Established Beta Amyloid Pathology Is Unaffected by TREM2 Elevation in Reactive Microglia in an Alzheimer's Disease Mouse Model

Effects of electroacupuncture on DNA methylation of the TREM2 gene in senescence-accelerated mouse prone 8 mice

OBJECTIVE

To explore the mechanism by which electroacupuncture (EA) upregulates triggering receptor expressed on myeloid cells 2 (TREM2) protein in the hippocampus of Alzheimer's disease (AD) model animals from the perspective of TREM2 DNA methylation.

METHODS

In total, 24 eight-month-old senescence-accelerated mouse prone 8 (SAMP8) mice were divided into an (untreated) AD group (n = 8), donepezil group (receiving donepezil treatment, n = 8) or EA group (receiving an EA intervention, n = 8). A healthy control group comprising 8-month-old senescence-accelerated mouse resistant 1 (SAMR1) mice (n = 8) was also included. Western blotting, bisulfite sequencing, and oxidative bisulfite sequencing were applied to test the relative expression of TREM2 protein and the methylation levels of the TREM2 gene.

RESULTS

EA significantly upregulated the relative expression of TREM2 protein (p < 0.01), downregulated the 5-methylcytosine level (p < 0.01) and upregulated the 5-hydroxymethylcytosine level (p < 0.05) in the hippocampus.

CONCLUSION

Downregulation of 5-methylcytosine levels and upregulation of 5-hydroxymethylcytosine levels in the TREM2 gene might be the mechanism by which EA promotes the expression of TREM2 protein.