The Role of Extracellular Histones and Neutrophil Extracellular traps in Necrotizing Enterocolitis

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Project Summary Necrotizing enterocolitis (NEC) is the most common surgical emergency in the neonatal period. Despite advances in medical care, mortality and morbidity caused by NEC has not changed in the past three decades. This is largely due to a poor understanding of the complex pathogenesis of this multifactorial diseases and by the lack of specific therapies. We have preliminary data showing the histones-DNA complexes are elevated in premature infants with NEC. Studies from our lab and others identified extracellular histones as major mediators in many pathological conditions including sepsis, thrombosis, and trauma. In humans and animal models of sepsis, high levels of histones-DNA correlate with organ failure and mortality. Moreover, histone inhibition with specific antibodies reduces mortality in LPS- and/or E.coli challenged animals, prevents ischemia-reperfusion and endotoxin induced acute kidney injury, and thrombocytopenia. All these data suggest that histones are relevant biomarkers and therapeutic targets in pathologic conditions that involve tissue necrosis and inflammation. Histones are released into the extracellular environment either passively by apoptotic or necrotic cells, or actively as neutrophil extracellular traps (NETs). NETs formation is a new paradigm of cell death where neutrophils release their nuclear contents in response to infection or other stimuli. Although NETs aid in trapping bacteria and other pathogens, their prolonged presence may lead to adjacent tissue damage. We have data showing the presence of NETs in intestinal tissue of premature infants with NEC. Whether NETs and their components, specifically histones, contribute to intestinal injury and disease progression in NEC is still unknown. Thus we aim in this proposal to investigate the role of histones and NETs in NEC pathology by (i) determining whether histones-DNA levels are biomarkers of poor prognosis in premature infants with NEC; (ii) characterizing histones' release and NETs formation in mouse models of NEC, and (iii) investigating the effects of histones inhibitors and NET formation using pharmacological and genetic approaches in experimental NEC. Over all this project will potentially advance our understanding of NEC, describe new biomarkers, and lead to novel therapeutic strategies for this highly lethal disease.