Muscle Cells In Plaques Research Articles

Dietary Avian Proteins Are Comparable to Soybean Proteins on the Atherosclerosis Development and Fatty Liver Disease in Apoe-Deficient Mice.

Background and aim: The type and amount of dietary protein has become a topic of renewed interest in light of their involvement in metabolic diseases, atherosclerosis and thrombosis. However, little attention has been devoted to the effect of avian proteins despite their wide human consumption. The aim was to investigate the influence of chicken and turkey as sources of protein compared with that of soybean on atherosclerosis and fatty liver disease. Methods and results: To this purpose, male and female Apoe-deficient were fed purified Western diets differing in their protein sources for 12 weeks. After this period, blood, liver, aortic tree and heart base samples were taken for analyses of plasma lipids and atherosclerosis. Plasma triglycerides, non-esterified fatty acids, esterified cholesterol levels and radical oxygen species in lipoproteins changed depending on the diet and sex. Females consuming the turkey protein-containing diet showed decreased atherosclerotic foci, as evidenced by the en face atherosclerosis analyses. The presence of macrophages and smooth muscle cells in plaques were not modified, and no changes were observed in hepatic lipid droplets in the studied groups either. Paraoxonase activity was higher in the group consuming turkey protein without sex differences, but only in females, it was significantly associated with aortic lesion areas. Conclusions: Compared to soybean protein, the consumption of avian proteins depending on sex resulted in similar or lower atherosclerosis development and comparable hepatic steatosis.

SLRP1 (Soluble Low-Density Lipoprotein Receptor-Related Protein 1): A Novel Biomarker for P2Y12 (P2Y Purinoceptor 12) Receptor Expression in Atherosclerotic Plaques.

Recent studies suggest that the P2Y12 (P2Y purinoceptor 12) receptor of vascular smooth muscle cells in atherosclerotic plaques aggravates atherosclerosis, and P2Y12 receptor inhibitors such as CDL (clopidogrel) may effectively treat atherosclerosis. It is imperative to identify an effective biomarker for reflecting the P2Y12 receptor expression on vascular smooth muscle cells in plaques. Approach and Results: We found that there was a positive correlation between the level of circulating sLRP1 (soluble low-density lipoprotein receptor-related protein 1) and the number of LRP1+ α-SMA+ (α-smooth muscle actin), P2Y12+, or P2Y12+ LRP1+ cells in plaques from apoE-/- mice fed a high-fat diet. Furthermore, activation of the P2Y12 receptor increased the expression and shedding of LRP1 in vascular smooth muscle cells by inhibiting cAMP (3'-5'-cyclic adenosine monophosphate)/PKA (protein kinase A)/SREBP-2 (sterol regulatory element binding transcription factor 2). Conversely, genetic knockdown or pharmacological inhibition of the P2Y12 receptor had the opposite effects. Additionally, CDL decreased the number of lesional LRP1+ α-SMA+ cells and the levels of circulating sLRP1 by activating cAMP/PKA/SREBP-2 in apoE-/- mice fed a high-fat diet. Our study suggests that sLRP1 may be a biomarker that reflects the P2Y12 receptor level in plaques and has the potential to be an indicator for administering P2Y12 receptor inhibitors for patients with atherosclerosis.

Neutrophils recruited by leukotriene B4 induce features of plaque destabilization during endotoxaemia.

Both leukotrienes and neutrophils have been linked to plaque destabilization. Despite being evoked, the role of leukotriene B4 (LTB4) in neutrophil recruitment to plaques and the concomitant effects of these two actors on plaque stability remain to be proven. Since both actors are elicited during endotoxaemia, a condition associated with the risk of cardiovascular events, we investigated whether endotoxaemia promotes LTB4-mediated neutrophil infiltration in plaques and explored the roles of LTB4 and neutrophils in plaque destabilization. Endotoxaemia induced by repeated peritoneal endotoxin injections at a non-lethal dose (1.5 mg/kg, 5 days) in chow-fed aged Apoe-/- mice (over 45 weeks old) resulted in neutrophil infiltration and activation in plaques. Subsequently to neutrophil invasion, plaques exhibited increased features of vulnerability: reduced collagen content, expanded necrotic cores, and thinned fibrous caps. These plaque features were reproduced by direct deposition of isolated neutrophils onto murine atheromatous carotid arteries in an in vivo assay. In endotoxemic mice, plaques produced increased amounts of LTB4. Genomic or pharmacological impairments of this production reduced neutrophil infiltration, collagenolysis, and apoptosis of smooth muscle cells in plaques of endotoxemic mice. Furthermore, conditioned media of human culprit plaques (CPs) contained more LTB4 than non-CPs and levels of LTB4 correlated to both neutrophil activation markers and endotoxin releases in CPs. These results show that the increased neutrophil recruitment elicited by LTB4 contributes to increase features of plaque destabilization in endotoxemic contexts and point out LTB4 as a potential therapeutic target in atherosclerosis.

