Peng Kemei
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China.
| | - Xiao Ke
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China
| | - Huang Haibo
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China
| | - Zhu Daiyun
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China
| | - Zheng Xinting
- College of Animal Science and Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China
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Geenen V, Bodart G, Henry S, Michaux H, Dardenne O, Charlet-Renard C, Martens H, Hober D. Programming of neuroendocrine self in the thymus and its defect in the development of neuroendocrine autoimmunity. Front Neurosci 2013; 7:187. [PMID: 24137108 PMCID: PMC3797387 DOI: 10.3389/fnins.2013.00187] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 09/27/2013] [Indexed: 12/20/2022] Open
Abstract
For centuries after its first description by Galen, the thymus was considered as only a vestigial endocrine organ until the discovery in 1961 by Jacques FAP Miller of its essential role in the development of T (thymo-dependent) lymphocytes. A unique thymus first appeared in cartilaginous fishes some 500 million years ago, at the same time or shortly after the emergence of the adaptive (acquired) immune system. The thymus may be compared to a small brain or a computer highly specialized in the orchestration of central immunological self-tolerance. This was a necessity for the survival of species, given the potent evolutionary pressure imposed by the high risk of autotoxicity inherent in the stochastic generation of the diversity of immune cell receptors that characterize the adaptive immune response. A new paradigm of “neuroendocrine self-peptides” has been proposed, together with the definition of “neuroendocrine self.” Neuroendocrine self-peptides are secreted by thymic epithelial cells (TECs) not according to the classic model of neuroendocrine signaling, but are processed for presentation by, or in association with, the thymic major histocompatibility complex (MHC) proteins. The autoimmune regulator (AIRE) gene/protein controls the transcription of neuroendocrine genes in TECs. The presentation of self-peptides in the thymus is responsible for the clonal deletion of self-reactive T cells, which emerge during the random recombination of gene segments that encode variable parts of the T cell receptor for the antigen (TCR). At the same time, self-antigen presentation in the thymus generates regulatory T (Treg) cells that can inhibit, in the periphery, those self-reactive T cells that escaped negative selection in the thymus. Several arguments indicate that the origin of autoimmunity directed against neuroendocrine glands results primarily from a defect in the intrathymic programming of self-tolerance to neuroendocrine functions. This defect may be genetic or acquired, for example during an enteroviral infection. This novel knowledge of normal and pathologic functions of the thymus constitutes a solid basis for the development of a novel type of tolerogenic/negative self-vaccination against type 1 diabetes (T1D).
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Affiliation(s)
- Vincent Geenen
- Department of Biomedical and Preclinical Sciences, Center of Immunoendocrinology, GIGA Research Institute, Fund of Scientific Research, University of Liege Liege-Sart Tilman, Belgium
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Koshimizu TA, Nakamura K, Egashira N, Hiroyama M, Nonoguchi H, Tanoue A. Vasopressin V1a and V1b Receptors: From Molecules to Physiological Systems. Physiol Rev 2012; 92:1813-64. [DOI: 10.1152/physrev.00035.2011] [Citation(s) in RCA: 250] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The neurohypophysial hormone arginine vasopressin (AVP) is essential for a wide range of physiological functions, including water reabsorption, cardiovascular homeostasis, hormone secretion, and social behavior. These and other actions of AVP are mediated by at least three distinct receptor subtypes: V1a, V1b, and V2. Although the antidiuretic action of AVP and V2 receptor in renal distal tubules and collecting ducts is relatively well understood, recent years have seen an increasing understanding of the physiological roles of V1a and V1b receptors. The V1a receptor is originally found in the vascular smooth muscle and the V1b receptor in the anterior pituitary. Deletion of V1a or V1b receptor genes in mice revealed that the contributions of these receptors extend far beyond cardiovascular or hormone-secreting functions. Together with extensively developed pharmacological tools, genetically altered rodent models have advanced the understanding of a variety of AVP systems. Our report reviews the findings in this important field by covering a wide range of research, from the molecular physiology of V1a and V1b receptors to studies on whole animals, including gene knockout/knockdown studies.
