TY - JOUR

T1 - Myeloperoxidase-derived oxidants modify apolipoprotein A-I and generate dysfunctional high-density lipoproteins

T2 - comparison of hypothiocyanous acid (HOSCN) with hypochlorous acid (HOCl)

AU - Hadfield, Katrina A

AU - Pattison, David I

AU - Brown, Bronwyn E

AU - Hou, Liming

AU - Rye, Kerry-Anne

AU - Davies, Michael Jonathan

AU - Hawkins, Clare Louise

PY - 2013/1/15

Y1 - 2013/1/15

N2 - Oxidative modification of HDLs (high-density lipoproteins) by MPO (myeloperoxidase) compromises its anti-atherogenic properties, which may contribute to the development of atherosclerosis. Although it has been established that HOCl (hypochlorous acid) produced by MPO targets apoA-I (apolipoprotein A-I), the major apolipoprotein of HDLs, the role of the other major oxidant generated by MPO, HOSCN (hypothiocyanous acid), in the generation of dysfunctional HDLs has not been examined. In the present study, we characterize the structural and functional modifications of lipid-free apoA-I and rHDL (reconstituted discoidal HDL) containing apoA-I complexed with phospholipid, induced by HOSCN and its decomposition product, OCN- (cyanate). Treatment of apoA-I with HOSCN resulted in the oxidation of tryptophan residues, whereas OCN- induced carbamylation of lysine residues to yield homocitrulline. Tryptophan residues were more readily oxidized on apoA-I contained in rHDLs. Exposure of lipid-free apoA-I to HOSCN and OCN- significantly reduced the extent of cholesterol efflux from cholesterol-loaded macrophages when compared with unmodified apoA-I. In contrast, HOSCN did not affect the anti-inflammatory properties of rHDL. The ability of HOSCN to impair apoA-I-mediated cholesterol efflux may contribute to the development of atherosclerosis, particularly in smokers who have high plasma levels of SCN- (thiocyanate).

AB - Oxidative modification of HDLs (high-density lipoproteins) by MPO (myeloperoxidase) compromises its anti-atherogenic properties, which may contribute to the development of atherosclerosis. Although it has been established that HOCl (hypochlorous acid) produced by MPO targets apoA-I (apolipoprotein A-I), the major apolipoprotein of HDLs, the role of the other major oxidant generated by MPO, HOSCN (hypothiocyanous acid), in the generation of dysfunctional HDLs has not been examined. In the present study, we characterize the structural and functional modifications of lipid-free apoA-I and rHDL (reconstituted discoidal HDL) containing apoA-I complexed with phospholipid, induced by HOSCN and its decomposition product, OCN- (cyanate). Treatment of apoA-I with HOSCN resulted in the oxidation of tryptophan residues, whereas OCN- induced carbamylation of lysine residues to yield homocitrulline. Tryptophan residues were more readily oxidized on apoA-I contained in rHDLs. Exposure of lipid-free apoA-I to HOSCN and OCN- significantly reduced the extent of cholesterol efflux from cholesterol-loaded macrophages when compared with unmodified apoA-I. In contrast, HOSCN did not affect the anti-inflammatory properties of rHDL. The ability of HOSCN to impair apoA-I-mediated cholesterol efflux may contribute to the development of atherosclerosis, particularly in smokers who have high plasma levels of SCN- (thiocyanate).

KW - Amino Acid Sequence

KW - Apolipoprotein A-I

KW - Biological Transport

KW - Cell Line

KW - Cells, Cultured

KW - Cholesterol

KW - E-Selectin

KW - Endothelium, Vascular

KW - Female

KW - Flow Cytometry

KW - Humans

KW - Hypochlorous Acid

KW - Intercellular Adhesion Molecule-1

KW - Lipoproteins, HDL

KW - Macrophages

KW - Male

KW - Molecular Sequence Data

KW - Oxidants

KW - Oxidation-Reduction

KW - Peptides

KW - Peroxidase

KW - Thiocyanates

KW - Vascular Cell Adhesion Molecule-1

U2 - 10.1042/BJ20121210

DO - 10.1042/BJ20121210

M3 - Journal article

C2 - 23088652

VL - 449

SP - 531

EP - 542

JO - Biochemical Journal

JF - Biochemical Journal

SN - 0264-6021

IS - 2

ER -