RESUMEN

BACKGROUND: The specific role of microglia on Aß-mediated neurotoxicity is difficult to assign in vivo due to their complicated environment in the brain. Therefore, most of the current microglia-related studies employed the isolated microglia. However, the previous in vitro studies have suggested either beneficial or destructive function in microglia. Therefore, to investigate the phenotypes of the isolated microglia which exert activity of neuroprotective or destructive is required. RESULTS: The present study investigates the phenotypes of isolated microglia on protecting neuron against Aß-mediated neurotoxicity. Primary microglia were isolated from the mixed glia culture, and were further cultured to distinct phenotypes, designated as proliferating amoeboid microglia (PAM) and differentiated process-bearing microglia (DPM). Their inflammatory phenotypes, response to amyloid ß (Aß), and the beneficial or destructive effects on neurons were investigated. DPM may induce both direct neurotoxicity without exogenous stimulation and indirect neurotoxicity after Aß activation. On the other hand, PAM attenuates Aß-mediated neurotoxicity through Aß phagocytosis and/or Aß degradation. CONCLUSIONS: Our results suggest that the proliferating microglia, but not the differentiated microglia, protect neurons against Aß-mediated neurotoxicity. This discovery may be helpful on the therapeutic investigation of Alzheimer's disease.

Asunto(s)

Péptidos beta-Amiloides/metabolismo , Péptidos beta-Amiloides/toxicidad , Corteza Cerebral/metabolismo , Microglía/metabolismo , Neuronas/metabolismo , Animales , Proliferación Celular , Células Cultivadas , Corteza Cerebral/citología , Ratones , Microglía/citología , Neuronas/citología , Fenotipo , Ratas , Ratas Sprague-Dawley

RESUMEN

BACKGROUND: Microglial inflammation may significantly contribute to the pathology of Alzheimer's disease. To examine the potential of Cudrania cochinchinensis to ameliorate amyloid ß protein (Aß)-induced microglia activation, BV-2 microglial cell line, and the ramified microglia in the primary glial mixed cultured were employed. RESULTS: Lipopolysaccharide (LPS), Interferon-γ (IFN-γ), fibrillary Aß (fAß), or oligomeric Aß (oAß) were used to activate microglia. LPS and IFN-γ, but not Aßs, activated BV-2 cells to produce nitric oxide through an increase in inducible nitric oxide synthase (iNOS) expression without significant effects on cell viability of microglia. fAß, but not oAß, enhanced the IFN-γ-stimulated nitric oxide production and iNOS expression.The ethanol/water extracts of Cudrania cochinchinensis (CC-EW) and the purified isolated components (i.e. CCA to CCF) effectively reduced the nitric oxide production and iNOS expression stimulated by IFN-γ combined with fAß. On the other hand, oAß effectively activated the ramified microglia in mixed glial culture by observing the morphological alteration of the microglia from ramified to amoeboid. CC-EW and CCB effectively prohibit the Aß-mediated morphological change of microglia. Furthermore, CC-EW and CCB effectively decreased Aß deposition and remained Aß in the conditioned medium suggesting the effect of CC-EW and CCB on promoting Aß clearance. Results are expressed as mean ± S.D. and were analyzed by ANOVA with post-hoc multiple comparisons with a Bonferroni test. CONCLUSIONS: The components of Cudrania cochinchinensis including CC-EW and CCB are potential for novel therapeutic intervention for Alzheimer's disease.

Asunto(s)

Péptidos beta-Amiloides/metabolismo , Microglía/efectos de los fármacos , Moraceae/química , Extractos Vegetales/farmacología , Enfermedad de Alzheimer/tratamiento farmacológico , Enfermedad de Alzheimer/metabolismo , Animales , Células Cultivadas , Interferón gamma/metabolismo , Microglía/metabolismo , Óxido Nítrico/metabolismo , Óxido Nítrico Sintasa de Tipo II/metabolismo , Fragmentos de Péptidos/metabolismo , Ratas , Ratas Sprague-Dawley

RESUMEN

Flemingia macrophylla (Leguminosae) is a popular traditional remedy used in Taiwan as anti-inflammatory, promoting blood circulation and antidiabetes agent. Recent study also suggested its neuroprotective activity against Alzheimer's disease. Therefore, the effects of F. macrophylla on Aß production and degradation were studied. The effect of F. macrophylla on Aß metabolism was detected using the cultured mouse neuroblastoma cells N2a transfected with human Swedish mutant APP (swAPP-N2a cells). The effects on Aß degradation were evaluated on a cell-free system. An ELISA assay was applied to detect the level of Aß1-40 and Aß1-42. Western blots assay was employed to measure the levels of soluble amyloid precursor protein and insulin degrading enzyme (IDE). Three fractions of F. macrophylla modified Aß accumulation by both inhibiting ß-secretase and activating IDE. Three flavonoids modified Aß accumulation by activating IDE. The activated IDE pool by the flavonoids was distinctly regulated by bacitracin (an IDE inhibitor). Furthermore, flavonoid 94-18-13 also modulates Aß accumulation by enhancing IDE expression. In conclusion, the components of F. macrophylla possess the potential for developing new therapeutic drugs for Alzheimer's disease.