Biological Rhythm Arterial calcification is influenced by our internal clock

Biological rhythm with significant influence on arteriosclerosis

Calcification of the arteries is a very widespread complaint that in the worst case can have fatal consequences. The changes in the blood vessels are subject to fluctuations in time of day, report scientists from the Ludwig-Maximilians-Universität München (LMU). In a recent study, the researchers found that the so-called circadian rhythm has a significant impact on atherosclerosis.

According to the researchers, the biological rhythm influences the extent of deposits on the vessel walls, which could also be used for therapeutic purposes. The treatment could therefore focus on the time of day, in which a particularly large number of deposits are formed. In the opinion of the researchers, this would allow for decisive improvements in therapeutic approaches. The researchers published their study results in the journal "Cell Metabolism".

What effect does biorhythm have on arteriosclerosis??

For the first time, the team led by Professor Oliver Söhnlein from the Institute for Prophylaxis and Epidemiology of Circulatory Diseases at the LMU in his latest study was able to demonstrate the influence of the biological rhythm in atherosclerosis. This internal clock controls all the vital functions in the body, from the body temperature to the blood pressure to the release of certain enzymes that are subject to daily rhythm fluctuations, explain the scientists. The circadian rhythm also has a considerable influence on the vascular disease of atherosclerosis. The condition is commonly known as arteriosclerosis and can ultimately lead to a heart attack or stroke.

Molecular mechanisms examined

The scientists investigated the molecular mechanisms in atherosclerosis, which lead to the deposits in the inner vessel wall of the arteries. Here, cells of the immune system migrate from the blood to the damaged area and attract more and more signal via signal substances, until finally the immune response derailed, explain the experts. This atherosclerotic inflammation develops over years, although the recruitment of the cells is subject to daily rhythmic fluctuations. Such fluctuations, the researchers could now prove in the mouse model.

Time shift in leukocyte activity

"At certain times of the day, three times as many leucocytes are on the way to the site of inflammation as usual," reports Prof. Söhnlein of the results of the study. However, her rhythm was shifted by about twelve hours from its occurrence in the microcirculation in the veins. Exactly this shift between the two vascular systems is interesting from a therapeutic point of view, according to the researchers. Because the recruitment of white blood cells in the microcirculation is important in acute infections such as septicemia, so ideally the recruitment of the immune cells should be maintained in the microcirculation, while it is stopped in the atherosclerotic inflammation.

Does the arteriosclerosis stop??

The researchers have not only identified the molecular mechanism in their investigations to stop the recruitment of leukocytes, but have already successfully tested it. Blockade of the enzyme CCL2 prevented it from emitting signals that would cause further leukocytes, the researchers report. By taking into account the daily rhythmic fluctuations, it was also possible to stop the recruitment only to the atherosclerotic sites of inflammation, while the microcirculation was not impaired.

Further investigations planned

"Our study shows how circadian patterns can be used for temporally targeted therapeutic intervention," emphasizes Prof. Söhnlein. In further investigations it must now be clarified to what extent circadian rhythms contribute to destabilization in advanced atherosclerosis. Researchers are also increasingly planning to investigate the circadian regulation of processes in the atherosclerotic deposition itself, such as the question of whether cell death is controlled circadian. (Fp)