Immunometabolism around the Clock

Almost every cell has a molecular clock, which controls gene expression on a 24-h cycle, providing circadian rhythmicity. An example of a circadian behaviour common to most organisms is the feeding/fasting cycle, which shapes whole-body metabolism. However, the exact mechanisms by which the clock controls cellular metabolism have only recently become clear. The molecular clock and related metabolic pathways are also key drivers of immunity. Thus, a natural convergence of circadian biology, metabolism, and immunology has emerged to form a new field that we term ‘circadian immunometabolism’. Expanding our understanding of this field will provide insights into chronic conditions such as obesity, cancer, diabetes, cardiovascular disease, and arthritis. Historically, humans would feed/wake during the daylight hours and fast/sleep during the night. Modern society has changed our behaviours leading to a disruption in our circadian rhythms. Circadian disruption has been associated with obesity, diabetes, cardiovascular disease, arthritis, and cancer. These diseases have an immune and a metabolic element, both systems that are under strong circadian control. Full understanding of these disorders will now require convergence of three fields into a new field, ‘circadian immunometabolism’.Therapeutic targeting of metabolic pathways is emerging as an exciting new prospect for the treatment of chronic inflammatory diseases. Recent advances that now allow us to determine an individual’s ‘body-clock time’ provide new opportunities to further enhance these treatments in line with our circadian rhythms.