APRIL is critical for plasmablast survival in the bone marrow and poorly expressed by early-life bone marrow stromal cells.

The persistence of serum IgG antibodies elicited in human infants is much shorter than when such responses are elicited later in life. The reasons for this rapid waning of antigen-specific antibodies elicited in infancy are yet unknown. We have recently shown that adoptively transferred tetanus toxoid (TT)-specific plasmablasts (PBs) efficiently reach the bone marrow (BM) of infant mice. However, TT-specific PBs fail to persist in the early-life BM, suggesting that they fail to receive the molecular signals that support their survival/differentiation. Using a proliferation-inducing ligand (APRIL)- and B-cell activating factor (BAFF) B-lymphocyte stimulator (BLyS)-deficient mice, we demonstrate here that APRIL is a critical factor for the establishment of the adult BM reservoir of anti-TT IgG-secreting cells. Through in vitro analyses of PB/plasma cell (PC) survival/differentiation, we show that APRIL induces the expression of Bcl-X(L) by a preferential binding to heparan sulfate proteoglycans at the surface of CD138(+) cells. Last, we identify BM-resident macrophages as the main cells that provide survival signals to PBs and show that this function is slowly acquired in early life, in parallel to a progressive acquisition of APRIL expression. Altogether, this identifies APRIL as a critical signal for PB survival that is poorly expressed in the early-life BM compartment.

Patterns of plant subcellular responses to successful oomycete infections reveal differences in host cell reprogramming and endocytic trafficking.

Adapted filamentous pathogens such as the oomycetes Hyaloperonospora arabidopsidis (Hpa) and Phytophthora infestans (Pi) project specialized hyphae, the haustoria, inside living host cells for the suppression of host defence and acquisition of nutrients. Accommodation of haustoria requires reorganization of the host cell and the biogenesis of a novel host cell membrane, the extrahaustorial membrane (EHM), which envelops the haustorium separating the host cell from the pathogen. Here, we applied live-cell imaging of fluorescent-tagged proteins labelling a variety of membrane compartments and investigated the subcellular changes associated with accommodating oomycete haustoria in Arabidopsis and N. benthamiana. Plasma membrane-resident proteins differentially localized to the EHM. Likewise, secretory vesicles and endosomal compartments surrounded Hpa and Pi haustoria revealing differences between these two oomycetes, and suggesting a role for vesicle trafficking pathways for the pathogen-controlled biogenesis of the EHM. The latter is supported by enhanced susceptibility of mutants in endosome-mediated trafficking regulators. These observations point at host subcellular defences and specialization of the EHM in a pathogen-specific manner. Defence-associated haustorial encasements, a double-layered membrane that grows around mature haustoria, were frequently observed in Hpa interactions. Intriguingly, all tested plant proteins accumulated at Hpa haustorial encasements suggesting the general recruitment of default vesicle trafficking pathways to defend pathogen access. Altogether, our results show common requirements of subcellular changes associated with oomycete biotrophy, and highlight differences between two oomycete pathogens in reprogramming host cell vesicle trafficking for haustoria accommodation. This provides a framework for further dissection of the pathogen-triggered reprogramming of host subcellular changes.

Mixed testicular germ cell tumor presenting as metastatic pure choriocarcinoma involving the maxillary gingiva.

Gingival metastases are infrequent and invariably associated with a widespread disease and a poor prognosis. Because of their unremarkable clinical appearance, they can be difficult to distinguish from more common gingival hyperplastic or reactive lesions, such as pyogenic granuloma, peripheral giant cell granuloma, and peripheral ossifying granuloma. We are reporting here an unusual case of a 36-year-old man with a mixed testicular germ cell tumor presenting as a metastatic pure choriocarcinoma involving the maxillary gingiva, extending from the first left premolar to the left second maxillary molar, mimicking a 'benign looking' gingival mass. Gingival metastases may be the first manifestation of a widespread metastatic disease and therefore particular attention must be paid to gingival lesions associated with atypical clinical symptoms and/or signs.

