Wen Qiang Chen

Oral rapamycin attenuates inflammation and enhances stability of atherosclerotic plaques in rabbits independent of serum lipid levels.

Background and purpose:  Atherosclerotic plaque rupture and thrombosis are the main cause of acute coronary syndrome. The study was aimed to test the hypothesis that oral administration of rapamycin may attenuate inflammation, inhibit progression and enhance stability of atherosclerotic plaques.

Chinese medicine tongxinluo significantly lowers serum lipid levels and stabilizes vulnerable plaques in a rabbit model

UNLABELLED RELEVANCE TO ETHNOPHARMACOLOGY: Tongxinluo capsule is a compound preparation formulated on the basis of the meridian theory of traditional Chinese medicine and is officially approved for the treatment of angina pectoris and ischemic stroke in China. OBJECTIVES To test the hypothesis that the Chinese traditional medicine tongxinluo in capsule form has similar effects as simvastatin in lowering serum lipid levels and stabilizing vulnerable plaques. MATERIALS AND METHODS Thirty New Zealand white rabbits underwent balloon-induced abdominal aortic endothelial injury and were fed a diet of 1% cholesterol for 8 weeks. The rabbits were then randomly divided into three groups (n=10 each) for daily doses of tongxinluo capsule (1 g/kg), simvastatin (5 mg/kg) or no drugs for 12 weeks. At the end of week 20, plaque rupture was induced by pharmacological triggering. Serological, ultrasonographic, pathologic, immunohistochemical, and gene expression studies were performed. RESULTS The incidence of plaque rupture with tongxinluo and simvastatin treatment was significantly lower than that with control treatment (0% for both drug treatments vs. 56.0%; P<0.05). Values of serum lipid profile, inflammatory markers, and pathological and immunohistological assays were significantly improved in the tongxinluo- and simvastatin-treated groups than in the control group. The simvastatin-treated group showed lower serum lipid levels than the tongxinluo-treated group. CONCLUSIONS Treatment with the Chinese medicine tongxinluo was as effective as simvastatin in lowering serum lipid levels, inhibiting plaque inflammation and preventing vulnerable plaques from rupture and may provide an alternative therapy for atherosclerosis.

Animal models and potential mechanisms of plaque destabilisation and disruption

Studies of the pathophysiological mechanism of both acute coronary syndromes and plaque stabilising treatment are driving the development of animal models of vulnerable plaque. In contrast to advances in human studies of pathology, the definition, criteria and classification of vulnerable and ruptured plaques in animal models are still in dispute. Many approaches to increasing the intrinsic vulnerability of plaques or extrinsic forces on plaques have been reported. However, an ideal animal model mimicking human plaque rupture is still lacking, and the exact cellular and molecular mechanisms of plaque progression are not fully understood. This review summarises current progress in animal model studies related to plaque destabilisation and disruption and the possible mechanisms involved.

Chymase activity is closely related with plaque vulnerability in a hamster model of atherosclerosis

OBJECTIVE To test the hypothesis that stimulation of chymase secretion may contribute to plaque vulnerability and inhibition of chymase activity may enhance plaque stability. METHODS AND RESULTS Sixty eight-week-old male Syrian golden hamsters were randomly divided into normal control group, high-cholesterol (HC) treated group, HC+ovalbumin treated group and HC+tranilast treated group. The normal control group received a normal diet while the other three intervention groups received a high-cholesterol diet for 15 weeks. Hamsters in the HC+ovalbumin treated group underwent transcatheter pharmacological triggering at the end of week 15 after antigen sensitization and those in the HC+tranilast treated group were given tranilast intragastrically for 3 weeks before euthanasia. Serological, ultrasonographic, pathologic, immunohistochemical, and gene expression studies were performed in all animals. The total number of mast cells, proportion of degranulated mast cells and the number of extracellular granules in plaques, the apoptosis rate of vascular smooth cells, the local activities of chymase, the concentration of Ang II and the expression levels of inflammatory markers as well as plaque vulnerability index all increased significantly in HC+ovalbumin treated group, but remarkably decreased in HC+tranilast treated group, in comparison with the HC treated group. These results suggest that stimulation of chymase secretion contributes to plaque vulnerability while inhibition of chymase activity enhances plaque stability. We conclude that chymase activity provides a promising therapeutic target in the stabilization of atherosclerotic plaques.

