ppi-2458 and Disease-Models--Animal

To determine whether blood vessel growth at the onset of resolving synovitis leads to its subsequent persistence and whether inhibiting this angiogenesis at the onset of persistent inflammation leads to its subsequent resolution.. Inflammation and angiogenesis were induced by injection of 0.03% carrageenan and/or 6 pmoles of fibroblast growth factor 2 (FGF-2) into rat knees. A brief treatment with the angiogenesis inhibitor PPI-2458 (5 mg/kg orally on alternate days) was administered 1 day before and up to 3 days after synovitis induction. Controls comprised naive and vehicle-treated rats. Synovial angiogenesis was measured using the endothelial cell proliferation index, and inflammation was determined by measuring joint swelling and macrophage percentage area. Data are presented as the geometric mean (95% confidence interval).. Intraarticular injection of 0.03% carrageenan into rat knees produced acute synovitis, which was not associated with synovial angiogenesis and which resolved within 29 days. Injection of FGF-2 (6 pmoles) induced synovial angiogenesis without significant synovitis. Stimulation of angiogenesis with FGF-2 at the time of carrageenan injection was followed by synovitis that persisted for 29 days. Persistence of carrageenan/FGF-2-induced synovitis was prevented by systemic administration of 3 doses of the angiogenesis inhibitor PPI-2458 during the acute phase.. Our findings indicate that conversion of acute inflammation to chronic inflammation may be due to the stimulation of angiogenesis, and brief antiangiogenic treatment during the acute phase of synovitis may prevent its subsequent progression. Clinical studies will be needed to determine whether brief antiangiogenic treatment may reduce the burden of inflammatory joint diseases such as rheumatoid arthritis by facilitating the resolution of early synovitis.

Topics: Angiogenesis Inhibitors; Animals; Carrageenan; Cell Proliferation; Disease Models, Animal; Drug Therapy, Combination; Endothelium, Vascular; Epoxy Compounds; Fibroblast Growth Factor 2; Hindlimb; Injections, Intra-Articular; Joints; Macrophages; Male; Neovascularization, Pathologic; Rats; Rats, Wistar; Synovial Membrane; Synovitis; Valine

To determine the disease-modifying activity and mechanism of action of the orally available methionine aminopeptidase type 2 inhibitor, [(1R)-1-carbamoyl-2-methyl-propyl]-carbamic acid-(3R,4S,5S,6R)-5-methoxy-4-[(2R,3R)-2-methyl-3-(3-methyl-but-2-enyl)-oxiranyl]-1-oxa-spiro [2.5] oct-6-yl ester (PPI-2458), in a rat model of peptidoglycan-polysaccharide (PG-PS)-induced arthritis.. Arthritis was induced in rats by administration of PG-PS, causing tarsal joint swelling and histopathologic changes characteristic of rheumatoid arthritis (RA). PPI-2458, a potent irreversible methionine aminopeptidase type 2 inhibitor, was administered orally every other day at 1, 5, or 10 mg/kg.. In an in vitro osteoclastogenesis model, PPI-2458 potently inhibited osteoclast differentiation and bone resorption. In the rat PG-PS arthritis model, PPI-2458 afforded significant protection against established disease after therapeutic dosing. This in vivo activity of PPI-2458 was linked to the inhibition of methionine aminopeptidase type 2. Histopathologic assessment of affected joints showed improvement in processes of inflammation, bone resorption, and cartilage erosion, associated with significant improvement in all clinical indices. The protective effects of PPI-2458 against bone destruction in vivo, including the structural preservation of affected hind joints, correlated with improvements in bone histomorphometric markers, as determined by microfocal computed tomography and a significant decrease in systemic C-telopeptide of type I collagen, suggesting decreased osteoclast activity in vivo. Moreover, PPI-2458 prevented cartilage erosion as shown by a significant decrease in systemic cartilage oligomeric matrix protein.. The findings of this study suggest that PPI-2458 exerts disease-modifying activity in experimental arthritis through its direct inhibition of several pathophysiologic processes of this disease. These results provide a rationale for assessing the potential of PPI-2458 as a novel RA therapy.

Topics: Aminopeptidases; Animals; Arthritis, Rheumatoid; Bone Resorption; Cell Differentiation; Cells, Cultured; Disease Models, Animal; Enzyme Inhibitors; Epoxy Compounds; Female; Glycoproteins; Humans; Joints; Osteoclasts; Peptidoglycan; Polysaccharides; Rats; Rats, Inbred Lew; Severity of Illness Index; Valine