Carotid plaque age is a feature of plaque stability inversely related to levels of plasma insulin.
PLoS One 2011;
6:e18248. [PMID:
21490968 PMCID:
PMC3072386 DOI:
10.1371/journal.pone.0018248]
[Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2010] [Accepted: 03/02/2011] [Indexed: 12/25/2022] Open
Abstract
Background
The stability of atherosclerotic plaques determines the risk for rupture,
which may lead to thrombus formation and potentially severe clinical
complications such as myocardial infarction and stroke. Although the rate of
plaque formation may be important for plaque stability, this process is not
well understood. We took advantage of the atmospheric
14C-declination curve (a result of the atomic bomb tests in the
1950s and 1960s) to determine the average biological age of carotid
plaques.
Methodology/Principal Finding
The cores of carotid plaques were dissected from 29 well-characterized,
symptomatic patients with carotid stenosis and analyzed for 14C
content by accelerator mass spectrometry. The average plaque age (i.e.
formation time) was 9.6±3.3 years. All but two plaques had formed
within 5–15 years before surgery. Plaque age was not associated with
the chronological ages of the patients but was inversely related to plasma
insulin levels (p = 0.0014). Most plaques were
echo-lucent rather than echo-rich (2.24±0.97, range 1–5).
However, plaques in the lowest tercile of plaque age (most recently formed)
were characterized by further instability with a higher content of lipids
and macrophages (67.8±12.4 vs. 50.4±6.2,
p = 0.00005; 57.6±26.1 vs. 39.8±25.7,
p<0.0005, respectively), less collagen (45.3±6.1 vs.
51.1±9.8, p<0.05), and fewer smooth muscle cells (130±31
vs. 141±21, p<0.05) than plaques in the highest tercile.
Microarray analysis of plaques in the lowest tercile also showed increased
activity of genes involved in immune responses and oxidative
phosphorylation.
Conclusions/Significance
Our results show, for the first time, that plaque age, as judge by relative
incorporation of 14C, can improve our understanding of carotid
plaque stability and therefore risk for clinical complications. Our results
also suggest that levels of plasma insulin might be involved in determining
carotid plaque age.
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