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

Selective neutralization of the serpin protease nexin-1 by a specific monoclonal antibody

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A Vegetation Index qualifying pasture edges is related to Ixodes ricinus density and to Babesia divergens seroprevalence in dairy cattle herds

International audienceBabesia divergens, transmitted by the tick Ixodes ricinus, is the main agent of bovine piroplasmosis in France. This Apicomplexa often is present in asymptomatic carriers; however, clinical cases are rare. While numerous factors are known to influence tick density, no risk factor of contact with B. divergens has been identified for cattle. Our study aimed to explore whether aVegetationIndex could serve as an indirect indicator of within-herd B. divergens seroprevalence. In February 2007, blood samples were taken from all of the cows in 19 dairy cattle herds in Western France and IFAT serology was performed individually to measure B. divergens seroprevalence. The following spring, I. ricinus nymphs were collected by drag sampling along transects on the vegetation of each farm's pasture perimeters. Tick density was related significantly to aVegetationIndex (V.I., ranging from 1 to 5) that took into account the abundance of trees and bushes on the edge of pastures: most ticks (57%) were found in transects with the highest V.I. (covering 15% of the explored surface in the study area). At the farm level, the proportion of transects presenting I. ricinus nymphs was significantly related to B. divergens seroprevalence: the farms with more than 15% of transects with I. ricinus had a significantly higher risk of high seroprevalence. The proportion of pasture perimeters where the V.I. = 5 also was significantly related to B. divergens seroprevalence: the farms where more than 20% of transects had a V.I. = 5 had a significantly higher risk of high seroprevalence. Given that the VegetationIndex is a steady indicator of the potential I. ricinus density in the biotope, we recommend that the risk of high B. divergens seroprevalence in cows be evaluated using this tool rather than drag sampling

A vegetation index qualifying pasture edges is related to tick density and reflects the risk of high Babesia divergens seroprevalence in dairy cattle herds

National audienc

A vegetation index qualifying pasture edges is related to tick density and reflects the risk of high Babesia divergens seroprevalence in dairy cattle herds

National audienc

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xiii, 404 p., : ill.,; 23 c

Development and characterization of single‐domain antibodies neutralizing protease nexin‐1 as tools to increase thrombin generation: Single-domain antibodies against protease nexin-1

International audienceBackground: Protease nexin-1 (PN-1) is a member of the serine protease inhibitor (Serpin)-family, with thrombin as its main target. Current polyclonal and monoclonal antibodies against PN-1 frequently cross-react with Plasminogen activator inhibitor-1 (PAI-1), a structurally and functionally homologous Serpin. Objectives: Here, we aimed to develop inhibitory single-domain antibodies (VHHs) that show specific binding to both human (hPN-1) and murine (mPN-1) PN-1. Methods: PN-1-binding VHHs were isolated via phage-display using llama-derived or synthetic VHH-libraries. Following bacterial expression, purified VHHs were analyzed in binding and activity assays.Results and Conclusions: By using a llama-derived library, 2 PN-1 specific VHHs were obtained (KB-PN1-01 & KB-PN1-02). Despite their specificity, none displayed inhibitory activity towards hPN-1 or mPN-1. From the synthetic library, 4 VHHs (H12, B11, F06, A08) could be isolated that combined efficient binding to both hPN-1 and mPN-1 with negligible binding to PAI-1. Of these, B11, F06 and A08 were able to fully restore thrombin activity by blocking PN-1. As monovalent VHH, IC50-values for hPN-1 were 50±10 nM, 290±30 and 960±390 nM, for B11, F06 and A08, respectively, and 1580±240 nM, 560±130 nM and 2880±770 nM for mPN-1. The inhibitory potential was improved 4- to 7-fold when bivalent VHHs were engineered. Importantly, all VHHs could block PN-1 activity in plasma as well as PN-1 released from activated platelets, one of the main sources of PN-1 during hemostasis.In conclusion, we report the generation of inhibitory anti-PN-1 antibodies using a specific approach to avoid cross-reactivity with the homologous Serpin PAI-1

Targeting protease nexin-1, a natural anticoagulant serpin, to control bleeding and improve hemostasis in hemophilia

