Marso.qxp 10/10/08 3:00 pm Page 30
Coronary
Characteristics of Adiponectin and Coronary Plaque –
An Intravascular Ultrasound Study
a report by
Steven P Marso
Mid America Heart Institute, University of Missouri Kansas City
Adiponectin (also known as APM1, Acrp 30, AdipoQ or GBP28) is a 30kD understood. It is believed that transport of lipoproteins across the
circulating plasma protein and is the most abundant adipokine secreted by endothelial cell monolayer is an initial step in atherogenesis and is also likely
adipose tissue. In humans, adiponectin accounts for approximately 0.01% enhanced in the presence of oxidised LDL cholesterol. A biological
of circulating plasma proteins.
1
It is thought to have a unique spectrum of association between adiponectin and atherosclerosis seems plausible.
properties for an adipokine, many of which are anti-atherosclerotic, and is Adiponectin suppresses macrophage to foam cell maturation and induces
downregulated in the presence of increasing central adiposity. Low levels the production of anti-inflammatory mediators, including interleukin-10 and
have been shown to be associated with inflammation, risk of metabolic interleukin-1 receptor antagonist.
6
syndrome, decreased low-density lipoprotein (LDL) cholesterol particle size
and small dense high-density lipoprotein (HDL) cholesterol, as well as insulin Intravascular ultrasound (IVUS) provides transmural imaging of the coronary
resistance,
2
type 2 diabetes,
3
lipid oxidation
4
and risk of myocardial artery wall and assists with early detection of atherosclerosis. Virtual
infarction. Increased levels have also been associated with reduced risk of Histology™ (VH) is an emerging adjunct to IVUS that categorises
myocardial infarction even following adjustment for traditional atherosclerotic plaque into four distinct colour-coded components (green =
cardiovascular risk factors.
5
fibrous; light green = fibrofatty; white = dense calcium; and red = necrotic
core) using autoregressive modelling of radiofrequency data. To understand
Adiponectin is thought to be involved in foam cell transformation. Although the association between adiponectin and human plaque composition, we
extensively studied, lipid accumulation in the vessel wall is incompletely studied a cohort of patients enrolled in the Diabetes Genome Project
Figure 1: Plaque Phenotype Classification Using Intravascular
undergoing IVUS-VH.
Ultrasound–Virtual Histology (IVUS-VH) and Representative
IVUS-VH Image of Each Phenotype
Methods
In a recent analysis from the Diabetes Genome Project (clinicaltrials.gov
Lesion Type Brief Description Sample Frame
identifier: NCT00428961), 185 patients underwent IVUS-VH and provided
ID-AIT <600µm thick on any IVUS frame.
informed consent for the provision of biomarker data. The methods have
Histopathologically, this type of lesion
is termed ‘intimal xanthoma’.
been previously described.
6
Briefly, all IVUS frames within the pullback area
comprised the region of interest for this analysis. IVUS frames were classified
by plaque composition and phenotype (see Figure 1).
ID-PIT >600µm thick and predominantly fibrous
Results
tissue with or without >15% fibrofatty
Of the total study group, 66 patients had diabetes and 119 did not.
tissue and without either confluent necrotic
Adiponectin levels correlated with age (r= 0.3; p<0.0001), body mass index
core or confluent dense calcium.
(r=-0.17; p=0.02) and markers of insulin resistance, including homeostasis
model assessment (r=-0.17; p=0.02) and fasting insulin (r=-0.20; p=0.008).
ID-FC >600µm thick and confluent dense calcium
There were no associations between adiponectin and diabetes, glycated
without confluent necrotic core. haemoglobin (HbA
1c
), fasting glucose or albuminuria.
There were significant associations between adiponectin and several
lipoproteins, specifically triglycerides (r=-0.27; p=0.0002), HDL cholesterol
ID-FA >600µm thick and confluent necrotic core
(r=0.4; p<0.001), small, dense LDL
3
(r=-0.27; p=0.003) and LDL
4
(r=-0.25;
not at the lumen or, if at the lumen surface,
p=0.0005) subfractions and the larger, more buoyant LDL
2
(r=0.18;
p=0.015). The relationship between adiponectin and IVUS measures of
≤14 pixels along lumen circumference on
three consecutive frames with or without atherosclerosis is shown in Figure 2 and Table 1. In the total study group,
confluent dense calcium.
plaque consisting of fibrofatty tissue declined with increasing adiponectin
level (see Figure 2), mostly driven by the non-diabetic cohort (see Table 1).
ID-TCFA >600µm thick, >50% plaque burden and
The association between fibrofatty volume and adiponectin was significant
confluent necrotic core extending >14 pixels
in non-diabetic (r=-0.23; p=0.009) but not diabetic patients. When classified
along the circumference of the lumen on
three consecutive frames with or without
by phenotype, the proportion of plaque identified as pathological intimal
confluent dense calcium.
thickening also declined as adiponectin levels increased in the non-diabetic
but not in the diabetic cohort (see Figure 3).
30 © TOUCH BRIEFINGS 2008
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