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Bruno Verhasselt

Publications and source records attributed to Bruno Verhasselt.

14 recordsLinked to original sources
PubMed2006

Lipoprotein lipase mRNA expression in whole blood is a prognostic marker in B cell chronic lymphocytic leukemia.

BACKGROUND: Chronic lymphocytic leukemia (CLL) is characterized by high individual variability in clinical course and the need for therapy. Differentiation of prognostic subgroups is based primarily on the mutation status of the genes for the variable region of the immunoglobulin heavy chain (IGHV). The time- and labor-intensive nature of this analysis necessitates the use of easily applicable surrogate markers. METHODS: We developed a quantitative PCR (qPCR) method for determining lipoprotein lipase (LPL) mRNA expression and analyzed samples of lysed whole blood and CD19-selected cells from 50 CLL patients. Associations of LPL and ZAP70 [zeta-chain (TCR) associated protein kinase 70 kDa] expression with IGHV mutation status, overall survival (OS), and treatment-free survival (TFS) were investigated. RESULTS: Lysed samples of whole blood and CD19-selected cells were similar with respect to LPL expression (R = 0.88; P <0.0001). LPL expression was significantly associated with IGHV mutation status [chi(2)(1) = 15.3; P <0.0001] and showed an 89.3% specificity, a 68.2% sensitivity, an 83.3% positive predictive value, and a 78.1% negative predictive value for IGHV mutation status. LPL expression was significantly associated with both OS and TFS in log-rank tests (both P values = 0.002). LPL-positive patients had a significantly shorter median TFS time (23 months) than LPL-negative patients (88 months) (P = 0.002). CONCLUSIONS: LPL mRNA expression is a valuable prognostic marker in CLL. The method does not require cell purification, and its applicability with archived samples facilitates its use in the clinical routine and other studies.

Adult↗
PubMed2006

Kolmogorov-Smirnov statistical test for analysis of ZAP-70 expression in B-CLL, compared with quantitative PCR and IgV(H) mutation status.

BACKGROUND: ZAP-70 has been proposed as a surrogate marker for immunoglobulin heavy-chain variable region (IgV(H)) mutation status, which is known as a prognostic marker in B-cell chronic lymphocytic leukemia (CLL). The flow cytometric analysis of ZAP-70 suffers from difficulties in standardization and interpretation. We applied the Kolmogorov-Smirnov (KS) statistical test to make analysis more straightforward. METHODS: We examined ZAP-70 expression by flow cytometry in 53 patients with CLL. Analysis was performed as initially described by Crespo et al. (New England J Med 2003; 348:1764-1775) and alternatively by application of the KS statistical test comparing T cells with B cells. Receiver-operating-characteristics (ROC)-curve analyses were performed to determine the optimal cut-off values for ZAP-70 measured by the two approaches. ZAP-70 protein expression was compared with ZAP-70 mRNA expression measured by a quantitative PCR (qPCR) and with the IgV(H) mutation status. RESULTS: Both flow cytometric analyses correlated well with the molecular technique and proved to be of equal value in predicting the IgV(H) mutation status. Applying the KS test is reproducible, simple, straightforward, and overcomes a number of difficulties encountered in the Crespo-method. CONCLUSIONS: The KS statistical test is an essential part of the software delivered with modern routine analytical flow cytometers and is well suited for analysis of ZAP-70 expression in CLL.

Adult↗
PubMed2006

EBV negative Richter's syndrome from a coexistent clone after salvage treatment with alemtuzumab in a CLL patient.

Transformation of B cell chronic lymphocytic leukemia (B-CLL) to large cell lymphoma or Hodgkin's disease is known as a Richter's syndrome (RS). According to the literature, 1-10% of B-CLL patients develop this high-grade lymphoid malignancy. The relationship between the immunosuppressive effect of nucleoside analogues (NA) and monoclonal antibodies and the development of large cell transformation still remains a controversial issue. We describe a CLL patient who developed a large B cell lymphoma 94 months after diagnosis and 3 months after the start of alemtuzumab. The CLL immunophenotype was retained by the transforming cells although a different light chain was expressed. Molecular analysis of the immunoglobulin heavy chain confirmed that the CLL and the RS had a different clonal origin. Subsequent molecular analyses of stored samples showed that the clone with transforming capacity already appeared two years before the clinical appearance of the RS. We hypothesize that alemtuzumab promoted the uncontrolled growth of the latest clone by eradicating the initial B-CLL clone efficiently, and by inducing a strong T cell depletion with consequent impairment of the immunosurveillance. We also ruled out that the RS was EBV driven. In conclusion, we report a case of EBV negative RS after alemtuzumab as salvage therapy.

