OBJECTIVETo investigate the effects of polyinosinic-polycytidylic acid (polyI:C) on the production of thymic stromal lymphopoietin (TSLP) and airway inflammation in mice with exacerbated asthma induced by respiratory syncytial virus (RSV).

METHODSThirty-two female BALB/c mice were randomly divided into 4 groups, namely the PBS control group, OVA group, OVA/RSV group, and OVA/RSV/polyI:C group. In the latter 3 groups, the mice were sensitized by OVA and stimulated with nebulized OVA. RSV was inoculated into the nasal cavity of the sensitized mice and polyI:C (1 mg/kg) was intramuscularly administered. The airway response to metacholine was examined, and the serum levels of IL-4, IL-5, IL-13, and IFN-γ and TSLP in the supernatants of bronchoalveolar lavage fluid (BALF) were detected using ELISA. The total BALF cells, eosinophils, lymphocytes and neutrophils were counted. The lung specimens were collected to observe the inflammation with HE staining, and immunohistochemistry was employed to determine TSLP production in the airway epithelial cells.

RESULTSThe mice in RSV/OVA/polyI:C group showed a significantly lower airway responsiveness to metacholine than those in OVA/RSV group (P<0.01). Compared with OVA/RSV group, RSV/OVA/polyI:C group showed significantly lower serum levels of IL-4, IL-5, IL-13 and TSLP in BALF (P<0.05), with also lower total BALF cells, eosinophils and lymphocytes (P<0.05) and lessened infiltration of the airway inflammatory cells. Immunohistochemistry of TSLP also demonstrated a lower production of TSLP in the airway epithelial cells in RSV/OVA/polyI:C group than in OVA/RSV group.

CONCLUSIONSpolyI:C can inhibit the increase in TSLP production in the airway epithelial cells after RSV infection and relieve airway inflammation in mice with RSV-induced asthma exacerbation.