Rôle de la phosphoinositide 3-Kinase gamma dans la paroi artérielle : une cible thérapeutique dans le traitement de l'athérosclérose et de ses complications ?

Le rôle de l'inflammation dans le développement des maladies cardiovasculaires reste un domaine majeur d'investigation dans la recherche de nouvelles thérapies. En effet, l'inflammation constitue un élément essentiel de la pathologie de l'athérosclérose mais également de la resténose, complication majeure du traitement par angioplastie de l'athérosclérose. Les cellules inflammatoires ainsi que les médiateurs immuns sont impliqués dans toutes les étapes du développement de l'athérosclérose. Elles participent également à la modulation phénotypique des cellules musculaires lisses (CML) qui vont acquérir un phénotype migratoire et prolifératif aboutissant à l'hyperplasie intimale, celle-ci constituant le mécanisme majeure de la resténose. L'isoforme gamma des phosphoinositide 3-kinases (PI3Kgamma) a fait l'objet d'un intérêt croissant ces dernières années dans les pathologies inflammatoires. Ces kinases appartiennent à la classe I des PI3K capables de générer du phosphatidylinositol 3,4,5-trisphosphate (PIP3) impliqués dans la régulation d'un grand nombre de processus biologiques. La classe I des PI3K est divisée en deux sous-classes, la classe IA (p110alpha, beta et delta) classiquement activée par les tyrosine kinases, et la classe IB (p110gamma) activée par les récepteurs couplés aux protéines G hétérotrimériques. La génération de souris invalidées pour la PI3Kgamma a permis de montrer que les voies de signalisation impliquant cette kinase modulaient des fonctions immunitaires plaçant la PI3Kgamma comme un bon candidat dans la recherche de cibles thérapeutiques pour le traitement de pathologies auto-immunes. De plus, des études récentes ont montré un profil d'expression complexe de la PI3Kgamma incluant de faibles taux d'expression de cette kinase dans différents types cellulaires du système cardiovasculaire notamment dans les CML. L'ensemble de ces données a permis de poser l'hypothèse d'un rôle possible de la PI3Kgamma dans l'athérogénèse et ses complications. Ainsi dans une première partie, nous nous sommes intéressés au rôle de la PI3Kgamma dans le développement de l'athérosclérose. L'administration intrapéritonéale d'un inhibiteur pharmacologique spécifique de la PI3Kgamma conduit à une diminution du développement de lésions athéromateuses précoces mais aussi de plaques plus avancées dans deux modèles murins d'athérosclérose. De plus, à l'aide de souris chimères dépourvues de la PI3Kgamma dans le système immunitaire, nous avons démontré le rôle central de la PI3Kgamma dans les processus inflammatoires de la paroi artérielle conduisant au développement de la plaque d'athérome et participant à sa déstabilisation. La deuxième partie de ce travail s'est intéressée aux fonctions de la PI3Kgamma dans les cellules composant la paroi artérielle et plus particulièrement les CML. Ce travail réalisé in vitro a permis de mettre en évidence l'implication de la PI3Kgamma dans la migration des CML stimulées par la chimiokine MCP-1 (monocyte chemotactic protein-1). De plus, nous avons montré que la PI3Kgamma pouvait servir d'amplificateur de la réponse au PDGF par un mécanisme autocrine/paracrine faisant intervenir le complexe MCP-1/CCR2 (MCP-1 receptor). L'ensemble des propriétés de la PI3Kgamma dans la paroi artérielle que nous avons démontré placent cette kinase comme une cible thérapeutique de choix dans le traitement de l'athérosclérose et de ses complications.The role of inflammation in cardiovascular diseases has become an active area of investigation for the development of novel and innovative drugs targeting inflammatory proteins. Inflammation is a crucial event in atherosclerosis and restenosis, a major complication of atherosclerosis treatment by angioplasty. Inflammatory cells and immune factors are involved in all stages of the atherosclerotic process. Moreover, these cells are in part responsible for smooth muscle cell (SMC) migration and proliferation leading to intimal hyperplasia. The gamma isoform of phosphoinositide 3-kinase (PI3Kgamma) belongs to class I PI3K family producing 3-phosphoinositides and especially phosphatidylinositol-3,4,5-trisphosphate (PIP3) involved in many biological effects. The class I of PI3K is divided in two subclasses: class IA (p110alpha, beta and delta) classically activated through tyrosine kinase receptors and class IB (p110gamma), mainly activated by G protein-coupled receptors. Mice lacking catalytic subunits p110gamma have demonstrated a role of this isoform in several inflammatory and immune functions marking PI3Kgamma as a good candidate for drug development in autoimmune diseases. In addition to its functions in the immune system recent studies have demonstrated a more complex expression pattern in other cell types, particularly in SMC. These properties suggest that PI3Kgamma could play a role in atherosclerosis and its complications. In this work, we have first focused on the role of PI3Kgamma in atherosclerosis development. Our results demonstrate that a specific PI3Kgamma inhibitor is effective in murine models of established atherosclerosis. Intraperitoneal administration of PI3Kγ inhibitor significantly decreased early atherosclerotic lesions and attenuated more advanced atherosclerosis in two mouse models of atherosclerosis. Moreover chimeric mice lacking PI3Kgamma exclusively in immune cells showed that PI3Kγ plays an essential role in inflammatory processes of the vascular wall leading to the development of atherosclerosis and to plaque stability. In a second part, we investigate the specific involvement of PI3Kgamma in arterial wall and especially in SMC functions. Our results show that this kinase is essential to SMC migration induced by MCP-1 (monocyte chemotactic protein-1) in vitro. Moreover we demonstrate that PI3Kγ could amplify PDGF (platelet-derived growth factor)-stimulated SMC migration by an autocrine/paracrine pathway involving MCP-1 secretion and its receptor CCR2 activation. Altogether our results indicate that PI3Kgamma could be a potential new therapeutic target in atherosclerosis treatment and its complications

