Shotgun proteomic analysis reveals proteome alterations in HDL of patients with cholesteryl ester transfer protein deficiency

Abstract

Background: We previously reported that the patients with cholesteryl ester transfer protein (CETP) deficiency (CETP-D) show marked changes in the size and lipid compositions of high-density lipoprotein (HDL) and that they are not protected from atherosclerotic cardiovascular diseases, despite increased serum HDL-cholesterol (HDL-C) levels. HDL particles carry a variety of proteins, some of which are known to have antiatherogenic functions.

Objective: This study aimed to investigate the protein composition of HDL particles in patients with CETP-D.

Methods: Eight patients with complete deficiency of CETP and 8 normolipidemic healthy subjects were enrolled. We performed shotgun proteomic analysis to investigate the proteome of ultracentrifugally isolated HDL.

Results: We identified 79 HDL-associated proteins involved in lipid metabolism, protease inhibition, complement regulation, and acute-phase response, including 5 potential newly identified HDL-associated proteins such as angiopoietin-like3 (ANGPTL3). Spectral counts of apolipoprotein (apo) E were increased in patients with CETP-D compared with controls (60.3 ± 6.9 vs 43.7 ± 2.5, P < .001), which is concordant with our previous report. Complement regulatory proteins such as C3, C4a, C4b, and C9 were also significantly enriched in HDL from patients with CETP-D. Furthermore, apoC-III and ANGPTL3, both of which are now known to associate with increased atherosclerotic cardiovascular diseases, were enriched in patients with CETP-D compared with normolipidemic subjects (35.9 ± 5.3 vs 27.1 ± 3.7, 2.3 ± 1.1 vs 0.4 ± 1.1, respectively; P < .01).

Conclusion: We have characterized HDL-associated proteins in patients with CETP-D. We identified a significant increase in the amount of apoE, apoC-III, ANGPTL3, and complement regulatory proteins. These proteomic changes might be partly responsible for the enhanced atherogenicity of patients with CETP-D.

Keywords: Cholesteryl ester transfer protein deficiency; High density lipoprotein; LC-MS/MS analysis; Shotgun proteomic analysis; Ultracentrifugation.