We study host defense mechanisms in the lungs, particularly the inflammatory and innate immune processes important in the pathogenesis and course of bacterial pneumonia, acute lung injury/acute respiratory distress syndrome, and cigarette smoke-associated lung disease. Basic and translational studies address mechanisms of host defense, including recruitment and function of leukocytes, vascular permeability leading to edema, bacterial clearance and resolution. Cell signaling pathways initiated by binding of leukocyte-endothelial cell adhesion molecules and molecular mechanisms underlying the functions of neutrophils are two particular areas.