Jean Baptiste Michel

Low-Dose Aspirin May Prevent Growth and Later Surgical Repair of Medium-Sized Abdominal Aortic Aneurysms

Experimental data suggest that aspirin-induced platelet inhibition may retard growth of abdominal aortic aneurysms. In this article, whether low-dose aspirin use is associated with reduced aneurysm progression and subsequent need for surgery is examined. In this observational cohort study within a screening trial, 148 patients with small aneurysms (maximum diameter 30-48 mm) annually are followed. Patients were referred for surgery when the aneurysmal diameter exceeded 50 mm. Median follow-up time was 6.6 years. Among patients whose abdominal aortic aneurysms were initially 40 to 49 mm in size, the abdominal aortic aneurysm expansion rate for low-dose aspirin users compared with nonusers was 2.92 mm/y versus 5.18 mm/y (difference 2.27 mm/y, 95% CI, 0.42-4.11). No difference in expansion rates and risk ratios for operative repair was found for patients with abdominal aortic aneurysms <40 mm. For medium-sized abdominal aortic aneurysms, low-dose aspirin may prevent abdominal aortic aneurysm growth and need for subsequent repair, but residual confounding cannot be excluded.

The translational science of Marfan syndrome

Marfan syndrome has changed over the last few years: new diagnostic criteria have been proposed, new clinical entities recognised and life expectancy increased. The role of fibrillin 1, which was initially thought to be mainly structural, has been shown to also be functional. The altered transforming growth factor β pathway is better understood, the importance of epigenetic factors has been demonstrated and recent data suggest that many of the observations made in Marfan syndrome can actually be made in thoracic aortic aneurysm from diverse aetiologies. Besides transforming growth factor β, the role of metalloproteinase, the fibrinolytic/coagulation system, is being suggested in the progression of the disease. A relationship between the type of fibrillin 1 (FBN1) gene mutation and the mechanism for the disease (haplo-insufficiency vs negative dominance), as well as some genotype/phenotype correlations, has been observed, although the main challenge of recognising gene modifiers has yet to explain tremendous variability despite similar mutation. This progress has led to new hopes for tomorrows therapies, some of which are being tested in clinics, whereas others are still in the field of animal models. Here we review some of the new data obtained in the understanding of the pathophysiology and genetics of this disease.

Long-term effects of angiotensin-converting enzyme inhibition on the arterial wall of adult spontaneously hypertensive rats

The effects of long-term angiotensin-converting enzyme (ACE) inhibitor treatment with perindopril 2 mg/kg/day, by gavage, for 3 months on the mechanical function and structure of large arteries were studied in adult spontaneously hypertensive rats with established hypertension. Hemodynamic parameters, including instantaneous aortic blood flow and pressure, were recorded under anesthesia at the end of the treatment period. Systemic arterial compliance was calculated from aortic pressure and flow recordings; passive mechanical properties of the in situ localized carotid artery were measured. Histologic and morphologic parameters of the aortic media, including cross-sectional area and thickness, size, and density of smooth muscle nuclei and of elastin and collagen fibers, were measured using an automated image analysis system. ACE inhibitor treatment significantly decreased mean arterial pressure (-27%, p < 0.001) and total peripheral resistance (-30%, p < 0.05) while cardiac output was increased (29%, p < 0.05). Systemic arterial compliance and carotid compliance were both increased by treatment (63%, p < 0.05, and 83%, p < 0.05, respectively). Morphometric assessment of vascular structure showed that ACE inhibitor treatment significantly decreased medial cross-sectional area (-36%, p < 0.001) and thickness (-16%, p < 0.001) by affecting smooth muscle cell hypertrophy (nucleus size decreased by 26%, p < 0.05) without changes in smooth cell number. Collagen density was decreased by treatment (-42%, p < 0.05), whereas elastin density was not affected by treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Localization of elastin mRNA and TGF-β1 in rat aorta and caudal artery as a function of age

Abstract Several in vitro studies have previously demonstrated that the addition of TGF-β to aortic smooth muscle cells or skin fibroblasts stimulates elastin synthesis. It is not clear however whether, in vivo, TGF-β participates in the regulation of elastin synthesis, especially in physiological conditions. The aim of our study was to explore the localization of elastin mRNA and TGF-β1 in the rat thoracic aorta (an elastic artery) and caudal artery (a muscular artery). Elastin mRNA was localized by in situ hybridization and quantified using Northern blot analysis. TGF-β1 was detected using immunohistochemistry. The study was carried out as a function of age (rats of 3, 10, 20, and 30 months). We observed that TGF-β1 immunoreactivity is present predominantly, but not exclusively, at the sites of elastin synthesis as determined by elastin mRNA detection: in smooth muscle cells in the aorta and in endothelial cells in the caudal artery. The ability of exogenously added TGF-β1 (0.001–10 ng/ml) to modulate the steady-state levels of elastin mRNA in primary cultures of endothelial cells, smooth muscle cells, and fibroblasts isolated from the thoracic aorta was also studied. At the highest concentration used, elastin mRNA levels increased 5-fold in endothelial cells and 11-fold in smooth muscle cells. The demonstration that TGF-β1 immunoreactivity is present at the sites of elastin synthesis in the thoracic aorta and in the caudal artery and the observation that TGF-β1 induces an increase in elastin mRNA levels in cultured endothelial cells and smooth muscle cells suggest that TGF-β1 may be implicated, at least in part, in the physiological regulation of elastin gene expression.