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Affiliation(s)
- Taka-aki Koshimizu
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Kazuaki Nakamura
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Nobuaki Egashira
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Masami Hiroyama
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Hiroshi Nonoguchi
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
| | - Akito Tanoue
- Department of Pharmacology, Division of Molecular Pharmacology, Jichi Medical University, Tochigi, Japan; Department of Pharmacology, National Research Institute for Child Health and Development, Tokyo, Japan; Department of Pharmacy, Kyushu University Hospital, Fukuoka, Japan; and Department of Internal Medicine, Kitasato University, Kitasato Institute Medical Center Hospital, Saitama, Japan
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8
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Geenen V. Thymus-Dependent T Cell Tolerance of Neuroendocrine Functions: Principles, Reflections, and Implications for Tolerogenic/Negative Self-Vaccination. Ann N Y Acad Sci 2006; 1088:284-96. [PMID: 17192574 DOI: 10.1196/annals.1366.009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Under the evolutionary pressure exerted by the emergence of adaptive immunity and its inherent risk of horror autotoxicus, the thymus appeared some 500 million years ago as a novel lymphoid structure able to prevent autoimmunity and to orchestrate self-tolerance as a cornerstone in the physiology of the immune system. Also, the thymus plays a prominent role in T cell education to neuroendocrine principles. Some self-antigens (oxytocin, neurotensin, insulin-like growth factor 2 [IGF-2]) have been selected to be predominantly expressed in thymic epithelium and to be presented to thymus T cells for educating them to tolerate other antigens related to them. In the insulin family, IGF2 is dominantly transcribed in cortical (c) and medullary (m) thymic epithelial cells (TECs), whereas the insulin gene (INS) is expressed at low level by only a few subsets of mTECs. Intrathymic transcription of both IGF2 and INS is under the control of the autoimmune regulator (Aire) gene. The highest concentrations of IGF-2 in the thymus explain why this peptide is much more tolerated than insulin, and why tolerance to IGF-2 is so difficult to break by active immunization. The high level of tolerance to IGF-2 is correlated to the development of a tolerogenic/regulatory profile when the sequence B11-25 of IGF-2 (homologous to the autoantigen insulin B9-23) is presented to DQ8+ type 1 diabetic patients. Since subcutaneous and oral insulin does not exert any tolerogenic properties, IGF-2 and other thymus self-antigens related to type 1 diabetes (T1D) should be preferred to insulin for the design of novel specific antigen-based preventive approaches against T1D.
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Affiliation(s)
- Vincent Geenen
- University of Liège, Center of Immunology, B-4000 Liège-Sart Tilman, Belgium.
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Hansenne I. Thymic transcription of neurohypophysial and insulin-related genes: impact upon T-cell differentiation and self-tolerance. J Neuroendocrinol 2005; 17:321-7. [PMID: 15869568 DOI: 10.1111/j.1365-2826.2005.01301.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The thymus is the unique lymphoid organ responsible for the generation of a diverse repertoire of T lymphocytes that are competent against non self-antigens while being tolerant to self-antigens. A vast repertoire of neuroendocrine-related genes is transcribed in the nonlymphoid cellular compartment of the thymus (thymic epithelial cells, dendritic cells and macrophages). The precursors encoded by these genes engage two types of interactions with developing T cells (thymocytes). First, they are not processed in a classical neuroendocrine way but as the source of self-antigens that are presented to pre-T cells by the major histocompatibility complex proteins of the thymus. This presentation could be responsible for the establishment of central T-cell self-tolerance to neuroendocrine functions. Second, they also deliver signal ligands that are able to bind to neuroendocrine-type receptors expressed by thymocytes. This interaction activates several types of intracellular signalling pathways implicated in the developmental process of T lymphocytes. Several experimental arguments support a role for thymic dysfunction as a crucial factor in the development of organ-specific autoimmune endocrinopathies, such as 'idiopathic' central diabetes insipidus and type 1 diabetes mellitus. The rational use of tolerogenic neuroendocrine self-antigens for the prevention/treatment of autoimmune endocrinopathies is currently under investigation.
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Affiliation(s)
- I Hansenne
- Liege University, Center of Immunology, Laboratory of Neuroimmune-Endocrinology and Embryology, Institute of Pathology, Liege-Sart Tilman, Belgium.
