Youth-associated protein TIMP2 regulates microglial state and function in healthy and aged mice

Hemmer, Philippi, Ferreira, et al.

1. 01

   TIMP2 is elevated in very young human and mouse plasma and declines rapidly into adulthood and old age

2. 02

   TIMP2 deletion exacerbated aging-associated microglial activation, lysosomal marker changes and altered myelin phagocytosis

3. 03

   In vivo microdialysis showed elevated stress and inflammatory proteins in brain extracellular space after TIMP2 loss

4. 04

   TIMP2 treatment of aged mice decreased microglial activation and reduced the proportion of proinflammatory microglia

5. 05

   TIMP2 treatment enhanced microglial phagocytosis of physiological substrates

6. 06

   Identifies a specific, druggable young-plasma factor acting on brain innate immunity rather than on neurons directly

Study Design

Preclinical Study

Sample Size

Not reported

Study Duration

Not specified (aged mouse cohorts)

Methodology

Conditional and global TIMP2 deletion in mice with microglial transcriptomic profiling, lysosomal and phagocytosis assays, and in vivo microdialysis of brain extracellular space; cell-pool-specific TIMP2 deletion to localise the source; TIMP2 protein administration to aged mice with reversal endpoints.

Limitations

Mouse-only; no human exposure or clinical endpoint. Recombinant TIMP2 is not available as a human therapeutic and no human dosing, route or safety data exist. TIMP2 is a matrix metalloproteinase inhibitor with plausible effects on tumour invasion and matrix remodelling that would require characterisation before any human protocol. Endpoints are cellular and biochemical, not cognitive or survival.