Mouse vaccination with dendritic cells loaded with prion protein peptides overcomes tolerance and delays scrapie.

Prion diseases are presumed to be caused by the accumulation in the brain of a pathological protein called prion protein (PrP) scrapie which results from the transconformation of cellular PrP, a ubiquitous glycoprotein expressed in all mammals. Since all isoforms of PrP are perceived as self by the host immune system, a major problem in designing efficient immunoprophylaxis or immunotherapy is to overcome tolerance. The present study was aimed at investigating whether bone-marrow-derived dendritic cells (DCs) loaded with peptides previously shown to be immunogenic in PrP-deficient mice, can overcome tolerance in PrP-proficient wild-type mice and protect them against scrapie. Results show that, in such mice, peptide-loaded DCs elicit both lymphokine release by T cells and antibody secretion against native cellular PrP. Repeated recalls with peptide-loaded DCs reduces the attack rate of 139A scrapie inoculated intraperitoneally and retards disease duration by 40 days. Most interestingly, survival time in individual mice appears to be correlated with the level of circulating antibody against native cellular PrP

Gout and pseudo-gout-related crystals promote GLUT1-mediated glycolysis that governs NLRP3 and interleukin-1β activation on macrophages

Objective Macrophage activation by monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals mediates an interleukin (IL)-1β-dependent inflammation during gout and pseudo-gout flare, respectively. Since metabolic reprogramming of macrophages goes along with inflammatory responses dependently on stimuli and tissue environment, we aimed to decipher the role of glycolysis and oxidative phosphorylation in the IL-1β-induced microcrystal response. Methods Briefly, an in vitro study (metabolomics and real-time extracellular flux analysis) on MSU and CPP crystal-stimulated macrophages was performed to demonstrate the metabolic phenotype of macrophages. Then, the role of aerobic glycolysis in IL-1β production was evaluated, as well in vitro as in vivo using 18F-fluorodeoxyglucose positron emission tomography imaging and glucose uptake assay, and molecular approach of glucose transporter 1 (GLUT1) inhibition. Results We observed that MSU and CPP crystals led to a metabolic rewiring toward the aerobic glycolysis pathway explained by an increase in GLUT1 plasma membrane expression and glucose uptake on macrophages. Also, neutrophils isolated from human synovial fluid during gout flare expressed GLUT1 at their plasma membrane more frequently than neutrophils isolated from bloodstream. Both glucose deprivation and treatment with either 2-deoxyglucose or GLUT1 inhibitor suppressed crystal-induced NLRP3 activation and IL-1β production, and microcrystal inflammation in vivo. Conclusion In conclusion, we demonstrated that GLUT1-mediated glucose uptake is instrumental during the inflammatory IL-1β response induced by MSU and CPP crystals. These findings open new therapeutic paths to modulate crystal-related inflammation

Analogues peptidiques marqués au gallium-68 pour l’imagerie TEP des récepteurs membranaires couplés aux protéines G