Elastin-derived peptides potentiate atherosclerosis through the immune Neu1-PI3Kγ pathway

Aims Elastin is degraded during vascular ageing and its products, elastin-derived peptides (EP), are present in the human blood circulation. EP binds to the elastin receptor complex (ERC) at the cell surface, composed of elastin-binding protein (EBP), a cathepsin A and a neuraminidase 1. Some in vitro functions have clearly been attributed to this binding, but the in vivo implications for arterial diseases have never been clearly investigated. Methods and results Here, we demonstrate that chronic doses of EP injected into mouse models of atherosclerosis increase atherosclerotic plaque size formation. Similar effects were observed following an injection of a VGVAPG peptide, suggesting that the ERC mediates these effects. The absence of phosphoinositide 3-kinase γ (PI3Kγ) in bone marrow-derived cells prevented EP-induced atherosclerosis development, demonstrating that PI3Kγ drive EP-induced arterial lesions. Accordingly, in vitro studies showed that PI3Kγ was required for EP-induced monocyte migration and ROS production and that this effect was dependent upon neuraminidase activity. Finally, we showed that degradation of elastic lamellae in LDLR−/− mice fed an atherogenic diet correlated with atherosclerotic plaque formation. At the same time, the absence of the cathepsin A-neuraminidase 1 complex in cells of the haematopoietic lineage abolished atheroma plaque size progression and decreased leucocytes infiltration, clearly demonstrating the role of this complex in atherogenesis and suggesting the involvement of endogenous EP. Conclusion Altogether, this work identifies EP as an enhancer of atherogenesis and defines the Neuraminidase 1/PI3Kγ signalling pathway as a key mediator of this function in vitro and in viv

