41 research outputs found

    Quelle rĂ©gulation pour l’arrĂȘt d’un protocole de recherche clinique de thĂ©rapie gĂ©nique somatique ? État des lieux auprĂšs des cliniciens-chercheurs europĂ©ens

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    Depuis 2002, le dĂ©bat sur les risques associĂ©s Ă  la thĂ©rapie gĂ©nique est initiĂ© suite Ă  l’annonce que deux enfants inclus dans un essai thĂ©rapeutique impliquant une thĂ©rapie gĂ©nique ont dĂ©veloppĂ© des effets indĂ©sirables important. En Janvier 2005, le dĂ©bat sur les risques reprit suite Ă  l’interruption du protocole sur les enfants bulle du Pr Fischer Ă  l’hĂŽpital Necker de Paris. Nous avons donc Ă©tudiĂ© le processus impliquĂ© ainsi que la rĂ©flexion Ă©thique associĂ©e aux dĂ©cisions d’arrĂȘt de protocole de recherche. Notre travail a Ă©tĂ© menĂ© par une Ă©quipe pluridisciplinaire combinant chercheurs en santĂ©, gĂ©nĂ©ticiens et Ă©thiciens. Nous avons Ă©tudiĂ© la participation des chercheurs, des patients, des institutions officielles, des comitĂ©s d’éthique ainsi que des associations de patients dans le processus de dĂ©cision d’interruption d’un protocole de recherche.Nous avons Ă©galement analysĂ© les critĂšres jugĂ©s les plus pertinents dans l’arrĂȘt d’un protocole de recherche. Enfin nous avons analysĂ© le point de vue des personnes directement impliquĂ©es dans la thĂ©rapie gĂ©nique au moyen d’un questionnaire. Toutes les personnes contactĂ©es ont prĂ©sentĂ© un poster de recherche au congrĂšs de la SociĂ©tĂ© EuropĂ©enne de ThĂ©rapie GĂ©nique. 62 personnes d’autant d’équipes de recherche diffĂ©rentes, de 17 pays, sur les 350 contactĂ©s ont rĂ©pondu. Selon eux, la dĂ©cision d’arrĂȘt d’un protocole de recherche doit ĂȘtre prise suite Ă  une consultation des chercheurs, des patients, du ministĂšre de tutelle, d’une agence nationale de rĂ©gulation ou d’un comitĂ© d’éthique ; la lĂ©gitimitĂ© Ă©tant accordĂ©e Ă  des dĂ©cisions prises en commun par les chercheurs, les patients et les comitĂ©s d’éthique. Les incidents sĂ©rieux et de façon plus surprenante, les incidents moins graves sont jugĂ©s comme Ă©tant des critĂšres suffisants pour interrompre un essai. Nous avons fini par analyser les consĂ©quences Ă©thiques, telles que balance bĂ©nĂ©fice/risque, processus de rĂ©gulation ou responsabilitĂ©, de ces critĂšres sur l’arrĂȘt d’un protocole de recherche.In 2002, the debate on the risks of gene therapy was initiated following the annoucement that two children included in a clinical trial developed serious adverse effects. In January 2005, the debate was reignited following the interruption of the “bubble kids protocol” at the HĂŽpital Necker in Paris. We have thus investigated the ethical stakes involved in decisions to stop protocols. This work was carried out by a multidisciplinary team combining ethics researchers and geneticists. We studied the specific participation of researchers, patients, official institution, ethics committees and patient associations in the processes that can lead to an interruption of trial.We also analysed the criterion judged most relevant for halting a trial. Finally, we analyzed the perspective of the actors implicated directly in the provision of gene therapy, by means of a questionnaire. All the individuals contacted had presented a scientific poster at the European Society of Gene Therapy. 62 out of 350 persons, from 17 countries, responded to our questionnaire. According to these respondants, decisions to stop a trial should be taken after consultation with researchers, patients, the ministry, national agencies or ethics committees. Legitimacy was accorded to joint decision-making by researchers, patients and committees. Serious incidents, and surprisingly less serious incidents, clearly emerge as criterion for stopping a trial. We conclude by analyzing the ethical consequences, such as risk/benefit ratios, regulatory processes and responsibility, associated with these criterions and decisions to stop a trial

    Combined Immunodeficiency With Late-Onset Progressive Hypogammaglobulinemia and Normal B Cell Count in a Patient With RAG2 Deficiency

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    Proteins expressed by recombination activating genes 1 and 2 (RAG1/2) are essential in the process of V(D)J recombination that leads to generation of the T and B cell repertoires. Clinical and immunological phenotypes of patients with RAG deficiencies correlate well to the degree of impaired RAG activity and this has been expanding to variants of combined immunodeficiency (CID) or even milder antibody deficiency syndromes. Pathogenic variants that severely impair recombinase activity of RAG1/2 determine a severe combined immunodeficiency (SCID) phenotype, whereas hypomorphic variants result in leaky (partial) SCID and other immunodeficiencies. We report a patient with novel pathogenic compound heterozygous RAG2 variants that result in a CID phenotype with two distinctive characteristics: late-onset progressive hypogammaglobulinemia and highly elevated B cell count. In addition, the patient had early onset of infections, T cell lymphopenia and expansion of lymphocytes after exposure to herpes family viruses. This case highlights the importance of considering pathogenic RAG variants among patients with preserved B cell count and CID phenotype

