title: Inverse associations between obesity indicators and thymic T-cell production levels in aging atomic-bomb survivors.
abstract: Reduction of the naive T-cell population represents a deteriorating state in the immune system that occurs with advancing age. In animal model studies, obesity compromises the T-cell immune system as a result of enhanced adipogenesis in primary lymphoid organs and systemic inflammation. In this study, to test the hypothesis that obesity may contribute to the aging of human T-cell immunity, a thousand atomic-bomb survivors were examined for obesity status and ability to produce naive T cells, i.e., T-cell receptor excision circle (TREC) numbers in CD4 and CD8 T cells. The number of TRECs showed a strong positive correlation with naive T cell numbers, and lower TREC numbers were associated with higher age. We found that the TREC number was inversely associated with levels of obesity indicators (BMI, hemoglobin A1c) and serum CRP levels. Development of type-2 diabetes and fatty liver was also associated with lower TREC numbers. This population study suggests that obesity with enhanced inflammation is involved in aging of the human T-cell immune system. Given the fact that obesity increases the risk of numerous age-related diseases, attenuated immune competence is a possible mechanistic link between obesity and disease development among the elderly.
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Kengo
authors.initials: K
authors.lastname: Yoshida
authors.affiliation: Department of Statistics, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Nakashima
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Yoshiko
authors.initials: Y
authors.lastname: Kubo
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Mika
authors.initials: M
authors.lastname: Yamaoka
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Junko
authors.initials: J
authors.lastname: Kajimura
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Seishi
authors.initials: S
authors.lastname: Kyoizumi
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Hayashi
authors.affiliation: Department of Clinical Studies, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Waka
authors.initials: W
authors.lastname: Ohishi
authors.affiliation: Department of Radiobiology/Molecular Epidemiology, Radiation Effects Research Foundation, Hiroshima, Japan.
authors.forename: Yoichiro
authors.initials: Y
authors.lastname: Kusunoki
mesh_terms: D000368:Aged; D000375:Aging / Q000276:immunology*; D054042:Bombs; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology; D005260:Female; D006801:Humans; D018655:Lymphocyte Count; D008297:Male; D015999:Multivariate Analysis; D009765:Obesity / Q000276:immunology* / Q000473:pathology*; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D012044:Regression Analysis; D017741:Survivors; D013601:T-Lymphocytes / Q000473:pathology*; D013950:Thymus Gland / Q000473:pathology*
chemical_list: D011948:Receptors, Antigen, T-Cell