Étude de la régulation transcriptionnelle de ICAM-1 : implication de la voie JAK/STAT

La molécule d'adhésion intercellulaire-1 (ICAM-1, CD54) est une glycoprotéine membre de la superfamille des immunoglobulines exprimée à la surface d'une grande variété de types cellulaires. Sa fonction première est de lier les β2-intégrines LFA-1 et MAC-1 exprimées à la surface des lymphocytes et des macrophages, respectivement. Cette interaction permet à ces derniers d'atteindre le site de l'inflammation en procédant à leur liaison à l'endothélium vasculaire et à leur extravasation. L'expression de ICAM-1 fût par contre également associée à diverses pathologies telles que l'asthme, l'arthrite rhumatoïde, le diabète, le développement des plaques athérosclérotiques et le développement des métastases. Bien que l'expression constitutive de ICAM-1 soit relativement faible, elle peut être augmentée par de nombreux médiateurs de l'inflammation tels que le TNF-α et l'IFNγ. Ces signaux amplifient l'expression de ICAM-1 au niveau transcriptionnel par diverses voies de signalisation menant à l'activation de facteurs de transcription tels que NF-KB et Stati. Ces facteurs de transcription agissent en se liant aux multiples éléments de réponse présents sur le promoteur de ICAM-1. La capacité de ces facteurs de transcription à activer la transcription de ICAM-1 dépend de nombreuses interactions physiques et fonctionnelles dont la nature n'est pas toujours bien connue. Par ailleurs, les voies de signalisation menant à l'inactivation de la transcription de ICAM-1 demeurent également incertaines. Étant donné le rôle capital de ICAM-1 au sein du système immunitaire, il est essentiel d'approfondir nos connaissances sur les différentes étapes menant à l'activation tout comme l'inactivation de la transcription de ce gène. Nous avons donc étudié la relation entre deux familles de facteurs de transcription impliquées dans la régulation transcriptionnelle de ICAM-1, soit la famille STAT et la famille Ets. Nous avons non seulement découvert qu'il existe une coopération fonctionnelle entre ces deux familles, mais également que le facteur de transcription Stati interagit physiquement avec le facteur de transcription Etsl dans les cellules vivantes. Ensuite, nous avons étudié les effets du bpV(pic), un inhibiteur de tyrosine phosphatase, sur l'activation de la transcription de ICAM-1. Nous avons découvert que ce composé de peroxovanadium inactive les phosphatases responsables de l'inactivation de la voie JAK/STAT suite au traitement à l'IFNγ. Finalement, nous avons testé un nouveau protocole d'électroporation à double impulsion permettant une grande efficacité de transfection transitoire des cellules endothéliales à faible coût

Self-assembled metal nanoparticles into rings: application to plasmonics

International audienc

Self-assembly of metallic nanoparticles into plasmonic rings

International audienceMetallic nanoparticles are self-assembled into plasmonic nanorings. The self-assembly is evaporation-induced and is driven using a template of dielectric microspheres. We obtain well-ordered arrays of metallic nanorings over large areas. The inner and outer diameters of the rings, as well as the pitch of the array, are fully controllable. The optical resonances supported by the plasmonic rings are then characterized using extinction spectroscopy. Our approach opens a simple and inexpensive road to create plasmonic structures that can find applications as metamaterials or substrates for enhanced spectroscopies

Self-assembled plasmonic nanorings

International audienceMetallic nanoparticles are self-assembled into plasmonic nanorings using an evaporation-driven bottom-up approach. Well-ordered arrays of nanorings with controllable diameter and pitch are obtained on large areas. Their optical resonances are then characterized using extinction spectroscopy

Self-organization of Au colloids assisted by copolymer templates

International audienc

Self-organization of Au colloids assisted by copolymer templates

International audienc

Self-organization of Au colloids assisted by copolymer templates

International audienceContext For the past fifteen years, the investigations of the Localized Surface Plasmon Resonance (LSPR) for plasmonic nanoparticles (NPs) has opened new perspectives for optical nanosensors. Indeed, there is no longer the need of using a prism in order to excite plasmons. The application possibilities are all the more numerous as the fundamental studies go to the direction of single molecule sensing. What is at stake today is the development of such large scale and low cost devices. Scientific aim and methods The scientific aim is here to use Polystyrene-Polymethylmethacrylate (PS-PMMA) copolymers as templates for small Au NPs (6-12nm large) self-organization onto substrates (see Figure 1). We developed two processes: 1) Incorporation of functionalized Au NPs in copolymer solution and organization in PS domains either by thermal annealing or Langmuir-Blodgett method 2) Incorporation of Au salts in PS-PMMA copolymer solution and in-situ synthesis and organization of Au NPs in PS domains. Results These processes are original routes to organize Au NPs onto substrates in order to fabricate optical nanosensors (see Figure 2). Surprisingly, the extinction optical measurements showed an expected main LSPR peak at about 550nm (for 10nm Au NPs) but also a second or even a third peak at longer wavelengths (respectively ~700nm and ~800nm). Discrete Dipole Approximation (DDA) simulations confirmed the experimental results and tend to argue that the 2nd and/or 3rd peak would come from coupling between very close Au NPs. Conclusion This study opens new routes for large-scale fabrication and organization of Au NPs onto substrates. It could pave the way for developing optical nanosensors when the polymer layer is thin enough