The role of Bmi1 in CNS development and in retinal degeneration

SUMMARY : The present work addresses several aspects of cell cycle regulation, cell fate specification and cell death in the central nervous system (CNS), specifically the cortex and the retina. More precisely, we investigated the role of Bmi1, a polycomb family gene required for stem cell proliferation and self-renewal, in the development of the cerebral cortex, as well as in the genesis of the retina. These data, together with studies published during the last two decades concerning cell cycle re-activation in apoptotic neurons in the CNS, raised the question of a possible link between regulation of the cell cycle during development and during retinal degeneration. 1. The effects of Bmi1 loss in the cerebral cortex : Consistently with our and others' observations on failure of Bmi9-/- stem cells to proliferate and self-renew in vitro, the Bmi9-/- cerebral cortex presented slight defects in proliferation in stem/progenitor cells compartments in vivo. This was in accordance with the pattern of Bmi1 expression in the developing forebrain. The modest proliferation defects, compared to the drastic consequences of Bmi9 loss in vitro, suggest that cell-extrinsic mechanisms may partially compensate for Bmi1 deletion in vivo during cortical histogenesis. Nevertheless, we observed a decreased proliferating activity in neurogenic regions of the adult telencephalon, more precisely in the subventricular zone, showing that Bmi1 controls neural stem/progenitor proliferation during adulthood in vivo. Our data also highlight an increased production of astrocytes at birth, and a generalized gliosis in the adult Bmi9-/- brain. Importantly, glial progenitors and astrocytes retained the ability to proliferate in the absence of Bmi1. 2. The effects of Bmi1 loss in the retina : The pattern of expression of Bmi1 during development and in the adult retina suggests a role for Bmi1 in cell fate specification and differentiation rather than in proliferation. While the layering and the global structure of the retina appear normal in Bmi1 /adult mice, immunohistochemìcal analysis revealed defects in the three major classes of retinal interneurons, namely: horizontal, bipolar and amacrine cells. Electroretinogram recordings in Bmi9-/- mice are coherent with the defects observed at the histological level, with a reduced b-wave and low-profile oscillatory potentials. These results show that Bmi1 controls not only proliferation, but also cell type generation, as previously observed in the cerebellum. 3. Cell cycle events and related neuroprotective strategies in retinal degeneration : In several neurodegenerative disorders, neurons re-express cell cycle proteins such as cyclin dependent kinases (Cdks) prior to apoptosis. Here, we show for the first time that this is also the case during retinal degeneration. Rd1 mice carry a recessive defect (Pdeóbrd/rd) that causes retinal degeneration and serves as a model of retinitis pigmentosa. We found that photoreceptors express Cdk4 and Cdk2, and undergo DNA synthesis prior to cell death. To interfere with the reactivation of Cdk-related pathways, we deleted E2fs or Brni1, which normally allow cell cycle progression. While deleting E2f1 (downstream of Cdk4/6) in Rd1 mice provides only temporary protection, knocking out Bmi1 (upstream of Cdks) leads to an extensive neuroprotective effect, independent of p16ink4a or p19arf, two tumor suppressors regulated by Bmi1. Analysis of Cdks and the DNA repair-related protein Ligase IV showed that Bmi1 acts downstream of DNA repair events and upstream of Cdks in this neurodegenerative mechanism. Expression of Cdks during an acute model of retinal degeneration, light damage-induced photoreceptor death, points to a role for Bmi1 and cell cycle proteins in retinal degeneration. Considering the similarity with the cell cycle-related apoptotic pathway observed in other neurodegenerative diseases, Bmi1 is a possible general target to prevent or delay neuronal death. RESUME : Ce travail aborde plusieurs aspects de la régulation du cycle cellulaire, de la spécification du devenir des cellules et de la mort cellulaire dans le système nerveux centrale (SNC), plus particulièrement dans le cortex cérébral et dans la rétine. Nous nous sommes intéressés au gène Bmi1, appartenant à la famille polycomb et nécessaire à la prolifération et au renouvellement des cellules souches. Nous avons visé à disséquer son rôle dans le développement du cortex et de la rétine. Ces données, ainsi qu'une série de travaux publiés au cours des deux dernières décennies concernant la réactivation du cycle cellulaire dans les neurones en voie d'apoptose dans le SNC, nous ont ensuite poussé à chercher un lien entre la régulation du cycle cellulaire pendant le développement et au cours de la dégénérescence rétinienne. 