Modulation of NET formation by DNAse1 or neutrophil elastase influences neutrophil recruitment, vascular permeability, and severity of VILI. WT mice with or without DNAse1 pretreatment and DNAse1^−/−/Trap1^m/m (DNAse1^−/−) mice and neutrophil elastase–deficient (NE^−/−) mice were ventilated with sham or VILI settings. (A) The paO₂/FiO₂ ratio, (B) neutrophil recruitment into the alveoli, and (C) protein concentration in the BAL were analyzed after 2 hours (n = 4). (D) The formation of circulating platelet-neutrophil aggregates was measured by flow cytometry 30 minutes after induction of sham or VILI ventilation (n = 4). (E) Circulating NET structures were quantified by MPO-DNA-ELISA (n = 4). *P < .05.