Microbial pathogenesis
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Microbial pathogenesis · Dec 2011
Absence of phagocyte NADPH oxidase 2 leads to severe inflammatory response in lungs of mice infected with Coccidioides.
Production of reactive oxygen species (ROS) resulting from phagocytic NADPH oxidase (NOX2) activity has been reported to contribute to host defense against numerous microbial pathogens. In this study we explored the role of NOX2 production in experimental coccidioidomycosis, a human respiratory disease caused by a soil-borne fungal pathogen. Activated and non-activated macrophages isolated from either NOX2(-/-) knock-out or wild type (WT) mice showed comparable ROS production and killing efficiency in vitro when infected with parasitic cells of Coccidioides. ⋯ These combined results initially suggested that NOX2 activity and ROS production are not essential for protection against Coccidioides infection. However, the reduced survival of non-vaccinated NOX2(-/-) mice correlated with high, sustained numbers of lung-infiltrated neutrophils on days 7 and 11 postchallenge, an expansion of the regulatory T cell population in infected lungs in the knock-out mice, and elevated concentrations of pro-inflammatory cytokines and chemokines in lung homogenates compared to infected WT mice. Although NOX2-derived ROS appeared to be dispensable for both innate and acquired immunity to pulmonary Coccidioides infection, evidence is presented that NOX2 production plays a role in limiting pathogenic inflammation in this murine model of coccidioidomycosis.