Anti-inflammatory effect of a selective 11ß-hydroxysteroid dehydrogenase type 1 inhibitor via the stimulation of heme oxygenase-1 in LPS-activated mice and J774.1 murine macrophages.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) converts inactive cortisone to the active cortisol. 11ß-HSD1 may be involved in the resolution of inflammation. In the present study, we investigate the anti-inflammatory effects of 2-(3-benzoyl)-4-hydroxy-1,1-dioxo-2H-1,2-benzothiazine-2-yl-1-phenylethanone (KR-66344), a selective 11ß-HSD1 inhibitor, in lipopolysaccharide (LPS)-activated C57BL/6J mice and macrophages. LPS increased 11ß-HSD1 activity and expression in macrophages, which was inhibited by KR-66344. In addition, KR-66344 increased survival rate in LPS treated C57BL/6J mice. HO-1 mRNA expression level was increased by KR-66344, and this effect was reversed by the HO competitive inhibitor, ZnPP, in macrophages. Moreover, ZnPP reversed the suppression of ROS formation and cell death induced by KR-66344. ZnPP also suppressed animal survival rate in LPS plus KR-66344 treated C57BL/6J mice. In the spleen of LPS-treated mice, KR-66344 prevented cell death via suppression of inflammation, followed by inhibition of ROS, iNOS and COX-2 expression. Furthermore, LPS increased NFκB-p65 and MAPK phosphorylation, and these effects were abolished by pretreatment with KR-66344. Taken together, KR-66344 protects against LPS-induced animal death and spleen injury by inhibition of inflammation via induction of HO-1 and inhibition of 11ß-HSD1 activity. Thus, we concluded that the selective 11ß-HSD1 inhibitor may provide a novel strategy in the prevention/treatment of inflammatory disorders in patients.

Distinction of microsomal prostaglandin E synthase-1 (mPGES-1) inhibition from cyclooxygenase-2 inhibition in cells using a novel, selective mPGES-1 inhibitor.

Inflammation-induced microsomal prostaglandin E synthase-1 (mPGES-1) is the terminal enzyme that synthesizes prostaglandin E(2) (PGE(2)) downstream of cyclooxygenase-2 (COX-2). The efficacy of nonsteroidal anti-inflammatory drugs and COX-2 inhibitors in the treatment of the signs and symptoms of osteoarthritis, rheumatoid arthritis and inflammatory pain, largely attributed to the inhibition of PGE(2) synthesis, provides a rationale for exploring mPGES-1 inhibition as a potential novel therapy for these diseases. Toward this aim, we identified PF-9184 as a novel mPGES-1 inhibitor. PF-9184 potently inhibited recombinant human (rh) mPGES-1 (IC(50)=16.5+/-3.8nM), and had no effect against rhCOX-1 and rhCOX-2 (>6500-fold selectivity). In inflammation and clinically relevant biological systems, mPGES-1 expression, like COX-2 expression was induced in cell context- and time-dependent manner, consistent with the kinetics of PGE(2) synthesis. In rationally designed cell systems ideal for determining direct effects of the inhibitors on mPGES-1 function, but not its expression, PF-9184 inhibited PGE(2) synthesis (IC(50) in the range of 0.5-5 microM in serum-free cell and human whole blood cultures, respectively) while sparing the synthesis of 6-keto-PGF(1alpha) (PGF(1alpha)) and PGF(2alpha). In contrast, as expected, the selective COX-2 inhibitor, SC-236, inhibited PGE(2), PGF(1alpha) and PGF(2alpha) synthesis. This profile of mPGES-1 inhibition, distinct from COX-2 inhibition in cells, validates mPGES-1 as an attractive target for therapeutic intervention.

Are 5-HT2 antagonists endowed with anxiolytic properties in rodents?

The precise role of serotonin (5-HT) in anxiety remains unclear. We report here on the effects of RP 62203, a new 5-HT2 antagonist, and ritanserin in different animal models of anxiety. In the elevated plus-maze in mice, RP 62203 increased dose-dependently the percentage of entries onto, and time spent on open arms, over the dose range 0.25-4 mg.kg-1 p.o. By contrast, ritanserin was ineffective up to the dose of 4 mg.kg-1 p.o. In addition, both compounds were tested against the anxiogenic compound FG 7142 (20 mg.kg-1, i.p.) in the plus-maze test in mice and via electrocorticographic recordings (ECoG) in rats. The anxiolytic effect of RP 62203 is antagonized by FG 7142 at a dose devoid of anxiogenic properties. A similar interaction between RP 62203 and FG 7142 is observed in ECoG studies. In contrast, ritanserin seemed to potentiate the anxiogenic and awakening activities of FG 7142. These results demonstrate that RP 62203, a selective 5-HT2 antagonist, possesses anxiolytic properties in rodents suggesting that 5-HT2 receptors are involved in the control of anxiety.