Obesity promotes fumonisin B1 hepatotoxicity

Obesity, which is a worldwide public health issue, is associated with chronic inflammation that contribute to long-term complications, including insulin resistance, type 2 diabetes and non-alcoholic fatty liver disease. We hypothesized that obesity may also influence the sensitivity to food contaminants, such as fumonisin B1 (FB1), a mycotoxin produced mainly by the Fusarium verticillioides. FB1, a common contaminant of corn, is the most abundant and best characterized member of the fumonisins family. We investigated whether diet-induced obesity could modulate the sensitivity to oral FB1 exposure, with emphasis on gut health and hepatotoxicity. Thus, metabolic effects of FB1 were assessed in obese and non-obese male C57BL/6J mice. Mice received a high-fat diet (HFD) or normal chow diet (CHOW) for 15 weeks. Then, during the last three weeks, mice were exposed to these diets in combination or not with FB1 (10 mg/kg body weight/day) through drinking water. As expected, HFD feeding induced significant body weight gain, increased fasting glycemia, and hepatic steatosis. Combined exposure to HFD and FB1 resulted in body weight loss and a decrease in fasting blood glucose level. This co-exposition also induces gut dysbiosis, an increase in plasma FB1 level, a decrease in liver weight and hepatic steatosis. Moreover, plasma transaminase levels were significantly increased and associated with liver inflammation in HFD/FB1-treated mice. Liver gene expression analysis revealed that the combined exposure to HFD and FB1 was associated with reduced expression of genes involved in lipogenesis and increased expression of immune response and cell cycle-associated genes. These results suggest that, in the context of obesity, FB1 exposure promotes gut dysbiosis and severe liver inflammation. To our knowledge, this study provides the first example of obesity-induced hepatitis in response to a food contaminant.L.D. PhD was supported by the INRAE Animal Health department. This work was also supported by grants from the French National Research Agency (ANR) Fumolip (ANR-16-CE21-0003) and the Hepatomics FEDER program of Région Occitanie. We thank Prof Wentzel C. Gelderblom for generously providing the FB1 and for his interest and support in our project. B.C. laboratory is supported by a Starting Grant from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. ERC-2018-StG- 804135), a Chaire d'Excellence from IdEx Université de Paris - ANR-18-IDEX-0001, an Innovator Award from the Kenneth Rainin Foundation, an ANR grant EMULBIONT ANR-21-CE15-0042-01 and the national program “Microbiote” from INSERM. We thank Anexplo (Genotoul, Toulouse) for their excellent work on plasma biochemistry. Neutral Lipids MS and NMR experiments were performed with instruments in the Metatoul-AXIOM platform. Sphingolipid MS analysis were performed with instruments in the RUBAM platform. The FB1 plasma levels were determined using an UPLC-MS/MS instrument part of the Ghent University MSsmall expertise centre for advanced mass spectrometry analysis of small organic molecules. We thank Elodie Rousseau-Bacquié and all members of the EZOP staff for their assistance in the animal facility. We are very grateful to Talal al Saati for histology analyses and review, and we thank all members of the US006/CREFRE staff at the histology facility and the Genom'IC platforms (INSERM U1016, Paris, France) for their expertise.Peer reviewe

Rôle de la phosphoinositide 3-Kinase gamma dans la paroi artérielle (une cible thérapeutique dans le traitement de l'athérosclérose et de ses complications ?)

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Neuraminidase 1 activates insulin receptor and reverses insulin resistance in obese mice

International audienc

Key role of PI3Kγ in monocyte chemotactic protein-1-mediated amplification of PDGF-induced aortic smooth muscle cell migration.

