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Toulouse, France

Chevalier G.,French Institute of Health and Medical Research | Chevalier G.,French National Center for Scientific Research | Chevalier G.,Toulouse 1 University Capitole | Suberbielle E.,French Institute of Health and Medical Research | And 21 more authors.
PLoS Pathogens | Year: 2011

Following infection of the central nervous system (CNS), the immune system is faced with the challenge of eliminating the pathogen without causing significant damage to neurons, which have limited capacities of renewal. In particular, it was thought that neurons were protected from direct attack by cytotoxic T lymphocytes (CTL) because they do not express major histocompatibility class I (MHC I) molecules, at least at steady state. To date, most of our current knowledge on the specifics of neuron-CTL interaction is based on studies artificially inducing MHC I expression on neurons, loading them with exogenous peptide and applying CTL clones or lines often differentiated in culture. Thus, much remains to be uncovered regarding the modalities of the interaction between infected neurons and antiviral CD8 T cells in the course of a natural disease. Here, we used the model of neuroinflammation caused by neurotropic Borna disease virus (BDV), in which virus-specific CTL have been demonstrated as the main immune effectors triggering disease. We tested the pathogenic properties of brain-isolated CD8 T cells against pure neuronal cultures infected with BDV. We observed that BDV infection of cortical neurons triggered a significant up regulation of MHC I molecules, rendering them susceptible to recognition by antiviral CTL, freshly isolated from the brains of acutely infected rats. Using real-time imaging, we analyzed the spatio-temporal relationships between neurons and CTL. Brain-isolated CTL exhibited a reduced mobility and established stable contacts with BDV-infected neurons, in an antigen- and MHC-dependent manner. This interaction induced rapid morphological changes of the neurons, without immediate killing or impairment of electrical activity. Early signs of neuronal apoptosis were detected only hours after this initial contact. Thus, our results show that infected neurons can be recognized efficiently by brain-isolated antiviral CD8 T cells and uncover the unusual modalities of CTL-induced neuronal damage. © 2011 Chevalier et al. Source


Thomas G.,Institute Of Recherche En Cance Rologie Of Montpellier | Thomas G.,French Institute of Health and Medical Research | Thomas G.,Montpellier University | Thomas G.,Roche Holding AG | And 39 more authors.
Oncotarget | Year: 2014

The anti-HER2 antibody pertuzumab inhibits HER2 dimerization and affects HER2/HER3 dimer formation and signaling. As HER3 and its ligand neuregulin are implicated in pancreatic tumorigenesis, we investigated whether HER3 expression could be a predictive biomarker of pertuzumab efficacy in HER2low-expressing pancreatic cancer. We correlated in vitro and in vivo HER3 expression and neuregulin dependency with the inhibitory effect of pertuzumab on cell viability and tumor progression. HER3 knockdown in BxPC-3 cells led to resistance to pertuzumab therapy. Pertuzumab treatment of HER3-expressing pancreatic cancer cells increased HER3 at the cell membrane, whereas the anti-HER3 monoclonal antibody 9F7-F11 down-regulated it. Both antibodies blocked HER3 and AKT phosphorylation and inhibited HER2/HER3 heterodimerization but affected differently HER2 and HER3 homodimers. The pertuzumab/9F7-F11 combination enhanced tumor inhibition and the median survival time in mice xenografted with HER3-expressing pancreatic cancer cells. Finally, HER2 and HER3 were co-expressed in 11% and HER3 alone in 27% of the 45 pancreatic ductal adenocarcinomas analyzed by immunohistochemistry. HER3 is essential for pertuzumab efficacy in HER2low-expressing pancreatic cancer and HER3 expression might be a predictive biomarker of pertuzumab efficacy in such cancers. Further studies in clinical samples are required to confirm these findings and the interest of combining anti-HER2 and anti-HER3 therapeutic antibodies. Source


Le Clorennec C.,Institute Of Recherche En Cancerologie Of Montpellier | Le Clorennec C.,French Institute of Health and Medical Research | Le Clorennec C.,Montpellier University | Le Clorennec C.,Institute Regional du Cancer Montpellier | And 27 more authors.
Oncotarget | Year: 2016

We characterized the mechanism of action of the neuregulin-non-competitive anti-HER3 therapeutic antibody 9F7-F11 that blocks the PI3K/AKT pathway, leading to cell cycle arrest and apoptosis in vitro and regression of pancreatic and breast cancer in vivo. We found that 9F7-F11 induces rapid HER3 down-regulation. Specifically, 9F7-F11-induced HER3 ubiquitination and degradation in pancreatic, breast and prostate cancer cell lines was driven mainly by the itchy E3 ubiquitin ligase (ITCH/AIP4). Overexpression of the ITCH/AIP4 inhibitor N4BP1 or small-interfering RNA-mediated knockdown of ITCH/AIP4 inhibited HER3 ubiquitination/degradation and PI3K/AKT signaling blockade induced by 9F7-F11. Moreover, 9F7-F11-mediated JNK1/2 phosphorylation led to ITCH/AIP4 activation and recruitment to HER3 for receptor ubiquitination and degradation. ITCH/AIP4 activity was activated by the deubiquitinases USP8 and USP9X, as demonstrated by RNA interference. Taken together, our results suggest that 9F7-F11-induced HER3 ubiquitination and degradation in cancer cells mainly occurs through JNK1/2-dependent ITCH/AIP4 activation. Source


Renaut L.,Millegen SA | Monnet C.,Millegen SA | Dubreuil O.,Millegen SA | Zaki O.,Millegen SA | And 4 more authors.
Methods in Molecular Biology | Year: 2012

As a growing number of therapeutic antibodies are developed, robust methods to efficiently improve the affinity and/or specificity of antibody candidates are needed. Here we describe our powerful platform that combines scFv affinity maturation and IgG high-throughput screening. After creating diversity with our random mutagenesis technology (MutaGen™), the scFv libraries are fully cleaned using a fusion system introducing the beta-lactamase gene to select in-frame and stop codon free variants on the basis of ampicillin resistance. The high-quality scFv libraries thereby constructed are then selected on the target in vitro using phage display technology. Contrary to standard procedures, instead of producing a limited number of affinity matured scFv as IgG molecules, we developed a cloning system to directly transfer the entire pool of selected scFv into an IgG expression vector permitting rapid IgG small-scale production (96 wells) in mammalian cells. Our integrated process allows us to generate high-quality scFv libraries and test numerous IgG variants, increasing the chances to select the best therapeutic antibody candidate. © 2012 Springer Science+Business Media, LLC. Source

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