Response to Dullaart re: 'Effects of Short-Term Hypothyroidism on the Lipid Transfer to High-Density Lipoprotein and Other Parameters Related to Lipoprotein Metabolism in Patients Submitted to Thyroidectomy for Thyroid Cancer'

摘要

Dear Editor: We are pleased to have received the comments of Dr. Dullaart (1) who illustrates the difficulties of sorting out the multifaceted functions of high-density lipoprotein (HDL) and how they relate to atherogenesis and other pathophysiologic processes, and the design and interpretation of functional tests for HDL (2). In this respect, lipid transfers among lipoprotein classes play a crucial role in HDL formation and remodeling, and are determinants of HDL lipid composition and of the content of >80 proteins present in HDL fraction. In this respect, subjects with cholesteryl ester transfer protein deficiency show important proteomic changes in the HDL fraction (3). The HDL fraction, which contains the majority of lecithin-cholesterol acyltransferase (LCAT) and apo A-I, the LCAT cofactor, is the main system responsible for cholesterol esterification, a process that is essential for cholesterol stabilization in the plasma and that creates driving gradients of reverse cholesterol transport. In this setting, the entry of cholesterol into HDL from the other lipoprotein classes to undergo esterification is of great importance for cholesterol homeostasis. These considerations were the chief motivations for the development of an in vitro assay in our laboratory, which determines the simultaneous transfer of the esterifled and unesterified cholesterol forms, triglycerides and phospholipids to HDL to approach the dynamics of lipid transfers in the plasma. This is a practical and reproducible method, which can eventually undergo automatization for the clinical laboratory (4).