Pf4 phage bound to bacterial vesicles dampens neutrophil responses to Pseudomonas aeruginosa

Stanford researchers show that the temperate filamentous phage Pf4 of Pseudomonas aeruginosa is decorated with outer membrane vesicles whose short RNAs trigger TLR3-dependent type I interferon production and suppress antibacterial cytokines and chemokines, including CXCL5, which limits neutrophil chemotaxis. In a mouse acute pneumonia model, Pf4 with vesicles produced less neutrophil infiltration than purified Pf4, suggesting phages may dampen inflammation at sites of colonization or infection.