Virginie Buhé

Université de Bretagne Occidentale, Brest, Brittany, France

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Publications (7)32.46 Total impact

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    ABSTRACT: The factor H (FH) protein (also known as beta1H globulin) is the main regulator of the complement alternative pathway. It exhibits multivalent binding sites to the complement component C3b, and polyanions and one binding site to sialic acid and cell surfaces. These multiple binding sites confer to FH a decay-accelerating factor activity in the fluid phase as well as at the cell surface. A defect in FH activity or a FH protein deficiency triggers chronic inflammation and tissue injury, leading to various disorders impacting the kidney or the eye. In contrast, some pathogens, as well as cancer cells, develop various strategies to bind FH and thereby subvert a complement attack. We focus on the functions of FH, and review the main pathological conditions in which FH is involved. Since the pathogenesis is elusive, appropriate FH dosage in biological fluids and FH gene analysis may help in improving understanding of such diseases.
    International journal of immunopathology and pharmacology 01/2010; 23(2):397-404. · 2.99 Impact Factor
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    ABSTRACT: The anti-CD20 monoclonal antibody rituximab (RTX) has been applied to the therapy of B-cell proliferative disease, but a number of factors, such as the expression level of its target antigen, modulate its efficacy. Since unmethylated CpG-containing DNA sequences activate members of the immune systems, including B lymphocytes, their benefit to RTX treatment was determined on human lymphoma B-cell line cells. These Daudi cells expressed high endosomal level of the CpG Toll-like receptor 9, but CpG had effects neither on the viability, nor on the proliferation of the cells. In contrast, there appeared to be an increase in the expression of CD20, resulting in a higher efficiency of RTX for the killing of malignant Daudi cells.
    Annals of the New York Academy of Sciences 09/2009; 1173:858-64. · 4.38 Impact Factor
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    ABSTRACT: Lipopolysaccharide (LPS), CpG-containing phosphothioate oligonucleotides (CpG) and various cytokines impact chronic lymphocytic leukemia (CLL) B cells. For example, they influence cell cycle entry, expression of co-receptors, and CD20. Rituximab (RTX), for which CD20 molecule is the target, proved to be less efficient in CLL than in lymphoma. This is accounted for by a lower CD20 level in the former than in the latter B lymphocytes. CD20 transcription is mediated by four transcription factors, of which only purine-rich box-1 (PU.1) is reduced in CLL. We thus examined the effects of LPS, CpG, tumor necrosis factor-alpha, interferon-alpha, interleukin (IL)-3, IL-4, IL-21, granulocyte macrophage-colony stimulating factor (CSF), and granulocyte-CSF on the transcription of PU.1, and the subsequent expression of CD20. It appeared that CpG was unique in that it raised the membrane expression of CD20 on malignant B cells, owing to a PU.1 independent increase in its gene transcription. Moreover, RTX-induced complement-mediated lysis was also ameliorated. Thus, CpG accelerates the transcription of CD20 independently of PU.1, and thereby improves the efficacy of RTX in CLL.
    Annals of the New York Academy of Sciences 09/2009; 1173:721-8. · 4.38 Impact Factor
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    ABSTRACT: As a model to dissect the effects of CpG-oligonucleotides (CpG) on rituximab (RTX)-mediated therapeutic killing of autoimmune or malignant B lymphocytes, nude mice were grafted with Daudi human B cells. These mice were then injected with RTX alone or together with CpG. The human B cell aggregate was measured, and the reactive infiltrate analyzed after selective depletion of murine circulating cells. Macrophages (MØ) were identified in infiltrates, but not polymorphonuclear neutrophils (PMN), as confirmed by the failure of quantitative polymerase chain reaction to detect transcripts for PMN-specific myeloperoxidase in graft extracts. Evidence that MØ predominate over PMN in the anti-B cell RTX-induced immune mechanisms, include the presence of MØ-derived cytokines, and the lack of consequences of depletion of NK cells or B lymphocytes on the CpG-mediated effects on RTX. Interestingly however, removal of circulating PMN reduced the number of MØ attracted by the Daudi B cells. Our interpretation that CpG-induced complement activation is required for PMN to influence MØ was first based on overproduction of C5a in treated mice. This excess was due to the binding of the inhibitor of the alternative pathway of complement to CpG, as demonstrated by the elution of factor H from CpG-affinity-chromatography columns. Thus MØ are recruited to the tissue in the presence of C5a, and exploited locally by RTX.
