Molecular and morphometric imaging of coagulation and inflammation in pulmonary embolism pathogenesis

PROJECT SUMMARY Pulmonary Embolism (PE) urgently requires improved diagnostic and therapeutic strategies to minimize both acute complications resulting in hemodynamic shock and late complications encompassing possible progressive pulmonary fibrosis, hypertension, and recurrent PE. Currently, fibrinolysis therapy of all PE does not provide an

overall net clinical benefit due to the increased risk of hemorrhagic stroke and fatal bleeding, aside from the potential for unsuccessful fibrinolysis. To more accurately stratify and prognose intermediate-risk and low-risk PE patients, a detailed understanding of the consequences of emboli composition, including its age, burden,

relevant cellular components, and post-PE inflammatory milieu, is needed. To address these unmet needs, this proposal will utilize a novel murine model of PE in which the thrombi are formed in vivo in the deep veins of mice. This model allows for direct control over thrombus age and size and the inclusion of the biological milieu during

thrombogenesis and aging. These thrombi are then embolized into the lung, resulting in PE. This model has demonstrated a resident time of these emboli to be greater than 30 days, unlike previous published murine models with emboli residence times up to 48 hours. To investigate the inflammatory and fibrotic response to PE

insult, we will utilize noninvasive longitudinal multiplexed molecular imaging evaluating specific agents for neutrophils, macrophages, platelets, activated endothelial, epithelial, fibroblasts, type 1 collagen, and thrombin activity. Translationally, we will quantify fibrin changes in various aged emboli pre- and post-fibrinolysis therapy

and its downstream effects on PE-induced inflammation and pulmonary fibrosis. Uniquely, this PE model allows for the application of single nucleus molecular profiling across the proposal to examine the differences in molecular signatures, cell composition, and cell-cell interactions associated with lung lobes with PE and those

lobes without PE from the same lung. This is important in uncovering the effects of PE-induced inflammation and fibrosis that may drive the development of late PE sequelae, such as CTEPH and pulmonary hypertension. Clinically translational imaging readouts tracking pulmonary artery pressures and right heart function in relation

to emboli size, age, and location will be correlated. Completion of the proposed work will provide a longitudinal understanding of the influence of emboli age and size will be reported. Translation of these results may help stratify PE beyond the acute high-low risk. It may help identify patients at a higher risk for late PE syndrome or

recurrent PE and highlight the usefulness of molecular imaging in the clinic, allowing for more bench-to-bedside translation of preclinical molecular imaging agents.