Self-organization of Au colloids assisted by copolymer templates

International audienceContext For the past fifteen years, the investigations of the Localized Surface Plasmon Resonance (LSPR) for plasmonic nanoparticles (NPs) has opened new perspectives for optical nanosensors. Indeed, there is no longer the need of using a prism in order to excite plasmons. The application possibilities are all the more numerous as the fundamental studies go to the direction of single molecule sensing. What is at stake today is the development of such large scale and low cost devices. Scientific aim and methods The scientific aim is here to use Polystyrene-Polymethylmethacrylate (PS-PMMA) copolymers as templates for small Au NPs (6-12nm large) self-organization onto substrates (see Figure 1). We developed two processes: 1) Incorporation of functionalized Au NPs in copolymer solution and organization in PS domains either by thermal annealing or Langmuir-Blodgett method 2) Incorporation of Au salts in PS-PMMA copolymer solution and in-situ synthesis and organization of Au NPs in PS domains. Results These processes are original routes to organize Au NPs onto substrates in order to fabricate optical nanosensors (see Figure 2). Surprisingly, the extinction optical measurements showed an expected main LSPR peak at about 550nm (for 10nm Au NPs) but also a second or even a third peak at longer wavelengths (respectively ~700nm and ~800nm). Discrete Dipole Approximation (DDA) simulations confirmed the experimental results and tend to argue that the 2nd and/or 3rd peak would come from coupling between very close Au NPs. Conclusion This study opens new routes for large-scale fabrication and organization of Au NPs onto substrates. It could pave the way for developing optical nanosensors when the polymer layer is thin enough

Tissue‐Engineered Disease Modeling of Lymphangioleiomyomatosis Exposes a Therapeutic Vulnerability to HDAC Inhibition

Abstract Lymphangioleiomyomatosis (LAM) is a rare disease involving cystic lung destruction by invasive LAM cells. These cells harbor loss‐of‐function mutations in TSC2, conferring hyperactive mTORC1 signaling. Here, tissue engineering tools are employed to model LAM and identify new therapeutic candidates. Biomimetic hydrogel culture of LAM cells is found to recapitulate the molecular and phenotypic characteristics of human disease more faithfully than culture on plastic. A 3D drug screen is conducted, identifying histone deacetylase (HDAC) inhibitors as anti‐invasive agents that are also selectively cytotoxic toward TSC2−/− cells. The anti‐invasive effects of HDAC inhibitors are independent of genotype, while selective cell death is mTORC1‐dependent and mediated by apoptosis. Genotype‐selective cytotoxicity is seen exclusively in hydrogel culture due to potentiated differential mTORC1 signaling, a feature that is abrogated in cell culture on plastic. Importantly, HDAC inhibitors block invasion and selectively eradicate LAM cells in vivo in zebrafish xenografts. These findings demonstrate that tissue‐engineered disease modeling exposes a physiologically relevant therapeutic vulnerability that would be otherwise missed by conventional culture on plastic. This work substantiates HDAC inhibitors as possible therapeutic candidates for the treatment of patients with LAM and requires further study

Placental growth factor as a marker of fetal growth restriction caused by placental dysfunction

INTRODUCTION: Discriminating between placentally-mediated fetal growth restriction and constitutionally-small fetuses is a challenge in obstetric practice. Placental growth factor (PlGF), measurable in the maternal circulation, may have this discriminatory capacity.METHODS: Plasma PlGF was measured in women presenting with suspected fetal growth restriction (FGR; ultrasound fetal abdominal circumference &lt;10th percentile for gestational age) at sites in Canada, New Zealand and the United Kingdom. When available, placenta tissue underwent histopathological examination for lesions indicating placental dysfunction, blinded to PlGF and clinical outcome. Lesions were evaluated according to pre-specified severity criteria and an overall severity grade was assigned (0-3, absent to severe). Low PlGF (concentration &lt;5th percentile for gestational age) to identify placental FGR (severity grade≥2) was assessed and compared with routine parameters for fetal assessment. For all cases, the relationship between PlGF and the sampling-to-delivery interval was determined.RESULTS: Low PlGF identified placental FGR with an area under the receiver-operator characteristic curve of 0.96 [95% CI 0.93-0.98], 98.2% [95% CI 90.5-99.9] sensitivity and 75.1% [95% CI 67.6-81.7] specificity. Negative and positive predictive values were 99.2% [95% CI 95.4-99.9] and 58.5% [95% CI 47.9-68.6], respectively. Low PlGF outperformed gestational age, abdominal circumference and umbilical artery resistance index in predicting placental FGR. Very low PlGF (&lt;12 pg/mL) was associated with shorter sampling-to-delivery intervals than normal PlGF (13 vs. 29.5 days, P &lt; 0.0001).DISCUSSION: Low PlGF identifies small fetuses with significant underlying placental pathology and is a promising tool for antenatal discrimination of FGR from fetuses who are constitutionally-small.</p