Figure 1.

Altered DC-airway epithelial cell (AECs) crosstalk leads to impaired mucosal tolerance and inflammation in the elderly. In normal healthy lung from young subjects, dendritic cells (DCs) do not activate the epithelium at homeostasis and there is no inflammation and hyper-responsiveness (left). In contrast, in the aged lung, DCs secrete low levels of chronic inflammatory mediators, such as TNF-α and IL-6, which modulate the functions of AECs. The permeability, as well as secretion of chemokines (colored circles) by epithelium, are increased which allows infiltration of cells to the airways and leads to airway hyper-responsiveness. Permeability to infections is also increased (right).