Imaging invasive fungal growth and inflammation in NADPH oxidase-deficient zebrafish

Abstract

AbstractNeutrophils are primary cells of the innate immune system that generate reactive oxygen species (ROS) and mediate host defense. Deficient phagocyte NADPH oxidase (PHOX) function leads to chronic granulomatous disease (CGD) that is characterized by invasive infections including those by the generally non-pathogenic fungusAspergillus nidulans. The role of neutrophil ROS in this specific host-pathogen interaction remains unclear. Here, we exploit the optical transparency of zebrafish to image the effects of neutrophil ROS on invasive fungal growth and neutrophil behavior in response toAspergillus nidulans. In a wild-type host,A. nidulansgerminates rapidly and elicits a robust inflammatory response with efficient fungal clearance. PHOX-deficient larvae have increased susceptibility to invasiveA. nidulansinfection despite robust neutrophil infiltration. Expression of p22phoxspecifically in neutrophils does not affect fungal germination but instead limits the area of fungal growth and excessive neutrophil inflammation and is sufficient to restore host survival in p22phox-deficient larvae. These findings suggest that neutrophil ROS limits invasive fungal growth and has immunomodulatory activities that contribute to the specific susceptibility of PHOX-deficient hosts to invasiveA. nidulansinfection.