In Vivo Detection of Succinate by Magnetic Resonance Spectroscopy as a Hallmark of SDHx Mutations in Paraganglioma

International audiencePurpose: Germline mutations in genes encoding mitochon-drial succinate dehydrogenase (SDH) are found in patients with paragangliomas, pheochromocytomas, gastrointestinal stromal tumors, and renal cancers. SDH inactivation leads to a massive accumulation of succinate, acting as an oncometabolite and which levels, assessed on surgically resected tissue are a highly specific biomarker of SDHx-mutated tumors. The aim of this study was to address the feasibility of detecting succinate in vivo by magnetic resonance spectroscopy. Experimental Design: A pulsed proton magnetic resonance spectroscopy (1 H-MRS) sequence was developed, optimized, and applied to image nude mice grafted with Sdhb À/À or wild-type chromaffin cells. The method was then applied to patients with paraganglioma carrying (n ¼ 5) or not (n ¼ 4) an SDHx gene mutation. Following surgery, succinate was measured using gas chromatography/mass spectrometry, and SDH protein expression was assessed by immunohistochemistry in resected tumors. Results: A succinate peak was observed at 2.44 ppm by 1 H-MRS in all Sdhb À/À-derived tumors in mice and in all paragangliomas of patients carrying an SDHx gene mutation, but neither in wild-type mouse tumors nor in patients exempt of SDHx mutation. In one patient, 1 H-MRS results led to the identification of an unsus-pected SDHA gene mutation. In another case, it helped define the pathogenicity of a variant of unknown significance in the SDHB gene. Conclusions: Detection of succinate by 1 H-MRS is a highly specific and sensitive hallmark of SDHx mutations. This non-invasive approach is a simple and robust method allowing in vivo detection of the major biomarker of SDHx-mutated tumors. Clin Cancer Res; 22(5); 1120–9. Ó2015 AACR

Nose-only inhalations of high-dose alumina nanoparticles/hydrogen chloride gas mixtures induce strong pulmonary pro-inflammatory response: a pilot study

Objective Solid composite propellants combustion, in aerospace and defense fields, can lead to complex aerosols emission containing high concentrations of alumina nanoparticles (Al2O3 NPs) and hydrogen chloride gas (HClg). Exposure to these mixtures by inhalation is thus possible but literature data toward their pulmonary toxicity are missing. To specify hazards resulting from these combustion aerosols, a pilot study was implemented. Materials and methods Male Wistar rats were nose-only exposed to Al2O3 NPs (primary size 13 nm, 10 g/L suspension leading to 20.0–22.1 mg/m3 aerosol) and/or to HClg aerosols (5 ppm target concentration) following two exposure scenarios (single exposures (SE) or repeated exposures (RE)). Bronchoalveolar lavage fluids (BALF) content and lungs histopathology were analyzed 24 h after exposures. Results Repeated co-exposures increased total proteins and LDH concentrations in BALF indicating alveolar–capillary barrier permeabilization and cytolysis. Early pulmonary inflammation was induced after RE to Al2O3 NPs ± HClg resulting in PMN, TNF-α, IL-1β, and GRO/KC increases in BALF. Both exposure scenarios resulted in pulmonary histopathological lesions (vascular congestions, bronchial pre-exfoliations, vascular and interalveolar septum edemas). Lung oxidative damages were observed in situ following SE. Conclusion Observed biological effects are dependent on both aerosol content and exposure scenario. Results showed an important pro-inflammatory effect of Al2O3 NPs/HClg mixtures on the lungs of rat 24 h after exposure. This pilot study raises concerns toward potential long-term pulmonary toxicity of combustion aerosols and highlights the importance for further studies to be led in order to define dose limitations and exposure thresholds for risk management at the work place

Integrative genomic analysis reveals somatic mutations in pheochromocytoma and

Pheochromocytomas and paragangliomas are neuroendocrine tumors that occur in the context of inherited cancer syndromes in ∼30% of cases and are linked to germline mutations in the VHL, RET, NF1, SDHA, SDHB, SDHC, SDHD, SDHAF2 and TMEM127 genes. Although genome-wide expression studies have revealed some of the mechanisms likely to be involved in pheochromocytoma/paraganglioma tumorigenesis, the complete molecular distinction of all subtypes of hereditary tumors has not been solved and the genetic events involved in the generation of sporadic tumors are unknown. With these purposes in mind, we investigated 202 pheochromocytomas/paragangliomas, including 75 hereditary tumors, using expression profiling, BAC array comparative genomic hybridization and somatic mutation screening. Gene expression signatures defined the hereditary tumors according to their genotype and notably, led to a complete subseparation between SDHx-and VHL-related tumors. In tumor tissues, the systematic characterization of somatic genetic events associated with germline mutations in tumor suppressor genes revealed loss of heterozygosity (LOH) in a majority of cases, but also detected point mutations and copy-neutral LOH. Finally, guided by transcriptome classifications and LOH profiles, somatic mutations in VHL or RET genes were identified in 14% of sporadic pheochromocytomas/paragangliomas. Overall, we found a germline or somatic genetic alteration in 45.5% (92/202) of the tumors in this large series of pheochromocytomas/paragangliomas. Regarding mutated genes, specific molecular pathways involved in tumorigenesis mechanisms are identified. Altogether, these new findings suggest that somatic mutation analysis is likely to yield important clues for personalizing molecular targeted therapies

