Longitudinal [F-18]GE-180 PET Imaging Facilitates In Vivo Monitoring of TSPO Expression in the GL261 Glioblastoma Mouse Model

The 18 kDa translocator protein (TSPO) is increasingly recognized as an interesting target for the imaging of glioblastoma (GBM). Here, we investigated TSPO PET imaging and autoradiography in the frequently used GL261 glioblastoma mouse model and aimed to generate insights into the temporal evolution of TSPO radioligand uptake in glioblastoma in a preclinical setting. We performed a longitudinal [F-18]GE-180 PET imaging study from day 4 to 14 post inoculation in the orthotopic syngeneic GL261 GBM mouse model (n = 21 GBM mice, n = 3 sham mice). Contrast-enhanced computed tomography (CT) was performed at the day of the final PET scan (+/- 1 day). [F-18] GE-180 autoradiography was performed on day 7, 11 and 14 (ex vivo: n = 13 GBM mice, n = 1 sham mouse;in vitro: n = 21 GBM mice;n = 2 sham mice). Brain sections were also used for hematoxylin and eosin (H&E) staining and TSPO immunohistochemistry. [F-18]GE-180 uptake in PET was elevated at the site of inoculation in GBM mice as compared to sham mice at day 11 and later (at day 14, TBRmax +27% compared to sham mice, p = 0.001). In GBM mice, [F-18]GE-180 uptake continuously increased over time, e.g., at day 11, mean TBRmax +16% compared to day 4, p = 0.011. [(18) F]GE-180 uptake as depicted by PET was in all mice co-localized with contrast-enhancement in CT and tissue-based findings. [F-18]GE-180 ex vivo and in vitro autoradiography showed highly congruent tracer distribution (r = 0.99, n = 13, p < 0.001). In conclusion, [F-18]GE-180 PET imaging facilitates non-invasive in vivo monitoring of TSPO expression in the GL261 GBM mouse model. [F-18]GE-180 in vitro autoradiography is a convenient surrogate for ex vivo autoradiography, allowing for straightforward identification of suitable models and scan time-points on previously generated tissue sections

The Traumatic Inoculation Process Affects TSPO Radioligand Uptake in Experimental Orthotopic Glioblastoma

Background: The translocator protein (TSPO) has been proven to have great potential as a target for the positron emission tomography (PET) imaging of glioblastoma. However, there is an ongoing debate about the potential various sources of the TSPO PET signal. This work investigates the impact of the inoculation-driven immune response on the PET signal in experimental orthotopic glioblastoma. Methods: Serial [F-18]GE-180 and O-(2-[F-18]fluoroethyl)-L-tyrosine ([F-18]FET) PET scans were performed at day 7/8 and day 14/15 after the inoculation of GL261 mouse glioblastoma cells (n = 24) or saline (sham, n = 6) into the right striatum of immunocompetent C57BL/6 mice. An additional n = 25 sham mice underwent [F-18]GE-180 PET and/or autoradiography (ARG) at days 7, 14, 21, 28, 35, 50 and 90 in order to monitor potential reactive processes that were solely related to the inoculation procedure. In vivo imaging results were directly compared to tissue-based analyses including ARG and immunohistochemistry. Results: We found that the inoculation process represents an immunogenic event, which significantly contributes to TSPO radioligand uptake. [F-18]GE-180 uptake in GL261-bearing mice surpassed [F-18]FET uptake both in the extent and the intensity, e.g., mean target-to-background ratio (TBRmean) in PET at day 7/8: 1.22 for [F-18]GE-180 vs. 1.04 for [F-18]FET, p < 0.001. Sham mice showed increased [F-18]GE-180 uptake at the inoculation channel, which, however, continuously decreased over time (e.g., TBRmean in PET: 1.20 at day 7 vs. 1.09 at day 35, p = 0.04). At the inoculation channel, the percentage of TSPO/IBA1 co-staining decreased, whereas TSPO/GFAP (glial fibrillary acidic protein) co-staining increased over time (p < 0.001). Conclusion: We identify the inoculation-driven immune response to be a relevant contributor to the PET signal and add a new aspect to consider for planning PET imaging studies in orthotopic glioblastoma models

Immunity at Cauliflower Hydathodes Controls Systemic Infection by Xanthomonas campestris pv campestris