1. Les effets de l'inactivation de Bmi1 dans le cortex cérébral : En accord avec l'incapacité des cellules souches neurales in vitro à proliférer et à se renouveler en absence de Bmi1, le cortex cérébral des souris Bmi1-/- présente de légers défauts de prolifération dans les compartiments contenant les cellules souches neurales. Ceci est en accord avec le profil d'expression de Bmi1 dans le télencéphale. Les conséquences de la délétion de Bmi1 sont toutefois nettement moins prononcées in vivo qu'in vitro ; cette différence suggère l'existence de mécanismes pouvant partiellement compenser l'absence de Bmi1 pendant la corticogenèse. Néanmoins, l'observation d'une réduction de la prolifération dans la zone sous-ventriculaire, la zone majeure de neurogenèse dans le télencéphale adulte, montre que Bmi1 contrôle la prolifération des cellules souche/progénitrices neurales chez la souris adulte. Nos résultats démontrent par ailleurs une augmentation de la production d'astrocytes à la naissance ainsi qu'une gliose généralisée à l'état adulte chez les souris Bmi1-/-. Les progéniteurs gliaux et les astrocytes conservent donc leur capacité à proliférer en absence de Bmi1. 2. Les effets de l'inactivation de Bmi1 dans la rétine : Le profil d'expression de Bmi1 pendant fe développement ainsi que dans la rétine adulte suggère un rôle de Bmi1 dans la spécification de certains types cellulaires et dans la différentiation plutôt que dans la prolifération. Alors que la structure et la lamination de la rétine semblent normales chez les souris Bmi1-/-, l'analyse par immunohistochimie amis en évidence des défauts au niveau des trois classes d'interneurones rétiniens (les cellules horizontales, bipolaires et amacrines). Les électrorétinogrammes des souris Bmi1-/- sont cohérents avec les défauts observés au niveau histologique et montrent une réduction de l'onde « b » et des potentiels oscillatoires. Ces résultats montrent que Bmi1 contrôle la génération de certaines sous-populations de neurones, comme démontré auparavant au niveau de cervelet. 3. Réactivation du cycle cellulaire et stratégies théraoeutiaues dans les dégénérescences rétiniennes : Dans plusieurs maladies neurodégénératives, les neurones ré-expriment des protéines du cycle cellulaire telles que les kinases cycline-dépendantes (Cdk) avant d'entrer en apoptose. Nous avons démontré que c'est aussi le cas dans les dégénérescences rétiniennes. Les souris Rd1 portent une mutation récessive (Pde6brd/rd) qui induit une dégénérescence de la rétine et sont utilisées comme modèle animal de rétinite pigmentaire. Nous avons observé que les photorécepteurs expriment Cdk4 et Cdk2, et entament une synthèse d'ADN avant de mourir par apoptose. Pour interférer avec la réactivation les mécanismes Cdk-dépendants, nous avons inactivé les gènes E2f et Bmi1, qui permettent normalement la progression du cycle cellulaire. Nous avons mis en évidence que la délétion de E2f1 (en aval de Cdk4/6) dans les souris Rd1 permet une protection transitoire des photorécepteurs. Toutefois, l'inactivation de Bmi1 (en amont des Cdk) est corrélée à une neuroprotection bien plus durable et ceci indépendamment de p16ink4a et p19arf, deux suppresseurs de tumeurs normalement régulés par Bmi1. L'analyse des Cdk et de la ligase IV (une protéine impliquée dans les mécanismes de réparation de l'ADN) a montré que Bmi1 agit en aval des événements de réparation de l'ADN et en amont des Cdk dans la cascade apoptotique dans les photorécepteurs des souris Rd1. Nous avons également observé la présence de Cdk dans un modèle aigu de dégénérescence rétinienne induit par une exposition des animaux à des niveaux toxiques de lumière. Nos résultats suggèrent donc un rôle général de Bmi1 et des protéines du cycle cellulaire dans les dégénérescences de la rétine. Si l'on considère la similarité avec les événements de réactivation du cycle cellulaire observés dans d'autres maladies neurodégénératives, Bmi1 pourrait être une cible thérapeutique générale pour prévenir la mort neuronale.

