Effects of serum lipid smoothness on the progression and vulnerability of atherosclerotic plaques in rabbits.

We aimed to explore the effects of lipid smoothness on the progression and vulnerability of atherosclerotic plaques.24 rabbits were divided into three groups randomly. Group 1 was given standard chow diet; group 2 was fed with cholesterol-rich diet; for group 3, subjects were planned to take cholesterol-rich diet at the first phase for 12 weeks and during the second phase, low-fat and cholesterol-rich diet was then applied alternately every three weeks till the end of the experiment. Lipid profiles, inflammatory factors, endothelium functions, pathological and histological changes were examined. Expressions of matrix metalloproteinase-9 and lectin-like oxidized LDL receptor-1 were measured by immunohistochemical staining.According to data collected during the whole experiment, lipid smoothness index of group 3 was the lowest. Compared with group 2, statistics of the group 3 indicated that: the development of plaques progressed faster; the plaque area and plaque thickness (53.53[22.6]% vs 33.90[24.91]% , 800.38[98.25]µm vs 675.00[109.67]µm) were higher while the fibrous cap thickness (103.50[45.66]µm vs 295.83[97.90]µm) was lower; hs-CRP (0.53[0.07]mg/dL vs 0.45[0.06]mg/dL), interleukin-18 (186.01[8.41]ng/L vs 158.08[2.37]ng/L), OX-LDL (177.15[5.93]µg/L vs 139.57[2.35] µg/L) and endothelin-1 (164.66[9.54]ng/L vs 131.52[4.39]ng/L) were higher while nitric-oxide (22.41[1.69]µmol/L vs 27.23[1.36]µmol/L) was lower; expressions of matrix metalloproteinase-9 (IOD: 37375.87[5634.52] vs 20956.57[4616.93]) and lectin-like oxidized LDL receptor-1 (IOD: 45213.04[16653.81] vs 21921.68[6142.32]) were higher.Lipids fluctuation could accelerate the progression and vulnerability of atherosclerotic plaques through worsening arterial endothelium dysfunction and inflammatory reactions

The vascular ultrasound of group 2 and group 3 in different weeks.

<p>Legend: (A) and (C): group 2 at week 12 and week 24; (B) and (D): group 3 at week 12 and week 24.</p

The H&E staining of atherosclerosis in the three groups.

<p>Legend: Magnifications: ×200(A–C2), ×400(C3). A: Normal aorta intima in group 1. B1–B2: Atherosclerotic plaque in group 2. The endothelial cells shed, numerous foam cells and cholesterol crystal (B1); cell necrosis and calcium deposition (B2). C1–C3: Atherosclerotic plaque in group 3. plaques with thin fibrous caps and big lipid cores (C1), the discontinuous fiber cap (C2), inflammatory cells (C3).</p

SI values in the three groups (mean [SD]).

<p>LDL-C: low-density lipoprotein cholesterol, SI: smoothness index, TC: total cholesterol.</p><p>*: <i>P</i><0.01,</p>c<p>: compared with group 1,</p>d<p>: compared with group 2.</p

The immuohistochemical staining of atherosclerosis in the 3 groups.

<p>Legend: Magnifications: ×400. MMP-9: matrix metalloproteinase-9; LOX-1: lectin-like oxidized low density lipoprotein receptor-1. Representative pictures of MMP-9 and LOX-1 expressions immuohistochemical staining in the aortic atherosclerotic plaque of the three groups.</p

The IMT of the three groups in different weeks (mean [SD], mm).

<p>IMT: intima-media thickness.</p>#<p>: <i>P</i><0.05,</p><p>*: <i>P</i><0.01,</p>a<p>: compared with 0 week,</p>b<p>: compared with week 12;</p>c<p>: compared with group 1,</p>d<p>: compared with group 2.</p

Body weight in the three groups (mean [SD]).

#<p>: <i>P</i><0.05,</p><p>*: <i>P</i><0.01,</p>a<p>: compared with 0 week,</p>b<p>: compared with week 12.</p

The characteristics of atherosclerotic plaque in the three groups (mean [SD]).

#<p>: <i>P</i><0.05,</p><p>*: <i>P</i><0.01,</p>c<p>: compared with group 1,</p>d<p>: compared with group 2.</p

Serum hs-CRP, IL-18, ET-1, OX-LDL and NO levels in the three groups (mean [SD]).

<p>ET-1: endothelin-1, hs-CRP: high-sensitivity C-reactive protein, IL-18: interleukin-18, NO: nitric oxide, OX-LDL: oxidized low density lipoprotein.</p>#<p>: <i>P</i><0.05,</p><p>*: <i>P</i><0.01,</p>a<p>: compared with 0 week,</p>b<p>: compared with week 12;</p>c<p>: compared with group 1,</p>d<p>:compared with group 2.</p