International audienceBACKGROUND AND PURPOSE: Vascular smooth muscle cell (SMC) migration within the arterial wall is a crucial event in atherogenesis and restenosis. Monocyte chemotactic protein-1/CC-chemokine receptor 2 (MCP-1/CCR2) signalling is involved in SMC migration processes but the molecular mechanisms have not been well characterized. We investigated the role of PI3Kγ in SMC migration induced by MCP-1. EXPERIMENTAL APPROACHES: A pharmacological PI3Kγ inhibitor, adenovirus encoding inactive forms of PI3Kγ and genetic deletion of PI3Kγ were used to investigate PI3Kγ functions in the MCP-1 and platelet-derived growth factor (PDGF) signalling pathway and migration process in primary aortic SMC. KEY RESULTS: The γ isoform of PI3K was shown to be the major signalling molecule mediating PKB phosphorylation in MCP-1-stimulated SMC. Using a PI3Kγ inhibitor and an adenovirus encoding a dominant negative form of PI3Kγ, we demonstrated that PI3Kγ is essential for SMC migration triggered by MCP-1. PDGF receptor stimulation induced MCP-1 mRNA and protein accumulation in SMCs. Blockade of the MCP-1/CCR2 pathway or pharmacological inhibition of PI3Kγ reduced PDGF-stimulated aortic SMC migration by 50%. Thus PDGF promotes an autocrine loop involving MCP-1/CCR2 signalling which is required for PDGF-mediated SMC migration. Furthermore, SMCs isolated from PI3Kγ-deficient mice (PI3Kγ(-/-)), or mice expressing an inactive PI3Kγ (PI3Kγ(KD/KD)), migrated less than control cells in response to MCP-1 and PDGF. CONCLUSIONS AND IMPLICATIONS: PI3Kγ is essential for MCP-1-stimulated aortic SMC migration and amplifies cell migration induced by PDGF by an autocrine/paracrine loop involving MCP-1 secretion and CCR2 activation. PI3Kγ is a promising target for the treatment of aortic fibroproliferative pathologies

Selective Inhibitors of Human Neuraminidase 3

Human neuraminidases (NEU) are associated with human diseases including cancer, atherosclerosis, and diabetes. To obtain small molecule inhibitors as research tools for the study of their biological functions, we designed a library of 2-deoxy-2,3-didehydro- N-acetylneuraminic acid (DANA) analogues with modifications at C4 and C9 positions. This library allowed us to discover selective inhibitors targeting the human NEU3 isoenzyme. Our most selective inhibitor for NEU3 has a K; i; of 320 ± 40 nM and a 15-fold selectivity over other human neuraminidase isoenzymes. This inhibitor blocks glycolipid processing by NEU3 in vitro. To improve their pharmacokinetic properties, various esters of the best inhibitors were synthesized and evaluated. Finally, we confirmed that our best compounds exhibited selective inhibition of NEU orthologues from murine brain

Regulation of hepatokine gene expression in response to fasting and feeding: Influence of PPARa and insulin-dependent signaling in hepatocytes

International audienceAim.-In hepatocyte, PPARa and insulin receptor (IR) are critical for the transcriptional responses to fasting and feeding, respectively. Here we analyzed the effects of the nutritional status (fasting vs feeding) on the expression of a large panel of hepatokines in hepatocyte-specific PPARa (Ppara hep−/−) and IR (IR hep−/−) null mice. Methods.-Ppara hep−/− , and IR hep−/− mice and their wild-type littermate were subjected to fasting or feeding metabolic challenges, and then analyzed for hepatokine gene expression. Experiments were conducted in mice of both sexes

Tissular Genomic Responses to Oral FB1 Exposure in Pigs

Fumonisin B1 (FB1) is a widespread mycotoxin produced by fungal Fusarium species—mainly in maize, one of the plants most commonly used for food and feed. Pigs and horses are the animal species most susceptible to this mycotoxin. FB1 exposure can cause highly diverse clinical symptoms, including hepatotoxicity, immunotoxicity, and intestinal barrier function disturbance. Inhibition of ceramide synthetase is a well-understood ubiquitous molecular mechanism of FB1 toxicity, but other more tissue-specific effects remain to be elucidated. To investigate the effects of FB1 in different exposed tissues, we cross-analyzed the transcriptomes of fours organs: liver, jejunum, jejunal Peyer’s patches, and spleen. During a four-week study period, pigs were fed a control diet or a FB1-contaminated diet (10 mg/kg feed). In response to oral FB1 exposure, we observed common biological processes in the four organs, including predominant and recurrent processes (extracellular matrix organization, integrin activation, granulocyte chemotaxis, neutrophil migration, and lipid and sterol homeostasis), as well as more tissue-specific processes that appeared to be related to lipid outcomes (cell cycle regulation in jejunum, and gluconeogenesis in liver)