Intestinal Infection: Time of Day Matters

You are probably aware that our bodies have an internal “body clock” that affects daily physiological functions. This clock is known as circadian rhythm and is affected by external cues such as daylight. But, did you also know that much of your immune system is also influenced by circadian rhythms?

A recent study published in Proceedings of the National Academy of Sciences tested the role of the circadian clock in acute infections. Specifically, mice were infected with salmonella bacteria at one of two time points: 10 am or 10 pm. For a mouse in this study, 10 am represents the early rest phase and 10 pm represents the early active phase. Three days post-infection, mice injected during their early rest period (10 am) developed significantly higher colonization of bacteria and an overall increased inflammatory response.

The authors show a weakened immune response in the rest phase of the circadian clock, resulting from changes in specific gene expression in the cecum of mice throughout a 24-hour cycle.

According to the authors, this is the first time that vulnerability to infection and circadian clock have been clearly linked. This work may help explain why susceptibility to infectious disease can be increased in people with disrupted sleep patterns. It may also help to target specific treatments and better inform treatment strategies.

What do you think?

How would this work in nocturnal animals compare to possible results in humans?

Further Reading:

Bellet MM, Deriu E, Liu JZ, Grimaldi B, Blaschitz C, Zeller M, Edwards RA, Sahar S, Dandekar S, Baldi P, George MD, Raffatellu M, Sassone-Corsi. Circadian clock regulates the host response to Salmonella. Proc Natl Acad Sci USA. 2013 May 28. [Epub ahead of print]