Immune cells that allow the elimination of beta-amyloid protein, linked to Alzheimer’s disease, can be disrupted when sleep cycles are not respected.
- The circadian rhythm corresponds to the alternation between phases of wakefulness and sleep during a 24-hour cycle.
- Alzheimer’s disease is linked to the formation of amyloid plaques in the brain.
- The elimination of the protein is carried out thanks to immune cells, dependent on the circadian rhythm.
Restless, too short or disturbed nights are detrimental to well-being and health. Poor quality sleep can increase the risk of depression, obesity or hypertension. But it is also linked to Alzheimer’s disease. In the review PLOS Geneticsscientists explain that disorders of the circadian rhythm, or our biological clock, are associated with Alzheimer’s disease.
Immune cells that follow our circadian rhythm
In their study, they worked on a molecular mechanism potentially responsible for this link between Alzheimer’s disease and circadian rhythms. They measured the activity of immune cells responsible for eliminating so-called beta-amyloid proteins that accumulate in the form of plaques in the brains of people with Alzheimer’s disease. Using cells grown in the lab, they discovered that they shed amyloid-beta protein in a daily cycle, controlled by circadian rhythms. When the cells no longer followed these rhythms, the cycles of elimination disappeared. According to their findings, this is linked to molecules of another protein, called heparan, which is found on the surface of these cells. Its functioning is also based on circadian rhythms, and previous studies have shown that it is involved in the elimination of beta-amyloid proteins.
A new avenue of treatment
If this study provides information on the origins of the disease and certain symptoms, because sick people often suffer from sleep disorders several years before the onset of the disease, it also offers new avenues for reflection concerning its treatment. “Understanding how our circadian rhythms can regulate cell surface heparan levels to control beta-amyloid accumulation may lead to the development of chronotherapies that alleviate symptoms of Alzheimer’s disease as well as other inflammatory diseases.”, says Jennifer Hurley, lead author of the study. The idea would be to restart the daily cycle of amyloid-beta protein elimination to prevent the disease from progressing, or getting worse.