Body clock found to affect the immune system
New research has suggested that the time of the day could be an important factor in the risk of getting an infection.
Researchers from Yale University School of Medicine have shown how a protein in the immune system was affected by changes in the chemistry of the body through the day. Plants, animals and even bacteria go through a daily 24-hour routine, known as a circadian rhythm. This can be fairly easily disturbed, hence we can suffer from conditions like jetlag. It has been known that there are variations in the immune system throughout the day, but the details remain uncertain.
These new findings, published in the journal ‘Immunity’, appear to prove that the time of an infection alters its severity. The researchers were investigating one of the proteins involved in the detection process – Toll-like receptor nine (TLR9), which can spot DNA from bacteria and viruses. Through experiments on mice, the scientists showed that the amount of TLR9 produced and the way it functioned was controlled by the body clock and varied through the day. Therefore, immunising mice at the peak of TLR9 activity improved the immune response.
It is known that humans with sepsis (blood poisoning) are at a greater risk of death between 02:00 and 06:00. When testing the mice, the severity of sepsis depended on the time of day infection started and coincided with changes in TLR9 activity.
Prof Erol Fikrig, who conducted the study, said they had found a “direct molecular link between circadian rhythms and the immune system, [which could have] important implications for the prevention and treatment of disease. It does appear that disruptions of the circadian clock influence our susceptibility to pathogens.”
The implications for healthcare could be that drugs need to be given at certain times of day in order to make them more effective, or drugs could be made which actually target the body clock to put the immune system into its most active phase.
Dr Akhilesh Reddy, who is researching circadian rhythms at the University of Cambridge, has added that drug companies were “all switching onto this” and were “now screening drugs at different times of the day.” He concludes that the body clock could have a impact on medicine within the next decade.
Source – BBC News 17 Feb 12
