High dimensional atlas of circulating neutrophils as reporters of solid organ functional status Chronic solid organ diseases (CSODs) collectively account for the majority of deaths in the United States. A central goal in modern medicine is to improve our ability to predict and detect CSODs in order to initiate successful therapeutic interventions early or to install appropriate early preventive measures. Several approaches have been devised to facilitate early detection of disease, including genetic testing and screening modalities such as imaging and laboratory tests. However, considerable number of CSODs lay silent and escape even the most watchful clinical eyes, only appearing when it is too late to reverse the pathophysiology of the disease. The identification of a non-invasive, accessible, sensitive, and comprehensive reporter system that simultaneously appraises the status of many solid organs would widen the window of opportunity for therapeutic intervention before overt disease occurs. Cellular injury and damage, which precede all organ-based disease, trigger an immune response that may be transcriptionally encoded into surveilling immune cells. The blood circulation accesses all solid organs and therefore provides an excellent portal into organ status. Specifically, neutrophils, the most abundant immune cells in humans, infiltrates nearly all organs under homeostasis. Contrary to their reputation as mere non-specific anti-microbial combatants, neutrophils have evolved as heterogeneous, functionally versatile cells that participate in organ homeostasis and mediate CSODs. The advent of high-dimensional approaches such as single-cell cytometry by time of flight (CyTOF) and single-cell RNA sequencing (scRNA-seq) have revealed numerous previously unknown neutrophil subpopulations with distinct transcriptional features. Moreover, tissue-infiltrating neutrophils assume specific organ-defined signatures. Unique from other immune cells, neutrophils do not establish permanent residence in the tissues they sojourn. This feature coupled with the neutrophils' short half-life yet significant transcriptional malleability renders them excellent candidates to serve as sentinels and reporters of organ status. In short, neutrophils that have infiltrated organs potentially return into the systemic circulation with vital organ-specific codes that may predict homeostatic state compared to perturbed, diseased states. This proposal will capitalize on these features of neutrophils to create a comprehensive atlas of their transcriptomics signatures, such that any tissue-specific dysregulation would be detected as an alteration in these transcriptional signatures. If successful, we envision a clinical world where blood analysis of neutrophil transcriptomic features would unveil lurking disease far before symptoms develop, prompting early intervention.

Project Narrative Our ability to predict disease in solid organs is markedly hampered by the clinical impracticability of routine biopsies for several organs. Here, we propose the use of a high dimensional atlas of circulating neutrophil transcriptomics as predictor of disease before signs and symptoms develop.