Prostaglandin as a Target Molecule for Pharmacotherapy of Allergic Inflammatory Diseases

The purpose of this review is to summarize the role of prostaglandins (PGs) in allergic inflammation and to know the value of PGs, as a target molecule for an anti-allergic drug. PGD2 is the major PG produced by the cyclooxygenase pathway in mast cells. Our and others findings indicate that PGD2 is one of the potent allergic inflammatory mediators and must be a target molecule of antiallergic agent. From our data, one of PGD2 receptor antagonists show clear inhibition of airway hypersensitivity caused by allergic reaction. Concerning the role of PGE2 in allergic inflammation, conflicting results have been reported. Many experimental data suggest an individual role of each PGE2 receptor, EP1, EP2, EP3 and EP4 in allergic reaction. Our results indicate the protective action of PGE2 on allergic reaction via EP3. In addition, one of EP3 agonists clearly inhibits the allergic airway inflammation. These findings indicate the value of EP3 agonists as an anti-allergic agent. In addition, some investigators including us reported that PGI2 plays an important role for the protection of the onset of allergic reaction. However, the efficacy of PGI2 analogue as an anti-allergic agent is not yet fully investigated. Finally, the role of thromboxane A2 (TxA2) in allergic reaction is discussed. Our experimental results suggest a different participation of TxA2 in allergic reaction of airway and skin. In this review, the role of PGs in allergic inflammation is summarized and the value of PGs as a target molecule for developing a new anti-allergic agent will be discussed.