RESUMEN
Evidence gathered over the last two decades suggests that beta amyloid (Abeta), the predominant proteinaceous component of senile plaques, plays an early and critical role in the etiology and pathogenesis of Alzheimer's disease (AD). Thus, it is reasonable to hypothesize that compounds capable of reducing the accumulation of Abeta may be of value therapeutically. Additionally, compounds that influence Abeta accumulation may be useful as tools to further dissect the cellular pathways that regulate Abeta production and accumulation. To screen for compounds that affect Abeta levels, we have established high throughput, cell-based assays capable of the sensitive and selective detection of Abeta40 in parallel with the more amyloidogenic form of the peptide, Abeta42. To validate the approach, we examined the effects of several compounds previously identified to influence Abeta accumulation. Analysis of peptide accumulation following treatment with these compounds showed results similar to those previously published. Currently, we are using this assay to screen drugs that have already received FDA approval for the treatment of other diseases and over-the-counter natural product extracts. If compounds such as these can be identified that lower Abeta in the brain, they may represent one of the fastest and most cost effective methods to therapy.
Asunto(s)
Enfermedad de Alzheimer/tratamiento farmacológico , Péptidos beta-Amiloides/análisis , Péptidos beta-Amiloides/efectos de los fármacos , Bioensayo/métodos , Células Cultivadas/efectos de los fármacos , Evaluación Preclínica de Medicamentos/métodos , Fármacos Neuroprotectores/farmacología , Enfermedad de Alzheimer/metabolismo , Enfermedad de Alzheimer/fisiopatología , Péptidos beta-Amiloides/metabolismo , Animales , Bioensayo/instrumentación , Células CHO/efectos de los fármacos , Células CHO/metabolismo , Técnicas de Cultivo de Célula , Supervivencia Celular/efectos de los fármacos , Supervivencia Celular/fisiología , Células Cultivadas/metabolismo , Cricetinae , Medios de Cultivo Condicionados/farmacología , Evaluación Preclínica de Medicamentos/instrumentación , Efectos Colaterales y Reacciones Adversas Relacionados con Medicamentos/metabolismo , Ensayo de Inmunoadsorción Enzimática/métodos , Humanos , Fragmentos de Péptidos/análisis , Fragmentos de Péptidos/efectos de los fármacos , Fragmentos de Péptidos/metabolismo , Reproducibilidad de los Resultados , Pruebas de Toxicidad/instrumentación , Pruebas de Toxicidad/métodosRESUMEN
The abnormal accumulation of the amyloid beta protein (Abeta) has been implicated as an early and critical event in the etiology and pathogenesis of Alzheimer's disease (AD). Compounds that reduce Abeta accumulation may therefore be useful therapeutically. In cell-based screens we detected a significant reduction in Abeta concentration after treatment with the phosphatidylinositol kinase inhibitors wortmannin and LY294002. To determine the effect of this class of compounds on in vivo Abeta accumulation, we administered wortmannin to the Tg2576 mouse model of AD. Oral administration of wortmannin over four months resulted in a significant, non-overlapping 40%-50% reduction in the number of senile plaques, one of the pathological hallmarks of AD. Sandwich ELISA analysis of formic acid extractable Abeta in the brain of treated animals indicates that both Abeta40 and the longer, more amyloidogenic form of the peptide, Abeta42, were significantly reduced. These data provide the first direct evidence that compounds identified by their ability to reduce Abeta concentration in vitro can reduce Abeta accumulation and deposition in the brain, thus establishing a basic paradigm for the identification and evaluation of additional compounds that lower Abeta accumulation.