An integrated genomic and expression analysis of 7q deletion in splenic marginal zone lymphoma.

Splenic marginal zone lymphoma (SMZL) is an indolent B-cell lymphoproliferative disorder characterised by 7q32 deletion, but the target genes of this deletion remain unknown. In order to elucidate the genetic target of this deletion, we performed an integrative analysis of the genetic, epigenetic, transcriptomic and miRNomic data. High resolution array comparative genomic hybridization of 56 cases of SMZL delineated a minimally deleted region (2.8 Mb) at 7q32, but showed no evidence of any cryptic homozygous deletion or recurrent breakpoint in this region. Integrated transcriptomic analysis confirmed significant under-expression of a number of genes in this region in cases of SMZL with deletion, several of which showed hypermethylation. In addition, a cluster of 8 miRNA in this region showed under-expression in cases with the deletion, and three (miR-182/96/183) were also significantly under-expressed (P<0.05) in SMZL relative to other lymphomas. Genomic sequencing of these miRNA and IRF5, a strong candidate gene, did not show any evidence of somatic mutation in SMZL. These observations provide valuable guidance for further characterisation of 7q deletion.

Early neutralizing antibody response against mouse mammary tumor virus: critical role of viral infection and superantigen-reactive T cells.

Infectious mouse mammary tumor virus (MMTV) is a retrovirus that expresses a superantigen shortly after infection of B cells. The superantigen first drives the polyclonal activation and proliferation of superantigen-reactive CD4+ T cells, which then induce the infected B cells to proliferate and differentiate. Part of the MMTV-induced B cell response leads to the production of Abs that are specific for the viral envelope protein gp52. Here we show that this Ab response has virus-neutralizing activity and confers protection against superinfection by other MMTV strains in vivo as soon as 4 to 7 days after infection. A protective Ab titer is maintained lifelong. Viral infection as well as the superantigen-induced T-B collaboration are required to generate this rapid and long lasting neutralizing Ab response. Polyclonal or superantigen-independent B cell activation, on the contrary, does not lead to detectable virus neutralization. The early onset of this superantigen-dependent neutralizing response suggests that viral envelope-specific B cells are selectively recruited to form part of the extrafollicular B cell response and are subsequently amplified and maintained by superantigen-reactive Th cells.

T cell costimulation by the TNF ligand BAFF.

The TNF ligand family member BAFF (B cell activating factor belonging to the TNF family, also called Blys, TALL-1, zTNF-4, or THANK) is an important survival factor for B cells [corrected]. In this study, we show that BAFF is able to regulate T cell activation. rBAFF induced responses (thymidine incorporation and cytokine secretion) of T cells, suboptimally stimulated through their TCR. BAFF activity was observed on naive, as well as on effector/memory T cells (both CD4+ and CD8+ subsets), indicating that BAFF has a wide function on T cell responses. Analysis of the signal transduced by BAFF into T cells shows that BAFF has no obvious effect on T cell survival upon activation, but is able to deliver a complete costimulation signal into T cells. Indeed, BAFF is sufficient to induce IL-2 secretion and T cell division, when added to an anti-TCR stimulation. This highlights some differences in the BAFF signaling pathway in T and B cells. In conclusion, our results indicate that BAFF may play a role in the development of T cell responses, in addition to its role in B cell homeostasis.

