Syndrome de larva migrans cutanée sur pied malformé (à propos d’un cas)

Le syndrome de larva migrans cutanée est une dermite sous cutanée causée par des larves d'ankylostomes d'animaux en impasse parasitaire chez l'homme. L'infestation transcutanée est favorisée par le contact avec le sol contaminé par les larves du parasite. Nous rapportons le cas d'un nourrisson de 15 mois, originaire de Guinée-Bissau, atteint d'un syndrome de larva migrans cutanée sur un pied malformé. Cette malformation sous forme d'une syndactylie associée à une tuméfaction du pied, était à l'origine d'un retard d'acquisition de la station debout. De même, on a rapporté une notion de pieds nus, vue la difficulté de chausser le pied malformé du patient. Tous ces facteurs auraient contribués à favoriser l'infestation du malade par les larves du nématode.Pan African Medical Journal 2016; 2

Molecular Mechanisms of HIF-1α Modulation Induced by Oxygen Tension and BMP2 in Glioblastoma Derived Cells

BACKGROUND: Glioblastoma multiforme (GBM) is one of most common and still poorly treated primary brain tumors. In search for new therapeutic approaches, Bone Morphogenetic Proteins (BMPs) induce astroglial commitment in GBM-derived cells in vitro. However, we recently suggested that hypoxia, which is characteristic of the brain niche where GBM reside, strongly counter-acts BMP effects. It seems apparent that a more complete understanding of the biology of GBM cells is needed, in particular considering the role played by hypoxia as a signaling pathways regulator. HIF-1alpha is controlled at the transcriptional and translational level by mTOR and, alike BMP, also mTOR pathway modulates glial differentiation in central nervous system (CNS) stem cells. METHODOLOGY/PRINCIPAL FINDINGS: Here, we investigate the role of mTOR signaling in the regulation of HIF-1alpha stability in primary GBM-derived cells maintained under hypoxia (2% oxygen). We found that GBM cells, when acutely exposed to high oxygen tension, undergo Akt/mTOR pathway activation and that BMP2 acts in an analogous way. Importantly, repression of Akt/mTOR signaling is maintained by HIF-1alpha through REDD1 upregulation. On the other hand, BMP2 counter-acts HIF-1alpha stability by modulating intracellular succinate and by controlling proline hydroxylase 2 (PHD2) protein through inhibition of FKBP38, a PHD2 protein regulator. CONCLUSIONS/SIGNIFICANCE: In this study we elucidate the molecular mechanisms by which two pro-differentiating stimuli, BMP2 and acute high oxygen exposure, control HIF-1alpha stability. We previously reported that both these stimuli, by inducing astroglial differentiation, affect GBM cells growth. We also found differences in high oxygen and BMP2 sensitivity between GBM cells and normal cells that should be further investigated to better define tumor cell biology

2-deoxyglucose effects and cancer stem cell distribution are affected by hypoxia in glioblastoma multiforme