    Identification of CD4−CD8− Double-Negative Natural Killer T Cell Precursors in the Thymus

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    BACKGROUND: It is well known that CD1d-restricted Valpha14 invariant natural killer T (NKT) cells are derived from cells in the CD4(+)CD8(+) double-positive (DP) population in the thymus. However, the developmental progression of NKT cells in the earlier stages remains unclear, and the possible existence of NKT cell presursors in the earlier stages than DP stage remains to be tested. PRINCIPAL FINDINGS: Here, we demonstrate that NKT cell precursors that express invariant Valpha14-Jalpha18 transcripts but devoid of surface expression of the invariant Valpha14 receptor are present in the late CD4(-)CD8(-) double-negative (DN)4 stage and have the potential to generate mature NKT cells in both in vivo and in vitro experimental conditions. Moreover, the DN4 population in CD1d knock-out (CD1dKO) mice was similar to those with an NKT cell potential in wild-type (WT) C57BL/6 (B6) mice, but failed to develop into NKT cells in vitro. However, these precursors could develop into NKT cells when co-cultured with normal thymocytes or in an in vivo experimental setting, indicating that functional NKT cell precursors are present in CD1dKO mice. CONCLUSIONS: Together, these results demonstrate that thymic DN4 fraction contains NKT cell precursors. Our findings provide new insights into the early development of NKT cells prior to surface expression of the invariant Valpha14 antigen receptor and suggest the possible alternative developmental pathway of NKT cells

    Analyse moléculaire de patients présentant un déficit immunitaire combiné avec microcéphalie associé à un défaut général de la réparation de l'ADN

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    Analyse moléculaire de patients présentant un déficit immunitaire combiné avec microcéphalie associé à un défaut général de la réparation de l'ADN. Les cassures double-brin d'ADN (dsb) formées au cours de la recombinaison V(D)J sont modifiées et ligaturées par des facteurs généraux de la réparation de l'ADN du non homologous end joining (NHEJ), avec six protéines connues impliquées:Ku70/Ku86/DNAPKcs, Artemis et Xrcc4/Lig4. Dans un premier temps, nous avons montré que des mutations hypomorphes de Lig4 peuvent entraßner un déficit immunitaire sévÚre avec radiosensibilité (RS-SCID) chez l'homme, caractérisé par un défaut de la recombinaison V(D)J in vitro, qui est complémenté par la forme sauvage de Lig4. DeuxiÚmement, nous avons identifié un nouveau facteur V(D)J/NHEJ grùce à l'analyse fonctionnelle et génétique d'un groupe de patients présentant un phénotype similaire à celui des patients déficients e Lig4. Nous avons nommé ce facteur Cernunnos, dont le gÚne codant est muté chez tous les patients analysés. Le défaut du NHEJ observé dans les cellules de ces patients est complémenté par la forme sauvage de Cernunnos.PARIS5-BU-Necker : Fermée (751152101) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

    V(D)J recombination defects

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    Distinct effects of DNA-PKcs and Artemis inactivation on signal joint formation in vivo.

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    International audienceThe assembly of functional immune receptor genes via V(D)J recombination in developing lymphocytes generates DNA double-stranded breaks intermediates that are repaired by non-homologous end joining (NHEJ). This repair pathway requires the sequential recruitment and activation onto coding and signal DNA ends of several proteins, including the DNA-dependent protein kinase and the nuclease Artemis. Artemis activity, triggered by the DNA-dependent protein kinase, is necessary to process the genes hairpin-sealed coding ends but appears dispensable for the ligation of the reciprocal phosphorylated, blunt-ended signal ends into a signal joint. The DNA-dependent protein kinase is however present on signal ends and could potentially recruit and activate Artemis during signal joint formation. To determine whether Artemis plays a role during the resolution of signal ends during V(D)J recombination, we analyzed the structure of signal joints generated in developing thymocytes during the rearrangement of T cell receptor genes in wild type mice and mice mutated for NHEJ factors. These joints exhibit junctional diversity resulting from N nucleotide polymerization by the terminal nucleotidyl transferase and nucleotide loss from one or both of the signal ends before they are ligated. Our results show that Artemis participates in the repair of signal ends in vivo. Furthermore, our results also show that while the DNA-dependent protein kinase complex protects signal ends from processing, including deletions, Artemis seems on the opposite to promote their accessibility to modifying enzymes. In addition, these data suggest that Artemis might be the nuclease responsible for nucleotide loss from signal ends during the repair process
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