PUBLICATION

A Macrophage Subversion Factor Is Shared by Intracellular and Extracellular Pathogens

Authors

Belon, C., Soscia, C., Bernut, A., Laubier, A., Bleves, S., Blanc-Potard, A.B.

ID

ZDB-PUB-150617-1

Date

2015

Source

PLoS pathogens 11: e1004969 (Journal)

Registered Authors

Keywords

Pseudomonas aeruginosa, Macrophages, Intracellular pathogens, Embryos, Bacterial biofilms, Bacterial pathogens, Pseudomonas infections, Salmonella

MeSH Terms

Zebrafish
Base Sequence
Virulence Factors/genetics*
Disease Models, Animal
Pseudomonas aeruginosa/genetics
Pseudomonas aeruginosa/pathogenicity*
Intracellular Space
Reverse Transcriptase Polymerase Chain Reaction
Microscopy, Confocal
Embryo, Nonmammalian
Molecular Sequence Data
Animals
Bacterial Proteins/genetics*
Immune Evasion/genetics*
Extracellular Space
Virulence/genetics*
Microscopy, Fluorescence
Pseudomonas Infections/genetics
Phylogeny
Macrophages/microbiology*

(all 20)

PubMed

26080006 Full text @ PLoS Pathog.

Abstract

Pathogenic bacteria have developed strategies to adapt to host environment and resist host immune response. Several intracellular bacterial pathogens, including Salmonella enterica and Mycobacterium tuberculosis, share the horizontally-acquired MgtC virulence factor that is important for multiplication inside macrophages. MgtC is also found in pathogenic Pseudomonas species. Here we investigate for the first time the role of MgtC in the virulence of an extracellular pathogen, Pseudomonas aeruginosa. A P. aeruginosa mgtC mutant is attenuated in the systemic infection model of zebrafish embryos, and strikingly, the attenuated phenotype is dependent on the presence of macrophages. In ex vivo experiments, the P. aeruginosa mgtC mutant is more sensitive to macrophage killing than the wild-type strain. However, wild-type and mutant strains behave similarly toward macrophage killing when macrophages are treated with an inhibitor of the vacuolar proton ATPase. Importantly, P. aeruginosa mgtC gene expression is strongly induced within macrophages and phagosome acidification contributes to an optimal expression of the gene. Thus, our results support the implication of a macrophage intracellular stage during P. aeruginosa acute infection and suggest that Pseudomonas MgtC requires phagosome acidification to play its intracellular role. Moreover, we demonstrate that P. aeruginosa MgtC is required for optimal growth in Mg2+ deprived medium, a property shared by MgtC factors from intracellular pathogens and, under Mg2+ limitation, P. aeruginosa MgtC prevents biofilm formation. We propose that MgtC shares a similar function in intracellular and extracellular pathogens, which contributes to macrophage resistance and fine-tune adaptation to host immune response in relation to the different bacterial lifestyles. In addition, the phenotypes observed with the mgtC mutant in infection models can be mimicked in wild-type P. aeruginosa strain by producing a MgtC antagonistic peptide, thus highlighting MgtC as a promising new target for anti-virulence strategies.

Genes / Markers

Figures