Study of the proteolytic activity of the paracaspase MALT1 in T cell activation

Summary : Several signalling cascades are initiated through the triggering of the T cell receptor (TCR) by an antigenic peptide expressed at the surface of an antigen presenting cell. These pathways lead to morphological changes controlling T cell adhesiveness and migration to the site of infection, and to the activation of transcription factors that regulate key genes for the proper development of the immune response. Amongst them, the nuclear factor xB (NF-κB) is the subject of intense research since more than twenty years because deregulated NF-κB signalling in lymphocytes can lead to immunodeficiency, autoimmunity or lymphomas. Therefore, the understanding of the molecular mechanisms regulating NF-κB activation is important for the development of new therapeutics aimed at treating various diseases. In T lymphocytes, a complex composed of CARMAI, BCL10 and MALT1 relays signals from TCR proximal events to NF-κB activation. Gene translocations of the BCL10 or MALTI genes or oncogenic mutations affecting CARNA 1 result in constitutive NF-κB activation and are related to the development of certain forms of lymphomas. MALT1 contains acaspase-like domain, but it is unknown whether this domain is proteolytically active. In this study, we found that MALT1 has arginine-directed proteolytic activity. We showed that the proteolytic activity of MALT 1 is key to TCR-induced NF-κB activation and production of interleukin 2. We identified BCL 10 as a MALT 1 substrate, and we showed that its cleavage regulates T cell adhesion to the extracellular matrix protein fibronectin. Furthermore, we identified caspase 10 as another substrate of MALT1. caspase 10 is a close homologue of caspase 8 and is known to be involved in the induction of apoptosis upon Fast or TRAIL stimulation. We showed that caspase 10 is important for TCR-induced NF-κB activation and interleukin 2 production, identifying for the first time a non apoptotic function for caspase 10. These data provide evidence for previously uncharacterized roles of MALT 1 and BCL 10 in the regulation of T cell adhesion and of caspase 10 in the activation of lymphocytes, and allow a better understanding of the molecular mechanisms of T lymphocyte activation. Since the proteolytic activity of MALT1 is essential to T cell activation, it suggests that the targeting of this activity may be relevant for the development of immunomodulatory or anticancer drugs. Résumé : De nombreuses voies de signalisation sont initiées via la stimulation des récepteurs des cellules T (TCR) par un peptide antigénique exprimé à la surface d'une cellule présentatrice d'antigènes. Ces cascades de signalisation produisent des changements morphologiques qui contrôlent l'adhésion des cellules T et leur migration vers le site d'infection. Elles contrôlent également l'activation de facteurs de transcription qui régulent la transcription de gènes importants pour la réponse immunitaire. Parmi ces derniers, le facteur nucléaire KB (NF-κB) joue un rôle essentiel, puisqu'une régulation aberrante de son activité dans les lymphocytes peut causer des immunodéficiences, des maladies autoimmunes ou des lymphomes. C'est pour cela que la compréhension des mécanismes moléculaires qui contrôlent l'activation de NF-κB est donc importante pour le développement de nouvelles thérapies. Un complexe contenant les protéines CAIZMAI, BCL10 et MALT1 transmet, dans les lymphocytes T, le signal du TCR vers l'activation de NF-κB. Des translocations des gènes qui codent pour BCL10 et MALTI et des mutations affectant la fonction de CARNAI ont été liées au développement de certaines formes de lymphomes. MALTI contient un domaine qui ressemble au domaine catalytique présent dans les caspases, mais il n'est pas connu si ce domaine a une activité protéolytique. Dans cette étude, nous avons découvert que MALTI est une protéase qui a une spécificité pour les acides aminés basiques comme l'arginine. Nous montrons que l'activité protéolytique de MALTI est importante pour l'activation de NF-κB et la production d'interleukine 2 après stimulation du TCR. Nous avons observé que BCL10 est clivé par MALTI pendant l'activation des lymphocytes T, et que ce clivage est impliqué dans la régulation de l'adhésion des lymphocytes T à la fibronectin, une protéine de la matrice extracellulaire. De plus, nous avons identifié que la caspase 10, qui a une grande homologie avec la caspase 8 et qui jusqu'à maintenant est connue pour son rôle dans l'induction de la mort cellulaire en réponse à une stimulation par Fast ou par TRAIL, est également un substrat de MALT 1. En montrant que la caspase 10 est nécessaire à l' activation de NF-icB et à la production de l'interleukine 2 après stimulation du TCR, nous décrivons pour la première fois une fonction non apoptotique de la caspase 10. Ces résultats décrivent de nouveaux rôles pour MALT1 et BCL10 dans le contrôle de l'adhésion des lymphocytes T et de la caspase 10 pour l'activation des lymphocytes T. Puisque l'activité protéolytique de MALT1 est essentielle pour l'activation des lymphocytes T, nous suggérons que cibler cette activité protéolytique de MALT 1 pourrait amener de nouvelles possibilités de traitement de maladies où une activation aberrante des lymphocytes est impliquée.

TCR-induced NF-kappaB activation: a crucial role for Carma1, Bcl10 and MALT1.

T-cell receptor (TCR) engagement induces the maturation of thymocytes and the activation and proliferation of peripheral T cells through signaling pathways that target several transcription factors. The transcription factor nuclear factor-κB (NF-κB) has an essential role in the activation of mature T cells but the signaling pathway leading from TCR stimulation to NF-κB activation is not well defined. Carma1, Bcl10 and MALT1 are recently identified proteins that have an important and previously unexpected role in antigen receptor-induced NF-κB activation and the control of lymphocyte proliferation. We believe that the recent advances in this field could stimulate research for the development of new immunomodulatory drugs and could lead to a better understanding of the molecular mechanisms underlying the formation of lymphomas and potentially of other immune disorders.

Notch1 deficiency dissociates the intrathymic development of dendritic cells and T cells.

Thymic dendritic cells (DCs) form a discrete subset of bone marrow (BM)-derived cells, the function of which is to mediate negative selection of autoreactive thymocytes. The developmental origin of thymic DCs remains controversial. Although cell transfer studies support a model in which T cells and thymic DCs develop from the same intrathymic pluripotential precursor, it remains possible that these two types of cells develop from independent intrathymic precursors. Notch proteins are cell surface receptors involved in the regulation of cell fate specification. We have recently reported that T cell development in inducible Notch1-deficient mice is severely impaired at an early stage, before the expression of T cell lineage markers. To investigate whether development of thymic DCs also depends on Notch1, we have constructed mixed BM chimeric mice. We report here that thymic DC development from Notch1(-/)- BM precursors is absolutely normal (in terms of absolute number and phenotype) in this competitive situation, despite the absence of Notch1(-/)- T cells. Furthermore, we find that peripheral DCs and Langerhans cells are also not affected by Notch1 deficiency. Our results demonstrate that the development of DCs is totally independent of Notch1 function, and strongly suggest a dissociation between intrathymic T cell and DC precursors.

