The effect of respiratory synctial virus on chemokine release by differentiated airway epithelium

Respiratory synctial virus (RSV) infection of undifferentiated airway epithelial cells has been shown to induce the production of chemokines. The purpose of this study was to investigate the vectorial release of interleukin (IL-8) and Released on Activation, Normal T-cell Expressed and Secreted (RANTES) by polarized, well-differentiated respiratory epithelial cells after RSV infection. Human bronchial epithelial cultures were differentiated under air-liquid interface conditions and infected with RSV by the apical or basolateral route. RSV infection was specific to the apical surface. Supernatants were collected at 6 and 48 hours after RSV inoculation, and IL-8 and RANTES were measured by enzyme-linked immunosorbent assay (ELISA). Both IL-8 and RANTES were significantly released by 48 hours following inoculation with RSV. The secretion of each chemokine was greatest after apical inoculation, and secretion was polarized to the basolateral supernatant. Immunohistochemical staining confirmed that RSV infection was specific to ciliated cells, and immunohistochemical staining for chemokines was localized to RSV-infected ciliated cells. The authors conclude that, in differentiated human airway epithelium in vitro, RSV-induced increases in IL-8 and RANTES release are predominantly in the basolateral direction. In epithelial layers, virus-containing cells are the predominant source of the increased chemokine release. The authors speculate that similar processes in vivo influence recruitment of leukocytes to sites of RSV infection.