Inflammation induced disruption in Circadian Rhythm in Pulmonary Endothelial Cells is modulated via Reactive Oxygen Species

Shampa Chatterjee; Yool Lee; Jian Qin Tao; Amita Sehgal; Shaon Sengupta

doi:10.1096/fasebj.2019.33.1_supplement.527.9

Background Circadian rhythms refer to cell autonomous oscillations that occur with a 24‐hr periodicity which are manifest in all cells. The vascular endothelium, a network that integrates biochemical and biophysical signals via the transport of blood, nutrients, inflammatory and pathogenic stimuli, is subject to circadian regulation. While the circadian clock has been characterized in systemic blood vessels and well established to contribute to various inflammatory pathologies associated with the endothelium, the mechanisms of circadian control of endothelial inflammation specifically in pulmonary inflammation is not known. The lung is important in the context of host defense which involves participation of various cell types of the mammalian lung to limit bacterial invasion; however it is the pulmonary endothelium that is the converging site for inflammation after pathogen attack. Investigating the circadian regulation of pulmonary vascular inflammation is thus crucial in understanding if lung infection and inflammation exhibit diurnal variation. We hypothesized that the pulmonary vasculature is under circadian control and that this rhythm is disrupted by inflammatory stimuli via redox mediated processes. Methods Circadian rhythms were monitored in pulmonary artery segments and endothelial cells isolated from mPer2luciferase transgenic mice in presence of an inflammatory stimuli (LPS). Reactive oxygen species (ROS) production in LPS treated cells was measured by fluorescence microscopy using the cell permeant dye CellROX Green. Results We observed that the circadian rhythm of the pulmonary endothelium was disrupted by LPS. To identify the mechanism of this disruption, ROS production in these cells was monitored. At 3 h post LPS treatment, we observed a >3 fold increase in ROS production which further increased to 6 fold by 36 h and returned to baseline values at 72 h. ROS was inhibited by pretreating the cells with the NADPH oxidase 2 (NOX2) inhibitor DPI. Addition of DPI, prior to LPS pretreatment also restored the circadian rhythmicity of the pulmonary endothelium. Conclusion Our data indicate that pro‐inflammatory stimuli can disrupt circadian rhythms in the pulmonary endothelium via NOX2 regulated ROS signaling. We speculate that under inflammatory conditions disrupted circadian rhythms in the pulmonary vascular endothelium contributes to worsening outcomes. Support or Funding Information This work was supported by funding from Howard Hughes Medical Institute (HHMI) to Amita Sehgal. This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .

Inflammation induced disruption in Circadian Rhythm in Pulmonary Endothelial Cells is modulated via Reactive Oxygen Species

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