Modulation of the airway allergic response : characterization of the cellular and molecular mechanisms

ABSTRACT Allergic asthma is a major complication of atopy. Its severity correlates with the presence of activated T lymphocytes and eosinophils in the bronchoalveolar lavage fluid (BALF). Mechanisms that protect against asthma are poorly understood. Based on oral models of mucosal tolerance induction, models using the nasal route showed that uptake of important amounts of antigen can induce tolerance and reverse the allergic phenotype. 1L-10 producing regulatory T cells were proposed as key players in tolerance induction, but other players, e.g. dendritic cells (DC), B cells and epithelial cells may have to be taken into consideration. The objective of the present study is to characterize the effects of a therapeutic intranasal treatment (INT) in a murine model of asthma and to determine, in this model, the cellular and molecular mechanisms leading to protection against asthma. First, we established an asthma model by sensitizing the BALB/c mouse to ovalbumin (OVA) by two intraperitoneal injections of alum-adsorbed OVA and three inhalations of aerosolized OVA. Then OVA was applied to the nasal mucosa of OVA- sensitized mice. Mice were later re-exposed to OVA aerosols to assess the protection induced by OVA INT. OVA sensitization induced strong eosinophil recruitment, OVA-specific T cell proliferation and IgE production. Three intranasal treatments at 24-hour intervals with 1.5 mg OVA drastically reduced inflammatory cell recruitment into the BALF and inhibited OVA-specific IgE production upon allergen re-exposure. T cell proliferation in ex vivo bronchial lymph node (BLN) cells was inhibited, as well as TH2 cytokine production. Protection against OVA-induced bronchial inflammation was effective for an extended period of time and treated mice resisted a second re-exposure. Transfer of CD4+ cells from BLN and lungs of OVA-treated mice protected asthmatic recipient mice from subsequent aerosol challenge indicating an involvement of CD4+ T regulatory cells in this protection. RESUME L'asthme allergique est une manifestation clinique majeure de l'atopie. La sévérité de l'asthme est liée à la présence de lymphocytes T activés ainsi que d'éosinophiles dans le lavage broncho-alvéolaire (LBA). Les mécanismes permettant de se prémunir contre l'asthme sont mal connus. Basés sur des modèles muqueux d'induction de tolérance par la voie orale, des modèles utilisant la voie nasale ont montré que d'importantes quantités d'antigène peuvent induire une tolérance et ainsi reverser le phénotype allergique. Des cellules régulatrices produisant de l'IL-10 pourraient jouer un rôle clé dans l'induction de la tolérance mais d'autres acteurs tels que les cellules dendritiques, les cellules B et les cellules épithéliales doivent aussi être prises en compte. L'objectif de la présente étude est de caractériser les effets d'un traitement intranasal thérapeutique dans un modèle murin d'asthme et de déterminer dans ce modèle les mécanismes cellulaires et moléculaires conférant une protection contre l'asthme. En premier lieu, un modèle d'asthme allergique a été établi en sensibilisant des souris BALB/c à l'ovalbumine (OVA) par deux injections intraperitonéales d'OVA adsorbé sur de l'alum et trois séances d'OVA en aérosol. Dans un second temps, de l'OVA a été administrée sur la muqueuse nasale des souris sensibilisées à l'OVA. Les souris furent ensuite challengées par des aérosols d'OVA afin d'évaluer la protection conférée par le traitement intranasal à l'OVA. La sensibilisation à l'OVA a induit un fort recrutement d'éosinophiles, une réponse proliférative des cellules T à l'OVA ainsi qu'une production d'lgE spécifiques. Trois traitements intranasaux à 24 heures d'intervalle avec 1.5 mg d'OVA ont permis de réduire drastiquement le recrutement des cellules inflammatoires dans le LBA ainsi que d'inhiber la production d'lgE spécifiques à l'OVA produits lors d'une ré-exposition à l'OVA. La prolifération en réponse à l'OVA de cellules extraites ex vivo de ganglions bronchiques a, elle aussi, été inhibée de même que la production de cytokines TH2. La protection contre l'inflammation provoquée par l'aérosol est efficace pour une longue période et les souris traitées résistent à une seconde ré- exposition. Le transfert de cellules CD4+ issues de ganglions bronchiques et de poumons de souris traitées à l'OVA protège les souris asthmatiques receveuses contre les effets inflammatoires d'un aérosol, indiquant que des cellules T CD4+ régulatrices pourraient être impliquées dans cette protection. RESUME DESTINE A UN LARGE PUBLIC L'asthme est une affection des voies respiratoires qui se caractérise par une contraction de la musculature des voies aériennes, une production de mucus et d'anticorps de l'allergie (IgE). On parle d'asthme allergique lorsque les facteurs déclenchant l'asthme sont des allergènes inhalés tels que acariens, pollens ou poils d'animaux. Le système immunitaire des patients asthmatiques a un défaut de programmation qui le rend réactif à des substances qui sont normalement inoffensives. Le traitement actuel de l'asthme repose sur le soulagement des symptômes grâce à des produits à base de stéroïdes. Les techniques permettant de reprogrammer le système immunitaire (immunothérapie) ne sont pas efficaces pour tous les antigènes et prennent beaucoup de temps. En conséquence, il est nécessaire de mieux comprendre les mécanismes sous-tendant une telle reprogrammation afin d'en améliorer le rendement et l'efficacité. Dans ce but, des modèles d'immunothérapie ont été mis au point chez la souris. Ils permettent une plus grande liberté d'investigation. Dans cette étude, un modèle d'asthme allergique dans la souris a été établi par une sensibilisation à un antigène particulier : l'ovalbumine (OVA). Ce modèle présente les caractéristiques principales de l'asthme humain : recrutement de cellules inflammatoires dans les poumons, augmentation de la production d'anticorps et de la résistance des bronches aux flux respiratoires. Cette souris asthmatique a ensuite été traitée par application nasale d'OVA. Comparées aux souris non traitées, les souris traitées à l'OVA ont moins de cellules inflammatoires dans leurs poumons et produisent moins d'anticorps IgE. D'autres marqueurs inflammatoires sont aussi fortement diminués. Des cellules de poumons ou de ganglions bronchiques prélevées sur des souris traitées injectées dans des souris asthmatiques améliorent les symptômes de l'asthme. Ces cellules pourraient donc avoir un rôle régulateur dans l'asthme. Les caractériser et les étudier afin d'être capable de les générer est crucial pour les futures thérapies de l'asthme.

