ReviewAirway epithelial regulation of pulmonary immune homeostasis and inflammation

- We review the role of the airway epithelium in inflammation and immunity.
- We focus on epithelial cell immune regulation triggered by environmental signals.
- We describe epithelial coordination of the innate and adaptive immune responses.
- We discuss epithelial recruitment of innate and adaptive inflammatory cells.
- We elaborate on the pathological implications of epithelial immune activation.

Recent genetic, structural and functional studies have identified the airway and lung epithelium as a key orchestrator of the immune response. Further, there is now strong evidence that epithelium dysfunction is involved in the development of inflammatory disorders of the lung. Here we review the characteristic immune responses that are orchestrated by the epithelium in response to diverse triggers such as pollutants, cigarette smoke, bacterial peptides, and viruses. We focus in part on the role of epithelium-derived interleukin (IL)-25, IL-33 and thymic stromal lymphopoietin (TSLP), as well as CC family chemokines as critical regulators of the immune response. We cite examples of the function of the epithelium in host defense and the role of epithelium dysfunction in the development of inflammatory diseases.