The Warburg Effect Is Genetically Determined in Inherited Pheochromocytomas

The Warburg effect describes how cancer cells down-regulate their aerobic respiration and preferentially use glycolysis to generate energy. To evaluate the link between hypoxia and Warburg effect, we studied mitochondrial electron transport, angiogenesis and glycolysis in pheochromocytomas induced by germ-line mutations in VHL, RET, NF1 and SDH genes. SDH and VHL gene mutations have been shown to lead to the activation of hypoxic response, even in normoxic conditions, a process now referred to as pseudohypoxia. We observed a decrease in electron transport protein expression and activity, associated with increased angiogenesis in SDH- and VHL-related, pseudohypoxic tumors, while stimulation of glycolysis was solely observed in VHL tumors. Moreover, microarray analyses revealed that expression of genes involved in these metabolic pathways is an efficient tool for classification of pheochromocytomas in accordance with the predisposition gene mutated. Our data suggest an unexpected association between pseudohypoxia and loss of p53, which leads to a distinct Warburg effect in VHL-related pheochromocytomas

Interactions moléculaires entre l'adénovirus entérique de sérotype 41 et la cellule hôte

L'adénovirus de sérotype 41 (Ad41) présente plusieurs particularités qui le différencient des autres adénovirus humains, telles que son tropisme ciblé pour le tractus digestif et la présence de deux protéines "fibres" de différentes longueurs, une courte et une longue. Les autres adénovirus humains présentent un seul type de fibre et un tropisme cellulaire moins restreint. Un certain nombre d'observations suggèrent que la fibre courte est impliquée dans le tropisme de l'Ad41. Nous avons utilisé le domaine "tête" de la fibre courte de l'Ad41 comme "appât" pour rechercher les partenaires cellulaires de l'Ad41, en détectant les interaction protéine-protéine survenant in vivo, dans la levure (système du double-hybride). Notre travail a permis de développer des outils propres à l'étude de l'Ad41, d'établir les conditions de production de l'Ad41 et de mettre en évidence le comportement atypique des pentons de l'Ad41 en électrophorèse des protéines et de déterminer la longueur et la stoechiométrie des fibres ontenues dans le virion. Nous avons identifié plusieurs partenaires cellulaires intéragissant avec la fibre courte de l'Ad41. Certaines de ces protéines interagissent communément avec les fibres des différents sérotypes(Ad2,Ad3 et Ad41) alors que d'autres semblent spécifiques de l'Ad41. Enfin, nous avons montré que, dans un environnemnt acide proche de celui du tractus digestif humain, l'Ad41 est plus stable que l'Ad2. Ces résultats indiquent que plusieurs facteurs distinguent l'Ad41 des autres adénovirus humains et peuvent influencer le tropisme de l'Ad41 pour le tractus digestif.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF

Macrophage Identification In Situ

Understanding the processes of inflammation and tissue regeneration after injury is of great importance. For a long time, macrophages have been known to play a central role during different stages of inflammation and tissue regeneration. However, the molecular and cellular mechanisms by which they exert their effects are as yet mostly unknown. While in vitro macrophages have been characterized, recent progress in macrophage biology studies revealed that macrophages in vivo exhibited distinctive features. Actually, the precise characterization of the macrophages in vivo is essential to develop new healing treatments and can be approached via in situ analyses. Nowadays, the characterization of macrophages in situ has improved significantly using antigen surface markers and cytokine secretion identification resulting in specific patterns. This review aims for a comprehensive overview of different tools used for in situ macrophage identification, reporter genes, immunolabeling and in situ hybridization, discussing their advantages and limitations

Non-Specific Binding, a Limitation of the Immunofluorescence Method to Study Macrophages In Situ

Advances in understanding tissue regenerative mechanisms require the characterization of in vivo macrophages as those play a fundamental role in this process. This characterization can be approached using the immuno-fluorescence method with widely studied and used pan-markers such as CD206 protein. This work investigated CD206 expression in an irradiated-muscle pig model using three different antibodies. Surprisingly, the expression pattern during immunodetection differed depending on the antibody origin and could give some false results. False results are rarely described in the literature, but this information is essential for scientists who need to characterize macrophages. In this context, we showed that in situ hybridization coupled with hybridization-chain-reaction detection (HCR) is an excellent alternative method to detect macrophages in situ

Hybridization‐chain‐reaction is a relevant method for in situ detection of M2d‐like macrophages in a mini‐pig model

International audienceMacrophages are a heterogeneous population of cells with an important role in innate immunity and tissue regeneration. Based on in vitro experiments, macrophages have been subdivided into five distinct subtypes named M1, M2a, M2b, M2c, and M2d, depending on the means of their activation and the cell surface markers they display. Whether all subtypes can be detected in vivo is still unclear. The identification of macrophages in vivo in the regenerating muscle could be used as a new diagnostic tool to monitor therapeutic strategies for tissue repair. The use of classical immunolabeling techniques is unable to discriminate between different M2 macrophages and a functional characterization of these macrophages is lacking. Using in situ hybridization coupled with hybridization-chain-reaction detection (HCR), we achieved the identification of M2d-like macrophages within regenerating muscle and applied this technique to understand the role of M2 macrophages in the regeneration of irradiated pig-muscle after adipose tissue stem cell treatment. Our work highlights the limits of immunolabeling and the usefulness of HCR analysis to provide valuable information for macrophage characterization

Phenotypic and genetic diversity of the traditional Lister smallpox vaccine.

International audienceAs an initial step in the development of a second-generation smallpox vaccine derived from the Lister strain, to be prepared for a variola virus threat, diversity of the traditional vaccine was examined by characterizing a series of ten viral clones. In vitro and in vivo phenotypic studies showed that the biological behavior of the clones diverged from each other and in most cases diverged from the vaccinia virus (VACV) Lister parental population. Taken together, these results demonstrate the heterogeneity of the viral population within the smallpox vaccine and highlight the difficulty in choosing one clone which would meet the current requirements for a safe and effective vaccine candidate