CIRCADIAN VARIATION IN FUNCTIONAL POLARIZATION OF MURINE PERITONEAL MACROPHAGES

Aim. This study aimed to investigate the circadian rhythm of the murine peritoneal macrophage (PM) metabolic profile. Methods. The metabolic profile of PM was characterized by phagocytic activity, reactive oxygen species (ROS) generation, and by the expression of phenotypic markers, associated with a pro- and anti-inflammatory metabolic shift. Phagocytosis of FITC-labeled inactivated Staphylococcus aureus, ROS generation, CD80, CD86, and CD206 expression were estimated by flow cytometry at a regular 4h interval over the daily light-dark cycle. Results. The phagocytic index and percentage of ROS-producing PM were found to be lower in the resting phase (ZT4) as compared to the active phase. In contrast, the level of CD86 expression was the highest in the inactive phase (ZT8). There was also a statistically significant peak in the proportion of ROS-producing PM, as well as in the level of ROS production per cell at the time of awakening (ZT12). As opposed to ROS generation, ZT12 was characterized by the lowest level of cell-surface CD206 expression. Conclusions. Our results indicate that there is a circadian rhythm in functional polarization of murine PM with an anti-inflammatory activation state in the resting phase in comparison to the active phase.