[show abstract][hide abstract] ABSTRACT: GALIG gene expression induces apoptosis in cultured cells through a pathway still under investigation. It is highly expressed in leukocytes but weakly detectable in bone marrow, suggesting a role in the myeloid lineage homeostasis. We show here that GALIG-induced cell death is counteracted by the overexpression of MCL-1, a pro-survival member of the Bcl2 family. Moreover, during spontaneous neutrophil apoptosis, a substantial increase in GALIG gene expression is observed: GALIG still opposes MCL-1. Finally, in bone marrow and peripheral blood cells from patients with Acute Myeloid Leukemia type 2, the level of GALIG transcripts is massively down-regulated when compared to their normal counterparts, while MCL-1 is expressed to the same extent. These data suggest that GALIG could be a key player in the cell death pathway involved in leukocytes homeostasis and myeloid malignancies.
[show abstract][hide abstract] ABSTRACT: Dehydrated hereditary stomatocytosis is a genetic condition with defective red blood cell membrane properties that causes an imbalance in intracellular cation concentrations. Recently, two missense mutations in the mechanically activated PIEZO1 (FAM38A) ion channel were associated with dehydrated hereditary stomatocytosis. However, it is not known how these mutations affect PIEZO1 function. Here, by combining linkage analysis and whole-exome sequencing in a large pedigree and Sanger sequencing in two additional kindreds and 11 unrelated dehydrated hereditary stomatocytosis cases, we identify three novel missense mutations and one recurrent duplication in PIEZO1, demonstrating that it is the major gene for dehydrated hereditary stomatocytosis. All the dehydrated hereditary stomatocytosis-associated mutations locate at C-terminal half of PIEZO1. Remarkably, we find that all PIEZO1 mutations give rise to mechanically activated currents that inactivate more slowly than wild-type currents. This gain-of-function PIEZO1 phenotype provides insight that helps to explain the increased permeability of cations in red blood cells of dehydrated hereditary stomatocytosis patients. Our findings also suggest a new role for mechanotransduction in red blood cell biology and pathophysiology.
[show abstract][hide abstract] ABSTRACT: HFE, an MHC class Ib molecule that controls iron metabolism, can be directly targeted by cytotoxic TCR αβ T lymphocytes. Transgenic DBA/2 mice expressing, in a Rag 2 KO context, an αβ TCR that directly recognizes mouse HFE (mHFE) were created to further explore the interface of HFE with the immune system. TCR-transgenic mHfe WT mice deleted mHFE-reactive T cells in the thymus, but a fraction of reprogrammed cells were able to escape deletion. In contrast, TCR-transgenic mice deprived of mHFE molecules (mHfe KO mice) or expressing a C282→Y mutated mHFE molecule - the most frequent mutation associated with human hereditary hemochromatosis - positively selected mHFE-reactive CD8(+) T lymphocytes and were not tolerant toward mHFE. By engrafting these mice with DBA/2 WT (mHFE(+)) skin, it was established, as suspected on the basis of similar engraftments performed on DBA/2 mHfe KO mice, that mHFE behaves as an autonomous skin-associated histocompatibility antigen, even for mHFE-C282→Y mutated mice. By contrast, infusion of DBA/2 mHFE(+) mice with naïve mHFE-reactive transgenic CD8(+) T lymphocytes did not induce GVHD. Thus, tolerance toward HFE in mHfe WT mice can be acquired at either thymic or peripheral levels but is disrupted in mice reproducing human familial hemochromatosis.
European Journal of Immunology 04/2012; 42(4):851-62. · 4.97 Impact Factor
[show abstract][hide abstract] ABSTRACT: A primary HCMV infection or virus reactivation may cause severe disease in hosts with a deficient immune system. The virus can disturb both innate and adaptive immunity by targeting dendritic cell (DC) functions. Monocytes, the precursors of DCs in vivo (MoDCs), are the primary targets of HCMV; they can also harbor latent virus. The DCs generated from infected monocytes (CMV-MoDCs) have an altered phenotype and functional defects. We have shown that CMV-MoDCs do not secrete IL-12 in response to lipopolysaccharide stimulation, cannot ingest dead cells, induce T(H)1 differentiation, or the proliferation of naive allogeneic CD4(+) T cells. We found that the GM-CSF signaling in an entire population of CMV-MoDCs was impaired, although only half of the cells were productively infected, and that IL-6 secretion and suppressors of cytokine signaling 3 induction contributed to this bystander effect. We also showed that MoDCs derived ex vivo from monocytes of viremic patients had the same altered phenotype as CMV-MoDCs, including decreased STAT5 phosphorylation, indicating defective GM-CSF signaling. We have thus described a new mechanism of HCMV-induced immunosupression, indicated how infection may disturb both GM-CSF-dependent physiologic processes and proposed GM-CSF-based therapeutic approaches.
