Respiratory syncytial virus predisposes mice to augmented allergic airway responses via IL-13-mediated mechanisms

The development of severe childhood asthma may be influenced by several fac tors including environmental and infectious stimuli. The causal relationshi p between infectious viral responses, such as respiratory syncytial virus ( RSV), and severe asthma during early childhood is unclear. In these studies , the ability for an initial RSV infection to exacerbate and promote a more severe asthmatic-type response was investigated by combining established m urine models of disease. We examined the ability of RSV to induce exacerbat ion of allergic disease over a relatively long period, leading to developme nt of severe airway responses including airway inflammation and hyperreacti vity. The preferential production of IL-13 during a primary RSV infection a ppears to play a critical role for the exacerbation of cockroach allergen-i nduced disease. The depletion of IL-13 during RSV infections inhibited the exacerbation and acceleration of severe allergen-induced airway hyperreacti vity. This was indicated by decreases in airway hyperreactivity and changes in lung chemokine production. These data suggest that the airway responses during asthma can be greatly affected by a previous RSV infection, even wh en infection occurs before allergen sensitization. Overall, infection of th e airways with RSV can induce an IL-13-dependent change in airway function and promotes an environment that contributes to the development of severe a llergic asthmatic responses.