Glioblastoma multiforme (GBM) is the highest grade glioma and the most common and aggressive form of primary adult brain tumors, classified as grade IV astrocytoma. The term "multiforme" in GBM describes the heterogeneous nature of these tumors, also characterized by diffuse infiltration into surrounding tissue. These features prevent complete surgical resection. Despite the use of surgery, radiation and chemotherapy, the median survival for patients with GBM is only 14.6 months. The poor prognosis for GBM patients is due to a high incidence of recurrence and limited responses to approved therapies [1]. Treatment-refractory property is thought to be due to a subpopulation of cells, called brain tumor stem cells or brain tumor initiating cells [2]. To overcome this problem, strategies combining chemotherapy and drugs that target different mechanism of action are under current research [3]. One of the most used oral alkylating agents for the treatment of GBM is temozolomide (TMZ). However, controversial data indicate that although TMZ seems to induce a dose- and time-dependent decline of the tumor stem cell subpopulation [4], other works indicate that TMZ does not seem to affect stem cells [5], which are considered the most chemoresistant cell population in the tumor bulk [6-9]. Thus, it is becoming pivotal to identify the phenotypic features of the resistant tumor cells and define their localization in the GBM tumor mass in order to distinguish and more effectively target them. Structural and functional integrity of brain function profoundly depends on a regular oxygen and glucose supply. Glucose metabolism in tumor cells occurs mainly through anaerobic glycolysis, even when tumor-derived cells are cultured under normoxic conditions, indicating that pseudo-anaerobic glycolysis is constitutively upregulated through stable genetic changes [10]. This phenomenon was first reported by Otto Heinrich Warburg in the 1920s [11]. Following Warburg’s initial observation, the interest of the scientific community toward the metabolic property of cancer cells, varied in the course of the years, especially after the widespread of the newer molecular techniques. The application of the imaging technique positron emission tomography (PET) using the glucose analogue tracer 18fluorodeoxyglucose (fdG) showed that most primary and metastatic human cancers had significantly increased glucose uptake, which is largely dependent on the rate of glycolysis, indicating that it continues to confer a proliferative advantage for the tumor [12-14]. Control over glycolytic flux primarily resides at the transporter and phosphorylation steps [15-17], although it can also be regulated at many downstream steps in the glycolytic pathway [18, 19]. The proliferative advantage of the glycolytic phenotype is not immediately apparent, since anaerobic metabolism of glucose produces only 2 ATP per glucose, whereas complete oxidation produces 38 ATP per glucose. Moreover, the metabolic products of glycolysis, such as hydrogen ions (H+), causes acidification of the extracellular space, which might result in cellular toxicity [20]. So why do tumor cells undergo glycolysis which is inefficient and potentially toxic? It has been suggested that cancer cells up regulated glycolysis is neither random nor accidental. Rather, it represents an evolved solution to common environmental growth constraints during carcinogenesis [10]. Tumors, particularly highly proliferative glioblastomas, characterized by a hypoxic microenvironment, modify their vascular niches in order to maintain the cancer stem cell pool [21]. These data provide further evidence that cancer development is not only a process that involve epigenetic or genetic events, but that also depends on the microenvironment. One of the aspects we investigated is the role of the hypoxic region, a common feature of solid tumors, in the maintenance of the brain tumor mass. Oxygen is an essential regulator of cellular metabolism, survival and proliferation. The oxygenation level within a tumor is not consistent and behaves in a cycling nature [22, 23]. This phenomenon is a result of several tumor characteristics such as chaotic vasculature, poor oxygen diffusion across the expanding tumor and irregular blood flow leading to an enhanced metastatic potential of the tumor [24]. Under these conditions a signaling pathway involving a key oxygen response regulator termed the hypoxia-inducible factor 1α (HIF1α) is switched on. HIF1α is a transcription factor that, in hypoxia, drives the induction or repression of a myriad of genes controlling multiple cell functions such as angiogenesis, metabolism, invasion/metastasis and apoptosis/survival [25]. Thus, the level of oxygen in a tumor cell dictates their molecular response through the modulation of gene expression. For this research project we sought to define how microenvironmental and intratumoral hypoxia affects cell metabolism and cancer stem cell distribution in GBM. Particularly, in the first part of this study we investigated the effects mediated by 2-deoxyglucose (2-DG), a glucose analogue and a very well described competitive inhibitor of glycolysis on primary GBM-derived cells maintained under hypoxia. In the second part, by exploiting image guided surgery to sample multiple intratumoral areas, in collaboration with the neurosurgery department, we identified the presence of a cellular heterogeneity in correlation to the oxygen tension gradient within the GBM mass. These results led us to define a novel concentric model of GBM stem cell niche.Il glioblastoma multiforme (GBM) è il più alto grado di glioma e la forma più comune e aggressiva tra i tumori primari cerebrali nell’adulto, classificato come astrocitoma di grado IV. Il termine "multiforme" in GBM descrive la natura eterogenea di questi tumori, anche caratterizzata da diffusa infiltrazione nel tessuto circostante. Queste caratteristiche rendono l’asportazione completa del tumore impossibile. Nonostante l'uso della chirurgia, la radioterapia e la chemioterapia, la sopravvivenza media per i pazienti con GBM è di soli 14,6 mesi. La bassa sopravvivenza dei