MPO and infectious disease: NETs are initially recognised to entrap and kill pathogens via a DNA framework comprising abundant antimicrobial granular proteins, such as MPO and NE.31 However, they are immunogenic and have been implicated in several autoimmune and non-infectious diseases.25,32,33 In COPD, augmented self-DNA from increased lung cell apoptosis acts as DAMPs, impeding inflammation resolution.