Restoration of anti-Aspergillus defense by NETs in human CGD after gene therapy is calprotectin-dependent (158.5)

Abstract

Abstract Aspergillus spp infection is a potentially lethal disease in patients with neutropenia or impaired neutrophil function. We have previously shown that Aspergillus hyphae which are too large for neutrophil phagocytosis are inhibited by reactive oxygen species dependent neutrophil extracellular trap (NET) formation. This process is defective in chronic granulomatous disease (CGD) due to impaired phagocyte NADPH oxidase function. Here we determined the antifungal agent and mechanism responsible for reconstitution of Aspergillus growth inhibition within NETs after complementation of NADPH oxidase function by gene therapy (GT) for CGD. We identified the host Zn2+ chelator calprotectin as neutrophil-associated antifungal agent expressed within NETs, reversibly preventing A. nidulans growth at low concentration, and leading to fungal starvation at higher concentration. Specific antibody-blocking and Zn2+ addition abolished calprotectin-mediated inhibition of A. nidulans proliferation in vitro. The role of calprotectin in anti-Aspergillus defence was confirmed in calprotectin knockout mice. Reconstituted NET formation by GT for human CGD was associated with rapid cure of pre-existing therapy refractory invasive pulmonary aspergillosis in vivo, underlining the role of functional NADPH oxidase in NET formation and calprotectin release for antifungal activity. These results demonstrate that calprotectin is a critical factor in the human innate immune defense to Aspergillus infection.