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Background and Purpose: Previous studies demonstrated that intraplaque haemorrhage increased the contents of cholesterol and oxidants in atherosclerotic plaques. The present study was aimed to test the hypothesis that enhanced expression of haem oxygenase-1 (HO-1) may stabilize vulnerable plaques.Experimental Approach: Intravascular ultrasound (IVUS) was performed to identify three similar abdominal aortic plaques in each of 58 fat-fed New Zealand rabbits after aortic balloon injury. With the guidance of IVUS, 50 microL autologous erythrocytes (RBC) or normal saline (NS) were injected from adventitia into two of the pre-selected plaques, respectively, whereas the third plaque served as a blank control. All rabbits were randomly divided into two groups, receiving intraperitoneal injection of haemin and saline respectively.Key Results: Compared with NS or control plaques, RBC plaques had more macrophage infiltration and lipid content, thinner plaque fibrous cap, and higher expression of inflammatory factors and incidence of plaque rupture. RBC plaques in the haemin group had about a 50% lower incidence of plaque rupture than those in the control group.Conclusions and Implications: Haem oxygenase-1 may eliminate haem or other oxidants, exert unexpected anti-oxidative and anti-inflammatory effects and serve as a promising approach to the direct inhibition of erythrocyte-induced plaque instability. [ABSTRACT FROM AUTHOR]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]