    Journal of Autoimmunity 09/2009; 34(2):136-44. · 8.15 Impact Factor
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    ABSTRACT: Chronic lymphocytic leukemia (CLL) is characterized by survival advantage and accumulation of CD5+ mature B lymphocytes. Expression of zeta-chain-associated protein-70 (ZAP-70), normally present in T lymphocytes or immature B cells, is associated with disease aggressiveness, as IgVH mutational status, and some proteins implicated in survival signal pathways are found to be constitutively activated in CLL cells. ZAP-70 signaling is regulated through molecular adaptors, such as the proto-oncogene product c-Casitas B lineage lymphoma (c-Cbl). The aim of this study was to determine the implication of this proto-oncogene product in CLL in survival signals. It appeared that expression of c-Cbl was increased in CLL and not correlated to that of B cell linker protein or ZAP-70. Furthermore, c-Cbl was significantly hypophosphorylated in progressive disease, so that hypophosphorylated form of c-Cbl (c-Cbl.P) along with ZAP-70, set a cutoff ratio distributing patients with stable situation below 1, and those with progressive disease equal or above 1. Given that phospholipase gamma 2 (PLC gamma 2) function is also influenced by c-Cbl hypophosphorylation, the ratio of PLC gamma 2 to c-Cbl.P was measured in CLL B cells and consistently found to be >or= 1 in Binet stage B CLL patients, as opposed to stage A CLL patients. These findings invite analysis of the role of c-Cbl in CLL.
    Annals of the New York Academy of Sciences 06/2007; 1107:193-205. · 4.38 Impact Factor
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    ABSTRACT: Glioblastoma multiform (GBM) remains the most devastating primary tumour in neuro-oncology. Human Epithelial Receptor Type 2 (HER2) is a transmembrane tyrosine/kinase receptor that is important for cancer growth. HER2 is not expressed in adult glial cells, but its expression increases with the degree of astrocytomas anaplasia. We have recently demonstrated the ability of anti-HER2 antibodies to induce in vitro apoptosis GBM cell lines; this ability is correlated to HER2 density. A decreasing of tyrosine/kinase receptors density during in vitro culture was reported. No information exists about the variation of HER2 expression after in vivo implantation. For that, the two cell lines in vitro tested (U251MG, A172) were in vivo implanted. We established a U251MG in vivo model in balb/c nude mice showing an important increasing of HER2 density. The HER2 density is correlated to anti-HER2 antibody efficiency so this model will be useful for the evaluation of in vivo anti-HER2 antibody treatment.
    Journal of Neuro-Oncology 03/2006; 76(3):249-55. · 3.12 Impact Factor
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    ABSTRACT: Glioblastoma multiforme (GBM) remains the most devastating primary tumour in neuro-oncology. Targeting of the human epithelial receptor type 2 (HER2)-neu receptor by specific antibodies is a recent well-established therapy for breast tumours. Human epithelial receptor type 2/neu is a transmembrane tyrosine/kinase receptor that appears to be important for the regulation of cancer growth. Human epithelial receptor type 2/neu is not expressed in the adult central nervous system, but its expression increases with the degree of astrocytoma anaplasia. The specificity of HER2/neu for tumoral astrocytomas leads us to study in vitro treatment of GBM with anti-HER2/neu antibody. We used human GBM cell lines expressing HER2/neu (A172 express HER2/neu more than U251MG) or not (U87MG) and monoclonal humanised antibody against HER2/neu (Herceptin). Human epithelial receptor type 2/neu expression was measured by immunohistochemistry and flow cytometry. Direct antibody effect, complement-dependent cytotoxicity and antibody-dependent cellular cytotoxicity were evaluated by different cytometric assays. We have shown, for the first time, the ability of anti-HER2/neu antibodies to induce apoptosis and cellular-dependent cytotoxicity of HER2/neu-expressing GBM cell lines. The results decreased from A172 to U251 and were negative for U87MG, in accordance with the decreasing density of HER2/neu receptors.
    British Journal of Cancer 10/2004; 91(6):1195-9. · 5.08 Impact Factor