[show abstract][hide abstract] ABSTRACT: The current screening for eligibility of unrelated volunteer marrow donors comprises a complete clinical check-up, a blood CBC and serum protein immunoelectrophoresis. This allows to eliminate acute leukemias, myeloproliferative and myelodysplastic disorders, myelomas and MGUS. To date, the risk of transmission of chronic lymphocytic leukemia (CLL) disease is only evaluated by the clinical evaluation and CBC. We report here the case of a CLL-type MBL disease occurring in a 12-year-old boy after unrelated BMT. Deep biological investigations, as Immunophenotyping, cytogenetic and molecular biology allow us to determine the donor origin of the CLL clone. In 2010, 14.2% donor (105/737) for unrelated hematopoietic stem cell transplantation were over 45y. It is currently estimated (USA) that 1 in 210 men and women will be diagnosed with CLL during their lifetime. Given the long asymptomatic phase of CLL, this raises the case for a detection strategy analog to that used for MGUS and myeloma through serum protein electrophoresis. This case-report, to our knowledge, of a CLL-type MBL unrelated donor-to-recipient transmission through BMT raises ethical and practical questions, such as the proper information about disease transmission risk. The cost-effectiveness of a systematic peripheral blood Immunophenotyping in donors elder than 40y at time of stem cell donation should be evaluated.
European Journal Of Haematology 12/2011; 88(3):269-72. · 2.55 Impact Factor
[show abstract][hide abstract] ABSTRACT: Digestive cryptosporidiosis (DC) can mimic GVHD after allogeneic haematopoietic stem cell transplantation (HSCT), thus requiring a reduction of immunosuppressive drugs and a specific therapy, whereas GVHD requires an intensification of immunosuppression. We systematically searched for cryptosporidiosis by light microscopy, immunochromatography and PCR in HSCT recipients who presented with at least one episode of diarrhoea. Of 115 consecutive patients allografted between July 2006 and November 2008, we analysed stools in 52 of 56 patients meeting these criteria. We identified Cryptosporidium parvum in 5 of the 52 patients (9.6%) at a median of 503 days (range 20-790) after HSCT. In those five patients, the median CD4+ cell and B lymphocyte counts were 60/mm3 (0-234) and 0/mm3 (0-96), respectively. Two patients died of invasive fungal infections. In the other three patients, diarrhoea disappeared after a median of 5 weeks following onset of bitherapy with azithromycine and nitazoxanide; they were still alive 433, 380 and 1179 days after the DC diagnosis. DC is probably under diagnosed after HSCT because it is difficult to detect during the asymptomatic phase. Early bitherapy and reduction of immunosuppression seem efficacious. In our series, DC has a seasonal pattern and is promoted by profound T lymphopenia.
Bone marrow transplantation 06/2011; 46(6):858-62. · 3.00 Impact Factor
[show abstract][hide abstract] ABSTRACT: In the context of CPOE of standardized antineoplastic drugs, the objectives of the present study were to determine the incidence of prescribing medication errors (PME) and to analyse PME related to antineoplastic treatment in university teaching hospitals.
All consecutive prescribing medication orders over 1 year were analysed prospectively. Potential clinical impact was quoted according to the Hatoum scale and risk factors identified with a logistic-regression model.
A total of 14,854 prescriptions were analysed. The PME incidence was estimated at 1.5% [1.3-1.7], i.e. 15 errors per 1000 prescribing medication orders, with a significant or very significant potential clinical impact in 62.9% of cases. Potentially death-threatening events were avoided in 3.7% of cases. Overall, PME incidence related to significant, very significant or vital potential clinical impact was estimated to be 1.0% [0.8-1.2], i.e. 10 errors per 1000 prescribing medication orders. The most common type of error was related to antineoplastic drug dosage (61.0%): inadequate adaptation (43.1%), not taking alarms into account (16.1%), incorrect weight (0.9%), incorrect unit (0.9%). More than 20% of PME are medication errors directly linked to the prescribing medication order (choice of antineoplastic treatment, double-prescribing medication order, forgotten or not validated by a resident or senior physician). Occasional users of the CPOE system and resident physicians were identified as main PME risk factors.