Metabolites secreted by human atherothrombotic aneurysms revealed through a metabolomic approach.

Abdominal aortic aneurysm (AAA) is perma-nent and localized dilation of the abdominal aorta. Intraluminal thrombus (ILT) is involved in evolution and rupture of AAA. Complex biological processes associated with AAA include oxidative stress, proteolysis, neovascularization, aortic inflammation, cell death, and extracellular matrix breakdown. Biomarkers of growth and AAA rupture could give a more nuanced indication for surgery, unveil novel pathogenic pathways, and open possibilities for pharmacological inhibition of growth. Differential analysis of metabolites released by normal and pathological arteries in culture may help to find molecules that have a high probability of later being found in plasma and start signaling processes or be useful diagnostic/prognostic markers. We used a LC-QTOF-MS metabolomic approach to analyze metabolites released by human ILT (divided into luminal and abluminal layers), aneurysm wall (AW), and healthy wall (HW). Statistical analysis was used to compare luminal with abluminal ILT layer, ILT with AW, and AW with HW to select the metabolites exchanged between tissue and external medium. Identified compounds are related to inflammation and oxidative stress and indicate the possible role of fatty acid amides in AAA. Some metabolites (e.g., hippuric acid) had not been previously associated to aneurysm, others (fatty acid amides) have arisen, indicating a very promising line of research.

Salmeterol restores secretory functions in cystic fibrosis airway submucosal gland serous cells

The activity of the cystic fibrosis (CF) transmembrane conductance regulator (CFTR) can be mediated by surface G protein-coupled receptors such as the beta(2)-adrenergic receptor. In this study, we explored the effect of a long-acting beta(2)-adrenergic agonist, salmeterol, on the CFTR-dependent secretory capacity of a human CF tracheal gland serous cell line (CF-KM4), homozygous for the delF508 mutation. We showed that, compared with the untreated CF serous cells, a 24-hour pre-incubation period with 200 nM salmeterol induced an 83% increase in delF508-CFTR-mediated chloride efflux. The restoration of the bioelectric properties is associated with increased apical surface pool of delF508-CFTR. Salmeterol induced a decrease in ion concentration and an increase in the level of hydration of the mucus packaged inside the CF secretory granules. The effects of salmeterol are not associated with a persistent production of cAMP. Western blotting on isolated secretory granules demonstrated immunoreactivity for CFTR and lysozyme. In parallel, we measured by atomic force microscopy an increased size of secretory granules isolated from CF serous cells compared with non-CF serous cells (MM39 cell line) and showed that salmeterol was able to restore a CF cell granule size similar to that of non-CF cells. To demonstrate that the salmeterol effect was a CFTR-dependent mechanism, we showed that the incubation of salmeterol-treated CF serous cells with CFTR-inh172 suppressed the restoration of normal secretory functions. The capacity of salmeterol to restore the secretory capacity of glandular serous cells suggests that it could also improve the airway mucociliary clearance in patients with CF.

M1 macrophages act as LTβR-independent lymphoid tissue inducer cells during atherosclerosis-related lymphoid neogenesis

AIMS The goal of this study was to characterize the role of inflammatory macrophages in the induction of the vascular smooth muscle cell (VSMC)-mediated formation of aortic tertiary lymphoid organs (TLOs). METHODS AND RESULTS Mouse bone marrow-derived M1 macrophages acted as lymphoid tissue inducer cells. Indeed, they expressed high levels of tumour necrosis factor (TNF)-α and membrane-bound lymphotoxin (LT)-α, two inducing cytokines that triggered expression of the chemokines CCL19, CCL20, and CXCL16, as did M1 supernatant. The blockade of LTβR signalling with LTβR-Ig had no effect, whereas that of TNFR1/2 signalling reduced chemokine expression by VSMCs in both wild-type (WT) and LTβR KO mice, demonstrating that LTβR signalling is dispensable for the M1-inducing effect. This effect was corroborated by the development of TLOs observed in LTβR KO->apolipoprotein E knockout (ApoE KO) aortic segments after orthotopic transplantation. Furthermore, treatment of ApoE KO mice with anti-TNF-α antibody decreased the number and incidence of aortic TLOs. Finally, lymphoid nodules composed of T and B cells formed in in vivo-implanted scaffolds seeded with VSMCs previously stimulated ex vivo by M1-conditioned medium. CONCLUSIONS These results are the first to identify M1 macrophages as inducer cells that trigger the expression of chemokines by VSMCs independently of LTβR signalling. We propose that the dialogue between macrophages and VSMCs-established across the vascular wall-contributes to the formation of aortic TLOs.

