Anti-atherogenic effects of the acyl-CoA:cholesterol acyltransferase inhibitor, avasimibe (CI-1011), in cultured primary human macrophages

详细信息    查看全文

• 作者：Rodriguez ; Annabelle ; Usher ; David C.
• 关键词：ACAT ; Foam cells ; Macrophages ; Apolipoprotein E
• 刊名：Atherosclerosis
• 出版年：2002
• 出版时间：March, 2002
• 年：2002
• 卷：161
• 期：1
• 页码：45-54
• 全文大小：211 K

文摘

Acyl-CoA:cholesterol acyltransferase (ACAT) inhibitors have been shown to reduce atherosclerotic lesions in animals; however, the mechanism(s) for this effect remains unclear. Therefore, we used cultured primary human monocyte-derived macrophages (HMMs) to examine the effect of the ACAT inhibitor, avasimibe (CI-1011), during foam cell formation and during cholesterol efflux from established foam cells. To examine the effect of CI-1011 on foam cell development, HMMs were incubated with aggregated acetylated LDL (ag-acLDL)±CI-1011 for 48 h. Total cholesterol (TC) was 29 % lower in HMMs incubated with ag-acLDL and CI-1011 compared with ag-acLDL (P<0.05). To determine if TC reduction was due to reduced ag-acLDL uptake by CI-1011, ¹²⁵I–acLDL binding at 4°C for 4 h to HMMs preincubated with acLDL or ag-acLDL, CI-1011, acLDL+CI-1011, or ag-acLDL+CI-1011 for 48 h was measured. Specific binding was 40 % lower in cells preincubated with acLDL+CI-1011, 52 % lower in cells preincubated with ag-acLDL+CI-1011 and 49 % lower in cells preincubated with CI-1011 compared with cells preincubated with acLDL (P<0.0003). Because CI-1011 appeared to directly affect acLDL binding, ¹²⁵I–acLDL (3–80 μg protein/ml) binding was done in HMMs preincubated with CI-1011 (0–10 μg/ml) for 48 h. The calculated B_max decreased in HMMs exposed to increasing concentrations of CI-1011, suggesting that CI-1011 altered scavenger receptor function and/or number. To examine the effects of CI-1011 on cholesterol efflux from established foam cells, we first examined whether CI-1011 was cytotoxic. HMMs were preincubated with ag-acLDL for 24 h, and then radiolabeled with [¹⁴C]adenine for 2 h (time zero). The radiolabeled cells were exposed to control RPMI medium or the same medium+HDL, CI-1011, or HDL+CI-1011 for 24 h. The release of [¹⁴C]adenine into the medium was not significantly different between cells exposed to RPMI, HDL, CI-1011, or HDL+CI-1011, suggesting that CI-1011 was not cytotoxic. Foam cells exposed to RPMI and CI-1011 (1–10 μg/ml) for 48 h showed time dependent reduction in cellular TC mass, with a corresponding increase in radiolabeled unesterified cholesterol into the medium. We then asked whether CI-1011 enhanced apoE mediated cholesterol efflux. Although cellular apoE increased between 2- and 7-fold in foam cells compared to control macrophages, apoE secreted into the medium was not significantly different between cells exposed to RPMI or CI-1011. Thus, CI-1011 exerted anti-atherogenic effects by reducing TC accumulation, inhibiting acLDL binding, and by limiting lipid storage in HMMs.