Apart from appetite, sleep or body temperature, the internal clock regulates the body’s immune response. This is revealed by a study published by researchers based in Canada. This work could in particular make it possible to improve immunotherapy strategies in the treatment of cancers.
We sometimes forget it, but it is our circadian clock – also called “biological” or “internal” – which is at the head of our body. Nestled in the center of our brain, in the hypothalamus, it is made up of two suprachiasmatic nuclei which each contain around 10,000 neurons. The latter are at the origin of an electrical activity oscillating over 24 hours, controlled by the cyclic expression of about fifteen “clock” genes.
Through direct or indirect messages, the suprachiasmatic nuclei regulate various functions of our organism, such as body temperature, appetite, and sleep. This cycle allows the human body to adapt to other cycles: environmental changes, such as the seasons, and the transition from day to night.
The essential role of the biological clock
If it is undeniable that our internal clock controls multiple aspects of our physiology, its role would be even more important: according to a study published in the journal Proceedings of the National Academy of Sciences of the United States of Americaour biological clock influences the effectiveness of our immune response (i.e. how effectively our immune system triggers a disease).
The six researchers, based in Canada, focused on the role of the circadian clock in regulating CD8 T cells, a class of leukocytes that play an important role in the secondary immune response as they destroy infected cells in the case of cancer or infection.
“The strength of the CD8 T cell response varies by time of day”
“Using a vaccine model in mice, we observed that after vaccination, the strength of the CD8 T cell response varied depending on the time of day, explains Nicolas Cermakian, one of the researchers, in a article published on the website of the Canadian university McGill. Conversely, in mice that lacked the clock gene in their CD8 T cells, this circadian rhythm was abolished and the response to the vaccine was diminished during the day.
It had previously been demonstrated that T cells react more or less strongly to the presence of a foreign body depending on the time of day, but the role of the circadian clock in this phenomenon remained unknown.
“Improving vaccination strategies as well as cancer immunotherapy”
“Identifying the mechanisms by which the biological clock modulates the T cell response will help us better understand the processes that regulate optimal T cell responses,” said Nathalie Labrecque, one of the study’s authors. will contribute to improving vaccination strategies as well as cancer immunotherapy”.
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