Autophagy activation by Terminalia chebula Retz. reduce Aβ generation by shifting APP processing toward non-amyloidogenic pathway in APPswe transgenic SH-SY5Y cells

Alzheimer's disease (AD) is the most common neurodegenerative disease. Deposition of amyloid β plaques (Aβ) is a central hallmark of AD. Accumulating evidence suggest that shifting amyloid precursor protein (APP) metabolism pathway to non-amyloidogenic ways and inducing autophagy play key roles in AD pathology. In published reports, there is no research on the APP metabolic process of Terminalia chebula Retz. (T. Chebula).The study aims to assess the effects of T. Chebula in AD transgenic SH-SY5Y cells to determine its underlying mechanisms on reducing Aβ level by regulating APP metabolic process.The effects of T. Chebula water extract (TWE) on APPswe transgenic SH-SY5Y cells were analyzed by cell viability. ELISA used to quantify extracellular Aβ1-40 and Aβ1-42 generations. Western blot and RT-PCR assays were chosen to detect the expression of proteins and genes. The acridine orange (AO) stain was used to label autophagic-vesicles.Treatment with TWE significantly suppressed the Aβ1-40 and Aβ1-42 generations of APPswe transgenic cells. TWE inhibited amyloidogenic pathway by reducing BACE1 expression, and promote non-amyloidogenic pathway by inducing ADAM10 level of APP metabolism. Additionally, TWE induced autophagy in APPswe transgenic cells involved in APP metabolism to shift the balance to non-amyloidogenic pathway.In summary, our finding first time expounded that TWE can inhibit the generation of Aβ1-40 and Aβ1-42 in APPswe transgenic SH-SY5Y cells, which were regulated APP metabolism tends to non-amyloid metabolism pathway and mediated by autophagy. The results presented a novel finding for AD treatment of traditional natural medicines.