Optimization of sTREM2 ELISA to understand the role of microglia in Alzheimer's disease

Abstract

Triggering receptor expressed on myeloid cells 2 (TREM2), a microglial receptor, plays a crucial role in the innate immune response in Alzheimer's disease (AD), aiding in the clearance of amyloid beta plaques and preventing Tau propagation. As a result of cleavage, soluble TREM2 (sTREM2) can be detected in human cerebrospinal fluid (CSF) and plasma across the AD continuum, serving as a biomarker of microglial activity. This study aimed to optimize a Meso Scale Discovery (MSD) enzyme-linked immunosorbent assay (ELISA) for the quantification of sTREM2 in biofluids. Validation parameters considered for optimization included signal-to-noise (S/N) ratio, background noise and coefficient of variation (CV%). Optimal capture and detection antibodies concentrations were determined to be 15.63 ng/ml and 0.125 μg/ml, respectively, resulting in improved assay performance. Despite higher background noise, storing MSD reagents at 4ºC and the use of MSD Small Spot coated-streptavidin plates improved the S/N ratio. Finally, a concentration of 0.0625 μg/ml of secondary antibody rendered a lower background and higher S/N ratio. These optimizations significantly increased the sensitivity and accuracy of the immunoassay, making it a promising tool for the early detection of pathological alterations linked to AD.