International audienceHemophilia A and B, diseases caused by the lack of factor VIII (FVIII) and factor IX (FIX) respectively, lead to insufficient thrombin production, and therefore to bleeding. New therapeutic strategies for hemophilia treatment that do not rely on clotting factor replacement, but imply the neutralization of natural anticoagulant proteins, have recently emerged. We propose an innovative approach consisting of targeting a natural and potent thrombin inhibitor, expressed by platelets, called protease nexin-1 (PN-1). By using the calibrated automated thrombin generation assay, we showed that a PN-1-neutralizing antibody could significantly shorten the thrombin burst in response to tissue factor in platelet-rich plasma (PRP) from patients with mild or moderate hemophilia. In contrast, in PRP from patients with severe hemophilia, PN-1 neutralization did not improve thrombin generation. However, after collagen-induced platelet activation, PN-1 deficiency in F8-/-mice or PN-1 blocking in patients with severe disease led to a significantly improved thrombin production in PRP, underlining the regulatory role of PN-1 released from platelet granules. In various bleeding models, F8-/-/PN-1-/- mice displayed significantly reduced blood loss and bleeding time compared with F8-/-mice. Moreover, platelet recruitment and fibrin(ogen) accumulation were significantly higher in F8-/-/PN-1-/- mice than in F8-/-mice in the ferric chloride-induced mesenteric vessel injury model. Thromboelastometry studies showed enhanced clot stability and lengthened clot lysis time in blood from F8-/-/PN-1-/- and from patients with hemophilia A incubated with a PN-1-neutralizing antibody compared with their respective controls. Our study thus provides proof of concept that PN-1 neutralization can be a novel approach for future clinical care in hemophilia

Clearance of plasmin-PN-1 complexes by vascular smooth muscle cells in human aneurysm of the ascending aorta

Plasminogen is a circulating zymogen which enters the arterial wall by radial, transmural hydraulic conductance, where it is converted to plasmin by tissue plasminogen activator t-PA on an activation platform involving S100A4 on the vascular smooth muscle cell (vSMC) membrane. Plasmin is involved in the progression of human thoracic aneurysm of the ascending aorta (TAA), vSMCs protect the TM wall from plasmin-induced proteolytic injury by expressing high levels of antiproteases. Protease nexin-1 (PN-1) is a tissue antiprotease belonging to the serpin superfamily, expressed in the vascular wall, and is able to form a covalent complex with plasmin. LDL receptor related protein-1 (LRP-1) is a scavenger receptor implicated in protease-antiprotease complex internalization. In this study, we investigated whether PN-1 and LRP-1 are involved in the inhibition and clearance of plasminogen by the SMCs of human TAA. We demonstrated an overexpression of S100A4, PN-1, and LRP-1 in the medial layer of human TM. Plasminogen activation taking place in the media of TAA was revealed by immunohistochemical staining and plasmin activity analyses. We showed by cell biology studies that plasmin-PN-1 complexes are internalized via LRP-1 in vSMCs from healthy and TAA media. Thus, two complementary mechanisms are involved in the protective role of PN-1 in human TM: one involving plasmin inhibition and the other involving tissue clearance of plasmin-PN1 complexes via the scavenger receptor LRP-1. (C) 2017 Elsevier Inc. All rights reserved.INSERM, Paris Diderot UniversityFrench National Research AgencyINSERM, Lab Vasc Translat Sci, UMR 1148, Paris, FranceParis7 Denis Diderot Univ, Paris, FranceUniv Sao Paulo, Fac Med, Hosp Clin, Heart Inst InCor, Sao Paulo, BrazilUniv Fed Sao Paulo, Dept Biol Sci, Sao Paulo, BrazilHop Xavier Bichat, Ctr Natl Reference Syndrome Marfan & Apparentes, Paris, FranceKatholieke Univ Leuven, Dept Pharmaceut & Pharmacol Sci, Lab Therapeut & Diagnost Antibodies, Leuven, BelgiumUniv Fed Sao Paulo, Dept Biol Sci, Sao Paulo, BrazilFrench National Research Agency: ANR-14-CE 15-0012-03French National Research Agency: ANR-BSV1-0009-01Web of Scienc

Mutation spectrum in the ABCC6 gene and genotype–phenotype correlations in a French cohort with pseudoxanthoma elasticum

International audiencePurpose: Pseudoxanthoma elasticum (PXE) is an autosomal recessive disorder caused by variants in the ABCC6 gene. Ectopic mineralization of connective tissues leads to skin, eye, and cardiovascular manifestations with considerable phenotypic variability of unknown cause. We aimed to identify genotype-phenotype correlations in PXE. Methods: A molecular analysis was performed on 458 French PXE probands clinically evaluated using the Phenodex score (PS). Variant topographic analysis and genotype-phenotype correlation analysis were performed according to the number and type of identified variants. Results: Complete molecular analysis of 306 cases allowed the identification of 538 mutational events (88% detection rate) with 142 distinct variants, of which 66 were novel. Missense variant distribution was specific to some regions and residues of ABCC6. For the 220 cases with a complete PS, there was a higher prevalence of eye features in Caucasian patients (P = 0.03) and more severe eye and vascular phenotype in patients with loss-of-function variants (P = 0.02 and 0.05, respectively). Nephrolithiases and strokes, absent from the PS, were prevalent features of the disorder (11 and 10%, respectively). Conclusion: We propose an updated PS including renal and neurological features and adaptation of follow-up according to the genetic and ethnic status of PXE-affected patients