title: Involvement of a 1-Cys peroxiredoxin in bacterial virulence.
abstract: The killing of bacterial pathogens by macrophages occurs via the oxidative burst and bacteria have evolved to overcome this challenge and survive, using several virulence and defense strategies, including antioxidant mechanisms. We show here that the 1-Cys peroxiredoxin LsfA from the opportunistic pathogen Pseudomonas aeruginosa is endowed with thiol-dependent peroxidase activity that protects the bacteria from H(2)O(2) and that this protein is implicated in pathogenicity. LsfA belongs to the poorly studied Prx6 subfamily of peroxiredoxins. The function of these peroxiredoxins has not been characterized in bacteria, and their contribution to host-pathogen interactions remains unknown. Infection of macrophages with the lsfA mutant strains resulted in higher levels of the cytokine TNF-α production due to the activation of the NF-kB and MAPK pathways, that are partially inhibited by the wild-type P. aeruginosa strain. A redox fluorescent probe was more oxidized in the lsfA mutant-infected macrophages than it was in the macrophages infected with the wild-type strain, suggesting that the oxidative burst was overstimulated in the absence of LsfA. Although no differences in the phagocytosis rates were observed when macrophages were infected with wild-type and mutant bacteria in a gentamicin exclusion assay, a higher number of wild-type bacterial cells was found in the supernatant. This difference was not observed when macrophages were pre-treated with a NADPH oxidase inhibitor, confirming the role of LsfA in the bacterial resistance to ROS generated via NADPH oxidase. In an acute pneumonia model, mice infected with the mutant strains presented higher cytokine release in the lungs and increased activated neutrophil recruitment, with reduced bacterial burden and improved survival rates compared to mice infected with the wild-type bacteria. LsfA is the first bacterial 1-Cys Prx shown to modulate host immune responses and its characterization will allow a better understanding of the role of redox signaling in host-pathogen interactions.
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Gilberto Hideo
authors.initials: GH
authors.lastname: Kaihami
authors.affiliation: Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: José Roberto Fogaça de
authors.initials: JR
authors.lastname: Almeida
authors.affiliation: Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Suelen Silvana dos
authors.initials: SS
authors.lastname: Santos
authors.affiliation: Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Luis Eduardo Soares
authors.initials: LE
authors.lastname: Netto
authors.affiliation: Departamento de Análises Clínicas, Faculdade de Ciências Farmacêuticas, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Sandro Rogério de
authors.initials: SR
authors.lastname: Almeida
authors.affiliation: Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
authors.forename: Regina Lúcia
authors.initials: RL
authors.lastname: Baldini
mesh_terms: D000818:Animals; D054884:Host-Pathogen Interactions / Q000276:immunology*; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008264:Macrophages / Q000187:drug effects / Q000276:immunology*; D051379:Mice; D019255:NADPH Oxidases / Q000378:metabolism; D054464:Peroxiredoxins / Q000494:pharmacology*; D010587:Phagocytosis / Q000276:immunology; D011552:Pseudomonas Infections / Q000378:metabolism* / Q000821:virology; D011550:Pseudomonas aeruginosa / Q000472:pathogenicity; D016897:Respiratory Burst / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D014774:Virulence / Q000187:drug effects
chemical_list: D014409:Tumor Necrosis Factor-alpha; D006861:Hydrogen Peroxide; D054464:Peroxiredoxins; D019255:NADPH Oxidases