Involvement of p21 in mitotic exit after paclitaxel treatment in MCF-7 breast adenocarcinoma cell line

International audienceIt has been shown recently that expression of p21 is enhanced by paclitaxel. This cytotoxic compound induces mitotic spindle damage resulting in blockade of the mitotic cell cycle associated or not with apoptotic cell death. In the present study, we showed that, in MCF-7 cells, paclitaxel induced accumulation of p21 in cells with a G2/M DNA content, corresponding to cells either in abnormal mitosis or in an interphase-like state (decondensed chromatin) with multiple nuclei. In MCF-7 cells, the increase in p21 was subsequent to the mitotic arrest and was associated with the exit from abnormal mitosis leading to formation of cells with micronuclei. In this cell line, we noted a relationship between the elevation of p21 expression and the inhibition of p34cdc2 activity. High levels of p21 protein were also found to be associated with inactive p34cdc2/cyclin B protein complex after treatment with paclitaxel. Treatment with p21 antisense oligonucleotide partially blocked induction of p21 expression by paclitaxel and significantly reduced survival of MCF-7 cells exposed to this agent. In NIH-OVCAR-3 cells, which are deficient in basal and paclitaxel-induced p21 expression, paclitaxel led to a prolonged activation of p34cdc2 and a delayed mitotic exit associated with apoptotic cell death. These observations suggest that p21 is not required for the mitotic arrest in response to paclitaxel, but argue in favor of a role for this inhibitor in facilitating the exit from abnormal mitosis. This effectively enhances cell survival after paclitaxel-induced spindle damage

Use of human reconstructed epidermis to analyze the regulation of -defensin hBD-1, hBD-2, and hBD-3 expression in response to LPS

International audienceDefensins have been identified as key elements of innate immunity against microbial infections. In the present study, human beta-defensin-2 (hBD-2) mRNA and peptide expression were evaluated by RT-PCR and Western blotting in normal human keratinocytes, in function of their stage of differentiation. In proliferating, non-differentiating keratinocytes generated in serum-free, low-calcium medium, a very low hBD-2 mRNA expression was found. A significantly higher expression was detected in high-calcium cultivated keratinocytes grown either as monolayers or as multilayers under submerged conditions. In an air-liquid interface culture of keratinocytes, allowing epidermis to be reconstructed, hBD-2 mRNA expression level was significantly higher than in the other conditions and displayed inter-individual variability as observed in native epidermis. The peptide was detected only in reconstructed epidermis. These results indicate that hBD-2 gene expression in normal human keratinocytes is dependent upon their stage of differentiation. The level of expression of hBD-1 mRNA was lower and that of hBD-3 was higher than that of hBD-2 in reconstructed epidermis. Exposure of reconstructed epidermis to bacterial lipopolysaccharide (LPS) resulted in an average 4-fold increase in hBD-2 mRNA 18 h after challenge, but not of hBD-1 and hBD-3 gene expression. These results show the selective regulation of hBD-2-encoding gene in an organotypic epidermal model, in response to LPS. They also provide evidence that in vitro reconstructed epidermis represents a useful model for studying regulation of expression of beta-defensins after skin challenge with pathogenic microorganisms in conditions as close as possible to the in vivo situation

Rituximab for prevention of delayed hemolytic transfusion reaction in sickle cell disease

International audienceDelayed hemolytic transfusion reaction (DHTR), a life-threatening transfusion complication in sickle cell disease (SCD), is characterized by a marked hemoglobin drop with destruction of both transfused and autologous red blood cells (RBCs) and exacerbation of SCD symptoms. One mechanism of RBCs destruction is auto-antibody production secondary to transfusion. As rituximab specifically targets circulating B cells, we thought that it could be beneficial in preventing this immune-mediated transfusion complication. We report the case of a SCD patient who previously experienced DHTR with auto-antibodies and who needed a new transfusion. DHTR recurrence was successfully prevented by rituximab administration prior transfusion, supporting the safe use of rituximab to prevent DHTR in SCD patients as a second line approach when other measures failed

Étude d’une cohorte de 206 patients drépanocytaires adultes transfusés : immunisation, risque transfusionnel et ressources en concentrés globulaires

