Molecular Imaging of Microglial Activation in Amyotrophic Lateral Sclerosis

There is growing evidence of activated microglia and inflammatory processes in the cerebral cortex in amyotrophic lateral sclerosis (ALS). Activated microglia is characterized by increased expression of the 18 kDa translocator protein (TSPO) in the brain and may be a useful biomarker of inflammation. In this study, we evaluated neuroinflammation in ALS patients using a radioligand of TSPO, 18F-DPA-714. Ten patients with probable or definite ALS (all right-handed, without dementia, and untreated by riluzole or other medication that might bias the binding on the TSPO), were enrolled prospectively and eight healthy controls matched for age underwent a PET study. Comparison of the distribution volume ratios between both groups were performed using a Mann-Whitney’s test. Significant increase of distribution of volume ratios values corresponding to microglial activation was found in the ALS sample in primary motor, supplementary motor and temporal cortex (p = 0.009, p = 0.001 and p = 0.004, respectively). These results suggested that the cortical uptake of 18F-DPA-714 was increased in ALS patients during the ‘‘time of diagnosis’’ phase of the disease. This finding might improve our understanding of the pathophysiology of ALS and might be a surrogate marker of efficacy of treatment on microglial activation

Recommendations on using VPN over SATCOM

VPN are a secured tunnel that help service providers to exchange data over non-secured networks. There is a large variety of VPN solutions that have variable deployment impacts on the target architecture as well as performance limitations or opportunities. This technical report compares Wireguard and OpenVPN for various SATCOM deployment scenarios and topologies

TSPO PET Imaging: From Microglial Activation to Peripheral Sterile Inflammatory Diseases?

Peripheral sterile inflammatory diseases (PSIDs) are a heterogeneous group of disorders that gathers several chronic insults involving the cardiovascular, respiratory, gastrointestinal, or musculoskeletal system and wherein inflammation is the cornerstone of the pathophysiology. In PSID, timely characterization and localization of inflammatory foci are crucial for an adequate care for patients. In brain diseases, in vivo positron emission tomography (PET) exploration of inflammation has matured over the last 20 years, through the development of radiopharmaceuticals targeting the translocator protein-18 kDa (TSPO) as molecular biomarkers of activated microglia. Recently, TSPO has been introduced as a possible molecular target for PSIDs PET imaging, making this protein a potential biomarker to address disease heterogeneity, to assist in patient stratification, and to contribute to predicting treatment response. In this review, we summarized the major research advances recently made in the field of TSPO PET imaging in PSIDs. Promising preliminary results have been reported in bowel, cardiovascular, and rheumatic inflammatory diseases, consolidated by preclinical studies. Limitations of TSPO PET imaging in PSIDs, regarding both its large expression in healthy peripheral tissues, unlike in central nervous system, and the production of peripheral radiolabeled metabolites, are also discussed, regarding their possible consequences on TSPO PET signal’s quantification

The Story of the Dopamine Transporter PET Tracer LBT-999: From Conception to Clinical Use

The membrane dopamine transporter (DAT) is involved in a number of brain disorders and its exploration by positron emission tomography (PET) imaging is highly relevant for the early and differential diagnosis, follow-up and treatment assessment of these diseases. A number of carbon-11 and fluor-18 labeled tracers are to date available for this aim, the majority of them being derived from the chemical structure of cocaine. The development of such a tracer, from its conception to its use, is a long process, the expected result being to obtain the best radiopharmaceutical adapted for clinical protocols. In this context, the cocaine derivative (E)-N-(4-fluorobut-2-enyl)2β-carbomethoxy-3β-(4′-tolyl)nortropane, or LBT-999, has passed all the required stages of the development that makes it now a highly relevant imaging tool, particularly in the context of Parkinson's disease. This review describes the different steps of the development of LBT-999 which initially came from its non-fluorinated derivative (E)-N-(3-iodoprop-2-enyl)-2-carbomethoxy-3-(4-methylphenyl) nortropane, or PE2I, because of its high promising properties. [18F]LBT-999 has been extensively characterized in rodent and non-human primate models, in which it demonstrated its capability to explore in vivo the DAT localized at the dopaminergic nerve endings as well as at the mesencephalic cell bodies, in physiological conditions. In lesion-induced rat models of Parkinson's disease, [18F]LBT-999 was able to precisely quantify in vivo the dopaminergic neuron loss, and to assess the beneficial effects of therapeutic approaches such as pharmacological treatment and cell transplantation. Finally recent clinical data demonstrated the efficiency of [18F]LBT-999 in the diagnosis of Parkinson's disease

Les Radiopharmaceutiques pour l'imagerie moléculaire de la neuroinflammation

TOURS-BU Sciences Pharmacie (372612104) / SudocSudocFranceF

Imagerie moléculaire de la neuroinflammation (evaluation préclinique d'un nouveau radiopharmaceutique)

