Macrophages are associated with lipid-rich carotid artery plaques, echolucency on B-mode imaging, and elevated plasma lipid levels.
OBJECTIVE
Atherosclerosis may be regarded as an inflammatory disease dominated by macrophages. We tested whether macrophages in carotid artery atherosclerotic plaques are associated with echolucency on B-mode ultrasound imaging, lipid levels, inflammatory markers, and aspirin use.


METHODS
We studied 106 patients undergoing carotid endarterectomy having >/=50% carotid artery stenosis and previous ipsilateral hemispheric neurologic symptoms.


RESULTS
Macrophages were particularly common in plaques with a high content of lipid and hemorrhage and, conversely, rare in plaques dominated by calcification and fibrous tissue. Macrophage density in carotid artery plaques classified by B-mode ultrasound imaging as echolucent (n = 56), intermediate (n = 25), or echorich (n = 25) was 1.8% +/- 0.2%, 1.5% +/- 0.4%, and 1.0% +/- 0.2% (+/-SE), respectively (analysis of variance, P =.02). A computer-generated measure of plaque echolucency, gray-scale median, was associated with increased macrophage density (r = -0.31; P =.002). Furthermore, plasma and low-density lipoprotein cholesterol levels were associated with carotid artery macrophage density (r = 0.26, P =.008 and r = 0.23, P =.02); this was most pronounced in patients with lipid-rich plaques. Macrophage density was not associated with plasma levels of acute-phase reactants. Finally, macrophage density in carotid artery plaques of users (n = 55) and nonusers of aspirin (n = 51) was 1.2% +/- 0.2% and 1.8% +/- 0.2% (t test, P =.01).


CONCLUSIONS
Increased macrophage density in carotid atherosclerotic plaques was associated with lipid content, plaque echolucency, and increased plasma and low-density lipoprotein cholesterol levels. Furthermore, use of aspirin was associated with reduced macrophage density in carotid artery plaques.
Grønholdt
Marie-Louise M
ML
Department of Vascular Surgery, Gentofte Hospital, Universities of Copenhagen and Aarhus, Denmark. mlg@dadlnet.dk.
Nordestgaard
Børge G
BG
Bentzon
Jacob
J
Wiebe
Britt M
BM
Zhou
Ji
J
Falk
Erling
E
Sillesen
Henrik
H
D000704:Analysis of Variance; D001241:Aspirin / Q000494:pharmacology*; D002339:Carotid Arteries / Q000000981:diagnostic imaging / Q000187:drug effects / Q000473:pathology; D002340:Carotid Artery Diseases / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D016893:Carotid Stenosis / Q000097:blood* / Q000150:complications / Q000175:diagnosis*; D016894:Endarterectomy, Carotid; D005260:Female; D005343:Fibrinolytic Agents / Q000494:pharmacology*; D006801:Humans; D018836:Inflammation Mediators / Q000097:blood*; D008055:Lipids / Q000097:blood*; D008163:Luminescent Measurements; D008264:Macrophages / Q000000981:diagnostic imaging* / Q000187:drug effects / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D009422:Nervous System Diseases / Q000097:blood / Q000175:diagnosis / Q000209:etiology; D014463:Ultrasonography
D005343:Fibrinolytic Agents; D018836:Inflammation Mediators; D008055:Lipids; D001241:Aspirin