Overexpression of Toll-Like Receptors 2, 3, 4, and 8 Is Correlated to the Vascular Atherosclerotic Process in the Hyperlipidemic Rabbit Model: The Effect of Statin Treatment

Background: Atherosclerosis is the major cause of cardiovascular disease; hypercholesterolemia is a major risk factor. We hypothesized that specific TLR members (TLR2, TLR3, TLR4, TLR8) may play a role in atherosclerosis progression and its accompanying inflammatory response. We determined the association of atherosclerotic lesions and TLR mRNA expression in different aortic sites. We also assessed the effects of fluvastatin (Flu) treatment on TLR expression and plaque characteristics. Methods: Male rabbits, fed with an atherogenic diet for a duration of 3 months, were screened for advanced atherosclerotic lesions in the aorta. Additional animals received normal diet or normal diet plus Flu for 1 additional month. TLR mRNA expression in various thoracic and abdominal aortic segments was assessed, together with atherosclerotic changes. Results: After high lipid diet, the atherosclerotic burden increased more in the abdominal than in the thoracic aorta; TLR2, 3, 4, and 8 also increased significantly. Flu decreased atherosclerotic plaque, calcium deposition, lipid cores, intraplaque hemorrhage, erythrocyte membranes, endothelial cells, and macrophage infiltration, while increasing smooth muscle cells in plaques of both aortic segments; it also lowered TLR2, 3, 4, and 8 expression in all aortic segments to a stronger degree than resumption of normal diet. There was a strong association between blood and tissue parameters during experimental period and finally a strong correlation found between these parameters with mRNA of TLR2, 3, 4, and 8 in various stages. Conclusion: For the first time TLR2, 3, 4, and 8 mRNA expression is prospectively explored after hypercholesterolemic diet in the rabbit model. TLR2, 3, 4, and 8 mRNA expression is strongly upregulated and correlates with the progression of atherosclerosis in the aorta. Flu significantly inhibited this progress and reduced inflammation via TLR downregulation which was strongly associated with regression of plaque morphology and atherosclerosis promoting factors.

Molecular targeting of atherosclerotic plaques by a stabilin-2-specific peptide ligand

Many cells, including macrophages, accumulate in atherosclerotic lesions, destabilizing plaques and driving plaque disruption. Therefore, macrophages serve as useful targets for atherosclerosis treatment and imaging. Stabilin-2 is a transmembrane protein expressed predominantly in macrophages and endothelial cells. In the present study, we found that stabilin-2 was widely expressed in atherosclerotic plaques than in normal vessel walls, and was present not only in macrophages but also in endothelial and smooth muscle cells in plaques. We used phage display technology to identify peptides that specifically bound to stabilin-2. After four rounds of selection, the most commonly isolated peptide had the sequence CRTLTVRKC, and was named S2P. We confirmed that this peptide specifically bound to stabilin-2-expressing cells in vitro and sinus endothelial cells in the spleen and lymph nodes in vivo. A FITC-conjugated synthetic CRTLTVRKC peptide was shown to home to atherosclerotic plaques in Ldlr−/− mice and to co-localize with endothelial cells, macrophages, and smooth muscle cells in such plaques. S2P conjugated to hydrophobically modified glycol chitosan nanoparticles was efficiently delivered to atherosclerotic plaques. These results show that the CRLTLTVRKC peptide homes to plaques by targeting stabilin-2; the peptide shows promise as a drug delivery moiety for, and an aid to molecular imaging of, atherosclerosis and other inflammatory diseases.

Expression of matrix metalloproteinase 3 in experimental atherosclerotic plaques.

In atherosclerotic lesions, matrix metalloproteinases produced by foam cells (macrophages) are thought to increase plaque instability, promote plaque rupture, by degradating extracellular matrix. To investigate the relationship between the expression of these proteinases and the histologic appearance of atheromas, immunohistochemical analysis of matrix metalloproteinase 3 and cell-type markers was performed in atherosclerotic plaques induced in rabbit abdominal aortas by high-cholesterol diets and mechanical injury. In addition to an antibody against matrix metalloproteinase 3, RAM-11 and HHF-35 were used to detect macrophages and smooth muscle cells, respectively. Matrix metalloproteinase 3 was expressed diffusely within the plaques with a fibrofatty histologic pattern. In plaques with foam cell accumulation, matrix metalloproteinase 3 was seen in areas rich in foam cells and the smooth muscle cells near the lumen. In the plaques with fewer macrophages, the proteinase was expressed only in such smooth muscle cells. Matrix metalloproteinase 3 was expressed in the smooth muscle cells in plaques of all histologic types, and macrophages also expressed the metalloproteinase when present in significant numbers. These findings suggest that macrophage accumulation plays an important pathophysiologic role in causing the instability of atherosclerotic lesions by increasing the levels of matrix metalloproteinase 3.

Effect of chronic nicotine delivery on the proliferation rate of endothelial and smooth muscle cells in experimentally induced vascular wall plaques

To study the effect of nicotine, cholesterol feeding, and their combination on endothelial and smooth muscle cells in vascular wall plaques an experimental method was established which allows the immunohistochemical detection and quantification of the fractions of endothelial and smooth muscle cells in DNA synthesis under the effect of these stimuli. For this purpose standardized fibromuscular plaques were produced by electrostimulation in the common carotid arteries of rabbits. The animals received either nicotine via implanted osmotic minipumps or a cholesterol diet or both. Plaque size was determined at the end of the experiments after 7 or 14 days as well as the fraction of endothelial and smooth muscle cells in DNA synthesis during exposure to bromodeoxyuridine (BrdU). The BrdU labeling index of endothelial cells clearly increased under chronic nicotine administration for either 7 days or 14 days compared to controls. The combination of nicotine and cholesterol diet led to a more significant increase. In contrast, the BrdU labeling index of smooth muscle cells was not increased under nicotine delivery. The combination of nicotine and cholesterol, however, led to a significant increase of the BrdU labeling index of smooth muscle cells in the plaques compared to cholesterol feeding. Measurement of the plaque size revealed no difference between controls and nicotine-treated animals after 14 days of nicotine delivery, whereas the combination of cholesterol and nicotine produced increased plaque formation compared to a group of animals which received a cholesterol diet alone.