Inflammation is normally bad news for pathogens, but one bacterium seems to have turned the process to its own advantage.

Alan Hauser and his team at Northwestern University in Chicago, Illinois, studied a particularly virulent strain of the pneumonia-causing Pseudomonas aeruginosa that had been isolated from a patient. The bacterium produces a protein known as RhsT, and the authors determined that P. aeruginosa injects this protein into host cells called phagocytes — white blood cells that normally engulf and destroy pathogens. Once inside them, RhsT activates an immune-signalling complex called the inflammasome, killing infected cells.

The authors found that the RhsT protein is linked to increased production of inflammatory proteins in cell culture and in the lungs of infected mice. The mice died within two days of infection. Conversely, mice infected with P. aeruginosa in which the rhsT gene had been deleted survived.

Many bacterial pathogens contain genes similar to rhsT, which may be important for infection.

Proc. Natl Acad. Sci. USA http://dx.doi.org/10.1073/pnas.1109285109 (2012)