Autoimmune Disease Severity Affected by Time of Day

Patients with autoimmune diseases may experience disease severity that fluctuates with the time of day. These underlying factors may influence the response to treatments for these conditions, including multiple sclerosis (MS), according to a new study published by Nature Communications.

Circadian rhythm is important for overall body health in adjusting to the 24-hour planetary cycle, as well as being crucial for numerous biological processes. Maintaining a balanced circadian rhythm has been linked to good health, while a poor balance has been implicated in numerous conditions, such as cancer, diabetes, and autoimmune diseases.

Understanding how the circadian rhythm affects the immune system may inform approaches to drug development for autoimmune conditions, according to the study.

The study authors found that immune response and autoimmunity regulation are different depending on when the response is activated.

They discovered that the master circadian gene, BMAL1, is able to sense and act on time-of-day cues to suppress inflammation in mice models.

However, loss of BMAL1—which spurs autoimmunity during the day instead of night—results in more severe MS in mice, according to the study.

"In the year that the Nobel Prize in Medicine was awarded for discoveries on the molecular mechanisms controlling the circadian rhythm, our exciting findings suggest that our immune system is programmed to respond better to infection and insults encountered at different times in the 24-hour clock,” said researcher Kingston Mills, PhD. “This has significant implications for the treatment of immune-mediated diseases and suggests there may be important differences in time of day response to drugs used to treat autoimmune diseases such as multiple sclerosis."

These findings add to a body of evidence regarding how important the 24-hour cycle is to immunity and overall health, according to the authors.

Despite the positive findings, additional research is needed to determine how to modify the circadian rhythm or time-of-day factors that are needed for optimal immunity, according to the study.

“Our study also shows how disruption of our body clocks, which is quite common now given our 24/7 lifestyle and erratic eating and sleeping patterns, may have an impact on autoimmune conditions,” said researcher Annie Curtis, PhD. "We are really beginning to uncover exactly how important our body clocks are for health and wellbeing."