International audienceHydathodes are water pores found on leaves of a wide range of vascular plants and are the sites of guttation. We report here on the detailed anatomy of cauliflower (Brassica oleracea) and Arabidopsis (Arabidopsis thaliana) hydathodes. Hydathode surface presents pores resembling stomata giving access to large cavities. Beneath, the epithem is composed of a lacunar and highly vascularized parenchyma offering a direct connection between leaf surface and xylem vessels. Arabidopsis hydathode pores were responsive to ABA and light similar to stomata. The flg22 flagellin peptide, a well-characterized elicitor of plant basal immunity, did not induce closure of hydathode pores in contrast to stomata. Because hydathodes are natural infection routes for several pathogens, we investigated hydathode infection by the adapted vascular phytopathogenic bacterium Xanthomonas campestris pv campestris (Xcc), the causal agent of black rot disease of Brassicaceae. Microscopic observations of hydathodes six days postinoculation indicated a digestion of the epithem cells and a high bacterial multiplication. Postinvasive immunity was shown to limit pathogen growth in the epithem and is actively suppressed by the type III secretion system and its effector proteins. Altogether, these results give a detailed anatomic description of Brassicaceae hydathodes and highlight the efficient use of this tissue as an initial niche for subsequent vascular systemic dissemination of Xcc in distant plant tissues

A novel locust (Schistocerca gregaria) serine protease inhibitor with a high affinity for neutrophil elastase

We have purified to homogeneity two forms of a new serine protease inhibitor specific for elastase/chymotrypsin from the ovary gland of the desert locust Schistocerca gregaria. This protein, greglin, has 83 amino acid residues and bears putative phosphorylation sites. Amino acid sequence alignments revealed no homology with pacifastin insect inhibitors and only a distant relationship with Kazal-type inhibitors. This was confirmed by computer-based structural studies. The most closely related homologue is a putative gene product from Ciona intestinalis with which it shares 38% sequence homology. Greglin is a fast-acting and tight binding inhibitor of human neutrophil elastase (k(ass)=1.2×10(7) M(−1)·s(−1), K(i)=3.6 nM) and subtilisin. It also binds neutrophil cathepsin G, pancreatic elastase and chymotrypsin with a lower affinity (26 nM≤K(i)≤153 nM), but does not inhibit neutrophil protease 3 or pancreatic trypsin. The capacity of greglin to inhibit neutrophil elastase was not significantly affected by exposure to acetonitrile, high temperature (90 °C), low or high pH (2.5–11.0), N-chlorosuccinimide-mediated oxidation or the proteolytic enzymes trypsin, papain and pseudolysin from Pseudomonas aeruginosa. Greglin efficiently inhibits the neutrophil elastase activity of sputum supernatants from cystic fibrosis patients. Its biological function in the locust ovary gland is currently unknown, but its physicochemical properties suggest that it can be used as a template to design a new generation of highly resistant elastase inhibitors for treating inflammatory diseases

Un bilan des activités 2017 de la plateforme de micro et nanotechnologies du LAAS-CNRS

National audienceLa plateforme de micro et nanotechnologies du LAAS fait partie du réseau Renatech.Elle offre aux domaines sensibles aux contaminations environnementales une concentration particulaire maîtrisée, une régulation de la température, de l'humidité, et de la lumière pour certaines opérations sensibles aux rayonnements ultraviolets au sein de la salle de 1600 m² en classes 100 et 10 000. Les équipements permettent l’élaboration, la mise en forme, le traitement de matériaux pour le prototypage de composants microélectroniques, optoélectroniques, micro et nano systèmes.La gestion et le développement de l’infrastructure, des équipements et procédés ; le soutien aux projets de recherche sont assurés par le service TEAM. Ces moyens humains et technologiques assurent le soutien des actions de recherche internes au LAAS, mais aussi l'accueil de demandes externes dans le cadre du réseau Renatech.Annuellement l’activité du service est examinée par une commission (ComTEAM), présidée par le Directeur du laboratoire.Ce document réalisé annuellement fait le bilan des activités 2017 et se projette sur des actions à conduire en 2018 dans les différentes zones gérées par le service TEAM.

Bilan des activités de la plateforme de micro et nano technologies du LAAS-CNRS

National audienceLa plateforme de micro et nanotechnologies du LAAS fait partie du réseau RENATECH. Elle offre aux domaines sensibles aux contaminations environnementales une concentration particulaire maîtrisée, une régulation de la température, de l'humidité, et de la lumière pour certaines opérations sensibles aux rayonnements ultraviolets au sein de la salle de 1600 m² en classes 100 et 10 000. Les équipements permettent l’élaboration, la mise en forme, le traitement de matériaux pour le prototypage de composants microélectroniques, optoélectroniques, micro et nano systèmes.La gestion et le développement de l’infrastructure, des équipements et procédés ; le soutien aux projets de recherche sont assurés par le service TEAM. Ces moyens humains et technologiques assurent le soutien des actions de recherche internes au LAAS, mais aussi l'accueil de demandes externes dans le cadre du réseau Renatech.Annuellement l’activité du service est examinée par une commission (ComTEAM), présidée par le Directeur du laboratoire.Ce document réalisé annuellement fait le bilan des activités 2016 et se projette sur des actions à conduire en 2017 dans les différentes zones gérées par le service TEAM