Dominant-negative mutation of monocyte chemoattractant protein-1 prevents vulnerable plaques from rupture in rabbits independent of serum lipid levels

Active inflammation is an important feature of vulnerable plaques, and monocyte chemoattractant protein‐1 (MCP‐1) is a key chemokine that promotes monocyte–endothelium binding and initiates inflammation. We aimed to determine whether dominant‐negative mutation of MCP‐1 could reverse atherosclerotic lesion progression and prevent vulnerable plaques from rupture regardless of serum lipid levels. The mutant MCP‐1 was produced by deletion of the N‐terminal amino acids 2 to 8 (7ND), and a eukaryotic expression vector plRES‐EGFP‐7ND was constructed. The transwell chamber was used to assay chemotaxis of monocytes in vitro. Thirty New Zealand white rabbits underwent balloon‐induced abdominal aortic endothelial injury and were randomly divided into control group without gene intervention (group A, n = 10), plRES‐EGFP‐7ND treatment group (group B, n = 10) and empty vector treatment group (group C, n = 10). All rabbits were fed a diet of 1% cholesterol for 8 weeks, and then group A rabbits were killed, whereas groups B and C rabbits received an intramuscular injection of plRES‐EGFP‐7ND and an empty lipofectamine, respectively, and remained on a high cholesterol diet for 4 weeks. At the end of week 12, groups B and C rabbits underwent pharmacological triggering by injection with Chinese Russellis viper venom and histamine. Serum lipids and inflammatory markers were measured, and high‐frequency ultra‐sonography and intravascular ultrasound imaging were performed. Immunohistochemistry and RT‐PCR were used to examine expression of inflammatory markers in the plaques. In vitro transfection of plRES‐EGFP‐7ND resulted in a significant inhibition of monocyte chemotaxis (P < 0.05) and in vivo transfection of plRES‐EGFP‐7ND significantly increased the thickness of the fibrous caps and decreased plaque vulnerability index. The incidence of plaque rupture in group B was 0% as compared with 56% in the empty vector treatment group (P< 0.05). The serum levels and expression of inflammatory markers were significantly reduced in group B. In conclusion, PIRES‐EGFP‐7ND transfection effectively inhibits plaque inflammation, reverses plaque progression and prevents vulnerable plaques from rupture. These therapeutic effects are independent of serum lipid levels and demonstrate that inhibition of plaque inflammation alone without lipid lowering can stabilize vulnerable plaques.

Peak radial and circumferential strain measured by velocity vector imaging is a novel index for detecting vulnerable plaques in a rabbit model of atherosclerosis

AIMS To evaluate the reliability of velocity vector imaging (VVI) for detecting vulnerable plaques. METHODS AND RESULTS After aortic balloon injury, 60 rabbits were fed a 1% cholesterol diet for 10 weeks and normal chow for another 6 weeks. Adenovirus containing p53 or lac Z was then injected into the aortic plaques and rabbits were divided into p53-treated group (n=20), lac Z-treated group (n=20) and blank control group (n=20). Peak longitudinal (LSp), radial (RSp) and circumferential (CSp) strain of plaques was measured using VVI at the end of week 18 before pharmacological triggering. Higher RSp and CSp and lower LSp were found in ruptured than those in non-ruptured plaques, and RSp, CSp and LSp correlated well with the fibrous cap thickness and plaque content of macrophages, smooth muscle cells and collagen (all p<0.01). A logistic regression model showed that both RSp (RR: 8.96, 95% CI: 5.3575-10.4857, p<0.001) and CSp (RR: 8.45, 95% CI: 5.9043-9.1043, p<0.001) were significant predictors of plaque rupture. RSp and CSp had a sensitivity of 88.0% and 88.6% and a specificity of 88.6% and 92.0% to predict plaque disruption, respectively. CONCLUSION VVI offers a new and noninvasive technique for measuring the peak strain of atherosclerotic plaques and RSp and CSp are a novel index with a high sensitivity and specificity for detecting plaques vulnerable to rupture.

