Psychological Stress Stimulates Vascular Inflammatory Responses and Destabilizes Atherosclerotic Plaques as Assessed by High-Speed, High-Resolution Intravital Imaging

Backgrounds: Psychological stress increases leukocyte accumulation within atherosclerotic lesions and exacerbates plaque vulnerability. However, the stress-induced real-time behavior of immune cells in the atheroma has been poorly defined in vivo . Here, we aim to investigate whether stress stimulates the inflammatory leukocyte dynamics in the atherosclerotic plaques and destabilizes the lesions using customized in vivo cell tracking strategies. Methods and Results: We developed a system and motion reconstruction algorithm that can probe and compensate for respiratory and pulsatile movements. Individual leukocytes near the atherosclerotic plaques were imaged in real-time by adapting a custom-built high-speed intravital microscopy system with multiple fluorescence channels. Stress was achieved by immobilization procedures and/or stereotaxic application of stress stimulus onto the brain amygdala. The high spatial and temporal resolution of our real-time cell tracking system allowed clear identification of rhodamine 6G-positive leukocytes in vivo . In the common femoral artery bifurcation of apolipoprotein E knockout mice, white blood cells firmly adhered to the inner layer of the vessel walls while some slowly flowed along the endothelium (Figure). We further demonstrate that the stress increased the rolling and adhesion of inflammatory leukocyte subsets near the atherosclerotic lesions, and enhanced the plaque macrophage activity as assessed by in vivo imaging. Confocal laser scanning microscopy and immunostaining analyses corroborated the in vivo findings that the stress induced the destabilization of the atherosclerotic plaques. Conclusion: Our data show that stress stimulated the dynamics of inflammatory leukocyte subsets in atherosclerotic environments and increased the plaque vulnerability as assessed by the customized high-resolution motion-compensated in vivo imaging strategy.