Neutrophil Recruitment to the Lungs during Bacterial Pneumonia

Neutrophil Recruitment to the Lungs during Bacterial Pneumonia
Ann Craig, John Mai, Shanshan Cai and Samithamby Jeyaseelan

Infect. Immun., Feb 2009; 77: 568 – 575.

Schematic representation describing the cascade of events by which bacteria induce neutrophil sequestration and eventual lung damage associated with lower respiratory tract infection. Bacteria initially interact with the cells in the alveoli, including alveolar epithelial cells and macrophages (1), and induce the secretion of cytokines and neutrophil chemoattractants (2). These cytokines upregulate the expression of cell adhesion molecules on capillary endothelia (3) and subsequently mediate the transmigration of neutrophils into alveolar spaces based on the chemotactic gradient (4). The transmigrated neutrophils produce proteases, reactive oxygen species (ROS), and reactive nitrogen species (RNS) (5), which act on cells that are infected and induce necrotic cell death (6). Gradually, all of these events lead to extensive lung injury. RBCs, red blood cells.