Inflammatory Cytokines and Alveolar Epithelium
The bronchial epithelium is a primary target for respiratory
viruses28. Alveolar epithelium plays an important role
in promoting cell barrier functions and strengthening cell-cell
junctions against virus-induced disruption of tight junctions.
However, virus infected epithelial
cells express cytokines that primarily attract macrophages. Once
recruited, the activated macrophages promote activation of adjacent
endothelial cells. Infiltrating macrophages produce reactive oxygen
species and nitric oxide30 that serve to damage the
barrier31. Macrophages also promote epithelial-cell
apoptosis epithelial cells and mediate phagocytosis of apoptotic
cells31, 32, 33.