In recent years, the targeting of G protein-coupled membrane receptors (GPCRs) with radiolabeled ligands has become very important in nuclear imaging, particularly with the progressive replacement of somatostatin analogues labelled with 111In for SPECT by others labelled with 68Ga for PET imaging, which improves diagnostic efficacy. High-affinity bombesin receptors (GRPR) or neurotensin receptors (NTR1) are also GPCRs overexpressed in many cancers as compared with normal tissue. GRPR is overexpressed in 83% of estrogen-dependent ductal carcinomas. In the first part of this work, we demonstrated that 68Ga-AMBA, an agonist ligand of GRPR, allowed the PET detection of a mouse model of estrogen-dependent breast cancer and could be more sensitive than 18F-FDG to predict and monitor tumour response to hormone therapy.Dr. Gruaz-Guyon's team has developed new neurotensin radioanalogues for targeting NTR1-positive tumours. They studied the properties of these 111In-labeled peptides in a model of colon adenocarcinoma overexpressing NTR1. Obtaining high-contrast images allowing the detection of cancer within a short time after injection, this team subsequently developed this peptide radiotracer for PET imaging. In the second part of this work, we carried out the 68Ga radiolabeling of the best-performing of these derivatives and evaluated its potential for PET imaging of colon adenocarcinoma in a tumor model. Overexpression of NTR1 has been demonstrated in several human cancers such as PDAC (75-88%). We characterized the expression of NTR1 using specimens of human pancreatic cancer and then demonstrated the potential of this PET radiotracer to image two mouse models of human PDAC. We characterized its biodistribution, assessed its specificity in vivo in comparison with 18F-FDG, in particular its ability to discriminate in vivo pancreatitis from pancreatic adenocarcinoma.Ces dernières années, le ciblage des RCPG avec des ligands radiomarqués est devenu très important en imagerie nucléaire, notamment avec le remplacement progressif d’analogues peptidiques de la somatostatine marqués à l’111In pour la TEMP par d’autres marqués au 68Ga pour l'imagerie TEP qui présente une meilleure efficacité diagnostique. Les récepteurs de haute affinité de la bombésine (GRPR) ou de la neurotensine (NTR1) sont eux aussi des RCPG surexprimés par les cellules tumorales par rapport au tissu sain. Le GRPR est surexprimé dans 83% des carcinomes mammaires canalaires estrogènes dépendants. Dans la première partie de ce travail, nous avons démontré qu’un agoniste du GRPR, l’AMBA marqué au 68Ga, permettait la détection en TEP d’un modèle murin de cancer du sein humain estrogène-dépendant et qu’il permettait de prédire la réponse tumorale à une hormonothérapie de manière plus sensible que le 18F-FDG.L’équipe du Dr. Gruaz-Guyon a développé de nouveaux radioligands analogues de la neurotensine pour le ciblage des tumeurs exprimant le NTR1 et a étudié les propriétés de ces peptides marqués à l'111In dans un modèle de tumeurs d’adénocarcinome colique surexprimant le NTR1. L’obtention d’images TEMP de contraste élevé, permettant une détection des greffes tumorales dans des temps courts après injection, a conduit cette équipe à envisager ce traceur peptidique pour l’imagerie TEP. Dans la seconde partie de ce travail, nous avons réalisé le radiomarquage au 68Ga du meilleur de ces dérivés (DOTA NT20.3) et évalué son potentiel pour l'imagerie TEP et la détection de tumeurs d’adénocarcinome colique. La surexpression de NTR1 a été démontrée dans plusieurs autres cancers comme l’adénocarcinome pancréatique (PDAC) (75-88%). Nous avons donc voulu étudier l'expression du NTR1 dans une tumorothèque locale de PDAC. Nous avons ensuite démontré le potentiel du 68Ga-DOTA-NT20.3 pour l’imagerie TEP dans deux modèles murins de PDAC humains. Nous avons caractérisé sa biodistribution, évalué sa spécificité in vivo et l’avons comparé au 18F-FDG, notamment pour valider sa capacité à discriminer in vivo la pancréatite de l’adénocarcinome pancréatique

PET Imaging of G Protein-Coupled Membrane Receptors with 68Ga Radiolabelled Peptide

