Search

Background and aims: The anti-inflammatory agent colchicine is gaining interest as a treatment for coronary artery disease. However, the effects of colchicine in atherosclerotic animal models are mostly unknown. This study aimed to evaluate colchicine in a rabbit model of atherosclerosis. Methods: Twenty-two rabbits were fed a 0.5% cholesterol-enriched diet for 10 weeks and then randomized to receive either oral saline (n=11) or colchicine (350 μg/kg/day; n=11) for 6 weeks, with 0.2% cholesterol-diet during the treatment period. We performed intravascular ultrasound imaging (at start and end of treatment) and histology analyses of the descending thoracic aorta. Leucocyte activation was assessed in vitro on blood samples obtained during treatment. Results: Colchicine prevented positive aortic vascular remodelling (p=0.029 vs placebo). This effect was even more marked at high plasma cholesterol level (third quartile of plasma cholesterol, p=0.020). At high cholesterol level, both atherosclerotic plaque and media areas on histomorphology were reduced by colchicine compared to placebo (p=0.031 and p=0.039, respectively). Plaque fibrosis and macrophage area were reduced by colchicine (Masson's trichrome stain: p=0.038; RAM-11: p=0.026). The plaque vulnerability index, assessed by histology, was reduced by colchicine (p=0.040). Elastin/type I collagen ratio in media was significantly higher with colchicine compared to placebo (p=0.013). At a high level of plasma cholesterol, in vitro LPS challenge revealed a decrease in monocyte activation following treatment with colchicine (p

Background We previously demonstrated that high-density lipoprotein (HDL) infusions may improve left ventricular diastolic dysfunction (LVDD) in an aortic valve stenosis (AVS) model. Whether the benefit was direct or mediated by the observed reduction in AVS severity is not clear. Here, we aimed to test the direct effect of an ApoA-I mimetic on LVDD in the absence of AVS. Methods Rabbits were exposed to three different protocols to develop LVDD. First, rabbits were exposed to 0.5% cholesterol-rich diet for an average of 17 weeks. Second, rabbits were subjected to surgical ascending aortic constriction (AAC), to mimic the effect of fixed reduced aortic valve area, and studied after 10 weeks. The third model combined both cholesterol-enriched diet (for 12 weeks) and surgical AAC. The control group consisted of age-matched rabbits under normal diet. After development of LVDD, rabbits were randomized to receive infusions of saline or apoA-I mimetic (25 mg/kg) 3 times per week for 4 weeks. Detailed cardiac structure and function measurements were assessed at baseline and weekly during treatment period. Histological and molecular analyses were performed on LV samples. Results In the three models, echocardiographic results showed development of LVDD over time, with preserved LV systolic and aortic valve functions versus controls. ApoA-I mimetic infusions did not significantly improve echocardiographic parameters nor molecular markers of cardiac inflammation, oxidative stress and fibrosis. Conclusion ApoA-I mimetic therapy did not directly improve LVDD. These results indicate that previously observed changes of LVDD were caused by AVS improvement induced by this treatment.

The acute respiratory distress syndrome (ARDS) is characterized by intense dysregulated inflammation leading to acute lung injury (ALI) and respiratory failure. There are no effective pharmacologic therapies for ARDS. Colchicine is a low-cost, widely available drug, effective in the treatment of inflammatory conditions. We studied the effects of colchicine pre-treatment on oleic acid-induced ARDS in rats. Rats were treated with colchicine (1 mg/kg) or placebo for three days prior to intravenous oleic acid-induced ALI (150 mg/kg). Four hours later they were studied and compared to a sham group. Colchicine reduced the area of histological lung injury by 61%, reduced lung edema, and markedly improved oxygenation by increasing PaO2/FiO2 from 66 ± 13 mmHg (mean ± SEM) to 246 ± 45 mmHg compared to 380 ± 18 mmHg in sham animals. Colchicine also reduced PaCO2 and respiratory acidosis. Lung neutrophil recruitment, assessed by myeloperoxidase immunostaining, was greatly increased after injury from 1.16 ± 0.19% to 8.86 ± 0.66% and significantly reduced by colchicine to 5.95 ± 1.13%. Increased lung NETosis was also reduced by therapy. Circulating leukocytosis after ALI was not reduced by colchicine therapy, but neutrophils reactivity and CD4 and CD8 cell surface expression on lymphocyte populations were restored. Colchicine reduces ALI and respiratory failure in experimental ARDS in relation with reduced lung neutrophil recruitment and reduced circulating leukocyte activation. This study supports the clinical development of colchicine for the prevention of ARDS in conditions causing ALI.

