RESUMO
A structural survey of pyrazolopyridine-pyridazinone phosphodiesterase (PDE) inhibitors was made with a view to optimization of their dual PDE3/4-inhibitory activity for respiratory disease applications. These studies identified (-)-6-(7-methoxy-2-trifluoromethylpyrazolo[1,5-a]pyridine-4-yl)-5-methyl-4,5-dihydro-3-(2H)-pyridazinone (KCA-1490, compound 2ac) as a compound with potent combined bronchodilatory and anti-inflammatory activity and an improved therapeutic window over roflumilast.
Assuntos
Anti-Inflamatórios não Esteroides/farmacologia , Broncodilatadores/farmacologia , Desenho de Fármacos , Inibidores da Fosfodiesterase 3/farmacologia , Inibidores da Fosfodiesterase 4/farmacologia , Pirazóis/farmacologia , Piridinas/farmacologia , Animais , Anti-Inflamatórios não Esteroides/síntese química , Anti-Inflamatórios não Esteroides/química , Broncodilatadores/síntese química , Broncodilatadores/química , Nucleotídeo Cíclico Fosfodiesterase do Tipo 3/metabolismo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Relação Dose-Resposta a Droga , Avaliação Pré-Clínica de Medicamentos , Cobaias , Estrutura Molecular , Inibidores da Fosfodiesterase 3/síntese química , Inibidores da Fosfodiesterase 3/química , Inibidores da Fosfodiesterase 4/síntese química , Inibidores da Fosfodiesterase 4/química , Pirazóis/síntese química , Pirazóis/química , Piridinas/síntese química , Piridinas/química , Ratos , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
BACKGROUND: A novel immunomodulator, KRP-203, the molecular structure of which has some similarity to FTY720, has been developed for use in organ transplantation. The present study was designed to investigate the potency and safety of KRP-203 on allograft survival against both acute and chronic rejection in rat skin and heart transplantation. METHODS AND RESULTS: KRP-203 significantly prolonged skin or heart allograft survival of a minor histocompatibility complex (mHC)-disparate (LEW to F344) rat combination. Histopathological and immunohistochemical analysis at 100 days after mHC-disparate rat heart transplantation revealed that KRP-203 treatment significantly inhibited infiltration of inflammatory cells, including macrophages and T cells; expression of endothelin-1 and transforming growth factor-beta1; and IgG deposition and eventually attenuated neointimal formation and myocardial fibrosis. KRP-203 also prolonged heart allograft survival in a major histocompatibility complex (MHC)-incompatible (DA to LEW) rat combination, but the efficacy was not as significant. However, KRP-203 combined with a subtherapeutic dose of cyclosporin A synergistically prolonged the heart allograft survival. Flow cytometric analysis demonstrated that KRP-203 reduced the number of peripheral blood mononuclear cells (lymphocytes and monocytes) but not granulocytes and enhanced lymphocyte homing into peripheral lymph nodes. The influence of KRP-203 on heart rate changes in Hartley guinea pigs was examined. KRP-203 had less of a tendency to cause bradycardia than FTY720. CONCLUSIONS: These findings demonstrated that KRP-203 prolonged skin and heart allograft survival and significantly attenuated chronic rejection and bradycardia as an adverse effect. Therefore, KRP-203 offers considerable potential as a novel therapeutic immunosuppressant in patients with organ transplantation.