11: THE ADENOSINE A2A RECEPTOR AGONIST UK-432,097 STIMULATES ANTI-ATHEROGENIC REVERSE CHOLESTEROL TRANSPORT PROTEINS IN THP-1 HUMAN MACROPHAGES

Purpose of Study Methotrexate (MTX) is an anti-rheumatic drug with atheroprotective properties mediated through adenosine release and activation of the adenosine A 2A receptor (A 2A R). A 2A R ligation increases reverse cholesterol transport via upregulation of cholesterol efflux proteins ATP-binding cassette transporter (ABC)A1 and ABCG1, liver X receptor (LXR) and cholesterol 27-hydroxylase. MTX is non-specific and associated with adverse effects on liver and kidney. Therefore, this study examines the anti-atherogenic efficacy of a specific A 2A R agonist, UK-432,097, a drug with an established safety profile in humans. Methods Used THP-1 human macrophages were incubated in the following conditions: (1) RPMI media (untreated control); (2) dimethyl sulfoxide vehicle control; (3) UK-432,097 (100 nM); (4) ZM-241385 (1 µM) (A 2A R antagonist)+UK-432,097 (100 nM). Gene expression analysis was performed using QRT-PCR for cholesterol efflux genes, normalized to the housekeeping gene GAPDH. Western blotting was performed using specific antibodies. All data were analyzed by one-way ANOVA with P values Summary of Results Following 6 h exposure to UK-432,097, mRNA and protein levels of ABCA1 increased by 88.75±5.4% and by 56.34±12.4% above control (P 2A R blockade with ZM-241385 negated the effect of UK-432,097. UK-432,097 decreased oxidized LDL uptake by 28.9% in THP-1 macrophages (P Conclusions This study demonstrates that UK-432,097 increases anti-atherogenic reverse cholesterol transport proteins with concomitant reduction in oxidized lipid accumulation in THP-1 macrophages. Since MTX is already being used in clinical trials to reduce cardiovascular risk, our results encourage further studies of specific A 2A R agonists as cardioprotective treatment in high risk individuals.