Soluble TREM2 in body fluid in Alzheimer's disease and Parkinson's disease

Previous studies showed conflicting results regarding soluble triggering receptor expressed on myeloid cells 2 (sTREM2) level alteration in body fluid in Alzheimer's disease (AD) and Parkinson's disease (PD).

We applied the STATA 12.0 software to compute standard mean difference (SMD) and 95% confidence interval (CI).

The study showed elevated sTREM2 level in cerebrospinal fluid (CSF) in AD, mild cognitive impairment (MCI), and preclinical AD (pre-AD) patients, compared to healthy controls (HCs) with random effects models (AD: SMD 0.28, 95% CI 0.12 to 0.44, I² = 77.6%, p < 0.001; MCI: SMD 0.29, 95% CI 0.09 to 0.48, I² = 89.7%, p < 0.001; pre-AD: SMD 0.24, 95% CI 0.00 to 0.48, I² = 80.8%, p < 0.001). The study showed no significant difference in sTREM2 level in plasma between AD patients and HCs with a random effects model (SMD 0.06, 95% CI - 0.16 to 0.28, I² = 65.6%, p = 0.008). The study showed no significant difference in sTREM2 level in CSF or plasma between PD patients and HCs with random effects models (CSF: SMD 0.33, 95% CI - 0.02 to 0.67, I² = 85.6%, p < 0.001; plasma: SMD 0.37, 95% CI - 0.17 to 0.92, I² = 77.8%, p = 0.011).

In conclusion, the study highlighted the CSF sTREM2 as a promising biomarker in the different clinical stages of AD. More studies were essential to explore the CSF and plasmatic concentrations of sTREM2 alteration in PD.