Oxidized LDL in human carotid plaques is related to symptomatic carotid disease and lesion instability.
BACKGROUND
Oxidative stress is an important determinant in atherosclerosis development. Various markers of oxidative stress, such as oxidation of low-density lipoprotein (LDL), nitrosative stress, lipid peroxidation, and protein oxidation, have been implicated in the initiation and/or progression of atherosclerosis, but their association with plaque erosion and symptomatic carotid disease has not been fully defined. In addition, certain oxidative markers have been shown in various models to promote plaque remodeling through matrix metalloproteinase (MMP) activation.


OBJECTIVE
To perform a global investigation of various oxidative stress markers and assess for potential relationships with destabilization and symptomatic development in human carotid plaques.


METHODS
Thirty-six patients undergoing endarterectomy were evaluated and compared with 20 control specimens obtained at the time of autopsy. Differences between stable and unstable plaques, symptomatic and asymptomatic patients, and >or=90% and <90% stenosis were evaluated. Oxidized LDL (ox-LDL), nitrotyrosine (NT), malondialdehyde (MDA), and protein carbonyls (PCs) levels were determined in atheromatic plaques homogenates by corresponding biochemical assays. Immunohistochemical (IHC) analysis was also employed to determine the percentage and topological distribution of cells expressing NT and metalloproteinase-9 (MMP-9) in serial sections from corresponding atheromatic plaques. MMP-9 expression was further verified using Western blot analysis.


RESULTS
Ox-LDL was increased in symptomatic patients (P < .05). Also, ox-LDL and NT levels were significantly higher in unstable versus stable carotid plaques (P < .05, respectively). Furthermore, IHC serial section analysis, corroborated by statistical analysis, showed a topological and expressional correlation between NT and MMP-9 (P < .05). MDA and PCs levels, although increased in carotid plaques, did not distinguish stable from unstable carotid plaques as well as symptomatic from asymptomatic patients with various degrees of stenosis.


CONCLUSIONS
All types of investigated oxidative stress markers were significantly increased in human carotid plaques, but only ox-LDL levels were associated with clinical symptoms, while peroxynitrite products and MMP-9 were specifically related to plaque instability.
Sigala
Fragiska
F
First Department of Propaedeutic Surgery, Hippocrateion Hospital, Medical School, University of Athens, Athens, Greece.
Kotsinas
Athanassios
A
Savari
Paraskevi
P
Filis
Konstantinos
K
Markantonis
Sophia
S
Iliodromitis
Efstathios K
EK
Gorgoulis
Vassilis G
VG
Andreadou
Ioanna
I
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000032:analysis; D015153:Blotting, Western; D002343:Carotid Artery, Internal / Q000737:chemistry* / Q000601:surgery; D016893:Carotid Stenosis / Q000378:metabolism* / Q000601:surgery; D016022:Case-Control Studies; D018450:Disease Progression; D016894:Endarterectomy, Carotid; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008077:Lipoproteins, LDL / Q000032:analysis*; D008297:Male; D008315:Malondialdehyde / Q000032:analysis; D020780:Matrix Metalloproteinase 9 / Q000032:analysis; D008875:Middle Aged; D018384:Oxidative Stress; D011446:Prospective Studies; D050050:Protein Carbonylation; D012421:Rupture; D012720:Severity of Illness Index; D014443:Tyrosine / Q000031:analogs & derivatives / Q000032:analysis; D015854:Up-Regulation
D015415:Biomarkers; D008077:Lipoproteins, LDL; C099252:oxidized low density lipoprotein; C002744:3-nitrotyrosine; D014443:Tyrosine; D008315:Malondialdehyde; D020780:Matrix Metalloproteinase 9