La protéine translocatrice 18kDa (TSPO), en reflétant l activation microgliale et la neuroinflammation, est actuellement reconnue comme un marqueur sensible de la survenue d événements pathologiques dans le cerveau. Par conséquent, la TSPO est une cible privilégiée pour l étude des pathologies du cerveau par imagerie moléculaire (TEP/TEMP). Il y a actuellement un manque d outils efficaces pour explorer la neuroinflammation en TEMP. Notre objectif a donc été d évaluer un nouveau radiopharmaceutique de forte affinité pour la TSPO, utilisable en TEMP : le CLINDE, dans deux modèles animaux : l excitotoxicité focale et l ischémie cérébrale. Dans ces deux modèles, les études ex vivo ont mis en évidence une accumulation préférentielle du [125I]-CLINDE dans les régions cérébrales lésées, riches en cellules microgliales. De plus, nous avons observé une relation quantitative entre l intensité de la lésion cérébrale et la fixation du radiopharmaceutique. Le CLINDE apparaît donc comme un candidat très prometteur pour l imagerie TEMP de la neuroinflammation en recherche clinique.The 18kDa Translocator protein (TSPO) is currently the most reliable marker for pathological events in the brain, reflecting microglial activation and neuroinflammation, which are linked to neuronal damage. Thereby, TSPO is a potential target to evaluate neuroinflammatory changes in a variety of brain diseases by molecular imaging (PET/SPECT). To date, there is a lack of effective tool to explore neuroinflammation by SPECT. Our aim was to evaluate a new high-affinity ligand for TSPO SPECT imaging: the CLINDE, in two rodent models: focal excitotoxicity and cerebral ischemia. In both animal models, ex vivo studies highlighted preferential localisation of [125I]-CLINDE accumulation in cerebral area that also expressed activated microglial cells as assessed by immunohistochemical staining. Moreover, we found a quantitative relationship between the intensity of brain damages and radiotracer binding, making CLINDE an attractive radioionidated candidate for imaging neuroinflammation by SPECT in clinical setting.TOURS-Bibl.électronique (372610011) / SudocSudocFranceF

A Novel Selective Inhibitor of CYP26B1 Potentiates the Effect of a Nanomolar Concentration of Retinoic Acid in Human Neuroblastoma SH-SY5Y Cells

Retinoic acid (RA) and its natural and synthetic derivatives are critical molecules for many biological processes, including cell proliferation and differentiation. Several studies demonstrated the RA therapeutic potential in neurodegenerative diseases treatment, showing higher tolerance to neurotoxicity and oxidative stress in vitro and in a Parkinson`s disease rodent model. Unfortunately, RA has a poor fate when administered externally in humans, inducing its own breakdown, resulting in activity loss during long-term treatment. Sice systemic administration of RA to overcome this situation require a high dose which can induce side effects in non-targeted organ/tissue, we sought to develop a new strategy to selectively increase RA concentration in the brain andinduce a neuroprotective effect. Among of the three CYP26 proteins indentified for mediating RA breakdown, CYP26B1 predominates in the brain whereas CYP26A1 on peripheral regions. Previously developed CYP26 inhibitors caused additional drug metabolizing enymes inhibition, resulting in limited usefulness. Therefore, is it possible to accurately and safely control RA concentrations for therapeutic benefit? Based on these evidences, we hypothesize that selective CYP26B1 inhibition will increase RA concentrations in brain and provide therapeutic advantages for patients with neurodegerative diseases without side effects associated with previously described non-specific CYP26 inhibitors. We designed a library of CYP26 inhibitors, among which are nanomolar-selective dual CYP26A1/B1 inhibitors, CYP26A1 inhibitors and selective CYP26B1 inhibitors. Cell culture were executed using human neuroblastoma SH-SY5Y cell line that can acquire neuron-like phenotypes after RA treatment. In this poster, we will report the effects on gene expression using PCR tecnic in SH-SY5Y cells treated with our CYP26 inhibitor and discuss about the neuroprotective effect of this compounds. The selected genes are modulated by RA-mediated signaling. We demonstrate RA metabolism inhibition, resulting increased RA concentration thereby inducing RA signaling in neuronal type cells