International audienceBackground: Prevention of hemolytic transfusion reactions depends upon our capacity to prevent allo-immunization and conflicts between antigens of transfused red blood cells and antibodies produced by the recipient. In this study, we show that to secure transfusion of sickle cell disease patients, it is necessary to take into account their immunohematologic characteristics in the organization of transfusion.Methods and results: Immunohematological data of 206 chronically transfused patients have been collected as well as phenotypes of transfused units. In order to prevent allo-immunization against C and E antigens for patients typed D+C-E-c+e+ (56%), 26% of the transfused units were D-C-E-c+e+. We found that 47% of the patients had a history of allo-immunization, whereas only 15% produced an antibody the day of inclusion in the study. The non-detectable antibodies were frequently known as dangerous for transfusion. Finally, this study shows the frequency of anti-D in D+ patients and anti-C in C+ patients, pointing out the question of partial antigens.Conclusion: To insure optimal transfusion safety for sickle cell disease patients, three points have to be improved: blood donation within the Afro-Caribbean community living in France, access to history of immuno-hematological data, detection of variant antigens, especially within the RH blood system.But de l’étude. – La prévention des hémolyses post-transfusionnelles chez les drépanocytaires est conditionnée par notre capacité à prévenir l’allo-immunisation et les conflits antigène–anticorps. Cette étude montre l’importance de mettre en place une organisation transfusionnelle adaptée au profil immunohématologique particulier des drépanocytaires pour leur garantir une sécurité transfusionnelle optimale.Méthodes et résultats. – Les données immunohématologiques de 206 adultes drépanocytaires transfusés en dehors de l’urgence ont été analysées, ainsi que le phénotype des concentrés globulaires (CGR) délivrés. Cinquante-quatre pour cent des patients ont un phénotype D+CEc+e+. Pour prévenir l’allo-immunisation anti-C et anti-E, 26 % de CGR DCEc+e+ ont été transfusés à ces patients D+. Quarante-sept pour cent des patients ont un historique d’allo-immunisation, alors que seulement 15 % ont une recherche d’agglutinines irrégulières positive le jour de l’inclusion, les anticorps non décelables étant souvent dangereux. Enfin, cette étude montre la fréquence importante d’anti-D chez les sujets D+ et d’anti-C chez les sujets C+, posant la question du caractère partiel des antigènes D et C.Conclusion. – Pour une sécurité transfusionnelle optimale des patients drépanocytaires et une meilleure adéquation entre phénotypes des receveurs et phénotypes des CGR disponibles, trois points dans l’organisation transfusionnelle doivent être améliorés : la promotion du don au sein des populations afro-antillaises doit être renforcée pour disposer de CGR D+CEc+e+ et éviter d’utiliser la ressource limitée de CGR DCEc+e+ ; les données immunohématologiques des patients doivent être accessibles aux prescripteurs et transfuseurs, afin d’éviter les accidents immuno-hémolytiques par restimulation ; enfin, la recherche par biologie moléculaire des antigènes variants d’intérêt transfusionnel doit être mise en place chez les donneurs et receveurs afro-antillais

The use of rituximab to prevent severe delayed haemolytic transfusion reaction in immunized patients with sickle cell disease

International audienceBackground: Delayed haemolytic transfusion reaction (DHTR) is mainly caused by an immune response to transfused red blood cells (RBCs). Immunized patients have a high risk of producing antibodies in response to further transfusion. Controlling the immune response to RBCs is therefore a major goal in sickle cell disease (SCD).Study design: We report an observational study of eight alloimmunized SCD patients with history of severe DHTR who were treated with rituximab before a new transfusion to prevent further immunization and DHTR.Results: Five patients showed a good clinical outcome following transfusion preceded by preemptive treatment with rituximab. The remaining patients presented mild DHTR. In all patients, the results of post-transfusion screening tests were identical to those of pretransfusion tests; no newly formed antibodies were detected.Conclusion: These cases suggest that rituximab prevents at least occurrence of newly formed antibodies in high responders and minimizes the risk of severe DHTR. This study confirms that DHTR is complex in SCD and does not rely only on the classical antigens/antibodies conflict. Considering potentially serious adverse effect of rituximab, this treatment should be considered cautiously, and only when transfusion is absolutely necessary in patients with history of severe DHTR linked to immunization

L’hémolyse post-transfusionnelle retardée : à propos de 3 patients drépanocytaires

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Probability of TCD-Normalization in the “Drepagreffe” Trial Comparing Transplantation to Chronic Transfusion in Sickle Cell Anemia Children with Abnormal-Transcranial Doppler Is Associated with Lower Ang-2 and BDNF Plasma Levels.

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