Intraplaque injection of Ad5‐CMV.p53 aggravates local inflammation and leads to plaque instability in rabbits

This study aims to develop a new animal model of vulnerable plaques and investigate the potential mechanisms of exogenous p53‐induced plaque instability. Forty rabbits underwent aortic balloon injury, were fed a 1% cholesterol diet for 10 weeks and then normal chow for 6 weeks. Rabbits were divided into Ad5‐CMV.p53‐treated group (n= 16), Ad5‐CMV.lac Z‐treated group (n= 16) and blank control group (n= 8). Under the guidance of intravascular ultrasound, a 50‐μl suspension of adenovirus containing p53 or lac Z was injected into the largest plaque of the first two groups, respectively, and these rabbits received pharmacological triggering 2 weeks later. In 76.9% of rabbits with p53 transfection, plaque rupture was found, which was significantly (P < 0.05) higher than that in the Ad5‐CMV.lac Z‐treated plaques (23.1%), or blank controls plaques (0%). Increased apoptotic cells, and subsequently, decreased vascular smooth muscle cells and collagen content, enhanced intima macrophage accumulation, increased C‐reactive protein (CRP) and matrix metalloproteinases staining and high serum levels of high sensitive CRP (hs‐CRP) and monocyte chemoattractant protein‐1 (MCP‐1) were observed in Ad5‐CMV.p53‐treated rabbits. However, a binary logistic regression model revealed that hs‐CRP concentration rather than apoptosis rate played an independent role in plaque rupture with an odds ratio as 1.314 (95% CI: 1.041–1.657, P= 0.021), and there were high positive correlations between inflammatory biomarkers (hs‐CRP or MCP‐1) and apoptosis (R2= 0.761, and R2= 0.557, respectively, both P < 0.01). Intraplaque injection of p53 gene provides a safe and effective method for inducing plaque vulnerability in rabbits. The destabilizing effect of p53 overexpression is mediated mainly through apoptosis‐enhanced inflammation rather than cell apoptosis itself.

Effects of loading dose of atorvastatin before percutaneous coronary intervention on periprocedural myocardial injury.

ObjectivesTo investigate the effects of loading dose of atorvastatin on periprocedural myocardial injury and inflammatory reaction in patients with non-ST segment elevation (NSTE) acute coronary syndromes (unstable angina or NSTE acute myocardial infarction). MethodsA total of 81 patients with NSTE-acute coronary syndromes were randomly divided into the pretreatment with atorvastatin group [80 mg 12 h before percutaneous coronary intervention (PCI), with a further 40 mg preprocedure dose] (n=41) or the placebo group (n=40). The main end point was a 30-day incidence of major adverse cardiac events (cardiac death, nonfatal acute myocardial infarction, or revascularization with either PCI or coronary artery bypass grafting). Creatine kinase-MB, cardiac troponin I, and high-sensitivity C-reactive protein levels were measured at the baseline and at 8 and 24 h after the procedure. ResultsMajor adverse cardiac events occurred in 2.4% of patients in the atorvastatin group and 22.5% of those in the placebo group (P=0.0161). This difference was mostly because of reduction in the incidence of myocardial infarction (2.4 vs. 20.0%; P=0.0307). Markers of the two groups were elevated after PCI; however, the higher values of creatine kinase-MB, cardiac troponin I, and high-sensitivity C-reactive protein in the atorvastatin treatment group were significantly lower than those in the placebo group (P<0.01). ConclusionShort-term pretreatment with a high dose of atorvastatin significantly reduces procedural myocardial injury in early PCI.

