Blood Triglyceride and High-Density Lipoprotein Levels Are Associated with Plasma Amyloid-β Transport: A Population-Based Cross-Sectional Study.

BACKGROUND Studies have found that blood lipids are associated with plasma amyloid-β (Aβ) levels, but the underlying mechanism is still unclear. Two Aβ transporters, soluble form of low-density lipoprotein receptor related protein-1 (sLRP1) and soluble receptor of advanced glycation end products (sRAGE), are crucial in peripheral Aβ transport. OBJECTIVE The aim was to investigate the effects of lipids on the relationships between plasma Aβ and transporter levels. METHODS This study included 1,436 adults aged 40 to 88 years old. Blood Aβ, sLRP1, sRAGE, and lipid levels were measured. Univariate and multivariate analyses were used to analyze the relationships between lipids and plasma Aβ, sLRP1, and sRAGE. RESULTS After adjusting for all possible covariates, high-density lipoprotein (HDL-c) was positively associated with plasma Aβ 42 and sRAGE (β= 6.158, p = 0.049; β= 121.156, p <  0.001, respectively), while triglyceride (TG) was negatively associated with plasma Aβ 40, Aβ 42, and sRAGE (β= -48.389, p = 0.017; β= -11.142, p = 0.020; β= -147.937, p = 0.003, respectively). Additionally, positive correlations were found between plasma Aβ and sRAGE in the normal TG (Aβ 40: β= 0.034, p = 0.005; Aβ 42: β= 0.010, p = 0.001) and HDL-c groups (Aβ 40: β= 0.023, p = 0.033; Aβ 42: β= 0.008, p = 0.002) but not in the high TG and low HDL-c groups. CONCLUSION Abnormal levels of TG and HDL-c are associated with decreased Aβ and sRAGE levels. Positive correlations between plasma Aβ and sRAGE were only found in the normal TG and HDL-c groups but not in the high TG and low HDL-c groups. These results indicated that dyslipidemia contributing to plasma Aβ levels might also be involved in peripheral Aβ clearance.