An epidemiologic survey of PME in the context of the use of a partial CPOE has allowed to determine the incidence and epidemiology of PME as well as the potential clinical impact they represent. Two risk factors have emerged that can be considered from an organization and software points of view. Better pharmacist's analysis of prescribing medication order within the CPOE system could possibly minimize duplication of antineoplasic drugs and the vital clinical impact associated with overdosage.
International Journal of Medical Informatics 10/2010; 79(10):699-706. · 2.06 Impact Factor
[show abstract][hide abstract] ABSTRACT: Initial molecular events leading to natural killer lymphocyte (NK) and dendritic cell (DC) interactions are largely unknown. Here, the role of CX3CL1 (fractalkine), a chemokine expressed on mature dendritic cells (mDCs) has been investigated. We show that CX3CL1 promotes NK activation by mDCs. After blocking of CX3CL1 by antibody, no activation occurred but major histocompatibility complex (MHC) class I neutralization restored DC-mediated NK activation, suggesting an interaction between CX3CL1 signaling and the functioning of inhibitory KIR. Then the YTS NK cell line, in which the inhibitory receptor KIR2DL1 had been introduced, was used. The presence of KIR2DL1 did not decrease YTS activation by HLA-Cw4 DC when CX3CL1 was functional. In contrast, CX3CL1 neutralization led to killer cell immunoglobulin-like receptor (KIR) phosphorylation and SHP-1 recruitment in YTS(KIR2DL1) cultured with HLA-Cw4 mDCs. Moreover, CX3CL1 neutralization promoted dispersion of lipid rafts and the formation of a multiprotein complex required for cytoskeletal rearrangements in YTS NK cells. These findings point to a pivotal role of CX3CL1 in the activation of resting NK cells by mature DCs.
[show abstract][hide abstract] ABSTRACT: CD4(+)CD25(+) regulatory T lymphocytes (Treg) have been initially shown to prevent organ-specific autoimmunity. It is now accepted that Treg homeostasis depends in part on the peripheral conversion of naïve CD4(+)CD25(-) T cells. This conversion implicates acquisition of the Treg-specific markers, forkhead winged helix protein 3 (Foxp3), after CD28 costimulation. Because natural killer cells (NK) are critical for efficient cytotoxic T-cell priming and TH1 polarization, we investigated their role in Foxp3 induction in CD4(+) T lymphocytes.
Human CD4(+)CD25(-) T lymphocytes were activated in vitro by CD28 costimulation in the presence of interleukin-2-activated NK. Three days after initial activation, Foxp3 protein and RNA expression were determined by flow cytometry and reverse transcription polymerase chain reaction. In vivo influence of activated NK on Foxp3 expression was studied in an adoptive transfer model of CD45.2(+) CD4(+)CD25(-) lymphocytes into CD45.1(+) mice.
Interleukin-2-activated NK decreased Treg conversion of adoptively transferred murine CD4(+)CD25(-) T cells in vivo. Likewise, human-activated NK, but not resting NK, decreased CD28-driven Foxp3 expression in CD4(+)CD25(-) T lymphocytes, while at the same time increasing proliferation and interferon-gamma (IFN-gamma) production. Neutralization of IFN-gamma partially restored Treg conversion and prevented TH1 polarization after CD28 costimulation.
The current study suggests that activated NK interfere with CD28-mediated Foxp3 expression in CD4(+)CD25(-) T lymphocytes. Our experiments further underline a molecular interaction between IFN-gamma and Foxp3 downstream of CD28 signaling. Together, these results demonstrate that activated NK play a critical role at the initiation step of immune responses by modulating peripheral Treg differentiation.
[show abstract][hide abstract] ABSTRACT: Extranodal thyroid lymphomatous involvement is rare in childhood. We report here 2 children, 1 with vertical transmission-acquired human immunodeficiency virus (HIV), presenting with lymphomatous infiltration of the thyroid gland at diagnosis. One child had infra-clinical endocrine impairment and both responded well to chemotherapy. Although the cases are too scarce to be affirmative, thyroid gland involvement doesn't seem to alter the good prognosis of childhood Burkitt's lymphoma. The third child's cancer in frequency is Non-Hodgkin Lymphomas. Presenting as the initial AIDS event in 1 patient, this case report also highlights the need to systematically propose antiretroviral therapy in vertically HIV infected children.
Archives de Pédiatrie 02/2006; 13(1):38-40. · 0.36 Impact Factor
[show abstract][hide abstract] ABSTRACT: Competitive immunoglobulin/T-cell receptor polymerase-chain reaction (PCR) analysis with fluorescent detection is a rapid, cheap and reproducible method for quantifying minimal residual disease (MRD), which is well adapted to the recognition of high-risk childhood acute lymphoblastic leukemia (ALL). We aimed at defining whether flow cytometry (FC) techniques can bypass limitations of PCR for MRD determination.