Alemtuzumab↗
PubMed2006

Modelling thymic HIV-1 Nef effects.

The nef gene is conserved among primate lentiviruses and is one of the first viral genes that is transcribed following infection. This suggests a critical role for Nef in the virus life cycle and in the pathogenesis of lentiviral infections. In vitro, several functions have been described, including down regulation of CD4 and MHC class I surface expression, altered T-cell signaling and activation, and enhanced viral infectivity. However, the impact of these individual functions on viral pathogenicity in general, and thymic T cell production in particular, remains elusive. Here, we review the observations from experimental models that have been used to study the pathogenic effect of HIV-1 Nef on the thymus. These in vitro and in vivo studies have led to a better understanding of Nef's mechanism of action, although there still exists discord as to the contribution of Nef-mediated disturbance of thymopoiesis in the pathogenesis of AIDS.

Animals↗
PubMed2005

Vitamin D binding protein, bone status and body composition in community-dwelling elderly men.

The vitamin D binding protein (DBP) is the major carrier protein for vitamin D metabolites in plasma. Polymorphisms in DBP have been described to be associated with an increased bone fracture risk and diabetes. The present study investigates the influence of both phenotypic and (TAAA)(n)-Alu repeat DBP-polymorphism and DBP-concentration on bone mineral density, body composition, bone turnover- and metabolic markers in a cohort of ambulatory elderly men. We included 211 men (>70 years) in this study. Bone mineral density (BMD) was determined by dual energy X-ray absorptiometry. Bone turnover was assessed by measurement of serum osteocalcin, serum and urinary C-terminal telopeptides of type I collagen and urinary deoxypyridinoline, together with 25(OH)-vitamin D and 1,25(OH)(2)-vitamin D concentrations. DBP-phenotypes were determined electrophoretically and the (TAAA)(n)-Alu repeat polymorphism was determined by polymerase chain reaction. Body composition was estimated using bioelectrical impedance analysis, together with handgrip and arm strength, fasting serum glucose and leptin concentrations. No differences in BMD or bone turnover markers among DBP-phenotypes or (TAAA)(n)-genotypes were observed in this study. Serum 25(OH)-vitamin D was comparable among DBP-variants and did not relate to DBP-concentrations, whereas 1,25(OH)(2)-vitamin D was different among DBP-phenotypes and was correlated positively with DBP-concentrations. DBP-concentrations related positively to body mass index, fat mass, leptin and glucose concentration. The correlation with leptin remained significant after correction for fat mass. Fasting glucose concentrations were different among DBP-phenotypes, whereas no difference was observed between (TAAA)(n)-genotypes. In conclusion, serum 1,25(OH)(2)-vitamin D concentrations are codetermined by DBP-phenotypes and DBP-concentrations. No major effect of DBP-polymorphism was demonstrated on BMD, bone turnover markers or body composition.

Absorptiometry, Photon↗
PubMed2005

Human immunodeficiency virus Nef induces rapid internalization of the T-cell coreceptor CD8alphabeta.

Human immunodeficiency virus (HIV) Nef is a membrane-associated protein decreasing surface expression of CD4, CD28, and major histocompatibility complex class I on infected cells. We report that Nef strongly down-modulates surface expression of the beta-chain of the CD8alphabeta receptor by accelerated endocytosis, while CD8 alpha-chain expression is less affected. By mutational analysis of the cytoplasmic tail of the CD8 beta-chain, an FMK amino acid motif was shown to be critical for Nef-induced endocytosis. Although independent of CD4, endocytosis of the CD8 beta-chain was abrogated by the same mutations in Nef that affect CD4 down-regulation, suggesting common molecular interactions. The ability to down-regulate the human CD8 beta-chain was conserved in HIV-1, HIV-2, and simian immunodeficiency virus SIVmac239 Nef and required an intact AP-2 complex. The Nef-mediated internalization of receptors, such as CD4, major histocompatibility complex class I, CD28, and CD8alphabeta, may contribute to the subversion of the host immune system and progression towards AIDS.

