References of "Heinen, Ernst"
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See detailDendritic cells: potential actors in prion neuroinvasion.
Dorban, G.; Lallemand, C.; Defaweux, Valérie ULg et al

Poster (2006, September)

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See detailStudy on the toxic mechanism of prion protein peptide 106-126 in neuronal and non neuronal cells
Dupiereux-Fettweis, Ingrid ULg; Zorzi, Willy ULg; Rachidi, W. et al

in Journal of Neuroscience Research (2006), 84(3), 637-646

A synthetic peptide corresponding to the 106-126 amyloidogenic region of the cellular human prion protein (PrPc) is useful for in vitro study of prion-induced neuronal cell death. The aim of the present ... [more ▼]

A synthetic peptide corresponding to the 106-126 amyloidogenic region of the cellular human prion protein (PrPc) is useful for in vitro study of prion-induced neuronal cell death. The aim of the present work was to examine the implication of the cellular prion protein in the toxicity mechanism induced by PrP 106-126. The effect of PrP 106-126 was investigated both on human neuroblastoma SH-SY5Y cells and on SH-SY5Y over-expressing murine cellular prions (wtPrP). We show by metabolic assay tests and ATP assays that PrPc expression does not modulate the toxicity of the prion peptide. Moreover, we investigated the effect of this peptide on an established non neuronal model, rabbit kidney epithelial A74 cells that express a doxycycline-inducible murine PrPc gene. We show for the first time that the prion peptide 106-126 does not exert any toxic effect on this cell line in the presence or absence of doxycycline. Our results show that the PrP 106-126-induced cell alteration is independent of PrPc expression. Rather, it seems to act via an interaction with lipidic components of the plasma membrane as strengthened by our results showing the differential susceptibility of neuronal and non neuronal cell lines that significantly differ by their membrane fatty acid composition. (c) 2006 Wiley-Liss, Inc. [less ▲]

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See detailLa tremblante du mouton influence-t-elle le système immunitaire lors d’une réponse vis-à-vis d’un antigène
Defaweux, Valérie ULg; Dorban, G.; Demonceau, C. et al

Conference (2005, November)

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See detailL'infection par les prions pathogènes modifie l'expression menbranaire de la PrPc par les cellules dendritiques
Dorban, G; Demonceau,C; Levavasseur, E et al

Poster (2005, October)

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See detailCharacterization of bovine and human cellular prion protein expressed in the central nervous system and in lymphoid organs.
Defaweux, Valérie ULg; Stramiello, Sara; Capellari, Sabina et al

Poster (2005, October)

Prion cell tropism varies significantly among animal species, depending on both the agent strain and host-specific factors. For example, prions show high lymphotropism in scrapie infected sheep and vCJD ... [more ▼]

Prion cell tropism varies significantly among animal species, depending on both the agent strain and host-specific factors. For example, prions show high lymphotropism in scrapie infected sheep and vCJD, but little, if any, in sCJD or BSE. In particular, the BSE strain is associate with significant PrP-res accumulation in tonsils, spleen and appendix in humans, whereas, it is largely confined to the nervous system in infected cattle. So, it appears that, at least in the case of BSE and vCJD, host properties can influence the accumulation of the infectious agent in lymphoid organs. Given that the normal cellular prion protein (PrPC), is sine qua non for PrP-res formation and the development of TSE, it appears reasonable to hypothesize that tissue-specific PrPC properties may represent one of the host factors influencing the cell tropism of the infectious agent in human or bovine. We applied a western blot analyses to compare the relative percentage of the di-, mono- and unglycosylated PrPC (the so called glycoform ratio) as well as the expression of truncated PrPC forms in tissues from the central nervous system and lymphoid structures (lymphoid follicles, lymphocytes and follicular dendritic cells) of both bovine and human. We found that PrPC glycoform ratio is significantly different between cerebellum and medulla in both bovine and human. Moreover, the expression of truncated forms of PrPC (i.e. 21 and 18 kDa PrPC) was also significantly heterogenous according to the brain region investigated. PrPC was highly glycosylated in spleen and lymphoid follicles isolated from bovine tonsils, mesenteric lymph nodes, ileal and jejunal Peyer’s patches. After deglycosylation, a novel PrPC truncated form with a relative molecular mass of about 25 kDa was detected in bovine lymphoid organs beside the typical 18 and 21 kDa forms. No difference in WB PrPC profile was seen in human lymphocytes extracted either from spleen or tonsil. Our results highlight variation in the profile expression of PrPC in peripheral and central tissues of bovine and human. Such differences may have an implication for PrPC function or may represent critical factors influencing the accumulation of the infectious agent in these areas. Supported by the EU contract QLG3-CT-2002-81030. [less ▲]

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See detailImplication of Peyer’s patches dendritic cells in prion diseases.
Dorban, G.; Defaweux, Valérie ULg; Demonceau, C. et al

Poster (2005, June)