Nanovecteurs pour la délivrance d'acides nucléiques

L essor de la thérapie génique comme alternative thérapeutique repose sur le développement de vecteurs polyfonctionnels. Cette concerne l étude de cyclodextrines amphiphiles cationiques (CDac) et de détergents dimérisables et perfluoroalkylés permettant la formulation de systèmes de transfert de gènes fonctionnalisables. L étude de CDac a montré leur capacité à compacter l ADN en particules (CDplexes) de tailles inférieures à 100 nm. L évaluation de leur stabilité dans des milieux proches des conditions physiologiques, ainsi que de leur activité de transfection in vitro, a permis de dégager les différents éléments structuraux conditionnant leur efficacité. Un composé, Hex-CD-T-[CN]2, dont les CDplexes sont capables de transfecter plusieurs types cellulaires avec des efficacités comparables à celles obtenues avec les polyplexes de JetPEI tout en ayant de meilleures viabilités se démarque. L étude des voies d entrée des CDplexes a permis de montrer que la voie cavéole étaitr, pour ce type de vecteurs, la voie la plus efficace pour l expression du gène. La fonctionnalisation de ces CDplexes, soit de façon non covalente (en utilisant les capacités d inclusion des CDac) grâce à un conjugué Adamantane-PEG-Folate, soit par couplage covalent de clusters glycosylés sur les CDac, n a cependant pas permis de mettre en évidence une transfection spécifique. La fonctionnalisation de particules d ADN compacté par des détergents cationiques perfluoroalkylés dimérisable à l aide d un ligand peptidique cyclique, le cVEGI, visant les récepteurs KDR du VEGF a permis de générer, dans certaines conditions, une transfection spécifique sur des cellules surexprimant ces récepteurs.The elaboration of multifunctionnal vectors is a key step for efficient gene transfer. This thesis relates on the study of highly functionalizable DNA particles formulated either with cationic amphiphilic cyclodextrins (caCD) or cationic perfluoroalkylated and dimerisable detergents. caCD were shown to condense plasmid DNA into particles smaller than 100 nm called CDplexes. Our study also revealed the impact of different structural motifs on stability and gene activity of CDplexes. Nanoparticles formulated from the lead Hex-CD-T-[C2N]2 were shown to promote gene expression on various cell lines with higher efficiency than JetPEI polyplexes and with lower cytotoxicity profiles. A particular experiment, targeting at internalization pathways, showed that gene delivery through Hex-CD-T-[C2-N]2 CDplexes predominantly proceeds via a caveolar pathway. Cdpllexes functionalized either through cavity inclusion capabilities with Folate-anchor conjugate or by covalent grafting of glycosylated clusters on CD were not able to mediate specific transfection. DNA particles formulated with perfluoroalkylated and dimerizable detergents were coated with a cyclic peptide conjugate, cVEGI, targeting at VEGF receptors (KDR). These systems were shown to mediate specific transfection on VEGF surexpressing cell lines in certain conditions.NICE-BU Sciences (060882101) / SudocSudocFranceF

Les promesses de One Health : s'ouvrir à d'autres savoirs

International audienc

Fluorinated radiopharmaceuticals development for early diagnosis of Alzheimer's Disease in PET (Positron Emission Tomography)

VAChT et nAChRs sont de bons marqueurs cholinergiques impliqués dès les premiers stades de la maladie d Alzheimer. L imagerie moléculaire de ces deux marqueurs, en TEP nous permettrait d obtenir un diagnostic précoce de la MA. Concernant le VAChT, nous avons développé des dérivés du benzovésamicol : (2R, 3R)-5-FPOBV (10), (2S, 3S)-5-FPOBV (11) et (2R, 3R)-5-FEOBV (15). Ces composes ont été radiomarqués au fluor-18. In vivo et ex vivo, chez le rat et le babouin, une fixation cérébrale faible et homogène a été observée. De plus, nous avons observé une forte accumulation osseuse indiquant la défluoration des composés [18F]10 et [18 F]11. Ces trois composés apparaissent comme non utilisables pour effectuer de l imagerie moléculaire in vivo du VAChT. Concernant les nAChRs, le composé [18 F]21 a été radiomarqué au fluor-18 et évalué in vivo chez le babouin. Ce composé montre une sélectivité pour les récepteurs dans le thalamus et une forte, et non sélective fixation dans le striatum.VAChT and nAChRs are related cholinergic markers involved in the early stages of AD. Imaging both these targets using PET would be of benefit to obtain an early diagnosis of AD. In the case of VAChT, we developed benzovesamicol analogues : (2R, 3R)-5-FPOBV (10), (2S, 3S)-5-FPOBV (11) and (2R, 3R)-5-FEOBV (15). These compounds were radiolabelled with 18F then in ex vivo and in vivo evaluation (in rat and baboon), a low and homogeneous brain uptake was found. Futhermore, high accumulation of radioactivity in bone, indicating defluorination of [18F]10 and [18F]11 was observed. From these results, [18 F]10, [18F]11, [18F]15 appear not to be suitable for in vivo imaging of the VAChT. Concerning nAChRs, [18F]21 was radiolabelled with 18F then in vivo evaluation was performed in baboon. [18F]21 shows selectivity for the receptors in the thalamus and an unexpected uptake in the striatum which could be due to other nAChRs or other receptors.TOURS-BU Médecine (372612103) / SudocSudocFranceAustraliaFRA