Metabolic syndrome in spontaneously hypertensive rats : Study of cGMP pathway modulators on cardiovascular reactivity and gut microbiota composition

Le syndrome métabolique associe plusieurs facteurs de risques cardiovasculaires chez le même individu. Des études ont montré une altération de la voie de signalisation du NO/GMPc au cours du syndrome métabolique. Le premier objectif de cette thèse a été d’étudier la modification de la fonction cardiaque globale et de la réactivité vasculaire des rats spontanément hypertendus (SHR) soumis à un régime hypercalorique de type « cafeteria diet » (CD). Dans un second temps, les effets de l’administration chronique des modulateurs de la voie du GMPc ont été évalués sur les paramètres métaboliques et la fonction circulatoire par des approches in vivo et ex vivo sur cœur et aorte isolés. Le microbiote intestinal apparait depuis quelques années comme un nouveau facteur impliqué dans la pathogenèse du syndrome métabolique et des altérations qui lui sont associées. Ainsi, une troisième partie de la thèse a été consacrée à l’analyse du microbiote intestinal chez les SHR avant et après traitements. Cette étude a montré que le régime CD induit les différentes composantes du syndrome métabolique. Ces anomalies étaient associées à une altération de la contractilité cardiaque et vasculaire ainsi qu’à une altération de la vasorelaxation induite par l’insuline. De plus, notre étude a montré des modifications dans la composition du microbiote intestinal à l’échelle « famille » et « espèce ». L’activation chronique de la voie du GMPc a amélioré les paramètres métaboliques mesurés in vivo et a rétabli partiellement la fonction circulatoire. Notre étude a montré pour la première fois les effets de la modulation de la voie du GMPc sur la composition du microbiote intestinal.The metabolic syndrome associates several cardiovascular risk factors in the same individual. Studies have already shown an alteration of the NO / cGMP signaling pathway during metabolic syndrome. The first aim of this thesis was to study the modification of the global cardiac function and the vascular reactivity in spontaneously hypertensive rats (SHR) subjected to a hypercaloric diet called "cafeteria diet" (CD). In a second step, effects of chronic administration of cGMP pathway modulators were evaluated on metabolic parameters and cardiovascular function using in vivo and ex vivo approaches on isolated heart and aorta. The gut microbiota has emerged for some years as a new factor involved in the pathogenesis of the metabolic syndrome and associated alterations. Thus, a third part of the thesis was devoted to the analysis of gut microbiota in SHR before and after treatment. This study has shown that CD diet induces the different components of metabolic syndrome. These abnormalities were associated with impaired cardiac and vascular contractility and an altered insulin-induced vasorelaxation. On the other hand, our study showed changes in the gut microbiota composition at the "family" and "species" level. Chronic activation of the cGMP pathway improved metabolic parameters measured in vivo and partially restored cardiovascular function. Our study showed for the first time, the effects of cGMP pathway modulators on gut microbiota composition

Sildenafil citrate long-term treatment effects on cardiovascular reactivity in a SHR experimental model of metabolic syndrome.

Much evidence indicates that metabolic syndrome is strongly correlated with a decrease in nitric oxide and an increase in oxidative stress leading to cardiovascular alterations. In recent years, gut microbiota has emerged as a new contributor to the metabolic syndrome establishment and associated cardiovascular diseases, but the underlying mechanisms remain unclear. We hypothesized that a positive modulation of cyclic guanosine monophosphate (cGMP) pathway, through phosphodiesterase type 5 (PDE5) inhibition could prevent cardiovascular alterations and gut dysbiosis that may be associated to metabolic syndrome. Spontaneously hypertensive rats (SHR) were randomly divided into 4 groups: control, cafeteria diet (CD) and sildenafil citrate treated groups (5mg/kg per os) were given either a CD or a standard chow diet for 10 weeks. Body weight, arterial blood pressure and glucose tolerance test were monitored. At the 10th week, cardiac inotropy and coronary perfusion pressure were evaluated on isolated heart according to Langendorff method. Cumulative concentration response curves to phenylephrine and acetylcholine were determined on thoracic aorta rings for vascular reactivity evaluation. Faecal samples were collected for the gut microbiota analysis. Compared to the control group, CD-fed rats showed a significant increase in body weight gain, arterial blood pressure and were glucose intolerant. This group showed also a decrease in β-adrenoceptor-induced cardiac inotropy and coronary vasodilation. Gut microbiota analysis revealed a significant reduction in the abundance of Lactobocillus spp in cafeteria diet-fed rats when compared to the control ones. Sildenafil citrate long-term treatment decreased weight gain and arterial blood pressure, improved coronary vasodilation and reduced α1-adrenoceptor-induced vasoconstriction in CD group. However, it did not reverse gut dysbiosis induced by chronic CD feeding. These results suggest that cGMP pathway targeting may be a potential therapeutic strategy for the management of the metabolic syndrome and associated cardiovascular disorders

