Legionella pneumophila outer membrane vesicles are potent pro-inflammatory stimulators

The formation and release of outer membrane vesicles (OMVs) is a common phenomenon of gram-negative bacteria, including Legionella pneumophila (L. pneumophila), which is a causative agent of severe community- and hospital-acquired pneumonia. Upon its transmission into the human lung, L. pneumophila primarily replicates in macrophages. In this study, we analyzed the influence of L. pneumophila OMVs on macrophages. For this, THP-1 cells were PMA-differentiated and incubated with increasing doses of OMVs, which led to a classical activation of macrophages with the release of pro-inflammatory cytokines. By use of mu…