Calcification and carotid plaque vulnerability:inverse relationship between the degree of calcification and fibrous cap pro-inflammatory gene expression

Abstract

Objective Inflammation and calcification are common phenomenons in human atherosclerotic plaque.The objective of this study was to determine the gene expression of some proteins and anti-inflammatory factors as well as bone formation mediators in the fibrous cap and shoulder region of non-calcified and calcified carotid endarterectomy(CEA) plaques.Methods Twenty-two CEA plaques were classified as Va(non-calcified,n=11) and Vb(calcified,n=11) in accordance with the AHA consensus in 1995.Mean percent in carotid stenosis and calcification area was 76.4% and 0% in Va and 74.2% and 33.6% in Vb respectively as determined by quantitative histomorphometry.Using laser capture microdissection,the fibrous cap and shoulder regions were excised from 22 frozen sections/plaques.After total RNA extraction and reverse transcription,gene expression of proteins(IL-1,IL-8,and MCP-1),anti-inflammatory factor(IL-10) and bone formation protein(BMP-6 and Osteocalcin) were detected by Real-time PCR.Results mRNA expression of MCP-1,IL-8 and IL-1 in Va plaques were 1.8 fold higher than that in Vb plaques,mRNA expression of anti-inflammatory factor IL-10 and osteogenic related genes BMP-6 and Osteocalcin were 3.8,4.2,and 6.9 fold higher in Vb plaques compared to Va plaques.Conclusions Our findings indicate that fibrous cap inflammation and susceptibility to disruption is more likely to occur in non-calcified plaques. Key words: Arteriosclerosis/PP; Calcinosis; Chemokines; Gene expression