Factors other than metalloprotease are required for full virulence of French Vibrio tubiashii isolates in oyster larvae

International audienceVibrio tubiashii is a marine pathogen isolated from larval and juvenile bivalve molluscs that causes bacillary necrosis. Recent studies demonstrated the isolation of this species in a French experimental hatchery/nursery affecting Crassostrea gigas spat in 2007. Here, using larvae of C. gigas as an interaction model, we showed that the French V. tubiashii is virulent to larvae and can cause bacillary necrosis symptoms with an LD50 of about 2.3x10(3) c.f.u. ml(-1) after 24 h. Moreover, complete or gel permeation HPLC fractionated extracellular products (ECPs) of this strain appeared toxic to larvae. MS-MS analysis of the different ECP fractions revealed the existence of an extracellular metalloprotease and other suspected virulence factors. This observation is also supported by the expression level of some potential virulence factors. The overall results suggest that the pathology caused by the French V. tubiashii in C. gigas oysters is caused by a group of toxic factors and not only the metalloprotease

Cutaneous leiomyosarcoma on the trunk: unusual presentation with an aggressive course – case report and review of literature

Primary cutaneous leiomyosarcoma (PCL) are soft-tissue sarcoma, arising in the dermis, with or without extension into the subcutis. They are thought to have an indolent course compared to their subcutaneous counterparts, they may recur but rarely metastases. We report the case of a patient with a PCL arising in the anterior trunk wall who developed pulmonary, bone and retroperitoneal metastases 6 years after wide surgical excision of the primary tumor

First description of French V. tubiashii strains pathogenic to mollusk: II. Characterization of properties of the proteolytic fraction of extracellular products

Extracellular products (ECPs) of the French V. tubiashii strain 07/118 T2 were previously reported to be toxic for the Pacific oyster Crassostrea gigas. In this study we now assessed host cellular immune responses and bacterial potential effectors by which these ECPs can be associated with host damages. The adhesion capacity (28% inhibition) and phagocytosis ability (56% inhibition) of oyster hemocytes were the main functions affected following in vitro contact between hemocytes and V. tubiashii ECPs. This may be linked to the demonstration of the capability of ECPs to cleave various cellular substrates as oyster collagen. Moreover, a strong metalloproteolytic activity was recorded with general (azocasein) and specific (ADAM) substrates and characterized by the use of standard inhibitors and metal ions. The addition of 1, 10-phenanthroline and Zn2+ decreased proteolytic activity by about 80% and 50% respectively, confirming the presence of zinc metalloproteolytic activity in the ECPs. Mass spectrometry analyses of crude ECPs identified an extracellular zinc metalloprotease encoded by a gene with an open reading frame of 1821 bp (606 aa). Consensus zinc-binding motifs specific to thermolysin family and some glycosylation and phosphorylation sites were located on the deduced protein sequence. Even if taken together, our results let us wonder if this (these) zinc metalloprotease(s) could be involved in the impairment of hemocyte immunological functions, the direct implication of this (these) protein(s) in ECPs toxicity still has to be demonstrated

Inhalation of Acidic Nanoparticles Prevents Doxorubicin Cardiotoxicity Through Improvement of Lysosomal Function

Doxorubicin (Dox) is an effective anticancer molecule, but its clinical efficacy is limited by strong cardiotoxic side effects. Lysosomal dysfunction has recently been proposed as a new mechanism of Dox-induced cardiomyopathy. However, to date, there is a paucity of therapeutic approaches capable of restoring lysosomal acidification and function in the heart. We designed novel poly(lactic-co-glycolic acid) (PLGA)-grafted silica nanoparticles (NPs) and investigated their therapeutic potential in the primary prevention of Dox cardiotoxicity in cardiomyocytes and mice. We showed that NPs-PLGA internalized rapidly in cardiomyocytes and accumulated inside the lysosomes. Mechanistically, NPs-PLGA restored lysosomal acidification in the presence of doxorubicin or bafilomycin A1, thereby improving lysosomal function and autophagic flux. Importantly, NPs-PLGA mitigated Dox-related mitochondrial dysfunction and oxidative stress, two main mechanisms of cardiotoxicity. In vivo, inhalation of NPs-PLGA led to effective and rapid targeting of the myocardium, which prevented Dox-induced adverse remodeling and cardiac dysfunction in mice. Our findings demonstrate a pivotal role for lysosomal dysfunction in Dox-induced cardiomyopathy and highlight for the first time that pulmonary-driven NPs-PLGA administration is a promising strategy against anthracycline cardiotoxicity