BackgroundLeft ventricular diastolic dysfunction (LVDD) is present in more than 50% of patients suffering from heart failure. LVDD animal models are limited and its underlying mechanisms remain largely unknown. Aortic valve stenosis (AVS) may cause LVDD, and we recently reported LVDD in an AVS rabbit model. Here we aimed to develop a rabbit model of LVDD without AVS.MethodsRabbits were fed with a 0.5% cholesterol-enriched diet (n = 9) or normal diet (n = 8) until they developed LVDD defined by a value of the echocardiographic parameter E/Em ratio higher than the mean at baseline + 2SD. Rabbits were then fed a 0.2% cholesterol-enriched diet for 4 weeks (average total diet duration: 20 weeks). Detailed cardiac structure and function measurements were assessed by echocardiography at baseline, weeks 8, 12 and 14 to 20, when applicable. Histological analyses and RT-qPCR were performed on LV samples.ResultsThe hypercholesterolemic diet induced LVDD without systolic dysfunction or AVS, as shown by multiple echocardiographic parameters, including early filling mitral peak velocity and deceleration rate, Em/Am ratio and E/Em ratio (all pConclusionRabbits fed with a cholesterol-enriched diet develop LVDD with preserved systolic function and evidence of cardiac inflammation and oxidative stress. This rabbit model may be used in future studies to test treatment strategies against LVDD.

This study aimed to evaluate the feasibility and accuracy of a technique for atherosclerosis imaging using local delivery of relatively small quantities (0.04–0.4 mg/kg) of labeled-specific imaging tracers targeting ICAM-1 and unpolymerized type I collagen or negative controls in 13 rabbits with atheroma induced by balloon injury in the abdominal aorta and a 12-week high-cholesterol diet. Immediately after local infusion, in vivo intravascular ultrasonography (IVUS)-NIRF imaging was performed at different time-points over a 40-minute period. The in vivo peak NIRF signal was significantly higher in the molecular tracer-injected rabbits than in the control-injected animals (P Ex vivo peak NIRF signal was significantly higher in the ICAM-1 probe-injected rabbits than in controls (P = 0.04), but not in the collagen probe-injected group (P = 0.29). NIRF signal discrimination following dual-probe delivery was also shown to be feasible in a single animal and thus offers the possibility of combining several distinct biological imaging agents in future studies. This innovative imaging strategy using in vivo local delivery of low concentrations of labeled molecular tracers followed by IVUS-NIRF catheter-based imaging holds potential for detection of vulnerable human coronary artery plaques.

Aortic valve stenosis (AVS) is the most common valvular heart disease in the Western world. Therapy based on apolipoprotein A-I (apoA-I), the major protein component of high-density lipoproteins, results in AVS regression in experimental models. Nevertheless, apoA-I degradation by proteases might lead to suboptimal efficacy of such therapy. An activatable probe using a quenched fluorescently labeled full-length apoA-I protein was generated to assess apoA-I-degrading protease activity in plasma derived from 44 men and 20 women with severe AVS (age 65.0 ± 10.4 years) as well as from a rabbit model of AVS. In human and rabbit AVS plasma, apoA-I-degrading protease activity was significantly higher than in controls (humans: 0.038 ± 0.009 vs 0.022 ± 0.005 RFU/s, p

Background Infusions of apolipoprotein A-I (apoA-I), the major protein component of high-density lipoproteins (HDL), result in aortic valve stenosis (AVS) regression in experimental models. Severe AVS can be complicated by acquired von Willebrand syndrome, a haemorrhagic disorder associated with loss of high-molecular-weight von Willebrand factor (vWF) multimers (HMWM), the latter being a consequence of increased shear stress and enhanced vWF-cleaving protease (ADAMTS-13) activity. Although antithrombotic actions of HDL have been described, its effects on ADAMTS-13 and vWF in AVS are unknown. Methods and Results We assessed ADAMTS-13 activity in plasma derived from a rabbit model of AVS (n = 29) as well as in plasma collected from 64 patients with severe AVS (age 65.0 ± 10.4 years, 44 males) undergoing aortic valve replacement (AVR). In both human and rabbit AVS plasma, ADAMTS-13 activity was higher than that in controls (p Conclusion Our data indicate that HDL levels are associated with reduced ADAMTS-13 activity and increased HMWM. HDL-based therapies may reduce the haematologic abnormalities of the acquired von Willebrand syndrome in AVS.

