Methods: We cultured A549 human epithelial cell line in serum-free media for a day and RSV was inoculated into the cells. After the infection for an hour, low or high dose of Dermatophagoides farinae (Der f) or Dermatophagoides pteronyssinus (Der p) allergen was treated into media and 24hr later we assessed the concentration of proinflammatory cytokines in media and their mRNA levels.
Results: IL-8 levels were highly detected in both RSV-infected cells only and allergen-treated cells only group. In low dose allergen-treated groups, particularly, IL-8 concentration in media was significantly higher in RSV-infected group than no-infected group. Other proinflammatory and allergy-related cytokines such as IL-6, TNF-a, and TSLP in RSV and allergen-treated groups showed no difference compared with control groups. The other house dust mite allergen, Der p also showed similar results with Der f, increasing IL-8 level in RSV-infected with low-dose allergen treated group.
Conclusions: Our findings showed that IL-8 production in low dose of Der f-sensitized human airway epithelial cells was highly enhanced by RSV infection. We therefore implied that RSV infection may allow the airway epithelial cells to be more sensitive against airborne allergens, leading to augmentation of susceptibility for asthma.