Ces dernières années, le ciblage des RCPG avec des ligands radiomarqués est devenu très important en imagerie nucléaire, notamment avec le remplacement progressif d’analogues peptidiques de la somatostatine marqués à l’111In pour la TEMP par d’autres marqués au 68Ga pour l'imagerie TEP qui présente une meilleure efficacité diagnostique. Les récepteurs de haute affinité de la bombésine (GRPR) ou de la neurotensine (NTR1) sont eux aussi des RCPG surexprimés par les cellules tumorales par rapport au tissu sain. Le GRPR est surexprimé dans 83% des carcinomes mammaires canalaires estrogènes dépendants. Dans la première partie de ce travail, nous avons démontré qu’un agoniste du GRPR, l’AMBA marqué au 68Ga, permettait la détection en TEP d’un modèle murin de cancer du sein humain estrogène-dépendant et qu’il permettait de prédire la réponse tumorale à une hormonothérapie de manière plus sensible que le 18F-FDG.L’équipe du Dr. Gruaz-Guyon a développé de nouveaux radioligands analogues de la neurotensine pour le ciblage des tumeurs exprimant le NTR1 et a étudié les propriétés de ces peptides marqués à l'111In dans un modèle de tumeurs d’adénocarcinome colique surexprimant le NTR1. L’obtention d’images TEMP de contraste élevé, permettant une détection des greffes tumorales dans des temps courts après injection, a conduit cette équipe à envisager ce traceur peptidique pour l’imagerie TEP. Dans la seconde partie de ce travail, nous avons réalisé le radiomarquage au 68Ga du meilleur de ces dérivés (DOTA NT20.3) et évalué son potentiel pour l'imagerie TEP et la détection de tumeurs d’adénocarcinome colique. La surexpression de NTR1 a été démontrée dans plusieurs autres cancers comme l’adénocarcinome pancréatique (PDAC) (75-88%). Nous avons donc voulu étudier l'expression du NTR1 dans une tumorothèque locale de PDAC. Nous avons ensuite démontré le potentiel du 68Ga-DOTA-NT20.3 pour l’imagerie TEP dans deux modèles murins de PDAC humains. Nous avons caractérisé sa biodistribution, évalué sa spécificité in vivo et l’avons comparé au 18F-FDG, notamment pour valider sa capacité à discriminer in vivo la pancréatite de l’adénocarcinome pancréatique.In recent years, the targeting of G protein-coupled membrane receptors (GPCRs) with radiolabeled ligands has become very important in nuclear imaging, particularly with the progressive replacement of somatostatin analogues labelled with 111In for SPECT by others labelled with 68Ga for PET imaging, which improves diagnostic efficacy. High-affinity bombesin receptors (GRPR) or neurotensin receptors (NTR1) are also GPCRs overexpressed in many cancers as compared with normal tissue. GRPR is overexpressed in 83% of estrogen-dependent ductal carcinomas. In the first part of this work, we demonstrated that 68Ga-AMBA, an agonist ligand of GRPR, allowed the PET detection of a mouse model of estrogen-dependent breast cancer and could be more sensitive than 18F-FDG to predict and monitor tumour response to hormone therapy.Dr. Gruaz-Guyon's team has developed new neurotensin radioanalogues for targeting NTR1-positive tumours. They studied the properties of these 111In-labeled peptides in a model of colon adenocarcinoma overexpressing NTR1. Obtaining high-contrast images allowing the detection of cancer within a short time after injection, this team subsequently developed this peptide radiotracer for PET imaging. In the second part of this work, we carried out the 68Ga radiolabeling of the best-performing of these derivatives and evaluated its potential for PET imaging of colon adenocarcinoma in a tumor model. Overexpression of NTR1 has been demonstrated in several human cancers such as PDAC (75-88%). We characterized the expression of NTR1 using specimens of human pancreatic cancer and then demonstrated the potential of this PET radiotracer to image two mouse models of human PDAC. We characterized its biodistribution, assessed its specificity in vivo in comparison with 18F-FDG, in particular its ability to discriminate in vivo pancreatitis from pancreatic adenocarcinoma

ACS Med Chem Lett

Bivalent ligands, i.e., molecules having two ligands covalently connected by a linker, have been gathering attention since the first description of their pharmacological potential in the early 80s. However, their synthesis, particularly of labeled heterobivalent ligands, can still be cumbersome and time-consuming. We herein report a straightforward procedure for the modular synthesis of labeled heterobivalent ligands (HBLs) using dual reactive 3,6-dichloro-1,2,4,5-tetrazine as a starting material and suitable partners for sequential SAr and inverse electron-demand Diels-Alder (IEDDA) reactions. This assembly method conducted in a stepwise or in a sequential one-pot manner provides quick access to multiple HBLs. A conjugate combining ligands toward the prostate-specific membrane antigen (PSMA) and the gastrin-releasing peptide receptor (GRPR) was radiolabeled, and its biological activity was assessed and (receptor binding affinity, biodistribution, imaging) as an illustration that the assembly methodology preserves the tumor targeting properties of the ligands.France Life Imagin

Liposomes for PET and MR imaging and for dual targeting (magnetic field/glucose moiety): synthesis, properties and in vivo studies

International audienceWe describe the potentiality of a new liposomal formulation enabling PET and MR imaging for cancer diagnosis. The bimodality is achieved by coupling a 68Ga-based radiotracer on the bilayer of ultra magnetic liposomes. In order to enhance the targeting properties obtained under a permanent magnetic field, a sugar moiety was added in the lipid formulation. Two new phospholipids were synthesized, one with a specific chelator of 68Ga (DSPE-PEG-NODAGA) and one with a glucose moiety (DSPE-PEG-Glucose). The liposomes were produced according to a fast and safe process, with a high radiolabeling yield. MR and PET imaging were performed on mice bearing human glioblastoma tumors (U87MG) after iv injection. The accumulation of the liposomes in solid tumor is evidenced by MR imaging and the amount is evaluated in vivo and ex vivo according to PET imaging. An efficient magnetic targeting is achieved with these new magnetic liposomes

Hepatocellular Carcinomas With Mutational Activation of Beta-Catenin Require Choline and Can Be Detected by Positron Emission Tomography

International audienc