Circadian rhythm is expressed in most organisms, and many functions and parameters in the immune system are associated with time-of-day. However, it is largely unknown if local circadian clocks in immune cells directly control physiological outcomes. We hypothesized that a circadian clock in murine bone marrow derived mast cells (BMMCs) modulates IgE-dependent activation in vitro. Mature BMMCs, grown from bone marrow of C57BL/6 mice, were synchronized with serum rich media (50% horse serum). Total RNA was harvested from BMMCs at 4 h intervals for up to 72 h following synchronization and expression of circadian genes (mPer1, mPer2, Bmal1, Rev-erbα, and Dbp) was measured by quantitative PCR. Serum shock synchronized expression of circadian genes (mPer2, Bmal1, Rev-erbα, and Dbp) in BMMCs. Synchronized BMMCs stimulated via the high affinity IgE receptor (FcεRI) at different time intervals display circadian rhythms in IL-13 and IL-6 mRNA expression. The expression of fcer1a gene and FcεRIα protein displayed a circadian pattern following serum shock, with mean periods of 18.9 and 28.6 h, respectively. These results demonstrate that synchronized BMMCs provide an in vitro model to study circadian mechanism(s) associated with allergic disease and that circadian oscillation of cytokine production following IgE-dependent activation is at least in part due to circadian oscillation of FcεRIα.
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