Endothelial glycocalyx shedding in septic injury

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PROJECT SUMMARY/ABSTRACT Sepsis is a critical illness arising from dysregulated host response to infection where invading pathogens elicit an adverse systemic inflammatory response that affects multiple organs and tissues. Currently, there are limited therapies that effectively treat this disease. The overarching goal of our work is to identify new molecular targets that can potentially serve as diagnostics or therapeutics for prevention and treatment of sepsis. This project focuses on glycocalyx shedding as not merely a consequence, but a critical cause, of inflammatory injury. Specifically, we hypothesize that bacterial infection promotes disintegrin metalloprotease (ADAM) upregulation and activity to shed glycocalyx molecules on endothelial surface and release their fragments into the circulation, which act as inflammatory signals to mediate microcirculatory dysfunction and barrier leakage by triggering endothelial cytoskeleton-junction responses. This novel concept will be tested by completing two aims: Aim 1 to characterize the molecular property of glycocalyx shedding products and function in microvascular inflammation during sepsis; Aim 2 to elucidate the molecular mechanisms of endothelial glycocalyx shedding and barrier injury. We propose a multifaceted approach based on an innovative design that integrates peptidomics, proteomics and nanotechnology with multispectral photoacoustic tomography, super-resolution confocal and 3D intravital microscopic imaging. Functionally viable human lungs and microvessels serve as the primary models, which are complemented by animal models and cell experiments. Microvascular barrier structure and function will be examined in-depth at the organ, tissue and cell levels under pathophysiologically relevant conditions of bacterial infection. We expect to gain novel insights that will not only fill the knowledge gaps in understanding the molecular mechanisms of septic injury, but also contribute to the development of effective therapeutics against infectious diseases. The proposed human organ studies further highlight the translational values of our work.