The microRNA‐1908 up‐regulation in the peripheral blood cells impairs amyloid clearance by targeting ApoE

Objective To give a new insight into the mechanism of ApoE dysregulation and microRNA‐1908 in Alzheimer's disease (AD). Methods Plasma ApoE levels were measured in 20 AD patients and 20 healthy controls. THP‐1 was maintained in RPMI1640 with 10% fetal bovine serum. Quantitative real‐time polymerase chain reaction was performed to detect 13‐microRNA and ApoE mRNA in cultured cell lines. Enzyme‐linked immunosorbent assay was used to measure human ApoE in the plasma or culture medium of cell lines and also used to quantify the human Aβ42 in the culture medium of cell lines. Results We found plasma ApoE level reduced in AD patients (2.28 vs 3.78 μg/mL, P  < .001), and microRNA‐1908 was up‐regulated in AD patients and was negatively associated with plasma ApoE ( r  = −0.32, P  = .012). In human macrophage cell line THP‐1 and astrocytoma cell line U87, microRNA‐1908 could inhibit the mRNA and protein levels of ApoE by targeting its 3′untranslated region. Consistently, microRNA‐1908 inhibits the ApoE‐mediated Aβ clearance. Conclusions Our study provides new insight into the mechanism of ApoE dysregulation in AD patients, and microRNA‐1908 might be a therapeutic target for AD treatment.