HRH1 and allergic disease: HRH1 has been found to be widely expressedwithin respiratory tract tissues, including nasal and lung tissues (37, 38).Upon encountering allergens, released histamines can bind to HRH1, therebytriggering allergic rhinitis and allergic lung responses, while the competitivebinding of antihistamine drugs to HRH1 alleviates histamine-induced allergies (39, 40).