Low plasma lecithin:cholesterol acyltransferase and lipid transfer protein activities in growth hormone deficient and acromegalic men: Role in altered high density lipoproteins

Growth hormone (GH) deficiency and acromegaly may be associated with increased cardiovascular risk. Little is known about alterations in high density lipoproteins (HDL) in these conditions. Lecithin:cholesterol acyl transferase (LCAT) has the ability to esterify free cholesterol (FC) in HDL. Cholesteryl ester transfer protein (CETP) is able to transfer cholesteryl esters (CE) from HDL to very low and low density lipoproteins (VLDL and LDL). During phospholipid transfer protein (PLTP) -mediated HDL remodelling, small pre β-HDL particles are generated which serve as acceptors for cellular cholesterol and provide the initial LCAT-substrate. We documented plasma lipids, LCAT, CETP and PLTP activity levels as well as plasma cholesterol esterification (EST) and cholesteryl ester transfer (CET) in 12 adult men with acquired GH deficiency, 12 acromegalic men and 24 healthy male subjects. All GH deficient and acromegalic patients received conventional hormonal replacement therapy if necessary. VLDL + LDL cholesterol and plasma triglycerides were higher in GH deficient (P < 0.01 and P < 0.05) and acromegalic patients (P < 0.05 and P < 0.01) than in healthy subjects. HDL cholesterol and HDL CE were lower (P < 0.05 for both) and the HDL FC/CE ratio was higher (P < 0.01) in these patient groups compared to healthy subjects. Plasma LCAT, CETP and PLTP activity levels were lower in acromegalic patients (P < 0.01 for all) and CETP activity was lower in GH deficient patients (P < 0.01) compared to healthy subjects. Plasma EST and CET were decreased in both acromegalic (P < 0.01 for both) and GH deficient patients (P < 0.05 for both). Multiple regression analysis demonstrated independent negative relationships of plasma insulin-like growth factor I with plasma LCAT (P = 0.0001), CETP (P = 0.009) and PLTP activity levels (P = 0.021). Plasma LCAT (P = 0.0001) and CETP activity (P = 0.0001) were also negatively associated with (substitution therapy for) adrenal insufficiency. In conclusion, GH deficient and acromegalic patients show abnormalities in HDL, consistent with impaired LCAT action. Decreases in plasma EST and CET in such patients, as well as a low PLTP activity in acromegaly suggest that reverse cholesterol transport may be impaired, contributing to increased cardiovascular risk.

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