PEGylated d -amino acid oxidase restores bactericidal activity of neutrophils in chronic granulomatous disease via hypochlorite

Abstract

Chronic granulomatous disease (CGD) causes impaired hydrogen peroxide (H₂O₂) generation. Consequently, neutrophils in patients with CGD fail to kill infecting pathogens. We expected that supplementation with H₂O₂ would effectively restore the bactericidal function of neutrophils in CGD. Here, we used polyethylene glycol-conjugated d-amino acid oxidase (PEG-DAO) as an H₂O₂ source. The enzyme DAO generates H₂O₂ by using d-amino acid and oxygen as substrates. PEG-DAO plus d-amino acid indeed exerted bacteriostatic activity against Staphylococcus aureus via H₂O₂ in vitro. Furthermore, use of PEG-DAO plus d-amino acids, which increased the amount of intracellular H₂O₂, restored bactericidal activity of neutrophils treated with diphenylene iodonium, in which nicotinamide adenine dinucleotide phosphate (NADPH) oxidase was defective. This restoration of bactericidal activity was mediated by myeloperoxidase, with concomitant production of H₂O₂ by PEG-DAO plus d-Ala. We also confirmed that PEG-DAO treatment restored bactericidal activity of congenitally defective neutrophils from patients with CGD. These results indicate that PEG-DAO can supply additional H₂O₂ for defective NADPH oxidase of neutrophils from patients with CGD, and thus neutrophils regain bactericidal activity.