Anti-inflammatory Effects of a Small Molecule Gastrin-Releasing Peptide Receptor Antagonist on Adjuvant-Induced Rheumatoid Arthritis in Rats

抄録

The anti-inflammatory effects of (R)-2-(1H-Imidazol-1-yl) ethyl-3-(1H-indol-3-yl)-2-(2-p-tolylacetamido)propanamide (RH-1402), a previous designed small molecule Gastrin releasing peptide (GRP) antagonist were evaluated in adjuvant-induced arthritic model of rats, and the inhibitory effect on neutrophil migration induced by GRP was determined by a transwell system experiment in vitro. The arthritis was induced by injection of Complete Freund’s Adjuvant (CFA) containing 10 mg/mL of heat killed mycobacterium into the left hind footpad. Experimental rats were randomly divided into 6 groups, including control, placebo, positive control group, RH-1402 of low/middle/high dose group. Disease incidence and severity was evaluated through scoring of the paw edema and histologic features of joint synovial. Blood of all experimental rats was collected for interleukin 1β (IL-1β) and tumor necrosis factor α (TNF-α) cytokine levels. A transwell system was used to investigate whether RH-1402 would inhibit neutrophils migrating up a gradient of GRP in vitro. RH-1402 (5 and 10 mg/kg) significantly decreased adjuvant induced increased arthritis index during the administration period (days 14–20). Significant inhibition of joint synovial histological features can be found in the RH-1402 treated group, including alleviated Hyperplasia, Inflammatory of infiltration and activation of pannus formation. It also suppressed TNF-α and IL-1β level. Five and 10 mg/kg of RH-1402 significantly inhibited the effect of GRP on neutrophil migration with a dose dependent relationship. These findings indicate that RH-1402 have potential protective anti-inflammatory effects on experimental models of arthritis.