Allergin-1 Immunoreceptor Suppresses House Dust Mite-Induced Allergic Airway Inflammation.

House dust mite (HDM) allergens are leading causes of allergic asthma characterized by Th2 responses. The lung-resident CD11b+ dendritic cells (DCs) play a key role in Th2 cell development in HDM-induced allergic asthma. However, the regulatory mechanism of HDM-induced CD11b+ DC activation remains incompletely understood. In this study, we demonstrate that mice deficient in an inhibitory immunoreceptor, Allergin-1, showed exacerbated HDM-induced airway eosinophilia and serum IgE elevation. By using bone marrow-chimeric mice that were sensitized with adoptively transferred HDM-stimulated wild-type or Allergin-1-deficient CD11b+ bone marrow-derived cultured DCs (BMDCs), followed by challenge with HDM, we show that Allergin-1 on the BMDCs suppressed HDM-induced allergic airway inflammation. We also show that Allergin-1 suppressed HDM-induced PGE2 production from CD11b+ BMDCs by inhibiting Syk tyrosine kinase activation through recruitment of SHP-1, subsequently leading to negative regulation of Th2 responses. These results suggest that Allergin-1 plays an important role in regulation of HDM-induced allergic airway inflammation.