pazienti colpiti da questo tumore è dovuta ad una elevata incidenza di recidiva e scarsa risposta alle terapie convenzionali [1]. Si pensa che la refrattarietà al trattamento sia dovuta ad una sottopopolazione di cellule, chiamate cellule staminali tumorali o cellule iniziatrici del tumore cerebrale [2]. Per superare questo problema, attualmente sono in fase di ricerca diverse strategie che combinano la chemioterapia con farmaci che colpiscono diversi meccanismi di azione [3]. Uno degli agenti alchilanti più utilizzati nel trattamento del glioblastoma multiforme è il temozolomide (TMZ). Tuttavia, a questo riguardo esistono dati controversi: alcuni studi hanno dimostrato, infatti, il trattamento con TMZ sembra indurre una diminuzione delle cellule staminali del tumore in una maniera dose-e tempo-dipendente [4], al contrario altri lavori hanno dimostrato che il TMZ non sembra influenzare le cellule staminali [5]. Per questa ragione queste cellule vengono considerate le più chemio-resistenti all’interno della massa tumorale [6-9]. Quindi sta diventando di fondamentale importanza identificare le caratteristiche fenotipiche delle cellule tumorali resistenti e definire la loro localizzazione all’interno della massa tumorale, al fine di distinguerle dalla controparte sana ed eliminarle più efficacemente. L’integrità strutturale e funzionale delle funzioni cerebrali dipende profondamente da un normale apporto di ossigeno e glucosio. Il glucosio nelle cellule tumorali viene metabolizzato principalmente attraverso la glicolisi anaerobica e questo processo si mantiene anche quando le cellule tumorali vengono messe in coltura in condizioni normossiche. Questo indica che la glicolisi pseudo-anaerobica è costitutivamente upregolata attraverso mutazioni genetiche [10]. Tale fenomeno è stato descritto per la prima volta da Otto Heinrich Warburg nel 1920 [11]. A seguito di questa iniziale osservazione, l'interesse della comunità scientifica verso le proprietà metaboliche delle cellule tumorali è stata variabile nel corso degli anni, soprattutto dopo la diffusione delle nuove tecniche molecolari. L'applicazione della tecnica PET (Positron Emission Tomography), che utilizza il tracciante analogo del glucosio 18fluorodeossiglucosio (FDG), ha dimostrato un notevole aumento nell’assorbimento del glucosio, che dipende in larga misura dal tasso di glicolisi, nella maggior parte dei tumori primari e metastatici umani. Questo risultato sta ad indicare che la glicolisi continua a conferire un vantaggio proliferativo per il tumore [12-14]. Il controllo sul flusso glicolitico risiede principalmente a livello del trasportatore del glucosio e nei primi passaggi di fosforilazione [15-17], ma può anche essere regolato in molte fasi più a valle della via glicolitica [18, 19]. Il vantaggio proliferativo del fenotipo glicolitico non è immediatamente evidente, poiché il metabolismo anaerobico del glucosio produce solo 2 ATP per glucosio, mentre l'ossidazione completa produce 38 ATP per glucosio. Inoltre, i prodotti metabolici della glicolisi, come ad esempio gli ioni idrogeno (H+), provocano l’acidificazione dello spazio extracellulare, cosa che potrebbe comportare tossicità cellulare [20]. Allora perché le cellule tumorali utilizzano preferibilmente la glicolisi, che è inefficiente e potenzialmente tossica? È stato suggerito che l’upregolazione della via glicolitica, da parte delle cellule tumorali, non sia né casuale né accidentale. Piuttosto, essa rappresenta una soluzione evolutasi durante lo sviluppo del tumore in risposta a vincoli microambientali [10]. I tumori altamente proliferativi, come ad esempio il glioblastomi, sono caratterizzati da un microambiente ipossico. Le cellule tumorali, presenti in questo microambiente ipossico, modificano le loro nicchie vascolari al fine di mantenere il pool delle cellule staminali tumorali [21]. Questi dati indicano che lo sviluppo del cancro non è solo un processo che coinvolge solamente eventi epigenetici o genetici, ma dipende anche dal microambiente. Uno degli aspetti che stiamo indagando è il ruolo dell’ipossia, una caratteristica comune dei tumori solidi, nel mantenimento della massa tumorale cerebrale. L'ossigeno è un regolatore fondamentale del metabolismo cellulare, la sopravvivenza e la proliferazione. Il livello di ossigenazione all'interno del tumore non è costante [22, 23]. Questo fenomeno è il risultato di diverse caratteristiche del tumore, come la presenza di una rete vascolare aberrante, una povera diffusione dell'ossigeno attraverso il tumore in espansione e un irregolare flusso di sangue. Tutti questi fattori aumentano le capacità metastatiche del tumore [24]. In queste condizioni ipossiche viene attivato un pathway che coinvolge un regolatore chiave della risposta ai livelli di ossigeno presenti nella cellula, chiamato hypoxia inducible factor 1α (HIF1α). HIF1α è un fattore di trascrizione che, in presenza di ipossia, promuove l'induzione o la repressione di una miriade di geni che controllano funzioni cellulari multiple, come l'angiogenesi, il metabolismo, l'invasione/metastasi e l'apoptosi/sopravvivenza [25]. Pertanto, il livello di ossigeno nelle cellule tumorali controlla particolari risposte cellulari consequenzialmente alla modulazione dell'espressione genica. Durante questo progetto di ricerca abbiamo cercato di definire come l'ipossia microambientale e intratumorale influenzasse il metabolismo e la distribuzione delle cellule staminali tumorali nel GBM. In particolare, nella prima parte dello studio abbiamo analizzato gli effetti mediati dal 2-deoxyglucosio (2-DG), un analogo del glucosio e noto inibitore competitivo della glicolisi su cellule primarie di GBM mantenute in ipossia. Nella seconda parte, mediante l'uso della chirurgia guidata per immagini, grazie alla collaborazione con la neurochirurgia di Padova, abbiamo campionato regioni diverse intratumorali ed abbiamo identificato la presenza di una certa eterogeneità cellulare in correlazione al gradiente di ossigeno all'interno della massa dei GBM. Questi risultati ci hanno permesso di definire un nuovo modello concentrico di nicchia delle cellule staminali del GBM

