Induction of high-affinity IgE receptor on lung dendritic cells during viral infection leads to mucous cell metaplasia

Respiratory viral infections are associated with an increased risk of asthma, but how acute Th1 antiviral immune responses lead to chronic inflammatory Th2 disease remains undefined. We define a novel pathway that links transient viral infection to chronic lung disease with dendritic cell (DC) expression of the high-affinity IgE receptor (FcεRIα). In a mouse model of virus-induced chronic lung disease, in which Sendai virus triggered a switch to persistent mucous cell metaplasia and airway hyperreactivity after clearance of replicating virus, we found that FceRIa^-/- mice no longer developed mucous cell metaplasia. Viral infection induced IgE-independent, type I IFN receptor - dependent expression of FcεRIα on mouse lung DCs. Cross-linking DC FcεRIα resulted in the production of the T cell chemoattractant CCL28. FceRIa^-/- mice had decreased CCL28 and recruitment of IL-13-producing CD4⁺ T cells to the lung after viral infection. Transfer of wild-type DCs to FceRIa ^-/- mice restored these events, whereas blockade of CCL28 inhibited mucous cell metaplasia. Therefore, lung DC expression of FcεRIα is part of the antiviral response that recruits CD4⁺ T cells and drives mucous cell metaplasia, thus linking antiviral responses to allergic/asthmatic Th2 responses. JEM