Regulation of the immune response by macrophage migration inhibitory factor: biological and structural features.

The classical T cell cytokine macrophage migration inhibitory factor (MIF) has reemerged recently as a critical mediator of the host immune and stress response. MIF has been found to be a mediator of several diseases including gram-negative septic shock and delayed-type hypersensitivity reactions. Its immunological functions include the modulation of the host macrophage and T and B cell response. In contrast to other known cytokines, MIF production is induced rather than suppressed by glucocorticoids, and MIF has been found to override the immunosuppressive effects of glucocorticoids. Recently, elucidation of the three-dimensional structure of MIF revealed that MIF has a novel, unique cytokine structure. Here the biological role of MIF is reviewed in view of its distinct immunological and structural properties.

Characterization of the Morphological and Molecular Changes Associated with Diabetic Peripheral Neuropathy in Type 2 Diabetes

More than 246 million individuals worldwide are affected by diabetes mellitus (DM) and this number is rapidly increasing (http://www.eatlas. idf.org). 90% of all diabetic patients have type 2 DM, which is characterized by insulin resistance and b-cell dysfunction. Even though diabetic peripheral neuropathy (DPN) is the major chronic complication of DM its underlying pathophysiological mechanisms still remain unknown. To get more insight into the DPN associated with type 2 DM, we characterized the rodent model of this form of diabetes, the db/db mice. The progression of pathological changes in db/db mice mimics the ones observed in humans: increase of the body weight, insulin insensitivity, elevated blood glucose level and reduction in nerve conduction velocity (NCV). Decreased NCV, present in many peripheral neuropathies, is usually associated with demyelination of peripheral nerves. However, our detailed analysis of the sciatic nerves of db/db mice exposed for 4 months to hyperglycemia, failed to reveal any signs of demyelination in spite of significantly reduced NCV in these animals. We therefore currently focus our analysis on the structure of Nodes of Ranvier, regions of intense axo-glial interactions, which also play a crucial role in rapid saltatory impulse conduction. In addition we are also evaluating molecular changes in somas of sensory neurons projecting through sciatic nerve, which are localized in the dorsal root ganglia. We hope that the combination of these approaches will shed light on molecular alterations leading to DPN as a consequence of type 2 DM.