Alleles↗
PubMed2005

Novel cryptic chromosomal rearrangements in childhood acute lymphoblastic leukemia detected by multiple color fluorescent in situ hybridization.

BACKGROUND AND OBJECTIVES: It is often difficult to obtain good karyotypes of cells from children with acute lymphoblastic leukemia (ALL) because of poor morphology and spreading. Detailed karyotyping can be further hampered by the presence of multiple rearrangements. Our objective was to search for cryptic rearrangements in childhood ALL. DESIGN AND METHODS: A series of eight cases of childhood ALL with at least two structural defects were selected and studied by multiple color fluorescent in situ hybridization (M-FISH). RESULTS: Four previously not reported translocations were detected: a t(14;20) (q32;q11.2) in a 3-year old girl with T-ALL, a cryptic t(7;11)(q35;q24) in association with a t(1;14)(p32;q32) in a patient with T-ALL and two translocations possibly involving the same 6q26 region on the distal end of the long arm of chromosome 6. Further FISH analysis on the t(7;11) indicated rearrangement of the TCRB locus at 7q35 suggesting that this t(7;11) leads to overexpression of an as yet unidentified gene at 11q24. This observation also triggered further screening for TCRB rearrangements in T-ALL. FISH analysis of the t(14;20) with an IGH locus-specific probe provided evidence for an unusual rearrangement of the IGH gene, in the variable gene segment region. Finally, we also observed cryptic insertions of AF4 and ETV6 in combination with complex rearrangements, leading to MLL/AF4 and ETV6/RUNX1 gene fusions. INTERPRETATION AND CONCLUSIONS: This study underscores the importance and power of M-FISH analysis in unraveling complex karyotypes and identifying cryptic chromosomal rearrangements. It also sheds some light on the implication of cryptic TCRB rearrangements in T-ALL.

Adolescent↗
PubMed2003

Signaling but not trafficking function of HIV-1 protein Nef is essential for Nef-induced defects in human intrathymic T-cell development.

The HIV-1 gene nef is important for progression toward AIDS and cellular depletion of the infected thymus. Expression of the Nef protein alone impairs human thymopoiesis. Here, we performed a structure-function analysis of the Nef protein by comparing the effect on T-cell development of different nef alleles, either wild type or defective for selected functions, expressed by human thymocytes. We show that Nef-mediated impaired thymopoiesis is not due to altered surface marker trafficking, nor dependent on oligomerization of Nef. By contrast, mutations in the myristoylation site and in signaling sites of Nef, ie, sites important for interaction with phosphofurin acidic cluster sorting protein-1 (PACS-1), Src homology domain 3 (SH3) domains, and p21-activated kinase 2 (PAK2), were found to be critical for its effect on T-cell development. These results point to sites in Nef to target therapeutically for restoration of thymopoiesis in HIV infection.

Alleles↗
PubMed2003

ALK activation by the CLTC-ALK fusion is a recurrent event in large B-cell lymphoma.

We present 3 cases of large B-cell lymphoma (LBCL) with a granular cytoplasmic staining for anaplastic lymphoma kinase (ALK). All of the cases showed striking similarities in morphology and immunohistochemical profile characterized by a massive monomorphic proliferation of CD20-/CD138+ plasmablast-like cells. In one of the cases, initially diagnosed as a null-type anaplastic large cell lymphoma (ALCL), the B-cell phenotype became evident only at recurrence. Fluorescent in situ hybridization (FISH) and molecular studies led to the detection of a CLTC-ALK rearrangement in all 3 cases, without any evidence of full-length ALK receptor expression. The associated t(2;17)(p23;q23) was demonstrated in the karyotype of 2 cases. Although a similar CLTC-ALK aberration was previously identified in ALK-positive T-/null cell ALCL and inflammatory myofibroblastic tumor, its association with ALK-positive LBCL seems to be specific and intriguing.

Adolescent↗
PubMed2002

Active form of Notch imposes T cell fate in human progenitor cells.