Atherosclerotic cardiovascular diseases are characterized by the formation of a plaque in the arterial wall. Intravascular ultrasound (IVUS) provides high-resolution images allowing delineation of atherosclerotic plaques. When combined with near infrared fluorescence (NIRF), the plaque can also be studied at a molecular level with a large variety of biomarkers. In this work, we present a system enabling automated volumetric histology imaging of excised aortas that can spatially correlate results with combined IVUS/NIRF imaging of lipid-rich atheroma in cholesterol-fed rabbits. Pullbacks in the rabbit aortas were performed with a dual modality IVUS/NIRF catheter developed by our group. Ex vivo three-dimensional (3D) histology was performed combining optical coherence tomography (OCT) and confocal fluorescence microscopy, providing high-resolution anatomical and molecular information, respectively, to validate in vivo findings. The microscope was combined with a serial slicer allowing for the imaging of the whole vessel automatically. Colocalization of in vivo and ex vivo results is demonstrated. Slices can then be recovered to be tested in conventional histology.

Background and Aim: Left ventricular diastolic dysfunction (LVDD) refers to abnormal filling of the left ventricle (LV) due to its impaired relaxation or increased stiffness. Animal models of LVDD are limited and underlying mechanisms remain largely unknown. We aimed to assess LVDD in Ldlr -/- mice using imaging and gene expression measurements. Methods: Sixty-nine Ldlr -/- mice were fed with a western-type diet supplemented with vitamin D 2 (30 U/g/day) for 20 weeks to induce LVDD. Eight normal mice were fed with a normal diet and used as control group. Serial echocardiograms were used to assess cardiac structure and function, histological analyses were done on LV sections, and RT-PCR was performed on LV samples. Results: Echocardiographic results show the development of LVDD over time (P values Ldlr -/- mice compared to controls as detected by Masson’s trichrome staining, which was correlated with increased mRNA expression for TGFß1 and Smad2 and 3 (PCol I : 1.33 (1.03; 1.97) vs 1.03 (0.90; 1.11), P=0.06; Col III : 1.49±0.30 vs 1.00±0.10, P=0.14). The angiotensin II precursor Agt mRNA level was also higher (1.07±0.08 vs 0.72±0.05; PLdlr -/- mice compared to controls. Conclusion: Taken together, Ldlr -/- mice fed with a western diet supplemented with vitamin D 2 develop progressive LVDD, perivascular fibrosis and mild left ventricular hypertrophy, which represents a new model of lipid-mediated diastolic dysfunction that may be used in future studies for the evaluation of novel treatments.

Purpose: High-density lipoprotein (HDL) infusions induce rapid improvement of atherosclerosis and aortic valve stenosis (AVS) in animals but their effect on left ventricular diastolic dysfunction (LVDD) remains unknown. Our study aimed at evaluating the effects of the HDL mimetic peptide CER-522 on LVDD in a rabbit model of AVS. Methods: Thirty-five (35) male New-Zealand White rabbits were fed with a 0.5% cholesterol- and vitamin D2-enriched diet until mild AVS was detected by echocardiography (mean duration of diet: 16 weeks). Animals were then randomized to receive saline (control group, n = 11) or the HDL mimetic peptide CER-522 at doses of 10 mg/kg (n = 12) or 30 mg/kg (n = 12) 3 times per week for 2 weeks. Serial echocardiograms and end-of-study histological examination of the aortic valve and left ventricle were performed. Results: Aortic valve area increased at day 10 in the CER-522 10 mg/kg group (P = 0.016) and at day 14 in both the CER-522 10 and 30 mg/kg treated groups compared to controls (P = 0.011 and P = 0.033, respectively). Aortic root strain index was higher in both CER-522 treated groups vs controls at 14 days of treatment (P = 0.007 and P = 0.047, respectively). At day 14, compared to controls, CER-522 normalized early filling deceleration time (P < 0.001 for both treated groups) and E wave deceleration rate (P < 0.001 for both treated groups), decreased E/Em ratio (P < 0.001 and P = 0.001 for the 10 and 30 mg/kg groups, respectively) and increased Em/Am ratio (P < 0.001 and P = 0.025). Although all groups had similar amount of global LVDD before treatment, moderate LVDD was present in 36.4, 16.7 and 0% of animals in the control, CER-522 10 and 30 mg/kg groups respectively at study end (P = 0.216 and P < 0.001 for 10 and 30 mg/kg groups vs controls). Histological analyses showed that RAM-11 positive cells (macrophages) in LV myocardium and pericoronary fibrosis were reduced with CER-522 10 mg/kg compared to controls (P = 0.006 and P = 0.018). The number of apoptotic cardiomyocytes was reduced by CER-522 30 mg/kg vs controls (P = 0.010; P=NS for 10 mg/kg). Coronary artery atheroma area was decreased in both CER-522 groups vs controls (P = 0.028 and P = 0.044 for 10 and 30 mg/kg groups), as was the case for the coronary external/internal elastic lamina area ratio (P = 0.003 and P = 0.010). Conclusions: The HDL mimetic peptide CER-522 improves LVDD in rabbits while also reducing cardiomyocyte apoptosis, mild AVS, aortic root rigidity and coronary atherosclerosis.