Hypoxia and succinate antagonize 2-deoxyglucose effects on glioblastoma

International audienceGlioblastoma multiforme (GBM) are highly proliferative brain tumors characterized by a hypoxic microenvironment which controls GBM stem cell maintenance. Tumor hypoxia promotes also elevated glycolytic rate, thus limiting glucose metabolism is a potential approach to inhibit tumor growth. Here we investigate the effects mediated by 2-deoxyglucose (2-DG), a glucose analogue, on primary GBM-derived cells maintained under hypoxia. Our results indicate that hypoxia protects GBM cells from the apoptotic effect elicited by 2-DG, which raises succinate dehydrogenase activity thus promoting succinate level decrease. As a consequence hypoxia inducible factor-1α (HIF-1α) degradation occurs and this induces GBM cells to acquire a neuronal committed phenotype. By adding succinate these effects are reverted, as succinate stabilizes HIF-1α and increases GBM stem cell fraction particularly under hypoxia, thus preserving the tumor stem cell niche

The efficacy of lapatinib and nilotinib in combination with radiation therapy in a model of NF2 associated peripheral schwannoma

International audienceNeurofibromatosis type 2 (NF2), a neurogenetic condition manifest by peripheral nerve sheath tumors (PNST) throughout the neuroaxis for which there are no approved therapies. In vitro and in vivo studies presented here examine agents targeting signaling pathways, angiogenesis, and DNA repair mechanisms. In vitro dose response assays demonstrated potent activity of lapatinib and nilotinib against the mouse schwannoma SC4 (Nf2 -/-) cell line. We then examined the efficacy of everolimus, nilotinib, lapatinib, bevacizumab and radiation (RT) as mono- and combination therapies in flank and sciatic nerve in vivo NF2-PNST models. Data were analyzed using generalized linear models, two sample T-tests and paired T-tests, and linear regression models. SC4(Nf2 -/-) cells implanted in the flank or sciatic nerve showed similar rates of growth (p = 0.9748). Lapatinib, nilotinib and RT significantly reduced tumor growth rate versus controls in the in vivo flank model (p = 0.0025, 0.0062, and 0.009, respectively) whereas bevacizumab and everolimus did not. The best performers were tested in the in vivo sciatic nerve model of NF2 associated PNST, where chemoradiation outperformed nilotinib or lapatinib as single agents (nilotinib vs. nilotinib + RT, p = 0.0001; lapatinib versus lapatinib + RT, p < 0.0001) with no observed toxicity. There was no re-growth of tumors even 14 days after treatment was stopped. The combination of either lapatinib or nilotinib with RT resulted in greater delays in tumor growth rate than any modality alone. This data suggest that concurrent low dose RT and targeted therapy may have a role in addressing progressive PNST in patients with NF2

The Pre-Existing Human Antibody Repertoire to Computationally Optimized Influenza H1 Hemagglutinin Vaccines.

Computationally optimized broadly reactive Ag (COBRA) hemagglutinin (HA) immunogens have previously been generated for several influenza subtypes to improve vaccine-elicited Ab breadth. As nearly all individuals have pre-existing immunity to influenza viruses, influenza-specific memory B cells will likely be recalled upon COBRA HA vaccination. We determined the epitope specificity and repertoire characteristics of pre-existing human B cells to H1 COBRA HA Ags. Cross-reactivity between wild-type HA and H1 COBRA HA proteins P1, X6, and Y2 were observed for isolated mAbs. The mAbs bound five distinct epitopes on the pandemic A/California/04/2009 HA head and stem domains, and most mAbs had hemagglutination inhibition and neutralizing activity against 2009 pandemic H1 strains. Two head-directed mAbs, CA09-26 and CA09-45, had hemagglutination inhibition and neutralizing activity against a prepandemic H1 strain. One mAb, P1-05, targeted the stem region of H1 HA, but did not compete with a known stem-targeting H1 mAb. We determined that mAb P1-05 recognizes a recently discovered HA epitope, the anchor epitope, and we identified similar mAbs using B cell repertoire sequencing. In addition, the trimerization domain distance from HA was critical to recognition of this epitope by mAb P1-05, suggesting the importance of protein design for vaccine formulations. Overall, these data indicate that seasonally vaccinated individuals possess a population of functional H1 COBRA HA-reactive B cells that target head, central stalk, and anchor epitopes, and they demonstrate the importance of structure-based assessment of subunit protein vaccine candidates to ensure accessibility of optimal protein epitopes