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10
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Vasopressin and oxytocin. ACTA ACUST UNITED AC 2005. [DOI: 10.1016/s0921-0709(05)80014-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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11
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Guyden JC, Pezzano M. Thymic nurse cells: a microenvironment for thymocyte development and selection. INTERNATIONAL REVIEW OF CYTOLOGY 2003; 223:1-37. [PMID: 12641209 DOI: 10.1016/s0074-7696(05)23001-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Thymic nurse cells (TNCs) represent a unique microenvironment in the thymus for MHC restriction and T cell repertoire selection composed of a cortical epithelial cell surrounding 20-200 immature thymocytes. TNCs have been isolated from many classes of animals from fish to humans. Studies performed using TNC lines showed that TNCs bind viable alphabetaTCRlow CD4(+)CD8(+)CD69(-) thymocytes. A subset of the bound cells is internalized, proliferates within the TNC, and matures to the alphabetaTCRhigh CD4(+)CD8(+)CD69(+) stage, indicative of positive selection. A subset of the internalized population is released while cells that remain internalized undergo apoptosis and are degraded by lysosomes within the TNC. A TNC-specific monoclonal antibody added to fetal thymic organ cultures resulted in an 80% reduction in the number of thymocytes recovered, with a block at the double positive stage of development. Together these data suggest a critical role for TNC internalization in thymocyte selection as well as the removal and degradation of negatively selected thymocytes. Recent studies have shown that in addition to thymocytes, peripheral circulating macrophages are also found within the TNC complex and can present antigens to the developing thymocytes. These circulating macrophages could provide a source of self-antigens used to ensure a self-tolerant mature T cell repertoire. A reduction in TNC numbers is associated with a variety of autoimmune diseases including thyroiditis and systemic lupus erythematosis.
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Affiliation(s)
- Jerry C Guyden
- Department of Biology, The City College of New York, New York, New York 10031, USA
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12
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Hu SB, Zhao ZS, Yhap C, Grinberg A, Huang SP, Westphal H, Gold P. Vasopressin receptor 1a-mediated negative regulation of B cell receptor signaling. J Neuroimmunol 2003; 135:72-81. [PMID: 12576226 DOI: 10.1016/s0165-5728(02)00442-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We report here a study of T and B cell development and function in mice with disruption of the vasopressin receptor 1a (v1a) gene. Loss of the v1a receptor caused a shift from IgM(high)/IgD(high) to the more mature IgM(low)/IgD(high) B cells, a significantly greater extent of splenic B cells proliferation in response to anti-IgM stimulation, and enhanced IgG1 and IgG2b production in response to immune challenge with T-dependent antigen. B-1 cells were increased in v1a(-/-) mice. In contrast, T cell differentiation and activation were normal in v1a(-/-) mice. Our data identify a novel function for v1a in the periphery as a negative regulator of B cell receptor (BCR) signaling. These data suggest that in addition to its other stress-related effects, vasopressin may also serve as a counter-regulatory restraint upon the immune system during fight or flight situations.
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Affiliation(s)
- Shuang-Bao Hu
- Clinical Neuroendocrinology Branch, National Institute of Mental Health, NIH, 10 Center Drive, 10/2D46, Bethesda, MD 20892, USA.
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13
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Pléau JM, Esling A, Geutkens S, Dardenne M, Homo-Delarche F. Pancreatic hormone and glutamic acid decarboxylase expression in the mouse thymus: a real-time PCR study. Biochem Biophys Res Commun 2001; 283:843-8. [PMID: 11350061 DOI: 10.1006/bbrc.2001.4884] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We devised a real-time RT-PCR method for the quantification of preproinsulin 1 and 2, proglucagon, prosomatostatin, and GAD 65 and 67 mRNAs in the thymus, using specific primers and internal probes. Corresponding standard cRNA synthesis and normalization to 18S ribosomal RNA allowed direct quantification. Then, during the first month of life, the expression of each substance of interest was measured in the thymus of NOD mice (a spontaneous model of type 1 diabetes), C57BL/6, BALB/c and lymphocyte-deficient mice (NODscid, NODrag, BALB/cscid and C57BL/6rag). In all mouse thymuses, preproinsulin 1 and GAD 65 were undetectable, preproinsulin 2 and proglucagon showed low expression, whereas that of GAD 67 and somatostatin were high. In 7-day-old mice, GAD 67 and prosomatostatin thymic expressions were lower in NOD than in C57BL/6, and at the same age, the scid mutation but not the rag mutation induced higher expression of all investigated genes compared to control mice. In conclusion, our data allowed the quantification of the expression of pancreatic factors in the mouse thymus. Investigations are underway to quantify, at the cellular level, i.e., in thymic dendritic/macrophage cells, the RNA expression of potential autoantigens, such as preproinsulin 2 and GAD 67.
