The Jekyll and Hyde of TREM2

Area of Science:

• Neuroscience
• Genetics
• Alzheimer's Disease Research

Background:

• Alzheimer's disease (AD) involves complex pathologies, including amyloid-beta (Aβ) plaques and tau tangles.
• The TREM2 gene, particularly the R47H variant, is a significant genetic risk factor for late-onset AD.
• Microglia, the brain's immune cells, play a crucial role in AD pathogenesis, with TREM2 signaling influencing their function.

Purpose of the Study:

• To investigate the specific role of the TREM2^R47H variant in tau-mediated neurodegeneration.
• To explore the context-dependent functions of TREM2 in different Alzheimer's disease pathologies (Aβ vs. tau).

Main Methods:

• Utilized a mouse model of tauopathy to study tau-mediated neurodegeneration.
• Assessed the impact of the TREM2^R47H variant on microglial responses and neuroinflammation in the context of tau pathology.

Main Results:

• Demonstrated a potential neuroprotective effect of the TREM2^R47H variant against tau-mediated neurodegeneration.
• Highlighted that microglial responses to TREM2 signaling are context-dependent, differing between Aβ and tau pathologies.
• Suggests TREM2 may have opposing roles in Aβ-driven versus tau-driven Alzheimer's disease processes.

Conclusions:

• The TREM2^R47H variant may confer protection against tau pathology, contrary to its established risk association with overall AD.
• Microglial function, modulated by TREM2, exhibits distinct behaviors in response to different AD pathological hallmarks.
• TREM2's role in Alzheimer's disease appears to be dichotomous, potentially acting antagonistically in Aβ and tau pathways.