Pyocyanin from Pseudomonas aeruginosa inhibits prostacyclin release from endothelial cells.

Pseudomonas aeruginosa pneumonia causes a vasculitis of small pulmonary arteries. While the fully developed lesion demonstrates vessel wall necrosis, the early lesion is remarkable for preservation of viable endothelium despite vessel wall invasion by bacteria. Pyocyanin, an exoproduct of P. aeruginosa, markedly inhibited prostacyclin production by pulmonary artery endothelial cells without causing cell lysis. Pyocyanin might after vascular homeostasis in the absence of cytolysis.