| Biochem/physiol Actions | Pyocyanin is a redox-active phenazine produced by Pseudomonas aeruginosa, which generates reactive oxygen intermediates that kill mammalian and bacterial cells. In bacteria, pyocyanin acts not only as an antibiotic to inhibit competitors, but also acts as an intracellular signal to activate SoxR, a transcription factor conserved in Proteo- and Actinobacteria. In humans, pyocyanin depletes intracellular stores of NADPH, as it generates intracellular superoxide. It has been found that pyocyanin dramatically accelerates a neutrophil apoptosis both in vitro and in vivo, impairs host defenses, and favors bacteral persistence. pyocyanin induces apoptosis by engagement of lysosomal pathways of cell death, destabilizes neutrophil granules, and releases cathepsin D into the cytosol. |
