Rationale: The alarmins IL-33 and HMGB1 (high mobility group box 1) contribute to type-2 inflammation and asthma pathogenesis.
Objectives: To determine whether P2Y13 receptor (P2Y13-R), a purinergic G protein-coupled receptor (GPCR) and risk allele for asthma, regulates the release of IL-33 and HMGB1.
Methods: Bronchial biopsies were obtained from healthy subjects. Primary human airway epithelial cells (AECs), primary mouse (m)AECs, or C57Bl/6 mice were inoculated with various aeroallergens or respiratory viruses, and the nuclear-to-cytoplasmic translocation and release of alarmins measured by immunohistochemistry and ELISA. The role of P2Y13-R in AEC function and in the onset, progression, and an exacerbation of experimental asthma, was assessed using pharmacological antagonists and P2Y13-R gene-deleted mice.
Measurements and Main Results: Aeroallergen-exposure induced the extracellular release of ADP and ATP, nucleotides that activate P2Y13-R. ATP, ADP, aeroallergen (house dust mite, cockroach or alternaria antigen) or virus exposure induced the nuclear-to-cytoplasmic translocation and subsequent release of IL-33 and HMGB1, and this response was ablated by genetic deletion or pharmacological antagonism of P2Y13. In mice, P2Y13-R blockade attenuated asthma onset, and critically, ablated the severity of a rhinovirus-associated exacerbation in a high-fidelity experimental model of chronic asthma. Moreover, P2Y13-R antagonism derepressed antiviral immunity, increasing IFN-λ production and decreasing viral copies in the lung.
Conclusions: We identify P2Y13-R as a novel gatekeeper of the nuclear alarmins IL-33 and HMGB1, and demonstrate that the targeting of this GPCR via genetic deletion or treatment with a small-molecule antagonist protects against the onset and exacerbations of experimental asthma.