The Circadian Clock and the Immune Response

The body's protection against infections and other external substances is the immune system. The circadian clock regulates the development of white blood cells, which are crucial for battling infections. Additionally, it controls the release of hormones like cortisol, which is crucial for the immunological response.

The article "The circadian clock influences T cell responses to vaccination by regulating dendritic cell antigen processing" shows the effect on the immune system from the biological clock. The circadian 24-hour biological clock affects how the immune system reacts to vaccines, according to research from RCSI University of Medicine and Health Sciences. The study, published in Nature Communications, looked at the changes occurring in the mitochondria of a crucial immune cell involved in the vaccine response. It may be used to alter the formulation and timing of future vaccines to increase their efficacy.

Dendritic cells play a crucial role in processing and presenting antigens to naive T-cells, which activates adaptive immunity. They demonstrate that immunizing mice during their rest phase rather than their active phase results in larger T-cell responses. Numerous components of immunity are known to be regulated by circadian rhythms, however, it is still unclear how dendritic cell activity is affected. They find that antigen processing has a circadian rhythm that is regulated by the Bmal1 molecular clock gene and that is synchronized with rhythms in mitochondrial morphology and metabolism. They may restore the circadian deficit in antigen processing and establish a mechanistic connection between mitochondrial morphology and antigen processing by using Mdivi-1, a substance that encourages mitochondrial fusion. Furthermore, they discover that the circadian regulation of antigen processing depends critically on variations in mitochondrial Ca2+. According to their research, cyclic variations in mitochondrial calcium that are linked to changes in mitochondrial morphology regulate how antigens are processed.

In "Circadian programming of the ellipsoid body sleep homeostat in Drosophila," researchers suggest that sleep deprivation is regulated at the protein level and not gene level in fruit flies for quality of sleep and circadian time, not sleep deprivation, drives differential gene expression in R5 neurons. It could be the same process for fruit flies to regulate their immune response.

RCSI. "New research explains how our body clock influences vaccine responses." ScienceDaily. ScienceDaily, 5 December 2022. <www.sciencedaily.com/releases/2022/12/221205104251.htm>.

Cervantes-Silva, M.P., Carroll, R.G., Wilk, M.M. et al. The circadian clock influences T cell responses to vaccination by regulating dendritic cell antigen processing. Nat Commun 13, 7217 (2022). https://doi.org/10.1038/s41467-022-34897-z.

Tomas Andreani, Clark Rosensweig, Shiju Sisobhan, Emmanuel Ogunlana, William Kath, Ravi Allada (2022) Circadian programming of the ellipsoid body sleep homeostat in Drosophila eLife 11:e74327. https://doi.org/10.7554/eLife.74327.