title: Commensal bacteria regulate thymic Aire expression.
abstract: Commensal bacteria in gastrointestinal tracts are reported to function as an environmental factor to regulate intestinal inflammation and immune responses. However, it remains largely unknown whether such bacterial function exerts any effect on other immune organs distant from the intestine. In this study, the influence of commensal bacteria in the thymus, where T cell lineages develop into mature type to form proper repertoires, was investigated using germ-free (GF) mice and Nod1-deficient mice lacking an intracellular recognition receptor for certain bacterial components, in which a commensal bacterial effect is predicted to be less. In both mice, there was no significant difference in the numbers and subset ratios of thymocytes. Interestingly, however, autoimmune regulator (Aire) expression in thymic epithelial cells (TECs), main components of the thymic microenvironment, was decreased in comparison to specific pathogen-free (SPF) mice and Nod1 wild-type (WT) mice, respectively. In vitro analysis using a fetal thymus organ culture (FTOC) system showed that Aire expression in TECs was increased in the presence of a bacterial component or a bacterial product. These results suggest that through their products, commensal bacteria have the potential to have some effect on epithelial cells of the thymus in tissues distant from the intestine where they are originally harbored.
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Nakajima
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Negishi
authors.affiliation: Department of Pathology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hiromichi
authors.initials: H
authors.lastname: Tsurui
authors.affiliation: Department of Pathology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Naomi
authors.initials: N
authors.lastname: Kadowaki-Ohtsuji
authors.affiliation: Atopy (Allergy) Research Center, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Maeda
authors.affiliation: Yakult Central Institute for Microbiological Research, Kunitachi, Tokyo, Japan.
authors.forename: Masanobu
authors.initials: M
authors.lastname: Nanno
authors.affiliation: Advanced Research Center for Genome Super Power, Keio University, Tsukuba, Ibaraki, Japan.
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Yamaguchi
authors.affiliation: Advanced Research Center for Genome Super Power, Keio University, Tsukuba, Ibaraki, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Shimizu
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Hideo
authors.initials: H
authors.lastname: Yagita
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan; Atopy (Allergy) Research Center, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Ko
authors.initials: K
authors.lastname: Okumura
authors.affiliation: Department of Immunology, Juntendo University School of Medicine, Bunkyo-ku, Tokyo, Japan.
authors.forename: Sonoko
authors.initials: S
authors.lastname: Habu
mesh_terms: D000818:Animals; D041981:Gastrointestinal Tract / Q000382:microbiology; D015870:Gene Expression; D005856:Germ-Free Life; D008807:Mice, Inbred BALB C; D018345:Mice, Knockout; D064307:Microbiota / Q000502:physiology*; D060168:Thymocytes / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000378:metabolism*; D046509:Tissue Culture Techniques; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D000096927:AIRE Protein
chemical_list: D014157:Transcription Factors; D000096927:AIRE Protein