The crucial role of Notch signaling in cell fate decisions in hematopoietic lineage and T lymphocyte development has been well established in mice. Overexpression of the intracellular domain of Notch mediates signal transduction of the protein. By retroviral transduction of this constitutively active truncated intracellular domain in human CD34+ umbilical cord blood progenitor cells, we were able to show that, in coculture with the stromal MS-5 cell line, depending on the cytokines added, the differentiation toward CD19+ B lymphocytes was blocked, the differentiation toward CD14+ monocytes was inhibited, and the differentiation toward CD56+ NK cells was favored. The number of CD7+cyCD3+ cells, a phenotype similar to T/NK progenitor cells, was also markedly increased. In fetal thymus organ culture, transduced CD34+ progenitor cells from umbilical cord blood cells or from thymus consistently generated more TCR-gammadelta T cells, whereas the other T cell subpopulations were largely unaffected. Interestingly, when injected in vivo in SCID-nonobese diabetic mice, the transduced cells generated ectopically human CD4+CD8+ TCR-alphabeta cells in the bone marrow, cells that are normally only present in the thymus, and lacked B cell differentiation potential. Our results show unequivocally that, in human, Notch signaling inhibits the monocyte and B cell fate, promotes the T cell fate, and alters the normal T cell differentiation pathway compatible with a pretumoral state.

Animals↗
PubMed2002

Identification of biologically active chemokine isoforms from ascitic fluid and elevated levels of CCL18/pulmonary and activation-regulated chemokine in ovarian carcinoma.

Chemokines are important in leukocyte homeostasis, inflammation, angiogenesis, and metastasis. Here, the molecular diversity of chemokines present in ovarian carcinoma was studied by purifying the proteins to homogeneity from ascitic fluid. Biologically active intact CCL2 and processed CXCL8, CCL3, and CCL18 isoforms were recovered. CCL7 and CCL20 were also purified, but their levels were 10-fold lower compared with CXCL8, CCL2, and CCL3 and even 100-fold lower than the amounts of CCL18 isolated. In ascitic fluids from patients with ovarian carcinoma (n = 12), significantly higher levels of CXCL8 and CCL18 (2.0 versus 0.7 ng/ml (p = 0.01) and 120 versus 44 ng/ml (p = 0.0002), respectively) were detected compared with those in nonovarian carcinoma patients (n = 12). In contrast to CXCL8, CCL18 was not inducible in carcinoma cell lines. Immunostaining showed CCL18 expression in tumor-infiltrating cells with monocyte/macrophage morphology but not in the ovarian carcinoma cells. Our data demonstrate that biochemically heterogenous but biologically active forms of several chemokines are present at different concentrations in ovarian carcinoma ascitic fluid. This points to a delicate balance of chemokines in epithelial ovarian cancer and to a potentially major role for CXCL8 and CCL18 in this tumor.

Ascites↗
PubMed2002

HOX-A10 regulates hematopoietic lineage commitment: evidence for a monocyte-specific transcription factor.

Homeobox genes are well known for their crucial role during embryogenesis but have also been found to be critically involved in normal and leukemic hematopoiesis. Because most previous studies focused on the role of aberrant HOX gene expression in leukemogenesis and because HOX-A10 is expressed in human CD34(+) precursor cells, this study investigated whether HOX-A10 also plays a pivotal role in normal hematopoietic-lineage determination. The effect of enforced expression of this transcription factor on hematopoietic differentiation of highly purified human cord-blood progenitors was examined by using in vitro assays. In fetal thymic organ cultures, a dramatic reduction in cells expressing high levels of HOX-A10 was observed, along with absence of thymocytes positive for CD3(+) T-cell receptor alphabeta. Furthermore, in MS-5 stromal cell cultures, there was a 7-fold reduction in the number of natural killer cells and a 9-fold reduction in the number of B cells, thus showing a profound defect in differentiation toward the lymphoid lineage in HOX-A10-transduced progenitors. In contrast, the number of CD14(+) monocytic cells in the stromal cell culture was 6-fold higher, suggesting an enhanced differentiation toward the myeloid differentiation pathway of HOX-A10-transduced progenitors. However, there was a slight reduction in the number of CD15(+) granulocytic cells, which were blocked in their final maturation. These data show that HOX-A10 can act as an important key regulator of lineage determination in human hematopoietic progenitor cells.

Animals↗