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Affiliation(s)
- J M Pléau
- CNRS UMR 8603, University of Paris V, Paris, France.
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Geenen V, Martens H, Brilot F, Renard C, Franchimont D, Kecha O. Thymic neuroendocrine self-antigens. Role in T-cell development and central T-cell self-tolerance. Ann N Y Acad Sci 2001; 917:710-23. [PMID: 11268399 DOI: 10.1111/j.1749-6632.2000.tb05435.x] [Citation(s) in RCA: 9] [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
The repertoire of thymic neuroendocrine precursors plays a dual role in T-cell differentiation as the source of either cryptocrine accessory signals in T-cell development or neuroendocrine self-antigens presented by the thymic major histocompatibility complex (MHC) machinery. Thymic neuroendocrine self-antigens usually correspond to peptide sequences highly conserved during the evolution of one family. The thymic presentation of some neuroendocrine self-antigens is not restricted by MHC alleles. Oxytocin (OT) is the dominant peptide of the neurohypophysial family. It is expressed by thymic epithelial and nurse cells (TEC/TNCs) of different species. Ontogenetic studies have shown that the thymic expression of the OT gene precedes the hypothalamic one. Both OT and VP stimulate the phosphorylation of p125FAK and other focal adhesion-related proteins in murine immature T cells. These early cell activation events could play a role in the promotion of close interactions between thymic stromal cells and developing T cells. It is established that such interactions are fundamental for the progression of thymic T-cell differentiation. Insulin-like growth factor 2 (IGF-2) is the dominant thymic polypeptide of the insulin family. Using fetal thymic organ cultures (FTOCs), the inhibition of thymic IGF-2-mediated signaling was shown to block the early stages of T-cell differentiation. The treatment of FTOCs with an mAb anti-(pro)insulin had no effect on T-cell development. In an animal model of autoimmune type 1 diabetes (BB rat), thymic levels of (pro)insulin and IGF-1 mRNAs were normal both in diabetes-resistant and diabetes-prone BB rats. IGF-2 transcripts were clearly identified in all thymuses from diabetes-resistant adult (5-week) and young (2- and 5-days) BB rats. In marked contrast, the IGF-2 transcripts were absent and the IGF-2 protein was almost undetectable in +/- 80% of the thymuses from diabetes-prone adult and young BB rats. These data show that a defect of the thymic IGF-2-mediated tolerogenic function might play an important role in the pathophysiology of autoimmune Type 1 diabetes.
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Affiliation(s)
- V Geenen
- Department of Medicine, Institute of Pathology CHU-B23, Laboratory of Radio-Immunology and Neuroendocrine-Immunology, University of Liège, Belgium.
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Kecha-Kamoun O, Achour I, Martens H, Collette J, Lefebvre PJ, Greiner DL, Geenen V. Thymic expression of insulin-related genes in an animal model of autoimmune type 1 diabetes. Diabetes Metab Res Rev 2001; 17:146-52. [PMID: 11307180 DOI: 10.1002/dmrr.182] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
BACKGROUND Insulin and multiple other autoantigens have been implicated in the pathogenesis of autoimmune type 1 diabetes, but the origin of immunological self-reactivity specifically oriented against insulin-secreting islet beta-cells remains obscure. The primary objective of the present study was to investigate the hypothesis that a defect in thymic central T-cell self-tolerance of the insulin hormone family could contribute to the pathophysiology of type 1 diabetes. This hypothesis was investigated in a classic animal model of type 1 diabetes, the Bio-Breeding (BB) rat. METHODS The expression of the mammalian insulin-related genes (Ins, Igf1 and Igf2) was analysed in the thymus of inbred Wistar Furth rats (WF), diabetes-resistant BB (BBDR) and diabetes-prone BB (BBDP) rats. RESULTS RT-PCR analyses of total RNA from WF, BBDP and BBDR thymi revealed that Igf1 and Ins mRNAs are present in 15/15 thymi from 2-day-old, 5-day-old and 5-week-old WF, BBDR and BBDP rats. In contrast, a complete absence of Igf2 mRNA was observed in more than 80% of BBDP thymi. The absence of detectable Igf2 transcripts in the thymus of BBDP rats is tissue-specific, since Igf2 mRNAs were detected in all BBDP brains and livers examined. Using a specific immunoradiometric assay, the concentration of thymic IGF-2 protein was significantly lower in BBDP than in BBDR rats (p<0.01). CONCLUSIONS The present study suggests an association between the emergence of autoimmune diabetes and a defect in Igf2 expression in the thymus of BBDP rats. This tissue-specific defect in gene expression could contribute both to the lymphopenia of these rats (by impaired T-cell development) and the absence of central T-cell self-tolerance of the insulin hormone family (by defective negative selection of self-reactive T-cells).
