Does Soluble TREM2 Protect Against Alzheimer's Disease?

Area of Science:

• Neuroscience
• Immunology
• Genetics

Background:

• Triggering Receptor Expressed in Myeloid Cells 2 (TREM2) is crucial for microglial function in Alzheimer's disease (AD).
• TREM2 mutations, like R47H, significantly elevate AD risk.
• TREM2 can be shed to form soluble TREM2 (sTREM2), a potential biomarker and therapeutic target.

Purpose of the Study:

• To investigate the protective role of soluble TREM2 (sTREM2) against amyloid pathology in Alzheimer's disease (AD).
• To differentiate the effects of sTREM2 from full-length TREM2 in AD pathogenesis.
• To explore the therapeutic potential of modulating sTREM2 levels in AD.

Main Methods:

• In vitro studies assessing sTREM2 binding to amyloid beta (Aβ) oligomers and fibrils.
• Analysis of AD brain pathology in relation to TREM2 mutations (R47H vs. wild-type).
• In vivo experiments using amyloid mouse models with wild-type sTREM2 administration.

Main Results:

• Wild-type sTREM2 inhibits Aβ oligomerization and fibrillization, reducing neurotoxicity in vitro.
• R47H sTREM2 promotes Aβ fibrillization and is associated with increased neuritic pathology in AD brains.
• Administration of wild-type sTREM2 ameliorates amyloid pathology in mouse models of AD.
• Cerebrospinal fluid sTREM2 levels correlate with AD progression, with higher levels indicating slower disease advancement.

Conclusions:

• sTREM2 exhibits protective functions against amyloid pathology and neurotoxicity in AD models.
• The R47H TREM2 mutation leads to a gain-of-toxic-function in sTREM2, promoting Aβ aggregation.
• Elevating sTREM2 levels could represent a promising therapeutic strategy for Alzheimer's disease.