Degradation of Extracellular DNA Significantly Ameliorates Necrotizing Enterocolitis Severity in Mice

BACKGROUND: Necrotizing enterocolitis (NEC) is one of the most devastating diseases in neonates and is characterized by high morbidity and mortality. It has been suggested that neutrophils play a crucial role in NEC pathogenesis and contribute to the hyperinflammatory reaction after bacterial colonization, which ultimately induces NEC. The aim of this study was to investigate whether dissolution of neutrophil extracellular traps (NETs) by systemic DNase1 therapy reduces NEC manifestation and morbidity.

METHODS: NEC was induced in neonatal mice by gavage feeding of lipopolysaccharide mixed in Neocate, followed by hypoxia q12 h for 5d. Inactivated DNase1 and DNase1 were administered intraperitoneally twice daily in the control and treatment groups, respectively, starting on day 5 for 72 h. Survival, NEC score, intestinal damage (Chiu score, malondialdehyde [MDA], glutathione peroxidase [GPx]), inflammation (neutrophil elastase [NE], myeloperoxidase [MPO], toll-like receptor 4 [TLR4]), and NETs markers (SYTOX orange, cell-free DNA [cfDNA], DNase, citrullinated Histone 3 [H3cit]) were then assessed.

RESULTS: In total, 44 neonatal mice were used in the experiment. Mice in the treatment group demonstrated significantly reduced NEC rates (44 versus 86%, P = 0.029) and improved survival in comparison to controls (65 versus 35%, P = 0.01). Furthermore, mice treated with DNase1 showed significantly less tissue damage (cfDNA, Chiu score), oxidative stress (MDA, GPx), and inflammation (NE, MPO, H3cit, TLR4), which ultimately lead to a significant reduction in mortality.

CONCLUSIONS: The results of the study indicate that systemic DNase1 treatment leads to a significant reduction in tissue damage, NEC severity, and mortality. Therefore, after validation of our findings in human subjects, DNase1 treatment should be considered as a therapeutic option in neonates diagnosed with NEC.