New insights into how the circadian clock influences T cell responses to vaccination

Research by RCSI University of Medicine and Health Sciences has provided new insights into the mechanism behind how our circadian 24-hour body clock influences our immune response to vaccines, depending on the time of day.

The paper published in Nature Communications examined the changes taking place in the mitochondria of a key immune cell involved in the vaccine response and could help improve the design and timing of administration of future vaccines to maximize effectiveness.

It had been previously found that humans mount a greater response to certain vaccines depending on the time of day at which the vaccine is administered, however the reason behind this wasn't clearly understood. This research has uncovered that our circadian clock is changing the shape of mitochondria within dendritic cells. The variations in the structure of mitochondria influence how well dendritic cells function throughout the day.

Our discovery has shed light on a crucial aspect of our body's response to vaccination and highlights the importance of circadian rhythms in immunity. We can apply this understanding in vaccine development to ensure we receive the maximum benefits from vaccination."

Annie Curtis, Research Author, Professor, School of Pharmacy and Biomolecular Sciences at RCSI

The circadian clock within dendritic cells is controlling whether mitochondria form one of two shapes either long strings, 'networked', or broken into small punctate pieces. It is within the networked formation that vaccination is most effective as dendritic cells have a better ability break up the vaccine into small pieces for interaction with our immune cells (T cells). Within the study, researchers used an approach to induce the networked phase which could have implications in vaccine design allowing us to optimize our immune response, irrespective of time of day.

The majority of this study was supported through funding provided by the Science Foundation Ireland Career Development Award (CDA) program by the Irish Research Council through a Laureate Award and an RCSI Strategic Academic Recruitment Program (StAR) award. Further support was provided by a Conacyt grant, a SFI Investigator Award and a European Research Council Consolidator Award.