Manago 2015 Abstract MiPschool London 2015
|Pseudomonas aeruginosa pyocyanin induces neutrophil death via mitochondrial reactive oxygen species ad mitochondrial acid sphingomyelinase.|
Event: MiPschool London 2015
Pulmonary infections with Pseudomonas aeruginosa are a serious clinical problem and are often lethal. Because many strains of P. aeruginosa are resistant to antibiotics, therapeutic options are limited. Neutrophils play an important role in the host’s early acute defense against pulmonary P. aeruginosa. Therefore, it is important to define the mechanisms by which P. aeruginosa interacts with host cells, particularly with neutrophils . Here, we report that pyocyanin, a membrane-permeable pigment and toxin released by P. aeruginosa  , induces the death of wild-type neutrophils.
We investigated the mechanism of action of pyocyanin in inducing cell death in host cells by measuring Annexin V staining and the release of cytochrome c; also the enzymatic activity of acid sphingomyelinase and the formation of ceramide were measured. Moreover the bioenergetic effects induced by pyocyanin, both on intacts cells and on isolated mitochondria were observed by measuring respiration, ROS production and mitochondrial membrane potential and the activity of the respiratory chain complexes in presence of pyocyanin.
We found that its interaction with the mitochondrial respiratory chain results in the release of reactive oxygen species (ROS), the activation of mitochondrial acid sphingomyelinase, the formation of mitochondrial ceramide, and the release of cytochrome c from mitochondria. A genetic deficiency in acid sphingomyelinase prevents both the activation of this pathway and pyocyanin-induced neutrophil death. This reduced death, on the other hand, is associated with an increase in the release of interleukin-8 from pyocyanin- activated acid sphingomyelinase-deficient neutrophils but not from wild-type cells.
These studies identified the mechanisms by which pyocyanin induces the release of mitochondrial ROS and by which ROS induce neutrophil death via mitochondrial acid sphingomyelinase. These findings demonstrate a novel mechanism of pyocyanin-induced death of neutrophils and show how this apoptosis balances innate immune reactions.
Labels: MiParea: Patients
Stress:Oxidative stress;RONS Organism: Protists
Preparation: Intact cells, Isolated mitochondria
1-Dept Biol, Univ Padua, Italy. - [email protected]
2-Dept Mol Biol, Univ Hospital, Univ Duisburg-Essen, Essen, Germany
3-Dept Surgery, Univ Cincinnati College Med, Cincinnati, Ohio, USA
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- Managò A, Becker KA, Carpinteiro A, Wilker B, Soddemann M, Seitz AP, Edwards MJ, Grassmé H, Szabò I, Gulbins E (2015) Pseudomonas aeruginosa pyocyanin induces neutrophil death via mitochondrial reactive oxygen species and mitochondrial acid sphingomyelinase. Antioxid Redox Signal 22:1097-110.