EGCG Promotes Aβ Clearance of Microglia Through Blockage of the HDAC6-PI3K/AKT/mTOR Signalling Axis Followed by Autophagy Activation
10.13471/j.cnki.j.sun.yat-sen.univ（med.sci）.2025.0313
- VernacularTitle:EGCG阻断HDAC6-PI3K/AKT/mTOR轴以激活自噬促进小胶质细胞清除Aβ
- Author:
Yu LIN
1
;
Kaiwen HUANG
1
;
Honghai HONG
2
;
Dan ZHU
2
;
Yousheng MO
1
;
Dongli LI
1
;
Shuhuan FANG
1
Author Information
1. Science and Technology Innovation Center， Guangzhou University of Chinese Medicine， Guangzhou 510405，China
2. Department of Clinical Laboratory， The Third Affiliated Hospital of Guangzhou Medical University， Guangzhou 511436 ，China
- Publication Type:Journal Article
- Keywords:
epigallocatechin gallate;
Alzheimer's disease;
amyloid β-protein;
microglia;
autophagy;
histone deacetylase 6
- From:
Journal of Sun Yat-sen University(Medical Sciences)
2025;46(3):486-497
- CountryChina
- Language:Chinese
-
Abstract:
ObjectiveTo clarify whether epigallocatechin gallate （EGCG） is involved in the clearance of amyloid β-protein （Aβ） and autophagy induction by microglia， so as to explore the potential mechanisms of EGCG in the prevention and treatment of Alzheimer's disease （AD）. MethodsSix-month-old APP/PS1 mice were randomly divided into model and EGCG groups， with some additional wild type （WT） mice as the control group， each group consisting of 15 mice. The EGCG group received continuous gavage administration［5 mg/（kg·d）］ for 8 weeks， followed by the open field test and Y-maze to assess the learning and memory abilities of the mice. Thioflavin-S staining was used to evaluate the content and distribution of amyloid β-protein （Aβ）in the brain parenchyma of the mice， and immunofluorescence was employed to detect the expression levels of Aβ1-42， glial fibrillary acidic protein （GFAP）， and ionized calcium-binding adapter molecule 1 （Iba1） in the hippocampal tissue of the mice. Additionally， N9 mouse microglial cells were induced with 20 µmol/L Aβ1-42， and the cell viability was measured after treatment with different concentrations of EGCG （5 µmol/L， 10 µmol/L， 20 µmol/L）. Western blotting was used to detect the levels of Aβ1-42， low density lipoprotein receptor-related protein 1（LRP1）， receptor for advanced glycation endproducts （RAGE）， amyloid precursor protein （APP）， insulin degrading enzyme （IDE）， neprilysin （NEP）， microtubule associated protein 1 hydrogen chain 3（LC3）-Ⅱ/LC3-Ⅰ， phosphatidylinositol 3-hydroxy kinase（PI3K）， p-PI3K， protein kinase B （AKT）， p-AKT， mammalian target of rapamycin （mTOR）， p-mTOR， and histone deacetylase 6（HDAC6）. Finally， through the co-culture of microglial cells and neuronal SH-SY5Y cells， cell viability and Caspase-3 levels were measured to verify the protective effect of EGCG-mediated Aβ clearance on neurons. ResultsEGCG increased the activity time and frequency of APP/PS1 mice in the central area of the open field （P<0.05）， and enhanced the percentage of alternation in the Y-maze test （P<0.01）； EGCG reduced Aβ deposition in the hippocampal tissue of APP/PS1 mice and increased the number of microglia； in vitro experiments showed that EGCG improved the survival rate of Aβ-induced N9 cells （P<0.01）， upregulated RAGE activity （P<0.05）， and promoted the internalization and phagocytosis of Aβ （P<0.01）. ECGC activated microglial autophagy by downregulating the level of HDAC6 （P<0.05）， inhibiting the phosphorylation of PI3K， AKT， mTOR （P<0.001）， and increasing the LC3-Ⅱ/LC3-I ratio （P<0.001）； EGCG improved the survival rate of SH-SY5Y cells （P<0.05） and reduced the activity of Caspase-3 （P<0.01） by clearing Aβ1-42 through microglia， and had a protective effect on neurons. ConclusionEGCG activates microglial autophagy to clear Aβ by targeting and inhibiting the HDAC6-PI3K/AKT/mTOR axis.
