Host monitoring of quorum sensing during Pseudomonas aeruginosa infection

Spying on bacterial signals Many bacteria produce small molecules for monitoring population density and thus regulating their collective behavior, a process termed quorum sensing. Pathogens likePseudomonas aeruginosa , which complicates cystic fibrosis disease, produce different quorum-sensing ligands at different stages of infection. Moura-Alveset al. used experiments in human cells, zebrafish, and mice to show that a host organism can eavesdrop on these bacterial conversations. A host sensor responds differentially to bacterial quorum-sensing molecules to activate or repress different response pathways. The ability to “listen in” on bacterial signaling provides the host with the capacity to fine-tune physiologically costly immune responses.Science , this issue p.eaaw1629