Abstract 14314: Macrophage ATP-Binding Cassette Transporter-A1 Protein Expression is Decreased in Human Aortic Atherosclerotic Plaques With Haptoglobin Genotype 2-2
Background: Macrophage membrane associated protein- ATP-binding cassette transporter A1 (ABCA1) mediates excess cholesterol egress from the cells into the High Density Lipoprotein (HDL) pathway. This may be linked to plaque regression through possible macrophage reverse cholesterol transport. Haptoglobin genotype 2-2 (Hp2-2) is associated with plaque progression due to impaired HDL pathway. We hypothesize that Hp2-2 plaques may have decreased ABCA1 receptor expression leading to impaired reverse cholesterol transport.
Method: Twenty three human aortic plaques (12 Hp2-2 plaques vs. 11 control plaques) were studied. All specimens were Hp genotyped from corresponding liver biopsy samples using RT-PCR. ABCA1 protein density was quantified using immunohistochemistry in 20 high power fields by computerized planimetry. AHA class, cap thickness, lipid core area and percent lipid core area were evaluated using H&E stain and planimetry.
Result: The ABCA1 protein expression was decreased in Hp2-2 plaques compared to control plaques (Figure). Fibrous cap thickness was decreased, and percent lipid core area was similar in both groups (Table).
Conclusion: Decreased expression of ABCA1 was documented in Hp2-2 plaques compared to control plaques. This may result in impaired reverse cholesterol transport in Hp2-2 plaques. Active human studies analyzing cholesterol efflux and HDL function are in process to evaluate the role of Hp genotyping and reverse cholesterol transport in DM atherosclerosis.
- © 2013 by American Heart Association, Inc.