IGHE and inflammatory response: In OVA-challenged model, which is widely accepted as a Th2-type asthma model (30), EP4 agonist PGE1-alcohol displayed similar potency as PGE2 in inhibiting OVA-induced airway inflammation based on all parameters examined, including IgE concentration, the exudation of inflammatory cells, and lung pathology (Figures 2C,D, Figure S2).