How microbes, the immune system, and the body’s internal clock interact

The circadian clock influences host immune responses and microbial interactions throughout the day-night cycle.

• Circadian rhythms synchronize immune cell functions with environmental light cycles.
• Host immunity varies in effectiveness against pathogens depending on the time of day.
• The circadian clock impacts the development and movement of immune cells.
• There is a two-way communication between the circadian clock and the microbiota.
• Microbial populations affect the regulation of host immunity and metabolic processes linked to the circadian clock.

Simplified