Abstract
The roles that thymus cytokines might play in regulating thymic atrophy are not known. Reversing thymic atrophy is important for immune reconstitution in adults. We have studied cytokine mRNA steady-state levels in 45 normal human (aged 3 days to 78 years) and 34 myasthenia gravis thymuses (aged 4 to 75 years) during aging, and correlated cytokine mRNA levels with thymic signal joint (sj) TCR delta excision circle (TREC) levels, a molecular marker for active thymopoiesis. LIF, oncostatin M (OSM), IL-6, M-CSF, and stem cell factor (SCF) mRNA were elevated in normal and myasthenia gravis-aged thymuses, and correlated with decreased levels of thymopoiesis, as determined by either decreased keratin-positive thymic epithelial space or decreased thymic sjTRECs. IL-7 is a key cytokine required during the early stages of thymocyte development. Interestingly, IL-7 mRNA expression did not fall with aging in either normal or myasthenia gravis thymuses. In vivo administration of LIF, OSM, IL-6, or SCF, but not M-CSF, i.p. to mice over 3 days induced thymic atrophy with loss of CD4+, CD8+ cortical thymocytes. Taken together, these data suggest a role for thymic cytokines in the process of thymic atrophy.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adolescent
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Adult
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Aged
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Aging / genetics
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Aging / immunology*
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Animals
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Atrophy
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Child
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Child, Preschool
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Epithelial Cells / chemistry
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Epithelial Cells / metabolism
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Epithelial Cells / pathology
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Extracellular Space / chemistry
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Extracellular Space / metabolism
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Female
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Gene Expression Regulation / immunology
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Gene Rearrangement, delta-Chain T-Cell Antigen Receptor
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Growth Inhibitors / administration & dosage
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Growth Inhibitors / biosynthesis
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Growth Inhibitors / genetics*
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Humans
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Infant
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Infant, Newborn
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Injections, Intraperitoneal
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Interleukin-6 / administration & dosage
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Interleukin-6 / biosynthesis
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Interleukin-6 / genetics*
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Leukemia Inhibitory Factor
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Lymphokines / administration & dosage
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Lymphokines / biosynthesis
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Lymphokines / genetics*
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Macrophage Colony-Stimulating Factor / administration & dosage
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Mice
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Mice, Inbred BALB C
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Middle Aged
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Myasthenia Gravis / immunology
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Myasthenia Gravis / metabolism
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Myasthenia Gravis / physiopathology
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Oncostatin M
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Peptides / administration & dosage
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Peptides / genetics*
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RNA, Messenger / biosynthesis*
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Stem Cell Factor / administration & dosage
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Stem Cell Factor / biosynthesis
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Stem Cell Factor / genetics*
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Thymus Gland / chemistry
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Thymus Gland / immunology
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Thymus Gland / metabolism*
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Thymus Gland / pathology*
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Transforming Growth Factor beta / genetics
Substances
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Growth Inhibitors
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Interleukin-6
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LIF protein, human
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Leukemia Inhibitory Factor
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Lif protein, mouse
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Lymphokines
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OSM protein, human
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Osm protein, mouse
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Peptides
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RNA, Messenger
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Stem Cell Factor
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Transforming Growth Factor beta
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Oncostatin M
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Macrophage Colony-Stimulating Factor