Circadian Rhythms in Septic Shock Patients
Background: Although intensive efforts to improve diagnosis and therapy of sepsis over the last decade, the mortality of septic shock remains high and causes substantial socioeconomical burden of disease. The function of immune cells is time-of-day-dependent and is regulated by several circadian clock genes. This study aims to investigate whether the rhythmicity of clock gene expression is altered in patients with septic shock.Methods: This prospective pilot study was performed at the
... ed at the university hospital Charité – Universitätsmedizin Berlin, Department of Anesthesiology and Operative Intensive Care Medicine (CCM, CVK). We included 20 patients with septic shock between May 2014 and January 2018, from whom blood was drawn every 4 hours over a 24-hour period to isolate CD14-positive monocytes and to measure expression of 17 clock and clock-associated genes. Of these patients, 3 whose samples expressed fewer than 8 clock genes were excluded from the final analysis. Expression data were compared to data of a healthy study population and a rhythmicity score SP was calculated, which comprises values between -1 (arrhythmic) and 1 (rhythmic). Results: Overall, the rhythmicity scores for septic shock patients were significantly (p < 0.0001) lower (0.23 ± 0.26) compared to the control group (12 healthy young men, 0.70 ± 0.18). 77% of the measured clock genes were classified as having inconclusive rhythms, i.e. neither rhythmic nor arrhythmic. The clock genes NR1D1, NR1D2 and CRY2 were the most rhythmic, while CLOCK and ARNTL were the least rhythmic. In addition, the expression of clock genes CRY1, NR1D1, NR1D2, DBP, and PER2 was suppressed in septic shock patients and CRY2 was significantly upregulated compared to controls.Conclusion: Compared to young healthy men, molecular rhythms in immune cells of septic shock patients were substantially decreased. The decrease in rhythmicity was clock gene-dependent. The loss of rhythmicity and downregulation of clock gene expression might be caused by sepsis and might further deteriorate immune responses and organ injury, but further studies are necessary to understand underlying pathophysiological mechanisms.Clinical trial registered with www.ClinicalTrials.gov (NCT02044575) on 24 January 2014.