A Multi-Center Phase II Study (SAKK 36/06) of Single Agent Everolimus (RAD001) In Patients with Relapsed or Refractory Mantle Cell Lymphoma

Introduction: Mantle cell lymphoma (MCL) accounts for 6% of all B-cell lymphomas and remains incurable for most patients. Those who relapse after first line therapy or hematopoietic stem cell transplantation have a dismal prognosis with short response duration after salvage therapy. On a molecular level, MCL is characterised by the translocation t[11;14] leading to Cyclin D1 overexpression. Cyclin D1 is downstream of the mammalian target of rapamycin (mTOR) kinase and can be effectively blocked by mTOR inhibitors such as temsirolimus. We set out to define the single agent activity of the orally available mTOR inhibitor everolimus (RAD001) in a prospective, multi-centre trial in patients with relapsed or refractory MCL (NCT00516412). The study was performed in collaboration with the EU-MCL network. Methods: Eligible patients with histologically/cytologically confirmed relapsed (not more than 3 prior lines of systemic treatment) or refractory MCL received everolimus 10 mg orally daily on day 1 - 28 of each cycle (4 weeks) for 6 cycles or until disease progression. The primary endpoint was the best objective response with adverse reactions, time to progression (TTP), time to treatment failure, response duration and molecular response as secondary endpoints. A response rate of ≤ 10% was considered uninteresting and, conversely, promising if ≥ 30%. The required sample size was 35 pts using the Simon's optimal two-stage design with 90% power and 5% significance. Results: A total of 36 patients with 35 evaluable patients from 19 centers were enrolled between August 2007 and January 2010. The median age was 69.4 years (range 40.1 to 84.9 years), with 22 males and 13 females. Thirty patients presented with relapsed and 5 with refractory MCL with a median of two prior therapies. Treatment was generally well tolerated with anemia (11%), thrombocytopenia (11%), neutropenia (8%), diarrhea (3%) and fatigue (3%) being the most frequent complications of CTC grade III or higher. Eighteen patients received 6 or more cycles of everolimus treatment. The objective response rate was 20% (95% CI: 8-37%) with 2 CR, 5 PR, 17 SD, and 11 PD. At a median follow-up of 6 months, TTP was 5.45 months (95% CI: 2.8-8.2 months) for the entire population and 10.6 months for the 18 patients receiving 6 or more cycles of treatment. Conclusion: This study demonstrates that single agent everolimus 10 mg once daily orally is well tolerated. The null hypothesis of inactivity could be rejected indicating a moderate anti-lymphoma activity in relapsed/refractory MCL. Further studies of either everolimus in combination with chemotherapy or as single agent for maintenance treatment are warranted in MCL.

Clinical characteristics and outcome of isolated extracerebral relapses of primary central nervous system lymphoma: a case series.

There is very limited data on isolated systemic relapses of primary central nervous system lymphomas (PCNSL). We retrospectively reviewed the clinical characteristics and outcome of 10 patients with isolated systemic disease among 209 patients with PCNSL mainly treated with methotrexate-based chemotherapy (CT) with or without radiation therapy (RT). Isolated systemic relapse remained rare (4.8%, 10/209 patients). Median time from initial diagnosis to relapse was 33 months (range, 3-94). Sites of relapse were mostly extranodal. Three patients presented with early extra-cerebral (EC) relapse 3, 5 and 8 months from the beginning of initial treatment, respectively, and 7 patients had later relapses (range, 17-94 months). Treatment at relapse included surgery alone, RT alone, CT with or without radiotherapy, or CT with autologous stem cell transplantation (ASCT). Median overall survival (OS) after relapse was 15.5 months (range, 5.8-24.5) compared to 4.6 months (range, 3.6-6.5) for patients with central nervous system (CNS) relapse (p = 0.35). In conclusion, isolated systemic relapses exist but are infrequent. Early EC relapse suggests the presence of systemic disease undetectable by conventional evaluation at initial diagnosis. Patient follow-up must be prolonged because systemic relapse can occur as late as 10 years after initial diagnosis. Whether EC relapses of PCNSL have a better prognosis than CNS relapses needs to be assessed in a larger cohort. Copyright © 2010 John Wiley & Sons, Ltd.