Circadian clocks in mouse and human CD4+ T cells.
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.
Institute of Medical Microbiology and Hygiene, University of Lübeck, Lübeck, Germany. Thomas.Bollinger@uk-sh.de
Thomas
T
Bollinger
Anton
A
Leutz
Alexei
A
Leliavski
Ludmila
L
Skrum
Judit
J
Kovac
Luigi
L
Bonacina
Christian
C
Benedict
Tanja
T
Lange
Jürgen
J
Westermann
Henrik
H
Oster
Werner
W
Solbach
D000818:Animals; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism*; D056926:CLOCK Proteins / Q000378:metabolism*; D057906:Circadian Clocks; D005434:Flow Cytometry; D006801:Humans; D007371:Interferon-gamma / Q000096:biosynthesis; D007376:Interleukin-2 / Q000096:biosynthesis; D015847:Interleukin-4 / Q000096:biosynthesis; D015759:Ionomycin / Q000494:pharmacology; D008213:Lymphocyte Activation / Q000187:drug effects; D051379:Mice; D020411:Oligonucleotide Array Sequence Analysis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D007376:Interleukin-2; D015847:Interleukin-4; D015759:Ionomycin; D007371:Interferon-gamma; D056926:CLOCK Proteins; D013755:Tetradecanoylphorbol Acetate