Lung Injury in ONcologic Stem cell transplants (LIONS) - PROJECT SUMMARY/ABSTRACT In the United States, > 1500 children undergo hematopoietic cell transplantation (HCT) as life-saving treatment for malignancies, immunodeficiencies, inborn errors of metabolism, and multiple other conditions. HCT requires intensive high-dose chemotherapy and/or radiation followed by an infusion of hematopoietic progenitor cells with the goal of correcting cellular defects, repopulating chemotherapy-ablated marrow, or eradicating malignancy. Survival is limited by the development of pulmonary toxicity, which occurs in up to 40% of pediatric HCT recipients due to infectious and noninfectious inflammation. HCT recipients with lung injury have 40% mortality when invasively ventilated and > 60% mortality if meeting acute respiratory distress syndrome (ARDS) criteria. The molecular pathogenesis of lung injury after HCT is largely unknown, partly due to a lack of well-phenotyped cohorts that examine clinical and biochemical characteristics prior to development of lung injury. Our research group focuses on mechanisms contributing to the development of lung injury, and in a recent comprehensive biomarker analysis of pediatric ARDS we found that nucleosomes, composed of histones and cell-free DNA (cfDNA) released from dying cells, were strongly associated with mortality. Histones and cfDNA have been implicated as damage-associated molecular patterns (DAMPs, endogenous danger signals released that propagate inflammation) and are potential upstream contributors to severe lung injury. In this cohort, 12% of children (and a disproportionate 35% of non-survivors) had undergone HCT and possessed a distinct biomarker profile, with elevated nucleosomes, histones, and cfDNA at ARDS onset. Preliminary interrogation of the larger plasma proteome and the cfDNA methylome also revealed targetable pathways warranting focused investigation. Overall, our clinical, proteomic, and cfDNA characterization of pediatric ARDS suggested that the molecular signature associated with HCT was also associated with higher mortality. Therefore, we propose the Lung Injury in ONcologic Stem cell transplants (LIONS) study in 400 subjects undergoing HCT at the Children’s Hospital of Philadelphia. LIONS is a prospective longitudinal cohort study, with serial plasma collection pre-HCT and immediately post-HCT (between day -2 to +20 of HCT) that aims to characterize the molecular changes leading to lung injury. We hypothesize that elevated DAMPs pre- and post- HCT predict subsequent lung injury, and that subjects who develop lung injury have a distinct molecular profile. Aim 1 tests the utility of nucleosomes, and their component histones and cfDNA, to predict lung injury post- HCT. In Aim 2, we leverage novel nanoparticle-enriched mass spectrometry to perform deep unbiased proteomics to characterize the molecular signature of subjects that develop lung injury. Finally, in Aim 3 we characterize the contribution of cell-specific cfDNA, and of recipient-derived cfDNA in allogeneic HCTs, to the development of lung injury. LIONS is the first necessary step towards identifying the molecular signature and tissue targets of lung injury post-HCT, which remains a condition with high mortality and no directed therapies.
