Increased leukocyte ABCA1 gene expression in post-menopausal women on hormone replacement therapy

Objective. The ATP binding cassette A1 (ABCA1) is a key participant in the reverse cholesterol process whereby mediates cholesterol efflux directly to HDL particles. The aim of this study was to investigate whether long-term treatment with conventional hormone replacement therapy (HRT) in post-menopausal women could affect their leukocytes ABCA1 expression. Changes in various serum lipids and lipoprotein fractions were also investigated. Material and Methods. A total of 60 non-obese normolipidaemic post-menopausal women treated with oral oestrogen together with progestin therapy for 3 months were selected. Leukocytes ABCA1 gene expression and serum lipid and lipoprotein concentrations were measured at the start and end of the HRT. Results. HRT led to significant increases in HDL cholesterol (P = 0.001) and apoA-I (P = 0.046) and significant decrease in apoB (P = 0.049) and LDL cholesterol (P = 0.022) when compared with the baseline levels. Analysis of leukocytes ABCA1 mRNA showed a significant increase in ABCA1 gene expression after HRT (P = 0.001). There was also a significant inverse association (r = 70.28, P = 0.03) between ABCA1 gene expression and log TG/HDL cholesterol changes related to HRT. Conclusion. The beneficial cardiovascular effects of HRT could be explained, at least in part, by increasing the ABCA1 gene expression.