Functional characterization of human COQ4, a gene required for Coenzyme Q10 biosynthesis

5 páginas, 3 figuras.Defects in genes involved in coenzyme Q (CoQ) biosynthesis cause primary CoQ deficiency, a severe multisystem disorders presenting as progressive encephalomyopathy and nephropathy. The COQ4 gene encodes an essential factor for biosynthesis in Saccharomyces cerevisiae. We have identified and cloned its human ortholog, COQ4, which is located on chromosome 9q34.13, and is transcribed into a 795 base-pair open reading frame, encoding a 265 amino acid (aa) protein (Isoform 1) with a predicted N-terminal mitochondrial targeting sequence. It shares 39% identity and 55% similarity with the yeast protein. Coq4 protein has no known enzymatic function, but may be a core component of multisubunit complex required for CoQ biosynthesis. The human transcript is detected in Northern blots as a approximately 1.4 kb single band and is expressed ubiquitously, but at high levels in liver, lung, and pancreas. Transcription initiates at multiple sites, located 333-23 nucleotides upstream of the ATG. A second group of transcripts originating inside intron 1 of the gene encodes a 241 aa protein, which lacks the mitochondrial targeting sequence (isoform 2). Expression of GFP-fusion proteins in HeLa cells confirmed that only isoform 1 is targeted to mitochondria. The functional significance of the second isoform is unknown. Human COQ4 isoform 1, expressed from a multicopy plasmid, efficiently restores both growth in glycerol, and CoQ content in COQ4(null) yeast strains. Human COQ4 is an interesting candidate gene for patients with isolated CoQ(10) deficiency.This work was supported by European Union contract #005151 UBIGENES and by Fondazione Città Della Speranza. Dr. Salviati is supported by Telethon Italy Grant GGP06256.Peer reviewe

Multifactorial Causes of Chronic Mortality in Juvenile Sturgeon (Huso huso)

This investigation focused on an episode of chronic mortality observed in juvenile Huso huso sturgeons. The examined subjects underwent pathological, microbiological, molecular, and chemical investigations. Grossly severe body shape deformities, epaxial muscle softening, and multifocal ulcerative dermatitis were the main observed findings. The more constant histopathologic findings were moderate to severe rarefaction and disorganization of the lymphohematopoietic lymphoid tissues, myofiber degeneration, atrophy and interstitial edema of skeletal epaxial muscles, and degeneration and atrophy of the gangliar neurons close to the myofibers. Chemical investigations showed a lower selenium concentration in affected animals, suggesting nutritional myopathy. Other manifestations were nephrocalcinosis and splenic vessel wall hyalinosis. Septicemia due to bacteria such as Aeromonas veronii, Shewanella putrefaciens, Citrobacter freundii, Chryseobacterium sp., and pigmented hyphae were found. No major sturgeon viral pathogens were detected by classical methods. Next-generation sequencing (NGS) analysis confirmed the absence of viral pathogens, with the exception of herpesvirus, at the order level; also, the presence of Aeromonas veronii and Shewanella putrefaciens was confirmed at the family level by the metagenomic classification of NGS data. In the absence of a primary yet undetected biological cause, it is supposed that environmental stressors, including nutritional imbalances, may have led to immune system impairment, facilitating the entry of opportunistic bacteria and mycotic hyphae

Migration Phenotype of Brain-Cancer Cells Predicts Patient Outcomes

SummaryGlioblastoma multiforme is a heterogeneous and infiltrative cancer with dismal prognosis. Studying the migratory behavior of tumor-derived cell populations can be informative, but it places a high premium on the precision of in vitro methods and the relevance of in vivo conditions. In particular, the analysis of 2D cell migration may not reflect invasion into 3D extracellular matrices in vivo. Here, we describe a method that allows time-resolved studies of primary cell migration with single-cell resolution on a fibrillar surface that closely mimics in vivo 3D migration. We used this platform to screen 14 patient-derived glioblastoma samples. We observed that the migratory phenotype of a subset of cells in response to platelet-derived growth factor was highly predictive of tumor location and recurrence in the clinic. Therefore, migratory phenotypic classifiers analyzed at the single-cell level in a patient-specific way can provide high diagnostic and prognostic value for invasive cancers