Macrophages render alveolar epithelial cells hypo-responsive to Legionella pneumophila

Pneumonia is a leading cause of mortality worldwide. To secure organ function, pulmonary innate immune response has to be tightly regulated. Here, we analyze whether macrophages influence immune reactivity of type II alveolar epithelial cells during infection with an intracellular bacterial pathogen. For this purpose, human macrophage-like differentiated THP-1 cells were co-cultured with human alveolar epithelial A549 cells in a transwell-setting. Infection of THP-1 cells with the important respiratory pathogen Legionella pneumophila (L. pneumophila) resulted in the release of pro-inflammatory cytokines, e.g. IL…