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See detailLymphotoxin-beta receptor-dependent genes in lymph node and follicular dendritic cell transcriptomes
Huber, Christoph; Thielen, Caroline ULg; Seeger, Harald et al

in Journal of Immunology (2005), 174(9), 5526-5536

Affinity-maturation and Ab class switches occur in lymphoid germinal centers (GCs), in which differentiation and maintenance depend on lymphotoxin (LT) signaling and include differentiation of follicular ... [more ▼]

Affinity-maturation and Ab class switches occur in lymphoid germinal centers (GCs), in which differentiation and maintenance depend on lymphotoxin (LT) signaling and include differentiation of follicular dendritic cells (FDCs). The events leading to FDC and GC maturation are poorly defined. Using several approaches of functional genomics, we enumerated transcripts affected in mice by suppressing LT beta receptor (LT beta R) signaling and/or overrepresented in FDC-enriched GC isolates. Protein expression analysis of 3 of 12 genes both enriched in FDCs and down-regulated by LT beta R signaling suppression validated them as FDC markers. Functional analysis of one of these three, clusterin, suggests a role as an FDC-derived trophic factor for GC B cells. Hence, the set of genes presented in this study includes markers emanating from LT beta R signaling and transcripts relevant to GC and FDC function. [less ▲]

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See detailInvestigation of germinal centres in vivo and in vitro in the context of prion disease
Demonceau, C.; Defaweux, Valérie ULg; Flandroy, S. et al

Poster (2005, April)

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See detailCellular and nervous environment of mouse mesenteric lymph node germinal centres
Wenders, Frédéric ULg; Dorban, G.; Piret, Joëlle ULg et al

Conference (2005, April)

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See detailFollicular dendritic cells innervation within spleen of five mouse strains with different incubation periods after intraperitoneal BSE inoculation.
Demonceau, C.; Marshall, A.; Sales, J. et al

Poster (2005, February)

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See detailFollicular dendritic cells related to nerve fibres and cellular prion protein expression in ileal and jejunal Peyer’s patches of cows and calves
Defaweux, Valérie ULg; Antoine, Nadine ULg; Dorban, G. et al

Poster (2005, February)

Prion pathogenesis following oral exposure is thought to involve gut-associated lymphoid tissue, which includes Peyer’s patches (PP). Before neuroinvasion, early accumulation of infectious prion protein ... [more ▼]

Prion pathogenesis following oral exposure is thought to involve gut-associated lymphoid tissue, which includes Peyer’s patches (PP). Before neuroinvasion, early accumulation of infectious prion protein (PrPsc) takes place on follicular dendritic cells (FDC) which are resident cells in germinal centres. The strain, the infection pathway and the lesions in the central nervous system are similar between bovine spongiform encephalopathy (BSE) and variant Creutzfeldt Jakob diseases. But in BSE, the agent tropism differs from lymphoid organs. Only bovine ileal PP are infectious. In order to study the replication and the possible ways of neuroinvasion of PrPsc in bovine PP, we studies the expression of cellular prion protein (PrPc), necessary for PrPsc accumulation, and compared the innervation of germinal centres related to FDC on ileal and jejunal PP of cows and calves. We performed classical immunoperoxydase staining and double immunofluorescence staining analyzed with a confocal microscopy. Differences in the innervation of germinal centres and expression of PrPc were evident. More contacts between FDC and nerve fibres are observed in calves PP. PrPc expression, carried out with different anti-PrPc antibodies, highlighted a heterogeneous labelling between calves and cows PP. Such results permit us to show that the innervation of PP is a dynamic process which could influence the first way of neuroinvasion in prion diseases. Moreover differences in the affinity of some antibody for PrPc allow us to postulate that PrPc glycoforms differ with age of bovines and thus could interfere with PrPsc tropism. [less ▲]

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See detailInterfaces between dendritic cells, other immune cells, and nerve fibres in mouse Peyer's patches: Potential sites for neuroinvasion in prion diseases
Defaweux, Valérie ULg; Dorban, Gauthier ULg; Demonceau, Christine ULg et al

in Microscopy Research and Technique (2005), 66(1), 1-9

In this study, we examined where immune cells and nerve fibres are located in mouse Peyer's patches, with a view to identifying potential sites for neuroinvasion by prions. Special attention was paid to ... [more ▼]

In this study, we examined where immune cells and nerve fibres are located in mouse Peyer's patches, with a view to identifying potential sites for neuroinvasion by prions. Special attention was paid to dendritic cells, viewed as candidate transporters of infectious prion. Double immunofluorescence labellings with anti-CD11c antibody and marker for other immune cells (B cells, T cells, follicular dendritic cells) were carried out and analysed by confocal microscopy on Peyer's patch cryosections. To reveal the extensive ganglionated networks of the myenteric and submucosal plexi and the sparse meshworks of nerve strands, we used antibodies directed against different neurofilament subunits or against glial fibrillary acidic protein. In the suprafollicular dome, dendritic cells connect, via their cytoplasmic extensions, enterocytes with M cells of the follicle-associated epithelium. They are also close to B and T cells. Nerve fibres are detected in the suprafollicular dome, notably in contact with dendritic cells. Similar connections between dendritic cells, T cells, and nerve fibres are seen in the interfollicular region. Germinal centres are not innervated; inside them dendritic cells establish contacts with follicular dendritic cells and with B cells. After immunolabelling of normal prion protein, dendritic cells of the suprafollicular dome are intensely positive labelled. (c) 2005 Wiley-Liss, Inc. [less ▲]