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MESH Headings
- Aging
- Animals
- Animals, Newborn
- Diabetes Mellitus, Type 1/genetics
- Diabetes Mellitus, Type 1/immunology
- Disease Models, Animal
- Gene Expression Regulation, Developmental
- Immunity, Innate
- Immunoradiometric Assay
- Insulin/analysis
- Insulin/genetics
- Insulin-Like Growth Factor I/analysis
- Insulin-Like Growth Factor I/genetics
- Insulin-Like Growth Factor II/analysis
- Insulin-Like Growth Factor II/genetics
- Proinsulin/analysis
- Proinsulin/genetics
- RNA, Messenger/genetics
- Rats
- Rats, Inbred BB
- Rats, Inbred WF
- Reverse Transcriptase Polymerase Chain Reaction
- Thymus Gland/growth & development
- Thymus Gland/physiology
- Transcription, Genetic
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Affiliation(s)
- O Kecha-Kamoun
- University of Liège, Department of Medicine & Center of Immunology, Institute of Pathology CHU-B23, B-4000 Liège 1-Sart Tilman, Belgium
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Abstract
We examined the distribution of parvalbumin in the pigeon thymus by light and electron microscopic immunohistochemistry. Tissues were also examined by conventional electron microscopy to determine the ultrastructure of immunoreactive cells. Parvalbumin immunoreaction was located in epithelial cells of the cortex, which formed dense mesh-like structures. Parvalbumin-positive epithelial cells were classified into 2 types. The first comprised elongated cells. In these, the nucleus was spindle-shaped, oval, or triangular, with a slightly irregular contour and contained rich heterochromatin peripherally. The cytoplasm was pale and processes extended laterally or ramified among the surrounding thymocytes. This type of cell formed the majority of immunoreactive cells. The other cell type consisted of polygonal epithelial cells. The nucleus was oval with deep indentations. Euchromatin occupied a large part of the nucleus. The cytoplasm contained numerous cell organelles compared with the elongated type, in particular, electron-dense vacuoles of various sizes and often bundles of tonofilaments. Both types of epithelial cell were interconnected by desmosomes. No secretory granules were found in the cytoplasm of elongated or polygonal cells. These results indicate the presence of heterogeneous group of parvalbumin-immunoreactive epithelial cells and suggest the likelihood of different functional roles for parvalbumin in the pigeon thymus.
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Affiliation(s)
- Y Atoji
- Laboratory of Veterinary Anatomy, Faculty of Agriculture, Gifu University, Japan.
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Kecha O, Martens H, Franchimont N, Achour I, Hazée-Hagelstein MT, Charlet-Renard C, Geenen V, Winkler R. Characterization of the insulin-like growth factor axis in the human thymus. J Neuroendocrinol 1999; 11:435-40. [PMID: 10336724 DOI: 10.1046/j.1365-2826.1999.00343.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The components of the insulin-like growth factor (IGF) axis have been investigated in the normal human thymus. Using ribonuclease protection assays (RPA), IGF-II transcripts were detected in the normal human thymus. By reverse transcriptase polymerase chain reaction (RT-PCR) analyses, promoters P3 and P4 were found to be active in the transcription of IGF2 gene within human thymic epithelial cells (TEC). No IGF-II mRNA could be detected in human lymphoid Jurkat T cells with 30 cycles of RT-PCR. By Northern blot analyses, IGFBP-2 to -6 (but not IGFBP-1) were found to be expressed in TEC with a predominance of IGFBP-4. Interestingly, Jurkat T cells only express IGFBP-2 but at high levels. The type 1 IGF receptor was detected in Jurkat T cells but not in human TEC. The identification of the components of the IGF axis within separate compartments of the human thymus adds further evidence for a role of this axis in the control of T-cell development. The precise influence of thymic IGF axis upon T-cell differentiation and immunological self-tolerance however needs to be further investigated.
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Affiliation(s)
- O Kecha
- Institute of Pathology CHU-B23, Laboratory of Molecular Oncology, University of Liège, Liège, Belgium.
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