Respiratory syncytial virus induces leukotriene C4 synthase expression in bronchial epithelial cells.

BACKGROUND AND OBJECTIVE: Respiratory syncytial virus (RSV) results in acute wheezing in infants and is frequently associated with recurrent wheezing. Although RSV-induced wheezing clinically resembles that of asthma, corticosteroids are not equivalently effective in RSV-associated wheezing. The study sought to determine the mechanisms of RSV-induced wheezing by establishing an in vitro model of RSV-infected human bronchial epithelial cells (16-HBEC).

METHODS: Leukotriene C4 synthase (LTC4 S) messenger RNA (mRNA) expression in 16-HBEC was detected using fluorescence quantitative polymerase chain reaction, and the relative level of LTC4 S mRNA was expressed as quotient cycle threshold (qCt) based on the threshold cycle number value compared with that of β-actin. Cysteinyl leukotrienes (CysLT) in culture supernatant were measured by enzyme-linked immunosorbent assay. RSV-infected 16-HBEC was incubated with gradient concentration of budesonide (BUD) to assess its effects on LTC4 S expression and CysLT secretion.

RESULTS: RSV infection resulted in increased LTC4 S mRNA expression between 48 and 96 h post-infection. High level of CysLT was detected in the supernatant of RSV-infected 16-HBEC. BUD at concentrations of 10(-10) to 10(-5) mol/L did not significantly alter LTC4 S mRNA expression.

CONCLUSIONS: RSV infection upregulated LTC4 S expression in HBEC leading to increased CysLT secretion. Such induction was not attenuated by BUD, suggesting that CysLT might contribute to the pathogenesis of RSV-induced wheezing.