Efficacy of intra-tendinous injection of platelet-rich plasma in treating tendinosis: comprehensive assessment of a rat model

ObjectivesTo assess the potential of intra-tendinous injection of platelet rich plasma (PRP) to treat tendinosis (T+) in a rat model of patellar and Achilles T+, and evaluate its local toxicity.MethodsThirty rats (120 patellar and Achilles tendons) were used. We induced T+ into 80 tendons (patellar = 40, Achilles = 40) by injecting collagenase at day 0 under ultrasound (US) guidance. Clinical examination and US at day 3, followed by US-guided intra-tendinous injection of either PRP (PRPT+, n = 40) or physiological serum (ST+, n = 40, control). Follow-up was at days 6, 13, 18 and 25 using clinical, US and histological evaluation. To study PRP toxicity, we injected PRP into 40 normal tendons (PRPT-) and compared with 40 untreated normal tendons (T-).ResultsAll PRPT+ showed better joint mobilisation compared with ST+ at day 6 (P = 0.005), day 13 (P = 0.02), day 18 (P = 0.003) and day 25 (P = 0.01). Similar results were found regarding US and histology, with smaller collagen fibre diameters (day 6, P = 0.003, day 25, P ≤ 0.004), less disorganisation and fewer neovessels (day 6, P = 0.003, day 25, P = 0.0003) in PRPT+ compared with ST+. Comparison between PRPT- and T- showed no PRP toxicity (P = 0.18).ConclusionsOur study suggests that mono-injection of PRP in T+ improves tendon healing, with no local toxicity.Key Points• We assessed the potential of platelet rich plasma (PRP) to treat tendinosis.• We treated patellar and Achilles tendinosis in a rat model.• We evaluated clinical, imaging and histological data.• Intra-tendinous PRP injection could be useful in the treatment of tendinosis.

Atrial natriuretic peptide decreases contractility of cultured chick ventricular cells

To determine whether atrial natriuretic peptide (ANP) has an inotropic effect, the contractility of spontaneously beating cultured chick embryo ventricular cells was studied in response to rat-ANP (1-23) superfused at concentrations ranging from 10(-10) M to 2.5 x 10(-7) M. r-ANP reversibly decreased contractility with a threshold concentration of 10(-8) M; at the highest concentration, r-ANP decreased contractility to a moderate extent (-30 +/- 4%) r-ANP increased dose-dependently intracellular cGMP levels. Stimulation of contractility with [Ca2+], the calcium-channel agonist BAY K 8644 or isoproterenol attenuated to various degrees the inhibitory effect of r-ANP. By contrast, the inhibitory effect of r-ANP on contractility was unchanged or even enhanced after stimulation of contractility by angiotensin II. There was no difference in r-ANP-induced increase in cGMP whether cells were pre-incubated with angiotensin II or not. These results indicate that r-ANP was able to decrease contractility of cultured cardiac myocytes and suggest a preferential antagonism of the inotropic effect of angiotensin II.

Anti-Platelet Treatment of Middle-Sized Abdominal Aortic Aneurysms

The physiological transport in the aortic wall occurs mainly by centrifugal convection from the lumen to the adventitia through the arterial wall. Enlargement of an abdominal aortic aneurysm (AAA) is usually associated with the development of an intraluminal mural thrombus (ILT). The interface between the luminal side of the thrombus and flowing blood is a site of constant thrombus renewal, which is linked to platelet aggregation-induced fibrin generation and accumulation. In addition, red blood cells are entrapped causing an oxidative response. Through centrifugal convection are factors increasing the inflammatory and degenerative response transported from the ILT to media and adventitia. Two experimental studies on rats with experimental AAA have shown that aneurysmal progression can be impaired by antiplatelet agents. By a systematic literature search, 4 human cohorts were identified analysing the effect of antiplatelet treatment on the progression of AAA. The two largest cohorts couldn´t detect any significant difference. However, the cohorts included very small AAA, in which ILT seldom is present. In the two other trials, only testing AAA sized above 35 and 39 mm, respectively, use of low dose aspirin was associated with significantly lower expansion rates and less need for later surgical repair. Size-based subgroup analyses from relevant existing cohorts ought to be conducted for confirmation. Finally, low dose aspirin is recommend as general cardiovascular secondary prevention, however, large-scaled trials comparing low dose aspirin with more potent antiplatelets would be relevant.