Gax gene transfer inhibits vascular remodeling induced by adventitial inflammation in rabbits

AIMS Adventitial fibroblasts (AFs) and inflammation play an important role in neointimal formation and vascular remodeling. The present study was aimed to investigate the therapeutic effects and underlying mechanisms of transcriptional regulator Gax gene transfection in aortic remodeling induced by adventitial inflammation. METHODS AND RESULTS Fifty rabbits fed a chow diet were randomly divided into a normal control group (n=10) and experimental group (n=40). All rabbits in the experimental group underwent collar placement around the abdominal aorta and intra-collar injection of lipopolysaccharide (LPS) to induce adventitial inflammation and they were further divided into model control group, saline-treated group, green fluorescence protein (Ad-GFP)-treated group and Gax gene (Ad-Gax)-treated group, respectively. Four weeks after treatment, the model control group, saline-treated group and Ad-GFP-treated group showed thickened neointima and adventitia, reduced lumen size and increased eccentricity and remodeling index of the abdominal aorta in comparison with the normal control group, whereas Ad-Gax-treated group exhibited attenuated neointimal formation and vascular remodeling (P<0.01-0.05) .The vascular expression levels of interleukin (IL)-1β, IL-6, IL-8, monocyte chemoattractant protein (MCP)-1, matrix metalloproteinase (MMP)-1, MMP-2, MMP-9, vascular cell adhesion molecule (VCAM)-1 and intercellular adhesion molecule (ICAM)-1, Smads, mitogen-activated protein kinases (MAPKs), integrins and nuclear factor kappa B (NF-kB) were significantly higher in the model control group, saline-treated group and Ad-GFP-treated group than those in the normal control group (P<0.01-0.05). In contrast, the local expression levels of these cytokines were substantially reduced by Ad-Gax gene transfer (P<0.01-0.05). Similarly, the serum levels of inflammatory cytokines including C-reactive protein (CRP), transforming growth factor (TGF)-β1, IL-1, IL-6, IL-8, tumor necrosis factor (TNF)-α, MCP-1, VCAM-1 and ICAM-1 were significantly higher in the model control group, saline-treated group and Ad-GFP-treated group than those of the Ad-Gax-treated group (P<0.01-0.05). In vitro studies showed that Gax overexpression diminished inflammatory cytokine expression in LPS-stimulated arterial fibroblasts. CONCLUSIONS Adventitial inflammation induces vascular remodeling via the interactions of multiple inflammatory cytokines and local Gax gene transfer in vivo can significantly inhibit these interactions and thereby attenuate local inflammation and vascular remodeling.

Doxycycline stabilizes vulnerable plaque via inhibiting matrix metalloproteinases and attenuating inflammation in rabbits.

Enhanced matrix metalloproteinases (MMPs) activity is implicated in the process of atherosclerotic plaque instability. We hypothesized that doxycycline, a broad MMPs inhibitor, was as effective as simvastatin in reducing the incidence of plaque disruption. Thirty rabbits underwent aortic balloon injury and were fed a high-fat diet for 20 weeks. At the end of week 8, the rabbits were divided into three groups for 12-week treatment: a doxycycline-treated group that received oral doxycycline at a dose of 10 mg/kg/d, a simvastatin-treated group that received oral simvastatin at a dose of 5 mg/kg/d, and a control group that received no treatment. At the end of week 20, pharmacological triggering was performed to induce plaque rupture. Biochemical, ultrasonographic, pathologic, immunohistochemical and mRNA expression studies were performed. The results showed that oral administration of doxycycline resulted in a significant increase in the thickness of the fibrous cap of the aortic plaque whereas there was a substantial reduction of MMPs expression, local and systemic inflammation, and aortic plaque vulnerability. The incidence of plaque rupture with either treatment (0% for both) was significantly lower than that for controls (56.0%, P<0.05). There was no significant difference between doxycycline-treated group and simvastatin-treated group in any serological, ultrasonographic, pathologic, immunohistochemical and mRNA expression measurement except for the serum lipid levels that were higher with doxycycline than with simvastatin treatment. In conclusion, doxycycline at a common antimicrobial dose stabilizes atherosclerotic lesions via inhibiting matrix metalloproteinases and attenuating inflammation in a rabbit model of vulnerable plaque. These effects were similar to a large dose of simvastatin and independent of serum lipid levels.