Approche critique du diagnostic biologique des "lupus anticoagulant" à l'Hôpital Henri Mondor

PARIS-BIUP (751062107) / SudocSudocFranceF

Approche originale de thérapie génique pour l'hémophilie B

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Bruising in a Depressed Patient: Self-Inflicted or Adverse Effect of Antidepressants?

International audienc

Glycoprotein Ibalpha promoter drives megakaryocytic lineage-restricted expression after hematopoietic stem cell transduction using a self-inactivating lentiviral vector.

International audienceMegakaryocytic (MK) lineage is an attractive target for cell/gene therapy approaches, aiming at correcting platelet protein deficiencies. However, MK cells are short-lived cells, and their permanent modification requires modification of hematopoietic stem cells with an integrative vector such as a lentiviral vector. Glycoprotein (Gp) IIb promoter, the most studied among the MK regulatory sequences, is also active in stem cells. To strictly limit transgene expression to the MK lineage after transduction of human CD34(+) hematopoietic cells with a lentiviral vector, we looked for a promoter activated later during MK differentiation. Human cord blood, bone marrow, and peripheral-blood mobilized CD34(+) cells were transduced with a human immunodeficiency virus-derived self-inactivating lentiviral vector encoding the green fluorescent protein (GFP) under the transcriptional control of GpIbalpha, GpIIb, or EF1alpha gene regulatory sequences. Both GpIbalpha and GpIIb promoters restricted GFP expression (analyzed by flow cytometry and immunoelectron microscopy) in MK cells among the maturing progeny of transduced cells. However, only the GpIbalpha promoter was strictly MK-specific, whereas GpIIb promoter was leaky in immature progenitor cells not yet engaged in MK cell lineage differentiation. We thus demonstrate the pertinence of using a 328-base-pair fragment of the human GpIbalpha gene regulatory sequence, in the context of a lentiviral vector, to tightly restrict transgene expression to the MK lineage after transduction of human CD34(+) hematopoietic cells. Disclosure of potential conflicts of interest is found at the end of this article

FVIII dosages in persons with haemophilia A treated with extended half‐life products: From local biology to optimized patient management

International audienceManagement of persons with haemophilia A (PwHA) has advanced considerably with the introduction of modified recombinant factor VIII (FVIII) with extended half-life (EHL). Monitoring such products may be challenging due to discrepancies between FVIII levels measured by chronometric one-stage assays (OSAs) and chromogenicstage assays (CSAs). CSA is considered to be the most consistent method because it is used for potency labelling of FVIII concentrates according to the European Pharmacopeia recommendations

Analysis of 65 pregnancies in 34 women with five different forms of inherited platelet function disorders

This study evaluated 65 pregnancies in 34 women with five different inherited platelet function disorders. Gestation was similar to that of the general population. Severe bleeds requiring blood transfusions were observed in 50% of deliveries in Glanzmann thrombasthenia (GT), but not in the patients with delta storage pool disease, Hermansky-Pudlak syndrome, P2Y12 defect or defect of thromboxane A2 receptor. Of note, severe haemorrhage also occurred in women with GT who had received prophylactic platelet transfusions, suggesting that better preventive treatments are required. Diagnosis and degree of spontaneous bleeding tendency before pregnancy were reliable parameters to predict the delivery-related bleeding risk

Apoptotic Platelet Events Are Not Observed in Severe von Willebrand Disease-Type 2B Mutation p.V1316M

<div><p>Thrombocytopenia and increased platelet clearance observed in von Willebrand disease-type 2B (VWD-2B) may be explained by platelet apoptosis triggered by the constitutive binding of VWF to its receptor, glycoprotein Ib (GPIb). Apoptosis was assessed in platelets from two patients with a severe VWD-2B mutation VWF/p.V1316M and from mice transiently expressing VWF/p.V1316M. We now report that the VWD-2B mutation VWF/p.V1316M which binds spontaneously to its receptor GPIbα does not induce apoptosis. In 2 unrelated patients (P1 and P2) exhibiting different VWF plasma levels (70% and 36%, respectively, compared with normal pooled human plasma given as 100%), inner transmembrane depolarization of mitochondria, characteristic of apoptotic events was undetectable in platelets, whether washed or in whole blood. No or a moderate phosphatidyl serine (PS) exposure as measured by annexin-V staining was observed for P1 and P2, respectively. Expression of pro-apoptotic proteins Bak and Bax, and caspase-3 activity were similar to control platelets. In the VWD-2B mouse model expressing high levels of mVWF/p.V1316M (423%), similar to what is found in inflammatory pathologies, no significant difference was observed between mice expressing mVWF/WT and mVWF/p.V1316M. These results strongly argue against apoptosis as a mechanism for the thrombocytopenia of severe VWD-2B exhibiting the VWF/p.V1316M mutation.</p></div

Expression of apoptotic proteins in mice expressing VWF/pV1316M.

<p>For each experiment, 12 mice were used: 2 injected with pLIVE, 4 injected with WT and 6 injected with VWF/p.V1316M mice. Washed murine platelets (2.5 x10⁸ platelets/mL) were lysed and then an equal number of platelets was loaded. Apoptotic proteins were assessed by immunoblotting with anti-Bak, anti-Bax and anti-14-3-3ζ antibodies. Data are expressed as the ratio of apoptotic protein expression versus 14-3-3ζ expression. Then, the ratio for mVWF/p.V1316M or WT mVWF was compared with the corresponding ratio for control pLIVE plasmid (100%) and results are presented as means ± SEM from three independent experiments.</p

PS exposure in patients with VWD-type 2B.

<p>PS exposure was determined <b>A)</b> in washed platelets and <b>B)</b> in blood pretreated or not with ABT-737 (10 μM) for 60 minutes at 37°C. Then washed platelets and blood were further incubated with annexin V-PE and an anti-CD41a-FITC (a platelet marker for blood) for 15 minutes and then analyzed by flow cytometry. Results are expressed as a percentage of positive Annexin V. Means ± SEM from three independent experiments are shown, **p = 1.4x10^-3 and ***p = 5.8x10^-8 (paired Student t test).</p