AT-56

AT-56 inhibits human and mouse L-PGDSs in a concentration (3–250 μm)-dependent manner. AT-56 inhibits the L-PGDS activity in a competitive manner against the substrate PGH2 (Km = 14 μm) with a Ki value of 75 μm. AT-56 inhibits the production of PGD2 by L-PGDS-expressing human TE-671 cells after stimulation with Ca2+ ionophore (5 μm A23187) with an IC50 value of about 3 μm without affecting their production of PGE2 and PGF2α.^[1]

TE-671 (1×10⁶ cells/well) and MEG-01S (5×10⁵ cells/well) are seeded into multiplates and cultured in Dulbecco's modified Eagle's medium supplemented with 10% heat-inactivated fetal bovine serum, 4 mM L-glutamine, 4.5 g/liter glucose, 100 units/ml penicillin, and 100 μg/ml streptomycin sulfate under a 5% CO2 atmosphere at 37 ℃. MEG-01S cells are caused to differentiate by treatment with 12-O-tetradecanoylphorbol-13-acetate to express H-PGDS and COX-1. After the cells have been cultured for 1 day, AT-56 is added to them at different doses ranging from 0 to 100 μM, and the cells are then incubated at 37 ℃ for 10 min. Thereafter, they are stimulated with a calcium ionophore, A23187 (5 μM), at 37 ℃ for 15 min. The culture media were harvested and centrifuged at 10,000 × g for 5 min to remove the cells, and the supernatant is removed and stored at 80 ℃ until the measurements of PGs can be made.

Orally administered AT-56 (<30 mg/kg body weight) decreases the PGD2 production to 40% in the brain of H-PGDS-deficient mice after a stab wound injury in a dose-dependent manner without affecting the production of PGE2 and PGF2α and also suppresses the accumulation of eosinophils and monocytes in the bronco-alveolar lavage fluid from the antigen-induced lung inflammation model of human L-PGDS-transgenic mice.^[1]