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See detailImmunoquantitative PCR for prion protein detection in sporadic Creutzfeldt-Jakob disease.
Gofflot, Stéphanie ULg; Deprez, Manuel ULg; Elmoualij, Benaïssa ULg et al

in Clinical Chemistry (2005), 51(9), 1605-11

BACKGROUND: The most common human prion disorder is Creutzfeldt-Jakob disease (CJD); it includes sporadic, familial, iatrogenic, and variant subtypes. Diagnostic tests aim at detection with the highest ... [more ▼]

BACKGROUND: The most common human prion disorder is Creutzfeldt-Jakob disease (CJD); it includes sporadic, familial, iatrogenic, and variant subtypes. Diagnostic tests aim at detection with the highest specificity of very small deposits of abnormal prion protein (PrP). METHODS: We used immunoquantitative PCR (iqPCR) to detect proteinase K-resistant PrP (PrPRes) in tissue from the middle frontal gyrus of 7 patients with sporadic CJD and 7 non-CJD cases. We compared iqPCR with routine optimized ELISA, Western blotting, and immunohistochemical analyses. RESULTS: The 4 methods showed similar 100% sensitivity and specificity for the diagnosis of CJD. Along with high specificity, however, iqPCR had a threshold for PrP(Res) detection at least 10-fold lower than that of the classic ELISA. CONCLUSIONS: iqPCR is a new method for PrPRes detection that combines 100% specificity with a detection threshold at least 10-fold lower than classic techniques. This method may improve the detection of minute PrPRes deposits in tissues and body fluids and thus be useful for diagnostic and sterilization applications. [less ▲]

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See detailInteraction of the 106-126 prion peptide with lipid membranes and potential implication for neurotoxicity.
Dupiereux-Fettweis, Ingrid ULg; Zorzi, Willy ULg; Lins, Laurence ULg et al

in Biochemical and Biophysical Research Communications (2005), 331(4), 894-901

Prion diseases are fatal neurodegenerative disorders characterized by the accumulation in the brain of an abnormally misfolded, protease-resistant, and beta-sheet rich pathogenic isoform (PrP(SC)) of the ... [more ▼]

Prion diseases are fatal neurodegenerative disorders characterized by the accumulation in the brain of an abnormally misfolded, protease-resistant, and beta-sheet rich pathogenic isoform (PrP(SC)) of the cellular prion protein (PrP(C)). In the present work, we were interested to study the mode of prion protein interaction with the membrane using the 106-126 peptide and small unilamellar lipid vesicles as model. As previously demonstrated, we showed by MTS assay that PrP 106-126 induces alterations in the human neuroblastoma SH-SY5Y cell line. We demonstrated for the first time by lipid-mixing assay and by the liposome vesicle leakage test that PrP 106-126, a non-tilted peptide, induces liposome fusion thus a potential cell membrane destabilization, as supported by membrane integrity assay (LDH). By circular dichroism (CD) analysis we showed that the fusogenic property of PrP 106-126 in the presence of liposome is associated with a predominantly beta-sheet structure. These data suggest that the fusogenic property associated with a predominant beta-sheet structure exhibited by the prion peptides contributes to the neurotoxicity of these peptides by destabilizing cellular membranes. The latter might be attached at the membrane surface in a parallel orientation as shown by molecular modeling. [less ▲]

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See detailDiscrimination self/non-self
Heinen, Ernst ULg

in Encyclopedia of Life Sciences (2005)

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See detailGerminal center
Thielen, C.; Heinen, Ernst ULg

in Encyclopedia of Life Sciences (2005)

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See detailDetection of biomarkers of pathogenic bacteria by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry
Ruelle, Virginie; El Moualij, B.; Zorzi, Willy ULg et al

in Lichtfouse, Eric; Schwarzbauer, Jan; Robert, Didier (Eds.) Environmental Chemistry : Green Chemistry and Pollutants in Ecosystems (2005)

In recent years, various mass spectrometry procedures has been developed for identifying bacteria. The accuracy and speed with which data can be obtained by Matrix-assisted laser Desorption/Ionization ... [more ▼]

In recent years, various mass spectrometry procedures has been developed for identifying bacteria. The accuracy and speed with which data can be obtained by Matrix-assisted laser Desorption/Ionization Time-of-flight Mass Spectrometry (MALDI-TOF-MS) make this an advantageous technique for environmental monitoring. However, minor variations in the sample preparation can influence the mass spectra significantly. In the present study, we have introduced a procedure to prepare bacteria by microextraction and we have optimized experimental parameters for rapid identification by MALDI-TOF-MS of whole bacterial cells isolated from environmental samples such as wastewater and soil. [less ▲]

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