Circadian Clocks in Mouse and Human CD4+ T Cells

• Published in: PloS one Vol. 6; no. 12; p. e29801
• Main Authors: Bollinger, Thomas, Leutz, Anton, Leliavski, Alexei, Skrum, Ludmila, Kovac, Judit, Bonacina, Luigi, Benedict, Christian, Lange, Tanja, Westermann, Jürgen, Oster, Henrik, Solbach, Werner
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 28.12.2011; Public Library of Science (PLoS)
• Subjects: Animals; Antigens; B cells; Biological clocks; Biology; CD4 antigen; CD4-Positive T-Lymphocytes - metabolism; CD40L protein; Cell culture; Circadian Clocks; Circadian rhythm; Circadian rhythms; Clock gene; CLOCK protein; CLOCK Proteins - metabolism; Cytokines; DNA microarrays; Evolution & development; Fibroblasts; Flow Cytometry; Gene expression; Genes; Hormones; Humans; Hygiene; Immune response; Immune response (cell-mediated); Immune system; Immunology; Immunotherapy; Influenza; Interferon; Interferon-gamma - biosynthesis; Interleukin 2; Interleukin 4; Interleukin-2 - biosynthesis; Interleukin-4 - biosynthesis; Ionomycin; Ionomycin - pharmacology; Laboratory animals; Lymphocyte Activation - drug effects; Lymphocytes; Lymphocytes T; Medicine; Mice; Molecular modelling; NF-κB protein; Oligonucleotide Array Sequence Analysis; Period 2 protein; Proteins; Rheumatoid arthritis; Rodents; Serum-free medium; Studies; T cells; Tetradecanoylphorbol Acetate - pharmacology; Thymus; Time of use; Transcription factors; γ-Interferon; Germany
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0029801

Though it has been shown that immunological functions of CD4+ T cells are time of day-dependent, the underlying molecular mechanisms remain largely obscure. To address the question whether T cells themselves harbor a functional clock driving circadian rhythms of immune function, we analyzed clock gene expression by qPCR in unstimulated CD4+ T cells and immune responses of PMA/ionomycin stimulated CD4+ T cells by FACS analysis purified from blood of healthy subjects at different time points throughout the day. Molecular clock as well as immune function was further analyzed in unstimulated T cells which were cultured in serum-free medium with circadian clock reporter systems. We found robust rhythms of clock gene expression as well as, after stimulation, IL-2, IL-4, IFN-γ production and CD40L expression in freshly isolated CD4+ T cells. Further analysis of IFN-γ and CD40L in cultivated T cells revealed that these parameters remain rhythmic in vitro. Moreover, circadian luciferase reporter activity in CD4+ T cells and in thymic sections from PER2::LUCIFERASE reporter mice suggest that endogenous T cell clock rhythms are self-sustained under constant culture conditions. Microarray analysis of stimulated CD4+ T cell cultures revealed regulation of the NF-κB pathway as a candidate mechanism mediating circadian immune responses. Collectively, these data demonstrate for the first time that CD4+ T cell responses are regulated by an intrinsic cellular circadian oscillator capable of driving rhythmic CD4+ T cell immune responses.