Methods: CysLT3R distribution in the lower airway epithelium was assessed by X-gal staining of CysLT3R-deficient (Oxgr1−⁄−) mice. Wild-type (WT), LTC4-synthase-deficient (Ltc4s−⁄−), and Oxgr1−⁄− mice received a single intranasal dose of 0 or 30 µg A.alternata, Cladosporium herbarum, or 100 µg Dermatophagoides farinae. After 3 days, airway inflammation and EpC composition were assessed by FACS and immunofluorescence in the lung and trachea, respectively. WT and Oxgr1−⁄− mice were given 4 daily doses of 0.25 nmol LTE4 and analyzed 24 h after the last inhalation as above. Antibody blockade with intraperitoneal anti-IL25 was performed on days 0 and 3 in conjunction with Alternaria and LTE4 challenges.
Results: CysLT3R is expressed on airway brush cells (BrCs), specialized chemosensory IL-25 generating EpCs. Inhalation of aeroallergens led to expansion of airway BrCs, which was attenuated in mice lacking either CysLT3R or LTC4 synthase, the biosynthetic enzyme required for cysLT generation. LTE4 inhalation was sufficient to elicit CysLT3R-dependent BrC expansion in the airway, attenuated by IL-25 blockade, indicating a direct action on airway EpCs. Blockade of IL-25 attenuated both aeroallergen and LTE4-elicited CysLT3R-dependent type 2 lung inflammation.
Conclusions: CysLT3R is activated by endogenously generated lipid ligand LTE4 and regulates airway BrC number and sentinel function through and IL-25 signaling pathway.