Advanced Glycation End Products (AGEs) Cause Pro-atherogenic Changes in Cholesterol Transport: A Possible Mechanism for Cardiovascular Risk in Diabetes

Gamez, JD, Voloshyna I, Littlefield MJ, Castro-Magana M, Reiss AB
Source: Other
Publication Date: (2014)
Issue: S11:005: ePub
Research Area:
Basic Research
Cells used in publication:
Species: human
Tissue Origin: blood
Macrophage, human
Species: human
Tissue Origin: blood
Mononuclear, peripheral blood, human
Species: human
Tissue Origin: blood
Purpose of Study: Hyperglycemia is the major cause of diabetic vascular complications. AGEs accumulate under hyperglycemic conditions and contribute to atherosclerosis. ATP binding cassette transporters (ABC) A1, G1, and cholesterol 27-hydroxylase (27-OHase) facilitate removal of cholesterol from macrophages and constitute a first line of defense in the prevention of atherosclerosis. ABCA1 and G1 are known to be suppressed by AGEs. Here we investigated the effects of AGEs on the expression of reverse cholesterol transport (RCT) proteins and scavenger receptors in THP-1 human macrophages. Methods Used: THP-1 monocytes (106 cells/ml), differentiated into adherent macrophages (phorbol dibutyrate, 100nM, 48 h) were incubated for 1h, 3h or 5h (370C, 5% C02) ± 50 ug/ml of the AGE carboxymethyl lysine (CML)-human serum albumin (HAS). 1µg of total RNA was used per condition for QRT-PCR. 27-OHase, ABCA1 and G1 were measured to assess cholesterol efflux. CD36, SRA1 and LOX1 to assess influx. PCR results were confirmed by Western blot. Summary of Results: Expression of ABCA1 and G1 diminished in the presence of AGEs. For the first time, we demonstrate that, AGEs decrease message and protein level of 27-OHase (by 54.5±2.9% and 48.7±9.23%, respectively). AGE products upregulated the CD36 receptor, to 156.5±5.9% for mRNA and 176.78±12.2% for protein, versus untreated. Expression of SRA1 and LOX-1 were unchanged. Conclusions: AGEs contribute to the process of accelerated atherosclerosis in diabetes by promoting lipid overload through downregulation of 27-OHase and other genes involved in cholesterol transport. Our present study provides a novel negative effect of AGEs on lipid handling.