We analyzed 140 remission samples from 91 patients using both competitive PCR amplification of antigen-receptor genes and four-color FC identification of leukemia immunophenotype. These methods were chosen with the aim of detecting at least 0.1% blasts.
MRD was measured using both PCR and FC methods in 123 samples and the two methods provided concordant results in 119 of them (97%). Moreover, three out of the four discordant results appeared minor since MRD was detectable by both methods, but at different levels. In 12 of 13 samples from nine patients, mainly infants with early CD10- and/or t(4;11) B-cell ALL and children with immature T-cell ALL, MRD could be determined using FC whereas PCR failed. Conversely, FC methods were unfeasible due to inappropriate leukemia immunophenotype in three additional children (including two with T-cell ALL) for whom PCR successfully provided MRD results.
The MRD results provided by FC techniques were highly concordant with those of competitive PCR. Moreover, the applicability of FC appeared higher in certain ALL subsets, although the appropriateness of this technique in terms of outcome prediction remains to be demonstrated.
[show abstract][hide abstract] ABSTRACT: Positive galactomannan (GM) anti-genemias are included as a microbiological item in the diagnosis of probable or possible invasive aspergillosis (IA). Because false-positive GM results frequently occur, at least two positive results on two different samples are required. Waiting for clinical specimens can delay the initiation of treatment. As an alternative, we wondered whether detection of circulating Aspergillus DNA on the first positive GM serum sample could aid in diagnosing IA. Therefore, we retrospectively screened the first GM-positive serum samples from 29 patients from our hematology unit for Aspergillus DNA using real-time PCR. We compared the real-time PCR results with the final classification of proven, probable, and possible IA according to consensual criteria. No clear correlation between PCR results and the classification with the medical files could be shown. However, a positive PCR result was associated with a poor prognosis (Fisher's test; P=0.01). Our preliminary data suggest that a positive PCR result could indicate a more advanced stage of the disease. Therefore, concomitant positive PCR and GM results may justify the initiation of antifungal therapy in neutropenic patients. In contrast, a negative PCR on the first positive GM sample may argue for postponing costly antifungal administration until additional arguments for the diagnosis of IA are presented.
Journal of Clinical Microbiology 11/2005; 43(10):5097-101. · 4.07 Impact Factor
[show abstract][hide abstract] ABSTRACT: Le Cidofovir, nouvelle drogue anti-virale, a été initialement utilisé chez les adultes présentant un SIDA avec infection à Cytomegalovirus. Plus récemment, le Cidofovir a fait preuve d’une efficacité contre l’adenovirus. Nous rapportons deux cas de douleurs sévères des membres inférieurs survenues chez des enfants recevant du Cidofovir.
Andréa, 9 ans a reçu une greffe de sang placentaire pour une leucémie aigüe myéloblastique en deuxième rémission complète. À 5 mois post-greffe, survenue d’une infection à Adenovirus avec atteinte digestive sévère Un traitement par Cidofovir à la dose de 5 mg/kg à J1, J8 puis toutes les deux semaines est entrepris. Au décours (24 h) de la troisième cure de Cidofovir sont apparues des douleurs très intenses au niveau des jambes sans signes locaux. Les douleurs à type de brûlures et/ou de déchirement mal soulagées par la morphine n’étaient pas augmentées par la palpation des masses musculaires. Le traitement par morphiniques n’étant pas suffisant, l’adjonction de clonazepam et d’amitryptiline ont permis un contrôle imparfait des douleurs d’une durée de 3 jours qui se sont répétées après la dose suivante de Cidofovir.
Laurine, 4 ans, a présenté 5 mois après une greffe de sang placentaire, une infection cutanée à herpes virus résistants aux anti-viraux courants. Un traitement par Cidofovir a également suivi lors de la 4e cure de douleurs violentes des deux cuisses avec palpation musculaire douloureuse. Devant l’efficacité incomplète de la nalbuphine, l’adjonction de clonazepam per os a permis une amélioration de la qualité de l’analgésie.
Malgré l’utilisation et la présence chez ces deux enfants d’un certain nombre de traitements concomitants au Cidofovir, nous suspectons fortement cette drogue, encore peu utilisée chez l’enfant, d’avoir contribué à ces tableaux douloureux complexes semblant associer une atteinte nociceptive et neuropathique.