Human carotid plaque calcification and vulnerability. Relationship between degree of plaque calcification, fibrous cap inflammatory gene expression and symptomatology.
BACKGROUND
Inflammation is a key mechanism in human atherosclerotic plaque vulnerability and disruption. The objective was to determine the differential gene expression of pro- and anti-inflammatory factors in the fibrous cap and shoulder region of noncalcified and calcified carotid endarterectomy plaques.


METHODS
Thirty carotid endarterectomy plaques were classified as type Va (noncalcified, n = 15) and type Vb (calcified, n = 15) in accordance with the American Heart Association consensus. Using laser capture microdissection, fibrous cap and shoulder regions were excised from frozen sections. Gene expression of pro- [interleukin 1 (IL-1), IL-8 and monocyte chemoattractant protein 1 (MCP-1)] and anti-inflammatory (IL-10) factors, and bone formation (bone morphogenetic protein 6 and osteocalcin) mediators were quantitated by real-time PCR. Protein levels were determined using Western blotting.


RESULTS
Mean percent carotid stenosis and calcification area were 79 and 5% in Va-plaques (40% symptomatic) and 77 and 42% in Vb-plaques (20% symptomatic). Macrophages infiltrating the region of the fibrous cap and the shoulder were more numerous in non-calcified plaques compared with calcified plaques (p < 0.01]. mRNA expression of MCP-1 and IL-8, and protein levels of IL-8 were also greater in Va plaques compared to Vb plaques (p < 0.05). Protein levels and mRNA expression of osteocalcin were greater in Vb compared to Va plaques (p < 0.05).


CONCLUSIONS
Fibrous cap inflammation is more likely to occur in noncalcified than in calcified plaques. These findings suggest that carotid atherosclerotic plaque calcification is a structural marker of plaque stability.
Wahlgren
Carl-Magnus
CM
Section of Vascular Surgery, Department of Surgery, University of Chicago, 5841 S Maryland Avenue, Chicago, IL 60637, USA.
Zheng
Wei
W
Shaalan
Wael
W
Tang
Jun
J
Bassiouny
Hisham S
HS
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D055418:Bone Morphogenetic Protein 6 / Q000235:genetics / Q000378:metabolism; D002114:Calcinosis / Q000378:metabolism* / Q000473:pathology*; D002340:Carotid Artery Diseases / Q000378:metabolism* / Q000473:pathology*; D016893:Carotid Stenosis / Q000378:metabolism* / Q000473:pathology*; D002465:Cell Movement; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D016894:Endarterectomy, Carotid; D005786:Gene Expression Regulation; D006801:Humans; D016753:Interleukin-10 / Q000235:genetics / Q000378:metabolism; D053583:Interleukin-1beta / Q000235:genetics / Q000378:metabolism; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000473:pathology; D008875:Middle Aged; D015675:Osteocalcin / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012189:Retrospective Studies
C525816:BMP6 protein, human; D015415:Biomarkers; D055418:Bone Morphogenetic Protein 6; C111835:CCL2 protein, human; D018932:Chemokine CCL2; D016207:Cytokines; D053583:Interleukin-1beta; D016209:Interleukin-8; D012333:RNA, Messenger; D015675:Osteocalcin; D016753:Interleukin-10